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Handbook Of Energy Audit
 9789339221331

Table of contents :
Title
Contents
1. Global and Indian Energy Scenarios
1.1 Energy Conservation
1.2 Energy Audit
1.3 Energy Scenario of India
1.3.1 Coal
1.3.2 Oil and natural gas
1.3.3 Electricity
1.3.4 Hydro energy
1.3.5 Nuclear energy
1.4 Present Nonrenewable Energy Scenario
1.4.1 Wind energy
1.4.2 Biomass power generation
1.4.3 Small hydropower plant
1.4.4 Solar power
1.4.5 Off-grid renewable power
1.4.6 Decentralized system
1.5 Present Energy Consumption
1.5.1 Gross domestic product (GDP)
1.5.2 Energy intensity
1.5.3 Current energy production and pricing
1.6 Energy Security
1.7 Energy Strategy for the Future
1.7.1 National electricity policy, 2005
1.7.2 Tariff policy, 2006
1.7.4 The electricity act, 2003
1.8 Clean Development Mechanism
1.8.1 Objectives of the clean development mechanism
1.8.2 Applications of the clean development mechanism
Descriptive Questions
Short-answer Questions
Multiple-Choice Questions
Glossary of Energy Terms
2. Types of Energy Audits and Energy-Audit Methodology 22–
2.2 Company/Building Where Energy Audit is Performed
2.3 Energy-Audit Methodology
Phase I Audit Preparation
Step 2: Scope of audit
Step 3: Selection of audit team
Step 4: Audit plan
Step 5: Audit checklist
Step 6: Initial walkthrough audit
Step 7: Collecting energy bills and data
Step 8: Conducting preliminary analysis
Phase II Execution
Step 1: Data inventory and measurement
Step 2: Analyzing energy-use patterns
Step 3: Benchmarking and comparative analysis
Step 4: Identifying energy-saving potential
Phase III Reporting
Step 1: Preparing audit report with recommendations
Step 2: Preparing the action plan
Step 3: Implementing the action plan
2.4 Financial Analysis
2.4.1 Simple payback
2.4.2 Return on investment
2.4.3 Net present value and internal rate of return
2.4.4 Lifecycle cost method
2.5 Sensitivity Analysis
2.6 Project-Financing Options
2.6.3 Equity and bonds
2.7 Energy Monitoring and Targeting
2.7.1 Regression analysis
2.7.2 Cumulative sum (CUSUM)
2.7.3 Targeting
Descriptive Questions
Short-answer Questions
Multiple-Choice Questions
3. Survey Instrumentation
3.1 Electrical Measurement
3.1.1 Multimeter
3.1.2 Power-factor meter
3.1.3 Power analyzer
3.2 Thermal Measurement
3.2.1 Temperature measurement
Air-leakage measurement
3.2.2 Pressure measurement
3.2.3 Flow measurement
3.2.4 Velocity measurement
Orsat apparatus
Fyrite gas analyzer
Portable combustion analyzer
3.3 Light Measurement
3.4 Speed Measurement
3.5 Data Logger and Data-Acquisition System
Data acquisition
3.6 Thermal Basics
Descriptive Questions
Short-answer Questions
Multiple-Choice Questions
4. Energy Audit of Boilers
4.1.1 Fire-tube boiler
4.1.2 Packaged boiler
4.1.3 Water-tube boiler
4.1.5 Pulverized coal boiler
4.1.6 Fluidized-bed boiler (FBC)
4.2 Parts of a Boiler
4.3.1 Direct method
4.3.2 Indirect method
4.4.1 How to measure excess air
4.4.2 Excess air control
4.5 Energy-Saving Methods
4.5.1 Keeping the boiler surface clean from soot deposition
4.5.2 Waste-heat utilization
4.5.4 Effective boiler loading
4.5.5 Exhaust-gas recirculation
4.5.7 Make-up water and feedwater management
Methods to monitor scale formation
Water-treatment methods
4.5.9 Heat loss in de-aeration
Checklist
Thumb Rules
Descriptive Questions
Short-answer Questions
Multiple-Choice Questions
5. Energy Audit of Furnaces
5.1 Parts of a Furnace
Heating system
Refractory
Loading unloading system
Heat exchanger
Instrumentation and control
Batch furnace
Continuous furnace
Flow-through
Conveyer belt
Rotary kilns
Walking beam
Vertical shaft
5.3 Energy-Saving Measures in Furnaces
5.3.1 Heat generation
5.3.2 Air preheating
5.3.3 Oxygen enrichment
5.3.4 Heat transfer
5.3.5 Heat loss through outer surface and openings
5.3.6 Heat recovery
5.3.7 Use of advanced technology
Energy saving in an arc furnace
5.3.9 Changing power source from AC to DC
5.3.10 Use of continuous casting machine
5.3.11 Use of a high-frequency melting furnace
Use of pulverized coal instead of coking coal
Installation of top-gas-recovery turbine
Dry quenching of coke
Case Study
Objective
Technical detail
Outcome
Checklist
Descriptive Questions
Short-answer Questions
Multiple-Choice Questions
6. Energy Audit of a Power Plant
6.1 Indian Power-Plant Scenario
6.2 How is Energy Audit of Power Plants Helpful?
6.3 Types of Power Plants
6.3.1 Thermal power plant
6.3.2 Combined-cycle power plant
6.4 Energy Audit of Power Plant
6.4.1 Use of supercritical pressure boilers
Discussion
6.4.2 Improving condenser performance by condenser-tube cleaning
Discussion
6.4.3 Waste-heat recovery
Discussion
Waste-heat-driven steam turbine
Waste-heat recovery in LNG fuelled HRSG system
6.4.4 Improvement in performance of air preheater
Discussion
6.4.5 Sootblowing optimization
Discussion
Discussion
6.4.7 Reduction in auxiliary power consumption
Discussion
Boiler feedwater system
Fans and draft systems
Coal-handling plant
Coal milling/grinding system
Cooling-water system
Water treatment plant and water pumping
Compressed air system
6.4.8 Gas-turbine inlet air cooling
Discussion
Descriptive Questions
Short-answer Questions
Multiple-Choice Questions
7. Energy Audit of Steam-Distribution Systems
7.1 Why is Steam Used as a Heating Fluid?
7.2 Steam Basics
7.3 How to Estimate Requirement of Steam?
7.4 Steam-Distribution System
7.5 Pressure
7.6 Piping
7.7 Losses in Steam-Distribution Systems
7.7.1 Quantify and estimate of steam leak
7.7.2 Insulation on steam-distribution lines and condensate return lines
7.7.3 Flash steam
7.7.4 Condensate recovery
7.7.5 Pipe size
7.8 Energy-Conservation Methods
7.8.1 Use of two different-capacity steam generators for two different pressure requirements
7.8.2 Install turbine between high-pressure steam generator and end use in new set-up or replace pressure-reducing valve with turbine in existing set-up
7.8.3 Use steam-turbine drive instead of electric motor
7.8.4 Cover open vessels containing hot water
7.8.6 Use steam at lowest possible pressure
7.8.7 Use low-pressure waste steam to run vapour-absorption refrigeration system
7.8.8 Enhance heat transfer
7.8.9 Proper selection of steam trap
7.8.10 Use of vapour recompression
7.8.11 Use of dry steam
Checklist
Housekeeping Checklist
Thumb Rules
Descriptive Questions
Short-answer Questions
Numerical Problems
Multiple-Choice Questions
8. Compressed Air System
8.2 Types of Compressors
8.2.1 Positive-displacement compressors
8.2.3 Reciprocating air compressors (1 CFM to 6300 CFM)
Thermodynamics of a reciprocating air compressor
8.2.4 Rotary screw compressors (30 CFM to 3000 CFM)
8.2.5 Vane compressor (40 CFM to 800 CFM)
8.2.6 Centrifugal compressors (400 CFM to 15000 CFM)
8.3 Compressed Air-System Layout
8.4 Energy-Saving Potential in a Compressed-Air System
8.4.1 Analyze compressed-air quality and quantity need
8.4.2 Inappropriate use of compressed air
8.4.3 Leakage in a compressed-air system
Leak-detection methods
8.4.4 Pressure drop in a compressed-air system
8.4.5 Controls of a compressed-air system
Individual compressor controls
Modulating or throttling control
Multiple compressor control
8.4.6 Compressed-air storage
8.4.7 Regular maintenance
8.4.8 Heat recovery in compressed-air systems
Checklist
Thumb Rules
Descriptive Questions
Short-answer Questions
Fill in the Blanks
Multiple-Choice Questions
9. Energy Audit of HVAC Systems
9.1 Introduction to HVAC
9.2 Components of an Air-Conditioning System
Outside air damper
Mixing chamber
Filter
Heating and cooling coils
Fan
9.3 Types of Air-Conditioning Systems
9.4 Human Comfort Zone and Psychrometry
Psychrometry
Dry-bulb temperature
Wet-bulb temperature
Relative humidity
9.5 Vapour-Compression Refrigeration Cycle
9.5.1 Performance of vapour-compression refrigeration cycle
9.5.2 Parameters affecting the performance of vapour-compression refrigeration cycle
9.5.3 Parts of a vapour-compression refrigeration cycle
Condenser
Expansion valve
Evaporator
Refrigerant
9.6 Energy Use Indices
9.7 Impact of Refrigerants on Environment and Global Warming
9.8 Energy-Saving Measures in HVAC
9.8.1 CAV vs VAV
CAVs with terminal reheat systems
CAV systems with terminal reheat in interior spaces and perimeter induction or fan-coil units
All-air induction systems with perimeter reheat
CAV double-duct systems
Variable air volume (VAV) systems
9.8.2 Optimize ventilation air
9.8.3 Use of variable-speed drive
9.8.4 Replace existing chiller
9.8.5 Use of boost-up systems or alternative systems
9.8.6 Duct-leakage repair
9.8.7 Heat-recovery wheel
9.8.8 Exhaust fans
9.8.9 Reducing cooling load
9.8.10 Operate the system at higher evaporator temperature and lower condenser temperature
9.8.13 Use of a vapour-absorption refrigeration system
9.8.14 Replace vapour-compression-based cooling with evaporative cooling
9.8.15 Use of alternative refrigerant
9.8.16 Encourage green building concept in india
9.8.17 Promote use of BMS and DDC systems
9.8.18 Thermal energy storage (TES) based air-conditioning system
Advantages of a VRF system
9.9 Star Rating and Labelling by BEE
Checklist
Thumb Rules
Descriptive Questions
Short-answer Questions
Fill in the Blanks
Multiple-Choice Questions
10. Electrical-Load Management
10.1 Electrical Basics
10.2 Electrical Load Management
10.2.1 Electricity and its cost
10.2.2 Load-management techniques
Use of storage system
Change in technology
Decentralized power generation
Reduce electricity use during peak hours
Use of demand controllers
10.3 Variable-Frequency Drive
Use of variable-frequency drive
10.4 Harmonics and Its Effects
10.4.1 Cause and effect of harmonics
10.4.2 How to control harmonics
10.5 Electricity Tariff
PART A: Residencial premises (at low and medium voltage)
PART B: Tariffs for high-tension consumers contracted for 100 kVA and above (3.3 kV and above, 3-phase, 50 cycles/second) and extra high tension
Power-factor penalty
Power-factor rebate
10.6 Power Factor
10.6.1 How to improve power factor
10.7 Transmission and Distribution Losses
Why do technical losses occur in transmission and distribution of electricity?
Methods to reduce technical losses
Why do commercial losses occur in transmission and distribution of electricity?
Methods to Reduce Commercial Losses
Short-answer Questions
Fill in the Blanks
11. Energy Audit of Motors
11.2 Parameters Related to Motors
11.4 Energy Conservation in Motors
11.4.1 Appropriate loading of motor
Direct electrical measurement
Slip measurement
Amperage readings
11.4.2 Selection of the right motor
11.4.3 Assessing motor and drive-system operating conditions
Motor rewinding
Power-factor improvement
Power quality
Effect of harmonics on an induction motor
Variable-frequency drives
11.4.4 Optimization of the complete system
Adopting MEPS (minimum energy performance standard)
Change the connections
Use of soft starters
Use of more copper
Reduce idle and redundant operations
Misalignment
Regular inspection and maintenance
11.5 BEE Star Rating and Labelling
Thumb Rules
Abbreviations
Descriptive Questions
Short-answer Questions
Justify the Following Statements
Fill in the Blanks
Multiple-Choice Questions
12. Energy Audit of Pumps, Blowers, and Cooling Towers
Part A: Pumps
12.A.1 Centrifugal Pump
12.A.2 Positive-Displacement Pump
12.A.4 Flow Control and Pump Losses
12.A.5 Series and Parallel Arrangement of Pumps
12.A.6 Selection of Pump
12.A.7 Energy-Saving Potential in a Pump
12.A.7.1 Correct sizing of pumps
12.A.7.2 Trim impeller of an oversized pump
12.A.7.3 Keeping the pump clean and well maintained
12.A.7.4 Select right-size motor for a pump
12.A.7.6 Use of multiple-speed pumps
12.A.7.7 Check pipe layout
12.A.8 Steps to Design New Pumping System
Step 1 Identify requirement
Step 2 Design the pumping system
Thumb Rules
Part B: Fans and Blowers
12.B.1.1 Centrifugal fans
12.B.1.2 Axial fans
12.B.2 Fan Laws and Curves
12.B.3 Power Consumption by a Fan
12.B.4 Energy-Saving Potential in Fans
12.B.4.1 Fan selection
12.B.4.2 Maintenance of a fan
12.B.4.3 Identify and rectify leakage
12.B.4.5 Use of variable-frequency driven fans
12.B.4.6 Reduce pressure loss in the duct by proper duct design
12.B.4.7 Fans in series and parallel arrangements
Part C: Cooling Tower
12.C.2 Performance of a Cooling Tower
12.C.3 Components of a Cooling Tower
12.C.3.1 Packing materials
12.C.3.2 Hot-water distribution system
12.C.3.3 Cooled water basin
12.C.3.4 Fans and controllers
12.C.3.5 Louvers and drift eliminators
12.C.3.6 Tower material of a cooling tower
12.C.4.1 Sizing of the cooling tower
12.C.4.2 Reduce water loss
12.C.4.3 Reduce blowdown
12.C.4.4 Maintenance, monitoring, and optimization
12.C.4.5 Minimizing corrosion and scale
12.C.4.6 Variable frequency drive for fans
Thumb rules
Checklist for pumps, fans, and cooling towers
Descriptive questions
Short-answer questions
Numerical problem
Fill in the blanks
Justify the following statements
Multiple-choice questions
13. Energy Audit of Lighting Systems
13.1 Fundamentals of Lighting
13.2 Different Lighting Systems
13.2.1 Incandescent lamp
13.2.3 Fluorescent lamps
13.2.4 High-intensity discharge (HID) lamps
Mercury vapour
Metal halide
High-pressure sodium (HPS)
Low-pressure sodium (LPS)
Light-emitting diodes (LEDs)
13.3 Ballasts
Magnetic ballast
Standard core-and-coil
Electronic ballasts
HID ballast
13.4 Fixtures (Luminaries)
13.6 Lenses and Louvres
13.7 Lighting Control Systems
13.7.1 Timers (time-scheduling control system)
13.7.2 Dimmer
13.7.3 Photocell
13.7.4 Infrared presence sensors
13.7.5 Ultrasonic presence sensor
13.8 Lighting System Audit
Step 1 Observation
Step 2 Output measurement
Step 3 Input measurement
Step 4 Compilation of results
Step 5 ILER analysis
13.9 Energy-Saving Opportunities
13.9.1 Daylighting
13.9.2 Task lighting
13.9.3 Solar-powered lighting
13.9.4 Group re-lamping
13.9.5 De-lamping
13.9.6 Daylight saving
Use of metal halide lamps
Use of high-pressure sodium-vapour lamps
Use of light emitting diode (LED) lamps
Use of electronic ballast
Bachat lamp yojana
Checklist
Descriptive Questions
Short-Answer Questions
Numerical Problem
14. Energy Audit Applied to Buildings
14.1 Energy-Saving Measures in New Buildings
14.1.2 Envelop heat gain
14.1.3 Equipment selection
14.1.4 Insulation
14.1.5 Cool roof
14.1.6 Improving air-tightness
14.1.8 Co-ordination between designer and developer
14.1.9 HVAC sizing and number of lightings
14.1.11 Adopt solar water heating
14.1.12 Promote use of decentralized power plants
14.1.13 Energy-saving measures in existing buildings
14.2 Water Audit
Water-audit methodology
Part A: Planning and preparation
Part C: Data collection
Part D: Analysis
14.3 How to Audit Your Home?
14.4 General Energy-saving Tips Applicable to New as Well as Existing Buildings
Descriptive Questions
Short-answer Questions
Fill in the Blanks
Multiple-Choice Questions
15. Thermal Insulation and Refractory Materials
15.2 Heat Transfer Mechanism in Thermal Insulation
15.2.1 Conduction
15.2.2 Convection
15.2.3 Radiation
15.2.4 Thermal conductivity
15.2.5 R-value of insulation
15.3.1 Fibrous insulation
15.3.2 Cellular insulation
15.3.3 Granular insulation
15.4 Different Forms of Insulation Materials Available In The Market
15.5 Selection of Insulating Material
15.6 Calculation of Insulation Thickness
15.7 Economic Thickness of Insulation
15.8 Refractory Material
15.9 Properties of Refractory Materials
Melting point
Porosity
Bulk density
Pyrometric cone equivalent (PCE)
Thermal expansion
Thermal conductivity
Cold crushing strength
15.10 Commonly Used Refractory Materials
Fireclay bricks
High-alumina refractory
Silica bricks
Magnesite refractory
Dolomite, chromite, zirconia, and monolithic refractory
15.11 Selection of Refractory Material
15.12 How to Improve Life of a Refractory Material
Checklist
Descriptive Questions
Short-Answer Questions
Fill in the Blanks
Multiple-Choice Questions
16. Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation
16.1 Basics of a Heat Exchanger
16.2 Heat-Exchanger Applications
Preheater
Radiator
Evaporator and condenser
Steam condenser
16.3 Performance of a Heat Exchanger
16.3.1 Log mean temperature difference (LMTD)
16.3.2 Effectiveness — NTU method
16.3.3 Pinch analysis
16.4 Fouling
Sedimentation fouling
Inverse solubility fouling
Chemical reaction fouling
Corrosion-product fouling
Biological fouling
Prevention and removal of fouling
16.5 Tubular Exchanger Manufacturers Association
16.6 Selection of a Heat Exchanger
Heat-exchanger tube inserts
Use of deformed tubes
16.8 Waste-Heat-Recovery Equipment
16.8.1 Recuperator (gas-to-gas or gas-to-air heat exchanger)
16.8.2 Rotary wheel (heat wheel)
16.8.3 Heat-pipe heat exchanger
16.8.4 Waste-heat boiler
16.8.5 Thermoelectric generator
16.8.6 Heat-recovery steam generator (HRSG)
16.9 Hurdles in the Waste-Heat-Recovery Process
16.10 Co-Generation
16.11 Types of Co-Generation
16.11.1 Internal-combustion-engine based co-generation
16.11.2 Steam-turbine-based co-generation
16.11.3 Gas-turbine-based co-generation
16.11.4 Microturbine-based co-generation
16.11.5 Fuel-cell-based cogeneration
16.12 Feasibility of a Combined Cycle
Energy-saving tips in heat exchangers
Descriptive Questions
Short-Answer Questions
Numerical Problem
Fill in the Blanks
Multiple-Choice Questions
17. Computer Software and Formats for Energy Audit
17.1 Name of Software: Energy Lens
by Doe for Calculating Home and Building Energy Use
17.3 Name of Software: Iheat by Hancock
17.4 Name of Software: Matrix 4 Utility Accounting System
17.6 Name of Software: 3E Plus (for Insulation Thickness Calculator)
17.7 Name of Software: Pump-Flo (to Select Pump)
17.8 Name of Software: Eco2.0 To Calculate Energy Saving Due to Variable Speed Drive Instead of Conventional Drives.
17.9 Name of Software: Honeywell VFD, Energy-Saving and Payback Calculator
17.10 Name of Software: Canmost—Motor Selection Tool
17.11 Name of Software: Motormaster+
Annexure I
Annexure II
References
Index

Citation preview

Handbook of Energy Audit

Handbook of Energy Audit

Sonal Desai Professor and Head Mechanical Department C K Pithawala College of Engineering and Technology (CKPCET) Surat, Gujarat

McGraw Hill Education (India) Private Limited NEW DELHI New Delhi New York St Louis San Francisco Auckland Bogotá Caracas Kuala Lumpur Lisbon London Madrid Mexico City Milan Montreal San Juan Santiago Singapore Sydney Tokyo Toronto

Published by McGraw Hill Education (India) Private Limited, P-24, Green Park Extension, New Delhi 110 016. Handbook of Energy Audit Copyright © 2015, McGraw Hill Education (India) Private Limited. No part of this publication may be reproduced or distributed in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise or stored in a database or retrieval system without the prior written permission of the publishers. The program listings (if any) may be entered, stored and executed in a computer system, but they may not be reproduced for publication. This edition can be exported from India only by the publishers, McGraw Hill Education (India) Private Limited. Print Edition ISBN (13): 978-93-392-2133-1 ISBN (10): 93-392-2133-8 E-book Edition ISBN (13): 978-93-392-2134-8 ISBN (10): 93-392-2134-6 Managing Director: Kaushik Bellani Head—Products (Higher Education and Professional): Vibha Mahajan Assistant Sponsoring Editor: Koyel Ghosh Development Editor: Deepika Jain Manager—Production Systems: Satinder S Baveja Assistant Manager—Editorial Services: Sohini Mukherjee Production Manager: Sohan Gaur Senior Publishing Manager: Shalini Jha Editorial Executive: Harsha Singh General Manager—Production: Rajender P Ghansela Manager—Production: Reji Kumar Information contained in this work has been obtained by McGraw Hill Education (India), from sources believed to be reliable. However, neither McGraw Hill Education (India) nor its authors guarantee the accuracy or completeness of any information published herein, and neither McGraw Hill Education (India) nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that McGraw Hill Education (India) and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. Typeset at Script Makers, 19, A1-B, DDA Market, Paschim Vihar, New Delhi 110 063, and text printed at Cover Printer: Cover Designer: Kapil Gupta

Foreword Handbook on Energy Audit by Dr Sonal Desai is a very useful book for practicing energy auditors, energy-conservation professionals, and students of power engineering, energy management, and energy conservation. A subject necessarily to be made mandatory in energy curriculum, this book will help

3. Industry/Building owners getting their premises audited 4. UG and PG students specializing in Energy Conservation and Management The subjects of Energy Conservation and Energy Saving are even more critical in these times of global debate to mitigate Climate Change (CC). New power plants, which are globally operating on coal as fuel with almost 60% of thermal power plants generating energy after coal consumption, thereby pose a challenge of ever-increasing carbon emissions and consequential Global Warming. Hence, steps for energy conservation and energy saving will result in Virtual Power Plants (VPPs). Making investments in new coal-based thermal power plants costs `60 million per megawatt as of construction data available in 2014–15. Whereas, deploying energy conservation and energy`10-20 million per megawatt at the most. Also, the gestation period for a new power plant is between 5-6 years, whereas energy conservation and energy-saving measures can be deployed in a year’s time, making this virtual power effective, quick, economical, and devoid of additional carbon emissions and associated maladies that cause damage to the environment. I am sure the author has done justice to the topic and presented the subject in the most lucid manner. Therefore, the book will serve both beginners and practicing professionals who have deep interest in energy conservation and energy saving. My Best Wishes for the Success of this Book! A Gopalakrishnan Iyer Editor-in-Chief & Publisher, ENERTIA President, ENERTIA Foundation President, Renewable Energy Promotion Association (REPA) President, Alliance for Small & Medium Enterprises of India (ASMEI)

Preface a reference book for engineers appearing for energy audit examinations, and as a handy tool for practicing energy auditors. This book contains the right blend of energy-conservation fundamentals and applications in the practicing energy world. The author has long felt that current books on this subject are academic-oriented and geared towards theoretical knowledge rather than practical approach towards energy audits. Energy is an active and rapidly developing parameter in everyone’s life, and even in the industry. It is closely related to living standards of people, economic growth of the country, and the outdoor environment. The need for effective energy management is increasing day-by-day due to continuous changes in the energy marketplace, and to conserve nature. This book will guide the user in learning about energy audit processes by helping identify and prioritize energy-conservation opportunities which are plenty and untapped. The book also provides sample calculations at various places to estimate energy saving for a suggested change or retrofit in the system. Equations and use of instruments are brought together and the outcome is presented as a systematic approach of audit, supported by detailed collection of technical material. The author hopes this book will be a hands-on help to professionals aiming or practicing energy audits. At the same time, the author would like to receive any constructive suggestions that readers may wish to pass on at [email protected] Let’s all make a better world that optimizes energy potential and conserves nature as well! Sonal Desai Publisher’s Note All our books are developed with a lot of love and sincere hard work. If you would like to make a suggestion or share your views, write in to us at [email protected], mentioning the title and author’s name in the subject line.

Contents Foreword Preface 1.

Global and Indian Energy Scenarios 1.1 Energy Conservation 1 1.2 Energy Audit 2 1.3 Energy Scenario of India 3 1.3.1 Coal 3 1.3.2 Oil and natural gas 5 1.3.3 Electricity 5 1.3.4 Hydro energy 6 1.3.5 Nuclear energy 7 1.4 Present Nonrenewable Energy Scenario 7 1.4.1 Wind energy 8 1.4.2 Biomass power generation 9 1.4.3 Small hydropower plant 10 1.4.4 Solar power 11 1.4.5 Off-grid renewable power 11 1.4.6 Decentralized system 11 1.5 Present Energy Consumption 13 1.5.1 Gross domestic product (GDP) 13 1.5.2 Energy intensity 13 1.5.3 Current energy production and pricing 13 1.6 Energy Security 15 1.7 Energy Strategy for the Future 16 1.7.1 National electricity policy, 2005 16 1.7.2 Tariff policy, 2006 16 1.7.4 The electricity act, 2003 17 1.8 Clean Development Mechanism 18 1.8.1 Objectives of the clean development mechanism 18 1.8.2 Applications of the clean development mechanism 18 Descriptive Questions 18 Short-answer Questions 19 Multiple-Choice Questions 19 Glossary of Energy Terms 20

v vii 1–21

x Contents

2.

Types of Energy Audits and Energy-Audit Methodology 2.2 Company/Building Where Energy Audit is Performed 2.3 Energy-Audit Methodology 23 Phase I Audit Preparation Step 2: Step 3: Step 4: Step 5: Step 6: Step 7: Step 8:

22–47 23

24

Scope of audit 25 Selection of audit team 26 Audit plan 26 Audit checklist 27 Initial walkthrough audit 27 Collecting energy bills and data 27 Conducting preliminary analysis 27

Phase II Execution 29 Step 1: Data inventory and measurement 29 Step 2: Analyzing energy-use patterns 31 Step 3: Benchmarking and comparative analysis 31 Step 4: Identifying energy-saving potential 32

2.4

2.5 2.6

Phase III Reporting 33 Step 1: Preparing audit report with recommendations 33 Step 2: Preparing the action plan 34 Step 3: Implementing the action plan 35 Financial Analysis 35 2.4.1 Simple payback 36 2.4.2 Return on investment 37 2.4.3 Net present value and internal rate of return 37 2.4.4 Lifecycle cost method 39 Sensitivity Analysis 40 Project-Financing Options 40

2.6.3 Equity and bonds 41 2.7 Energy Monitoring and Targeting 41 2.7.1 Regression analysis 42 2.7.2 Cumulative sum (CUSUM) 42 2.7.3 Targeting 45 Descriptive Questions 46 Short-answer Questions 46 Multiple-Choice Questions 46

Contents

3.

Survey Instrumentation

xi

48–59

3.1 Electrical Measurement 48 3.1.1 Multimeter 48 3.1.2 Power-factor meter 48 3.1.3 Power analyzer 48 3.2 Thermal Measurement 49 3.2.1 Temperature measurement 49 Air-leakage measurement 50 3.2.2 Pressure measurement 51 3.2.3 Flow measurement 51 3.2.4 Velocity measurement 52 Orsat apparatus 52 Fyrite gas analyzer 53 Portable combustion analyzer 53 3.3 Light Measurement 53 3.4 Speed Measurement 54 3.5 Data Logger and Data-Acquisition System 54 Data acquisition 54 3.6 Thermal Basics 55 Descriptive Questions 57 Short-answer Questions 58 Multiple-Choice Questions 58 4.

Energy Audit of Boilers

4.2

4.1.1 4.1.2 4.1.3

Fire-tube boiler 61 Packaged boiler 61 Water-tube boiler 63

4.1.5 4.1.6

Pulverized coal boiler 66 Fluidized-bed boiler (FBC) 67

Parts of a Boiler 69 4.3.1 4.3.2

Direct method 69 Indirect method 70

4.4.1 4.4.2

How to measure excess air 76 Excess air control 76

60–85

xii Contents

4.5 Energy-Saving Methods 77 4.5.1 Keeping the boiler surface clean from soot deposition 77 4.5.2 Waste-heat utilization 78 4.5.4 4.5.5

Effective boiler loading 79 Exhaust-gas recirculation 80

4.5.7 Make-up water and feedwater management 80 Methods to monitor scale formation 81 Water-treatment methods 81 4.5.9

Heat loss in de-aeration 82

Checklist 83 Thumb Rules 83 Descriptive Questions 84 Short-answer Questions 84 Multiple-Choice Questions 84 5.

Energy Audit of Furnaces 5.1 Parts of a Furnace 86 Heating system 86 Refractory 86 Loading unloading system 86 Heat exchanger 86 Instrumentation and control 86 Batch furnace 87 Continuous furnace 87 Flow-through 89 Conveyer belt 89 Rotary kilns 89 Walking beam 89 Vertical shaft 90 5.3 Energy-Saving Measures in Furnaces 90 5.3.1 Heat generation 90 5.3.2 Air preheating 90 5.3.3 Oxygen enrichment 91 5.3.4 Heat transfer 92 5.3.5 Heat loss through outer surface and openings 92 5.3.6 Heat recovery 93

86–101

Contents

5.3.7

xiii

Use of advanced technology 93

Energy saving in an arc furnace 93 5.3.9 Changing power source from AC to DC 94 5.3.10 Use of continuous casting machine 95 5.3.11 Use of a high-frequency melting furnace 95 Use of pulverized coal instead of coking coal 95 Installation of top-gas-recovery turbine 95 Dry quenching of coke 95 Case Study 99 Objective 99 Technical detail 99 Outcome 100 Checklist 100 Descriptive Questions 100 Short-answer Questions 100 Multiple-Choice Questions 101 6.

Energy Audit of a Power Plant 6.1 Indian Power-Plant Scenario 102 6.2 How is Energy Audit of Power Plants Helpful? 102 6.3 Types of Power Plants 102 6.3.1 Thermal power plant 102 6.3.2 Combined-cycle power plant 107 6.4 Energy Audit of Power Plant 108 6.4.1 Use of supercritical pressure boilers 109 Discussion 109 6.4.2 Improving condenser performance by condenser-tube cleaning 109 Discussion 109 6.4.3 Waste-heat recovery 110 Discussion 110 Waste-heat-driven steam turbine 110 Waste-heat recovery in LNG fuelled HRSG system 111 6.4.4 Improvement in performance of air preheater 112 Discussion

112

102–121

xiv Contents

6.4.5

Sootblowing optimization 114

Discussion

114

Discussion 114 6.4.7 Reduction in auxiliary power consumption 115 Discussion 115 Boiler feedwater system 115 Fans and draft systems 116 Coal-handling plant 117 Coal milling/grinding system 117 Cooling-water system 117 Water treatment plant and water pumping 117 Compressed air system 117 6.4.8 Gas-turbine inlet air cooling 118 Discussion 118 Descriptive Questions 119 Short-answer Questions 119 Multiple-Choice Questions 119 7.

Energy Audit of Steam-Distribution Systems 7.1 7.2 7.3 7.4 7.5 7.6 7.7

122–142

Why is Steam Used as a Heating Fluid? 122 Steam Basics 123 How to Estimate Requirement of Steam? 124 Steam-Distribution System 125 Pressure 126 Piping 127 Losses in Steam-Distribution Systems 128 7.7.1 Quantify and estimate of steam leak 128 7.7.2 Insulation on steam-distribution lines and condensate return lines 129 7.7.3 Flash steam 131 7.7.4 Condensate recovery 132 7.7.5 Pipe size 133 7.8 Energy-Conservation Methods 134 7.8.1 Use of two different-capacity steam generators for two different pressure requirements 134 7.8.2 Install turbine between high-pressure steam generator and end use in new set-up or replace pressure-reducing valve with turbine in existing set-up 134

Contents

7.8.3 7.8.4

xv

Use steam-turbine drive instead of electric motor 134 Cover open vessels containing hot water 134

7.8.6 7.8.7

Use steam at lowest possible pressure 135 Use low-pressure waste steam to run vapour-absorption refrigeration system 135 7.8.8 Enhance heat transfer 135 7.8.9 Proper selection of steam trap 135 7.8.10 Use of vapour recompression 136 7.8.11 Use of dry steam 136 Checklist 139 Housekeeping Checklist 139 140 Thumb Rules 140 Descriptive Questions 140 Short-answer Questions 140 Numerical Problems 141 Multiple-Choice Questions 141 8.

Compressed Air System 8.2 Types of Compressors 145 8.2.1 Positive-displacement compressors 145 8.2.3 Reciprocating air compressors (1 CFM to 6300 CFM) 145 Thermodynamics of a reciprocating air compressor 147 8.2.4 Rotary screw compressors (30 CFM to 3000 CFM) 147 8.2.5 Vane compressor (40 CFM to 800 CFM) 148 8.2.6 Centrifugal compressors (400 CFM to 15000 CFM) 149 8.3 Compressed Air-System Layout 149 8.4 Energy-Saving Potential in a Compressed-Air System 150 8.4.1 Analyze compressed-air quality and quantity need 150 8.4.2 Inappropriate use of compressed air 151 8.4.3 Leakage in a compressed-air system 151 Leak-detection methods 152 8.4.4 Pressure drop in a compressed-air system 152 8.4.5 Controls of a compressed-air system 153 Individual compressor controls 153 Modulating or throttling control 153 Multiple compressor control 153 8.4.6 Compressed-air storage 154

143–158

xvi Contents

8.4.7 Regular maintenance 154 8.4.8 Heat recovery in compressed-air systems 155 Checklist 155 Thumb Rules 156 Descriptive Questions 156 Short-answer Questions 156 Fill in the Blanks 157 Multiple-Choice Questions 157 9.

Energy Audit of HVAC Systems 9.1 9.2

9.3 9.4

9.5

9.6 9.7 9.8

159–192

Introduction to HVAC 159 Components of an Air-Conditioning System 160 Outside air damper 160 Mixing chamber 160 Filter 160 Heating and cooling coils 160 Fan 160 Types of Air-Conditioning Systems 160 Human Comfort Zone and Psychrometry 163 Psychrometry 164 Dry-bulb temperature 164 Wet-bulb temperature 164 Relative humidity 164 Vapour-Compression Refrigeration Cycle 164 9.5.1 Performance of vapour-compression refrigeration cycle 165 9.5.2 Parameters affecting the performance of vapour-compression refrigeration cycle 166 9.5.3 Parts of a vapour-compression refrigeration cycle 167 Condenser 168 Expansion valve 168 Evaporator 169 Refrigerant 169 Energy Use Indices 169 Impact of Refrigerants on Environment and Global Warming 170 Energy-Saving Measures in HVAC 171 9.8.1 CAV vs VAV 171 CAVs with terminal reheat systems 171 CAV systems with terminal reheat in interior spaces and perimeter induction or fan-coil units 171

Contents

xvii

All-air induction systems with perimeter reheat 171 CAV double-duct systems 172 Variable air volume (VAV) systems 172 9.8.2 Optimize ventilation air 172 9.8.3 Use of variable-speed drive 173 9.8.4 Replace existing chiller 175 9.8.5 Use of boost-up systems or alternative systems 176 9.8.6 Duct-leakage repair 176 9.8.7 Heat-recovery wheel 176 9.8.8 Exhaust fans 177 9.8.9 Reducing cooling load 177 9.8.10 Operate the system at higher evaporator temperature and lower condenser temperature 178

9.8.13 Use of a vapour-absorption refrigeration system 180 9.8.14 Replace vapour-compression-based cooling with evaporative cooling 181 9.8.15 Use of alternative refrigerant 182 9.8.16 Encourage green building concept in india 183 9.8.17 Promote use of BMS and DDC systems 184 9.8.18 Thermal energy storage (TES) based air-conditioning system 184 Advantages of a VRF system 186 9.9 Star Rating and Labelling by BEE 187 Checklist 188 Thumb Rules 189 Descriptive Questions 189 Short-answer Questions 189 Fill in the Blanks 190 Multiple-Choice Questions 190 10.

Electrical-Load Management 10.1 10.2

Electrical Basics 193 Electrical Load Management 194 10.2.1 Electricity and its cost 195 10.2.2 Load-management techniques 196 Use of storage system 196 Change in technology 196 Decentralized power generation 197 Reduce electricity use during peak hours 197 Use of demand controllers 197

193–207

xviii Contents

10.3

Variable-Frequency Drive 198 Use of variable-frequency drive 199 10.4 Harmonics and Its Effects 200 10.4.1 Cause and effect of harmonics 201 10.4.2 How to control harmonics 201 10.5 Electricity Tariff 201 PART A: Residencial premises (at low and medium voltage) 202 PART B: Tariffs for high-tension consumers contracted for 100 kVA and above (3.3 kV and above, 3-phase, 50 cycles/second) and extra high tension 202 Power-factor penalty 203 Power-factor rebate 203 10.6 Power Factor 203 10.6.1 How to improve power factor 204 10.7 Transmission and Distribution Losses 205 Why do technical losses occur in transmission and distribution of electricity? 205 Methods to reduce technical losses 205 Why do commercial losses occur in transmission and distribution of electricity? 206 Methods to Reduce Commercial Losses 206 Short-answer Questions 207 Fill in the Blanks 207 11.

Energy Audit of Motors 11.2

Parameters Related to Motors 211

11.4 Energy Conservation in Motors 214 11.4.1 Appropriate loading of motor 214 Direct electrical measurement 214 Slip measurement 215 Amperage readings 215 11.4.2 Selection of the right motor 216 11.4.3 Assessing motor and drive-system operating conditions 217 Motor rewinding 217 Power-factor improvement 218 Power quality 218 Effect of harmonics on an induction motor 219 Variable-frequency drives 220

208–232

Contents

xix

11.4.4 Optimization of the complete system 220 Adopting MEPS (minimum energy performance standard) 220 Change the connections 221 Use of soft starters 221 Use of more copper 221 Reduce idle and redundant operations 221 Misalignment 222 Regular inspection and maintenance 222 222

11.5 BEE Star Rating and Labelling 229 Thumb Rules 229 Abbreviations 230 Descriptive Questions 230 Short-answer Questions 230 Justify the Following Statements 231 Fill in the Blanks 231 Multiple-Choice Questions 231 12.

Energy Audit of Pumps, Blowers, and Cooling Towers Part A: Pumps 233 12.A.1 Centrifugal Pump 234 12.A.2 Positive-Displacement Pump

234

12.A.4 Flow Control and Pump Losses 240 12.A.5 Series and Parallel Arrangement of Pumps 241 12.A.6 Selection of Pump 242 12.A.7 Energy-Saving Potential in a Pump 244 12.A.7.1 Correct sizing of pumps 245 12.A.7.2 Trim impeller of an oversized pump 245 12.A.7.3 Keeping the pump clean and well maintained 246 12.A.7.4 Select right-size motor for a pump 247 12.A.7.6 12.A.7.7

Use of multiple-speed pumps 247 Check pipe layout 248

233–272

xx Contents

12.A.8 Steps to Design New Pumping System 248 Step 1 Identify requirement 248 Step 2 Design the pumping system 249 Thumb Rules Part B:

249 Fans and Blowers 249

12.B.1.1 Centrifugal fans 250 12.B.1.2 Axial fans 251 12.B.2 Fan Laws and Curves 251 12.B.3 Power Consumption by a Fan 256 12.B.4 Energy-Saving Potential in Fans 257 12.B.4.1 Fan selection 257 12.B.4.2 Maintenance of a fan 257 12.B.4.3 Identify and rectify leakage 258 12.B.4.5 Use of variable-frequency driven fans 259 12.B.4.6 Reduce pressure loss in the duct by proper duct design 259 12.B.4.7 Fans in series and parallel arrangements 259 Part C:

Cooling Tower 261

12.C.2 Performance of a Cooling Tower 263 12.C.3 Components of a Cooling Tower 264 12.C.3.1 Packing materials 264 12.C.3.2 Hot-water distribution system 265 12.C.3.3 Cooled water basin 265 12.C.3.4 Fans and controllers 265 12.C.3.5 Louvers and drift eliminators 265 12.C.3.6 Tower material of a cooling tower 265 12.C.4.1 Sizing of the cooling tower 266 12.C.4.2 Reduce water loss 267 12.C.4.3 Reduce blowdown 267 12.C.4.4 Maintenance, monitoring, and optimization 267 12.C.4.5 Minimizing corrosion and scale 268 12.C.4.6 Variable frequency drive for fans 268 Thumb rules 268 Checklist for pumps, fans, and cooling towers 269 Descriptive questions 270

Contents

xxi

Short-answer questions 270 Numerical problem 271 Fill in the blanks 271 Justify the following statements 272 Multiple-choice questions 272 13.

Energy Audit of Lighting Systems 13.1 13.2

Fundamentals of Lighting 273 Different Lighting Systems 275 13.2.1 Incandescent lamp 275

13.2.3 Fluorescent lamps 277 13.2.4 High-intensity discharge (HID) lamps 277 Mercury vapour 277 Metal halide 277 High-pressure sodium (HPS) 278 Low-pressure sodium (LPS) 278 Light-emitting diodes (LEDs) 279 13.3 Ballasts 280 Magnetic ballast 281 Standard core-and-coil 281 Electronic ballasts 281 HID ballast 281 13.4 Fixtures (Luminaries) 281 13.6 13.7

Lenses and Louvres 282 Lighting Control Systems 283 13.7.1 Timers (time-scheduling control system) 283 13.7.2 Dimmer 283 13.7.3 Photocell 283 13.7.4 Infrared presence sensors 284 13.7.5 Ultrasonic presence sensor 284 13.8 Lighting System Audit 284 Step 1 Observation 284 Step 2 Output measurement 285 Step 3 Input measurement 285 Step 4 Compilation of results 285 Step 5 ILER analysis 285 13.9 Energy-Saving Opportunities 286 13.9.1 Daylighting 286

273–294

xxii Contents

13.9.2 13.9.3 13.9.4 13.9.5 13.9.6

Task lighting 287 Solar-powered lighting 287 Group re-lamping 288 De-lamping 288 Daylight saving 288

Use of metal halide lamps 289 Use of high-pressure sodium-vapour lamps 289 Use of light emitting diode (LED) lamps 289 Use of electronic ballast 289

Bachat lamp yojana 290 Checklist 291 Descriptive Questions 292 Short-Answer Questions 292 Numerical Problem 293 14.

Energy Audit Applied to Buildings 14.1

Energy-Saving Measures in New Buildings 296 14.1.2 Envelop heat gain 297 14.1.3 Equipment selection 299 14.1.4 Insulation 300 14.1.5 Cool roof 300 14.1.6 Improving air-tightness 301 14.1.8 14.1.9

Co-ordination between designer and developer 301 HVAC sizing and number of lightings 301

14.1.11 Adopt solar water heating 302 14.1.12 Promote use of decentralized power plants 303 14.1.13 Energy-saving measures in existing buildings 303 14.2 Water Audit 305 Water-audit methodology 305 Part A: Planning and preparation 305 Part C: Data collection 306 Part D: Analysis 306 14.3 How to Audit Your Home? 306

295–309

Contents

xxiii

14.4 General Energy-saving Tips Applicable to New as Well as Existing Buildings 307 Descriptive Questions 308 Short-answer Questions 308 Fill in the Blanks 308 Multiple-Choice Questions 308 15.

Thermal Insulation and Refractory Materials 15.2

Heat Transfer Mechanism in Thermal Insulation 310 15.2.1 Conduction 311 15.2.2 Convection 311 15.2.3 Radiation 311 15.2.4 Thermal conductivity 312 15.2.5 R-value of insulation 313

15.3.1 Fibrous insulation 315 15.3.2 Cellular insulation 317 15.3.3 Granular insulation 317 15.4 Different Forms of Insulation Materials Available In The Market 319 15.5 Selection of Insulating Material 320 15.6 Calculation of Insulation Thickness 320 15.7 Economic Thickness of Insulation 322 15.8 Refractory Material 324 15.9 Properties of Refractory Materials 324 Melting point 324 Porosity 325 Bulk density 325 Pyrometric cone equivalent (PCE) 325 Thermal expansion 325 Thermal conductivity 325 Cold crushing strength 326 15.10 Commonly Used Refractory Materials 326 Fireclay bricks 326 High-alumina refractory 326 Silica bricks 326 Magnesite refractory 326 Dolomite, chromite, zirconia, and monolithic refractory 326 15.11 Selection of Refractory Material 327 15.12 How to Improve Life of a Refractory Material 327

310–330

xxiv Contents

Checklist 328 Descriptive Questions 328 Short-Answer Questions 328 Fill in the Blanks 329 Multiple-Choice Questions 329 16.

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation 16.1 16.2

16.3

16.4

16.5 16.6

Basics of a Heat Exchanger 331 Heat-Exchanger Applications 334 Preheater 334 Radiator 334 Evaporator and condenser 334 Steam condenser 334 Performance of a Heat Exchanger 335 16.3.1 Log mean temperature difference (LMTD) 335 16.3.2 Effectiveness — NTU method 338 16.3.3 Pinch analysis 341 Fouling 343 Sedimentation fouling 343 Inverse solubility fouling 343 Chemical reaction fouling 343 Corrosion-product fouling 343 Biological fouling 343 Prevention and removal of fouling 344 Tubular Exchanger Manufacturers Association 344 Selection of a Heat Exchanger 346 Heat-exchanger tube inserts 346 Use of deformed tubes 347

16.8

Waste-Heat-Recovery Equipment 349 16.8.1 Recuperator (gas-to-gas or gas-to-air heat exchanger) 349 16.8.2 Rotary wheel (heat wheel) 351 16.8.3 Heat-pipe heat exchanger 352 16.8.4 Waste-heat boiler 353 16.8.5 Thermoelectric generator 353 16.8.6 Heat-recovery steam generator (HRSG) 354 16.9 Hurdles in the Waste-Heat-Recovery Process 354

331–361

Contents

xxv

16.10 Co-Generation 355 16.11 Types of Co-Generation 356 16.11.1 Internal-combustion-engine based co-generation 356 16.11.2 Steam-turbine-based co-generation 357 16.11.3 Gas-turbine-based co-generation 358 16.11.4 Microturbine-based co-generation 358 16.11.5 Fuel-cell-based cogeneration 358 16.12 Feasibility of a Combined Cycle 359 Energy-saving tips in heat exchangers 359 Descriptive Questions 360 Short-Answer Questions 360 Numerical Problem 361 Fill in the Blanks 361 Multiple-Choice Questions 361 17.

Computer Software and Formats for Energy Audit 17.1

Name of Software: Energy Lens

362–372

362

by Doe for Calculating Home and Building Energy Use 362 17.3 Name of Software: Iheat by Hancock 363 17.4 Name of Software: Matrix 4 Utility Accounting System 363

17.6 17.7 17.8

Name of Software: 3E Plus (for Insulation Thickness Calculator) 364 Name of Software: Pump-Flo (to Select Pump) 364 Name of Software: Eco2.0 To Calculate Energy Saving Due to Variable Speed Drive Instead of Conventional Drives. 364 17.9 Name of Software: Honeywell VFD, Energy-Saving and Payback Calculator 365 17.10 Name of Software: Canmost—Motor Selection Tool 365 17.11 Name of Software: Motormaster+ 365 Annexure I 373 Annexure II 404 References 419 Index 425

1

Global and Indian Energy Scenarios Energy is fundamental to daily life—whether it is to provide light, charge mobiles to irrigate our crops, or to run commercial or electrical enterprises. It provides



1.1

Table 1.1

ENERGY CONSERVATION

Classification of energy

Primary energy and Secondary energy

Fossil fuels like coal, lignite, oil, natural gas, nuclear, biomass, which are either found or stored in nature, are primary energy. Primary energy when converted to electricity, heat, etc., is known as secondary energy.

Commercial energy and Noncommercial energy

Commercial energy is used by industrial, agricultural, transport, domestic, and commercial users in electricity, coal, or other available petroleum forms. Firewood, cattle dung, agro waste, solar heat, wind etc., are noncommercial energy. As they are not bought at a price, they are often ignored in energy accounting.

Renewable energy and Nonrenewable energy

Inexhaustible sources give renewable energy like wind, sun, geothermal, tidal waves, hydro, etc. They are clean and have minimum impact on the environment. All conventional fuels like coal, oil, gas, etc., are nonrenewable energy.

2 Handbook of Energy Audit



1.2

Table 1.2

ENERGY AUDIT

Distribution of different plants in the Indian energy scenario

Type of plant

Total capacity (MW)

Percentage contribution

Coal

1,34,389

59

Hydro

39,789

17

Renewable

28,184

12

Natural gas

20,381

9

Nuclear

4780

2

Oil

1200

1

Total

2,28,723

1200 1041 1000 800 622 600 400 200

G

Chart 1.1

Source:

Comparison of lifecycle emission

d

14

in

er m th

uc

le a

al

r

ro yd H

rp

v

s as

So la

ur al at

Bi om

ga s

l oa C N

15

17

W

18

eo

39

N

46 0

Tons of CO2 equivalent per GWhr

Source:

Transmission and distribution losses

Global and Indian Energy Scenarios

35.00%

25.00% 20.00% 15.00%

1.3.1

1.3

13.30%

10.00% 5.90%

7.70%

0.00% USA

China

Austrailia

Brazil

India

Transmission and distribution losses in India and abroad

ENERGY SCENARIO OF INDIA

Coal

6.10%

5.00%

Chart 1.2



29.20%

30.00%

3

4 Handbook of Energy Audit

Major coal field TAJIKISTAN

Main coal-fired power plant Main steel plant Jammu and Kashmir

AFGHANISTAN

Coal-importing port

Himachal Pradesh Punjab Uttarakhand PAKISTAN

CHINA Arunachal Pradesh

Haryana Delhi

Sikkim BHUTAN Assam Nagaland Meghalaya Uttar Pradesh Bihar Manipur Rajasthan BANGLADESH 2 3 Tripura 1 Mizoram West 4 Bengal Jharkhand Kolkata Madhya Pradesh MYANMAR Gujarat 5 Haldia Chhattisgarh 6 Paradip Odisha 7 Maharashtra Mumbai 8 Visakhapatnam NEPAL

INDIA

Arabian sea

Goa

Hyderabad Andhra Pradesh

Bay of Bengal

Karnataka Neyvoli (lignite)

Ennore Chennai

Tamil Nadu Kerala Tuticorin

Major coal fields SRI LANKA

Indian Ocean 0

Km 250 500 Figure 1.1

1. Raniganj 2. Jharia 3. East Bokaro & west Bokaro 4. Singrauli 5. Pench-Kanhan, Tawa Valley 6. Talcher 7. Chanda-wardha 8. Godavari Valley

Indian coal map (See color figure)

Global and Indian Energy Scenarios

CO2 30000 t/day COAL 12000 t/day

SO2 + NO2 680 t/day

1000 MW POWER STATION

FURNACE OIL 101 m3/day

920 MW GT

WATER 98000 m3/day UAT ELECTRICITY 80 MW

5000 Crores

80 MW

ASH 4200 t/day

Figure 1.2

Energy balance for a 1000 MW thermal power plant (See color figure)

Source: 1.3.2

Oil and Natural Gas

1.3.3

Electricity

5

6 Handbook of Energy Audit Andhra Pradesh, 3% Tamil Nadu, Tripura, 3% 3% Rajasthan, 1%

Tamil Nadu, 1%

Eastern offshore 3% Rajasthan, 9%

Andhra Pradesh, 1%

Gujarat, 6% Eastern offshore, 35%

CBM, 7% Western offshore, 45%

Gujarat, 18%

Assam, 10% Assam, 23% Western offshore, 32%

Chart 1.3

Geographical distribution of crude oil and natural gas in India (See color figure)

Source:

Electricity (MW) thousands

250 200 150 100

50 0 1970 Thermal

Figure 1.3

1.3.4

Hydro Energy

1980 Hydro

1990 Year Nuclear

2000

2010 Other

Total electricity production (See color figure)

Total

Global and Indian Energy Scenarios

1.3.5



7

Nuclear Energy

1.4

PRESENT NONRENEWABLE ENERGY SCENARIO Installed renewable energy Solar 4% Biomass 13%

Hydro 13%

Wind 70%

Chart 1.4 Energy distribution of total installed capacity of 25410 MW (as on August 2012) (See color figure)

8 Handbook of Energy Audit

1.4.1

Wind Energy

Indian Wind Atlas

Wind Atlas The Indian Wind Atlas

Table 1.3

State-wise installed capacities of wind energy State

Installed capacity (MW)

Tamil Nadu

7153

% of total production

38.56

Gujarat

3093

16.67

Maharashtra

2976

16.04

Rajasthan

2355

12.69

Karnataka

2113

11.39

Andhra Pradesh

435

2.34

Madhya Pradesh

386

2.08

Kerala

35

0.19

Others

4

0.02

Total

18, 550

Table 1.4

State-wise potential for installation of wind farms State

Potential (MW)

State

Potential (MW)

Andaman & Nicobar

2

Madhya Pradesh

920

Andhra Pradesh

5394

Maharashtra

5439

Arunachal Pradesh

201

Manipur

7

Assam

53

Meghalaya

44

Chhattisgarh

23

Nagaland

3

Gujarat

10609

Odisha

910

Himachal Pradesh

20

Rajasthan

5005

Contd

Global and Indian Energy Scenarios

State

Potential (MW)

State

Potential (MW)

Jammu & Kashmir

5311

Sikkim

98

Karnataka

8591

Tamil Nadu

5374

Kerala

790

Uttarakhand

161

Lakshadweep

16

Uttar Pradesh

137

West Bengal

22

Total

49, 130

Table 1.5

Indian wind energy on the world map Country

1.4.2

Installed capacity (MW)

China

62, 364

USA

46, 919

Germany

29, 060

Spain

21, 674

India

16, 084

France

6800

Italy

6737

UK

6540

Other countries

41, 491

Total capacity

2, 37, 669

Biomass Power Generation

jatropha

9

10 Handbook of Energy Audit

Table 1.6

State-wise details of biogas power generation

State

Installed (kW)

Under installation (kW)

State

Installed (kW)

Under installation (kW)

Andhra Pradesh

253

279

Tamil Nadu

1051

1117

Bihar

0

3

Uttarakhand

37

17

Gujarat

30

0

Uttar Pradesh

10

122

Haryana

115

20

Madhya Pradesh

25

13

Karnataka

746.5

450

Chhattisgarh

0

10

Maharashtra

524.5

215

Kerala

118

9

Punjab

166.5

516

West Bengal

60

0

Rajasthan

7.5

10

Odisha

4

3

Total

3148

2784

1.4.3

Small Hydropower Plant

Table 1.7

Statewise details of small hydropower projects

State

Andhra Pradesh Arunachal Pradesh Assam Chhattisgarh Gujarat

Potential Installed Under installation (MW) (MW) (MW)

978.4 1341.4 238.7 1107.1 202

217.8 101.5 31.1 27.2 15.6

35.25 31 15 140 -

State

Manipur Meghalaya Mizoram Nagaland Odisha

Potential Installed Under installation (MW) (MW) (MW)

109.1 230 168.9 197 295.5

5.5 31 36.5 28.7 64.3

2.8 1.7 0.5 4.2 3.6

Contd

Global and Indian Energy Scenarios

State

Goa Haryana Himachal Pradesh Jammu & Kashmir Karnataka Kerala Madhya Pradesh Maharashtra

Potential Installed Under installation (MW) (MW) (MW)

6.5 110 2397.9 1430.7 4141.1 704.1 820.4

0.05 70.1 536.9 130.5 915.4 158.4 86.1

3.35 182.5 34.7 322 52.8 4.9

794.3

295.5

80.6

1.4.4

Solar Power

1.4.5

Off-grid Renewable Power

1.4.6

Decentralized System

State

11

Potential Installed Under installation (MW) (MW) (MW)

Punjab 441.1 Rajasthan 57.2 Sikkim 266.6 Tamil Nadu 46.9 Tripura 46.9 Uttarakhand 1707.9 Uttar Pradesh 460.8 Andaman & 7.9 Nicobar Total 19750

154.5 23.9 52.1 16 16 170.8 25.1

21.2 0.2 178 -

5.3 3496

1251

12 Handbook of Energy Audit

Figure 1.4

Map of gas pipelines in India (See color figure)

Global and Indian Energy Scenarios



1.5

13

PRESENT ENERGY CONSUMPTION Others, 5%

Traction and Railway, 2%

Commercial, 9% Industy, 45%

Agricultural, 17%

Domestic, 22%

1.5.1

Gross Domestic Product (GDP)

C

I

M 1.5.2

Energy Intensity

1.5.3

Current Energy Production and Pricing

Chart 1.5 Sector-wise distribution of present energy consumption (See color figure)

G

X

14 Handbook of Energy Audit

Energy intensity of GDP at constant purchasing power parities

Unit: koe/$05p Less than 0.15 koe/$05p 0.15 to 0.20 koe/$05p 0.20 to 0.30 koe/$05p 0.30 to 0.70 koe/$05p More than 0.70 koe/$05p No data

Source Enerdata

Figure 1.5

World map of energy intensity (See color figure)

7000

0.17 0.165

Per capita energy cons. (kWh)

0.16 5000

0.155 0.15

4000 0.145 3000

0.14 0.135

2000

0.13 1000 0.125 0 1960

1970

1980

1990

2000

2010

0.12 2020

Year

Figure 1.6

History of per-capita energy consumption and energy intensity

Energy intensity (kWh) per rupee)

6000

Global and Indian Energy Scenarios

Primary energy production in thousands of peta joules

450

360.399 350

250 200 150

130.51

100 50

Figure 1.7

1.6

322.988

300

0



389.279

400

33.286 Non Crude oil conventional

Coal

Hydro

Nuclear

Different sources of energy contributing to total primary energy

ENERGY SECURITY

15

16 Handbook of Energy Audit



1.7

ENERGY STRATEGY FOR THE FUTURE

1.7.1

National Electricity Policy, 2005

1.7.2

Tariff Policy, 2006

Global and Indian Energy Scenarios

1.7.4

The Electricity Act, 2003

17

18 Handbook of Energy Audit



1.8

CLEAN DEVELOPMENT MECHANISM

1.8.1

Objectives of the Clean Development Mechanism

1.8.2

Applications of the Clean Development Mechanism

If you cannot create a drop of oil or a watt of power, you have no right to waste it. Descriptive Questions

Q-3 Write a note on Indian energy security and the Indian energy strategy for future.

Global and Indian Energy Scenarios

Short-Answer Questions

Q-5 What is the Indian Wind Atlas

Multiple-Choice Questions

emission

nd

(b) 3rd (d) 5th

th

Answers 1. (c)

2. (b)

3. (b)

4. (a)

5. (d)

6. (b)

7. (b)

19

20 Handbook of Energy Audit

THINK

GREEN

Glossary of Energy Terms



Solid fuel



Liquid fuel

Hard coal including anthracite and bituminous coal. Lignite Coke Crude

Motor gasoline

Kerosene o

o

: Kerosene and gasoline or naphtha are blended volume. Gas oil or diesel oil o

o

Fuel oil: It consists of residual fuel oil and heavy fuel oil. It is a general

process. heavy hydrocarbon oil, tar, and pitch. It has high carbon and low ash

Global and Indian Energy Scenarios

21

: It is semisolid or solid hydrocarbon of brown

: It is a noncondensable gas collected in the petroleum∑

Gaseous fuel

Natural gas

Coke or oven gas Biogas

It is obtained from natural or managed forests and also includes wood

∑ ∑

Charcoal

∑ ∑

Bagasse Installed capacity

∑ ∑

Energy

energy

2

Types of Energy Audits and Energy-Audit Methodology



2.1

DEFINITION OF ENERGY AUDIT

Types of Energy Audits and Energy-Audit Methodology



2.2

COMPANY/BUILDING WHERE ENERGY AUDIT IS PERFORMED

Industry/Building

Plant A/Ground Floor

Plant B/First Floor

Department A/Section I

Process A

Equipment A

Chart 2.1



2.3

Process B

Equipment B

Department B/Section II

Department A

Department B

Process A

Process B

Process

Equipment A

Equipment A

Equipment

Symbolic representation of the company or building where the audit is performed

ENERGY-AUDIT METHODOLOGY

Preliminary audit walkthrough audit

23

24

Handbook of Energy Audit

Table 2.1

Preliminary and detailed audits Preliminary audit (Walkthrough audit)

Detailed audit

Fast process of existing data collection, e.g., collection Observe the parameters if metering devices are of energy bill, gas bill, invoice. installed and if not, use measuring devices. Check for steam, fluid, compressed air, chilled air, fuel leak, damper position, etc.

Apart from physical check, carry out energy and material balance for each stream and process.

Identify immediate and low-cost energy-saving areas, In addition to immediate and low-cost energye.g., setting the thermostat on higher temperature in saving potential, work out vigorously for technology air conditions, reducing lighting lamps, etc. change, retrofits, cost of change, or upgradation of installation, etc. Identify the areas where detailed energy audit is required like process modification, waste-heat utilization, etc.

Detailed audit

∑ ∑ ∑

Phase I Audit Preparation � Step 1:



∑ ∑

Carry out in-depth financial analysis of proposed changes. Suggest ESCOs.

Types of Energy Audits and Energy-Audit Methodology

Audit criteria

Data inventory and measurement Preparing the audit report with recommendations

Scope

Selection of team

Analyzing energy-use pattern

Audit plan

Checklist preparation

Initial walkthrough

Benchmarking and comparative analysis

Identifying energy-saving potential

Collecting energy bills and data

Preliminary analysis

PREPARATION

Implementing the action plan Cost-benefit analysis

EXECUTION

Chart 2.2 Three phases of audit

∑ ∑ ∑ ∑ ∑ � Step 2:

Preparing the action plan

REPORTING

25

26

Handbook of Energy Audit

Industry/Building

Plant A/Ground Floor

Plant B/First Floor

Department B/Section II

Department A/Section I

Process A

Process B

Equipment A

Equipment B



∑ � Step 3:

� Step 4:

Department B

Process A

Process B

Process

Equipment A

Equipment A

Equipment

Chart 2.3 Scope of audit



Department A

Types of Energy Audits and Energy-Audit Methodology

∑ ∑ ∑ ∑ � Step 5:

∑ ∑ ∑ ∑ ∑ � Step 6:

� Step 7:

∑ ∑ ∑ ∑ ∑ ∑ � Step 8: A preliminary analysis

27

28

Handbook of Energy Audit Fine gas 902 MJ

Hot exhaust air 1500 MJ

Electricity 10 KJ Steam

Steam boiler

HD oil 5000 MJ

Process heating

3987 KJ

Blow down loss 50 MJ

Electricity 500 MJ

Product

Air

Refrigeration plant

Cold water

Condensate 1600 KJ

Process cooling

Finished product

Heat from condenser 1500 MJ

Figure 2.1

Energy flow chart 1 Total Efficiency (HHV) : 65.00%

Recycle: 50% 0.99 MPa 1273 K 55.181 MW

SOFC

Inverter 97%

1750 K

Exhaust gas 1750 K 0.98 MPa

1 123 K 1.0 MPa

0.101 MPa 1237 K

Preheater

0.97 MPa 635 K

400 K 0.1 MPa

1.01 MPa 580 K CP

G 12.620 MW

Water

Heat exchanger

841 K Preheater

1149 K 0.99 MPa 310 mol/s

Combustor

0.772 V

Blower 0.032 MW

100 MW Natural gas (methane) 290 K 1.01 MPa 112 mol/s

34 mol/s 566 K 0.99 MPa

TB 0.1 MPa

CP Oxygen

TB

Air 290 K 2264 mol/s

Oxygen separator Air 365 K

Figure 2.2

Feed pump

Vapor Separator 290 K 1.01 MPA

0.924 MW

A.C. gen 95%

365 K 0.1 MPa

322 K 0.1 MPA

Air 290 K

Energy flow chart 2

Liquefaction 1.844 MW

Carbon Dioxide tank

Types of Energy Audits and Energy-Audit Methodology

29

Phase II Execution � Step 1: Sankey diagram

TOTAL ENERGY IN T% = 100% or T Joules

56

56

100 27 17

17 Waste Sound S% energy or out S Joules

Figure 2.3

27 Heat H% or H Joules

A sample Sankey diagram

Diesel consumption in GPM

250

200

150

100

50

0

Jan

Feb Mar April May June July

Aug Sept

Oct

Nov

Dec

Month of the year

Figure 2.4

Inventory diagram for diesel-oil consumption per month

Handbook of Energy Audit 3300 3200 Unit consumption kWh

3100 3000 2900 2800 2700 2600 2500 2400

Jan

Feb

Mar April May June July

Aug Sept Oct

Nov Dec

Month of the year

Figure 2.5

Inventory diagram for annual electricity consumption Cleaning cost 4% Maintenance cost 16%

Energy Cost 54% Operating cost 26%

Figure 2.6 Annual Energy Consumption in MJ

30

Pie chart of annual building-operating cost (See color figure) 7000 6000 5000 4000 3000 2007 2008 2009 2010 2011 2012 2013 2014 Year Plant A

Figure 2.7

Plant B

Specific energy consumptions of two different plants

Types of Energy Audits and Energy-Audit Methodology

Salvage value

Revenues

t=0 End of life-cycle

Maintenance costs

Initial cost Figure 2.8

Cash flow of a project

∑ ∑ ∑ ∑ � Step 2:

Energy intensity (kW per ton) = � Step 3:

Energy consumed (kW) on (ton) Productio

31

32

Handbook of Energy Audit

∑ ∑ ∑ ∑ ∑ ∑

� Step 4: Energy Conservation Methods (ECM)



∑ x





x

Types of Energy Audits and Energy-Audit Methodology

� Step 5:

Phase III Reporting � Step 1:













33

34

Handbook of Energy Audit

Table 2.2

Sample audit report

S. No.

Content

1 1.1 1.2 1.3

Summary of report Key findings like annual consumption, budget, performance indicators, etc. Recommended energy-conservation methods Outcome of financial analysis

2

Audit, objective, scope, and methodology

3 3.1 3.2 3.3

About the plant Introduction of plant and general plant details Process and production of plant Plant layout Type of energy used in the plant

4 4.1 4.2

Process description Flow diagram Energy balance

5 5.1 5.2 5.3 5.4

Energy analysis (whichever applicable) Boiler assessment Lighting system assessment HVAC system assessment Compressed-air system assessment

6 6.1 6.2 6.3

Energy use and cost analysis Specific energy consumption Analysis of energy use and production pattern Energy benchmarking

7 7.1 7.2 7.3

Energy-conservation measures Suggested energy-conservation measures with financial analysis Energy-action plan Energy benchmarking

8

Concluding remarks and brief action plan for implementation of energy-saving measures

9

Acknowledgement

10

Annexure Worksheet and calculations Technical data List of supplier/vendors for technologies and systems

� Step 2:

Types of Energy Audits and Energy-Audit Methodology

∑ ∑ ∑ ∑

� Step 3:

∑ ∑ ∑ ∑ ∑



2.4

FINANCIAL ANALYSIS

principal (P) interest (I

depreciation

35

36

Handbook of Energy Audit

time value of money

simple interest

F =

*

F

compound interest

F = capital cost

2.4.1

Annual cash

Simple Payback

Capital cost Annual savings

Types of Energy Audits and Energy-Audit Methodology

0 5 Project life (years) Project A

Figure 2.9

2.4.2

0

5 10 Project life (years) Project B

37

15

Simple payback method applied to two different types of projects

Return on Investment

Annual net cash flow ¥100 Capital cost

100 Total saving (for life of project) - Estimated project cost ¥ Project life Estimated project cost

2.4.3

Net Present Value and Internal Rate of Return

present value of money money

future value of

38

Handbook of Energy Audit

internal rate of return.



B - Cn B1 - C1 B2 - C2 + + �� + n 2 (1 + r ) (1 + r ) (1 + r )n



B - Cn B1 - C1 B - C2 + 2 + �� + n 2 (1 + IRR ) (1 + IRR ) (1 + IRR )n



B - Cn B1 - C1 B2 - C2 + = + �� + n 2 (1 + r ) (1 + r ) (1 + r )n

Example 2.1

Solution n

B -C

 (1t + r )tt

t =0

3400 - 3000 40700 - 4000 33500 - 5000 2500 + 9000 + + + = 8955 Rupees (1 + 0.12 ) (1 + 0.12 )2 (1 + 0.12 )3 (1 + 0.12 )4

Example 2.2

Solution

Types of Energy Audits and Energy-Audit Methodology

Table 2.3

Net present value for different discount rates

Discount rate

Net present value

12%

+8955

16%

+7139

17%

+441

18%

–1104

Figure 2.10

2.4.4

Screenshot of Microsoft Excel 2007

Lifecycle Cost Method

C

 tn= 0 (1 + td )t

=



39

40

Handbook of Energy Audit



2.5

SENSITIVITY ANALYSIS



2.6

PROJECT-FINANCING OPTIONS

2.6.1

Credit Financing (Loan)

Types of Energy Audits and Energy-Audit Methodology

2.6.2

Lease Financing

operating lease, capital lease

2.6.3



Equity and Bonds

2.7

ENERGY MONITORING AND TARGETING

Energy monitoring

Table 2.4 Week

Tabulated data for energy consumption for 12 weeks Production (tonnes)

Energy consumption (kWh)

1

140

145

2

90

105

3

70

92

4

80

87

5

120

147

6

130

157

7

140

145

8

100

110

9

90

114

10

80

106

11

70

84

12

65

76

41

42

Handbook of Energy Audit

2.7.1

Regression Analysis

=

180 160

y = 0.9572x + 20.277 R² = 0.9049

Energy (kWh)

140 120 100 80 60 40 20 0 0

20

40

Figure 2.11

2.7.2

Cumulative Sum (CUSUM)

Example 2.3

60 80 100 Production (tonnes)

120

140

Energy consumption vs production

160

Types of Energy Audits and Energy-Audit Methodology

Solution Step 1: Step 2 Step 3

Table 2.5

Energy consumption for different production rates over two years

Month

Energy consumption (toe/month)

Production (tonnes/month)

1

610

720

2

630

780

3

590

680

4

700

840

5

680

770

6

580

630

7

620

780

8

750

960

9

690

790

10

710

830

11

570

610

12

590

670

13

600

780

14

650

820

15

680

940

16

590

750

17

550

610

18

580

670

19

580

780

20

620

830

21

530

950

22

670

840

23

650

800

24

610

710

43

Handbook of Energy Audit Energy consumption (toe/month)

44

800 y = 0.5651x + 216.69

750 700 650 600 550 500 500

Figure 2.12

600

700 800 900 Producton rate (tonnes/month)

1000

Energy consumption vs production rates for the first twelve months

Step 4 Step 5 Step 6 Step 7 Step 8 Table 2.6

Calculated values of energy consumption and CUSUM

Month

Energy consumption (actual)

Production

1 2 3 4 5 6 7 8 9 10 11 12 13

610 630 590 700 680 580 620 750 690 710 570 590 600

720 780 680 840 770 630 780 960 790 830 610 670 780

Energy consumption (calculated)

623.4 657.3 600.8 691.2 651.65 572.55 657.3 759 662.95 685.55 561.25 595.15 657.3

Energy consumption (actual – calculated)

–13.4 –27.3 –10.8 8.8 28.35 7.45 –37.3 –9 27.05 24.45 8.75 –5.15 –57.3

CUSUM

–13.4 –40.7 –51.5 –42.7 –14.35 –6.9 –44.2 –53.2 –26.15 –1.7 7.05 1.9 –55.4

Types of Energy Audits and Energy-Audit Methodology

Month

Energy consumption (actual)

Production

14 15 16 17 18 19 20 21 22 23 24

650 680 590 550 580 580 620 530 670 650 610

820 940 750 610 670 780 830 950 840 800 710

Energy consumption (calculated)

679.9 747.7 640.35 561.25 595.15 657.3 685.55 753.35 691.2 668.6 617.75

Energy consumption (actual – calculated)

–29.9 –67.7 –50.35 –11.25 –15.15 –77.3 –65.55 –223.35 –21.2 –18.6 –7.75

CUSUM

–85.3 –153 –203.35 –214.6 –229.75 –307.05 –372.6 –595.95 –617.15 –635.75 –643.5

100 0 1

3

5

7

9

11

13

15

17

19

-100 Months

CUSUM

-200 -300 -400 -500 -600 -700

Figure 2.13

2.7.3

CUSUM chart for given data

Targeting

∑ Performance Benchmarks

∑ Normalized Performance Indicator 3

21

23

45

46

Handbook of Energy Audit



Descriptive Questions

Short-Answer Questions

Multiple-Choice Questions

Types of Energy Audits and Energy-Audit Methodology

Answers 1. 8.

2. 9.

3. 10.

4.

5.

6.

7.

47

3

Survey Instrumentation



3.1

ELECTRICAL MEASUREMENT

Electrical measurement includes estimating the energy consumption of the entire plant/factory/ building and the energy consumptions of individual systems. It includes the wattmeter, ammeter, multimeter, power-factor meter, etc. These instruments can measure and/or record the data for a particular period and help check the change in pattern over a period of time. 3.1.1

Multimeter

As the name says, the multimeter (also known as volt–ohm meter) is a versatile measuring instrument as it can measure voltage, current, and resistance. It is available in many forms like analogue, digital, clamp–on, etc., with measuring capabilities ranging from 0 to 300 A, 0 to 600 V,

3.1.2

Power-Factor Meter

A power-factor meter measures the ratio between resistive power and total (resistive + inductive) power. The value of the power factor is important to an auditor as power distortion and penalty are decided by it. 3.1.3

Power Analyzer

The power analyzer is a single and three-phase power measuring system, capable of measuring voltage, current, power factor, instantaneous power, instantaneous voltage, reactive volt–amperes, frequency, average and maximum power, harmonic distortion, energy in watt-hour. It is able to store or print the data and also network with computer software and similar instruments at different locations. Some high-end models have features like measuring wide bandwidth, accurate capturing

Survey Instrumentation

49

of voltage and current waveforms, harmonic analysis, high-frequency power spectrum analysis, synchronized measurement, etc. Figure 3.1 shows a multimeter, power-factor meter, and power analyzer.

Figure 3.1



3.2.1

3.2

Multimeter, power-factor meter, and power analyzer (See color figure)

THERMAL MEASUREMENT

Temperature Measurement

of waste heat, and potential for waste-heat recovery. Temperature-measurement equipment are available in many forms like surface temperature probes, immersion probes, radiation-shielded probes, infrared thermometers (noncontact thermometers), thermographic equipment, etc. Temperature is measured by three basic methods—thermal expansion, change in resistance, and thermocouples. Mercury in glass is an example of the thermal-expansion principle, normally used for on-site temperature measurement. This method lacks the means for automated data recording and accuracy. A Resistance Temperature Detector (RTD) operates on the basis of the change in resistance as a function of temperature. Usually, copper and platinum are used as they show a fairly linear increase of resistance with rise in temperature. Thermocouples work on the principle, “when two dissimilar metals are joined with each other, known as the Seebeck effect. Contact thermometers work on the thermocouple principle and are For surface-temperature measurement, a leaf-type probe is used. They are calibrated for different temperature ranges, decided by a wire diameter. A probe consists of a wire housed inside a metallic tube, and is known as a sheath. Infrared thermometers, or noncontact thermometers, can measure temperature from a distance by measuring the infrared energy emitted by the object and its emissivity. These are helpful to measure temperatures of distant locations and close systems like furnaces, etc. An infrared thermometer torch and its working is shown in Figure 3.2.

50

Handbook of Energy Audit

Bandwidth filter

Emissivity

Lens Hot target

Energy radiance

Irradiance reflected energy

Detector

Amp

Output signal Linearization

Figure 3.2

Infrared thermometer and its working (See color figure)

Like a usual camera, the thermographic camera or infrared camera (FLIR— Forward-Looking Infrared Camera) captures thermal images of the object by detecting its radiation. It can work even in total darkness. Apart from an energy audit, this device is very useful in rescue operations in smokecamera are shown in Figure 3.3. A thermal leak detector works on the same principle and helps an auditor identify the area of heat leak.

Figure 3.3

Thermographic image of a building (See color figure)

Apart from temperature, humidity plays an important role in the HVAC industry. A psychrometer is used to measure the relative humidity of air. It has two bulbs, one dry and the other wetted with wick. Due to evaporation of water from the wick of the wet bulb, it measures the saturation temperature of air at the corresponding vapour pressure. Readings of dry-bulb temperature and wetbulb temperature give the Relative Humidity (RH) at that location. A hygrometer is a device which measures moisture content in the air. Images of a psychrometer and hygrometer are shown in Figure 3.4. � Air-leakage Measurement The blower door test measures the air tightness of a building. In this Figure 3.4

Psychrometer and hygrometer (See color figure)

Survey Instrumentation

51

through unsealed gaps, cracks, openings, etc. A manometer measures the pressure difference between two sides of door which shows the amount of air leak in the room. 3.2.2

Pressure Measurement

The U-tube manometer is a device which measures the difference in system pressure and atmospheric pressure by measuring the height of a liquid (water, alcohol, or mercury) in a U-shaped clear glass tube. Pgauge = Psystem – Patm = r gh

(3.1)

Here, r is the density of the liquid in the tube, measured in kg/m3. A more sensitive version of the U-tube manometer is the inclined-tube manometer. The most commonly known pressure measurement device is a Bourdon gauge, in which an elliptical section tube is used which is sealed at one end. When exposed to high pressure at the open gauge pressure on the dial. Bellows and barometers are also used as pressure-measuring devices. Piezoelectric pressure sensors and strain-gauge sensors are used where precise pressure measurements are required. In the piezoelectric pressure sensor, change in pressure is detected by displacement of a thin metal or semiconductor diaphragm, which causes a strain on the piezoelectric crystals integrated in circuit. They offer the advantage of small size, fast response, and wide operating range. Vacuum is measured by Pirani and ionization gauges. Process pressure

P2 h P1

Figure 3.5

U-tube manometer, Bourdon gauge, piezoelectric pressure sensor, and digital manometer (See color figure)

A Pitot tube with a manometer is used to measure total and static pressures. It has doublewalled tubes—the inner tube measures total pressure, the outer tube measures static pressure, and differential pressure can be obtained from it. 3.2.3

Flow Measurement

52

Handbook of Energy Audit

meters, etc., are installed at all critical plant locations. An auditor can read data either from a measuring device or This method uses ultrasound sensors to detect average beam of ultrasound. It has no moving parts and, hence, is wear-free and maintenance-free, has no pressure drop, and is ideal for non-intrusive parts. 3.2.4

Velocity Measurement

An auditor needs to measure velocity of air in the HVAC section and combustion air. The velocities of air and gases,

Figure 3.6 Ultrasonic flowmeter (See color figure)

by cup anemometers, windmill anemometers, hot-wire sensors, laser dopplers, sonic anemometers, etc. To determine the velocity, an anemometer detects

3.2.5

Combustion and Flue-Gas Analysis

gas composition. Combustion testing determines the concentration of products of stack gas, which are usually carbon dioxide, carbon monoxide, and oxygen. The concentration and temperature of the Fyrite® gas analyzer, and portable combustion analyzer are known methods to measure the composition of stack gas. � Orsat Apparatus In this test, a measured volume of stack gas is taken to a calibrated water-jacketed burette, which is connected by a glass capillary tube to two or three absorption pipettes containing chemical solutions that absorb the gases. A solution of caustic potash is used to absorb the carbon dioxide gas;

Figure 3.7 Anemometer to measure air velocity (See color figure)

solution of cuprous chloride is used to absorb carbon monoxide. During the stages of absorption, the reduction in volume after each stage is a measure of each constituent. as it requires considerable time, the operator has to handle it accurately, and it is not useful for low concentrations. Hence, portable and easy-to-use equipment are used.

Survey Instrumentation

Figure 3.8

53

Combustion-gas analyzer (See color figure)

� Fyrite® Gas Analyzer It can analyze carbon dioxide or oxygen by taking the gas sample ®

gas analyzer is, it does not depend upon complicated sequential tests, is free from the effect of � Portable Combustion Analyzer It is shown in Figure 3.9 is generally used by boiler and furnace attendants and energy auditors. The combustion analyzer has in-built chemical cells for measurement and display of oxygen level, gas temperature, 2

x

2

2

Many PCAs offer data acquisition and printing facility. The sampling probe is inserted in the middle of the stack, where A more advanced unit for a combustion analyzer is the

environment compliance. Whether the combustion in plant is as per environmental regulations or not, can be checked by this equipment which can help improve the overall and smoke testers are few more equipment used to measure pressure in draft tubes and quality of combustion respectively. �

3.3

Figure 3.9 Lux meter (See color figure)

LIGHT MEASUREMENT

and lux meters are used to measure the intensity of light in a particular area. A lux meter consists of photocells, which sense light output and convert it to lux, footcandle, or cd/m2. Some units offer internal memory, data logging, and recording facility. Data obtained from lux and light meters are helpful in optimizing the sizes and types of lighting systems and ensuring that proper lighting level is maintained as per standards.

54



Handbook of Energy Audit

3.4

SPEED MEASUREMENT

Speed measurement is critical to applications like electric motors, fans, pumps, compressors, etc. A tachometer, or RPM meter, is used to measure the rotation of a shaft. A digital or analogue dial displays the speed in RPM. A tachometer can be used where direct access is possible, while a stroboscope is used in case of noncontact type of speed measurement. Hard performed by a stroboscope. Both units have built-in memory s that permit automatic storage of maximum, minimum, average, last displayed value, etc., in advanced versions. �

3.5

Figure 3.10 Tachometer and stroboscope (See color figure)

DATA LOGGER AND DATA-ACQUISITION SYSTEM

A data logger is a digital-processor-based electronic device that records data over a stipulated time, either with a built-in sensor or via signals received from a sensor. They are small and portable devices equipped with microprocessors, memory, sensors, etc. Many of them are interfaced with personal computers and appropriate software. They are general-purpose as well as tailor-made logger is automatic collection of data at a 24-hour basis, and the device can be left unattended to measure and record data for a particular duration. The costs of data loggers are decreasing as technology improves. Data acquisition It is the process of sampling signals that measure physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. They include sensors that convert physical parameters to electric signals, signal-conditioning circuits to convert sensor signals into digital values, and analogue-to-digital converters. The difference between a data logger and a data acquisition system is data loggers are batteryoperated, and have high resolution, in-built memory, and slow sample rates. Table 3.1 gives a list of other special-purpose instruments with the parameters measured by them. Table 3.1 S. No.

List of some other special-purpose instruments Name of instrument

Parameters measured

1.

Hot disk transient plane source (Gustafsson probe)

Thermal conductivity, thermal diffusivity, specific heat, etc., of solids and liquids

2.

Blower door test

Building’s air tightness

3.

Digital thermo-anemometer

Air velocity in feet per minute or metre per second, air temperature in °F or °C

4.

Amprobe— relative humidity temperature meter

Relative humidity of air

Contd...

Survey Instrumentation

S. No.

Name of instrument

55

Parameters measured

5.

TDS meter

Conductivity and, thereby, total dissolved solids in blowdown water of a boiler

6.

Dynamometer

Power produced by engine, motor, or other prime mover

7.

Pyranometer and pyrheliometer Diffused and beam solar radiation

8.

Sunshine recorder



3.6

Hours of sunshine over a day

THERMAL BASICS

Common terms used in thermal energy are explained here: 1. Temperature is a measure of the molecular activity of a substance. The greater the

temperature scales normally employed for measurement purposes are the Fahrenheit (F) and Celsius (C) scales. 2. Pressure is a measure of the force exerted per unit area on the boundaries of a substance (or system). It is caused by the collisions of the molecules of the substance with the boundaries of the system. As molecules hit the walls, they exert forces that try to push the walls outward. The forces resulting from all of these collisions cause the pressure exerted 2 , or psi. When pressure is measured relative to a perfect vacuum, it is called absolute pressure and when measured relative to atmospheric pressure, it is called gauge pressure. Pabs = Patm + Pabsgauge

(3.2)

3. Energy Potential Energy Kinetic Energy (KE) is the energy of motion and Internal Energy (IE) is the energy in microscopic form (rotation, vibration, as stored energy or transit energy. 4. Heat because of temperature difference. Heat can be transferred in three different mechanisms like conduction, convection, or radiation. In conduction, the process of heat transfer occurs in the direction of temperature gradient from one particle to another without moving them from their places. While in convection, particles move from their places. Radiation occurs through electromagnetic waves and is independent of the medium in which it occurs. 5. is the amount of heat required to raise the temperature of a unit mass of any substance through one degree. Solids and liquids do not change their volumes on heating pressure and volume.

56

Handbook of Energy Audit

6.

m ¥ Cp ¥ (T2 – T1)

(3.3)

m ¥ Cv ¥ (T2 – T1)

(3.4)

It is transformation from one phase or state to another by heat transfer. terms for phase-change process are given in the following table.

Table 3.2

Phase-change processes Solid

Liquid

Gas

Solid

---

Melting

Sublimation

Liquid

Freezing

---

Boiling or evaporation

Gas

Deposition

Condensation

---

7.

is a thermodynamic property and is the summation of internal energy of the system and product of pressure and volume. h = U + pV

8.

9.

10.

11.

12. 13.

(3.5)

is the energy released or absorbed by a body during change of phase. Temperature change does not occur during phase-change process and, hence, the name given to the exchange of heat is a synonym of the word hidden; while sensible heat is the one due to change in temperature. Latent heat of fusion (or enthalpy of fusion) is the change in enthalpy resulting from heating a substance to change its state from solid to liquid. Similarly, latent heat of vaporization is the enthalpy change required to transfer the substance from liquid into a gas at a particular pressure. is the science dealing with the study of moist air. Dry air is a mixture of a number of gases like nitrogen, oxygen, carbon dioxide, etc. Moist air is a mixture of dry air and water vapour. Saturated air is a mixture of dry air and water vapour when the air has diffused the maximum amount of water vapour into it. is the mass of water vapour in 1 kg of dry air; and the ratio of actual mass of water vapour in a given volume of air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure is termed relative humidity. is the temperature recorded by a thermometer and wet-bulb temperature is the temperature of air recorded by a thermometer whose bulb is surrounded by a wet cloth exposed to air. is recorded by a thermometer when the moisture present in the air begins to condensate. are materials storing potential energy that can be released for work of heat. A fuel can be solid, liquid, or gas in nature. Wood, coal, charcoal, peat, etc., are examples of solid fuels. Heat released from the complete combustion of fuel is known as heat of combustion.

Survey Instrumentation

14.

57

is the heat produced by the complete combustion of fuel and measured in kJ/kg. The is the total heat liberated by complete combustion of one unit of fuel including the heat recovered from condensed water vapour. If the heat recovered from condensed water vapour is excluded, it is termed value. HCV – LCV = Mass of H2 ¥ Latent heat

Table 3.3

(3.6)

Calorific values of some fuels

Solid fuel

Calorific value (kJ/kg)

Liquid fuel

Calorific value (kJ/kg)

Gaseous fuel

Calorific value (kJ/m3)

Peat

14,500

Petrol

44,250

Natural gas

35,500 to 46,000

Lignite coal

21,000

Kerosene/Paraffin oil

44,000

Coal gas

21,000 to 25,000

Bituminous coal

31,500

Fuel oil

44,250

Producer gas

4200 to 6600

Anthracite coal

36,000

Alcohol

26,800

Blast-furnace gas 3800

Wood charcoal

28,000

Petrol

44,250

Coke or oven gas 14,500 to 19,000

Coke

32,500

Diesel

44,800

Oil gas

17,000 to 25,000

15.

Steam which includes water droplets is known as wet steam. When the steam is heated further, all water droplets evaporate and the steam is called dry saturated steam. Heating it further at higher than its boiling point is termed superheating and the steam is called superheated steam. 16. describe fundamental physical quantities like temperature, pressure, and entropy. The zeroth law of thermodynamics states that “If two systems are in thermal equilibrium The of thermodynamics states that “When energy passes, as work, as heat, or with matter into or out from a system, its internal energy changes in accord with the law of The second law of thermodynamics states that “In a natural thermodynamic process, the The third law of thermodynamics states that “The entropy of a system approaches a

Descriptive Questions

58

Handbook of Energy Audit

Short-Answer Questions

Multiple-Choice Questions

Survey Instrumentation

1.

2.

3

4

5

Answers 1. (d) 8. (d)

2. (a)

3.

4. (a)

5.

6.

7. (d)

59

4

Energy Audit of Boilers A boiler, or a steam generator, produces steam at a designed pressure and

Data Source



4.1

CLASSIFICATIONS OF BOILERS

Energy Audit of Boilers

4.1.1

Fire-tube Boiler

Steam out

Furnace

Figure 4.1

4.1.2

Packaged Boiler

Hot gases

Boiler

Smoke stack

A typical fire-tube boiler

61

62

Handbook of Energy Audit

Safety valve

Anti Steam Water level priming stop Manhole pipe valve alarm

Internal flues

Steam space Boiler feed Water

Blowdown

Water

Coal feed

Figure 4.2

Lancashire boiler Fully trimmed with all safety controls and piping Exhaust stack

Davited hinged access doors (tubes)

High temp. refractory lined rear door

UL. listed burner

Flame sight port

Fully automated processor

Figure 4.3

Source:

Gas, oil or combination forced draft burners

Extra heavy skids and supports

All A.S.M.E. code piping to second valve

Internal construction of a packaged boiler (See color figure)

Energy Audit of Boilers

4.1.3

Water-tube Boiler

Furnace

Water pipes

Steam out

Hot gases

Smoke stack

Water in

Figure 4.4

A typical water-tube boiler

63

64

Handbook of Energy Audit

Steam Feedwater

Steam off-take Steam Water

Feedwater Waste gases to stack Heat

Waste gases to stack

Heat (a) Straight-tube longitudinal drum

(b) Straight-tube cross drum Steam off-take

Feedwater Waste gases to stack

Mud drum Heat (c) Bent-tube (Stirling boiler)

Figure 4.5

Underfeed stokers

Overfeed stokers Mass-feed stokers

Water-tube boilers

Energy Audit of Boilers

Spreader stokers

Dumping grate Spray pipe Ash PLT

Figure 4.6

Dumping grate Spray pipe

Air damper Push bar

Retort

Coal Distribution block

Ash PLT

Cross section of underfeed stoker (Source Reference: T C Elliott)

Rear furnace arch Grate cooling tubes Adjustable ash dam

Air damper

Coal air nozzles Fuel feed gate Water cooled header

Vibration

Air zones

Figure 4.7

generator Grate support and flaxing member

Cross section of overfeed mass-feed stoker (Source Reference: T C Elliott)

65

66

Handbook of Energy Audit Overfire air nozzle

Coal hopper Furnace arch

Fuel feed grate

Grate clips or grate keys

Air control dampers

Figure 4.8 Cross section of overfeed travelling grate stoker (Source Reference: T C Elliott)

Exhaust pipe Pressure spring Raw coal feed pipe Air intake

Grinding roll Ring or bowl

Bearing

Worm drive

Worm gear Bearing

Figure 4.9

4.1.5

Pulverized Coal Boiler

Ring pulverizer (See color figure)

Energy Audit of Boilers

4.1.6

Fluidized-Bed Boiler (FBC)

Figure 4.10

Fluidized-bed combustion boiler

67

68

Handbook of Energy Audit

Gasifier

Gas stream cleanup/component separation

Fuels Syngas CO/H2

Chemicals

H2

Coal

Transportation fuels

Particulates

Biomass Feedstock Petroleum coke/resid

H2

Gaseous constituents

Solids

Combustion Turbine

Sulfur/ sulfuric acid Air

Electric power Combined cycle Generator Electric power

Oxygen

ASU

Air

Exhaust Water

Waste

Steam

Heat recovery steam generator

Marketable solid by-products

Stack Exhaust CO2 for sequestration Generator

Electric power Steam turbine

Figure 4.11

Integrated gasification combined cycle (See color figure)

Energy Audit of Boilers



4.2

PARTS OF A BOILER

evaporator superheater

economizer Air preheaters burner

boiler blowdown system feedwater pump collecting tank/hotwell boiler combustion air system

de-aerator



4.3.1

4.3

EFFICIENCY OF A BOILER

Direct Method

69

70

Handbook of Energy Audit

h=

Output Enthaply of steam - Enthalpy of feedwater ¥100 = Input Heat r eleased in boiler

EXAMPLE 4.1

Solution

h= h 4.3.2

Indirect Method

10000 ¥ (2899.2 - 440.17) ¥ 100 860 ¥ 41200

Energy Audit of Boilers

Step 1: ¥C C H 2 S2

¥ S2

¥ H2

O2

O2

Step 2: O2 ¥ 100 21 - O2 ¥ Step 3: mg ¥ C pg ¥ (T f - Ta ) GCV of fuel

CO2

SO2

N2

N2

¥ 100

O2

C Tf Ta Step 4:

H2

=

2

=

M ¥ [ H fg + C p

steam

¥ (T f - Ta )]

GCV of fuel

¥ 100

Step 5: 9 ¥ H 2 ¥ [ H fg + C p steam (T f - Ta )] GCV of fuel

¥ 100

71

72

Handbook of Energy Audit

Step 6:

=

Actual air supply ¥ Humidity factor ¥ c p (T f - Ta ) GCV of fuel

¥ 100

Step 7: Total fly ash collected ¥ GCV of fly ash kg of fuel burnt = ¥ GCV of fuel Step 8: Total bottom ash collected ¥ GCV of bottom ash kg of fuel burnt ¥100 = GCV V of fuel Step 9:

Table 4.1

Percentage heat loss from a boiler surface

Boiler capacity (kg/h)

% heat loss

90,000

0.5

45,000

0.7

22,500

0.9

10,000

1.0

Step 10:

EXAMPLE 4.2

2

2

2

Energy Audit of Boilers

2

2

2

Solution

¥

¥

¥

3.8 ¥ 100 21 - 3.8

¥

17.03 ¥ 1.005 ¥ (260 - 20) ¥ 100 41200 2

H2

9 ¥ 0.12 ¥ [2444 ¥ (260 - 20)] ¥ 100 41200

H2

=

0.01 ¥ ( 2444 + 1.88 ¥ ( 260 - 20 )) ¥ 100 41200

=

0.0195 ¥ 19.69 ¥ [2444 + 1.88 ¥ (260 - 20)] ¥ 100 41200

73

74

Handbook of Energy Audit

Efficiency of boiler

84 83.2 82.4 81.6 80.8 0

10

20

30

Ambient air temperature C

Figure 4.12



4.4

Effect of ambient temperature on efficiency

ROLE OF EXCESS AIR IN BOILER EFFICIENCY

40

Energy Audit of Boilers

2

®

Table 4.2

Effect of excess air on combustion efficiency

Excess air %

Combustion efficiency (Tf – Ta)ºC

9.5 15 28 45 82

95

150

205

260

315

85.4 85.2 84.7 84.1 82.8

83.1 82.8 82.1 81.2 79.3

80.8 80.4 79.5 78.2 75.6

78.4 77.9 76.7 75.2 71.9

76.0 75.4 74.0 72.1 68.2

EXAMPLE 4.3

` O

7 ¥ 100 23 - 7

O

2 ¥ 100 23 - 2

O2

h inittial ˆ Ê ¥ ¥ Á1 Ë h modified ˜¯ `/

75

76

Handbook of Energy Audit

O2 and CO2 in flue gas (% by volume)

18

14

CO2

10

O2

6

Anthrasite coal Bituminous coal Fuel oil Propane Natural gas

2 0

20

60 100 Excess air

140

Figure 4.13 O2, CO2, and excess air

4.4.1

How to Measure Excess Air

4.4.2

Excess Air Control

Energy Audit of Boilers



4.5

ENERGY-SAVING METHODS

2

77

78

Handbook of Energy Audit

4.5.2

Waste-Heat Utilization

Table 4.3

Energy saved due to feedwater heating

Feedwater temperature in ºC 1

40 60 80 100 120

Energy saved in kJ/kg for different boiler operating pressures (bar) 5 10 15 100

250 167 84 -----

464 377 294 211 126

2

Table 4.4

585 502 418 334 251

660 577 493 410 326

1133 1049 966 882 798

2

Stack gas and feedwater temperatures for different fuels

Type of fuel

Acid dew point temperature ºC

Natural gas Oil Low sulphur oil

65.5 82.2 93.3

Minimum stack-gas temperature ºC

121.1 135 149

Minimum feedwater temperature ºC

99 99 104.4

Energy Audit of Boilers

79

Intermittent blowdown continuous blowdown

Feed water TDS x % make up water Maximum permissible TDS 4.5.4

Effective Boiler Loading Flash steam

Blowdown lines Flash Tank To sewer

Figure 4.14

Heat recovery in blowdown

80

Handbook of Energy Audit

4.5.5

Exhaust-Gas Recirculation

Energy Audit of Boilers

Table 4.5

Thermal conductivity values of different types of scales

% Increase in cost

Material

Thermal Conductivity in W/mK

Silicate scale

0.35

Carbonate scale

0.60

Sulphate scale

1.45

Mild steel

52.50

80 70 60 50 40 30 20 10 0 0

0.1

Figure 4.15

0.2 0.3 Scale thickness (inch)

0.4

Effect of scale deposition on operating cost

Methods to Monitor Scale Formation

Water-treatment Methods internal water-treatment

External treatment

0.5

81

82

Handbook of Energy Audit

4.5.9

Heat Loss in De-aeration

4.5.10

Use of Briquette-Fired Boilers

Table 4.6

Composition of briquettes

Appearance

Gray/ Black

Nature

Cellulose

Bulk Density

1100 kg/m3

Carbon

40% to 42%

Hydrogen

3%

Sulphur

Nil

Moisture

Less than 5%

GCV

3800 to 4000 kcal/kg

Ash

5% to 8%

Energy Audit of Boilers

CHECKLIST

THUMB RULES

83

84

Handbook of Energy Audit

Descriptive Questions

Short-Answer Questions

Multiple-Choice Questions

Energy Audit of Boilers

Answers

1. 8.

2. 9.

3. 10.

4. 11.

5. 12.

6.

7.

85

5

Energy Audit of Furnaces furnace



5.1

PARTS OF A FURNACE

� Heating System

� Refractory

� Loading Unloading System

� Heat Exchanger

� Instrumentation and Control

Energy Audit of Furnaces



5.2

CLASSIFICATION OF FURNACES

� Batch Furnace � Continuous Furnace

Furnace

Type of loading

Batch

Continuous

Type of heating

Direct-fired

Indirectly heated

Material handling

Flowthrough

Conveyer belt

Rotary kiln

Walking beam

Vertical shaft

Car bottom

Chart 5.1 Classification of furnaces

87

Cokes BG

Dust Catcher Venturi scrubber LDG Scrap

Circulation Cyclone blower

Belt conveyor

Figure 5.1

Pure water tank

Condenser

Steelmaking process

Moltern

Blooming mill

Slab

Bloom

Billet

Direct rolling

Rolling process

Reheating furnace

Roles of furnaces in the steel industry

Slabbing

Soaking

Ingot making

Steel

Oxygen, auxiliary materials

Power generator

Plants

BF gas holder

Continuous Hot Hot blast caster metal Sintering machine stove Blast furnace Low pressure steam Scrap Waste heat boiler Coke High pressure steam oven Dust Deaerator remover Electric furnace G Turbine Coke car Cokes 200° C Power generator

Coke oven Powder cokes

Coking coal

Ironmaking process

Hot rolled coil Hot rolled sheet

Seamless pipe

Welded pipe butt welded pipe

Cast iron products

Seamless pipe mill

Welded pipe mill

Cold rolled coil Cold rolled sheet Steel sheet for Cold stip rolling mill plating

Hot strip rolling mill

Plate rolling mill

Plate

Wire rod

Major products Rail Steel piling Steel section Steel bar

Wire rod rolling mill

Long product rolling mill

Rolling

88 Handbook of Energy Audit

Energy Audit of Furnaces

Table 5.1

89

Details of different types of furnaces

Process

Process description

Type of furnace

Source of heating

Approximate temperature, °C

Carbonization Conversion of coal to coke Coke oven

Indirect heating

1000 to 1200

Calcination

Removal of CO2 from CaCO3 for cement production

Rotary kiln

Fossil fuel

1200 to 1300

Heating

Hot working and/or heat treatment

Batch /Continuous Oil- or gas-fired type

Below melting point

Sintering

To produce compacts of particles

Sintering furnace

Fossil or electric

Below melting point

Electrolysis of To produce Al, Mg, molten metal and Na

Hall-Heroult cell

Electric

700 to 900

Refining

To produce steel

Electric

Electric or chemical 1600

Smelting

To produce matte

smelter

Fossil or chemical

1200

Converting

To produce copper from matte

Side-blown converter

Chemical

1100 to 1200

� Flow-through

� Conveyer Belt

� Rotary Kilns

Figure 5.2 Conveyer and rotary-kiln furnace (See color figure)

� Walking Beam

90

Handbook of Energy Audit

� Vertical Shaft



5.3.1

5.3

ENERGY-SAVING MEASURES IN FURNACES

Heat Generation

Flue loss

Usable heat

Heat input to furnace

Stored heat

Coolant loss

Operating loss

Wall loss

Chart 5.2 Heat losses in a furnace

5.3.2

Air Preheating

Energy Audit of Furnaces

Table 5.2

Energy saving due to air preheater

Furnace exhaust-gas temperature, ºC

5.3.3

Gain in efficiency for preheated air temperature, ºC 315

425

540

650

760

990

540

13

18

-

-

-

-

650

14

19

23

-

-

-

760

15

20

24

28

-

-

870

17

22

26

30

34

-

990

18

24

28

33

37

40

1100

20

26

31

35

39

43

1200

23

29

34

39

43

47

1315

26

32

38

43

47

51

Oxygen Enrichment

Air

Air Oxygen Fuel

Fuel Oxygen Oxygen injection lance

Figure 5.3

Fuel Oxygen

Different methods of oxygen enrichment

91

92

Handbook of Energy Audit

5.3.4

Heat Transfer

Q = e s A (Ts4 - T•4 ) (Ts

T A

5.3.5

Heat Loss Through Outer Surface and Openings

Energy Audit of Furnaces

5.3.6

93

Heat Recovery

Tri-generation

5.3.7

Use of Advanced Technology

turndown ratio

5.3.8

Energy Saving in an Electric-Fired Furnace

Electrodes

Charging door

� Energy Saving in an Arc Furnace

Arc furnaces are

Slag

Arc

Spout

Molten steel

Figure 5.4 Arc furnace (See color figure)

94

Handbook of Energy Audit

5.3.9

Changing Power Source from AC to DC

AC

DC electric furnace

DCL (-) Electric room

VCB Transformer Transformer

Bottom electrode (+)

Substatin Bottom electrode cooling device X

Figure 5.5

Schematic of a dc arc furnace

Energy Audit of Furnaces

5.3.10

Use of Continuous Casting Machine

5.3.11

Use of a High-Frequency Melting Furnace

Table 5.3

Comparison of low-frequency and high-frequency melting furnaces Low-frequency melting furnace

High-frequency melting furnace

Slow melting process due to low current density

Rapid melting process due to high current density

Difficult to have batch operation

Possible to have batch operation

Low equipment cost

High equipment cost

High specific power consumption (719 kWh/t)

Low specific power consumption (630 kWh/t)

Slow melting speed (910 kg/h)

Fast melting speed (1550 kg/h)

5.3.12 Energy Saving in a Fuel-Fired Furnace

� Use of Pulverized Coal Instead of Coking Coal

� Installation of Top-Gas-Recovery Turbine

� Dry Quenching of Coke

95

96

Handbook of Energy Audit

Y

Figure 5.6



5.4

A turbine to produce electricity from blast-furnace exhaust gas

FURNACE EFFICIENCY

Heat in the stock Heat in the fuel h=

mstock ¥ C p ¥ DT mfuel ¥ CV

m Cp T mfuel

Step 1:

Calculate theoretical air required. ¥C C H S

O

¥H

¥S

O

Energy Audit of Furnaces

Calculate actual air supplied, which is a summation of theoretical air and excess air.

Step 2:

O2 ¥ 100 21 - O 2 ¥ Step 3: m g ¥ C p ¥ (T f - Ta ) GCV of fuel

¥ 100

m +N Cp Tf Ta GCV Calculate heat loss due to evaporation of water formed due to H2

Step 4:

H 9 ¥ H 2 ¥ [H fg + C p steam ¥ (T f - Ta )] GCV of fuel

¥ 100

Cp Step 5:

=

mstock ¥ C p stock ¥ (T f - Ta ) GCV of fuel

¥ 100

m Cp Tf Ta Step 6:

=

Actual air supply ¥ Humidity factor ¥ C p steam ¥ (T f - Ta ) GCV of fueel

¥ 100

97

98

Handbook of Energy Audit

Calculate heat loss due to radiation and convection heal loss from the furnace’s outer

Step 7:

2 ˘ ÈÊ T - 75 ˆ Q È 9.7Twall ˘ =Í - 1.42Twall + 164 ˙ - ÍÁ amb ˜¯ (0.085 (Twall - 100 ) + 90 )˙ Ë A Î 1, 000 50 ˚ ˚ Î Reference Industrial Furnaces

qsurface =

A T

= qsur face ¥ 100 GCV of fuel

Step 8:

(

t ¥ s ¥ A ¥ T f4 - Ta4 GCV of fuel

) ¥ 100

t A Tf Ta Step 9:

m water ¥ C p water ¥ (Two - Twi ) GCV of fuel m C T

T

¥ 100

Energy Audit of Furnaces

99

Step 10:

re think re use re cycle re inkTM

CASE STUDY

� Objective furnace � Technical Detail

∑ ∑ ∑ ∑ ∑ Details

Monthly energy consumption of 30 kg induction arc furnace Material handled per month Number of cycles per month Specific energy consumption Annual energy consumption Cost of energy Annual energy saving due to induction furnace Annual cost saving Investment for induction furnace (Medium frequency-3000 Hz, 50 kg and 100 kg pot size at 90 kW and 125 kW respectively) Payback period

Units

Data

kWh kg No kWh/Mt kWh Rs kWh Rs Rs

14, 434 13, 970 438 968 1, 73, 208 8, 66, 040 1, 03, 925 5, 19, 625 10, 00, 000

Years

1.92

100

Handbook of Energy Audit

� Outcome

CHECKLIST

Descriptive Questions

Short-Answer Questions

Energy Audit of Furnaces

Multiple-Choice Questions

Answers 1. 8.

2.

3.

4.

5.

6.

7.

101

6

Energy Audit of a Power Plant



6.1

INDIAN POWER-PLANT SCENARIO

The total installed capacity of Indian power plants is 258.701 GW (Data Source CEA, as on 31/01/2015) being produced by National Hydroelectric Power Corporation (NHPC), National Thermal Power Corporation (NTPC), Nuclear Power Corporation of India (NPCIL), statelevel co-operations, and private sectors. The Power Grid Corporation of India is responsible for the inter-state transmission of electricity and development of the national grid. Out of total electricity generation in India, 69.71% is from coal, gas and diesel-based thermal power stations, 15.79 % is from hydro generation, 2.23 % is from nuclear-based power plants, and the remaining 12.25% is contributed by renewable sources (includes small hydro projects, power plants. �

6.2

HOW IS ENERGY AUDIT OF POWER PLANTS HELPFUL?

Energy audit of a power plant results in resource protection—as less fuel is required for generation of electricity, substantial reduction in CO2 emission, and increased electricity generation from the range of 36–40%, and that of a supercritical pressure range thermal power plant is around 40–44%. Hence, there is good scope to achieve the above-mentioned goals. Energy audit of a thermal power plant is discussed in the present chapter after a brief description of thermal power plants. � 6.3.1

6.3

TYPES OF POWER PLANTS

Thermal Power Plant

Since inception of the Rankine cycle, steam power plants use it as a standard cycle. The real Rankine cycle used in a power plant is much more complex than the original simple ideal Rankine cycle.

Energy Audit of a Power Plant

103

A thermal power plant continuously converts the energy of fossil fuels like coal, oil, or gas into work and ultimately into electricity. The Rankine cycle consists of four thermodynamic processes: (i) reversible constant pressure heating of water to steam in a boiler, (ii) reversible adiabatic expansion of steam in a turbine, (iii) reversible constant-pressure heat rejection in the condenser, and (iv) reversible adiabatic compression of liquid in a pump. The ideal Rankine cycle is a combination of all these processes, and Figure 6.1 gives its schematic representation. Figures 6.2 and 6.3 give its thermodynamic representations on p-v and T-s. 1 WT Superheater

Turbine Steam generator

Evaporator Q1

2

Economizer

Condenser

Q2

3 Pump 6

Figure 6.1 P

Schematic of a thermal power plant T

CP 4 B

CP

1

1

B

3

4

2

3

2 S

V

Figure 6.2

Rankine cycle on p-V coordinates

h= WP = WT = Wnet = Q1 = h1 to h4 =

where

Figure 6.3 Rankine cycle on T-s coordinates

Wnet WT - WP (h1 - h2 ) - (h4 - h3 ) = = h1 - h4 Q1 Q1

pump work turbine work net work = turbine work – pump work heat input enthalpy of steam at terminal points

(6.1)

104

Handbook of Energy Audit

The combustion gases leaving the boiler are at much higher temperatures than the saturation temperature at which steam is produced in a steam drum in an ideal Rankine cycle, resulting in irreversibility. Use of superheat and reheat reduces overall temperature difference between steam with superheat and reheat in which ab shows temperature drop in the combustion gas, 1234 represents the superheat cycle, and 123456 is the reheat cycle. Reheating is carried out at 20% to 25% of initial steam pressure to optimize the performance. T

a

T a 1

3

1

b 8

7

b

2

4

6

3

2

5

4¢ 4 S

S

Rankine cycle with superheat

Figure 6.4

Rankine cycle with reheat

Figure 6.5

feedwater heaters. Feed heaters are basically of two types — open or closed. They extract live steam and use its energy to heat the condensate. In most thermal power plants, closed feedwater heaters are used with at least one open feedwater heater to serve the purpose of de-aeration. Though successively diminishes with the increase in the number of feedwater heaters. The schematic and T-s diagram of regeneration is shown in Figures 6.6 and 6.7 respectively. T

1

1 Steam turbine 2 3 4

B 2

10 9

8 7

6

Steam generator

m1 m1

3

m3

m2

Condenser P

5

P

P

5

10

4

9

8

7

6

S

Figure 6.6

Rankine cycle with regeneration

Figure 6.7

Schematic diagram of regeneration

Coal

Railway tanker heavy oil

Day tank

Oil transfer pump

Heavy oil pump

F.D. Fan

I.D. Fan

Gas from chimney

Storage tank

Coal storage

Air from atmosphere

Chimney

Figure 6.8

H.P. Feed heater Evaporator Water treatment plant

Boiler feed pump

Generator

U.G. Tank

Treated water

Surface reservoir

River water for make up

Bore well

Chlorine plant

Cold Water

River

C.W. Pump

Water storage basin

Cooling pond

Hot Water

Intake pump house

Raw water

Booster pump

L.P. Feed heater

Gas to atmosphere ejector

Hot well pump

Condenser

Typical layout of a thermal power plant

Distilled water

Gas to atmosphere

Turbine

Generator

Energy Audit of a Power Plant

105

106

Handbook of Energy Audit

h overall =

power avaiilable at the generator y the combustion of fuel rate of energy release by

= hgenerator ¥ hturbine ¥ hthermal ¥ hboiler

(6.2)

The value of hoverall is around 35%; hence, the remaining 65% is lost to the environment Heat rate and steam rate Heat rate = Steam rate =

Q1 Wnet

(6.3)

1 kg Wnet kWs

(6.4)

Figure 6.9 shows steam and water circuits of a thermal power plant. 168 Kg/cm2 320°C

Main steam 150 Kglcm2, 540°C

Main steam

Reheated steam 35 Kgicm2, 540° C

Reheated steam Bled steam

IP SV & CV 210 MW, KWU design, 3 cylinder turbine

HP SV & CV

HPT

Boiler drum

IPT

247 MVA Generator GEN.

LPT

Deaerator

Super reheater heater B.F.P.

Evaporator

Economizer 1300°C Flue gases 244°C 180 Kg/cm2

Air Coal

Warm water Cooled water

30°C C.W. pump Condensate 45°C

LP heaters Feed water

Figure 6.9

Condenser 0.91 Kg/cm2 vacuum

FRS

HP heaters

Boiler

Bled steam

120°C

C.E.pump

Cooling tower

Feed water Condenser cooling water

Steam and water circuits of thermal power plant (See color figure)

(Source: http://indianpowersector.com )

Energy Audit of a Power Plant

6.3.2

107

Combined-Cycle Power Plant

As there is a wide difference between combustion temperature and steam temperature, there is a

used with a high-temperature plant as a topping plant over a steam-operated power plant. A gasturbine plant, either of open or closed type, is used as a topping plant as it offers advantages like faster and cheaper installation, quick starting, and fast response to load change. A gas turbine alone Figure 6.10 shows the schematic of an open gas-turbine cycle. The gas enters a compressor where it is compressed and delivered to the combustor. Heat is added at constant pressure in the combustor (theoretically) and hot gas expands through the turbine, and then mixes with the atmosphere and fresh air is supplied to the compressor. The compressor is driven by the turbine and the difference is available on the shaft as the net power output. The compression of air in the compressor and expansion of gas in the turbine are ideally isentropic in nature. Fuel Exhaust Gas

Air Inlet Combustor

Generator Compressor

Figure 6.10

Turbine

Open-cycle gas-turbine plant

Figure 6.11 shows intercooling and reheating in an open-cycle gas-turbine plant, and Figure 6.12 shows regeneration in an open-cycle gas-turbine plant. Use of intercooling between two stages of power output of the turbine. In regeneration, the waste heat of the exhaust gas of the turbine is Coolant (air, water etc.) intercooler

Combustor Fuel

Fuel

Generator LP compressor

Figure 6.11

HP compressor

HP compressor

Power turbine

Intercooling and reheating in an open-cycle gas-turbine plant

108

Handbook of Energy Audit Regenerator

Combustor

Generator

Compressor

Figure 6.12 b

Turbine

Regeneration in an open-cycle gas-turbine plant

Fuel

c

C.C Air Compressor

Gas Turbine

Generator

d

a Fuel

1

C.C Steam Turbine

e

Generator

H R S G

2 Condenser

f

Pump 4

Figure 6.13

3

Schematic flow diagram of a combined-cycle power plant

combustor, and gas turbine in the topping cycle; and a heat-recovery steam generator, steam turbine, condenser and pump in the bottoming cycle. The path of the open-cycle gas turbine is indicated as abcdef. Gas leaves the turbine at the point d as it is further heated in the combustion chamber where fuel is supplied and passes through the heat-recovery steam generator, which is a conventional steam generator having heat exchangers like an evaporator, economizer, superheater, reheater, etc. further combustion. The gas leaves the HRSG at f. The path followed by the steam cycle is shown Energy-audit methods and checklist discussed in the chapters are focused on thermal and combined-cycle power plant technology as out of the total electricity production, 65% is produced by these technologies. These are also applicable to steam cycles of nuclear power plants. �

6.4

ENERGY AUDIT OF POWER PLANT

Energy Audit of a Power Plant

109

service utilities, collection of design and operating data, measurement of various parameters, technologies and their technical and economical viabilities, prioritization, documentation, and

and, therefore, will be a valuable input into the next inspection maintenance scope to implement the necessary corrective actions. Some useful observations of energy audit of a power plant are discussed in detail as follows. 6.4.1

Use of Supercritical Pressure Boilers

Use of supercritical-pressure boiler instead of subcritical boilers.

(refer Rankine cycle T-s diagram), and environment friendly. A supercritical cycle with reheat Adopting a supercritical boiler instead of a subcritical boiler will reduce fuel consumption and, consecutively, carbon dioxide emissions reduce by approximately 5 percent. A supercritical boiler is also known as a once-through boiler as it does not require a drum which adds to quick start and rapid load change. However, supercritical-type generation requires more sophisticated equipment design and high-strength material to withstand the high temperatures and pressures. Extremely pure water is required since all solids present are deposited in the tubes or carried to the turbine blades. Availability of high-temperature resistance material at economical rates has increased the adoption of supercritical-pressure steam generation. 6.4.2

Improving Condenser Performance by Condenser-Tube Cleaning

Select appropriate method to clean the condenser tubes. A condenser degrades primarily due to fouling of the tubes and air in-leakage. Tube fouling leads to reduced heat-transfer rates, while air in-leakage directly increases the back by mechanical, thermal, or chemical methods. A more suitable method for online cleaning is using rubber sponge balls condenser tubes with the coolant. Frictional contact between the balls and tubing scrapes away most of the fouling accumulated on the inside of the tubes. The balls are circulated through the condenser for a few hours each day. Periodical checking and replacement of balls are required as sponge balls eventually lose their surface roughness, or become deformed, and become unable to contact the inside wall closely. Figure 6.14 shows the basic arrangement of a typical ball-type tube-cleaning system. The main components are a ball injection nozzle, a ball strainer, a ball recirculating pump, and a ball collector.

110

Handbook of Energy Audit

Condenser cooling water pump

Ball collecter

Condenser

Ball recirculating pump

Figure 6.14

6.4.3

Arrangement of ball-type tube-cleaning system

Waste-Heat Recovery

Identify the source of waste heat and utilize it. Before installing any heat-recovery system, an investigation needs to be carried

1. Recycling energy back into the process 2. Recovering energy for other on-site uses 3. Recovering energy for electricity generation Active heat recovery requires input of energy to upgrade the waste heat to a higher temperature, while passive heat recovery uses a heat exchanger of different type to transfer the heat from the higher temperature source to the lower temperature stream. The advantage of a passive heat-recovery device is that it does not is simpler to implement and maintain than active heat-recovery strategies. In some applications, both types of heat-recovery devices are used together. over the course of day and year, and fouling characteristics. Some waste-heat-recovery systems are discussed here: In this process, thermal energy of the high-temperature exhaust gas, which was previously wasted, is recovered, is converted into steam in the waste-heat boiler, and is used for driving the steam turbine to generate electrical power.

Energy Audit of a Power Plant

111

Exhaust gas out

Pre heater

Steam turbine

Condenser

Pump

Super heater

Cooling tower Pump

Exhaust gas in

Figure 6.15

Waste-heat-driven steam turbine

The probable layout of waste-heat recovery steam generation is shown in Figure 6.15. The should involve low-pressure loss. Dust accumulation in the heat-exchanger tube, and resultant corrosive gases, the design should be such that the temperature of the heat-exchanger tube does not fall in a range to cause low- or high-temperature corrosion. Use of a preheater and superheater will small, supplementary fuel is used. The electric power generated is used as auxiliary power. In this arrangement, latent heat of steam leaving the steam turbine and sensible heat of exhaust gas leaving the HRSG is utilized. The arrangement is shown in Figure 6.16. As discussed in Section 6.3.2, a combined-cycle power plant utilizes the waste heat of a gas-turbine exhaust. The energy of steam generated in the heat-recovery steam generator is utilized in a steam turbine. Now, instead of condensing the steam in a conventional condenser, it is taken to LNG condensing heat-exchanger condenser where LNG at a low temperature is pumped to the required pressure. The LNG gets vaporized at –162oC exchanging latent heat with steam. Feedwater will be circulated in a shell-and-tube type heat exchanger utilizing remaining sensible heat of exhaust gas to preheat the water till the saturation temperature. Some mass of preheated water will be used in heating NG up to 120°C. The advantages of these methods are given here: 1. The condensation of steam takes place at a lower temperature which reduces condenser 2. Additional hot water/air is not required to vaporize and preheat LNG. Some examples of waste-heat recovery for applicable temperature ranges are listed here. If waste-heat stream temperature is more than 100°C, waste heat is used for. 1. Preheating combustion air. 2. Preheating boiler make-up water using a feedwater economizer.

112

Handbook of Energy Audit Combustion chamber

AC

GT

LNG at -120° C To combustion chamber

HRSG

ST

LNG condenser LNG

Exhaust

NG at -162° C

Figure 6.16

Waste-heat recovery in LNG fuelled HRSG system

3. Preheating the supply air into a process such as a food dryer by passing its supply air and exhaust through an air-to-air heat exchanger. 5. Using waste heat from a process to meet other in-plant needs such as space heating, water lower temperature processes. for absorption chillers of refrigeration or air-conditioning devices.

6.4.4

Improvement in Performance of Air Preheater

Minimize leakage and losses from an air preheater.

of the economizer. There are two primary types of air preheaters—regenerative, rotating-type and more advanced systems using heat pipes. The majority of air preheaters used with utility-scale boilers is the regenerative type. (refer

Energy Audit of a Power Plant

113

enamel-coated carbon steel material at the cooler end due to acid deposition. The cylinder rotates cold pre-combustion air. The cylinder rotates on an axle. Ductwork manifolds on the top and bottom use of regenerative air preheaters is air leakage as shown in Figure 6.18 from the higher-pressure

to lost heat recuperation. Fans are affected by the leakage since the combustion air requirement is Forced Draft (FD) and Induced Draft (ID the furnace.

Combustion air (to boiler)

Flue gas (from boiler)

Rotary housing

Gas

Air Inlet air

to stack Leaking air

Figure 6.18 Figure 6.17

Construction of air preheater

Leakage from circum of air preheater

Source: Alstom Power

Commissioning of air preheaters generally results in air leakage from the combustion-air side

2

power consumption of the FD fan; and if ID fans are used, even more auxiliary power is required to transfer the extra air.

evident in the loads on the fans as compared to original design loads if all other leakages are taken into account. If the air preheater allows a substantial amount of leakage and that is not addressed, Improvements to seals on regenerative air preheaters have enabled the reduction of air leakage to

114

Handbook of Energy Audit

roughly 6%. Different types of seals like carbon seal, electromechanical seal, or a gap controller is used to reduce the leakage. The gap between the sector plate and rotor changes according to the boiler load and gas temperature. Figure 6.19 shows the noncontact-type sensor which measures the gap and automatically controls the vertical gap within the desired limit. Enhancing the heat-transfer area and maintaining exit temperature of

6.4.5

Controller

Air

Gap adjuster

Radial seal

Exhaust gas

Sootblowing Optimization Figure 6.19

Gap controller of air preheater

sootblower. Sootblowing is an important part of boiler operation, since a clean heat-transfer employ soot-cleaning devices like sootblowers, sonic devices, water lances, and water cannons, or hydro-jets. These soot-cleaning devices use steam, water, or air to dislodge slag and clean surfaces within a boiler. The number of soot-cleaning devices on a given power-generating unit can range from several to over a hundred. Manual sequential and time-based sequencing of soot-cleaning devices have been the traditional methods employed to improve boiler cleanliness. These sootcleaning devices are generally automated and are initiated by a master control device. Frequent operation of a sootblower wastes steam, increases blower maintenance cost, and aggravates the tube erosion. Conversely, far less frequent blowing allows too much soot accumulation blown. Therefore, intelligent adjustment of the cleaning schedule according to the actual cleaning

and reduce fatigue in the turbine blades. Adjusting the amount of water sprayed into the steam header after the steam has passed through the superheater controls the steam temperature. The addition of spray water. Typical arrangement of a steam-temperature controller by an attemperator is shown in Figure 6.20. Some boilers are equipped with burner tilt which alters the distribution of heat for reheat temperature control that directly effects steam superheat temperature. Gas-pass dampers and gas recirculation is also used to control steam temperature in some utility boilers. At

Energy Audit of a Power Plant

115

low loads, gas recirculation is high to assist in achieving reheat temperature while at high loads, gas recirculation is reduced to its minimum value. Recommendations for steam-temperature control systems are listed here: 1. Instruments should be installed as close as practical to the source of the measurement. Temperature measurement should be located at least 20 pipe diameters downstream of any attemperator. 2. Proper coordination is required when more than one method of controlling the temperature is adopted. Attemperator spray water flow FT Attemperator block valve

Attemperator control valve

Spray water Drain valve

Stop valve

Check valve

Secondary superheater inlet temperature

Final steam temperature

TT

TT To turbine

Primary superheater

Attemperator

Secondary superheater

Drum

Figure 6.20

6.4.7

Typical arrangement of an attemperator

Reduction in Auxiliary Power Consumption

Minimize auxiliary power consumption. Auxiliary power consumption of Indian power plants is around 6.15% for a 500 MW plant and 8 to 10% for a 100 to 250 MW power plants. Various systems contributing to of equipment, start-up and shut-down, age of the plant and coal quality are key features affecting auxiliary power requirement. Auxiliaries may consume up to 12% of total generation; hence, reduction of even 0.5–1.0 % will result in huge savings and additional output of a few megawatts. Suggestions on individual auxiliary power-consumption devices are given in the following section. 1. Use speed control in place of valve control. 2. Use variable-speed-drive boiler feed pump and condensate extraction pump and variablespeed-drive hydraulic coupling.

116

Handbook of Energy Audit

Feed water system 38%

Cooling water system 13%

Draft system 25%

Ash handling system 8%

Coal handling and grinding 7%

Power Auxiliary Consumption

Water treatment plant 3%

Compressed air system 5% Lighting 1%

Figure 6.21

Various systems of auxiliary power consumption

3. Perform boiler feed pump scoop operation in three-element mode instead of DP mode. 4. Avoid recirculation and faulty valve. 5. Replacement of worn-out cartridge of boiler feed pump reduces current consumption and 6. Perform CEP pressure reduction by stage removal. 1. Arrest air in-leaks in the draft system by O2 measurement as excess air for combustion results in increase of FD, PA, and ID fan power. Leakage in APH results in increase of FD, PA, and ID fan-power consumption. Leakage in duct and ESP body results in increase of ID fan-power consumption. 2. Compare analyses of fan performances with respect to design condition and identify gaps by investigation and observation. 3. Check inlet/outlet duct connections, and fan body for holes and cracks. 4. Remove deposit formations in impellers and casings. 5. Treat erosion of impeller blades. 6. Properly maintain primary-air-to-secondary-air ratio to reduce the PA fan-power consumption. 7. Eliminate damper and inlet guide-vane-based capacity control with variable speed-control systems.

Energy Audit of a Power Plant

117

sized impellers. 1. Utilize proper capacity of the loading system and avoid idle running of conveyors/crushers. 2. Use auto Star–Delta starters instead of Direct OnLine (DOL) to minimize losses. 3. Observe that crushers are adequately and constantly loaded. 1. Maintain proper air–fuel ratio. 3. Optimized mill parameters like ball loading, roller pressure, etc., with respect to size and quality of coal.

Cooling-Water Pumps

2. 3. 4. 5.

Avoid mismatch of required head and rated head by proper selection of pump. Avoid circulation of water in standby systems. Use of booster pump is more advisable for small loads at higher pressure. Check seals and packing to minimize waste of water.

Cooling Tower

2. Follow the manufacturer’s recommended clearances around cooling towers while locating, and relocate or modify structures that interfere with inlet and exhaust air. 3. Optimize cooling-tower fan-blade angle on weather and/or load basis. 4. Correct excessive and/or uneven fan-blade tip clearance. 5. Periodically clean plugged distribution nozzles of cooling tower. 6. Maintain the optimum liquid to gas ratio (normally 1.4 to 1.6). 1. Avoid oversized pumps. 3. Do impeller trimming to permanently reduce the capacity of the pump. 4. Periodically check valves and leakage in gland sealing. Also check for deposition on impeller and casing.

1. Reduce discharge air pressure to lowest allowable limit. 2. Install a control system to coordinate more than one air compressor.

118

Handbook of Energy Audit

4. Identify and attend leakages and minimize purges. 5. Monitor the compressed-air distribution system and select lower pressure drop network. 6.4.8

Gas-Turbine Inlet Air Cooling

Inlet air temperature of air compressor of gas turbine. Cooling the turbine inlet air even by a few degrees increases power output substantially. This is because combustion turbines are constant-volume machines; hence, at a given shaft speed, they always move the same volume of air while the power developed by the turbine

output. Another reason of poor performance of gas turbine during summer is power consumption of the compressor. The work required to compress air is directly proportional to the temperature of the air, so reducing the inlet air temperature reduces the work of compression and there is more work available at the turbine shaft. The typical gas turbine on a hot summer day, for instance, produces up to 20% less power than on a cold winter day. There is, however, a limitation on the amount of inlet-air cooling that can safely be accomplished. If the temperature is allowed to go too low, ice may form on inlet guide vanes which will damage the compressor blades. This phenomenon may occur even when the inlet-air temperature is above the freezing point of moisture as the suction at a turbine inlet creates low pressure. To avoid this problem, most turbine manufacturers recommend a minimum inlet air temperature of 8ºC. Traditionally, mechanical chillers or evaporative coolers are used to cool combustion turbine inlet air. Recently, fogging system or absorption chillers are used to cool the inlet air.

Combustion air

Water tank Air filter

Wetted media

Water treatment

Exhaust gas

Make up

Fuel

Blow down

Combustion turbine

Figure 6.22

Evaporative cooling for air cooling

Energy Audit of a Power Plant

119

Factors affecting the selection and economics of a turbine inlet system are listed below: 1. Combustion turbine characteristics

Evaporative cooling and fogging systems (refer Figure 6.22) are useful for less humid locations. Their initial and running costs are low and cooling capacity is also low. For more humid locations, mechanical chillers are the alternative solution. Absorption chillers are used when the plant is in a combined cycle or cogeneration mode and has access to low-pressure steam. Descriptive Questions

Short-Answer Questions Q-1 How are superheat and reheat processes helpful in a Rankine cycle?

controlled?

Multiple-Choice Questions

(c) hydro power plants

(d) nuclear power plants

120

Handbook of Energy Audit

Q-3 Which one of the following is not an advantage of performing energy audit of a power plant? (a) Reduced CO2 emission

Q-5 Role of open feedwater heater in a ranking cycle is to perform

(c) 45 to 50%

(d) 55 to 60%

(c) 5, more

(d) 10, more

(c) 25–35%

(d) 35–45 %

(c) 20%

(d) 10%

(c) 20, more

(d) 30, more

Energy Audit of a Power Plant

(c) 10 Answers 1. (b) 8. (d) 15. (b)

(d) 15

2. (c) 9. (d)

3. (b) 10. (a)

4. (c) 11. (a)

5. (a) 12. (d)

6. (d) 13. (d)

7. (a) 14. (a)

121

7

Energy Audit of Steam-Distribution Systems



7.1

Table 7.1

WHY IS STEAM USED AS A HEATING FLUID?

Latent heats of different fluids at their boiling points Substance

Normal boiling point, ºC

Latent heat, kJ/kg

Water

100

2257

Ammonia

–33.3

1357

Ethanol

78.2

838.3

Ethylene glycol

198.7

800.1

Hydrogen

–252.8

445.7

Mercury

356.7

294.7

Nitrogen

–195.8

198.6

R-134a

–26.1

216.8

Energy Audit of Steam-Distribution Systems



7.2

STEAM BASICS

sensible heat

latent heat

100°C

Steam Atmospheric pressure

7 bar 170°C

Latent heat Latent heat

2,050 kJ/kg

2,257 kJ/kg

170°C 100°C Sensible heat Sensible heat 0°C

Figure 7.1

0°C

Conversion of water to steam at atmospheric pressure and higher pressure

Phases of Steam in the T s

Steam generation, steam utilization and steam recovery

123

124

Handbook of Energy Audit

350 221 bar .2

800 750 700

Dry steam line

600 Water line

500

Superheated lines

450

x=

300 273.16 250 0

0.25

350

1

2

r

Constant volume 2 /kg 0.5 m

400

0.006 112 b a

550

1 bar

ABS temperature K

650

h

2700 kJ/kg

Isothermal I. Dryness fraction 3

4

5

6

7

8

9

10

Entropy and kJ/kgK

Figure 7.2

T-s diagram of steam

th



7.3

Table 7.2

HOW TO ESTIMATE REQUIREMENT OF STEAM?

Steam quantity required by different consumers

Consumer

Bakery

Process

Dough room and oven

Soft drink Bottle washing for 100 bottles/ minute

Steam pressure required (bar) Steam flow rate required (kg/h)

2

2

2

13

Dairy

Pasteurizer

2 to 6

115

Hospital

Sterilizing and disinfecting (1500 cc)

4 to 4.5

12

Laundry

Steam ironing

8

2

EXAMPLE 7.1 Calculate the requirement of steam for a bottle-washing plant of 2000 bottles/minute capacity.

Energy Audit of Steam-Distribution Systems

Solution



7.4

STEAM-DISTRIBUTION SYSTEM

Boiler-2

Boiler-1 High-pressure stem

Turbine generator

Pressure-reducing station

Process-2

Process-1 Low-pressure vent Process turbine drive Condense

Process-3

Condensate receiver

Degenerator

Process-4

Condensate receiver

Figure 7.3 Sample of a steam-distribution network

125

126



Handbook of Energy Audit

7.5

Table 7.3

PRESSURE

Uses of steam

Process

Application of steam

Power generation

To drive a turbine, which in turn produces electricity.

Mechanical drive

To drive steam-powered turbines as an option of electricity purchased from a grid.

Drying

To dry agricultural and chemical products.

Injecting

For agitation or blending in chemical and petroleum process.

Quenching

To regulate the reaction temperature in an exothermic reaction process by direct injecting in the process.

Contd

Energy Audit of Steam-Distribution Systems

Process

127

Application of steam

Diluting

To dilute process gas and thereby reduce coke formation on the surface of a heat exchanger.

Pressure regulating

To control partial pressure of a reaction process, steam is injected with reactants.

Transporting

To transport the products, steam is injected in the process for entrainment.

Stripping

To remove contaminants from a process fluid.

Fractionating

To separate components having different boiling points in a distillation tower.

Ejecting

To maintain vacuum in the process.



7.6

Table 7.4

PIPING

Steam velocities for different steam qualities

Steam quality

Steam velocity in pipe (m/s)

Superheated

50 to 70

Dry saturated

30 to 40

Wet

20 to 30

EXAMPLE 7.2 Calculate the pipe diameter, handling steam for a process which requires 7000 kg/h of wet steam at 10 bar pressure. Solution 3

3

¥ 2

p xD D

128

Handbook of Energy Audit

A

B

Figure 7.4 A–Incorrect connection; B–Correct connection

B

A

Figure 7.5



7.7.1

7.7

A–Incorrect branch connection; B–Correct branch connection

LOSSES IN STEAM-DISTRIBUTION SYSTEMS

Quantify and Estimate of Steam Leak

Energy Audit of Steam-Distribution Systems

Table 7.5

Steam loss at different steam pressures

Leakage size (mm) 3.45

Leakage of steam in kg/h at a given steam pressure (bar) 6.89 10.34 13.79 17.24 20.68

3.2

12

21

30

39

48

60

67

6.4 9.5 12.7 19.1 25.4 31.8 38.1

46 103 183 411 731 1143 1645

82 183 326 733 1303 2036 2931

118 265 470 1058 1881 2938 4231

153 347 616 1387 2465 3851 5546

191 430 764 1719 3056 4776 6877

239 538 956 2151 3824 5975 8604

268 604 1073 2413 4290 6703 9653

Table 7.6

Steam losses at different plume lengths

Plume length (ft)

3 6 9 12

Steam loss (kg/h) 21°C ambient temperature 32°C ambient temperature

15.4 77.0 226.5 394.1

22.6 131.4 362.4 634.2

¥

7.7.2

129

Insulation on Steam-Distribution Lines and Condensate Return Lines

24.13

130

Handbook of Energy Audit

Table 7.7

Heat losses from un-insulated pipes at different steam pressures per 100 feet length of pipe

Distribution-line diameter, inches (mm)

Heat loss per 100 feet (30.84 m) of un-insulated steam line (million kJ/yr) at 24 °C ambient temperature Steam pressure (bar) 1 10 20 40

1 (25.4) 2 (50.8) 4 (101.6) 8 (203.2) Table 7.8

148 248 438 780

300 506 896 1625

395 665 1182 2142

522 886 1582 2875

Heat losses from un-insulated pipes at different steam temperatures per m length of pipe

Distribution-line diameter, inches (mm)

Heat loss per m of un-insulated steam line (MJ/h) at 21ºC ambient temperature Steam temperature (°C) 93

204

316

427

538

1 (25.4)

1

3

6

9

14

2 (50.8)

2

5

9

14

20

4 (101.6)

3

8

14

24

37

8 (203.2)

5

13

25

42

66

Energy Audit of Steam-Distribution Systems

131

EXAMPLE 7.3 Calculate heat loss from a bare pipe of 1-inch diameter, carrying steam at 10 bar pressure for a length of 1000 feet. Solution

` `

` ` `

` `

7.7.3

Flash Steam

Table 7.9

Energy loss from vent steam

Pipe diameter, inch (mm)

Energy content of a vent steam in million kJ/yr (Make-up water temperature is 25ºC and steam condenses at 40°C) Steam velocity, m/s 1

1.5

2

2.5

3

2 (50.8)

95

148

195

243

295

4 (101.6)

390

580

781

976

1171

6 (152.4)

881

1319

1757

2200

2638

10 (254)

2442

3661

4885

6198

7327

132

Handbook of Energy Audit

EXAMPLE 7.4 Quantify the steam leak per annum for a vent diameter of 2 inches and steam velocity of 2.5 m/s. Solution

` ` 7.7.4

Condensate Recovery

Saturated vapor supply

High-pressure condensate Steam trap

Low-pressure flash vessel Saturated vapor

Level controller

Saturated liquid

Figure 7.6

Condensate-recovery system

Condensate discharge

Energy Audit of Steam-Distribution Systems

133

EXAMPLE 7.5 Consider a steam system that returns an additional 5000 kg/h of condensate at 82ºC due to distri82%, and make-up water temperature of 25°C. The water and sewage costs, and treatment cost is 0.05 `/ ¥

Solution ¥ ¥

Heat Remaining in condensate (%)

¥

¥

Heat Loss in Condensate 30 25 20 15 10 5 0 50

Figure 7.7

7.7.5

Pipe Size

¥ `

70

90 110 130 150 Condensate Temperature (°C)

170

Heat loss in a condensate at different temperatures

134



Handbook of Energy Audit

7.8

ENERGY-CONSERVATION METHODS

7.8.1

Use of Two Different-Capacity Steam Generators for Two Different Pressure Requirements

7.8.2

Install Turbine Between High-Pressure Steam Generator and End Use in New Set-up Or Replace Pressure-Reducing Valve with Turbine in Existing Set-up

turbogenerators

7.8.3

Use Steam-Turbine Drive Instead of Electric Motor

7.8.4

Cover Open Vessels Containing Hot Water

Energy Audit of Steam-Distribution Systems

Table 7.10

Evaporative heat loss from steam to different atmosphere temperatures Evaporative heat loss in W/m2 from one square foot of open area

Fluid temperature, °C

Atmospheric temperature, °C

43 54 65 77 88

18

24

29

35

769 1509 2800 5065 9135

699 1424 2696 4933 8962

630 1339 2589 4800 8788

557 1250 2482 4668 8621

7.8.5

Use Removable Insulations on Valves and Fittings

7.8.6

Use Steam at Lowest Possible Pressure

7.8.7

Use Low-Pressure Waste Steam to Run Vapour-Absorption Refrigeration System

7.8.8

Enhance Heat Transfer

7.8.9 Proper Selection of Steam Trap

40

479 1162 2375 4536 8454

135

136

Handbook of Energy Audit

7.8.10

Use of Vapour Recompression

7.8.11

Use of Dry Steam

Table 7.11

Steam traps

Type of steam trap

Working-principle subcategory

Inverted bucket The mechanism consists of steam trap an inverted bucket attached by a lever to a valve. Under normal conditions, the bucket hangs down, pulling the valve off its seat. Condensate flows under the bottom of the bucket filling the body and flowing away through the outlet. When steam accumulates below the bucket, it raises it and lifts the lever and thereby shuts the outlet. It remains off till the steam condenses or vents off.

Cut-section image

Features

Outlet

Orifice Bleed hole Inverted bucket

Inlet

It can withstand high pressure. It has good tolerance to water-hammer condition. It can be used in superheated steam lines. It fails in open mode so it’s safe. Small hole size discharges air very slowly. Not suitable for fluctuating pressure applications.

Energy Audit of Steam-Distribution Systems

Type of steam trap

Float-type mechanical steam trap

Working-principle subcategory

Cut-section image

The ball float-type trap operates by sensing the difference in density between steam and condensate. The condensate accumulating in the valve chamber lifts the valve off from its position and releases condensate. New versions have thermostatic air vents for automatic release of air.

Thermodynamic In this robust and simple steam trap trap, dynamic effect of flash steam is utilized. During start-up, the steam pressure raises the disc and cool condensate and air is discharged. When flash-steam pressure builds up above the disc, it is forced down and sealed. Condensation of steam reopens the valve. Balanced The operating element is a pressure steam capsule containing a special trap liquid and water mixture whose boiling point is below water. The capsule is in relaxed condition at cold temperature. As the condensate passes through it, the liquid in the capsule expands and valve shuts. Heat loss from the trap cools the water surrounding the capsule and restores original position.

137

Features

It ensures continuous discharge of steam; hence, suitable for high rate of heat-transfer applications. Linear behaviours for all types of condensate load and not affected by fluctuations in mass-flow rate and pressure; it is water-hammer resistant. A valve operates best in its range of pressure difference for higher pressure difference; it will close and will not pass condensate. Long service life, compact, Peripheral outlets simple; and large capacity. It can work in waterhammer and vibration, easy to maintain. It will not work in low differential pressure.

Open

Valve open Closed

Vaporised fill

Small, lightweight, and has a large capacity. Valve is full open during start-up condition allowing maximum condensate removal. Simple to maintain. It may damage by waterhammer or corrosion at long run. It will not open until the condensate temperature drops below steam temperature.

Contd

138

Handbook of Energy Audit

Type of steam trap

Working-principle subcategory

Cut-section image

Features

Open

Bimetallic steam It is made of two dissimilar trap metal strips welded together. The element deflects when heated.

Compact, open while start-up, can withstand water-hammer and corrosive condensate and high steam pressure. It does not respond quickly to change in load or pressure because the element is slow to react.

Closed

A single bimetal strip may not meet required power; hence, a large mass is required.

Impulse steam trap

It consists of a hollow piston (A) with a piston disc (B) and both are placed in a tapered piston (C). The valve is lifted up in case of accumulation of steam.

Labyrinth steam It consists of a series trap of baffles which can be adjusted by a handwheel. Hot condensate passing between the baffle and trap casing expands and drops in pressure.

Source:

F A D

Condensate in

B C E

It can work for a wide range of pressure. It is good at venting air. Tight shut-off is not possible as some steam continuously leaks Condensate out through the vent. Extremely small clearance is easily affected by dirt.

Condensate in

Condensate out

Small and compact and have less chances of mechanical failure. Manual adjustment is required.

Energy Audit of Steam-Distribution Systems

CHECKLIST

Housekeeping Checklist

139

140

Handbook of Energy Audit

Some Retrofits

THUMB RULES

`

Descriptive Questions

Short-Answer Questions

Energy Audit of Steam-Distribution Systems

Numerical Problems

¢ ¢

Multiple-Choice Questions

141

142

Handbook of Energy Audit

` ` Answers 1. 8. 15.

` `

2. 9. 16.

3. 10.

4. 11.

5. 12.

6. 13.

7. 14.

8 Compressed Air System

Energy cost, 73 %

Installation cost, 2 %

Maintenance cost, 7 % Initial cost, 18 %

Figure 8.1 Cost distribution

instrument air

Table 8.1

Applications of compressed air

Name of industry

Type of application

Automobile

Tool powering, controls, actuators, conveying

Textile

Agitation, tool powering, controls, actuators, conveying

Contd.

144

Handbook of Energy Audit

Name of industry

Type of application

Chemical and pharmaceuticals

Controls, actuators, conveying

Food

Dehydration, bottling and packaging plants, spraying, cleaning, controls, actuators, conveying

Wood and furniture

Sawing, hoisting, clamping, tool powering, spraying, controls, actuators

Fabrication and manufacturing

Clamping, stamping, tool powering, cleaning, controls, actuators, injection moulding, spraying

Petroleum

Gas compressing, controls, actuators

Pulp, paper, rubber, plastic

Controls, actuators, conveying, tool powering, clamping, forming, injection moulding

Agriculture

Spraying pesticides, material-handling

Mining

Pneumatic tools, hoists, pumps, controls, actuators, conveying

Gas-power plants

Starting gas turbines, controls, actuators

Transportation

Pneumatic tools, hoists, air brakes

Miscellaneous applications

Service industries, water-treatment plants, recreation, etc.



8.1

CLASSIFICATION OF COMPRESSORS

Compressor

Positive displacement

Reciprocating

Continuous flow

Rotary

Ejector

Dynamic

Centrifugal flow

Single acting

Screw

Double acting

Scroll

Axial flow

Diaphragm

Vane

Mixed flow

Lobe

Chart 8.1 Classification of compressors

Compressed Air System

� 8.2.1

8.2

145

TYPES OF COMPRESSORS

Positive-Displacement Compressors

reciprocating compressor rotary compressor

8.2.2

Continuous-Flow Compressors

centrifugal compressor

8.2.3

Reciprocating Air Compressors (1 CFM to 6300 CFM)

146

Handbook of Energy Audit

oil-free compressors

Suction valve (discharge valve on opposite side) Piston

Discharge valve

2nd stage

Suction valve

Air inlet 1st stage

1st stage

Crankcase oil dipstick

Connecting rods

Oil sump Crankshaft

Figure 8.2

Reciprocating compressor

Compressed Air System

Thermodynamics of a Reciprocating Air Compressor p pv

p pv

Isothermal work Actual work

Volume of air inhaled Stroke volume V 1- c Vs

hv

È ÍÊ p2 ˆ ÍÁË p1 ˜¯ ÍÎ

Vs

Vc

()

˘ - 1˙ ˙ ˙˚

1 n

n Discharge valve will close at end piston stroke E

D

V

Valve open

dp Compression line

P2 Re-expansion line

Intake valve open V2

B

C P1

O V1 Volume

Figure 8.3

8.2.4

pv diagram of a reciprocating air compressor

Rotary Screw Compressors (30 CFM to 3000 CFM)

147

148

Handbook of Energy Audit

Shaft seals Timing gears

Cooling jackets

Anti-friction and roller bearings

Figure 8.4

8.2.5

Asymmetric rotors

Rotary screw compressor (See color figure)

Vane Compressor (40 CFM to 800 CFM)

Air in

Air out

Figure 8.5 Vane compressor

Compressed Air System

8.2.6

Centrifugal Compressors (400 CFM to 15000 CFM)

Figure 8.6 Centrifugal compressor



8.3

COMPRESSED AIR-SYSTEM LAYOUT

149

150

Handbook of Energy Audit Air receiver (main)

Primary filter

Pre-filter (dryer) Auto drain

Compressor

Dryer After-filter (dryer)

Ring main Branch line

Drain line system Main trunk line

Air receiver (local) user process Oil/water (large intermittent demand for compressed air) separator

Figure 8.7



8.4.1

8.4

Compressed air layout

ENERGY-SAVING POTENTIAL IN A COMPRESSED-AIR SYSTEM

Analyze Compressed-Air Quality and Quantity Need

oversized compressors

Compressed Air System

8.4.2

151

Inappropriate Use of Compressed Air

Table 8.2

Alternatives of compressed air Inappropriate use

Alternative

Cooling, drying, cleaning, draining compressed air lines, clearing jams

Brush, broom, dust collector, blower, fan

Aerating, agitating, oxygenating, percolating

Mixtures and low-pressure blowers

Aspirating

Low-pressure blowers

Atomizing in fuel oil

Low-pressure blowers

Vacuum generation in ejector

Vacuum pump

8.4.3

Leakage in a Compressed-Air System

Table 8.3

Cost estimation of leakage Size of leakage

Energy cost per year in rupees



1/16≤

62,760



1/8≤

2,51,400



1/4≤

10,05,840

152

Handbook of Energy Audit

Leak-detection Methods Ultrasonic acoustic leak detectors soap solution

isolation valve

Step 1: Step 2: Step 3: T¥

T+t

T t

Step 1: Step 2: Step 3: Step 4: Step 5:

P bar. P bar. T V¥ P –P

8.4.4

Pressure Drop in a Compressed-Air System

pressure drop

¥T

Compressed Air System

8.4.5

Controls of a Compressed-Air System

Individual Compressor Controls

Modulating or Throttling Control

Multiple Compressor Control

153

154

Handbook of Energy Audit

8.4.6

Compressed-Air Storage

T ¥ C ¥ Pa P1 - P2 T Pa P 8.4.7

Step 1: Step 2: Step 3: Step 4: Step 4: Step 5:

Regular Maintenance

P

C is

Compressed Air System

∑ ∑ ∑ ∑ ∑ ∑ ∑ ∑ ∑ ∑ 8.4.8

Heat Recovery in Compressed-air Systems

¥

CHECKLIST

¥

¥

¥ ¥

¥

155

156

Handbook of Energy Audit

THUMB RULES 3

Descriptive Questions

Short-Answer Questions

Compressed Air System

Fill in the Blanks

Multiple-Choice Questions

157

158

Handbook of Energy Audit

Answers Fill in the Blanks 4. 5.

1. 2. 3. Multiple-Choice Questions 1. 2. 8.

3.

4.

5. (a)

6.

7. (a)

9

Energy Audit of HVAC Systems

-



9.1

INTRODUCTION TO HVAC

In institutional, commercial, and residential buildings, air-conditioning systems are mainly for the occupants’ health and comfort. They are often called comfort air-conditioning systems. In manufacturing buildings, air-conditioning systems are provided for product processing or for the health and comfort of workers as well as processing and are called processing air-conditioning systems. Cold storages are used for food preservation. Most refrigeration systems used for air-conditioning are vapour-compression-cycle-based systems. Vapour absorption is still more popular where waste heat is available and high initial cost is allowable. Air-expansion refrigeration systems are used mainly in aircraft and cryogenics (lowtemperature refrigeration). Basic processes of air-conditioning systems are mentioned here: 1. Sensible cooling 2. Sensible heating 3. Humidifying 4. Dehumidifying 5. Air cleaning 6. Air change 7. Air movement In sensible cooling and heating processes, heat is removed or added in conditioned space to maintain the temperature. and are processes of adding or removing water vapour from the air. Air cleaning is removing dust and other particulates, biological contaminants to maintain air quality. Air change is the process of exchanging air between the outdoor and indoor to maintain oxygen level, air quality, and freshness. Air movement is to control air circulation. Out of the basic seven processes, the climate decides the required processes which may again vary throughout the year depending on whether the climate is hot and humid or cool and dry.

160



Handbook of Energy Audit

9.2

COMPONENTS OF AN AIR-CONDITIONING SYSTEM

Outside Air Damper It regulates outside air intake. The arrangement is provided which closes off the outside air intake when the system is switched off as well as when the power is off. It is also Mixing Chamber air) in this chamber.

Air returning from the room mixes with the outside fresh air (ventilation Return air from the space

Outside air

Fan

Humidifier

Cooling coil

Filter

Figure 9.1

Heating coil

Outside air damper

Conditioned supply air to the space

Mixing chamber

Schematic of an air-conditioning system

Figure 9.1 shows the basic components of an air-conditioning system. Filter so that it cleans the return air and the ventilation air. It also prevents heating and cooling coil across it. Heating and Cooling Coils The heating coil increases air temperature and the cooling coil thermostats. It adds moisture and is controlled by a humidistat. Fan It supplies air to the space though a duct. �

9.3

TYPES OF AIR-CONDITIONING SYSTEMS

In commercial and residential buildings, air-conditioning systems are used for residents’ health and comfort; hence, they are called comfort air-conditioning systems. In manufacturing buildings and processes, air-conditioning systems are provided for product, process, or workers’ health and comfort, and are called process air-conditioning systems. Based on their size, construction, and

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161

Air conditioning

Individual system

Space air conditioning

Evaporative cooling air conditioning

Desiccant based air conditioning

Thermal storage air conditioning

Clean room air conditioning

Central air conditioning

Chart 9.1 Classification of air-conditioning systems

Individual systems are commonly known as window, split, or package air conditioners. Window air conditioners are installed in a window or through a wall, while in a split or package air conditioner, indoor and outdoor units are mounted separately. An outdoor condensing unit consists of a compressor and condenser, and an indoor air handler is located at a more advantageous location with reduced noise level. Individual systems are factory-assembled units. Individual systems have main components like, evaporator, compressor, condenser, capillary evaporator, the refrigerant evaporates and absorbs room heat directly; hence, it is known as direct expansion (DX) coil. The system schematic is shown in Figure 9.2. Supply outlet Room air conditioner

Return grille

Figure 9.2

Individual air-conditioning system

Space air-conditioning systems by an evaporator and fan coil, a heat pump or another device within or outside the conditioned space. It usually has a short-supply and no-return ducts. Space air-conditioning systems are usually employed with a separate outdoor ventilation air system to provide outdoor air for the occupants in the conditioned space. Evaporative-cooling air-conditioning systems use the cooling effect of the evaporation of liquid water to cool an airstream directly or indirectly. When an evaporative cooler provides only a portion of the cooling effect, it becomes a component of a central hydronic or a packaged unit system. or indirect-contact heat exchanger, exhaust fan, water sprays, reticulating water pump, and water sump. An evaporative cooling system consumes low energy as compared to vapour-compressionbased air-conditioning systems due to absence of a compressor, but it can perform well only in dry atmosphere.

162

Handbook of Energy Audit Wet side air fan

Spray nozzle manifold Moisture separators Stainless steel housing

Air filter

Heat exchanger Supply air fan

Water sump Wet side air filter

Figure 9.3

Evaporative cooling system

A desiccant-based air-conditioning system is a system in which latent cooling is performed by a considerable part of expensive vapour-compression refrigeration is replaced by inexpensive evaporative cooling. A desiccant-based air-conditioning system is usually a hybrid system of There are two airstreams in a desiccant-based air-conditioning system: a process airstream and a regenerative airstream. Process air can be all outdoor air or a mixture of outdoor and recirculating air. Process air is also conditioned air supplied directly to the conditioned space or enclosed manufacturing process, or to the Air-Handling Unit (AHU), Packaged Unit (PU), or terminal for further treatment. Regenerative airstream is a high-temperature airstream used to reactivate the desiccant. A desiccant-based air-conditioned system consists of the following components: rotary desiccant

and piping. In a thermal storage air-conditioning system, the electricity-driven refrigeration compressors are operated during off-peak hours. Stored chilled water or stored ice in tanks is used to provide cooling in buildings during peak hours when high electric demand charges and electric energy rates are in effect. A thermal storage system reduces high electric demand for HVAC&R and partially or fully shifts the high electric energy rates from peak hours to off-peak hours. A thermal storage airconditioning system is always of central air-conditioning type. Further details of thermal storage type of air-conditioning systems are given in Section 9.8.18. Clean-room or clean-space air-conditioning systems serve spaces where there is a need for critical control of particulates, temperature, relative humidity, ventilation, noise, vibration, and space pressurization. In a clean-space air-conditioning system, the quality of indoor environmental control directly affects the quality of the products produced in the clean space.

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163

A clean-space air-conditioning system consists of a recirculating air unit and a make-up air piping work, pumps, refrigeration systems, and related controls. A central hydronic air-conditioning system or central air-conditioning system uses a central zones of conditioned space. The heat capacity of water is 3000 times higher than that of air; hence, or cool the conditioned space. However, the system becomes more complicated and expensive for small size.

Cooling tower Ppump.ct

Tcond.set Condenser

Expansion valve

Pchiller

Chiller

Compressor Tchw.set

Evaporator Main water loop Cooling oil

Filter Tspa.set

Supply fan

Ventilation air

Figure 9.4



9.4

Central air-conditioning system

HUMAN COMFORT ZONE AND PSYCHROMETRY

which is achieved by obtaining heat balance between persons and their surrounding environment. A person generates heat by digestion of food (metabolism) and loses heat by conduction, convection, radiation, and evaporative cooling (by perspiration) which is the primary heat-loss mechanism. It is a known fact that only 20% of the food we digest is converted into energy and the rest is wasted in heat or any other form. There are many parameters which affect the amount of heat released by our bodies, namely, activity of a person, surrounding atmospheric temperature and humidity, air motion, clothing, metabolic rate, etc. Human comfort can be achieved at air temperatures between about 20ºC and 26.6ºC, and relative humidity between 20% and 70%, under varying air velocities and radiant surface temperatures. Figure 9.5 shows the generalized “comfort zone” for summer and winter weather.

164

Handbook of Energy Audit 90° 80° 70°

90

er

m

70

60

fo

%

7 8 0 % 9 94 4 8 6 8 4 75 6 6 34 0

p. m te 0 e tiv 6

m co

10

60% 50%

80

40%

75

30% 20%

66

10%

80

c fe Ef 5 5

75 table fer m

71

50

63 60

40

55 50

o RH

50 65 75 84 97 97 81 65 48

Wet bulb temperature, deg. F

m Su

m co

r fo

(Relative humidity)

rt

80

e bl

ta

ne zo

0%

%

Wi

60

o

or mf

e

on

tz

rc

nte

%

co

70 80 90 Dry bulb temperature, deg, F

Figure 9.5

100

Human comfort chart

Psychrometry Air is a mixture of gasses and water vapour. Dry air is made of nitrogen, oxygen, and minute portions of other gases. The amount of water vapour varies greatly for different locations and weather conditions. Air obeys Dalton’s law which states that “Total barometric pressure is the summation of pressure exerted by dry gases and partial pressure exerted by water vapour”. Psyhrometric terms are explained here. Dry-bulb temperature is measured by a standard thermometer with a dry-sensing bulb. Wet-bulb temperature is measured by a thermometer using a sensing bulb covered with a wet wick and the thermometer is rotated in air. Moving of the thermometer in air makes the water evaporate from the wick, absorbing latent heat of evaporation from the wick, which lowers bulb temperature. The amount of evaporation is decided by the relative humidity of air. An instrument measuring dry-bulb and wet-bulb temperatures is known as a sling psychrometer (Figure 3.4 in Chapter 3). Relative humidity is the ratio of the amount of water vapour present in the sample air and the amount of water vapour in saturated air. Knowing dry-bulb and wet-bulb temperatures of air, relative humidity can be obtained and is expresses as % RH. �

9.5

VAPOUR-COMPRESSION REFRIGERATION CYCLE

The vapour-compression refrigeration cycle is the most common cycle based on which most HVAC devices work. It consists of four basic components, namely, compressor, condenser, evaporator,

Energy Audit of HVAC Systems

165

and expansion valve. In an ideal vapour-compression refrigeration cycle, the refrigerant enters the compressor as a saturated vapour and is compressed isentropically. Compressed vapour is cooled in a condenser to the saturated liquid state and then expands from high pressure to low pressure in the expansion device. A mixture of the refrigerant liquid and vapour comes out of the expansion of evaporation, which is known as cooling effect. Schematic arrangement of vapour-compression refrigeration cycle and thermodynamic representation on ph and Ts diagrams are shown in Figures 9.6 and 9.7 respectively. Condenser

3

2 Compressor

Expansion valve Evaporator 4

Figure 9.6

1

Schematic of vapour-compression refrigeration cycle 2

3

p

2 T3

4

h3 = h4

Figure 9.7

9.5.1

1

T4

3

1

4

s4

h1

s1

Thermodynamic representation of vapour-compression refrigeration cycle

Performance of Vapour-Compression Refrigeration Cycle

Table 9.1 shows the thermodynamic nature of processes in all the components of a vapourcompression refrigeration cycle. Table 9.1 Process

Processes of vapour-compression refrigeration cycle Component

Thermodynamic nature

Steady-flow analysis

1-2

Compressor

Isentropic compressions = constant

Win = m(h2 – h1)

2-3

Condenser

Isobaric condensation

Qh = m(h3 – h2)

3-4

Expansion valve

Isenthalpic expansion

h4 = h3

4-1

Evaporator

Isobaric evaporation

Qr = m(h1 – h4)

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Handbook of Energy Audit

The performance of the same is measure in terms of COP as given in Equation (9.1). QR h1 - h4 COPR = = Win h2 - h1

(9.1)

Here, QR is refrigeration effect (amount of heat removed in evaporator) and Win is work input to the compressor. 9.5.2

Parameters Affecting the Performance of Vapour-Compression Refrigeration Cycle

The vapour-compression refrigeration cycle discussed in the earlier section is an ideal cycle and the actual cycle is affected by several parameters like evaporator pressure, condenser pressure, subcooling, superheating, etc. The refrigerant coming out of the condenser is usually subcooled to a temperature lower than the saturated temperature corresponding to the condensing pressure of the refrigerant, shown in Figure 9.8. This increases the refrigerating effect. The degree of subcooling depends mainly on the temperature of the coolant (e.g., atmospheric air, surface water, or well water) during condensation and the construction and capacity of the condenser. Subcooling

p

2



p

3

2

3



1

4

h

Figure 9.8

1 Superheating

4

h

Effect of subcooling and superheating on vapour-compression refrigeration cycle

The refrigerant vapour at the suction of the compressor is slightly superheated which ensures dry compression in compressor, and if the superheating process is occurring in the last few coils of the evaporator, it increases the refrigerating capacity of the system. Thus, subcooing and superheating are advisable for better performance of vapour-compression refrigeration system. A typical ph chart for R134a refrigerant is shown in Figure 9.9. decreases the capacity of the reciprocating compressor and increases the power consumption per unit refrigeration. Likewise, increase in condenser pressure decreases refrigeration capacity and power consumption increases. Thus, both these operating conditions are not advisable. For multiple temperature applications like cold storages, dairy industry, etc., multistage vapour valves, etc.

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167

R-134a

S = 2.0

T = 90 T = 80 T = 70 T = 60 S = 2.1

T = 50 T = 40

1 0.9 0.8 0.7

T = 30 T = 20

0.6 0.5

T = 10

0.4

T=0

0.3

T = 110

T = 20

T = 130 T = 120

T = 10

0.2

T = 200 T = 190 T = 180 T = 170 T = 160 T = 150 T = 140

Pressure [MPa]

S = 1.8

S = 1.7

S = 1.6

S = 1.5

S = 1.3

S = 1.1

S = 1.0

S = 0.9

2

S = 1.2

4 3

S = 1.9

R-134a Pressure-enthalpy diagram s = specific entropy, kJ/kg¢K T = Temperature ° C

S = 1.4

10 9 8 7 6 5

0.1 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560

580 600

Enthalpy [kJ/kg]

Figure 9.9

9.5.3

ph chart of refrigerant R134a

Parts of a Vapour-Compression Refrigeration Cycle

The refrigerant vapour entering the compressor is compressed to high pressure by a reciprocating, scroll, screw or centrifugal compressor, out of which the reciprocating scroll and screw are positivedisplacement type and the centrifugal compressor is of dynamic type. Basics of compressors available in capacity of 0.5 ton to 200 ton and can handle compression ratio of 10 to 12. For small systems, hermetically sealed reciprocating compressors are used in which the compressor and motor are directly coupled and housed in a single unit. Open compressors are more suitable for large systems. Low initial cost is the advantage of a reciprocating compressor; at the same time, it requires frequent maintenance. Centrifugal compressors are variable-volume displacement units of open as well as hermetic types. They are available from 90- to 2000-ton capacity. The main advantage of centrifugal

Screw compressors are positive-displacement-type machines and are of single-screw, twinscrew, oil-type or oil-free type. Their capacity range is 20 to 1000 tons and they operate at high

168

Handbook of Energy Audit

compression ratio. Main advantages of screw compressors are they are compact, lightweight, silent, Condenser Compressed high-pressure and high-temperature refrigerant vapour comes to the condenser, where it is condensed to liquid state by removing its latent heat and subcooled by removing sensible heat. Air or water is used to remove heat of the refrigerant. Both have their inherent advantages and allocations. Air-cooled condenser does not require water, simple and less maintenance is involved but works at higher condensation temperature and air having less heat-carrying capacity requires more heat-transfer surface area. Proper air circulation and regular cleaning are essential in air-cooled condensers.

water is used to condense the refrigerant while in a close-circuit water-cooled condenser, a cooling tower is required which adds to initial as well as operating cost of the plant. Mostly, a shell-and-tube arrangement is used for a water-cooled condenser. Expansion Valve the function of an expansion valve is to meter the liquid refrigerant in the evaporator and maintain a pressure difference between the condenser and evaporator. Different expansion valves used in the HVAC industry are hand valve, capillary tube, etc. Water outlet

Safety valve connection

Water inlet

Front cover

Figure 9.10

Service socket

Refrigerant outlet connection

Liffting lug

Heat exchange tubes

Air-cooled and water-cooled condensers (Source: Alfa laval)

Refrigerant inlet connection

End cover

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169

A capillary tube is the simplest expansion device to produce pressure difference. It is made of a small-diameter tube and is suitable for company-assembled devices like refrigerator, water cooler, display type cabinets, window air conditioners, etc. It cannot regulate the amount of refrigerant so The most common expansion device is the thermostatic expansion valve which can control the more internal port, it is able to balance pressure more accurately and is known as a balanced expansion valve. Evaporator Refrigerant evaporates and absorbs latent heat of evaporation from the surroundings in an evaporator. An air-cooled evaporator may be of natural circulation type or forced circulation type. Liquid-cooled heat exchangers are shell-and-tube type or plate-type. ShellRefrigerant The refrigerant plays the role of absorbing and transmitting heat in a vapourcompression refrigeration system. Most common desirable properties of a refrigerant are pressuretemperature relationship (it should not have excessively low pressure in the evaporator and high pressure in the condenser), freezing point, chemical stability, toxicity, ozone-depletion potential, global warming potential, and cost. CFCs were popular refrigerants in the last century and they have now been replaced with HFCs and HCFCs to save the environment. In addition to the listed components, controls, thermostats, high-pressure–low-pressure switches, relief valves, oil separators, solenoid valves, accumulators, dehydrators, insulations, etc., complete a vapour-compression refrigeration system. �

9.6

ENERGY USE INDICES

According to ASHRAE standards, following are the current energy-use indices for refrigeration compressors, packaged units, heat pumps, and chillers: input in kW, at any given set of rating conditions. COP =

Refrigeration effect kW Work input kW

(9.2)

device, in W, under designated operating conditions. EER =

Refrigeration effect BTU/hr Work input W

(9.3)

Work input kW Refgireration effect ton

(9.4)

refrigeration effect.

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Handbook of Energy Audit

4. Integrated Part Load Value (IPLV) is a single index of merit that is based on part-load EER heat pumps based on the weighted operation at various load capacities. Table 9.2

Relation between COP, EER, and kW/ton

COP

EER

kW/ton

1.76

6

2.0

2.34

8

1.5

2.93

10

1.2

3.56

12

1.0

4.39

15

0.8

5.86

20

0.6

8.89

30

0.4

IPLV = 0.01A + 0.42B + 0.45C + 0.12D where, A = COP or EER at 100% capacity B = COP or EER at 75 % capacity C = COP or EER at 50 % capacity D = COP or EER at 25 % capacity �

9.7

(9.5)

IMPACT OF REFRIGERANTS ON ENVIRONMENT AND GLOBAL WARMING

The surface of the earth is surrounded by a layer of air, called the atmosphere. The lower atmosphere is called the homosphere, and the upper atmosphere is called the stratosphere. In the mid-1980s, (CFCs) were widely used as refrigerants in mechanical refrigeration systems, to produce thermal insulation foam and to produce aerosol propellants for many household consumer products. CFC-11 (CCl3F) and CFC-12 (CCl2F2) are commonly used CFCs. They are very stable. Halons are also halogenated hydrocarbons. If CFCs and halons leak or are discharged from a refrigeration system during operation or repair to the lower atmosphere, they will migrate to the upper stratosphere and decompose under the action of ultraviolet rays throughout decades or centuries. The free chlorine atoms react with oxygen atoms of the ozone layer in the upper stratosphere and cause a depletion of this layer. The theory of the depletion of the ozone layer was may cause skin cancer, a serious threat to human beings. 1996, actions have been taken to ban the production of CFCs and halons before it is too late. A cloudless homosphere is mainly transparent to short-wave solar radiation but is quite opaque to long-wave infrared rays emitted from the surface of the earth. Carbon dioxide (CO2) has the greatest blocking effect of all; water vapour and synthetic CFCs also play important roles in blocking the direct escape of infrared energy. The phenomenon of transparency to incoming solar radiation and blanketing of outgoing infrared rays is called the greenhouse effect. The increase of the CO2, water

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vapour, CFCs, and other gases, often called greenhouse gases (GHGs), eventually will result in a rise in air temperature near the earth’s surface. This is known as the global warming effect. �

9.8

ENERGY-SAVING MEASURES IN HVAC

As an HVAC system is a tailor-made system designed and manufactured to meet the requirement of a particular end user, its audit will also vary for different end users. In general, the methodology to audit an HVAC system is given in Chart 9.2. It includes inspection and evaluation of HVAC

Check the HVAC system capacity of the building

Visually inspect the plant and monitor maintenance schedule

Reduce internal load

Use BMS

Improve insulation

Change set temperatures

Add solar shading

Change filters

Calculate savings due to energy saving measures taken up

Chart 9.2

9.8.1

Hierarchy of HVAC system audit

CAV vs VAV

A Constant Air Volume (CAV) system provides a constant amount of supply air, conditioned at proper temperature to meet the thermal loads in each space based on a thermostat setting. Either mixing cooled air with heated or bypassed air or directly reheating cooled air is used to control the partial load conditions. Different types of CAV systems used presently are described below: CAVs with terminal reheat systems which require the circulated air to be cooled to meet design thermal loads. If partial thermal load conditions occur, reheat of pre-cooled air is required. CAV systems with terminal reheat in interior spaces and perimeter induction or fan-coil units For these systems, the energy waste is reduced at the perimeter spaces, since a large portion of the air supplied to the perimeter spaces is re-circulated within each space by either induction or fan-coil units. All-air induction systems with perimeter reheat The induction units accept varying amounts of warm return air to mix with primary air for temperature control. The energy waste due to reheat is small for these systems. However, extensive static pressure control is required at the terminals.

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CAV double-duct systems which have a cold-air duct and a hot-air duct. Mixing cold air with hot air proportionally to meet the thermal load of the space controls the supply-air temperature. Energy waste occurs during partial thermal load conditions when mixing is needed. Variable Air Volume (VAV) systems provide a variable amount of supply air, conditioned at a constant temperature to meet the thermal loads in each space based on thermostat setting. The air volume is controlled using outlet dampers, inlet vanes, and variable speed drives. Only cooled air is supplied at the central AHU while reheat is provided in each space depending on the thermal types are: VAV systems with terminal reheat which reduce the amount of air supplied as the cooling load lowers until a preset minimum volume is reached. At this limit, reheat is provided to the supply air to meet the thermal load. Because of this volume reduction, reheat energy VAV systems with perimeter heating units providing only cooling since heating is performed by other systems, such as hot-water baseboard units. The heating units are controlled by outside air temperature, since the perimeter heating load is a function of the transmission losses. VAV double-duct systems which have cold-air and hot-air ducts and operate in a similar way to VAV systems with terminal reheat. As the cooling load decreases, only cold air is supplied until a preset minimum volume is reached. At this limit, the hot air is mixed with the cold airstream.

effective energy-conservation measure for HVACs. However, energy saving can also be considered, even if the existing system is a VAV. The potential for energy saving in HVAC systems depends on several factors, including their design, the method of operation, and their maintenance. 9.8.2

Optimize Ventilation Air

where it is used to provide fresh air to occupants, and industrial facilities, where it is used to control the level of dust, gases, fumes or vapours, especially in locations with extreme weather conditions. The auditor should estimate the existing volume of fresh air and compare this estimation to the amount of ventilation air required by the appropriate standards and codes. loads. Some energy-conservation measures related to ventilation are described here. However, in may actually reduce cooling and heating loads through the use of airside economizer cycles. The potential of energy savings attributed to economizers is also discussed here. First, evaluate the existing level of ventilation air through a mechanical system. The tracer-gas or enthalpy-balance technique can be used to determine the amount of fresh air entering a room. Once the existing ventilation air is estimated, it has to be compared to the ventilation requirements

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by the applicable standards. Table 9.3 gives ventilation-air requirement for some selected spaces in reduce the same. Table 9.3

Ventilation-air requirement

Type of area

Room

Ventilation air flow (m3/h per person)

17–26

Washrooms

51–85

Corridor

12–17

Public area

17–26

Meeting room

34–51

Dining room

26–34

Kitchen

60

Another method to control ventilation air is using CO2 sensors, as CO2 present in the room indicates pollutant level in the room. A damper controller receives signals from the CO2 sensor and The calculation of the energy saving by reducing ventilation air is given in Equation (9.6) for heating and (9.7) for cooling. 3.6 ra C pa Nh (Voa , E - Voa , R )(Ti - To ) (9.6) Units saved in heating = hh Nh represents the number of operating hours in where ra is density of air, Cpa heating mode, Voa,E and Voa,R represent existing and reduced ventilation air, Ti and To represent temperature of air inside and outside and hh 3.6 ra Nh (Voa , E - Voa , R ) D Hc Units saved in cooling = (9.7) EER where ra is density of air, Nh represents number of operating hours in cooling mode, Voa,E and Hc represents enthalpy difference of outside Voa,R and inside air, and EER Apart from reducing ventilation air, other suggestions are listed below: 1. Use low-leakage dampers which restrict leakage to 1% compared to standard dampers which allow 5 to 10% leakage when closed. 2. Use controls to shut off ventilation air during no-occupancy periods.

doors and windows, accumulation of fumes, odour, dirt and dust, etc. 9.8.3

Use of Variable-Speed Drive

In India, most HVAC systems are designed to keep the building cool on the hottest days and, therefore, the HVAC system needs to work at full capacity only on the 20 to 30 hottest days during

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the year. On the other 335 days, the HVAC system can operate at a reduced capacity. This is where a variable air-volume system with variable speed drives (also called variable-frequency drives, or

used. If a building uses a constant-volume air-handling system with no variable-speed drives, the the appropriate rooms does not control the speed of the motor and does not save energy as well. Following components if driven through variable-speed machines will able to save energy. 1. Centrifugal air-handler fans 2. Centrifugal exhaust fans 3. Centrifugal chilled-water pumps 4. Centrifugal hot-water pumps 5. Cooling-tower pumps 6. Cooling-tower fans The following example shows the amount of energy saved with a variable-speed drive. EXAMPLE 9.1 A 50 hp fan needs to supply air 10 hours/day for 250 days. The cost of running the fan at full speed would be 50 hp ¥ 0.746 kW / hp 2500 hrs ¥ ` 6 / kWh = ` 5, 59, 500 It is assumed that the fan runs at different speeds during the year as per the given schedule: 25% of the time at 100%; 50% of the time at 80%; 25% of the time at 60%. Solution % rated speed Days (% of total days)

Cost calculation

Cost, ₹

100

62.5 days (25 %)

50 hp ¥ (1.0) ¥ 0.746 kW / hp ¥ 625 hrs ¥ ` 6 / kWh

1,39,875

80

125 days (50 %)

50 hp ¥ (0.8) ¥ 0.746 kW / hp ¥ 1250 hrs ¥ ` 6 / kWh

1,43,232

60

62.5 days (25 %)

50 hp ¥ (0.6) ¥ 0.746 kW / hp ¥ 625 hrs ¥ ` 6 / kWh

30,213

3

3

3

Total Cost

3,13,320

Potential saving in the 50 hp pump for a year = ` 5,59,500 – `3,13,320 = `2,46,180 The average payback period of a variable-frequency drive is 18 to 24 months but it also depends on size, type, and operating hours. The lifespan of an HVAC equipment is 15 to 25 years and, hence, adopting a variable-frequency drive will give substantial return. Online payback calculators are available from various variable-frequency-drive manufacturers.

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system run by a VFD increases the comfort of the building and reduces equipment-maintenance costs and downtime. It also reduces the long-term wear and tear on equipment. The drives provide a soft start instead of slamming motors at full speed, so HVAC systems last longer, requiring less maintenance and causing fewer instances of unscheduled downtime. 9.8.4

Replace Existing Chiller

a multicompressor, variable-speed centrifugal chiller, or a scroll compressor chiller. 1. Multiple compressor chillers can be reciprocating, screw, or centrifugal, with capacities in part-load conditions. A multicompressor chiller can save up to 25% of the energy of a single compressor chiller. 2. Variable-speed compressor chillers are, in general, centrifugal and operate with variable head pressure using variable-speed motors; therefore, they work best when their cooling load is most of the time below the peak. Their typical capacity is in the range of 500 to 2500 kW. It is reported that chillers with variable-speed compressors can reduce the cooling energy use by almost 50%. scroll and an orbiting scroll, both needed to compress and increase the pressure of the heat loss between the discharge and the suction gases is reduced. The following example shows payback calculation of chiller replacement. EXAMPLE 9.2 An existing chiller with a capacity of 800 kW and an average seasonal COP of 3.5 is to be replaced by a new chiller with the same capacity but with an average seasonal COP of 4.5. Determine the simple payback period of the chiller replacement if the cost of electricity is `6 / kWh and the cost differential of the new chiller is ` 7,50,000. Assume that the number of equivalent full-load hours for the chiller is 1000 per year, both before and after the replacement. Solution: Ê QNh Lf ˆ - Ê QNh Lf ˆ (9.8) Energy Saving = Ë COP ¯existing Ë COP ¯retrofit Q stands for cooling capacity, Nh stands for working hour, Lf performance. `3,04,800. If a new chillier is costing `7,50,000 then simple payback time is less than two and a half years.

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Before replacing an existing chiller, some proven recommendations for existing chillers are the following: 1. Set the chiller water at the highest possible temperature to increase COP of the system. 2. Decrease condenser-water temperature (for water-cooled condenser) to improve the performance. 3. Increase surface areas of the evaporator and condenser for more effective heat transfer. 4. Enlarge refrigerant lines for lower friction. 5. Carry out ozonation of the condenser water to prevent scaling and biological contamination. 9.8.5

Use of Boost-up Systems or Alternative Systems

Some alternative systems or boost-up systems are suggested here to reduce the cooling load on the existing system: or 1. Use water-side economizers. In favourable weather conditions, water can be cooled by using cooling towers instead of chillers, this cooled water will be circulated through chiller circuits or heat-exchanger coils. 2. Evaporative cooling can be used in dry weather condition in series with chillers. It is discussed in Section 9.8.14. 3. Use desiccant cooling for industrial applications. 4. Subcooling the refrigerant before it enters the expansion device increases refrigeration capacity of the plant for the same amount of power consumption. Subcooling is achieved either by a suction-line heat exchanger or an external heat sink such as a small cooling tower or a ground-source water loop. 9.8.6

Duct-Leakage Repair

and installing proper insulation can reduce up to 30% of energy consumption in an HVAC. Duct leakage increases during summer. To reduce duct leakage, ensure that duct connections are securely fastened and use mastic sealants and gaskets. 9.8.7

Heat-Recovery Wheel

A heat-recovery wheel recovers total energy and assists in meeting all the requirements of Indoor Air Quality (IAQ), humidity control, and energy savings. Incorporation of heatrecovery wheels into the air-conditioning system means more outdoor air at lower energy cost and reduced chiller load. In a typical installation, the wheel is positioned in an airhandling unit so that it is divided into two semicircular sections. Exhaust air passes out through one half and outdoor air enters time, the wheel is rotated. Sensible heat is transferred as the

Figure 9.11

Heat-recovery wheel

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metallic substrate picks up and stores heat from the warmer airstream and gives it up to the cooler one. 1. Heating/cooling energy (e.g. 80%) is always returned to where it came from Heat in Heat out

Cooling energy out

Cooling energy in

2. Moisture and dry air (e.g. 80%) is always returned to where it came from Dry air out Dry air in

Figure 9.12

Heat-flow pattern through a heat-recovery wheel

To control the humidity of air, latent heat is transferred as the desiccant coating on the metallic substrate adsorbs moisture from the airstream that has the higher humidity ratio and releases the moisture into the airstream that has the lower humidity ratio. Advantages of Heat-Recovery Wheel 1. Helps precondition the incoming fresh air 2. Easy to install in existing ventilation systems 3. Helps meet ventilation standards without adding operation cost 4. Maintains humidity level at no additional cost 5. With installation of heat recovery wheel, system capacity reduces from 30 to 65% 9.8.8

Exhaust Fans

9.8.9

Reducing Cooling Load

Figure 9.15 shows a model of a building adopted to reduce heat load on it. Some general areas where cooling loads are reduced are discussed here: 1. Size the air-conditioning system accurately. Estimate the load based on theoretical calculations to reduce the chances of oversizing the units. Consider differant factors like seasonal effects, working cycle, climatic changes, use of ground-source heat pump while designing the same. building. 3. Instead of using central or package air-conditioning systems, use evaporative coolers for

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4. In centrally air-conditioned room areas, certain applications like ovens, kitchens, cleaning rooms adds on the cooling load. Isolate these areas to reduce the load on the system. 5. Cold storages which are mainatined in minus range of temperatures have serious effect on performance due to ice build-up, frost, or frequent openings. Wind curtains and high-speed doors are popularly used solutions. 9.8.10

Operate the System at Higher Evaporator Temperature and Lower Condenser Temperature

The evaporator temperature can be increased by changing process-temperature settings, using larger evaporator-surface area, and keeping the evaporator clean from fouling or frosting. Similarly, to reduce condenser temperature, install a condenser of larger size and use water or evaporative cooled condenser.

Light-colored roof coatings reflect solar radiation and reduce conducting potential

Smaller cooling plant accurately sized to meet the reduced cooling load

Insulating the roof helps decrease heat conduction to the inside of the building

Roof-wetting lowers roof temperature by evaporative and radiative cooling

Structural overhangs light shelves reduce solar gain

Automatic louvers fixed louvers and solar screens block solar radiation Spectrally selective glazings let light in but keep heat out

South

Movable awnings provide shade

Tree block solar radiation and provide cooling benefit throught avapotran spiration

Figure 9.13

Window films reduce solar gain without sacrificing daylight or aesthetics

Methods to reduce cooling load on a building

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The role of the air-distribution system in an HVAC is to bring in fresh outside air to disperse contaminants, to provide free cooling, to transport heat generated or removed by space-conditioning equipment, and to create air movement in the space being conditioned. About 30% of the energy consumed by air-conditioning systems is used to power the fans that drive air distribution. To

to the building. Reducing the friction of distribution system and pressure drop across the system improves the performance. As air has to travel a long path in an air-conditioning system and is occur, selecting components which offer minimum pressure drop will reduce running cost of the will consume less energy. Friction in the fan ultimately turns into heat which is dissipated by the

this system are listed below: reduced. 2. Relatively warmer air is supplied to the room using this system, which improves the 3. Air is supplied to the room from bottom and it moves towards ceiling; hence, heat load of light is carried away by leaving air which reduces effective cooling load and required cooling capacity of the HVAC system. Floor slab

Floor slab Ceiling plenum

Ceiling plenum

Diffuser Floor slab

Floor plenum

Floor slab

Figure 9.14

Conventional and underfloor air-disribution system

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panels makes it easy to relocate the diffuser, wiring, and plumbing to accommodate changes.

and diluting it. slab-to-slab height, reduced capacity of equipment, and reduced ducting. The additional cost system is highly advantageous to buildings where frequenct internal changes are made. In addition, this system offers easy excess for maintenance. 9.8.13

Use of a Vapour-Absorption Refrigeration System

The vapour-absorption refrigeration system is getting more attention nowadays due to less running cost, environment-friendliness, and economic attractiveness when waste-heat source is available. In this system, the refrigerant is absorbed by a transport medium and compressed in a liquid form. Two commonly used absorption refrigeration systems are ammonia–water and lithium bromide– water. 7 Waste heat input

16

8

2

4

11

1

3 Evaporator

12

Heat output

Absorber

Heat exchanger 15

13 9

6

2

Condenser 5 water

1

Condenser Refrigerant pump

Figure 9.15

10

Waste heat input

Generator 14 (desorber) Solution pump

Schematic of vapour-absorption refrigeration system

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a condenser, an expansion valve, and an evaporator. However, the absorption cycle uses different refrigerants and a different method of compression than the vapour-compression cycle. The schematic of the vapour-absorption system is shown in Figure 9.15. The compressor of the vapourcompression refrigeration cycle is replaced with a generator and an absorber. The refrigerant vapour coming from the evaporator mixes with the returning absorbent and the mixture is pumped to the generator. Heating of the mixture in generator separates the refrigerant vapour at high pressure which is condensed in condenser, expanded in the expansion valve and evaporated in the evaporator (similar to the vapour-compression refrigeration system). 9.8.14

Replace Vapour-Compression-Based Cooling with Evaporative Cooling

Due to geographical variations, India has varied weather conditions, from dry and cool in the north to wet and humid in the south. In dry climates, use of evaporative cooling can be a costeffective option compared to a vapour-compression-based air-conditioning system. Alternatively, vapour compression and evaporative cooling can be used in combination to reduce operating cost of the system. As evaporative cooling has no compressor and works only with heat exchanger and th of a vapour-compressor-based system. Another advatange of evaporative cooling is it continuously supplies fresh air. The cost of an evaporative cooler is not directly comparable because it depends on the type of end user, design, and material used and there are not many players in the market. Evaporative cooling systems are of three types, namely, direct evaportive cooling, indirect evaporative cooling, and direct–indirect evaporative cooling. In direct evaporative cooling, water evaporates into the air and due to this, the temperature of air reduces. The process is adiabatic saturation and is represneted in Figure 9.16. This type of cooling

Air in T1 T 1¢

Cooled air to room DEC

2

T2 T 2¢ = T 1¢

1

Sp.humidity (Kg/Kg dry air)

for domestic applications.

Temperature ( C)

Figure 9.16 Direct evaporative cooling

In indirect evaporative cooling, air is used in a heat exchanger to remove the heat from supply air and cooling of supply air takes place without adding moisture. A heat-exchanger surface will be wetted with water over which outside air will pass and due to evaporation of the water, the surface temperature of the heat exchanger will reduce and ultimately, the supply-air tempeature will reduce. The disadvantage of direct evaporative cooling is overcome in indirect cooling. Figure 9.17 shows

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arrangement and psychrometric represenation of indirect evaporative cooling, in which the full line shows room-air path and the dotted line shows secondary-air (air used to cool room air) path. The third type of evaporating cooling is direct–indirect type in which indirect cooling is used in shown in Figure 9.18. The full line shows room-air path and the dotted line shows secondary-air (air used to cool room air) path.

Primary P, 1 air

Air-to-air heat exchanger

P, 2 Cooled air to room

S, 2 Secondary S, 1 air

2

1

DEC Temperature (°C) Primary

Figure 9.17

Sp.humidity (Kg/Kg dry air)

S, 3

Secondary

Indirect evaporative cooling Cooled air to room

Primary P, 1 air

Air-to-air heat exchanger

P, 2

DEC

P, 3

S, 2 Secondary S, 1 air

3 2

1

DEC Temperature (°C) Primary

Figure 9.18

9.8.15

Sp.humidity (Kg/Kg dry air)

S, 3

Secondary

Direct–indirect evaporative cooling

Use of Alternative Refrigerant

There is global awareness to switch over from CFC to HFC to protect the environment as it has zero Ozone-Depleting Potential (ODP). India, a party to the Montreal Protocol, and having issued the ‘Ozone Rules 2000’, all OEMs in India using CFCs as refrigerants had to change over to nonCFC refrigerants with effect from 1 January, 2003. There are certain advantages of CFCs: they are CFC-12 was widely used in domestic refrigerators and air conditioners (domestic and mobile). Properties which decide a refrigerant’s suitability as an alternative of CFC-12 are listed here. 1. Ozone-depletion potential 2. Global-warming potential 3. Toxicity

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4. Flammability 5. Thermal and chemical stability Suitable alternative refrigerants and their properties are listed in Table 9.4. Table 9.4

Alternative refrigerants Density (kg/m3) Saturated Saturated vapour liquid

Formula

Critical Temperature (°C)

Boiling point (°C) at 100 (kPa)

CF2Cl2

112

29.8

7.57

1472.0

1

10600

HFC-134a

CH2FCF3

101.1

26.16

5.50

1371.0

0

1300

HFC-152a

CH3CHF2

113.5

25.0

3.25

1013.0

0

120

C3H8

96.0

–30

3.14

584.4

0

3

C4H10

135.0

–11.7

1.66

608.3

0

3

C3H8

96.8

–42.1

2.42

580.7

0

3

Refrigerants

CFC-12

HC-290 Isobutene HC-600a Propane HC-290

ODP

GWP

Among these, HFC-134a is more popular. The volumetric capacity of HFC-134a is about 12% lower than CFC-12 at the standard rating conditions: –23.3°C for evaporator, 55°C for condenser temperature which can be offset by increasing compressor displacement. Hence, performance of a system with HFC-134a is approximately equal to that of CFC-12. The drawback of HFC is it is immiscible with naphthenic mineral oils and benzene oils; hence, alternative synthetic oils have been developed. These oils are hygroscopic and require more maintenance to ensure a moisturefree system. Another change required with HFC-134a is resistant-grade electrical insulation for

9.8.16

Encourage Green Building Concept in India

The concept of green building is very much acceptable in India, as in the developed countries, the energy-consumption growth rate is marginally higher than the population growth rate. For

energy consumers and can contribute to a high extent. Approximately, 30 to 40% of total energy is 1. Reduction in energy and water consumption 2. Improved productivity due to maintained human comfort 3. Rainwater harvesting

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Some design aspects of green buildings are listed here: 1. Provision of charging points for electrically operated vehicles. Promote employees to use mass transportation and shared vehicles. 2. More open space. 3. Building orientation to maximize south and north exposure and minimize west and east exposure to follow the solar path. Placing windows and glazing on north wall to minimize heat gain and maximize day lighting. Use of low U-value glazing. 4. Design of air-conditioning system as per ASHRAE standards. 5. Maintain U-value of roof and wall as per ASHRAE standards. 6. Minimize building footprints to reduce impact on environment. 7. Maximize daylight usage. 8. Use of rainwater harvesting and drip irrigation. 9. Cover 60% of roof area with garden and plantation. 10. Recycle grey water and reuse after treatment. Segregate and reuse building waste like paper and plastic.

electronic ballasts, occupancy sensors, and controllers. motors, BMS, CFC-free HVAC equipment, CO2 sensors. 14. Promote use of on-site renewable energy and salvaged material for construction. 16. Use of low-voltaic organic compound paints. 9.8.17

Promote Use of BMS and DDC Systems

Building management system and direct digital controls are techniques used to monitor and control a variety of systems and functions at optimum level. Differant parameters controlled are HVAC, are tailor-made systems and require common network connections. 9.8.18 Thermal Energy Storage (TES) Based Air-Conditioning System

Thermal energy storage is a cost-saving technique for allowing energy-intensive, electrically driven cooling equipment to be predominantly operated during off-peak hours when electricity rates are lower. During summer, air conditioners of buildings are the largest contributor to peak electrical demand. The electricity consumption is peak during afternoon and evening hours and low at night and early-morning hours. To meet this peak demand, utilities increase their generation capacity and during lean-demand periods, the power plants are operated at less capacity which affects the performance and return on investments. TES may be considered a useful tool to reduce the number of refrigeration machines by means of spreading the daytime load over a 24-hour period. In TES, water or another substance is cooled by

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chillers during off-peak (usually night) hours and stored in an insulated tank. This stored coolness is used during peak (usually afternoon) hours. Media used for thermal storage are of different types like chilled water, ice, eutectic salts, etc. Among them, the chilled-water system works on storage of sensible type of heat, while ice and eutectic salts work on storage of latent heat. Figures 9.19 and 9.20 show water- and ice-based thermal energy storage and silos storing the media. Load shifting: Due to shifting of load during off-peak hours, advantage of daytime tariff Storage system chillers operate at full load during off-peak hours instead of conventional operation. Less capacity and space required compared to conventional system. During night hours, outdoor temperature is less; hence, condensation occurs at low temperature and the net effect is rise in EER. Easy to take up maintenance during off-peak hours.

Discharging Building load Discharging pump

Building load

Ice harvester chiller

Warm Storage Cool

Primary pump Charging

Chiller

Figure 9.19

Chilled water pump

Ice/water mixture

Water- and ice-based thermal energy storage (Source: ASHRAE)

Figure 9.20

Silo of thermal energy storage system

Ice-water pump

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Use of thermal energy storage is not helpful for small-capacity systems (less than 100 tons) and where peak demand charge is same as off-peak demand charge. 9.8.19

Use of Variable-Refrigerant Flow System (VRF)

Variable-Refrigerant Flow Systems (VRF) use multiple evaporators of different capacities and different zones and heat recovery between different zones. They operate with direct expansion unit and multiple indoor units with the difference that the multi-split unit turns ON or OFF in Pulse Modulating Valve (PMV) which is controlled by a microprocessor receiving signals from sensors located with each indoor unit. It ultimately controls the compressor speed to match cooling or heating load on the system. A VRF system saves 11 to 17% energy with initial higher cost compared to conventional units. With this technology, up to 48 indoor units are operated with single outdoor units and screw-compressor speed variation ranges from 6 to 100%. Maximum system capacity is 70 kW (approx. 20 TR). A schematic of a VRF system is shown in Figure 9.21. Separation tube

Header

Refrigerant branch unit Outdoor unit

Transmission adaptor Indoor unit

PC controller Central remote controller

Wireless remote controller

Wired remote controller

Figure 9.21

Wired remote controller

Schematic of a VRF system

Advantages of a VRF System

3. Precise humidity control. 4. It is possible to achieve simultaneous cooling and heating. individualized bills.

Wired remote controller

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6. As shown in Figure 9.22, a single condensing unit can be connected to different sizes of indoor units of varying capacity (0.5 ton to 8 ton). consumption and compressor speed to reduce energy consumption. It provides superior

excellent. Room A 24°C

Room A 24°C

Room B 18°C Outdoor condensing unit

Room C 27°C

Room E 23°C

Room D OFF

0.6 Ton

Cassette type fan coil unit Room 2

Room 1

Figure 9.22



9.9

Ducted indoor unit 8 Ton

Operating flexibility in a VRF system

STAR RATING AND LABELLING BY BEE

As a part of BEE star rating and labelling procedure, it is mandatory for manufacturers of different

and single-phase power supply to adopt the star-rating procedure. The range of EER for deciding numbers of stars to be given to a particaular model is given in Tables 9.5 and 9.6 for different timelines. Details of testing and sampling are mentioned in the BEE website. Table 9.5

Star rating by BEE for room air conditioners valid from 1 January, 2012 to 31 December, 2013 Star rating

Min. EER (W/W)

Max. EER (W/W)

1 star

2.50

2.69

2 star

2.70

2.89

3 star

2.90

3.09

4 star

3.10

3.29

5 star

3.30

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Table 9.6

Star rating by BEE for room air conditioners valid from 1 January, 2014 to 31 December, 2015 Star rating

Min. EER (W/W)

Max. EER (W/W)

1 star

2.70

2.89

2 star

2.90

3.09

3 star

3.10

3.29

4 star

3.30

3.49

5 star

3.50

Similarly, it is mandatory for direct-cool and frost-free refrigeators manufacturers to adopt star rating and labelling for their products. Detailed information is available on the BEE website.

CHECKLIST

Energy Audit of HVAC Systems

Energy-Management System

THUMB RULES

Descriptive Questions

Short-Answer Questions

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Fill in the Blanks

Multiple-Choice Questions

Energy Audit of HVAC Systems

Answers Fill in the Blanks 4. 5. 6.

1. 2. 3. Multiple-Choice Questions 1.

2.

3.

4.

5.

191

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10

Electrical-Load Management . Our



10.1

ELECTRICAL BASICS

Common terms used in electrical energy are explained here: The electrical power or demand used in a circuit depends on two fundamental quantities, voltage and current. 1. Voltage is the magnitude of the push trying to send electrical charge through a wire. It is measured in volts. 2. Current voltage; it is measured in amperes (amps). 3. Power is voltage and current acting together to do useful work. It is measured in watts. Power = Voltage × Current 4. Resistance component or circuit has resistance and it changes electrical energy into another form of energy like heat, light, or motion. It is measured in ohms. 5. Demand is the rate of use of electrical energy. It generally refers to the average power measured over a given time interval. 6. Direct current (DC 7. Alternating current (AC

8. The supply frequency frequency is cycles/second or hertz. In India, the typical household voltage goes through a complete cycle of 50 times per second, known as 50 hertz (Hz).

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9. In AC circuits, the current and voltage do not always work together. How well they work power factor heaters and incandescent lamps are called resistive loads. These loads do not reduce the power factor. They allow the voltage and current to work together (unity pf). While inductive devices cause inductive loads,

Kilowatt (kW) =

Volts ¥ Amps ¥ Power Factor = kVA ¥ Power Factor 1000

(10.1)

10. in kilowatt-hours (kWh).

11. Electricity tariff or kW for each month. The tariff unit of electricity is kWh. It is a measure of energy use usually one or two months, depend on the type of user. 12. Domestic customers are charged for usage of electric units only, while commercial and industrial customers are charged for the amount of energy used and on peak demand for each month. Contract demand is the amount of electricity a consumer is demanding from utility and maximum demand is the highest average recorded during one demand Demand factor is the ratio of maximum demand to the connected load where connected load is the summation of all nameplate ratings of the equipment existing in the area. To calculate load factor, the ratio of actual energy



10.2

ELECTRICAL LOAD MANAGEMENT

Key implementation challenges for India’s electricity sector include new project management and

and central government levels, and training of skilled manpower to prevent talent shortages for operating latest technology plants. Demand-Side Management (DSM). It is a process

is known as load management. If demand and supply are not matched successfully, the system

Electrical-Load Management

195

modelling considering topology, capacity, etc., and planning of load scenario considering weather, management. 10.2.1

Electricity and its Cost

and consumed at the same moment. In addition, depending on plant production rate at various times

also includes cost of fuel, wages of plant operators, maintenance, depreciation, capital cost, taxes, etc. Thus, cost of electricity is given as the following equation: Ct = a + bP + cE where P is maximum power demand, E is annual energy supply; and a, b, and c To meet continuously changing demands, the utility is made of different types of power plants, base-load plant is a nuclear,

Intermediate plants to operate at different load conditions. Peak-load plants Typical day load curve (% of daily peak)

Transmission

Generation

100

Fuel

Peak load

80 Power plant

Substation

Intermediate cycling load

60 Power lines 40

Base load

Substation 20 0 Distribution

Customers

Figure 10.1

0 Time

8

12

18

24

A typical 24-hour electric-system load profile

consumption (kVARh), and maximum demand. Power companies focus on reducing kWh consumption and improving power factor. Power consumed over a predetermined time period is

196

Handbook of Energy Audit

known as maximum demand. Predetermined time minutes. per the hour of the day and season (kW and kWh charges are higher during peak time and lower

1. 2. Additional plant is not required to meet load demand; this not only reduces cost of electricity

4. 5. Some common techniques to manage the load are discussed here. 10.2.2

Load-Management Techniques

Use of Storage System

to less cost involved and ease of operation. Some examples of energy storage are listed here: 1. 2. industries.

4. Change in Technology less power for the same level of performance. For example,

system.

Electrical-Load Management

197

Decentralized Power Generation Generation of electricity on the location of use is known

heat and electricity are required simultaneously. Reduce Electricity Use During Peak Hours

totally stopped. It will postpone or delay some activities, which are not on the priority list. If

Use of Demand Controllers Demand controllers set the limit for maximum load and disconnect the load from the grid when the limit is crossed. According to the priority list, the controller switches off the loads when the limit of maximum load exceeds and it is switched on when the load is within limits. It consists of the following: 1. An input device to do programming of load.

5. Interface with a computer and printer. Utility meter pulse output Demand controller

Loads 1-64 24 V DC relay

Main feed/ disconnect

kW transducer mA output Telephone line/modern communication Remote PC

Figure 10.2

Demand-control device

198

Handbook of Energy Audit

loads. In case of manned loads, load and unload signals are given to the operator. In sophisticated

of a demand controller is easily recovered in a very short time and, hence, it is installed in almost all industries. Mostly, lights, compressors, air conditioners, pumps, fans, packing machinery, etc., are controlled when maximum demand exceeds. A demand controller operates either in preventive mode or predictive mode. Preventive mode is

manually disconnects the load. In the predictive method



10.3

VARIABLE-FREQUENCY DRIVE

As mentioned in the chapter on electrical motors, a major portion of electrical energy is consumed for driving electric motors. It is used to drive pumps, fans, compressors, conveyers, presses, etc. A load of any industry or process is not constant and so it is of the motor. Old ways to control motor

require continuous monitoring as well as maintenance, and cannot give precise speed control. Fans,

AC current to DC current, and then with switching mechanism converting DC to synthetic AC with controlled voltage

In a voltage-source inverter DC pulses, which can damage the application at low frequency. In a current-source inverter DC

Electrical-Load Management

199

The pulse-width modulator DC

single drive. Sine wave power

Mechanical power

Variable frequency power

AC motor

Variable frequency controller

1540

Power conversion

Power conversion

Operator interface

Figure 10.3 Table 10.1

Variable-speed drive

Summary of types of loads

Type of load

Change in parameters

Applications

Variable torque

Lower torque at low speed

Centrifugal pump, fan, blower

Constant torque

Same torque at all speeds

Conveyer, positive-displacement pump and compressor, extruder

Constant horsepower

High torque at low speed, low torque at high Metal cutting and extruder speed, constant horsepower at all speeds

Use of Variable-Frequency Drive its uses are mentioned here: 2. motor. 4.

200

Handbook of Energy Audit



10.4

HARMONICS AND ITS EFFECTS

of primary frequency superimposed on the alternating current waveform. A distorted harmonics frequency is twice that of the fundamental frequency is called second-order harmonics, and that which is three times the fundamental frequency is called third order harmonics. Even harmonics, odd harmonics tend to add and create distortion. Harmonic distortion is the degree to which a waveform deviates from its pure sinusoidal waveform. The ideal sine waveform has zero harmonics. According to the International and is represented as a percentage value. Total harmonic distortion is the summation of all harmonic components of voltage or current waveforms compared to the fundamental component of the

Total harmonic distortion =

(V22 + V32 + V42 + º + Vn2 ) ¥ 100 V1

Waveform

+ 0

Time -

Figure 10.4 Table 10.2

Current voltage

Current voltage

where V , V , V Waveform

+ 0

Time -

Ideal and distorted waveforms

Power quality for different devices Device

Active power (W)

Power factor

THD (%)

16 W CFL with electronic ballast

16

0.91

20

400 W high-intensity discharge lighting with magnetic transformer

425

0.99

14

100 W incandescent lighting

101

1

1

CPU

33

0.56

139

13≤ colour monitor

49

0.56

138

Laser printer (in use)

799

0.98

15

Electrical-Load Management

10.4.1

201

Cause and Effect of Harmonics

in motors, harmonics overheat the motor and make operation noisy. It may overheat capacitors and

10.4.2

How to Control Harmonics

1 har

Non-linear load

Figure 10.5

Filter

Harmonics filter

Another solution is use of equipment to reduce the level of harmonics. By installing line reactors,

a feature of the unit. �

10.5

ELECTRICITY TARIFF

202

Handbook of Energy Audit

PART A: Residencial Premises (at Low and Medium Voltage) ∑ ∑ Fixed charges per month (other than BPL consumers) Demand

Charges

(a) Up to and including 2 kW

₹ 15 per month

(b) Above 2 to 4 kW

₹ 25 per month

(c) Above 4 to 6 kW

₹ 45 per month

(d) Above 6 kW

₹ 65 per month

For BPL (Below Poverty Line) consumers

Fixed charges

₹ 5 per month

Monthly charges – Energy charges (other than BPL consumers) Usage

Charges

(a) First 50 units

315 paise per unit

(b) Next 50 units

360 paise per unit

(c) Next 150 units

425 paise per unit

(d) Above 250 units

520 paise per unit

PART B: Tariffs for High-Tension Consumers Contracted for 100 kVA and above (3.3 kV and above, 3-phase, 50 cycles/second) and Extra High Tension Demand

(a)

For First 500 kVA of billing demand

Charges

₹ 120 per kVA per month

(b) For next 500 kVA of billing deamand

₹ 230 per kVA per month

(c)

₹ 350 per kVA per month

For billing demand in excess over 1000 kVA

(d) For billing demand in excess over the contract demand

₹ 430 per kVA per month

Energy charges For entire consumption during the month

Charges

(a) Up to 500 kVA of billing demand

400 paise per unit

(b) For billing demand above 500 and upto 2500 kVA

420 paise per unit

(c) For billing demand above 2500 kVA

430 paise per unit

Electrical-Load Management

203

1. 2. 85% of contract demand 100 kVA Time-of-use charges

Energy consumption during peak periods (1) 7:00 to 11:00 h, and (2) 18:00 to 22:00 h For billing demand up to 500 kVA

35 paise per unit

For billing demand above 500 kVA

75 paise per unit

Power-Factor Penalty

Power-Factor Rebate

lights, railways, etc. �

10.6

POWER FACTOR

In AC active component IR which is in phase with the supply voltage and the reactive component Io which is perpendicular respect to the active component IR. Power factor cos j and total value of current I apparent power in VA. cos f =

I R Real power or active power in W = Apparent power in VA I

I lags with IR W to the

Handbook of Energy Audit

IR

r we

V

j

re pa

nt

A) (kV

po

Ap

Power factor angle IQ

I

Reactive power (kVAr)

204

Real power (kW)

Figure 10.6 Power factor

devices like AC motors, transformers, furnaces, ovens, etc., and is measured in kVAR. Reactive performed. Depending on the type of application, apparent power is always in excess or active useful work.

power factor is 0.8 in industry. It means that for a 1 MVA transformer, the consumer can draw 800 kW and to meet a low power factor, the utility company has to generate much more current

To discourage these activities, the electricity company charges penalty for low power factor. Table 10.3

Values of power factors for some common electrical applications

Electrical equipment

Power factor, cos j

Transformer (no load)

0.1 to 0.15

Motor

0.7 to 0.85

Arc and resistance welding

0.35 to 0.6

Fluorescent lamp

0.4 to 0.6

DC drives

0.4 to 0.75

AC drives

0.95 to 0.97

Resistive load

1

10.6.1

How to Improve Power Factor

A high power factor is generally recomended to reduce transmission losses and improve voltage

Electrical-Load Management

205

correction equipment.

capacitors and if a load has capacitive value, inductors (reactors) are used to correct the power factors. Inductors consume reactive power and capacitors supply reactive power. The disadvantage

the system. �

10.7

TRANSMISSION AND DISTRIBUTION LOSSES

country. Off the record, it goes to 50% in some states. These losses are very important as they technical and commercial. Technical losses are due to energy dissipated in the electricity conductors to an extent with use of proper design and material. Commercial losses are due to pilferage, use of defective meters, wrong reading of meters, and estimation of unmetered power supply. Why do technical losses occur in transmission and distribution of electricity?

5. Poor load management. 6. Inadequate reactive compensation in grid. Methods to Reduce Technical Losses

transformers.

6. Carry out detailed study to forecast load development during the next two years and prepare

206

Handbook of Energy Audit

Figure 10.7

Image of illegal tapping of electricity (See color figure)

Why do commercial losses occur in transmission and distribution of electricity? country.

8. Another way to steal electricity is through excess unmetered use of electricity. Methods to Reduce Commercial Losses 1. Set norms of severe penalties for tampering of meters and seals.

Electrical-Load Management

5. Conduct regular meter testing and replacement of faulty meters. Practice regularly. Short-Answer Questions

Fill in the Blanks

Answers 1. 1 2. 2

3. 4.

207

11

Energy Audit of Motors

spend ` electrical energy to operate it. A price premium of ` ` `

`

fundamentals of motors are discussed here. �

11.1

CLASSIFICATION OF MOTORS

Alternating current (AC) or Direct current (DC

AC

AC

asynchronous (induction) and synchronous motors.

Energy Audit of Motors

209

120 ¥ frequency (Hz) number of poles Electric motors

Single phase

Efficiency

Special motors

DC motors

AC motors

Series wound

Stepper motor

Standard efficiency motor

Shunt wound

Linear motor

High efficiency motor

Wound motor

Compound wound

Universal motor

Premium efficiency motor

Squirrel cage

Permanent magnet

Polyphase

Synchronous

Induction

Chart 11.1 Classification of motors Fan cover (hood)

Stator (Windings)

Fan Frame

Bearings Bracket (end bell)

Rotor Conduit box cover

Figure 11.1

Conduit box

Motor shaft

Internal view of a motor (See color figure)

Seal

210

Handbook of Energy Audit

slip Squirrel-cage motors are Wound-rotor motors AC DC DC DC to DC Table 11.1

AC

DC Synchronous speeds for different-pole motors Poles

Speed in rpm at 50 cycles

2

3000

4 6 8 10

1500 1000 750 600

series

DC motor

2

a

compound motor permanent-magnet motor

motor

stepper motor universal motor

linear

Compressor 5% RAC 5%

Fans 13% Pumps 42%

Others 35%

Figure 11.2

Industrial uses of motors (See color figure)

Energy Audit of Motors

211

small motors medium motors large motors

high



11.2

PARAMETERS RELATED TO MOTORS

∑ Horsepower

or

(or

∑ Phase ∑ Poles ∑ Core ∑ Torque ∑ Rotor ∑ Stator ∑ Insulation class

Table 11.2

Maximum allowable temperature Temperature-tolerance class

Maximum operation temperature allowed °C

A

105

B

130

F

155

H

180

212

Handbook of Energy Audit

∑ Air gap

∑ Design Design A

Design B Design C Design D

∑ Frame size

∑ Enclosure



11.3

EFFICIENCY OF A MOTOR

Output Input - Losses Output = = Input Input Output + Losses

∑ Fixed losses ∑ Variable losses ∑ Core loss

Energy Audit of Motors

213

∑ Windage-and-friction losses

∑ Stator losses

I I2R loss. I2R

R

I2R output hp ¥ 0.746

I

3 ¥ v ¥ pf ¥ h

v pf ∑ Rotor losses

¥ ∑ Stray-load losses I2R Table 11.3

No-load losses in a motor

Type of loss

Typical distribution (%)

Factors deciding loss

Methods to reduce loss

Core loss

15–25

Type and quality of magnetic material

Use of improved magnetic material and by lengthening the core

Windage-andfriction losses

5–15

Design and selection of fan and bearings

Improved bearing selection, airflow, and fan design are employed

Table 11.4

Losses in a motor operating under loads

Type of loss

Typical distribution (%)

Factors deciding loss

Methods to reduce loss

Stator loss

25–40

Stator conductor size

Use of improved slot design or by decreasing insulation thickness

Rotor loss

15–25

Rotor conductor size

Increasing the size of the conductive bars and end rings

Stray-load loss

10–20

Manufacturing and design methods

Use of optimized design and strict quality control procedures minimizes stray-load losses

214



Handbook of Energy Audit

11.4

11.4.1

ENERGY CONSERVATION IN MOTORS

Appropriate Loading of Motor

Percent efficiency 100 95

100 hp 50 hp

90 85 80 75 70

0

25

50

75

100

Percent rated load

Source: Figure 11.3

Variation in efficiency for different loads on motors

IEEE Trans

Energy Audit of Motors

215

Actual input power Input power at rated load

slip (Synchronous speed - Actual speed) ¥ 100 Synchronous speed slip Synchronous speed - full load nameplate rpm 0.746 ¥ motor load ¥ nameplate hp ¥ 100 measured input in kW EXAMPLE 11.1 An induction motor having 1500 rpm synchronous speed is running at 1480 rpm. Its nameplate Solution

20 = 0.8 1500 - 1475 0.746 ¥ 0.8 ¥ 25 ¥ 100 = 82.88 % 18

216

Handbook of Energy Audit

(2 ¥ LLA) - NLA ¥ 100 (2 ¥ NPA) - NLA EXAMPLE 11.2 A 20 hp motor driving a pump is operating on 440 volts and has a loaded line amperage of 16.5. When disconnected from the motor, the load amperage is 9.3. Calculate the load on the motor if the nameplate amperage for 440 volts is 24. Solution (2 ¥ 16.5) - 9.3 ¥ 100 = 61.2 (2 ¥ 24) - 9.3 11.4.2

Selection of the Right Motor

2. I2R

∑ ∑ ∑

Energy Audit of Motors

11.4.3

Assessing Motor and Drive-System Operating Conditions

Motor Rewinding

I2R 2.

∑ ∑ ∑ ∑ ∑ ∑ ∑

217

218

Handbook of Energy Audit

of `

Energy Audit of Motors

Table 11.5

Effect of voltage imbalance on motor characteristics

Motor characteristics

Supply voltage as % of normat voltage 100%

110%

Starting torque

81%

100%

121%

Total current

111%

100%

93%

Speed

98.5%

100%

101%

Efficiency

Decrease

100%

Decrease

Temperature rise %

90%

Motor Overheating

300 250 200 150 100 50 0 0

Figure 11.4

2

4 Voltage imbalance %

Insulation breakdown 6 zone 8

Effect of voltage imbalance on motor temperature

∑ ∑ ∑ ∑ ∑ ∑

AC

219

220

Handbook of Energy Audit

brown-out,

∑ ∑ ∑

15 10 5 0 1

5 7 9 11 13 3 Percentage rated flow

Figure 11.5

11.4.4

Poor example for VFD drive Operating hours

Operating hours

Good example for VFD drive

15

20 10 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Percentage rated flow

Example showing suitability of motor for VFD

Optimization of the Complete System

Energy Audit of Motors

2

A soft starter

AC motors

electrical

Figure 11.6 Image of a soft starter (See color figure)

∑ ∑ ∑

221

222

Handbook of Energy Audit

Table 11.6

Different types of belts with their range of efficiencies

Type of belt

Efficiency

Characteristics

Standard V-belt

90 to 96%

Losses from flexing and slippage

Cogged V-belt

92 to 98%

Lower losses from flexing and slippage

Synchronous belt

98 to 99%

No slippage but most expensive

EXAMPLE 11.3 A 100 hp motor operates at 75% load and consumes 5,25,000 units annually. Calculate annual Solution ¥

h of v

`

Table 11.7

h `

Example of maintenance schedule

Time interval

Action

Weekly

Check oil level in bearings and oil rings. Inspect the shaft for signs of oil leakage. Inspect the starter, switches, and fuses. Check the start-up time for the motor.

Monthly

Blow out dirt, wipe up commutator and brushes, check brushes, inspect for wear, check oil quality in sleeve bearings, check grease in antifriction bearings, check operating speed, and check enclosure and foundation.

Yearly

Re-grease antifriction bearings, check air gaps, check bearing clearances, and clean slots in the commutator.

Energy Audit of Motors

Table 11.8

223

Reasons for reduced losses in energy-efficient motors Losses

Reasons for reduced losses in energy-efficient motors

Iron losses Stator I2R losses Rotor I2R losses Friction and windage losses Stray-load loss

Use of thinner gauge and lower-loss core steel reduces eddy-current losses Use of more copper and large conductors Use of large rotor conductor bar Use of more efficient fan design Use of quality control and optimized design

More copper wiring in stator

Higher slot fill

Lower loss premium steel core Longer stator steel stack with thinner laminations

Figure 11.7

IE3 Premium-efficiency motor (See color figure)

Source:

224

Handbook of Energy Audit

2.

Table 11.9

Performance of EF1 motors

OUTPUT P FRAME kW HP O SIZE L E 0.37 0.50 2 SD71 4 SD71 6 SD/ND80 8 SD/ND90S 0.55 0.75 2 SD71 4 SD/ND80 6 SD/ND80 8 SD/ND90L 0.75 1.00 2 SD/ND80 4 SD/ND80 6 SD/ND90S 8 SD/ND100L

FL FLC FLT RPM AMPS Kg-m

EFFICIENCY (%) POWER FACTOR DOL STG. POT GD.2 NET FL 3/4 1/2 FL 3/4 1/2 STGT STGC %FLT KGM2 WT LOAD LOAD LOAD LOAD %FLT %FLC kG

2820 1400 910 680 2800 1410 910 680 2820 1410 935 700

70.2 730 69.4 66.8 74.0 78.0 720 71.1 77.0 82.5 746 73.8

0.95 1.00 1.05 1.40 1.30 1.25 1.55 1.80 1.65 1.70 2.00 2.55

0.13 0.26 0.40 0.53 0.19 0.37 0.58 0.78 0.26 0.52 0.78 1.04

70.2 730 69.4 66.8 74.0 780 720 71.1 77.0 825 74.6 73.8

68.2 71.0 67.4 64.8 72.0 76.0 70.0 69.1 75.0 80.5 72.6 71.8

0.79 070 071 0.57 0.78 078 071 060 0.81 078 072 0.58

0.72 058 063 0.50 0.72 075 063 0.48 0.73 075 065 051

0.60 0.43 0.52 0.40 0.60 0.64 0.52 0.37 0.62 0.64 0.58 0.41

250 225 210 170 250 200 200 150 250 200 200 175

500 600 400 400 500 500 400 400 600 500 400 400

300 275 260 220 300 250 250 200 300 250 250 225

0.002 0.004 0.011 0.015 0.002 0.007 0.011 0.021 0.003 0.007 0.015 0.030

7.0 7.0 10/17 13/22 7.0 10/17 10/17 13/22 10/17 10/17 13/22 19/32

Energy Audit of Motors

OUTPUT P FRAME FL FLC kW HP O SIZE RPM AMPS L E 1.10 1.50 2 SD/ND80*** 2820 2.35 4 SD/ND90S 1415 2.40 6 SD/ND90L 935 2.75 8 SD100L/ 700 3.30 ND100L 1.50 2.00 2 SD/ND90S 2830 3.00 4 SD/ND90L 1415 3.00 6 SD/ND100L 935 3.60 8 SD112M/ 700 3.90 ND112M 2.20 3.00 2 SD/ND90L 2830 4.40 4 SD/ND100L 1440 4.30 6 SD/ND112M 935 5.00 8 ND132S 710 5.40 3.70 5.00 2 SD/ND100L 2875 7.20 4 SD/ND112M 1440 7.20 6 SD/ND132S 950 8.00 5.50 7.50 2 SD/ND132S 2865 9.70 4 SD/ND132S 1450 10.60 6 SD/ND132M 950 11.30 7.50 10.00 2 SD/ND132S*** 2880 13.70 4 SD/ND132M 1455 13.80 3.7 5.0 8 ND160M 710 8.0 5.5 7.5 8 ND160M 710 12.0 7.5 10.0 6 ND160M 975 11.0 8 ND160L 710 12.0 9.3 12.5 2 ND160M 2920 16.0 4 ND160M 1460 17.0 6 ND160L 975 18.0 8 ND180L 720 20.0 11 15 2 ND160M 2920 19.0 4 ND160M 1460 21.0 6 ND160L 975 21.0 8 ND180L 720 23.0 15 20 2 ND160M 2920 26.0 4 ND160L 1460 27.0 6 ND180L 975 29.0 8 ND200L 725 33.0 18.5 25 2 ND160L 2920 32.0 4 ND180M 1475 33.0 6 ND200L 975 34.0 8 ND225S 725 38.0

225

FLT Kg-m

EFFICIENCY (%) POWER FACTOR DOL STG. POT GD.2 NET FL 3/4 1/2 FL 3/4 1/2 STGT STGC %FLT KGM2 WT LOAD LOAD LOAD LOAD %FLT %FLC kG

0.38 0.76 1.15 1.53

82.8 82.8 83.8 838 773 773 76.2 76.2

80.8 81.8 75.3 74.2

0.82 078 072 062

0.77 075 065 057

0.70 0.64 0.58 0.47

200 200 200 160

600 500 500 400

250 250 250 210

0.004 0.014 0.021 0.034

10/17 13/22 16/25 19/35

0.52 1.03 1.56 2.09

84.1 84.1 85.0 850 79.6 79.6 779 77.9

82.1 83.0 77.6 75.9

0.82 081 0.72 0.68

0.77 078 065 0.60

0.70 0.71 0.58 0.52

225 200 200 190

600 600 500 400

275 250 250 240

0.006 0.019 0.030 0.057

13/22 16/25 19/32 29/45

0.76 1.49 2.29 3.02 1.25 2.50 3.79 1.87 3.69 5.64 2.54 5.02 5.08 7.55 5.49 7.55 3.10 6.20 9.29 12.58 3.67 7.34 10.99 14.88 5.00 10.01 14.98 20.15 6.17 12.22 18.48 24.85

85.6 86.4 82.2 80.5 87.5 88.3 85.1 88.6 89.2 86.8 89.5 90.1 83.0 85.1 88.1 86.4 90.0 90.5 89.3 87.3 90.5 91.0 89.7 88.1 91.3 91.8 90.5 89.0 91.8 92.2 91.3 89.8

83.6 84.4 80.2 78.5 85.5 86.3 83.1 86.6 87.2 84.8 87.5 88.1 81.0 83.1 86.1 84.4 88.0 88.5 87.3 85.3 88.5 89.0 87.7 86.1 89.3 89.8 88.5 87.0 89.8 90.2 89.3 87.8

0.82 082 0.75 0.71 0.82 081 0.76 0.89 0.81 0.76 0.85 0.84 0.74 0.74 0.80 0.76 0.88 0.84 0.80 0.74 0.88 0.82 0.80 0.74 0.88 0.85 0.79 0.71 0.88 0.84 0.84 0.75

0.77 078 0.70 0.68 0.77 076 0.73 0.85 0.80 0.75 0.82 0.82 0.70 0.70 0.76 0.72 0.86 0.81 0.76 0.70 0.86 0.79 0.76 0.70 0.86 0.83 0.73 0.65 0.86 0.80 0.82 0.71

0.70 0.72 0.60 0.61 0.70 0.69 0.63 0.80 0.75 0.68 0.76 0.74 0.62 0.62 0.68 0.64 0.78 0.73 0.68 0.60 0.78 0.70 0.68 0.60 0.79 0.75 0.66 0.55 0.79 0.72 0.73 0.63

225 200 200 180 250 200 200 250 250 200 200 250 150 150 200 150 225 175 200 175 225 200 200 175 225 200 225 225 225 200 200 175

650 600 500 500 650 600 600 600 600 600 650 650 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700

275 250 250 230 300 250 250 300 300 250 250 300 200 200 250 200 275 225 250 225 275 250 250 225 275 250 275 275 275 250 250 225

0.008 0.030 0.046 0.174 0.022 0.052 0.174 0.034 0.131 0.214 0.062 0.161 0.46 0.46 0.46 0.64 0.13 0.31 0.59 0.99 0.13 0.36 0.64 1.16 0.17 0.47 1.16 2.14 0.21 0.81 1.69 3.24

16/25 19/32 29/42 68.0 19/36 29/42 42/68 29/45 42/68 45/79 45/68 45/79 125 125 125 148 125 125 148 174 125 125 148 210 125 148 210 282 148 174 282 345

85.6 864 82.2 80.5 87.5 883 85.1 88.6 89.2 86.8 89.5 90.1 83.0 85.1 88.1 86.4 90.0 90.5 89.3 87.3 90.5 91.0 89.7 88.1 91.3 91.8 90.5 89.0 91.8 92.2 91.3 89.8

226

Handbook of Energy Audit

Table 11.10 OUTPUT P kW HP O L E 22 30 2 4 6 8 30 40 2 4 6 8 37 50 2 4 6 8 45 60 2 4 6 8 55 75 2 4 6 8 75 100 2 4 6 8 90 120 2 4 6 8 110 150 2 4 6 8 132 180 2 4 6 8 160 215 2 4 fi

Performance of EF1 motors FRAME FL FLC FLT SIZE RPM AMPS Kg-m

ND180M ND180L ND200L ND225M ND200L ND200L ND225M ND250M ND200L ND225S ND250M ND280S ND225M ND225M ND280S ND280M ND250M ND250M ND280M ND315S ND280S ND280S ND315S ND315M ND280M ND280M ND315M ND315L ND315S ND315S ND315M ND315L ND315M ND315M ND315L ND315L ND315L ND315L NmiSI

2930 1475 975 725 2950 1475 980 735 2950 1460 980 735 2955 1480 980 725 2955 1475 980 740 2975 1460 987 740 2975 1460 987 740 2965 1466 987 740 2965 1466 985 740 2975 1490 990

40.0 39.0 40.0 45.0 50.0 50.0 53.0 61.0 61.0 62.0 66.0 75.0 71.0 75.0 79.0 90.0 87.0 91.0 95.0 113.0 123 0 122.0 129.0 153.0 146 0 146.0 154 0 178.0 171.0 175.0 188.0 216.0 205.0 209.0 225.0 259.0 2480 258.0 272 0

7.31 14.53 21.98 29.56 9.91 19.81 29.82 39.76 12.22 24.35 36.77 49.03 14.83 29.61 44.72 60.46 18.13 36.32 54.66 72.39 24.55 49.36 74.01 98.72 29.47 59.23 88.81 118.46 36.13 72.00 10855 144.76 43.36 86.40 13053 173.74 52.38 104.59 157 41

EFFICIENCY (%) POWER FACTOR DOL STG. POT GD.2 NET FL 3/4 1/2 FL 3/4 1/2 STGT STGC %FLT KGM2 WT kG LOAD LOAD LOAD LOAD %FLT %FLC 92.2 92.2 92.6 92.6 91.8 91.8 90.2 90.2 92.9 92.9 93.2 93.2 92.6 92.6 91.5 91.5 933 933 93.6 93.6 93.0 930 91.9 91.9 93.7 93.7 93.9 93.9 93.4 934 92.4 92.4 94.0 94.0 94.2 94.2 93.8 938 93.0 93.0 94.6 94.6 94.7 94.7 94.2 94.2 93.5 93.5 950 950 95.0 95.0 94.5 945 94.0 94.0 95.0 95.0 95.2 95.2 94.6 946 94.3 94.3 95.3 95.3 95.5 95.5 94.9 949 94.7 94.7 955 955 95.8 95.8 95 1 CIS 1

90.2 90.6 89.8 68.2 909 91.2 90.6 69.5 91.3 91.6 910 69.9 91.7 91.9 914 90.4 92.0 92.2 918 91.0 92.6 92.7 92.2 91.5 930 93.0 925 92.0 93.0 93.2 92.6 92.3 93.3 93.5 929 92.7 935 93.8 931

0.83 0.84 0.84 0.75 0.90 0.89 0.85 0.75 090 0.89 084 0.75 0.94 0.89 085 0.75 0.94 0.89 086 0.73 0.90 0.90 0.86 0.73 090 0.90 086 0.75 094 0.92 086 0.75 0.94 0.92 086 0.75 094 0.90 0 86

0.80 0.80 0.82 0.71 0.89 0.86 0.82 0.71 089 0.86 081 0.71 0.92 0.86 082 0.71 0.92 0.86 082 0.66 0.86 0.88 0.82 0.66 086 0.88 082 0.72 091 0.88 082 0.72 0.90 0.88 082 0.72 092 0.86 0 8?

0.72 0.72 0.78 0.63 0.87 0.78 0.73 0.63 067 0.78 072 0.63 0.68 0.78 073 0.63 068 0.62 0.74 0.56 078 0.84 0.74 0.56 078 0.84 074 0.68 084 0.80 074 0.68 0.82 0.80 074 0.68 090 0.78 0 74

225 200 200 175 200 250 200 175 200 250 250 200 225 250 250 175 175 200 175 250 225 250 250 200 225 250 250 250 200 225 250 250 200 225 250 225 175 200 250

700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700 700

275 250 250 225 250 300 250 225 250 300 300 250 275 300 300 225 225 250 225 300 275 300 300 250 275 300 300 300 250 275 300 300 250 275 300 275 225 250 300

0.44 0.95 2.04 3.61 0.80 1.62 3.61 4.82 089 2.64 482 8.01 1.87 3.13 801 9.89 2.79 3.45 989 14.12 7.14 7.21 14.12 18.98 8.18 8.26 1700 29.85 663 11.62 18.98 29.85 7.97 13.98 29.85 29.85 1637 24.97 29 85

164 210 282 375 282 282 375 473 282 345 473 600 375 375 600 670 473 473 670 900 600 600 900 950 670 670 950 1160 900 900 950 1160 950 950 1160 1160 1160 1160 1160

Energy Audit of Motors

NOTE: ∑ ∑ LOAD. ∑

Simple payback ¥

¥

¥

Ê 100 100 ˆ ¥C¥ Á Ë hstd hee ˜¯

C h hee

price premium - utility rebate Annual rupees saving motor price + istallation charges - utility rebate - salvage value of old motor Annual rupees saving

227

228

Handbook of Energy Audit

EXAMPLE 11.4 ` motor is `9380. Calculate the simple payback for 4000 working hours per year at an electricity cost of `5/kWh. Assume the motor runs on 80% of the rated capacity. Solution `

¥

`

¥

` `

¥ ¥

¥ ¥

Ê 100 100 ˆ ¥C¥ Á Ë hstd hee ˜¯

100 100 ˆ ¥ ÊÁ Ë 85 88.3 ˜¯

Energy Audit of Motors

Table 11.11

Efficiency comparison for different countries

Country

USA

Europe

India

Standard

EPACT

CEMEP

IS 12615

Rating of motor (kW)

EPACT

NEMA premium

Eff1

Eff2

Eff1

Eff2

1.1

84

86.5

83.8

76.2

83.8

76.2

2.2

84

86.5

86.4

81

86.4

81

3.7

87.5

89.5

88.3

84.2

88.3

84

5.5

87.5

89.5

89.2

85.7

89.2

85.7

7.5

89.5

91.7

90.1

87

90.1

87



11.5

BEE STAR RATING AND LABELLING

2.

4.

THUMB RULES

229

230

Handbook of Energy Audit



ABBREVIATIONS

IEC

International Electrotechnical Commission

NEMA OEM

National Electrical Manufacturers Association Original Equipment Manufacturer

ASD

Adjustable Speed Drives

MEPS HEM

Minimum Energy Performance Standard High-Energy Motor

TEFC

Totally Enclosed Fan Cooled

SCR BEE

Silicon-Controlled Rectifier Bureau of Energy Efficiency

Descriptive Questions

Short-Answer Questions

enclosures.

Energy Audit of Motors

Justify the Following Statements

Fill in the Blanks

Multiple-Choice Questions

Slip calculates Synchronous speed - full load nameplate rpm

231

232

Q-4

Handbook of Energy Audit

0.746 ¥ motor load ¥ name plate hp ¥ 100 calculates measured input in kW

th

th

Answers Fill in the Blanks 1. 2. 3. 4. 5. 6. Multiple Choice Questions 1. 2.

7. 8. 9. 2 10. 11. Delta 12.

3.

4.

5.

7.

12

Energy Audit of Pumps, Blowers, and Cooling Towers �

PART A: PUMPS

Selecting a large pump and using a throttle is like pressing the brake and acceleration pedals simultaneously in a car, which we never do. Pumps being essential parts of industrial and commercial applications, most are selected oversized, to meet variations in load as well as future load. The major part of energy saving is associated in selecting the right pump and operating it on its best performance point. Pumping systems consume as much as 20% of the world’s total energy, and manufacturing

Figure 12.A.1

Energy cost

Maintenance cost

Initial cost

Other cost

Lifecycle cost of pump (See color figure)

In the present chapter, different types of pumps, their selection procedures, governing laws, and

234



Handbook of Energy Audit

12.A.1

CENTRIFUGAL PUMP

It is the mostly used radial machine in the world because it is simple, safe, requires minimum periphery of the rotating element known as the impeller. The impeller is a casting having vanes on

Direction of rotation

Outlet

Figure 12.A.2



Impeller Impeller blade

Inlet

Centrifugal pump with flow direction

Outlet

Impeller

Inlet

Courtesy: Grundfos

12.A.2 POSITIVE-DISPLACEMENT PUMP

volume of the system. It can be reciprocating or rotary in nature. Such pumps are more suitable for the following applications: multistage centrifugal pumps. This pump can produce pressure up to 500 bar.

Energy Audit of Pumps, Blowers, and Cooling Towers

235

of energy.

Motion

to more moving parts and, hence, an inventory of spares is needed to be maintained to reduce downtime.

Plunger

Packing Discharge pipe

Suction pipe

Suction check valve

Discharge check valve Liquid cylinder

a. Piston-type or plunger-type Figure 12.A.3



b. Vane-type

c. Lobe-type

Positive-displacement pumps

12.A.3 PUMP TERMS AND AFFINITY LAWS

The Q-H curve, or

. 3

D p = rgH

2

Flow

Pressure or head

Pressure or head

1 Kinetic (rotodynamic)

Positive displacement

Flow

Figure 12.A.4 Flow vs head curve (pump curve) for centrifugal and positive-displacement curve

236

Handbook of Energy Audit

is the location where the pump is mounted. Higher the head, more the pumping cost. It is the height at is system working on the same level will have only friction loss and it can be minimized by reducing

Pressure of head

Pressure of head

Pump curve

Best efficiency point Operating point

Static head or lift Flow

Figure 12.A.5

Flow

System curve and combined system and pump curves

power consumption increases and it operates with noise and vibration.

60

Temp rise, lower efficiency, noise, vibration

Increased power, lower efficiency, noise, vibration

54 Performance curve

48 42

EEP Efficiency

Head 36 (m) 30 24 18

Efficiency (%) 70 12 60 50 9 40 bhp 6 (kW) 30

bhp

12

20 10 0

6 0

Figure 12.A.6

6.3

12.6 Flow (L/S)

3 0

18.9

Best efficiency point for centrifugal pump

Energy Audit of Pumps, Blowers, and Cooling Towers

237

Dptotal = Dpstatic + Dpdynamic where Dpstatic is measured at the inlet and outlet of the pump by a differential pressure sensor. Thus, Dpstatic = Dpstatic,out – Dpstatic,in 1 2 1 2 rVout - rVin 2 2 In practice, dynamic pressure drop is not measured, instead, it is calculated from the following Dpdynamic =

1 Ê Q ˆ2 Ê 1 1 - 4 ˆ˜ Dpdynamic = r Á 4 Ë ¯ 2 p / 4 Ë Dout Din ¯ P2 stands for shaft power. Phyd

P1 stands for supply power and stands for hydraulic power which is transferred from the shaft to

Phyd = rgQH Or r gQH 3600 ¥ 103

Phyd

where r = density in kg/m3 = gravitational constant = 9.81 m/s2 3

= head in m P[W]

h[%] hhyd P1

htot

P2

Q[m3/h]

Figure 12.A.7

Q[m3/h]

Power and efficiency curves

is the ratio between hydraulic power and shaft power and is given by the following equation. hhyd =

Phyd ¥ 100 P2

238

Handbook of Energy Audit

Phyd ¥ 100

htotal =

P1

The is a term describing the condition where vapour bubbles generated due to low pressure result in cavitation in a pump. It generally occurs in centrifugal pumps. The liquid vaporizes in tiny bubbles and when the surrounding pressure increases, these surrounding surface, damages the impeller, and erodes the casing and pipe surfaces. It is harmful because it reduces head and creates vibration in the pump. It also damages bearings and seals.

document provided by him/her.

(Pabsolute, total - Pvapour )

NPSHavailable =

rg

where Pabsolute, total is absolute pressure at the inlet of the pump and Pvapour is vapour pressure at the available required, to avoid vaporization 1. Lowering the pump compared to water level in the open system. 2. Increasing system pressure in the closed system. 3. Reducing length and increasing diameter of the suction line to reduce friction and velocity loss.

100

es

su

50

re

Fl ow

75

er

Pr w

25

Po

% of flow or pressure or power

proportional to the speed, the head is directly proportional to the square of speed, and pumping power is directly proportional to the cube of the speed.

0 1

Figure 12.A.8

20

40 60 80 100 % maximum pump rotation speed

Graphical representation of affinity laws

Energy Audit of Pumps, Blowers, and Cooling Towers

239

Q2 N2 = Q1 N1 H2 ÊN ˆ = Á 2˜ Ë N1 ¯ H1

2

P2 ÊN ˆ = Á 2˜ Ë N1 ¯ P1

3

where Q is head, N is pump speed, D is impeller diameter, and P is the pumping power. Similarly, for a given pump with constant speed, the capacity of the pump is directly proportional to the impeller diameter, the head is directly proportional to the square of the impeller diameter, and pumping power is directly proportional to the cube of the impeller diameter. Interrelation of these Q2 D2 = Q1 D1 H2 ÊD ˆ = Á 2˜ Ë D1 ¯ H1

2

P2 ÊD ˆ = Á 2˜ Ë D1 ¯ P1

3

EXAMPLE 12.A.1

Solution 2900 ˆ ÊN ˆ Q2 = Q1 Á 2 ˜ = 1100 Ê = 911.42 lit/m Ë 3500 ¯ Ë N1 ¯ Revised head 2

2900 ˆ 2 ÊN ˆ = 60.41m H2 = H1 Á 2 ˜ = 88 Ê Ë 3500 ¯ Ë N1 ¯ Revised power consumption 3

2900 ˆ 3 ÊN ˆ = 15.07 kW P2 = P1 Á 2 ˜ = 26.5 Ê Ë 3500 ¯ Ë N1 ¯

of power.

Handbook of Energy Audit

Pressure of head

240

Operating points

Flow

Figure 12.A.9

Change of pump speed on performance curve

Note saving potential. EXAMPLE 12.A.2

Solution applied to get the revised working conditions. 9 ÊD ˆ Q2 = Q1 Á 2 ˜ = 1135 Ê ˆ = 928.6 lit/m Ë Ë D1 ¯ 11¯ Revised head 2

9 2 ÊD ˆ H2 = H1 Á 2 ˜ = 34 Ê ˆ = 22.76 m Ë 11¯ Ë D1 ¯ Revised power consumption 3

9 3 ÊD ˆ P2 = P1 Á 2 ˜ = 10.5 Ê ˆ = 5.75 kW Ë 11 ¯ Ë D1 ¯ �

12.A.4 FLOW CONTROL AND PUMP LOSSES

Pump performance is affected by mechanical and hydraulic losses, resulting in smaller head, lesser

Energy Audit of Pumps, Blowers, and Cooling Towers

241

or drive, which consists of bearings, gear, shaft seal, etc. Hydraulic loss is due to friction in the

following methods help achieve the same: 1. Use of throttle valve

Pressure of head

3. Speed control 4. Use of multiple pumps

System curve #2 with throttle valve partially closed

System curve #1 with throttle valve fully opened

Wasted energy

Useful energy Flow Required flow

Figure 12.A.10



12.A.5

Loss in energy due to throttling

SERIES AND PARALLEL ARRANGEMENT OF PUMPS

242

Handbook of Energy Audit

+ F1

~

F

Flow

+ F1



12.A.6

P2

~ F2 Flow

Pressure of head

P1

Flow

Figure 12.A.12

Flow

Flow

Series arrangement of pump

Pressure of head

Pressure of head

Figure 12.A.11

Pressure of head

Pump 1 Pump 2

P1

Pressure of head

Pressure of head

P1 + P2

P F1 + F 2 Flow

Parallel arrangement of pumps

SELECTION OF PUMP

temperature, initial cost, maintenance cost, pumping layout, etc., are required. The pump should be 3

etc. 4. Thermodynamic properties like gravity, viscosity, vapour pressure, etc., are necessary for proper pump selection. Viscosity and gravity decides the pump capacity and vapour pressure is required to know whether cavitation will occur or not. upper range of pressure and head delivered by rotary, reciprocating, and centrifugal pumps.

Energy Audit of Pumps, Blowers, and Cooling Towers

243

Reciprocating pumps are more suitable for higher pressure range (up to 10,350 bar) and centrifugal 3 /h). head. Once deciding on the type of pump, the pump capacity is decided from the resistance curve

and consume more power. It is economical to purchase a small pump to meet today’s requirement and replace it with a large pump when demand increases in future or run a second pump in parallel range on the system curve. 100,000

Capacity, m3/h 10 100

1

10,000

1000

10,000

1000

Reciprocating Rotary

100

1000

10

100

10 1

Figure 12.A.13

1 10

100

1000

10,000

100,000

Approximate upper limits of different types of pumps

EXAMPLE 12.A.3

Solution r¥ g ¥Q¥ HˆÊ 1 1ˆ Power difference = Ê Ë 3600 ¥ 103 ¯ ÁË n A nB ˜¯ Energy saving per year = 10.94 kW ¥ 4400

hours ` 7 =` ¥ year unit

Pressure, bar

Pressure, mp/m2

Centrifugal

244

Handbook of Energy Audit

Pump

Positive displacement

Reciprocating

Dynamic Pressure Drop (Kinetic)

Rotary Centrifugal

Piston Plunger

Diaphragm

Vane Screw Gear Lobe

Axial

Mixed

Turbine

Jet

Radial

Chart 12.A.1 Classification of pumps



12.A.7 ENERGY-SAVING POTENTIAL IN A PUMP

Like other engineering equipment, energy saving is possible right at the design and selection stage. However, if it is missed at the design stage, there are some other methods by which power

Table 12.A.1

Energy saving in pumps Working condition

Oversized pump

Energy-saving potential

1. 2. 3. 4. 5.

Select a small pump which operates near BEP. Change or trim impeller. Use a multispeed pump. Use pumps in parallel. Use a variable-speed drive.

Flow throttle

Same as above

Wear and tear

Regular maintenance

Oversized motor

Use small motor.

Inefficient motor

Use energy-efficient motor.

Insufficient pipe diameter

Use large pipe diameter.

Energy Audit of Pumps, Blowers, and Cooling Towers

12.A.7.1

245

Correct Sizing of Pumps

Uncertainty is also due to change in weather. Pumps are also oversized to meet gradual resistance

One or more of the following working conditions indicate oversizing of pump:

The remedy of an oversized pump is to downsize the same, but it is not always possible and, hence, some other alternatives are suggested here:

12.A.7.2

Trim Impeller of an Oversized Pump

the impeller is removed by machining and, thereby, energy consumption is reduced. The pump

trimming. not smaller than the minimum diameter shown on the pump curve. It is to be noted that a trimmed EXAMPLE 12.A.4 ≤

Solution Using the equation, ÊD ˆ H2 = H1 Á 2 ˜ Ë D1 ¯ ÊD ˆ 50 Á 2 ˜ Ë 14 ¯ D2 = 12≤

2

2

246

Handbook of Energy Audit

Reduction in power consumption due to impeller trimming is calculated by the following equation: ÊD ˆ P2 = P1 Á 2 ˜ Ë D1 ¯

3

12 3 P2 = 120 Ê ˆ Ë 14 ¯ P2

(Pold - Pnew ) ¥ Annual operating hours

Energy saving per year =

Motor efficiency

120 - 75.56) ¥ 8200 Energy saving per year = ( 0.92 ` Impeller sizes 200

Iso-efficiency lines

8¢¢ 78%

180

Head (ft)

160

7¢¢

140

6¢¢

120

5¢¢

76% 74%

100 Head/flow curves

4¢¢

80 60 40 20 0 0

50

100

150

200

250

Flow (gpm)

Figure 12.A.14

Performance curves for various impeller diameters

12.A.7.3 Keeping the Pump Clean and Well Maintained

and gradually increases load on the system. Timely inspection and proper maintenance will ensure pump remains working in clean conditions. Regular maintenance reduces losses and unscheduled downtime. The main cause of wear and corrosion is high concentrations of particulates and low pH values. Here are a few locations where pumps are likely to fail.

Energy Audit of Pumps, Blowers, and Cooling Towers

12.A.7.4

247

Select Right-Size Motor for a Pump

Usually, one size large motor is selected to meet requirements and actually this working condition

Table 12.A.2

Energy cost of pump driven by 100 kW motor at full capacity operating at 90% efficiency

Operating time

Electricity cost in rupees ` 5 /unit

` 6 /unit

` 7 /unit

5.60

6.70

7.80

24 hours

133.30

160

186.70

1 month

4000

4800

5600

1 year

48667

58400

68134

1 hour

12.A.7.5

Review Flow-Control Methods

. Use of a and

pumps operating near to full load. They are of either mechanical or electrical type. In a mechanical

12.A.7.6

Use of Multiple-Speed Pumps

compared to opting for parallel pumps with additional piping.

248

Handbook of Energy Audit 200 180

High speed

System curve

160 140 120 Head (ft) 100

Medium speed 4¢¢

80

Pump curves

60

Low speed

40 20 0 0

50

100

150

200

250

Flow (gpm)

Figure 12.A.15 Multiple-speed pump

12.A.7.7 Check Pipe Layout

like: 1. Improper diameter of pipe. Small diameter causes frictional loss and big diameter will reduce pressure.



12.A.8

STEPS TO DESIGN NEW PUMPING SYSTEM

Identify Requirement pump performance is understanding pump requirements. Identify peak demand, average demand,

∑ ∑ ∑ these applications. ∑ ∑

Energy Audit of Pumps, Blowers, and Cooling Towers

249

Design the Pumping System Design the pumping system which consumes minimum energy. Consider the following design aspects: ∑ Consider present energy price to select motor, pump, and other devices. ∑ ∑ speed pumps. Do not buy an oversized pump or motor for ‘safety margin’. ∑ Ensure that performance measurement and monitoring is possible in the system.

that losses are minimized. Some design guidelines are given below: ∑ to the process. ∑ Use less number of bends and turns in the piping layout. Use shallow bends instead of deep ones. ∑ resistance and steel pipes are smoother than galvanized iron pipes.

Thumb Rules



PART B: FANS AND BLOWERS

Ventilation and industrial processes use fans and blowers to circulate air in plants. They generate pressure to move air or gases against the resistance created by friction while passing in ducts, energy from it. Difference Between Fan, Blower, and Compressor

250

Handbook of Energy Audit

Table 12.B.1

Pressure ratios of fans, blowers, and compressors Pressure ratio



Rise in pressure (bar)

Fan

Up to 1.11

0.11

Blower

1.11 to 1.20

0.2

Compressor

More than 1.20

0.2 onwards

12.B.1

CLASSIFICATION OF FANS

are like propellers, increase the speed of the air stream with the rotating impeller. The speed increases as it reaches the end of the blades and then it is converted to pressure energy. In a centrifugal fan, air direction changes twice. Though having

temperature, tolerance for corrosion and dust particles, cost, availability, etc. Fan

Centrifugal flow

Backward curved

Forward curved

Axial flow

Inclined

Radial

Chart 12.B.1

12.B.1.1

Tube axial

Propeller

Vane axial

Classification of fans

Centrifugal Fans

has blades that curve in the direction of rotation. These fans operate of air at relatively low pressure. Their low speed and noise level makes them suitable for heating and ventilation applications of lower capacity. They are used for clean applications. R V1

Figure 12.B.1

R

V2 V1

R

V2

V2

V1

Wheel-vector diagram for forward, backward, and radial fans

Energy Audit of Pumps, Blowers, and Cooling Towers

251

R R is used for high air volumes. Housing Fan wheel Gas out

Gas in (a) Forward curved

Figure 12.B.2

(b) Backward curved

(c) Radial

Centrifugal fans

12.B.1.2 Axial Fans

pressurizes the air. Compared to centrifugal fans, they are compact and of low cost and, hence, are

Figure 12.B.3

Images of centrifugal and axial fans

force produces kinetic energy with a small increase in potential energy. �

12.B.2

curve.

FAN LAWS AND CURVES

252

Handbook of Energy Audit

Table 12.B.2

Fan laws

Variable speed (n)

p•n

Variable impeller diameter (d)

2

p•d

Variable density (ρ)

2

p•r

3

Q•n

Q•d

Q is fix

P • n3

P • d5

P•r

n = rotational speed = impeller diameter r = air density

= power consumption

Q = Qi ÊÁ Ë

nf

ˆ ni ˜¯

p = pi ÊÁ

nf

ˆ ni ˜¯

2

n p = pi ÊÁ f n ˆ˜ Ë i¯

3

Ë

Static pressure 20

Static pressure 20

18

18

16

16

14

14

12

12

10

SP

110% of speed

10 SP

8

8

6

6

4

4

2

2 5

10 15 CFM in 1000's

90% of speed

5

10 15 CFM in 1000's

Figure 12.B.4 Fan curve of a centrifugal fan

Energy Audit of Pumps, Blowers, and Cooling Towers

Table 12.B.3

253

Centrifugal fan

Type of centrifugal fan

Advantage

Forward-curved fans

Handle low to medium volume at low pressure and low speed; Small size; Lower noise level; Low cost

Low pressure ratio; HVAC application Suitable for clean applications; Low efficiency (55 to 65%); Power increases with airflow

Backward-curved fan

Efficiency is higher than forward-curved fans (85%); Can handle change in pressure; Suitable for forced-draft applications; Robust blades

Suitable for clean applications; Blades are thin and erode at long run

Radial blades

Airfoil

Disadvantage

Application

HVAC applications; Process industry

Handle low to medium Lowest efficiency volume at high pressure; Simplest in construction; High strength; Easy to repair; Can operate without vibration at low flow rate; Can handle dust-laden flow

Material-handling; High-pressure applications; Handles highparticulate airstream

Highest efficiency. Airfoil contour of blades; Saves power

HVAC applications

Suitable for clean applications

254

Handbook of Energy Audit

Table 12.B.4

Axial fan

Type of axial fan

Advantage

Disadvantage

Application

Propeller

Low cost due to simple construction; Low pressure and Air circulation; Can handle high volume of air at low efficiency; Rooftop ventilations pressure; Noisy operation Installed without duct; Can produce flow in reverse direction which is useful in rooftop ventilation; Directly connected to motor shaft

Tube-axial

More efficient than propeller fans; Can handle medium-and highpressure range and airflow rate; Quick acceleration; Can produce flow in reverse direction

Vane-axial

Solid blades permit medium-to Costly compared to HVAC; high-pressure capacity. propeller fans Induced draft fans High efficiency (up to 85%); Drying ovens; Compact in size (compared to Paint-spray booths; centrifugal fans); Fume exhaust system Can produce flow in reverse direction; Directly connected to motor shaft

Static pressure 20

Brake horsepower 10

Ducted HVAC; Drying ovens; Paint-spray booths; Fume exhaust system

Resistance curve

9

18

8

16 SP

14

7

12

6

10

5

8

Costly and less efficient compared to propeller fans; Mostly belt driven; Less noisy compared to propeller fans

Design point

4

bhp

6

3

4

2

2

1 5

Design pressure

10 15 CFM 1000's

Figure 12.B.5

Fan curve

Design flow ratio

Fan curve with BHP and resistance curve for centrifugal fan

Energy Audit of Pumps, Blowers, and Cooling Towers

255

all pressure losses through a duct, passages, elbows, dampers, regulators, etc. The fan will operate

Increased resistance Design system Deceased resistance

Design pressure

Design flow rate

Figure 12.B.6

Fan curve for change in system resistance

90 80

To ta l

70 60 50

St

40

r

eff ic

ien

cy

e

10 10 0

y

r su es

20

ienc

pr

owe

sep Hor

re

effic

ic at

30

ss u

Tota l at ic

pr e

St

Percent of flow static pressure horsepower and efficiency

100

10

Figure 12.B.7

20

30

40 50 60 70 80 Percent of free delivery

90

100

(a) Fan curve for forward-curve centrifugal fan

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Handbook of Energy Audit

er

ow

ep ors

90 H

80

To ta

70

St

60 50

at ic

eff

To t

al

ici en

cy

40

lp re ss

ur e

ef fic

ien

ati

St

30

cy

re

cp

20

ur

ss

Percent of flow static pressure horsepower and efficiency

100

e

10 0 0

10

20

Figure 12.B.7

30

40 50 60 70 Percent of free delivery

80

Ho rse

er

80 70 60 50

St

40 30

at ic

y e nc ssur e ie r fic l pre essu ef r al Tota tic p Sta

t To

Percent of flow static pressure horsepower and efficiency

po w

90

eff

ici

20

en c

y

10 0

10

Figure 12.B.7

12.B.3

100

(b) Fan curve for backward-curve centrifugal fan

100



90

20

30

40 50 60 70 Percent of free delivery

80

90

100

(c) Fan curve for radial-blade centrifugal fan

POWER CONSUMPTION BY A FAN

The following three methods are used to calculate power consumption by a fan: 1. Using nameplate data 2. Direct measurement of power 3. Using performance curve gives quick measurement of power consumption by a fan. It is necessary to know the percentage load at which the fan works to calculate actual power consumption as in most

Energy Audit of Pumps, Blowers, and Cooling Towers

257

equation, power consumption of a fan is calculated. Fan motor capacity in kW ¥ Operating hours ¥ Electricity cost in rupees per kWh ¥ Load factor Efficiency

third method of power consumption, the pressure of the air stream is measured. Once knowing pressure, power consumption is obtained from the performance curve. �

12.B.4

12.B.4.1

ENERGY-SAVING POTENTIAL IN FANS

Fan Selection

noise, and vibration. Like other engineering systems, selection of the right fan is also a key decision in energy consumption. Sometimes, the fan is selected to meet present as well as future requirements and is selected in high operating cost, poor performance, high noise, high vibration, and frequent maintenance. Ultimately, it is costlier to operate an oversized fan rather than installing an additional fan to meet

The best alternative to an oversized fan is replacing it with a fan of suitable size, or else follow any one of these guidelines: 1. Decrease fan speed using a smaller motor. 3. 12.B.4.2

Maintenance of a Fan

per hour. This annually will cost around 33,000 rupees.

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Handbook of Energy Audit

inclined airfoil blades are more susceptible to dust and moisture deposition. Check bearing lubrication and grease quality periodically to ensure frictionless and noiseless always saves cost and time compared to reactive maintenance. 12.B.4.3

Identify and Rectify Leakage

Multi vane dampers

Figure 12.B.8

Multivane dampers

measuring device. The tighter the ductwork, the lesser the air needed from the fan to create change amount of air leakage in the ductwork.

hours, and effectiveness of control.

increases air pressure. Thus, reduced air output is achieved at the cost of additional unwanted performance curve). reduce the angle of attachment between the incoming air and fan blades and, thereby, reduces

Energy Audit of Pumps, Blowers, and Cooling Towers

259

variations occur.

used with contaminated air.

12.B.4.5

Use of Variable-Frequency Driven Fans

maintenance cost, and no mechanical linkage for speed change. Due to a long list of advantages applicable in a speed range where fans become unstable as it may lead the fan to run at a resonant frequency causing high vibration level and damaging the fan. 12.B.4.6

Reduce Pressure Loss in the Duct by Proper Duct Design

D

(0.109136 q1.9 ) d e5.02

where Dp = frictional pressure drop in air (inches water gauge/100 ft of duct) e = equivalent duct diameter (inches) In case of a rectangular duct, the equivalent diameter is calculated as per the given equation: Ê (a ¥ b )0.625 ˆ

e = 1.30 ¥ Á Ë (a + b )0.25 ˜¯

12.B.4.7

Fans in Series and Parallel Arrangements

option. Series installation is used for long ducts or large pressure ratio; and parallel installation is and installed

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Handbook of Energy Audit

C, where the resistance curve intersects the combined characteristics C. In series installation, air a

b D

Q pa

fan b

fan a

pb

a

Qa Qb

b

pc

pc = pa + pb

C

Fan pressure p

Fan pressure p

Combined fans

Qc

fan a

fan b A

B

C

p

Combined fans

pb

B

E

pa

A Effective resistance curve

Figure 12.B.9 Table 12.B.5

Q c = Q a + Qb

Qa Qb

Q Airflow Q

Airflow Q

Fans in series and parallel arrangements

Suggestions in fan installation for ductwork

Mount the fan in the direction of air flow and provide straighter flow.

Keep L = 3D for entry of fan after a bend in ductwork.

D

If not possible to maintain L = 3D, use a gradual bend instead of a sharp one.

L

Energy Audit of Pumps, Blowers, and Cooling Towers

261

Or provide smoother flow in a sharp bend.

A tee joint located very near to the fan may create swirl in flow, to avoid it, maintain some distance between the fan and tee. L

D

Change in direction of airflow will create pressure loss.

The flow is in the direction of fan delivery, which is advisable compared to the previous case.



PART C: COOLING TOWER

capacity of a cooling tower is stated in

. Cooling load is decided by the amount

capacity in all weather conditions and under variation of load. with the atmospheric air by evaporative cooling phenomenon. Some amount of hot water evaporates, absorbing latent heat of vaporization from the remaining water and as heat is removed from the remaining water, its temperature reduces. The end result is air temperature and humidity increase while water temperature decreases.

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Handbook of Energy Audit

12.C.1

CLASSIFICATION OF COOLING TOWERS

, due to direct contact between hot water and atmospheric air, evaporation of some amount of water takes place. Evaporation absorbs latent heat of vaporization from the surrounding

tower, hot water is circulated inside the coils, which are cooled by water circulated on their outer side. The difference in open and closed cooling towers is shown in Chart 12.C.1. Cooling Towers

Evaporative/Wet/Open

Non evaporative/Close

Natural Draft

Counter flow

Artificial Draft

Cross flow

Induced draft

Chart 12.C.1

Forced draft

Balanced draft

Types of cooling towers

to be regularly inspected, else it may cause capacity reduction in the cooling tower.

Hot water

Hot water

Fill

Centrifugal fan

Centrifugal fan

Cold water Cold water

Figure 12.C.1

Open and closed cooling towers

Energy Audit of Pumps, Blowers, and Cooling Towers

(also known as

263

) uses the buoyancy effect of

air causing a current of air through the cooling tower. This type of cooling tower does not require fans, motors, etc., but uses a large space and is generally installed by utility power station. They

Figure 12.C.2

Natural-draft and artificial-draft cooling towers

is more disposed to recirculation of moist air due to its low velocity and as fans are to be mounted



12.C.2

PERFORMANCE OF A COOLING TOWER

∑ Range indicates effective heat removal. Range = (Cooling water inlet temperature,°C – Cooling water outlet temperature,°C) (12.C.1) ∑ Approach of cold water leaving the cooling tower. The lower the approach, the better the performance.

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Handbook of Energy Audit

inlet air, °C)

(12.C.2)

∑ Effectiveness evaluates the performance of cooling tower and is given as the following ratio. (Cooling water outlet temperature,°C - Cooling water outlet temperature °C) ¥ 100 = (Cooling water outlet temperature,°C - Wet bulb temperature of inlet air °C) =

Range ¥ 100 Range + Approach

(12.C.3)

∑ Cooling capacity following: V¥r¥C ¥D

(12.C.4)

3 /s V r = density of water in kg/m3

where

p

= temperature difference of inlet and outlet water ∑ Evaporation loss represents loss of cooling water. The general rule is 0.43 m3 of water is ∑ Cycle of concentration is the ratio of dissolved solids in circulating water to the dissolved solids in makeup water. Total dissolved solids in the makeup water (12.C.5) Total dissolved solids in the bled off water ∑ Blowdown loss is the amount of water loss due to periodic blowdown process and is given by the following equation. Evaporation loss (COC - 1) Cycle of concentration =

∑ Drift

cooling tower. �

12.C.3

12.C.3.1

COMPONENTS OF A COOLING TOWER

Packing Materials

slats are arranged in a staggered pattern. Hot water falls on this distribution deck and then it is

plastic sheets joined in a honeycombed shape. .

are suitable for pure water and are more

Energy Audit of Pumps, Blowers, and Cooling Towers

265

Figure 12.C.3 Images of packing material

12.C.3.2

Hot-Water Distribution System

12.C.3.3

Cooled Water Basin

in litres per minute. 12.C.3.4

Fans and Controllers

cooling towers.

capable to save power over the large range of load variation. Thermostatically operated dampers control air volume by opening or closing the air inlet. 12.C.3.5

Louvers and Drift Eliminators

and prevent water from coming out of the tower structure. Drift eliminators are labyrinth passages with the help of drift eliminators. 12.C.3.6

Tower Material of a Cooling Tower

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Handbook of Energy Audit

resist corrosion. Stainless steel is costlier than galvanized steel but can withstand corrosion. The galvanized steel. In a highly corrosive environment, SS 304 is used. Special coating on the tower

lightweight, chemically resistant, and able to handle variation in pH value. �

12.C.4

METHODS TO IMPROVE EFFICIENCY OF COOLING TOWER

There is very little scope to reduce energy consumption after installing a cooling tower. It is very much important to select the right size of cooling tower to achieve the best of its performance.

12.C.4.1

Sizing of the Cooling Tower

Like other systems, the sizing of cooling tower has direct impact on energy consumption. Heat load, range, approach, and ambient wet bulb are key parameters to decide the size of the cooling tower. Certain effects of these parameters on size of the cooling tower are described here: 1. Size of cooling tower • heat load 2. Size of cooling tower • 1 / range 3. Size of cooling tower • 1 / approach 4. Size of cooling tower • 1 / wet bulb temperature

have similar effects. The basic four parameters are necessary to size a cooling tower: (i) heat load temperature of ambient air. EXAMPLE 12.C.1

Solution V¥r¥C ¥D where

V

3

/s

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267

= density of water in kg/m3 p

D = temperature difference of inlet and outlet water 150 ¥ 1000 ¥ 4.18 ¥ 5 3600

12.C.4.2

Reduce Water Loss

12.C.4.3

Reduce Blowdown

Due to evaporation of water from a cooling tower, the concentration of water increases due to increased amount of contaminants, salts, minerals, etc. If not removed, these may cause biological growth, scale, and corrosion, and ultimately reduce heat transfer and cause tower damage. blowdown process and equivalent fresh makeup water is added. The amount of water to blowdown is judged by the quality of water, ultimately measured by the conductivity of water. To optimize water blowdown, periodical measurement and comparison of water quality is required. Contaminants and quality of water are measured in terms of of Total dissolved solids is the concentration of minerals in water and is measured in milligrams per litre or parts per million. Higher COC is advisable as it reduces the number and volume of blowdown. Its recommended value is more than 5. Cycle of concentration =

Total dissolved solids in the recirculation water Total dissolved solids in the makeup water

irrigation, cleaning, etc. 12.C.4.4

Maintenance, Monitoring, and Optimization

Regular maintenance, continuous monitoring, and optimization of a cooling tower will improve its

maintain cooling tower.

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Handbook of Energy Audit

media, etc. 3. Use conductivity probe to reduce unnecessary blowdown and recalibrate if required.

12.C.4.5

Minimizing Corrosion and Scale

Complete elimination of corrosion is a nearly impossible task in the aqueous environment.

be added to reduce biological growth. and condenser. It creates a coat on the surface which reduces heat transfer and, ultimately, heat duty of the system. Calcium, magnesium, and silica are primary sources of scale formation. The pH of scaling additives, pH control, removal of calcium and magnesium ions, etc. 12.C.4.6

Variable Frequency Drive for Fans

power varies proportionally with the cube of its speed, a small speed reduction will result in large

THUMB RULES

Energy Audit of Pumps, Blowers, and Cooling Towers

CHECKLIST FOR PUMPS, FANS, AND COOLING TOWERS

269

270

Handbook of Energy Audit

Descriptive Questions

Short-Answer Questions

Energy Audit of Pumps, Blowers, and Cooling Towers

Numerical Problem

`

Fill in the Blanks

271

272

Handbook of Energy Audit

Justify the Following Statements

Multiple-Choice Questions

Answers Fill in the Blanks 1. 2. 3. 4. 5. 6. 7. 8. Multiple Choice Questions 1. 2.

9. 10. 10% 11. 12. 13. 14. 15. 16.

3.

13

Energy Audit of Lighting Systems



13.1

FUNDAMENTALS OF LIGHTING

Lighting quantity and quality is basically expressed in watts, lumens, and illuminance. ∑ Watt the rate of energy consumption by the lighting system. ∑ Lumen is the most common measure of light output. Light sources are labelled with an

lumen depreciation occurs). Thus, the number of lumens describes how much light is being produced by the lighting system. ∑ illuminance, which is measured in foot-candles—workplane lumens per square foot. Foot-candles are the end result

Figure 13.1.

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Handbook of Energy Audit

Power Input watts

Light output lumens

Light level (Illuminance) Footcandles (Lumens/SF)

Brightness (Luminance) Footlamberts (candelas/m2)

Workplane

Figure 13.1

The concept of watt, lumens, and illuminance

usually in all engineering systems and it

∑ Thus, produce 50 to 90 lumens per watt, and high-pressure sodium lamps produce as much as 140 lumens per watt. uniformity of illuminance, colour rendition, colour rendering index, colour temperature, etc., are described below. ∑ Glare keyword is

∑ Contrast

and increase annoyance. ∑ The

Energy Audit of Pumps, Blowers, and Cooling Towers

275

∑ The

areas, and bright and dark spots which cause discomfort to occupants. ∑ The ability to see colours properly is another aspect of lighting quality. In simple terms, the Colour Rendering Index

the occupants to distinguish colours. For example, a room with a colour printing press requires illumination with excellent colour rendition. In comparison, outdoor security lighting for a building ∑ Colour temperature



13.2

DIFFERENT LIGHTING SYSTEMS

In general, there are four types of lamps commonly used. 1. Incandescent lamp 2. Fluorescent lamp 3. High-intensity discharge lamp 4. Light-emitting diodes 13.2.1

Incandescent Lamp

The oldest electric lighting technology is the incandescent lamp. Incandescent lamps are also the

276

Handbook of Energy Audit

shapes are shown in Figure 13.2. Bulb Filament Gas

Base

Tubular

Figure 13.2

13.2.2

Candle

Flame

A-lamp

Globe (G-lamp)

Construction of a typical incandescent lamp and common shapes

Compact Fluorescent Lamps (CFLs)

lamps. They are made of two parts, the lamp and the ballast. The short tubular lamps can last longer

and sizes as shown in Figure 13.3.

Modular twin tube

Modular circular

Self-ballasted twin tube

Self-ballasted triple tubes

Modular quad tube

Figure 13.3

Different types of compact fluorescent lamps

Energy Audit of Pumps, Blowers, and Cooling Towers

13.2.3

to

Fluorescent Lamps

, producing

13.2.4

277

electricity to excite mercury light which causes a phosphor . The most common light sources used for building interiors are

High-Intensity Discharge (HID) Lamps

called high-intensity discharge. Normally, HIDs are used for outdoor and industrial applications;

3. High-pressure sodium 4. Low-pressure sodium Mercury Vapour

Metal Halide

industrial facilities, sports arenas, and other spaces where good colour rendition is required. Figure

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Handbook of Energy Audit

Nitrogen fill gas BaO2 getter

Quartz tube

Outer bulb

Main electrode Outer bulb

Argon fill gas and mercury

Shroud Arc tube

Starting electrode

Main electrode UV enhancer

SAES getter

Starting resistor

Mogul base

Figure 13.4

Source:

Construction of a high-pressure mercury-vapour lamp and a metal halide lamp

, 9th Edition

High-Pressure Sodium (HPS) as shown in Figure 13.5, are an economical choice for most outdoor and some industrial applications

and metal halide lamps in that they do not contain starting electrodes; the ballast circuit includes

colour rendition. Low-Pressure Sodium (LPS)

limited to security or street-lighting. and controlling a light beam, compared with point sources like high-pressure sodium and metal

Energy Audit of Pumps, Blowers, and Cooling Towers

279

Amalgam reservoir with sodium and mercury Main electrode Xenon fill gas, sodium and mercury vapor

Vacuum

Ceramic arc tube Arc tube mount structure

Main electrode Hard glass bulb

Mogul base

Figure 13.5

Construction of a high-pressure sodium lamp

Light-Emitting Diodes (LEDs)

story, particularly with regard to directional light sources. Due to the directional nature of their light

intended location. Typical LED shapes are shown in Figure 13.6.

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Handbook of Energy Audit

Chip LED

Subminiature LED

T-1 3/4 Lamp T-1 3/4 Oval

Figure 13.6

Table 13.1

High flux emitter

Very high flux emitter

Typical LED shapes

General information on different types of lamps Incandescent Standard

Wattage

3–1500

Halogen

Fluorescent Full–size or U–Bent

Compact

HID Metal halide

High–pressure sodium

10–1500

4–215

5–58

32–2000

35–1000

Lamp efficiency 6–24

8–35

26–105

28–84

50–110

50–120

Average rated life (hours)

750–2000

2000–4000 7500–24, 000 10, 000–20, 000 6000–20, 000 16, 000–24, 000

Cri (%)

99

99

Start–to–full brightness

82–86

65–96

Immediate Immediate 0–5 seconds

0–5 minutes

1–15 minutes 4–6 minutes

Re–strike time

Immediate Immediate Immediate

Immediate

2–20 minutes 1 minutes

Lumen maintenance

Very good Excellent

Good

Fair/Good



13.3

49–96

Very good

21–65

Very good

BALLASTS

.

the lamp impedance decreases. As ballasts are an integral component of the lighting system, they

Energy Audit of Pumps, Blowers, and Cooling Towers

281

Magnetic Ballast

1. Standard core-and-coil

Standard Core-and-Coil Such magnetic ballasts are essentially core-and-coil transformers the aluminium wiring and lower grade steel of the standard ballast with copper wiring and enhanced

that cut off power to the lamp cathodes after the lamps are operating, resulting in an additional Electronic Ballasts

to a higher frequency, usually 25,000 to 40,000 Hz. Lamps operating at these higher frequencies

capabilities. An electronic ballast is designed to operate up to four lamps at a time. In addition, parallel wiring is another feature that allows all companion lamps in the ballast circuit to continue

failed. Thus, the electronically ballasted system will reduce time to diagnose problems. Due to a HID Ballast



13.4

FIXTURES (LUMINARIES)

types of luminaries. The following is a list of some of the common luminary types.

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Handbook of Energy Audit

¥ 4, 2 ¥ 2, and 1 ¥ 4 2. 3. 4. 5.

Fluorescent for direct lighting Indirect lighting Spotlights or accent lighting Task lighting



13.5

REFLECTORS



13.6

LENSES AND LOUVRES

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283

computer screens. �

13.7

LIGHTING CONTROL SYSTEMS

in the reduction of energy consumption of the lighting without impeding comfort goals. Hence, Different parameters are to be studied before deciding the type of lighting control system like

control systems are discussed in the following section. 13.7.1

Timers (Time-Scheduling Control System)

The time-scheduling control system is used to reduce the operating hours of the lighting installation according to building occupancy. Different schedules can be programmed for different areas of the building based on the occupant needs. The time-scheduling control strategy enables switching on or off automatically based on-time schedules and occupancy patterns for different zones. Twenty-four hour timers allow the occupants to set certain times for lighting. 13.7.2

Dimmer

that allows ballasts from different manufacturers to be used with compatible systems. is a way to control the light output of the luminaires based on a limited

13.7.3 Photocell

For most outdoor lighting applications, photocells which turn lights on when it gets dark, and

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Handbook of Energy Audit

sources. Sensors are often used in large areas, each controlling a separate group of lights in order to

illuminance strategy. 13.7.4

Infrared Presence Sensors

most common sensors used in the building sector are

that react to

control units.

13.7.5

Ultrasonic Presence Sensor

There are products combining the two technologies, called

They see greater control

working hours, except when other sensors indicate that a space is occupied. �

13.8

LIGHTING SYSTEM AUDIT

Energy audit of a lighting system depends on the end user, and, hence, has to be tailor-made. The Step 1 Observation

condition, etc. D. Find the type of control used for the lighting system.

Energy Audit of Pumps, Blowers, and Cooling Towers

285

E. Identify the task/operation performed by the occupant/resident. Step 2 Output Measurement

D. Estimate electrical consumption. Annual lighting cost = Annual working hours ¥ number of lamps ¥ watts per lamp ¥

rate kWh

If lamps are of different capacities then calculate accordingly. Average luminance on the working plane Circuit watt Step 3 Input Measurement with a power analyzer. If total power is not measurable, try to measure power consumption of at least one or two lamps and calculate the total power consumption. Step 4 Compilation of Results

Step 5 ILER Analysis

L ¥W Hm ¥ (L + W ) where L, W, and

m

Installed load efficacy Target Installed Load Efficacy

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Handbook of Energy Audit

Table 13.2

Target installed load efficacy

Room index

Commercial and clean industrial areas with CRI = 40–85

Industrial lighting with CRI = 40–85

Industrial lighting with CRI = 20–40

1

36

33

52

1.25

40

36

55

1.5

43

39

58

2

46

42

61

2.5

48

44

64

3

50

46

65

4

52

48

66

5

53

49

67

Table 13.3

ILER range ILER



Assessment

0.75 or above

Satisfactory to good

0.51 to 0.74

Review suggested

0.5 or less

Urgent action required

13.9

ENERGY-SAVING OPPORTUNITIES

frequent, and if occupancy is infrequent, use suitable lighting controls.

life and lead to an increased need for lamp/e-choke replacements and, hence, higher operation and

13.9.1 Daylighting

as much light as a dozen or more lightbulbs, and the light quality is unsurpassed. Exposure to

Energy Audit of Pumps, Blowers, and Cooling Towers

A new way to add daylighting to a room is with a

287

as shown in Figure 13.7. These ¢¢ to 20¢¢

tubes bring daylight into the house with much less disruption of roof and ceiling construction

Figure 13.7

13.9.2

Task Lighting

13.9.3

Solar-Powered Lighting

A typical skylight tube

Another way to power lighting, particularly for outdoor lights, is to use solar energy. A panel uses the solar energy of the sun to generate electricity, which is stored in a battery. The

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Handbook of Energy Audit

13.9.4

Group Re-lamping

The largest cost of a lighting system to a commercial user is not the initial cost of lamps and installation, but energy and maintenance costs. The largest lighting maintenance cost is relamping—

use a practice called . In a typical non-group relamping procedure, when a lamp burns out in the workplace, it is

installation procedure. Hours or days later, another lamp burns out somewhere else and the process is repeated. This can take a lot of time, disrupt worker or customer operations, and introduce safety concerns.

regular basis. This allows trained maintenance-staff members to schedule access to an area, bring

group relamping.

13.9.5

De-lamping

luminaries, and reducing the number of lamps has ensured that the illuminance is marginally a useful concept. 13.9.6

Daylight Saving

on residential lighting use. In-depth research is required to analyze the possibility of splitting the

Energy Audit of Pumps, Blowers, and Cooling Towers

289

than three years.

2. Lighting technology older than 10 years. 3. Lighting system has crossed its useful life and is poorly maintained. 5. High electricity charges. Use of Metal Halide Lamps Installation of metal halide lamps in place of mercury/sodium-

line, inspection areas, painting shops, etc. Use of High-Pressure Sodium-Vapour Lamps

Use of Light Emitting Diode (LED) Lamps Installation of LED panel indicator lamps in place lesser power consumption and longer life. Use of Electronic Ballast

from about 20,000 Hz to 30,000 Hz. The losses in electronic ballasts for tubelights are only about 1

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Handbook of Energy Audit

Table 13.4

Effect of electronic ballast Type of lamp

With conventional electromagnetic ballast

With electronic ballast

Power savings, watts

40 W Tubelight

51

35

16

35 W low-pressure sodium

48

32

16

70 W high-pressure sodium

81

75

6

Select T5 Fluorescent Tubelights

glass and the phosphors. This drastically reduces the need for mercury from about 15 milligrams to

Streetlights contribute to peak power consumption of

make an area safer and secure. potentially reduce energy consumption.

glowing hours. Bachat Lamp Yojana As per the

Energy Audit of Pumps, Blowers, and Cooling Towers

The

291

aims at the large-scale replacement of incandescent bulbs in households

The `

CHECKLIST

292

Handbook of Energy Audit

Descriptive Questions

Bachat Lamp Yojana.

Short-Answer Questions lumen

illuminance

Energy Audit of Pumps, Blowers, and Cooling Towers

Numerical Problem ¢ ¢

Fill in the Blanks

Answers 1. 2. 3. 4.

5. 6. 7. 8.

¢

293

294

Handbook of Energy Audit

9. 10. 11. 12.

13. 14. 15. 16.

14

Energy Audit Applied to Buildings It is very surprising that when buying a new car, people are very much concerned about economy, but when buying a new home or making a new building (whose of energy and its impact on environment is almost equal in both cases.

Green buildings

LEED (Leadership in Environmental and Energy Design) assesses buildings against a set of established environmental performance criteria of energy, water

Table 14.1

Some LEED rated buildings in India Project name

Pune Chennai Gurgaon

Gold

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Handbook of Energy Audit

this chapter.

Air conditioning Other equipment

Chart 14.1



14.1

Lighting Ventilation fans

Energy consumption in a commercial building (See color figure)

ENERGY-SAVING MEASURES IN NEW BUILDINGS

As we know, conduction, convection, and radiation are three modes by which heat is transferred from high-temperature atmospheric air to the building envelop. Chart 14.1 shows approximate heat gain by a building by different heat sources. As shown in the chart, the highest amount of heat is poured through glazed walls followed by internal-heat gain and roof-heat gain. Some energysaving aspects to reduce heat gain and, thereby to reduce energy consumption, are discussed here. 14.1.1

Maximize Use of Natural Energy Flow

HVAC need of the building is directly related to difference between inside and outside temperatures. trapping and storing solar radiation in winter—minimizing the burden of the HVAC system and geographical location and surrounding climate of the building. This is also known as passive design of the building. Key elements describing passive design are discussed here: 1. Orientation of Building Orienting a building in the proper direction will have passive heating and cooling in all weather and helps reduce energy bills. A building should have minimum exposure in south and west directions to reduce direct heat load from sunrays for Indian latitudes and longitudes falling in hot regions. 2. Insulation Insulation is selected based on several criteria like lifespan, cost, applicable temperature range, weather effect, etc. Some building materials like concrete, brick, etc., serve the purpose of insulation. They also average day and night temperature difference, and thereby increase comfort at reduced energy cost.

Energy Audit Applied to Buildings

297

3. As shown in Chart 14.2, maximum heat gain in a building is through glazing and windows. Thus, they are designed and located to maximize cool breeze to enter the building in summer and minimize winter winds to enter the building in winter. 4. Skylights As mentioned in Chapter 13, use of daylight is the ideal source in terms of quality Some skylight options are shown in Figure 14.1.

Figure 14.1

Chart 14.2

Different fixtures for skylights (See color figure)

Conduction through glazed walls

Internal heat gain

Roof conduction

Wall conduction

Approximate heat gain in a building premises (See color figure)

14.1.2 Envelop Heat Gain

The location of a building decides heat gain by its envelop. As our country spreads over a wide geographical span, different states have variations in average atmospheric temperature. Figure 14.2 shows the general atmosphere of a particular location. A summary of advisable indoor conditions are given in Table 14.2. To reduce heat gain through building envelops, some suggestions are given here:

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Handbook of Energy Audit

1. Select high-performance glazing with low U light transmittance. bricks to reduce heat ingress. 3. Select and use proper insulation material on sun-facing walls and roofs. 4. Consider window shades, venetian blinds (window blinds), or tree plantations outside the building to reduce direct heat gain.

Leh

Delhi

Ahmedabad

Kolkata

Hyderabad

Legends Bengaluru

Hot and dry Hot humid Composite Gold Moderate

Map of India showing different climatic zones (map not to scale) Figure 14.2

Different climate zones of India (See color figure)

Energy Audit Applied to Buildings

299

14.1.3 Equipment Selection

equipment/system consider the following aspects: high star ratings. 2. Use variable-frequency drives for ventilation fans, pumps, etc. 3. Select and locate the cooling tower to perform at its best. 4. Use heat-recovery wheels, heat-pipe-based heat-recovery systems, and economizers in HVAC units. 5. Take maximum advantage of time of day tariff (pumping of water during night hours to reduce daytime electricity consumption). 6. Install wind curtains on all openings. 7. Install occupancy sensors on escalators to avoid continuous running. 8. Adopt building-management system for effective control of equipment. 9. Select and use CFC-free refrigerant in HVAC equipment, which has minimum ozonedepletion potential. Table 14.2

Recommendations for different types of weather

Climate zone

Recommended building conditions

Hot and dry

Reduce heat gain by proper orientation. Decrease exposed surface area. Increase thermal mass and resistance. Decrease ventilation during daytime and increase during night time. Increase use of shades with fins and trees. Use light colours on wall exteriors. Use reflective tiles on the roof. Use open-water surfaces, i.e., ponds, fountains, etc., to increase evaporative cooling.

Hot and humid

Reduce heat gain by proper orientation. Decrease exposed surface area. Increase thermal mass and resistance. Increase ventilation during day and night. Increase use of shades with fins and trees. Use light colours on wall exteriors. Use reflective tiles on the roof. Use dehumidifiers and desiccant-based cooling systems to reduce humidity.

(Contd.)

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Handbook of Energy Audit

(Contd.) Climate zone

Recommended building conditions

Composite

Reduce heat gain in summer and loss in winter. Decrease exposed surface area. Increase thermal mass and resistance. Increase ventilation in summer and monsoon and decrease in winter. Increase use of shades with fins and trees. Use light colours on wall exteriors. Use reflective tiles on the roof. Increase humidity in summer and decrease in monsoon.

Cold

Reduce heat loss. Decrease exposed surface area. Increase thermal mass and resistance. Decrease ventilation. Decrease use of shades with fins and trees. Use dark colours on wall exteriors and glass to absorb more solar radiation.

Moderate

Reduce heat gain. Decrease exposed surface area. Increase thermal mass and resistance. Increase ventilation. Increase use of shades with fins and trees. Use light colours on wall exteriors. Use reflective tiles on the roof. Increase humidity in summer and decrease in monsoon.

14.1.4

Insulation

After selecting appropriate insulating material, it is necessary to install it without any cavity or air gap. They need to be protected from sunlight, moisture, wind, and other weather effects. 14.1.5 Cool Roof

Maximum solar radiation is received by the roof of the building as it is continuously exposed to the sun. Heat received by the roof surface is partly absorbed and transmitted to the building and partly

decides the amount of solar radiation received by building. cool roofs that temperature is 10 to 15ºC lesser than conventional buildings in peak summer. Use of whitecoloured china mosaic tiles or white cement tiles also reduces solar radiation received by buildings.

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301

14.1.6 Improving Air-tightness

1. 2. 3. 4.

Installing continuous vapour retarders on walls and ceilings. Blocking holes, cracks, and open surfaces. Proper sealing around windows and doors. Proper sealing around pipeworks and ductworks.

of green buildings are summarized in Table 14.3. Table 14.3

Benefits of green buildings Benefits of green buildings

Builder/Developer

Employee

Owner

Different identification and image







Saleability of building





Higher rents





Higher return on investment





Higher re sale value



More work satisfaction and productivity

√ √



Reduction in water consumption



Reduction in energy consumption



14.1.8 Co-ordination Between Designer and Developer

Lack of coordination has been observed in the Indian construction industry, which ultimately results in fast and nasty designs. Instead of technical designs and software, developers still use rules of thumb in many cases. Awareness and building code mandates may help increase the number of green buildings. 14.1.9 HVAC Sizing and Number of Lightings

It is observed that most buildings have oversized air-conditioning plants installed and same is the case in lighting. It is also observed that highest or lowest temperatures just exist for 2 to 5% of the than future expansion plans or thumb rules. Similarly, excessive lighting should be discouraged, as it adds load on the HVAC system and energy bill.

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Handbook of Energy Audit

As per IGBC codes, installed chillers and air conditioners of a building should meet the following performance values to meet requirements of a green building. Table 14.4

Minimum power consumption of chiller units as per IGBC codes Type of chiller

Capacity (ton)

Minimum COP

Minimum IPLV

Air-cooled chiller

Less than 150

2.90

3.16

Air-cooled chiller

More than 150

3.05

3.32

Centrifugal water-cooled

Less than 150

5.80

6.09

Centrifugal water-cooled

150 ton to 300 tons

5.80

6.17

Centrifugal water-cooled

More than 300

6.3

6.61

Reciprocating, water-cooled

All sizes

4.2

5.05

Rotary, screw, and scroll compressor, water-cooled

More than 150

4.7

5.49

Table 14.5

Minimum power consumption of AC units as per IGBC codes Maximum power consumption (kW)

Cooling capacity (kW)

1.7 2.6 3.5

4.4 5.2

7.0 8.7 10.5

Unitary AC

Package AC

Split AC

Water-cooled

Air-cooled

1.1 1.4 1.6 2.0

3.75 6.00 9.00 11.5

4.75 7.00 10.0 13.5

– – 1.7 –

2.4 3.2

17.0 –

20.0 –

2.6 3.4

4.25





4.5

5.2





5.4

Reduced use of water has direct impact on the environment and indirect impact on energy saving. A building design should utilize the groundwater table and reduce municipal-water demand through effective management of rainwater. Providing a rainwater harvesting system will capture run-off water from the roof area. water-treatment system to treat wastewater generated in the building. Treated wastewater or

14.1.11

Adopt Solar Water Heating

A solar water-heating system has a collector area and storage tank. The collector is made of an insulated box having an array of water pipes attached to black-painted metal sheets. The collector box might have a glass or plastic cover to retain solar energy. Solar water heating can be of passive

Energy Audit Applied to Buildings

303

or active type. In passive systems, circulation of water is gravity-assisted and, hence, does not require pump. A tank connected with a collector stores hot water. The schematic of passive and active solar water-heating systems are shown in Figure 14.3. In an active solar water-heating system, a pump circulates water from the storage tank. Up to 90% of energy saving is possible with building. Calculate total hot water requirement of the building at the design stage and install solar panels at the initial stage of the building. Tank

Collector

Pump Controller Tank

Collector

Figure 14.3

14.1.12

(A)

(B)

Passive and active solar water-heating systems

Promote Use of Decentralized Power Plants

Distributed generation, or decentralized power plants, are small-capacity generators using many sources of energy. These plants have excellent economics of scale and if run with green fuel, they have positive impact on the environment. A biofuel-based or non-edible-oil-based decentralized power plant is an option of utility power and reduces dependence on fossil fuels. 14.1.13

Energy-saving Measures in Existing Buildings

Fear of rapid depletion of exhaustible energy sources, global warming, climate change, and mushroom growth in the construction industry are reasons for conducting energy audits of existing

data collection, analysis, identifying opportunities, planning, and then implementing. The list of information to be collected by an audit team is listed below: 1. Building plan and HVAC layout. 2. Energy cost and tariff data. 3. Type of chiller, capacity, and operating pattern. 4. Details of fan, pump, pipework, ductwork, etc.

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Handbook of Energy Audit

5. Occupancy with respect to time and day. 6. Various equipment and systems installed. 7. Type and numbers of luminaries and their control mechanisms. 8. Power distribution and transformer details. 9. Details of lift, escalators, and their operating hours. 10. Other sources of energy if used like gas, diesel, etc. After obtaining the above data, the energy-audit team will compare the same with design and historical data. Major deviations in current data, design data, and historical data for a particular system or equipment are an indication of abnormality. The following parameters can be assessed to compare data: 1. COP or IPLV of the HVAC system. 3. Piping-system frictional losses. 5. Heat loss from hot water or steam lines. Follow this principle for data collection: “Do not estimate what you can calculate and do not calculate what you can measure.” It is also critical to decide the points of data collection. Follow technical guidance given in respective chapters to collect the data of an HVAC system, lightings, pumps, motors, etc., to have accurate data. The next task after data collection is analyzing. At this junction of time, the audit team will screen and spot the parameters for which qualitative and quantitative deviations in trends are observed. These points are sources of energy-management opportunities, now onward noted as EMO. present-value calculations, etc., for suggested changes. If required, lifecycle cost assessment will be carried out for a particular EMO. It should be noted that the EMO should not downgrade the quality of service or working environment, e.g., increasing room temperature will save energy but creates uncomfortable working conditions for residents or employees. The EMO should also consider previous audit recommendation or due maintenance, if any, which is followed by implementation. The Energy Utilization Factor (EUI) is a platform to compare energy consumptions of different buildings of similar nature. Annual energy consumption (14.1) EUI = Gross floor area Collect the energy-consumption data in the following format. Table 14.6 Month

January February March

Data sheet kWh

KVA

PF

kW

Energy charges Demand charges

Total cost

Diesel or gas charges

Energy Audit Applied to Buildings

305

April May June July August September October November December

If a building uses gas or diesel as a secondary form of energy, add their monthly consumptions. area is taken in m2 �

14.2

2

.

WATER AUDIT

water consumption by various activities. Like energy audit, water audit is also a part of energy assessment of an existing building. It is an assessment of the capacity of total water produced by the governing authority and actual quantity of water distributed throughout the assessment area (e.g., town, municipal corporation area, township, etc.) The difference between the two is known as nonrevenue water or unaccounted water. A water audit also gives qualitative and quantitative analyses of water consumption. Advantages of a water audit are listed below: 1. It encourages social responsibility by identifying wasteful use of water. 2. It promotes water conservation and thereby reduces cost of water distribution and pumping. Water-audit Methodology

Like an energy audit, the method to carry out a water audit depends upon many parameters like water source, population, type of use, climatic condition, source of wastewater generation, legal requirements, distribution network, etc., and, hence, an audit method is a tailor-made method applicable to a particular end user. However, general guidelines are given here for carrying out a water audit. Part A: Planning and Preparation It includes data collection and preparation of site sketch.

Verify the mapped water-distribution system with the existing watersupply system for piping layout, valves, connections, etc. Verify that water meters are available or can be installed at major supply points, tube-well supply to the main line, reservoir supply line, etc.

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Handbook of Energy Audit

density, number of operating hours and per capita consumption or per ton consumption, raw water plant, demineralization plant, reverse osmosis plant, wastewater plant, etc. Collect the data of operating details of various pumps in each stream and operating hours. Also, collect water-quality details at all key points. In case of any breakdown or scheduled maintenance occurring in history, collect the data for the same. Part D: Analysis The information collected will be consolidated and used to prepare overall

1. Locations that need immediate action to repair leak. 2. Locations that need water losses closely monitored. taking advantage of time of day tariff. �

14.3

HOW TO AUDIT YOUR HOME?

Audit of a single-family a residence is fairly simple. It starts with gathering information of the building envelop, and past electricity and gas bills. List the number of plugged equipment at your home. In an air-conditioned house, inspect insulation and seals for windows and doors, and the integrity of ducts. From past energy bills, analyze the consumption and identify patterns or anomalies. Ceiling 40%

Walls 25%

Drafts 10%

Windows 15%

10% Floors

Figure 14.4

Energy saving from different parts of a building

Identify potential energy-saving opportunities from the analysis, e.g., performance deviation in the air-conditioning system, adding insulation, service requirement of hot-water system, adding

analysis.

Energy Audit Applied to Buildings



307

14.4 GENERAL ENERGY-SAVING TIPS APPLICABLE TO NEW AS WELL AS EXISTING BUILDINGS

1. Use solar control glass to restrict solar radiation to pour through glazing. They permit light and restrict radiation from entering the building and, thereby keep the building-temperature low. 2. Keep high-heat-generation processes away from the building or use exhaust/ventilation fans for them. 3. Some locations have a big difference in day and night temperatures. It is advisable to use high thermal mass material (concrete, bricks, tiles, etc.) in such locations, as they are able to keep the building warm during winter nights and cold during summer days. 4. Replace outdated thermostats with programmable ones. 5. Rather than using an air conditioner, install ceiling fans, as in many cases, air movement is

replace them. 7. Maintain and clean lamps for best performance. 8. Reduce the number of lamps in nonworking areas or use low-wattage bulbs. 10. Avoid acrylic paints or wallpaper, instead use natural paints or low Volatile Organic Compound (VOC) paints. 11. Use indoor plants as they add oxygen to the atmosphere and eliminate harmful volatile organic compounds. 12. Use on-demand hot-water heaters instead of storage-type hot-water heaters. gain from window glass. An SHGC of 0.3 indicates that the window allows 30% of solar radiation to pass across the window glass. 14. Encourage the use of electric vehicles in township, campus, etc., and provide electricvehicle-charging facility. 15. Promote use of solar, wind, biogas, and biomass energy to reduce burden on the utility. 16. Encourage continuous monitoring of energy performance. Use different meters for external data are available. 17. In case of residential and hospital buildings, segregate waste (dry, wet, paper, plastic, and e-waste separately. Identify the scope of recycling green waste in the campus. 18. Encourage use of salvaged building materials and products instead of virgin material.

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Handbook of Energy Audit

Descriptive Questions

Short-Answer Questions

Fill in the Blanks

summer.

Multiple-Choice Questions

Energy Audit Applied to Buildings

Answers Fill in the Blanks 1. Leadership in environment and energy design 2. 3. Cool roof 4. Multiple-Choice Questions 1. (d) 2. (d)

309

15

Thermal Insulation and Refractory Materials



15.1

BENEFITS OF THERMAL INSULATIONS

∑ Energy Saving ∑ Protection ∑ Maintain Process Temperature ∑ Minimize Temperature Variation and Fluctuation ∑ Prevent Condensation

∑ Fire Protection ∑ Freezing Protection ∑ Reduced Level of Vibration and Noise �

15.2

HEAT TRANSFER MECHANISM IN THERMAL INSULATION

Thermal Insulation and Refractory Materials

311

thermal conductivity

15.2.1 Conduction

dT Q� = -k A dx dT/dx

k

A 2

15.2.2

Convection

forced convection free convection

Q� = h A Ts – T 2

h

Ts – T 2

A 15.2.3

Radiation

T

312

Handbook of Energy Audit

Ts4 – T

4

Q� = e s A (T 4s - T •4 ) A

e e 15.2.4

¥

–8

2

K

4

Thermal Conductivity

Table 15.1

Thermal conductivity values of some common materials Material

Thermal conductivity, W / m ºC

Silver

429

Copper

401

Aluminium

237

Iron

80.2

Mercury

8.54

Glass

0.78

Brick

0.72

Water

0.613

Wood

0.17

Soft rubber

0.13

Glass fibre

0.043

Air

0.026

Urethane foam

0.026

2

Thermal Insulation and Refractory Materials

Table 15.2

313

Required properties of insulating materials

Property of material

Condition required

Thermal conductivity

As low as possible.

Mechanical stability

Able to withstand vibration, expansion, and contraction.

Durability

Able to withstand extreme operating temperature.

Weight

As less as possible or else additional support is required.

Thickness

As small as possible for compactness.

Water absorption

Water increases thermal conductivity of insulation and reduces its effectiveness; hence, it should be less.

Effect of chemicals

Able to resist chemicals/fumes used in the surrounding environment.

Effect of microbes

Able to resist vermin and fungal growth, especially in food storage and factory applications.

Emissivity

Low surface emittance is required.

Health hazards

It should be asbestos-free to reduce danger of inhalation of fine particles.

Fire hazards

The material itself should be noncombustible in case of fire-prone or smokeinvolved applications.

Corrosion

In case of wetted insulation (due to leak or internal condensation), the insulation-soluble compounds should not promote corrosion.

15.2.5

R-value of Insulation

R L k

R L

k r2 r2 ln k r1

R r2

r R

Q� =

DT ¥ Area R-value

314

Handbook of Energy Audit

R Table 15.3

R-values of common insulating materials R-value (m2 K/ W)

Material

Silica aerogel

1.76

Polyurethane rigid panel

1.3

Urea foam

0.92

Fibreglass rigid panel

0.44



15.3

CLASSIFICATION OF THERMAL INSULATION

resistive insulation Capacitive insulation

Thermal Insulation

Capacitive

Reflective

Resistive

Fibrous

Cellular

Granular

Inorganic

Organic

Wood fibre

Cloth fibre

Animal hair

Chart 15.1

Cotton fibre

Loose fill

Ceramic fibre

Based on shape

Rigid

Glass fibre

Classification of thermal insulation

Blankets and batts

Mineral fibre

Insulation cement

Thermal Insulation and Refractory Materials

15.3.1

315

Fibrous Insulation

Table 15.4

Properties of rock mineral wool Rock mineral wool

60 to 160 kg/m3

Density Thermal conductivity, W/mº C

Density, 80 kg/m3

Mean temperature, 10 Service temperature, ºC Fire characteristics Water-vapour transmission Compressive strength Shapes available Thickness available Applications

Table 15.5

0.033

–200 to 900 Noncombustible Nonpermeable 10.5 kN/m2 for 80 kg/m3 density Loose fill, mats, pipe section, rolls, slabs 20 to 120 mm Used as a thermal and acoustic insulation and fire protection of plant, equipment, marine, offshore, HVAC, industry, commercial, domestic sectors

Properties of glass mineral wool Glass mineral wool

Density

10 to 80 kg/m3

Thermal conductivity, W/mº C Mean temperature, ºC

Density, 48 kg/m3

Density, 80 kg/m3

–20

0.028

0.028

10

0.030

0.031

20

0.032

0.032

50

0.035

0.035

100

0.044

0.042

Contd.

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Handbook of Energy Audit

Glass mineral wool

Service temperature, ºC

–200 to 450

Fire characteristics

Noncombustible

Water-vapour transmission

Nonpermeable

Compressive strength

1 to 8 kN/m2 at 5% deformation

Shapes available

Blown fibre, pipe section, rolls, slabs

Thickness available

15 to 150 mm

Applications

Widely used for thermal and acoustic insulation in HVAC applications, transport, shipping, building, etc.

Table 15.6

Properties of ceramic fibres Ceramic fibre (blanket)

Density

64 to 192 kg/m3

Thermal conductivity, W/mº C Mean temperature, ºC

Density, 96 kg/m3

Density, 128 kg/m3

100

0.041

0.03

300

0.079

0.06

600

0.14

0.12

800

0.22

0.18

1000

0.36

0.28

Maximum temperature, ºC

1250

Fire characteristics

Noncombustible

Water-vapour transmission

Permeable

Compressive strength

2.5 kN/m2 at 10% deformation

Shapes available

Logs, sections, slabs

Thickness available

6 to 50 mm

Applications

Thermal and acoustic insulation for motor, petrochemical and power generation, fire protection of commercial buildings and offshore structures

Thermal Insulation and Refractory Materials

15.3.2

317

Cellular Insulation

Table 15.7

Properties of cellular glass Cellular glass

Thermal conductivity, W/mº C Mean temperature, ºC

Density, 120 kg/m3

Density, 135 kg/m3

–100

0.034



0

0.038

0.044

10

0.04

0.046

100

0.081



Temperature range. ºC

–260 to 430

Fire characteristics

Noncombustible

Water-vapour transmission

Nonpermeable

Compressive strength

700 kN/m2

Shapes available

Board, pipe shells, slabs

Thickness available

40 to 160 mm

Applications

Cold storage and marine applications, tank and vessel bases, buildings. etc.

15.3.3

Granular Insulation

Vermiculite

expanded perlites

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Handbook of Energy Audit

Table 15.8

Properties of calcium silicate Calcium silicate

Thermal conductivity, W/mºC

Maximum temperature, ºC Fire characteristics Compressive strength Shapes available Thickness available Applications

Mean Temperature, ºC Thermal Conductivity 100 0.054 150 0.058 200 0.063 250 0.068 300 0.074 350 0.082 1000 Noncombustible 600 kN/m2 at 1.5% deformation Logs, sections, slabs 25 to 100 mm Steam pipes and vessels, ovens, petrochemical, furnace, general heating, process insulation, and-food processing plants

Figure 15.1 Table 15.9

Images of different insulating materials

Properties of vermiculite Vermiculite

Density Thermal conductivity Service temperature, ºC Fire characteristics Water-vapour transmission Compressive strength Shapes available Applications

50 to 150 kg/m3 0.067 W/m °C for a density of 104 kg/m3 0 to 1300 Noncombustible Permeable 10.5 kN/m2 for a density of 80 kg/m3 Depends upon type of application Loose-fill granular insulations are used in loft insulation, steel works, foundries, packing, plasters, building boards, etc.

Thermal Insulation and Refractory Materials

Table 15.10

319

Properties of expanded perlite Expanded perlite

Density

50 to 150 kg/m3

Thermal conductivity

0.057 W/m °C for a density of 80 kg/m3

Service temperature, ºC

–250 to 1000

Fire characteristics

Noncombustible

Water-vapour transmission

Nonpermeable

Shapes available

Loose-fill granular material

Thickness available

25 to 300 mm

Applications

Used as a structural insulation for domestic and commercial buildings; also used for low-temperature applications



15.4

Table 15.11

DIFFERENT FORMS OF INSULATION MATERIALS AVAILABLE IN THE MARKET

Shapes available for different insulating materials

Insulating material

Calcium silicate

Board

Block





Cellular glass √

Mineral wool



Polystyrene and polyurethane



√ √

Pipe fitting





Fibre glass

Perlite

Sheet

√ √









√ √

320



Handbook of Energy Audit

15.5

SELECTION OF INSULATING MATERIAL

∑ Purpose/Application

∑ Type of Surface ∑ Surrounding Condition

∑ Ease of Applying/Frequent Removal

∑ Cost



15.6

CALCULATION OF INSULATION THICKNESS

U=

D D2

1 ÊD ˆ ÊD ˆ D3 ln Á 2 ˜ D3 ln Á 3 ˜ Ë D1 ¯ Ë D2 ¯ 1 D3 + + + D1 hi 2 kw 2 ki ho

D

D D

D2 hi kw

ho ki

Thermal Insulation and Refractory Materials

U=

321

1 ÊD ˆ D3 ln Á 3 ˜ Ë D2 ¯ 1 + 2 ki ho

Q = p D3 U (Tin - Tout ) L T

T

EXAMPLE 15.1 Compare heat loss and calculate annual saving due to application of insulation in the following case: Outer diameter of pipe = 4.5≤ (114.3 mm) and thickness = 3.05 mm

2

Insulation thickness is 32 mm and cost of insulation is `500 /m. Operating hours are 8760 hours per year.

U=

1 ÊD ˆ D2 ln Á 2 ˜ Ë D1 ¯ 1 D2 + + 2 kw ho D1 hi

Solution U=

1 ÊD ˆ D2 ln Á 2 ˜ Ë D1 ¯ 1 D2 + + 2 kw D1 hi ho

= 9.89 W

W m2 K

2

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Handbook of Energy Audit

U=

W 1 = 1.314 2 ÊD ˆ m K D3 ln Á 3 ˜ Ë D2 ¯ 1 + 2 ki ho

Q = p D3 U (Tin - Tout ) L Q L Q L DQ¥

Q

¥

DQ DQ = = 3668 kWh hboiler 0.8 ¥ ` `



15.7

ECONOMIC THICKNESS OF INSULATION

Simple payback

Cost

H+1 I

economic thickness of insulation I H+I

MC H

H

M

M M

Insulation thickness

Figure 15.2

Critical thickness of insulation

Thermal Insulation and Refractory Materials

323

EXAMPLE 15.2 Calculate economic thickness of insulation for Example 15.1. Additional data: Table 15.12

Cost of insulation for different thicknesses Insulation thickness in mm

Cost of insulation per metre in `

0.5≤ 1≤ 1.5≤ 2≤ 2.5≤ 3≤ 3.5≤ 4≤

450 500 565 635 715 810 915 1030

U Table 15.13

Q/L

Result table

Insulation thickness, mm

Pipe diameter after addition of insulation, mm

0.5≤ 1≤ 1.5≤ 2≤ 2.5≤ 3≤ 3.5≤ 4≤

139.7 165.1 190.5 215.9 241.3 266.7 292.1 317.5

Overall heat transfer co-efficient, W/m2 ºC

4.26 1.972 1.230 0.873 0.665 0.530 0.437 0.369

Heat loss Q/L, W/m

222.5 121.00 87.59 70.46 59.90 52.80 47.72 43.79

Cost of heat loss, `

267 145.20 105.11 84.65 71.88 63.38 57.26 52.54

Cost of insulation, `

450 500 565 635 715 810 915 1030

Total cost, `

717.00 645.20 670.11 719.65 786.44 873.33 972.26 1082.54

324

Handbook of Energy Audit

≤ ≤



15.8

REFRACTORY MATERIAL

Refractory material

Chemical composition

Type of shape

Unsapped refractory

Shapped refractory

Acid (silica, zirconia)

Chart 15.2

Neutral (Alumina, carnon graphite)

Type of use

Basic (magnesia Dolomite)

Classification of refractory materials

metallurgy industry nonmetallurgy industry



15.9

PROPERTIES OF REFRACTORY MATERIALS

Melting Point

Metallurgical

Non metallurgical

Thermal Insulation and Refractory Materials

325

Table 15.14 Melting temperature of different constituents of refractory materials Constituents of refractory materials

Melting temperature, ºC

Graphite

3500

Magnesia

2800

Lime

2570

Magnesia

2200

Alumina

2050

Fireclay

1870

Silica

1715

Porosity

Bulk Density

Pyrometric Cone Equivalent (PCE)

Figure 15.3

Thermal Expansion

creep

Thermal Conductivity

Pyrometric-cone preparation

326

Handbook of Energy Audit

Cold Crushing Strength 2



15.10

COMMONLY USED REFRACTORY MATERIALS

Fireclay Bricks 2

2O

High-Alumina Refractory

Silica Bricks Figure 15.4

A sample of fireclay brick

2

Magnesite Refractory

Dolomite, Chromite, Zirconia, and Monolithic Refractory Dolomite

Chrome magnesite

refractory Zirconia

refractory

Figure 15.5

Monolithic refractory casted in required shape

Thermal Insulation and Refractory Materials

Monolithic refractory

Ceramic Fibre—An Insulating Refractory



15.11

SELECTION OF REFRACTORY MATERIAL



15.12

HOW TO IMPROVE LIFE OF A REFRACTORY MATERIAL

327

328

Handbook of Energy Audit

CHECKLIST

Descriptive Questions

Short-Answer Questions

Thermal Insulation and Refractory Materials

Fill in the Blanks

Multiple-Choice Questions

329

330

Handbook of Energy Audit

Answers Fill in the Blanks 1. 2. 3. Multiple-Choice Questions 1. 2.

4. 5.

3.

4.

5.

16 Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation



16.1

BASICS OF A HEAT EXCHANGER

As discussed in the earlier chapter (Chapter 15), there are three modes of heat transfer which decide the heat exchange in any process or system: chemical, mechanical, or nuclear. Conduction, convection, and radiation—all three modes of heat transfer are involved in a heat exchanger. A heat recuperative heat exchanger) or there exists direct contact regenerative heat exchanger).

multitube-pass heat exchangers, while multiple shells connected in multi-shell heat exchangers. Tube outlet

Shell inlet

Baffles

Shell outlet

Figure 16.1

Tube inlet

Different views of a shell-and-tube heat exchanger

Handbook of Energy Audit

Figure 16.2

Different views of a plate heat exchanger

Shell-side fluid out Baffle

Shell

Tube sheet

Outlet plenum

Out

In Tube-side fluid

Shell side

Tube bundle with U-tubes

Inlet plenum

Baffle Shell-side fluid out

Tube bundle Tube sheet with straight tubes

Shell

Shell-side fluid in Tube sheet

Inlet plenum

332

Shell-side Tube-side fluid out fluid in

Baffle

Tube-side fluid out

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation Tube bundle with straight Tube sheet tubes

333

Tube-side fluid in

Shell-side fluid in Shell

Inlet plenum Outlet plenum

Tube-sheet Shell-side fluid out

Baffle

Tube-side fluid out

Figure 16.3 Different types of shell-and-tube heat exchangers: (a) U-tube heat exchanger (b) One-pass heat exchanger (c) Two-pass heat exchanger

Latest developments in plate heat exchangers and compactness have now made them compatible compact heat exchanger 1000 m 15,000 m

3

3 3

3

.

t1

t1 T1

T2

Parallel flow

t2

t1 T1 T1

T2 t1

t2

Position

Temperature

Temperature

T1

Figure 16.4

T2

Counter flow

T2 t2 t1 Position

Parallel and counter-flow heat exchangers with temperature and flow profiles

334

Handbook of Energy Audit

heat exchangers. �

16.2

HEAT-EXCHANGER APPLICATIONS

Chemical, mechanical, petrochemical, paper, jute, and textile industries use one or the other type of evaporator or condenser when used in HVAC, radiator superheater, air preheater, condenser, reheater or economizer when used in a power plant, intercooler when used in a compressor, etc. exchangers are discussed here. Preheater

In case of thermal power plants, live steam is trapped off and is used to preheat the condensate. plant, exhaust gas is used to preheat air. Radiator atmosphere. Air being a poor conductor needs more surface area and, hence, the radiator tubes are Evaporator and Condenser

rejecting heat to the surrounding air or water.

Figure 16.5

Images of evaporator, air preheater, and steam condenser

Steam Condenser It is a major component of thermal power plants. In this heat exchanger, steam gives up its latent heat of condensation to the cooling water. After the steam condenses,

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

335

the condensate temperature reduces and is subcooled and collected in the bottom or condenser hot well

pump is used. �

16.3

16.3.1

PERFORMANCE OF A HEAT EXCHANGER

Log Mean Temperature Difference (LMTD)

q 2 - q1 DT2 - DT1 = q2 DT ln ln 2 q1 DT1 2 = Th2 – Tc2 1 = Th1 – Tc1

= Dq = where = 1= 2

and Th and Tc

considering overall heat transfer by conduction and convection. Q� = UADTm where, Q Q� = U

(mC p DT )h = (mC p DT ) c K.

Q=

Q=

T1 - T2 = UA DToverall Dx 1 1 + + h1 A kA h2 A T1 - T2 = UA DToverall r D ln o r 1 1 i + + ho Ao hi Ai 2p kL

( )

336

Handbook of Energy Audit

T2, h2 T1, h1

T1, h1

r2

r1 T2, h2 x1

x2

Figure 16.6

Q=

Heat transfer in plane wall and cylinder

T1 - T2 ro R fi D ln ri R 1 1 + + + o + hi Ai Ai Aio ho Ao 2p kL

( )

1

U= 1 + R fi + hi

A D ln

(r r ) + R o

i

2p kL

fo

+

1 ho

where R and Rfo Table 16.1

Fouling factors for different types of waters

Type of water

Velocity

Fouling factor (m2K/W); Cooling-water temperature < 50ºC; Cooled fluid < 120ºC

Fouling factor (m2K/W) Cooling-water temperature > 50ºC; Cooled fluid >120ºC

< 1 m/s

>1 m/s

< 1 m/s

> 1 m/s

Sea

0.00009

0.00009

0.00018

0.00018

Brackish

0.00035

0.00035

0.00053

0.00053

City grid

0.00018

0.00018

0.00035

0.00035

River

0.00018

0.00018

0.00035

0.00035

Engine jacket

0.00018

0.00018

0.00018

0.00018

Demineralized or distilled

0.00009

0.00009

0.00009

0.00009

Treated feedwater

0.00018

0.00009

0.00018

0.00018

Boiler blowdown

0.00035

0.00035

0.00035

0.00035

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

Table 16.2

Fouling factors for other fluids Fouling factor (m2K/W)

Type of fluid

Gas oil

0.00009

Transformer oil

0.00018

Lubrication oil

0.00018

Hydraulic oil

0.00018

Engine exhaust

0.00176

Steam

0.00009

Compressed air

0.00035

Natural gas

0.00018

Cooling fluid

0.00018

Organic heat transfer fluid

0.00018

Salt

0.00009

LPG and LNG

0.00018

Caustics

0.00035

Vegetable oil

0.00053

EXAMPLE 16.1

Th1

Th1 Hot fluid

Hot fluid DT1 Th2 DT1

DT2 Tc2

dTh dQ

Tc1

Cold fluid

dTc

Tc1

DT2 Tc2

End 1

Figure 16.7

Th2

End 2

End 1

End 2

Hot and cold fluid temperatures for parallel- and counter-flow heat exchangers

Solution LMTD =

DT2 - DT1 (110 - 70) - (75 - 30) = = 37.44∞C DT (110 - 70) ln ln 2 DT1 (75 - 30)

337

338

Handbook of Energy Audit

Q� = mC p DT = UA DTm 70 ¥ 4.18 ¥ 103 ¥ (75 - 30) 60

¥A¥

A

Q� = UAF Tm F EXAMPLE 16.2

P and R factors. From Figure

Solution

and

P=

t2 - t1 T1 - t1

R=

T1 - T2 t2 - t1

where T

t P = 0.5 and R F Corrected LMTD

16.3.2

¥ LMTDD

Effectiveness — NTU Method

Log mean temperature method is useful when the inlet and exit temperatures of heat exchangers are effectiveness ratio of actual heat transfer to maximum possible heat transfer.

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

Effectiveness = Π=

Actual heat tr ansfer Maximum possible heat tr ansfer

ÈÊ -UA ˆ Ê Cmin ˆ ˘ 1 - exp ÍÁ ˜ Á1 + ˜˙ ÎË Cmin ¯ Ë Cmax ¯ ˚ Œparallel = C 1 + min Cmax ÈÊ -UA ˆ Ê Cmin ˆ ˘ 1 - exp ÍÁ 1Ë Cmin ˜¯ ÁË Cmax ˜¯ ˙˚ Î = ÊC ˆ ÈÊ -UA ˆ Ê Cmin ˆ ˘ 1 - Á min ˜ exp ÍÁ ˜ Á1 ˜˙ Ë Cmax ¯ ÎË Cmin ¯ Ë Cmax ¯ ˚

Œ

Œboiler or condenser = 1- exp

-UA Cmin

U A = area of heat exchanger ¥ = p

where

min

p value

max

p value

min

= number of transfer units LMTD Correction Factor Charts

Correction factor, F

1.0 0.9

T1

0.8 R = 4.0 3.0

2.0 1.5

1.0 0.8

0.6

0.4

0.2

0.7 0.6 0.5

R= 0

T2

T1 - T 2 t2 - t1 0.1

0.2

0.3

0.4

0.5 P=

t2 - t1 T2 - T 1

0.6

0.7

0.8

0.9

1.0

339

340

Handbook of Energy Audit

Correction factor, F

1.0 T1 0.9 t2

0.8 R = 4.0 3.0

2.0

1.5

1.0 0.8

0.6

0.4 0.2 t1

0.7 0.6

T1 - T2

R=

T2

t2 - t1

0.5 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

t2 - t 1 P= T2 - T1

Correction factor, F

1.0 T1

0.9 0.8 R = 4.0 3.0

2.0

1.5

1.0 0.8

0.6

0.4 0.2

t1

t2

0.7 0.6 0.5

R= 0

T1 - T2 t2 - t1

0.1

0.2

T2 0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

t2 - t1 P= T1 - t1

Figure 16.8

Correction factors for different heat exchangers (Reference, Kays and London)

EXAMPLE 16.3

Solution mh

ph

c = mc

pc

h=

and Capacity ratio,

min

=

h

max

=

c

=

min

= 0.76

max

NTU =

UA = 0.9 Cmin

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

341

Case 1 ÈÊ -UA ˆ Ê Cmin ˆ ˘ 1 - exp ÍÁ 1+ Ë Cmin ˜¯ ÁË Cmax ˜¯ ˙˚ Î Œparallel = = 0.452 C 1 + min Cmax min

Th1 - Th 2 Œ= Th1 - Tc1 T = 110°C T is obtained from energy balance h

(Th1 – Th ) =

c

(Tc – Tc1)

Tc Case 2 ÈÊ - UA ˆ Ê Cmin ˆ ˘ 1 - exp ÍÁ 1Ë Cmin ˜¯ ÁË Cmax ˜¯ ˙˚ Î = = 0.501 Ê Cmin ˆ ÈÊ - UA ˆ Ê Cmin ˆ ˘ exp ÍÁ 1- Á ˜ Á1 ˜˙ Ë Cmax ˜¯ ÎË Cmin ¯ Ë Cmax ¯ ˚

Œ

min

Œ=

Th1 - Th 2 Th1 - Tc1

T T is obtained from energy balance h

(Th1 – Th ) =

c

(Tc – Tc1)

Tc 16.3.3

Pinch Analysis

consumption in a process.

is a simple methodology applicable to all processes

written for enthalpy changes in a heat exchanger. It is a fact for a heat exchanger that neither a to a temperature more than the inlet temperature of hot stream. In practice, the temperature up to

pinch point in a heat exchanger.

342

Handbook of Energy Audit

An example of pinch analysis for a process is given below.

Stream = A Feed 80°C

Reactor 200°C

1

Product

2

90°C CW = B

1 Hot stream = product 1 Cold stream = feed T

Stream = A

200 100 90 80

CW = B

H

(a)

Figure 16.9 Example of a process

X amount of pinch, case with lower pinch. It is easy to perform pinch analysis on a single stream compared to a process which involves multiple streams and has complex nature. Stream = A-X Feed 80°C

1

Reactor 200°C

2

Product 90°C

CW = B-X

3

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation T

X

343

Stream = A-X

200

1 Hot stream = product 1 Cold stream = freed

100 90 80

Curves are "shifted" horizontally6 toward each other till they are vertically apart by 20°C

Figure 16.10



16.4

Recovered heat = X H CW = B-X (b)

Pinch analysis applied to a sample process

FOULING

is termed fouling fouling, heat transfer in a heat exchanger reduces and, ultimately, heat capacity of the heat exchanger overloads the pump. While designing and selecting a heat exchanger, fouling is considered and an oversized heat exchanger is selected. Various types of foulings are discussed here. Sedimentation Fouling

Inverse Solubility Fouling remove this type of fouling. Chemical Reaction Fouling Corrosion-Product Fouling necessary to prevent corrosion. Biological Fouling and grow on solid surfaces of the heat exchanger. Apart from reducing heat transfer, they may reduce biological fouling. or more mechanisms resulting in fouling. As a result of fouling, a solid layer is deposited on the surface which results in increase of conductive thermal resistance. Fouling cannot be predicted and, hence, fouling factors are used for additional resistance in designing heat exchangers. Fouling

344

Handbook of Energy Audit

Fouled bundle

Figure 16.11

Clean bundle

Images of fouled surfaces

Prevention and Removal of Fouling

disassembly of the unit.



16.5

TUBULAR EXCHANGER MANUFACTURERS ASSOCIATION

petroleum and related processes,

is for general commercial applications, and

is for is

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

Front-End Stationary Head Types

Shell Types

Rear-End Head Types

L

E A

345

Fixed Tubesheet Like-“A” Stationary Head

One-Pass Shell Channel and Removable Cover

M F

Fixed Tubesheet Like-“B” Stationary Head

Two-Pass Shell with Longitudinal Baffle B N

Fixed Tubesheet Like-“N” Stationary Head

G

Bonnet (Integral Cover)

Split Flow P Outside Packed Floating Head

H

C

Double Split Flow

Channel Integral with Tubesheet and Removable Cover

S Floating Head with Backing Device

J Divided Flow

N

T Pull-through Floating Head

Channel Integral with Tubesheet and Removable Cover

K

U U-Tube Bundle

Kettle Type Reboiler D W

X Special High-Pressure Closure Figure 16.12

Crossflow

Externally Sealed Floating Tubesheet

Shell-and-tube heat-exchanger classifications as per TEMA

346



Handbook of Energy Audit

16.6

SELECTION OF A HEAT EXCHANGER

involved, a spiral plate heat exchanger is a good solution. For HVAC applications, plate and frame as

1. Application (to cool, to heat, or to exchange heat)

5. Location and plan



16.7

METHODS TO IMPROVE EFFICIENCY OF HEAT EXCHANGERS

Heat-Exchanger Tube Inserts

complex relationship, no general correlations are available to predict

material deposits on the tube wall. Use of Fins

Figure 16.13 Tube insert for a heat exchanger

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

tube.

Finned tube

Figure 16.14

Use of Deformed Tubes of pressure drop. Deformed tubes increase turbulence and enhance boiling.

Figure 16.15

Corrugated tube

is more effective compared to conventional ones.

Figure 16.16

Spiral baffles and conventional baffles for a shell-and-tube heat exchanger

347

348

Handbook of Energy Audit

performance and size over a period of its use. Fouling, its effect, and removal methods are

transfer surface, and slag

∑ Visual Inspection ∑ Chemical-Reagent Test ∑ Pressure-change Method (Vacuum Method)

∑ Overpressure or Bubble Test

∑ Dye-penetration Method

∑ Acoustic Leak Detection It uses sonic or ultrasonic signals generated by the gas, as it ∑ Mass Spectrometer

∑ Radiotracer

and corrosion.

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation



16.8

349

WASTE-HEAT-RECOVERY EQUIPMENT

the environment or water. Recovering this waste heat has the largest potential in energy saving,

Table 16.3

Different examples of waste-heat recovery Waste fluid (rejecting heat)

Source fluid (gaining heat)

Exhaust of gas turbine Air preheating Exhaust of furnace (glass melting, cement kiln, Water preheating incinerator, metal furnace, arc furnace) Load preheating (material supplied to process) Exhaust of boiler Steam generation Exhaust of diesel engine Power generation Heat from end product (ingot, casting, etc.) Space heating Heat from hot surfaces Waste fluid (gaining heat)

Air conditioning return air at low temperature

Source fluid (rejecting heat)

Fresh air supplied to air-conditioning system

3. Chemical composition.

temperature and pressure can be increased. process).

Recovery technology (regenerator, recuperator, boiler, economizer etc.) End use of recovered heat (preheating source fluid or precooling of air in case of HVAC)

here. 16.8.1

Source of waste heat (exhasut from turbine, furnace, oven etc. or low temperature air in case of HVAC

Recuperator (Gas-to-Gas or Gas-to-Air Heat Exchanger)

Electericity production from waste heat (HRSG to produce electricity)

350

Handbook of Energy Audit Gases outlet

Gases outlet Air outlet

Gases inlet

Air outlet

Air outlet

Air inlet

Air inlet

Air inlet

Gases outlet Gases inlet

Gases inlet

(a) Double shell

(b) Cage type Air outlet

(e) Vertical-tube, bundle-type Air inlet

Gases inlet Gases outlet

(d) Horizontal-tube, bundle-type Gases outlet

Gases outlet

Gases outlet

Air outlet

Water outlet

Air inlet

Air inlet

Water inlet

Air outlet Air inlet Gases inlet (e) Combined type

Gases inlet (f)Double-shell and tube-type

Figure 16.17

Type of recuperators

Air outlet Gases inlet (g) Multifluid heating

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

351

radiation recuperators

construction, this arrangement offers minimum pressure loss and is widely used in the steel industry,

16.8.2

Rotary Wheel (Heat Wheel)

combustion chamber and has a better control of combustion process. In an HVAC heat recovery wheel, chilled outgoing air reduces temperature of hot incoming air and, thereby reduces load of

wheel is mounted is divided into two parts.

Outside air -10°C< t < 30°C

Exhaust air 31°C< t < 37°C Make up air 25°C

Figure 16.18

Rotary wheel

352

Handbook of Energy Audit

of stainless steel, brass or aluminium wire mesh, or a ceramic honeycomb for higher temperature or Flue gas carries latent heat of water vapour because as a part of combustion, moisture present in the same, rotary wheels are coated with hygroscopic material.

16.8.3

Heat-Pipe Heat Exchanger

A heat pipe thermal conductivity may be several orders of magnitude higher than that of good solid conductors.

and the condensate returns to the evaporator by means of capillary action. A heat pipe consists of a

Heat input

Wick

Heat output

Vapor flow

Liquid return Evaporator

Condenser

Figure 16.19

Single heat pipe and heat-pipe heat exchanger

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

16.8.4

Waste-heat Boiler

produce just dry saturated steam. Steam out

Cooled waste gas out

Steam dram

Feedwater in Water tubes

Hot waste gas (waste heat stream)

Figure 16.20

16.8.5

Thermoelectric Generator

3. Heat pump 5. Vapour recompression

Waste-heat recovery boiler

353

354

Handbook of Energy Audit

16.8.6

Heat-Recovery Steam Generator (HRSG)

are operated either as a cogeneration plant (steam produced is used for heating in process) or

Fuel HP CC ST GT

Air

Figure 16.21



16.9

G

LP Water

HRSG cw ST GT C HP LP

ST

G

Combustion gas

C

CW

Gas to stack

= cooling water CC = combustion chamber = steam turbine G = electrical generator = gas turbine = condenser and pump = compressor = high pressure steam = low pressure steam

Heat-Recovery Steam Generator (HRSG)

HURDLES IN THE WASTE-HEAT-RECOVERY PROCESS

is thermally and economically less viable.

economically viable.

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

355

material and coating which is uneconomical. �

16.10

CO-GENERATION

, is the simultaneous generation of useful heat and electricity from a single source of fuel or energy, near to the point of use. It is a thermodynamically

transmission. When electricity, heat, and cooling—three outputs are there from a single plant, it trigeneration or generation plant are: emission

Cooling/Heating

Steam or hot water

Water

Heat recovery unit

Hot exhaust gases

Fuel

Engine or turbine

Electricity Generator

Building or facility Grid

Figure 16.22

Concept of cogeneration

is used to produce power. A diesel power plant producing electricity and hot water is an example

356

Handbook of Energy Audit Fuel

Combustor

Very high temperature gases

Low temperature gases (exhaust)

Electricity

Generator

Compressor

Process steam

Heat recovery steam generator

Gas turbine

Water

Air High temperature gases

Figure 16.23

Gas-turbine topping cycle Low temperature gases (exhaust)

Fuel Furnace

Air

Very high temperature gases

Process

High temperature gases

High pressure steam Heat recovery steam generator

Electricity Steam turbine

Generator

Low pressure steam

Pump

Condenser Water

Figure 16.24 Table 16.4

Furnace bottoming cycle

Types of prime movers based on plant capacity

Capacity

Type of prime mover

Features

More than 4 MW

Reciprocating internal combustion engine Gas turbine

Less than 200 kW

Micro turbine

Less than 250 kW Large capacity

Fuel cells Condensing steam turbine

Suitable where heat is required in the form of hot water and low-pressure steam Suitable where heat is required in the form of high-pressure steam Compact and flexible, suitable where heat is required in the form of hot water Quiet, clean but expensive option Most popular in industry

Less than 5 MW



16.11

16.11.1

TYPES OF CO-GENERATION

Internal-Combustion-Engine Based Co-generation

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

357

the engine is cooled by force circulation of the coolant through a passage around it which is later

Customer heat exchanger

Exhaust

Engine Heat recovery

Gear box

Excess heat exchanger T Oil cooler Jacket water

Figure 16.25

Internal-combustion-engine-based CHP plant

16.11.2 Steam-Turbine-Based Co-generation

while in an extraction turbine, steam is extracted from the casing of the turbine before condenser

Fuel

Generator

Boiler

G

W

Steam turbine Steam to process

Condenser

Cooling water Condensate from process

Pump

Figure 16.26

Condensate tank

Steam-turbine-based CHP plant

Q

358

Handbook of Energy Audit

16.11.3 Gas-Turbine-Based Co-generation

Stack loss heat

Condensate return

Heat recovery generator

Steam turbine

Fuel

Air

Power

Turbine

Compressor

Generator Combustion chamber Power

To condenser

Generator

Figure 16.27

Gas-turbine-based CHP plant

16.11.4 Microturbine-Based Co-generation

application. A microturbine is a good alternative for commercial and light industrial users as these refrigeration, or as a prime mover to other systems. 16.11.5 Fuel-Cell-Based Cogeneration

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

359

of technology. A fuel cell is similar to batteries—due to electrochemical process, it produces direct

Exhaust

Recuperator

Air inlet

Fuel

Combustor Generator Compressor

Figure 16.28



16.12

Turbine

Microturbine-based CHP plant

FEASIBILITY OF A COMBINED CYCLE

indicates how the capacity of a prime mover is utilized in a combined heat and

Capacity factor =

Actual energy consumption Peak capacity of prime mover ¥ 8760

If the industry is consistently producing excess heat or steam from a process, it is a good produce steam and it will drive a steam turbine to produce electricity. Alternatively, a steam turbine can also be used to drive an air compressor, refrigeration compressor, or other rotating devices. Energy-Saving Tips in Heat Exchangers

etc.

360

Handbook of Energy Audit

5. All process heat exchangers need air venting, because air being an insulator, if not

parameter, deciding the size and performance of the heat exchanger.

Descriptive Questions

Short-Answer Questions

Energy Audit of Heat Exchangers, Waste-Heat Recovery, and Co-generation

361

Numerical Problem

2 p

p

of

Fill in the Blanks

Multiple-Choice Questions

Answers Numerical Problem 1. Fill in the Blanks 1. 2. 3. Multiple-Choice Questions 1. 2.

2

2

4. 5. 3000 6. 5 MW

17

Computer Software and Formats for Energy Audit



17.1

NAME OF SOFTWARE: ENERGY LENS

Website: http://www.energylens.com/ Size: 4.08 MB Features: Energy Lens is an energy-management software and is a tool for charting and analyzing energy consumption. Apart from Energy Lens, the group also offers BiZee Benchmark and Bizee Pro software for energy audits. It helps identify: When and where energy is wasted How much energy is wasted Progress made in reducing energy consumption Outputs compatible with Excel Free download available: For trial period only Cost (if any): 495 USD for each licence �

17.2

NAME OF SOFTWARE: TREAT (

Website: http://psdconsulting.com/software/treat/ Features: TREAT is an innovative solution for home-performance professionals looking for robust, yet nimble energy-modelling software. Some special features are the following:

Computer Software and Formats for Energy Audit

363

1. It creates models quickly and easily by building component libraries. 2. It calculates energy usage and predicts energy saving. 3. It automatically calculates payback and saving to investment ratio. 4. It generates physical reports. Free download available: Free trial available for 30 days Cost (if any): 495 USD for each licence �

17.3

NAME OF SOFTWARE: HEAT BY HANCOCK

Website: http://www.hancocksoftware.com Features: iHEAT is an energy-modelling and design software with the following features: 1. It trends activity over time and pinpoints program bottlenecks. 2. It can manage multiple programs. walkthroughs. 4. It establishes a budget, measures costs, and forecasts reimbursements. 5. It helps the user see behavioural and demographic trends. Free download available: Free trial available for 30 days Cost (if any): Price available on request �

17.4

NAME OF SOFTWARE: MATRIX 4 UTILITY ACCOUNTING SYSTEM

Website: http://www.abraxasenergy.com Features: Matrix 4 normalizes energy usage for weather and other variables like production, etc., and presents true energy saving. It has unique features like: Benchmarking Load-factor analysis Rate analysis Determining changes in energy usage pattern Setting saving targets and tracking progress Excel compatible Free download available: Free trial available for 30 days Cost (if any): Price available on request �

17.5

NAME OF SOFTWARE: EFFICIENCY TRACK, VIRTUAL ENERGY ASSESSMENT, AND AUTOMATED ENERGY AUDIT ARE THREE SOFTWARE AVAILABLE FROM RETROFICIENCY

Website: Features: The

software transforms building assessment and audit from a static

Virtual Energy Assessment prioritizes buildings by Automated Energy Audit software enables users develop comprehensive, accurate energy audits and generates reports. Cost: Free demo and cost available on request.

364

Handbook of Energy Audit



Website: http://www.pipeinsulation.org/ Features: 3E Plus is helpful in deciding economic thickness of insulation over pipes of different diameters. Some key features are the following: 1. Determines economic thickness of insulations based on return on investment for chosen fuel cost, installed cost, tax rates, maintenance, etc. 2. Calculates the amount of insulation needed for personnel protection for various design conditions. 3. Calculates the thickness of insulation needed for condensation control. 4. Calculates greenhouse-gas emissions and reductions. 5. Determines surface temperature and heat loss/gain calculations of individual insulation thicknesses up to 10 inches (250 mm). 6. Solves for outside insulated surface temperatures for all types of insulation applications at

pipe sizes from 1/2≤ to 48≤ (15–1200 mm). 9. Calculates heat loss/gain and outside insulated surface temperatures for any insulation material provided the thermal conductivity, associated mean temperatures, and temperature limit are entered by the user. Free download available: Freeware �

Website: Features: PUMP-FLO helps size and select pumps from more than 80 suppliers. It offers quotations, lead generation, pricing, and overall sales processes from worldwide leaders of pumps like Sulzur, Goulds, Gorman-Rupp, Patterson, Crane, etc. Free download available: Free trial available for 30 days Cost (if any): Available on request �

17.8 NAME OF SOFTWARE: ECO2.0 TO CALCULATE ENERGY SAVING DUE TO VARIABLE SPEED DRIVE INSTEAD OF CONVENTIONAL DRIVES

Website: http://www.schneider-electric.com/ software/7589-eco20/ Features: ECO2.0 estimates energy saving on HVAC pumps and fan-motor applications up to 2.4 MW. It suggests alternative variable-speed-drive solutions instead of standard mechanical solutions. Cost: Freeware

Computer Software and Formats for Energy Audit



365

17.9 NAME OF SOFTWARE: HONEYWELL VFD, ENERGY-SAVING AND PAYBACK CALCULATOR

Website: https://customer.honeywell.com/en-us/support/commercial/se/vfde/Pages/default.aspx Features: Honeywell calculates the energy saving and payback period based on application demand schedule and variable-frequency-drive horsepower. It is in an Excel worksheet form. Cost: Freeware �

17.10

NAME OF SOFTWARE:

MOST—MOTOR SELECTION TOOL

Website: http://oee.nrcan.gc.ca/industrial/equipment/software/ Features: With CanMOST, the following calculations are made: 1. Compute the energy demand and savings associated with the purchase of a new energy2. Predict expected energy and cost savings from replacing a failed or operable standard-

point and annual operating hours. Cost: Freeware/Registration is required to download the software. �

17.11

NAME OF SOFTWARE:

+

Website: https://www1.eere.energy.gov/manufacturing/tech_assistance/software_motormaster. html Features: MotorMaster+ is a software by NEMA (National Electrical Manufacturers Association) List of motors and motor suppliers Analysis of repair vs. replace cost Technical data to help optimize drive system Energy accounting, conservation, savings tracking, and greenhouse-gas-emission reduction reports Cost: Freeware The following section includes some data sheets for conducting energy audits of different systems or premises.

Handbook of Energy Audit

Boiler-plant assessment

1

1

1

1

1

1

1

1

1

1

0

3

2

3

2

Total points

1

Economizer control

1

Enrgy recovery

0

Repaired when required

2

Preventive maintenance

2

Makeup water meter

1

Fuel meter

2

Steam meters

2

2

Standard operating procedure

Maximum points

0

Automatic controls

1

General working condition

Many Leaks

2

Some Leaks

Points

Leakage of steam

No Leaks

Boiler number/ location

Average

Type of insulation

Good

Date

Flange Insulated

Sheet 17.1

Poor

366

Boiler 1 Boiler 2 Boiler 3 Total points Rating of boiler plant = (100*Total points)/(Number of boilers* Maximum score) Scorecard: Score

Action required

0-20

Immediate

20-40

Urgent

40-60

Corrective

60-80

Potential for energy saving

80 to 100

No action Sample boiler-plant assessment

1

1

1

1

1

1

1

1

1

1

0

3

2

3

2

Total points

1

Economizer control

1

Enrgy recovery

0

Repaired when required

Preventive maintenance

2

Makeup water meter

2

Fuel meter

1

Steam meters

2

Standard operating procedure

2

2

Automatic controls

Maximum points

0

General working condition

Many Leaks

1

Some Leaks

2

No Leaks

Points

Leakage of steam

Flange Insulated

Boiler number/ location

Average

Type of insulation

Good

Date 13/12/2013

Poor

Sheet 17.2

17

(Contd.)

Computer Software and Formats for Energy Audit

Date 13/12/2013 Boiler 1

Type of insulation

Leakage of steam

2

Boiler 2

2 1

Boiler 3

1 0

General working condition

1

1

1

1

1

3

2

14

1

1

1

1

1

3

2

12

2

2

0

Total points

28

Rating of boiler plant = (100*28)/(3*17) = 55

Action required : Potential for energy saving

Lighting-system assessment

1

1

0

1

0

1

1

1

Rating

0

Total points

2

Reflectors dirty

1

Reflectors clean

l

Luminaries dirty

2

Luminaries clean

1

Fluorescent lighting

Maximum points

Manual Switch

0

Motion sensor

Area/Points

Proper Illumination

Details of Illumination

Excessive Illumination

Date

Incandescent lighting

Sheet 17.3

367

0

100

%

Area 1

Area 2 Area 3 Total points and overall rating = Sample lighting-system assessment

Motion sensor

Manual Switch

Incandescent lighting

Fluorescent lighting

Luminaries clean

Luminaries dirty

Reflectors clean

Reflectors dirty

0

1

2

1

0

1

1

0

1

0

Maximum points

1

2

1

1

Shop floor

1

2

1

2

1

Area/Points

Office

0

Parking Total points and overall rating =

1

1

0

1 0

1

0

Rating

Proper Illumination

Details of Illumination

Excessive Illumination

Date 14/12/2013

Total points

Sheet 17.4

% 6

100

0

4

66.7

0

4

66.7

0

2

33.3

10

67

Handbook of Energy Audit

Sample cooling system

Maximum

0

1

Total points

1

1

Enthalpy control used

1 1

Outside air used

1 1

Energy recovery

1

Fix as required

0

Preventive measurement

Flange Insulated

1

3 3

2 2

1 1

12

Sample ducting and cool-air distribution system

Insulation condtion Poor

Flange Insulated

Stadard operation procedure

Control good

Control average

Control poor

Preventive measurement

Fix as required

Condition as required

Constant conditioning

Zone control good

Zone control average

Zone control poor

General working condition

Insulation condtion average

Type of insulation

Insulation condtion good

Date

location Points

2 2

2

1

0

2

1

2

1

0

1

0

1

0

2

1

0

2

2

1

2

1

1

2

Criteria for Evaluation

Insulation condition good

Insulation not breaked or missing, not wet or cracked

Insulation condition average

Small section breaked or missing, not wet or cracekd

Insulation condition poor

Section of insulation missing, broken, wet or crackex

Zone cotrol

Certain area of the building can be cotrolled

Cotrol good

Able to maintain rooom temperature near to thermostat setting

Total points

Sheet 17.6

Insulation condtion Poor

Location Points Maximum points

General working condition

Insulation condtion average

Type of insulation

Insulation condtion good

Date

Power meter installed

Sheet 17.5

Stadard Procedure followed

368

11

Plant or building name Good insulation condition Average insulation condition Poor insulation condition No leaks

Points

2

1

0

1

Maximum

2

1

0

1

1

1

1

Manage peak power demand Following standard procedure Preventive maintenance Fix as required Maintaining more than 0.9 pf

2 1 1

1 1 1 1 0 2

Maximum

2 1 1 1 1 1 1

Total points

Installation of peak power demand alarm

Points

2 10

0

1

2

1

2 Total points

Supply water temperature regulated as per requirement

Insulation

Supply water temp below 60 °C

Date

Fix as required

Sheet 17.8

Preventive maintenance

Coordination with power company

Date

Following standard procedure

Recording hourly usage pattern

Sheet 17.7

Faucet leaks

Recording ammeter

Computer Software and Formats for Energy Audit

369

Power-demand management sheet General working condition

Hot-water distribution sheet

General working condition

8

Sheet 17.10

1

January

February

March

April

May

June

July

August

September

October

November

December

Total consumption

Total area of building/ plant in m2 = Actual EPI (Energy perfomance index) BEE recomended EPI (Energy perfomance)

Total cost

Demand charges

0 1 1 1

1 1 1

Total points

Control preventive below off in case of centrifugal compressor

1

1

Air quality maintained as per requirements

1

1

Supply pleasure minimized

Preventive maintenance

1

1

Energy charges

Date

Fix as required

Following standard procedure

1

kVA

0

kW

Energy consumption and EPI

Run additional compressor on demand

1

PF

1

Maximum Compressor sized property

Points Some leaks

Plant or building name No leaks

Sheet 17.9

KWh

Month

370 Handbook of Energy Audit

Compressed-air assessment sheet General working conditions

8

Computer Software and Formats for Energy Audit

EPI Energy Performance Index =

Total energy consumption (kWh) Area of the building or plant (m 2 )

Sheet 17.11 Details of transformers and motors Location of Transformer

Transformer 1

Transformer 2

Transformers 3

Make Rated kVA High side voltage Low side voltage Frequency Type of cooling Year of installation Maintenance status

Motor at chilled water pump 1 Motor at chilled water pump 2 Motor at chilled water pump 3 Motor at condenser pump 1 Motor at condenser pump 2 Motor at condenser pump 3 Motor of cooling tower 1 Motor of cooling tower 2 Motor at AHU Other motor 1 Other motor 2 Remark

Power drawn kW

Current

Voltage

Location of motor

Power factor

Remark

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Handbook of Energy Audit

Efficiency (%)

Actual head (m)

Rated head (m)

Actual flow (CFM)

Location of pump

Rated flow (CFM)

Details of transformers and motors

Actual (kW)

Sheet 17.12

Rated (KW)

372

Chiller pump 1 Chiller pump 2 Chiller pump 3 Condenser pump 1 Condenser pump 2 Condenser pump 3 Cooling tower pump 1 Cooling tower pump 2 Other pump 1 Other pump 2 Sheet 17.13

Details lighting and lighting levels

1 2 3 4 5 6 7 8

Load (kW)

Month

Deficiency or excess lighting

Recomended lighting level (lux)

Average lighting level (lux)

Area (m2)

Total load (W)

Number of lamp

Type of luminaries

Type of lamp

Area

Floor

Name or type of building

Sr. No.

Annual lighting consumption

January February March April May June July August September October November December Total area of building = Total consumption =

I

Annexure Electricity Act MINISTRY OF LAW, JUSTICE AND COMPANY AFFAIRS (Legislative Department) New Delhi, the 1st October, 2001/Asvina 9, 1923 (Saka) The following Act of Parliament received the assent of the President on the 29th September, 2001, and is hereby published for general information:-THE ENERGY CONSERVATION ACT, 2001 No 52 of 2001 [29th September 2001] matters connected therewith or incidental thereto. Be it enacted by Parliament in the Fifty second Year of the Republic of India as follows:—

CHAPTER I Preliminary Short title, extent and commencement

1. (1) This Act may be called the Energy Conservation Act, 2001. (2) It extends to the whole of India except the state of Jammu and Kashmir (3) It shall come into force on such dates as the Central Government dates may be appointed for different provisions of this Act and any reference in any such provision to the commencement of this Act shall be construed as a reference to the coming into force of that provision. 2. In this Act, unless the context otherwise requires: —

(b) “ Appellate Tribunal” means Appellate Tribunal for Energy

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Handbook of Energy Audit

(c) “building” means any structure or erection or part of a structure or erection, after the rules relating to energy conservation building

(f) “designated agency” means any agency designated under clause (d)

(h) “energy” means any form of energy derived from fossil fuels, nuclear substances or materials, hydro-electricity and includes electrical energy or electricity generated from renewable sources of energy or

use of energy including submission of technical report containing

(j) “energy conservation building codes” means the norms and standards of energy consumption expressed in terms of per square meter of the

21 of 1860

(l) “Energy Management Centre” means the Energy Management Centre set up under the Resolution of the Government of India in the erstwhile Ministry of Energy, Department of Power No. 7(2)/87-EP

(n) “ Governing Council” means the Governing Council referred to in (o) “member” means the member of the Governing Council and includes

Annexure I : Electricity Act

14 of 1998

9 of 1940 54 of 1948 14 of 1998

375

(t) “State Commission” means the State Electricity Regulatory Commission established under sub-section (l) of section 17 of the Electricity Regulatory Commissions Act, in the Indian Electricity Act, 1910 or the Electricity (Supply) Act, 1948 or the Electricity Regulatory Commissions Act, 1998 shall have meanings respectively assigned to them in those Acts.

CHAPTER II Bureau of Energy Efficiency incorporation of Bureau of Energy

3. (1) With effect from such date as the Central Government may, by appoint, there shall be established, for the purposes (2) The Bureau shall be a body corporate by the name aforesaid having perpetual succession and a common seal, with power subject to the provisions of this Act, to acquire, hold and dispose of property, both movable and immovable, and to contract, and shall, by the said name, sue or be sued.

Management of Bureau

4. (1) The general superintendence, direction and management of the affairs of the Bureau shall vest in the Governing Council which shall consists of not less than twenty, but not exceeding twenty-six members to be appointed by the Central Government. (2) The Governing Council shall consist of the following members, namely:(a) the Minister in charge of the Ministry or Department of the Central Government dealing with the Power Chairperson (b) the Secretary to the Government of India, in charge of the Ministry or Department of the Central Government member dealing with the Power

376

Handbook of Energy Audit

54 of 1948 Karnataka Act 17 of 1960

(c) the Secretary to the Government of India, in charge of the Ministry or Department of the Central Government dealing with the Petroleum and Natural Gas (d) the Secretary to the Government of India, in charge of the Ministry or Department of the Central Government dealing with the Coal (e) the Secretary to the Government of India, in charge of the Ministry or Department of the Central Government dealing with the Non-conventional Energy Sources (f) the Secretary to the Government of India, in charge of the Ministry or Department of the Central Government dealing with the Atomic Energy (g) the Secretary to the Government of India, in charge of the Ministry or Department of the Central Government dealing with the Consumer Affairs (h) Chairman of the Central Electricity Authority established under the Electricity (Supply) Act, 1948 (i) Director-General of the Central Power Research Institute

member

member

member

member

member

member member

XXI of 1860

(j)

Executive Director of the Petroleum Conservation Research Association, a society registered under the member

1 of 1956

(

Chairman-cum-Managing Director of the Central Mine Planning and Design Institute Limited, a company member

63 of 1986

(l)

Director-General of the Bureau of Indian Standards established under the Bureau of Indian Standards Act, member

(m) Director-General of the National Test House, Department member 1 of 1956

(n) Managing Director of the Indian Renewable Energy Development Agency Limited, a company incorporated member (o)

members;

the States of the region to be appointed by the Central Government (p) such number of persons, not exceeding four as may be members prescribed, to be appointed by the Central Government as members from amongst persons who are in the opinion of the Central Government capable of representing industry, equipment and appliance manufacturers, architects and consumers

Annexure I : Electricity Act

377

(q) such number of persons, not exceeding two as may be members nominated by the Governing Council as members (r) Director-General of Bureau member – secretary; (3) The Governing Council may exercise all powers and do all acts and things which may be exercised or done by the Bureau. (4) Every member referred to in clause (o), (p) and (q) of sub-section (2)

up of vacancies and the procedure to be followed in the discharge of their functions shall be such as may be prescribed. Governing Council

Governing Council

not to invalidate Bureau, Governing Council or Committee

Removal of

shall observe such rules of procedure in regard to the transaction of business as its meetings (including quorum of such meetings) as may be provided by regulations. (2) The Chairperson or, if for any reason, he is unable to attend a meeting of the Governing Council, any other member chosen by the members present from amongst themselves at the meeting shall preside at the meeting. (3) All questions which come up before any meeting of the Governing Council shall be decided by a majority vote of the members present and voting, and in the event of an equality of votes, the Chairperson or his absence, the person presiding, shall have second or casting vote. Committee shall be invalid merely by reason of – (a) any vacancy in, or any defect in the constitution of, the Bureau or the (b) any defect in the appointment of a person acting as a Director-General or Secretary of the Bureau or a member of the Governing Council or (c) any irregularity in the procedure of the Bureau or the Governing Council or the Committee not affecting the merits of the case. 7. The Central Government shall remove a member referred to in clause (o),

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Handbook of Energy Audit

(c) has been convicted of an offence which, in the opinion of the Central (d) has, in the opinion of the Central Government, so abused his position interest: Provided that no member shall be removed under this clause unless he has been given a reasonable opportunity of being heard in the matter. 8. (1) Subject to any regulations made in this behalf, the Bureau shall, within six months from the date of commencement of this Act, constitute (2) Each Advisory Committee shall consist of a Chairperson and such other members as may be determined by regulations. Bureau may constitute, such number of technical committees of experts for the formulation of energy consumption standards or norms in respect of equipment or processes, as it considers necessary. Director-General of Bureau

General from amongst persons of ability and standing, having relating to energy production, supply and energy management

as Secretary of the Bureau

of sixty years, whichever is earlier (4) The salary and allowances payable to the Director-General and other terms and conditions of his service and other terms and conditions of service of the Secretary of the Bureau shall be such as may be prescribed affairs by the Governing Council, the Director-General of the Bureau shall be the Chief Executive Authority of the Bureau

Annexure I : Electricity Act

379

powers and duties of the Bureau as may be determined by regulations

Bureau

discharge of its functions under this Act. of the Bureau appointed under sub-section (1) shall be such as may be prescribed.

Authentication

Bureau

11. All orders and decisions of the Bureau shall be authenticated by the authorised by the Director-General in this behalf.

CHAPTER III Transfer of Assets, Liabilities etc, of Energy Management Centre to Bureau of Energy Management Centre

(a) any reference to the Energy Management Centre in any law other than this Act or in any contract or other instrument shall be (b) all properties and assets, movable and immovable of, or belonging to, the Energy Management Centre shall vest in the (c) all the rights and liabilities of the Energy Management Centre shall be transferred to, and be the right and liabilities of, the (d) without prejudice to the provisions of clause (c), all debts, obligations and liabilities incurred, all contracts entered into and all matters and things engaged to be done by, with or for the Energy Management Centre immediately before that date for or in connection with the purposes of the said Centre shall be deemed to have been incurred, entered into, or engaged to be (e) all sums of money due to the Energy Management Centre immediately before that date shall be deemed to be due to the

380

Handbook of Energy Audit

(f) all suits and other legal proceedings instituted or which could have been instituted by or against the Energy Management Centre immediately before that date may be continued or may be

Management Centre immediately before that date shall hold terms and conditions of service as respects remuneration, leave,

14 of 1947

shall continue to do so as an employee of the Bureau or until the expiry of six months from the date if such employee opts not to be the employee of the Bureau within such period. (2) Not withstanding anything contained in the Industrial Disputes Act, 1947 or in any other law for the time being in force, the absorption of any employees by the Bureau in its regular service under this section shall not entitle such employees to any compensation under that Act or other law and no such claim shall be entertained by any court, tribunal or other authority.

CHAPTER IV Powers and Functions of Bureau 13. (1) The Bureau shall, effectively co-ordinate with designated consumers, designated agencies and other agencies, recognise and utilise the existing resources and infrastructure, in performing the functions assigned to it by or under this Act (2) The Bureau may perform such functions and exercise such powers as may be assigned to it by or under this Act and in particular, such functions and powers include the function and power to (a) recommend to the Central Government the norms for processes

(b) recommend to the Central Government the particulars required tobe displayed on label on equipment or on appliances and (c) recommend to the Central Government for notifying any user or class of users of energy as a designated consumer under clause

Annexure I : Electricity Act

381

(j) formulate and facilitate implementation of pilot projects and

(n) levy fee, as may be determined by regulations, for services

(q) specify, by regulations, the manner and intervals of time in which

conservation for educational institutions, boards, universities or autonomous bodies and coordinate with them for inclusion of (t) implement international co-operation programmes relating to

(u) perform such other functions as may be prescribed.

382

Handbook of Energy Audit

CHAPTER V Power of Central Government to Facilitate and Enforce Efficient use of Energy and its Conservation Power of Central Government to

Bureau, — (a) specify the norms for processes and energy consumption standards for any equipment, appliances which consumes, generates, transmits (b) specify equipment or appliance or class of equipments or appliances, (c) prohibit manufacture or sale or purchase or import of equipment

purchase or import or equipment or appliance shall be issued within

(d) direct display of such particulars on label on equipment or on

(e) specify, having regarding to the intensity or quantity of energy consumed and the amount of investment required for switching over

required by the industry, any user or class of users of energy as a

(g) establish and prescribe such energy consumption norms and standards for designated consumers as it may consider necessary: Provided that the Central Government may prescribe different norms and standards for different designated consumers having (h) direct, having regard to quantity of energy consumed or the norms

Annexure I : Electricity Act

383

audit conducted by an accredited energy auditor in such manner and

conservation, any designated consumer to get energy audit conducted (j) specify the matters to be included for the purposes of inspection

such form and manner and within such period, as may be prescribed,

(l) direct any designated consumer to designate or appoint energy manger and submit a report, in the form and manner as may be prescribed,

(n) direct every designated consumer to comply with energy consumption

consumption norms and standards prescribed under clause (g), to

(q) amend the energy conservation building codes to suit the regional (r) direct every owner or occupier of the building or building complex, being a designated consumer to comply with the provisions of

(s) direct, any designated consumer referred to in clause (r), if considered building to get energy audit conducted in respect of such building by an accredited energy auditor in such manner and intervals of time as

384

Handbook of Energy Audit

(u) arrange and organise training of personnel and specialists in the

Provided that the powers under clauses (p) and (s) shall be exercised in consultation with the concerned State.

CHAPTER VI Power of State Government to Facilitate and Enforce Efficient use of Energy and its Conservation Power of State Government to enforce certain

Bureau – (a) amend the energy conservation building codes to suit the regional and local climatic conditions and may, by rules made by it, specify and notify energy conservation building codes with respect to use of (b) direct every owner or occupier of a building or building complex being a designated consumer to comply with the provisions of the

conservation, any designated consumer referred to in clause (b) to get energy audit conducted by an accredited energy auditor in

(d) designate any agency as designated agency to coordinate, regulate

(f) arrange and organise training of personnel and specialists in the

(h) direct, any designated consumer to furnish to the designated agency,

Annexure I : Electricity Act

385

by rules made by it, information with regard to the energy consumed (i) specify the matters to be included for the purposes of inspection

of Fund by State Government

use of energy and its conservation within the State. (2) To the Fund shall be credited all grants and loans that may be made by the State Government or, Central Government or any other (3) The Fund shall be applied for meeting the expenses incurred for implementing the provisions of this Act. (4) The Fund created under sub-section (l) shall be administered by such the rules made by the State Government.

Power of

from the date of commencement of this Act, as many inspecting

section 14 or ensure display of particulars on label on equipment or of performing such other functions as may be assigned to them. have power to (a) inspect any operation carried on or in connection with the 14 or in respect of which energy standards under clause (a) of (b) enter any place of designated consumer at which the energy is used for any activity and may require any proprietor, employee, director, manager or secretary or any other person who may be attending in any manner to or helping in, carrying on any activity with the help of energy (i) to afford him necessary facility to inspect – (A) any equipment or appliance as he may require and (B) any production process to ascertain the energy

386

Handbook of Energy Audit

(iii) to record the statement of any person which may be useful for, under this Act.

open for production or conduct of business connected therewith. remove or cause to be removed from the place wherein he has entered, Power of Central Government or State Government

18. The Central Government or the State Government may, in the exercise of use of energy and its conservation, issue such directions in writing as it

designated consumer shall be bound to comply with such directions. Explanation – For the avoidance of doubts, it is hereby declared that the power to issue directions under this section includes the power to direct – (a) regulation of norms for process and energy consumption (b) regulation of the energy consumption standards for equipment and appliances.

CHAPTER VII Finance, Account s and Audit of Bureau 19. The Central Government may, after due appropriation made by Parliament Government

Fund by Central Government

grants and loans of such sums or money as the Central Government may consider necessary. 20. (1) There shall be constituted a Fund to be called as the Central Energy Conservation Fund and there shall be credited thereto – (a) any grants and loans made to the Bureau by the Central

(c) all sums received by the Bureau from such other sources as may be decided upon by the Central Government.

Annexure I : Electricity Act

387

(2) The Fund shall be applied for meeting – (a) the salary, allowances and other remuneration of Director(b) expenses of the Bureau in the discharge of its functions under (c) fee and allowances to be paid to the members of the Governing

of Bureau

(d) expenses on objects and for purposes authorised by this Act 21. (1) The Bureau may, with the consent of the Central Government or in accordance with the terms of any general or special authority given to it by the Central Government borrow money from any source as it

with respect to the loans borrowed by the Bureau under sub-section (l). Budget

the estimated receipts and expenditure of the Bureau and forward the same to the Central Government. Annual report

year as may be prescribed, its annual report, giving full account of its

Annual report tobe laid before Parliament

the Central Government. 24. The Central Government shall cause the annual report referred to in section 23 to be laid, as soon as may be after it is received, before each House of Parliament. and prepare an annual statement of accounts in such form as may be prescribed by the Central Government in consultation with the Comptroller and Auditor-General of India. (2) The accounts of the Bureau shall be audited by the Comptroller and and any expenditure incurred in connection with such audit shall be payable by the Bureau to the Comptroller and Auditor-General. (3) The Comptroller and Auditor-General of India and any other person appointed by him in connection with the audit of the accounts of the Bureau shall have the same rights and privileges and authority in connection with such audit as the Comptroller and Auditor-General generally has in connection with the audit of the Government accounts

388

Handbook of Energy Audit

and in particular, shall have the right to demand the production of

Auditor-General of India or any other person appointed by him in this behalf together with the audit report thereon shall forward annually to the Central Government and that Government shall cause the same to be laid before each House of Parliament.

CHAPTER VIII Penalties and Adjudication Penalty

clause (n) or clause (r) or clause (s) of section 14 or clause (b) or which shall not exceed ten thousand rupees for each such failures and, in the case of continuing failures, with an additional penalty which may extend to one thousand rupees for every day during which such failures continues:

Power to adjudicate

years from the date of commencement of this Act. (2) Any amount payable under this section, if not paid, may be recovered as if it were an arrear of land revenue.

holding an inquiry in such manner as may be prescribed by the Central Government, after giving any person concerned a reasonable opportunity of being heard for the purpose of imposing any penalty. summon and enforce the attendance of any person acquainted with the facts and circumstances of the case of give evidence or produce be useful for or relevant to the subject-matter of the inquiry, and if,

with the provisions of any of those clauses of that section:

Annexure I : Electricity Act

389

Provided that where a State Commission has not been established

State Commission on its establishment in that State:

all matters being adjudicated by him and thereafter the adjudicating penalties on such matters. into account by

namely:– (a) the amount of disproportionate gain or unfair advantage, wherever

Civil court not to

(b) the repetitive nature of the default. 29. No civil court shall have jurisdiction to entertain any suit or proceeding in respect of any this Act or the Appellate Tribunal is empowered by or under this Act to determine and no injunction shall be granted by any court or other power conferred by or under this Act.

CHAPTER IX Appellate Tribunal for Energy Conservation Appellate Tribunal

Government or the State Government or any other authority under this Act. Appeal to Appellate Tribunal

or the Central Government or the State Government or any other authority under this Act, may prefer an appeal to the Appellate Tribunal for Energy Conservation:

390

Handbook of Energy Audit

Provided that any person appealing against the order of the deposit the amount of such penalty: Provided further that where in any particular case, the Appellate Tribunal is of the opinion that the deposit of such penalty would cause undue hardship to such person, the Appellate Tribunal may dispense with such deposit subject to such conditions as it may deem

Government or any other authority is received by the aggrieved accompanies by such fee as may be prescribed Provided that the Appellate Tribunal may entertain an appeal after

may, after giving the parties to the appeal an opportunity of being or setting aside the order appealed against (4) The Appellate Tribunal shall send a copy of every order made by it or the Central Government or the State Government or any other authority. shall be dealt with by it as expeditiously as possible and endeavour and eighty days from the date of receipt of the appeal: Provided that where an appeal could not be disposed of within the said period of one hundred and eighty days, the Appellate Tribunal shall record its reasons in writing for not disposing of the appeal within the said period. propriety or correctness of any order made by the adjudicating other authority under this Act, as the case may be in relation to any proceeding, on its own motion or otherwise, call for the records of

Annexure I : Electricity Act

Appellate Tribunal

391

32. (1) The Appellate Tribunal shall consist of a Chairperson and such number of Members not exceeding four, as the Central Government (2) Subject to the provisions of this Act, (a) the jurisdiction of the Appellate Tribunal maybe exercised by (b) a Bench may be constituted by the Chairperson of the Appellate Tribunal with two or more Members of the Appellate Tribunal as Provided that every Bench constituted under this clause shall (c) The Benches of the Appellate Tribunal shall ordinarily sit at Delhi and such other places as the Central Government may, in consultation with the Chairperson of the Appellate Tribunal, (d) The Central Government shall notify the areas in relation to which each Bench of the Appellate Tribunal may exercise jurisdiction, (3) Notwithstanding anything contained in sub-section (2), the Chairperson of the Appellate Tribunal may transfer a Member of the Appellate Tribunal from one Bench to another Bench Explanation – For the purposes of this Chapter, – (i) “Judicial Member” means a Member of the Appellate Tribunal appointed as such under item (i) or item (ii) or clause (b) of subsection (1) of section 33, and includes the Chairperson of the (ii) “Technical Member” means a Member of the Appellate Tribunal appointed as such under item (iii) or item (iv) or item (v) or item (vi) of clause (b) of sub-section (l) of section 33

for appointment

Appellate Tribunal

the Appellate Tribunal or a Member of the Appellate Tribunal unless he (a) in the case of Chairperson of the Appellate Tribunal, is or has been, a judge of the Supreme Court or the Chief Justice of a High (b) in the case of a Member of the Appellate Tribunal,– or (ii) is, or has been, a Member of the Indian Legal Service and has held a post in Grade I in that service for atleast three

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Handbook of Energy Audit

(iii) is, or has been, a Secretary for at least one year in Ministry or Department or the Central Government dealing with the Power, or Coal, or Petroleum and Natural Gas, or Atomic (iv) is, or has been Chairman of the Central Electricity Authority (v) is, or has been, Director-General of Bureau or DirectorGeneral of the Central Power Research Institute or Bureau of Indian Standards for atleast three years or has held any

dealing with the matters relating to energy production and use of energy and its conservation, and has shown capacity commerce, economics, law or management 34. The Chairperson of the Appellate Tribunal and every Member of the

Provided that no Chairperson of the Appellate Tribunal or Member of (a) in the case of the Chairperson of the Appellate Tribunal, the age of (b) in the case of any Member of the Appellate Tribunal, the age of sixty-

of service of the Chairperson of the Appellate Tribunal, Members of the Appellate Tribunal shall be such as may be prescribed: Provided that neither the salary and allowances nor the other terms and conditions of service of the Chairperson of the Appellate Tribunal or a Member of the Appellate Tribunal shall be varied to his disadvantage after appointment.

Appellate Tribunal, the Central Government shall appoint another person proceedings may be continued before the Appellate Tribunal from the

Annexure I : Electricity Act

removal

393

37. (1) The Chairperson or a Member of the Appellate Tribunal may, by notice in writing under his hand addressed to the Central Government, Provided that the Chairperson of the Appellate Tribunal or a Member of the Appellate Tribunal shall, unless he is permitted by

of such notice or until a person duly appointed as his successor enters earliest. (2) The Chairperson of the Appellate Tribunal or a Member of the by an order by the Central Government on the ground of proved misbehaviour or incapacity after an inquiry made by such persons as the President may appoint for this purpose in which the Chairperson or a Member of the Appellate Tribunal concerned has been informed of the charges against him and given a reasonable opportunity of being heard in respect of such charges. Member to act in certain

Staff of Appellate Tribunal

Chairperson of the Appellate Tribunal by reason of his death, resignation or otherwise, the senior-most member of the Appellate Tribunal shall act as the Chairperson of the Appellate Tribunal until the date on which a new Chairperson appointed in accordance with

his functions owing to his absence, illness or any other cause, the senior most Member of the Appellate Tribunal shall discharge the functions of the Chairperson of the Appellate Tribunal until the date on which the Chairperson of the Appellate Tribunal resumes his duties. 39. (1) The Central Government shall provide the Appellate Tribunal with

their functions under the general superintendence of the Chairperson of the Appellate Tribunal as the case may be. (3) The salaries and allowances and other conditions of service of the may be prescribed.

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5 of 1908 Procedure Appellate Tribunal

5 of 1908

1 of 1972

40. (1) The Appellate Tribunal shall not be bound by the procedure laid down by the Code of civil Procedure, 1908 but shall be guided by the principles of natural justice and subject to the other provisions of this Act, the Appellate Tribunal shall have powers to regulate it own procedure. (2) The Appellate Tribunal shall have, for the purposes of discharging its functions under this Act, the same powers as are vested in the civil court under the Code of Civil Procedure 1908, while trying to suit in respect of the following matters, namely:(a) summoning and enforcing the attendance of any person and

(d) subject to the provisions of section 123 and 124 of the Indian Evidence Act, 1872, requisitioning any public record or (e) issuing commissions for the examination of witnesses or

(h) setting aside any order of dismissal or any representation for (i) any other matter which may be prescribed by the Central Government. (3) An order made by the Appellate Tribunal under this Act shall be executable by the Appellate Tribunal as a decree of civil court and, for this purpose, the Appellate Tribunal shall have all the powers of a civil court. (4) Not withstanding anything contained in sub-section (3), the Appellate Tribunal may transmit any order made by it to a civil court having local jurisdiction and such civil court shall execute the order as if it were a decree made by the that court. 45 of 1860

2 of 1974

judicial proceedings within the meaning of sections 193 and 228 of the Indian Penal Code and the Appellate Tribunal shall be deemed to Criminal Procedure, 1973.

Annexure I : Electricity Act

395

the distribution of the business of the Appellate Tribunal amongst the Benches and also provide for the matters which may be dealt with by each Bench. Power of

after hearing such of them as he may desire to be heard, or on his own motion without such notice, the Chairperson of the Appellate Tribunal may transfer any case pending before one Bench for disposal, to any other Bench. majority

43. If the Members of the Appellate Tribunal of a Bench consisting of two Members differ in opinion on any point, they shall state the point or the Appellate Tribunal who shall either hear the point or points himself or refer the case for hearing on such point or points by one or more of the other Members of the Appellate Tribunal and such point or points shall be decided according to the opinion of the majority of the Members of heard it.

Right to appellant of legal practitioner or accredited auditor and of Government to

44. (1) A person preferring an appeal to the Appellate Tribunal under this Act may either or an accredited energy auditor of his choice to present his case before the Appellate Tribunal, as the case may be. (2) The Central Government or the State Government may authorise one or more legal respect to any appeal before the Appellate Tribunal as the case may be.

Appeal to Supreme Court

of communication of the decision or order of the Appellate Tribunal to 5 of 1908

Code of Civil Procedure, 1908:

sixty days.

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Handbook of Energy Audit

CHAPTER X Miscellaneous Power of Central Government to Bureau

Power of Central Government to

shall, in exercise of its powers or the performance of its functions under this Act, be bound by such directions on questions of policy as the Central Government may give in writing to it from time to time: Provided that the Bureau shall, as far as practicable, be given an opportunity to express his views before any direction is given under this sub-section. (2) The decision of the Central Government, whether a question is one of 47. (1) If at any time the Central Government is of opinion – (a) that on account of grave emergency, the Bureau is unable to discharge the functions and duties imposed on it by or under the (b) that the Bureau has persistently made default in complying with any direction issued by the Central Government under this Act or in discharge of the functions and duties imposed on it by or under the provisions of this Act and as a result of such default,

(c) that circumstances exist which render it necessary in the public supersede the Bureau for such period, not exceeding six months,

superseding the Bureau (a) all the members referred to in clauses (o), (p) and (q) of subsection (2) of section 4 shall, as from the date of supersession, (b) all the powers, functions and duties which may, by or under the provisions of this Act, be exercised or discharged by or on behalf of the Bureau, shall until the Bureau is reconstituted under sub-section (3), be exercised and discharged by such person or (c) all property owned or controlled by the Bureau shall, until the Bureau is reconstituted under sub-section (3), vest in the Central Government.

Annexure I : Electricity Act

397

may reconstitute the Bureau by a fresh appointment and in such case

Provided that the Central Government may, at any time, before sub-section

section and the circumstances leading to such action to be laid before each House of Parliament at the earliest. Default by

clause (l) or clause (n) or clause (r) or clause (s) of section 14 or clause time of such contravention was incharge of, and was responsible to the company for the conduct of the business of the company, as well as the company, shall be deemed to have acted in contravention of the said provisions and shall be liable to be proceeded against and Provided that nothing contained in this sub-section shall render any such person liable for penalty provided in this Act if he proves that the contravention of the aforesaid provisions was committed without contravention of the aforesaid provision. (2) Notwithstanding anything contained in sub-section (l), where any contravention of the provisions of clause (c) or clause (d) or clause or clause (s) of section 14 or clause (b) or clause (c) or clause (h) of in attributable to, any neglect on the part of , any director, manager,

the said provisions and shall be liable to be proceeded for imposition of penalty accordingly. Explanation – For the purposes of this section, “company” means a

398

Handbook of Energy Audit

43 of 1961

other enactment for the time being in force relating to tax on income, Exemption from tax on income

(b) the existing Energy Management Centre from the date of its constitution to the date of establishment of the Bureau, shall not be liable to pay any income tax or any tax in respect of their income, Protection of action taken in good faith

Government or Director-General or Secretary or State Government or

which is in good faith done or intended to be done under this Act or the rules or regulations made thereunder. Delegation

member, member of such of its powers and functions under this Act (except the powers under Power to obtain information

information, and with such samples of any material or substance used in relation to any equipment or appliance, as the Bureau may require. Power to exempt

that it is necessary orexpedient so to do in the public interest, it may,

consumers from application of all or any of the provisions of this Act: Provided that the Central Government or the State Government, as the case may be, shall not grant exemption to any designated consumer or Provided further that the Central Government or State Government, granting such exemption.

Appellate Tribunal,

General, Secretary,

Appellate Tribunal or the members of the State Commission or the members, Director-General, when acting or purporting to act in pursuance of any of the provisions of the Act, to be public servants within the meaning of section 21 of the 45 of 1860 Indian Penal Code.

Annexure I : Electricity Act

Power of Central Government to Power of Central Government to

399

the Bureau as to carrying out into execution of this Act in the State out the provisions of this Act. (2) In particular, and without prejudice to the generality of the foregoing power, such rules may provide for all or any of the following matters, namely:-(a) such number of persons to be appointed as members by the Central Government under clauses (o), (p) and (q) of sub-section (b) the fee and allowances to be paid to the members under sub(c) the salary and allowances payable to the Director-General and other terms and conditions of his service and other terms and conditions of service of the Secretary of the Bureau under sub-

(e) performing such other functions by the Bureau, as may be (f) the energy consumption norms and standards for designated (g) prescribing the different norms and standards for different designated consumers under the proviso to clause (g) of section (h) the form and manner and the time within which information recommendations of the accredited energy auditor be furnished (i) the form and manner in which the status of energy consumption

(l) the energy conservation building codes under clause (p) of (m) the matters relating to inspection under sub-section (2) of section

400

Handbook of Energy Audit

(n) the form in which, and the time at which, the Bureau shall prepare (o) the form in which, and the time at which, the Bureau shall prepare (p) the form in which the accounts of the Bureau shall be maintained (q) the manner of holding inquiry under sub-section (l) of section

(s) the salary and allowances payable to and other terms and conditions of service of the Chairperson of the Appellate Tribunal (t) the salary and allowances and other conditions of service of the

(u) the additional matters in respect of which the Appellate Tribunal may exercise the powers of a civil court under clause (i) of sub(v) any other matters which is to be, or may be, prescribed, or in respect of which provision is to be made, or may be made by rules. Power of State Government to

out the provisions of this Act and not inconsistent with the rules, if any, made by the Central Government. (2) In particular, and without prejudice to the generality of the foregoing power, such rules may provide for all or any of the following matters, namely: (a) energy conservation building codes under clause (a) of section (b) the form, the manner and the period within which information with regard to energy consumption shall be furnished under (c) the person or any authority who shall administer the Fund and the manner in which the Fund shall be administered under sub(d) the matters to be included for the purposes of inspection under sub-section (2) of section 17

Annexure I : Electricity Act

401

(e) any other matter which is to be, or may be, prescribed, or in respect of which provision is to be made, or may be made, by rules. Power of Bureau to

Government and subject to the condition of previous publication, by this Act and the rules made thereunder to carry out the purposes of this Act. (2) In particular, and without prejudice to the generality of the foregoing power, such regulations may provide for all or any of the following matters, namely:-(a) the times and places of the meetings of the Governing Council and the procedure to be followed at such meetings (b) the members of advisory committees constituted under sub(c) the powers and duties that maybe exercised and discharged by

of energy and its conservation under clause (n) of sub-section (2) (e) the list of accredited energy auditors under clause (o) of sub-

(g) the manner and the intervals or time in which the energy audit shall be conducted under clause (q) of sub-section (2) of section

(i) particulars required to be displayed on label and the manner of (j) the manner and the intervals of time for conduct of energy audit

402

Handbook of Energy Audit

be laid before Parliament and

9. (1) Every rule made by the Central Government and every regulation made under this Act shall be laid, as soon as may be after it is made, before each House of Parliament while it is in session, for a total period of thirty days which may be comprised in one session or in two or more successive session, and if, before the expiry of the session immediately following the session or the successive sessions or regulation, or both Houses agree that the rule or regulation should not be made, the rule or regulation shall thereafter have effect only in

the validity of anything previously done under that rule or regulation. (2) Every rule made by the State Government shall be laid, as soon as may be after it is made, before each House of the State Legislature where it consists of two Houses, or where such Legislature consists of one House, before that House. Application of other

the provisions of any other law for the time being in force. not to apply in

of the Central Government dealing with Defence, Atomic Energy or institutions under the control of such Ministries or Departments as may

Power to remove

Provided that no such order shall be made under this section after the expiry of two years from the date of commencement of this Act. (2) Every order made under this section shall be laid, as soon as may be after it is made, before each House of Parliament.

Annexure I : Electricity Act

403

THE SCHEDULE [See section 2 (s)]

List of Energy Intensive Industries and other establishments specified as designated consumers

14. Thermal Power Stations, hydel power stations, electricity transmission companies and

SUBHASH C.JAIN, Secy. to the Govt. of India.

II

Annexure Properties of Steam Properties of Saturated Water and Steam (Temperature) Temp. t (°C)

Pressure MPa

Volume, m3/kg VL

Enthalpy, kJ/kg

VV

hL

hV

Entropy, kJ/(kg · K) SL

SV

Temp. t (°C)

0.01

0.0006117

0.0010002

20600

0.001

2500.9

0.0000

9.1555

0.01

5

0.0008726

0.0010001

14702

21.019

2510.1

0.0763

9.0249

5

10

0.001228

0.0010003

106.31

42.021

2519.2

0.1511

8.8998

10

15

0.001706

0.0010009

77.881

62.984

2528.4

0.2245

8.7804

15

20

0.002339

0.0010018

57.761

83.920

2537.5

0.2965

8.6661

20

25

0.003170

0.0010030

43.341

104.84

2546.5

0.3673

8.5568

25

30

0.004247

0.0010044

32.882

125.75

2555.6

0.4368

8.4521

30

35

0.005629

0.0010060

25.208

146.64

2564.6

0.5052

8.3518

35

40

0.007384

0.0010079

19.517

167.54

2573.5

0.5724

8.2557

40

45

0.009594

0.0010099

15.253

188.44

2582.5

0.6386

8.1634

45

50

0.012351

0.0010121

1.2028

209.34

2591.3

0.7038

8.0749

50

55

0.015761

0.0010145

9.5649

230.24

2600.1

0.7680

7.9899

55

60

0.019946

0.0010171

7.6677

251.15

2608.8

0.8312

7.9082

60

65

0.025041

0.0010199

6.1938

272.08

2617.5

0.8935

7.8296

65

70

0.031201

0.0010228

5.0397

293.02

2626.1

0.9550

7.7540

70

75

0.038595

0.0010258

4.1291

313.97

2634.6

1.0156

7.6812

75

80

0.047415

0.0010290

3.4053

334.95

2643.0

1.0754

7.6110

80

85

0.057867

0.0010324

2.8259

355.95

2651.3

1.1344

7.5434

85

90

0.070182

0.0010359

2.3591

376.97

2659.5

1.1927

7.4781

90

95

0.084609

0.0010396

1.9806

398.02

2667.6

1.2502

7.4150

95

(Contd.)

Annexure II : Properties of Steam

Temp. t (°C)

Pressure MPa

Volume, m3/kg VL

VV

Enthalpy, kJ/kg hL

hV

Entropy, kJ/(kg · K) SL

SV

405

Temp. t (°C)

100

0.10142

0.0010435

1.6719

419.10

2675.6

1.3070

7.3541

100

105

0.12090

0.0010474

1.4185

440.21

2683.4

1.3632

7.2951

105

110

0.14338

0.0010516

1.2094

461.36

2691.1

1.4187

7.2380

110

115

0.16918

0.0010559

1.0359

482.55

2698.6

1.4735

7.1827

115

120

0.19867

0.0010603

0.89130

503.78

2705.9

1.5278

7.1291

120

125

0.23222

0.0010649

0.77011

525.06

2713.1

1.5815

7.0770

125

130

0.27026

0.0010697

0.66808

546.39

2720.1

1.6346

7.0264

130

135

0.31320

0.0010747

0.58180

567.77

2726.9

1.6872

6.9772

135

140

0.36150

0.0010798

0.50852

589.20

2733.4

1.7393

6.9293

140

145

0.41563

0.0010850

0.44602

610.69

2739.8

1.7909

6.8826

145

150

0.47610

0.0010905

0.39250

632.25

2745.9

1.8420

6.8370

150

155

0.54342

0.0010962

0.34650

653.88

2751.8

1.8926

6.7926

155

160

0.61814

0.0011020

0.30682

675.57

2757.4

1.9428

6.7491

160

165

0.70082

0.0011080

0.27246

697.35

2762.8

1.9926

6.7066

165

170

0.79205

0.0011143

0.24262

719.21

2767.9

2.0419

6.6649

170

175

0.89245

0.0011207

0.21660

741.15

2772.7

2.0909

6.6241

175

180

1.0026

0.0011274

0.19386

763.19

2777.2

2.1395

6.5841

180

185

1.1233

0.0011343

0.17392

785.32

2781.4

2.1878

6.5447

185

190

1.2550

0.0011414

0.15638

807.57

2785.3

2.2358

6.5060

190

195

1.3986

0.0011488

0.14091

829.92

2788.9

2.2834

6.4679

195

200

1.5547

0.0011565

0.12722

852.39

2792.1

2.3308

6.4303

200

205

1.7240

0.0011645

0.11509

874.99

2794.9

2.3779

6.3932

205

210

1.9074

0.0011727

0.10430

897.73

2797.4

2.4248

6.3565

210

215

2.1055

0.0011813

0.094689

920.61

2799.4

2.4714

6.3202

215

220

2.3193

0.0011902

0.086101

943.64

2801.1

2.5178

6.2842

220

225

2.5494

0.001199

0.078411

966.84

2802.3

2.5641

6.2485

225

230

2.7968

0.001209

0.071510

990.21

2803.0

2.6102

6.2131

230

235

3.0622

0.001219

0.065304

1013.8

2803.3

2.6561

6.1777

235

240

3.3467

0.001229

0.059710

1037.5

2803.1

2.7019

6.1425

240

(Contd.)

406

Handbook of Energy Audit

Temp. t (°C)

Pressure MPa

Volume, m3/kg VL

VV

Enthalpy, kJ/kg hL

hV

Entropy, kJ/(kg · K) SL

SV

Temp. t (°C)

245

3.6509

0.001240

0.054658

1061.5

2802.3

2.7477

6.1074

245

250

3.9759

0.001252

0.050087

1085.7

2801.0

2.7934

6.0722

250

255

4.3227

0.001264

0.045941

1110.1

2799.1

2.8391

6.0370

255

260

4.6921

0.001276

0.042175

1134.8

2796.6

2.8847

6.0017

260

265

5.0851

0.001289

0.038748

1159.8

2793.5

2.9304

5.9662

265

270

5.5028

0.001303

0.035622

1185.1

2789.7

2.9762

5.9304

270

275

5.9463

0.001318

0.032767

1210.7

2785.1

3.0221

5.8943

275

280

6.4165

0.001333

0.030154

1236.7

2779.8

3.0681

5.8578

280

285

6.9145

0.001349

0.027758

1263.0

2773.7

3.1143

5.8208

285

290

7.4416

0.001366

0.025557

1289.8

2766.6

3.1608

5.7832

290

295

7.5990

0.001385

0.023531

1317.0

2758.6

3.2076

5.7449

295

300

8.5877

0.001404

0.021663

1344.8

2749.6

3.2547

5.7058

300

305

9.2092

0.001425

0.019937

1373.1

2739.4

3.3024

5.6656

305

310

9.8647

0.001448

0.018339

1402.0

2727.9

3.3506

5.6243

310

315

10.556

0.001472

0.016856

1431.6

2715.1

3.3994

5.5816

315

320

11.284

0.001499

0.015476

1462.1

2700.7

3.4491

5.5373

320

325

12.051

0.001528

0.014189

1493.4

2684.5

3.4997

5.4911

325

330

12.858

0.001561

0.012984

1525.7

2666.2

3.5516

5.4425

330

335

13.707

0.001597

0.011852

1559.3

2645.6

3.6048

5.3910

335

340

14.600

0001638

0.010784

1594.4

2622.1

3.6599

5.3359

340

345

15.540

0.001685

0.009770

1631.4

2595.0

3.7175

5.2763

345

350

16.529

0.001740

0.008801

1670.9

2563.6

3.7783

5.2109

350

355

17.570

0.001808

0.007866

1713.7

2526.4

3.8438

5.1377

355

360

18.666

0.001895

0.006945

17615

2481.0

3.9164

5.0527

360

365

19.822

0.002016

0.006004

1817.6

2422.0

4.0011

4.9482

365

370

21.043

0.002222

0.004946

1892.6

2333.5

4.1142

4.7996

370

TC

22.064

0.003106

0.003106

2087.5

2087.5

4.4120

4.4120

TC

TC = 373.946 °C

Annexure II : Properties of Steam

407

Properties of Saturated Water and Steam (Pressure) Press. MPa

Temp. t (°C)

0.001

Volume, m3/kg

Enthalpy, kJ/kg

Entropy, kJ/(kg · K)

Press. MPa

VL

VV

hL

hV

SL

SV

6.97

0.0010001

129.18

29.298

2513.7

0.1059

8.9749

0.001

0.002

17.50

0.0010014

66.990

73.435

2532.9

0.2606

8.7227

0.002

0.003

24.08

0.0010028

45.655

100.99

2544.9

0.3543

8.5766

0.003

0.004

28.96

0.0010041

34.792

121.40

2553.7

0.4224

8.4735

0.004

0.005

32.88

0.0010053

28.186

137.77

2560.8

0.4763

8.3939

0.005

0.006

36.16

0.0010064

23.734

151.49

2566.7

0.5209

8.3291

0.006

0.007

39.00

0.0010075

20.525

163.37

2571.8

0.5591

8.2746

0.007

0.008

41.51

0.0010085

18.099

173.85

2576.2

0.5925

8.2274

0.008

0.009

43.76

0.0010094

16.200

183.26

2580.3

0.6223

8.1859

0.009

0.010

45.81

0.0010103

14.671

191.81

2583.9

0.6492

8.1489

0.010

0.012

49.42

0.0010119

12.359

206.91

2590.3

0.6963

8.0850

0.012

0.014

52.55

0.0010133

10.691

219.99

2595.8

0.7366

8.0312

0.014

0.016

55.31

0.0010147

9.4309

231.55

2600.7

0.7720

7.9847

0.016

0.018

57.80

0.0010160

8.4433

241.95

2606.0

0.8035

7.9437

0.018

0.020

60.06

0.0010171

7.6482

251.40

2608.9

0.8320

7.9072

0.020

0.025

64.96

0.0010198

6.2034

271.93

2617.4

0.8931

7.8302

0.025

0.030

69.10

0.0010222

5.2286

289.23

2624.6

0.9439

7.7675

0.030

0.035

72.68

0.0010244

4.5252

304.25

2630.7

0.9876

7.7146

0.035

0.040

75.86

0.0010264

3.9931

317.57

2636.1

1.0259

7.6690

0.040

0.045

78.71

0.0010282

3.5761

329.55

2640.9

1.0601

7.6288

0.045

0.05

81.32

0.0010299

32401

340.48

2645.2

1.0910

7.5930

0.05

0.06

85.93

0.0010331

2.7318

359.84

2652.9

1.1452

7.5311

0.06

0.07

89.93

0.0010359

2.3649

376.68

2659.4

1.1919

7.4790

0.07

0.08

93.49

0.0010385

2.0872

391.64

2665.2

1.2328

7.4339

0.08

0.09

96.69

0.0010409

1.8695

405.13

2670.3

1.2694

7.3942

0.09

0.10

99.61

0.0010431

1.6940

417.44

2674.9

1.3026

7.3588

0.10

0.12

104.78

0.0010473

1.4284

439.30

2683.1

1.3608

7.2976

0.12

0.14

109.29

0.0010510

1.2366

458.37

2690.0

1.4109

7.2460

0.14

0.16

113.30

0.0010544

1.0914

475.34

2696.0

1,4549

7.2014

0.16

0.18

116.91

0.0010576

0.97753

490.67

2701.4

1.4944

7.1620

0.18

(contd.)

408

Handbook of Energy Audit

Press. MPa

Temp. t (°C)

0.20

Volume, m3/kg

Enthalpy, kJ/kg

Entropy, kJ/(kg · K)

Press. MPa

VL

VV

hL

hV

SL

SV

120.21

0.0010605

0.88574

504.68

2706.2

1.5301

7.1269

0.20

0.25

127.41

0.0010672

0.71870

535.35

2716.5

1.6072

7.0524

0.25

0.30

133.53

0.0010732

0.60579

561.46

2724.9

1.6718

6.9916

0.30

0.35

138.86

0.0010786

0.52420

584.31

2732.0

1.7275

6.9401

0.35

0.40

143.61

0.0010836

0.46239

604.72

2738.1

1.7766

6.8954

0.40

0.45

147.91

0.0010882

0.41390

623.22

2743.4

1.8206

6.8560

0.45

0.50

151.84

0.0010926

0.37480

640.19

2748.1

1.8606

6.8206

0.50

0.55

155.46

0.0010967

0.34259

655.88

2752.3

1.8972

6.7885

0.55

0.60

158.83

0.0011006

0.31558

670.50

2756.1

1.9311

6.7592

0.60

0.65

161.99

0.0011044

0.29258

684.22

2759.6

1.9626

6.7321

0.65

0.70

164.95

0.0011080

0.27276

697.14

2762.7

1.9921

6.7070

0.70

0.80

170.41

0.0011148

0.24033

721.02

2768.3

2.0460

6.6615

0.80

0.90

175.36

0.0011212

0.21487

742.72

2773.0

2.0944

6.6212

0.90

1.00

179.89

0.0011272

0.19435

762.68

2777.1

2.1384

6.5850

1.00

1.10

184.07

0.0011330

0.17744

78120

2780.7

2.1789

6.5520

1.10

1.2

187.96

0.001139

0.16325

798.50

2783.8

2.2163

6.5217

1.2

1.3

191.61

0.001144

0.15117

814.76

2786.5

2.2512

6.4936

1.3

1.4

195.05

0.001149

0.14077

830.13

2788.9

2.2839

6.4675

1.4

1.5

198.30

0.001154

0.13170

844.72

2791.0

2.3147

6.4431

1.5

1.6

201.38

0.001159

0.12373

858.61

2792.9

2.3438

6.4200

1.6

1.8

207.12

0.001168

0.11036

884.61

2796.0

2.3978

6.3776

1.8

2.0

212.38

0.001177

0.099581

908.62

2798.4

2.4470

6.3392

2.0

2.2

217.26

0.001185

0.090695

930.98

2800.2

2.4924

6.3040

2.2

2.4

221.80

0001193

0.083242

951.95

2801.5

2.5344

6.2714

2.4

2.6

226.05

0.001201

0.076897

971.74

2802.5

2.5738

6.2411

2.6

2.8

230.06

0.001209

0.071428

990.50

2803.0

2.6107

6.2126

2.8

3.0

233.86

0.001217

0.066664

1008.4

2803.3

2.6456

6.1858

3.0

3.2

237.46

0.001224

0.062475

1025.5

2803.2

2.6787

6.1604

3.2

3.4

240.90

0.001231

0.058761

1041.8

2803.0

2.7102

6.1362

3.4

3.6

244.19

0.001239

0.055446

1057.6

2802.5

2.7403

6.1131

3.6

(contd.)

409

Annexure II : Properties of Steam

Press. MPa

Temp. t (°C)

3.8

Volume, m3/kg

Enthalpy, kJ/kg

Entropy, kJ/(kg · K)

Press. MPa

VL

VV

hL

hV

SL

SV

247.33

0.001246

0.052468

1072.8

2801.8

2.7690

6.0910

3.8

4.0

250.36

0.001253

0.049777

1087.4

2800.9

2.7967

6.0697

4.0

4.2

253.27

0.001259

0.047333

1101.6

2799.9

2.8232

6.0492

4.2

4.4

256.07

0.001266

0.045103

1115.4

2798.7

2.8488

6.0294

4.4

4.6

258.78

0.001273

0.043060

1128.8

2797.3

2.8736

6.0103

4.6

4.8

26140

0.001280

0.041181

1141.8

2795.8

2.8975

5.9917

4.8

5.0

263.94

0.001286

0.039446

1154.5

2794.2

2.9207

5.9737

5.0

5.5

269.97

0.001303

0.035642

1184.9

2789.7

2.9759

5.9307

5.5

6.0

275.59

0.001319

0.032449

1213.7

2784.6

3.0274

5.8901

6.0

6.5

280.86

0.001336

0.029728

1241.2

2778.8

3.0760

5.8515

6.5

7.0

285.83

0.001352

0.027380

1267.4

2772.6

3.1220

5.8146

7.0

7.5

290.54

0.001368

0.025331

1292.7

2765.8

3.1658

5.7792

7.5

8.0

295.01

0.001385

0.023528

1317.1

2758.6

3.2077

5.7448

8.0

8.5

299.27

0.001401

0.021926

1340.7

2751.0

3.2478

5.7115

8.5

9.0

303.35

0.001418

0.020493

1363.7

2742.9

3.2866

5.6790

9.0

9.5

307.25

0.001435

0.019203

1386.0

2734.4

3.3240

5.6472

9.5

10.0

311.00

0.001453

0.018034

1407.9

2725.5

3.3603

5.6159

10.0

11.0

318.08

0.001489

0.015994

1450.3

2706.4

3.4300

5.5545

11.0

12.0

324.68

0.001526

0.014269

1491.3

2685.6

3.4965

5.4941

12.0

13.0

330.86

0.001566

0.012785

1531.4

2662.9

3.5606

5.4339

13.0

14.0

336.67

0.001610

0.011489

1570.9

2638.1

3.6230

5.3730

14.0

15.0

342.16

0.001657

0.010340

1610.2

2610.9

3.6844

5.3108

15.0

16.0

347.36

0.001710

0.009308

1649.7

2580.8

3.7457

5.2463

16.0

17.0

352.29

0.001769

0.008369

1690.0

2547.4

3.8077

5.1785

17.0

18.0

356.99

0.001839

0.007499

1732.0

2509.5

3.8717

5.1055

18.0

19.0

361.47

0.001925

0.006673

1776.9

2465.4

3.9396

5.0246

19.0

20.0

365.75

0.002039

0.005858

1827.1

2411.4

4.0154

4.9299

20.0

21.0

369.83

0.002212

0.004988

1889.4

2337.5

41093

4.8062

21.0

22.0

373.71

0.002750

0.003577

2021.9

2164.2

4.3109

4.5308

22.0

pc

373.946

0.003106

0.003106

2087.5

2087.5

4.4120

4.4120

pc

pc = 22.064 MPa

410

Handbook of Energy Audit

Superheated Steam – SI Units Pressure MPa (Sat.T)

Temperature—Degrees Celsius 50

100

150

200

250

300

350

400

450

500

550

600

700

0.005 v 29.782 34.419 39.043 43.663 48.281 52.898 57.515 62.131 66.747 71.363 75.979 80.594 89.826 (32.88) h 2593.4 2688.0 2783.4 2879.8 2977.6 3076.9 3177.6 3280.0 3384.0 3489.7 3597.1 3706.3 3929.9 s 8.4976 8.7700 9.0097 9.2251 9.4216 9.6027 9.7713 9.9293 10.078 10.220 10.354 10.483 10.725 0.01 v 14.867 17.197 19.514 21.826 24.136 26.446 28.755 31.064 33.372 35.680 37.968 40.296 44.912 (45.81) h 2592.0 2687.4 2783.0 2879.6 2977.4 3076.7 3177.5 3279.9 3384.0 3480.7 3597.1 3706.3 3929.9 s 8.1741 8.4488 8.6892 8.9048 9.1014 9.2827 9.4513 9.6093 9.7584 9.8997 10.034 10.163 10.405 0.02 v (60.06) h s

8.5857 9.7488 10.907 12.064 13.220 14.375 15.530 16.684 17.839 18.993 20.147 22.455 2686.2 2782.3 2879.1 2977.1 3076.5 3177.4 3279.8 3383.8 3489.6 3597.0 3706.2 3929.8 8.1262 8.3680 8.5842 8.7811 8.9624 9.1311 9.2892 9.4383 9.5797 9.7143 9.8431 10.086

0.05 v (81.32) h s

3.4188 3.8899 4.3563 4.8207 5.2841 5.7470 6.2095 6.6718 7.1339 7.5959 8.0578 8.9614 2682.4 2780.2 2877.8 2976.2 3075.8 3176.8 3279.3 3383.2 3489.6 3596.7 3706.0 3929.7 7.6952 7.9412 8.1591 8.3568 8.5386 8.7076 8.8658 9.0150 91565 9.2912 9.4200 9.6625

0.10 v (99.61) h s

1.6960 1.9367 2.1725 2.4062 2.6389 2.8710 3.1027 3.3342 3.5656 3.7968 4.0279 4.4900 2675.8 2776.6 2875.5 2974.5 3074.5 3175.8 3278.5 3382.8 3488.7 3596.3 3705.6 3929.4 7.3610 7.6147 7.8356 8.0346 8.2171 8.3865 8.5451 8.6945 8.8361 8.9709 9.0998 9.3424

0.15 v (111.35) h s

1.2856 1.4445 1.6013 1.7571 1.9123 2.0671 2.2217 2.3762 2.5305 2.6847 2.9929 2772.9 2873.1 2972.9 3073.3 3174.9 3277.8 3382.2 3488.2 3595.8 3705.2 3929.1 7.4207 7.6447 7.8451 8.0284 8.1983 8.3571 8.5067 8.6484 8.7833 8.9123 9.1550

0.20 v (120.21) h s

0.9599 1.0805 1.1989 1.3162 1.4330 1.5493 1.6655 1.7814 1.8973 2.0130 2.2444 2769.1 2870.8 2971.3 3072.1 3173.9 3277.0 3381.5 3487.6 3595.4 3704.8 3928.8 7.2809 7.5081 7.7100 7.8940 8.0643 8.2235 8.3733 8.5151 8.6501 8.7792 9.0220

0.25 v (127.41) h s

0.7644 0.8621 0.9574 1.0617 1.1454 1.2387 1.3317 1.4246 1.5174 1.6101 1.7952 2765.2 2868.4 2969.6 3070.8 3172.9 3276.2 3380.9 3487.1 3594.9 3704.4 3928.5 7.1707 7.4013 7.6046 7.7895 7.9602 8.1196 8.2696 8.4116 8.5467 8.6759 8.9188

0.30 v (133.53) h s

0.6340 0.7164 0.7965 0.8753 0.9536 1.0315 1.1092 1.1867 1.2641 1.3414 1.4958 2761.2 2866.0 2967.9 3069.6 3172.0 3275.4 3380.2 3486.6 3594.5 3704.0 3928.2 7.0791 7.3132 7.5181 7.7037 7.8749 8.0346 8.1846 8.3269 8.4622 8.5914 8.8344

0.35 v (138.86) h s

0.5408 0.6124 0.6815 0.7494 0.8167 0.8836 0.9503 1.0168 1.0632 1.1495 1.2819 2757.1 2863.5 2966.3 3068.4 3171.0 3274.6 3379.6 3486.0 3594.0 3703.6 3927.9 7.0002 7.2381 7.4445 7.6310 7.8026 7.9626 8.1130 8.2553 8.3906 8.5199 8.7630

0.40 v (143.61) h s

0.4709 0.5343 0.5952 0.6549 0.7139 0.7726 0.8311 0.8894 0.9475 1.0056 1.1215 2752.8 2861.0 2964.6 3067.1 3170.0 3273.9 3379.0 348.55 35936 37032 3927.6 6.9305 7.1724 7.3805 7.5677 7.7398 7.9001 8.0507 8.1931 8.3286 8.4579 8.7012

(contd.)

Annexure II : Properties of Steam

Pressure MPa (Sat.T)

411

Temperature—Degrees Celsius 50

100

150

200

250

300

350

400

450

500

550

600

700

0.45 v (147.91) h s

0.4164 0.4736 0.5281 0.5814 0.6341 0.6863 0.7384 0.7902 0.8420 0.8936 0.9968 2748.3 2858.5 2962.8 3065.9 3169.0 3273.1 3378.3 3484.9 3593.1 3702.8 3927.3 6.8677 7.1139 7.3237 7.5117 7.6843 7.8449 7.9957 8.1383 8.2738 8.4032 8.6466

0.50 v (151.84) h s

0.4250 0.4744 0.5226 0.5701 0.6173 0.6642 0.7109 0.7576 0.8041 0.8970 2855.9 2961.1 3064.6 3168.1 3272.3 3377.7 3484.4 3592.6 3702.5 3927.0 7.0611 7.2726 7.4614 7.6345 7.7954 7.9464 8.0891 8.2247 8.3543 8.5977

0.55 v (155.46) h s

0.3853 0.4305 0.4745 0.5178 0.5608 0.6035 0.6461 0.6885 0.7308 0.8153 2853.3 2969.4 3063.3 3167.1 3271.5 3377.0 3483.9 3592.2 3702.1 3926.8 7.0128 7.2261 7.4158 7.5894 7.7505 7.9017 8.0446 8.1803 8.3099 8.5535

0.60 v (158.43) h s

0.3521 0.3939 0.4344 0.4743 0.5137 0.5530 0.5920 0.6309 0.6698 0.7473 2850.7 2957.7 3062.1 3166.1 3270.7 3376.4 3483.3 3591.7 3701.7 3926.5 6.9684 7.1834 7.3740 7.5480 7.7095 7.8609 8.0039 8.1398 8.2694 8.5131

v = specific volume m3/kg

h = enthalpy, kJ/kg

s = entropy, kJ/(kg·K)

Superheated Steam – SI Units Pressure MPa (Sat.T)

Temperature—Degrees Celsius 200

250

300

350

400

450

500

550

600

650

700

750

800

0.65 v 0.3241 0.3629 0.4005 0.4374 0.4739 0.5102 0.5463 0.5822 0.6181 0.6539 0.6897 0.7254 0.7611 (161.99) h 2848.0 2955.9 3060.8 3165.1 3269.9 3375.7 3482.8 3591.3 3701.3 3812.9 3926.2 4041.1 4157.7 s 6.9270 7.1439 7.3354 7.5099 7.6717 7.8233 7.9665 8.1024 8.2321 8.3564 8.4759 8.5911 8.7024 0.70 v 0.3000 0.3364 0.3714 0.4058 0.4398 0.4735 0.5070 0.5405 0.5738 0.6071 0.6403 0.6735 0.7067 (164.95) h 2845.3 2954.1 3059.5 3164.1 3269.1 3375.1 3482.3 3590.8 3700.9 3812.6 3925.9 4040.8 4157.5 s 6.8884 7.1071 7.2995 7.4745 7.6366 7.7884 7.9317 8.0678 8.1976 8.3220 8.4415 8.5567 8.6680 0.75 v 0.2791 0.3133 0.3462 0.3784 0.4102 0.4417 0.4731 0.5043 0.5354 0.5665 0.5975 0.6285 0.6595 (167.76) h 2842.5 2952.3 3058.2 3163.1 3267.4 3374.4 3481.7 3590.4 3700.5 3812.2 3925.6 4040.6 4157.3 s 6.8520 7.0727 7.2660 7.4415 7.6039 7.7559 7.8994 8.0355 8.1654 8.2898 8.4094 8.5246 8.6360 0.80 v 0.2609 0.2932 0.3242 0.3544 0.3843 0.4139 0.4433 0.4726 0.5019 0.5310 0.5601 0.5892 0.6182 (170.41) h 2839.8 2950.5 30569 31622 32676 3373.8 3481.2 3589.9 3700.1 3811.9 3925.3 4040.3 4157.1 s 6.8176 7.0403 7.2345 7.4106 7.5733 7.7255 7.8690 8.0053 8.1353 8.2598 8.3794 8.4947 8.6060 0.90 v 0.2304 0.2596 0.2874 0.3145 0.3411 0.3675 0.3938 0.4199 0.4459 0.4718 0.4977 0.5236 0.5494 (175.36) h 2834.1 2939.5 3054.3 3160.2 3266.0 3372.5 3480.1 3589.8 3699.3 3811.2 3924.7 4039.8 4156.6 s 6.7538 6.9806 7.1768 7.3538 7.5172 7.6698 7.8136 7.9501 8.0803 8.2049 8.3246 8.4399 8.5513

(contd.)

412

Handbook of Energy Audit

Pressure MPa (Sat.T)

Temperature—Degrees Celsius 200

250

300

350

400

450

500

550

600

650

700

750

800

1.0 v 0.2060 0.2327 0.2580 0.2825 0.3066 0.3304 0.3541 0.3777 0.4011 0.4245 0.4478 0.4711 0.4944 (179.89) h 2828.3 2943.2 3051.7 3158.2 3264.4 3371.2 3479.0 3588.1 3698.6 3810.5 3924.1 4039.3 4156.2 s 6.6955 6.9266 7.1247 7.3028 7.4668 7.6198 7.7640 7.9007 8.0309 8.1557 8.2755 8.3909 8.5024 1.1 v 0.1860 0.2107 0.2580 0.2563 0.2783 0.3001 0.3217 0.3431 0.3645 0.3858 0.4070 0.4282 0.4494 (184.07) h 2822.3 2939.5 3049.1 3156.2 3262.8 3369.9 3477.9 3587.2 3697.8 3809.9 3923.5 4038.8 4155.7 s 6.6414 6.8772 7.0773 7.2564 7.4210 7.5745 7.7189 7.8558 7.9863 8.1111 8.2310 8.3465 8.4580 1.2 v 0.1693 0.1924 0.2139 0.2345 0.2548 0.2748 0.2946 0.3143 0.3339 0.3535 0.3730 0.3924 0.4118 (187.96) h 2816.1 2935.7 3046.4 3154.1 3261.2 3368.6 3476.8 3586.2 3697.0 3809.2 3922.9 4038.3 4155.2 s 6.5908 6.8314 7.0336 7.2138 7.3791 7.5330 7.6777 7.8148 7.9454 8.0704 8.1904 8.3059 8.4175 1.3 v 0.1552 0.1769 0.1969 0.2161 0.2349 0.2534 0.2718 0.2900 0.3081 0.3262 0.3442 0.3621 0.3801 (191.61) h 2809.6 2931.8 3043.7 3152.1 3259.6 3367.3 3475.7 3585.3 3696.2 3908.5 3922.4 4037.8 4154.8 s 6.5430 6.7888 6.9931 7.1745 7.3404 7.4947 7.6397 7.7770 7.9078 8.0329 8.1530 8.2686 8.3803 1.4 v 0.1430 0.1635 0.1823 0.2003 0.2178 0.2351 0.2522 0.2691 0.2860 0.3028 0.3195 0.3362 0.3529 (195.05) h 2803.0 2927.9 3041.0 3150.1 3258.0 3366.0 3474.7 3584.4 3695.4 3807.8 3921.8 4037.2 4154.3 s 6.4975 6.7488 6.9553 7.1378 7.3044 7.4591 7.6045 7.7420 7.5729 7.9981 8.1183 8.2340 8.3457 1.5 v 0.1324 0.1520 0.1697 0.1866 0.2030 0.2192 0.2352 0.2510 0.2668 0.2825 0.2981 0.3137 0.3293 (196.30) h 2796.0 2924.0 3038.3 3148.0 3256.4 3364.7 3473.6 3583.5 3694.6 38072 39212 40367 4153.9 s 6.4537 6.7111 6.9199 7.1035 7.2708 7.4259 7.5716 7.7093 7.8404 7.9657 8.0860 8.2018 8.3135 1.6 v (201.38) h s

0.1419 0.1587 0.1746 0.1901 0.2053 0.2203 0.2352 0.2500 0.2647 0.2794 0.2940 0.3087 2919.9 3035.5 3146.0 3254.7 3363.3 3472.5 3582.6 3693.9 3806.5 3920.6 4036.2 4153.4 6.6754 68865 7.0713 7.2392 7.3948 7.5407 7.6787 7.8099 7.9354 8.0557 8.1716 82834

1.7 v (204.31) h s

0.1330 0.1489 0.1640 0.1786 0.1930 0.2072 0.2212 0.2352 0.2491 0.2629 0.2767 0.2904 2915.9 3032.7 3143.9 3253.1 3362.0 3471.4 3581.6 3693.1 3805.8 3920.0 4035.7 4153.0 6.6413 6.8548 7.0406 7.2094 7.3654 7.5117 7.6499 7.7813 7.9068 8.0273 8.1432 8.2551

1.8 v (207.12) h s

0.1250 0.1402 0.1546 0.1685 0.1821 0.1955 0.2088 0.2220 0.2351 0.2482 0.2612 0.2743 2911.7 3029.9 3141.8 3251.5 3360.7 3470.3 3580.7 3692.3 3805.1 3919.4 4035.2 4152.5 6.6087 6.8247 7.0119 7.1812 7.3377 7.4842 7.6226 7.7542 7.8799 8.0004 8.1164 8.2284

2.0 v (212.38) h s

0.1115 0.1255 0.1386 0.1512 0.1635 0.1757 0.1877 0.1996 0.2115 0.2233 0.2350 0.2467 2903.2 3024.3 3137.6 3248.2 3358.1 3468..1 3578.9 3690.7 3803.8 3918.2 4034.2 4151.6 6.5474 6.7685 6.9582 7.1290 7.2863 7.4335 7.5723 7.7042 7.8301 7.9509 8.0670 8.1791

v = specific volume m3/kg

h = enthalpy, kJ/kg

s = entropy, kJ/(kg·K)

Annexure II : Properties of Steam

Superheated Steam – SI Pressure MPa (Sat.T)

413

Units

Temperature—Degrees Celsius 225

250

300

350

400

450

500

550

600

650

700

750

800

2.2 v 0.0931 0.1004 0.1134 0.1255 0.1371 0.1484 0.1595 0.1704 0.1813 0.1921 0.2028 0.2136 0.2242 (217.26) h 2824.5 3894.5 3018.5 3133.4 3244.9 3355.4 3465.9 3577.0 3689.1 3802.4 3917.1 4033.1 4150.7 s 6.3531 6.4903 6.7168 6.5091 7.0813 7.2396 7.3873 7.5266 7.6588 7.7850 7.9069 8.0222 8.1344 2.4 v 0.0842 0.0911 0.1034 0.1146 0.1253 0.1357 0.1459 0.1560 0.1660 0.1760 0.1858 0.1957 0.2055 (221.80) h 2812.1 2885.5 3012.6 3129.1 3241.6 3352.7 3463.7 3575.2 3687.6 3801.1 3915.5 4032.1 4149.8 s 6.2926 6.4365 6.6688 6.8638 7.0375 7.1967 7.3450 7.4848 7.6173 7.7437 7.8648 7.9813 8.0936 2.6 v (226.05) h s

0.0833 0.0948 0.1053 0.1153 0.1250 0.1345 0.1439 0.1531 0.1623 0.1714 0.1805 0.1896 2876.2 3006.6 3124.8 3238.3 3350.0 3461.5 3573.3 3686.9 1799.7 3914.7 4031.1 4148.9 6.3854 6.6238 6.8216 6.9968 7.1570 7.3060 7.4461 7.5790 7.7056 7.8265 7.5435 8.0559

2.8 v (230.06) h s

0.0765 0.0875 0.0974 0.1068 0.1158 0.1247 0.1334 0.1420 0.1506 0.1591 0.1676 0.1760 2866.5 3000.5 3120.5 3234.9 3347.4 3459.3 3571.5 1684.4 3798.4 3913.5 4030.0 4148.0 6.5814 6.7821 6.9589 7.1200 7.2696 7.4102 7.5434 7.6703 7.7918 7.5085 8.0210

3.0 v (233.86) h s

0.0706 0.0812 0.0906 0.0994 0.1079 0.1162 0.1244 0.1324 0.1406 0.1484 0.1563 0.1642 2856.5 2994.3 3116.1 3231.6 3344.7 3457.0 3569.5 9382.8 3797.0 3912.3 4029.0 4147.0 6.2893 6.5412 6.7449 6.9233 7.0853 7.2356 7.3767 7.5102 7.6373 7.7590 7.8759 7.9885

3.2 v (237.46) h s

0.0655 0.0756 0.0845 0.0929 0.1009 0.1068 0.1165 0.1240 0.1316 0.1390 0.1465 0.1539 2846.2 2988.0 3111.6 3282.8 3341.9 3454.8 3567.7 3861.2 3796.6 3911.2 4028.0 4146.1 6.2434 6.5029 6.7097 6.8897 7.0527 7.2036 7.3451 7.4790 7.6064 7.7283 7.8453 7.9581

3.4 v (240.90) h s

0.0609 0.0707 0.0792 0.0872 0.0948 0.1022 0.1095 0.1166 0.1237 0.1308 0.1378 0.1448 2835.3 2981.6 3107.1 3224.8 3339.2 3452.6 3565.9 3679.6 3794.3 3910.0 4026.9 4145.2 6.1986 6.4662 6.6762 6.8579 7.0219 7.1735 7.3154 7.4496 7.5773 7.6993 7.8165 7.9294

3.6 v (244.19) h s

0.0668 0.0663 0.0745 0.0821 0.0893 0.0964 0.1033 0.1101 0.1168 0.1234 0.1301 0.1367 2824.0 2975.1 3102.6 3221.3 3336.5 3450.3 3564.0 3678.0 3792.9 3908.8 4025.9 4144.3 6.1545 6.4309 6.6443 6.8276 6.9927 7.1449 7.2873 7.4219 7.5498 7.6720 7.7893 7.9023

3.8 v (247.33) h s

0.0531 0.0624 0.0703 0.0775 0.0844 0.0911 0.0977 0.1042 0.1105 0.1165 0.1232 0.1294 2812.1 2968.4 3098.0 32175 3333.7 3448.1 3562.1 3676.4 3791.5 3907.6 4024.8 4143.4 6.1107 6.3968 6.6137 6.7988 6.9649 7.1178 7.2607 7.3955 7.5237 7.6461 7.7636 7.8767

4.0 v (250.36) h s

0.0589 0.0665 0.0734 0.0800 0.0864 0.0927 0.0989 0.1049 0.1110 0.1170 0.1229 2961.7 3093.3 3214.4 3331.0 3445.8 3560.2 3674.8 3790.2 3906.4 4023.8 4142.5 6.3638 6.5843 6.7712 6.9383 7.0919 7.2353 7.3704 7.4989 7.6215 7.7391 7.8523

4.5 v (257.44) h s

0.0514 0.0684 0.0648 0.0708 0.0765 0.0821 0.0677 0.0931 0.0985 0.1038 0.1092 2944.1 3081.5 3205.6 3324.0 3440.2 3555.5 3670.8 3786.7 3903.4 4021.2 4140.2 6.2852 6.5153 6.7069 6.8767 7.0320 7.1765 7.3126 7.4416 7.5647 7.6827 7.7962

(contd.)

414

Handbook of Energy Audit

Pressure MPa (Sat.T)

Temperature—Degrees Celsius 225

250

300

350

400

450

500

550

600

650

700

750

800

5.0 v (263.94) h s

0.0453 0.0520 0.0578 0.0633 0.0686 0.0737 0.0787 0.0836 0.0885 0.0933 0.0982 2925.6 3069.3 3196.6 3317.0 3434.5 3550.8 3666.8 3783.3 3900.5 4018.6 4137.9 6.2109 6.4515 6.6481 6.8208 6.9778 7.1235 7.2604 7.3901 7.5137 7.6321 7.7459

5.5 v (269.97) h s

0.0404 0.0467 0.0522 0.0572 0.0621 0.0668 0.0714 0.0759 0.0603 0.0848 0.0691 2906.2 3056.8 3187.5 3309.9 3428.7 3546.0 3662.8 3779.8 3897.5 4016.0 4135.6 6.1396 6.3919 6.5938 6.7693 6.9282 7.0751 7.2129 7.3432 7.4673 7.5861 7.7002

6.0 v (275.59) h s

0.0362 0.0423 0.0474 0.0522 0.0567 0.0610 0.0653 0.0694 0.0735 0.0776 0.0816 2885.5 3043.9 3178.2 3302.8 3422.9 3541.2 3656.8 3776.4 3691.9 4013.4 4133.3 6.0702 6.3356 6.5431 6.7216 6.8824 7.0306 7.1652 7.3002 7.4248 7.5439 7.6583

6.5 v (280.86) h s

0.0326 0.0385 0.0434 0.0479 0.0521 0.0561 0.0601 0.0640 0.0678 0.0716 0.0753 2863.5 3030.6 3168.7 3295.5 3417.1 3638.4 3654.7 3772.9 3891.5 4010.7 4131.0 6.0018 6.2819 6.4953 6.6771 6.8397 6.5892 7.1287 7.2603 7.3854 7.5050 7.6196

v = specific volume m3/kg

h = enthalpy, kJ/kg

s = entropy, kJ/(kg·K)

Superheated Steam – SI Units Pressure MPa (Sat.T)

Temperature—Degrees Celsius 300

325

350

375

400

450

500

550

600

650

700

750

800

7.0 v 0.0295 0.0326 0.0353 0.0377 0.0400 0.0442 0.0482 0.0520 0.0557 0.0593 0.0628 0.0664 0.0698 (285.83) h 2839.8 2935.5 3016.8 3090.4 3159.1 3288.2 3411.3 3531.5 3650.6 3769.4 3888.5 4008.1 4128.6 s 5.9335 6.0970 6.2303 6.3460 6.4501 6.6351 6.7997 6.9505 7.0909 7.2232 7.3488 7.4687 7.5837 7.5 v 0.0267 0.0298 0.0325 0.0348 0.0370 0.0410 0.0448 0.0483 0.0518 0.0552 0.0586 0.0619 0.0651 (290.54) h 2814.3 2917.4 3002.7 3078.8 3149.3 3280.7 3405.3 3526.7 3646.5 3765.9 3885.4 4005.5 4126.3 s 5.8644 6.0407 6.1805 6.3002 6.4070 6.5954 6.7620 6.9141 7.0555 7.1885 7.3145 7.4348 7.5501 8.0 v 0.0243 0.0274 0.0300 0.0323 0.0343 0.0382 0.0418 0.0452 0.0485 0.0517 0.0548 0.0679 0.0610 (295.01) h 2786.4 2898.3 2968.1 3065.9 3139.3 3273.2 3399.4 3521.8 3542.4 3762.4 3882.4 4000.2 4124.0 s 5.7935 5.9849 6.1319 6.2560 6.3657 6.5677 6.7264 6.8798 7.0221 7.1557 7.2823 7.4030 7.5186 8.5 v 0.0220 0.0252 0.0278 0.0300 0.0320 0.0357 0.0391 0.0424 0.0455 0.0485 0.0515 0.0545 0.0674 (29927) h 2755.4 2878.3 2972.9 3054.7 3129.1 3265.6 3393.4 3516.9 3638.3 3758.9 3879.4 4000.2 4121.7 s 5.7193 5.9294 6.0845 6.2132 6.3259 6.5216 6.6925 6.8473 6.9905 7.1248 7.2519 7.3730 7.4889 9.0 v (303.35) h s

0.0233 0.0258 0.0280 0.0300 0.0335 0.0368 0.0399 0.0429 0.0458 0.0486 0.0514 0.0541 2857.0 2957.2 3042.2 3118.8 3257.9 3387.3 3511.9 3634.2 3755.4 3876.4 3997.6 4119.4 5.8736 6.0378 6.1716 6.2875 6.4871 6.6601 6.8163 6.9605 7.0955 7.2231 7.3446 7.4608

(contd.)

Annexure II : Properties of Steam

Pressure MPa (Sat.T)

415

Temperature—Degrees Celsius 300

325

350

375

400

450

500

550

600

650

700

750

800

9.5 v (30725) h s

0.0215 0.0240 0.0262 0.0281 0.0316 0.0347 0.0377 0.0405 0.0433 0.0460 0.0486 0.0612 2834.4 2940.9 3029.4 3108.2 3250.2 3381.2 3505.9 3630.0 3751.9 3873.3 3994.9 4117.0 5.8170 5.9917 6.1309 6.2502 6.4538 6.6291 6.7867 6.9319 7.0676 71957 7.3176 7.4341

10.0 v (311.00) h s

0.0199 0.0224 0.0246 0.0264 0.0298 0.0328 0.0357 0.0384 0.0410 0.0436 0.0461 0.0486 5759.3 2924.0 3016.2 3097.4 3242.3 3375.1 3501.9 3625.4 3748.3 3870.3 3992.3 4114.7 5.9458 6.0910 6.2139 6.4217 6.5993 6.7584 6.9045 7.0409 7.1696 7.2918 7.4086

11.0 v (318.08) h s

0.0170 0.0196 0.0217 0.0235 0.0267 0.0295 0.0322 0.0347 0.0371 0.0395 0.0418 0.0441 2755.6 2887.8 2988.7 3075.1 3226.2 3362.6 3491.9 3617.5 3741.2 3864.2 3987.0 4110.1 5.6373 5.8541 6.0129 6.1438 6.3605 6.5430 6.7050 6.8531 6.9910 7.1207 7.2437 7.3612

12.0 v (324.68) h s

0.0143 0.0172 0.0193 0.0211 0.0242 0.0268 0.0293 0.0317 0.0339 0.0361 0.0383 0.0404 2688.4 2848.0 2959.5 3051.9 3209.8 3350.0 3481.7 3609.0 3734.1 3858.1 3981.6 4105.4 5.4988 5.7607 5.5362 6.0762 6.3027 6.4902 6.6553 6.8055 6.9448 7.0756 7.1994 7.3175

13.0 v (330.86) h s

0.0151 0.0173 0.0190 0.0220 0.0245 0.0269 0.0291 0.0312 0.0332 0.0352 0.0372 2803.6 2928.3 3027.6 3192.9 3337.1 3471.4 3600.5 3726.9 3851.9 3976.3 4100.7 5.6635 5.8600 6.0104 6.2475 6.4404 6.6087 6.7610 6.9018 7.0336 71583 7.2771

14.0 v (336.67) h s

0.0132 0.0155 0.0172 0.0201 0.0225 0.0248 0.0268 0.0288 0.0308 0.0326 0.0345 2752.9 2894.9 3002.2 3175.6 3324.1 3461.0 3591.9 3719.7 3845.7 3970.9 4096.0 5.5595 5.7832 5.9457 6.1945 6.3931 6.5548 6.7192 5.8615 6.9944 7.1200 7.2393

15.0 v (342.16) h s

0.0115 0.0139 0.0157 0.0185 0.0208 0.0229 0.0249 0.0268 0.0286 0.0304 0.0321 2693.0 2858.9 2975.5 3157.8 3310.8 3450.5 3583.3 3712.4 3839.5 3965.6 4091.3 5.4435 5.7049 5.8817 6.1433 6.3479 6.5230 6.6797 6.8235 6.9576 7.0839 7.2039

16.0 v (34736) h s

0.0098 0.0125 0.0143 0.0170 0.0193 0.0214 0.0232 0.0250 0.0267 0.0284 0.0301 2617.0 2819.5 2947.5 3139.6 3297.3 3439.8 3574.6 3705.1 3833.3 3960.2 4086.6 5.3045 5.6238 5.8177 6.0935 6.3045 6.4832 6.6422 6.7876 6.9228 7.0499 7.1706

17.0 v (35229) h s

0.0112 0.0130 0.0158 0.0180 0.0199 0.0218 0.0235 0.0251 0.0267 0.0282 2775.9 2917.8 3120.9 3283.6 3429.1 3565.9 3697.8 3827.0 3954.8 4081.9 5.5384 5.7533 6.0449 6.2627 6.4451 6.6064 6.7534 6.8897 7.0178 7.1391

18.0 v (356.99) h s

0.0100 0.0119 0.0147 0.0168 0.0187 0.0204 0.0221 0.0236 0.0251 0.0266 2726.9 2886.3 3101.7 3269.7 3418.3 3557.0 3690.4 3820.7 3949.4 4077.2 5.4465 5.6881 5.9973 6.2222 6.4085 6.5722 6.7208 6.8583 6.9872 7.1091

v = specific volume m3/kg

h = enthalpy, kJ/kg

s = entropy, kJ/(kg·K)

416

Handbook of Energy Audit

Superheated Steam – SI Units Pressure MPa (Sat.T)

Temperature—Degrees Celsius 375

400

425

450

475

500

550

600

650

700

750

800

20 v 0.00768 0.00995 0.0115 0.0127 0.0138 0.0148 0.0166 0.0182 0.0197 0.0211 0.0225 0.0239 (365.75) h 2602.4 2816.8 2952.9 3061.5 3155.8 3241.2 3396.2 3539.2 3675.6 3806.2 3938.5 4067.7 s 5.2272 5.5525 5.7510 5.9041 6.0322 6.1445 6.3390 6.5077 6.6596 6.7994 6.9301 7.0534 22 v 0.00490 0.00826 0.00987 0.0111 0.0122 0.0131 0.0148 0.0163 0.0178 0.0191 0.0204 0.0216 (373.71) h 2354.0 2735.8 2897.8 3019.0 3121.0 3211.8 3373.8 3521.2 3660.6 3795.5 3927.6 4058.2 s 4.8240 5.4050 5.6417 5.8124 5.9611 6.0704 6.2736 6.4475 6.6029 6.7451 6.8776 7.0022 24

v 0.00206 0.00673 0.00850 0.00977 0.0108 0.0118 0.0134 0.0148 0.0161 0.0174 0.0186 0.0197 h 1872.5 2637.4 2837.4 2974.0 3084.8 3181.4 3350.9 3502.9 3645.6 3782.8 3916.7 4048.8 s 4.0731 5.2366 5.5289 5.7212 5.8720 5.9991 6.2116 6.3910 6.5499 6.6946 6.8289 6.9549

26

v 0.00192 0.00529 0.00731 0.00662 0.00967 0.0106 0.0121 0.0135 0.0148 0.0160 0.0171 0.0182 h 1832.8 2510.6 2770.6 2926.1 3047.0 3150.2 3327.6 3484.4 3630.4 3770.0 3905.8 4039.3 s 4.0059 50304 5.4106 5.6296 5.7942 5.9298 6.1523 6.3374 6.5000 6.6473 6.7833 6.9107

28

v 0.00185 0.00385 0.00625 0.00762 0.00867 0.00957 0.0111 0.0124 0.0136 0.0147 0.0158 0.0168 h 1809.1 2334.4 2695.8 2875.1 3007.7 3117.9 3303.9 3465.7 3615.1 3757.1 3894.8 4029.7 s 3.9535 4.7552 5.2841 5.5367 5.7170 5.8621 6.0953 6.2863 6.4527 6.6026 6.7405 6.8693

30

v 0.00179 0.00280 0.00530 0.00674 0.00780 0.00869 0.0102 0.0114 0.0126 0.0137 0.0147 0.0156 h 1792.0 2152.4 2611.9 2820.9 2966.7 3084.8 3279.8 3446.9 3599.7 3744.2 3883.8 4020.2 s 3.9314 4.4750 5.1473 5.4419 5.6402 5.7956 6.0403 6.2374 6.4077 6.5602 6.7000 6.8303

35

v 0.00170 0.00211 0.00344 0.00496 0.00606 0.00693 0.00835 0.00952 0.0106 0.0115 0.0124 0.0133 h 1762.5 1968.4 2373.5 2671.0 2857.3 2998.0 3218.1 3399.0 3560.9 3711.9 3856.3 3996.5 s 3.8725 4.2140 4.7752 5.1945 5.4480 5.6331 5.9093 6.1229 6.3032 6.4625 6.6072 6.7411

40

v 0.00164 0.00191 0.00254 0.00369 0.00476 0.00562 0.00699 0.00809 0.00905 0.00993 0.0107 0.0115 h 1742.7 1931.1 2198.6 2511.8 2740.1 2906.7 3154.6 3350.4 3521.8 3679.4 3828.8 3972.8 s 3.8290 4.1141 4.5037 4.9447 5.2555 5.4746 5.7859 6.0170 6.2079 6.3743 6.5239 6.6614

45

v 0.00160 0.00180 0.00219 0.00292 0.00382 0.00463 0.00594 0.00698 000788 0.00870 0.00945 0.0102 h 1728.0 1897.6 2110.8 2377.3 2623.4 2813.4 3090.2 3301.5 3482.5 3647.0 3801.3 3949.3 s 3.7939 4.0505 4.3612 4.7362 5.0710 5.3209 5.6685 5.9179 6.1197 6.2932 6.4479 6.5891

50

v 0.00156 0.00173 0.00201 0.00249 0.00317 0.00389 0.00512 0.00611 0.00696 0.00772 0.00842 0.00907 h 1716.6 1874.3 2060.2 2284.4 2520.0 2722.5 3025.7 3252.6 3443.5 3614.8 3774.1 3926.0 s 3.7642 4.0028 4.2738 4.5892 4.9096 5.1759 5.5566 5.8245 6.0372 6.2180 6.3777 6.5226

60

v 0.00150 0.00163 0.00182 0.00208 0.00247 0.00295 0.00395 0.00483 0.00559 0.00627 0.00688 0.00746 h 1699.9 1843.1 2001.6 2179.8 2375.2 2570.4 2902.1 3157.0 3366.8 3551.4 3720.6 3880.2 s 3.7148 3.9316 4.1626 4.4134 4.6790 4.9356 5.3519 5.6528 5.8867 6.0815 6.2512 6.4034

(contd.)

Annexure II : Properties of Steam

Pressure MPa (Sat.T)

417

Temperature—Degrees Celsius 375

400

425

450

475

500

550

600

650

700

750

800

70

v 0.00146 0.00157 0.00171 0.00189 0.00214 0.00246 0.00322 0.00397 0.00465 0.00525 0.00880 0.00632 h 1688.4 1822.9 1967.1 2123.4 2291.7 2466.2 2795.0 3067.5 3293.6 3490.5 3669.0 3835.8 s 3.6743 3.8778 4.0880 4.3080 4.5368 4.7662 5.1786 5.5003 5.7522 5.9600 6.1390 6.2982

80

v 0.00143 0.00152 0.00163 0.00177 0.00196 0.00219 0.00276 0.00338 0.00398 0.00452 0.00501 0.00548 h 1680.4 1808.8 1944.0 2087.6 2239.6 2397.6 2709.9 2988.1 3225.7 3432.9 3619.7 3793.3 s 3.6395 3.8339 4.0311 4.2331 4.4398 4.6474 5.0391 5.3674 5.6321 5.8509 6.0382 6.2039

90

v 0.00140 0.00148 0.00157 0.00169 0.00184 0.00201 0.00246 0.00297 0.00348 0.00397 0.00442 0.00484 h 1674.6 1798.6 1927.6 2062.7 2204.0 2350.3 2645.2 2920.8 3164.4 3379.5 3573.5 3753.0 s 3.6089 3.7965 3.4847 4.1747 4.3669 4.5593 4.9288 5.2540 5.5255 5.7526 5.9470 6.1184

100

v 0.00137 0.00144 0.00153 0.00163 0.00175 0.00189 0.00225 0.00267 0.00311 0.00355 0.00395 0.00434 h 1670.7 1791.1 1915.5 2044.5 2178.3 2316.2 2596.1 2865.1 3110.6 3330.8 3.5307 3715.2 s 3.5815 3.7638 3.9452 4.1267 4.3086 4.4899 4.8407 5.1580 5.4316 5.6640 5.8644 6.0405

v = specific volume m3/kg

h = enthalpy, kJ/kg

s = entropy, kJ/(kg·K)

418

Handbook of Energy Audit

References Book/Reports/ Case Study

1.

Energy Statistics, 2013

Publishing Author/s and Publisher

Year of Publication

Ministry of Statistics and Programme 2013 Implementation (20th Issue)

2.

Load Generation Balance Report 2012–13

Central Electricity Authority

3.

Load Generation Balance Report 2012–13

Load Generation Balance Report 2012–13

4.

National Energy Map for India: Technology TERI Press Vision 2030

5.

Renewable Energy Strategies for Indian Ghosh Debyani, Shukla P R, Garg Amit, Power Sector and Ramana P.V. A Centre De Sciences Humaines (CSH)

6.

Energy Audit Guide Part A: Methodology And Technics

7.

Climate Change Post-Kyoto Perspectives Tata Energy Research Institute From the South

8.

Review of Combined Heat and Power Technologies

Onsite Sycom Energy Corporation

October 1999

9.

Boiler Efficiency Guide

Cleaver–Brooks, Inc

2010

10.

Guide to Combined Heat and Power C B Oland, Oak Ridge National Systems for Boiler Owners and Operators Laboratory

July 2004

11.

Clean Coal Power Generation Technology The World Bank Review: Worldwide Experience and Implications for India

June 2008

12.

Steam System Survey Guide

May 2002

13.

Optimizing Blast Furnace Operation to US Department of Energy Increase Efficiency and Lower Costs

May 2011

14.

Blast Furnace Ironmaking Process Using Nippon Steel Technical Report Pre-Reduced Iron Ore

July 2006

April 2006

Directorate General for Employment and Athens, Social Affairs European Commission May 2000

Greg Harrell, Oak Ridge National Laboratory

420

Handbook of Energy Audit

Book/Reports/ Case Study

Publishing Author/s and Publisher

Year of Publication

15.

Reduction of UBC (Unburned Carbon- Dirk Schmidt, Moo-Sung Oh, Powergen 2006 In-Ash) Using an Innovative Combustion Europe Controller to Increase Efficiency

16.

Savings in Steam Systems (A Case Study)

17.

Compressed Air Energy Savings: SAV-AIR Kenneth J Anderson; Northwest Energy Monitor and Control System and the PNW Efficiency Alliance Compressed Air Challenge

18.

Energy Consumption Characteristics Detlef Westphalen and Scott Koszalinski April 2001 of Commercial Building HVAC Systems Volume I: Chillers, Refrigerant Compressors, and Heating Systems

19.

Energy Consumption Characteristics of Detlef Westphalen and Scott Koszalinski; October Commercial Building HVAC Systems, Building Technologies Program (DOE) 1999 Volume II: thermal Distribution, Auxiliary Equipment, and Ventilation

20.

Energy Consumption Characteristics of Kurt W Roth, Detlef Westphalen, July, 2002 Commercial Building HVAC Systems, John Dieckmann, Sephir D. Hamilton, Volume III: Energy Savings Potential William Goetzler Building Technologies Program (DOE)

21.

The European Green Building Programme European Commission Energy Audit Guidelines

22.

Handbook of Air Conditioning And Shan K Wang Refrigeration McGraw Hill

23.

Thermal Environmental Conditions for ASHRAE STANDARD Human Occupancy 55P

24.

Reducing Technical and Non‐Technical Losses in the Power Sector

World Bank Group Energy Sector July 2009 Strategy

25.

Transmission and Distribution In India

WEC‐IMC and Power Grid Corporation Of India Limited

26.

theft and Loss of Electricity in an Indian Miriam Golden, Brian Min International January State Growth Centre 2012

27.

Tariff Booklet

The Tata Power Company Limited

28.

Energy-Efficient Electric Motor Selection Handbook

Gilbert A McCoy, Todd Litman, John January 1993 G Douglass, Washington State Energy Office, Olympia, Washington, United States, Department of Energy

29.

Lighting Fundamentals L Lighting Upgrade EPA’s Green Lights® Program Manual

Rich Debat Steam Digest

2001

September 2005

February 2003

May 2007

February 1997

References

Reference Paper

1. 2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

Energy Scenario and Vision 2020 in India Conventional and Renewable Energy Scenario of India: Present and Future Energy Efficiency in Buildings

Author/s

P Garg

Name of Journal

Journal of Sustainable Energy and Environment 3, Mahendra Lalwani, Canadian Journal on Electrical Mool Singh and Electronics Engineering Vol. 1, No. 6 R V Shahi Keynote Address for India— International Energy Agency (IEA) Joint Workshop on “Energy Efficiency in Buildings and Building Codes Energy Supply, Demand and I V Saradhi, World Academy of Science, Environmental Analysis—A G G Pandit, Engineering and Technology, 51 Case Study of Indian Energy V D Puranik 2009 Scenario Energy-Saving Potentials Joachim G THERMPROCESS Symposium; for Gas-Fired Industrial Wünning 2007, Germany Furnaces Energy Efficiency Anders Proceedings From the 14th National Industrial Energy Improvement by Mlirtensson Technology Conference, Measurement and Control Houston, USA Effective Utilization of B Das*, S Prakash, The European Journal of Mineral Blast Furnace Flue Dust of P S R Reddy, Processing and Environmental Integrated Steel Plants S K Biswal, Protection B K Mohapatra, V N Misra High-Performance Akihito Suzuki Hitachi Review Condenser Tube Cleaning Kenchu Seki, System Featuring Advanced Dr. Eng. Takeo Ball Collecting Technology Takei Steam Systems in Industry: Einstein, Dan Lawrence Berkeley National Energy Use and Energy Worrell, Ernst Laboratory Efficiency Improvement Khrushch, Marta Potentials Potential Energy Savings in Dragan Šešlija1*, African Journal of Business Compressed Air Systems in Ivana Ignjatović1, Management Serbia Slobodan Dudić1 and Bojan Lagod2 Energy Saving Through Md. Zahurul Haq Short Course on Energy Efficiency HVAC System Improvement

421

Year of Publication

2012 October 2010

October 2006

2007

April 1992

2002

2005

2001

July 2011

422

Handbook of Energy Audit

Reference Paper

12.

13.

14.

15.

16.

17. 18.

19.

20.

21.

Transmission and Distribution of Electricity In India Regulation, Investment and Efficiency Energy Efficient Electric Motors

Author/s

Name of Journal

Year of Publication

Yoginder Alagh

R Hanitsch

University of Technology, Berlin Germany; RIO 02—World Climate and Energy Event Energy Audit and Nagendrappa. Department of Electrical and Management of Induction H1. Prakash Bure 2 Electronics Engineering, National Motor Using Field Test and Institute of Technology (NIT) Genetic Algorithm Karnataka, Surathkal, India; International Journal of Recent Trends in Engineering, Vol 1, No. 3 Energy Efficient Industrial Gajendra Singh, International Journal of N K Sharma, Engineering Science and Motors P Tiwari Technology, Vol. 2(12) Improving the Efficiency of J. Smrekar, J Energy Conversion and Natural Draft Cooling towers Oman*, Management, 47 B Sˇirok Improving Cooling tower Robert C Monroe Seventh Turbomachinery Fan System Efficiencies Symposium, Texas Parametric Study O P Singh International Journal of Advances of Centrifugal Fan in Engineering and Technology 1*. Rakesh Performance: Experiments Khilwani and Numerical 2. T Sreenivasulu Simulation 1. M Kannan A Programming Design King-Leung Wong, IMECS, Hong Kong for Calculating Suitable Wen-Lih Chen, Insulation Thickness and Tsung-Lieh Hsien, Heat Transfer Characteristics Hsueh-Chieh Yu of an Insulated Rectangular Duct with One to Three Insulated Layers Optimum Insulation M S Soè Ylemez, Energy Conversion and Thickness for Refrigeration Management, 40 M UÈ Nsal Applications Energy Auditing and Tahsin Engin, Energy Conversion and Recovery for Dry Type Management, 46 Vedat Ari Cement Rotary Kiln Systems—A Case Study

January 6–11, 2002

May 2009

2010

2006

December 1978 May 2011

2008

1999

2005

References

Reference Paper

22.

Author/s

Heat Exchanger Efficiency

Name of Journal

Year of Publication

Ahmad Fakheri

Website

423

Data Collected

1.

www.dgvcl.com

Tariff Data

2.

www.pal.com

Improving Coal Pulveriser Performance and Reliability

3.

www.eptq.com

Optimizing Steam System

4.

www.abb.com

Power Factor Correction and Harmonic Filtering In Electrical Plants

5.

www.amca.org

Fan Efficiency Standards

6.

www.igbc.com

Green Building Rating System

Index 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

Global and Indian Energy Scenario Global Environmental Concerns Types of Energy Audit and Energy Audit Methodology Survey Instrumentation Energy Audit of Boilers Energy Audit of Furnaces Energy Audit of Power Plants Energy Audit of Steam Distribution Systems Energy Audit of Compressed Air Network Energy Audit of HVAC System Electrical Load Management Energy Audit of Motor Energy Audit of Pumps, Fan and Cooling Towers Energy Audit of Lighting System Energy Audit Applied to Building Thermal Insulation and Refractory Material Energy Audit of Chemical Plants and Heat Exchangers Computer Software and Case Studies

Color Plate

1

Major coal field TAJIKISTAN

Main coal-fired power plant Main steel plant Jammu and Kashmir

AFGHANISTAN

Coal-importing port

Himachal Pradesh Punjab Uttarakhand PAKISTAN

CHINA Arunachal Pradesh

Haryana Delhi

Sikkim BHUTAN Assam Nagaland Meghalaya Uttar Pradesh Bihar Manipur Rajasthan BANGLADESH 2 3 Tripura 1 Mizoram West 4 Jharkhand Bengal Kolkata Madhya Pradesh MYANMAR Gujarat 5 Haldia Chhattisgarh 6 Paradip Odisha 7 Maharashtra Mumbai 8 Visakhapatnam NEPAL

INDIA

Arabian sea

Goa

Hyderabad Andhra Pradesh

Bay of Bengal

Karnataka Neyvoli (lignite)

Ennore Chennai

Tamil Nadu Kerala Tuticorin

Major coal fields SRI LANKA

Indian Ocean 0

Km 250 500 Figure 1.1

1. Raniganj 2. Jharia 3. East Bokaro & west Bokaro 4. Singrauli 5. Pench-Kanhan, Tawa Valley 6. Talcher 7. Chanda-wardha 8. Godavari Valley

Indian coal map

Color Plate

2

CO2 30000 t/day COAL 12000 t/day

SO2 + NO2 680 t/day

1000 MW POWER STATION

FURNACE OIL 101 m3/day

920 MW GT

WATER 98000 m3/day UAT ELECTRICITY 80 MW

80 MW

5000 Crores ASH 4200 t/day

Figure 1.2

Energy balance for a 1000 MW thermal power plant Andhra Pradesh, 3% Tamil Nadu, Tripura, 3% 3% Rajasthan, 1%

Tamil Nadu, 1%

Eastern offshore 3% Rajasthan, 9%

Andhra Pradesh, 1%

Gujarat, 6% Eastern offshore, 35%

CBM, 7% Western offshore, 45%

Gujarat, 18%

Assam, 10% Assam, 23% Western offshore, 32%

Chart 1.3 Geographical distribution of crude oil and natural gas in India

Electricity (MW) thousands

250 200

Installed renewable energy Solar 4%

150

Biomass 13% 100

50

Hydro 13%

0 1970 Thermal

1980

1990 Year

Hydro

Figure 1.3

Nuclear

2000

Wind 70%

2010 Other

Total electricity production

Total

Chart 1.4 Energy distribution of total installed capacity of 25410 MW (as on August 2012)

Color Plate

Figure 1.4

3

Map of gas pipelines in India

Color Plate Others, 5%

4

Traction and Railway, 2%

Commercial, 9% Industy, 45%

Agricultural, 17%

Domestic, 22%

Chart 1.5

Sector-wise distribution of present energy consumption

Energy intensity of GDP at constant purchasing power parities

Unit: koe/$05p Less than 0.15 koe/$05p 0.15 to 0.20 koe/$05p 0.20 to 0.30 koe/$05p 0.30 to 0.70 koe/$05p More than 0.70 koe/$05p No data

Source Enerdata

Figure 1.5 World map of energy intensity

Cleaning cost 4% Maintenance cost 16%

Energy Cost 54% Operating cost 26%

Figure 2.6

Pie chart of annual building-operating cost

Color Plate

Figure 3.1

5

Multimeter, power-factor meter, and power analyzer Bandwidth filter

Emissivity

Lens Energy radiance

Irradiance reflected energy

Detector

Amp

Output signal Linearization

Figure 3.2

Infrared thermometer and its working

Figure 3.3 Thermographic image of a building

Figure 3.4 Psychrometer and hygrometer

Process pressure

P2 h P1

Figure 3.5

U-tube manometer, Bourdon gauge, piezoelectric pressure sensor, and digital manometer

Color Plate

Figure 3.6

Ultrasonic flowmeter

Figure 3.8

6

Figure 3.7 air velocity

Combustion-gas analyzer

Figure 3.10

Anemometer to measure

Figure 3.9

Tachometer and stroboscope

Lux meter

Color Plate

7

Fully trimmed with all safety controls and piping Exhaust stack

Davited hinged access doors (tubes)

High temp. refractory lined rear door

UL. listed burner

Flame sight port

Fully automated processor

Gas, oil or combination forced draft burners

Figure 4.3

Extra heavy skids and supports

All A.S.M.E. code piping to second valve

Internal construction of a packaged boiler

Exhaust pipe Pressure spring Raw coal feed pipe Air intake Grinding roll Ring or bowl

Bearing

Worm drive

Worm gear Bearing

Figure 4.9

Ring pulverizer

Color Plate

Gasifier

8

Gas stream cleanup/component separation

Fuels

Syngas CO/H2

Chemicals

H2 H2

Gaseous constituents

Coal

Transportation fuels

Particulates

Biomass Feedstock Solids

Petroleum coke/resid

Combustion Turbine

Sulfur/ sulfuric acid Air

Electric power Combined cycle Generator Electric power

Oxygen

ASU

Air

Exhaust Water

Waste

Marketable solid by-products

Steam

Heat recovery steam generator

Stack Exhaust CO2 for sequestration Generator

Electric power Steam turbine

Figure 4.11

Integrated gasification combined cycle

Electrodes

Charging door

Slag

Arc

Molten steel

Figure 5.2

Conveyer and rotary-kiln furnace

Figure 5.4

Arc furnace

Spout

Color Plate

168 Kg/cm2 320°C

Main steam 150 Kglcm2, 540°C

9 Main steam

Reheated steam 35 Kgicm2, 540° C

Reheated steam Bled steam

IP SV & CV 210 MW, KWU design, 3 cylinder turbine

HP SV & CV

HPT

Boiler drum

IPT

247 MVA Generator GEN.

LPT

Deaerator 120°C

Bled steam

Super reheater heater B.F.P.

Evaporator

Economizer 1300°C

Air Coal

FRS Flue gases 244°C 180 Kg/cm2 HP heaters Boiler

Warm water Cooled water

30°C C.W. pump Condensate 45°C

LP heaters Feed water

Figure 6.9

Condenser 0.91 Kg/cm2 vacuum

C.E.pump

Steam and water circuits of thermal power plant Shaft seals

Timing grars

Cooling jackets

Anti-friction and roller bearings

Figure 8.4

Asymmetric rotors

Rotary screw compressor

Cooling tower

Feed water Condenser cooling water

Color Plate

Fan cover (hood)

10

Stator (Windings)

Fan Frame

Bearings Bracket (end bell)

Rotor Conduit box cover

Figure 10.7

Image of illegal tapping of electricity

Motor shaft

Conduit box

Figure 11.1

Seal

Internal view of a motor

Compressor 42% RAC 5%

Fans 13% Pumps 42%

Others 35%

Figure 11.2

Industrial uses of motors

More copper wiring in stator

Figure 11.6

Image of a soft starter

Higher slot fill

Lower loss premium steel core Longer stator steel stack with thinner laminations

Figure 11.7

IE3 Premium-efficiency motor

Color Plate

Energy cost

Maintenance cost

Initial cost

Other cost

Figure 12.A.1

Air conditioning Other equipment

11

Lifecycle cost of pump

Lighting

Conduction through glazed walls

Internal heat gain

Ventilation fans

Roof conduction

Wall conduction

Chart 14.1 Energy consumption in a commercial building

Figure 14.1

Chart 14.2 Approximate heat gain in a building premises

Different fixtures for skylights

Color Plate

12

Leh

Delhi

Ahmedabad Kolkata

Hyderabad

Legends Bengaluru

Hot and dry Hot humid Composite Gold Moderate

Map of India showing different climatic zones (map not to scale) Figure 14.2

Different climate zones of India