Bunker Fuel for Marine Engines : A Technical Introduction 9781908663030, 9781908663009

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A Technical Introduction

Nigel Draffin

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BUNKER FUEL FOR MARINE ENGINES A Technical Introduction

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BUNKER FUEL FOR MARINE ENGINES

Dedication

This book is dedicated to my wife Chris and my sons, David and William, who put up with years of ‘an absent husband’ and ‘an absent dad’ whilst I acquired the experience and understanding to write this book yet who never insisted that I should seek a more conventional lifestyle.

Nigel Draffin

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BUNKER FUEL FOR MARINE ENGINES A Technical Introduction by

Nigel Draffin

First Edition

Foreword by Dr Rudolph Kassinger

Published by Petrospot Limited England 2012

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BUNKER FUEL FOR MARINE ENGINES Published in the United Kingdom by Petrospot Limited Petrospot House, Somerville Court, Trinity Way, Adderbury, Oxfordshire OX17 3SN, England www.petrospot.com Tel: +44 1295 814455 Fax: +44 1295 814466

© Nigel Draffin First published 2012 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library

ISBN 978-1-908663-00-9 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photographic, recorded or otherwise, without the prior written permission of the publisher, Petrospot Limited. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold with the understanding that the publisher is not engaged in rendering legal, accounting, or other professional service. If legal advice or other expert assistance is required, the services of a competent professional person should be sought.

Petrospot books are available at special quantity discounts for use in corporate training programmes or onboard ships Petrospot Limited (www.petrospot.com) Designed by Alison Design and Marketing Limited (www.alison.co.uk) Printed in the United Kingdom by Stephens Print Solutions Limited (www.stephensprintsolutions.com)

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Foreword

Foreword Nigel Draffin is a natural teacher who loves the industry to which he has dedicated almost 50 years of his life. In his latest book, Bunker Fuel for Marine Engines – A Technical Introduction, he has written a comprehensive sequel to John Lamb’s seminal treatise, Petroleum and its Combustion in Diesel Engines. This book, first published in 1955 and long out of print, now has a worthy successor which encompasses another 57 years of history in the bunker fuel sector during which there have been dramatic developments in main and auxiliary diesel engine design, vessel types and other technological advances. In Bunker Fuel for Marine Engines – A Technical Introduction, Nigel once again gets right down to the basics to describe the most complex of issues in a simple, direct style. In this book he sheds light on the complicated relationship between ships’ engines and the marine fuels that power them, and he provides the reader with a solid introduction to a subject which every supplier or user of marine fuels would do well to understand. If you have ever looked at a message from a ship describing an onboard fuelrelated problem and wondered what on earth it means, or if you have ever wondered why there are so many different machines in a ship’s engine room, then this book is written for you. Bunker fuel is the life-blood of the ship. It provides the energy for propulsion, electrical power, heating, cooling, cargo care (including passengers) and for the operation of the onboard pneumatic and hydraulic equipment. A ship’s engine room is a place of refuge for engineers but a place of mysteries to most others. Nigel Draffin embarks on a technical tour around the equipment that will be found there, from main and auxiliary engines to generators, refrigerating plant and other fuel-using machines. This is a chance to look underneath the bonnet or hood and, perhaps for the first time, to recognise what makes this equipment work and why some fuel problems are more significant than others. He takes the reader through the process of burning fuel onboard, from storage of fuel to dealing with the exhaust, before looking at the different types of diesel engine and their specific fuel requirements. He looks at gas turbines, fuel cells and developments in shore power, and covers boilers, fuel and accommodation heating and incinerators, before also looking at waste heat recovery systems. Fuel types and bunker quality standards are succinctly reviewed, as well as blending, storage and onboard fuel treatment, where the work of separators, purifiers, clarifiers, decanters, homogenisers, filters and other engine room kit is explained. Fuel heating, pumps, fuel measurement and storage are also amply covered.

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BUNKER FUEL FOR MARINE ENGINES

Importantly, the book looks at emissions and how they might be controlled, and also at unconventional fuels such as biodiesel, shale oil, liquefied and compressed natural gas, liquefied petroleum gas and even coal. As someone who has been deeply involved with marine fuels for even longer than Nigel Draffin has, I can see that this book is a valuable addition to the growing library of useful books on marine fuels. I suggest that this volume should have a place onboard ship or on the shelves of a shipowner, charterer or bunker supplier. It seems to me that the more people able to access and understand the information contained in this book, the fewer fuel-related engine problems might be expected. And for seafarers, and for those involved in any way in shipping, this can only be a good development. Dr Rudolph Kassinger Westfield, New Jersey May 2012

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Preface

Preface I have always wanted to write a book that introduced the non-specialist to the fascinating world of how ships work. In this book I have focused on the engine room and on the equipment that heats, treats and burns fuel. My intention is to explain what goes on in this space, how the machinery works and integrates with the ship’s functions, and why the way we source, supply, treat and use fuel is so significant for the efficient, economic and environmentally acceptable operation of ships. This book is not a textbook for marine engineers, nor is it an academic reference book for serious study. It is a book that may prove a useful companion for non-specialists when they are confronted with comment or detail they do not immediately understand. If I have oversimplified, or if my explanations are in any way misleading, then I apologise in advance but would plead the need to keep things clear and simple. Nigel Draffin May 2012

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About the author

About the author Bunker Fuel for Marine Engines – A Technical Introduction is Nigel Draffin’s fifth book on marine fuels and one of the first to address technical issues in bunkering since John Lamb’s iconic The Running and Maintenance of the Marine Diesel Engine written in 1927 and Petroleum and its Combustion in Diesel Engines, written in 1955. Nigel has been involved in shipping for almost 50 years and with the commercial bunker market for over 25 years. After joining Shell Tankers as an apprentice engineer in 1966, he progressed through the ranks, serving on all classes of vessel, including very large crude carriers (VLCCs) and liquefied natural gas (LNG) tankers. He came ashore in 1979 to join the newbuilding department of Shell International Marine. After two years of new construction in Ireland, South Korea and the Netherlands, he transferred to Shell’s Research & Development unit, specialising in control systems, fuel combustion and safety systems. In 1986, Nigel moved to the commercial department as a bunker buyer and economics analyst. In 1988, he was promoted to be Head of Operational Economics, responsible for all of the fuel purchased for the Shell fleet, the operation of the risk management policy and the speed/performance of the owned fleet. In March 1996, he joined the staff of E.A.Gibson Shipbrokers Ltd in the bunker department, and became the manager. In 2006, this department merged with US-based broking house LQM Petroleum Services, where Nigel is currently Senior Broker and Technical Manager. Nigel is a founder member of the International Bunker Industry Association (IBIA) and has served several times on its council of management and executive board. In April 2012, he was elected Chairman and is a member of the Education Working Group. He is also the author of IBIA’s Basic Bunkering Course. He is the Director of both the Oxford Bunker Course and the Oxford Bunker Course (Advanced). Nigel is a member of the Institute of Marine Engineering Science and Technology and Past Master of the Worshipful Company of Fuellers. Nigel’s bunker books have been sold all over the world and continue to contribute enormously to the knowledge and understanding of hundreds of newcomers to the industry. Llewellyn Bankes-Hughes Managing Director Petrospot Limited May 2012

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Acknowledgements

Acknowledgements The author wishes to thank all those who have contributed help, comments, images and encouragement throughout the conception, gestation and production of this book. Special thanks are due to Dr Rudy Kassinger who gave encouragement as soon as he knew that I was going to write the book. Many colleagues in IBIA, LQM and elsewhere have answered my questions and made suggestions that have contributed to the scale and scope of this volume. My thanks must also go to the students on the Oxford Bunker Course and other training events for asking an endless flow of questions that provided much of the inspiration for the content. I would also like to note the help and support of two senior engineers from Shell Tankers and Shell International Marine, Arthur Findlater and David Cusdin, who gave me encouragement and inspiration during my career. They have now passed on and I only regret that I was never able to tell them how much their guidance helped me at the time. I extend my thanks to Llewellyn Bankes-Hughes and his team at Petrospot for pressing me into writing this fifth book on bunkering. Particular thanks are due to Alison Cutler, Cheryl Marshall and Lesley Bankes-Hughes for designing, producing and bringing the book to life. Nigel Draffin May 2012

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Contents

Contents Foreword

v

Preface

vii

About the author

ix

Acknowledgements

xi

Chapter 1 - Ships and fuel

1

The engine room..................................................................................................................... 1 Engine room diagrams............................................................................................................ 4 Engine room staff.................................................................................................................. 12

Chapter 2 - Burning fuel

15

Continuous combustion - oil burners..................................................................................... 15 Intermittent combustion - fuel injectors.................................................................................. 18

Chapter 3 - Using fuel onboard

19

Diesel engines....................................................................................................................... 19 What is a ‘good’ fuel?............................................................................................................ 23 Types of diesel engine........................................................................................................... 25 Gas turbines.......................................................................................................................... 33 Fuel cells............................................................................................................................... 34 Boilers................................................................................................................................... 39 Incinerators............................................................................................................................ 43 Inert gas generators.............................................................................................................. 44

Chapter 4 - Waste heat recovery

45

Waste heat simple plant layout.............................................................................................. 46 Waste heat complex plant layout........................................................................................... 47

Chapter 5 - Refining and types of fuel

49

Simple refining....................................................................................................................... 49 Complex refining................................................................................................................... 50 What is in the fuel (and why do we need to know)?.............................................................. 51

Chapter 6 - Quality standards and specifications

55

ISO 8217............................................................................................................................... 55 CIMAC................................................................................................................................... 55

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BUNKER FUEL FOR MARINE ENGINES National specifications........................................................................................................... 56

Chapter 7 - Blending

57

Batch..................................................................................................................................... 57 Splash................................................................................................................................... 57 In line..................................................................................................................................... 57 Stability.................................................................................................................................. 59 Comingling............................................................................................................................ 60

Chapter 8 - Fuel storage and treatment systems onboard ship

61

Layout.................................................................................................................................... 61 Fuel storage.......................................................................................................................... 62

Chapter 9 - Fuel treatment

67

Separators............................................................................................................................. 67 Purifiers................................................................................................................................. 72 Clarifiers................................................................................................................................ 72 Decanters.............................................................................................................................. 72 Homogenisers....................................................................................................................... 73 Blenders................................................................................................................................ 75 Static mixers.......................................................................................................................... 76 Cold filters............................................................................................................................. 76 Hot filters............................................................................................................................... 77

Chapter 10 - Fuel heaters

79

Steam heating....................................................................................................................... 79 Thermal oil heating................................................................................................................ 82 Electric heating...................................................................................................................... 82 Temperature control.............................................................................................................. 82 Viscosity control..................................................................................................................... 83

Chapter 11 - Pumps

85

Centrifugal............................................................................................................................. 85 Positive displacement............................................................................................................ 86

Chapter 12 - Measurement

91

Level...................................................................................................................................... 91 Rate of flow meters............................................................................................................... 91 Volume.................................................................................................................................. 91 Mass ..................................................................................................................................... 91

Chapter 13 - Sensitivity to fuel qualities

93

Storage.................................................................................................................................. 93

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Contents Other storage issues............................................................................................................. 94 Treatment.............................................................................................................................. 94 At the engine......................................................................................................................... 96 Issues using distillate fuels in slow speed and medium speed engines................................ 97 Issues related to change over of fuel grade.......................................................................... 97

Chapter 14 - Emissions

99

SOx..................................................................................................................................... 100 NOx..................................................................................................................................... 100 CO ...................................................................................................................................... 100 CO2 ..................................................................................................................................... 101 PM....................................................................................................................................... 101 Exhaust scrubbers............................................................................................................... 101 NOx control......................................................................................................................... 102

Chapter 15 - Unconventional fuels

105

Biodiesel.............................................................................................................................. 105 Shale oil............................................................................................................................... 105 Liquefied natural gas........................................................................................................... 105 Dual fuel and gas burning engines...................................................................................... 107 Liquefied petroleum gas...................................................................................................... 108 Coal..................................................................................................................................... 108

Glossary

111

Appendix 1 - Where to go for help

129

Non-governmental organisations........................................................................................ 129 Technical and legal information........................................................................................... 130 General bunkering............................................................................................................... 130 Useful websites................................................................................................................... 130

Appendix 2 - ISO 8217:2010

133

Index

137

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List of Tables and Figures

List of Tables and Figures Figure 1.  Traditional 4 ram hydraulic steering gear.............................................................. 3 Photograph courtesy of Nigel Draffin Figure 2.  Two of the four engines of the Stolt Capability ..................................................... 4 Photograph courtesy of Karsten Petersen Figure 3.  Engine room – bottom platform............................................................................. 5 Diagram courtesy of Nigel Draffin Figure 4.  Engine room – middle platform.............................................................................. 6 Diagram courtesy of Nigel Draffin Figure 5.  Engine room – top platform................................................................................... 7 Diagram courtesy of Nigel Draffin Figure 6.  Engine room elevation........................................................................................... 8 Diagram courtesy of Nigel Draffin Figure 7.  Engine room auxiliaries....................................................................................... 10 Photograph courtesy of Nigel Draffin Figure 8.  Main engine control room.................................................................................... 11 Photograph courtesy of Nigel Draffin Figure 9.  Main switchboard................................................................................................. 11 Photograph courtesy of Nigel Draffin Figure 10.  Pressure jet burner ........................................................................................... 16 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 11.  Steam atomised burner ..................................................................................... 16 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 12.  Spirax Sarco Rotary Cup Burner....................................................................... 17 Illustrations and text are taken from the Spirax Sarco website ‘Steam Engineering Tutorials’ at www.spiraxsarco.com/resources/steam-engineering-tutorials.asp. Illustrations and text are copyright, remain the intellectual property of Spirax Sarco, and have been used with their kind permission Figure 13.  Fuel pump internal arrangement....................................................................... 20 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 14.  Fuel valves for K98MC...................................................................................... 21 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 15.  MAN Type TCR turbocharger............................................................................ 23 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 16.  Wärtsilä slow speed engine RTFlex 62............................................................. 25 Photograph courtesy of Wärtsilä Corporation (www.wartsila.com) Figure 17.  Cross-section of MAN Type S35 slow speed engine......................................... 26 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 18.  Loop scavenge.................................................................................................. 27 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 19.  Cross scavenge................................................................................................. 27 Diagram courtesy of Petrospot Ltd (www.petrospot.com)

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BUNKER FUEL FOR MARINE ENGINES Figure 20.  Uniflow scavenge.............................................................................................. 28 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 21.  MAN 58/64 engine (cutaway) ........................................................................... 30 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 22.  Caterpillar C175-16 .......................................................................................... 32 Photograph courtesy of Caterpillar Inc. (www.caterpillar.com) Figure 23.  GE Marine LM2500 gas turbine......................................................................... 34 Drawing courtesy of GE Marine, a division of GE Aviation, Cincinnati OH, USA Figure 24.  Wärtsilä WFC20 fuel cell................................................................................... 35 Photograph courtesy of Wärtsilä Corporation (www.wartsila.com) Figure 25.  Cable connection plugs..................................................................................... 36 Photograph courtesy of Port Metro Vancouver (www.portmetrovancouver.com) Figure 26.  Cavotec ship-mounted cable reel...................................................................... 37 Figure 27.  Cavotec connection ‘pit’ on the quayside with cables connected...................... 37 Photographs courtesy of Cavotec SA (www.cavotec.com) Figure 28.  LNG cold ironing illustration............................................................................... 38 Illustration courtesy of ABB Marine (www.abb.com/marine) Figure 29.  Marine radiant boiler - 3D diagram.................................................................... 40 Figure 30.  Auxiliary boiler - Aalborg Mission D.................................................................. 41 The image is being used under permission by Alfa Laval. Aalborg Mission D is a trademark owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 31.  Packaged boiler Aalborg OS-TCi....................................................................... 42 The image is being used under permission by Alfa Laval. Aalborg OS-TCi is a trademark owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 32.  Atlas incinerator - external................................................................................. 43 Photograph courtesy of Atlas Incinerators A/S (www.atlasinc.dk) Figure 33.  Atlas incinerator - cutaway diagram................................................................... 43 Photograph courtesy of Atlas Incinerators A/S (www.atlasinc.dk) Figure 34.  Alfa Laval inert gas generator ........................................................................... 44 The image is being used under permission by Alfa Laval. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 35.  Sankey diagram................................................................................................. 45 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 36.  Simple waste heat recovery plant...................................................................... 46 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 37.  Waste heat complex plant diagram................................................................... 47 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 38.  A simple refinery................................................................................................ 49 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 39.  Modern refinery process.................................................................................... 50 Diagram courtesy of: Petrospot Ltd (www.petrospot.com) Figure 40.  CBI blender........................................................................................................ 58 Photograph courtesy of CBI Engineering (www.cbi.dk)

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List of Tables and Figures Figure 41.  Manual blender.................................................................................................. 58 Diagram courtesy of Nigel Draffin Figure 42.  Automatic blender.............................................................................................. 59 Diagram courtesy of Nigel Draffin Figure 43.  Fuel system schematic diagram........................................................................ 61 Diagram courtesy of Nigel Draffin Figure 44.  Fuel oil treatment system.................................................................................. 61 Source: CIMAC Recommendation No. 25 (2006). Copyright of CIMAC (www.cimac.com) Figure 45.  Simplified fuel piping diagram for double HFO settling and service tanks......... 62 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 46.  Container vessel bunker tank locations............................................................. 63 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 47.  Tanker bunker tank locations............................................................................. 64 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 48.  General cargo/reefer tank locations.................................................................. 64 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 49.  Settling tank diagram......................................................................................... 65 Source: CIMAC Recommendation No. 25 (2006). Copyright of CIMAC (www.cimac.com) Figure 50.  Separating trough with baffles........................................................................... 67 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 51.  Centrifugal separating bowl............................................................................... 68 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 52.  Purifier bowl and disc-stack............................................................................... 68 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 53.  Purifier............................................................................................................... 69 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 54.  Clarifier.............................................................................................................. 69 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 55.  Automatic desludging purifier............................................................................ 70 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 56.  Conventional separator interface....................................................................... 71 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 57.  Oil/water interface temperature sensitivity......................................................... 71 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 58.  Westfalia separator............................................................................................ 72 Diagram courtesy of GEA Westfalia Separator Group (www.westfalia-separator.com) Figure 59.  Mitsubishi Vane Decanter Centrifuge................................................................ 73 Diagram courtesy of Mitsubishi Kakoki Kaisha, Ltd (www.kakoki.co.jp/english/) Figure 60.  Droplet distribution............................................................................................. 74 Courtesy of JOWA Technology (www.jowa.com) Figure 61.  JOWA Homogeniser.......................................................................................... 74 Courtesy of JOWA Technology (www.jowa.com) Figure 62.  Pressurised fuel oil system with homogeniser................................................... 75 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

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BUNKER FUEL FOR MARINE ENGINES Figure 63.  Cold filter........................................................................................................... 76 Diagram courtesy of Eaton Corporation (www.eaton.com) Figure 64.  Automatic fuel oil filter with electrical motor....................................................... 77 The image is being used under permission by Alfa Laval. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 65.  Fully assembled filter showing full-flow and diversion chamber filter elements and electric motor.................................................................................................................. 78 The image is being used under permission by Alfa Laval. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 66.  Alfa Laval Aalborg MX shell and tube heat exchanger for ships........................ 80 The image is being used under permission by Alfa Laval. Alfa Laval Aalborg MX is a trademark owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 67.  Shell and tube heat exchanger.......................................................................... 80 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 68.  Plate heat exchanger (Alfa Laval)..................................................................... 81 The image is being used under permission by Alfa Laval. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 69.  Flow principle of a plate heat exchanger........................................................... 81 The image is being used under permission by Alfa Laval. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 70.  VESTA EH electric heater.................................................................................. 82 The image is being used under permission by Alfa Laval. VESTA EH is a trademark owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com) Figure 71.  VAF Viscotherm................................................................................................. 83 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 72.  Location of gas oil cooling system..................................................................... 84 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 73.  Components of gas oil chiller system................................................................ 84 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 74.  C2G centrifugal pump........................................................................................ 85 Photograph courtesy of Wärtsilä Hamworthy Limited (www.hamworthy.com) Figure 75.  Centrifugal pumps in engine room..................................................................... 86 Photograph courtesy of Wärtsilä Hamworthy Limited (www.hamworthy.com) Figure 76.  Gear pump......................................................................................................... 87 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 77.  Lobe pump......................................................................................................... 87 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 78.  IMO screw pump............................................................................................... 88 Diagram courtesy of Colfax Fluid Handling (www.colfaxcorp.com) Figure 79.  Screw pump 3 rotors......................................................................................... 88 Diagram courtesy of Colfax Fluid Handling (www.colfaxcorp.com) Figure 80.  Flow process and typical exhaust gas composition........................................... 99 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 81.  Exhaust gas pollutant quantities...................................................................... 100

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List of Tables and Figures Figure 82.  Diagram of water injection system................................................................... 102 Diagram courtesy of Petrospot Ltd (www.petrospot.com) Figure 83.  MAN Humid Air Motor...................................................................................... 103 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 84.  MAN Humid Air Motor...................................................................................... 103 Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com) Figure 85.  Capstone Micro Turbine engine....................................................................... 106 Diagram courtesy of Capstone Turbine Corp. (www.capstoneturbine.com/prodsol/ products/) Figure 86.  The Bit Viking converted to LNG operation..................................................... 108 Photograph courtesy of Tarbit Shipping AB (www.tarbit.se) Figure 87.  River Boyne and River Embley, Australia........................................................ 109

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Ships and fuel

Chapter 1 - Ships and fuel The use of fuel on ships has been fraught with difficulties for centuries. In the early days of coal fired steamships if the boiler output was less than the master desired, or the coal consumption was greater than the owner expected, the first object of their scrutiny was the coal. Within 10 years of the appearance of the steamship we saw the first bunker quality clauses in a charterparty agreement. Once vessels started to use oil as fuel, the quality requirements became more important, especially for the ships with diesel engines. However, for the first 50 years of the 20th century the oil fuel required could be described quite simply: either boiler fuel or diesel oil. All that changed in the 1950s, when new boiler designs on steamships and diesel engines burning residual fuel became the norm. This book is intended to explain why so much time and effort goes into the production, blending, storage, treatment and burning of marine fuels. It is not intended as a textbook for the marine engineer or for the refinery technologist but as a guide for the non-specialist.

The engine room The engine room of a conventional motor ship contains not only the diesel engine itself but all of the ancillary equipment required to keep the ship functioning. The ship will have electrical power generators, almost always diesel driven, providing power for the engine room auxiliary machinery, the hotel services for the crew (lighting, heating and air conditioning) and the services needed for ‘cargo care’ (hotel services for passenger spaces, power for refrigeration on container ships and reefers, heating for some oil cargo and provision of inert gas for tankers). Because of the size of the equipment involved, it is usual for all of the services needed for the engine to be separated from the engine itself – fuel supply, cooling, air supply, etc. – rather than attached to the engine itself (as it is in a motor car or truck). The engine room requires some specific services in order to operate. A salt water cooling system draws sea water into the ship, circulates it through various heat exchangers to cool down the operating fluids onboard before being returned to the sea. Sea water is used in some fluid coolers directly, such as in steam condensers, most engine combustion air coolers (scavenge air cooling), fresh water generators and some emergency engines outside the engine room. The salt water system also supplies and cools the fresh water generators (evaporators) used to make the fresh water onboard used for cooling, boiler systems and drinking. Where sea water is not suitable as a direct cooling fluid, fresh water (usually made onboard from salt water) is circulated through the lubricating oil coolers and

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BUNKER FUEL FOR MARINE ENGINES

through the engine structure (called jacket water cooling) in order to control the temperature of the lubricating oil and the temperature of the engine cylinders. It is used to cool refrigeration plant, air conditioning plant and the hydraulic oil used for hydraulic power to winches, cargo pumps, etc. On some older engines, the fuel injectors are cooled by fresh water. This is a small self-contained system designed to ensure that any fuel oil that leaks into the cooling medium cannot contaminate the whole fresh water cooling system. The fresh water system itself is cooled by sea water. The main exception to the above is the emergency diesel generator (in its generator room outside the engine room) that has its own fresh water cooling system. This system is usually cooled by a large radiator and fan (air cooling). Fuel oil and distillate transfer, treatment and supply systems will be discussed later in some detail. Electrical supply systems for driving motors, lighting, some heating requirements, and navigational systems are supplied by batteries, auxiliary generators and, on electrically-propelled ships, by very large main generators. The number of electrical voltages varies according to the size and complexity of the ship but on a simple general cargo ship they will normally have a 24 volt (V) battery system, and use 220 V alternating current for lighting and domestic machines and 440 V alternating current for motors. Ships with electric propulsion may generate at very much higher voltages and use sophisticated electronic converter systems to regulate the power direction and speed of the propulsion motors. Compressed air systems are installed for general use and for operation there are air driven tools, ventilation fans and lights (especially on tankers). There will also be a high pressure air system for starting the diesel engines. The starting air system is normally fed by large electrically driven air compressors but will have a small diesel driven compressor (hand started) for restoring power after all systems have shut down. All ships have comprehensive ventilation systems for the accommodation spaces, the machinery spaces and, where needed, for the cargo spaces. The two other major services provided are the steering gear and the deck machinery. The steering gear is the equipment which operates the rudder in order to adjust the direction of travel of the vessel. The amount of power required is considerable, even on a small ship, and the majority of steering gear systems are operated by hydraulic rams fed by duplicated electrically driven hydraulic pumps which have a variable output and a variable direction of flow. In almost all ships the steering is controlled by electric valves.

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Ships and fuel

Figure 1.  Traditional 4 ram hydraulic steering gear Photograph courtesy of Nigel Draffin

On some older (and on some smaller) vessels the rudder is attached to a geared quadrant and the quadrant is rotated by electric motors to steer the ship. The electric motors used require a sophisticated control system to regulate the speed and the precise position of the quadrant Ships also require mechanical means of handling mooring ropes, anchor chain (always called anchor cable) and any cranes used for handling cargo and ships stores and spares. This is generically referred to as deck machinery. This equipment (winches, windlasses, cranes, etc.) is usually electrically powered although on tankers it will be driven by hydraulic motors for safety reasons. Hydraulic systems are better when high power is required and will usually afford better control at slow speeds.

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BUNKER FUEL FOR MARINE ENGINES

Figure 2.  Two of the four engines of the Stolt Capability Photograph courtesy of Karsten Petersen

Dry cargo ship On a simple dry cargo ship of 20,000 deadweight tonnes (DWT) with a 6 megawatt (MW) engine, the electrical power required will be about 400 kilowatts (kW) to 500 kW. The ship will have at least two generators rated at this power together with an emergency generator, usually situated outside the engine room with sufficient power to restart the engine room services in case of a complete shut down (between 50 kW and 150 kW in this case).

Engine room diagrams The following diagrams show a generic bulk carrier engine room with a slow speed main engine, and four diesel generators from the late 1990s.

4

Main Engine 6 cylinder 500 mm bore

Ships and fuel

Figure 3.  Engine room – bottom platform Diagram courtesy of Nigel Draffin

5

6

Figure 4.  Engine room – middle platform

Diagram courtesy of Nigel Draffin

Diesel generator no 4

Diesel generator no 3

Diesel generator no 2

Diesel generator no 1

Injection pumps

Top up air compressor

Injection pumps

Main starting air compressors

Control air compressor

Main engine fuel heaters

Diesel oil purifier

Scavenge air blower

Fuel oil Purifier oil heaters purifiers

Boiler fuel pumps Main engine fuel pumps

Scavenge air cooler

Main Engine 6 cylinder 500 mm bore

Injection pumps

Emergency air compressor

Boiler fuel heaters

Auxiliary fresh water pumps Auxiliary fresh water cooler

Emergency air receiver

Main engine lub oil cooler

Main engine jacket water cooler

Fresh water extraction pump

Fresh water generator

Main air receiver

Main air receiver

BUNKER FUEL FOR MARINE ENGINES

Hotwell tank

Figure 5.  Engine room – top platform

Diagram courtesy of Nigel Draffin

7 Cylinder lub oil tank

Jacket water expansion tank

Diesel settling tank

Diesel service tank

Fuel oil service tank Fuel oil settling tank

System lub oil tank

Ships and fuel

BUNKER FUEL FOR MARINE ENGINES

Figure 6.  Engine room elevation Diagram courtesy of Nigel Draffin

8

Ships and fuel

Large tanker/bulker A large tanker or bulker of 150,000 DWT will have a 20 MW main engine and two or three diesel generators of 800 kW-1200 kW in the engine room and an emergency generator of about 200 kW outside. The tanker will also have a large boiler to provide steam for cargo heating and for driving the cargo and ballast pumps.

Cruise liner A cruise liner will have a number of medium speed engines, with some driving the propellers and some smaller ones as generators, or on some vessels all of the engines powering generators with electric propulsion (diesel electric). This is because of the very high electrical power requirement for all the passengers. The total installed power might be as much as 60 MW. In many cases, the engines will be of the same design but with different numbers of cylinders so that the vessel can optimise its efficiency by running just the ‘right’ combination of engines to be at their most efficient. This is often called a ‘father and son’ installation. For example, 2 x 16 cylinder engines and 2 x 8 cylinder engines.

Container ship A big container ship will have one big engine (up to 14 cylinders up to 100 MW) and three or four large generators of 3 MW or 4 MW each. The large generators are required to provide power for the refrigerated containers. This type of ship will normally use the same fuel grade for the main engine and the generators.

LNG tanker Large liquefied natural gas (LNG) tankers use either steam turbines, with large boilers to provide the steam, or special diesel engines. These ships use the ‘boil off’ gas from the cargo as fuel whilst they are on loaded passage and use fuel oil for all or part of their ballast passage. The steam turbines will be about 35 MW, the special diesel engines about 40 MW. They have a high electrical load in port as the cargo pumps are electrically driven, usually with two main generators of at least 3 MW. The engine room will contain cooling pumps (pumping sea water and fresh water), the fuel treatment and fuel supply systems, the pumps and compressors for all of the ship board services (air conditioning, sewage systems, fresh water production, compressed air, etc.) with a few other systems located outside the engine room but dependent on it for power and cooling.

9

BUNKER FUEL FOR MARINE ENGINES

Figure 7.  Engine room auxiliaries Photograph courtesy of Nigel Draffin

On a bulk carrier, tanker or container vessel the engine room is one large space and, for most ships, it will be located towards the after end of the ship. On some ships, such as passenger vessels and roll-on roll-off (ro-ro) ships, the machinery may be distributed in a number of interconnected spaces, with each space dedicated to particular functions (air conditioning plant, electrical generating plant, main switchboards). This permits a more efficient use of the onboard space – passengers do not like to be accommodated below the waterline on a cruise ship! On almost all modern vessels, the engines, generators, pumps and systems are controlled from a central, air-conditioned and insulated control room. On most vessels, the main switchboard is situated in the control room. However, on vessels with ‘high voltage’ systems of more than 440 V AC, the switchboard may be situated in a separate switchboard room that is air-conditioned and insulated.

10

Ships and fuel

Figure 8.  Main engine control room Photograph courtesy of Nigel Draffin

Figure 9.  Main switchboard Photograph courtesy of Nigel Draffin

11

BUNKER FUEL FOR MARINE ENGINES

Starting diesel engines One common question is ‘how do you start the engine?’. When the size of the engines is considered it is easy to understand why they do not use batteries and an electric motor once the engines are more than about 350 kW. The standard method is to inject high pressure air into the cylinders to get the engine turning and then admit fuel once it has reached a certain speed. This requires special ‘starting air valves’ on each cylinder and a large reserve of high pressure air. The air is kept in large air tanks (air receivers) in the engine which are kept topped up by air compressors at all times. They usually contain enough air when full for 10 to 15 starts of the main engine without any top up. But remember that for the big engines, every time the engine switches from running forwards to running backwards, during manoeuvring at an anchorage or in port, it requires a start of the engine. A canal transit involving locks can be a challenging experience.

Engine room staff The engineering department on a conventional cargo ship will number from four to nine people and normally consist of the following: Chief engineer – In charge of the engineering department and its administration. The second most senior officer onboard the ship, he does not usually act as a watchkeeper or duty engineer Second engineer (sometimes called the first assistant engineer) – He is the senior watch keeper or duty engineer. On most ships he is responsible for the day-to-day operation of the engine room Third engineer – On ships without an electrician, he will be responsible for the electrical installation. He is usually responsible for the operation and maintenance of the fuel systems Fourth engineer – The most junior of the watch-keeping or duty engineers Junior engineers – From none, up to three, depending on the onboard manning levels. Engine room crew – Variously called motorman, fireman, greaser, engine room storekeeper (a petty officer), pumpman (petty officer). The senior officers are required to have appropriate certificates issued by the flag state. If the junior engineers or engine room crew are to carry out watch duties they also need appropriate certification from the flag state. If the engine room is equipped for unmanned operation, called an Unmanned Machinery Space (UMS), then one of the seniors will be designated as the duty engineer who will undertake operational duties during the day and respond to alarms when the engine room is unattended.

12

Ships and fuel

If the engine room operates watches, then there will usually be one senior engineer and one junior engineer in the engine room during each watch period. The day is usually split into six four-hour watches.

Additional staff Depending on the size and complexity of the ship, any or all of the following staff may be carried: Electrical engineer – Responsible for the operation and maintenance of all of the electrical equipment onboard Electronics engineer – Carried on vessels with a significant amount of electronic instrumentation and equipment Refrigeration engineer – Responsible for the operation and maintenance of refrigeration and air-conditioning plant onboard Cargo engineer – Usually carried on LNG and liquefied petroleum gas (LPG) tankers to assist with cargo operations and maintain the cargo transfer and cargo monitoring equipment.

13

BUNKER FUEL FOR MARINE ENGINES

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14

Burning fuel

Chapter 2 - Burning fuel The act of burning fuel is to liberate the chemical energy stored in that fuel as heat and to turn that heat into mechanical work (or power). It can be done as a continuous process, where fuel goes in one end and heat comes out of the other, or it can be a batch (intermittent) process, where a defined quantity of fuel is burned, the energy extracted as mechanical work and then the next quantity of fuel is subjected to the process. The fundamental requirements for burning are fuel, oxygen and a source of ignition. The oxygen is normally from air and the source of ignition is a flame, a spark, or exposure to a gas which is hotter than the ‘auto ignition’ temperature of the fuel. The oil burner of a boiler uses the first method of ignition, a gasoline engine uses the second, and a diesel engine uses the third. If you try to burn a fuel, the success will depend on the ability to get the liquid to produce a vapour to mix with the air. Gasoline gives off vapour very freely so it is easy to ignite and will burn quickly and cleanly. Gasoil will give off vapour quite readily at elevated temperatures. Fuel oil has to have a considerable amount of heat to give off enough vapour to sustain combustion. The way around this problem is to create the greatest possible surface area of liquid and expose it to heat. By using an ‘atomising’ spray the fuel is broken into very small droplets with the heat provided by the fuel already burning (in a continuous process such as a boiler) or by the high air temperature in the cylinder of a diesel engine (the intermittent process). The droplet size varies between an upper limit of about 1,000 micrometre (μmetre) to a lower limit of 50 μmetre and is a function of injection pressure, fuel viscosity, temperature and nozzle geometry.

Continuous combustion - oil burners •

The use of fuel in boilers and heaters is generally a continuous process where the oil is burned in a furnace, the heat extracted and the exhaust gas passed out to the atmosphere in a continuous stream.

•

In order to burn the fuel, we need to convert the bulk liquid oil to small droplets so as to maximise the surface area, then, as long as we provide an initial flame, the continuous stream of oil and the correct amount of air, the flame will become self-sustaining. This is done by the use of an oil burner (usually a pressure jet burner) with a sprayer plate or nozzle at the business end which emits the oil into the furnace as a fine spray. As long as the pressure of the incoming oil is within the correct range and the nozzle has clean sharp-edged holes for the oil to spray out of, the flame will be self-sustaining. Pressure jet burners need frequent cleaning.

15

BUNKER FUEL FOR MARINE ENGINES

Swirl ports

Burner body

Cap nut

Orifice plate Swirl chamber

Oil supply

Orifice

Swirl plate

Figure 10.  Pressure jet burner Diagram courtesy of Petrospot Ltd (www.petrospot.com)

The need for a wide load range (for manoeuvring the ship or running a variable number of steam pumps at varying loads) and the ability to automate, led to the development of the steam atomised burner. In this type, the oil, under pressure, is mixed intimately with steam in the sprayer nozzle. The nozzle orifices are small sharp-edged holes but with a larger diameter than the equivalent pressure jet as they have to handle the volume of the atomising steam. Steam atomised burners can remain in use for many weeks without maintenance. Sprayer nozzle

Cap nut

Outer barrel Inner barrel Oil Steam Oil

Washers Figure 11.  Steam atomised burner Diagram courtesy of Petrospot Ltd (www.petrospot.com)

16

Burning fuel

There is an alternative type of burner used for boilers and other continuous process combustion, the rotary cup burner. The working principle of rotary cup burners is based on atomising by centrifugal force. The atomising cup is driven at high speed via a heavy-duty belt drive. The oil is gently positioned at low pressure into the spinning cup where gradually, and forced by the centrifugal action of the cup, it moves forward until it is thrown off the cup rim as a very fine, uniform film. The high velocity primary air discharged around the cup strikes the oil film, breaks it up and converts it into a mist of fine particles, which are introduced into the combustion zone and burner. The secondary air and tertiary air necessary for complete combustion are supplied by a forced-draught fan through ducting around the spinning cup.

Figure 12.  Spirax Sarco Rotary Cup Burner Illustrations and text are taken from the Spirax Sarco website ‘Steam Engineering Tutorials’ at www. spiraxsarco.com/resources/steam-engineering-tutorials.asp. Illustrations and text are copyright, remain the intellectual property of Spirax Sarco, and have been used with their kind permission

17

BUNKER FUEL FOR MARINE ENGINES

Intermittent combustion - fuel injectors In a diesel engine, the fuel is squirted from an injector into the cylinder in measured ‘doses’ at very high pressure, through a number of very small sharp-edged holes. The droplets produced are much smaller than those of the oil burner and the spray pattern is very different. The air for combustion is already in the cylinder and has been compressed to such a high temperature that the oil bursts into flame as soon as it is admitted though the holes. Over the last 100 years, the design of the fuel injectors (sometimes called fuel valves) has changed considerably. The changes have been dictated by the use of different fuels, the size of the cylinders, and the need to develop particular spray patterns, especially when there is more than one injector per cylinder. The standard of design and manufacture of fuel injectors is very high. The surface finish on the needle valve and the barrel is very fine. Even the acid from your fingers can affect the surface finish so they must be handled with extreme care during maintenance and adjustment.

18

Using fuel onboard

Chapter 3 - Using fuel onboard Diesel engines Diesel engines are not created equal – the most efficient are the slow speed engines and they are the ones that have the ability to burn residual fuels. When diesel engines first went to sea they burned ‘diesel oil’ which was a type of gasoil. This fuel was easy to handle, burned well and needed nothing more than filtration prior to use. The early diesel ships demonstrated that they could be reliable competitors for steam ships with the potential to feature simpler engine rooms with a smaller manpower burden. Diesel ships made slow but steady progress in terms of market share but their routine acceptance was hindered by the relatively high cost of their fuel. Whilst their efficiency was better than steam plant, they needed expensive diesel fuel and they were limited as to the total power per engine. .

After World War II, the technical research team at Shell conducted extensive research into the use of residual fuel in diesel engines. This demonstrated that with appropriate treatment, the slow speed diesel engines of the day could use residual fuel. Over the next 10 years, the two-stroke single acting slow speed engine became the prime mover of choice for powers up to about 12 megawatt (MW). The research showed that it was necessary to process the fuel to remove solid contaminants and water (which had been anticipated by others in the 1930s) and also to change the design of the fuel injection pumps and nozzles in order to get efficient ignition and good combustion. The earliest diesel engines used a variety of injection techniques but, by the 1940s, most used the technique of ‘solid injection’. The fuel is supplied to the fuel injector (sometimes called the fuel valve) at high pressure by a reciprocating pump (the injection pump). Once the pressure exceeds the opening pressure of the valve, the fuel passes though the injector into the cylinder as a very fine mist. Because the system is hydraulic, the injection starts almost as soon as the injection pump starts to discharge and stops as soon as the discharge ceases. The output of the engine is controlled by the amount of fuel delivered by the pump. The pumps and the injectors are pieces of precision engineering with very fine clearances (less than 10 microns). Some modern fuel injection systems operate at pressures up to 2,000 bar. The latest developments feature injection systems using ‘common rail’ pumps where the engine has a single high pressure supply to all injectors as opposed to a dedicated pump for each cylinder. The use of common rail systems, which started with high speed engines in the 1960s, has now encompassed the slow speed engine family because of the suitability of electronic control of the injection process, allowing the start of injection and pressure profile during the burn and

19

BUNKER FUEL FOR MARINE ENGINES

end of injection to be controlled independently per cylinder whilst the engine is running.

Delivery Valve Spring Delivery Valve

Inlet Port Rack

Slot Helix Plunger

Barrel

Spill port

Pinion

Control Sleeve Control Flange

Figure 13.  Fuel pump internal arrangement Diagram courtesy of Petrospot Ltd (www.petrospot.com)

The design of the nozzles allows the use of more than one injector per cylinder and the reduction of exhaust pollutants, especially nitrous oxide (NOx) .

20

Using fuel onboard

Solid Now used as standard Conventional fuel valve Sac volume 1690 mm3

Slide type fuel valve Sac volume 0 mm3

Figure 14.  Fuel valves for K98MC Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

As more attention has been given to exhaust gas emissions, designers have adapted the design of the tip of the injector to reduce the amount of ‘dead’ fuel left in the tip after the injector needle valve has closed (the end of injection). This has reduced the emissions of NOx and reduced the amount of visible smoke in the exhaust.

Pistons, piston rings, cylinder liners and exhaust valves These components are subject to the harshest physical conditions when the engine is running. The piston takes the full force of the expanding and burning gas. The upper surface of the piston (the piston crown operates at temperatures around 500°C) is cooled internally by the system lubricating oil. The cylinder liner contains the pressure and provides a smooth regular cylinder surface for the piston to move up and down. It also has to resist very high temperature especially in the upper third of its height. It is cooled by the jacket cooling water. The piston rings provide the seal between the piston and the cylinder liner. The rings sit in grooves cut into the side of the piston and have to be free to expand, contract and rotate in the groove at all times. The piston will have between

21

BUNKER FUEL FOR MARINE ENGINES

three and six piston rings, dependent on the design of the engine. The contact or wearing surfaces are the inside surface of the cylinder liner and the outside surface of the piston rings. This is lubricated with cylinder lubrication oil squirted into the liner while the engine is running by mechanical lubricator pumps driven by the engine. The engineer has to find a balance between too little cylinder oil and too much. And the required dosing rate varies with engine load and the sulphur content of the fuel. In addition to lubricating the ring surface, the cylinder lubricating oil has to neutralise any acid formed by the combustion of the sulphur in the fuel. For this reason, the cylinder lubricating oil is alkaline, and its alkalinity is described by its Total Base Number (TBN). On some ships, when the engine switches from a high sulphur to a low sulphur fuel oil, the cylinder lube oil is also switched to a less alkaline oil. The exhaust valve has to be able to withstand the high temperature of the exhaust, be resistant to corrosion and remain leak tight when closed (otherwise the engine will not be able to compress the air sufficiently to ignite the fuel when it is injected). All of these components can be adversely affected by poor quality fuel, poor combustion, poor ignition performance and inadequate maintenance.

Turbochargers Almost all marine diesel engines are fitted with turbochargers. The earliest use of turbochargers was in marine engines in the late 1920s, well before they became fashionable in smart European motor cars. The turbocharger is a gas turbine powered by the heat in the exhaust gas and driving an air compressor to permit a greater mass of air to fill the cylinder. This in turn permits a larger charge of fuel to be burned in each power stroke. The turbocharger (some engines have up to three) runs at high speed (4,000 rev/min) and discharges the air at up to 2.5 bar. It is very sensitive to fouling, so poor fuel or bad combustion will decrease the efficiency considerably. If the unit is fouled it pumps less air, the engine combustion deteriorates and the fouling increases. It is a process that increases until the engine can no longer function correctly. The act of compressing the air increases its temperature and, because the amount of fuel we can burn in the cylinder is governed by the mass of air in the cylinder (not the volume), it is more efficient to cool the air after the turbocharger before it enters the cylinder. This is done in the scavenge air coolers, sometimes called charge air coolers.

22

Using fuel onboard

Figure 15.  MAN Type TCR turbocharger Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

What is a ‘good’ fuel? To use a fuel successfully in a diesel engine, it must have some fundamental characteristics: •

It must be stable both in storage and treatment and should not contain any component that significantly impairs the ability of the treatment plant to process the fuel

•

It must not contain components which leave deposits that can affect the good operation of the fuel treatment and injection system

•

It must be capable of atomising in a consistent way, producing droplets of near uniform size (between 10 and 20 micron diameter)

•

It needs a predictable ignition and burning characteristic, especially with regard to pre-ignition, turbulent ignition and steady burning performance

•

It must burn completely before the commencement of the exhaust phase of the cycle

•

It should not contain corrosive constituents that exceed the resistance capability of the engine materials

•

It should not contain abrasive particles after treatment in quantities which exceed the engine builder’s requirements.

23

BUNKER FUEL FOR MARINE ENGINES

A fuel that meets all of the above will give a predictable and consistent power with minimal exhaust fouling, deposits and engine wear. Various measurable parameters will indicate if a fuel is likely to give problems in meeting the above requirements in service although some of them require interpretation dependent on the design of the engine being used and the method of fuel treatment and preparation employed. The indicative parameters for each condition are listed below: •

The pour point must be 100 lower than the normal bunker storage temperature. The TSA/TSP should be within ISO 8217 limits; the difference between this figure and the TSE should be less than 0.02. The density must be homogeneous throughout and within the limits of the separation equipment

•

The fuel should not contain polymers at a level which can obstruct the hot fuel filters or bio components which could leave deposits on fuel pumps or injectors

•

The injection temperature and pressure needed to meet the engine builder’s requirements should be within the design limits of the plant (heating temperature, maximum injection pressure)

•

The distillation curve should contain no unusual peaks or troughs, the rate of heat release should be consistent across the load range and the microturbine residue (MCR) and asphaltenes should be within normal limits. Research done by Shell highlights the interaction between the Calculated Carbon Aromaticity Index (CCAI) and ignition delay and ideally both parameters are needed to show good correlation between calculated and actual ignition performance. CCAI is derived from the relationship between viscosity and density, ignition delay from measurement in a test rig (like the Fuel Ignition Analyser (FIA)). The actual ignition delay is always less in real life, as the test rig has no ‘swirling’ motion to encourage ignition

•

The water content after treatment should be less than 0.5% to avoid disrupting combustion

•

The acid number should ideally be below 2 mg/KOH unless the origin of the fuel is naphthenic crude

•

The combined level of Aluminium and Silicon should not exceed 60 mg/kg and must not exceed 100 mg/kg.

Some of the above parameters are not part of routine fuel analysis but the wording of Clause 5 of ISO 8217 would routinely exclude their presence. In addition to the above, it must be remembered that the engine operating conditions must meet the engine builder’s requirements with regard to the inlet air conditions (temperature and pressure), the engine cooling requirements (temperatures and coolant flow for each cooling system fluid) and appropriate

24

Using fuel onboard

lubrication of all moving parts (cylinder oil, crankcase oil, valve and fuel pump operating oil). The inlet air conditions and surface temperature of cylinders and pistons are especially important to effective ignition and combustion.

Types of diesel engine Slow speed

Figure 16.  Wärtsilä slow speed engine RTFlex 62 Photograph courtesy of Wärtsilä Corporation (www.wartsila.com)

25

BUNKER FUEL FOR MARINE ENGINES

Figure 17.  Cross-section of MAN Type S35 slow speed engine Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

Slow speed engines (full speed from 60 rev/min up to 160 rev/min) are crosshead type engines and all operate on the two-stroke cycle. Until the late 1980s, the engine designs featured three distinct types:

26

Using fuel onboard

The loop scavenge (where the piston acts as both the inlet and the exhaust valve)

Exhaust out

Scavenge air in

Figure 18.  Loop scavenge Diagram courtesy of Petrospot Ltd (www.petrospot.com)

The cross flow scavenge (where the piston acts as both the inlet and the exhaust valve)

Exhaust outlet

Scavenge air inlet

Figure 19.  Cross scavenge Diagram courtesy of Petrospot Ltd (www.petrospot.com)

27

BUNKER FUEL FOR MARINE ENGINES

The uniflow scavenge – opposed piston engines with two pistons in each cylinder and engines with an exhaust valve (where the piston acts as the inlet valve and there is an exhaust valve situated in the cylinder cover of the engine). Exhaust valve Top Piston Exhaust out Exhaust out

Scavenge air in

Scavenge air in

Bottom Piston

Piston (acts as inlet valve)

Opposed Piston Uniflow

Conventional Uniflow

Figure 20.  Uniflow scavenge Diagram courtesy of Petrospot Ltd (www.petrospot.com)

Loop scavenge engines were mechanically simpler but could not achieve the efficiency of the uniflow scavenge engine (B&W) and once MAN stopped building its own slow speed engine design and Sulzer switched to uniflow scavenging, the loop scavenge engine is steadily disappearing from the seas. The opposed piston uniflow (Doxford) engines disappeared because of their inability to match the efficiency of those with a central exhaust valve. The two Wärtsilä engines shown above are very similar. However, the RT-Flex 62 has full electronic control of the injection and no traditional camshaft (an adaptation of the ‘common rail’ method). The RTA 50 has fuel pumps and exhaust valves operated by cams on a camshaft. Engines like the Wärtsilä RT-Flex feature electronic control of the fuel injection and electronic control of the timing of the exhaust valve operation which helps the engine to operate over a wider load range and with more efficient combustion than engines with mechanical control of these functions. MAN B&W ME-C engines use electronic control of injection but mechanical control over exhaust valve operation. The inherent advantage of slow speed engines is that the slow speed gives a longer time for ignition and full combustion of the fuel. The inherent disadvantage is size (especially height) and weight.

28

Using fuel onboard

A crosshead type engine has a seal (the piston rod seal) and barrier separating the cylinder space from the crank case of the engine, which helps to keep the system lubricating oil clean and free of the products of combustion. The space above this barrier, called the scavenge space, can collect used cylinder lubricating oil and some combustion products which, under adverse conditions, can catch fire (a scavenge fire). This is a serious problem usually linked to the condition of the piston rings and the quality of the ignition and combustion of the fuel. This type of engine has used residual fuels since the 1950s and engines built since 2000 are usually capable of burning ISO 8217 RMG and RMK grades, subject to the fuel handling and treatment plant fitted onboard. The advantage of the crosshead design is that the piston rod only has to move in the vertical plane, permitting the use of the seal mentioned above. This is a complex design problem, especially for engines where the stroke is very long. Without the use of the seal, it is not possible to use the piston as a means of closing off the incoming air to the cylinder space. The largest engines of this type are as follows: Height

14.3

metres (m)

Length

24.4

m

Width

4.4

m

Weight

1,975

metric tonnes (mt)

Power

72,240

kW

Number of cylinders

12

Speed

104

rev/min

Fuel consumption

305

mt/day

The smallest engines of this type are as follows: Height

7.5

m

Length

4.4

m

Width

2.2

m

Weight

81

mt

Power

4,350

kW

Number of cylinders

5

Speed

165

rev/min

Fuel consumption

16

mt/day

There are three main designs, Wärtsilä (Sulzer), MAN B&W and Mitsubishi, which are built by a large number of licensees worldwide.

29

BUNKER FUEL FOR MARINE ENGINES

Medium speed Medium speed engines (full speed from 450 rev/min up to 1,000 rev/min) are trunk piston type engines and operate on the four-stroke cycle. The engines have inlet valves and exhaust valves in the cylinder covers (usually two of each in each cylinder). Some modern medium speed engines feature electronic control of the fuel injection which helps the engine to operate over a wider load range and with more efficient combustion than engines with mechanical control of this function. The inherent advantage of medium speed engines is their moderate height and weight which makes them suitable for ships with restrictions on engine room size. The inherent disadvantage relative to the slow speed is that their higher speed gives a shorter time for ignition and full combustion of the fuel. The trunk piston engine has no barrier between the bottom of the cylinders and the crankcase, so cylinder lubricating oil and some products of combustion will find their way into the system oil, which places a greater burden on keeping the system lubricating oil in good condition. Most engines of this type are now suitable for burning grades RMG and RMK subject to the fuel handling and treatment plant fitted onboard. Many operators choose to restrict their engines to using distillate or heavy distillate grades to simplify operation onboard and reduce maintenance. This is especially true for engines with power of less than 2,000 kW and rotational speeds above 750 rev/ min.

Figure 21.  MAN 58/64 engine (cutaway) Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

30

Using fuel onboard

The largest engines of this type are as follows: Height

4.8

m

Length

14.1

m

Width

4.7

m

Weight

265

mt

Power

21,600

kW

Number of cylinders

18

Speed

514

rev/min

Fuel consumption

91

mt/day

The smallest engines of this type are as follows: Height

3.1

m

Length

4.2

m

Width

1.7

m

Weight

16

mt

Power

1,290

kW

Number of cylinders

6

Speed

1,000

rev/min

Fuel consumption

6

mt/day

There are a number of main designs, including Wärtsilä, MAN B&W and Mitsubishi, which are built by a large number of licensees worldwide.

31

BUNKER FUEL FOR MARINE ENGINES

High speed High speed engines (full speed from 1,200 rev/min up to 2,500 rev/min) are trunk piston type engines and operate on the four stroke cycle. The engines have inlet valves and exhaust valves in the cylinder covers (usually two of each in each cylinder). Some modern high speed engines feature electronic control of the fuel injection which helps the engine to operate over a wider load range and with more efficient combustion than engines with mechanical control of this function.

Figure 22.  Caterpillar C175-16 Photograph courtesy of Caterpillar Inc. (www.caterpillar.com)

The largest engines of this type are as follows: Height

2.13

m

Length

3.185

m

Width

2.14

m

Weight

8

mt

Power

2,350

kW

Number of cylinders

18

Speed

1,800

rev/min

Fuel consumption

10

mt/day

32

Using fuel onboard

The smallest engines of this type are as follows: Height

1.2

m

Length

1.4

m

Width

0.7

m

Weight

0.6

mt

Power

150

kW

Number of cylinders

4

Speed

1,800

rev/min

Fuel consumption

0.6

mt/day

Smaller high speed engines than those shown above can be found as prime movers for generators, pumps and other auxiliaries. Some, with only one or two cylinders, are designed for emergency service and are started by hand. These run at speeds below 1,000 rev/min.

Gas turbines Marine gas turbines are still a minority interest in the commercial sector. Most warships are powered by gas turbines, as well as some cruise ships and a few other merchant ships. This is likely to change in time, as gas turbines have considerable power to weight advantages. They are not as efficient as diesel engines and all of those currently in service at sea require distillate fuel. Marine gas turbines are not new; they were used in the 1950s and burned residual fuel but they were specially built and, compared to diesel engines, they were uneconomical. The modern gas turbines are adapted from aviation practice with very many shared components. The fuel is burned in cylindrical combustion chambers arranged around the outer circumference of the main turbine / compressor assembly. The fuel is sprayed in at relatively low pressure, ignited by a form of spark plug and then the flame is maintained by the continual flow of fuel and air. The fuel must be homogenous and free of water, and it is important that the mixing of the fuel spray and the swirling air from the compressor allows the fuel to burn completely in the combustor otherwise the gas turbine blades will be damaged by overheating.

33

BUNKER FUEL FOR MARINE ENGINES

Figure 23.  GE Marine LM2500 gas turbine Drawing courtesy of GE Marine, a division of GE Aviation, Cincinnati OH, USA

The largest units of this type are as follows: Height

3.99

m

Length

14.38

m

Width

3.14

m

Weight

24

mt

Power

30,000

kW

Speed

3,600

rev/min

Fuel consumption

156

mt/day

Fuel cells These devices allow the conversion of chemical energy directly to electrical energy. There are no moving parts. There are experimental versions of 20 kW up to 50kW currently in service, fuelled by methanol. The cell works by passing hydrogen through an electrolyte in a cell which has two electrodes which form the electrical source for an external circuit – a little like a battery. If the fuel is not hydrogen, then the hydrogen must be manufactured by a ‘reformer’ which makes the cell more complex. They are not new – they were invented in the 19th century – but it is only since the space industry needed a reliable source of electricity for manned spacecraft and satellites that the technology has developed. There are

34

Using fuel onboard

dozens in service at sea now, and they are being adopted for use in submarines as an alternative to nuclear propulsion.

Figure 24.  Wärtsilä WFC20 fuel cell Photograph courtesy of Wärtsilä Corporation (www.wartsila.com)

Norway has a hot gas fuel cell of 320 kW on the Viking Lady, an offshore support vessel, fuelled by methanol, installed as part of a research project. The unit is experimental and weighs 20 mt. It is a marinised version of units in service on land.

Shore power There are two circumstances where a vessel needs power provided from the shore. The first (and most common) is when a vessel is under repair, with the onboard systems shut down. All vessels have the ability to be connected to a source of electrical power from the shore. The vessel will have a connection box, usually placed in the emergency generator room, which allows flexible cables from the supply onshore to provide electricity at a voltage and frequency suitable for the vessel. This will then be switched in to the main electrical switchboard on the ship after the vessel’s own generators have been shut down. The connection is made with simple brass lugs on the cable ends bolted onto terminals inside the shore power connection box – very low tech! The shore power connection will be limited, providing just enough to maintain the ‘hotel services’ and to run sufficient electrical equipment in the engine room to facilitate the start up of the ship’s own generator system. The shore supply and the ship’s own generators are usually not connected.

Cold ironing A recent development is the concept of routine connection to shore power when alongside, working cargo, in a port. The purpose of this is to reduce the vessel

35

BUNKER FUEL FOR MARINE ENGINES

emissions to atmosphere in port whilst permitting normal operation of all onboard systems. This is often referred to as ‘cold ironing’. The equipment and arrangements are very different to conventional shore supply. The shore supply equipment is engineered to allow rapid connection to and disconnection from the ship. The cables are arranged for ease of handling and are able to deal with change of vessel draught due to cargo handling whilst still connected. The system capacity is much larger than the conventional shore power used for repair periods; the rating for some container ships can be in excess of 4 MW and for some cruise liners more than 12 MW. All of this requires considerable investment, especially by the port operator, as the supply must be electrically isolated from the main shore distribution system and ideally capable of delivering different voltages and frequencies as required by different ships. The ship will need a special connection box with standardised fittings to accept the plugs on the end of the shore power cables. There is a lot of work being done at the moment to develop this interface. There is now an international standard, ISO/IEC/IEEE/FDIS 80005-1, for interconnecting high voltage ship and shore systems.

Figure 25.  Cable connection plugs Photograph courtesy of Port Metro Vancouver (www.portmetrovancouver.com)

The plugs and sockets need to be weatherproof and capable of dealing with the high electrical current loads. The shore-based equipment may also feature special handling arrangements for the cables.

36

Using fuel onboard

Some container vessels are fitted with permanent cable reels at the main deck and the cables are lowered by the ship to the quayside where they are connected to a connection box on the quay or in a pit just below the surface of the quay.

Figure 26.  Cavotec ship-mounted cable reel

Figure 27.  Cavotec connection ‘pit’ on the quayside with cables connected Photographs courtesy of Cavotec SA (www.cavotec.com)

37

BUNKER FUEL FOR MARINE ENGINES

The prime targets for cold ironing are those vessels with a high load whilst alongside in port, such as container ships, cruise liners and LNG tankers. There has been considerable progress with container vessels and some with cruise liners in the United States and Scandinavia. All three ship types have considerable electrical power consumption in port so the scope for reducing emissions is worth pursuing. There is an additional potential with LNG tankers as some of them may be using methane to fuel their generators in port, and they may be able to generate electrical power with a lower level of emissions than the power station ashore. They will also have spare generating capacity so there are suggestions that they could feed power into the shore power grid. This has not yet been done, but is under investigation.

Figure 28.  LNG cold ironing illustration Illustration courtesy of ABB Marine (www.abb.com/marine)

Conventional tankers pose a problem because of the power needed to pump the cargo. Most large tankers (very large crude carriers (VLCC), Suezmax, long range (LR)) have steam-powered cargo pumps. The cost of converting to electrical pumps on existing ships is not manageable; not only would they need the motors and switchgear but also additional generating capacity onboard for ports without cold ironing. Some smaller tankers (medium range (MR) and general purpose (GP)) already have electrically-driven pumps or hydraulically-driven pumps with an electric motor-driven power pack. These vessels would be suitable for cold ironing.

38

Using fuel onboard

LPG tankers also have electrically-driven pumping systems so they would also be suitable. There is one final obstacle for all tankers. The entire installation will have to meet the requirements for safety and hazards from fire and explosion because of the potential of a flammable atmosphere.

Boilers Marine boilers have been around longer than steel ships! The process of burning fuel in a boiler is not dissimilar to burning fuel in a gas turbine, but the boiler furnace is much bigger, there is a greater tolerance of less than ideal conditions, and a marine boiler can burn old socks! The boilers of the 1920s, ‘30s, ‘40s and ‘50s used ‘pressure jet’ burners where the fuel passed through a single nozzle tip plate with a sharp-edged orifice that caused the fuel to break up into a fine mist. The flow of fuel was regulated by the pressure of the oil supply but was limited in the range of flow rate it could handle. When the boiler load was changed, it was necessary to reduce or increase the number of burners in use. In the 1960s, a new type of burner was introduced which mixed fuel and steam at the tip of the nozzle (steam atomisation) to allow the burner to produce a good spray over a much wider range of throughput thereby allowing the operators to adjust the load significantly without the need to shut off burners. Recently, the requirement in some ports to use distillate fuel has necessitated the use of different designs of burner with the steam and fuel pipes in the burner assembly being in parallel rather than concentric. As an alternative, compressed air can be used as the atomising medium in place of steam. The classic large boiler has a cylindrical pressure container at the bottom (the water drum) and a larger container at the top (the steam drum) connected by hundreds of steel tubes. The tubes surrounding the space where the fuel is burned (the furnace) are welded together on three sides to form a solid barrier full of water (the water wall) whilst the fourth side has gaps in between the tubes which allow the hot gas to pass out through banks of additional steel tubes (the generating bank). The water drum is full of water, the wall tubes and generating bank are full of water with steam bubbles, the steam drum is half full of water and the steam bubbles rise out of the water into the steam space. The fuel enters though burners usually positioned at the top of the furnace and the flame is completely contained within the furnace. There is a bank of tubes which is not connected to the water drum, only to the top of the steam drum. This is the superheater, which raises the temperature of the steam to well above its boiling temperature (superheating), and this increases the amount of work done in the turbines and the efficiency of the plant overall.

39

BUNKER FUEL FOR MARINE ENGINES

When the gas leaves the top of the boiler it is still very hot. It passes through further banks of tubes, called economisers, which add heat to the water being supplied to the boiler (feed water). The water used is of the highest purity and is recycled, being condensed after use in the turbines. This is called a closed feed system.

Figure 29.  Marine radiant boiler - 3D diagram

Propulsion Steam propulsion is almost exclusively limited to LNG tankers, where fuel oil at sea is supplemented with boil-off gas (BOG) from the cargo. This last bastion of the steam turbine is now being displaced by new designs of diesel engines that can burn methane gas. Propulsion boilers require complex automation and a very high load turn down so sophisticated steam atomising burners are the norm. The methane gas is injected into the swirling combustion air as it enters the furnace.

Cargo heating and pumping Almost all big tankers use steam to power turbine driven cargo pumps. The amount of power required makes it uneconomical to use alternative power sources. In addition, the boilers can provide steam for cargo heating and tank cleaning. Smaller tankers use electric or even diesel driven pumps for cargo work. Their

40

Using fuel onboard

cargo heating is either steam or ‘thermal oil’, which is just a lubricating oil with minimal additives. The thermal oil heaters use the same sort of burner technology as most package boilers, employing the old fashioned pressure jet burner or the rotating cup burner. These boilers and heaters do not need sophisticated load control and can be easily automated. Tanker auxiliary boilers are similar in design to propulsion boilers but with simpler systems and lower steam temperatures and pressures. On smaller ships there is no need for a significant degree of superheating. The burners are usually mounted in the roof of the furnace and the control system will adjust the fuel flow and water level control on a continuous basis.

Figure 30.  Auxiliary boiler - Aalborg Mission D The image is being used under permission by Alfa Laval Aalborg Mission D is a trademark owned by Alfa Laval Corporate AB Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com)

Fuel and accommodation heating On ships without a need for cargo heating this is by ‘packaged’ boilers producing relatively low pressure steam or supplied by thermal oil heaters. Thermal oil

41

BUNKER FUEL FOR MARINE ENGINES

heaters are very similar to packaged boilers but use thermal oil (almost the same as lubricating oil) instead of steam as the heating medium. On many small ships this service is provided by electric heating. Package boilers have a furnace surrounded by water tubes but do not have a conventional water drum or steam drum. The water drum is replaced with a circular steel pipe at the bottom that connects all the furnace tubes together at the bottom. The space above the furnace is a chamber to which all the tubes are connected and with large ducts running through to carry away the furnace exhaust to the funnel. This chamber has water (and steam bubbles) at the bottom and steam at the top. The oil burner is side mounted, near the bottom of the boiler and is a selfcontained unit; one motor drives both the fan and the oil pump. It will switch on and off automatically in order to keep the steam pressure within an acceptable range. It is usually for distillate fuel only but some package units can operate on residual fuel.

Figure 31.  Packaged boiler Aalborg OS-TCi The image is being used under permission by Alfa Laval Aalborg OS-TCi is a trademark owned by Alfa Laval Corporate AB Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com)

42

Using fuel onboard

Thermal oil heaters have a much smaller space in the top chamber as there is no need to separate steam from water. The whole thermal oil system is full of thermal oil and is circulated by pumps which move the hot oil to the heat exchangers around the ship and the cold oil back to the heater.

Incinerators Vessels will be fitted with incinerators to dispose of solid waste and fuel sludge. The incinerators use distillate fuel with pressure jet burners. If a ship cannot incinerate the waste, it must be retained onboard until it can be landed and disposed of ashore.

Figure 32.  Atlas incinerator - external Photograph courtesy of Atlas Incinerators A/S (www.atlasinc.dk)

Figure 33.  Atlas incinerator - cutaway diagram Photograph courtesy of Atlas Incinerators A/S (www.atlasinc.dk)

43

BUNKER FUEL FOR MARINE ENGINES

Inert gas generators In some tankers it is necessary to provide a blanket of inert gas above the cargo. This can be done using cleaned boiler exhaust or, especially with LPG tankers and some specialist product vessels, by producing a gas with a very low oxygen content in a special combustor. The fuel used is always distillate.

Figure 34.  Alfa Laval inert gas generator The image is being used under permission by Alfa Laval Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com)

44

Waste heat recovery

Chapter 4 - Waste heat recovery As can be seen from the diagram below (on the left hand side), 26% of the energy in the fuel goes straight up the funnel and is wasted. Over the years, ship designers have chipped into that waste, using some of it for onboard heating. As the cost of fuel has soared and the pressure on freight rates has increased, the efforts to win back more from the exhaust have increased and the very latest vessels have realised a massive reduction in heat lost in the exhaust. It must be remembered that this area of ship design is aimed directly at large slow speed engines, although there have been significant improvements with multi-engine medium speed installations, especially in passenger service (cruise liners).

Overall efficiency 49%

Overall efficiency 55%

Shaft power 49

Shaft power 48

Electrical power 5.5% Condenser 8.5%

Exhaust gas 26%

Exhaust gas 12.5%

Scavenge air cooling water 14%

Scavenge air cooling water 13%

Jacket water 6.5%

Jacket water 6.5%

Lubricating oil 4.5%

Lubricating oil 4.5%

Radiation 0.5%

Radiation 0.5% Fuel input 100%

Fuel input 100%

Sankey diagram showing gain in efficiency using waste heat recovery Compiled from data from a number of sources Figure 35.  Sankey diagram Diagram courtesy of Petrospot Ltd (www.petrospot.com)

45

BUNKER FUEL FOR MARINE ENGINES

The simplest systems have been in use for many years to provide heat for the heavy fuel plant and the domestic heating requirements. As the diesel engine installations reached powers of 15 MW, it became economically viable to generate electrical power onboard from the heat in the exhaust but, until recently, this was only effective near the top of the engine output curve. Using sophisticated design, very efficient turbines and modern control systems, it is now possible to realise some significant gains in fuel efficiency.

Waste heat simple plant layout The simplest systems (in use from the late 1970s) installed a waste heat exchanger in the exhaust uptake, feeding water to a steam boiler drum and providing steam to a turbo generator set. The boiler could be oil fired if required but normally the system would be self-sufficient when the main engine was running at sea. At about this time, great strides were being made in engine efficiency, so the amount of heat in the exhaust was decreasing and, unless the system could meet the normal seagoing electrical load, the system would cost too much to install to give a realistic pay back. Improvements in turbocharger design in the 1990s restored the balance (the exhaust gas after the turbocharger got hotter) and these systems found favour once more. However, much of the original market (tankers and bulk carriers) were being fitted with significantly lower engine power so the focus shifted to container vessels. Single-pressure exhaust gas economiser

Stream Heating

Electrical Consumers

steam turbine

G

Aux. engines

Turbo charger G

Main engine

G

Figure 36.  Simple waste heat recovery plant Diagram courtesy of Petrospot Ltd (www.petrospot.com)

46

Waste heat recovery

Waste heat complex plant layout Steam Heating

Exhaust gas economiser steam turbine

Electrical Consumers Exhaust Gas turbine

G Aux. engines G

Turbo chargers Motor/generator

G

M

G

Main engine

G

Figure 37.  Waste heat complex plant diagram Diagram courtesy of Petrospot Ltd (www.petrospot.com)

The complex system shown is that fitted to the latest Maersk container ships with huge 14 cylinder slow speed engines providing electrical power to the shipboard services at sea and with the ability to feed additional power (if available) back to the propeller via a shaft-mounted motor/generator unit. The efficiency of these units is dependent on keeping the exhaust gas waste heat unit free of fouling, which can be caused by poor combustion. The heating surfaces are periodically ‘swept clean’ by the use of air or steam soot blowers which pass high velocity air or steam over the heating surfaces. The system shown above takes the exhaust gas from the outlet of the turbocharger (at between 300°C and 400°C) and, after passing it over four stages of heat exchange in the waste heat unit, sends it up the funnel at less than 170°C. The steam turbine is fed with both high and low pressure steam and connected in tandem with an exhaust gas power turbine. The unit then drives an electrical power generator. The water feeding the waste heat unit is pre-heated by the cooling system of the main engine (the ‘jacket water cooling’) and by the air that has been compressed in the turbocharger (the ‘scavenge air cooler’). Nothing is wasted.

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BUNKER FUEL FOR MARINE ENGINES

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48

Refining and types of fuel

Chapter 5 - Refining and types of fuel The majority of fuels used at sea are the product of hydrocarbon refining crude oil. The basic tool is a still. The crude oil is heated until it boils and the vapour allowed to condense, with the condensate being captured at different temperatures.

Simple refining Crude oil is refined by distillation at atmospheric pressure and then separated into ‘fractions’. The crude is heated to over 350°C and the lighter fractions (the good stuff) evaporate and pass up a tower filled with trays. At each level different products condense and are drawn off at the side. The very lightest fractions do not condense, but pass out of the top for further treatment. These become the petroleum gases propane, butane and ethane. The trays collect the gasoline, kerosene and naphtha, leaving at the bottom of the tower the ‘atmospheric residue‘ from which we get residual fuel oil and bitumen.

Figure 38.  A simple refinery Diagram courtesy of Petrospot Ltd (www.petrospot.com)

49

BUNKER FUEL FOR MARINE ENGINES

Complex refining

Fuel Gas

Refinery Fuel

Amine Treating

Other Gases

H2S Gas Processing

Gas

H2

Gas

H2

H2 Isomerate Gas

H2 Reformate

Catalytic Reformer

Hydrotreater

Naphtha

Sulphur

H2S from Sour Water Stripper

Jet Fuel and/or Kerosene

Merox Treater

Kerosene

Gas Diesel Oil

H2

Hydrotreater

Diesel Oil

Hydrocracked Gasoline

Diesel Oil Gas i-Butane

Atmospheric

Butenes Pentenes

Gasoil

Gas Naphtha

H2

Fluid Catalytic Cracker (FCC)

Gas

FCC Feed Hydrotreater Light Vacuum

Vacuum Distillation

Atmospheric Bottoms

Gas Evacuated non-condensibles

Alkylate

Alkytation H2

Hydrotreater

FCC Gasoil

Gasoline Blending Pool

Gas H2 Jet Fuel

Hydrocracker

Atmospheric Distillation

Heavy

Oil

Gas

Isomerization Plant

Hydrotreater

Naphtha

Crude

LPG Butanes

Merox Treaters

Gas Light

Claus Sulphur Plant

FCC Gasoline

Fuel Oil

Gasoil

Heavy Vacuum Gasoil

Air

Asphalt Blowing

CO2

Asphalt Natural Gas Steam

Sour Waters H2

Hydrogen Synthesis

Steam

Sour Water Steam Stripper

H2S to Sulphur Plant Vacuum Residuum

Stripped Water

• Finished products are shown in blue • Many refineries also include vacuum residuum cokers • The ‘other gases’ entering the gas processing unit includes all the gas streams from the various process units

Figure 39.  Modern refinery process Diagram courtesy of: Petrospot Ltd (www.petrospot.com)

50

Refining and types of fuel

Modern refineries then further distil the atmospheric residue under a vacuum, evaporating even more of the so-called middle distillates (gasoil, kerosene and naphtha) which are passed into more sophisticated processes. This includes catalytic cracking, where the products are processed in the presence of a catalyst (an aluminium and silicon compound) to produce even more gasoline. The material at the bottom, ‘vacuum residue’, is broken down even further. We still get fuel oil and bitumen, but there is much less of it. The fuel oil is too thick and too dense to use ‘as is’ but has to be diluted to get to a product we can use on ships.

What is in the fuel (and why do we need to know)? Elements in the fuel Fuel oil contains the following elements which come from the crude oil. Some crude oils can contain sodium and some calcium. •

Hydrogen

•

Carbon

•

Sulphur

•

Vanadium

•

Sodium (from crude)

•

Nickel

•

Calcium (from crude)

Contaminants Fuel may also contain the following contaminants, which should not be there but have been picked up in the refinery process, storage or transportation. When the fuel comes out of the refinery process it is completely dry. There should be no water. •

Sodium (from salt water or from the refinery process)

•

Iron

•

Bottoms, sediment and water (BS & W), the sediments of storage and transportation

•

Water. Fresh water is benign in small quantities if distilled, but salt water can cause severe fouling

•

Aluminium and silicon. These are elements from the refinery catalyst. They are very hard and abrasive and can cause mechanical damage through abrasive wear to fuel pumps, piston rings and cylinder liners

•

Sodium. From salt water or from the refinery process

51

BUNKER FUEL FOR MARINE ENGINES

•

Iron. Usually rust from storage.

Adulterants Unscrupulous suppliers may add elements in order to dispose of them in the bunker pool. Waste lubricating oil was historically added as an ‘ecologically friendly’ way to dispose of it. This is now prohibited. Other chemical wastes cost a lot of money to dispose of properly. At times they have been illegally added to bunkers to avoid disposal costs. They are difficult to trace but, even in quite small quantities, can cause significant damage very quickly. Calcium, zinc, phosphorus (from lubricating oil). All three of these together are an indication of the presence of waste lube oils in the fuel. They may also carry quantities of iron. Strong acids are measured by a strong acid number (SAN). These are inorganic acids and are precluded by clause 5.1 in the ISO 8217 bunker quality specification. Some organic acids (from cleaning solvents and industrial processes). Their presence is usually detected by Fourier transform infrared (FTIR) spectroscopy screening. Note that many organic compounds are benign and many come from the refinery process. Another measure is total acid number (TAN) which is not in the international specification but is used by some oil companies as a method of internal quality control. At present, they work to a limit of 3 mg/KoH (potassium hydroxide) but it is likely that this control limit will be reduced. The growth of biofuels and their impact on the blending components used for marine fuel are encouraging the use of a different test method, finding the acid number (AN).

Physical parameters Most of the things we test for in analysis are physical properties. Viscosity is the runniness of the fuel which affects pumpability, injection and flow and which varies with temperature. When discussing viscosity it is important to relate the result of the test with the temperature at which the test is performed. Density is the heaviness of the fuel. This affects the ability to separate fuel from water and contributes to the energy content of the fuel. Total sediment is the quantity of insoluble materials in the fuel. Ash is the amount of material in the fuel that will not burn.

52

Refining and types of fuel

Calculated parameters CCAI / CII In the 1980s, oil companies looked for a way to quantify ignition qualities. It was known that there was a link between viscosity, density and ignition and two different calculations were established. The Calculated Carbon Aromaticity Index (CCAI) developed by Shell, and the Calculated Ignition Index (CII) developed by BP. The CCAI calculation is more widely used. As fuel production methods and fuel chemistry have changed in recent years, it is felt that the protection given by monitoring CCAI or CII levels is no longer sufficient and new techniques are being tried out. Both calculations require only that the density and the viscosity are known. FIA A fuel ignition analyser (FIA) is a pressurised container into which fuel is injected and various parameters recorded. This equipment reports the following parameters: •

Ignition delay – the time taken between the start of injection and the start of ignition under strictly controlled conditions

•

Rate of heat release (ROHR) – the rate heat is given off during combustion under strictly controlled conditions

•

Estimated Cetane Number (ECN) – an artificial number which can give guidance as to the ignition performance of a fuel.

Specific energy There is a widely accepted formula for calculating the specific energy in fuel. It requires the density, sulphur, water and ash to be known. The answer given is either gross specific energy (which takes into account the latent heat in any water) or net specific energy (which does not take account of the latent heat in any water). For diesel-engined ships, it is the net specific energy which is of interest.

Visual appearance For distillate fuels, some specifications require distillate diesel to be ‘bright and clear’. For all gasoil grades DMA and DMX, the appearance must be ‘visually clear’.

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BUNKER FUEL FOR MARINE ENGINES

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54

Quality standards and specifications

Chapter 6 - Quality standards and specifications The first recognised marine fuel standard was published by the British Standards (BS) organisation in 1982 as BS MA100. It worked in cooperation with the Congrès International des Machines á Combustion (CIMAC) and, as a member of the International Organization for Standardization (ISO), it adopted the ISO 8217 standard in full in 1989. There are two commonly used standards for marine fuels in use today, one published by the ISO and the other by the engine builders’ association, CIMAC. CIMAC, which had worked closely with BS in the late 1970s and early 1980s, released its own specification for fuel as delivered to ships in 1990. These organisations are well respected non-governmental organisations (NGO) with their standards created through discussion and consideration of evidence and experience. A number of the delegates to the respective working groups are common to both bodies so it is not surprising that there is a lot of common ground. The ISO standard is more readily accepted worldwide and is voted on by delegates from the participating national standards organisations.

ISO 8217 The current ISO standard is ISO 8217:2010 which is the fourth edition (see Appendix 2). It contains considerable changes from the preceding ISO 8217:2005, the third edition. Many suppliers still offer fuel according to the 2005 edition. It usually takes six months to a year before a new standard finds acceptance but, because of the large number of changes, the 2010 edition is taking longer to penetrate the market. Whilst the normal interval between issuing a revised ISO fuel standard is about nine years, the ISO was specifically asked by the IMO to update the standard by 2010 in order to assist in the regulation of marine fuel quality. It is this update which led to the inclusion of new parameters, a general tightening of restrictions and a reduction in the number of grades included. (Please refer to Appendix 2.)

CIMAC The CIMAC Recommendations regarding Fuel Quality for Diesel Engines is a technical paper re-issued from time to time rather than an international standard, but it does have the status of an international standard within the industry. CIMAC 2003 is almost identical to the ISO 8217 standard and uses the same grade descriptions without the prefix DM or RM. The CIMAC and ISO working groups work closely together and in many cases working group delegates are members of both bodies. The CIMAC organisation has the advantage of having a simpler

55

BUNKER FUEL FOR MARINE ENGINES

structure and a more direct focus on the machinery and the fuel. It claims it can respond to change more quickly than the ISO and, over the years, the CIMAC specification has been revised at least one or two years earlier than the ISO 8217 standard.

National specifications There are a number of nation states whose oil product standards are regulated by their governments and they frequently diverge from the international standard, especially with regard to the number of controlled parameters and test methods used. This can cause commercial complexities for fuel buyers and traders operating in those countries.

56

Blending

Chapter 7 - Blending Because the fuel produced in the refinery is almost never suitable for use onboard, it must be blended with other products (gasoil, cycle oil, etc.) before use. This is generally done at shore terminals, onboard bunker barges or, very occasionally, onboard the receiving vessel. There are three main types of blending as described below.

Batch This is the oldest and least sophisticated method and, in practice, it is the only one available to many ships if faced with a need to blend two products. The theory is simple: after assessing the analysis of each product and ensuring compatibility between the products, the ship must calculate the proportion of the blend and then mix the required volumes together. As long as the products are compatible and the mixture is effective, the blend will meet the requirement.

Splash This is the simplest (and least effective) method. The required volume of diluent (the smaller component of the blend) is added directly into a tank containing the base product. The resultant blend may be improved by circulation using pumps to circulate the blended product. It may also be improved by ‘sparging’, where air is bubbled though the resultant blend. This technique is use for barge-based blending in some ports.

In line This technique involves admixing the two blend components through a blender which mixes the two streams into a single outlet. Manual blenders rely on a fixed setting of the blend ratio and are often used onboard ships where the tolerance of the important resultant parameters (usually viscosity and density) are monitored and the flow ratio continually adjusted to get the correct output. Most blending units involve a static mixer. Where the resultant blend is required to meet commercial guarantees then sophisticated automatic blending units are employed.

57

BUNKER FUEL FOR MARINE ENGINES

Figure 40.  CBI blender Photograph courtesy of CBI Engineering (www.cbi.dk)

Manual blender The schematic below shows the simplest arrangement. In practice, commercial blending units are more sophisticated, adapting the valve opening to compensate for fluctuations in the pressure of the two product streams to maintain the required blending ratio.

Manual blender Manual blender

Component 1 Static mixing device

Blended product p Component 2

Figure 41.  Manual blender Diagram courtesy of Nigel Draffin

58

Blending

Automatic blender The automatic blender uses control systems to produce a blend which fulfils a predetermined limit on viscosity or density. They can be found in tank terminals, on some bunker barges and on a few ships which require more than one grade of residual fuel for different pieces of onboard equipment.

Automatic blender Automatic blender

Component 1 Static mixing device Blended product

Component 2 Blend  computer

Temperature  measurement Density  measurement Viscosity  measurement

Figure 42.  Automatic blender Diagram courtesy of Nigel Draffin

Stability All fuels are sold on the basis that they are a stable, homogeneous product. In the case of distillates, this is the normal state of affairs and the only exception is what is called oxidation stability. This is where the distillate shows an increased tendency to oxidisation, especially after prolonged storage. The situation with residual fuels is different. Residual fuels consist of different constituents from the crude and the refining processes, which vary in molecular weight. The heaviest are asphaltenes, the lightest are true liquid hydrocarbons. The asphaltenes are normally suspended in the resin phase, the maltene. Whilst they remain suspended, the fuel is stable and will not precipitate sludge. This ability to keep the asphaltenes ‘floating about’ is dependent on the aromatic nature of the rest of the constituents (resins and liquid hydrocarbons) called ‘maltene’. If the ability of the maltene to support the suspended asphaltenes (its peptising power) is disturbed, then the asphaltenes will ‘fall out ‘of the liquid, forming a significant quantity of thick sludge. It is the skill of the blender which provides confidence that fuel will remain stable. A number of tests have been developed

59

BUNKER FUEL FOR MARINE ENGINES

over the years to assist in blending stable residual fuels. Once asphaltenic sludge has started to precipitate, it cannot be stopped. It is not possible to add an aromatic component to reverse the process.

Comingling Problems with fuel stability come from the fact that two stable ‘on specification’ fuels may become unstable when mixed. This is because the peptising power of the mixed fuels is not enough to keep the asphaltenes in suspension. It is very unusual for any difficulty to arise if the blend ratio is less than 10:90. The risk is greatest when the ratio is 50:50. For this reason a blend stability test should always be performed before mixing fuels at a ratio of more than 10:90. If two fuels are mixed and the mixture is unstable then the likelihood of sludge formation is increased by heat and by mechanical stress – exactly the things that will be generated by passing the fuel through a separator.

60

Fuel storage and treatment systems onboard ship

Chapter 8 - Fuel storage and treatment systems onboard ship Layout Bunker loading manifold g

Service tank overflow

Main tank  1

Main tank  2

Settling  tank

Service  tank

Heater

Double  bottom bottom  tank 1

Double  bottom bottom  tank 2

To main  engine via  heaters and  filters

Transfer  pump Purifier

Figure 43.  Fuel system schematic diagram Diagram courtesy of Nigel Draffin Fuel cleaning system

Fuel conditioning system

4 4 3

1 2

8

5 7 6

2 19

17

16

20

10

6

3

18

21

Oil recovery and sludge treatment system

22

Main Engine

15

Legend 1. Settling tank 2. Separator feed pumps 3. Fuel oil pre-heaters 4. Centrifugal separators 5. Service tank 6. Fuel oil supply pumps 7. Main filter 8. Bypass filter 9. Flow meter 10. Mixing tube 11. Circulation pumps

12

15

11

13

FI

9

VI

11

12

12. Heaters 13. Viscosity transmitter 14. Duplex safety filter 15 Constant pressure valves 16. Sludge tank 17. Feed pump to sludge separator 18 Sludge heater 19. Sludge separator 20. Concentrated sludge tank 21. Recovered fuel oil tank 22. Bilge water tank

44.  Fuel oil treatment system Figure 3:1. Fuel Figure oil treatment system Source: CIMAC Recommendation No. 25 (2006). Copyright of CIMAC (www.cimac.com)

61

14

Auxiliary engine

BUNKER FUEL FOR MARINE ENGINES

Overflow pipe

To engines

Service Tank 12 hrs MCR

Settling tanks, 24 hrs MCR

Settling tank

Service tank

To engines

H.F.O. storage tank

H.F.O. Low Sulpur Tank

H.F.O. storage tank

F.O. heaters

Fuel oil purifier

Figure 45.  Simplified fuel piping diagram for double HFO settling and service tanks Diagram courtesy of Petrospot Ltd (www.petrospot.com))

Fuel storage Fuel storage tank design and construction on ships are controlled by the Safety of Life at Sea (SOLAS) international convention and by the requirements of the classification societies. Recent developments have addressed the issue of bunker tank location in order to limit the potential for oil pollution after a collision, and this will have considerable effect on the placement of bunker storage tanks on some classes of new ships. The rules on protective locations for bunker tanks are part of the MARPOL Annex 1 regulation 12.

Bunker storage tanks Historically, the placement of bunker storage tanks was not given particular priority by naval architects – the tanks often filled up void spaces in the design. As a consequence, many existing vessels have tanks located all over the place. The ideal situation is to have a reasonable number of storage tanks, sufficient to give plenty of fuel storage options without the need to comingle and to allow clear access for maintenance and cleaning. In practice, many ships are still being built with just two fuel oil storage tanks and one distillate storage tank. This causes considerable problems for operators trying to comply with sulphur regulations. An irregular tank cross-section hinders accurate level measurements and matters are made worse by pipelines, structures and intrusions into the tanks. There is always debate about the best design – low and wide versus tall and narrow.

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Fuel storage and treatment systems onboard ship

A low and wide tank is better for settling but much worse for sediment and water being stirred up by ship movement in a seaway. Low and wide tanks were favoured in the double bottoms of ships (passenger ships, bulk carriers, reefer ships). Tall and narrow tanks were popular on container tonnage in the space either side of the container cells. These examples are of ship types with a significant number of storage tanks. Tankers and many bulk carriers have storage tanks either side of the engine room, although these are the ship types with fewest tanks. An ideal arrangement would feature at least five fuel oil storage tanks and at least two distillate storage tanks. It would be prudent to ensure that the ship systems should be able to use any of the tanks for storing any of the required products although, as yet, this is not common.

Figure 46.  Container vessel bunker tank locations Diagram courtesy of Petrospot Ltd (www.petrospot.com))

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BUNKER FUEL FOR MARINE ENGINES

HFO Storage Tanks

HFO Filling Connection P&S

HFO Filling Line

MDO Filling Line

DO Service Tank DO Storage Tank

HFO Storage Tanks

HFO Settling HFO Service

Figure 47.  Tanker bunker tank locations Diagram courtesy of Petrospot Ltd (www.petrospot.com))

Figure 48.  General cargo/reefer tank locations Diagram courtesy of Petrospot Ltd (www.petrospot.com))

64

MDO Filling Connection P&S

Fuel storage and treatment systems onboard ship

Settling tanks Many of the previous comments on storage tanks apply to settling tank design and the general solution has been to use a tall and narrow design. Unlike storage tanks, most authorities recommend a sloping bottom to the tank to allow settled water and solids to be readily drained from the tank. Gravity settling is enhanced by maintaining the tank at a higher temperature. The settling tank will have a high level suction for normal use, a low suction for use when the tank level is low, and a drain cock for draining water and solids. In order to assist with change over between different sulphur fuels (Emission Control Area (ECA) and non-ECA), some vessels are now equipped with two settling tanks. For ships with boiler plant, the boiler fuel pumps can be supplied directly from the settling tank as boiler fuel. 5 6

Legend

3 4

7

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

Valve manifold Transfer pump level controlled High level switch Low level switch Overflow pipe from service tank Re-circulation pipe from separators Temperature controlled heating coil Pump suction - high level Pump suction - low level Water drain To engine and transfer Pump strainer - suction side Separator feed pump No-return valve Stand-by pump-set (option)

15 8 9 10

2

11

12

13

14

1

Figure 3:2

Settling tank a fuel treatment system Figurein49.  Settling tank diagram Source: CIMAC Recommendation No. 25 (2006). Copyright of CIMAC (www.cimac.com)

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BUNKER FUEL FOR MARINE ENGINES

Service tanks The service tank is called either the day tank or daily use tank, which describes its function perfectly. The fuel in the service tank has been settled and purified. All that remains is for it to be passed though the main fuel heaters prior to injection to the engine.

Sludge tanks There will be tank storage for the sludge produced at the separators and the filters. The save-alls and drip trays which catch any spillage from the fuel treatment and burning equipment are also arranged to drain to these tanks. On some ships there is a waste oil recovery plant to recycle some of this by extracting usable oil but most of it will either be burned in an incinerator or landed ashore to approved collection services.

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Fuel treatment

Chapter 9 - Fuel treatment Separators One of the fundamental tasks of the fuel treatment plant on a ship is to separate solids from the liquid fuel and separate water from the fuel. The principal equipment for this is the centrifugal separator. The fuel is rotated at high speed (5,000 rev/ min to 6,000 rev/min) in a steel bowl. The design of the internals permits the separation of water from the fuel and separation of approximately 80% of the solids. The first distinction is between a purifier (which allows for continuous discharge of both clean fuel oil and water and retains solids inside the bowl). The second type is the clarifier, which has only an oil discharge and retains both water and solids in the bowl. The only difference between the two is in the arrangement of the ‘gravity disc’ or ‘dam ring’ at the top of the bowl assembly. This functions as a spill way or dam to maintain the required head of water and can be best visualised by looking at a cross-section of half of the separator bowl lying on its side. In this example, the only separating force is gravity. In the machines used onboard, because they rotate at such high speed (more than 6,000 rev/min), the centrifugal force provides a separating effect much greater than gravity alone. This example shows a trough with baffles and a dam to control the interface. Dirty oil in

Figure 50.  Separating trough with baffles Diagram courtesy of Petrospot Ltd (www.petrospot.com)

67

Clean oil out

Water out Dam

Interface between the oil and the water The interface is adjusted by the dam according to the density difference between oil and water.

BUNKER FUEL FOR MARINE ENGINES

If you now imagine the trough rotated to the vertical and to be in the form of a bowl – spinning with the centrifugal force acting on the fluid – you should start to get the idea. Dirty oil in

Clean oil out

Clean oil out

Water out

Water out Gravity disc

Oil / water Interface

Oil / water Interface

Figure 51.  Centrifugal separating bowl Diagram courtesy of Petrospot Ltd (www.petrospot.com))

The bowl is filled with a series of conical discs which channel the oil up through the machine, collecting the water and solids on their surface and returning them to the bottom (or the outside for the machine when vertically mounted on the ship). Flow between discs

5000 g

Solids

Liquid

0.5 mm

Caulk(s) 0.5 - 0.8 mm

The disc-stack

Figure 52.  Purifier bowl and disc-stack Diagram courtesy of Petrospot Ltd (www.petrospot.com))

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Fuel treatment

Vessels built in the 1950s and early 1960s would have two machines and would run them as purifier and clarifier in series, with both machines being shut down for manual cleaning, typically every four hours. In the following diagrams, the ‘light phase’ is the fuel oil and the ‘heavy phase’ is the water. inlet light phase heavy phase

sludge

Figure 53.  Purifier Diagram courtesy of Petrospot Ltd (www.petrospot.com))

inlet light phase heavy phase

sludge

Figure 54.  Clarifier Diagram courtesy of Petrospot Ltd (www.petrospot.com))

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BUNKER FUEL FOR MARINE ENGINES

By the late 1950s, designs were appearing which allowed the operation to be suspended for a couple of minutes and the bowl opened remotely to discharge the retained contents into a sludge tank. The bowl was designed in the form of two conical cylinders, where the sludge and solids collect at the point where the cylinders meet. The bowl opens by allowing the lower cylinder to drop down by a few millimetres, permitting the solid sludge to be ejected by centrifugal force. dirty oil clean oil water

sludge

Sludge ports opened by moving bottom part of bowl.

Figure 55.  Automatic desludging purifier Diagram courtesy of Petrospot Ltd (www.petrospot.com)

These later units were operated either by manual control of the desludge or by an automatic timer. The opening and closing of the bowl is effected by hydraulic means. The critical requirement for operating any of the above as a purifier is the maintenance of a sufficient difference between the density of the oil and the density of the water. The position of the interface has to be inside the outer edge of the disc stack to keep the oil/water hydrostatic balance, but if it comes too close to the centre, the effect on purifier efficiency is drastic.

70

Fuel treatment Oil inlet Clean oil outlet Water outlet

Gravity disc

Disc stack Top disc Interface

Interface

CORRECT

INCORRECT

Figure 56.  Conventional separator interface Diagram courtesy of Petrospot Ltd (www.petrospot.com))

A 1°C drop (from the optimum of 98°C) moves the interface towards the centre by 40 mm and will reduce the efficiency by more than 20%. With all conventional purifiers, the machine is started with the bowl full of water. Once the oil starts to flow in, it displaces the water from the clean oil outlet until it reaches a balance point at which time the oil will start to come out of the clean oil outlet. Interface displacement per °C 40

mm/deg.C

35 30 25 20 15 10 5 0 840

860

880

900

910

920

930

940

950

960

970

980

990

Fuel density at 15 °C, kg/m³ Figure 57.  Oil/water interface temperature sensitivity Diagram courtesy of Petrospot Ltd (www.petrospot.com)

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BUNKER FUEL FOR MARINE ENGINES

Purifiers Modern purifiers are closer to a fully automated clarifier than a purifier. They do not have a free water outlet, but measure the separator performance and then allow the release of water when the water capacity of the bowl is nearing full. This removes the need for the balanced oil/water interface and allows the machines to treat oil with a density greater than 991 kg/m³.

Figure 58.  Westfalia separator Diagram courtesy of GEA Westfalia Separator Group (www.westfalia-separator.com)

Most manufacturers will guarantee performance (under controlled conditions) with fuels up to 1010 kg/ m³ and the machines are more tolerant of temperature fluctuations.

Clarifiers A clarifier is a traditional separator which has the water outlet at the top of the bowl closed off. It is intended for secondary separation of solid materials after the use of a purifier. It cannot handle significant quantities of water. If it is an automatic desludging type, it can deal with small quantities of water by increasing the frequency of desludging, as long as the separated water in the bowl space does not spill over into the clean oil outlet.

Decanters This is a pre-treatment device, used before the conventional separators.

72

Fuel treatment

The drum is mounted horizontally; the large diameter end, where most separation takes place, is called the ‘pond’, the narrow conical end is called the ‘beach’. The purpose of the screw is to act as a plough, pushing the separated solids towards the beach prior to discharge as solid waste either for incineration or landing ashore. These units are also used on some ships to separate liquid from solid sludge from the contents of the sludge tank, after discharge from the purifier sludge outlet. Screw conveyor Motor

Bowl

Oil feed pipe

Slurry (feed liquid)

Differential gear Main bearing

Beach zone

Vane stack

Main bearing

Clarified liquid

Dehydrated solids (sludge)

Figure 59.  Mitsubishi Vane Decanter Centrifuge Diagram courtesy of Mitsubishi Kakoki Kaisha, Ltd (www.kakoki.co.jp/english/)

The purpose of a decanter is to remove significant quantities of solids from fuel oil. The bowl spins at very high speed and its internals, a large Archimedian screw counter, rotates at a much slower speed pushing the solids towards the conical end of the unit. They were fitted to a number of ships in the 1990s but seem to have fallen out of favour recently.

Homogenisers A homogeniser is a mechanical mill which, it is claimed, will reduce fuel consumption by increasing combustion efficiency and will also impact NOx and PM emissions. They have been used at sea with varying success since 1985 although the Marintek study of 2002 was unable to show a statistically significant benefit. One area where they can have an impact is handling high asphaltenes content fuels; another is the reduction of sludge.

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BUNKER FUEL FOR MARINE ENGINES

Figure 60.  Droplet distribution Courtesy of JOWA Technology (www.jowa.com)

Figure 61.  JOWA Homogeniser Courtesy of JOWA Technology (www.jowa.com)

The action of the unit breaks up the large asphaltenes particles and it is claimed that this reduces the amount shed as sludge and improves combustion.

74

Fuel treatment From centrifuge Aut. de-aerating valve

Diesel oil service tank

Heavy fuel oil service tank

Venting box

Full flow filter

Supply pumps

Circulating pumps

Homogenizer

Pre-heater

Fuel oil drain tank

Fresh water supply

Figure 62.  Pressurised fuel oil system with homogeniser Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

There are strong opinions both for and against the use of homogenisers, and no agreement as to whether they affect the efficiency of separators if placed before them in the fuel oil system. However, there are at least six separate types in service and they are found on a significant minority of ships. Homogenisers are also used with the creation of water/fuel emulsions for the purpose of reducing NOx. This technique was initially used experimentally to improve fuel efficiency in the 1980s but has now found favour as a technique to reduce NOx.

Blenders Blenders are devices for mixing two different fuel product streams to produce a blend which meets the needs of the machinery. The units found ashore or on bunker barges can be very sophisticated, whilst those used onboard ship tend to be very simple. They were used on ships where the generator engines ran on a lighter grade of residual fuel oil than the main engine. Their use has fallen out of favour in recent years.

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BUNKER FUEL FOR MARINE ENGINES

Static mixers These are specially designed fittings in a pipeline (usually downstream of an in line blending unit) to ensure thorough mixing of the blend components. They rely on a minimum flow rate to achieve good mixing.

Cold filters So called ‘cold fuel filters’ are fitted in the fuel treatment system before the fuel transfer pump in order to trap solids which might damage the pump internals. For the fuel system of a typical merchant vessel, the size of the openings in the filter will be about 2 mm to 10 mm dependent on the flow rates involved and the type of fuel. The filter type is usually a basket filter with two chambers; one in use and the other on standby. Cleaning is performed manually and is labour intensive. Normal use will only require the filter to be cleaned every month unless there are problems with the fuel. The filter must be taken out of service and drained before being cleaned.

Figure 63.  Cold filter Diagram courtesy of Eaton Corporation (www.eaton.com)

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Fuel treatment

Hot filters The ‘hot fuel filters’ are fitted after the fuel oil heaters and before the engine. The filter elements have openings of between 10 μm and 50 μm, giving an effective particle limit of 5 μm up to 30 μm dependent on engine design requirements.

Self-cleaning filters Most hot filters are of the ‘self-cleaning’ or ‘back-flushing’ type, with a number of parallel filtration elements, one of which is cleaned by the flow of the hot oil flowing into a sludge tank, whilst all the other elements filter the oil going to the engine. The unit will automatically switch round the elements one after another so that they all get cleaned. The frequency of back-flushing is determined by the speed at which the filter pressure differential increases, so the dirtier the oil, the more frequent the back flush process.

Figure 64.  Automatic fuel oil filter with electrical motor The image is being used under permission by Alfa Laval Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com))

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BUNKER FUEL FOR MARINE ENGINES

Figure 65.  Fully assembled filter showing full-flow and diversion chamber filter elements and electric motor The image is being used under permission by Alfa Laval Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com)

Full flow filters An alternative to self-cleaning filters are ‘full flow’ filters containing consumable filter elements which carry the full flow of oil though the element. These filters are physically much larger. The life of the elements is about two months after which time they are manually exchanged. It is claimed that full flow filters can work down to 2 μm and remove the pressure on efficiency from the purifiers. The disadvantage is the manual labour involved in cleaning and exchanging the filter elements. There is also the cost of disposal of used filter elements. Full flow filters are the norm for high speed engines and engines running only on distillate fuels.

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Fuel heaters

Chapter 10 - Fuel heaters Fuel heaters are required to maintain the temperature in storage, settling and service tanks, and to heat the oil before the separators and to before injection at the engine. When using residual fuels, the temperature in the storage tanks must be maintained at a temperature high enough to permit efficient pumping by the fuel transfer system and always above the pour point of the fuel. For most ships this will be about 40°C. The fuel in the settling tanks will usually be maintained at a higher temperature as this will aid gravity separation of water and solids in the settling tank. For most ships this will be about 60°C. The fuel must be heated before entering the separators to a temperature of 98°C. This is the design temperature; it ensures correct positioning of the interface in conventional separators and is not so high that any water will start to boil. The service tank will normally be maintained at about 80°C-85°C but the inflow of oil from the separators will need to have heating arrangements in case the separators are not in use. The fuel leaving the service tank has to be heated to the appropriate temperature in order to deliver the fuel to the injectors at a viscosity between 10 mm/s2 cSt and 15 mm/s2 cSt for correct injection. On a steam ship, the fuel to the boiler burners will not need so much heating, the normal burner viscosity requirement being about 30 mm/s2 - 50 mm/s2. The methods of heating are described below.

Steam heating This is the most common heating medium. In the fuel tanks, there is a system of coiled pipes (heating coils). The steam is admitted to the coils and as the heat is transferred to the oil though the pipe walls, the steam will condense and the coil outlet will be distilled water. The coil outlet has ‘stem traps’ which ensure that only condensate can leave the coils. If the heating fluid is allowed to escape as steam, then the proper transfer of heat will not be achieved and energy will be wasted. In the fuel heaters, the heat transfer is either though pipes (a shell and tube heat exchanger) or across large transfer surfaces that have fuel on one side and steam on the other side (plate heat exchangers) .

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BUNKER FUEL FOR MARINE ENGINES

Figure 66.  Alfa Laval Aalborg MX shell and tube heat exchanger for ships The image is being used under permission by Alfa Laval Alfa Laval Aalborg MX is a trademark owned by Alfa Laval Corporate AB Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com))

In the shell and tube heat exchanger shown above, the fuel transits from right to left. The steam enters at the top flange on the left and the condensed steam leaves from the outlet at the bottom right. One potential risk with steam heaters is local overheating and deposition of carbon on the surface of the tubes.

Figure 67.  Shell and tube heat exchanger Diagram courtesy of Petrospot Ltd (www.petrospot.com)

80

Fuel heaters

Figure 68.  Plate heat exchanger (Alfa Laval) The image is being used under permission by Alfa Laval Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com))

Figure 69.  Flow principle of a plate heat exchanger The image is being used under permission by Alfa Laval Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com)

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BUNKER FUEL FOR MARINE ENGINES

In both cases, the outlet of the heating medium is fitted with steam traps to ensure full transfer of the heat from steam to fuel.

Thermal oil heating On ships without a steam supply then the next most common transfer fluid is thermal oil. This is a very basic lubricating oil with almost no additives. It will be heated in a thermal oil heater, which usually uses an oil burner to supply the heat, or it can be heated in a heat exchanger which takes heat from the engine exhaust.

Electric heating The simplest form of heating is provided by electric heaters submerged in the oil. Overall energy costs mean that this is more suited to smaller vessels where the complexity of steam or thermal oil systems is inappropriate. The heating elements need to be kept free of deposits to maintain efficiency. Unlike heating coils (stem or thermal oil), the heat is not as widely distributed in the tanks and this means that electric heating is most common on smaller ships.

Figure 70.  VESTA EH electric heater The image is being used under permission by Alfa Laval VESTA EH is a trademark owned by Alfa Laval Corporate AB Alfa Laval is a trademark registered and owned by Alfa Laval Corporate AB (www.alfalaval.com)

Temperature control Fuel tank heating is temperature controlled, either fully or partially automatically. The control systems used are normally very simple. The heating of fuel entering the purifiers is also temperature controlled but with a more sophisticated control system to cope with variations in flow rate and inlet temperature.

82

Fuel heaters

Viscosity control The fuel from the service tank to the engine is almost always controlled on viscosity rather than temperature. The viscosity controller is set at the desired injection viscosity (usually between 10 cSt and 15 cSt) and the controller adjusts the amount of heat to maintain this. The fuel is pumped through a small diameter tube and the pressure drop across the tube is a function of the viscosity. The pump and capillary tube only carry a small proportion of the total fuel flow to the engine. Signal to Heater Controls

Differential Pressure Transmitter Local Thermometer

Capillary tube

Gear Pump

Fuel Inlet Figure 71.  VAF Viscotherm Diagram courtesy of Petrospot Ltd (www.petrospot.com)

Fuel chillers With the introduction of specific rules on using fuel with sulphur below 0.1% in some coastal areas, there has been greater attention paid to the effect of using very low sulphur distillate in engines designed for use with residual fuel. Manufacturers have become concerned about the low viscosity of these distillates and have re-stated their criteria for minimum viscosity and minimum lubricity. The viscosity limit is usually between 2.5 cSt and 3 cSt at the engine, dependent on manufacturer and engine type. This is frequently lower than the viscosity of the distillate supplied so in order to meet the manufacturer’s limits the fuel has to be cooled on its way to the engine. In order to handle some distillates, a cooler

83

BUNKER FUEL FOR MARINE ENGINES

using salt water might not be sufficient. In such cases, a chiller unit is used to refrigerate the cooling medium. This will permit operation on distillates with a viscosity of 2 cSt at 40°C in areas of high sea water temperatures.

Figure 72.  Location of gas oil cooling system Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

Figure 73.  Components of gas oil chiller system Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

As there may be times when the gasoil has to be cooled to below 15°C, care should be taken to ensure that the pour point, cold filter plugging point (CFPP) and cloud point are not reached.

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Pumps

Chapter 11 - Pumps Fuel system pumps are used to transfer fuel between tanks, to feed fuel to the purifiers and to feed fuel into the pressurised systems for the main engine or the boilers.

Centrifugal Centrifugal pumps are seldom used in fuel systems although they are used in some systems for distillate fuels. In the example shown, the fluid enters the pump suction on the right hand side and is expelled from the discharge at the top. The main limitation of this type of pump is the viscosity of the fluid (it is not normally used for fuel oil except as a cargo pump on oil tankers) and, for a single stage pump, the discharge pressure is limited.

Figure 74.  C2G centrifugal pump Photograph courtesy of Wärtsilä Hamworthy Limited (www.hamworthy.com)

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BUNKER FUEL FOR MARINE ENGINES

Figure 75.  Centrifugal pumps in engine room Photograph courtesy of Wärtsilä Hamworthy Limited (www.hamworthy.com)

The pump impeller imparts a rotating motion to the fluid inside the impeller chamber and this rotation produces a force that propels the fluid to the outer circumference of the pump chamber. One advantage of the centrifugal pump is that it is relatively insensitive to fluids with some solids and abrasive particles. These pumps are used for the transfer of distillate fuels, for all cooling water, ballast and firefighting systems and other duties requiring a reasonable high flow rate but with a relatively low discharge pressure. If a high discharge pressure is needed (to feed water to boilers), the pumps are ‘multi-stage’ with as many as four impellers all on the same shaft, the discharge of the first stage feeding the suction of the second stage and so on.

Positive displacement Most fuel pumps in marine systems are ‘positive displacement’ pumps. The most common types seen in fuel systems are gear pumps, lobe pumps and scroll pumps. The advantage of these pumps is their ability to produce a high discharge pressure. They are used to transfer the fuel from storage tanks to the settling tank, to feed the fuel to the separators, to supply fuel from the service tank to the engine fuel system and to pump the fuel at very high pressure to the injectors of the diesel engine.

86

Pumps

Positive displacement pumps are also used for hydraulic power services onboard (steering gear, lubrication oil systems, winches and cranes, as well as the power for hydraulic cargo pumps on some tankers).

Figure 76.  Gear pump Diagram courtesy of Petrospot Ltd (www.petrospot.com)

Gear pump In a gear pump the two interlocked gears rotate in a casing and fluid is trapped in the spaces between the gear teeth. These pumps are sensitive to solids and abrasive fluids. They can produce quitePump high discharge pressures. Lobe Discharge

Vane

Suction Figure 77.  Lobe pump Diagram courtesy of Petrospot Ltd (www.petrospot.com)

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BUNKER FUEL FOR MARINE ENGINES

Lobe pump This pump type is similar to the gear pump and has the additional advantage that because the chamber spaces are larger than those on a gear pump, there is less milling and risk of emulsifying water in oil mixtures. External Seal Chamber Return Line

Inlet

Outlet Precision Ground & Hardened Idler Rotors

(6D and 12D series pumps only) *3D series pumps utilize an internal seal chamber return

External Ball Bearing Thrust Plate

Balance Cup

Precision Ground and Hardened Power Rotor

Replaceable Rotor Housing

Balance Piston

Figure 78.  IMO screw pump Diagram courtesy of Colfax Fluid Handling (www.colfaxcorp.com)

Figure 79.  Screw pump 3 rotors Diagram courtesy of Colfax Fluid Handling (www.colfaxcorp.com)

88

Mechanical Seal

Pumps

In this type, the interlocking screws form the seal and the fluid is driven along the periphery of the pump chamber. This type of pump produces the least amount of fluctuations in discharge pressure when compared to other positive displacement pumps. The three rotor pumps are popular for fuel oil supply, lubrication oil service and hydraulic system service. A very good description of all types of positive displacement pumps is available at the following website: www.imopump.com/tech.htm under Rotary Pump Handbook.

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BUNKER FUEL FOR MARINE ENGINES

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90

Measurement

Chapter 12 - Measurement Level Most routine tank levels onboard a ship are indicated on mechanical or electronic read-outs from level measurement sensors. These are either in the engine control room or local to the tank. These gauges are used for operational measurement rather than ‘custody transfer’ and may only have limited accuracy. The majority of these gauges will be ‘hydrostatic’, measuring the head pressure created by the fluid in the tank. Where there is a need for accurate level measurement, the preferred method is by steel tape measurement and the use of calibration tables to convert the level indicated into quantity. Some modern vessels have sophisticated remote gauging which may have accuracy approaching the standard required for ‘custody transfer’ but this will not be sufficient for proof of delivered quantity.

Rate of flow meters Flow meters are used onboard to monitor the consumption of fuel and other process fluids. The use of meters to indicate instantaneous flow helps the engineers to operate the plant and adjust the process onboard according to flow rate. Most of them only indicate an instantaneous snapshot of the rate of flow, however there are two specific examples where flow meters are integrated over time which gives the ability to totalise flow.

Volume Volume flow meters are used onboard for distillates, water and heavy fuel. The meters used are seldom temperature compensated and rarely have any air separation equipment. For this reason, they are not appropriate for custody transfer. The meters used on residual fuel are generally of the oval gear type; accurate and reliable but very expensive. When used for measuring propulsion fuel with diesel engines, two meters per system are required; one to measure the flow to the engine and another to record the fuel return from the engine fuel pumps.

Mass Recent work by shipping giant A.P. Møller and others has seen the installation of mass flow meters onboard ship as a custody control measure for bunkering.

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BUNKER FUEL FOR MARINE ENGINES

Mass flow meters work on the principle of Coriolis forces and give a reliable and reasonable accurate measure of the mass flow though the meter, permitting integration to provide total mass received, giving a continuous reading of the density and an indication of the amount of gas or vapour entrained with the fuel. The accuracy is typically within 0.25%, decreasing to about 3% when the fuel is full of entrained air. This gives a typical accuracy over the whole of the bunker delivery of about 0.5% of mass delivered. Current projects are intended to prove the technology – with product being measured by meters on the barge and the receiving ship. It is likely that this technology will see increasing application over time although it will be some time before it is a routine fitting on bunker vessels. It is a very expensive solution for fitting to the receiving vessel.

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Sensitivity to fuel qualities

Chapter 13 - Sensitivity to fuel qualities Storage A fuel should remain homogeneous in storage onboard. In routine storage, there will be some settling out of solids and water. The water and some solids can be removed by regular manual draining. The main problems likely to show up in storage are as follows.

Stratification If a fuel has been improperly blended, especially where the blend components have not been carefully selected, the fuel components will tend to return to their original state. At worst, this can be a layer of high density residue, a layer of moderate density lighter viscosity residual fuel and a layer of low density low viscosity diluent at the top. The impact can be reduced by circulation (done in shore tanks by using a mechanical agitator), and the motion of a vessel in a seaway will help to keep the product mixed.

Sludge deposition Fuel with a high total sediment will deposit sludge. If the fuel is an unstable blend, where the total sediment after ageing (Total Sediment Potential (TSP) or Total Sediment Accelerated (TSA)) is higher than the Total Sediment Existent (TSE), then the fuel will release asphaltenic sludge in response to thermal or mechanical stress. This can happen in the storage or settling tanks, although not to the same degree as at the separators.

Wax deposition A waxy fuel, if not stored well above its pour point, will allow the wax in the fuel to form crystals and deposit ‘pillows’ of wax in the storage tanks. Once the wax has separated from the fuel it cannot be recombined.

Accumulation of solid debris on the tank bottom The majority of solids that settle out in storage tanks remain in the tanks until mechanically cleaned out. In the past this was done once every few years (every four or five years). Current practice is to leave the solids in the tank unless they are causing operational problems. Some authorities believe that this debris can become disturbed in heavy weather and find its way to settling tanks and fuel treatment plant, with a potential to subject the machinery to abrasive wear from previously settled catalytic fines. Most of the supporting evidence of this is anecdotal.

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BUNKER FUEL FOR MARINE ENGINES

Other storage issues High viscosity In extreme cases, the viscosity of the fuel in storage may be too high for efficient pumping. In such cases, increasing the tank heating should remedy the problem.

Low flash point There is a prohibition under SOLAS regulations on storage and the use of fuels with a flash point below 60°C for anything except lifeboat engines, externally located emergency generators and externally located diesel-driven pumps. Some vessels operating in extreme climates can be given an exemption from their flag state.

Tendency to oxidisation (distillate fuels) Some distillate fuels show an increasing tendency to oxidisation if kept in storage for an extended period. Whilst this occurs in storage, the impact is not apparent until the fuel is used, when it forms ‘gum’ deposits on the fuel injection pumps and injector needle valves.

Treatment High viscosity This is only relevant if the delivered viscosity is so high that the heating equipment is unable to bring the viscosity down to the engine builder’s requirement (usually in the range of 10 mm/s2 to 15 mm/s2 at the engine). In practice, this is almost never a problem technically although it may have commercial implications. The following table shows two separate possibilities: a fuel ordered as 180 mm/ s2 (shown in yellow) and a fuel ordered as 380 mm/s2 shown in blue. The builders would have provided a heating plant capable of heating the specified grade to meet the engine builder’s minimum viscosity (10 mm/s2) on one heater; they will also have provided two heaters!

94

Sensitivity to fuel qualities Delivered viscosity cSt at 50°C 180 cSt 220 cSt 280 cSt 380 cSt 420 cSt 480 cSt 520 cSt 580 cSt 620 cSt 680 cSt

Temperature for 10 cSt

Temperature for 15 cSt

129 133 138 144 146 149 150 152 154 155

113 117 121 127 129 132 133 135 136 138

°C °C °C °C °C °C °C °C °C °C

°C °C °C °C °C °C °C °C °C °C

As can be seen, the 180 cSt ship can cope with a delivered grade of 420 cSt as long as all other parameters are in specification limits. The 380 cSt ship can cope with a delivered grade of 680 cSt as long as all other parameters are in specification limits.

Excess water The separators have a finite capacity to deal with water in the fuel. Whilst most manufacturers will indicate an ability to handle up to 2% water, in practice most separators manage slightly more than this (say 3%), provided the water is not emulsified (which makes separation almost impossible). Separation performance is improved with minimum flow rates and, if practical, with parallel operation of the separators.

High TSP/TSA This may lead to heavy sludge deposits at the separators, to a degree which may prevent normal operation of the equipment. The mechanical shock of the separator triggers the fall-out of asphaltenic sludge.

High density May prevent conventional separators from establishing a stable water seal. They cannot function as a purifier without a water seal.

Adulteration with polymers Polymer compounds (polystyrene or polyethylene, for example) can present as small fibres in the fuel which melt, becoming very plastic at temperatures of about 120°C. They are small enough to try to pass though the hot filters but because of their semi-plastic state they curl around the filter gaps and block the filters.

Carbon deposits in the main fuel heaters If the heating medium is too hot (usually only with steam heaters) and the fuel flow rate is slow, the fuel can carbonise inside the heater forming deposits which will block the hot filters.

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BUNKER FUEL FOR MARINE ENGINES

At the engine Fuel too hot If fuel is too hot, some of it turns to gas at the injection pumps (and any remaining water may turn to steam) which prevents the pump from generating the proper pressure for injection.

Fuel too cold If fuel is too cold, the injection pressure can become dangerously high (normal limits are between 800 bar and 1000 bar maximum) and the spray pattern in the cylinder will be too long, with the burning fuel touching the cylinder wall.

High catalyst fines If the level of catalyst fines is too high after treatment (more than 15 mg/kg-20 mg/kg) then this will cause abrasive damage to fuel injection pumps, fuel injector valves, piston rings and liners. If the particles are more than 5 micron, there is a chance they could jam the movement of the fuel pump plungers or the needle valves.

High carbon residue If the carbon level is too high the residual carbon can form deposits behind and around the piston rings, causing them to seize in the ring grooves and leading to exhaust gases escaping to the low pressure space below the piston. In a medium speed engine this causes contamination of the system lubricating oil and can over pressure the crankcase. On a slow speed engine it can cause fires in the scavenge space (the space beneath the piston but above the piston rod seal).

Poor ignition If the ignition performance is poor, in addition to excess carbon potentially causing ring seizure, the percussive effect can cause the piston rings to break. Poor ignition causes reduced power output, erratic turbocharger performance and generates smoke.

High ash If the ash level is too high, deposits will be found in the exhaust system and on both stationary and moving components in the gas turbine of the turbocharger. This will degrade the performance of the turbocharger. Ash deposits will also coat the surfaces of the waste heat unit, preventing efficient recovery of heat from the exhaust gas and increasing the risk of soot fires.

Sodium/vanadium ratio There is an additional risk for medium speed engines if the sodium is between 20% and 40% of the vanadium level. In this case, the two elements cause the melting temperature of the ash to fall, leading to the possibility of molten droplets of ash

96

Sensitivity to fuel qualities

being deposited on the hot components of the engine exhaust. The deposits for corrosion cells leading to ‘high temperature corrosion’. This effect is controlled by the exhaust temperature. The exhaust temperatures of slow speed engines (below 475°C) are too low for this to matter whilst the exhaust temperature of medium speed engines (around 520°C - 550°C) is in the danger area.

Issues using distillate fuels in slow speed and medium speed engines Viscosity In the last five years, engine builders have drawn attention to their minimum viscosity requirements for fuels, with particular attention to their use after long periods of running on residual fuel. The typical restriction is a minimum viscosity of 2.8 mm/s2 or 3.0 mm/s2 at the engine. Whilst these limits have been in existence for decades, no particular issues had been reported until the imposition of restrictions on fuels used in Californian waters and at berth in EU waters. The normal minimum viscosity of gasoil ISO 8217:2005 (and earlier) DMA was 1.5 mm/s2 at 40°C, the fuel at the engine will normally be at or above this temperature. As a consequence, the ISO 8217:2010 DMA has a minimum viscosity of 2 mm/ s2 at 40°C and an additional grade of DMZ has been introduced with a minimum viscosity of 3.0 mm/s2 at 40°C. Even so, some vessels will need to use chillers (see the earlier section on fuel heating for details) to cool the gasoil prior to the injection pumps. Another effect is that much more care must be taken whilst changing over to distillate to ensure that the change in temperature is not too fast.

Lubricity One side effect of the reduction of sulphur content in gasoil has been to reduce the ability of the gasoil to lubricate the fuel injection pump and fuel injector needle valves. This parameter must show a ‘wear scar diameter’ of less than 520 microns if the sulphur level is below 0.05% sulphur. It is not the level of sulphur which reduces the lubrication effect but rather the process involved in reducing the sulphur which also affects other physical properties of the oil.

Issues related to change over of fuel grade There are two specific risks with regard to fuel change over.

Rate of change of temperature This only affects changes between residual and distillate fuels and vice versa. The change over must be controlled to ensure the rate of change of temperature stays within the recommended range. MAN recommend a maximum rate of change of 2°C per minute. It also recommends that the actual viscosity at the engine should be kept within the range of 2 mm/s2 to 20 mm/s2.

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BUNKER FUEL FOR MARINE ENGINES

Loss of blend stability during the change over Because of the different characteristics of residual high sulphur and both residual and distillate low sulphur fuels there is a greater possibility of forming an unstable blend in the service tank and the hot part of the system during change over. It is recommended that onboard checks of compatibility are made prior to mixing. The probability involved is small but the consequences are serious.

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Emissions

Chapter 14 - Emissions For many years the only interest that shipboard engineers had in combustion chemistry was to try to optimise the performance of the plant. It was well known that oxygen and carbon dioxide measurement in the exhaust would assist in adjusting the combustion process. In the 1970s, as inert gas plant was fitted to oil tankers as a safety measure, the measurement of oxygen levels assumed additional importance as the exhaust gas, if the oxygen level was below 7%, could be used to act as an inert gas blanket above the cargo. Environmental concerns about air pollution from ships caused regulators to examine first the amount of sulphur dioxide (SO2) in the exhaust and then the amount of NOx in the exhaust.

Heat Exhaust gas 13.0% O2 75.8% N2 5.2% CO2 5.35% H2O

Air 8.5 kg/kWh 21% O2 79% N2 Fuel 175% g/kWh 97% HC 3% S

1500 vppm NOx 600 vppm SOx 60 ppm CO 180 ppm HC 120 mg/Nm3part.

Lube 1 g/kWh 97% HC 2.5% CA 0.5% S Work

Figure 80.  Flow process and typical exhaust gas composition Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

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BUNKER FUEL FOR MARINE ENGINES Pollutant

Medium Speed Engines Slow Speed Engines g/kWh g/kWh

NOx

1.2

17

CO

1.6

1.6

HC

0.5

0.5

CO2

660

660

SO2

4.2*% Sulphur

4.2*% Sulphur

Figure 81.  Exhaust gas pollutant quantities

SOx Sulphur Oxide (SOx) in the atmosphere raised the issue of acid rain (this affected vegetation, especially in areas with very thin topsoil). High SOx levels were also suspected of causing health problems in the general population – on land, the restrictions on sulphur in automotive fuel started in the 1980s. By the last decade of the 20th century it was clear that action to reduce SOx emissions from ships was desirable and necessary. This led to an annex (Annex VI) to the MARPOL convention limiting the sulphur in fuel worldwide and an additional limit in areas where the risk was deemed to be particularly high. The limits are constantly under review, the number of ECAs is increasing and this trend is likely to continue. The regulations governing ships are still much less strict than those governing the use of fuels on land.

NOx Unlike the sulphur rules, the amount of NOx cannot be reduced by limiting the composition of the fuels. In fact, the current levels of NOx are a function of the enormous efficiency of slow speed diesel engines. Decades of research went into improving combustion efficiency which increased the level of NOx. The initial regulations coming into effect on NOx could only be met by changes to engine design. The latest, and most severe, restriction will require the treating of engine exhaust with a chemical process onboard before it is released to atmosphere. This involves the use of selective catalytic reactors and will apply to engines installed after 2016 when the ship is in an ECA.

CO Emission of CO (carbon monoxide) is undesirable; it indicates incomplete combustion and is a poisonous gas.

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Emissions

CO2 Emission of carbon dioxide (CO2) is normal for all hydrocarbon fuels. It is a greenhouse gas (GHG) which contributes to global warming. It can only be reduced by burning less fuel, or by burning a fuel which contains smaller amounts of carbon (such as methane or biodiesel). It is very likely that it will become regulated by convention in the near future. The mass of CO2 is approximately 3.5 times the mass of fuel burned.

PM PM is ‘particulate matter’ – soot to you and me. It is a significant health risk and the degree of risk is related to the size of the particles. This is also subject to considerable debate within the IMO and is a target for future regulation.

Exhaust scrubbers One of the provisions of the MARPOL Annex VI convention is that a ship may comply with the sulphur restrictions by removing the sulphur oxides in the exhaust duct. The currently available techniques are called sulphur scrubbers and there are two basic types, wet scrubbers and dry scrubbers

Wet scrubber – salt water The simplest is the salt water wet scrubber. This sprays the exhaust with salt water, and the sulphur oxides are dissolved into the water which is then discharged overboard into the sea The equipment is very similar to the ‘inert gas scrubbers’ used on oil tankers to provide cool clean inert gas to blanket the space above the crude oil in the cargo tanks. The equipment has been used since 1935 although it was only used in large numbers in the 1970s. The concern with this technique is that the water discharged overboard could cause environmental problems, especially in areas where the salt content of the water is reduced (such as in the Baltic Sea). There are now strict requirements for the ‘wash water’ outlet which means that the water must be treated before discharge.

Wet scrubber – fresh water The alternative is the fresh water wet scrubber. This system uses sodium hydroxide, operates on a closed cycle and does not discharge wash water into the sea. There is continuous treatment of the wash water to remove the solids washed out of the exhaust and there is a small outflow of treated fresh water to the sea. Some engineering companies are developing scrubbers that will function as a salt water scrubber in open waters and a fresh water scrubber in sensitive areas.

Dry scrubber With a dry scrubber, the exhaust gas passes through a limestone bed and in the process the sulphur oxides react with the limestone to produce gypsum. This

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BUNKER FUEL FOR MARINE ENGINES

system requires the ship to carry calcium hydroxide granulate onboard. The vessel has to discharge the gypsum ashore where it has many uses in industry. The space required onboard and the logistics of granulate supply and gypsum removal are the difficult areas but there is no effluent and the power consumption is low.

NOx control Selective catalytic reactors In order to meet the new Tier III limits on NOx, designers are struggling to find practical solutions – the most promising solution is to use a device called a selective catalytic reactor (SCR) which reduces the NOx to well below the required limits. The system requires the use of urea in order to regenerate the catalyst. The technology is proven and mature, however the catalyst needs to operate at an elevated temperature and it is susceptible to ‘poisoning’ by sulphur oxides. The simple solution would be to place a scrubber before the SCR but because most scrubbers use water to wash the gas, the inlet temperature at the SCR would be too low for good operation. The dry type of scrubber looks best suited under these conditions but new techniques to allow the use of wet scrubbers are under development

Water injection and HAM There are other techniques for meeting the NOx limit: one is water injection, where water is injected with the fuel and this modifies the combustion process, producing a much reduced level of NOx.

Water

Fuel oil

Control oil Electronic rail valve

Figure 82.  Diagram of water injection system Diagram courtesy of Petrospot Ltd (www.petrospot.com)

It is also possible to achieve a similar effect by spraying water into the inlet air; this is referred to as a Humid Air Motor (HAM).

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Emissions Line for simple EGR SW Spray WMC

FW Spray Diesel engine

Spray

SW

WMC Spray

FW

Exhaust SW gas scrubber

WMC

Auxiliary blower

WMC

EGR blower Non return valve

Cooler No. 1 + No. 2

Line for simple EGR

Figure 83.  MAN Humid Air Motor Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

Hot exhaust gas inlet

Seawater injectors

Freshwater drain

Freshwater injectors Cold exhaust gas outlet

1st stage Flow change cyclone water separator

2nd stage Flow change cyclone water separator Freshwater drain

Figure 84.  MAN Humid Air Motor Diagram courtesy of MAN Diesel & Turbo (www.mandieselturbo.com)

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WMC

BUNKER FUEL FOR MARINE ENGINES

The results are similar to water injection but as salt water is used there are some questions on the potential for fouling.

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Unconventional fuels

Chapter 15 - Unconventional fuels Biodiesel Biodiesel is a diesel fuel manufactured from non-hydrocarbon fuel sources. Because of this, it is not a fuel that meets the current ISO 8217 standard. It is widely used on land as it is seen as an (almost) carbon neutral fuel. It is a very effective replacement for DMA and DMB fuels, however current biodiesel has certain issues with long-term storage, some engine components (seals and jointing materials) and there is a lack of suitable standards and tests for marine application. There is a real risk if biodiesel is used as a diluent for marine residual fuels although the biggest risk is with bio waste rather than finished biodiesel. At the moment, biodiesel is only an economic option if there are government financial incentives to promote its use.

Shale oil Shale oils can be used as a feedstock to make marine fuels and they are specifically allowed within the ISO 8217 standard. At the time of the introduction of the standard, this was allowed because of the existing significant use of shale oil in the United States and Canada for making marine fuel. The recent presence of shale oil in some fuels sourced in the east of Europe has proved problematic and some authorities believe this is linked to high vegetable matter in this shale oil.

Liquefied natural gas This has been used as a fuel for LNG tankers since 1963. The methane gas that boils off the cargo during the voyage is collected and burned in the vessel boilers. Recently, manufacturers have developed diesel engines which can burn methane and many of the newest LNG tankers have dual fuel diesel engines. There is a realisation that methane, stored as LNG, may be a practical solution for many ship types, avoiding the problems with SOx. There are a number of smaller non-tankers using LNG as fuel in Norway (where LNG is freely available by road tanker and ex pipe). The ships need specialist bunker tanks as the fuel is stored at -162°C at atmospheric pressure. The amount of space required is about 30% to 40% greater than that for fuel oil. There are a number of ongoing studies into providing dedicated bunker barges for LNG, especially in Singapore, Rotterdam and Gothenburg.

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BUNKER FUEL FOR MARINE ENGINES

The vapourised methane contains a variable amount of nitrogen and this varies during a voyage. Because of this, the vessel will need to have a control system that can adapt the combustion process to suit the gas composition. At the time of writing, there is a lot of effort being directed towards the adoption of LNG as a fuel on inland waterways in Europe and some work in the southern United States. Current planning is to have LNG refuelling stations for inland barges providing a limited network from late 2012 in the Netherlands and to have LNG bunker barges in service from 2015. As of 2012, there are about 40 vessels other than LNG tankers using LNG but most of these are in Norwegian waters. These include conventional tankers, small coastal cargo vessels, offshore support ships and passenger ferries. Vessels using LNG can also use this fuel directly in fuel cells and in small micro gas turbines (Capstone Turbine Corp. micro turbines) for auxiliary power. The example below is a 65 kW unit, it requires no lubricating oil or coolant, fits in a container measuring 0.75 m x 2.0 m x 2.0 m, and weighs just 1 ton.

Figure 85.  Capstone Micro Turbine engine Diagram courtesy of Capstone Turbine Corp. (www.capstoneturbine.com/prodsol/products/)

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Unconventional fuels

Compressed natural gas This is also methane fuel but stored as a compressed methane gas mixture called compressed natural gas (CNG) at ambient temperature. It remains to be seen if this evolves into a workable fuel storage technique. The supporters for this technique claim it avoids the problems of ‘weathering’ (where the nitrogen content varies in use) but the logistics of fuel transfer are fraught with difficulties.

Dual fuel and gas burning engines Many engines burning methane as fuel are not true diesel engines. In a diesel engine the fuel is ignited by the high temperature of the air in the combustion space at the end of the compression stroke. Some ‘gas’ engines admit the gas into the cylinder with the combustion air via an electronically-controlled valve just before the inlet valve on the cylinder head during the compression stroke (just like a gasoline engine) and they have a much lower compression ratio than a diesel engine. The gas/air mixture is then ignited by a spark plug. This system is used in medium speed engines. It is used for driving electrical power generators or used with reduction gears driving a propeller. The technology has been used onshore for more than 100 years for driving generators. The principal advantage of this is simplicity and the fact that the gas is supplied at a relatively low pressure. A more recent development is the dual fuel system used by Wärtsilä and MAN in four-stroke medium speed engines, where the engine runs on a hybrid cycle using a small amount of pilot liquid fuel (1% of total in normal gas operation) which acts as the ignition source for the gas fuel. The gas fuel is admitted with the normal scavenge air in a controlled manner by an electronically-controlled valve just before the cylinder air inlet valve. This system is in use in dual fuel engines currently in service with LNG tankers. These vessels are diesel electric and the propulsion is by electric motors. These engines could also be used in vessels with a gearbox drive to the propeller. MAN B&W has introduced a high pressure gas injection system for two-stroke low speed engines where the gas is admitted directly into the cylinder by a gas injection valve fitted in the cylinder head at the end of the compression stroke together with pilot liquid fuel which acts as the source of ignition for the gas fuel. This system is used with direct drive. The high pressure gas injection system requires a very sophisticated gas compressor system but has the advantage of very good thermal efficiency and low speed combined with the reduced emissions as seen in the other two solutions. To date, the application of the high pressure injection system is at a low level but it can be expected to gain a market share as it gains service experience.

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BUNKER FUEL FOR MARINE ENGINES

The principal concerns for marine use are focused on safety, especially the location of the gas storage and the method of isolating the fuel gas from the engine room. The engine receives its supply from a gas valve unit which acts as a shut-off device, controls the supply pressure and can purge the system with nitrogen before and after use.

Figure 86.  The Bit Viking converted to LNG operation Photograph courtesy of Tarbit Shipping AB (www.tarbit.se)

On most existing ships, the gas valve unit is installed outside the engine room in a room with special ventilation and lighting arrangements but it must be within 10 m of the engines. Wärtsilä has developed an encapsulated gas valve unit which can be installed safely in the engine room, making retrofit installations and application feasible on many more ship types.

Liquefied petroleum gas There are engines which will operate on propane and butane gas. This is stored as liquid at a much higher temperature than LNG but, because the gas is heavier than air, the classification societies do not have approved systems for use at sea at this time.

Coal There are a few vessels operating in niche trades which use coal as fuel for boilers. There are environmental issues over the use of coal and there is no logistical infrastructure for supply. If economics give an increasing advantage to coal over oil then it may come back into fashion. The photograph on the facing page is of the bulk carriers River Boyne and River Embley operating on the Australian coast. The grey structure behind the accommodation is the coal storage and transfer area.

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Unconventional fuels

Figure 87. 

River Boyne and River Embley, Australia

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BUNKER FUEL FOR MARINE ENGINES

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110

Glossary

Glossary TERM

Abrasion

Acid

Acid number Additive Alkali Alkalinity

API gravity

DESCRIPTION

Common wear characterised by fairly regularly spaced grooves running in rubbing direction. Usually near top dead centre of the engine. A substance which forms hydrogen ions in solution which may be replaced by a metal to form salts. Acids are usually sour, corrosive and turn blue litmus red. They neutralise and are neutralised by alkalis. pH values 0-6. A measure of the potassium hydroxide needed to neutralise all or part of the acidity of a petroleum product. Any material added to a base stock to change its properties, characteristics or performance. A chemical compound capable of neutralising an acid, e.g., caustic soda (potassium hydroxide) pH value of 7-14. The extent to which a solution is alkali (pH value). An arbitrary scale adopted by the American Petroleum Institute (API) for expressing the relative density of oils. Its relation to relative density/specific gravity is: API Gravity (Degrees) = (_____141.5______ ) - 131.5

Ash

Asphaltenes ASTM Atmospheric distillation

(Specific Gravity at 60/60 Degrees F ) Incombustible non-carbonaceous fuel residues usually containing a mixture of aluminium, calcium, iron, nickel, silicon, sodium and vanadium. Contamination may be derived from the crude oil stock or from catalytic fines, downstream storage and airborne dirt. If combustion has been complete, the ash will be entirely inorganic. An integral part of fuel oil which are combustible, insoluble particles, which contain a high carbon to hydrogen ratio and can entrap water, fuel, ashes and other impurities. American Society for Testing and Materials (www.astm. org). Primary distillation process in a refinery, the operation being carried out at normal atmospheric pressure.

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BUNKER FUEL FOR MARINE ENGINES TERM

DESCRIPTION

The pressure of air in the open atmosphere, exerted equally in all directions. The standard pressure at sea Atmospheric pressure level is that which will support a column of mercury 760 millimeters high (29.91 inches). This is equivalent to 14.7 pounds per square inch, or 1.0133 bar. Sub-division of a material into its smallest parts, Atomisation particularly applied to liquids reduced to fine spray or mist e.g., diesel injection. Pressure on the exhaust side of an engine or system. The pressure caused by pumping oil up the sheer side Back pressure of a vessel – particularly noticed/important in supplying a VLCC in ballast. Unit of pressure. One bar is equal to 0.987 standard Bar atmospheric pressure, or 14.50 pounds per square inch. BFO Bunker fuel oil. A mixture of distillate and residual fuel oils, or a cutter Blended fuel oil stock and a residual fuel oil. The intimate mixing of various components, including base oils and additives, in the preparation of a product Blending of specified properties. In fuel oils, refers to the mixing of fuels of differing viscosities and densities to obtain a product of the required viscosity and density. British Thermal Unit The quantity of heat required to raise the temperature of (BTU) 1lb of water through 1 degree Fahrenheit. BS & W Bottom sediment and water. A vessel capable of carrying dry cargo in bulk, i.e. not Bulk carrier palletised or containerised. A heavy residual fuel – usually 420-470 cSt, but can be lighter, sulphur typically 2.5% - 3.5% but could also be Bunker C higher, and vanadium 100-350 ppm. The heaviest fuel available in the port. The first ships to be driven by an engine used steam for power. The steam was manufactured by burning coal in the ship’s furnaces. The coal was stored in spaces Bunkers onboard the ship, which were called ‘coal bunkers’. When oil took over from coal the name remained – therefore currently bunkers are distillate or residual fuel for a vessel’s consumption. Eccentric lobes attached to a camshaft which are used Cams in most internal combustion engines to open and close valves and operate fuel pumps.

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Glossary TERM

DESCRIPTION

Camshaft The shaft carrying the cams. Capesize bulk carrier Very Large Dry Bulk Carrier usually over 120,000 DWT. Inert gas present in the products of fuel combustion. Used Carbon dioxide as a refrigerant gas and for fire fighting – specifically for electrical fires. Also recognised as a greenhouse gas. Coked material remaining after an oil has been exposed to high temperatures under controlled conditions. Carbon residue There are three ways of testing: Micro, Ramsbottom or Conradson. Tanks for heavy oils, molasses or other viscous fluids are fitted with heating coils to raise temperature in order Cargo-heating coil that carried fuels may run more easily to pump suctions. Heating may be by steam or oil. A substance which accelerates or changes the course Catalyst of a reaction without undergoing any chemical change itself. Small (typically less than 50 microns) particles of aluminium silicate used as a catalyst in catalytic cracking (cat cracker) refineries. They are sometimes carried over in the refinery process and can be found Catalyst fines in residual fuels. They are very abrasive and can cause excessive wear in engine parts, particularly fuel pumps, cylinder liners and piston rings. An integral part of vehicle emission control systems since 1975. Oxidising converters remove hydrocarbons and carbon monoxide (CO) from exhaust gases, while Catalytic converter reducing converters control nitrogen oxide (NOx) emissions. Both use noble metal (platinum, palladium or rhodium) catalysts that can be ‘poisoned’ by lead compounds in the fuel or lubricant. Secondary oil refining process using a catalyst in a high temperature environment to break down large Catalytic cracking molecules into smaller lighter range molecules. This process increases the volume of the more valuable, lighter products, particularly gasoline. Calculated Carbon Aromaticity Index / Calculated Ignition CCAI/CII Index. A measure of the ignition quality of marine fuels. See Stoke (Numerically equivalent to the SI Unit mm2/ centiStoke (cSt) sec).

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BUNKER FUEL FOR MARINE ENGINES TERM

Cetane Index

Cetane number

Chemical tanker CIMAC

Clarifier

Cloud Point

CO Cold Filter Plugging Point (CFPP) Combustion

DESCRIPTION

A measure of the ignition quality of a distillate fuel. The relative ease with which the fuel will ignite when injected into a compression-ignition engine. Cetane Index is calculated from the API gravity and the mid boiling point of the fuel. Higher Cetane Indices indicate shorter ignition lags and are associated with better combustion performances. A measure of the ignition quality of a diesel fuel, as determined in a standard single cylinder test engine, which measures ignition delay compared to primary reference fuels. The higher the Cetane number, the easier a high speed, direct-injection engine will start, and the less ‘white smoking’ and ‘diesel knock’ after start-up. Tanker carrying chemical and specialised wet cargoes usually up to 50,000 DWT. Conseil International des Machines à Combustion (International Council on Combustion Engines). Engine manufacturers’ association (www.cimac.com). Centrifugal separator operated for removal of solid particles only. Typically older designs without a gravity disk. Also covers new models that no longer use gravity disks and cope with water by automatic blow-down of the bowl contents to a sludge tank. The temperature at which a cloud or haze begins to appear in a previously dried oil when cooled under prescribed conditions, due to the separation of paraffin wax. Since a fuel must be clear and bright for the clouding to be observed, this only applies to certain distillate fuels. Clouding may be regarded as an advance warning of the onset of pour point problems due to either the low temperature or high wax content of the fuel. Oxides of carbon – CO, carbon monoxide, CO2, carbon dioxide, etc. The measure of the ability of diesel fuels to flow at low temperature. A fuel with a low CFPP is capable of being used satisfactorily at low ambient temperatures and will not cause blockages in fuel systems through the precipitation of wax particles. The process of burning fuel, requiring the three elements of heat, fuel and oxygen.

114

Glossary TERM

DESCRIPTION

Ability of a petroleum product to form a homogeneous mixture that neither separates nor is altered by chemical, time or temperature interaction. When blending two Compatibility or more fuels of different crude oil origins and / or different refinery processes, should the resultant blend precipitate asphaltenes, then two or more of the fuels are incompatible. A container with a lid is dipped into the barge’s oil tank and when it is 1/6 of the way down the lid is removed and a sample taken; it is then taken up and poured into a container. This is repeated in the middle and at Composite sample the bottom of the tank. The three samples are then thoroughly mixed and divided up to be delivered to the vessel and barge. See BS 3195: Part 1, Sampling Petroleum Products. Initiation of combustion of fuel in diesel engines due to Compression ignition high temperature and pressure. In an internal combustion engine, the ratio of the volume Compression ratio of combustion space at bottom dead centre to that at top dead centre. Equipment for changing a material from its vapour state Condenser to its liquid state. Conversion of molecular structure of a fuel to provide lighter oils from heavier, carried out either directly by Cracking heat and pressure (thermal cracking) or in presence of catalyst (catalytic or cat cracking). Slow speed marine diesel engine with separate lubrication systems for cylinders and crankcase. Crosshead diesel Invariably operating on the 2-stroke cycle, these engines engine derive their name from the crosshead bearing which couples the piston rod to the connecting rod. The top of the piston in an internal combustion Crown engine above the fire ring, exposed to direct flame impingement. Lubricating oil usually having a high total base number (TBN) for the lubrication of the cylinders of crosshead Cylinder oil marine diesel engines and cylinder lubrication on some types of trunk piston engines. General; this is the actual number of tons of cargo, Dead weight bunkers, stores, etc., that can be put onboard a ship to bring her down to her maximum summer loadline.

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BUNKER FUEL FOR MARINE ENGINES TERM

Density Detonation

Diesel engine Diesel oil Diluent Distillate DMA DMB

DMC

DMX

DMZ Dual fuel engine DWT Dynamic positioning EGCS

DESCRIPTION

A physical property of a material defined as the mass per unit volume at a certain temperature usually expressed in kilogrammes per cubic metre. Uncontrolled burning of the last portion (end gas) of the air/fuel mixture in the cylinder of a spark-ignition engine. Also known as ‘knock’ or ‘ping’. An internal combustion engine, which runs on diesel oil. It does not have spark plugs to ignite the fuel – the combustion is caused by heat generated in the compression stage of the cycle. Oil used as fuel in diesel and other compression-ignition engines. In fuel blending, low-viscosity materials having suitably high flash points are used to reduce the viscosity of residues. Any liquid product obtained by condensing the vapours distilled from petroleum crude oil or its products. The ‘normal’ gasoil burnt in marine engines. Normally a distillate diesel oil, but in some areas of the world there is a blended diesel oil which will meet all the stated parameters. A blended diesel oil for use in low speed marine diesel when manoeuvring the vessel and in larger generators and auxiliaries. Renamed RMA10 in the 2010 standard. A low cloud and low flash point gasoil for use particularly in lifeboats and emergency generators. Due to its low flash point it should not be stored in hot tanks around the engine room. A version of ‘normal’ gasoil burnt in marine engines but with a minimum viscosity of 3 cSt at 40°C to permit continuous use in larger main engines in an emission control area (ECA). Engines designed to burn more than one type of fuel, typically gas fuel and liquid fuel. Deadweight tonnage. The method whereby a vessel is kept on station by computer controlled thruster propellers rather than by anchors. Exhaust gas cleaning systems, equipment fitted to ship in order to reduce emissions.

116

Glossary TERM

E.I.

Engine deposits

Evaporation Evaporator

Exhaust gas recirculation (EGR) Filter Flange

Flash point FPSO Fresh water Friction FSO Fuels - Gasoil Fuels - Marine Fuels - Marine diesel

DESCRIPTION

Energy Institute, the successor to the Institute of Petroleum. Accumulation of sludge, varnish and carbonaceous residues due to blow-by of unburned and partially burned fuel, or from partial breakdown of the crankcase lubricant. Water from condensation of combustion products, carbon, residues from fuel oil additives; dust and metal particles also contribute. Conversion of a liquid to a vapour, without necessarily reaching the boiling point. A device to convert sea water to steam and then condense it to produce distilled water for shipboard use. System to reduce automotive emission of nitrogen oxides (NOx). It routes exhaust gases into the carburettor or intake manifold where they dilute the air/fuel mixture and reduce peak combustion temperatures, thereby reducing the tendency for NOx to form. Device for separating solids or suspended particles from liquid. A projecting flat rim or collar by which pipes are held together; half of a bolted or clamped connection. The point of connection for bunker deliveries. Minimum temperature at which a fluid will support instantaneous combustion (a flash) but before it will burn continuously (fire point). Flash point is an important indicator of the fire and explosion hazards associated with a petroleum product. Floating production storage and offloading system. Water containing no salt (pure water has a density of 1.000). Resistance to motion of one object over another. Friction depends on the smoothness of the contacting surfaces, as well as the force with which they are pressed together. Floating storage and offloading system. A distillate fuel with viscosity in the range 1.5 cSt to 6.0 cSt at 40°C. A distillate or blended product containing some residue. A distillate or blended product containing residue, with a viscosity in the range of 5.5 cSt to 11.0 cSt at 40°C.

117

BUNKER FUEL FOR MARINE ENGINES TERM

DESCRIPTION

The residue remaining after removal of the lighter Fuels - Residual Fuel products or the result of selective blending of various Oil residues and distillate cutter stocks. Furnace Oil Term used in Sri Lanka for fuel oil. G.P. tanker Tanker of between 16,500-24,999 DWT. A petroleum distillate having a viscosity and distillation Gas oil range intermediate to kerosene and light lubricating oil (1.5 cSt - 6.0 cSt at 40°C). Rotary heat engine using combustion gases as a Gas turbine working medium. See Turbine. Liquefied or compressed hydrocarbon gases (propane, butane or natural gas), which are finding increasing Gaseous fuels use in motor vehicles as replacements for gasoline and diesel fuel. Glow plug Heater in combustion chamber of some diesel engines. Greenhouse gases, emissions responsible for global GHG warming. Basically, the capacity in cubic feet of spaces within the hull plus the enclosed spaces above the deck available Gross tonnage (GT) for cargo, stores, fuel, passengers and crew, with a few exceptions, divided by 100. Therefore 100 cubic feet of capacity is the same as 1 gross tonne. GRT Gross registered tonnes now GT. GT Gross Tonnage. Handymax bulker A bulk carrier of 40,000-55,000 DWT. Handysized bulker A bulk carrier usually of 20,000-40,000 DWT. HFO Heavy fuel oil – usually 380 cSt and heavier. High speed marine A marine diesel engine with a rotational speed of over diesel 1,200 revolutions per minute. High sulphur fuel A fuel oil with Sulphur content of above 1.0%. A product is said to be homogeneous when it is totally uniform throughout its structure. In bunkering terms, residual fuel and blended diesel are unlikely to be homogeneous as they are a blend/mixture of more than one product and contain asphaltenes. Gasoil, distillate Homogeneous diesel and distillate fuel oil should be homogeneous so long as they have not been mixed with other products and are the straight run product from the refinery. Sometimes a blend of distillate fuel oil and distillate gasoil/diesel oil from the same crude source/refinery process may be homogeneous, but not necessarily. Hydrocarbon A compound of carbon and hydrogen.

118

Glossary TERM

DESCRIPTION

An instrument used to measure the density or specific Hydrometer gravity of a liquid. International Association of Ports & Harbours (www. IAPH iaph.or.jp). IMO International Maritime Organization (www.imo.org). International Association of Classification Societies IACS (www.iacs.org.uk). IBIA The International Bunker Industry Association. Institute of Chartered Shipbrokers (www.seanet.co.uk/ ICS classif/marassoc/ics/ics1.htm). ICS International Chamber of Shipping. IEA International Energy Agency (www.iea.org). Intermediate fuel oil – usually of viscosity between 30 IFO cSt and 180 cSt. IG System (IGS) Inert gas system. The process of using baffles within a blending chamber in the delivery system, which mixes and swirls the In line blending product on its way from the barge tanks to the vessel, to produce an even blend. In port Within the port limits. Incompatibility is the tendency of a residual fuel to Incompatible produce a deposit on dilution or blending with other fuels. A gas used to fill the head space in a tank (the area above the oil) to stop the chance of explosion or fire. Inert gas Normally washed exhaust gases but can be from a dedicated inert gas generator burning gasoil. A safety system to replace the atmosphere in oil cargo Inert gas system tanks with an inert gas. Normally washed exhaust gases. The Institute of Petroleum, based in London, sets test procedures for petroleum products, as well as being Institute of Petroleum heavily involved in training and education of energy employees (website www.petroleum.co.uk). International Association of Dry Cargo Shipowners Intercargo (www.intercargo.org). An engine in which power is obtained from an explosion Internal combustion of vaporised oil and air in a cylinder (as opposed to a engine turbine engine). International Association of Independent Tanker Owners INTERTANKO (www.intertanko.org).

119

BUNKER FUEL FOR MARINE ENGINES TERM

DESCRIPTION

IP

Institute of Petroleum. International Organization for Standardization (www. ISO iso.org). A unit of work or energy. Work done by a force of one Newton when its point of application moves one metre Joule in the direction of action of the force. Electrical – the heat generated by a current of one ampere flowing for one second against a resistance of one ohm. Measure of a fluid’s resistance to flow under gravity at a Kinematic viscosity specific temperature (usually 40°C, 50°C or 100°C). Knocking See Detonation. LR 1 Tanker of 45,000-79,999 DWT. LR 2 Tanker of 80,000-159,999 DWT. The circumferential areas between the grooves of a Lands piston. LASH Lighter aboard ship (barge carrier). Length between perpendiculars. The maximum water LBP line length of the vessel (excluding the bow and stern overhangs). LFO Light fuel oil – normally covering 20 cSt up to 150 cSt. Natural gas that has been liquefied by refrigeration or Liquefied natural gas pressure in order to facilitate storage or transportation; (LNG) it generally consists mainly of methane. A mixture of light hydrocarbons derived from oil bearing strata which is gaseous at normal temperatures but Liquefied petroleum which has been liquefied by refrigeration or pressure gas (LPG) in order to facilitate storage or transport; it generally consists mainly of propane and butane. LNG Liquefied natural gas. Tanker carrying liquefied natural gas – usually between LNG tanker 30,000 and 250,000 m3. Lo-Lo Lift on-lift off. LOA Length overall. The maximum length of the vessel. Low pour point fuel oil A fuel oil with a pour point of 15°C or below. Low pour point gasoil A gasoil with a pour point of 0°C or below. Low speed marine A marine diesel engine with a rotational speed of up to diesel engine 300 revolutions per minute. Low sulphur fuel A fuel oil with a sulphur content of 1.0% or below. Low sulphur gasoil A gasoil with a sulphur content of 1.0% or below. LPG Liquefied petroleum gas.

120

Glossary TERM

LPG tanker Lubrication MR MS MSDS MV Manifold MARPOL Medium speed marine diesel oil Melting point MEPC Metal content Metric tonne MFO Mixture Molecule MSC Multi-purpose bulker Naphthenic Net tonnage NOx No. 2 Oil

DESCRIPTION

Tanker carrying liquefied petroleum gas – usually between 5,000-85,000 m3. Control of friction and wear by the introduction of a friction-reducing film between moving surfaces in contact. May be a fluid, solid or plastic substance. Tanker of 25,000 - 44,999 DWT. Motor ship. Material Safety Data Sheets. Motor vessel. A piping arrangement which allows one stream of liquid or gas to be divided into two or more streams. The point of connection for bunker deliveries. The International Convention for the Prevention of Pollution of the Sea from Ships. A marine diesel engine with a rotational speed of between 300 and 1,200 revolutions per minute. The temperature at which solids melt. Marine Environment Protection Committee (IMO). Any metallic contaminants present in residual fuels. Equivalent to 1000 kilos, 2204.61lbs or 0.9842 tons. Marine fuel oil – any viscosity for use in a marine engine. A comingling of two or more substances in which each retains its chemical nature and identity. The smallest particle of a compound that is capable of independent existence while retaining its individual properties. Maritime Safety Committee (IMO). Usually 5,000-25,000 DWT and used for carrying containers, breakbulk cargo, lumber, and general large bulky raw materials. A type of petroleum fluid derived from naphthenic crude oil, containing a high proportion of closed-ring methylene groups. This is the gross tonnage less space used for accommodation of master, officers, crew, navigation and propelling machinery. Oxides of nitrogen – NO, nitrous oxide, NO2, nitrogen dioxide, etc. American gasoil, with max SG 0.855, min Cetane 40 sulphur either 0.2 or 0.5 max.

121

BUNKER FUEL FOR MARINE ENGINES TERM

DESCRIPTION

American heavy fuel oil with max SG 0.9861, Sulphur No. 6 Oil 3.0% 3.0 max, and viscosity of 200-250 ssf. NRT Nett registered tonnes, now NT. NT Nett tonnage. OBO Ore/bulk/oil carrier. OCIMF Oil Companies International Marine Forum. A mixture of liquid hydrocarbons of different molecular Oil weights and which also, in its crude form, contains other minerals. A compact sedimentary rock consisting mainly of organic Oil shale matter which yields oil when heated. OPL Outside port limits. For a product to be described as organic, it must have Organic carbon in its molecular make up Occurs when oxygen attacks petroleum fluids. The process is accelerated by heat, light, metal catalysts Oxidation and the presence of water, acids or solid contaminants. It leads to increased viscosity and deposit formation. Largest bulker able to transit the Panama Canal, before its expansion, usually 55,000-80,000 DWT but with Panamax bulk carrier maximum beam of 32.5 m to allow the vessel to fit in the locks on the canal. Largest tanker that can transit the Panama Canal usually Panamax tanker 55,000-80,000 mt DWT but with maximum beam of 32.5m to allow vessel to fit in the locks on the canal. A type of petroleum fluid derived from paraffinic crude oil and containing a high proportion of straight chain Paraffinic saturated hydrocarbons. Often susceptible to cold flow problems. Pascal A unit of pressure, one Newton per square metre. Naturally occurring green to black coloured mixtures of crude hydrocarbon oils found as earth seepages or obtained by boring. The principal producing land areas are North America, Venezuela, Arabian Gulf, Russia, Petroleum West Africa and Indonesia. In the last two decades the search for petroleum has been extended to offshore continental shelves and production has been developed in the Gulf of Mexico and the North Sea.

122

Glossary TERM

pH

Piston rings

Polishing (bore)

Pour point ppm Pressure Product tanker Pumpability Purifier Refinery

Refining

Residual fuel

DESCRIPTION

A measure of the acidity or alkalinity of a solution which is a function of the hydrogen-ion concentration. The pH scale is a logarithmic scale and ranges from 0, which represents a strong acid, to 13, which represents a strong alkali. A neutral solution, which is neither acidic nor alkali, and pure water have a pH value of 7. Circular metallic elements that ride in the grooves of a piston and provide compression sealing during combustion. Also used to spread oil for lubrication. Excessive smoothing of the surface finish of the cylinder bore or cylinder liner in an engine to a mirrorlike appearance, resulting in depreciation of ring sealing and oil consumption performance. An indicator of the ability of an oil or distillate fuel to flow at cold temperatures. It is the lowest temperature at which the fluid will flow when cooled under prescribed conditions. Parts per million. The force of one body acting on another by weight or the application of power. Measured as force per unit area (e.g. pounds per square inch). Smaller tanker carrying oil or food products – usually 10,000-55,000 DWT. The low temperature, low shear stress-shear rate viscosity characteristics of an oil that permit satisfactory flow to and from the engine oil pump and subsequent lubrication of moving components. Centrifugal separator used for the removal of solids and water from lube and fuel oil. A plant used to separate the various components present in crude oil and convert them into usable products or feedstock for other purposes. Series of processes to convert crude oil and its fractions into finished petroleum products, including thermal cracking, catalytic cracking, polymerisation, alkylation, reforming, hydrocracking, hydroforming, hydrogenation, hydrogen treating, hydrorefining, solvent extraction, dewaxing, de-oiling, acid treating, clay filtration and deasphalting. The fuel oil burnt by most vessels, made from the residue of the refinery process.

123

BUNKER FUEL FOR MARINE ENGINES TERM

Residue RINA Ring sticking

Rings RMA 10 RMB 30 RMD 80 RME 180 RMG 180 RMG 380 RMG 500 RMG 700 RMK 380 RMK 700 Ro-Ro SS Salt water

Sample

Sampling

DESCRIPTION

The unevaporated liquid or solid material remaining after a process involving distillation or cracking. Royal Institute of Naval Architects (www.rina.org.uk). The situation when the piston grooves become sufficiently full of deposits or covered in lacquer to prevent the piston rings moving freely. Ring sticking can occur under hot or cold conditions. Circular metallic elements that ride in the grooves of a piston and provide compression sealing during combustion. Also used to spread oil for lubrication (see Piston rings). A light fuel oil of viscosity 10 cSt at 50°C. A light fuel oil of viscosity 30 cSt at 50°C. It has a higher density and pour point than RMA30. A light fuel oil of viscosity 80 cSt at 50°C. A medium fuel oil of viscosity 180 cSt at 50°C which has low vanadium, carbon and ash content. A medium fuel oil of viscosity 180 cSt at 50°C. A heavy fuel oil of viscosity 380 cSt at 50°C. A heavy fuel oil of viscosity 500 cSt at 50°C with standard density. A heavy fuel oil of viscosity 700 cSt at 50°C with standard density. A heavy fuel oil of viscosity 380 cSt at 50°C which has higher vanadium and carbon content than RMG380 but also a higher density. A heavy fuel oil of viscosity 700 cSt at 50°C which has higher density than RMG700. Roll on-roll off. Steam ship. Sea water containing salt. Generally accepted to have density of 1.025. A small amount of the oil supplied (about 3-5 litres) is taken into bottles at the time of delivery to be representative of the product supplied. It can then be tested at a later time to verify the actual quality delivered. Three samples should be taken: one for the vessel, one for the delivery vehicle and one for a surveyor (if in attendance). The process of obtaining a small quantity of material which is as representative as possible of the total delivery.

124

Glossary TERM

Scuffing Segregated ballast Separator SG Shaft horse power (SHP) Sludge SOLAS Sounding

Specific energy

Specific gravity Specification

Splash blend Spot sampling

DESCRIPTION

Abnormal engine wear due to localised welding and fracture. It can be prevented through the use of antiwear, extreme pressure and friction modifier additives. Sea water used as ballast kept from contact with any cargo tanks. Loaded and discharged by its own piping and pumping system. See Purifier and Clarifier. Also a static device used for the removal of oil from water as in the oily water bilge separator. Specific gravity. Net power delivered to shafting from an engine after passing through gearboxes, thrust block, etc. Fuel oil. A dark residue that may be found in fuel oil as a result of instability. International Convention for Safety of Life at Sea (IMO). Depth of oil or liquid in a tank, can be measured traditionally by a sounding tape dropped down the sounding pipe, or may be measured remotely by gauges. The amount of heat liberated by the combustion of a unit quantity under specified conditions. The gross specific energy is the sum of the heat produced by the total combustion of the fuel and the heat released by the condensation of the water formed by such combustion. This is applicable to a boiler. The net specific energy is the gross value minus the heat released by condensation of the water vapour formed by the combustion. The net value is applicable to a diesel engine. Mass/unit volume of product at 60 °F divided by mass/ unit volume of water at 60 °F. Negotiated, fixed set of product characteristics based on designated test methods, may be a standard, such as ISO 8217, or supplier’s own specifications, such as CPC specifications or buyer’s own requirements. The products are pumped into a tank and left to mix as the barge moves around the harbour. This mix may not be homogeneous. A sample which is taken either before or at different times throughout the delivery usually by dipping a container into the oil tanks before delivery.

125

BUNKER FUEL FOR MARINE ENGINES TERM

Stability

Steam turbine Stokes (St)

Straight run Suezmax tanker

Sulphur

TESS Tanker TBN Therm Thermal cracking (visbreaking) Ton/Tonne Top dead centre

DESCRIPTION

Fuel stability is a complex matter that is relevant to MFO and Thin FO. In very simple terms, it may be said that the asphaltenes in a stable fuel are dispersed in an even suspension and will not settle out as a sludge or deposit on heating surfaces, either with time or as a result of heating. See Turbine. The unit of kinematic viscosity, i.e. the measurement of a fluid’s resistance to flow defined by the ratio of the fluid’s dynamic viscosity to its density; usually quoted as centiStokes (cSt) = stokes/100. Products produced by simple refinery distillation without cracking or any alteration to the structure of the constituent hydrocarbon. Largest tanker that can transit the Suez Canal, usually 120,000-170,000 DWT. Symbol S, Atomic number 16 and is in group 16 or (iva) of the periodic table. Sulphur is a tasteless, odourless, light yellow non-metallic element. Sulphur dioxide (SO2)is released into the atmosphere in the combustion of fossil fuels, such as gas, petroleum and coal, and constitutes one of the most troublesome air pollutants, as it contributes towards acid rain. Turbo-electric steam ship. A steam turbine powered vessel which produces electricity from its main engines and uses this to drive a motor to turn the propeller. A ship or vehicle used to transport oil, refined products or liquefied gas. See BN. 100,000 British Thermal Units (BTU). The heat needed to raise 100,000 pounds of water 1°F. An oil refinery process in which the reaction is produced by the action of heat and pressure. A long ton weighs 2,240 pounds; a short or net ton weighs 2,000 pounds; a metric tonne equals 1,000 kilograms or 2,200 pounds. In a reciprocating engine, the position at the top of a piston stroke, where the connecting rod and the crank are in line and the cylinder volume is least.

126

Glossary TERM

Trunk piston diesel engine

Turbine

Turbocharger ULCC Vacuum distillation

Valve lifter Vapour Vapour pressure Varnish Visbreaking Viscosity VLCC VLOO

DESCRIPTION

Medium speed, or high speed, diesel engine generally using the same oil for both cylinder and crankcase lubrication, and utilising connecting rods to transmit piston power directly to the crankshaft rather than through a crosshead. An engine in which a shaft is steadily rotated by the impact of a flow of steam, gas, air, water or other fluid directed from jets or nozzles upon blades of a wheel or series of wheels. Compressor driven by exhaust gas driven turbine supplying pressurised air to the engine to increase power. Ultra large crude carrier. Above 250,000 DWT, typical size about 320,000 DWT maximum. Jahre Viking built in 1979 weighed in at 564,763 DWT. The process in which distillation is carried out in a vacuum or at much reduced pressure and reduced temperature, to ensure the product is not thermally cracked. Sometimes called a ‘cam follower’, a component in engine design that uses a linkage system between a cam and the valve it operates. The lifter typically translates the rotational motion of the cam to a reciprocating linear motion in the linkage system. Gaseous form of a material, normally liquid or solid. The pressure exerted by vapour escaping from a liquid; as temperature rises so does pressure increase. A thin, insoluble, non-wipeable film occurring on interior engine parts. Can cause sticking and malfunction of close-clearance moving parts. Called lacquer in diesel engines. See Thermal cracking. A measure of a fluid’s resistance to flow. Very large crude carrier – 200,000-280,000 DWT, typically about 260,000 DWT. Very large oil/ore carrier usually of over 200,000 DWT. These vessels will either carry oil or dry cargo, not a mixture of both at the same time.

127

BUNKER FUEL FOR MARINE ENGINES

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128

Appendix 1 - Where to go for help

Appendix 1 - Where to go for help For verification of ship names and a cross check with the IMO number, Equasis: www.equasis.org For general assistance with questions about the bunker industry, the International Bunker Industry Association (IBIA): www.ibia.net For details on International Maritime Organization (IMO) conventions such as MARPOL and SOLAS: www.imo.org For details on European Union regulations on control of atmospheric pollution: www.europa.eu/legislation_summaries/environment/air_pollution/21050_en.htm A good source of energy market information (not specific to bunkers) is: www. bloomberg.com/news/energy/ Limited live Automatic Identification of Ships (AIS) data can be viewed without charge on: www.marinetraffic.com/ais/

Non-governmental organisations There are a number of non-governmental organisations (NGOs) that get involved with bunkering. Amongst these are: BIMCO – Baltic and International Maritime Council: www.bimco.dk CONCAWE – Conservation of Clean Air and Water in Europe: www.concawe.be INTERTANKO – The Independent Tanker Owners industry association: www. intertanko.com OCIMF – The Oil Companies International Maritime Forum: www.ocimf.com ITOPF – The International Tanker Owners Pollution Federation: www.itopf.com There are a number of other companies and organisations: Shell: www.shell.com Chevron: www.fammllc.com BP: www.bp.com Total: www.marinefuels.total.com The Institute of Marine Engineering Science and Technology (I.Mar.E.S.T.) is a source of all technical information: www.imarest.org The American Bureau of Shipping has a good site on regulatory matters: www. eagle.org

129

BUNKER FUEL FOR MARINE ENGINES

Det Norske Veritas has a good download on MARPOL Annex VI and the ECAs: www.dnv.com North of England P & I Club has a good page for industry news on regulations: www.nepia.com/publications/industrynews/listing/

Technical and legal information For detailed technical and legal information, I can recommend: Bunkers: An Analysis of the Practical, Technical and Legal Issues Third edition. ISBN 0-9548097-0-X. Chris Fisher and Jonathan Lux. Published in 2004 by Petrospot Limited, Oxfordshire, England. www.petrospot.com/books Legal Issues in Bunkering – An introduction to the law relating to the sale and use of marine fuels First edition. ISBN 978-0-9548097-6-8. Trevor Harrison. Published in 2011 by Petrospot Limited, Oxfordshire, England. www.petrospot.com/books

General bunkering For general information on bunkering, I can recommend: An Introduction to Bunkering First edition. English version ISBN 978-0-9548097-1-3 (Spanish version ISBN 978-0-9548097-2-0). Nigel Draffin. Published in 2008. Second edition published in 2012. Both published by Petrospot Limited, Oxfordshire, England. www.petrospot. com/books An Introduction to Fuel Analysis First edition. ISBN 978-0-9548097-3-7. Nigel Draffin. Published in 2009 by Petrospot Limited, Oxfordshire, England. www.petrospot.com/books An Introduction to Bunker Operations First edition. ISBN 978-0-9548097-4-4. Nigel Draffin. Published in 2010 by Petrospot Limited, Oxfordshire, England. www.petrospot.com/books Commercial Practice in Bunkering First edition. ISBN 978-0-9548097-8-2. Nigel Draffin. Published in 2011 by Petrospot Limited, Oxfordshire, England. www.petrospot.com/books

Useful websites Information sources: IHS Fairplay’s Sea-Web: www.sea-web.com Lloyd’s List Intelligence’s Seasearcher: www.seasearcher.com Petrospot’s Bunkerspot: www.bunkerspot.com

130

Appendix 1 - Where to go for help

Petromedia’s Bunkerworld: www.bunkerworld.com McGraw-Hill’s Platts: www.platts.com Tradewinds: www.tradewinds.no Ship Management International: www.shipmanagementinternational.com There are some useful manufacturers’ websites dealing with technical issues: The Diesel Duck site on diesel engines: www.dieselduck.net Warsash Maritime Academy site on marine diesels: www.marinediesels.co.uk Kittiwake are specialists in fuel sampling and testing equipment: www.kittiwake. com

131

BUNKER FUEL FOR MARINE ENGINES

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