BOILER OPERATORS HANDBOOK prepared by National Industrial Fuel Efficiency Service Ltd. Graham & Trotman
First published in 1959 as the New Stoker's Manual and in 1969 as The Boiler Operators Handbook This revised edition published in 1981 by Graham and Trotman Limited Sterling House 66 Wilton Road London SW1V 1DE Reprinted 1985 National Industrial Fuel Efficiency Service Ltd, 1981, 1985 ISBN-13: 978-0-86010-251-9 e-isbn-13: 978-94-010-9134-3 DOl: 10.1007/978-94-010-9134-3 This publication is protected by international copyright law. All rights reserved. No part ofthis publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photo-copying, recording or otherwise, without the prior permission ofthe publishers. Biddies Ltd, Guildford, Surrey Typeset in Great Britain by Input Typesetting Limited, London
CONTENTS List of Figures Foreword v vii Chapter 1 Fuels in Common Use Coal. Calorific value. Sizes. Ash. Moisture. Sulphur. Coke. Liquid fuels. Gaseous fuels Chapter 2 Combustion 9 Combustion in practice. Air supply in practice. Combustion of coal on a grate. Burning oil, gas and pulverised fuel. Flames. Flame type. Chapter 3 Water and Steam 18 Steam raising. Definition of terms. Water. Priming (causes and treatment). Chapter 4 Boiler Efficiency and Beat Transfer 29 Boiler thermal efficiency. Gross or higher calorific value. Heat losses. Heat lost in flue gases. Effect of raising flue gas temperature. Air supply. Flue gas temperature. Dirty heat transfer surfaces. Boiler load. Carbon in ash. Heat lost in dust and fly ash. Radiation and other losses. General fuel efficiency within the boiler house. Operating efficiency. Heat transfer. Boiler heat recovery plant. Feedwater economisers. Superheaters. Air heaters. Cleaning heat transfer surfaces. Chapter 5 Boiler Types 48 Vertical boiler. Horizontal boiler. Packaged boilers. Locomotive boiler. Thermal storage boiler. Water-tube boiler. Forced circulation boiler. Steam generators. Sectional boilers for central heating. Automatic or magazine boiler.
Chapter 6 Principles of Solid Fuel Firing 60 Hand firing. Fuelbed thickness. Methods of firing. Firing tools. Grate or firebars. Reducing the grate area. Recovering unburned fuel. Clinker prevention. Cleaning fires. Banking. Chapter 7 Mec:Iumic:a1 Firing 69 Types of mechanical stoker. Sprinkler. Coking. Chaingrate. Automatic controls. Underfeed. Maintenance of mechanical stokers. Vekos automatic auxiliary furnace. Chapter 8 Pulverised Fuel 83 Drying the fuel. Conveyors and storage. Pulverised fuel burners. Ash handling. Chapter 9 Liqaid. Fuels 88 Delivery, h a n and ~ storage. g Fuel oil systems. Oil heaters and filters. Liquid fuel burners. Burner maintenance. Care of burners when shutting down. Carbon deposit. Chapter 10 Gaseous fuels 98 Natural gas. Liquid petroleum gases. Combustion characteristics. Types of burner for use with natural gas. General. Chapter 11 Central Beating: What the Caretaker Should 105 Know Plant operation. Draught control. Repairs. Air inlet to boiler room. Tools. Fuel. Operating Procedure. Chapter 12 Automatic: Control and ldstruments 115 Automatic control. Safety function. Functional control. Anticipatory/sequential control. General. Instruments. Chapter 13 Safety 127 Statutory safety equipment for boiler plant. Boiler safety. Notes on safety valves arising from insurance co. requirements for steam boilers. Water gauges. Gauge glass drill. Automatically controlled steam and hot water boilers. Blowing down of water level controls. Other safety aspects. General safety points. Conclusion. Chapter 14 The Clean Air Act 140 Smoke. Smoke control areas. Grit emission and dispersion of combustion products. Chimney height. Acid smut formation. Grit arrestor.
LIST OF FIGURES 1. Percentage of carbon dioxide in flue gas by volume 10 2. The combustion of coal 11 3. Coal burning on a grate 14 4. Properties of steam 19 5. Vertical smoke tube boiler 47 6. Lancashire boiler 49 7. Two-pass dryback economic boiler 50 8. Packaged boiler 51 9. Locomotive boiler 52 10. Thermal storage boiler 52 11. Three drum water tube boiler 54 12. Forced circulation boiler 55 13. Steam generator. From proceedings of 1977 conference 'Steam at Work' by courtesy of Institute of Mech. Engineers 56 14. Cast iron sectional hot water boiler 57 15. Automatic hot water boiler 58 16. Rotary type sprinkler stoker 70 17. Ram type coking stoker 72 18. Chain grate stoker 74 19. Hopper model underfeed stoker. By courtesy of NCB/College of Fuel Tech. (London) 77 20. Vekos. By courtesy of NCB/College of Fuel Tech. (London) 81 21. Pulverised fuel system 85 22. Parallel flow pulverised fuel burner 86 23. Ring main system 90 24. Pressure jet burner 91 25. Low pressure air burner 93 26. Sectional view of motor-driven rotary cup burner 94 27. Atmospheric injector burner 100 28. Dual gasloil burner 101 29. Automatic gas burner 104 30. Hypothetical control for large burner with pilot 118 31. Orsat gas analyser 123 v
32. Fyrite gas analyser 33. Fusible plug 34. Ringelmann chart 35. Simple grit arrestor 36. Multicell grit arrestor 37. General scheme of electrostatic precipitator 124 129 142 149 150 151 vi
FOREWORD The popularity of the Boiler Operators H a n ~ has oprompted o k the issue of a revised edition. Other than a relatively small number of developments, essentially associated with solid fuel firing methods using the fluidised bed technique, no radical changes have occurred since the first edition of the Handbook was issued in 1969. In revising a work of this kind there is a great temptation to omit practices that are now less common in the UK. In view of the enormous pressure on Global energy resources, however, the chapters dealing in methods of hand-firing have been retained in the hope that they may be of value to those in the less developed nations where energy problems are infinitely greater than ours. High combustion intensity boilers, commonly known as Package Boilers, of the Shell Construction design, have now much greater steam output than their predecessors and the need for high levels of maintenance and operating skills remain as essential as when this group of boilers first appeared on the market. Also the standard of water treatment required is probably higher than the Operator has been accustomed to. The Health and Safety at Work Act re-emphasised the continued need for adherence to the principles that ensure a pressure vessel be maintained in a safe condition at all times. Accordingly the revised edition of the Boiler Operators Handbook has enlarged its sections on Safety and the Clean Air Act. The Boiler Operators Handbook, like its predecessor the New Stoker's Manual, is intended to help the boiler operator carry out his important work with skill and efficiency. It is not a textbook, nor does it go into great detail. Within its compass however, it contains sufficient information to encourage the vii
operator to study the subject more extensively and obtain a recognised qualification. Any of the NIFES offices are prepared to discuss the availability of courses to enable the operator to further enhance his knowledge and skills. Both the Imperial units and their SI equivalents have been included in this new issue. Much inefficiency and many accidents are the result of ignorance and it is to be hoped that this new issue will help the operator and/or nominated attendant to understand the principles involved and enhance his interest in the plant under his care. viii