S E X P L O S I O N in the Process Industries T H I R D E D I T I O N Dust Explosions in fhe Process Indusfries Dust Explosions in the Process Industries Third Edition Rolf K. Eckhoff Gulf Professional Publishing an imprint of Elsevier Science Amsterdam Boston Heidelberg London New York Oxford Paris San Diego San Francisco Singapore Sydney Tokyo Gulf Professional Publishing is an imprint of Elsevier Science. Copyright 02003, Elsevier Science (USA). 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, photocopying,recording, or otherwise, without the prior written permission of the publisher. Recognizing the importance of preserving what has been written, Elsevier Science prints its books on acid-free paper whenever possible. Library of Congress Cataloging-in-PublicationData Eckhoff, Rolf K. Dust explosions in the process industries / Rolf Eckhoff.-3rd ed. p. cm. Includes bibliographical references and index. ISBN 0-7506-7602-7 (HC : alk. paper) 1. Dust explosions. 2. Fire prevention. 3. Industrial accidents. I. Title. TH9446.D86E34 2003 604.7-dc2 1 2003040799 British Library Cataloguing-in-PublicationData A catalogue record for this book is available from the British Library. The publisher offers special discounts on bulk orders of this book. For information, please contact: Manager of Special Sales Elsevier Science 200 Wheeler Road Burlington, MA 01803 Tel: 781-313-4700 Fax: 781-313-4882 For information on all Elsevier Science publications available, contact our World Wide Web home page at: http://www.elsevier.com 10 9 8 7 6 5 4 3 2 I Printed in the United States of America With deep gratitude for their love and support, I dedicate this book to my wife Astrid and our children Kristian, Ragnar, Solveig, and Jorunn, and their families, and to my mother and the memory of my father. The words in Isaiah 42.16 also gave me hope and courage. Gontents Foreword xvii Prefaces xix 1 Dust Explosions-Origin, Propagation, Prevention, and Mitigation: n An Overview 1.1 The nature of dust explosions i 1.1.1 The phenomenon 1 1.1.2 Materials that can cause dust explosions 5 1.1.3 Explosible range of dust concentrations-primary and secondary explosions 7 1.1.4 Ignition sources 10 1.2 Significanceof the dust explosion hazard: statistical records 20 1.2.1 Recording dust explosions, an activity of long traditions 20 1.2.2 Dust explosions in the United States, 1900-1956 21 1.2.3 Dust explosions in the Federal Republic of Germany, 1965-1985 22 1.2.4 Recent statistics of grain dust explosions in the United States 25 1.3 Dust and dust cloud properties that influence ignitability and explosion violence 25 1.3.1 Dust chemistry, including moisture 25 1.3.2 Particle size or specific surface area 29 1.3.3 Degree of dust dispersion effective particle size 32 1.3.4 Dust concentration 34 1.3.5 Turbulence 36 1.3.6 Oxygen content of oxidizer gas 39 1.3.7 Initial temperature of the dust cloud 44 1.3.8 Initial pressure of a dust cloud 47 1.3.9 Combustible gas or vapor mixed with a dust cloud (“Hybrid” mixtures) 50 1.3.10 Inerting by mixing inert dust with combustible dust 55 1.3.11 Concluding remarks 56 1.4. Means for preventing and mitigating dust explosions 57 1.4.1 The means available: an overview 57 1.4.2 Preventing ignition sources 57 .4.3 Preventing explosible dust clouds 67 1.4.4 Preventing explosion transfer between process units via pipes and ducts: explosion isolation 73 I .4.5 Explosion-pressure-resistantequipment 81 1.4.6 Explosion venting 84