Dust Explosions in the Process Industries Second Edition phần 1 doc

Dust Explosions

in the Process Industries

Second Edition

Rolf K. Eckhoff

1 EINEMANN

Butterworth-Heinemann

Linacre House, Jordan Hill, Oxford OX2 8DP

225 Wildwood Avenue, Woburn, MA 01801-2041

A division of the Reed Educational and Professional Publishing Ltd

@A member of the Reed Elsevier plc group

OX t 0 K I)

10H A N N ES H IJ KG

A I!C K LAN I1 BOS-ION

M EL BOU R NE N E W I1 EL Ii I

First published 1991

Paperback edition 1994

Second edition 1997

Reprinted 1998, 1999

(' Reed Educational and Professional Publishing Ltd 1991, 1997

All rights reserved. No part of this publication

may be reproduced in any material form (including

photocopying or storing in any medium by electronic

means and whether or not transiently or incidentally

to some other use of this publication) without the

written permission of the copyright holder except in

accordance with the provisions of the Copyright.

Designs and Patents Act 1988 or under the terms of a

licence issued by the Copyright Licensing Agency Ltd,

YO Tottenham Court Road, London, England WIP YHE.

Applications for the copyright holder's written permission

to reproduce any part of this publication should be addressed

to the publishers

British Library Cataloguing in Publication Data

A catalogue record for this book is available

from the British Library

Library of Congress Cataloguing in Publication Data

A catalogue record for this book is available

from the Library of Congress

ISBN 0 7506 3270 4

Typeset by Keyword Ltd, Wallington, Surrey

Printed in Great Britain by St Edmundsbury Press Ltd, Bury St Edmunds, Suffolk

With deep gratitude for their love and support, 1 dedicate this book to my wife Astrid and

our children Kristian, Ragnar, Solveig and Jorunn, and to my mother and the memory of

my father. The words in Isaiah 42.16 also gave me hope and courage.

Contents

Foreword

Preface

viii

ix

1 Dust explosions - origin, propagation, prevention, and mitigation: an

overview

1.1 The nature of dust explosions

1.2 Significance of the dust explosion hazard: statistical records

1.3 Dust and dust cloud properties that influence ignitability and explosion

violence

1.4 Means for preventing and mitigating dust explosions

1.5 Selecting appropriate means for preventing and mitigating dust

explosions

2 Case histories

2.1 Introduction

2.2 The explosion in a flour warehouse in Turin on 14th December, 1785

2.3 Grain dust explosions in Norway

2.4 Four grain dust explosions in USA, 1980-1981

2.5 A dust explosion in a fish meal factory in Norway in 1975

2.6 Smouldering gas explosion in a silo plant in Stavanger, Norway, in

November 1985

2.7 Smouldering gas explosions in a large storage facility for grain and

feedstuffs in Tomylovo in the Knibyshev Region of USSR

2.8 Smouldering gas explosion and subsequent successful extinction of

smouldering combustion in pelletized wheat bran in a silo cell at Nord

Mills, Malmo, Sweden, in 1989

2.9 Linen flax dust explosion in Harbin linen textile plant, P. R. China,

March 1987

2.10 Fires and explosions in coal dust plants

2.11 Dust explosion in a silicon powder grinding plant at Bremanger,

2.12 Two devastating aluminium dust explosions

Norway, in 1972

3 Generation of explosible dust clouds by re-entrainment and re-dispersion of

deposited dust in air

3.1 Background

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vi Contents

3.2 Structure of problem

3.3 Attraction forces between particles in powder or dust deposits

3.4 Relationship between inter-particle attraction forces and strength of bulk

powder

3.5 Dynamics of particles suspended in a gas

3.6 Dislodgement of dust particles from a dust or powder deposit by

interaction with an airflow

3.7 Dispersion of agglomerates of cohesive particles suspended in a gas, by

flow through a narrow nozzle

3.8 Diffusion of dust particles in a turbulent gas flow

3.9 Methods for generating experimental dust clouds for dust explosion

research purposes

4 Propagation of flames in dust clouds

4.1

4.2 Laminar dust flames

4.3

4.4 Turbulent flame propagation

4.5

Ignition and combustion of single particles

Non-laminar dust flame propagation phenomena in vertical ducts

Detonations in dust clouds in air

5 Ignition of dust clouds and dust deposits: further consideration of some

selected aspects

5.1 What is ignition?

5.2 Self-heating and self-ignition in powder deposits

5.3 Ignition of dust clouds by electric spark discharges between two

metal electrodes

5.4 Ignition of dust clouds by heat from mechanical rubbing, grinding or

impact between solid bodies

5.5 Ignition of dust clouds by hot surfaces

6 Sizing of dust explosion vents in the process industries: further

consideration of some important aspects

6.1 Some vent sizing methods used in Europe and USA

6.2 Comparison of data from recent realistic full-scale vented dust explosion

experiments, with predictions by various vent sizing methods

6.3 Vent sizing procedures for the present and near future

6.4 Influence of actual turbulence intensity of the burning dust cloud on the

maximum pressure in a vented dust explosion

6.5 Theories of dust explosion venting

6.6 Probabilistic nature of the practical vent sizing problem

7 Assessment of ignitability, explosibility and related properties of dusts by

laboratory scale tests

7.1 Historical background

7.2

7.3

A philosophy of testing ignitability and explosibility of dusts:

relationship between test results and the real industrial hazard

Sampling of dusts for testing

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