Guidelines for combustible dust hazard analysis

240 Pages·2017·5.48 MB·English

GUIDELINES FOR
COMBUSTIBLE DUST HAZARD
ANALYSIS
This book is one in a series of process safety and guideline and concept
books published by the Center for Chemical Process Safety (CCPS).
Please go to www.wiley.com/go/ccps for a full list of titles in this series.
GUIDELINES FOR
COMBUSTIBLE DUST HAZARD
ANALYSIS
CENTER FOR CHEMICAL PROCESS SAFETY
OF THE
AMERICAN INSTITUTE OF CHEMICAL ENGINEERS
NEW YORK, NY
Copyright © 2017 by the American Institute of Chemical Engineers, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

A Joint Publication of the Center for Chemical Process Safety of the American Institute of Chemical
Engineers and John Wiley & Sons, Inc.

Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data is available.

ISBN: 978-1-119-01016-6

Printed in the United States of America.

10 9 8 7 6 5 4 3 2 1
It is our sincere intention that the information presented in this
document will lead to an even more impressive safety record for the
entire industry; however, neither the American Institute of Chemical
Engineers (AIChE), its consultants, CCPS Technical Steering Committee
and Subcommittee members, their employers, their employers officers
and directors, warrant or represent, expressly or by implication, the
correctness or accuracy of the content of the information presented in
this document. As between (1) AIChE, its consultants, CCPS Technical
Steering Committee and Subcommittee members, their employers, their
employers officers and directors, and (2) the user of this document, the
user accepts any legal liability or responsibility whatsoever for the
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TABLE OF CONTENTS
LIST OF TABLES xiii
LIST OF FIGURES xv
ACRONYMS AND ABBREVIATIONS xvii
GLOSSARY xix
ACKNOWLEDGMENTS xxiv
PREFACE xxvii
1.Introduction 1
1.1 Purpose of Book 1
1.2 Book Road Map 2
1.3 References 4
2.Background 5
2.1 Nature of the Dust Fire and Explosion Problem 5
2.1.1 Dust Explosion Statistics 5
2.1.2 Case Study: Hoeganaes Corporation 5
Findings and Lessons 10
2.2 Requirements for Dust Fires and Explosions 11
2.2.1 Layer Fire. 12
2.2.2 Flash Fires and Explosions 12
2.3 Combustibility and Explosivity Parameters 15
2.3.1 Explosibility Screening Test 15
2.3.2 Deflagration Index, K (bar-m/sec) 18
St
2.3.3 Maximum Pressure, P (Bar) 18
max
2.3.4 Minimum Explosible Concentration, MEC (g/m3) 19
2.3.5 Minimum Ignition Energy, MIE (mJoules, mJ) 19
2.3.6 Minimum Auto Ignition Temperature, Cloud, MAIT ( C) 20
2.3.7 Layer Ignition Temperature, LIT ( C) 20
2.3.8 Limiting Oxygen Concentration, LOC (vol% O ) 20
2
vii
viii GUIDELINES FOR COMBUSTIBLE DUST HAZARD ANALYSIS
2.3.9 Volume Resistivity (Ohm-m) 20
2.4 Comparison to Combustible Vapors 21
2.5 Effect of Parameters 22
2.6 Summary 22
2.7 References 23
3. The Hazards Within – Dust Inside Equipment 25
3.1 Methods of Prevention, Protection, Mitigation 25
3.1.1 Ignition Control 26
3.1.2 Inerting/Oxidant Control 28
3.1.3 Combustible Concentration Control 28
3.1.4 Deflagration Venting 28
3.1.5 Deflagration Suppression 29
3.1.6 Containment 29
3.1.7 Deflagration Isolation 30
3.2 Issues 30
3.2.1 Air/Material Separators 32
3.2.2 Size Reduction Equipment (grinders, mills, etc.) 34
3.2.3 Dryers 35
3.2.4 Silos/Hoppers 36
3.2.5 Portable Containers 37
3.2.6 Conveyors 38
3.2.7 Blenders/Mixers 41
3.2.8 Feeding into Vessels Having Flammable Vapor Atmospheres 4 1
3.3 Summary 42
3.4 References 42
4.Hazards of Dust External to Equipment 45
4.1 Case Study – Imperial Sugar 45
4.2 Issues Inside a Room or Building 48
4.3 Methods of Prevention and Protection 49
4.3.1 Control of Dust Deposits Outside of Equipment 49
4.3.2 Ignition Control 52
4.3.3 Damage Limiting Construction 52
TABLE OF CONTENTS ix
4.4 Summary 52
4.5 References 53
5. Traditional Approach to Hazard Assessment and Control 55
5.1 Introduction 55
5.1.1 Process Safety Information (PSI) 55
5.1.2 Competent Team 56
5.2 Steps to the Traditional Approach 56
5.2.1 Step 1 – Is a combustible dust involved? 57
5.2.2 Step 2 – Determine Which Standards Apply 58
5.2.3 Step 3 - Determine Where Fire/Explosion Hazards Exist 62
5.2.4 Step 4 – Review Unit Operation vs. Standard Requirements for
Prevention and Mitigation of Fires/Explosions 63
5.2.5 Step 5 – Make Recommendations 65
5.2.6 Step 6 – Document the DHA 65
5.2.7 Step 7 – Implement the Recommendations 66
5.3 Summary 67
5.4 References 68
6.Risk-based Approach to Dust Hazard Analysis 69
6.1 Introduction 69
6.2 Technique for a Risk-based DHA 70
6.2.1 Step 1: Identify Failure Scenarios 70
6.2.2 Step 2: Evaluate the Consequences 70
6.2.3 Step 3: Are the Consequences Tolerable? 73
6.2.4 Step 4: Estimate Likelihood and Risk 73
6.2.5 Step 5: Is the Risk Tolerable 78
6.2.6 Step 6: Recommend and Evaluate Solutions 80
6.2.7 Step 7: Is the Mitigated Risk Tolerable? 81
6.2.8 Step 8: Document Results 81
6.3 DHA Risk Assessment, Additional Requirements 82
6.3.1 DHA Leader Competency 83
6.3.2 Documentation 83
6.4 Managing Change and Updating Risk Assessment 83
6.5 Summary 83
x GUIDELINES FOR COMBUSTIBLE DUST HAZARD ANALYSIS
6.6 References 84
7. Special Considerations: Combustible Dust Issues in Existing
Facilities 87
7.1 Introduction 87
7.2 Existing Facilities and Combustible Dusts 87
7.2.1 Potential Issues 87
7.2.2 Issues Impact 91
7.2.3 Precautions 92
7.3 Summary 92
7.4 References 93
8. Worked Examples 95
8.1 Introduction 95
8.2 Example 1 95
8.2.1 Process Description – Example 1 95
8.2.2 Traditional DHA – Example 1 95
8.2.3 Risk-based DHA – Example 1 112
8.2.4 Comparison of Traditional vs. Risk-based Approach –
Example1 167
8.3 Example 2 169
8.3.1 Process Description 2 169
8.3.2 Traditional DHA 171
8.3.3 Risk-based DHA 173
8.3.4 Comparison of Traditional vs. Risk-based Approach –
Example 2 176
8.4 Example 3 177
8.4.1 Process Description – Example 3 177
8.4.2 Traditional DHA – Example 3 179
8.4.3 Risk-based DHA – Example 3 181
8.5 Summary 188
8.6 References 188
Appendix A Regulations and Codes 191
A.1 Regulations 191
A.1.1 U.S. 191
TABLE OF CONTENTS xi
A.1.2 International 191
A.2 Codes 192
References 195
Appendix B AdditionalResources 197
B.1 Book s 197
B.2 U.S. Chemical Safety Board Reports 197
B.3 Journal Articles 198
B.4 Other 199
Appendix C Data for Risk-based DHA 201
C.1 Probability Assessment of Process Unit Fire or
Dust E xplosion 201
C.1.1 Initiating Event Frequencies 204
C.1.2 Ignition Probabilities 205
C.1.3 Protection Layer PFDs 207
C.2 References 209
Appendix D Good Practices 211
D.1 S elfA ssessment 211
D.2 Housekeeping 213
D.2.1 Combustible Dust Housekeeping Inspection Checklist 215
D.3 Explosion Protection Methods 217
Appendix E D HA Roadmap 219
Notes for Figure E.1 221
INDEX 223