Guidelines for Vapor Cloud Explosion, Pressure Vessel Burst, BLEVE, and Flash Fire Hazards E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Veröffentlichungsjahr: 2011

Beschreibung

This guide provides an overview of methods for estimating the characteristics of vapor cloud explosions, flash fires, and boiling-liquid-expanding-vapor explosions (BLEVEs) for practicing engineers. It has been updated to include advanced modeling technology, especially with respect to vapor cloud modeling and the use of computational fluid dynamics. The text also reviews past experimental and theoretical research and methods to estimate consequences. Heavily illustrated with photos, charts, tables, and diagrams, this manual is an essential tool for safety, insurance, regulatory, and engineering students and professionals.

Leseprobe

CONTENTS

Cover

Half Title page

Title page

Copyright page

List of Tables

List of Figures

Glossary

Acknowledgments

Chapter 1: Introduction

Chapter 2: Management Overview

2.1. Flash Fires

2.2. Vapor Cloud Explosions

2.3. Pressure Vessel Bursts

2.4. BLEVEs

2.5. Prediction Methodologies

Chapter 3: Case Histories

3.1. Historical Experience

3.2. Flash Fires

3.3. Vapor Cloud Explosions

3.4. Pressure Vessel Burst

3.5. BLEVE

Chapter 4: Basic Concepts

4.1. Atmospheric Vapor Cloud Dispersion

4.2. Ignition

4.3. Thermal Radiation

4.4. Explosions — VCE

4.5. Blast Effects

Chapter 5: Flash Fires

5.1. Overview of Experimental Research

5.2. Flash-Fire Radiation Models

5.3. Sample Calculations

Chapter 6: Vapor Cloud Explosions

6.1. Introduction

6.2. Vapor Cloud Deflagration Theory and Research

6.3. Vapor Cloud Detonation Theory and Research

6.4. VCE Prediction Methods

6.5. Sample Problems

Chapter 7: Pressure Vessel Bursts

7.1. Mechanism of A PVB

7.2. Scaling Laws Used in PVB Analyses

7.3. Blast Eeffects of Pressure-Vessel Bursts

7.4. Methods for Predicting Blast Effects from Vessel Bursts

7.5. Fragments from A PVB

7.6. Predicting Fragment Effects from Vessel Bursts

Chapter 8: Basic Principles of BLEVEs

8.1. Introduction

8.2. Definition of A BLEVE

8.3. Theory

8.4. BLEVE Consequences

8.5. Analytical Models

8.6. Sample Problems

Chapter 9: References

Appendix A: View Factors for Selected Configurations

A-1. View Factor of A Spherical Emitter (e.g., Fireball)

A-2. View Factor of A Vertical Cylinder

A-3. View Factor of A Vertical Plane Surface

Appendix B: Tabulation of Some Gas Properties In Metric Units

Appendix C: Conversion Factors to Si for Selected Quantities

Index

Guidelines for Vapor Cloud Explosion, Pressure Vessel Burst, BLEVE, and Flash Fire Hazards

This book is one in a series of process safety 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.

It is sincerely hoped that the information presented in this document will lead to an even more impressive safety record for the entire industry. However, the American Institute of Chemical Engineers, its consultants, the CCPS Technical Steering Committee and Subcommittee members, their employers, their employers’ officers and directors, and BakerRisk, and its employees do not warrant or represent, expressly or by implication, the correctness or accuracy of the content of the information presented in this document. As between (1) American Institute of Chemical Engineers, its consultants, CCPS Technical Steering Committee and Subcommittee members, their employers, their employers’ officers and directors, and BakerRisk, and its employees and (2) the user of this document, the user accepts any legal liability or responsibility whatsoever for the consequences of its use or misuse.

Copyright © 2010 by American Institute of Chemical Engineers, Inc. All rights reserved.

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

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

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Library of Congress Cataloging-in-Publication Data:

Guidelines for vapor cloud explosion, pressure vessel burst, BLEVE, and flash fire hazards. — 2nd ed. p. cm. “Center for Chemical Process Safety.” Includes index. ISBN 978-0-470-25147-8 (cloth) 1 Chemical plants—Fires and fire prevention. 2. Chemical plants—Safety measures. 3. Pressure vessels—Safety measures. 4. Chemicals—Fires and fire prevention. 5. Explosions—Prevention. I. American Institute of Chemical Engineers. Center for Chemical Process Safety. TH9445.C47G86 2010 660’.2804—dc22

2010003430

GLOSSARY

Blast:

A transient change in the gas density, pressure, and velocity of the air surrounding an explosion point. The initial change can be either discontinuous or gradual. A discontinuous change is referred to as a shock wave, and a gradual change is known as a pressure wave.

BLEVE (Boiling Liquid, Expanding Vapor Explosion):

The explosively rapid vaporization and corresponding release of energy of a liquid, flammable or otherwise, upon its sudden release from containment under greater-than-atmospheric pressure at a temperature above its atmospheric boiling point. A BLEVE is often accompanied by a fireball if the suddenly depressurized liquid is flammable and its release results from vessel failure caused by an external fire. The energy released during flashing vaporization may contribute to a shock wave.

Burning velocity:

The velocity of propagation of a flame burning through a flammable gas-air mixture. This velocity is measured relative to the unburned gases immediately ahead of the flame front. Laminar burning velocity is a fundamental property of a gas-air mixture.

Deflagration:

A propagating chemical reaction of a substance in which the reaction front advances into the unreacted substance rapidly but at less than sonic velocity in the unreacted material.

Detonation:

A propagating chemical reaction of a substance in which the reaction front advances into the unreacted substance at or greater than sonic velocity in the unreacted material.

Emissivity:

The ratio of radiant energy emitted by a surface to that emitted by a black body of the same temperature.

Emissive power:

The total radiative power discharged from the surface of a fire per unit area (also referred to as surface-emissive power).

Explosion:

A release of energy that causes a blast.

Fireball:

A burning fuel-air cloud whose energy is emitted primarily in the form of radiant heat. The inner core of the cloud consists almost completely of fuel, whereas the outer layer (where ignition first occurs) consists of a flammable fuel-air mixture. As the buoyancy forces of hot gases increase, the burning cloud tends to rise, expand, and assume a spherical shape.

Flame speed:

The speed of a flame burning through a flammable mixture of gas and air measured relative to a fixed observer, that is, the sum of the burning and translational velocities of the unburned gases.

Flammable limits:

The minimum and maximum concentrations of combustible material in a homogeneous mixture with a gaseous oxidizer that will propagate a flame.

Flash vaporization:

The instantaneous vaporization of some or all a liquid whose temperature is above its atmospheric boiling point when its pressure is suddenly reduced to atmospheric.

Flash fire:

The combustion of a flammable gas or vapor and air mixture in which the flame propagates through that mixture in a manner such that negligible or no damaging overpressure is generated.

Impulse:

A measure that can be used to define the ability of a blast wave to do damage. It is calculated by the integration of the pressure-time curve.

Jet:

A discharge of liquid, vapor, or gas into free space from an orifice, the momentum of which induces the surrounding atmosphere to mix with the discharged material.

Lean mixture:

A mixture of flammable gas or vapor and air in which the fuel concentration is below the fuel’s lower limit of flammability (LFL).

Negative phase:

That portion of a blast wave whose pressure is below ambient.

Overpressure:

Any pressure above atmospheric caused by a blast.

Positive phase:

That portion of a blast wave whose pressure is above ambient.

Pressure wave:

See Blast.

Reflected pressure:

Impulse or pressure experienced by an object facing a blast.

Rich mixture:

A mixture of flammable gas or vapor and air in which the fuel concentration is above the fuel’s upper limit of flammability (UFL).

Shock wave:

See Blast.

Side-on pressure:

The impulse or pressure experienced by an object as a blast wave passes by it.

Stoichiometric ratio:

The precise ratio of air (or oxygen) and flammable material which would allow all oxygen present to combine with all flammable material present to produce fully oxidized products.

Superheat limit temperature:

The temperature of a liquid above which flash vaporization can proceed explosively.

Surface-emissive power:

See Emissive power.

Transmissivity:

The fraction of radiant energy transmitted from a radiating object through the atmosphere to a target after reduction by atmospheric absorption and scattering.

TNT equivalence:

The amount of TNT (trinitrotoluene) that would produce observed damage effects similar to those of the explosion under consideration. For non-dense phase explosions, the equivalence has meaning only at a considerable distance from the explosion source, where the nature of the blast wave arising is more or less comparable with that of TNT.

Turbulence:

A random-flow motion of a fluid superimposed on its mean flow.

Vapor cloud explosion:

The explosion resulting from the ignition of a cloud of flammable vapor, gas, or mist in which flame speeds accelerate to sufficiently high velocities to produce significant overpressure.

View factor:

The ratio of the incident radiation received by a surface to the emissive power from the emitting surface per unit area.

ACKNOWLEDGMENTS

This Guideline book was developed as a result of two projects sponsored by The Center for Chemical Process Safety of the American Institute of Chemical Engineers. The second edition of the Guideline was prepared under the direction of the Vapor Cloud Explosion subcommittee comprised of the following engineers and scientists:

Larry J. Moore (FM Global), chair

Chris R. Buchwald (ExxonMobil)

Gary A. Fitzgerald (ABS Consulting)

Steve Hall (BP plc)

Randy Hawkins (RRS Engineering)

David D. Herrmann (DuPont)

Phil Partridge (The Dow Chemical Company)

Steve Gill Sigmon (Honeywell - Specialty Materials)

James Slaugh (LyondellBasell)

Jan C. Windhorst (NOVA Chemical, emeritus)

The second edition was authored by the Blast Effects group at Baker Engineering and Risk Consultants, Inc. The authors were:

Quentin A. Baker

Ming Jun Tang

Adrian J. Pierorazio

A. M. Birk (Queen’s University)

John L. Woodward

Ernesto Salzano (CNR - Institute of Research on Combustion)

Jihui Geng

Donald E. Ketchum

Philip J. Parsons

J. Kelly Thomas

Benjamin Daudonnet

The authors and the subcommittee were well supported during the project by John Davenport, who served as the CCPS staff representative.

The efforts of the document editors at BakerRisk are gratefully acknowledged for their contributions in editing, layout and assembly of the book. They are Moira Woodhouse and Phyllis Whiteaker.

CCPS also gratefully acknowledges the comments submitted by the following peer reviews:

Eric Lenior (AIU Holding)

Fred Henselwood (NOVA Chemicals)

John Alderman (RRS Engineering)

Lisa Morrison (BP International Limited)

Mark Whitney (ABS Consulting)

William Vogtman (SIS-TECH Solutions)

David Clark (DuPont, emeritus)

A NOTE ON NOMENCLATURE AND UNITS

The equations in this volume are from a number of reference sources, not all of which use consistent nomenclature (symbols) and units. In order to facilitate comparisons within sources, the conventions of each source were presented unchanged.

Nomenclature and units are given after each equation (or set of equations) in the text. Readers should ensure that they use the proper values when applying these equations to their problems.

CHAPTER 1

INTRODUCTION

The American Institute of Chemical Engineers (AIChE) has been involved with process safety and loss control for chemical and petrochemical plants for more than forty years. Through its strong ties with process designers, builders, operators, safety professionals, and academia, AIChE has enhanced communication and fostered improvements in the safety standards of the industry. Its publications and symposia on causes of accidents and methods of prevention have become information resources for the chemical engineering profession.

Early in 1985, AIChE established the Center for Chemical Process Safety (CCPS) to serve as a focus for a continuing program for process safety. The first CCPS project was the publication of a document entitled Guidelines for Hazard Evaluation Procedures. In 1987, Guidelines for Use of Vapor Cloud Dispersion Models was published, and in 1989, Guidelines for Chemical Process Quantitative Risk Analysis and Guidelines for Technical Management of Chemical Process Safety were published.

The first edition of this book was published in 1994, and it remains the most in-depth technical material produced in a CCPS project.

This current edition is intended to provide an overview of methods for practicing engineers to estimate the characteristics of a flash fire, vapor cloud explosion (VCE), pressure vessel burst (PVB), and boiling-liquid-expanding-vapor explosion (BLEVEs). This edition summarizes and evaluates these methods, identifies areas in which information is lacking, and provides an overview of ongoing work in the field. The arrangement of this book is considerably different from previous editions, including separating pressure vessel bursts into its own chapter.

For a person new to the field of explosion and flash fire hazard evaluation this book provides a starting point for understanding the phenomena covered and presents methods for calculating the possible consequences of incidents. It provides an overview of research in the field and numerous references for readers with more experience. Managers will be able to utilize this book to develop a basic understanding of the governing phenomena, the calculational methods to estimate consequences, and the limitations of each method.

Chapter 2 of this book was written for managers, and it contains an overview of the hazards associated with flash fires, vapor cloud explosions (VCEs), pressure vessel bursts (PVBs), and boiling liquid expanding vapor explosions (BLEVEs). Chapter 3 provides a review of case histories involving these hazards. These case histories illustrate the conditions present at the time of the event, highlighting the serious consequences of such events and the need for evaluation of the hazards.

Chapter 4 provides an overview of the basic concepts associated with flash fires, VCEs, PVBs and BLEVEs. This chapter includes a discussion of dispersion, ignition, fires, thermal radiation, VCEs, and blast waves.

Chapters 5 through 8 separately address the phenomena of each type of hazard (i.e., flash fires, VCEs, PVBs and BLEVEs). These chapters include a description of the relevant phenomena, an overview of the related past and present experimental work and theoretical research, and selected consequence estimation methodologies. Each chapter includes sample problems to illustrate application of the methodologies presented. References are provided in Chapter 9.

The goal of this book is to provide the reader with an adequate understanding of the basic physical principles of flash fires and explosions and the current state of the art in hazard estimation methodologies. It is not the goal of this book to provide a comprehensive discussion of all of the experimental work and theoretical research that has been performed in the field of flash fire and explosion evaluation.

This book does not address subjects such as toxic effects, confined explosions (e.g., an explosion within a building), dust explosions, runaway reactions, condensed-phase explosions, pool fires, jet flames, or structural responses of buildings. Furthermore, no attempt is made to address frequency or likelihood of accident scenarios. References to other works related to these topics are provided for the interested reader.