Safe Design and Operation of Process Vents and Emission Control Systems

Transcription

1 Safe Design and Operation of Process Vents and Emission Control Systems

2 Safe Design and Operation of Process Vents and Emission Control Systems Center for Chemical Process Safety of the American Institute of Chemical Engineers CCP S CENTER FOR CHEMICAL PROCESS SAFETY An AlChE industry Technology Alliance A JOHN WILEY & SONS, INC., PUBLICATION

3 Copyright by John Wiley &. Sons, 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. 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, scanning, or otherwise, except as permitted under Section 107 or 108 ofthe 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) , fax (978) , or on the web at Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 1 I 1 River Street, Hoboken, NJ 07030, (201) , fax (201) , or online at Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neilher the publisher nor author shall be liable for any loss of profit or any other commercial damages,, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) , outside the United States at (317) or fax (317) Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic format. For information about Wiley products, visit our web'site at Library of Congress Cataloging-in-Publication Data: Safe design and operation of process vents and emission control systems i Center for Chemical Process Safety, p. cm. Includes index. ISBN-13: (cloth) ISBN-10: (cloth) 1. Chemical industry-fume control. 2. Chemical plants-heating and ventilation-safety measures. 3. Chemical industry-fires and fire prevention. 4. Air-Pollution. 5. Chemical plants-piping. 6. Air ducts-design and construction. 1. American Institute of Chemical Engineers Center for Chemical Process Safety. TH7684.C44.S '.2804-& Printed in the United States of America. I

4 DISCLAIMER 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, neither the American Institute of Chemical Engineers, its consultants, CCPS Technical Steering Committee and Subcommittee members, their employers, their employers' officers and directors, nor [Contractor name] and its employees 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 Risk, Reliability and Safety Engineering, LLC, and its employees, and (2) the user of this document, the user accepts any legal liability or responsibility whatsoever for the consequence of its use or misuse. V

5 CONTENTS Preface Acknowledgment XIV xv Introduction 1.1 Objective 1.2 Relationship to Other CCPS Publications 1.3 Industnes and Operations Covered 1.4 Intended Audience 1.5 How to Use this Book 1.6 References Management Overview 2.1. Impact on Vent Header Systems Normal Process and Emergency Systems 3.1 Types of Vent Header Systems Normal Process Vent Header Systems Emergency Vent Header Systems Combined Vent Header Systems Considerations 3.2 Design Philosophy Design Sequence Hazards Associated with Combining Vent Streams Inherent Safety Flammability and Combustibility

6 Contents Toxicity Reactivity Regulatory Issues 3.3 Reference Combustion and Flammability 4.1 Flammable Limits Mixture Stoichiometry Factors Influencing Flammable Limits Flammable Limit Variability Effects of Temperature on Flammable Limits Effects of Pressure on Flammable Limits Flammable Limits of Combined Gas Streams Cool Flame Hybrid Mixtures 4.2 Limiting Oxidant Concentration 4.3 Deflagrations 4.4 Pressure Piling 4.5 Detonation Phenomena Deflagration to Detonation Transition (DDT) and Run-Up Distance Overdnven and Stable Detonations Detonation Cell Size 4.6 References UNDERSTANDING REQUIREMENTS 5.1 Understanding the Sources Identify Vent Sources Identify Normal Process Vent Streams Normal Process Vent System, Design Case Scenario Define Interface Requirements Identify Hazard Scenarios That Could Result in Emergency Venting Vent Gas Characteristics for Emergency Venting Emergency Venting Design Case Scenario Liquid Entrainment or Condensation in Normal Process Vent Headers Two-Phase Venting viii

7 Contents Flammable Gases and Vapors Toxic and Noxious Materials Reactive Systems 5.2 Regulatory Issues Historical Background Brief Review of Laws and Regulations Improved Air Quality 5.3 At-Source Treatment Options 5.4 Combining Vent Streams 5.5 End-of-Line Treatment Systems 5.6 Specify Design Requirements 5.7 References DESIGN APPROACH Design Basis 85 Merging Vent Streams Features Favorable for Merging Steams Features that do not Favor Merging Streams 87 Vent Header Systems Handling Flammable Materials Explosion Prevention Operating Fuel Lean Operating Inerted Operating Fuel Rich Oxidizers Other Than Oxygen Explosion Protection Ignition Sources 117 Vent Header Systems Handling Toxic Gases Operating Pnnciples for Header Systems Handling Toxic Gases Piping Design Combined Relief Valve and Rupture Disk Devices 121 Reactive Systems Reactive Systems Design Considerations 121 Mechanical Design Considerations Vent Header Pipe Specifications Vent Header Supports Stresses on Vent Header Piping Shock Waves Downstream of Rupture Disks Corrosion Header Operating Pressure and Pressure Drop 125 ix

8 Contents Thermal Stresses and Low Temperature Embrittlement Liquid Knock-Out and Drainage Expansion Joints and Flexible Connections Valves in the Vent Header System 6.7 References Treatment and Disposal Systems Selection of Treatment and Disposal Methods 133 Collection Containment Collection with Venting Dump and Catch Tanks Blowdown Drums and Tanks Quench Drums Quench Pools Advantages and Disadvantages - Collection Systems 147 Physical Separation Vapor-Liquid Gravity Separators Knock-Out Tanks and Drums Mist Eliminators Cyclones Advantages and Disadvantages - Physical Separators 152 Absorption Spray Towers Tray Towers Packed-Bed Scrubber Venturi Scrubbers Advantages and Disadvantages - Absorption Systems 155 Adsorption Advantages and Disadvantages - Carbon Adsorption 158 Recovery Condensing Systems Gas Recovery Systems Advantages and Disadvantages - Recovery Systems 165 Thermal Destruction Flares Thermal and Catalyhc Oxidizers Process Heaters Used for Thermal Destruction Advantages and Disadvantages -Thermal Destruction Systems 175 X

9 Contents 7.8 Dispersion of Vent Gas Design and Safety Considerations Atmospheric Dispersion Design Advantages and Disadvantages - Dispersion to Atmosphere References 179 HAZARD ANALYSIS AND CONSEQUENCE ASSESSMENT 8.1 Hazard Analysis Methods 8.2 Hazard Analysis Process Identification of Causes Development of Consequences Estimation of Hazard Scenario Risk 8.3 Consequence Assessment Techniques 8.4 References Operations and Maintenance 9.1 Daily Inspections 9.2 Scheduled Inspections and Maintenance Materials Build-Up Pressure Relief Valves and Rupture Disks Conservation Vents Explosion Prevention Systems Fast Acting Valves and Chemical Isolation Systems Explosion Relief Panels Inemng Systems Instrument and Controls Low Point Drains Corrosion and Erosion Structural Supports for Vent Headers Insulation and Heat Tracing 9.3 Management of Change 9.4 References

10 Contents Acronyms and Abbreviations 203 Glossary 207 Selected US Environmental Air Pollution Control Regulations 21 5 Vent Header Design Checklist 225 Normal Vent Header Source Control and Configuration Examples 233 PHA HAZOP Deviation Table 243 Worked Examples G1. Inerted Flammable Liguid Storage G2. Flamable Liquid Process Operating Fuel Lean G3. Flamable Liquid Process Operating Fuel Rich G4. Flamable Liquid Process Operating Fuel Rich G5. Refinery Example: Crude and Vacuum Units G6. Refinery Example: Coker Unit and Gas Processing Plant G7. Reactive System Past Incidents H1. Combustion Incidents H2. Reactive Chemical Incidnets H3. Vacuum Failures H4. References

11 Contents Historical Perspective on Air Pollution Control 11. Historical Background on Air Pollution 12. Brief Review of Laws and Regulations 13. Improved Air Quality 14. References

12 PREFACE The American Institute of Chemical Engineers (AIChE) has helped chemical plants, petrochemical plants, and refineries address the issues of process safety and loss control for over 50 years. Through its ties with process designers, plant constructors, facility operators, safety professionals, and academia, AIChE has enhanced communication and fostered improvement in the high safety standards of the industry. AIChE's publications and symposia have become an information resource for the chemical engineering profession on the causes of incidents and means of prevention. The Center for Chemical Process Safety (CCPS), an Industry Technology Alliance of AIChE, was established in 1985 to develop and disseminate technical information for use in the prevention of major chemical accidents. CCPS is supported by a diverse group of industrial sponsors in the chemical industry and related industries who provide the necessary funding and professional guidance for its projects. The CCPS Technical Steering Committee and the technical subcommittees oversee individual projects selected by CCPS. Professional representatives from sponsoring companies staff the subcommittees and a member of the CCPS staff coordinates their activities. Since its founding, CCPS has published many volumes in its "Guidelines" series and in smaller "Concept" series texts. Although most CCPS books are written for engineers in plant design and operations and address scientific techniques and engineering practices, several guidelines cover subjects related to chemical process safety management. A successful process safety program relies upon committed managers at all levels of a company who view process safety as an integral part of overall business management and act accordingly. A team of experts from the chemical industry drafted the chapters for this concept book and provided real world exarr.ples to illustrate some of the tools and methods used in their profession. The subcommittee members reviewed the content extensively and industry peers evaluated this book to help ensure it represents a factual accounting of industry best practices. xiv

13 ACKNOWLEDGEMENTS The American Institute of Chemical Engineers wishes to thank the Center for Chemical Process Safety (CCPS) and those involved in its operation, including its many sponsors whose funding made this project possible; the members of its Technical Steering Committee who conceived of and supported this concept book project, and the members of its Process Vent and Emission Control Systems Subcommittee. The members of the CCPS Process Vents and Emissions Control Subcommittee were: Christopher Lowe, Chair, Syngenta Crop Protection, lnc. Danny Bice, The Dow Chemical Company James Case, Air Products and Chemicals, Inc. David Kirby, Baker Engineering and Risk Consul tants Peter Lodal, Eastman Chemical Company Ray Mendelsohn, DuPont Edward Zamejc, BP John Davenport was the CCPS staff liaison and was responsible for overall administration of the project. Risk, Reliability and Safety Engineering (RRS), of League City, Texas was contracted to write this concept book. The principal RRS authors of this guideline were: John Birtwistle Tim McNamara Christy Franklyn Additional RRS staff that supported this project includes Donna Hamilton and Cathy Malek. CCPS also gratefully acknowledges the comments and suggestions received from the following peer reviewers; their insights, comments, and suggestions helped ensure a balanced perspective to this concept book: John Alderman, Risk, Reliability and Safety Engineering James Case, Air Products and Chemicals, lnc. Stan Grossel, Process Safety and Design, Inc. xv

14 Acknowledgments Neil McNaughton, Innovene William Olsen, Merck and Company, Inc. Tony Thompson, Monsanto The members of the CCPS Process Vent and Emission Control Systems and the peer reviewers wish to thank their employers for allowing them to participate in this project. xv i