Guidelines for Pressure Relief and Effluent Handling Systems

This book is one in a series of process safety guideline and concept books published by the Center for Chemical Process Safety (CCPS) in cooperation with the Design Institute for Emergency Relief Systems (DIERS). Please go to www.wiley.com/ccps for a full list of titles in this series.

DISCLAIMER

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), The Design Institute for Emergency Relief Systems (DIERS), the Subcommittee members, its consultants, the Center for Chemical Process Safety (CCPS) Technical Steering Committee and 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) DIERS, the DIERS user group, the authors, its consultants, (2) AIChE, CCPS Technical Steering Committee and Subcommittee members, their employers, their employers officers and directors, and (3) the user of this document, the user accepts any legal liability or responsibility whatsoever for the consequence of its use or misuse.

GUIDELINES FOR

PRESSURE RELIEF AND EFFLUENT HANDLING

SYSTEMS

SECOND EDITION

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.

Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data:

Names: American Institute of Chemical Engineers. Center for Chemical Process

Safety, author.

Title: Guidelines for pressure relief and effluent handling systems / Center

for Chemical Process Safety of the American Institute of Chemical

Engineers.

Description: Second edition. | New York, NY : John Wiley & Sons, Inc., [2017]

| Includes bibliographical references and index.

Identifiers: LCCN 2017002351 (print) | LCCN 2017004079 (ebook) | ISBN

9780470767733 (cloth) | ISBN 9781119330264 (pdf) | ISBN 9781119330295

(epub)

Subjects: LCSH: Chemical plants--Waste disposal. | Hazardous

wastes--Management. | Relief valves. | Sewage disposal.

Classification: LCC TD899.C5 G85 2017 (print) | LCC TD899.C5 (ebook) | DDC

660.028/6--dc23

LC record available at https://lccn.loc.gov/2017002351

DEDICATIONS

Dr. Michael A. Grolmes (Centaurus Technology), an original employee of Fauske & Associates LLC, who was principally responsible for development and documentation of much of the DIERS two-flow technology, the large-scale blowdown and reactive experimental program, and the SAFIRE computer program.

Dr. Joseph C. Leung (LeungInc), an original employee of Fauske & Associates LLC, who was jointly responsible for development of the DIERS Bench-Scale Apparatus (Later the VSP) and the reported experimental results as well as development of the Omega Method for calculating two-phase flows and sizing emergency relief systems for runaway reactions.

Dr. Georges A. Melhem (President and CEO, ioMosaic Corporation) who developed the SuperChems™ family (EXPERT, DIERS, and Lite) of computer programs. These programs are widely used for various process safety studies and sizing of emergency relief and flare systems. The SuperChems™ for DIERS computer program was made available for licensing and distribution by AIChE. The SuperChems™ for DIERS Lite computer program was made available to AIChE for distribution and licensing with this book. Dr. Melhem was co-editor of this guideline and the 1st (1995), 2nd (1998) and 3rd (2005) International Symposium Proceedings published by AIChE / DIERS.

ioMosaic Corporation provided editorial, administrative, and significant financial support for the publication of this guideline and the 1st (1995), 2nd (1998) and 3rd (2005) International Symposium Proceedings published by AIChE / DIERS.

Fauske & Associates LLC, led by Dr. Hans K. Fauske, was the DIERS contractor responsible for the original development and documentation of the DIERS technology that changed the engineering paradigm for design of emergency relief system involving runaway reaction and two-phase flow. FAI recently celebrated their 35th anniversary of continuous technology development and support of safety improvements for the chemical process and nuclear industries.

Contents

Cover

Disclaimer

Title

Copyright

Dedication

Contents

List of Figures

List of Tables

Preface

Acknowledgements

In Memoriam

Files on the Web Accompanying This Book

1 Introduction

1.1 Objective

1.2 Scope

1.3 Design Codes and Regulations, and Sources of Information

1.4 Organization of This Book

1.5 General Pressure and Relief System Design Criteria

1.5.1 Process Hazard Analysis

1.5.2 Process Safety Information

1.5.3 Problems Inherent in Pressure Relief and Effluent Handling Systems

2 Relief Design Criteria and Strategy

2.1 Limitations of the Technology

2.2 General Pressure Relief Strategy

2.2.1 Mechanism of Pressure Relief

2.2.2 Approach to Design

2.2.3 Limitations of Systems Actuated by Pressure

2.3 Codes, Standards, and Guidelines

2.3.1 Scope of Principal USA Documents

2.3.2 General Provisions

2.3.3 Protection by System Design

2.4 Relief Device Types and Operation

2.4.1 General Terminology

2.4.2 Pressure Relief Valves

2.4.3 Rupture Disk Devices

2.4.4 Devices in Combination (Series)

2.4.5 Low Pressure Relief Valves & Vents

2.4.6 Miscellaneous Relief System Components

2.4.7 Selection of Pressure Relief Devices

2.5 Relief System Layout

2.5.1 General Code Requirements

2.5.2 Pressure Relief Valves

2.5.3 Rupture Disk Devices

2.5.4 Low-Pressure Devices

2.5.5 Devices in Series

2.5.6 Devices in Parallel

2.5.7 Header Systems

2.5.8 Mechanical Integrity

2.5.9 Material Selection

2.5.10 Drainage and Freeze-up Provisions

2.5.11 Noise

2.6 Design Flows and Code Provisions

2.6.1 Safety Valves

2.6.2 Incompressible Liquid Flow

2.6.3 Low Pressure Devices

2.6.4 Rupture Disk Devices

2.6.5 Devices in Combination

2.6.6 Miscellaneous Nonreclosing Devices

2.7 Scenario Selection Considerations

2.7.1 Events Requiring Relief Due to Overpressure

2.7.2 Design Scenarios

2.8 Fluid Properties and System Characterization

2.8.1 Property Data Sources/Determination/Estimation

2.8.2 Pure-Component Properties

2.8.3 Mixture Properties

2.8.4 Phase Behavior

2.8.5 Chemical Reaction

2.8.6 Miscellaneous Fluid Characteristics

2.9 Fluid Behavior in Vessel

2.9.1 Accounting for Chemical Reactions

2.9.2 Two-Phase Venting Conditions and Effects

2.10 Flow of Fluids Through Relief Systems

2.10.1 Conditions for Two-Phase Flow

2.10.2 Nature of Compressible Flow

2.10.3 Stagnation Pressure and Non-recoverable Pressure Loss

2.10.4 Flow Rate to Effluent Handling System

2.11 Relief System Reliability

2.11.1 Relief Device Reliability

2.11.2 System Reliability

3 Requirements for Relief System Design

3.1 Introduction

3.1.1 Required Background

3.2 Vessel Venting Background

3.2.1 General Considerations

3.2.2 Schematics and Principle Variables, Properties and Parameters

3.2.3 Basic Mass and Energy Balances

3.2.4 Physical and Thermodynamic Properties

3.2.5 Energy Input or Output

3.2.6 Solution Methods Using Computer Tools

3.2.7 Mass and Energy Balance Simplifications

3.2.8 Limiting Cases

3.2.9 Vapor/Liquid Disengagement

3.3 Venting Requirements for Nonreacting Cases

3.3.1 Heating or Cooling of a Constant Volume Vessel

3.3.2 Excess Inflow/Outflow

3.3.3 Additional Techniques and Considerations

3.4 Calorimetry for Emergency Relief System Design

3.4.1 Executive Summary

3.4.2 Runaway Reaction Effects

3.4.3 Reaction Basics

3.4.4 Reaction Screening and Chemistry Identification

3.4.5 Measuring Reaction Rates

3.4.6 Experimental Test Design

3.4.7 Calorimetry Data Interpretation and Analysis

3.5 Venting Requirements for Reactive Cases

3.5.1 Executive Summary

3.5.2 Overview of Reactive Relief Load

3.5.3 Analytical Methods

3.5.4 Dynamic Computer Modeling

3.5.5 Closing Comment

4 Methods for Relief System Design

4.1 Introduction

4.1.1 Relief System Sizing Computational Strategy and Tools for Relief Design

4.2 Manual and Spreadsheet Methods for Relief Valve Sizing

4.2.1 Relief Valve Sizing Fundamental Equations

4.2.2 Two-Phase Flow Methods

4.2.3 Relief Valve Sizing - Discharge Coefficient

4.2.4 Relief Valve Sizing - Choking in Nozzle and Valve Exit

4.3 Miscellaneous

4.3.1 Low-Pressure Devices - Liquid Flow

4.3.2 Low-Pressure Devices - Gas Flow

4.3.3 Low-Pressure Devices - Two-Phase Flow

4.3.4 Low-Pressure Devices - Associated Piping

4.4 Piping

4.4.1 Piping - Fundamental Equations

4.4.2 Piping - Pipe Friction Factors

4.4.3 Incompressible (Liquid) Flow

4.4.4 Piping Adiabatic Compressible Flow

4.4.5 Isothermal Compressible Flow

4.4.6 Homogeneous Two-Phase Pipe Flow

4.4.7 Piping - Separated Two-Phase Flows

4.4.8 Slip/Holdup

4.4.9 Piping - Temperature Effects

4.5 Rupture Disk Device Systems

4.5.1 Rupture Disks - Nozzle Model

4.5.2 Rupture Disks - Pipe Model

4.6 Multiple Devices

4.6.1 Multiple Devices in Parallel

4.6.2 Multiple Devices - Rupture Disk Device Upstream of a PRV

4.6.3 Multiple Devices - Rupture Disk Device Downstream of a PRV

4.7 Worked Example Index

5 Additional Considerations for Relief System Design

5.1 Introduction

5.2 Reaction Forces

5.3 Background

5.4 Selection of Design Case

5.5 Design Methods

5.5.1 Steady State Exit Force from Flow Discharging to the Atmosphere

5.5.2 Dynamic Load Factor

5.6 Selection of Design Flow Rate and Dynamic Load Factor

5.6.1 Rupture Disks

5.6.2 Safety Relief Valves

5.7 Transient Forces on Relief Device Discharge Piping

5.7.1 Liquid Relief

5.7.2 Gas Relief

5.7.3 Two-Phase Flow

5.8 Pipe Tension

5.8.1 Safety Relief Valves

5.8.2 Rupture Disks

5.9 Real Gases

5.10 Changes in Pipe Size

5.11 Location of Anchors

5.12 Exit Geometry

5.13 Worked Examples

6 Handling Emergency Relief Effluents

6.1 General Strategy

6.2 Basis for Selection of Equipment

6.3 Determining if Direct Discharge to Atmosphere is Acceptable

6.4 Factors That Influence Selection of Effluent Treatment Systems

6.4.1 Physical and Chemical Properties

6.4.2 Two-Phase Flow and Foaming

6.4.3 Passive or Active Systems

6.4.4 Technology Status and Reliability

6.4.5 Discharging to a Common Collection System

6.4.6 Plant Geography

6.4.7 Space Availability

6.4.8 Turndown

6.4.9 Vapor-Liquid Separation

6.4.10 Possible Condensation and Vapor-Condensate Hammer

6.4.11 Time Availability

6.4.12 Capital and Continuing Costs

6.5 Methods of Effluent Handling

6.5.1 Containment

6.5.2 Direct Discharge to Atmosphere

6.5.3 Vapor-Liquid Separators

6.5.4 Quench Tanks

6.5.5 Scrubbers (Absorbers)

6.5.6 Flares

7 Design Methods for Handling Effluent from Emergency Relief Systems

7.1 Design Basis Selection

7.2 Total Containment Systems

7.2.1 Containment in Original Vessel

7.2.2 Containment in External Vessel (Dump Tank or Catch Tank)

7.3 Relief Devices, Discharge Piping, and Collection Headers

7.3.1 Corrosion

7.3.2 Brittle Metal Fracture

7.3.3 Deposition

7.3.4 Vibration

7.3.5 Cleaning

7.4 Vapor-Liquid Gravity Separators

7.4.1 Separator Inlet Velocity Considerations

7.4.2 Horizontal Gravity Separators

7.4.3 Vertical Gravity Separators

7.4.4 Separator Safety Considerations and Features

7.4.5 Separator Vessel Design and Instrumentation

7.5 Cyclone Separators

7.5.1 Droplet Removal Efficiency

7.5.2 Design Procedure

7.5.3 Cyclone Separator Sizing Procedure

7.5.4 Alternate Cyclone Separator Design Procedure

7.5.5 Cyclone Reaction Force

7.6 Quench Pools

7.6.1 Design Procedure Overview

7.6.2 Design Parameter Interrelations

7.6.3 Quench Pool Liquid Selection

7.6.4 Quench Tank Operating Pressure

7.6.5 Quench Pool Heat Balance

7.6.6 Quench Pool Dimensions

7.6.7 Sparger Design

7.6.8 Handling Effluent from Multiple Relief Devices

7.6.9 Reverse Flow Problems

7.6.10 Vapor-Condensate Hammer

7.6.11 Mechanical Design Loads

7.6.12 Worked Example Index for Discharge Handling System Design

Acronyms and Abbreviations

Glossary

Nomenclature

Appendix A: SuperChems™ for DIERS Lite - Description and Instructions

A.1 Scope

A.2 Software Functions

A.2.1 Source Term Flow Calculation

A.2.2 Emergency Relief Requirement Calculations

A.2.3 Physical Properties

A.2.4 Piping Isometrics

A.2.5 Specifying Vessel Designs

A.3 Installing and Running SuperChems™

Appendix B: CCFlow, TPHEM and COMFLOW Description and Instructions

B.1 Scope

B.1.1 Uncertainties

B.2 CCFlow Calculation Options

B.2.1 Opening and Running CCFlow

B.2.2 File Operations

B.2.3 Help Files

B.2.4 Other Operations

B.2.5 CCFlow Input Menu Errata

B.3 TPHEM Calculation Options

B.3.1 Running TPHEM with File Input

B.4 COMFLOW Calculation Options

B.4.1 Running COMFLOW

Appendix C: SuperChems™ for DIERS - Description and Instructions

C.1 Scope

C.2 Software Functions

C.2.1 Main Menu Tabs

C.2.2 Define Tab

C.2.3 Dynamic Flow Simulation

C.2.4 Steady-State Flow Calculations

C.2.5 Properties Tab

C.2.6 VLE Tab

C.3 Installing and Running SuperChems™

Appendix D: Venting Requirements

D.1 Worked Examples - Emergency Venting

D.1.1 External Fire - Vapor Venting

D.1.2 Tube Rupture

D.1.3 Literature Examples for Non-Reactive Cases

D.2 Venting Requirements for Reactive Cases

D.3 Relief Valve Sizing Examples

D.3.1 Incompressible Liquid Flow (with Viscosity Correction)

D.3.2 Real Gas Flow

D.3.3 Supercritical Fluid Flow

D.3.4 Non-Flashing (Frozen) Choked Flow

D.3.5 Non-Flashing (Frozen) Non-choked Flow

D.3.6 Equilibrium Flow of Single-Component Fluid

D.3.7 Non-Equilibrium Flow of Single-Component Fluid

D.3.8 Multicomponent Fluid Flow

D.3.9 Equilibrium Flow of One-Component Fluid (Low Subcooled Liquid Flow)

D.3.10 Equilibrium Flow of Single-Component Fluid (Highly Subcooled Liquid Flow)

D.3.11 Single-Component Vapor Flow with Retrograde Condensation

D.4 Piping Flow Examples

D.4.1 Two-Phase Gas-Liquid Flow with Conventional Multiple Chokes

D.4.2 Real Gas Flow with Multiple Chokes

D.4.3 Flow of High Viscosity Liquid

D.5 Reaction Forces

D.5.1 PRV with Viscous Liquid Flow – Steady Forces

D.5.2 PRV with Real Gas Flow – Steady Forces

D.5.3 RD with Liquid Flow – Steady and Transient Forces

D.5.4 RD with Air Flow – Steady and Transient Forces

D.5.5 PRV with Steam Flow – Steady and Transient Forces

D.5.6 PRV with Two-Phase Flow – Steady and Transient Forces and Piping Design Pressure

D.5.7 PRV with Two-Phase Flow – Steady and Transient Forces and Piping Design Pressure

D.5.8 RD with Two-Phase Flow – Steady and Transient Forces and Piping Design Pressure

Appendix E: Worked Examples – Effluent Handling

E.1 Phase Separator and Quench Tank Design Examples

E.1.1 Example Problem Statement

E.1.2 Given Conditions

E.1.3 Quench Pool Design

E.1.4 Gravity Separator Design

E.1.5 Cyclone Separator Design

E.1.6 Summary

References

Index

Eula

CONTENTS

List of Figures

List of Tables

Preface

Acknowledgements

In Memoriam

Files on the Web Accompanying This Book

Introduction

1.1 Objective

1.2 Scope

1.3 Design Codes and Regulations, and Sources of Information

1.4 Organization of This Book

1.5 General Pressure and Relief System Design Criteria

1.5.1 Process Hazard Analysis

1.5.2 Process Safety Information

1.5.3 Problems Inherent in Pressure Relief and Effluent Handling Systems

Relief Design Criteria and Strategy

2.1 Limitations of the Technology

2.2 General Pressure Relief Strategy

2.2.1 Mechanism of Pressure Relief

2.2.2 Approach to Design

2.2.3 Limitations of Systems Actuated by Pressure

2.3 Codes, Standards, and Guidelines

2.3.1 Scope of Principal USA Documents

2.3.2 General Provisions

2.3.3 Protection by System Design

2.4 Relief Device Types and Operation

2.4.1 General Terminology

2.4.2 Pressure Relief Valves

2.4.3 Rupture Disk Devices

2.4.4 Devices in Combination (Series)

2.4.5 Low Pressure Relief Valves & Vents

2.4.6 Miscellaneous Relief System Components

2.4.7 Selection of Pressure Relief Devices

2.5 Relief System Layout

2.5.1 General Code Requirements

2.5.2 Pressure Relief Valves

2.5.3 Rupture Disk Devices

2.5.4 Low-Pressure Devices

2.5.5 Devices in Series

2.5.6 Devices in Parallel

2.5.7 Header Systems

2.5.8 Mechanical Integrity

2.5.9 Material Selection

2.5.10 Drainage and Freeze-up Provisions

2.5.11 Noise

2.6 Design Flows and Code Provisions

2.6.1 Safety Valves

2.6.2 Incompressible Liquid Flow

2.6.3 Low Pressure Devices

2.6.4 Rupture Disk Devices

2.6.5 Devices in Combination

2.6.6 Miscellaneous Nonreclosing Devices

2.7 Scenario Selection Considerations

2.7.1 Events Requiring Relief Due to Overpressure

2.7.2 Design Scenarios

2.8 Fluid Properties and System Characterization

2.8.1 Property Data Sources/Determination/Estimation

2.8.2 Pure-Component Properties

2.8.3 Mixture Properties

2.8.4 Phase Behavior

2.8.5 Chemical Reaction

2.8.6 Miscellaneous Fluid Characteristics

2.9 Fluid Behavior in Vessel

2.9.1 Accounting for Chemical Reactions

2.9.2 Two-Phase Venting Conditions and Effects

2.10 Flow of Fluids Through Relief Systems

2.10.1 Conditions for Two-Phase Flow

2.10.2 Nature of Compressible Flow

2.10.3 Stagnation Pressure and Non-recoverable Pressure Loss

2.10.4 Flow Rate to Effluent Handling System

2.11 Relief System Reliability

2.11.1 Relief Device Reliability

2.11.2 System Reliability

Requirements for Relief System Design

3.1 Introduction

3.1.1 Required Background

3.2 Vessel Venting Background

3.2.1 General Considerations

3.2.2 Schematics and Principle Variables, Properties and Parameters

3.2.3 Basic Mass and Energy Balances

3.2.4 Physical and Thermodynamic Properties

3.2.5 Energy Input or Output

3.2.6 Solution Methods Using Computer Tools

3.2.7 Mass and Energy Balance Simplifications

3.2.8 Limiting Cases

3.2.9 Vapor/Liquid Disengagement

3.3 Venting Requirements for Nonreacting Cases

3.3.1 Heating or Cooling of a Constant Volume Vessel

3.3.2 Excess Inflow/Outflow

3.3.3 Additional Techniques and Considerations

3.4 Calorimetry for Emergency Relief System Design

3.4.1 Executive Summary

3.4.2 Runaway Reaction Effects

3.4.3 Reaction Basics

3.4.4 Reaction Screening and Chemistry Identification

3.4.5 Measuring Reaction Rates

3.4.6 Experimental Test Design

3.4.7 Calorimetry Data Interpretation and Analysis

3.5 Venting Requirements for Reactive Cases

3.5.1 Executive Summary

3.5.2 Overview of Reactive Relief Load

3.5.3 Analytical Methods

3.5.4 Dynamic Computer Modeling

3.5.5 Closing Comment

Methods for Relief System Design

4.1 Introduction

4.1.1 Relief System Sizing Computational Strategy and Tools for Relief Design

4.2 Manual and Spreadsheet Methods for Relief Valve Sizing

4.2.1 Relief Valve Sizing Fundamental Equations

4.2.2 Two-Phase Flow Methods

4.2.3 Relief Valve Sizing - Discharge Coefficient

4.2.4 Relief Valve Sizing - Choking in Nozzle and Valve Exit

4.3 Miscellaneous

4.3.1 Low-Pressure Devices - Liquid Flow

4.3.2 Low-Pressure Devices - Gas Flow

4.3.3 Low-Pressure Devices - Two-Phase Flow

4.3.4 Low-Pressure Devices - Associated Piping

4.4 Piping

4.4.1 Piping - Fundamental Equations

4.4.2 Piping - Pipe Friction Factors

4.4.3 Incompressible (Liquid) Flow

4.4.4 Piping Adiabatic Compressible Flow

4.4.5 Isothermal Compressible Flow

4.4.6 Homogeneous Two-Phase Pipe Flow

4.4.7 Piping - Separated Two-Phase Flows

4.4.8 Slip/Holdup

4.4.9 Piping - Temperature Effects

4.5 Rupture Disk Device Systems

4.5.1 Rupture Disks - Nozzle Model

4.5.2 Rupture Disks - Pipe Model

4.6 Multiple Devices

4.6.1 Multiple Devices in Parallel

4.6.2 Multiple Devices - Rupture Disk Device Upstream of a PRV

4.6.3 Multiple Devices - Rupture Disk Device Downstream of a PRV

4.7 Worked Example Index

Additional Considerations for Relief System Design

5.1 Introduction

5.2 Reaction Forces

5.3 Background

5.4 Selection of Design Case

5.5 Design Methods

5.5.1 Steady State Exit Force from Flow Discharging to the Atmosphere

5.5.2 Dynamic Load Factor

5.6 Selection of Design Flow Rate and Dynamic Load Factor

5.6.1 Rupture Disks

5.6.2 Safety Relief Valves

5.7 Transient Forces on Relief Device Discharge Piping

5.7.1 Liquid Relief

5.7.2 Gas Relief

5.7.3 Two-Phase Flow

5.8 Pipe Tension

5.8.1 Safety Relief Valves

5.8.2 Rupture Disks

5.9 Real Gases

5.10 Changes in Pipe Size

5.11 Location of Anchors

5.12 Exit Geometry

5.13 Worked Examples

Handling Emergency Relief Effluents

6.1 General Strategy

6.2 Basis for Selection of Equipment

6.3 Determining if Direct Discharge to Atmosphere is Acceptable

6.4 Factors That Influence Selection of Effluent Treatment Systems

6.4.1 Physical and Chemical Properties

6.4.2 Two-Phase Flow and Foaming

6.4.3 Passive or Active Systems

6.4.4 Technology Status and Reliability

6.4.5 Discharging to a Common Collection System

6.4.6 Plant Geography

6.4.7 Space Availability

6.4.8 Turndown

6.4.9 Vapor-Liquid Separation

6.4.10 Possible Condensation and Vapor-Condensate Hammer

6.4.11 Time Availability

6.4.12 Capital and Continuing Costs

6.5 Methods of Effluent Handling

6.5.1 Containment

6.5.2 Direct Discharge to Atmosphere

6.5.3 Vapor-Liquid Separators

6.5.4 Quench Tanks

6.5.5 Scrubbers (Absorbers)

6.5.6 Flares

Design Methods for Handling Effluent from Emergency Relief Systems

7.1 Design Basis Selection

7.2 Total Containment Systems

7.2.1 Containment in Original Vessel

7.2.2 Containment in External Vessel (Dump Tank or Catch Tank)

7.3 Relief Devices, Discharge Piping, and Collection Headers

7.3.1 Corrosion

7.3.2 Brittle Metal Fracture

7.3.3 Deposition

7.3.4 Vibration

7.3.5 Cleaning

7.4 Vapor-Liquid Gravity Separators

7.4.1 Separator Inlet Velocity Considerations

7.4.2 Horizontal Gravity Separators

7.4.3 Vertical Gravity Separators

7.4.4 Separator Safety Considerations and Features

7.4.5 Separator Vessel Design and Instrumentation

7.5 Cyclone Separators

7.5.1 Droplet Removal Efficiency

7.5.2 Design Procedure

7.5.3 Cyclone Separator Sizing Procedure

7.5.4 Alternate Cyclone Separator Design Procedure

7.5.5 Cyclone Reaction Force

7.6 Quench Pools

7.6.1 Design Procedure Overview

7.6.2 Design Parameter Interrelations

7.6.3 Quench Pool Liquid Selection

7.6.4 Quench Tank Operating Pressure

7.6.5 Quench Pool Heat Balance

7.6.6 Quench Pool Dimensions

7.6.7 Sparger Design

7.6.8 Handling Effluent from Multiple Relief Devices

7.6.9 Reverse Flow Problems

7.6.10 Vapor-Condensate Hammer

7.6.11 Mechanical Design Loads

7.6.12 Worked Example Index for Discharge Handling System Design

Acronyms and Abbreviations

Glossary

Nomenclature

Appendix A: SuperChems™ for DIERS Lite - Description and Instructions

A.1 Scope

A.2 Software Functions

A.2.1 Source Term Flow Calculation

A.2.2 Emergency Relief Requirement Calculations

A.2.3 Physical Properties

A.2.4 Piping Isometrics

A.2.5 Specifying Vessel Designs

A.3 Installing and Running SuperChems™

Appendix B: CCFlow, TPHEM and COMFLOW Description and Instructions

B.1 Scope

B.1.1 Uncertainties

B.2 CCFlow Calculation Options

B.2.1 Opening and Running CCFlow

B.2.2 File Operations

B.2.3 Help Files

B.2.4 Other Operations

B.2.5 CCFlow Input Menu Errata

B.3 TPHEM Calculation Options

B.3.1 Running TPHEM with File Input

B.4 COMFLOW Calculation Options

B.4.1 Running COMFLOW

Appendix C: SuperChems™ for DIERS - Description and Instructions

C.1 Scope

C.2 Software Functions

C.2.1 Main Menu Tabs

C.2.2 Define Tab

C.2.3 Dynamic Flow Simulation

C.2.4 Steady-State Flow Calculations

C.2.5 Properties Tab

C.2.6 VLE Tab

C.3 Installing and Running SuperChems™

Appendix D: Venting Requirements

D.1 Worked Examples - Emergency Venting

D.1.1 External Fire - Vapor Venting

D.1.2 Tube Rupture

D.1.3 Literature Examples for Non-Reactive Cases

D.2 Venting Requirements for Reactive Cases

D.3 Relief Valve Sizing Examples

D.3.1 Incompressible Liquid Flow (with Viscosity Correction)

D.3.2 Real Gas Flow

D.3.3 Supercritical Fluid Flow

D.3.4 Non-Flashing (Frozen) Choked Flow

D.3.5 Non-Flashing (Frozen) Non-choked Flow

D.3.6 Equilibrium Flow of Single-Component Fluid

D.3.7 Non-Equilibrium Flow of Single-Component Fluid

D.3.8 Multicomponent Fluid Flow

D.3.9 Equilibrium Flow of One-Component Fluid (Low Subcooled Liquid Flow)

D.3.10 Equilibrium Flow of Single-Component Fluid (Highly Subcooled Liquid Flow)

D.3.11 Single-Component Vapor Flow with Retrograde Condensation

D.4 Piping Flow Examples

D.4.1 Two-Phase Gas-Liquid Flow with Conventional Multiple Chokes

D.4.2 Real Gas Flow with Multiple Chokes

D.4.3 Flow of High Viscosity Liquid

D.5 Reaction Forces

D.5.1 PRV with Viscous Liquid Flow – Steady Forces

D.5.2 PRV with Real Gas Flow – Steady Forces

D.5.3 RD with Liquid Flow – Steady and Transient Forces

D.5.4 RD with Air Flow – Steady and Transient Forces

D.5.5 PRV with Steam Flow – Steady and Transient Forces

D.5.6 PRV with Two-Phase Flow – Steady and Transient Forces and Piping Design Pressure

D.5.7 PRV with Two-Phase Flow – Steady and Transient Forces and Piping Design Pressure

D.5.8 RD with Two-Phase Flow – Steady and Transient Forces and Piping Design Pressure

Appendix E: Worked Examples – Effluent Handling

E.1 Phase Separator and Quench Tank Design Examples

E.1.1 Example Problem Statement

E.1.2 Given Conditions

E.1.3 Quench Pool Design

E.1.4 Gravity Separator Design

E.1.5 Cyclone Separator Design

E.1.6 Summary

References

Index

List of Tables

A

TABLE A.1-1.

TABLE A.2-1.

TABLE A.2-2.

C

TABLE C.1.

D

TABLE D.1-1..

TABLE D.3.2-1.

TABLE D.3.7-1.

E

TABLE E.1-1.

TABLE E.1-2.

TABLE E.1-3.

TABLE E.1-4.

TABLE E.1-5.

TABLE E.1-6.

TABLE E.1-7.

TABLE E.1-8.

TABLE E.1-9.

TABLE E.1-10.

TABLE E.1-11.

Chapter 2

TABLE 2.3-1.

TABLE 2.3-2.

TABLE 2.3-3.

TABLE 2.4-1.

TABLE 2.4-2.

TABLE 2.4-3.

Chapter 3

TABLE 3.3-1.

TABLE 3.3-2.

TABLE 3.3-3.

TABLE 3.4-1.

Chapter 4

TABLE 4.4-1.

TABLE 4.4-2.

Chapter 5

TABLE 5.6-1.

TABLE 5.6-2.

Chapter 6

TABLE 6.5-1.

TABLE 6.5-2.

TABLE 6.5-3.

TABLE 6.5-4.

TABLE 6.5-5.

TABLE 6.5-6.

TABLE 6.5-8.

TABLE 6.5-9.

TABLE 6.5-11.

TABLE 6.5-13.

TABLE 6.5-14.

List of Illustrations

D

FIGURE D.3.2-1. CCFlow Calculation of Isentropic Expansion Exponent

FIGURE D.3.3-1. CCFlow Calculation of Isentropic Expansion Exponent

FIGURE D.3.5-1. Mass Flux Calculation Results

FIGURE D.3.8-1. Input Data Menu

FIGURE D.3.9-1. TPHEM Output for 3-Point Interpolation Ideal Nozzle Mass Flux Calculation

FIGURE D.3.11-1. CCFlow Calculation of Isentropic Expansion Exponent

FIGURE D.4.1-1. SuperChems Wizard Input Screen After Initial Data Entry

FIGURE D.4.1-2. Middle Part of Relief Valve Specification Menu

FIGURE D.4.1-3. Upper Part of Inlet Piping Segment Specification Menu

FIGURE D.4.1-4. Piping Layout Menu

FIGURE D.4.1-5. SuperChems Case Output – Upper Part

FIGURE D.4.1-6. SuperChems Output – Second Part

FIGURE D.4.2-1. CCFlow Main Menu with Options

FIGURE D.4.2-2. CCFlow Second Menu Input

FIGURE D.4.2-3. CCFlow Third Menu Input and Results

FIGURE D.4.2-4. Using CCFlow to Determine Discharge Temperature

FIGURE D.5.1-1. Piping Forces

FIGURE D.5.2-1. Forces Acting on Relief Valve

FIGURE D.5.3-1. Piping and Reaction Forces

FIGURE D.5.3-2. Anchor and Force Locations

FIGURE D.5.4-1. Reaction Forces

FIGURE D.5.4-2. Steady State Force from COMFLOW

FIGURE D.5.4-3. Transient Force from COMFLOW

FIGURE D.5.4-4. Tension Force from COMFLOW

FIGURE D.5.5-1. Steam Being Relieved by 4N6 Safety Valve

FIGURE D.5.5-2. Steady State Force (F2) from COMFLOW

FIGURE D.5.6-1. Liquid Being Relieved by a Bellows 4N6 Safety Valve

FIGURE D.5.7-1. Two-Phase Relief by a Bellows 4N6 Safety Valve

FIGURE D.5.7-2. Exit Thrust (TPHEM)

FIGURE D.5.8-1. Reaction Force for Rupture Disk with Two-Phase Flow

FIGURE D.5.8-2. Capacity and Exit Force from TPHEM

FIGURE D.5.8-3. Transient Force from TPHEM

E

FIGURE E.1-1. Results of Process Simulation

FIGURE E.1-2. Results of Quench Pool Calculations

Chapter 2

FIGURE 2.3-1. Typical ASME BPVC Section VII Multiple Valve (Non-Fire Case) Installations

FIGURE 2.3-2. Example Adiabatic Pressure-Temperature History in a Non-vented Vessel (Computed from example phenol-formaldehyde reaction data. Booth, et al. (1980))

FIGURE 2.4-1. Conventional Pressure Relief Valve (Courtesy of Pentair Valves and Controls)

FIGURE 2.4-2. Balanced Bellows Pressure Relief Valve (Courtesy of Pentair Valves and Controls)

FIGURE 2.4-3. Liquid Relief Valve (Courtesy of Anderson Greenwood Crosby, Stafford, TX)

FIGURE 2.4-4. Pop Action Pilot Operated Pressure Relief Valve (Courtesy of Pentair Valves and Controls)

FIGURE 2.4-5a. Conventional Pre-bulged (Courtesy of Fike Corporation)

FIGURE 2.4-5b. Typical Composite Style Rupture Disk (Courtesy of Continental Disk)

FIGURE 2.4-5c. Graphite with Resin Binder (Courtesy of BS&B Safety Systems LLC)

FIGURE 2.4-5d. Forward Acting Scored (Courtesy of Fike Corporation)

FIGURE 2.4-6a. Pressure Relief Vent (Courtesy of the Groth Corporation, Stafford, Texas)

FIGURE 2.4-6b. Combination Pressure-Vacuum Relief Vent (Courtesy of the Groth Corporation, Stafford, Texas)

FIGURE 2.4-6c. Pilot Operated Relief Vent (Courtesy of the Groth Corporation, Stafford, Texas)

FIGURE 2.4-6d. Weight Loaded Emergency Relief Vent (Courtesy of the Groth Corporation, Stafford, Texas)

FIGURE 2.4-7. Selection of Pressure Relief Devices Adapted from Parry (1994)

FIGURE 2.5-1. Bleed System with Excess Flow Valve and Bleed Valve

FIGURE 2.5-2. Bleed System with Pressure Switch for Alarm Signal Generation (detects seepage and burst)

FIGURE 2.5-3. Bleed System with Burst Disk Detector for Alarm Signal Generation (some styles can also detect seepage)

FIGURE 2.7-1. Blow Through Scenario

FIGURE 2.10-1. Adiabatic Flow of Gases and Vapors in Nozzles and Piping See Lapple (1943)

FIGURE 2.10-2a. Choked No-Slip Two-Phase Flow in Ideal Nozzles – Critical Pressure Ratio vs. Mass Fraction Vapor Phase

FIGURE 2.10-2b. Choked No-Slip Two-Phase Flow in Ideal Nozzles – Mass Flow Rate Ratio vs. Mass Fraction Vapor Phase

Chapter 3

FIGURE 3.2-1. All-Vapor Venting (a) versus Two-Phase Venting (b)

FIGURE 3.2-2a. Typical Vessel Protected by a Pressure Relief Valve and Venting a Vapor

FIGURE 3.2-2b. Typical Vessel Protected by a Pressure Relief Valve and Venting a Two-Phase Mixture

FIGURE 3.2-2c. Typical Vessel Protected by a Rupture Disk and Venting a Two-Phase Mixture

FIGURE 3.2-3. Two-Phase Vapor-Liquid Disengagement

FIGURE 3.4-1. Schematic of DSC Configuration (Courtesy of Netzsch Instruments)

FIGURE 3.4-2. Schematic of the Accelerating Rate Calorimeter® (Based on the Dow Design)

FIGURE 3.4-3. Pictorial Representation of ARC Operation Modes

(A) Standard Heat-Wait-Search (H-W-S) and (B) Iso-aging followed exotherm (Courtesy of Netzsch Instruments)

FIGURE 3.4-4a. Schematic of the ARSST Containment Vessel (Courtesy of Fauske & Associates, LLC)

FIGURE 3.4-4b. Depiction of Internals and Test Cell Assembly (Courtesy of Fauske & Associates, LLC)

FIGURE 3.4-5. Schematic of the VSP Test Cell and Containment Vessel (Courtesy of Fauske & Associates, LLC)

FIGURE 3.4-6a. NETZSCH APTAC 264 - View of Entire Instrument (Courtesy of Netzsch Instruments)

FIGURE 3.4-6b. Depiction of Containment Vessel Internals (Courtesy of Netzsch Instruments)

FIGURE 3.4-7. Illustration of Flow Regime Detector in the ARSST for (A) Non-Foamy and (B) Foamy Systems (Courtesy of Fauske & Associates, LLC)

FIGURE 3.4-8. Self-Heat Rate Plot for DTBP as a Function of Concentration (As Measured in the APTAC)

FIGURE 3.4-9. Effect of Thermal Inertia Factor on Self-Heat Rate

FIGURE 3.4-10. Effect of Reactant Concentration on Self-Heat Rate

FIGURE 3.4-11. Effect of External Heating (e.g., Fire) on Self-Heat Rate

FIGURE 3.4-12. Example of Instrument Drift Note Slight Positive Slope of Heat-Wait-Search Steps Leading into the Exotherm as well as Shallow Slope after Completion of the Exotherm.

FIGURE 3.4-13. Limit in Ability to Measure High Self-Heat Rates Attributed to Sample Thermocouple Lag

FIGURE 3.4-14. Pressure Behavior with Change in Temperature for Reaction of DTBP in Toluene

FIGURE 3.4-15. Autocatalytic Behavior (from Computer Simulation)

FIGURE 3.4-16. Self-Heat Rate Shapes for Various Reaction Orders

FIGURE 3.4-17. Estimating Activation Energy from the Initial Slope of a Self-Heat Rate Plot

FIGURE 3.4-18. Adjustment of Self-Heat Rate Data for Thermal Inertia and Initial Temperature

FIGURE 3.4-19. Adjustment of Self-Heat Rate Data for Thermal Inertia and Initial Temperature

FIGURE 3.5-1. Generalized Vent Sizing Guideline and Comparison with Benchmark Data

Chapter 4

FIGURE 4.2-1. Capacity Correction Factor for Balanced-Bellows Relief Valves in Liquid Service

FIGURE 4.2-2. Dimensionless Mass Flux and Critical Pressure versus Omega

FIGURE 4.4-1. Configuration for Pipe Flow Analysis

FIGURE 4.4-2. Comparison of Adiabatic and Isothermal Pipe Flow for Air for the Same Upstream and Downstream Pressure

FIGURE 4.4-3. Subsonic Flow of a Compressible Fluid in a Constant Diameter Pipe

Chapter 5

FIGURE 5.3-1. Control Volume for Calculating Exit Reaction Force

FIGURE 5.3-2. Control Volume for Evaluation of Transient Forces

FIGURE 5.3-3. Control Volume for Calculating Pipe Tension

FIGURE 5.6-1. Performance of Safety Valves in Gas Service

FIGURE 5.7-1. Compression of the Upper and Lower Limit Equations to the Shock-Expansion Wave Analysis

FIGURE 5.7-2. Normalized Transient Force from a Rupture Disk with Gas Flow

FIGURE 5.7-3. Comparison of the Transient Reaction Force from an Ideal Nozzle to a Frictionless Pipe Analysis

FIGURE 5.8-1. Equivalent Design Pressure for Pipe Tension for Flow from a Rupture Disk

FIGURE 5.12-1. Exit Reaction Force with a Slant Cut at the Pipe Discharge

Chapter 6

FIGURE 6.1-1. Flow Chart for Selection of Process Options

Chapter 7

FIGURE 7.4-1. Schematic Flow Sheet for Horizontal Separator

FIGURE 7.4-2. Horizontal Separator: Alternative Configurations

FIGURE 7.4-3. Fill Fraction as a Function of Liquid Level in Horizontal Separator

FIGURE 7.5-2. Cyclone Separator: Design Dimensional Relationships

FIGURE 7.5-3. Alternate Cyclone Design

FIGURE 7.6-1. Schematic Flow Sheet for Typical Quench Pool

LIST OF FIGURES

FIGURE 2.3-1. Typical ASME BPVC Section VII Multiple Valve (Non-Fire Case) Installations

FIGURE 2.3-2. Example Adiabatic Pressure-Temperature

FIGURE 2.4-1. Conventional Pressure Relief Valve

FIGURE 2.4-2. Balanced Bellows Pressure Relief Valve

FIGURE 2.4-3. Liquid Relief Valve

FIGURE 2.4-4. Pop Action Pilot Operated Pressure Relief Valve

FIGURE 2.4-5a. Conventional Pre-bulged

FIGURE 2.4-5b. Typical Composite Style Rupture Disk

FIGURE 2.4-5c. Graphite with Resin Binder

FIGURE 2.4-5d. Forward Acting Scored

FIGURE 2.4-6a. Pressure Relief Vent (Courtesy of the Groth Corporation, Stafford, Texas)

FIGURE 2.4-6b. Combination Pressure-Vacuum Relief Vent

FIGURE 2.4-6c. Pilot Operated Relief Vent

FIGURE 2.4-6d. Weight Loaded Emergency Relief Vent

FIGURE 2.4-7. Selection of Pressure Relief Devices

FIGURE 2.5-1. Bleed System with Excess Flow Valve and Bleed Valve

FIGURE 2.5-2. Bleed System with Pressure Switch for Alarm Signal Generation (detects seepage and burst)

FIGURE 2.5-3. Bleed System with Burst Disk Detector for Alarm Signal Generation (some styles can also detect seepage)

FIGURE 2.7-1. Blow Through Scenario

FIGURE 2.10-1. Adiabatic Flow of Gases and Vapors in Nozzles and Piping See Lapple (1943)

FIGURE 2.10-2a. Choked No-Slip Two-Phase Flow in Ideal Nozzles – Critical Pressure Ratio vs. Mass Fraction Vapor Phase

FIGURE 2.10-2b. Choked No-Slip Two-Phase Flow in Ideal Nozzles – Mass Flow Rate Ratio vs. Mass Fraction Vapor Phase

FIGURE 3.2-1. All-Vapor Venting (a) versus Two-Phase Venting (b)

FIGURE 3.2-2a. Typical Vessel Protected by a Pressure Relief Valve and Venting a Vapor

FIGURE 3.2-2b. Typical Vessel Protected by a Pressure Relief Valve and Venting a Two-Phase Mixture

FIGURE 3.2-2c. Typical Vessel Protected by a Rupture Disk and Venting a Two-Phase Mixture

FIGURE 3.2-3. Two-Phase Vapor-Liquid Disengagement

FIGURE 3.4-1. Schematic of DSC Configuration (Courtesy of Netzsch Instruments)

FIGURE 3.4-2. Schematic of the Accelerating Rate Calorimeter®

FIGURE 3.4-3. Pictorial Representation of ARC Operation Modes

FIGURE 3.4-4a. Schematic of the ARSST Containment Vessel

FIGURE 3.4-4b. Depiction of Internals and Test Cell Assembly

FIGURE 3.4-5. Schematic of the VSP Test Cell and Containment Vessel

FIGURE 3.4-6a. NETZSCH APTAC 264 - View of Entire Instrument

FIGURE 3.4-6b. Depiction of Containment Vessel Internals

FIGURE 3.4-7. Illustration of Flow Regime Detector in the ARSST for (A) Non-Foamy and (B) Foamy Systems

FIGURE 3.4-8. Self-Heat Rate Plot for DTBP as a Function of Concentration (As Measured in the APTAC)

FIGURE 3.4-9. Effect of Thermal Inertia Factor on Self-Heat Rate

FIGURE 3.4-10. Effect of Reactant Concentration on Self-Heat Rate

FIGURE 3.4-11. Effect of External Heating (e.g., Fire) on Self-Heat Rate

FIGURE 3.4-12. Example of Instrument Drift

FIGURE 3.4-13. Limit in Ability to Measure High Self-Heat Rates Attributed to Sample Thermocouple Lag

FIGURE 3.4-14. Pressure Behavior with Change in Temperature for Reaction of DTBP in Toluene

FIGURE 3.4-15. Autocatalytic Behavior (from Computer Simulation)

FIGURE 3.4-16. Self-Heat Rate Shapes for Various Reaction Orders

FIGURE 3.4-17. Estimating Activation Energy from the Initial Slope of a Self-Heat Rate Plot

FIGURE 3.4-18. Adjustment of Self-Heat Rate Data for Thermal Inertia and Initial Temperature

FIGURE 3.4-19. Adjustment of Self-Heat Rate Data for Thermal Inertia and Initial Temperature

FIGURE 3.5-1. Generalized Vent Sizing Guideline and Comparison with Benchmark Data

FIGURE 4.2-1. Capacity Correction Factor for Balanced-Bellows Relief Valves in Liquid Service

FIGURE 4.4-1. Configuration for Pipe Flow Analysis

FIGURE 4.4-2. Comparison of Adiabatic and Isothermal Pipe Flow for Air for the Same Upstream and Downstream Pressure

FIGURE 4.4-3. Subsonic Flow of a Compressible Fluid in a Constant Diameter Pipe

FIGURE 5.3-1. Control Volume for Calculating Exit Reaction Force

FIGURE 5.3-2. Control Volume for Evaluation of Transient Forces

FIGURE 5.3-3. Control Volume for Calculating Pipe Tension

FIGURE 5.6-1. Performance of Safety Valves in Gas Service

FIGURE 5.7-1. Compression of the Upper and Lower Limit Equations to the Shock-Expansion Wave Analysis

FIGURE 5.7-2. Normalized Transient Force from a Rupture Disk with Gas Flow

FIGURE 5.7-3. Comparison of the Transient Reaction Force from an Ideal Nozzle to a Frictionless Pipe Analysis

FIGURE 5.8-1. Equivalent Design Pressure for Pipe Tension for Flow from a Rupture Disk

FIGURE 5.12-1. Exit Reaction Force with a Slant Cut at the Pipe Discharge

FIGURE 6.1-1. Flow Chart for Selection of Process Options

FIGURE 7.4-1. Schematic Flow Sheet for Horizontal Separator

FIGURE 7.4-2. Horizontal Separator: Alternative Configurations

FIGURE 7.4-3. Fill Fraction as a Function of Liquid Level in Horizontal Separator

FIGURE 7.4-4. Vertical Separator

FIGURE 7.5-1. Schematic Flow Sheet for Emergency Cyclone Separator

FIGURE 7.5-2. Cyclone Separator: Design Dimensional Relationships

FIGURE 7.5-3. Alternate Cyclone Design

FIGURE 7.6-1. Schematic Flow Sheet for Typical Quench Pool

FIGURE 7.6-2. Typical Sparger Arrangement

FIGURE 7.6-3. Alternative Sparger Arrangements

FIGURE D.3.2-1. CCFlow Calculation of Isentropic Expansion Exponent

FIGURE D.3.3-1. CCFlow Calculation of Isentropic Expansion Exponent

FIGURE D.3.5-1. Mass Flux Calculation Results

FIGURE D.3.8-1. Input Data Menu

FIGURE D.3.9-1. TPHEM Output for 3-Point Interpolation Ideal Nozzle Mass Flux Calculation

FIGURE D.3.11-1. CCFlow Calculation of Isentropic Expansion Exponent

FIGURE D.4.1-1. SuperChems Wizard Input Screen After Initial Data Entry

FIGURE D.4.1-2. Middle Part of Relief Valve Specification Menu

FIGURE D.4.1-3. Upper Part of Inlet Piping Segment Specification Menu

FIGURE D.4.1-4. Piping Layout Menu

FIGURE D.4.1-5. SuperChems Case Output – Upper Part

FIGURE D.4.1-6. SuperChems Output – Second Part

FIGURE D.4.2-1. CCFlow Main Menu with Options

FIGURE D.4.2-2. CCFlow Second Menu Input

FIGURE D.4.2-3. CCFlow Third Menu Input and Results

FIGURE D.4.2-4. Using CCFlow to Determine Discharge Temperature

FIGURE D.5.1-1. Piping Forces

FIGURE D.5.2-1. Forces Acting on Relief Valve

FIGURE D.5.3-1. Piping and Reaction Forces

FIGURE D.5.3-2. Anchor and Force Locations

FIGURE D.5.4-1. Reaction Forces

FIGURE D.5.4-2. Steady State Force from COMFLOW

FIGURE D.5.4-3. Transient Force from COMFLOW

FIGURE D.5.4-4. Tension Force from COMFLOW

FIGURE D.5.5-1. Steam Being Relieved by 4N6 Safety Valve

FIGURE D.5.5-2. Steady State Force (F2) from COMFLOW

FIGURE D.5.6-1. Liquid Being Relieved by a Bellows 4N6 Safety Valve

FIGURE D.5.7-1. Two-Phase Relief by a Bellows 4N6 Safety Valve

FIGURE D.5.7-2. Exit Thrust (TPHEM)

FIGURE D.5.8-1. Reaction Force for Rupture Disk with Two-Phase Flow

FIGURE D.5.8-2. Capacity and Exit Force from TPHEM

FIGURE D.5.8-3. Transient Force from TPHEM

FIGURE E.1-1. Results of Process Simulation

FIGURE E.1-2. Results of Quench Pool Calculations

LIST OF TABLES

TABLE 2.3-1. Maximum Accumulation as a Percent of MAWP

TABLE 2.3-2. Maximum Set Pressures as a Percent of MAWP

TABLE 2.3-3. Set Pressure Compensation Requirements for Pressure Relief Devices

TABLE 2.4-1. PRV Orifice Parameters

TABLE 2.4-2. PRV Set Pressure Tolerances

TABLE 2.4-3. Typical Characteristics of Rupture Disk Devices

TABLE 3.3-1. OSHA Venting Requirements: Fire Exposure of Storage Tanks

TABLE 3.3-2. NFPA Heat Input to Vessel from Fire Exposure

TABLE 3.3-3. Wetted Area

TABLE 3.4-1. Comparison of Calorimeters Utilized for ERS Design

TABLE 4.4-1. 3-K Constants for Loss Coefficients for Valves and Fittings

TABLE 4.4-2. Loss Coefficients for Expansions and Contractions (Hooper, 1988)

TABLE 5.6-1. Basis for Calculating Quasi-Steady State and Transient Reaction Forces from Rupture Disk Systems

TABLE 5.6-2. Basis for Calculating Quasi-Steady State and Transient Reaction Forces from Safety Valve Systems

TABLE 6.2-1. Checklist for Emergency Relief Effluent Handling Systems

TABLE 6.5-1. Containment in the Original Vessel

TABLE 6.5-2. External Containment

TABLE 6.5-3. Direct Discharge to the Atmosphere

TABLE 6.5-4. Droplet Size Characterization

TABLE 6.5-5. Selection of Vapor-Liquid Separators

TABLE 6.5-6. Separator Selection Screening - Foam Handling Capability

TABLE 6.5-7. Separator Selection Screening - Droplet Size Removal/Handling Capability

TABLE 6.5-8. Separator Selection Screen - Droplet Size Removal Efficiency

TABLE 6.5-9. Gravity Separators

TABLE 6.5-10. Vane Impingement Entrainment Separators

TABLE 6.5-11. Cyclone Separators

TABLE 6.5-12. Quench Pools

TABLE 6.5-13. Examples of Quench Pool Liquid Applications

TABLE 6.5-14. Scrubber

TABLE 7.5-1. Cyclone Separator Design F-Factors

TABLE A.1-1. SuperChems™ for DIERS Lite Capabilities

TABLE A.2-1. Source Term Wizards

TABLE A.2-2. Emergency Relief Systems Wizards

TABLE C.1. SuperChems™ for DIERS Capabilities

TABLE D.1-1. Software Usage and Input File Names for Worked Examples

TABLE D.1-1. Software Usage and Input File Names for Worked Examples (continued)

TABLE D.1-1. Software Usage and Input File Names for Worked Examples (continued)

TABLE D.1.1-1. Component Properties for Fire Exposure Example Problem

TABLE D.1.2-1. Propane Properties

TABLE D.4.3-1. Summary of Iterative Calculations

TABLE E.1-1. Rupture Disk System: Rupture Disk – NPS 3

TABLE E.1-2. Pressure Relief Valve System – 4N6

PREFACE

The American Institute of Chemical Engineers (AIChE) has been closely involved with process safety and loss control issues in the chemical and allied industries for more than four decades. Through its strong ties with process designers, constructors, operators, safety professionals, and members in academia, AIChE had enhanced communication and fostered continuous improvement of the industry’s high safety standards. AIChE publications and symposia have become information resources for those devoted to understanding the causes of incidents and discovering better means of preventing their occurrence and mitigating their consequences.

The Design Institute for Emergency Relief Systems (DIERS), formed in 1976, was a consortium of 29 companies that developed methods for the design of emergency relief systems to handle runaway reactions. DIERS spent $1.6 million to investigate the two-phase vapor-liquid onset / disengagement dynamics and the hydrodynamics of emergency relief systems. Of particular interest to DIERS were the prediction of two-phase flow venting and the applicability of various sizing methods for two-phase vapor-liquid flashing flow.

DIERS became a Users Group in 1985 with a purpose:

to reduce the frequency, severity and consequences of pressure-producing accidents and

to promote the development of new techniques that will improve the design of emergency relief systems

The DIERS Users Group conducted 60 semi-annual 3-day technical meetings in 31 cities to include three International Symposia, three meetings in Canada, and two Joint US – European DIERS meetings in Hamburg and Dü sseldorf, Germany during the last 30 years. There were nineteen visits to industrial (chemical production plants; safety relief valve, rupture disk, and breather vent manufacturing facilities; and equipment supplier laboratories) and twelve computer and laboratory equipment training sessions conducted in conjunction with the semi-annual technical meetings. Approximately 625 additional technical presentations have provided a learning environment for the company representatives.

A combination of computational and / or experimental round-robin exercises have been conducted almost every year since the formation of the DIERS Users Group.

The reorganization of DIERS in 2015 from a corporate based to an individual based membership will provide a basis for further growth. New general (non-funded) and special (funded) projects as well other initiatives and activities are planned and underway to increase the scope and breadth of DIERS technical and outreach programs.

The Center for Chemical Process Safety (CCPS) was established in 1985 by AIChE to develop and disseminate technical information for use in the prevention of major chemical incidents. CCPS is supported by more than 170 sponsoring companies in the chemical process industry and allied industries; these companies provide the necessary funding and professional experience for its technical subcommittees.

Pressure relief systems have always been important components in the design of safety systems for chemical and petrochemical plants. The first DIERS book on pressure relief systems was Emergency Relief System Design Using DIERS Technology: The Design Institute for Emergency Relief Systems (DIERS) Project Manual (CCPS 1993). The first edition of Guidelines for Pressure Relief and Effluent Handling Systems was issued in 1998 in recognition of the need for guidance in designing emergency relief systems to minimize or contain the discharge of potentially harmful materials. This second edition has been written to incorporate learnings in the field of emergency pressure relief since then.

ACKNOWLEDGEMENTS

The American Institute of Chemical Engineers (AIChE) wishes to thank the Center for Chemical Process Safety (CCPS) and the Design Institute of Emergency Relief Systems (DIERS) and those involved in its operation, including its many Sponsors whose funding made this project possible; the members of the Technical Steering Committee who conceived of and supported this project; and the members of the DIERS Emergency Relief / Effluent Handling Subcommittee for their dedicated efforts and technical contributions.

This book was edited by:

The Subcommittee wishes to thank the following peer reviewers for their thoughtful and detailed comments and valued suggestions:

CCPS thanks ioMosaic Corporation and all of their contributors that made the publications of this book possible:

Daniel Nguyen and Paul Goncalves for software support.

Vanessa Millette, Kristi Marak and Sarah Weinmann for preparing the manuscript.

IN MEMORIAM

To the Memory of Our Colleagues

Stanley S. Grossel

Howard E. Huckins

Harold S. Kemp

Stanley D. Morris

Thomas J. Rebarchak

Richard Schwab

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1

INTRODUCTION

1.1 OBJECTIVE

Guidance for the design and selection of pressure relief devices for most applications can be found in documents provided by several organizations including: the American Society of Mechanical Engineers (ASME), the American Petroleum Institute (API), the National Fire Protection Association (NFPA), the Compressed Gas Association (CGA), and the International Organization for Standardization (ISO). The Occupational Safety and Health Administration (OSHA) Process Safety Management (PSM) regulation and the similar Environmental Protection Agency (EPA) Chemical Accident Prevention regulation (commonly referred to as Risk Management Plan (RMP)) and increased industry efforts to improve safety and environmental protection practices have led to much greater focus on reducing and controlling releases of materials from pressure relief systems to the atmosphere.

The guidance and sizing formulas provided by the above organizations are generally applicable only to single-phase flow. Research and studies by the Design Institute for Emergency Relief Systems (DIERS) resulted in a new body of technology on two-phase flow from relieving vessels and the effect of two-phase flow on pressure relief system design and on the performance of pressure relief valves under such conditions. These developments suggested a need for a presentation from a chemical industry perspective on the design and selection of pressure relief devices for single as well as multi-phase flow from pressure relief systems and for the treatment of the effluent from pressure relief systems. Preparation of this book by the CCPS was in response to this need.

This CCPS / DIERS book is directed toward experienced process engineers and specialists with a basic proficiency in fluid dynamics and process engineering fundamentals. The objective is to present information that will provide guidance for selecting and designing reliable emergency pressure relief and effluent handling systems. These systems should be designed to protect equipment from overpressure and to either contain or safely control hazardous materials discharged during an emergency.

This second edition presents updated information on several widely used national codes and standards to include those which have been adopted by regulatory authorities for inclusion in either federal or local regulations. These documents should be viewed by designers as representing industry practices with proven value in providing reliable process safety systems, not just as regulations requiring compliance.

1.2 SCOPE

General background information on pressure relief technology is presented along with guidance for selecting relief devices and effluent handling equipment. Calculation procedures for designing pressure relief and selected effluent handling equipment are also presented. Numerous example problems are used to illustrate calculation procedures. Computer programs are presented for handling flow calculations for compressible gases, for evaluating complex two-phase flow situations, and for sizing effluent handling equipment. The book includes:

Discussions of national and international codes and regulatory impacts on pressure relief system design and operation.

Reviews of causes of overpressure events and selection of the worst case scenario and the relief system design and design basis for the relief system including systems involving chemically reactive and highly viscous materials.

Descriptions of a range of relief devices and operating performance characteristics including flow calculation methods for sizing pressure relief devices and associated piping systems.

Characterization of fluid properties including sources of property information and handling of mixtures.

Methods for calculation of reaction thrust forces from discharge of relief systems.

Guidance in selecting effluent handling systems including equipment commonly used for pressure relief system applications. This includes gravity and cyclone separators, scrubbers, quench pools, flares, and atmospheric dispersion (for non-hazardous materials only).

Calculation procedures for sizing the most widely used equipment for effluent handling, including gravity separators, cyclones, quench pools and spargers.

Maintenance, operations, and testing procedures and technology are not discussed in detail, but are covered briefly in selected cases. Prevention or mitigation of overpressure incidents and the essential components of a good process safety management system are beyond the scope of this book. Such procedures and technology include emergency control or shutdown systems, inherent safety concepts, safety layers of protection, prevention of explosive deflagrations and detonations, and other measures used to reduce the frequency or magnitude of emergency overpressure events. Guidance on these subjects can be found in other CCPS books, which are listed in the appropriate sections of this book.

If potentially hazardous materials might be discharged to the atmosphere, specialists on the health and environmental effects should be consulted to determine safe levels of discharge to the air, water, and land. In general the release of hazardous materials to the environment should be avoided if at all possible.

1.3 DESIGN CODES AND REGULATIONS, AND SOURCES OF INFORMATION

There are a number of organizations that provide information on pressure relief and handling of effluent from pressure relief systems. Some of these, with a brief summary of their role, are shown below (see Section 2.3.1 for a more extensive listing):

Federal and local governments. The federal government, through OSHA and EPA regulations, provides much information on requirements for process safety and environmental protection. Many states have implemented regulations that parallel or exceed federal regulations. Designers and operators of pressure relief systems should maintain a familiarity with these requirements. While the focus in this book is on practices, codes, and standards of U.S. origin, designers and operators of facilities in other countries are urged to become familiar with any practices or regulations that may apply. In many cases facilities designed to meet U.S. requirements will either meet or exceed requirements based on international regulations.

American Society of Mechanical Engineers (ASME). The ASME publishes the Boiler and Pressure Vessel Code (ASME BPV Code), which contains basic requirements for overpressure protection of vessels covered by the Code. Section VIII covers Pressure Vessels, which are applicable to the petroleum and chemical process industries. Many governmental authorities have adopted the ASME BPV Code and made it part of their regulations. The ASME BPV Code therefore has the force of law in many states.

American Petroleum Institute (API). The API publishes a series of standards and recommended practices that cover the fundamentals and application of pressure relief technology including pressure relief of low pressure tanks and testing and maintance of pressure relief valves. Many recommendations are presented that cover various aspects of pressure relief system design, including effluent handling.

National Fire Protection Association (NFPA). The NFPA publishes a number of documents that present pressure relief requirements for various specific fluid services. Their Flammable and Combustible Liquids Code (NFPA 30), Standard for Water Spray Fixed Systems for Fire Protection (NFPA 15), Standard on Explosion Protection by Deflagration Venting (NFPA 68) and Standard on Explosion Prevention Systems (NFPA 69) are of particular interest to the chemical and petroleum process industries.

National Board of Boiler and Pressure Vessel Inspectors (NB). The National Board publishes information on certified flow capacity of valves tested in accordance with ASME procedures and documents related to inspection and repair of pressure relief valves.

International Organization for Standardization (ISO). ISO publishes international standards. Some of these documents are cross-branded with API documents. Compliance with these standards is required by most European countries. The ISO 4126 standard for safety devices for protection against excessive pressure is divided into eleven separate parts applicable to safety valves, rupture disks, pilot operated valves and other topics.

DIERS. The Design Institute for Emergency Relief Systems (DIERS) was established in 1976 to develop a better understanding of pressure relief system technology including vapor-liquid disengagement in vessels and flow of two-phase fluids through pressure relief devices and piping. The results of the initial research have been published (DIERS 1992). Current developments are covered during DIERS biannual meetings and in associated reports where information on new research, practices and technology is presented and discussed.

Other sources of information that supplement the standards and codes indicated above are given as references and noted within the text of each chapter of the book.

1.4 ORGANIZATION OF THIS BOOK

Pressure relief technology is covered in the chapters of this book. The following is a brief summary of each chapter:

Chapter 1. Introduction

Chapter 2. Relief System Design Criteria and Strategy: Presents general information on pressure relief technology (including terminology and definitions) pressure relief design strategies, ASME BPV Code requirements, and descriptions and layout of relief systems. Also covered are causes of overpressure, review of worst credible relief scenarios, analysis of vapor-liquid phase behavior in vessels, determination of required flow capacity, fluid properties and system characterization, flow of fluids through relief systems, and relief system reliability.

Chapter 3. Requirements for Relief Systems Design: Covers vessel venting background to include vessel onset / disengagement dynamics for evaluating whether two-phase flow might occur, venting requirements for nonreacting cases, calorimetry for reactive emergency relief system design, and venting requirements for reactive cases.

Chapter 4. Methods for Relief Systems Design: Covers calculation methods for sizing and rating pressure relief devices and associated piping to include computerized and manual methods for safety relief valves and piping and rupture disks and associated piping for vapor, liquid, and two-phase flows.

Chapter 5. Additional Considerations for Relief Systems Design: Covers the mechanical forces involved during emergency venting. Methods for estimating reaction thrust from relief system discharge are covered.

Chapter 6. Handling Emergency Relief Effluents: Presents guides to selection of equipment and systems to treat the effluent from relief devices. The focus is on equipment and techniques that are more commonly used in pressure relief applications. Information is summarized in tables that list advantages, disadvantages, and areas of possible application for the various types of equipment.

Chapter 7. Design Methods for Handling Effluent from Emergency Relief Systems: Covers design methods and sizing calculation procedures for various types of equipment and processes that are commonly used to treat effluent in emergency relief situations. Methods are presented in detail for gravity separators, cyclone separators, and quench pools (including spargers for quench pools).

Computer Programs. Several useful computer programs are provided at the CCPS website listed in the front of the book. These programs are provided to aid in making flow calculations for relief devices and piping and for sizing selected effluent handling equipment. The computer programs include the SuperChems™ family of new programs and the CCFlow and TPHEM legacy programs provided in the first edition of this guideline.

SuperChems™ for DIERS Lite includes steady state methods for evaluation of relief requirements and contains a visual interface for the construction of piping isometrics with a variety of pressure relief devices components such as rupture disks and safety relief valves. SuperChems™ for DIERS includes methods for modeling the dynamics of relief from vessels with and/or without chemical reactions.

The CCFlow family of programs includes the following:

TPHEM, a DOS program for two-phase flow through piping and nozzles,

COMFLOW, a DOS program for gas/vapor flow through piping and nozzles,

CCFlow, a Windows® program for two-phase and gas/vapor flow through piping and nozzles for sizing and evaluating relief valves and for sizing gravity separators, cyclone separators, and spargers.

CCFlow Utilities, a program to calculate Antoine coefficients, compressibility factors, and isentropic expansion coefficients. Multicomponent systems can be handled for the latter two items.

Instructions for use of The CCFlow program are included in the CCFlow Help files. The uses of the programs are illustrated in the Appendices. These programs do not address determination of required relieving capacity or composition of the effluent.

1.5 GENERAL PRESSURE AND RELIEF SYSTEM DESIGN CRITERIA

Anyone with responsibility for designing, operating, and maintaining pressure relief systems and other process equipment should be familiar with: the provisions of the OSHA Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119) PSM standard; the EPA Risk Management Program (40 CFR 68.130) RMP rule; and the requirements of States that have their own State Plan. Guidance on the implementation of the principles embodied in the Federal and State standards are discussed in general in CCPS (1989c and 1992) and in API Standard 750. More specific guidance on each of the required elements is provided in numerous CCPS books.

While compliance with all applicable regulations is important, the basic objective is the safety of people and preventing damage to facilities and the environment. Compliance with regulations alone may not provide an acceptable level of protection. Compliance with the Federal and State Plan regulations is required if a listed chemical is present in the process in an amount equal to or in excess of a threshold quantity. The engineering practices provided in this book are applicable to all processes and may be considered to represent the current best thinking of the DIERS working group.

Company standards and practices are also an important source of information on design requirements for pressure relief systems. They are usually based on process safety management principles that have been developed from many years of experience. Many regulations use industry best-practices as a reference. These practices have been proven to represent good business practices as well as good process safety management and have been incorporated into the culture of many organizations.

Some important process safety management techniques related to pressure relief system design, which are not covered in detail in this book, are discussed briefly below. OSHA published a standard in 1992, Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119) to control chemical hazards in the workplace. That standard covers basic requirements for implementing a good process safety management program which involves applying generally recognized and accepted good engineering practices to ensure process safety in new and existing plant facilities. Two components of a process safety management program referred to in 29 CFR 1910.119 are particularly relevant to the design, operation, and maintenance of pressure relief systems; these are Process Hazards Analysis and Process Safety Information, which are discussed briefly in the following sections.

1.5.1 Process Hazard Analysis

A chemical process and plant facility should be analyzed for all possible causes of overpressure to determine the worst credible scenario. The worst credible scenario establishes the design basis for the pressure relief and for the effluent handling system. Methods for conducting such a hazards analysis and evaluation are presented in CCPS (2003 and 2008a). The hazard analysis should be revalidated on a regular basis to review the current process conditions, any possible mechanical changes in the facility since the original construction or last hazard analysis, and maintenance and operating records for any signs of problems. The pressure relief system should then be verified to ensure that it is still adequate to protect the equipment. Guidance on how to revalidate a hazard analysis is provided in CCPS (2001) and by Chadwell (1997).

Inherent safety concepts should be applied during the process design on the hazards of the process. Refer to CCPS (2009) for guidance on this topic. This can include changing process chemistry to use less hazardous materials, avoiding extreme temperatures and pressures, and designing for total containment by increasing vessel design pressure.

Operating and maintenance personnel should be trained. Operating and maintenance procedures must be written for start-up, shutdown, upset, and normal operating conditions. These written procedures must be updated and must be part of the periodic hazard review and analysis program. Proper supervisory controls must be instituted and training and refresher courses provided for operating and maintenance personnel. Refer to CCPS (1989c, 1995e and 1996b) for guidance on this topic.

Process safety audits should be conducted. An independent audit and verification of the design can provide additional assurance that the emergency relief system will adequately protect the vessel. An audit of the initial design can include a review of overpressure events