Rules of Thumb for Chemical Engineers

Stephen Hall

• Publisher: Elsevier
• Year: 2017
• Edition: 6
• eBook ISBN:
  9780128110386
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

Rules of Thumb for Chemical Engineers, Sixth Edition, is the most complete guide for chemical and process engineers who need reliable and authoritative solutions to on-the-job problems. The text is comprehensively revised and updated with new data and formulas. The book helps solve process design problems quickly, accurately and safely, with hundreds of common sense techniques, shortcuts and calculations. Its concise sections detail the steps needed to answer critical design questions and challenges. The book discusses physical properties for proprietary materials, pharmaceutical and biopharmaceutical sector heuristics, process design, closed-loop heat transfer systems, heat exchangers, packed columns and structured packings. This book will help you: save time you no longer have to spend on theory or derivations; improve accuracy by exploiting well tested and accepted methods culled from industry experts; and save money by reducing reliance on consultants. The book brings together solutions, information and work-arounds from engineers in the process industry. - Includes new chapters on biotechnology and filtration - Incorporates additional tables with typical values and new calculations - Features supporting data for selecting and specifying heat transfer equipment

Chapter 1

Safety

Abstract

After providing an overview of the US Occupational Safety and Health Association (OSHA) Process Safety Management (PSM) mandate, this chapter discusses the qualitative and quantitative methods for conducting Process Hazard Analysis (PHA). General safety design practices are listed. Emergency venting systems, through relief valves or rupture disks, are discussed along with the design equations following the American Petroleum Institute (API), OSHA, and the National Fire Protection Association (NFPA) standards. Equations are given for estimating the flash point of binary mixtures. Deflagration prevention and control are discussed. A key concept—prevention of backflow—is presented. Equipment purging schemes are defined along with calculations. Electrical area classifications are discussed. Design recommendations to prevent or control dust explosion hazards are provided.

Keywords

Process safety management; Process hazard analysis; Emergency venting; Flash point; Deflagration; Equipment purging; Dust explosion

Introduction

A prerequisite for every process design is that the safety of people, the environment, and equipment is assured. Although it may not be possible or practicable to absolutely prevent every incident, by using appropriate assessment and design tools, engineers do strive to strike a consistent balance between safety, technology, and cost.

This chapter gives an overview of the most comprehensive of the US safety standards, OSHA's Process Safety Management (PSM). The chapter then gives specifics that pertain to a range of safety-related issues and calculations. The two underlying principles are the following:

1. Information and Data. Engineers must have a thorough understanding of the chemistry, process, equipment, controls, operations, maintenance practices, and other factors that contribute to a safe plant. Understanding goes beyond the facts, criteria, equations, and algorithms that are presented throughout this book. Good engineers synthesize those individual unit operation concepts into coherent plant-wide designs. The combination of this informed high-level view and the details for each process step and unit operation form the body of knowledge for the hazards analyses, which are the second principle.

2. Process hazards analysis (PHA). Variously called a risk assessment, PHA, FMEA, HazOp, and many other terms, the PHA is intended to identify what could go wrong and determine the potential health impacts (both acute and chronic), environmental degradations, and business interruptions that could result. In addition to “what,” the PHA can address “who,” “why,” “when,” and “how” questions and provide guidance for whether or not mitigating features should be added to the plant design or operating instructions.

Many chapters in this book include a “Safety Considerations” section. These are intended to provide pointers and are not comprehensive. Incorporate them into the information and data that form the basis for a plant that is designed with safety being in the forefront.

Process Safety Management (PSM)

Compliance with OSHA's PSM [1] regulation is mandatory for every process facility that meets one of these tests:

• Quantities of specific listed highly hazardous chemicals are greater than the quantities listed in the regulation. Examples: 110 kg (250 lb) methyl isocyanate, 225 kg (500 lb) nitric acid (94.5% by weight or greater), 680 kg (1500 lb) chlorine gas, or 6800 kg (15,000 lb) methyl chloride.

• More than 4500 kg (10,000 lb) of flammable liquids or gases are present in one location, except for hydrocarbon fuels used solely for onsite consumption as a fuel, and flammable liquids stored in atmospheric tanks or transferred at a temperature below their normal boiling point (without benefit of chilling or refrigeration).

Certain facilities are exempt including retail facilities, oil or gas drilling and servicing facilities, and normally unoccupied remote facilities.

It is a 14-point performance-oriented system summarized in Table 1.1. While clearly emphasizing safety, PSM also makes good business sense because compliance reduces the frequency and severity of accidents. The elements composing PSM range widely and may have far-reaching implications.

Table 1.1

The 14 Elements of OSHA's Process Safety Management Regulation [1]

Element	Description
Employee participation	Employers must consult with their employees and their representatives regarding the employer's efforts in the development and implementation of the PSM program elements and hazard assessments. Employers must also train and educate their employees and to inform affected employees of the findings from incident investigations required by the PSM program
Process safety information	Complete and accurate written information concerni...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1: Safety
• Chapter 2: Process Evaluation
• Chapter 3: Process Modeling
• Chapter 4: Fluid Flow
• Chapter 5: Vessels
• Chapter 6: Blending and Agitation
• Chapter 7: Pumps
• Chapter 8: Fans, Blowers, and Compressors
• Chapter 9: Vacuum Systems
• Chapter 10: Pneumatic Conveying
• Chapter 11: Filtration
• Chapter 12: Heat Exchangers
• Chapter 13: Closed-Loop Heat Transfer Systems
• Chapter 14: Fractionators
• Chapter 15: Absorbers
• Chapter 16: Controls
• Chapter 17: Biopharmaceutical Systems
• Chapter 18: Bioprocessing
• Chapter 19: Energy Conservation
• Chapter 20: Drivers
• Chapter 21: Boilers
• Chapter 22: Cooling Towers
• Chapter 23: Refrigeration
• Chapter 24: Reliability
• Chapter 25: Metallurgy
• Chapter 26: Troubleshooting
• Chapter 27: Startup
• Chapter 28: Conversion Factors and Constants
• Chapter 29: Properties
• Appendix A: Resources
• Appendix B: Tank Cleaning
• Index