Mass and Energy Balancing

Calculations for Plant Design

David Pritchard, Shaik Feroz

• Publisher: CRC Press
• Year: 2021
• eBook ISBN: 9781000392326
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Chemistry
• Index: Chemistry

The aim of this text is to provide a comprehensive set of calculations relating to mass and energy balances for an entire process plant. An ammonia synthesis plant will be taken as a calculation model to develop the relevant mass and energy balances necessary for the design and subsequent production, as the production of ammonia synthesis gas is an internationally used process. Instead of teaching the basics of mass and energy balances, the text aims to give a detailed series of process integrated and illustrated calculations to help readers develop and design a process plant.

• Details complete mass and energy calculations related to a manufacturing plant and includes stepwise procedures for mass and energy balances

• Demonstrates how the series of integrated calculations will lead to the production of a specified amount of final product

• Features "teaching" appendices that lay out applications of prior-assumed knowledge, which can be used in conjunction with the main text where more detailed explanation may be needed

• Contains problems linked to various manufacturing sections covered in the text to help readers consolidate their knowledge

This book will serve undergraduate Chemical Engineering students as a teaching aid in capstone design and related courses and gives useful insights to advanced students, researchers, and industry personnel within the Chemical Engineering field.

1 Introduction, Reformers and Stream Energy Interchange

1.1 General Introduction and Basis for Calculation

If you are intending to use this text in an informative, learning, teaching or critical situation, then there is an assumption that you know some of the principles of process engineering and the breadth and depth of the challenge you may be faced with. There exist a number of texts [1] that can supplement your knowledge and be informative in introducing you to further aspects of process engineering. This particular text deals with one of the initial, essential, procedures in process engineering, an analysis of the mass and energy requirement of any and all operations.

You cannot carry out mass and energy balances unless the basic principles of thermodynamics are understood and observed. The first law is often pithily stated that mass is conserved. There are obviously various subheadings to write here, but the conservation of mass sounds a good basis for

$$\text{Input}=\text{Output}$$

Those of you who have experienced process engineering in theory and in practice will know that it is crucial to be able to handle the masses and energies involved in the chemical reaction as well as non-reacting systems. As usual, thermodynamics takes us calmly by the shoulder and points out that species may change through the reaction, but the total mass of atoms confirms that mass and energy input does indeed equal mass and energy output. The second law of thermodynamics gives us the concepts and tools to be able to carry out quantitative analysis of the balance when chemical reaction is also involved.

Many operations within process engineering are carried out at steady state, and the mass and energy balances do not vary with respect to time; for both mass and energy, the input equals the output. Mass and energy balances have a time-variant form if required; a time-variant term, the accumulation or depletion, can be added or subtracted. This term will not be considered in this text. All production of ammonia syngas is considered at steady state.

If you are relatively new to process engineering and its component parts, then it might be useful to read the next few pages. If you know everything there is to know about it, then the next few pages may be old hat – but still readable. A general description of process engineering would include the following, this description includes concepts already covered:

• Process engineering is the engineering part of production processes in which chemical and physical changes take place. The process engineer deals with all aspects of the chemical industry from planning, designing, construction, operation and control, as well as research and development, marketing and technical services for customers. Of course, the process engineer should also be aware of the economic aspects of production. Process engineering is aimed towards the design of processes that change materials from one form or species to another, more useful and valuable form,...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Foreword
• Preface
• Acknowledgements
• Nomenclature
• Authors
• Chapter 1 Introduction, Reformers and Stream Energy Interchange
• Chapter 2 Shift Converters and Stream Energy Interchange
• Chapter 3 Carbon Dioxide Removal and Stream Energy Interchange
• Chapter 4 Compression, Preheat and Desulphurisation
• Chapter 5 Problems to Solve with Hints
• Chapter 6 Answers to Problems in Chapter 5
• Appendix 1: Basic Equations Relating to the Thermodynamics of Equilibrium Constants and Their Calculation and Their Values for the Methane–Steam Reaction and Water–Gas Shift Reaction
• Appendix 2: Calculation of Fractional Conversions for the Primary Reformer
• Appendix 3: Discussion of Data Sources and Basic Equations Relating to the Enthalpy Property
• Appendix 4: Solution of Simultaneous Equations for the Secondary Reformer
• Appendix 5: Use of Approach to Equilibrium in Assessing Catalyst Performance
• Index