Special Distillation Processes

Zhigang Lei, Biaohua Chen, Zhongwei Ding

• Publisher: Elsevier Science
• Year: 2005
• Print ISBN: 9780444516480
• eBook ISBN: 9780080455754
• Topic: Physical Sciences
• Subtopic: Analytic Chemistry

Special distillation processes are required for separation of mixtures close to boiling point or for forming azeotrope mixtures into their pure components. In Special Distillation Processes, the authors focus on latest developments in the field, such as separation methods that may prove useful for solving problems encountered during research. Topics include extraction, membrane and adsorption distillation involving the separation principle, process design and experimental techniques. The relationship between the processes and the techniques are also presented. Comprehensive and easy-to-read, this book provides key information needed to understand the processes and is a valuable reference source for chemical engineers as well as students wishing to branch out in chemical engineering.* The only comprehensive book available on special distillation processes* Contains a thorough introduction to recent developments in the field* A valuable reference for students and engineers in chemical engineering

Chapter 1

Thermodynamic fundamentals

This chapter presents the thermodynamic fundamentals closely related with special distillation processes, which may facilitate readers to understand the separation principle discussed in the subsequent chapters. Some novel contents, which are commonly not involved in many classic thermodynamic texts, but necessary for the understanding, such as salt effect, nonequilibrium thermodynamic analysis and multi-component mass transfer, are covered. In accordance with the step-by-step rule, the section of vapor-liquid phase equilibrium is present at the beginning, and thus there is a little overlapping with common texts.

1 VAPOR-LIQUID PHASE EQUILIBRIUM

Phase equilibrium can be sorted into vapor-liquid, liquid-liquid, vapor-liquid-liquid, etc. Vapor-liquid phase equilibrium as the most applied and calculable form of phase equilibrium plays a major role in special distillation processes, particularly with respect to energy requirements, process simulation and sizing equipment. Thus, in this chapter this content is more highlighted. But, for the sake of immiscibility, sometimes the occurrence of two-liquid phase in the distillation column is inevitable. So on the foregoing basis vapor-liquid-liquid equilibrium is also briefly mentioned in this chapter. The details about how to numerically calculate the problem on vapor-liquid-liquid equilibrium are described in chapter 3 (azeotropic distillation) where vapor-liquid-liquid equilibrium is involved.

1.1 The equilibrium ratio

Equilibrium is defined as a state that will be returned to its initial state after any short, small mechanical disturbance of external conditions. According to the knowledge of physical chemistry, within any closed system where phase equilibrium exists, the total Gibbs free energy for all phases is a minimum because at this time there is no heat and mass transfer in the system. This is the starting point for studying phase equilibrium. On the other hand, from classical thermodynamics, the total Gibbs free energy and the change of Gibbs free energy in a single phase, i-component system are:

(1)

and

(2)

respectively, where T (temperature), P (pressure), n₁, n₂, · · ·, n_i (mole number of components 1, 2, … i, …, etc, respectively) are independent variants.

Thus, the change...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1: Thermodynamic fundamentals
• Chapter 2: Extractive distillation
• Chapter 3: Azeotropic distillation
• Chapter 4: Catalytic distillation
• Chapter 5: Adsorption distillation
• Chapter 6: Membrane distillation
• Chapter 7: Pressure-swing distillation
• Chapter 8: Other distillation techniques
• Subject Index