Page 11 - Gas Purification 5E

Chapter 1

Introduction

DEFINITIONS, 1

PROCESS SELECTION, 2

PRINCIPLES OF ABSORPTION, 6

Introduction, 6
Contactor Selection, 6
Design Approach, 12
Material and Energy Balance, 13
Column Height, 15
Column Diameter, 27
General Design Considerations, 31

REFERENCES, 35

DEFINITIONS

Gas purification, as discussed in this text, involves the removal of vapor-phase impurities
from gas streams. The processes which have been developed to accomplish gas purification
vary from simple once-through wash operations to complex multiple-step recycle systems. In
many cases, the process complexities arise from the need for recovery of the impurity or
reuse of the material employed to remove it. The primary operation of gas purification
processes generally falls into one of the following five categories:

1. Absorption into a liquid
2. Adsorption on a solid
3. Permeation through a membrane
4. Chemical conversion to another compound
5. Condensation

Absorption refers to the transfer of a component of a gas phase to a liquid phase in which it
is soluble. Stripping is exactly the reverse-the transfer of a component from a liquid phase in
which it is dissolved to a gas phase. Absorption is undoubtedly the single most important

1