Introduction

A general study of absorption can be confusing since the calculation methods for the two major types are quite different. First, there is hydrocarbon absorption using a lean oil having hydrocarbon components much heavier than the component absorbed from the gas stream. These absorbers may or may not be reboiled. For designing these, one uses equilibrium vaporization constants (K values) similarly to distillation. Another similarity to distillation is the frequent use of fractionating trays instead of packing. Canned computer distillation programs usually include hydrocarbon absorber options.

The other major type is gas absorption of inorganic components in aqueous solutions. For this type design one uses mass transfer coefficients. Packed towers are used so often for this type that its discussion is often included under sections on packed towers. However, in this book it is included here.

Hydrocarbon Absorber Design

Because of its similarity to distillation, many parts of this subject have already been covered, such as

1. Tray Efficiency

2. Tower Diameter Calculations

3. K Values

As for distillation, shortcut hand calculation methods exist, for hydrocarbon absorption. In distillation, relative volatility ( ?) values are generated from the K values. For hydrocarbon absorption the K values are used to generate absorption and stripping factors. The 1947 Edmister1 method using effective overall absorption and stripping factors and the well-known Edmister graphs are very popular for hand calculations. An excellent write-up on this and the Kremser-Brown-Sherwood...