When the solution is quite dilute (say less than 1% solute in both gas and liquid), the total liquid and gas flow rates will not change significantly since little solute is transferred. The column was shown in Figure 12-1 and the operating equation was given in Eq. (12-6).
To use Eq. (12-6) in a McCabe-Thiele diagram, we assume the following:
1. L/V (total flows) is constant.
2. Isothermal system.
3. Isobaric system.
4. Negligible heat of absorption.
These are reasonable assumptions for dilute absorbers and strippers.