When designing scrubbing columns, one of the key steps is to calculate the number of equilibrium stages needed. This can be achieved for system where a component is removed from a vapour stream by a liquid stream, assuming that the vapour solvent and liquid stream are not mutually soluble, by using a McCabe-Thiele style construction.
The video below gives a quick summary of the derivation of the key lines needed for both stripping and scrubbing.
The graph below shows an example of the McCabe-Thiele style method for scrubbing. The key parameters can be varied to help understand how they affect the design.