Chapter 15. Mass Transfer Analysis

Up to now we have used an equilibrium stage analysis procedure even in packed columns where there are no stages. A major advantage of this procedure is that it does not require determination of the mass transfer rate.

In packed columns, it is conceptually incorrect to use the staged model even though it works if the correct height equivalent to a theoretical plate (HETP) is used. In this chapter we will develop a physically more realistic model for packed columns that is based on mass transfer between the phases. After developing the model for distillation, we will discuss mass transfer correlations that allow us to predict the required coefficients for common packings. Next, we will repeat the analysis for both dilute and concentrated absorbers and strippers and analyze cocurrent absorbers. Finally, a simple model for mass transfer on a stage will be developed, and the estimation of stage efficiency will be considered.