Mathematical modelling of absorption with chemical reaction in liquid phase in a tray column

Abstract

A methodology for the modelling and simulation of tray columns in which gas absorption is accompanied by a chemical reaction is suggested. The presented model is based on the concept of a non-equilibrium stage and the effect of chemical reaction is described by enhancement factors. Pseudo-enhancement factors are introduced for components in liquid phase which take part in the reaction but are not transferred through the gas-liquid interface. A method for calculation of these factors from enhancement factors of components in gas phase and reaction stoichiometry is suggested. The advantages of the so-called global approach to the solution of the system of non-linear algebraic equations forming the column model are shown; this approach enables simply to combine universal equations with specific equations valid for a particular case. An example of CO2 absorption into aqueous solution of K2CO3 and KHCO3 in a tray column illustrates the usefulness of the approach. The proposed model is compared with simplified models and models in which the concept of pseudo-enhancement factors is not included. The comparison proves the superiority of the presented model.