A two-dimensional mathematical model for removal of acid gases (H2S and CO2) by methyl diethanol amine in a commercial sieve tray column has been developed. The velocity profile in the liquid both in radial and axial directions of each plate has been calculated by Eulerian–Eulerian computational fluid dynamics framework. In order to establish the temperature and concentration profiles in radial and axial directions of plates, mass and energy balance equations have been developed and solved numerically. A non-equilibrium rate based method combined with the two-film theory has been considered to obtain concentration profile. In this model most of the important parameters in the gas absorption process have been included, therefore one can expect that the model will be able to predict the performance of the columns at wide ranges of operating conditions. The results obtained by the model using operational data of a commercial plant indicate that there exists appreciable distribution of velocity, concentration and temperature in radial and axial directions. More interesting finding is that the extent of these distributions decline from bottom to top of the column as is expected. In fact, good agreement was noticed when the results of model were compared with operating conditions of an industrial column.

Keywords