Modeling and Simulation of Absorption Column of Natural Gas Sweetening Unit by Mass Transfer Method

The most common and widely used solvent for gas sweetening, are amines. In recent years, the use of mixed amines for this purpose in the natural gas industry of the world has expanded significantly. Modeling of the absorption and desorption columns of gas sweetening units is obtained by the three methods: equilibrium, non- equilibrium and mass transfer. Using of mass transfer model was first performed in 1986 by Leye and Froment. In this paper, with the correction and development of the Leye and Froment model and using of mass transfer method, a model is proposed for the simulation of the absorption of hydrogen sulfide and carbon dioxide by mixed amines (DEA and MDEA) in the absorption column of gas sweetening unit in one of the gas refineries in our country. In this model, the two film theory has been used in order to calculate mass transfer rate and the liquid phase stream on the tray is considered as mixed and the gas phase stream is considered as plug. MATLAB programming was utilized to solve the derived systems of equations with minimum mathematical complexity. The obtained results were observed to be of good agreement with operational data and in comparison with the results of the Leye and Froment model (compared to operational data).