MASS TRANSFER ANALYSIS AND SIMULATION OF A HOLLOW FIBER GAS-LIQUID MEMBRANE CONTACTOR.

A steady state model was developed for a hollow fiber membrane contactor to describe gas absorption performance. Countercurrent absorption of pure CO2, pure SO2, CO2-N2 and SO2-N2 mixtures in diethanolamine solution (DEA), and water as the absorbent were investigated. The model is able to predict gas phase concentration and the velocity profile in the axial direction inside the shell, as well as the liquid concentration profile in both the axial and radial direction inside the fibers. A numerical scheme was proposed to solve the simultaneous mathematical expressions that were obtained based on concepts of mass transfer, and the results were validated with experimental data found in the literature. Axial variations of gas velocity, gas concentration and a two dimensional concentration profile of the liquid phase were compared for three absorbing systems, including low (CO2-water), moderate (CO2-DEA) and high (SO2-water) absorption rates. The effect of chemical reaction on the importance of external resistance was also studied using this model. It was found that the shell side and membrane resistances are negligible in comparison with the liquid resistance in low absorption rates, for example in a CO2-water system, however they have significant effects when the chemical reaction is fast and the absorption rate is high, such as SO2-water system.