Kinetic study and process model development of CO2 absorption using hollow fiber membrane contactor with promoted hot potassium carbonate

Abstract

In this study, application of hollow fiber membrane contactor (HFMC) as an appropriate technology for absorption of CO2 from gas mixture is proposed. A mathematical model is developed based on a new kinetic for prediction of “non−wetted” mode of HFMC performance in the presence of hot potassium carbonate promoted by diethanolamine (DEA). The model validation results show an appropriate agreement with experimental data which is reported in literature. Study of some related parameters on CO2 removal efficiency indicates that increasing the liquid flow rate and number of fibers have positive effect on the CO2 absorption, whereas enhancing the gas flow rate decreases the rate of absorption. The results show that the counter−current operation mode has better performance with respect to co−current flow. Also when gas and liquid phases pass through the tube and shell sides respectively, due to increasing the contact surface in the liquid phase, the CO2 absorption will occur with higher efficiency than the case of gas flow in the shell side. Investigation of different absorption solvents indicates that the order of absorption rate of solvents is as follows: promoted hot potassium carbonate>2-amino-2-methyl-1-propanol (AMP)>DEA>methyldiethanolamine (MDEA)> blend of MDEA and DEA. Modeling analysis reveals that due to higher absorption rate of promoted hot potassium carbonate with respect to other solvents, the required operating temperature for chemical absorption is lower than other solvents and as a result, this advantage also improves physical absorption.