Mathematical modeling of CO2 absorption into novel reactive DEAB solution in hollow fiber membrane contactors; kinetic and mass transfer investigation

Abstract

In this study, 4−diethylamino−2−butanol (DEAB) has been applied as a novel amino alcohol absorbent in a gas–liquid hollow fiber membrane contactor (HFMC) for CO2 separation from a CO2/N2 gas mixture. A comprehensive 2−D mathematical model based on the finite element method (FEM) was developed to solve the applied partial differential equations for the shell, tube and membrane sides of a gas–solvent HFMC. The proposed model was validated using the available experimental data in the literature and the modeling results were in consistent with the experimental data. To investigate the influence of solvent on separation performance of a non−wetted mode of HFMC, the absorption of CO2 using DEAB is compared with other common industrial solvents such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA) and methyldiethanolamine (MDEA). Under moderate operating conditions, the impact of parameters such as liquid and gas flow rates, concentration, temperature and CO2 partial pressure on the performance of a HFMC have been examined. Sensitivity analysis of operating conditions reveals that mass transfer resistance of gas phase is more significant than mass transfer resistance of liquid phase and the major mass transfer resistance is located in the gas phase. The modeling results indicated that the percentage absorption of CO2 into DEAB solution was competitive with MEA solution, however much higher than DEA, MDEA and TEA solutions in all range of liquid and gas flow rates and also partial pressure. It was concluded that increasing temperature, absorbent concentration, liquid flow rate and also decreasing gas flow rate enhance the removal of CO2.