Performance and sensitivity analysis of packed-column absorption process using multi-amine solvents for post-combustion CO2 capture

Abstract

Although many novel multi-amine solvents with high CO2 solubility were reported, they have not yet been evaluated for the performance in CO2 absorption processes. In this study, the efficiency and inside profile of the packed-column CO2 absorption process using a novel multi-amine solvent were investigated by using a mathematical model. Three amine solvents were selected: 2-(2-aminoethylamino)-ethanol (AEEA) and diethylenetriamine (DETA) as multi-amine solvents and monoethanolamine (MEA) as a reference. Based on the 90% capture efficiency of flue gas CO2 from a coal-fired power plant, a sensitivity analysis using the liquid-to-gas ratio was conducted to minimize the energy consumption for CO2 capture. Based on the utilization of the same 30 wt% solvent, the lowest reboiler thermal energy achieved by the process using DETA was 3.242 GJ/tonCO2, which was 8.57% lower than that obtained when MEA was employed. In contrast, the process using AEEA required 7.04% higher energy than MEA. In the process modified by rich-solvent split for further enhancing efficiency, the DETA process could achieve 2.962 GJ/tonCO2, which reduced the reboiler duty by 16.8% from the MEA process. The CO2 capture performance of absorbents could not be evaluated not only by the absorption rate and capacity. Owing to the larger molecular weight of multi-amines than MEA, the performance of capture and regeneration was discussed with respect to the amine properties and number of amine moles in the solution. A well-selected multi-amine for a modified process configuration has considerable potential for improving the energy efficiency of CO2 capture.