Optimization of novel hybrid cryogenic CO2 capture process with membrane separation

As an effective means of greenhouse gas emission control, CO2 capture has become an important research topic. As one of the emerging technologies, cryogenic CO2 capture has received attention due to its technological advantages in product purity. However, energy consumption and CO2 recovery in the cryogenic CO2 capture are very sensitive to feed gas CO2 concentration, and the high CO2 concentration feed gas is beneficial for obtaining a higher CO2 recovery and a lower energy consumption level simultaneously. Therefore, a novel hybrid cryogenic CO2 capture process with membrane separation was proposed. The feed gas CO2 concentration was actively controlled by membrane selectivity, hence cryogenic CO2 capture was carried out at the optimal concentration. In this paper, based on the characteristics of different traditional cryogenic capture processes, different hybrid process modes were compared and analyzed to determine the optimal hybrid process structure. The optimal operating parameters of the hybrid process were determined, and the relationship between membrane permeate side CO2 concentration and feed gas CO2 concentration was obtained based on the goal of achieving the lowest energy consumption and the highest CO2 recovery, providing guidance for the selection of membrane modules in the hybrid process. The energy consumption of the proposed hybrid process is 1.92MJ/kgCO2, which was reduced by 16.5% compared to the traditional cryogenic process. © 2020, Chemical Industry Press. All right reserved.