Hybrid physical-chemical absorption process for carbon capture with strategy of high-pressure absorption/medium-pressure desorption

Abstract

Based on the conception of controlling the total energy consumption of CO2 capture process, this work proposed a hybrid physical-chemical absorption process, combined the traditional methods of physical absorption and chemical absorption, and adopted the strategy of high-pressure absorption/medium-pressure desorption, in order to achieve the reduction of total energy consumption of CO2 capture technology. The proposed process consisted of three main steps: physical absorption and desorption, chemical absorption and desorption, and compression with intercooling. Commercially used dimethyl ether of polyethylene glycol and methyl diethanolamine were selected as the physical absorbent and chemical absorbent, respectively. The process scheme was constructed and simulated for capturing CO2 from industrial high-pressure and CO2-rich gas to liquid CO2 product under pressure of 15 MPa. The total energy consumption was 0.1810 MWh·t−1 CO2, which was markedly lower than that of the traditional methods. Sensitivity analyses were carried out to investigate the effects of the key system parameters, including the desorption pressure and the allocation of the capture rate between the physical absorption and chemical absorption, on the performance of the hybrid physical-chemical absorption process. Additionally, the mechanism of energy conservation of hybrid physical-chemical absorption process was further elaborated in a strategy of high-pressure absorption/medium-pressure desorption.