Analysis and comparison of the membrane-cryogenic hybrid process and multistage membrane process for pre-combustion carbon capture based on the superstructure method

Abstract

The feed in pre-combustion carbon capture has a high CO2 concentration and high pressure, which gives membrane technology and membrane-based hybrid technology a strong separation driving force. Because the membrane-cryogenic hybrid method can inexpensively achieve the high CO2 purity and recovery, it offers a novel approach in addition to traditional separation methods. Nevertheless, it is uncommon to consider the combination of membrane materials and processes. Furthermore, investigations comparing multistage membrane processes with membrane-cryogenic hybrid processes under identical conditions are lacking. Therefore, this paper establishes separately the membrane-cryogenic hybrid processes and multistage membrane process by the superstructure method, which considers the number of membrane stage, membrane material type, and operating parameters simultaneously. The optimal process structures for three-stage membrane, cryogenic-membrane process, and membrane-cryogenic process are investigated and compared. The influences of membrane price and electricity price on the CO2 capture cost are also investigated. Results shows that the CO2 capture cost of cryogenic + membrane process is the lowest (11.69 $/t CO2) of the studied processes at 96 % CO2 purity and 90 % CO2 recovery. The system structure of the cryogenic + membrane process varies with CO2 purity and recovery. Electricity price has a more important impact on the CO2 capture cost than membrane price under the optimized conditions.