Techno-economic evaluation of cryogenic CO 2 capture—A comparison with absorption and membrane technology

Abstract

Abstract A techno-economic evaluation of a novel cryogenic post-combustion CO 2 capture technology is presented in this work. The process concept is based on the periodic operation of cryogenically cooled packed beds. A process cycle consists of three consecutive steps: a cooling, capture and recovery step. The bed is first cooled down to temperatures below −120 ° C during the cooling step, possibly using cold energy released during the evaporation of LNG. Flue gas is fed to the refrigerated packed bed during the capture step. The flue gas will be cooled down and components as H 2O and CO 2 will condense and desublimate respectively at the packing surface, while permanent gases such as N 2 will pass through the bed without undergoing any phase change. In a final recovery step the stored components will be recovered from the bed by recycling CO 2 for CO 2 recovery and air for H 2O recovery. A basic process design focusing on the CO 2/N 2 separation for a 600 MW coal fired power plant is given in this work and the CO 2 avoidance costs are calculated. The influence of several process parameters is investigated, lower initial bed temperatures and higher CO 2 concentrations in the feed result in more efficient use of the bed volume. The pressure drop over the system plays an important role in the process economics, due to the high flow rates required in the process. The cryogenic concept is compared to two competing technologies: amine absorption and membrane separation. The results show that the preferred technology highly depends on assumptions related to the availability of utilities.