Abstract
Membrane separation technology for CO(2) capture in pre-combustion has the advantages of easy operation, minimal land use and no pollution and is considered a reliable alternative to traditional technology. However, previous studies only focused on the H(2)-selective membrane (HM) or CO(2)-selective membrane (CM), paying little attention to the combination of different membranes. Therefore, it is hopeful to find the optimal process by considering the potential combination of H(2)-selective and CO(2)-selective membranes. For the CO(2) capture process in pre-combustion, this paper presents an optimization model based on the superstructure method to determine the best membrane process. In the superstructure model, both CO(2)-selective and H(2)-selective commercial membranes are considered. In addition, the changes in optimal membrane performance and capture cost are studied when the selectivity and permeability of membrane change synchronously based on the Robeson upper bound. The results show that when the CO(2) purity is 96% and the CO(2) recovery rate is 90%, the combination of different membrane types achieves better results. The optimal process is the two-stage membrane process with recycling, using the combination of CM and HM in all situations, which has obvious economic advantages compared with the Selexol process. Under the condition of 96% CO(2) purity and 90% CO(2) recovery, the CO(2) capture cost can be reduced to 11.75$/t CO(2) by optimizing the process structure, operating parameters, and performance of membranes.