Chapter 7: Membrane Gas Separation Processes for Post-combustion CO2 Capture
Published:06 Jul 2011
P. M. Follmann, C. Bayer, M. Wessling, and T. Melin, in Membrane Engineering for the Treatment of Gases: Gas-separation Problems with Membranes, ed. E. Drioli, G. Barbieri, E. Drioli, and G. Barbieri, The Royal Society of Chemistry, 2011, vol. 1, ch. 7, pp. 196-214.
Download citation file:
This chapter provides an integral view on membrane-based CO2 capture from coal-fired power plants. Since gas separation membranes do not feature the same selectivity towards CO2 as chemical absorption processes, a specification of the process boundary conditions up- and downstream of the membrane unit was performed first. The ongoing uncertainty regarding CO2 purity requirements resulted in the derivation of different purity scenarios. Subsequent to the selection of an appropriate membrane material, the generation of the driving force for CO2 permeation across the membrane was studied. Different options such as feed compression, suction at the permeate side or sweeping were reviewed with focus on large scale implementation in power plants. Since single-stage membrane processes are not able to achieve the required CO2 purity in conjunction with high CO2 recoveries, only two-stage membrane processes were examined in this work. A techno-economic analysis of two-stage membrane processes with and without recycling streams provided insight into economics and related energy consumption, CO2 recovery and CO2 avoidance costs. The techno-economic analysis revealed that post combustion CO2 capture by membranes appears feasible. Nevertheless, the CO2 product stream contains at least 1 vol.% of O2, thus violating strict purity requirements as for enhanced oil recovery.