An Investigation of Hybrid Membrane/Chemical Absorption CO2 Capture Processes in Coal-fired Power Plant

Abstract

Post-combustion CO2 capture technologies such as traditional amine-based chemical absorption and membrane-based gas separation have been widely investigated for reducing CO2 emissions in the power sector. However, most of these technologies are constrained by the low CO2 concentration in the flue gas and thus a high energy demand is unavoidable. This paper reports on two types of hybrid membrane/chemical absorption processes for post-combustion CO2 capture. Both of these combine membrane-based gas separation technology (Polyactive®) with monoethanolamine (MEA)-based chemical absorption technology. In one type of the hybrid capture process, the two technologies are arranged in series and in the other, in parallel. Parametric studies were first conducted for a standalone cascaded membrane separation process and standalone MEA-based chemical absorption process, respectively, to optimize their energy consumption. Then, a comparison was made between the hybrid processes, standalone cascaded membrane separation process and standalone MEA-based chemical absorption process, respectively, with respect to the efficiency penalties caused by them. It was found that the hybrid process in the parallel arrangement, with a split fraction of 0.25 to 0.75, resulted in the lowest efficiency penalty of 9.7%-pts.