Integration aspects of reactive absorption for post-combustion CO2 capture from NGCC (natural gas combined cycle) power plants

Abstract

Reactive absorption of CO2 with MEA (monoethanolamine) has been established as the preferred reference technology in benchmark studies of novel post combustion CO2 capture technologies. However, recent advances in solvents tailored for CO2 capture warrant an updated reference for consistent performance comparisons. Moreover, as innovative solvent concepts require desorption heat at varying temperatures, SRDs (specific reboiler duties) are not directly comparable. This paper estimates the specific capture and compression work for two different solvents with varying SRD as a method to rapidly assess the CO2 capture energy penalty. To confirm the results, full process simulations are presented for the NGCC (Natural Gas Combined Cycle) with post combustion capture using a novel amine-based solvent and compared to MEA. Desorber pressure, exhaust gas recirculation ratio and reboiler approach temperature is varied. For identical operating conditions, the novel solvent increases the net plant efficiency from 49.4% to 50.4% compared to MEA. However, although an increased desorber pressure reduces SRD by 8%, the net efficiency is virtually constant. This illustrates the difference between reduced SRD and improved net plant efficiency and the importance of systems level analysis. The best net efficiency, with EGR (Exhaust Gas Recirculation) and 5 °C reboiler approach temperature, for the novel solvent corresponds to a 6.2%pt capture penalty.