Aspen plus supported design of pre-combustion CO<inf>2</inf> capture processes based on ionic liquids

Abstract

H2 production processes from steam methane reforming and combined cycle power plants require carbon dioxide removal from raw synthesis gas to obtain a useful H2-rich product stream. In this work, a wide variety of operating configurations were techno-economically evaluated in Aspen Plus commercial process simulator to improve the efficiency and costs of the pre-combustion CO2 capture process based on chemical absorption using [P2228][CNPyr] ionic liquid. Multiple absorption (from 30 °C to 70 °C) and regeneration (between 90 °C and 120 °C) temperatures were tested along with four different regenerating pressures: 0.1, 0.25, 0.5 and 1 bar. Energy and solvent consumptions and capital and operating costs were calculated for nine configurations using the COSMO-based/Aspen methodology combined with Aspen Economic Analyzer tool. The most promising results were obtained when regenerating the IL at 1 bar and at elevated absorption and regeneration temperatures, due to the higher operating and equipment costs associated with vacuum and the greater utilities cost related to heat transfer when the gap between both temperatures grows. The minimum cost achieved was 64.1$/tCO2 considering an IL scaled up price of 50 $/kg, but it could even be further less than 40 $/tCO2 goal for new generation solvents, when only direct costs were considered