An assessment of different solvent-based capture technologies within an IGCC–CCS power plant

Abstract

This study evaluates three different solvent absorption processes for the pre-combustion capture of CO2 for a black coal IGCC (Integrated Gasification Combined Cycle) power-plant, with the aim of determining the best solvent process for pre-combustion capture. The three solvent processes are MDEA (mono diethanolamine), hot potassium carbonate and Selexol™. The study involves detailed thermodynamic models of the entrained flow gasifier, synthesis gas processes, CO2 capture process and the gas turbine and steam turbine combined cycle plant.IGCC without capture yielded an efficiency of 45.02%. For the CO2 capture processes at 90% CO2 capture, the power generation efficiencies are almost identical for MDEA and Selexol™ with 36.39% and 36.42%, respectively. The IGCC with the hot potassium carbonate process yielded the highest efficiency with 37.33%. This improvement is attributed to the higher operating temperature of the absorber which allows water vapor in the synthesis gas to be sent to the gas turbine resulting in a greater power production from the gas turbine.A multi-objective optimization is performed by varying different decision variables in the IGCC with the hot potassium carbonate capture process. By optimizing these variables, an efficiency of 39.31% is obtained – a 2% point improvement for 90% capture.