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

摘要

This study evaluates three different solvent absorption processes for the pre-combustion capture of CO_2 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, CO_2 capture process and the gas turbine and steam turbine combined cycle plant. IGCC without capture yielded an efficiency of 45.02%. For the CO_2 capture processes at 90% CO_2 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.