Thermo-economic analyses of IGCC power plants employing warm gas CO2 separation technology

Abstract

Integrated gasification combined cycle (IGCC) power plant with dual-stage Selexol™ for carbon capture is compared to pressure swing adsorption (PSA)-based warm gas CO2 capture. Capture with Selexol™ was limited to 83.4% due to high syngas CH4 content while the efficiency was 31.11% HHV resulting in a 1st year cost of electricity (COE) of 148.6 $/MWh. Carbon capture can be increased to 88.6% and efficiency to 33.76% HHV with warm gas CO2 removal. When holding the same carbon capture level as the Selexol™ case, efficiency is increased to 34.20% HHV and after further optimization of the water gas shift (WGS) reactors to 35.63% HHV leading to a lower COE of 127.2 $/MWh. Reaction kinetic models are developed and applied for optimization of WGS reactors to convert syngas CO to CO2. Cost for warm gas carbon capture reduced to 47.5 $/tonne from 66.0 $/tonne for IGCC without carbon capture while CO2 avoided cost reduced from 89.4 $/tonne to 54.3 $/tonne. Carbon capture cost dropped from 88.0 $/tonne to 72.7 $/tonne while the CO2 avoided cost decreased from 112.2 $/tonne to 78.3 $/tonne over supercritical boiler plant without carbon capture. Furthermore, warm gas cleanup lowered the specific net water withdrawal/usage by 13.4%.