Optimization study of CO2 capture unit for subcritical coal-fired power generation unit based on Ebsilon and Aspen plus

Abstract

CO2 emissions from coal-fired power generation account for 70% of the total carbon emissions from the global power industry, thus it is essential to install CO2 capture unit (CCU) to coal-fired power generation units (CPGU), but this will cause a decrease in the thermal economy of the unit. Based on this, this paper takes 220 MW subcritical CPGU as the research object. An optimized CCU with integrated rich solvent split (RSS) process and CO2 compression intercoolers heat recovery (CIHR) process is constructed by Aspen Plus. Furthermore, an absorption heat pump (AHP) system driven by superheat of extracted steam is proposed to recover the waste heat of CO2-removed flue gas, and finally a novel CO2 capture CPGU coupled with AHP and optimized CCU is built and the thermal economy of the unit is simulated by Ebsilon. The results show that when the CO2 capture capacity is 500,000 tons/year, the optimized CCU reduces the regeneration energy consumption by 19.02% compared with the conventional CCU. When the unit load is 127.55 MW, the net electric power output of the novel CO2 capture CPGU is increased by 7.45%, the net generation efficiency is increased by 2.18%, the heat consumption is reduced by 887.31 kJ/kWh, and the standard coal consumption is reduced by 30.32 g/kWh compared with the conventional CO2 capture CPGU. The novel CO2 capture CPGU proposed in this study can significantly improve the thermal economy of the units and provide guidance for thermal integration of the CCU with the subcritical CPGUs.