System integration for combined heat and power (CHP) plants with post-combustion CO₂ capture

Based on a typical 1000 MW_e coal-fired power plant with ultra-supercritical parameters, this study proposes a new integration scheme for the combined heat and power (CHP) plant with post-combustion CO₂ capture. By introducing a back-pressure heat supply (BPHS) turbine and a back-pressure CO₂ capture (BPCC) turbine, the superheated degree of the extraction steam is effectively retrieved for parameter matching of CO₂ capture and heat supply. With 90% CO₂ capture efficiency and 785.06 MW_th heat supply, the total efficiency penalty for the CHP plants with solid amine-based CO₂ capture reaches 19.32%. To optimize the proposed integration scheme, over 90% of the waste heat in the CO₂ capture is recovered by applying the absorption heat exchanger (AHE) to increase the heating capacity of the integrated system. Energy analysis results show that the heating capacity of the integrated system is increased by 64.18%. Exergy analysis results reveal that the exergy destruction of the CO₂ capture process and the heat exchange between the primary and secondary heating networks is reduced by 40.27 MW_ex and 10.33 MW_ex. Economic analysis results show that the cost of electricity (COE) and the cost of CO₂ avoided (COA) are reduced by 2.59 $/MWh and 4.19 $/t CO₂.