Thermodynamic performance evaluation of supercritical CO2 closed Brayton cycles for coal-fired power generation with solvent-based CO2 capture

Power generation from coal-fired power plants represents a major source of CO2 emission into the atmosphere. Efficiency improvement and integration of carbon capture and storage (CCS) facilities have been recommended for reducing the amount of CO2 emissions. The focus of this work was to evaluate the thermodynamic performance of s-CO2 Brayton cycles coupled to coal-fired furnace and integrated with 90% post-combustion CO2 capture. The modification of the s-CO2 power plant for effective utilisation of the sensible heat in the flue gas was examined. Three bottoming s-CO2 cycle layouts were investigated, which included a newly proposed single recuperator recompression cycle. The performances of the coal-fired s-CO2 power plant with and without carbon capture were compared. Results for a 290 bar and 593 °C power cycle without CO2 capture showed that the configuration with single recuperator recompression cycle as bottoming cycle has the highest plant net efficiency of 42.96% (Higher Heating Value). Without CO2 capture, the efficiencies of the coal-fired s-CO2 cycle plants were about 3.34–3.86% higher than the steam plant and about 0.68–1.31% higher with CO2 capture. The findings so far underscored the promising potential of cascaded s-CO2 power cycles for coal-fired power plant application.