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

Highlights: • Supercritical CO₂ cycle was investigated for coal-fired power plant application. • Three s-CO₂ cycles were investigated as possible bottoming cycle options. • Integration of coal-fired plant with post-combustion CO₂ capture was studied. • Thermodynamic analysis and performance comparison were performed. -- Abstract: 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.