Energy and exergy analyses of an improved recompression supercritical CO2 cycle for coal-fired power plant

An improved recompression S–CO2 cycle for coal-fired power plant is proposed in order to improve boiler thermal efficiency, increase cycle exergy efficiency, and resolve issues of regulating the working fluid temperature of the boiler rapidly and effectively. The models for energy and exergy analyses are built. Systematic comparisons between the improved S–CO2 cycle system and the original S–CO2 cycle system are carried out based on the detailed energy and exergy analyses. The results suggest that the improved S–CO2 cycle is excellent in both energy and exergy efficiencies, the thermal efficiency and exergy efficiency of the boiler in the improved S–CO2 cycle system are 94.68% and 53.41%, respectively, which are 1.04% and 2.76% higher than those of the original S–CO2 cycle system. The power efficiency of the improved S–CO2 cycle system is higher than that of the original one, which are 48.06% and 47.89%, respectively. The exergy efficiency of the entire cycle system of the improved S–CO2 cycle is 48.24%, which is 2.32% higher than that of the original S–CO2 cycle. In addition, the spray attemperator performance is investigated. The boiler in the improved S–CO2 cycle can regulate the working fluid temperature effectively.