Proposal and investigation of a high-efficiency coal-fired power generation system enabled by chemical recuperative supercritical water coal gasification

Gasification process is a promising technology for efficient and clean utilization of solid fuels that has been attracting increasing attention. This paper proposes a high-efficiency coal-fired power generation system enabled by chemical recuperative supercritical water coal gasification. The main feature is that the reaction heat of gasification process is supplied by the high-temperature flue gas generated by the gas turbine, which can be achieved by adjusting the pressure ratio. Since coal can be converted into clean syngas with supercritical water at 600–700 °C without the oxidation of part of the fuel to provide reaction heat, the exergy destruction of gasification process is decreased dramatically and a small amount of chemical energy of coal is converted into thermal energy. The results showed that in the proposed system and reference system, the net power generation efficiencies are 53.8% and 48.9%, respectively; and the corresponding exergy efficiencies are 52.5% and 47.7%, respectively. It is observed that in the proposed system, the net power generation and exergy efficiencies increased by 4.9 and 4.8% points, respectively. Additionally, the mechanism of exergy destruction reduction is revealed by the graphical exergy analysis, and the comprehensive cascade utilization of chemical and thermal energy is realized.