Thermoeconomic investigation of pressurized oxy-fuel combustion integrated with supercritical CO2 Brayton cycle

Pressurization is expected to increase the power efficiency of oxy-fuel combustion plant. Supercritical CO2 (sCO2) Brayton cycle could yield higher thermal efficiencies at lower capital cost than the state-of-the-art steam-based power cycles. The coupling of pressurized oxy-fuel combustion and sCO2 cycle could potentially offer higher net power efficiency over its counterparts with CO2 capture. In this paper, pressurized oxy-fuel combustion was integrated with three different sCO2 Brayton cycle layouts, i.e., single reheated recompression, double reheated recompression, and intercooled recompression. The systems were analyzed from the perspective of thermodynamics and economics. The net power efficiencies for the three systems were 39.4%, 40.2%, and 41.3%, respectively. The effect of boiler pressure on the latent heat recovery of the flue gas was analyzed. In the sensitivity analysis, the influence of turbine inlet temperature, turbine inlet pressure, turbine inlet temperature, turbine outlet pressure, recirculated fan pressure boost, and the high-temperature recuperator (HTR) split ratio on the plant net power efficiency was assessed. Finally, the economic analysis was conducted. The levelized cost of electricity (LCOE) of the three systems were 103.18 $/MWh, 108.45 $/MWh, and 110.07 $/MWh, respectively. The results showed that the integrated systems were attractive as potential candidates for the coal-fired power generation with CO2 capture.

Automated summary

Pressurization increases power efficiency, and coupling it with a supercritical CO2 Brayton cycle offers higher efficiency than steam-based power cycles with CO2 capture. Three layouts of the coupled system were analyzed thermodynamically and economically, with net power efficiencies of 39.4%, 40.2%, and 41.3%. Sensitivity analysis evaluated the impact of various factors on net power efficiency, and economic analysis showed their attractiveness for coal-fired power generation with CO2 capture.