Investigating the performance of circulating fluidized bed oxy-fuel combustion in a coal fired power plant

Abstract

This research presents a study on the oxy-fuel combustion of a coal-fired power plant. Thermodynamic approach is applied to evaluate the impact of operating parameters on the power plant in terms of the boiler efficiency, the turbine thermal efficiency and the net power capacity of the power plant. The GateCycle application used for design and performance evaluation of thermal power plant systems at both design and off-design condition. The model validation is based on the air-combustion power plant, the result of GateCycle and the design data at the boiler maximum continuous rating (BMCR) is comparable with a maximum error of approximately 1.56%. The gross power generation of the oxy-fuel combustion at 0.7 RFG ratio and oxygen concentration 0.95%mass compare with conventional combustion increases from 131.80MW to 135.11MW and energy loss of flue gas decreases from 27.5MJ/s to 13.8MJ/s. The operation condition of oxy-fuel combustion, the higher recycled flue gas ratio increases the net power generation, turbine efficiency and increases the concentration of CO2 in the flue gas. The boiler efficiency is increased by increasing the oxygen concentration. The heat recovery from recycled flue gas is investigated by integrating the heat exchanger before the feed water heater unit. The position of heat exchanger locates approach the boiler can be improve the boiler efficiency. The results are used as data to investigate the performance of the coal-fired power plant. The results of model show that the boiler efficiency is 86.20% to 85.55% when the recycled flue gas ratio at 0.71 to 0.75 and oxygen concentration at 0.95% mass is applied.