Simulation study on 660 MW coal-fired power plant coupled with a steam ejector to ensure NOx reduction ability

A 660 MW supercritical coal-fired power plant coupled with a steam ejector is proposed to increase the feedwater temperature, which is used to ensure the NOx reduction ability under a low load. The simulation work for the system performance under different steam sources of feedwater heater, feedwater regenerative heating systems and steam sources of steam ejector is carried out. Results indicate that it's a favorable choice to increase the water temperature through adding No. 0 feedwater heater coupled with steam ejector, because NOx removal efficiency increases from 68.97% (benchmark condition) to 74.66% under 50% THA condition, and it would improve the plant thermal efficiency while the standard coal consumption rate would decrease 0.5 g (kW h)⁻¹. Meanwhile, results conclude that it has superior performance than the system by No. 1 feedwater heater coupled with steam ejector. Finally, it's found that it is more suitable when the primary flow is from the platen superheater outlet. It also finds that the system performance (the induced flow is from No. 1 steam extraction) is more efficient compared with systems that the induced flow is from the cold or hot reheat steam.