1 000 MW超超临界二次再热机组双机回热系统改造提效研究OA

[Objective]The installed capacity of China's new energy power is increasing year by year.Its randomness and volatility require coal-fired power units to have flexible peak-shaving capabilities and be able to achieve efficient operation under wide load.Therefore,it is necessary to carry out research on energy-saving and efficiency-increasing technologies for large-scale coal-fired power units under ultra-low load.In order to further enhance the energy-saving potential of ultra-supercritical units,it is necessary to retrofit the regenerative system of the unit.[Methods]In this paper,a 1 000 MW double-reheat ultra-supercritical unit is taken as the research object.From the perspective of the total energy system theory,it is proposed to add a regenerative steam turbine to the regenerative system to increase the power generation,and to realize the cascade utilization of steam heat energy by increasing the number of extraction stages using Ebsilon.The thermodynamic parameters of the unit under the 30%turbine heat acceptance(THA)condition and the 20%THA load condition under the reference scheme and the retrofit scheme are calculated and compared,and the optimization effect of the retrofit scheme is explored.[Results]The results show that compared with the reference unit,under the condition of 30%THA,the coal consumption rate of the modified unit is reduced by 6.279 g/(kW·h),the exergy efficiency is increased by 0.965%,the heat consumption rate is reduced by 2.213%,the thermal efficiency is increased by 1.05%,and the steam consumption rate is reduced by 0.038 kg/(kW·h).Under the condition of 20%THA,the coal consumption rate decreases by 11.480 g/(kW·h),the exergy efficiency increases by 1.633%,the heat consumption rate decreases by 3.860%,the thermal efficiency increases by 1.775%,and the steam consumption rate decreases by 0.069 kg/(kW·h).Under the condition of ultra-low load,adding regenerative steam turbine in the regenerative system of the unit can significantly reduce coal consumption and improve efficiency.[Conclusion]Under the condition of ultra-low load,the transformation scheme of double-machine regenerative system for large double-reheat unit has the effect of energy saving and efficiency improvement,which can be used as a reference for the energy saving transformation of similar units.