二次再热燃煤机组疏水梯级预热空气系统研究

Study on Drainage Cascade Preheating Air System in Double Reheat Coal-fired Unit

随着电力行业中新能源的冲击,燃煤发电机组发电效率亟待提高。针对燃煤机组空气预热系统中?损大,该文提出一种疏水预热空气集成旁通烟道余热利用新系统。利用回热加热器中的疏水来逐级加热一次空气,减少空气预热过程中的传热温差,同时引出高温风作为调温风与热一次空气掺混,降低了磨煤机前掺混温差。接着耦合旁通烟道系统,排挤了高品位的抽汽返回汽轮机中做功,使汽轮机组做功量明显增加。结果表明,机组传热过程?损失大幅降低,发电效率提升0.67%,发电标准煤耗减少3.47g/(kW·h);年度单位发电成本降低0.49$/(MW·h),实现机组节能降耗的同时,具有显著的经济效益。

With the impact of new energy in the power industry,the efficiency of coal-fired power generation needs to be improved urgently.For the large waste heat loss in the air preheating system of coal-fired units,a new system on drainage cascade preheating air integrated bypass flue was proposed.The drain water in the regenerative heater was utilized to heat the primary air step by step,which reduced the heat transfer temperature difference in the process of air preheating.At the same time,the high-temperature air was introduced as the temperature regulating air and mixed with the hot primary air to reduce the mixing temperature difference before grinding.The new system coupled with the bypass flue system;the high-grade extraction steam was excluded and returned to the steam turbine to work,which significantly increased the work done by the steam turbine unit.The results show that the heat transfer loss of the unit is significantly reduced,and the power generation efficiency is increased by 0.67%,the standard coal consumption for power generation is reduced by 3.47g/(kW·h),and the annual unit power generation cost is reduced by 0.49$/(MW·h).while saving energy and reducing consumption,and the unit has significant energy-saving benefits.