带废热回收的预干燥燃褐煤发电系统理论研究

在褐煤发电系统中,对褐煤进行预干燥可以明显提高燃褐煤发电系统效率,而褐煤预干燥过程中产生的干燥尾气废热的回收利用可以进一步提高系统效率。为了研究尾气废热回收对系统效率的影响,该文建立了干燥机热平衡模型,并且应用等效热降法建立了该系统干燥尾气废热回收的理论分析模型。该文针对某600 MW燃褐煤机组,对其干燥尾气废热回收的节能潜力进行了分析,并且对干燥机、原煤预热器和给水加热器热效率对整厂热效率的影响进行了计算。计算结果表明:在基准工况下采用原系统,可以节煤11.44 g/(kW h),而采用废热回收,系统的节煤量可提高到14.65 g/(kW h);干燥机效率对整厂效率的影响最为明显,干燥机效率每提高10%,可以增加节煤量达1.8 g/(kW h)。

Theoretical Study on a Pre-dried Lignite-fired Power System With Waste Heat Recovery

Lignite pre-drying can improve lignite-fired power system efficiency obviously,and the waste heat recovery can improve efficiency further.In order to consider the effect of waste heat recovery on the system thermal efficiency,this paper established the thermal equilibrium model of the dryer and the theoretical analysis model of waste heat recovery with the application of equivalent heat drop method.The energy saving potential with waste heat recovery was analyzed on an existing 600 MW lignite-fired power plant,and the influence of dryer efficiency,coal preheater efficiency and water heater efficiency on system efficiency improvement were calculated.The results show that: coal consumption rate reduction of pre-dried lignite-fired power system improves from 11.44 g/(kW h) to 14.65 g/(kW h) with waste heat recovery;the dryer efficiency is the most obvious factor on system efficiency,and when 10% higher dryer efficiency is improved the coal consumption rate can increase 1.8 g/(kW h).