1000MW超超临界汽轮机排汽焓和冷端能量损失模型

A Model of Exhaust Enthalpy and Energy Loss in Cold End for 1000MW USC Steam Turbines

建立凝汽式汽轮机冷源损失热量和排汽焓的计算模型,实时分析负荷和机组状态对冷端损失、低压缸排汽湿度和凝汽器总体换热系数的影响规律。基于别尔曼公式的形式,提出凝汽器总体换热系数的经验预测公式。结果表明,冷端能量损失百分比随负荷增大而单调降低。冷端能量损失占机组总输入能量的48.4%,占总能量损耗的85%~88%。低压缸排汽焓随负荷增加而单调降低,排汽湿度随负荷增加而单调增大。低负荷下,低压缸排汽为微过热蒸汽;高负荷下,低压缸排汽为饱和湿蒸汽。凝汽器总体换热系数随负荷增加而单调增加,且正比于低压缸排汽流量。

A model was developed to study the effects of the unit load and conditions on the exhaust enthalpy, steam humidity, energy loss in cold end and total heat transfer coefficient of the condenser in real time. The prediction model of the total heat transfer coefficient of the condenser was then presented based on the form of Biermann＇s formula. The results show that the percentage of energy loss in cold end decreases with the increase of unit load. The energy loss in cold end may take up 48.4% of the total energy input and 85%-88% of the total energy loss. With the increase of unit load, the exhaust enthalpy of the low pressure cylinder decreases while the exhaust steam humidity increases. The exhaust steam at lower unit load is slightly superheated, while the exhaust steam at higher unit load is saturated wet steam. The total heat transfer coefficient of the condenser increases with the increase of unit load and the amount of exhaust steam.