基于蒸汽喷射式热泵的火电厂除氧器乏汽回收系统热经济性分析

Thermo-economic Analysis of Deaerator Exhaust Steam Recovery System with Steam Ejector Heat Pump

针对火电厂汽轮机回热系统中的工质损失和热损失,以某电厂600MW机组为例,对采用蒸汽喷射式热泵将除氧器乏汽回收到低压加热器中的节能技术进行研究,利用等效焓降法对各个节能方案的热经济性指标进行了计算,并对不同节能方案的热经济性进行了比较.结果表明:除氧器乏汽通过蒸汽喷射式热泵回收到5号低压加热器(方案4)的节能效果最显著,经济效益最好.与原方案相比,采用方案4,每发1度电平均可以节约标准煤0.3g,按机组年运行5 500h计算,每年可以节约标准煤990t.

To minimize the loss of heat and working medium from heat recovery system of steam turbines, energy-saving schemes were proposed for recovering exhaust steam from deaerator to low-pressure heater of a 600 MW unit using steam ejector heat pump, of which corresponding thermo-economic indexes were respectively calculated and compared using equivalent enthalpy drop method. Results show that among all the energy-saving schemes, scheme No. 4 will produce the highest economic benefits when the exhaust steam is led to the No. 5 low-pressure heater from deaerator by steam ejector heat pump. Compared with the original scheme, scheme No. 4 may economize 990 t standard coal per year, based on the assumption that 0.3 g standard coal is saved for generation of 1 kW h power and the unit annually operates for 5 500 h.