分离式热管换热器与低压省煤器的性能分析

根据火电厂热系统节能理论,对低压省煤器(low pressure economizer, LPE)系统利用电站锅炉排烟余热加热凝结水进行了节能定量分析,同时分析了分离式热管换热器的工作原理与传热机理。结合某320 MW凝汽机组参数,应用等效焓降法,对分离式热管换热器与低压省煤器进行了经济性与可靠性分析比较。结果表明,分离式热管换热器具有等壁温防低温腐蚀的优点,但结构布置的特点导致其更易积灰。分离式热管换热器加热的凝结水温度受热管工质饱和温度的限制,排挤抽汽的能级低,回收相同的烟气热量,低压省煤器的节能量约为相同换热面积分离式热管换热器的2倍。

Performance analyses of separated type heat pipe and low pressure economizer

Based on the theory of energy conservation for a power plant thermal system, the energy conservation of a the low pressure economizer(LPE) system was quantitatively analyzed, which could recover the flue gas waste heat from power station boiler to heat the condensation water. The operating principle and heat-transfer mechanism of a separated type heat pipe(STHP) were discussed. The economic performance and reliability for STHP and LPE of the parameters of a 320MW condensing unit were respectively analyzed using the equivalent enthalpy method. The results showed that all the tube wall temperatures of STHP were uniform, which could help to avoid cold end corrosion, while the layout of STHP could easily lead to ash deposition. The heated condensation water temperature was limited to the saturation temperature inside STHP. So the saving extraction steam of STHP had a lower energy level. The amount of energy saving of LPE was double compared with STHP with the same heat transfer areas and flue gas temperature decrease.