Abstract:

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.

Key words: separated type heat pipe, low pressure economizer, energy conservation in power plant, flue gas waste heat utilization, equivalent enthalpy method, economic performance