Effect of Gland Heater Disposal Method on the Unit Thermal Economy

300MW unit is taken for example in this paper, two calculation methods are used in heat balance calculation. One is that No.8 low-pressure heater, gland heater and condenser hot well are regarded as a whole to list heat balance equation, and the other is that only No.8 low-pressure heater is regarded as a whole to list heat balance equation. Then, the paper analyses and compares difference between two calculated results under conditions of steam turbine load variation and emergency drainage occurs in low-pressure heater. Meanwhile, in view of drainage flash evaporation in condenser hot well, the calculation method with respect to heater´s drainage flash evaporation is given. The conclusions are significant to further improve the accuracy of steam turbine thermal system calculation and study the change mechanism of steam turbine heat economy.