Abstract: Increasing feedwater temperature is an important means to improve the thermal efficiency of unit operation cycle. Taking a 1000MW double reheat unit in a power plant as an example, by fully opening the steam admission control valve and bypass electric valve for the No.1 high pressure heater, the feedwater temperature at each load increased, and so did the flue gas temperature at denitrification device inlet. This operation mode can not only improve the economy of the unit, but also reduce the lower load limit of the denitration device.

Key words: feedwater temperature, economy； high pressure heater, steam admission control valve, bypass electric valve, partial load mode operation