On the premise of keeping the reheater tubes' wall temperature in the designed range

increasing the reheat steam temperature is a very important project. By taking a 1 000 MW double reheat unit tower type boiler as the research object

this paper elaborates the method for metal temperature optimal adjustment while the reheat steam temperature is improved

in which the hedge arrangement of two horizontal layers of flue gas recirculation angle is adjusted to the layout scheme that the lower recirculation horizontally offset tangent is the maximum and the upper tangent center

meanwhile the SOFA horizontal pendulum angle is regulated from disorderly arrangement to hedge arrangement

the mill operation mode combination is adjusted from ABCDEF to ABCDE. After the optimization

under the rated load

the high pressure/low pressure reheat steam temperature increased from 603.4 ℃/601.4 ℃ to 612.5 ℃/612.7 ℃

the effect is obvious. However

limited by the heat absorption deviation between tube bundles

the temperature of both sides of the tube wall is low

and the improvement of difference between the maximum and minimum wall temperature is not obvious. It is suggested the method of reforming the throttling ring or heating surface be adopted to increase the heat absorption at the low point of wall temperature or to reduce the heat absorption at the high point of the wall temperature.