Energy & Fuels, Vol.26, No.9, 5804-5820, 2012
Research on Retrofit Schemes for Reheat Steam Underheating and Excessive Desuperheater Spray for a 600 MW Tangentially Coal-Fired Boiler
Reheat steam underheating, excessive desuperheater water, and temperature deviation at the furnace outlet are common problems of the large scale tangentially coal-fired boilers both in China and abroad. It is thus very important to develop an effective retrofit scheme to settle the problems. Truncation of partition platen superheater (PPS) is found to be one of the most promising schemes, based on qualitative analysis and calculation. Detailed analyses of the truncation schemes are done in this work for Unit 1 boiler of Wangtan Power Plant (WPP) suffering all the aforementioned problems. Effects are thoroughly analyzed for 1 m, 2 m, and 3 m truncations of PPS at boiler operation loads of 600 MW, 450 MW, and 300 MW. Effects of different truncation schemes on the gas flow field in the boiler are also simulated at both cold and hot conditions. The 2 m PPS truncation scheme is found capable to solve the problems properly, and it is recommended for implementation. After retrofitted, the temperature of reheat steam has been increased to the designed value, the desuperheater spray has been reduced by an average of about 30 t/h, and steam temperature deviation at the furnace outlet has also been alleviated.