Retrofitting a Steam Power Cycle by Using Water From the Interstage Feed Water Pump as Reheat Spray

Various methods are used in thermal power plants to adjust the superheated or reheated steam temperature to a pre-determined set point, including flue gas recirculation, using tilting burners and spray of water from discharge of feed water pump, etc. In this paper, an innovative method is presented to control the reheater temperature by tapping water from an interstage of the feed water pump to control reheater temperature at the Bisotoun Power Plant (a steam cycle based power plant in the western Iran). The spray water for the superheaters is secured from the discharge of feed water pump, but interstage water, instead of gas recirculation or using tilting burner, is used to control the reheater temperature. The total cycle is simulated with this arrangement and the results are compared with power plant actual data. Here, the variation of pump head and its power consumption is investigated as well. The tapped water requirement is calculated in terms of controlling reheat steam temperature at different loads.