Economic assessment of the use of double-acting resuperheating of water vapor at the PGU-420 Cherepovets state district power station

Abstract

To increase the efficiency of a three-circuit combined-cycle plant, it is proposed to perform double resuperheating of water vapor in the high pressure loop (intermediate superheater ISH-1) and in the cooler part of the heat recovery boiler (intermediate superheater ISH-2). It was found by calculation that the implementation of the double reheated steam at high pressure and the tail of the WHRB increases the electrical efficiency of PGU-420 by 0.92 % compared to the option of a single resuperheat (from 60.45 to 61.37 %). The capacity of PGU-420 increases by 3.7 % (from 422.94 to 438.61 MWt). The specific reference fuel consumption is reduced by 1.5 % (from 203.47 to 200.42 g/(kWfh)). The steam dryness factor increases by 6.03 % (from 93.2 to 99.23 %). The steam turbine efficiency increases by 1.15 % (from 36.26 to 37.41 %), and steam turbine power increases by 11.61 % (from 134.94 to 150.61 MWt). The economic effect of the implementation of the second water vapor resuperheating in monetary terms is 48.0 million rubles per year when the cost of fuel equivalent is 3700 rubles/t. f e. and at the operating time of 7500 h/year.