Development of technologies for improving the efficiency and reliability of operation of a combined-cycle gas-vapor TPP with a double-circuit waste heat boiler

Abstract

To increase the saving of a combined-cycle gas-vapor TPP, it was proposed to carry out intermediate superheating of the water vapour flow that has been exhausted in the high-pressure cylinder of a steam turbine in a double-circuit waste heat boiler. Mathematical algorithm and methodology of waste heat boiler are developed. Calculations were made for the steam-gas unit CCGT-450. It is shown that when an intermediate superheater is installed in a waste heat boiler, its efficiency coefficient increases by 2.15%. At the same time, the efficiency coefficient of the CСP for generating electricity increases by 3.36%, the degree of dryness of the steam exhausted in the turbine by 0.082Accordingly, the specific consumption of referense fuel for the generation of electrical energy is reduced by 6.1%. The calculation of the thermal scheme of CCGT-450 for two variants of operation was performed: without the implementation of intermediate overheating of water vapor and with the implementation of intermediate overheating of water vapor that has worked out in the high-pressure cylinder of the steam turbine. During the intermediate overheating of water vapor in the waste heat boiler, the main indicators of the CCGT increase: electric power by 28.96 MW, efficiency coefficient for generating electricity by 3.36% Respectively, the specific consumption of reference fuel for the generation of electrical energy is reduced by 6.1%. At the same time, the saving of reference fuel for CCGT-450 with its operating time of 4,500 hours per year and the cost of reference fuel of 3,700 rubles per ton of reference fuel. fuel in monetary terms is 118.72 million rubles per year.