Exergy Analysis of Hot-Windbox Repowering Option For A Coal-Fired Thermal Power Plant

This study investigates the exergetic effects of the hot-windbox repowering option for a coal-fired thermal power plant. The hot-windbox repowering option consists of a gas turbine, an air-to-water heat exchanger for feedwater heating, and an air-to-air heat exchanger to preheat the combustion air. An air dilution part is also needed for the required temperature set at the inlet of burners. A burner modification can also be necessary without air dilution dampers. Exergy calculations for the power plant before repowering were performed according to the design data of Soma-A Thermal Power Plant and were repeated for the hot-windbox repowering (HWB) scheme. According to the results, the percent exergy destruction in the boiler decreased from 84.70% to 68.80%, which that in the combustion chamber of the gas turbine (GT) was 14.77%. Total exergy destruction increased from 56.65 MW to 69.33 MW, whereas the total exergy destruction per installed capacity decreased from 2.39 MW/MWel to 2.06 MW/MWel, and exergetic efficiency of the power plant increased from 29.13% to 34.70% after hot windbox repowering.