Aligning Combined Cycle Power Plant Performance with Field Measurements

Abstract

This paper studied a system of two gas turbine engines with inlet guide vanes followed by a steam turbine. The steam turbine recovers energy from the exhaust gas of the gas turbine engines through heat recovery steam generators. An actual combined cycle is modeled; this system model takes into consideration the variation of specific heats of air and combustion gases, the polytropic efficiencies of gas turbines and compressors, and the isentropic efficiencies of the steam turbine and pumps. Moreover, pressure drops were taken into consideration for all different heat exchangers. Model performance predictions were then aligned with the field measurements of a Jordanian combined cycle power plant. This paper presents the comparison between the model predictions and actual performance, specifically for power output and fuel consumption. The relative error between the theoretical and actual output power from the plant is approximately 8%. Ambient air temperature has a major effect on the plant-produced power and fuel consumption. Under desert conditions between summer and winter, when the ambient temperature drops from 46 to 1 $$^\circ $$ C, an extra 47.2 MW could be generated, with the corresponding increase in efficiency of approximately 6.5%, while SFC decreases by 1.1%.