Optimization and analysis of exergy, economic, and environmental of a combined cycle power plant

In this study, a combined cycle power plant with a nominal capacity of 500 MW, including two gas turbine units and one steam turbine unit, is considered by a mathematical model. This study is carried out to optimize three objective functions of exergy efficiency, CO2 emission and produced power costs. This multi-objective optimization has been carried out by using the Non-Dominated Sorting Genetic Algorithm (NSGA-II). The results indicate that the efficiency of the combined cycle power plant depends on the design parameters including gas turbine input temperature, compressor pressure ratio, and pinch point temperature. Furthermore, any change occurring in these settings may lead to noticeable changes in objective functions, so that the efficiency of this power plant is increased after optimization by up to 8.12 %, and its heat rate is correspondingly reduced from 7233 (kJ/kWh) to 7023 (kJ/kWh). Similarly, exergy destruction in the total system shows a reduction by 7.23%.