Energy and Exergy Analyses of a Combined Power Plant Based on Natural Gas Combustion

Abstract

The present study implemented energy and exergy analyses on a 750MW combined cycle power plant (CCPP). The research utilized a simulation process using a computer model developed in MATLAB. The model was based on the natural gas combustion concept, energy balances, enthalpy balances, entropy changes, and the CCPPs heat transfer. The model was validated with the case study of the CCPP at Tuanku Ja’afar Power Station, Port Dickson. The results showed that the CCPP’s energy and exergy efficiencies were 56% and 51%, respectively. Furthermore, applying exergy analysis revealed that the combustion chamber had a significant source of exergy destruction rate, i.e., 224.58 MW, which corresponded to 67.48% of the total exergy destruction in the CCPP, followed by the air compressor 7.53%, and the steam turbine 7.07%. Meanwhile, increasing the turbine inlet temperature (TIT) reduced the exergy destruction rate of the combustion chamber of the gas turbine cycle. The optimum performance obtained at TIT was higher than 1262 °C, where the exergy destruction decreased in the CCPP. Moreover, In CCPP, the combustion chamber was the highest exergy destruction rate, i.e., 225MW, among the main components of the power system. It can be grasped that the current adaptive model of natural gas combustion is a powerful tool for predicting the overall performance of the CCPPs based on exergy analysis.