Assessment of Site Parameters and Heat Recovery Characteristics on Combined Cycle Performance in an Equatorial Environment

Abstract

This paper investigates the effects of site based parameters such as ambient temperature, humid-ity, altitude and heat transfer characteristic of a dual pressure heat recovery system on the per-formance of the combined cycle power plant within an equatorial environment. The bulk heat uti-lization and configuration of a dual pressure heat recovery system are investigated. It is observed that the heat system configuration play a vital role in optimizing the combined cycle overall per-formance, which has proportionality relationship with the operating ambient temperature and relative humidity of the gas turbine. The investigation is carried out within the ambient tempera-ture range of 24˚C to 35˚C, relative humidity of 60% to 80%, and a high level steam pressure of 60 bar to 110 bar. The results show that at 24˚C ambient temperature, the heat recovery system has the highest duty of 239.4 MW, the optimum combined cycle power output of 205.52 MW, and over-all efficiency of 47.46%. It further indicates that as the ambient temperature increases at an average exhaust gas temperature of 530˚C and mass flow of 470 kg/s, the combined cycle power output and efficiency decrease by 15.5% and 13.7% respectively under the various considerations. This results from a drop in the air and exhaust mass flow as the values of the site parameters increase. The overall results indicate that decreasing the ambient temperature at optimum exhaust gas flow and temperature increases the heat recovery system heat duty performance, the steam generation, overall combined cycle power output and efficiency, which satisfies the research objective.