Advanced Exergy Analysis and Performance Ranking of Components of a Combined Cycle Power Plant

Abstract

As conventional exergy analyses do not reveal the exergy destruction rates in a thermal system component caused by inefficiencies of interconnected components, actual potentials for improving the component performances cannot be provided by such analyses. This study analyses a combined-cycle gas turbine power plant using advanced exergy analysis methodologies, which address the shortcomings of conventional exergy analysis by evaluating the exergy destruction rates that are endogenous and exogenous, avoidable and unavoidable. Avoidable exergy destruction rates in the entire plant were found to be 31% of the total exergy destruction rates, indicating a significant potential for improving the plant. Exergy destruction rates for most of the plant components were largely endogenous (95.2%), signifying that contributions of cross-component interactions were limited. Avoidable endogenous exergy destruction rates account for 28.4% of the overall exergy destruction rates in the plant, while avoidable exogenous exergy destruction rates account for 2.1%. A component-level ranking of the plant components ranked the pumps in the plant as first for improvement whereas the highest priority was allocated to the combustion chambers (CC) by a plant-level ranking. A parametric study of the influence of CC operating conditions on the plant’s performance showed that CC operating temperatures more significantly affected plant exergy destruction rates than the CC operating pressures.