ENERGY AND EXERGY PERFORMANCE ASSESSMENT OF A 660 MW SUPERCRITICAL COAL-FIRED POWER PLANT UNDER DESIGNED AND OPERATIONAL CONDITIONS: A CASE STUDY OF JAMSHORO, PAKISTAN

Abstract

The increasing demand for electricity, coupled with concerns regarding fuel efficiency and environmental sustainability, has intensified the need for improving the performance of thermal power plants. Supercritical coal-fired power plants operate at higher steam pressures and temperatures than conventional subcritical units, resulting in enhanced thermal efficiency and reduced fuel consumption. However, discrepancies between designed and actual operating conditions often lead to performance deterioration that cannot be adequately evaluated using conventional energy analysis alone. Therefore, this study aimed to assess the thermodynamic performance of a 660 MW supercritical coal-fired power plant at Jamshoro, Pakistan, using integrated energy and exergy analyses under both designed and operational conditions.

A comprehensive thermodynamic model of the supercritical Rankine cycle was developed using Engineering Equation Solver (EES). Energy and exergy balance equations were applied to all major plant components, including the boiler, turbines, condenser, feedwater heaters, pumps, and generator. Component-wise performance, overall plant efficiency, exergy destruction, and the influence of operating parameters were evaluated. Model validation was performed through comparison with published literature on similar supercritical power plants.

Under designed conditions, the plant achieved a thermal efficiency of 41.55% and an overall exergy efficiency of 38.21%, whereas operational conditions reduced these values to 38.72% and 35.14%, respectively. Gross power output decreased from 660 MW to 635 MW, while net power output declined from 642 MW to 615 MW. Boiler heat input increased from 1545 MW to 1588 MW, accompanied by a 7.34% increase in heat rate and a 9.49% increase in total exergy destruction. The boiler was identified as the largest contributor to thermodynamic irreversibilities, followed by the turbine stages and condenser. Comparison with previous studies demonstrated that the designed performance of the Jamshoro supercritical unit exceeded that of conventional subcritical plants while remaining comparable with international supercritical facilities.

The findings demonstrate that exergy analysis provides a more comprehensive assessment of plant performance than conventional energy analysis by identifying the magnitude and location of thermodynamic irreversibilities. The developed EES model offers a reliable framework for performance evaluation, operational optimization, and efficiency improvement of large-scale thermal power plants. Implementation of optimized steam conditions, improved combustion control, enhanced condenser performance, and periodic exergy-based performance monitoring could substantially reduce fuel consumption, improve plant efficiency, and support sustainable thermal power generation in Pakistan.