Applying Combined Pinch and Exergy Analysis to Closed-Cycle Gas Turbine System Design

Abstract

Pinch technology has developed into a powerful tool for thermodynamic analysis of chemical processes and associated utilities, resulting in significant energy savings. Conventional pinch analysis identifies the most economical energy consumption in terms of heat loads and provides practical design guidelines to achieve this. However, in analyzing systems involving heat and power, for example, steam and gas turbines, etc., pure heat load analysis is insufficient. Exergy analysis, on the other hand, provides a tool for heat and power analysis, although at times it does not provide clear practical design guidelines. An appropriate combination of pinch and exergy analysis can provide practical methodology for the analysis of heat and power systems. The methodology has been successfully applied to refrigeration systems. This paper introduces the application of a combined pinch and exergy approach to commercial power plants with a demonstration example of a closed-cycle gas turbine (CCGT) system. Efficiency improvement of about 0.82 percent (50.2 to 51.02 percent) can be obtained by application of the new approach. More importantly, the approach can be used as an analysis and screening tool for the various design improvements and is generally applicable to any commercial power generation facility.