Combined pinch and exergy analysis for energy efficiency optimization in a steam power plant

Abstract

In this paper, the simulation of a 325 MW steam power plant was performed in a Cycle-Tempo 5.0 simulator and operational parameters of the Rankine cycle were optimized using the Exergy concept combined with a Pinch-based approach. The Combined Pinch and Exergy Analysis (CPEA) first considers the representation of the hot and cold Composite Curves of the Rankine cycle and defines the energy and Exergy requirements. The basic assumption of the minimum approach temperature difference (DTmin) required for the Pinch Analysis is represented as a distinct Exergy loss that increases the fuel requirement for power generation. The exergy composite curves put the focus on the opportunities for fuel conservation in the cycle. The application results of CPEA in the power plant showed that its fuel consumption could be reduced by 5.3% and the thermal cycle performance could be increased from 39.4 to 41.9%. In addition, the production drop problem in current power plants, due to the inefficiency of the cooling system, especially in warm seasons, could be eliminated, thanks to an 18.77 MW reduction in the cooling load of the condenser. Key words: Rankine cycle, composite curves, exergy loss, fuel conservation, cooling system, condenser.