Performance comparison of SOFC integrated combined power systems with three different bottoming steam turbine cycles

Abstract

In this article, a thermodynamic model is developed for analyzing the energetic and exergetic performance of a solid oxide fuel cell (SOFC) integrated combined power system with triple pressure reheat cycle in the bottoming steam turbine (ST) plant. A temperature difference range of 15–20°C is considered between flue gas and steam at superheater inlet in the high and intermediate pressure stages of the heat recovery steam generator (HRSG). Also, a temperature difference of 20°C is maintained at the pinch point between flue gas and saturated water in the low pressure stage of the HRSG. Detail performance variation is provided as a function of compressor pressure ratio (CPR) showing that the system’s power and efficiency increase while total irreversibility decreases at higher CPR. Further, thermodynamic modeling is done for two other systems with dual pressure reheat and single pressure ST cycles for performance comparison amongst all, under identical conditions. The comparative study shows that the system with single pressure ST cycle performs better compared to the others; the highest power is obtained from this system with minimum total irreversibility. It is recommended that the system with single pressure ST cycle would be the most appropriate as it is simple with less number of components and minimum total cost.