Efficiency of a combined gas-steam process

Abstract

The equations for the determination of the overall energy and exergy efficiency of a combined gas-steam cycle process are determined and discussed. The cogeneration in the gas and in the steam cycle, the reduction of power due to increasing the heat flow in the steam process, the supplementary firing at the gas turbine exhaust, the heat recovery boiler efficiency as well as the heat exchanger efficiency in the gas and steam cycle were taken into consideration. The presentation of the results is based on the thermodynamic derivation, the calculations of a typical example, and graphic diagrams.