Exergo-economic study of a dual-pressure HRSG in gas/steam combined cycle plants

Combined power plants are among the most attractive options to optimally utilise conventional fuel energy with respect to energy conversion and the environment. In the present study, a dual-pressure heat recovery steam generator (HRSG) used in a gas/steam combined cycle power plant is investigated. This paper presents exergy and economic analysis of a dual-pressure HRSG. The parameters used for the investigation of the exergo-economic study are pinch point, fuel price, cost of exergy losses, gas turbine inlet temperature and cycle pressure ratio. A parametric study shows that the considered parameters have a huge impact on the total annual cost per unit exergy of steam produced in the HRSG. It is seen that best exergo-economic conditions are obtained at the pinch point value of 10 K to get the total annual cost per unit exergy of steam produced to be the minimum.