Multi Objective Optimization of Feedwater Heating Repowering on a Steam Power Plant Using the Genetic Algorithm

Repowering as a tested and general method can be effective for repowering steam power plants. There are different repowering methods to choose from based on a plant‟s specifications. Repowering has been categorized into two main categories: Full repowering and partial repowering. Feedwater heating is one of the best options available for partial repowering. In the feedwater heating based on partial repowering which has been studied in this paper, two heat exchangers have been used in parallel to the existing feedwater heaters and the required heat is supplied by an appropriate gas turbine. Two options have been considered for the added gas turbine. In the first option, a 25 MW gas turbine has been considered while in the other scenario, the considered gas turbine power output has been optimized as a dependent variable. The final result using a 25MW gas turbine is a 1.55% increase in exergy efficiency and an electricity generation cost of 404.15 Rial/kWh. In the other scenario (dependent gas turbine), exergy efficiency is increased by 1.73% and electricity generation cost is 396.22 Rial/kWh.