Evaluation of different alternatives of power augmentation for an existing combined cycle power plant in Brazil

Not only in simple cycle power plants, but also in combined cycle power plants based on gas turbines, the power output is considerably reduced with the increase of the ambient temperature. Many technologies for power augmentation of gas turbines have been proposed along the last decades, and several systems have already been applied in real plants. Power augmentation techniques are concentrated on the philosophy of increasing the mass now rate going through the gas turbine. The goal of this paper is to review the state-of-the-art of the different technologies of power augmentation available today for gas turbines, as well as to evaluate and to select the best alternative of power augmentation for an existing combined cycle power plant in Brazil. The calculations are carried out using an in-house computer program, called the Power Augmentation Technologies (PAT) model, developed for thermal performance modeling and financial analysis. In order to validate the computational model developed, the authors carried out comparisons between the results obtained with this model and data obtained from literature. For the specific combined cycle power plant analyzed in this work, and considering the internal rate of return and the pay-back period as the main investment economic indicators determining the implementation of a project developed for increasing the plant power output, the results show that the power augmentation systems based on evaporative coolers are the most suitable for this plant.