Sensitivity analysis for the capacity improvement of a combined cycle power plant (100–600 MW)

Power improvement of a combined cycle power plant using inlet air cooling was analyzed in this paper. The corresponding CC capacities in a range of 100–600 MW were examined. The CC performance can be improved by decreasing an inlet air temperature and humidity to 15 °C (ISO) and 100% RH before entering air compressor of a gas turbine (GT). All year ambient temperature in Bangkok is normally higher than 15 °C. This research used a steam absorption chiller (AC) to cool intake air to the desired temperature level and no storage unit was needed. The CC uses a cooling tower (CT) for cooling purpose. In the 400 MW power plant as an example, it could increase the power output of the GT by 9.32% and the CC by 5.8%, while the ST power decreased by 3.42% annually, as some steam was supplied to the AC. In the economical analysis, the payback period (PB) will be in the range of 0.68–0.94 years, internal rate of return (IRR) 29–176%, and net present value (NPV) 116.5–154.63 MUS$. Additionally, sensitivity analysis concerning economic performance and environmental impact of the plants were also studied.