GT Inlet Air Boosting and Cooling Coupled with Cold Thermal Storage in Combined Cycle Power Plants

Investigation results of compressor inlet air boosting and cooling, applied to combined cycle power plants, are presented and discussed. Gas turbine performances may be reduced by site altitude and inlet losses due to air ducts and filters. Increasing inlet pressure by fans allows the restoring of gas turbine power output and efficiency at least to ISO reference conditions. Coupling such a system with inlet air cooling may completely suppress the temperature increase given by inlet air compression and the pressure losses through air coils as well; therefore, by this way, a further increase of electric energy production can be achieved. An in-house simulation code, developed for evaluating inlet air cooling system performance by cool thermal storage, has been adapted in order to also simulate off-design behaviour of boosting applied to combined cycle plants. A 127 MW reference power plant, operating in the Italian scenario, has been considered. Inlet pressure increase has been evaluated with and without inlet cooling, and in comparison with inlet cooling solution alone. Both thermodynamic and economical results have been analyzed. A parametric analysis on both system sizing parameters has been carried out. Best solution was found in coupling boosting to inlet cooling system through cool thermal storage; it produced an important increase in electric energy production. Location site influence on investment pay-back proved to be less important compared to the solution with inlet air cooling system alone.