COMPARISON OF GAS TURBINE POWER CYCLES PERFORMANCE USING AIR/STEAM BLADE COOLING

Two recuperated gas turbine power cycles with entailed heat recovery steam generator, namely Steam Injected Recuperated Air/Steam Cooled GT Cycle (SIRASC) and Intercooled Recuperative Steam Cooled GT Cycle with Water Recovery (IRSC-WRGT) were proposed and studie d. The adoption of open loop steam blade cooling and humidified air, obtained by mixing the produced steam and air bled from the compressor, have been analysed and discussed. The effects of different coolants properties on blade cooling effectiveness were considered and included in all the adopted thermodynamic models. The possibility of partial injection of the produced steam in combustion chamber combined with steam and air/steam blade cooling were considered and discussed for the SIRASC. The IRSC-WRGT configuration is a modification of SIRASC, with the addiction of a condensing heat exchanger on the exhausts line to recover the related water content and use it for blade cooling. Differently from the first one, this does not need any external addiction of water. The best performing configurations are those with pure steam blade cooling, even if rather interesting values of efficiency have been obtained with highly humidified air as blade cooling media. Finally, the exergy analysis of the two proposed power cycles evidenced the better features of the IRSCWRGT, mainly due to the lower stack and HRSG exergy destruction and to the higher applicable recuperation degree.