Alternative gas turbine architecture for pressure gain combustion combined cycles with steam-integrated turbine cooling

This paper investigates the theoretical benefits of the performance of Combined Cycle Gas Turbine (CCGT) using three advanced technologies: Pressure Gain Combustion (PGC), an alternative gas turbine architecture, and steam-integrated turbine blade cooling. The study evaluates the performance of next-generation combined-cycle plants employing PGC, a promising approach for improving gas turbine efficiency. It has been studied here with both a conventional gas turbine (GT) layout and an alternative layout that maximizes pressure gain by enabling stoichiometric combustion independent of turbine inlet temperature. Moreover, alongside conventional open-loop air cooling (OLAC), CCGT was investigated with three different turbine cooling approaches: (i) compressor bleed air cooling (CBAC), ii) Mixed loop steam cooling (MLSC) and iii) a combination of MLSC and CBAC (MLSC+CBAC). Furthermore, the PGC combustor was investigated under optimistic and realistic cases. Results showed that in the open cycle, the alternate GT layout provides higher efficiency than the conventional one, especially in the realistic PGC combustor (+2.3 p.p.) that included combustor inlet pressure loss of 20%. More importantly, in the combined cycle configuration, the new GT layout outperformed the conventional one in the realistic case. Among all the cooling strategies, MLSC+CBAC achieved the highest efficiency improvements with the Joule and PGC combustors. Finally, a combination of PGC technology, the alternative GT layout and an MLSC+CBAC cooling strategy was found to increase the efficiency of the current H-class combined cycles from 64.87% to 68.76% (+3.9 p.p.) with an ideal PGC combustor and to 67.95% (+3.1 p.p.) with a realistic PGC combustor. These high-efficiency gains from the simultaneous implementation of the three technologies provide a theoretical basis for developing next-generation CCGT plants capable of exceeding 68% efficiency.