Thermodynamic Study of Influence of Steam Injection in Combustion Chamber of Simple Gas/Steam Combined Cycle

Abstract

Steam injection is seen as one of the popular ways for power augmentation by number of turbine manufacturers and number of steam injected turbines such as Allison 501-K, GE LM 2500, and LM5000 are already in use. This paper presents the thermodynamic study of influence of steam injection in combustion chamber of topping cycle in a simple gas / steam combined cycle power plants upon the efficiency and specific work out put of topping cycle, bottoming cycle and combined cycle. The simple gas / steam combined cycle power plant configuration considered for the study has topping cycle gas turbine with film cooled stages employing air / steam as coolants and single pressure steam generation in the heat recovery steam generator (HRSG). Air for cooling has been bled out from compressor depending upon the requirement and the steam requirement as coolant is met from the steam generated in heat recovery steam generator (HRSG). Thermodynamic analysis of the simple combined cycle configuration considered has been completed with the variation in various parameters such as cycle pressure ratio, type of coolant used for gas turbine stages, mass fraction of the steam being injected in combustion chamber of topping cycle. Results obtained have been plotted suitably for the critical evaluation of influence of one parameter upon the other.