Performance Evaluation Of Combined Cycle Based On Reheat Gas Turbine

Ramtin Rakhsha1, Farshad Kowsari2, Kazem Sarabchi3


1 Advanced Dynamic & Control Systems Lab.(ADCSL), Faculty of Mechanical Engineering, University of Tehran, P.O.box: 11365/4563, Tehran, IRAN, E-mail: ramtin_rakhsha@yahoo.com
2 Associate Professor of Mechanical Engineering, Faculty of Mechanical Engineering, University of Tehran, P.O.box: 11365/4563, Tehran, IRAN, E-mail address: fkowsari@ut.ac.ir
3 Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran

ABSTRACT The fact that combined gas-steam power plants produce a significant amount of our electricity calls for increasingly detailed analysis of solutions that enhance plant performance and/or specific power levels. The role of the gas turbine in combined cycles has been considerably increased in the last two or three decades. As part of this effort, we have employed first law analysis of a one-pressure steam cycle, and various methods have been proposed in order to improve the performance of the gas turbine cycle. Specifically, in this research, performance of a reheat cycle (RC) was compared with that of a simple cycle (SC).Today, to achieve a higher efficiency and capacity in gas turbines, higher turbine inlet temperatures (1300 oC and beyond) are recommended. Application of such temperatures without turbine blade cooling is impossible. Therefore, modelling a gas turbine without considering the blade cooling will not lead to a valid result. The main objective of this paper is to study the performance of a reheat cycle (RC) under realistic conditions (with blade cooling) and investigate its effect on the efficiency in single pressure combined cycle. The results based on the proposed model show that reheating in gas turbine combined cycle within the context of realistic study, may lead to satisfactory results in efficiency.

 

KEYWORDS: Gas turbine; Combined cycle; Reheat; Cooling air;


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