Session: 06-02 Pressure Gain Combustion

Paper Number: 153615

Efficiency Enhancement in Pressure Gain Combustion Combined Cycle Gas Turbine by Blade Cooling Integration With Bottoming Cycle 

This paper investigates the potential advantages of integrating turbine blade cooling with bottoming cycle in Combined Cycle Gas Turbine (CCGT) with Pressure Gain Combustion (PGC) for land-based power generation application. PGCs have recently emerged as a promising solution to achieve significant performance gains in current Gas Turbines (GT) and CCGTs, in terms of efficiency and power output. However, GTs with PGC combustors require higher cooling flow compared to conventional GTs, due to the increased temperature of cooling flow from its secondary compression that is necessary for admission in the turbine. The present work aims to address this issue by utilizing the working fluid from the steam cycle for cooling stator and rotor vanes. PGC is represented by a steady-state zero-dimensional constant volume combustion (CVC) model based on the Humphrey cycle. The PGC combustor model also includes practical losses such as inlet pressure loss, degree of isobaric combustion and internal expansion efficiency for a realistic performance. Three different approaches of turbine blade cooling through the bottoming cycle are investigated in this work; (i) cooling of compressor bleed air ii) open-loop steam cooling for stator and vanes and iii) closed-loop steam cooling for stator and vanes. A heavy-duty practical H-class CCGT with a PGC combustor and a three-pressure level heat recovery steam generator (HRSG) is modelled in WTEMP (Web-based Thermo-Economic Modular Program) software, an original modular cycle analysis tool developed at the University of Genova. Thermodynamic analysis of the CCGT cycle was performed with realistic component efficiencies at a wide range of operating conditions, with hydrogen as the fuel. The impact of different cooling approaches on the cycle performance was analysed in terms of efficiency and specific work. Results showed using water or steam from the bottoming cycle can reduce the cooling flow requirement in PGC-based CCGT and the associated cooling penalty thereby increasing the efficiency of the cycle slightly by upto 2 percentage points. Finally, practical challenges in integrating blade cooling with bottoming cycles are discussed and the most promising solution is suggested.

Presenting Author: Abhishek Dubey University of Genova

Presenting Author Biography: Abhishek is an aerospace engineer from India. He obtained a Master's in aerospace propulsion from the Indian Institute of Technology Kanpur, India, in 2018 and subsequently worked at the Indian Institute of Science (IISc) Bangalore for three years before joining the INSPIRE program at the University of Genoa in January 2022. He has over five years of research experience in the field of gas turbine combustion, emission reduction technologies, laser diagnostics and the design of high-pressure optically accessible test rigs. He is passionate about developing more efficient and clean gas turbine technologies for propulsion and power generation.

Authors:

Abhishek Dubey University of Genova
Alessandro Sorce University of Genova
Massardo Aristide Fausto University of Genova