Design of gas turbine axial compressors for fuel flexibility

Nucara, Pascal (2014) Design of gas turbine axial compressors for fuel flexibility. Doctoral thesis (PhD), University of Sussex.

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Current gas turbine technology for power generation is generally optimised for natural gas. On the basis of current instabilities in natural gas price and supply, the use of alternative fuels, such as syngas, has recently gained high interest. Due to the different thermodynamic properties of syngas compared to natural gas the behaviour of existing gas turbine components may significantly change. From practical and economic points of view, it is generally considered that in order to meet the new fuel properties, the main effort should be put on the adaptation of conventional gas turbines in integrated gasification combined cycle (IGCC) plants rather than producing a new generation of gas turbine designs from scratch. In addition to the requirement of new combustion technologies, main critical issues are represented by the reduction of compressor surge margin and turbine blade overheating. Solutions might include thermodynamic cycle as well as turbine geometry modifications. The latter would be preferred in terms of power plant performance. The main aim of this thesis is to explore suitable solutions to be applied to gas turbine compressors in order to accommodate syngas combustion. Among others, the use of variable stator vanes (VSVs) and blade radial stacking line modifications are considered. These are investigated on reference geometries available in the public domain. A baseline compressor geometry representative of a conventional heavy-duty gas turbine fueled with natural gas is generated and modified according to the understating gained during this study. The re-designed machine is a result of the application of stator vanes re-staggering in the front stages and blade sweep in the rear stages in order to cope with compressor air supply control and critical flow separation regions respectively. The obtained results show that efficient and stable operation during power modulation can be achieved, while reducing the need of other modifications to the combined cycle plant. It was therefore concluded that the proposed option can be considered a viable option to satisfy some important technical and economic constraints imposed by the integration of an existing gas turbine within an IGCC plant.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ0266 Turbines. Turbomachines (General)
T Technology > TJ Mechanical engineering and machinery > TJ0751 Miscellaneous motors and engines Including gas, gasoline, diesel engines
Depositing User: Library Cataloguing
Date Deposited: 05 Jun 2014 14:09
Last Modified: 21 Sep 2015 14:34

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