Effects of Using Hydrogen-Rich Syngas in Industrial Gas Turbines While Maintaining Fuel Flexibility on a Multistage Axial Compressor Design

Abstract

Current gas turbine technology for power generation is generally optimised for natural gas. Recently the use of Low Calorific Value (LCV) fuels gained interest, particularly, Hydrogen rich syngas resulting from coal and solid waste gasification. When LCV fuels are used the performance and behaviour of the engines could significantly change and modifications may be needed. For instance, due to the relatively low heating value of the syngas, higher fuel mass flow rate is required compared to the natural gas combustion case. This leads to a decrease of demand for air from the compressor, which results in increased back pressure, reduction of stall margin and possible compressor instability. In a previous work an exploration of some compressor geometry modifications to allow for high fuel flexibility was conducted on a single axial compressor rotor. The investigation provided insights into the effect of blade shape modifications, such as stagger, lean and sweep on rotor performance. With the same purpose of identifying trends rather than producing optimum design, in this study the analysis is extended to a multistage axial compressor. Two different investigations have been performed, both having, as objective, the shifting of the original mass flow rate towards a lower value while maintaining high performance. In the first study the effect of IGV and stator vanes stagger variations only was considered while in a second approach the re-design of the original machine included modifies to rotor’s stagger angles. In order to understand the change in each single blade performance when modifying the original geometry, the variation of critical parameters such as blade loading and diffusion factor has been here considered in first analysis.