Laboratory Study of Premixed H2-Air and H2-N2-Air Flames in a Low-Swirl Injector for Ultra-Low Emissions Gas Turbines
The objective of this study is to conduct laboratory experiments on low-swirl injectors (LSIs) to obtain the basic information for adapting LSI to burn H2 and diluted H2 fuels that will be utilized in the gas turbines of the integrated gasification combined cycle coal power plants. The LSI is a novel ultralow emission dry-low NOx combustion method that has been developed for gas turbines operating on natural gas. It is being developed for fuel-flexible turbines burning a variety of hydrocarbon fuels, biomass gases, and refinery gases. The adaptation of the LSI to accept H2 flames is guided by an analytical expression derived from the flow field characteristics and the turbulent flame speed correlation. The evaluation of the operating regimes of nine LSI configurations for H2 shows an optimum swirl number of 0.51, which is slightly lower than the swirl number of 0.54 for the hydrocarbon LSI. Using particle image velocimetry (PIV), the flow fields of 32 premixed H2-air and H2–N2-air flames were measured. The turbulent flame speeds deduced from PIV show a linear correlation with turbulence intensity. The correlation constant for H2 is 3.1 and is higher than the 2.14 value for hydrocarbons. The analysis of velocity profiles confirms that the near field flow features of the H2 flames are self-similar. These results demonstrate that the basic LSI mechanism is not affected by the differences in the properties of H2 and hydrocarbon flames and support the feasibility of the LSI concept for hydrogen fueled gas turbines.