Jet Shear Layer Turbulent Diffusion Flames for Ultralow NO_x Emissions

Direct fueling of each shear layer generated by an array of holes in a grid plate was shown to have ultralow NO_x emissions combined with a good flame stability, compared with a premixed system. Two methods of fuel injection were investigated that had opposite NO_x/stability characteristics. Four shear layers in a 76-mm combustor were used at gas turbine primary zone operating conditions with 60 percent simulated primary zone air at one bar pressure. The fuels used were propane and natural gas and a minimum NO_x emission of 2.5 ppm at 15 percent oxygen, compatible with a 0.1 percent inefficiency, was demonstrated for natural gas with a reasonable stability margin. These designs have the potential for a dry NO_x solution to any current or proposed gas turbine NO_x regulation for natural gas.