Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames

Abstract

Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Program's aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation, the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter, nitrogen dilution, and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition, dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2, 4 and 8 atm. The NOx emission data from these experiments are discussed, as well as the results from onedimensional flame calculations