Hydrogen Admixture Effects on Natural Gas-Oxygen Burner for Glass-melting: Flame Imaging, Temperature Profiles, Exhaust Gas Analysis, and False Air Impact

An experimental investigation is carried out to evaluate the effect of introducing hydrogen into natural gas flames on the combustion process (different temperature profiles, flame locations, and burning velocity) in glass melting furnaces. This work considers the fundamental changes in a non-premixed natural gas-oxygen flame (referred to as oxyfuel flame) with varying levels of hydrogen admixtures ranging from 0 to 100 vol%. To facilitate meaningful data comparisons, the burner power output is maintained at a constant thermal power of 20 kW during the entire series of tests. At first, the flow field of the oxyfuel burner is measured by using laser doppler anemometry (LDA). Then the burner is tested in a multi-segment combustion chamber with optical accesses. A camera system is employed to visually observe the combustion zone, capturing signals in both the visible (VIS) and ultraviolet (UV) wavelengths. The chemiluminescence of the OH* radicals could be determined over the entire flame length. Notably, the study reveals variations in flame position, especially with higher hydrogen concentrations. Furthermore, radial and axial flame temperature profiles are recorded at various po sitions. The analysis extends to major exhaust gas components (CO2, NOx, O2) at different fuel compositions and multiple equivalence ratios. In addition, a study is being carried out to investigate the influence of false air impacts. The obtained results indicate that the flame temperature increases slightly with pure hydrogen. The NOx values in the overall exhaust gas also show an increase with a higher hydrogen admixture. In particular, the influence of false air can lead to a significant rise in NOx levels.