Emissions from buoyancy dominated gas and gas/oil turbulent-jet diffusion flames

Emissions of NOx, N2O, CO and unburnt hydrocarbons (UHC) from free turbulent gas and gas/oil jet diffusion flames are reported. Various gaseous fuels have been studied including methane, propane, n-butane and mixtures of pure gases, such as methane-propane mixtures. In addition to varying the gaseous fuel composition, atomized oil droplets have been injected into propane flames to study the effect of condensed phases. Measurements of NOx, N2O, CO and UHC have been performed in small vertical laboratory hydrocarbon flames (<0.7 MW) and medium size propane jet diffusion flames (<9 MW) with nozzle exit Reynolds and Froude numbers ranging from 7025 to 908000 and 18 to 417000, respectively. This has been achieved by varying the exit gas velocity between 3.0 and 247.3 m/s, and the exit nozzle diameter between 5 and 50 mm. Both axial and radial emission profiles have been measured above the visible flame region. The measuring equipment includes continuous gas analysers and water cooled quartz/stainless steel suction probes. Emission indices of the various compounds are found and reported. A recently developed scaling law for the global NOx-emission index as function of the Froude number for propane and methane flames is tested and discussed. The new results compare well with the scaling law which shows that the NOx-emission index is strongly dependent upon the Froude number. These formulas can be employed for engineering purposes and provide guidance for calculating NOx-emissions from turbulent hydrocarbon gas and gas/oil jet diffusion flames. In addition to NOx, emission indices for N2O, CO and UHC are reported. No scaling effect is observed for these emissions. 17 refs., 6 figs., 4 tabs