OCR Text |
Show from the fuel; (2) the inevitable distribution of stoichiometrics from fuel-rich to fuel-lean which occur because the primary zone is supplied by a diffusion flame; and (3) the overall temperature of the primary zone. From equilibrium considerations the total fixed nitrogen (TFN given by NO + HCN + NH3) is a minimum at approximately 65 percent theoretical air with levels less than 10 ppm depending upon temperature and fuel C/H ratio Exhaust NO emissions are considerably greater than levels predicted by equilibrium, suggesting the existence of kinetic limitations in the fuel-rich primary stage. The results presented in this paper are part of a study to investigate the influence of spray properties, fuel composition, stoichiometry and thermal environment on pollutant formation in liquid fuel flames. The technical approach was experimental involving parallel programs in two combustors of different scales: - a downfired 20 kW (70,000 Btu/hr) tunnel furnace, and - a 900 kw (3,000,000 Btu/hr) cold wall axisymmetric combustor which simulates the firetube of a package boiler. The downfired tunnel furnace allowed experiments to be economically carried out on the fate of fuel-bound nitrogen during liquid fuel combustion as a function of fuel properties and combustion conditions. Comparison with the performance in the package boiler allows generalization of these results to a wider range of combustor types. 7-4 |