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BURNER CRITERIA FOR NOX CONTROL. VOLUME I. INFLUENCE OF BURNER VARIABLES ON NOX IN PULVERIZED COAL FLAMES
Citation:
Heap, M., T. Lowes, R. Walmsley, H. Bartelds, AND P. LeVaguerese. BURNER CRITERIA FOR NOX CONTROL. VOLUME I. INFLUENCE OF BURNER VARIABLES ON NOX IN PULVERIZED COAL FLAMES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-76/061a.
Description:
The report gives results of the first phase of an investigation to specify burner design criteria to control NOx in natural gas and pulverized coal flames. The two parameters found to have major influence on NO formation were the method of fuel injection and the degree of swirl. NO formation can be controlled by optimizing burner design parameters because its rate of formation depends on the detailed mixing history of the fuel, combustion air, and recirculating combustion products. The same parameters also dictate such flame characteristics as stability, length, and luminosity. An explanation of the influence of burner parameters on pulverized coal flames is based on two assumptions: the most significant factor of the total emission is fuel NO, and the emission variation depends on the fate of the volatile nitrogen compounds. Fuel NO formation can be reduced by ensuring that the volatile nitrogen compounds react under oxygen deficient conditions. Maximum emissions occur with radial fuel injects because the coal is rapidly mixed with the total air supply and hot recirculating products. These conditions ensure early stable ignition. However, fuel/air mixing promotes NO formation. Conversely, NO formation can be restricted by maintaining the fuel in a coherent axial jet and discouraging primary/secondary mixing by surrounding the fuel jet with an ignition front. The coal must also be delivered with the minimum amount of primary air.