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Show EFFECT OF OPERATING PARAMETERS ON N O X PRODUCTION IN A FLAT GLASS FURNACE 5_ portneck flow in the form of preheated air with the corresponding amount of nitrogen), 2) 10% of the furnace oxygen flow was introduced in the lance with a global furnace stoichiometry of 1 0 7% theoretical 02, and 3) 3 0 % of the total furnace oxygen flow was introduced in the lance with a global furnace stoichiometry of 1 1 9 % theoretical 02. The oxygen lance velocity was modified for each case so as to be approximately 50 m/s. This velocity was found to ensure adequate penetration into the furnace. This lance simulates, after a fashion, a staged combustion condition wherein oxidizer is delivered to the fuel stream over the length of the flame, resulting in possible lower flame temperatures and reduced residence time between oxygen and nitrogen. Oxygen/Fuel Combustion. This well-known technique for reducing NOx has been successfully applied to smaller scale (container glass, fiberglass, etc.) furnaces with dramatic reductions in N O x levels. Of course, the reduction depends in part on several factors: i) how well the furnace is sealed from infiltration of atmospheric air and the accompanying nitrogen, ii) the amount of nitrogen in the fuel, and Hi) the purity of the oxygen produced for the combustion (amount of residual nitrogen from the on-site generation of oxygen). Two different scenarios were investigated for oxy/fuel combustion: 1) firing with pure oxygen (as would be found with an on-site generation technique yielding ultra-pure 02) with 1 0 5 % theoretical 02, and 2) firing with a 9 0 % O 2/10%N2 mixture (as might be the result with an oxygen generation technique yielding less efficient 02/N2 separation) at 1 0 5 % theoretical 02. Infiltration of atmospheric nitrogen into the furnace was neglected in both simulations, but the 6.8% nitrogen in the fuel was included. A full-furnace simulation as shown schematically in Fig. 4 was performed for the study of oxy/fuel firing. Six simple burners were configured to fire in-line with identical burners on the opposite wall. In the simulations the symmetry of the furnace along its centerline was exploited. Fuel was introduced through a central port in each burner and the oxygen issued through a simulated annular port surrounding the fuel. Exhaust gases exited through a single exhaust port on each side of the furnace toward the working end. Oxy/Fuel Burners Figure 4. Schematic illustration of oxy/fuel tired full furnace simulated. |