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Show Dilution Air -0> - ) • Combustion Air Gaseous Fuel Liquid Fuel Gaseous Fuel Atomization (Swirl Nozzle) Gas ,njection Holes Figure 2: Dual-Fuel EV Burner obtained shortly after injection and, by appropriately distributing the holes along the inlet slots, the fuel concentration profile in the burner exit plane can be controlled. A vortex breakdown zone stabilizes the flame in free space. Therefore, there is no flame holder hardware exposed to the ignition mixtures. In this way, the fuel and combustion air is premixed within the cone prior to ignition. The onset of the recirculation zone acts as a flame holder by recirculating hot flue gas to the ignition point. In contrast to other, more conventional premix burner designs, no diffusion or pilot stage is required to improve the stability of the premixed flame. The absence of fuel upstream of the burner gives exceptional reliability because it eliminates the possibility of flashback. Within the burner itself, high axial velocities are produced which prevent the flame from propagating upstream. Since the ignition zone is significantly displaced from the burner walls, the heat transfer to the burner section is also rrdnirnized. In the burner cone head (opposite end from the exit plane), there is space for an oil gun for light oil firing capability. The cones can be either cast alloy or fabricated from steel plate. BURNER TEST PROGRAM The purpose of the E V and L N V ™ burner test program was to characterize the natural gas-firing performance and emissions of a premixed burner and diffusion burner. The L N V ™ burner test program also characterized No. 2 fuel oil. Experiments were carried out at ABB Power Plant Laboratories' Industrial Scale Burner Facility (ISBF) to evaluate the effects of burner input parameters on N O x emission levels. The variables tested included: 5 IV-24 |
