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Show combustion of natural gas, LFG, and No.2 fuel oil, simulating combustion air preheat and the use of FGR. A broad range of design variables was examined, including LFG heating values, injection nozzle design, swirler design, burner register draft losses, and the use of FGR. The LFG heating value was simulated with the use of natural gas and nitrogen as a diluent. The absence of CO2 from the fuel blend certainly affected full simulation of LFG. Nevertheless, the results obtained were sufficiently encouraging to proceed with the commercial installation of the developed burner in operating utility boilen. The proof of design in full-scale prototype testing proved to be invaluable in essentially eliminating operational problems during start-up and optimization of the commercial systems. 4.0 SYSTEM DESCRIPTIONS 4.1 AUS-5000 LFG Burner A schematic of the single register AUS-5000 LFG low NOx burner is shown in Figure 3. Both the prototype and commercial burner have essentially similar key features which consist primarily of a set of multi-fuel dispensers, an air slide, a Venturi register, and a gas ignitor. Table 3 summarizes the design characteristics of the AUS-5000 LFG low NOx burner. LFG is supplied to the furnace through six pokers arranged around the periphery of the primary swider. In addition, natural gas is introduced through an . annular gas gun while the oil gun is fitted down the center of the gas gun. When oil is fired, the natural gas gun is retracted allowing the oil atomizer to be exposed. When the air slide is opened, the combustion air flows through the annular air intake and the Venturi register. A Class 1 natural gas ignitor is provided for main burner ignition and boiler warm-up. -11- |