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Show a low enthalpy, DC, non-transferable arc plasma torch which was specifically designed for this project by Pegasus Refractory Materials (PERMA) in Montreal, Canada. The torch has a maximum electrical input of 50 KW. The arc is rotated magnetically to provide uniform heating of the gas passing through the torch. A secondary gas supply which does not pass through the arc can also be added to vary the temperature or composition of the pla~ma gas. The torch can be operated with plasma gas flows ranging from about 1 SCFM to 3 SCFM. Spectroscopic Equipment An nitrogen dye laser fluorescence system was utilized to perform radical species measurements in the exhaust of the plasma torch. A schematic of the system used is shown in figure 4. The dye in the laser can be changed to quantify various species in the gas stream. The emission spectra was first analyzed to determine the major species present in the plasma jet exhaust and then the laser fluorescence system was used to quantify the CH and ~ concentrations present for a range of operating conditions. Test Facility The exhaust of a 100 hp firetube boiler was modified to conduct the initial testing of the PYRONOx process. One objective of the modification was to provide an experimental facility that could produce a wide range of exit temperatures typical of a variety of industrial exhaust gas streams including, boilers, gas turbines and engines. Consequently an auxiliary gas burner was installed in the exit of the boiler to provide a method of simulating exhaust gases from engines and turbines. The initial NOx level in the exhaust gas can be varied from about 10 ppm to about 200 ppm by varying the airpreheat and FGR levels to the natural gas burner. NOx levels higher than 200 ppm can be obtained by doping the combustion air with NH3• Several methods of introducing the plasma gas into the flue gas were designed into the system in order to optimize the mixing between the hydrocarbon radicals and NOx• Provisions were also made for introducing swirl vanes into the flue gas flow to accelerate the mixing between the two gas steams. A schematic of the experimental facility is shown in figure 5. The firetube boiler facility is fully equipped with continuous gas analyzers for 02, CO2, CO, total hydrocarbons, NO, NOx and N20. HCN was also analyzed using wet chemical techniques and the soot concentration was measured using a EPA method 15 sampling train. THEORETICAL ANALYSIS One objective of the PYRONOx project was to develop a kinetic model capable of predicting data trends and useful for screening other gas mixtures for their effectiveness in reducing NOx emissions. Initial calculations were conducted using an existing version on the Chemkin kinetic model originally developed at Sandia to attempt to correlate the original experimental data acquired using the microwave plasma generator and a hydrocarbon/steam mixture as the plasma gas. Table 1 lists the 162 reversible reactions used in the initial modelling 6 |