OCR Text |
Show The burner used in this investigation was assembled in a double concentric arrangement capable of accepting a wide range of commercial oil nozzles. The unheated combustion air was supplied through an annular duct (inner diameter 5 cm, outer diameter 13 cm). The axial air velocity was 31 m/sec (100 ft/sec) and swirl was generated with interchangeable fixed vane swirlers. The burner exit was a refractory cone 20 cm in length and with 45 degree half angle. The oil gun was precisely positioned to locate all the atomizers at the throat of the divergent and the combustion air supply was designed to give a uniform air distribution across the throat. A steam/auxiliary electric heating system was used to maintain the oil temperature (measured by a thermocouple) at the nozzle constant. In these investigations the staged air was injected through a water-cooled axial boom inserted through the rear of the combustion chamber. The distance of the air injector from the fuel atomizer (size of first stage) was varied between 25 and 260 cm. Analytical System The same sampling and analysis system was used for both the boiler simulator and the tunnel furnace. It allowed for continuous monitoring of NO, NO , CO, CO2, 02> and S02 using commercially available instruments. Flue gas was withdrawn from the appropriate stack through a water-cooled, stainless steel probe. Sample conditioning prior to the instrumentation consisted of an ice-bath water condenser, glass-wool filters, and a stainless/ Teflon sampling pump. All sample lines were 6.3 mm Teflon tubing and all fittings 316 stainless steel. Fuels Figure 2 illustrates the range of properties of petroleum and alternative liquid fuels investigated to date. This information was generated by an independent testing laboratory. The petroleum-derived fuels had sulfur contents ranging from 0.2 to 2.22 percent with a minimum nitrogen content of 0.86. The nitrogen content of the alternative fuels range from 0.24 to 2.5 percent. 7-7 |