| OCR Text |
Show elDI VICW' "w. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Fig. 4. Schematic diagram of the laboratory-scale furnace. Thermocouple positions are denoted by the T 1-T7 labels. pointer inside the entrainment chamber. The pointer was attached to a translation stage, and the pointer did not noticeably affect the flame behavior. Laboratory-Scale Furnace The performance of the DOC system was examined in the laboratory-scale furnace shown in Fig. 4. The cylindrical-shaped, cast refractory-lined furnace had an inner diameter of 914 nun (36.0 in) and an inner length of 3.20 m (126 in). Both furnace endcaps and the midsection pieces had a number of port openings giving access to the furnace interior to allow for variation in burner positioning, extraction of gas samples via water-cooled probes, insertion of water-cooled heat sinks, placement of suction pyrometers and, in general, the insertion of any burner device or diagnostic instrument. Water-cooled heat sinks having a diameter of 48.3 rom and a length of 1.52 m were often used to tailor the furnace wall temperature to the desired level. These heat sinks could be inserted through most of the ports in the furnace. Each of the seven furnace midsections was equipped with a thermocouple, the position of each being shown in Fig. 4. The average wall temperature, T W' of the laboratory-scale furnace was typically ascertained by averaging five thermocouple readings (Tl to T5 - see Fig. 4) along the length of the furnace. Lances were used to deliver the appropriate gases to the furnace. Each lance consisted of a water-cooled pipe with a removable nozzle and only one reactant was supplied through each lance. The nozzle diameters varied from 4.0 to 17 nun. The effects of burner arrangement, furnace temperature (Tw=1175 to 1550 K) fuma nitrogen content (0 to 77% vol. wet) and oxidant composition (pure oxygen or air) o~ pOl1u~et emissions were evaluated. When natural gas and o~ygen were used as reactants, nitrogen war: fed into the furnace through three ports along the SIde of the furnace to simulate nitrogen leakage or a partial oxy-fuel conversion. It is important to point out that as the nitrogen content of the furnace was varied from 0 to 77 % for a given DOC burner geometric/flow 7 |
