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Show uniformity, NOx emissions and physical survival under enrichment conditions. EXPERIMENTAL FACILITIES - The burner test facility (Figure 4) at Air Products is a refractorylined, water-cooled furnace. The burner fires from one end with the flue located at the opposite end. The furnace is rectangular in cross section and is capable of firing burners rated up to 20 KM BTU/hour. Temperatures in excess of 2500°F can be achieved independent of the burner firing rate. The furnace is equipped with access ports along the sidewall that permit use of various probes for gas sampling, as well as temperature and heat transfer determinations. The control room houses a computer that monitors air, oxygen, and fuel flow rates, furnace temperatures, gas temperatures, and flue gas composition. A number of safety interlocks prevent potentially unsafe operation. Both data collection and data reduction are computerized. Data Collection - Each burner was allowed to reach its own equilibrium furnace temperature under the conditions of interest. Air, oxygen, and natural gas flow rates and associated pressure drops were continuously monitored by the computer. The furnace temperature profile, and the flue gas temperature were continuously monitored by the computer. Flue gases were sampled and analyzed for CO, C02, NO, and excess 02. CO level in the flue was maintained at less than 100 ppm. Oxygen concentration in the enriched air stream was continuously monitored. Furnace atmosphere was sampled via a movable high-temperature probe through ports on the side of the furnace. The samples were analyzed for CO, C02, NO, and excess 02. A suction pyrometer was used to measure the flame temperature profile. Readings were taken at four predetermined insertion lengths through windows along the length of the furnace. A total heat flux meter was used to measure the rate of heat transfer. The burner internals and the burner block were examined for mechanical integrity after high enrichment level runs. Any deformation, melting, or burning was interpreted as mechanical failure. Thermocouple(s) were installed to monitor internal burner temperature. The maximum allowable internal temperature limit was set according to the materials of construction. The burners were tested with firing rates ranging from 1 KM BTU/hour to 3.75 KM BTU/hour, with enrichment levels ranging from O~ (air, 21~ 02 in the air stream) to 79~ (100~ 02 in the air stream). Pure oxygen was premixed with the appropriate amount of air to achieve the desired enrichment levels. Excess oxygen levels were minimized without exceeding 100 ppm CO level in the flue. The furnace pressure was controlled to minimize air infiltration. Burners - The test results for two burners are presented here to illustrate the effects of oxygen enrichment on their performance. Burner A was a natural gas burner rated at 4 KM BTU/hour with 1 psig air. It had a stationary metallic plate to generate swirl in the combustion air stream. The natural gas was fed through a number of small but straight holes at the center of the swirling air stream. The burner tile was cylindrical in shape with a length to diameter ratio less than 2. Burner B was a dual-fuel burner rated at 7 KM BTU/hour with 1 psig air. It had a stationary metallic plate in the air stream to feed the air in a diverging manner to the diverging burner tile. There was no provision to generate swirl. The natural gas was fed through an annular space around the oil atomizer at the center of the diverging air stream. The burner tile was divergent near the nozzle and cylindrical thereafter. The ratio of length to the diameter of the tile was less than one. RESULTS AND DISCUSSION FURNACE TEMPERATURE (Figure 5) - The reference furnace temperature was measured at the center of the roof. The variation of furnace temperature with increasing firing rate and increasing oxygen enrichment level is shown in Figure 5. The temperature increased significantly with firing rate and with enrichment level for both the burners tested. On air, both burners achieved approximately the same temperature at each firing rate tested. Burner B achieved higher furnace temperatures with oxygen enrichment when compared to Burner A. This result can be explained based on the fact that Burner A possessed higher drive and thus was able to maintain the flame direction better than Burner B. This explanation is further supported by the data on the uniformity of furnace temperatures in the vertical direction. FURNACE TEMPERATURE UNIFORMITY - The difference between the temperature at the center of the roof and that at the center of the hearth is shown in Figure 6. The difference is used as a measure of furnace temperature uniformity. The sidewall temperatures were symmetrical about the flame axis. The data show that the furnace temperature uniformity was better at higher firing rates and low oxygen enrichment levels. This appears to be a direct result of an increase in the combined volumetric |