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Show MMBtuJhr conventional burners to staged burners. The staged burners produced a flame length that measured 38% longer than that of the conventional design (Fig. 5). The flame envelope was non-lofting with low momentum. Required combustion oxygen pressure was reduced by 50% compared to the original OXY -THERM design. A dramatic increase in flame luminosity, although not yet measured quantitatively, was noted and confirmed by photography. With regard to the other development goals, various atomizing mediums were tested and proven as acceptable alternatives to oxygen atomization. NOx testing using the various atomizing mediums provided expected results (Fig. 6). Atomizing with air increased NOx emissions by 10% compared to oxygen atomizing. This was not viewed as a problem, however, due to the OXY-THERM LE's 50% to 60% reduction in NOx over conventional oxy-fuel firing (noted above). Steam atomization reduced NOx emissions by almost 40% compared to oxygen atomizing. Unfortunately, atomizing with steam caused a reduction in flame length of approximately 15% to 20%. Due to the low volumetric consumption of the OXY -THERM atomizer, further testing using natural gas and propane for atomizing is planned. Oxy-Fuel Burner Comparison Test Due to the proprietary nature of the oxy-fuel burner comparison tests and the subsequent conversion of two production melters, Maxon has agreed not to publish the name of the company involved or specific comparative results, or use either in advertising. Laboratory results, while useful in relative terms, still reflect best case scenarios. With that in mind, a search for a field trial site for the staged oxygen burner, now named OXY-THERM LE, began in July 1993. At about the same time, oxy-fuel burner suppliers received an invitation from a U.S. glass producer to participate in an evaluation test of current oxy-fuel burner technology. The need to comply with South Coast Air Quality Management District (Los Angeles) regulations was a major factor in this glass producer's decision to conduct evaluation tests in the fall and winter 1993. The testing consisted of the installation of 4 representative burners from each participating company in an existing oxy-fuel fired furnace (Table 2). At that time, the furnace had been in operation for approximately 18 months, using 10 oxy-fuel burners, which had not been supplied by Maxon. The 4 test burners would carry approximately 50% of the total heat input to the furnace. Evaluation criteria were established (Table 3) and tests began in late summer 1993. Each set of test burners was scheduled to run for 2 to 4 weeks. A total of 5 burner suppliers participated in the testing. With 4 OXY-THERM LE burners firing 50% of the furnace load, a 30% reduction in NOx emissions (below the historical oxy-fuel baseline) was recorded. Based on NOx performance and the evaluation criteria in Table 3, the glass producer selected the OXYTHERM LE for replacement of the existing burners in the furnace used for the comparison test, as well as the conversion of a newly rebuilt furnace in California. Both furnaces were designed and engineered by the glass producer. Firing 50% of the furnace load with test burners was not an ideal performance predictor of a total conversion to one style of burner. However, the test represented a reliable comparison, since all burners were subjected to identical operating conditions. 5 |