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Show Fuel gas enters the combustion zone via multiple gas spuds, designated "core-jetM, which circumvent the annulus zone. The proprietary core-jet nozzle pattern is designed to promote maximum internal fuel staging without exceeding the limitations imposed by flame shaping requirements. The core-jet nozzle pattern is also designed to promote local stoichiometric levels compatible with maximum burner stability and minimum noise levels. This is especially important when utilized in high SHAA applications and when high levels of recirculated flue gas are employed. BURNER PERFORMANCE During the first half of 1992, second generation OAF burners were successfully started up in 27 package boiler units as summarized in Table 1. Most units were started up within an acceptable time frame (typically under a week) I and easily met guaranteed emission levels. No problems were experienced with excess burner induced rumble or vibration, even when the burner was used in applications with SHAA's approaching 140,000 BTU/HRFT". Figure 3 summarizes the operating NOx levels for all units started up in the first half of 1992. It should be noted that the listed NOx emission numbers may not necessarily represent lowest achievable for each application, but may be indicative of a comfortable margin below regulatory requirements. Most of the units operating above .1 # /MMBTU NOx represent air preheat and/or propane gas applications. As shown in Figure 4, the vast majority of units operate with CO levels under 50 ppm. This can be attributed to the narrow flame and mixing characteristics incorporated into the burner design. Even with heat inputs per foot of furnace width as high as 43 MMBTU /HA-FT, no problems were experienced with sidewall flame impingement. 5 Figure 1 DAF Register ....... Controhd Wix Fuei ItId AI Zone / Fuel Jets Entrain CombustI«t PToducts T empenture .nd """ / to Reduce Flame " - , 0, Concemnooon ~~"'L ... ' '\ Figure 2 DAF Air Flow Patterns ~?-~$.' k/ //,: jj' J/ 'J P - |