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Show This paper specifically addresses the problems with ultra low N O x burner controls over the burner turn down and means of solving or alleviating these problems with the new C O E N burner. The burner was developed during the course of research program funded by Gas Research Institute, C O E N Company, Southern California Gas, and California Air Resources Board. The following is a list of the specific burner performance targets for the current research program • less than 5 ppm NOx emissions (@ 3% 02, dry) for ambient combustion air • less than 9 ppm NOx emissions (@ 3% 02, dry) for up to 600°F preheated combustion air • less than 30 ppm CO emissions (@ 3% 02, dry) • low hydrocarbon emissions • low VOC / air toxics emissions In addition to meeting these burner emissions performance targets, the resulting burner must have several key features allowing it to be a commercially viable design. The burner must perform satisfactorily over a minimum of 7:1 turndown range. The burner must be dual fuel capable. It must be a design amenable to retrofit so it can be applied to existing boiler applications. The burner must not degrade safety or reliability for the industrial user. BURNER DEVELOPMENT PROCESS The successful development of a 5 ppm N O x industrial burner technology will require minimization of two major sources of NOx: Thermal and Prompt N Ox [Zeldovich, et al, 1947; Fenimore, 1971; Bowman, 1975] that theoretically can be achieved by burning natural gas premixed with combustion air and sufficient amount of FGR. Initial attempts were directed to the extending performance envelope of previously developed C O E N burners [Drennan, et al, 1996; Drennan and Lifshits, 1997] for operation with higher amounts of FGR. Prototypes of one burner built in two sizes 5 and 40 MMBtu/Hr demonstrated emissions down to 7 ppm. However, the burner did not have any margin in the performance. With slightly higher amounts of FGR, the flame was blowing out, as multiple recirculation areas in the wake of six trapezoid bluff bodies were not strong enough to stabilize the combustion. At the same the burner did not show pulsation problems within relatively wide ranges of the excess air and FGR. It is interesting to note that the same burner were successfully applied in high excess 3 |
