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Show Paper presented at the 1998 AFRC/JFRC International Symposium, Maui, Hawaii October 11-15, 1998 DEVELOPMENT OF AN ULTRA LOW NOx BURNER WITH WIDENED STABILITY LIMITS Vladimir Lifshits Scott A. Drennan Coen Company, Inc. 1510 Rollins Road Burlingame, CA 94010 (650) 697-0440 phone (650) 686-5655 fax ABSTRACT This paper describes development process of a new ultra low N O x burner for industrial steam generators that targets 5 ppm N O x emissions on natural gas with primary emphasis on the burner operational limits over the turndown range and requirements to the combustion controls. Mixing of air and high percentages of recirculated F G R with fuel gas prior to ignition is used to control thermal and prompt NOx down to a few ppm range. Combustion driven pulsation is viewed as a major problem to be solved by burner design and high dynamic accuracy combustion controls. This paper specifically addresses the flammability and burner stability issues involved with ultra low N O x performance. The need for advanced combustion controls and flame scanners are also discussed. A variable geometry burner, with multiple fuel zones, described showed significant improvements to the stability limits with respect to allowable deviations in the amounts of F G R and excess air over wider turndown. The developed burner has demonstrated the target ultra low N O x levels of less than 5 ppm without air preheat and less than 9 ppm with air preheat up to 600°F. Corresponding Author |