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Show 1. Fuel staging 2. Fuel staging combined with low FGR levels 3. High FGR levels Tests were conducted at Alzeta and at a field demonstration site. Emissions targets of sub-9 ppm NOx and sub-50 ppm CO were achieved using both fuel staging and FGR; however, the fuel staging technique appears to be a superior technique. FGR burners generally require a larger combustion fan to recirculate the flue gases leading to increased operating and maintenance costs. We believe that a staged fuel technique forming a secondary combustion zone around the RSB overcomes the limitations of FGR and meets our emissions targets. After verifying the staging technique in the 3 MMBtu/hr watertube boiler in our laboratory, we scaled up to 62.5 MMBtu/hr using an existing RSB in an oil field steamer operated by Chevron Production Company. We achieved NOx emissions as low as 10 ppm. After these encouraging results, we returned to our laboratory to refine the burners performance in the 3 MMBtu/hr watertube boiler. Our laboratory tests confirmed the field results, and by optimizing the secondary flame envelope, NOx emissions between 6 ppm and 10 ppm were demonstrated. Subsequent analyses showed that NOx emissions can be correlated with an entrainment factor. The entrainment factor is composed of variables that can be easily manipulated in the design phase of a project to develop a burner that can meet NOx emissions requirements of 9 to 30 ppm depending on application requirements. ACKNOWLEDGMENTS This work was sponsored in part by the U.S. Department of Energy, Office of Industrial Technologies. The field demonstration boiler was provided by Chevron USA. REFERENCES 1. Wilhelm, D.J., Johnson, H.E., and Karp, A.D., "The Potential Cost and Environmental Benefits of Very Low Emissions Burners for NOx Control" Final Report prepared by SFA Pacific, Inc. Mountain View, CA for U.S. Department of Energy, Contract DE-AC01-94FE63260, July 1995. 13 |