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Show PAPER NO. 49 EXPERIMENTAL INVESTIGATION OF A STAGED POROUS CERAMIC BURNER· Ronald D. Bell Radian Corporation Austin, TX 78720-1088 C. Chaffin and M. Koeroghlian Department of Mechanical Engineering University of Texas at Austin Austin, TX 78712 ABSTRACT An experimental investigation of two-stage, premixed methane/air combustion in a porous media burner was performed. A flame holder was used to extend the stability range in the first stage and stable burning was demonstrated in both stages at several equivalence ratios and flow rates. The axial temperature distribution for two-stage operation was found to exhibit lower average temperatures compared to single-stage burning. Emissions of NOx and CO were lower for two-stage operation (lean-rich) than that for single-stage burning at the same overall equivalence ratios. Two-stage burning using a fuel-rich first stage and a fuel-lean second stage did not demonstrate a significant advantage over single-stage operation for lowering NOx emissions. Very low NOx concentrations (10 ppm at ~=0.87 and 20 ppm at ~=1.0) were demonstrated by two-stage operation having a lean first stage and a fuel-rich second stage. INTRODUCTION Environmental pollution, caused by combustion-generated NOx emissions, is a matter of great concern to the public and industrial fuel users. Beginning in the 1960s, government agencies, prompted by this public concern with increasing levels of smog and air pollutants, imposed NOx reduction requirements upon existing power plants in major metropolitan areas. These restrictions were expanded in the 1970s and 1980s to include virtually all industries with combustion equipment. Industry, accepting the challenge, has already developed a large variety of technologies to meet the new needs. Modifying the combustion process has become the most widely used technology for reducing combustion-generated NOx• In addition, a number of flue gas treatment technologies, such as selective reduction with ammonia * Patent Pending -1- |