Experimental Investigation of a Staged Porous Ceramic Burner

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 o=0.87 and 20 ppm at o=1.0) were demonstrated by two-stage operation having a lean first stage and a fuel-rich second stage.