A comparison of low-NOx burners for combustion of methane and hydrogen mixtures

Lean premixed fuel mixtures of CH 4 and H 2 are studied in four different low-NO x burners. These four burners include a fiber burner, a swirl burner and two porous inert material burners with and without catalytic support. Measurements were performed of the concentrations of NO x , CO, CO 2 , and O 2 in the flue gases. The temperature profiles were also measured for the two different porous burners. The maximum measured temperature was 1830 K. The thermal loads based on the lower heating values were varied from 2.6 to 21 kW, and excess air ratios were varied from 1.0 to 1.9. The NO x emissions were less than 25 ppm at 3% O 2 for all experiments besides the fiber burner, which under the conditions used had NO x emissions up to 85 ppm. Another scope of the paper is to clarify the influences of hydrogen addition to methane and its effect on pollutant emissions. For the porous burners hydreogen was fund to lower the NO x emissions slightly, while for the other burners an increase, or no obvious effects, was found. The pressure variations over the burners were also measured, and the swirl burner was found to have the highest pressure drop. The use of low-NO x burners in gas turbines and industrial boilers is important in the reduction of pollutants from combustion applications. Other applications are small-scale combined heat and power systems utilizing such burners with low-temperature fuel cells or in Stirling engines.