A COMPARISON OF LOW-NO_x BURNERS FOR COMBUSTION OF METHANE AND HYDROGEN MIXTURES

摘要

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 hydrogen was found 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.