Experimental study on the pollutant emissions of premixed ammonia/methane/air flame within porous burner

In the present study, premixed ammonia-methane combustion within a two-layer porous burner was investigated experimentally in order to evaluate the pollutant emissions. The effects of alumina spheres diameter, equivalence ratio and ammonia fraction on the flame stability limits, CO and NO pollutant emissions were considered. The tests were performed for equivalence ratios from 0.8 to 1, ammonia fraction from 20% to 80% and a range of alumina spheres diameters from 5 to 40 mm. Measurements illustrated that increasing the equivalence ratio improved the flame stability limits regardless of ammonia fraction while flame stability limits decreased with increasing the ammonia fraction. Results indicated that for the mixtures with ammonia content less than 50%, increasing ammonia fraction caused increase in NO emission regardless to the equivalence ratio, while for mixtures with ammonia fractions higher than 50%, the NO emission decreased slightly as ammonia content increased. Meanwhile, with increasing the ammonia fraction, CO concentration decreased at examined equivalence ratios. It was found that increasing equivalence ratio increased the NO emission, while CO concentration decreased as equivalence ratio increased. Measurements proved that decreasing the diameter of alumina spheres caused decrease of NO and CO quantities regardless to equivalence ratio.