Experimental research on the hydrocarbon species for reducing NO in methane reburning process

The concentration variations of CH 4 , H 2 , C 2 H 2 , O 2 , CO, CO 2 , NO, HCN and (NO+HCN) with stoichiometric ratio in methane reburning process were measured at elevated temperatures of 1373 K, 1423 K, 1473 K and 1523 K. The experimental results show that there are no any other hydrocarbon species, such as C 2 H 6 or C 2 H 4 , in the methane reburning process at elevated temperatures, C 2 H 2 is an important intermediate hydrocarbon precursor species except CH 4 in methane reburning process. The concentration tendencies of CH 4 , C 2 H 2 , NO, HCN, and (NO+HCN) have strong relationships with temperature. As temperature increases from 1373 K to 1523 K, the minimum concentration value of (NO+HCN) decreases from 450 ppm to 282 ppm, and the corresponding stoichiometric ratio decreases from 0.97 to about 0.94, the variation tendency of C 2 H 2 concentration is opposite with concentrations of NO, HCN and (NO+HCN). It could be suggested that C 2 H 2 is an important intermediate hydrocarbon precursor responsible for NO reduction during methane reburning process with the reaction route of CH 4 → C 2 H 2 for the formation of the active HCCO radical species.