Experimental study on conversion of char nitrogen to NO during char combustion

Effects of different reaction conditions and fuel characteristics on conversion of char-N to NO during coal char combustion at batch particles condition in horizontal tube furnace reactor were studied. Results show that the fractional conversion of char-N to NO firstly increases with increasing the mixing ratios sharply and then keeps quite constant which can be explained by less secondary reaction of char-NO. When the reaction temperature changes from 850℃ to 1050℃, the fractional conversion of char-N to NO initially increases and then decreases. During the char combustion at 1050℃ with oxygen concentration increasing from 2% to 20% and the conversion ratio of char-N to NO reaches a maximum at 10% oxygen concentration. When the char-O₂ reaction occurs on the surface of char, higher NO conversion ratio is obtained for less secondary reaction of char-NO and when reaction temperature is up to certain value, NO reduction is apparently enhanced. Coal chars with high rank and high fuel-N content produces higher NO conversion ratio. Function groups of nitrogen on the surface of char also influence NO emission in our experiment.