Chemical-kinetic simulation of NO production in oxy-coal MILD combustion

The influence of mixing temperature and oxygen concentration between oxidizer and inner-recirculated flue gas on NO production in oxy-coal MILD combustion was studied through CHEMKIN simulation. The temperature was chosen as 1 273,1 373 and 1 473 K,besides,the atmosphere was 5% O2 / 90% CO2 / 5% H2 O,10% O2 / 85% CO2 / 5%H2 O,15% O2 / 80% CO2 / 5% H2 O and 25% O2 / 70% CO2 / 5% H2 O. The results show:NH2 is a crucial precursor that the reaction NH2 +OH = NH+H2 O is predominantly sensitive to the formation of NO,while the reaction NH2 +NO = N2 + H2 O is predominantly sensitive to the consumption of NO,both become more important as the oxygen concentration de- creases;the fuel-N→NO transfer rate and OH radical equilibrium concentration become larger as temperature and oxy- gen concentration increase;the mixing oxygen concentration of 10% -15% is a reasonable range for balancing NO and CO emissions,besides,there is little relationship between the mixing temperature and the influence of oxygen concen- tration on pollutant emissions;the reaction rate corresponding to NO reduction path increases under low oxygen con- centration,indicating that the trend of reduction is enhanced,therefore,the reaction progress extends and the overall complexity develops in MILD combustion.