Concentration of nitrogen oxides in fuel-combustion products

Methods of predicting the formation of nitrogen oxides in the combustion products of gaseous fuel are considered. Predicted concentrations of nitrogen oxides in the smoke gases are obtained for the combustion of natural gas in burners with different methods of mixing the fuel and air. Other conditions being equal, the minimum content of nitrogen oxides in the combustion products is seen in burners with open flames (flat-flame burners and radiant burners) and in burners with improved mixing. The content of nitrogen oxides is somewhat higher in burners without preliminary mixing of the fuel and air. The most toxic smoke gases are formed in injection burners. On heating the air for combustion, the content of nitrogen oxides in the smoke gases increases by a factor of 2–3. The discrepancy between the results obtained by the methods considered is 5–7% for high-temperature furnaces and 20% or more for low-temperature furnaces. With considerable air heating, the discrepancy increases.