Effects of Chemical Kinetics in Predicting NOx Reduction with Selective Non-Catalytic Reduction (SNCR) Method

Using fossil fuels in industrial furnaces and power plants has a major role in the production of NOx. In the present study, different chemical kinetics are used to predict NOx reduction by selective non-catalytic reduction method (SNCR). In SNCR method, ammonia is injected into the flue gases in stack, in a temprature rang from 1150 to 1350K and converts NOx to nitrogen and H2O. To validate the present simulations, the results are comapred with experimental data of Ostberg et al. from a cylindrical tube of 5ft length and 5in diameter. Four chemical kinetic mechasnisms offered by Miller, Duo, Glarborg and Brouwer are used in this study to predict the NOx reduction. The results indicate that the Glarborg and Brouwer kinetic mechanisms predict the NOx reduction better than the other mechanisms. In this study the effects of inert materials (Hydrogen and Nitrogen) to improve the reduction of NOx by SNCR is also investigated. An important question that should be considered in SNCR method is the ammonia slip phenomenon.Using Glarborg chemical kinetic mechanism, it is found that theammonia slip decreases by increasing the inlet temperature to 1250K.