A model for prediction of selective noncatalytic reduction of nitrogen oxides by ammonia, urea, and cyanuric acid with mixing limitations in the presence of co

A reduced chemical kinetic mechanism for the prediction of selective noncatalytic reduction (SNCR) chemistry has been developed and incorporated into a three-dimensional. CFD-based turbulent reacting flow model. The model can be used for prediction and investigation of thermal and mixing effects as well as the influence of CO on the SNCR process in practical systems. The model accurately describes the SNCR chemistry as indicated by comparisons of NO reduction efficiency, ammonia slip, and N2O emissions with predictions using a complete chemical mechanism (70 species, 327 reactions) and experimental measurements from independent investigators. The reduced mechanism (6 species, 7 reactions) and individual rate constants are provised so that the mechanism could be incorporated into any CFD-based computer code. The effects of thermal environment (injection temperature and quench rate), reactant ratios (initial NO and NH3/NO), and reagent mixing on NO reduction by ammonia were investigated in the presence and absence of CO using a pilot-scale facility. Comparison with the coupled CFD/chemistry model predictions indicated good agreement, and both suggest that SNCR effectiveness is critically influenced by (1) finiterate chemistry, (2) imperfect reagent dispersion, (3) mixing delay times, (4) local CO concentrations, and (5) nonisothermal temperature profile.