| Abstract |
Fuels such as coal, oil shale and residual oils contain nitrogen which is converted to HCN, NO and N2 during combustion. The utilization of these energy sources in an environmentally acceptable manner requires combustion strategies which maximize conversion of bound nitrogen to the desirable product N2. To understand fuel nitrogen conversion, the kinetics of formation and destruction of NO, N«0, HCN, NH~ and N2 have been studied by doping sub-atmospheric hydrogen-oxygen-argon flat flames with pyridine. Species profiles were measured via gas chromatography (H2, 02, N2, N20, CO, C02, Ar), chemiluminescence (NO), ionspecific electrodes (HCN, NH3) and UV absorption (OH). A novel feature of the experimental technique is the use of predicted radical profiles (O, H, OH) for pure hydrogen-oxygen-argon flames to analyze the kinetics of doped flames. Rate coefficients have been determined at 700-1400 K by analysis of reaction rate profiles for three elementary reactions: HCN + OH - HNCO + H; NH + 0 - NO + H; NH + NO - N2O + H. Using a postulated reaction mechanism, species profiles have been predicted by integration of the conservation equations for lean, stoichiometric and rich flames. Good agreement was achieved with experimental profiles (4> = 0.6, 1.0, 1.4) and measured post-flame yields as a function of stoichiometry (4> - 0.4-2.0). An equivalence ratio of 1.3-1.4 was found to maximize conversion of fuel nitrogen to N2. |
