Kinetic modeling and sensitivity analysis of nitrogen oxide formation in well-stirred reactors

Abstract

We have modeled the experimental data of Bartok et al. and Duterque et al. on methane combustion in stirred reactors. A method to calculate the first-order sensitivities of the mole fractions and temperature with respect to the rate constants is discussed and applied to nitric oxide production. We have thus been able to evaluate the nitrogen chemistry in the presence of hydrocarbons under stirred conditions. We find the extended Zeldovich mechanism to be the major source of NO under lean conditions, while the prompt-NO formation is dominant under fuel-rich conditions. The important features of the model under fuel-rich conditions are the following: 1. 1. The reaction CH + N 2 ⇄ HCN + N is the only important initiating step in the prompt-NO formation. 2. 2. The CH concentration is established through the sequence CH 3 + ⇄ CH 2 + HX, CH 2 + ⇄ CH + HX, CH 2 + X ⇄ C + OH, where X is H or OH. 3. 3. Nitric oxide is recycled back to CN and HCN through reactions with C, CH, and CH 2. This results in the exhaust of significant quantities of HCN from the reactor.