KINETIC MODELING OF HYDROCARBON NITRIC-OXIDE INTERACTIONS IN A FLOW REACTOR

The reduction of nitric oxide by reaction with C-1 and C-2 hydrocarbon s under reducing conditions in a flow reactor has been analyzed in ter ms of a detailed chemical kinetic model. The experimental data were pa rtly adopted from previous work and partly obtained in the present stu dy; they cover the temperature range 800-1500 K and the reburn fuels C H4, C2H2, C2H4, C2H6, and natural gas. Modeling predictions indicate t hat, under the conditions investigated, HCCO + NO and CH3 + NO are the reactions most important in reducing NO. The HCCO + NO reaction is th e dominant reaction when using natural gas or C-2 hydrocarbons as rebu rn fuels. This reaction leads partly to HCNO, which is recycled to NO, and partly to HCN, which is converted to N-2 or NO. When methane or n atural gas are used as reburn fuel, the CH3 + NO reaction contributes significantly to remove NO. Modeling predictions are in reasonably goo d agreement with the experimental observations for the fuels investiga ted, even though the NO reduction potential is overpredicted for metha ne and underpredicted for ethane. Modeling predictions for NO are very sensitive to the formation of HCCO and to the product branching ratio for the HCCO + NO reaction. Furthermore, the present analysis indicat es that more work is needed on critical steps in the hydrocarbon oxida tion scheme. (C) 1998 by The Combustion Institute.