675 / 2019-04-29 21:03:21

NO reduction by methane reburning under oxy-fuel conditions: Experiments and modeling

Reburning, NO reduction, Jet-stirred reactor, CO2 dilution

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New experimental results on the NO reduction by CH4 in N2 and CO2 atmospheres are obtained in a jet-stirred reactor. Experiments are conducted in the temperature range of 600-1323 K, the equivalence ratio range of 0.5-2.5 and the CO2 concentration range of 0-60%. The experiments are simulated using an updated reaction mechanism and the simulations are highly consistent with the experiments. In both N2 and CO2 atmospheres, less than 25% of NO is reduced under the fuel-lean condition while the NO reduction under the fuel-rich condition can exceed more than 40%. Moreover, the NO reduction in the CO2 atmosphere is approximately 30% smaller than that in the N2 atmosphere under fuel-rich conditions of 1200-1400 K. The inhibition of methane oxidation under oxy-fuel conditions is responsible for the decrease of the NO reduction efficiency and the main pathway of NO reduction is: NO (→H2CN) → HCN → CH3CN → NCO → N2. Moreover, the maximum NO reduction is achieved at 1300 K-1400 K and near an equivalence ratio of 1.2-1.5. With the increase in the CO2 concentration, the inhibition of methane oxidation is strengthened and the NO reduction is further weakened.