关键词: 天然气, 氮氧化物, 稀释气, 反应动力学

Abstract:

The effect of different diluents on the NO_x  emission of the combustion of natural gas with CO₂ and N₂ was studied with premixed methane/air/diluent flame. The chemical effect and thermal effect of CO₂ on the NO production was revealed via conducting reactionpath analysis. The numerical results show that: 1) CO₂ is more effective than NO in emission reduction. The chemical effect is achieved by consuming larger part of CH₂(s) in the flame zone, leading to smaller NO production subsequent to lower CH concentration; 2) compared to the chemical effect, the thermal one plays a more important role in NO emission by reducing the adiabatic flame temperature of the mixture; 3) the introduced diluents enlarge the ignition delay time slightly and greatly reduce the laminar flame speed of the mixture, indicating that low NO_x  emission characteristic of diluents accompanies with significant inhibiting effect on the combustion of the mixture.

Key words: natural gas; NO_x , diluent, Kinetic reaction mechanism