Study on Formation Mechanisms and Control of NO_x in High Prssure Combustion

通过对一维层流火焰传播方程的数值求解，研究了甲烷-空气预混火焰中37种组分144个基元反应和传输特性对NO和瞬发NO生成的影响。(1)通过比较有无瞬发NO生成反应的NO浓度分布，发现瞬发NO的生成主要受CH+N_2*HCN+N反应控制。(2)当当量比为0.6 ~ 1.4时，瞬时NO在可见火焰区迅速生成，而在下游区除当量比为1.4外，不增加。在当量比为1.4的火焰中，在下游区域仍有瞬发NO生成。(3)瞬时NO与总NO的浓度比在可见火焰区域较大，在下游区域除当量比为1.4外迅速减小。(4)在298 ~ 398 K范围内，贫燃火焰中瞬发NO的生成量随未燃气体温度的升高而略有增加，而富燃火焰中瞬发NO的生成量基本不变。(5)在富燃火焰中，压力在0.1 ~ 0.2MPa范围内，瞬发NO的生成量随压力的增加而增加。

The equations of one-dimensional laminar flame propagation were numerically resolved to study the formation of NO and prompt NO in the premixed methane-air flame by considering 37 species with 144 elementary reactions and by using theoretically calculated transport properties.(1) By comparing the concentration profiles of NO calculated with and without prompt NO formation reactions, the formation of prompt NO is found to be predominantly governed by the reaction CH+N_2*HCN+N.(2) At any equivalence ratio from 0.6 to 1.4, the prompt NO is rapidly formed in the visible flame region and does not increase in the downstream rgion except for the equivalence ratio of 1.4. In the flame of equivalence ratio of 1.4, the prompt NO is formed still in the downstream region.(3) The concentration ratio of the prompt NO to the total NO is large in the visible flame region and it deacreases rapidly in the downstream region except for the equivalence ratio of 1.4.(4) The formation of prompt NO increases slightly with the unburned gas temperature from 298K to 398K in the lean flame, but does not change in the rich flame.(5) The formation of prompt NO increases with the pressure from 0.1MPa to 0.2MPa in the rich flame.