气体再燃低NOx燃烧中NO与NHi的反应机理研究

Research on reaction mechanism between NO and NHi during low NOx gas reburning

    摘要
  • 摘要: 采用量子化学密度泛函理论(DFT)对NO与NHi自由基的反应机理进行了研究,并结合经典过渡态理论对各反应速率常数进行了计算。结果表明,NO与NH2自由基的反应体系可通过六个反应通道形成N2+H2O、N2O+H2和N2H+OH。从能量变化和反应速率两方面考虑,产物N2+H2O最容易生成,其最佳反应通道为NO+NH2→→N2+H2O;NO与NH自由基的反应体系可通过七个反应通道形成N2+OH、N2O+H和N2H+O;其中,N2+OH最容易生成,最佳反应通道为NO+NH→→N2+OH。比较发现, NH比NH2自由基更易与NO发生反应生成N2。因此,在实际运行中改变操作条件,实现NH2等向NH方向转化,有利于NOx的还原。

     

    Abstract: The reaction mechanisms between free radicals NO and NHi were studied using quantum chemical density functional theory (DFT) and rate constant for each reaction was calculated combining with classical transition state theory in this paper. The results show that there are six different reaction channels for free radicals NO and NH2, and the products are N2+H2O, N2O+H2 and N2H+OH. The optimum reaction channel is NO+NH2→→N2+H2O from the views of energy change and reaction rate. Similarly, N2+OH, N2O+H and N2H+O will be produced by seven different reaction channels between free radicals NO and NH, and the optimum reaction channel is NO+NH→→N2+OH. So it is easier for free radical NH reacting with NO to generate N2 than NH2. Therefore, an important conclusion was got that the lower NOx emission could be obtained by making NH2 turn to NH in the actual operation.

     

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