Chemical kinetic modeling was applied to simulate N transformation in the pressurized oxy-fuel combustion process of pulverized coal. Modeling accuracy was validated by experimental data at different operation pressures. The key reaction paths from fuel-N to different N products were revealed by analyzing the rate of production. NO formation was synergistically affected by six elementary reactions, in which NCO and other intermediate species were involved. The reactions among N, NH, NH₂, and NO were the key paths of N₂ formation. After pressurizing the combustion system, NO and N₂ contents decreased and increased, respectively. High operation pressure inhibited the diffusion of NO from the internal to the external part of char. This condition prolonged the residence time of NO inside the char, triggered a typical heterogeneous reaction between gaseous NO and unburned char, and reduced the conversion from fuel-N to NO. Moreover, modeling was performed to predict NO_x emission in pressurized oxy-fuel combustion as a function of various operating parameters, including temperature and excess air and recycling ratios. This study may provide guidance for reducing NO_x emissions and improving combustion efficiency in oxy-fuel combustion, and it can serve as a reference for industrial applications that involve pulverized coal combustion.

中文翻译：

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煤粉加压富氧燃烧氮转化模拟

应用化学动力学模型模拟煤粉加压全氧燃烧过程中的氮转化。通过不同操作压力下的实验数据验证了建模的准确性。通过分析生产率，揭示了从燃料-N 到不同 N 产物的关键反应路径。NO 的形成受到六种基本反应的协同影响，其中涉及 NCO 和其他中间物质。N、NH、NH ₂和NO之间的反应是N ₂生成的关键途径。对燃烧系统加压后，NO 和 N ₂含量分别减少和增加。高操作压力抑制了NO从炭内部向外部的扩散。该条件延长了NO在炭内部的停留时间，引发了气态NO和未燃烧炭之间的典型非均相反应，降低了燃料-N向NO的转化。此外，还进行了建模以预测加压氧燃料燃烧中的NO _{x排放与各种运行参数的关系，包括温度和过量空气以及再循环率。该研究可为富氧燃烧中降低NO x}排放和提高燃烧效率提供指导，可为涉及煤粉燃烧的工业应用提供参考。