Carrier-phase DNS of detailed NOx formation in early-stage pulverized coal combustion with fuel-bound nitrogen
Carrier-phase DNS of detailed NOx formation in early-stage pulverized coal combustion with fuel-bound nitrogen
复制标题
DOI：
10.1016/j.fuel.2020.119998
复制
发表时间：
2021-05
期刊：
影响因子：
7.4
通讯作者：
A. Shamooni;P. Debiagi;B. Wang;T. D. Luu;O. Stein;A. Kronenburg;G. Bagheri;A. Stagni;A. Frassoldati;T. Faravelli;Achim Kempf;X. Wen;C. Hasse
中科院分区：
文献类型：
--
作者：
A. Shamooni;P. Debiagi;B. Wang;T. D. Luu;O. Stein;A. Kronenburg;G. Bagheri;A. Stagni;A. Frassoldati;T. Faravelli;Achim Kempf;X. Wen;C. Hasse
在 3D 随时间演变的混合层设置中，对含有燃料结合氮的粉煤火焰 (PCC) 中详细的 NO x 形成进行了载相直接数值模拟，其中空气流（域的上半部分）中的拉格朗日颗粒（哥伦比亚烟煤）与下游中贫挥发物/空气燃烧的产物混合。燃料-N 的释放由氨、氰化氢和块状氮化焦油（吡啶）代表。通过将两步热解方法拟合到详细的非均相 PoliMi 动力学来模拟脱挥发分。采用包括NO x 和吡啶氧化的所有标准途径的全面均质机制。结果显示，火焰建立后，NO 分布在 NO 质量分数与挥发性混合物分数散点图的两个不同分支中，对应于下游火焰区域中的 NO 和上游附近的热点。在PCC的早期阶段，NO 2 、瞬发和热机制对总NO x 的贡献是有限的。 NO的主要来源是燃料-N，其中NH是最重要的前体。吡啶对于上游通过CHCHCN形成的CN生成NO起着重要作用。 CN 和氨氧化对 NH 产生的贡献最大。关于NO破坏，NO通过再燃烧过程与HCCO、CH i和C反应构成最大份额。 NO 被 NH 转化为 N 2 O，然后 N 2 O 转化为 N 2 以及 NO+ N→ N 2+ O 是直接将 NO 还原为 N 2 的两个最重要的途径。
Carrier-phase direct numerical simulation of detailed NO x formation in pulverized coal flames (PCC) with fuel-bound nitrogen is conducted in a 3D temporally evolving mixing layer setup where Lagrangian particles (Colombian bituminous coal) in an air stream (upper half of the domain) mix with the products of lean volatile/air combustion in the lower stream. The release of fuel-N is represented by ammonia, hydrogen cyanide, and a lumped nitrogenated tar (pyridine). Devolatilization is modeled by fitting a 2-step pyrolysis approach to the detailed heterogeneous PoliMi kinetics. A comprehensive homogeneous mechanism including all standard pathways of NO x and pyridine oxidation is adopted. Results show a partition of NO in two distinct branches of scatter plots of NO mass fraction vs. volatile mixture fraction after flame establishment, corresponding to NO in the lower stream flame region and hot spots near the upper stream. The contribution of NO 2, prompt, and thermal mechanisms to total NO x is limited in the early stages of PCC. The main source of NO is fuel-N, with NH being the most important precursor. Pyridine plays an important role for NO production in the upper stream through CN formed from CHCHCN. CN and ammonia oxidation have the highest contribution to NH production. Regarding NO destruction, NO reactions with HCCO, CH i and C through the reburn process constitute the largest share. NO conversion to N 2 O by NH followed by conversion of N 2 O to N 2 and NO+ N→ N 2+ O are the two most important pathways directly reducing NO to N 2.