Experimental and ReaxFF molecular dynamic study of NO emission during municipal sludge/coal co-combustion
Experimental and ReaxFF molecular dynamic study of NO emission during municipal sludge/coal co-combustion
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DOI：
10.1016/j.fuel.2022.127342
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发表时间：
2023-04
期刊：
影响因子：
7.4
通讯作者：
Tong Xu;Chunbo Wang;Dikun Hong;Song Li
中科院分区：
文献类型：
--
作者：
Tong Xu;Chunbo Wang;Dikun Hong;Song Li
采用实验和ReaxFF分子动力学方法研究了城市污泥与梅花井烟煤混烧过程中NO的排放行为。实验和ReaxFF MD结果均表明，MS/MHJ共燃对NO排放有负协同效应。此外，MS/MHJ共燃对N2和NO2的排放具有正的协同效应。利用原子标记法，观察到在共燃过程中，MS-NO的产率降低，而MHJ-NO的产率几乎不变。同时，MS-N2和MS-NO2的生成量也有所增加。结果表明，MHJ对掺混燃烧过程中的MS-NO排放有显著影响，而MS对MHJ-NO排放影响不大。这归因于MHJ消耗更多的氧，导致在共燃过程中产生更多的OH自由基，加速MS中吡咯和吡啶结构的裂解，形成更多的含氮化合物。随着燃烧的进行，来自MS的含氮化合物逐渐转化为HCN。随后，HCN被氧化为NCO，这增加了共燃过程中MS-NCO的产率。同时，共燃过程中MS-NCO的增加促进了MS-NCO与MS-NO之间的还原反应，提高了MS-N2的产率。此外，O自由基生成量的增加也促进了MS-NO向MS-NO2的氧化.
In this work, the emission behavior of NO during the co-combustion of municipal sludge (MS) and Meihuajing bituminous coal (MHJ) was studied using experiments and ReaxFF molecular dynamics methods. Both experimental and ReaxFF MD results indicated that there has negative synergistic effect on NO emission during MS/MHJ co-combustion. In addition, there has positive synergistic effect on N2and NO2emission during MS/MHJ co-combustion. Using the atomic labeling method, it was observed that the yield of MS-NO decreased, while the yield of MHJ-NO was almost unchanged during co-combustion. Moreover, the yields of MS-N2and MS-NO2during co-combustion were increased. It indicated that MHJ has a significant effect on the MS-NO emission during co-combustion, while MS has little effect on the MHJ-NO emission. It attributed to the fact that MHJ consumed more oxygen, which resulted in more OH radicals generated during co-combustion, accelerating the cleavage of pyrrolic and pyridinic structures in MS to form more nitrogen-containing compounds. As combustion proceeds, the nitrogen-containing compounds from MS were gradually converted to HCN. Subsequently, HCN was oxidized to NCO, which increased the yield of MS-NCO during co-combustion. Then, the increase in MS-NCO during co-combustion promoted the reduction reaction between MS-NCO and MS-NO, increasing MS-N2yield. In addition, the increased yield of O radicals also promoted the oxidation of MS-NO to MS-NO2during co-combustion.