Experimental study and mechanism analysis of NO formation during volatile-N model compounds combustion in H2O/CO2 atmosphere
Experimental study and mechanism analysis of NO formation during volatile-N model compounds combustion in H2O/CO2 atmosphere
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DOI：
10.1016/j.fuel.2020.117722
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发表时间：
2020-08
期刊：
影响因子：
7.4
通讯作者：
Qiangqiang Ren;H. Chi;Jian Gao;Chunxiu Zhang;Sheng Su;Huini Leong;Kai Xu;Song Hu;Yi Wang-Yi-Wan
中科院分区：
文献类型：
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作者：
Qiangqiang Ren;H. Chi;Jian Gao;Chunxiu Zhang;Sheng Su;Huini Leong;Kai Xu;Song Hu;Yi Wang-Yi-Wan
研究了挥发分氮燃烧条件下H2O和CO2对NO生成的影响。通过实验和数值模拟研究了挥发氮模型化合物（吡啶和吡咯）在H2O/CO2气氛下燃烧过程中NO生成的特性和机理。结果表明，在吡啶和吡咯燃烧过程中，加入H2O和CO2可显著降低NO的生成。在O2/H2O气氛下，H2O能显著促进H+ O2（+ M）参与HO 2（+M）反应，消耗反应体系中的H和O2。结果表明，抑制了H+ O2参与OH+ O的链式反应，减少了O自由基的产生，从而抑制了NO的生成。在O2/CO2气氛下，CO2的加入抑制了CO+ HO参与CO2 + H和NCO+ O2参与NO+ CO2。结果表明，NO还原反应通过2 CO +2 NO参与N2 + 2 CO2的方式进行，而NCO氧化生成NO的反应受到抑制。在O2/H2O/CO2气氛下，由于HCN+ OH参与CN+ H2O和NCO+ O2参与NO+ CO2的抑制作用，NO的生成进一步受到抑制.发现氮转化机理为：吡啶和吡咯中的氮首先热解为NH3和HCN，然后被O和OH基团氧化为NH、HNO、N、NCO等含氮中间相，HNO和NCO继续氧化生成NO，NCO、NH和NH 2与生成的NO反应生成N2，以NCO为主.
This work aimed at deeply investigating the effects of H 2 O and CO 2 on NO formation under volatile-N combustion. The characteristics and mechanism of NO formation during volatile-N model compounds (pyridine and pyrrole) combustion in H 2 O/CO 2 atmosphere were systematically investigated via experiments and numerical simulations. The results both showed NO formation significantly decreased with addition of H 2 O and CO 2 during combustion of pyridine and pyrrole. Under O 2/H 2 O atmosphere, H 2 O can significantly promote the reaction H+ O 2 (+ M)↔ HO 2 (+ M) which consumed H and O 2 in reaction system. As a result, the chain reaction of H+ O 2↔ OH+ O was inhibited and O radical decreased, thus NO formation was inhibited. Under O 2/CO 2 atmosphere, addition of CO 2 inhibited CO+ HO↔ CO 2+ H and NCO+ O 2↔ NO+ CO 2. As a result, NO reduction was promoted via 2CO+ 2NO↔ N 2+ 2CO 2 and oxidation of NCO to form NO was inhibited. Under O 2/H 2 O/CO 2 atmosphere, NO formation was further inhibited due to inhibitions of HCN+ OH↔ CN+ H 2 O and NCO+ O 2↔ NO+ CO 2. The mechanism of nitrogen conversion was found: Nitrogen in pyridine and pyrrole was firstly pyrolyzed into NH 3 and HCN, then oxidized by O and OH groups to be nitrogen-containing intermediate phases such as NH, HNO, N, NCO, etc. HNO and NCO will continue to be oxidized to generate NO. NCO, NH and NH 2 would react with the generated NO to form N 2, and NCO dominated.