Investigation on ignition behaviors of pulverized coal particles in a tubular swirl burner
Investigation on ignition behaviors of pulverized coal particles in a tubular swirl burner
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DOI：
10.1016/j.proci.2020.07.131
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
Yang Xu;C. Axt;Minhang Song;R. Kneer;Shuiqing Li
中科院分区：
文献类型：
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作者：
Yang Xu;C. Axt;Minhang Song;R. Kneer;Shuiqing Li
本文对一种新型全混式旋流燃烧器中湍流煤粉火焰的着火进行了深入的研究。采用Nikon D300s数码相机对不同环境条件下分散煤颗粒流的着火行为进行了统计研究。同时，还利用高速摄影技术记录了单个煤粒的燃烧动态。本研究对呼伦贝尔褐煤和准东煤两种低阶煤进行了煤样的煤岩性质测试。对旋流燃烧器和平焰燃烧器中煤粉颗粒的着火延迟时间进行了比较。与以前的层流平焰燃烧器的工作相比，目前的实验结果表明，湍流环境显着提高了所有煤样的点火，这是非常明显的高温和低氧条件下。此外，敏感性分析表明，强化传热和传质有助于早期点火的湍流。在低氧气氛中，传质系数的提高效果变得突出，其中挥发物的阻隔效应被增强的混合过程抑制。湍流的综合作用有利于点火模式向非均质主导区的转移。最后但并非最不重要的是，在湍流低氧环境中观察到的停止的挥发性火焰进一步证实了非均相点火的重要作用。
This paper intensively investigated the ignition of turbulent coal flames in a novel fully-mixed tubular swirl burner. The Nikon D300s digital camera was used to capture the statistical ignition behavior of dispersed coal particle streams in different ambiences. Meanwhile, the combustion dynamics of individual coal particles were also recorded by means of high-speed photography. Two low-rank coal samples, Hulunbel lignite and Zhundong coal, were tested in this study. The ignition delay times of coal particles in the swirl burner were compared with those in a flat-flame burner. In contrast to previous work on a laminar flat-flame burner, the current experimental results show that the turbulent ambience significantly enhances the ignition of all coal samples, which is exceptionally pronounced under high temperature and low oxygen conditions. In addition, the sensitivity analysis suggests that both the enhanced heat and mass transfer contribute to the early ignition in turbulence. The effect of elevated mass transfer coefficient turns prominent in low oxygen fraction ambience, wherein the volatile barrier effect is suppressed by the enhanced mixing process. The combined effect of turbulence favors the shifting of ignition modes to the heterogeneous-dominant region. Last but not least, the ceased volatile flame that visualized in turbulent low oxygen ambience further confirms the important role of heterogeneous ignition.