甲烷/煤尘复合爆炸火焰的传播特性

周永浩; 甘波; 姜海鹏; 黄磊; 高伟

doi:10.11883/bzycj-2021-0064

甲烷/煤尘复合爆炸火焰的传播特性

doi: 10.11883/bzycj-2021-0064

大连理工大学化工学院精细化工国家重点实验室，辽宁大连 116024

基金项目: 国家重点研发计划（2018YFC0807900）

详细信息

作者简介:
周永浩（1995－　），男，博士研究生，rambozhou@mail.dlut.edu.cn

通讯作者:
高　伟（1984－　），男，博士，教授，博士生导师，gaoweidlut@dlut.edu.cn

中图分类号: O389; X932
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- 被引次数: 0
出版历程
- 收稿日期: 2021-02-10
- 录用日期: 2021-11-22
- 修回日期: 2021-05-13
- 网络出版日期: 2021-12-01
- 刊出日期: 2022-01-20

Investigations on the flame propagation characteristics in methane and coal dust hybrid explosions

State Key Laboratory of Fine Chemicals, Department of Chemical Machinery and Safety Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China

摘要

摘要: 为揭示甲烷/煤尘复合爆炸火焰的传播机理，利用气粉两相混合爆炸实验系统，在低于甲烷爆炸下限条件下，采用高速摄影机记录火焰传播图像，通过热电偶采集火焰温度，研究了煤尘种类以及甲烷体积分数对甲烷/煤尘复合火焰传播特性的影响。结果表明：挥发分是衡量煤尘燃烧特性的主导因素；随着煤尘挥发分的升高，燃烧反应增强，火焰传播速度升高，火焰温度升高；挥发分含量差异较小时，水分含量越低，燃烧反应越剧烈；在相同条件下，焦煤的燃烧反应强度最高，其次为长焰煤，最后为褐煤；随着甲烷体积分数的增加，煤尘颗粒的燃烧可由释放挥发分的扩散燃烧转变为气相预混燃烧，燃烧反应增强，火焰传播速度和火焰温度显著升高；热辐射和热对流作用促进煤尘颗粒热解，释放挥发分进行燃烧反应，维持复合火焰的持续传播；随着混合体系中甲烷体积分数的增加，混合爆炸机制由粉尘驱动型爆炸转为气体驱动型爆炸，燃烧反应增强；甲烷/煤尘复合爆炸火焰可由未燃区、预热区、气相燃烧区、多相燃烧区和焦炭燃烧区5部分组成，湍流扰动导致燃烧介质空间分布存在差异，使得燃烧区无规则交错分布。
- 甲烷/煤尘复合爆炸 /
- 火焰传播速度 /
- 火焰温度 /
- 火焰传播机理
Abstract: To reveal the flame propagation mechanisms in the methane/coal dust hybrid explosions, the effects of coal type and methane concentration on the propagation characteristics of methane/coal dust hybrid explosion flame were experimentally investigated. Experiments were performed in a gas-solid hybrid explosion apparatus with methane concentrations below the lower explosive limit. The flame propagation images were captured by a high-speed camera and the flame temperature was recorded by a high-accuracy thermocouple. The results show that the volatile component is the dominant parameter in measuring the combustion characteristics of a certain coal type. With the increase of the volatile component, the combustion of the methane/coal dust flame gets enhanced. As a result, the flame propagation velocity increases and the flame temperature goes up. When the difference of the volatile component is small, due to the heat loss of the water evaporation, the combustion reaction of coal dust with lower water component is severer, the flame propagates more quickly. With the increase of the methane concentration, the combustion of the coal dust particle gradually transforms from the diffusion combustion of the released volatile components to the premixed combustion. The heat radiation and convection promotes the pyrolysis of the coal particle and the combustible substances are released, which maintains the continuous propagation of the hybrid flame. With the increase of the methane concentration, the hybrid explosion mechanism is transformed from the dust-driven type to the gas-driven type, and the combustion reaction gets enhanced. The methane/coal dust hybrid flame could be composed by five zones: unburned zone, preheated zone, gas combustion zone, multi-phase combustion zone and char combustion zone. Behind the flame front, large or the agglomerated particles could continue the combustion reaction, which is the multi-phase combustion zone. In addition, the combustion of the char develops the char combustion zone. The turbulent disturbance results in the distribution difference of the combustion materials, which leads to the interlacement of the different combustion zones.
- methane/coal dust hybrid explosion /
- flame propagation velocity /
- flame temperature /
- flame propagation mechanisms

HTML全文

图 1 气粉两相混合爆炸火焰传播实验系统

Figure 1. Experimental system for flame propagation of gas-dust hybrid explosion

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图 2 粒径分布与扫描电子显微镜图像

Figure 2. Particle size distributions and SEM images

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图 3 煤尘热解特性

Figure 3. Pyrolysis characteristics of the coal samples

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图 4 甲烷体积分数为4.1%时3种煤样复合火焰传播图像

Figure 4. Flame propagation images of the hybrid flame of three coal species at 4.1% methane volume fraction

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图 5 甲烷体积分数为4.1%时3种煤样复合火焰传播速度和火焰温度

Figure 5. Flame propagation velocity and flame temperature of three coal species at 4.1% methane volume fraction

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图 6 三种不同甲烷体积分数的复合火焰传播图像

Figure 6. Flame propagation images of the hybrid flame at different methane volume fractions

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图 7 三种不同体积分数甲烷的复合火焰传播速度和火焰温度

Figure 7. Flame propagation velocity and flame temperature at different methane volume fractions

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图 8 甲烷/煤尘复合爆炸火焰传播机理

Figure 8. Methane/coal hybrid flame propagation mechanisms

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表 1 煤样工业分析和元素分析结果

Table 1. Proximate and ultimate analysis of different coal species

煤尘种类	各组分质量分数/%				各元素质量分数/%
煤尘种类	挥发分	水分	灰分	固定碳	C	H	O	N	S
焦煤	34.04	1.55	11.75	52.66	66.97	4.12	14.04	1.29	0.29
长焰煤	32.22	9.32	9.74	48.72	65.81	4.79	8.93	0.92	0.49
褐煤	26.50	5.14	6.78	61.59	71.73	4.00	10.39	0.73	1.24

下载: 导出CSV

表 2 煤尘粒径特性

Table 2. Characteristic parameters of the coal samples

煤尘种类	粒径/μm	D_[4,3]/μm	D_[3,2]/μm	S/（m²·g^–1）	d_(0.1)/μm	d_(0.5)/μm	d_(0.9)/μm
焦煤	0～75	22.745	6.138	0.978	2.604	16.665	51.655
褐煤	0～75	22.482	5.567	1.080	2.318	14.652	54.871
长焰煤	0～75	33.946	11.899	0.504	6.016	28.208	70.885

下载: 导出CSV

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