Comparison of explosion characteristics of methane/graphite powder and methane/pulverized coal

doi:10.11949/0438-1157.20220850

Abstract

Abstract:

In this paper, the similarities and differences of explosion characteristics of methane/graphite powder and methane/pulverized coal composite systems are studied by means of 20 L spherical explosion system. The results show that the methane concentration has an important influence on the explosion characteristics of methane/graphite powder two-phase systems and methane/pulverized coal two-phase systems, when the concentration of methane is 6%(vol), the pressure curve of methane/graphite powder system changes from single peak to double peak with the increase of graphite powder particle size, graphite powder with three particle sizes (D₅₀:7, 18,75 μm) reaches the maximum explosion pressure (0.691, 0.657, 0.611 MPa) at 60, 200, and 30 g/m³respectively. The maximum value of methane/pulverized coal system is 0.724 MPa at 400 g/m³, which is higher than that of methane/graphite powder system. When the methane concentration is close to the equivalence ratio, the explosion pressure peaks of the three particle sizes of graphite powder show a decreasing trend, the smaller the particle size of graphite powder, the smaller the explosion pressure peak of the methane/graphite powder two-phase system, the methane/graphite powder system reaches the maximum value when the mass concentration is 10 g/m³. The explosion pressure of methane/pulverized coal system reaches the maximum value of 0.776 MPa at 60 g/m³, the deflagration index of methane/pulverized coal is higher than that of graphite powder/methane system, because the volatile content of pulverized coal is high, the combustion of pulverized coal is more sufficient, and coke participated in the explosion process. The volatile content of graphite powder is low, and the carbon content is much higher than that of pulverized coal. Only a small part of graphite powder participated in the explosion. The research results will provide guidance for the prevention and control of gas powder two-phase mixture explosion.

Key words: graphite powder, two-phase system, volatile matter, explosion characteristics

摘要：

借助20 L球形爆炸系统研究了甲烷/石墨粉和甲烷/煤粉复合体系爆炸特性异同，结果表明：甲烷浓度对甲烷/石墨粉和甲烷/煤粉两相体系的爆炸特性有重要影响，当甲烷的浓度为6%（体积）时，随着石墨粉粒径的增加，甲烷/石墨粉体系的压力曲线由单峰转为双峰，三种粒径的石墨粉（D₅₀：7、18、75 μm）浓度分别在60、200、30 g/m³达到爆炸压力最大值0.691、0.657、0.611 MPa；甲烷/煤粉体系则在400 g/m³达到最大值0.724 MPa，高于甲烷/石墨粉体系。当甲烷浓度接近当量比时，三种粒径石墨粉的爆炸压力峰值均呈现逐渐减小的趋势，石墨粉的粒径越小，甲烷/石墨粉两相体系的爆炸压力峰值越小，甲烷/石墨粉体系在质量浓度为10 g/m³时达到最大值；甲烷/煤粉体系的爆炸压力则在60 g/m³时达到最大值0.776 MPa。甲烷浓度由6%增加至9%时，甲烷/石墨粉和甲烷/煤粉的爆炸火焰由不规则形状转为近似球形发展，火焰表面褶皱消失，同时两相体系的爆燃指数显著增高，当粉尘质量浓度大于30 g/m³时，甲烷/煤粉的爆燃指数大于甲烷/石墨粉体系，这是由于煤粉挥发分含量高，燃烧更为充分，且焦炭参与了爆炸过程；石墨粉本身的挥发分含量低，含碳量远超过煤粉，爆炸中仅有少部分石墨粉参与了爆炸。研究结果将对气粉两相混合物爆炸防治提供指导。

关键词: 石墨粉, 两相体系, 挥发分, 爆炸特性

CLC Number:

TD 712

Bei PEI, Mengjiao XU, Shuangming WEI, Jiaqi GUO, Shiliang LI, Ziwei HU. Comparison of explosion characteristics of methane/graphite powder and methane/pulverized coal[J]. CIESC Journal, 2022, 73(10): 4769-4779.

裴蓓, 徐梦娇, 韦双明, 郭佳琪, 李世梁, 胡紫维. 甲烷/石墨粉与甲烷/煤粉爆炸特性对比研究[J]. 化工学报, 2022, 73(10): 4769-4779.

Figures/Tables 12

Fig.1 Schematic diagram of experimental system

Table 1 Industrial analysis of graphite powder and pulverized coal

石墨粉/

粉煤

Fig.2 Variation curve of explosion pressure peak value of methane/graphite powder with mass concentration of three particle sizes

Fig.3 Comparison of peak explosion pressure of methane/graphite powder and methane/pulverized coal with mass concentration(pulverized coal D50: 83 μm, graphite powder D50: 75 μm)

Fig.4 Variation curve of peak pressure rise rate of three particle sizes of methane/graphite powder with mass concentration

Fig.5 Comparison of peak explosion pressure of methane/graphite powder and methane/pulverized coal with mass concentration(pulverized coal D50:83 μm, graphite powder D50:75 μm)

Fig.6 Schlieren flame structure images of methane/graphite powder and methane/pulverized coal

Fig.7 Flame velocity curves of methane/graphite powder and methane/pulverized coa

Fig.8 Deflagration index of methane / graphite powder and methane/pulverized coal with different methane concentrations

Fig.9 Industrial analysis of graphite powder before and after explosion

Fig.10 Industrial analysis before and after pulverized coal explosion

Fig.11 SEM images of graphite powder and pulverized coal before and after explosion

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