大尺度条件下甲烷—空气和煤尘—空气混合及爆炸特性研究

发布时间：2018-04-18 08:54

本文选题：爆炸驱动 + 气体混合　；参考：《北京理工大学》2015年博士论文

【摘要】：甲烷爆炸或甲烷-煤尘爆炸是煤矿井下爆炸事故的主要形式，受到社会的广泛关注。甲烷-空气混合物、煤粉-空气混合物的混合过程与爆炸特性是爆炸事故发生的基础问题，因此开展此项研究工作具有重要理论意义和现实意义。本文利用以大尺寸密闭容器10m3爆炸罐为主体的多元气体混合及浓度监测实验系统；通过系统性实验，研究了进气装置结构尺寸、进气速率及不同进气压差等因素对甲烷-空气二元混合效果的影响，结果表明，当进气系统开孔直径为1.5mm、开孔间距为100mm、进气速率控制在8m3/h和初始真空度为-0.04MPa时，气体混合效果达到最佳状态。在甲烷-空气快速均匀混合的条件下，对大尺寸密闭容器10m3爆炸罐内甲烷在空气中的爆炸极限进行了测试，通过压力发展和光学测试相结合的评判标准，按照一定程度“绝对安全”的理念，确定10m3爆炸罐内甲烷在空气中的不爆炸下限为5.5%，不爆炸上限为15.5%。在对甲烷空气混合物燃爆压力波形分析后发现，接近甲烷爆炸下限浓度处存在三种压力波形式且存在前导弱压力波和二次发展形成的燃烧波共存的状态。基于爆炸波驱动固体颗粒抛撒的相关理论及基础研究成果，建立了适用于大尺寸空间内煤粉云团均匀稳定形成的方法。通过系统实验，对爆炸波驱动煤粉抛撒的过程进行动态分析，发现煤尘云团边界层速度呈现三个运动阶段：加速、减速和湍流阶段；通过分析不同驱动能量对煤粉云团的边界速度及云团体积的影响，发现在本实验条件下，中心药量的增加并不能获得较大的云团体积，可以获得较大的初始边界运动速度；当中心药质量百分比为1.3%时，煤粉量范围在320g到1110g之间的抛撒形成云团体积均达到最大值。利用AutoReaGas软件模拟研究了巷道内甲烷浓度、甲烷积聚区位置、障碍物阻塞比、初始压力、初始温度等因素对甲烷-空气混合物爆炸特征参数的影响；对比分析了甲烷-空气和甲烷-煤粉-空气混合物爆炸特征参数。结果发现，有煤粉参与的燃烧爆炸混合物的爆炸超压更大，，最大超压出现的位置更靠近点火源。上述取得的大尺度条件下甲烷及煤尘空气中混合与爆炸特性研究的成果，为煤矿井下爆炸预防和控制打下了基础。
[Abstract]:Methane explosion or methane-coal dust explosion is the main form of underground coal mine explosion, and has been widely concerned by the society.The mixing process and explosion characteristics of methane-air mixture, pulverized coal and air mixture are the basic problems of explosion accident, so it is of great theoretical and practical significance to carry out this research.In this paper, a multicomponent gas mixing and concentration monitoring system with 10m3 explosion tank as the main body is used, and the structural dimensions of the intake device are studied through systematic experiments.The effects of inlet rate and different inlet pressure difference on the effect of methane air binary mixing were studied. The results show that when the inlet system is 1.5mm in diameter and 100mm in spacing, the inlet rate is controlled at 8m3/h and initial vacuum of -0.04MPa.The gas mixing effect reaches the best condition.Under the condition of rapid and uniform mixing of methane and air, the explosion limit of methane in the 10m3 explosion tank of a large size airtight vessel was measured. The criterion of combining pressure development with optical test was adopted.According to the concept of "absolute safety" to a certain extent, the lower limit of non-explosion of methane in 10m3 explosion tank in air is 5.5 and the upper limit of non-explosion is 15.5.It is found that there are three kinds of pressure waves near the lower limit of methane explosion and the coexistence of the leading weak pressure wave and the combustion wave formed by the secondary development after the analysis of the explosion pressure waveform of the methane air mixture.Based on the theory of explosive wave driving solid particle dispersion and the basic research results, a method for uniform and stable formation of pulverized coal cloud in large space is established.Through systematic experiments, the dynamic analysis of pulverized coal dispersal driven by explosion wave is carried out. It is found that the velocity of the boundary layer of coal dust cloud presents three stages: acceleration, deceleration and turbulence;By analyzing the influence of different driving energy on the boundary velocity and cloud volume of pulverized coal cloud, it is found that under the experimental conditions, the larger cloud volume can not be obtained with the increase of the central charge, and the larger initial boundary velocity can be obtained.When the mass percentage of the central medicine is 1.3g, the volume of the cloud will reach the maximum when the amount of pulverized coal is in the range of 320g to 1110g.The effects of methane concentration, location of methane accumulation area, barrier blocking ratio, initial pressure and initial temperature on the characteristic parameters of methane / air mixture explosion were simulated by AutoReaGas software.The explosion characteristic parameters of methane-air and methane-coal-air mixtures are compared and analyzed.The results show that the explosion overpressure of the mixture with pulverized coal is higher and the location of the maximum overpressure is closer to the ignition source.The results of the study on the mixing and explosion characteristics of methane and coal dust in the air on large scale have laid a foundation for the prevention and control of underground explosion in coal mines.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD712.7

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