煤矿火区瓦斯爆炸危险性演化规律研究

发布时间：2018-10-30 19:07

【摘要】：煤矿发生火灾后(若无法直接灭火),尤其是采空区火灾,最常用的防灭火方法为封闭火区,但在火区封闭过程中极易发生瓦斯爆炸.本论文采用理论分析、实验研究和计算机模拟相结合的方法,研究瓦斯矿井火区封闭过程中流场、浓度场、温度场的变化规律.分析了火区气体来源及组分,得出火区内主要气体有：CO、CO_2、CH4、H2,根据流体力学、传热学等理论进行分析推导,得到了火区燃烧速度变化规律、火区气体分布规律、火区温度分布规律.进行了巷道火灾发展实验研究,在实验基础上建立了巷道火灾模型,对模型进行了划分,利用模型对火灾初期的发展进行了数值模拟,得到了火灾初期巷道中心垂直剖面流场随温度的变化规律,火区巷道中心垂直剖面温度分布规律以及气体浓度分布规律.进行了瓦斯爆炸危险性实验,得到了温度、可燃气体及惰性气体浓度等参数对瓦斯爆炸危险性和爆炸强度的影响规律,初始温度、初始压力升高,瓦斯爆炸危险性增加,混入CO浓度升高瓦斯爆炸危险性增加,注入N2与CO_2后,瓦斯爆炸危险性降低,失爆氧浓度分别为13.4%和15.8%,C02的惰化效果优于N2,瓦斯爆炸压力随初始温度的升高而降低,随着CO浓度的增加而显著增大,瓦斯爆炸上限时的爆炸压力远大于瓦斯爆炸下限时的爆炸压力,瓦斯浓度为9.5%时瓦斯爆炸压力最大,瓦斯爆炸压力梯度随瓦斯浓度的增高而增大,随着初始温度的升高而增大,但幅度较小,随着CO浓度的增加而显著增大,当初始压力在10～16MPa间变化时,瓦斯爆炸压力梯度基本不变,当初始压力在16-20MPa间变化时,瓦斯爆炸压力梯度随着初始压力的升高而增大.分析了火区封闭过程中流场变化规律并进行数值模拟,得到在入口平均风降到1.5m·s~(-1)以下时将形成逆流层,逆流层厚度、逆流长度和最大逆流速度均随着入口平均风速的减小而增大,随着风速的下降,火区瓦斯及CO浓度升高,当风速降低到0.1 m·s~(-1)时,火源上风侧10.1 m处巷道顶板附近,混入CO浓度大于5%,瓦斯爆炸下限降到2.8%以下,而该区域瓦斯浓度为4%且氧气浓度相对较高,极有可能发生瓦斯爆炸.分析了注惰的惰化作用、稀释作用,对封闭过程中注入惰性气体进行数值模拟,得出逆流层及易爆区域发展变化规律,确定了注惰参数的优化方向.本论文分析了瓦斯爆炸的影响参数及火区封闭过程中流场变化规律,通过数值模拟判定火区瓦斯爆炸危险区域,研究了封闭过程中注惰对瓦斯爆炸危险性的影响,对防止火区封闭过程中瓦斯爆炸,有效遏制煤矿重特大灾害事故的发生具有重要意义.
[Abstract]:After the coal mine fire (if can not be directly extinguished), especially in the goaf, the most commonly used fire prevention method is the closed fire area, but in the process of the fire zone closure, gas explosion is easy to occur. In this paper, theoretical analysis, experimental study and computer simulation are used to study the variation of flow field, concentration field and temperature field in the process of gas mine fire area closure. The source and composition of the gas in the fire zone are analyzed. The main gases in the fire zone are as follows: according to the theories of fluid mechanics and heat transfer, CO,CO_2,CH4,H2, is used to analyze and deduce the variation of the combustion rate and the distribution of the gas in the fire zone. Distribution of temperature in fire zone. On the basis of the experiment, the roadway fire model is established, the model is divided, and the initial development of the fire is simulated by using the model. The variation of flow field with temperature in the vertical section of tunnel center in the early stage of fire, the temperature distribution law of vertical section of tunnel center and the distribution law of gas concentration in the center of roadway in fire area were obtained. The effects of temperature, flammable gas and inert gas concentration on the gas explosion risk and explosion intensity are obtained. The initial temperature and initial pressure increase, and the gas explosion risk increases. The danger of gas explosion increased with the increase of CO concentration. After N _ 2 and CO_2 were injected, the risk of gas explosion decreased, and the inerting effect of oxygen loss concentration of 13.4% and 15.8C _ (02) was better than that of N _ 2, respectively. The gas explosion pressure decreases with the increase of the initial temperature and increases significantly with the increase of CO concentration. The explosion pressure of the upper limit of gas explosion is much greater than that of the lower limit of gas explosion. When the gas concentration is 9.5, the gas explosion pressure is the largest. The gas explosion pressure gradient increases with the increase of the gas concentration, and increases with the increase of the initial temperature, but the amplitude is smaller, and the gas explosion pressure gradient increases significantly with the increase of the CO concentration. When the initial pressure varies between 10~16MPa, the gas explosion pressure gradient is almost unchanged, and when the initial pressure changes between 16-20MPa, the gas explosion pressure gradient increases with the increase of initial pressure. The variation law of flow field in the process of fire closure is analyzed and numerical simulation is carried out. It is concluded that when the average inlet wind drops below 1.5 m s ~ (-1), the countercurrent layer will be formed and the countercurrent layer thickness will be formed. Both the countercurrent length and the maximum countercurrent velocity increase with the decrease of the inlet average wind speed, and with the decrease of the wind speed, the concentration of gas and CO in the fire zone increase, and when the wind speed decreases to 0.1 m s-1, the maximum countercurrent velocity increases with the decrease of the wind speed. Near the roof of roadway at 10.1 m above the upper side of the fire source, when the CO concentration is greater than 5, the lower limit of gas explosion is lower than 2.8%, while the gas concentration in this area is 4% and the oxygen concentration is relatively high, so it is very likely that gas explosion will occur. The inerting effect and dilution action of inert injection are analyzed, and the numerical simulation of inert gas injection in the closed process is carried out. The development and variation law of countercurrent layer and explosive zone is obtained, and the optimization direction of the inert injection parameter is determined. In this paper, the influence parameters of gas explosion and the variation law of flow field in the process of fire area closure are analyzed. The dangerous area of gas explosion in fire area is determined by numerical simulation, and the influence of inert injection on gas explosion risk is studied. It is of great significance to prevent gas explosion in the process of fire area closure and to effectively curb the occurrence of serious and serious disasters in coal mines.
【学位授予单位】：辽宁工程技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD712.7

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