矿井火区封闭进程中瓦斯爆炸极限模拟研究

发布时间：2018-03-05 10:09

本文选题：矿井火区封闭　切入点：瓦斯爆炸　出处：《中国矿业大学》2017年硕士论文　论文类型：学位论文

【摘要】：瓦斯爆炸热动力灾害是威胁矿井安全生产,矿井火区封闭进程是瓦斯爆炸爆燃事故易发时间节点。矿井火区封闭进程改变了矿井中气体浓度场、温度场,改变了瓦斯爆炸危险性。因此,本文以从火源燃烧状态、多组分烟气耦合作用下甲烷混合气体爆炸、火区封闭过程瓦斯爆炸危险性时空分布等方面对矿井火区封闭过程瓦斯爆炸热动力灾害发生规律进行研究。通过对矿井火区封闭进程进行研究,揭示了封闭火区火源燃烧状态变化规律。研究结果表明采用进回风巷同时封闭方法对矿井火区进行封闭时,封闭区域局部阻力随封闭时间增加呈指数增加,且在封闭过程中机械通风风量线性降低,当机械通风风量降低至初始风量65%~70%时,封闭火区火源位置氧气浓度降低至16%以下,火源燃烧状态由富氧燃烧转变为富燃料燃烧,火灾烟气由单一气体为主转变为多组分气体共存。利用甲烷燃烧爆炸过程中热平衡原理,提出了开放系统、半封闭系统以及封闭系统的热平衡模型,采用热平衡法建立多组分气体耦合作用下甲烷混合气体爆炸界限的演化模型。揭示了单一火灾气体对甲烷爆炸极限影响规律:CO_2提升了甲烷混合气体爆炸下限,降低了混合气体爆炸上限;CO降低了甲烷混合气体爆炸下限。在此基础上,提出了CO_2和CO多组分气体耦合作用甲烷混合气体极限动态变化规律:CO_2和CO烟气浓度与组分比值改变了甲烷混合气体爆炸极限,且混合气体爆炸极限对不同组分气体敏感性存在差异:甲烷混合气体爆炸下限对CO更敏感,甲烷混合气体爆炸上限对CO_2更为敏感。应用数值分析研究了矿井火区封闭进程中瓦斯爆炸危险性,揭示了火区封闭过程中采空区瓦斯爆炸危险性时空分布。采用有限元模型,并对FLUENT进行二次开发实现矿井火区封闭进程的数值分析。矿井火区封闭进程中瓦斯在CO_2和CO烟气耦合作用下,爆炸危险性较高区域主要位于采空区靠近火源位置与回风侧区域,其在靠近火源位置出现高度危险区域;当封闭过程中风量降到原配风量的小于7.5%~12.5%时,封闭火区内可燃性混合气体浓度位于爆炸极限范围内,爆炸的危险性最高。
[Abstract]:The thermal power disaster of gas explosion is a threat to mine safety, and the process of mine fire area closure is the time node of gas explosion and deflagration accident. The process of mine fire zone closure changes the gas concentration field and temperature field in the mine. Therefore, in this paper, the methane mixture gas explosion under the action of multi-component flue gas coupling from the state of fire source combustion, In this paper, the occurrence law of gas explosion thermal dynamic disaster in the process of coal mine fire closure is studied from the aspects of the space-time distribution of gas explosion hazard in the process of fire area closure, and the process of mine fire area closure is studied. The research results show that the local resistance of the closed area increases exponentially with the increase of the closing time when the fire source combustion state of the closed fire area is closed at the same time as the inlet and return air lane is closed to the mine fire area. In the process of sealing, the air volume of mechanical ventilation decreases linearly. When the air volume of mechanical ventilation decreases to the initial air volume of 65 ~ 70, the oxygen concentration of the fire source in the closed fire area decreases to less than 16%, and the combustion state of the fire source changes from oxygen-enriched combustion to fuel-rich combustion. Based on the principle of heat balance in methane combustion and explosion, the thermal equilibrium models of open system, semi-closed system and closed system are proposed. The evolution model of the explosion boundary of methane mixture gas under the coupling action of multi-component gas is established by using the thermal equilibrium method. The effect of a single fire gas on the limit of methane explosion is revealed. The upper limit of mixture gas explosion is reduced and the lower limit of methane mixture explosion is reduced by CO. The dynamic variation of the limit of methane mixture gas coupled with CO_2 and CO is presented. The concentration of CO and the ratio of CO concentration to component change the explosion limit of methane mixture gas. The explosion limit of mixed gas is sensitive to different components of gases: the lower limit of methane mixture explosion is more sensitive to CO. The upper limit of methane mixed gas explosion is more sensitive to CO_2. The danger of gas explosion in mine fire area is studied by numerical analysis, and the spatiotemporal distribution of gas explosion risk in goaf is revealed by using finite element model. Numerical analysis of FLUENT secondary development to realize the process of mine fire closure. Under the action of CO_2 and CO flue gas coupling, the area with high explosion risk is mainly located in the goaf near the fire source position and return air side area. The combustible mixed gas concentration in the closed fire zone is within the limit of explosion, and the explosion risk is the highest when the air volume decreases to the original air volume less than 7.5 ~ 12.5 in the closed fire area.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.7

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