采空区遗煤氧化升温时空演化机制研究

发布时间：2018-03-01 02:13

  本文关键词： 低温氧化 多场耦合 非均质孔隙率 采空区 四维动态　出处：《北京科技大学》2017年博士论文　论文类型：学位论文

【摘要】：采空区遗煤自燃是煤矿灾害的主要来源之一,严重威胁着煤矿的安全生产。本文基于煤氧化学动力学机理及多孔介质渗流理论,对采空区在动态推进过程中遗煤氧化升温的时空演化规律进行研究,为实际生产及煤矿自燃靶向性防治提供依据。本文在移动双坐标系的基础上,建立了采空区氧化升温时空演化动态模型,主要包括基于煤氧化学动力学原理的煤氧反应动力学模型和多场耦合模型、非均质孔隙率时空演化模型。通过Fluent开源接口UDF将模型编入Fluent中对已有控制方程进行补充和修正,对阳泉煤业孙家沟矿13304工作面采空区升温规律进行了四维动态模拟研究。通过相似准则的推导,搭建了动态采空区实验台,对模型做进一步的研究和验证,采用分体式开采系统实现工作面的动态推进，研制了一种自发热材料,与煤混合后做为相似材料以非均质的方式填充在采空区内,采用48路温度巡检仪进行密集采集数据,对动态采空区升温过程进行了实验研究。研究表明：通过四维动态模拟研究,得到了采空区温度场在工作面推进过程中的变化规律,主要包括温度场的分布规律、升温规律、高温点的迁移规律、升温—耗氧之间的耦合关系等。高温区域主要在进风侧,随着工作面的推进,高温区域不断向前迁移,迁移速度主要受到孔隙率、工作面推进速度及开采时间的影响；对采空区氧化升温之间的耦合关系进行研究,揭示了采空区内高温区与高氧区之间的动态变化规律，高温区始终位于高氧区之后,二者的背离程度越大,进入降温区时剩余氧量越多,对自燃的削弱程度越大；从多场耦合的角度,对比分析了U型通风与U+L型通风采空区遗煤的氧化过程，，表明尾巷的存在使得氧化升温带宽度增加且向回风侧偏移,回风侧在联络巷口温度高出周围约3.3℃,联络巷口具有很好的升温潜质,确定了尾巷对采空区自燃的危害性。通过在实验室搭建动态采空区氧化升温实验,对采空区时空演化动态模型进行验证。研制出了一种能在室温下形成明显温度场的自发热材料,通过试管实验及传热相似性实验,得到了相似材料的最佳配比；相似材料与原煤的放热量相似比qr=4.5,耗氧速率相似比V(T)r=120,实验中时间相似比为tr=1/100。对工作面推进过程中的温度场进行研究,表明无论是温度场的分布、升温速率都与数值模拟结果基本吻合。通过束管监测的方式在采空区进风侧和回风侧预埋测点，进行了现场测温试验。根据特征点升温规律的实测值和模拟值对比分析结果,表明模拟结果与实测结果具有一致性。从而为确定采空区高温区域的参数及采空区遗煤自燃的预测提供依据。
[Abstract]:The spontaneous combustion of coal in goaf is one of the main sources of coal mine disasters, which seriously threatens the safety of coal production. This paper is based on the kinetic mechanism of coal oxidation and porous media seepage theory. The temporal and spatial evolution law of coal oxidation and heating in goaf during dynamic advance is studied, which provides the basis for actual production and prevention and control of coal spontaneous combustion. This paper is based on moving double coordinate system. The spatio-temporal evolution dynamic model of oxidation heating in goaf is established, which includes coal oxygen reaction kinetic model and multi-field coupling model based on coal oxidation kinetics principle. The model of spatiotemporal evolution of heterogeneous porosity is programmed into Fluent by UDF, an open source interface of Fluent, to supplement and modify the existing governing equations. In this paper, the four dimensional dynamic simulation study on the heating law of goaf in 13304 working face of Sunjiagou Coal Mine, Yangquan Coal Industry is carried out. Through the derivation of similar criteria, a dynamic goaf experimental bench is built, and the model is further studied and verified. In this paper, a self-heating material is developed, which is mixed with coal and filled in the goaf in a heterogeneous way after mixing with coal, and 48 channel temperature patrol instrument is used to collect the data. The experimental study on the process of dynamic goaf temperature rise is carried out. The results show that through the four dimensional dynamic simulation study, the variation law of the temperature field in the working face is obtained, which includes the distribution law of temperature field and the law of heating up. The migration law of high temperature points and the coupling relationship between temperature rise and oxygen consumption etc. The high temperature area is mainly in the inlet air side. With the advance of the working face, the high temperature area moves forward continuously, and the migration velocity is mainly affected by porosity. The influence of working face speed and mining time on the coupling relationship between oxidation and temperature rise in goaf is studied, and the dynamic change law between high temperature area and high oxygen area in goaf is revealed. The high temperature area is always located behind high oxygen area. The greater the degree of deviation between the two is, the more oxygen is left in the cooling zone, and the greater the degree of weakening to spontaneous combustion. From the point of view of multi-field coupling, the oxidation process of coal left in goaf of U-type ventilation and UL-type ventilation is compared and analyzed. The results showed that the width of the oxidation heating zone increased and the return wind side shifted to the return wind side. The temperature of the back wind side was about 3.3 鈩

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