【作者】 李宗翔；

【导师】 刘剑；

【作者基本信息】 辽宁工程技术大学 ， 安全技术及工程， 2007， 博士

【摘要】 高瓦斯易自燃煤层开采采空区是采煤工作面最大的灾害源,包括冒落瓦斯涌出和遗煤自燃释放CO气体两个方面,同时,采空区内存在着瓦斯涌出与遗煤自燃的耦合问题。针对这一问题开展了系统地研究。在同一流场中,将遗煤自燃和瓦斯涌出二者综合考虑,基于非均质渗流连续性方程、多相气体混溶扩散方程和多孔介质综合传热方程,建立采空区瓦斯与自燃耦合数学模型。用迎风格式有限元方法,结合现场条件,来分析两者耦合作用机理及其互动影响的一般规律。根据冒落采空区特点,在流线方程中引入修正函数,提出按边界类型自适应剖分和边界条件自动识别的实用计算方案,计算可在计算机上显示漏风流动规律和速度场。提出瓦斯大气两相混溶扩散方程,用负指数衰减函数的采空区瓦斯涌出强度模型,计算采空区瓦斯移动和分布状态;用模拟实验方法,分析了采空区瓦斯向工作面的涌出一般规律,结果更贴近于实际。从两相混溶扩散方程进而拓展到自燃过程中气体组分交换与变化的多相气体混溶流扩散通用方程,将瓦斯、氧、CO气体统一考虑,为在同一流场中瓦斯与自燃耦合研究创造了前提条件。将煤氧化速度常数作为衡量采空区自燃环境的特征指标;通过计算得到,采空区存在漏风流沿程耗氧,氧浓度分布非均衡性与漏风强度之间没有必然联系;以“速度和氧浓度二场叠加”确定自燃氧化带。通过自燃采空区的温度场计算,模拟了采空区煤早期自燃的升温过程,给出大量的动态变化图形分布解;讨论了自然发火期与各开采因素的关系。在本文研究中,更全面地考虑了流场漏风、工作面风量、自燃氧化性和工作面推进等开采技术因素和瓦斯地质因素等,考虑了瓦斯抽放与注氮等防灾技术措施对采空区瓦斯和自燃的影响。高瓦斯易自燃煤层开采工作面瓦斯超限与采空区煤自燃是不可调和的,提出风量安全调节范围指标和二灾害失衡的判别条件。详细论述了在实施防灾技术措施条件下的相互制约关系,回答了以下几方面问题:(1)瓦斯涌出强度与自燃条件和自燃规模的关系;(2)瓦斯涌出对自燃过程的影响;(3)瓦斯涌出稀释氧的作用强度;(4)瓦斯抽放引发采空区自燃的规律;(5)采空区防灭自燃注氮对采空区瓦斯绝对涌出量的影响。其中由大流量瓦斯抽放引发的采空区自燃问题,绝不可被忽视。更多还原

【Abstract】 Highly gassy and spontaneous combustion goafs are the greatest disaster sources of working faces, which includes gas effusion caused by caving and carbon monoxide released by the spontaneous combustion of coal remains, at the same time, there is a coupling problem of gas effusion and the spontaneous combustion of coal remains in goafs, and a systematic study to this problem is carried on. In a flow field, the spontaneous combustion of coal remains and gas effusion are taken into account synthetically, a mathematical model for the coupling of gas and spontaneous combustion in goafs are established based on the continuity equation for anisotropic seepage, the diffusion equation for the compounding of multiphase gases and the integrative heat transfer equation for porous medium. The general laws of the mechanism of coupling action and the reciprocal influences are analyzed by the finite element method of windward format, and the locale conditions are considered too.According to the characteristics of goafs, a modified function is introduced to streamline equation. A applied computing scheme which can achieve self-adapting split according to boundary style and the automatic identification of boundary conditions is put forward, and the flow law of air leakage and velocity field can be displayed on computer display. A diffusion equation for the compounding of gas and atmosphere is put forward. A negative exponent attenuation function adopted by the model for gas effusion intensity of goaf is used to compute the motion and distributing state of goafs. A simulating test method is used to analyze the general law of gas effusion from goafs to working faces, and the result is closed to practice.The general equation for the compounding and diffusion of multiphase gases of the exchange and variation of gas components during the spontaneous combustion is developed from the diffusion equation of two phase compounding, at the same time, gas, oxygen and carbon monoxide are considered unitedly, which provides a precondition for the study of the coupling of gas and spontaneous combustion in the same flow field.The velocity constant of coal oxidation is considered as the characteristic index of weighing the spontaneous combustion environment in goafs. According to the computation, a problem of oxygen consumption along the courses of air leakage exists in goafs, and there is no consequent relationship between the disequilibrium of oxygen concentration distribution and the intensity of air leakage. The oxidation zone of spontaneous combustion is determined by the superposition of velocity field and oxygen concentration field. The whole process of the forepart of spontaneous combustion in goafs is simulated by computing the temperature field of goafs with spontaneous combustion, and a lot of distributing solves in the form of figures with dynamic variations are given.In the study of the thesis, some more comprehensive mining and gas geology factors, such as the air leakage of flow field, the air quantity of working face, the oxidation of spontaneous combustion and the advance of working face are taken into account, moreover, the influence of some technical measures for hazard prevention, such as gas drainage and nitrogen injection to gas and spontaneous combustion in goafs are considered too.The contradiction between gas overrun and of highly gassy and spontaneous combustion of coal in goafs is implacable. The safe regulating range index of air quantity and the judge condition of the unbalance between the two hazards are put forward. The interaction relationship under the conditions of implementing technical measures of hazard prevention is discussed in detail. The following problems are solved: (1) the relationship between gas effusion intensity and spontaneous combustion conditions and spontaneous combustion scale. (2) The influence of gas effusion on the process of spontaneous combustion. (3) The action intensity of oxygen dilution caused by gas effusion. (4) The law of spontaneous combustion in goafs caused by gas drainage. (5) The influence of the spontaneous combustion control measures of nitrogen injection on the absolute gas effusion quantity in goafs. The problem of spontaneous combustion in goafs caused by mass flow gas drainage can not be neglected.更多还原