【作者】 邵昊；

【导师】 蒋曙光；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2011， 博士

【摘要】 目前,瓦斯抽放是治理工作面瓦斯超限的主要方法,但由于我国大部分煤层的渗透率较低,单靠瓦斯抽放不足以解决高瓦斯综放工作面上隅角的瓦斯超限问题。对此,有学者提出利用增加漏风汇的方法予以解决,其中尾巷就是比较经济有效的治理上隅角瓦斯超限的方法。但我国《煤矿安全规程》规定,尾巷只能在不易自燃的煤层中使用,这就增加了高瓦斯易自燃工作面的瓦斯治理难度。因此有必要对高瓦斯易自燃工作面的瓦斯治理和煤自燃预防方法进行研究,力求找到一种不会增加煤矿自燃危险性的瓦斯治理方法,从而降低煤矿的瓦斯治理难度和开采成本,促进煤矿的安全高效开采。采空区煤自燃是一个复杂的物理、化学变化过程,其低温阶段的宏观表现为热量的产生和气体产物的生成。本文建立了能够反映采空区CH4、CO2的动态生成及采空区多孔介质固气间能量交换的三维动态采空区煤自燃数学模型,并对其关键参数进行了研究。利用动网格技术建立了反应工作面回采过程的三维动态几何模型,并用UDF自定义函数定义了采空区区域运行方式,结合煤自燃动态数学模型,实现了对三维采空区煤自燃的动态仿真模拟。U型通风系统为一源一汇的通风系统,U+L型通风系统为一源两汇的通风系统。U型通风系统不利于上隅角瓦斯防治,但可以最大限度的减少向采空区的漏风,对采空区煤自燃防治有利,而U+L型通风系统恰恰相反。为了对比研究U型通风系统和U+L型通风系统对采空区煤自燃的影响规律,分别研究了两种通风系统对采空区漏风流场、瓦斯浓度场分布规律以及采空区底板遗煤和冒落带中不可采的临近层遗煤的自燃耦合规律及高温点的空间分布规律,结果表明:(1)采空区双层遗煤的温度场分布状态是工作面通风系统、采空区遗煤位置、厚度、采空区瓦斯浓度、煤层倾角等因素综合作用的结果;(2)U+L型通风系统的回风巷和尾巷压差、煤层倾角对采空区煤自燃有重要的影响。围岩温度影响着矿井大气的温度、煤低温氧化热生成速率和向周围环境的散热速率。本文研制了温度控制范围从0～180℃的煤低温氧化绝热实验系统,完成了从起始温度20℃绝热升温到160℃的绝热氧化实验,结果表明,煤在低温阶段(20～40℃)的升温时间占总升温时间的54%。本文还利用煤自燃动态仿真模拟方法,对不同的围岩温度下,采空区温度场的分布规律进行了研究,研究表明围岩温度越高,正常回采时的采空区最高温度越高,停采后达到燃点的时间越短。实验室物理模拟实验和数值模拟实验表明,在相同煤质下,矿井围岩温度越低,采空区遗煤的自然发火期越长。基于以上研究,本文得到了一种新型的通风系统——U_U型均压通风系统。相对于U型通风系统,U_U型均压通风系统对采空区风压梯度和漏风流场的影响很小,不会增加采空区底板遗煤进风侧遗煤和冒落带遗煤温度,只会略微增大联络巷口附近的采空区遗煤温度,而联络巷口附近的遗煤自燃氧化过程完全可控。由于U_U型均压通风系统有大的沿空留巷断面,可以保证回风巷和联络巷仅有一个小的压差就能使联络巷中有足够的风量,这样既解决了上隅角瓦斯超限,又可把联络巷瓦斯浓度控制在较低水平。所以U_U型均压通风系统能够有效治理工作面瓦斯超限并且不会增加采空区煤自燃的危险性。U_U型均压通风系统在煤矿现场的成功应用表明,它是高瓦斯易自燃工作面治理瓦斯超限和防止采空区煤自燃的有效方法,具有重大的社会效益和经济效益。该论文有图114幅,表11个,参考文献163篇。更多还原

【Abstract】 Currently, gas emission has already become the main means of controlling gas overrun of working face. However, due to the lower penetrability of most coal seams in China, gas emission can not solve the problem of gas overrun in high gas working face, especially at the upper corner of the fully mechanized top-coal caving face. According to The Coal Mine Safety Rules, tail roadway is only used in coal seams that can not easily self-ignite which increases the difficulty of gas control in the working face of high gas and easily spontaneous combustion. Owing to different temperatures, the coal that has the same tendency of spontaneous combustion has great different periods of spontaneous combustion. Therefore, it is necessary to research on the gas control and prevention coal spontaneous combustion in the working face. This study strives to find a way of gas control which can not increase the risk of mine spontaneous combustion in the coal seams of high gas and easily spontaneous combustion, reduces the difficulty of gas control as well as the mining cost, and promotes safety and high effective mining.Coal spontaneous combustion in the gob is a complicated process of chemical and physical change. Macroscopic manifestation in the phase of low temperature is the products of the heat and gas. This dissertation established the dynamic mathematic model which could reflect the dynamic production of CH4 and CO2, and took into consideration that the dynamic mathematic model of the coal spontaneous combustion in three-dimensional gob which could transform the energy between the solid and liquid states of many holes medium. What’s more, its key parameters were also studied. The three-dimensional dynamic geometric model, which reflected the exploitation process of working face, was also established by means of dynamic mesh technique. What’s more, the operation mode for the field of gob was built using the self-defining function. The study realized dynamic analog simulation of the three-dimensional gob coal spontaneous combustion associated with the dynamic mathematical model of the coal spontaneous combustion.U-type ventilation system is one air inlet and one air outlet, while U+L-type ventilation system has one air inlet and two air outlets. U-type ventilation system is not conducive to gas prevention at the upper corner, but can decrease the quantity of air to gob by the greatest extent, which is good for preventing coal spontaneous combustion in the gob. TheU+L-type ventilation system runs counter to U-type ventilation system. This research respectively studied U-type and U+L-type ventilation systems which were influenced on the following laws: the distribution law of gas concentration field and temperature field,the spontaneous combustion coupling law of residual coal in the soleplate and not mining coal seam in the falling zone. This aim is to comparatively study influencing law of U-type and U+L-type ventilation systems which is influencing on coal spontaneous combustion in the gob. The dissertation yielded two important results through comparative study: 1) The distribution of temperature field of double-deck residual coal resulted from the joint effects, such as position and thickness residual coal in the gob, gas concentration in the gob, the obliquity of the coal seam, etc. 2) Pressure difference between return airway and tail roadway of U+L-type ventilation system and the obliquity of the coal seam were the foremost factors that influenced on the cal spontaneous combustion in the gob.The temperature of wall rock influenced on the temperature of atmosphere, the speed of heat of oxidation in low-temperature and condition and the speed of heat dissipation.This study developed adiabatic test system of the coal low-temperature oxidation that the controlling range of temperature was from 0℃to 180℃. The adiabatic test finished from the original temperature 20℃to 160℃. The finding show that rising time in the low-temperature phase accounts for 54% of the whole temperature rising time. This research made use of the way of dynamic analog simulation to study the distribution of temperature field of the gob under different wall rock temperatures. The results indicated that the higher the temperature of wall rock was, the higher highest temperature was under the normal mining, the shorter the time reached on critical burning point. The physical and numerical simulation tests in lab showed that the lower the temperature of wall rock was, the longer the stage of spontaneous combustion for the residual coal in the gob was.Based on above research, a new ventilation system-U_U-type pressure balancing ventilation system came out. Compared to U-type ventilation system, U_U-type pressure balancing ventilation system has a very small influence on the blast pressure gradient and air leakage flow field in the gob, will not increase the temperature of intake air side in the soleplate and residual coal, and only increase slightly the temperature of residual coal near crossheading. Under this condition, it can control the course of oxidation for the coal spontaneous combustion near the crossheading. U_U-type pressure balancing ventilation system had a large gob-side entry retaining fault surface. This surface can hold the enough air quantity because of the pressure difference of return roadway and crossheading. This not only solved the problem of gas overrun at the upper corner but also controlled the gas concentration in crossheading to be lower level. Thus, U_U-type pressure balancing ventilation system could be capable of controlling gas overrun and not increase the risk of coal spontaneous combustion in the gob. The successful application of U_U-type pressure balancing ventilation system in field showed that this was an economical and effective way for controlling gas overrun in working face and preventing the coal from spontaneous combustion in the gob. It has great significance of social and economic benefits.The work contains 114 figures, 11 tables, 163 references.更多还原