【作者】 封华；

【导师】 文虎；

【作者基本信息】 西安科技大学 ， 矿业工程， 2010， 硕士

【摘要】 我国许多矿井都开采高瓦斯易自燃煤层,煤层自燃和瓦斯灾害都十分严重。高瓦斯矿井抽放条件下采空区漏风规律与无抽放的低瓦斯矿井有很大区别,采空区自燃危险区域的分布规律也更加复杂,这种条件下的自燃预测问题目前还没有完全解决。本论文开展了下石节煤样自然发火实验,真实地模拟了煤样从常温至380℃以上煤自燃的全过程。实验得到下石节矿煤样自然发火期和特征温度,分析了自燃指标气体及氧化放热强度随温度变化规律,煤自燃的下限氧浓度、上限漏风强度、极限浮煤厚度等参数。建立了高瓦斯煤矿瓦斯抽放条件下,采空区渗流、扩散、吸附与脱附、化学反应等多场耦合的数学模型,将采空区流场与浓度场的数值模拟和自燃危险区域判定理论相结合,实现了高瓦斯易自燃煤层抽放条件下采空区自燃危险区域判定和预测。对下石节煤矿215工作面研究表明:(1)瓦斯抽放后,在抽放口处漏风强度最大,在回风侧相对比进风侧大,采空区氧气浓度在距工作面较近处较高,距离工作面越远则氧气浓度越低,在抽放口附近氧气浓度有所降低;(2)在工作面进风侧距离煤柱约5m附近氧化升温带宽度最大,该处窒熄带深度约85m,散热带深度约15m,即对应氧化升温带宽度约70m;(3)采空区可能发生自燃的工作面极限推进速度为1.6m/d,当采煤工作面的推进速度大于1.6m/d时,采空区无自然发火危险;当工作面连续超过45d推进速度均小于1.6m/d,采空区将有自然发火危险。论文对指导煤自燃防治有重要意义。更多还原

【Abstract】 Many coalmines in China are high-methane spontaneous combustion ones, where spontaneous combustion are quite serious. Due to gas extraction, air leakage in the gob of high-methane mines is different from those in low-methane mines , which caused spontaneous combustion in the high-methane mine very complicated and difficult to predict. In the present study, spontaneous combustion modeling experiment is carried out to model the whole process of Xiashijie coal spontaneous combustion from room temperature to over 380 degree centigrade. Character temperature including index gases, critic loose coal depth, critic air leakage intensity and critic oxygen concentration of coal spontaneous combustion are tested with the experiment.A couped numeric model of flow, diffusion, absorption and desorption as well as chemical reaction is set up to to simulate the field of air concentration and flux. The spontaneous combustion danger zone and possible time is determined with the simulation result and the theory of spontaneous combustion patition. It proved that in the 215 workface of Xiashijie coalmine, (1) the largest air leakage spot is near the gas extraction port, and air leakage intensity in thr air outlet side of the workface is larger than air inlet one, the farther it is from the workface, the smaller the oxygen concentration is except that near gas extraction port where oxygen concentration is lower; (2) self-heating zone near the air inlet side of the gob is of the widest, where the boundary of choking zone is 85m away from the workface, of the heat dissipation zone is 15m away, and the width of self-heating zone is 70m; (3) the critic workface movement velocity of spontaneous combustion is 1.6m/d, which means when the velocity is larger than 1.6m/d, there is no danger of coal spontaneous combustion in the gob; nevertheless, spontaneous combustion may take place when the velocity of workface movement is smaller than 1.6m/d for 45d continuously. The study is very important for theoretical instruction of prevention and fathering spontaneous combustion in high-methane coalmine on comdition of gas extraction.更多还原