大倾角易自燃煤层综放开采自燃防治技术研究

发布时间：2018-10-25 20:41

【摘要】：煤矿自燃火灾次数占火灾总次数的90%以上,其中80%的自燃火灾发生在厚煤层中,在中国大倾角煤层储量约占煤炭总储量的14.05%,大倾角厚煤层自燃防治问题更为严峻。古山矿所含煤层为极易自燃煤层,065-2综放工作面是大倾角易自燃厚煤层综放开采工作面,受老火区影响严重,自然倾向性增强,发火期缩短,老火区复燃和回采工作面与邻近小煤窑老火区贯通而引起开采层自燃的比例高,发生发展速度较快,自燃防治难度大。针对不同开采阶段结合现场实际,采用现场测试、实验室实验、理论分析(数值模拟)以及工程应用相结合的方法,主要进行的工作和取得的成果如下：(1.)通过现场取样、室内热重实验、光谱特性实验等,研究平庄矿区古山矿煤体的自燃特性及指标气体产生规律,开展了不同配比阻化泡沫对不同煤样阻化效果实验,得出泡沫与水的体积比1：2为最佳配比,对提高煤的着火点温度及活化能都是最有利的。(2)通过065-2大倾角综放工作面采空区气体、温度现场监测和数值模拟研究,指出大倾角综放工作面采空区在氧气浓度分布、温度分布、风流速度分布、氧化带分布等方面和近水平及缓倾斜综放工作面采空区分布具有明显区别,得到大倾角综放工作面采空区自燃危险区域分布特征。(3)使用COMSOL Multiphysics 4.3b2D数值模拟软件,通过数值模拟,指出工作面风量变化的敏感反映指标是氧化带终止边界深入采空区的距离和采空区的最大风流速度,注氮时间和氧化带宽度之间具有近似“Z”字型的Boltzmann关系,提出了连续注氮存在最低有效作用时间和最大效率注氮时间。(4)采用数值解算方法,从隔离墙长度、间距、道数三个方面对采用砌筑隔离墙调控采空区风流结构的效果进行对比研究,得到不同风流结构调控技术参数与采空区氧化带宽度的定量关系和砌筑隔离墙的有效保护范围,提出结合有效保护距离、近似“√.”型关系及工程量和现场实际选择隔离墙参数的方法。(5)通过数值模拟,揭示了分阶段放顶煤采空区风流矢量和自燃危险区域的定量变化规律,指出分阶段放顶煤能够显著改变采空区内风流方向、降低风流速度和危险区域范围,对火区影响下大倾角易自燃综放工作面安全穿越老火区具有重要作用和意义。(6)提出加强采空区及老火区监测及封堵漏风、合理控制或降低风量、在有效时间基础上开展注氮并缩短注氮步距、在有效保护距离内适当长度的砌筑隔离墙并加密、加强老火区超前探测及采前和采中综合治理、加固顶板及巷帮保证灌注凝胶和泡沫阻化剂的密封性并缩短管路错距和多孔大量喷射阻化泡沫、分阶段放顶煤自燃综合防治技术方案,成功实现了火区影响下大倾角特厚易自燃煤层综放工作面的安全、高效生产。
[Abstract]:The number of spontaneous combustion in coal mines accounts for more than 90% of the total number of fires, in which 80% of the spontaneous fires occur in thick coal beds. In China, the reserves of large inclined coal seams account for about 14.05% of the total coal reserves. The prevention and treatment of spontaneous combustion in large inclined and thick coal seams is more serious. The coal bed contained in Gushan Mine is easily spontaneous combustion coal seam. 065-2 fully mechanized caving face is a fully mechanized caving mining face with large inclination and easy spontaneous combustion thick seam. It is seriously affected by the old fire area, the natural tendency is enhanced, and the ignition period is shortened. The rate of spontaneous combustion of mining bed is high, the speed of occurrence and development is relatively fast, and the prevention and control of spontaneous combustion is very difficult because of the high proportion of spontaneous combustion in the old fire area and the connection between the working face and the old fire area adjacent to the small coal mine. According to different mining stages combined with field practice, the methods of field test, laboratory experiment, theoretical analysis (numerical simulation) and engineering application are adopted. The main work and results are as follows: (1) Through field sampling, indoor thermogravimetric test and spectrum characteristic experiment, the spontaneous combustion characteristics and index gas production of coal body in Gushan Coal Mine in Pingzhuang mining area were studied. It is obtained that the optimum ratio of foam to water volume is 1:2, which is the most favorable to increase the ignition temperature and activation energy of coal. (2) through the gas field monitoring and numerical simulation study of gas in goaf of 065-2 fully mechanized caving face with large inclination angle, It is pointed out that the distribution of oxygen concentration, temperature, air flow velocity and oxidation zone in the goaf of fully mechanized caving face with large inclination is obviously different from that in the near level and gently inclined fully mechanized caving face. The distribution characteristics of spontaneous combustion danger area in goaf of fully mechanized caving face with large inclination are obtained. (3) using COMSOL Multiphysics 4.3b2D numerical simulation software, through numerical simulation, It is pointed out that the sensitive index of the change of air volume in the face is the distance from the end of the oxidation zone to the goaf and the maximum air flow velocity of the goaf, and the Boltzmann relationship between the nitrogen injection time and the width of the oxidation zone is similar to that of "Z". The minimum effective time and maximum efficiency time for continuous nitrogen injection are proposed. (4) numerical method is used to calculate the length and spacing of the separation wall. This paper makes a comparative study on the effect of using the masonry wall to control the air-flow structure of goaf in three aspects, and obtains the quantitative relationship between the technical parameters of the air-flow structure and the width of the oxidation zone of the goaf and the effective protection range of the masonry wall. Proposed to combine effective protection distance, approximate "square." (5) through numerical simulation, the paper reveals the quantitative variation law of air flow vector and spontaneous combustion danger area in the goaf of coal caving in different stages. It is pointed out that stage top coal caving can significantly change the direction of air flow in goaf and reduce the velocity of air flow and the range of dangerous area. Under the influence of fire area, it is of great importance and significance for fully mechanized caving face with large inclined angle to pass through the old fire area safely. (6) it is proposed to strengthen the monitoring of goaf and old fire area and to block the air leakage, and to control or reduce the air volume reasonably. On the basis of effective time, nitrogen injection should be carried out and the step distance of nitrogen injection should be shortened. The construction and encryption of the wall with appropriate length within the effective protection distance should be carried out, so as to strengthen the advance detection of the old fire area and the comprehensive control before and in mining. To strengthen roof and roadway to ensure the sealing property of pouring gel and foam inhibitor, to shorten the misalignment of pipes and a large amount of porous spray foam, and to prevent and cure the spontaneous combustion of coal caving in stages. The safety and high efficiency production of fully mechanized caving face with large dip angle and high thickness spontaneous combustion coal seam has been realized successfully under the influence of fire area.
【学位授予单位】：辽宁工程技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TD752.2

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