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采空区煤体自燃温度场演变模拟试验研究

Simulation test study on temperature field evolution of coal spontaneous combustion in gob

  • 摘要: 为研究工作面采空区遗煤自燃过程中温度场的演变规律,基于几何相似原则及煤自燃原理,研发了采空区温度场分布规律相似模拟试验装置,将现场采集的大块煤样进行破碎后,选择粒径≤30 mm的混煤进行填充,设置热源和测点,模拟采空区煤自燃火源热传递过程,研究松散煤体内部温度场分布规律,热源温度对对松散煤体热量传递规律的影响以及Y型通风采空区煤体温度场分布规律。试验结果表明:无对流条件下,热源向周围煤体的热量传递呈各向同性特征,随着热源温度的增加,热源在松散煤体内的热量传递能力以非线性的形式快速增加,增速越来越大;恒温热源周围某测点的温度与恒温热源的距离和时间的关系,在测点距离或加载时间小于抛物线对称轴数值时,符合二次函数关系,在测点距离或加载时间大于抛物线对称轴数值时,测点温度基本稳定;煤自燃过程中的高温点会以加速度方式向氧气富集区域迁移,受火风压吸风效果影响,火源上部区域迁移效果更加明显。

     

    Abstract: In order to study the evolution law of temperature field during spontaneous combustion process of coal in gob of rhe working face, based on geometric similarity and the principle of coal spontaneous combustion, a similar simulation test device for the temperature field distribution in the gob was developed.After crushing the large lump coal samples collected on site, the mixed coal with particle size less than 30 mm were selected for filling. Heat sources and measuring points were set up to simulate the heat transfer process of coal spontaneous combustion in gob, and the distribution law of temperature field inside loose coal body, the effect of heat source temperature on the heat transfer law of loose coal body, and the distribution law of temperature field of Y-shaped ventilated gob were studied. The test results show that under the condition of no convection, the heat transfer from the heat source to the surrounding coal body is isotropic.With the increase of the heat source temperature, the heat transfer capacity of the heat source in the loose coal rapidly increases in a non-linear form, and increase rate is getting larger and larger. The relationship between the temperature of a measuring point around the constant temperature heat source and the distance and time of the constant temperature heat source is that, when the distance or time is less than the value of parabolic symmetry axis, it conforms to the quadratic function relationship, and when the value is greater than the value of parabolic symmetry axis, the temperature of the measuring point is basically stable. In the process of coal spontaneous combustion, the high temperature point in the spontaneous combustion process of coal will migrate to the oxygen enrichment area in an accelerated manner. Affected by the pressure and suction effect of the fire wind, the migration effect of the upper area of the fire source is more obvious.

     

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