采空区内煤自燃气体特征及产生规律分析

Analysis of gas characteristics and generation rules of coal spontaneous combustion in goaf

  • 摘要: 针对目前对在模拟逐渐升温的采空区环境条件下不同变质程度煤自燃现象的研究较少的问题,以采集的4种变质程度的焦瘦煤、气肥煤、无烟煤、肥焦煤为例,利用煤自燃模拟系统进行了煤自燃实验,研究在采空区环境条件下煤的燃烧特征及自燃气体的产生规律。实验结果表明,焦瘦煤、气肥煤、无烟煤、肥焦煤自燃时,温度会呈现“S”型上升趋势,前期温度先缓慢积累,而后开始快速升温,最后在300 ℃时趋于平衡,而后缓慢上升;不同煤样在自燃过程中均会产生碳氢化合物和碳氧化合物等挥发性气体,且生成速率受温度影响,并出现极大值和极小值2个拐点;无烟煤温度上升曲线近似于直线,气体曲线随温度波动不明显;气肥煤和肥焦煤自燃时会产生大量CO和CH4,气肥煤产生CO的速率最快,CO最大体积分数可达8%,肥焦煤产生CH4的速率最快,CH4最大体积分数可达14%,焦瘦煤和无烟煤产生的CO和CO2的体积分数分别在2%和4%左右。

     

    Abstract: At present,there are few researches on coal spontaneous combustion with different metamorphic degree under environment conditions of simulated gradually heated goaf. Taking 4 kinds of metamorphic coal samples, such as coke lean coal, gas-fat coal, anthracite coal and fat coke coal as example, the experiment of coal spontaneous combustion was carried out by using simulation system of coal spontaneous combustion to study combustion characteristics of coal and generation rules of spontaneous combustion gas under goaf environment. Experiment results show that when coke lean coal, gas-fat coal, anthracite and fat coke coal are warmed up, the temperature will rise "S" type. The early temperature will have a slow accumulation process at first and then start to heat up quickly, and finally tend to balance at 300 ℃, and then slowly rising. Different coal samples produce volatile gases such as hydrocarbons and carbon oxides during the spontaneous combustion process and the rate of formation is affected by temperature, as well as the maximum and minimum two inflection points are present. The temperature rise curve of anthracite coal is similar to a straight line, and the gas curve does not fluctuate obviously with temperature. Large amounts of CO and CH4 are produced in spontaneous combustion of gas-fat coal and fat coke coal, the rate of CO production of gas-fat coal is the fastest, the maximum volume fraction of CO can reach 8%; and the rate of CH4 production of fat coke coal is the fastest, the maximum volume fraction of CH4 can reach 14%. The volume fraction of CO and CO2 produced by coke lean coal and anthracite is about 2% and 4% respectively.

     

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