空气湿度对煤自燃特性及氧化动力学参数的影响研究

    Research on the influence of air humidity on coal spontaneous combustion characteristics and oxidation kinetics parameters

    • 摘要: 空气湿度对矿井煤自燃过程具有重要影响,为了研究空气湿度对煤自然氧化特性及氧化动力学参数的影响特征,选取文家坡煤矿4105综放工作面煤样开展程序升温实验研究,分析不同空气湿度条件下煤样氧化自燃特性,并构建公式根据耗氧速率计算不同氧化阶段的表观活化能及指前因子。结果表明:不同空气湿度条件下,CO气体和耗氧速率随温度升高均呈现出指数型增长趋势,C2H4气体是煤高温热解的产物,在90 °C以后才开始出现,文家坡煤矿煤样的临界温度为60~80 °C,干裂温度为100~120 °C;通过临界温度前后煤氧化动力学参数计算,煤样的表观活化能随着空气湿度的增大逐渐减小,当空气湿度超过60%以后,表观活化能又逐渐增大,且指前因子表现出类似的规律,说明煤自燃过程存在临界湿度,该湿度对煤自燃起到一定的促进作用,在该环境下煤样更加容易自燃。

       

      Abstract: Air humidity has an important impact on the spontaneous combustion process of coal in mines. In order to study the influence characteristics of air humidity on the natural oxidation characteristics and oxidation kinetics parameters of coal, a programmed heating experiment was conducted on coal samples from 4105 fully mechanized caving face of Wenjiapo Coal Mine. The oxidation spontaneous combustion characteristics of coal samples were analyzed under different air humidity conditions, and a formula was constructed to calculate the apparent activation energy and pre-exponential factor of different oxidation stages based on the oxygen consumption rate. The research results indicate that under different air humidity conditions, CO gas and oxygen consumption rate both exhibit an exponential growth trend with increasing temperature. C2H4 gas is a product of coal high-temperature pyrolysis and only appears after 90 °C. The critical temperature of coal samples in Wenjiapo Coal Mine is 60-80 °C, and the dry-cracking temperature is 100-120 °C. By calculating the coal oxidation kinetics parameters before and after the critical temperature, the apparent activation energy of the coal sample gradually decreases with the increase of air humidity. When the air humidity exceeds 60%, the apparent activation energy gradually increases, and the pre-exponential factor shows a similar pattern, indicating that the coal spontaneous combustion process exists in the critical humidity, which plays a certain promoting role in coal spontaneous combustion, and the coal sample is more prone to spontaneous combustion in this environment.

       

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