煤低温氧化动力学参数测试方法对比研究

Comparative study on test methods of coal low-temperature oxidation kinetic parameters

  • 摘要: 针对现有研究缺乏对不同煤低温氧化动力学参数测试方法的对比分析,采用Coats-Redfern法、q/m法及Starink等转化率法3种测试方法分别计算煤低温氧化动力学参数,并以煤氧化自热反应时间和自燃临界堆积厚度作为对比参量比较3种方法的准确性。通过绝热氧化装置和同步热分析仪进行了煤样在纯氧和贫氧条件下的绝热氧化实验、多升温速率实验和恒温实验。根据热分析实验结果,分别采用3种方法计算煤低温氧化动力学参数。依据获得的动力学参数计算煤氧化自热反应时间和自燃临界堆积厚度。将计算结果与实测的煤氧化自热反应时间和采空区实际遗煤厚度进行对比,评价3种方法的准确性。实验结果表明:① 通过绝热氧化实验实测的煤氧化自热温度变化率随时间的推移均逐渐增大;采用Coats-Redfern法计算得到的温度在0~8 h(q/m法为0~10 h)内几乎不发生变化,超过这一时间段后温度迅速升高;采用Starink等转化率法获得的温度变化趋势与绝热氧化实验实测结果类似。② 采空区实际遗煤厚度大于Coats-Redfern法计算得到的临界堆积厚度;采用q/m法获得的临界堆积厚度超过了该工作面所在煤层厚度,与实际明显不符;采用Starink等转化率法获得的计算结果与实际较为接近。③ 采用Starink等转化率法获得的预测结果与实测结果更为接近,表明Starink等转化率法得到的煤低温氧化动力学参数较其他2种测试方法更为准确。

     

    Abstract: In order to solve the problem of the lack of comparative analysis of different coal low-temperature oxidation kinetic parameters test methods in existing studies, three test methods, Coats-Redfern method, q/m method and Starink iso-conversional method, are used to calculate coal low-temperature oxidation kinetic parameters respectively. The accuracy of the three methods is compared with coal oxidation self-heating reaction time and critical accumulative thickness of spontaneous combustion as comparative parameters. The adiabatic oxidation experiment, the multiple heating rate experiment and the constant temperature experiment of the coal sample under pure oxygen and poor oxygen conditions are carried out through an adiabatic oxidation device and a simultaneous thermal analyzer. Based on the results of the thermal analysis experiments, three methods are used to calculate coal low-temperature oxidation kinetic parameters. The coal oxidation self-heating reaction time and the critical accumulative thickness of spontaneous combustion are calculated based on the obtained kinetic parameters. The calculated results are compared with the measured coal oxidation self-heating reaction time and the actual thickness of residual coal in goaf to evaluate the accuracy of the three methods. The experimental results show the results as follows. ① The coal oxidation self-heating temperature change rate measured by the adiabatic oxidation experiment increases gradually with the time. The temperature calculated by the Coats-Redfern method hardly changes from 0-8 h (0-10 h for the q/m method), and the temperature increases rapidly after this time period. The temperature change trend obtained by the Starink iso-conversional method is similar to the measured result of adiabatic oxidation experiment. ② The actual thickness of residual coal in goaf is greater than the critical accumulative thickness calculated by the Coats-Redfern method. The critical accumulative thickness obtained by the q/m method exceeds the thickness of the coal seam where the working face is located, which is obviously inconsistent with the actual situation. The calculation results obtained by the Starink iso-conversional method are closer to the actual situation. ③ The prediction results obtained by the Starink iso-conversional method are closer to the measured results, indicating that the low-temperature coal oxidation kinetic parameters obtained by the Starink iso-conversional method are more accurate than the other two test methods.

     

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