煤自燃过程中自氧化加速温度研究

基于静态耗氧实验、热分析实验及红外光谱实验结果，结合煤低温氧化阶段的宏观耗氧放热规律及微观活性基团含量变化，对煤的化学动力自氧化加速温度进行了探讨。基于静态耗氧实验结果所得的活化能变化规律显示，随温度升高，煤氧复合的活化能逐渐减小，较高温度时出现负活化能，标志着煤氧复合反应进入自发反应阶段；利用补偿效应推导了等动力学温度点T iso的计算公式，得到实验煤样的T iso为127 ℃。在T iso附近，煤中还原性强的基团急剧减少而含氧基团快速增加；另用热重-差示扫描量热TG-DSC实验结果计算得到在T iso附近活化能达到最低。微观结构变化和宏观放热特征证实了计算所得T iso与煤自氧化加速点的相关性，认为可将等动力学温度点T iso视为煤从低温缓慢氧化进入自活化反应阶段的临界点，即自氧化加速温度点。

Self-accelerating oxidation temperature during the spontaneous combustion of coal

Based on the results of the static oxygen-consumption experiment， thermogravimetry-differential scanning calorimetery(TG-DSC) test and Fourier Transform Infrared Spectroscopy(FTIR) test， the self-accelerating oxidation temperature during coal’s spontaneous combustion was discussed.According to the computation results of the static oxygen-consumption experiment， the activation energy during different coal oxidation stages was calculated.The results show that the activation energy gradually reduces with the rising temperatures， and a negative value appears in the higher temperature stage， which indicates that the coal enters into the self-accelerating spontaneous reaction.The calculation formula of the isokinetic temperature point(T iso) was deduced combining with the compensation effect， and the T iso was calculated as 127 ℃ for the experimental coal sample.FTIR experiment results indicate that the microscopic deoxidizing structures reduce greatly and the oxidizing active groups swiftly increase around T iso.Moreover， according to the TG-DSC results， the lowest activation energy is also close to T iso.Therefore， from micro structures and macro heat release characteristics， the isokinetic temperature point T iso can be considered as the critical temperature， which is the self-accelerating oxidation temperature， when the coal enters into the self-activation reaction stage.