基于热重实验的煤自燃临界氧体积分数分析

对同一种煤样在不同氧体积分数下进行热重实验,利用Matlab得出了该煤样的残留质量比率(TG),质量变化率(DTG),放热速率(DSC)和放热变化率(DDSC)的立体分布和等值线图,研究了不同条件下残留质量和放热速率的变化规律.结果显示,当氧体积分数大于10%时,该煤样在设定的温度内能完全反应和存在最大放热速率,但完全反应对应的温度随着氧体积分数的降低而升高;当氧体积分数小于10%时,尤其是氧体积分数趋向于0时,该煤样难以在设定的温度范围内完全反应,且残留质量随氧体积分数的降低加速上升,同时在实验温度段内放热速率波动不大.最后,对煤样产生不同残留质量的原因进行了分析,结合热重实验得出该煤自燃的临界氧体积分数为18%和8%,从而为采空区自燃"三带"划分提供指导.

Thermogravimetric determination of the critical oxygen volume fraction for spontaneous combustion of coal

Thermogravimetric experiments were conducted on identical coal samples under different volume fractions of oxygen.The residual mass and heat release rate under the different conditions was determined.Graphics produced by Matlab were used to display the TG,DTG,DSC,and DDSC data.The data shows that volume fractions of oxygen greater than ten percent result in completed reaction and greatest heat release rate at a given temperature.In this regime the temperature at completion of the reaction increases with decreasing oxygen volume fraction.When the oxygen volume fraction is less than ten percent,especially when the oxygen volume fraction is close to zero,the reaction does not go to completion and the residual weight increases as the oxygen content drops.At the same time,the heat release rate has a little change in this regime.The reason for different residual masses of the coal samples was analyzed.The critical oxygen volume fraction for spontaneous combustion of this coal was found to be eight and eighteen percent.This result can guide spontaneous combustion "three-zone" division in goaf.