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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.
The thermal gravimetric tests were carried out on the same kind of coal samples under different oxygen volume fractions. The residual mass ratio (TG), mass change rate (DTG), heat release rate (DSC) and exothermic rate of change (DDSC) were used to investigate the variation of residual mass and exothermic rate under different conditions.The results show that when the volume fraction of oxygen is more than 10%, the sample can be completely annealed at the set temperature Reaction and the existence of the maximum heat release rate, but the temperature corresponding to the complete reaction increases with the decrease of the oxygen volume fraction; when the oxygen volume fraction is less than 10%, especially the oxygen volume fraction tends to 0, the coal sample is difficult to set The results show that the rate of heat release increases with the decrease of the oxygen concentration, and the rate of heat release in the experimental temperature does not fluctuate.Finally, the reasons for the different residual mass of coal samples are analyzed, The experiment results show that the critical oxygen volume fraction of spontaneous combustion of the coal is 18% and 8%, respectively, which provides guidance for the spontaneous combustion and “three zones” division of goaf.