不同自燃性煤氧化阶段的表征差异

对3种不同自燃倾向性煤样进行低温氧化实验,利用CO体积分数与煤体温度间变化的计算模型,求解出活化能和煤氧化过程发生转变的特征温度,同时结合热重-差示扫描量热(TGDSC,theremogravimetric analysis-differential scanning calorimetry)实验结果,分析了不同自燃性煤氧化特性和活化能的低温表征规律。结果表明:1)低温氧化阶段,CO生成量、耗氧量和耗氧速率随着煤自燃倾向性增强而增大;不同煤样在实验过程中出现同样的CO生成量和耗氧速率急剧上升的温度拐点,且煤的自燃性越强,该拐点温度越低,同时CO体积分数的变化具有明显的阶段性。2)不同自燃性煤氧化阶段活化能变化规律存在显著差异,当各煤样的温度到达活性温度时,活化能快速减少,且活化能变化点对应于煤氧化过程发生转变的特征温度点。3)根据煤特征温度和活化能的变化规律,把煤低温氧化进程分为4个阶段,分别为表面氧化、氧化自热、加速氧化和深度氧化。

Characterization difference of coals with different spontaneouscombustion tendencies during oxidation stage

Low temperature oxidation experiments of three coal samples with different spontaneous combustion tendencies were carried out. Activation energies and characteristic temperatures of coal oxidation process conversion were obtained by the computational model based on the relationship between CO volume fraction and coal temperature change. With the experimental results of TG-DSC(theremogravimetric analysis-differential scanning calorimetry), the change laws of activation energy and oxidation characteristics of three coal samples in low temperature were analyzed. The results show that 1) during the low temperature oxidation, the CO generation amount, the oxygen consumption amount and the oxygen consumption rate increase with the enhancement of spontaneous combustion tendency. Temperature inflections that CO generation amount and oxygen consumption rate increase sharply are the same during the experiment of different coal samples. And the stronger the spontaneous combustion is, the lower the temperature inflection is, and the change of CO volume fraction shows obvious stages. 2) The change laws of activation energy of coals with different spontaneous combustion tendencies are significantly different. When coal temperature reaches the active temperature, activation energy decreases rapidly, and the mutation points of activation energy are corresponding to the conversion characteristic temperatures in coal oxidation process. 3) According to the characteristic temperature and the change law of activation energy, the low temperature oxidation process could be divided into four stages, namely surface oxidation, thermal oxidation, accelerated oxidation and deep oxidation.