不同变质程度煤样氧化自燃热特性试验研究

Experimental study on thermal characteristics of coal samples with different metamorphism degree during spontaneous combustion

为探究煤在氧化自燃过程中的热特性,采用傅里叶变换红外(FTIR)光谱试验分析煤样中官能团种类和含量的差异性,结合热重分析-差式扫描量热法(TG-DSC)联用试验,分析煤样在自燃过程中失重量、放热量等参数,建立动力学方程并求解,得到煤样的活化能值E和指前因子A。研究结果表明:不同变质程度煤分子中官能团种类相似,低变质程度煤样中的羟基、脂肪烃、含氧官能团含量多于高变质程度煤样;高变质程度煤的TG、DSC曲线较低变质程度煤的曲线发生偏移出现滞后性,煤氧复合速率减缓,失重量减少,放热量增加;在增重阶段,高变质程度煤的指前因子最小;而燃烧阶段,高变质程度煤的活化能与指前因子相较于低变质程度煤均增大,发生自燃需要更多的能量。

To explore thermal characteristics of coal spontaneous combustion,different types and content of functional groups in coal samples were analyzed by FTIR.Then,parameters,such as weight loss and heat release,were analyzed based on multiple tests of TG-DSC,a kinetic equation was established and solved,and activation energy value E and pre-index factor A of samples were obtained.The results suggest that types of functional groups in coal molecules,in spite of their different metamorphism degrees,are similar.Content of hydroxyl group,aliphatic hydrocarbon and oxygen-containing functional groups in samples with low metamorphism is greater than that in those with high metamorphism,however,the latter's TG and DSC curves show deviation and hysteresis,its rate of coal oxygen recombination slows down,weight loss decreases and heat release increases.In the stage of weight gain,pre-index factor of coal with high metamorphism degree is the smallest,while in the stage of combustion,its activation energy and pre-index factor both increase,so more energy is needed for spontaneous combustion.