褐煤自燃特性热重实验及动力学分析

Thermogravimetric experiments and dynamic analysis on spontaneous combustion characteristics of lignite

对锡盟褐煤和印尼褐煤进行热重实验,并与大同烟煤、平顶山烟煤、神华低灰烟煤、阳泉无烟煤等煤样进行了对比。通过分析热重曲线,将煤从吸氧氧化到燃烧的整个过程分为物理吸附、水分蒸发失重、吸氧增重、煤受热分解、燃烧和燃尽6个阶段,并得到各阶段的特征温度点。结果表明,2种褐煤的自燃倾向明显大于其他4种烟煤和无烟煤。通过Coats-Redfern积分法研究煤样的氧化燃烧动力学特性,计算煤样的活化能,得到6种煤的氧化过程属于一级化学反应,且褐煤自燃倾向性较强;煤样粒度越小,褐煤自燃倾向性越强;随着氧气浓度的增大,煤样更易自燃。

Thermogravimetric experiments on Ximeng lignite and Indonesia lignite were carried out,and the results were compared with that of the Datong bituminous coal,Pingdingshan bituminous coal,Shenhua low ash bituminous coal and Yangquan anthracite.By analyzing the TG and DTG curves,the whole process from coal oxidation to coal combustion could be divided into six stages：physical adsorption,water evaporation with losing weight,absorption of oxygen with increasing weight,thermal decomposition,combustion and burning out.The characteristic temperatures of each stage were obtained.The results show that,the tendency of spontaneous combustion of the above two lignite was significantly obvious than that of the other four bituminous coal and anthracite.Coats-Redfern integral method was used to analyze the samples＇ oxidative combustion dynamic characteristics.Moreover,activation energy of the six coal samples was calculated to analyze the tendency of spontaneous combustion of coal.The calculation results show that,the oxidation process of the six coal samples belonged to the first-order reaction,and the tendency of spontaneous combustion of the two lignite coal was greater.The tendency of spontaneous combustion of Ximeng lignite was affected by particle size and oxygen density.Analysis shows that：the smaller the particle size,the stronger the tendency of spontaneous combustion;the greater the oxygen density,the stronger the tendency of spontaneous combustion in general.