高温烟气干燥后褐煤的自燃特性

Self-combustion Characteristics of Lignite After Dried by High Temperature Flue Gases

运用热重分析仪对原煤及经不同温度干燥处理的煤样进行自燃特性研究,得到了各煤样的自燃特征温度点,并依据温度点对煤样的转化过程进行了划分。最后,采用Coats-Redfern积分法对各煤样在不同阶段的动力学参数进行求解,并选取吸氧增重阶段的活化能作为自燃倾向性的指标。结果表明:整个燃烧过程可以分为失水失重、吸氧增重和燃烧失重3个阶段;高温模拟烟气干燥条件下烟气温度增加对干燥后所得煤样的吸氧增重和着火燃烧没有太大的影响;高温干燥后煤样的着火活化能升高,煤样不易自燃。

By using a thermogravimetric analyzer,studied were the self-combustion characteristics of raw coal and various coal samples which had been subjected to a drying process at different temperatures and the self-ignition characteristic temperature points of various coal samples were obtained. On the basis of these temperature points,the conversion processes of the coal samples were divided. Finally,by using the Coats-Redfern integration method,the solutions to the kinetic parameters of various coal samples in different stages were sought and the activated energy in the oxygeninhaling and weight-adding stages was chosen as an index indicating a self-ignition tendency. It has been found that the whole combustion process can be divided into three stages: water losing and weight losing stage,oxygen-inhaling and weight-adding stage and combustion-caused weight-losing stage. Under the condition of the drying process by high temperature flue gases simulated,to increase the flue gas temperature has no big influence on the oxygen-inhaling and weight-adding,ignition and combustion of coal samples obtained after the drying process. The coal samples after the high temperature drying process has a higher ignition activated energy and the coal samples are not easy to perform its self-ignition.