基于TG-MS研究不同升温速率下褐煤热解气体产物析出特性及其动力学参数

Study on releasing characteristics of pyrolysis gas products and kinetic analysis of lignite pyrolysis at different heating rates based on TG-MS

为研究褐煤热解特性及动力学参数分布规律,采用热重质谱联用分析仪(TG-MS)对锡林郭勒褐煤进行不同升温速率下的热解实验,研究了不同升温速率下煤样的热失重规律、CO和H_2析出过程的变化规律,并对热解气体产物热值及未冷凝气体效率进行了计算。实验结果表明:煤样热解初始阶段,不同升温速率下水分析出速率相等,与热解升温速率关系不大。随着热解时间延长,煤样的质量逐渐降低。不同升温速率下热解煤样最终残留质量相差不大,平均剩余为6.51mg。热解转化率较小时,活化能E值较大,指前因子A较高。随着热解转化率的逐渐增大,反应活化能呈现降低趋势,这表明随着热解温度的升高,煤中分子吸收能量后克服反应势垒差值降低,热解反应速率增大。CO和H_2释放过程可大致分为三个阶段,且析出峰温随着升温速率增大向高温段移动。热解气体产物热值和未冷凝气体效率呈波浪状变化趋势。

In order to investigate the pyrolysis characteristics and the distribution of gas phase product of lignite,pyrolysis experiments at different heating rates were carried out with a thermogravimetric mass spectrometry（ TG-MS）,and the weight loss of coal samples at different heating rates,the change of release process of CO and H_2,and the calorific value of the pyrolysis gas and the cold gas efficiency were explored and calculated. Research results show that the release rate of water vapor at different heating rates is equal,which is not related to the pyrolysis heating rate. The mass of coal sample decreases gradually with the increase of pyrolysis time. At different heating rates,the final residual mass of pyrolysis coal samples is different,and the average remaining mass is 6. 51 mg. When the pyrolysis conversion is small,the activation energy E value is larger,and the pre exponential factor A is higher. With the increasing of the pyrolysis conversion rate,the activation energy decreased,which indicates that with the increase of pyrolysis temperature,coal molecular absorption energy to overcome the reaction barrier difference decreases,the pyrolysis rate increases. The release of CO and H_2 can be divided into three stages,and the release peak temperature moves to the high temperature with the increase of heating rate.The calorific value of gas product and cold gas efficiency exhibits a wavelike trend.