焦油渣热解和动力学分析

Pyrolysis and kinetic analysis of tar residue

以焦油渣为原料,利用热重-红外联用(TG-IR)仪在氮气气氛下考察不同升温速率对焦油渣热解的影响规律,基于Friedman理论、DAEM理论以及OFW理论对焦油渣热解动力学参数进行计算、分析对比。结果表明,焦油渣热解过程可以分为3个阶段:失水脱气阶段、主要热解阶段、缩聚反应阶段。随着升温速率的提高,热解产率增加,第二阶段的DTG曲线峰值对应温度降低,第三阶段的DTG曲线峰值则向高温区移动。通过红外分析研究了热解过程小分子气相产物的释放规律,CO和CO_(2)在640℃达到析出量峰值,CH_(4)则分别在173、370、590℃处有3个峰值;焦油渣热解反应活化能随着转化率升高出现先降低后增加的趋势;基于Friedman法计算,热解过程可分为低温、中温和高温3个阶段,对应的平均活化能分别为44.59、27.76、170.69 kJ/mol。

Using tar residue as experimental raw material,the effects of different heating rates on tar residue pyrolysis are investigated by means of thermogravimetry infrared(TG-IR)in nitrogen atmosphere.Based on Friedman theory,DAEM theory and OFW theory,the pyrolysis kinetic parameters of tar residue are calculated,analyzed and compared.The results show that the pyrolysis process of tar residue can be divided into three stages:dehydration and degassing stage,main pyrolysis stage and polycondensation reaction stage.With the increase of heating rate,the pyrolysis yield increases,the peak value of DTG curve in the second stage decreases corresponding to the temperature,and the peak value of DTG curve in the third stage moves to the high temperature zone.The release law of small molecular gas products(CO,CO_(2)and CH_(4))during pyrolysis is studied by means of infrared analysis.Both CO and CO_(2)reach their peak values of precipitation amount at 640℃,while the precipitation amount of CH_(4)has three peaks at 173℃,370℃and 590℃,respectively.The activation energy of tar residue pyrolysis reaction decreases first and increases then with the increase of conversion.Based on Friedman method,the pyrolysis process can be divided into three stages:low temperature,medium temperature and high temperature,with the corresponding average activation energy of 44.59,27.76 and 170.69 kJ·mol^(-1)respectively.