废弃植物中药渣的热解特性及动力学研究

Study on characteristics and kinetics of pyrolysis of herb residue

采用热重分析法（TGA）对丹参中药渣的热解特性及其动力学规律进行了研究。分析了不同升温速率（10、30和50℃/min）和不同粒径（0.85~0.6、0.3~0.18和0.125~0.1 mm）药渣的热解特性。结果表明,药渣热解可分为3个阶段：预热干燥阶段、主热解阶段和碳化阶段,随升温速率的升高,热重（TG）和微分热重（DTG）曲线向高温侧移动,药渣的最大失重速率也显著增加;与大颗粒相比较小颗粒的挥发分产量较大。采用Coats-Redfern法和Flynn-Wall-Ozawa（FWO）法对药渣热解的动力学进行分析,选出了较为合理的机理函数,并计算得出药渣热解活化能为62~72 kJ/mol。

Pyrolysis characteristics and kinetics of herb residue were investigated using thermogravimetric analyzer（TGA）.The thermogravimetric experiments were performed under the condition of different heating rates（10,30,50 ℃/min） and different particle sizes（0.85~0.6,0.3~0.18 and 0.125~0.1 mm）.The results showed that the pyrolysis of herb residue included three steps： losing water,main pyrolysis and carbonization.As the heating rate increased,the TG and DTG curves moved to the higher temperature zone and the maximum rate of weight loss increased evidently.The smaller particle size was favored to produce volatiles.The methods of Coats-Redfern and FWO were used to analyze the kinetics of the pyrolysis of herb residue,and the optimal mechanism functions were determined.The activation energy of herb residue pyrolysis was obtained as 62~72 kJ/mol.