竹材热解动力学特性分析

Study on Pyrolysis Kinetics of Bamboo

采用热重分析法研究了氮气气氛下竹材的热解行为及其动力学特性,分析了升温速率和粒径对竹材热解过程及动力学参数的影响.结果表明,竹材热解分为干燥、预热解、热解和缓慢热解4个阶段;升温速率对竹材的热失重特性有显著影响,当升温速率从40℃/min增加到100℃/min时,竹材热解出现了滞后现象,热解活化能从130.87 k J/mol下降到73.85 k J/mol,频率因子及反应级数单调减小;不同升温速率下计算的活化能和频率因子之间存在良好的补偿效应;当粒径大于380μm时,竹材的热解不仅受动力学控制,受颗粒传热、传质影响也较大.

Kinetic study on bamboo pyrolysis was conducted with a thermogravimetric analyzer under nitrogen condition. The effects of heating rate and particle size on the pyrolysis process were examined. The results showed that the pyrolysis process of bamboo included four stages, drying, pre-pyrolysis, rapid pyrolysis and slow pyrolysis. Heating rate had a significant effect on the bamboo pyrolysis. With the increase of heating rate from 40 to 100 ℃/min, both the maximum and average reaction rates increased, and the decomposition reaction was postponed to a higher temperature. The values of kinetic parameters calculated from the main reaction regimes decreased from 130.87 to 73.85 k J/mol. A kinetic compensation effect was observed between the values of natural logarithm of frequency factor and activation energy. The pyrolysis process of bamboo was controlled by not only kinetics, but also heat and mass transfer within the particles with the sizes larger than 380 μm.