基于分布活化能模型的烟草燃烧动力学特性研究

摘要

To study the kinetic characteristics of combustion behaviors of flue-cured tobacco,the influences of stalk position of tobacco leaf,oxygen concentration and heating rate on the combustion process of flue-cured tobacco were investigated via thermogravimetric experiments,and the kinetics parameters of combustion of middle leaves were obtained by distributed activation energy model (DAEM). The results showed that:1) Within the oxygen concentration of 0-10%,the increase of oxygen concentration slightly influenced the process of volatile component evolution,but significantly improved the semi-coke combustion process of tobacco. 2) The increase of heating rate caused the mass loss profile of tobacco shifted towards a higher temperature region, it was not beneficial to the ignition and burnout of tobacco. 3) The variation curves of apparent activation energy Ea(α)along with the cause of reaction and the distribution function of activation energy f(E)of middle leaves at the oxygen concentrations of 0,5% and 10% were obtained;Ea(α)first increased and then decreased in mass loss process generally,and f(E) did not present obvious gaussian distribution characteristics. The distribution of activation energy of tobacco differed in different atmospheres,and a remarkable kinetic compensation effect was observed at the second stage (volatile non-polymeric component release and partial tobacco polymer decomposition)and the fourth stage(semi-coke combustion)of tobacco combustion process.%为研究烤烟烟叶的燃烧反应动力学特性，选取烤烟烟叶进行热重实验，考察了烟叶部位、氧气浓度和升温速率对烟叶燃烧过程的影响，利用分布活化能模型（DAEM）获得了中部烟叶燃烧动力学参数。结果表明：①在0～10%的O2浓度范围内，氧气浓度提高对挥发分的析出过程影响较小，但可显著改善烟草半焦燃烧过程。②提高升温速率会导致热滞后使得失重曲线向高温区移动，不利于着火燃尽。③获得了中部烟叶在0、5%、10%氧气浓度下表观活化能随反应进程的连续变化曲线Ea（α），以及活化能分布函数f（E）；Ea（α）随失重过程总体呈现先升后降的趋势，f（E）未呈现明显的高斯（Gaussian）分布特征；不同气氛下烟草材料活化能分布情况存在差异，在第二阶段易挥发的非聚合物组分的释放以及部分烟草聚合物初步受热分解和第四阶段半焦燃烧存在显著的动力学补偿效应。