生物质热反应机理特性研究

STUDY ON THE BIOMASS THERMO REACTIVITY MECHANISM

通过对不同生物质在热解以及不同氧含量下燃烧过程的研究，详细探讨了生物质热反应机理。将OZAWA分析方法和动力学分析法结合，计算得到固体样品在热反应过程中的活化能分布特征，进而确定所对应的动力学反应机理。通过对纤维素热解过程的分析证明该方法的准确性，并对不同生物质在不同条件下热反应过程进行全面分析。结果表明，热反应过程可以分为两个阶段，第一阶段为挥发份释放阶段，动力学基本上符合R2即三维随机成核和核增长（除棉杆在N2：O2=54：1条件下的反应）；第二阶段为焦反应阶段，动力学机理变化较大，而该变化与颗粒相的结构有关，其动力学特征可以归纳为（1-a）^m，n的取值与颗粒结构特性相关。

Different thermal reactions of several biomasses were described in this paper to study the thermal reaction mechanism of biomasses. A new method combined the OZAWA method with mechanism analysis was used to calculate activation energy distribution and decided the different thermal reactions mechanism of. Cellulose pyrolysis was analyzed by this method and the analytical results show a satisfied precision. Different biomasses, such as rice husk, rice straw and cotton straw, were chose to study thermal reactions with different oxygen contents. The results show that thermal reaction can be divided into two parts. The first part of thermal reactions is release process of the volatiles. The dynamics in the first part coincides with the mechanism R2 which is three-dimension Randon nucleation and nuclei growth （except one condition, cotton straw combustion under N2：O2=54：1 atmosphere）. The second part is char reaction process. The mechanisms of this part changes obviously. This kind of change is caused by physical structure of char particle. The mechanism of this part could be expressed by （ 1 - a ）^n, n is related with physical structure of char particle.