森林腐殖质热解动力学模型对比与分析

Comparison and analysis of kinetic models ofpyrolysis of forest humus

林火是对森林资源破坏十分严重的一种自然灾害,一旦引发,会在森林中快速蔓延且不易扑灭,因此对林地内可燃物的热解特性进行研究分析有十分重要的现实意义。本文以帽儿山人工阔叶红松林内的腐殖质为研究对象,利用TG-DTG曲线分析腐殖质的热解过程。试验数据采用Coats-Redfern(CR)法、Doyle法、Flynn-Wall-Ozawa(F-W-O)法、分布活化能模型(DAEM)4种典型方程进行动力学模型分析,分别计算反应活化能、反应级数和频率因子。试验结果表明:腐殖质的热解主要分为4个阶段:脱水阶段、过渡阶段、主要失重阶段和炭化阶段。对主要失重阶段的动力学参数进行计算,结果显示,Doyle法和DAEM模型较其他2种方程更适合腐殖质的热解动力学分析。其中DAEM模型适合分析样品活化能的变化趋势,Doyle法适合求取不同失重率下的活化能。

Forest fire is a natural disaster that damages forest re-sources seriously,and once started,it spreads rapidly in the for-est and is not easy to be extinguished.Therefore,it is of great practical importance to study and analyze the pyrolysis charac-teristics of combustible materials in the forest.In this paper,we analyzed the pyrolysis process of humus using TG-DTG curves in an artificial broad-leaved red pine forest in Mao'er Mountain.The experimental data were analyzed using Coats-Redfern(CR)method,Doyle method,Flynn-Wall-Ozawa(F-W-O)method,and four typical equations of distributed activation energy mod-el(DAEM)for kinetic modeling,and the reaction activation en-ergy,reaction level and frequency factor were calculated respec-tively.The experimental results showed that the pyrolysis of hu-mus was mainly divided into four stages:dehydration stage,transition stage,major weight loss stage and carbonization stage.The kinetic parameters of the major weight loss stages were calculated,and the results showed that the Doyle method and the DAEM model were more suitable for the kinetic analy-sis of the pyrolysis of humic substances than the other two equa-tions.Among them,the DAEM model is suitable for analyzing the trend of activation energy of samples,and the Doyle method is suitable for finding the activation energy at different weight loss rates.