玉米秸秆热解特性及动力学分析

以玉米秸秆为原料, 利用热重分析法研究其热解的特性及动力学。根据TG和DTG曲线, 研究玉米秸秆的热解特性, 采用Flynn-Wall-Ozawa(FWO)和Kissinger-Akahira-Sunose(KAS)两种等转化率法计算玉米秸秆热解的活化能, 并结合主曲线法和Coats-Redfern(C-R)法探讨了玉米秸秆热解遵循的机理方程。研究结果表明: 玉米秸秆热解过程可分为干燥脱水、过渡、主热解和炭化4个阶段, 随着热解升温速率增大, TG和DTG曲线向高温侧偏移; 利用FWO和KAS法计算得到的表观活化能分别为181.7和181.5 kJ/mol; 利用主曲线法和C-R法求解出玉米秸秆热解的机理方程遵循Avrami-Erofeev方程, 当α=0.1~0.5时, n=3, f(α)=1/3(1-α)-ln(1-α)]^-2; 当α=0.5~0.7时, n=2, f(α)=1/2(1-α)-ln(1-α)]^-1。

Pyrolysis Characteristics and Kinetic Analysis of Corn Straw

Using corn straw as raw material, the characteristics and kinetics of its pyrolysis were studied by TG. The physicochemical properties of corn straw before and after pyrolysis were analzed according to the TG and DTG curves. Activation energy of corn straw pyrolysis were calculated using the isoconversional models of Flynn-Wall-Ozawa(FWO) and Kissinger-Akahira-Sunose(KAS), and the thermal degradation mechanism was investigated by the master-plot and Coats-Redfern(C-R) methods. The results showed that the pyrolysis process of corn straw could be divided into 4 stages: drying dehydration stage, transition stage, main pyrolysis stage, and carbonization stage. The pyrolysis curve shifted to the high temperature side with the increasing heating rate. The apparent activation energies calculated by FWO and KAS were 181.7 and 181.5 kJ/mol, respectively. The pyrolysis mechanism equation of corn straw was calculated using the master-plot method and C-R method, which follows Avrami-Erofeev equation. When α=0.1-0.5, n=3, f(α)=1/3(1-α)-ln(1-α)]^-2, and when α=0.5-0.7, n=2, f(α)=1/2(1-α)-ln(1-α)]^-1.