采用热分析仪并借助等转化率的FWO法和KAS法,研究了热解温度分别为450℃,550℃,600℃,650℃,750℃时制备的半焦的燃烧特性和动力学参数,并进一步利用Malek方法对不同转化阶段活化能对应的机理函数进行了探究。结果表明:随着热解温度的升高,半焦的燃烧性能变差,燃烧所需活化能升高,在转化率(α)大于0.5时,活化能与转化率的二阶导数趋于稳定。不同转化阶段的燃烧动力学机理存在差异,转化率(α)小于0.5时,不同半焦的燃烧动力学机理均以化学反应(G(α)=(1-a)-1-1)为主,随着转化率的提高,燃烧动力学机理由随机成核和随后生长的标准机理模型(G(α)=[-ln(1-a)]23)转变为以扩散为主要限制性环节的动力学机理模型;随着热解温度的升高,半焦燃烧过程中更容易在较低转化率时转化为以扩散为主要的限制性环节。

The combustion characteristics and kinetic parameters of semi-cokes prepared at  different pyrolysis temperatures were studied by a thermal analyzer via Flynn-Wall-Ozawa (FWO)  and Kissinger-Akah-Sunose (KAS) methods.  Furthermore, the Malek method was used to explore  the mechanism functions corresponding to activation energy at different conversion stages.  The results  indicate that increasing pyrolysis temperature deteriorates the combustion performance of semi-coke  and increases the energy consumption.  When conversion α>0. 5, the second derivative of activation  energy and conversion tends to stabilize.  There are differences in combustion dynamic mechanisms at  different conversion stages.  When α <0. 5, the combustion dynamic mechanism of semi-cokes is  mainly chemical reactions ( G ( α )= 1 - a  - 1 ).  As the conversion increases, the combustion  dynamic mechanism changes from a standard mechanism model of random nucleation and nuclei  growth ( G ( α )=  - ln (1 - α ) ) to a dynamic mechanism model with diffusion as the main restric‐ tive step.  In addition, with the increase of pyrolysis temperature, semi-coke is more likely to be trans‐ formed into a restrictive step dominated by diffusion at lower conversions.