煤干馏反应动力学的2种研究方法比较

为了深入了解COREX块煤在高温下的裂解机理,对所用块煤进行了不同温度下的高温干馏试验,确定不同温度下块煤焦油析出规律,之后分别采用混合模型法和分段法研究其干馏过程反应动力学,计算了相应的活化能和其他动力学参数.结果表明:混合模型法拟合得到3个阶段反应级数n分别为0.5、0.8、1.0,且活化能随着温度升高而增加,但由于该方法放弃反应模型物理意义,得到的只是表观活化能.分段法则根据煤干馏不同过程,确定了反应过程的机理分别为非等温收缩核、一级热解反应和分子扩散的反Jander模型,3个反应阶段的活化能分别为27.82、63.41、84.04 kJ/mol,间接地反映出块煤的裂解动力学特性,同时可为COREX熔融气化炉的数值模拟提供动力学参数.

Comparison of two investigation methods on reaction kinetics about coal dry distillation process

In order to further study the pyrolysis mechanism of coal used in COREX,the experiment of coal dry dis tillation was carried on at different temperatures and the change of tar precipitation was examined.Furthermore,the kinetics of coal dry distillations were analyzed by mixed model method and sectioning method and the activation energy Ea and other kinetic parameters were calculated respectively.The results show that the reaction orders of mechanism functions in three stages are 0.5,0.8 and 1.0 by mixed model method,and the Ea values increase with the rise of temperature.Due to this method abandoning physical meaning of reaction models,only apparent activation energy is calculated.According to coal dry distillation processes,the reaction mechanisms in three stages are determined as non-isothermal shrinking core model,first order pyrolysis reaction model and anti-Jander molecular diffusion model by sectioning method.The Ea values of the different stages are 27.82,63.41 and 84.04 kJ/mol.The results of sectioning method can not only reflect the kinetic characteristics of coal pyrolysis,but also provide kinetic parameters for the numerical simulation of COREX melting gasifier.