Mathematical modeling of char reactivity in Ar-O-2 and CO2-O-2 mixtures
Mathematical modeling of char reactivity in Ar-O-2 and CO2-O-2 mixtures
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DOI：
10.1021/ef950252z
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发表时间：
1996-11-01
期刊：
影响因子：
5.3
通讯作者：
Richard, JR
中科院分区：
文献类型：
--
作者：
Varhegyi, G;Szabo, P;Richard, JR
用热重法研究了煤焦+ O-2反应的动力学。采用低样品质量以确保近似的动力学状态。特别强调的是，澄清如何再循环的烟道气（即存在大量的CO2在低O-2浓度）影响的反应性。环境气体浓度在CO2或Ar中从100%O-2变化到5%O-2。一个半经验模型，可以近似的反应性变化在转换过程中，并考虑到样品的异质性。一个最小二乘评估程序导致在一个很好的适合在各种各样的温度程序和环境气体浓度的实验数据。根据实验条件，样品的总燃尽时间从8分钟到3小时不等。发现反应速率与环境气体的O-2浓度成正比，并且不受大量CO2存在的影响。反应开始时有一个急剧的加速期，表明炭表面的初始活化。
The kinetics of the coal char + O-2 reaction was studied by thermogravimetry. Low sample masses were employed to ensure an approximate kinetic regime. Special emphasis was placed on clarifying how the recirculation of the flue gases (i.e. the presence of a high amount of CO2 at low O-2 concentrations) affects the reactivity. The ambient gas concentrations varied from 100% O-2 to 5% O-2 in CO2 or Ar. A semiempirical model is presented that can approximate the reactivity changes during the conversion and takes into account the heterogeneity of the samples. A least-squares evaluation procedure resulted in a good fit to the experimental data over a wide variety of temperature programs and ambient gas concentrations. The overall burn-off time of the samples varied from 8 min to 3 h depending on the experimental conditions. The reaction rate was found to be proportional to the O-2 concentration of the ambient gas and was not influenced by the presence of high amounts of CO2. The reaction started with a sharp acceleration period, indicating an initial activation of the char surface.