焦炭溶损反应动力学及其模型研究

焦炭溶损反应动力学及其模型研究

  • 摘要: 利用未反应核收缩模型对高炉焦炭与CO2的反应动力学进行了研究,建立了以可测参数(R)表达的焦炭与CO2的反应动力学关系式。并对反应速率常数和有效扩散系数、表观反应活化能和有效扩散活化能及反应过程中各步骤阻力进行了分析。结果表明,(1)焦炭与CO2的反应符合未反应核收缩模型。(2)反应的表观活化能Ea=124.5kJ/mol,有效扩散活化能ED=642.4 kJ/mol;界面化学反应的阻力随反应温度升高而增加;残余灰层内的内扩散传质阻力相对比例随温度升高而下降。(3)焦炭溶损反应在低温区主要受内扩散控制,随着温度升高,反应由外扩散、化学反应和内扩散三步控制;当进入高温区,反应进行一段时间后主要受内扩散控制。

     

    Abstract: The kinetics of the reaction between coke and CO2 under the condition of blast furnace was studied by using the shrinking unreacted core model, and a relational expression of reaction kinetics was established with R, a determinable parameter. Reaction rate constant, effective diffusivity, apparent activation energy, effective diffusion activation energy and resistance in various steps of the reaction process were analyzed in this paper. The results show that the reaction of coke with CO2 is consonant with the shrinking unreacted core model, which has an apparent activation energy Ea=124.5kJ/mol, and an effective diffusion activation energy ED=642.4kJ/mol. With the increasing of reaction temperature, the resistance of surface chemical reaction increases, but the relative proportion of internal diffusion mass transfer resistance decreases in the residue ash layer. The coke reaction with CO2 is mainly controlled by the internal diffusion at lower temperatures, while with the increasing of reaction temperature, it is controlled by a combination of external diffusion, chemical reaction and internal diffusion. After a period of time at high temperatures the reaction turns to be controlled by the internal diffusion.

     

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