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A hierarchical approach to chemical reactor engineering: an application to micro packed bed reactors†
Reaction Chemistry & Engineering ( IF 3.9 ) Pub Date : 2018-01-08 00:00:00 , DOI: 10.1039/c7re00195a
Stefano Rebughini 1, 2, 3, 4, 5 , Mauro Bracconi 1, 2, 3, 4, 5 , Anthony G. Dixon 6, 7, 8, 9 , Matteo Maestri 1, 2, 3, 4, 5
Affiliation  

Hierarchical modeling is applied for the investigation of micro packed bed reactors. This method allows for the use of Computational Fluid Dynamics (CFD) simulations in the analysis of representative complex geometries, where a full-scale CFD simulation of the entire reactor is not possible. Detailed and computationally demanding analyses are used to study a selected number of conditions and phenomena. Then, lumped parameters are derived from CFD results by means of engineering correlations. These parameters are incorporated in simplified reactor models based on macroscopic conservation equations. We provide evidence for the potential of the approach by using as a show-case a micro packed bed reactor in the context of highly exothermic selective oxidation processes. This reactor configuration consists of catalytic particles packed in the channels of a honeycomb matrix, which is expected to strongly enhance the radial heat transfer. In particular, we first focus on the analysis of energy transfer mechanisms by CFD and their interpretation via a 1D model and we provide an assessment of existing correlations with respect to the unconventional configuration (2 mm channel equivalent diameter and 0.8 mm sphere diameter). These correlations are then implemented in a pseudo-continuous (i.e. macroscopic) 2D model to allow for a systematic investigation of the capabilities of the micro packed bed reactor in dealing with the selective oxidation of o-xylene to phthalic anhydride. We found that due to the enhanced radial heat transfer micro packed bed reactors allow for quasi-isothermal operations, thus extending the range of operating conditions possible without occurring in adverse thermal behavior of the reactor. On a more general basis, we prove that the hierarchical approach to chemical reactor engineering is an effective tool to bring the application of fundamental modeling at a level of complexity relevant to full-scale applications, otherwise not possible because of the impractical computational costs.

中文翻译:

化学反应器工程的分层方法:在微型填充床反应器中的应用

分层建模用于研究微型填充床反应器。这种方法允许在代表性的复杂几何形状的分析中使用计算流体动力学(CFD)模拟,而无法对整个反应器进行全面的CFD模拟。详细且计算量大的分析用于研究选定数量的条件和现象。然后,通过工程相关性从CFD结果中得出集总参数。这些参数被并入基于宏观守恒方程式的简化反应器模型中。我们通过在高放热选择性氧化过程中使用微型填充床反应器作为展示,为该方法的潜力提供了证据。该反应器配置由填充在蜂窝状基质通道中的催化颗粒组成,有望大大增强径向传热。特别是,我们首先关注通过差价合约分析能量传递机理及其解释通过一维模型,我们提供了与非常规配置(2毫米通道等效直径和0.8毫米球体直径)相关的现有相关性评估。然后,在伪连续(宏观)二维模型中实现这些相关性,以便系统地研究微填充床反应器处理o的选择性氧化的能力-二甲苯制邻苯二甲酸酐。我们发现,由于增强的径向传热,微型填充床反应器允许准等温运行,从而扩展了可能的运行条件范围,而不会发生不利的反应器热行为。在更一般的基础上,我们证明了化学反应器工程的分层方法是一种有效的工具,可以使基本模型的应用达到与全面应用相关的复杂度,否则由于不切实际的计算成本而无法实现。
更新日期:2018-01-08
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