Fluidized bed reactors are commonly considered as more effective devices for the oxidative coupling of methane (OCM) reaction in comparison to traditional fixed bed reactors. In a fluidized bed, particles are prone to agglomerate to generate clusters, changing the original fluidization state and weakening the catalytic ability of catalyst particles. In this study, the inhomogeneous flow behaviors of gaseous species inside a particle cluster were investigated via the computational fluid dynamics (CFD) method compared to isolated particles. The effect of flow characteristics on the heat transfer and the spatial distribution of products of the OCM reaction were subsequently studied. The results indicated that obstruction caused by outer particles of the cluster resulted in the inhomogeneous flow behaviors inside the cluster, leading to the formation of hot spots, the excessive oxidation of C₂H₄, and the generation of CO₂. C₂H₄ was found to be unevenly concentrated inside the particle cluster, with a higher level on the upwind side and a lower level on the downwind side, while it was more uniformly distributed in the isolated particle model. The C₂H₄ yield was significantly lower in the particle cluster model than that in the isolated particle model, with reductions of 47.66% from the peak value and 37.12% from the average value under different working conditions in a model of three-layer 13 particle structure. These results emphasized the uneven flow behaviors of fluids, which impeded the heat transfer between gas and solid and ultimately resulted in the formation of CO₂ and the reduction of C₂H₄ yield. A prediction model was developed to describe the inhibition effect of uneven flow behaviors on the C₂H₄ yield. Furthermore, improving uneven flow behaviors to alleviate the cluster effect on reaction efficiency could be a key focus for future research.

中文翻译：

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OCM 反应中颗粒簇内不均匀流动行为影响的数值研究


与传统的固定床反应器相比，流化床反应器通常被认为是甲烷氧化偶联（OCM）反应更有效的装置。在流化床中，颗粒容易团聚生成团簇，改变原有的流化状态，削弱催化剂颗粒的催化能力。在这项研究中，通过计算流体动力学 (CFD) 方法研究了颗粒簇内气体物质的不均匀流动行为，并与孤立颗粒进行了比较。随后研究了流动特性对 OCM 反应传热和产物空间分布的影响。结果表明，团簇外部颗粒的阻碍导致团簇内部流动行为不均匀，导致热点的形成，C ₂ H ₄ 的过度氧化。 ，以及 CO ₂ 的产生。 C ₂ H ₄ 颗粒团簇内部分布不均匀，上风侧含量较高，下风侧含量较低，但分布较为均匀在孤立粒子模型中。颗粒簇模型中的C ₂ H ₄ 产率明显低于孤立颗粒模型，峰值降低了47.66%，平均值降低了37.12%三层13颗粒结构模型中不同工况下的情况。这些结果强调了流体的不均匀流动行为，阻碍了气体和固体之间的传热，最终导致 CO ₂ 的形成和 C ₂ H ₄ 产量。 建立了一个预测模型来描述不均匀流动行为对 C ₂ H ₄ 产率的抑制作用。此外，改善不均匀流动行为以减轻集群对反应效率的影响可能是未来研究的重点。