The Kenics static mixer is expected to enhance the extraction performance to reduce the burden of the extraction column in the phenolic wastewater treatment process. Currently, it has been deployed as a pre-extractor in a newly built project of 35 m³/h wastewater treatment in Datang coal gasification corporation. The fluctuating flow rate brings instability of the extraction performance. However, few studies have paid attention to the mass transfer performance in demo- or commercial-sized static mixers. Thus, this work adopted a three-dimensional model coupled with the CFD-PBE model, the interphase mass transfer model, and the interface mass transfer–droplet size effect function in the simulation of various sizes of Kenics static mixers to describe the droplet size distribution and mass transfer performance. Besides, to increase the accuracy of extraction performance prediction, the eddy cell model and droplet size effect model were introduced to correct the mass transfer performance and droplet size distribution prediction with the change of equipment size and operation flowing velocity. In the simulations, it was found that the greater static mixer size can achieve better mass transfer performance with fewer mixing elements but translated into a lower time efficiency. It was also found that each size Kenics static mixer featured an optimal total flowing velocity, achieving the maximum extraction efficiency in catechol extraction. The extraction efficiencies peaked at total flowing velocities of 0.8, 1.1, 1.2, and 1.2 m/s, with diameters of 30, 100, 200, and 300 mm, respectively. The characteristics of the change in turbulence dissipation rate, turbulent viscosity, and interfacial tension are key factors in the explanation of these phenomena. In each size static mixer, under the respective optimal flowing velocity, the mass fraction of catechol in the aqueous phase meets the criterion of biochemical treatment process influent after continuous two-stage extraction.

中文翻译：

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不同尺寸的 Kenics 静态混合器萃取时传质预测的数值研究：用涡流模型和液滴尺寸效应模型进行校正


Kenics静态混合器有望增强萃取性能，减轻含酚废水处理过程中萃取塔的负担。目前已在大唐煤气化公司新建35m ³ /h污水处理项目中作为预萃取器使用。流量的波动带来萃取性能的不稳定。然而，很少有研究关注演示或商业尺寸静态混合器的传质性能。因此，本工作在模拟各种尺寸的Kenics静态混合器时，采用三维模型结合CFD-PBE模型、相间传质模型和界面传质-液滴尺寸效应函数来描述液滴尺寸分布和传质性能。此外，为了提高萃取性能预测的准确性，引入涡流模型和液滴尺寸效应模型，随着设备尺寸和操作流速的变化来校正传质性能和液滴尺寸分布预测。在模拟中发现，较大的静态混合器尺寸可以用较少的混合元件实现更好的传质性能，但转化为较低的时间效率。研究还发现，每种尺寸的Kenics静态混合器都具有最佳的总流速，在儿茶酚提取中实现了最大的提取效率。萃取效率在总流速为 0.8、1.1、1.2 和 1.2 m/s、直径分别为 30、100、200 和 300 mm 时达到峰值。湍流耗散率、湍流粘度和界面张力的变化特征是解释这些现象的关键因素。 在各尺寸静态混合器中，在各自的最佳流速下，水相中儿茶酚的质量分数满足生化处理工艺进水连续两级萃取的标准。