CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

doi:10.1016/j.cjche.2024.03.018

中国化学工程学报 ›› 2024, Vol. 70 ›› Issue (6): 173-188.DOI: 10.1016/j.cjche.2024.03.018

CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

Junhai Deng¹, Shilin Lan², Juchang Wu¹, Shenghua Du², Weidong Liu², Luchang Han¹, Yefeng Zhou¹

1. National & Local United Engineering Research Centre for Chemical Process Simulation and Intensification, Chemical Process Simulation and Optimization Engineering Research Center of Ministry of Education, Xiangtan University, Xiangtan 411105, China;
2. Hunan Haili Chemical Industry Company Limited, Changsha 410000, China

收稿日期:2023-09-21 修回日期:2024-03-20 出版日期:2024-06-28 发布日期:2024-08-05
通讯作者: Weidong Liu,E-mail:582745530@qq.com;Yefeng Zhou,E-mail:zhouyf@xtu.edu.cn
基金资助:
The work was supported by the National Natural Science Foundation of China (22078278), Hunan Innovative Talent Project (2022RC1111), Hunan Provincial Education Bureau Foundation (22A0131), Hunan Province Higher Education Key Laboratory of Green Catalysis and Industrial Reaction Process Intensification, and Furong Plan Provincial Enterprise Technology Innovation and Entrepreneurship Team.

CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

Junhai Deng¹, Shilin Lan², Juchang Wu¹, Shenghua Du², Weidong Liu², Luchang Han¹, Yefeng Zhou¹

1. National & Local United Engineering Research Centre for Chemical Process Simulation and Intensification, Chemical Process Simulation and Optimization Engineering Research Center of Ministry of Education, Xiangtan University, Xiangtan 411105, China;
2. Hunan Haili Chemical Industry Company Limited, Changsha 410000, China

Received:2023-09-21 Revised:2024-03-20 Online:2024-06-28 Published:2024-08-05
Contact: Weidong Liu,E-mail:582745530@qq.com;Yefeng Zhou,E-mail:zhouyf@xtu.edu.cn
Supported by:
The work was supported by the National Natural Science Foundation of China (22078278), Hunan Innovative Talent Project (2022RC1111), Hunan Provincial Education Bureau Foundation (22A0131), Hunan Province Higher Education Key Laboratory of Green Catalysis and Industrial Reaction Process Intensification, and Furong Plan Provincial Enterprise Technology Innovation and Entrepreneurship Team.

摘要/Abstract

摘要： Kenics static mixers (KSM) are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency, low power homogenization and easy continuous production. Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM. In this work, a computational fluid dynamics-population balance model (CFD-PBM) coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution, to further reveal the liquid-liquid dispersion characteristics. Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation, reducing Sauter mean diameter (SMD) of dispersed phase droplets and with a shift in droplet size distribution (DSD) towards smaller size. Smaller aspect ratios, greater blade twist and assembly angles amplify shear rate, leading to smaller droplet size and a narrower DSD in the smaller range. The degree of impact exerted by the aspect ratio is notably greater. Notably, mixing elements with different spin enhance shear and stretching efficiency. Compared to the same spin, SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower distribution. Taking into account the pressure drop and efficiency in a comprehensive manner, optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5, a blade twist angle of 180°, an assembly angle of 90°, and interlaced assembly of adjacent elements with different spin. This work provides vital theoretical underpinning and future reference for enhancing KSM performance.

关键词: CFD, Population balance, Liquid-liquid dispersion, Kenics static mixer

Abstract: Kenics static mixers (KSM) are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency, low power homogenization and easy continuous production. Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM. In this work, a computational fluid dynamics-population balance model (CFD-PBM) coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution, to further reveal the liquid-liquid dispersion characteristics. Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation, reducing Sauter mean diameter (SMD) of dispersed phase droplets and with a shift in droplet size distribution (DSD) towards smaller size. Smaller aspect ratios, greater blade twist and assembly angles amplify shear rate, leading to smaller droplet size and a narrower DSD in the smaller range. The degree of impact exerted by the aspect ratio is notably greater. Notably, mixing elements with different spin enhance shear and stretching efficiency. Compared to the same spin, SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower distribution. Taking into account the pressure drop and efficiency in a comprehensive manner, optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5, a blade twist angle of 180°, an assembly angle of 90°, and interlaced assembly of adjacent elements with different spin. This work provides vital theoretical underpinning and future reference for enhancing KSM performance.

Key words: CFD, Population balance, Liquid-liquid dispersion, Kenics static mixer

Junhai Deng, Shilin Lan, Juchang Wu, Shenghua Du, Weidong Liu, Luchang Han, Yefeng Zhou. CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer[J]. 中国化学工程学报, 2024, 70(6): 173-188.

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CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

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