Influences of Three-Layer Impeller Structure and Combination on the Gas-Liquid Dispersion in Stirred Tanks
XIE Nannan1, CHEN He2, YI Xin1, YE Guanghua1, SHU Zhongming1, FU Songbao2, ZHOU Xinggui1
1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;
2. Institute of Chemicals & Advanced Materials (Beijing) Company Limited, CNOOC, Beijing 102209, China
Abstract：Gas-liquid stirred tanks are widely used as reactors in the industry, and impellers play a critical role in affecting mass transfer and reaction in this type of reactor. A computational fluid dynamics (CFD) model coupling Euler two-fluid model and population balance model for gas-liquid stirred tanks is established and validated, and this model is used to study the influent of three-layer impeller structure and combination on the gas-liquid dispersion performance. When the six parabolic blade disc turbines (PDT) and six arrow blade disc turbines (ABDT) radial impellers are placed at the bottom, and four wide blade axial flow impellers (KYA), four wide blade airfoil impellers (WHD) and oblique four-blade open turbine impellers (PBT) axial impellers are placed at the top, the flow field structures are similar. PDT+2KYA combination is more favorable than the other combinations in updating the fluid at the tank bottom, due to the strong circulation ability of KYA. In addition, ABDT performs well in breaking bubbles, which are both beneficial in extending the residence time of bubbles. Thus, PDT+2KYA and ABDT+2PBT combinations both show large gas hold-up. ABDT+2PBT combination gives the smallest bubble size and thus highest volumetric mass transfer coefficient, indicating this combination performs best in terms of gas-liquid mass transfer. With the increase of rotational speed, the volumetric mass transfer coefficients of ABDT+2PBT and PDT+2KYA are close, but the former has a higher power consumption. PDT+2KYA conducts higher gas holdup per unit power and average volumetric mass transfer coefficient per unit power under a high rotational speed. Therefore, PDT+2KYA combination is optimal. These results can provide some theoretical guidance for the design and optimization of impellers for gas-liquid stirred tank reactors.
XIE Nannan,CHEN He,YI Xin et al. Influences of Three-Layer Impeller Structure and Combination on the Gas-Liquid Dispersion in Stirred Tanks[J]. Chemical Reaction Engineering and Technology, 2025, 41(1): 134-142.
