Flow behavior and size characteristics of microbubble swarm in a HiGee-aided fixed bed reactor with different packed structures.

[Display omitted] • The flow behavior, d 32 , and ɛ g of microbubble swarm were investigated under different packed structures of catalyst bed and catalyst support bed. • An empirical correlation would be established to predict (d 32) o /(d 32) i. • The mass transfer parameters, such as the microbubble number density (MND) and effective interfacial area (a e) of HFBR, were also obtained. A HiGee-aided fixed bed reactor (HFBR) has great potential for catalytic hydrogenation with hydrogen microbubble swarm for gas–liquid mass transfer intensification. However, the flow behavior and size characteristics of microbubble swarm in the catalyst bed of HFBR still remain unclear. In this work, the flow characteristics of microbubble swarm in different packed structures of catalysts and catalyst supports had been fully analyzed by the high-speed photography and image processing technology. The optimal ratio of packing heights for the bottom of the catalyst supports was Φ 13 mm: Φ 6 mm: Φ 3 mm = 3: 1: 1, while the top of the catalyst supports was packed with single catalyst support of Φ 6 mm. Furthermore, a dimensionless correlation based on the experimental results had been developed to predict (d 32) o /(d 32) i with deviations within ±15 %. The effective interfacial area of HFBR was 0.6 ∼ 6.1 × 103 m2/m3 under the experimental conditions. [ABSTRACT FROM AUTHOR]