Multiscale Model of Gas–Liquid Interface Mass Transfer in Gas–Liquid–Solid Fluidized Beds

Abstract

The gas−liquid−solid fluidized bed (GLSFB) is one of the most important multiphase chemical and biochemical reactors in the process industry. Quantifying scientifically the process of gas/liquid mass transfer is the key routine to design and optimize such a reactor. However, until now, most of the masstransfer calculations in a fluidized bed are done by using empirical correlations, which have limited applications. This work develops a multiscale gas/liquid mass-transfer model for the first time together with consideration of the bimodal bubble size distribution in the GLSFB based on the principle of energy minimum multiscale. This new model is able to predict the gas−liquid mass-transfer parameters and the influence of the double-peak bubble size distribution on mass transfer and to reveal the mechanism of multiscale regulation and control of the gas/liquid mass-transfer process in GLSFB. The results of model calculations agree with literature data, the modeling predictions show that the small bubbles have greater impact on gas−liquid interfacial area; and the area can be adjusted by changing the microscale of small bubbles; the large bubbles have greater impact on mass-transfer coefficient, and the coefficient can be regulated by the mesoscale of large bubbles; when changing the superficial gas and liquid velocities, small bubbles have greater influence on volume mass-transfer coefficient and can be regulated by the microscale of small bubbles, and when changing the superficial particle velocity, large bubbles have greater influence and can be regulated by the mesoscale of large bubbles.