Bubble column fluid dynamics, flow structures in slender columns with large-diameter ring-spargers

摘要

Bubble columns, when operated at higher superficial gas velocities, depict a chaotic flow behavior. However, it is generally observed that the long time average of its flow velocity pattern depicts a simple structure: The dispersion is rising close to the column axis and, by continuity, it is coming down again near the wall. Long columns, equipped with larger-diameter ring-spargers, depict an average flow pattern that deviates from this behavior. In the lower part of the column, the flow is moving downwards near the axis and rising close to the wall, while in the upper part of the column quite the opposite is observed. This phenomenon, already observed by Lapin et al. (Chem. Eng. Sci. 56 (2000) 239) in large industrial reactors, is examined in detail on the pilot scale. Experimental results are compared with numerical simulations based on the Euler-Lagrange representation of the Navier-Stokes equation system. (C) 2002 Published by Elsevier Science Ltd. [References: 12]