Liquid flow and phase holdup—measurement and CFD modeling for two-and three-phase bubble columns

• Published in: Chemical engineering science Vol. 57; no. 11; pp. 1899 - 1908
• Main Authors: Michele, Volker, Hempel, Dietmar C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.2002; Elsevier
• Subjects: Applied sciences; Biotechnology; Bubble columns; Catalysis; CFD; Chemical engineering; Chemical industry; Chemical reactors; Computational fluid dynamics; Exact sciences and technology; Fermentation; Fluidization; Hydrodynamics of contact apparatus; Modeling; Momentum transfer; Multiphase reactors; Optimization; Personal computers; Turbulence; CFD; Multiphase reactors; Turbulence; Momentum transfer; Fluidization; Modeling; Gas liquid; Gas holdup; Two phase flow; Multiphase flow; Volume fraction; Computational fluid dynamics; Hydrodynamics; Velocity distribution; Particle suspension; Experimental study; Flow velocity measurement; Flow field; Three phase flow; Bubble column; Gas liquid solid; Numerical simulation; Flow velocity; Liquid flow; Electrodiffusion; Measurement method
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/S0009-2509(02)00051-9

Bubble columns are an important class of contacting devices in chemical industry and biotechnology. Their simple setup makes them ideal reactors for two- and three-phase operations such as fermentations or heterogeneous catalysis. Still, design and operation of these reactors is subject to widely empirical scale-up strategies. With recent advances in the development of measurement techniques, a more detailed approach to the development of optimized reactors for specific operations should become possible. This report is based on detailed measurements of local dispersed phase holdups in a pilot plant-sized bubble column operated at high superficial gas velocities and solid holdups. It deals with the influence of superficial gas velocity, solid loading and sparger geometry on measured and computed liquid flow velocities and holdup distributions. Liquid velocity measurements have been performed using the electrodiffusion method, modeling calculations have been carried out using the computational fluid dynamics (CFD) code CFX-4.3. Measurement results presented here give an insight into the development of liquid circulation and fluctuating velocity distribution depending on superficial gas velocity, solid loading and sparger geometry. CFD results implementing a multi-fluid model with k– ε turbulence and special momentum exchange terms for direct gas–solid interactions show that, even on standard PC workstations, this kind of computations can deliver qualitatively reasonable agreement with measurements.