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Modeling of scale‐down effects on the hydrodynamics of expanded bed adsorption columns
Author(s) -
Fenneteau Frédérique,
Aomari Hafida,
Chahal Parminder,
Legros Robert
Publication year - 2003
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.10522
Subject(s) - dispersion (optics) , chromatography , adsorption , scaling , breakthrough curve , separation process , chemistry , packed bed , viscosity , expanded bed adsorption , mechanics , filtration (mathematics) , superficial velocity , simulated moving bed , fluidized bed , centrifugation , materials science , flow (mathematics) , composite material , physics , optics , elution , geometry , mathematics , organic chemistry , statistics
Expanded‐bed adsorption (EBA) is a technique for primary recovery of proteins starting from unclarified broths. This process combines centrifugation, concentration, filtration, and initial capturing of the proteins in a single step. An expanded bed (EB) is comparable to a packed bed in terms of separation performance but its hydrodynamics are that of a fluidized bed. Downstream process development involving EBA is normally carried out in small columns to minimize time and costs. Our purpose here is to characterize the hydrodynamics of expanded beds of different diameters, to develop scaling parameters that can be reliably used to predict separation efficiency of larger EBA columns. A hydrodynamic model has been developed which takes into account the radial liquid velocity profile in the column. The scale‐down effect can be characterized in terms of apparent axial dispersion, D axl,app , and plate number, N EB , adapted for expanded bed. The model is in good agreement with experimental results obtained from 1‐ and 5‐cm column diameters with buffer solutions of different viscosities. The model and the experiments show an increase of apparent axial dispersion with an increase in column diameter. Furthermore, the apparent axial dispersion is affected by an increase in liquid velocity and viscos‐ ity. Supported by visual observations and predictions from the model, it was concluded that operating conditions (liquid viscosity and superficial velocity) resulting in a bed‐void fraction between 0.7 and 0.75 would provide the optimal separation efficiency in terms of N EB . © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 790–799, 2003.