A MODIFIED VERSION OF THE VOLUME-AVERAGED CONTINUUM THEORY TO PREDICTPRESSURE-DROP ACROSS COMPRESSIBLE PACKED-BEDS OF SEPHAROSE BIG-BEADS SP

Using a modified version of the volume-averaged continuum theory for m ultiphase processes, theoretical predictions of pressure drop across c ompressible packed beds of Sepharose Big-Beads SP (Amrad Pharmacia Bio tech, Sydney, Australia) are made. Modifications to the volume-average d continuum theory included an additional term incorporated into gover ning equations to account for the influence of column diameter and a c onstitutive function to account for the effect of compressibility on p ressure gradient. Theoretical predictions are compared to experimental pressure-drop data. Results indicate the modified volume-averaged con tinuum theory can provide accurate pressure-drop predictions for Sepha rose Big-Beads SP at different bed heights, column diameters, superfic ial velocities, and fluid viscosity. The influence of column diameter on pressure-drop behavior during scale-up is then examined by comparin g theoretical predictions for laboratory and production-scale columns. Predictions demonstrate a significant dependence on column diameter. This result emphasizes the dangers of predicting pressure-drop behavio r for compressible chromatography resins in production-scale columns b y extrapolation from laboratory-scale pressure-drop data.