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A New Fluid Distribution System for Scale-Flexible Expanded Bed Adsorption.

A New Fluid Distribution System for Scale-Flexible Expanded Bed Adsorption.

J.J. Hubbuch, A. Heeboll-Nielsen, T.J. Hobley, O.R.T. Thomas


Biotechnology and Bioengineering, vol. 78, pages 35-43

Datum: 2002

A new fluid distribution system designed for expanded bed adsorption was introduced and studied in a 150-cm diameter column. Based on fluid application through a rotating distributor, it eradicates the need for perforated plates, meshes, or local mixers. The effect of rotation rate on column performance was examined by fluidizing a 30-cm high bed of supports with tap water and introducing pulses of dye or acetone tracer. Linear bed expansion was seen as the superficial fluid velocity raised from 170 cm (.) h(-1) to 450 cm (.) h(-1) (3000 L (.) h(-1) to 8000 L (.) h(-1)), and there was little change in expansion characteristics as distributor rotation rate was increased from 2.5 to 10 rpm. The distributor was observed to generate a flow pattern suitable for expanded bed adsorption when the supports were fluidized at a superficial fluid velocity of 283 cm (.) h(-1) and dye pulses introduced. At a rotation rate of 2.5 rpm, no significant dead zones were observed, and a discrete band was formed that moved up through the bed. Furthermore, the pattern of dye movement could be used to calculate interstitial linear fluid velocities of 460 cm (.) h(-1) and 572 cm (.) h(-1) at the column wall and center, respectively, indicating a parabolic flow profile. The distributor rotation rate giving the best operating conditions was found to be 2.5 rpm when the bed was fluidized at a flow velocity of 283 cm (.) h(-1) and the residence time distribution of acetone tracer examined. Under these conditions, the coefficient of axial dispersion was 6.1 x 10(-6) m(2) (.) s(-1) and 29 theoretical plates were measured. When the rotation rate was raised to 10 rpm, the coefficient of axial dispersion increased to 8.08 x 10(-6) m(2 .) s(-1) and the number of theoretical plates decreased to 22. (C) 2002 Wiley Periodicals, Inc.