Liquid purification or separation – Particulate material type separator – e.g. – ion exchange or... – With rehabilitation means
Patent
1996-08-30
1998-06-02
Nessler, Cynthia L.
Liquid purification or separation
Particulate material type separator, e.g., ion exchange or...
With rehabilitation means
210273, 210291, 210274, B01D 2436, B01D 2438
Patent
active
057593957
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a column construction which includes a movable adaptor that can be used to deliver liquid to or to lead liquid away from a liquid permeable bed in which it is desired to adsorb a substance present in the incoming liquid. The adaptor may also be used in the desorption/elution/washing of the bed. The adaptor is adapted particularly for fluidized beds (=expanded particle beds).
By "movable" is meant that the adaptor can be moved in the direction of flow applied during an adsorption/desorption/washing process.
A fluidized (expanded) bed consists of particles and a through-flowing liquid that keep the particles suspended within a given volume. Such beds have long been used in fermentation processes, among others. In recent times the fluidized bed has also been used as a separation medium in liquid chromatography (WO-A-9218237 and WO-A-9200799).
Particles which have a density which is higher than the density of a surrounding liquid can be fluidized by allowing liquid to flow through the bed in a direction which opposes the direction of gravity (an upwardly directed flow). When the particles have a density which is lower than the density of the surrounding liquid, a downwardly directed flow is required to fluidize the bed. See WO-A-9218237 and WO-A-9200799.
A fluidized bed is considered to be stable when each individual particle keeps within a given cross-section of the column (perpendicular to the flow direction). The settling tendencies of the particles (settling rate measured without counterflow) depends on density and size. In the case of a stabilized fluidized bed, this tendency increases continuously along the flow direction. Those particles which have the most pronounced settling tendency position themselves furthest down in the column. See, for instance, WO-A-9218237. Stable fluidized beds shall be vertical (.+-.0.5.degree.) with vertical flow direction (.+-.0.5.degree.).
A DESCRIPTION OF THE BACKGROUND ART AND A RESUME OF THE PROBLEMS SOLVED BY
THE INVENTION
Adapters earlier used in liquid chromatography are intended to hold a stationary phase (bed) in place and to lead the flow either from or to the stationary phase. Consequently, adapters have had a distributing function on that side which is proximal to the stationary phase, and an opening on the opposite or distal side through which liquid is either delivered or led away.
Movable adapters have earlier been used in chromatography in conjunction with matrices which are packed conventionally in columns. This movability has been achieved by applying a controllable force on the matrix via the adaptor, either through an upper end-piece.
This latter alternative also requires the use of a rod which extends up from the adaptor through the column end-piece, although in this case in order to hold the adaptor in position relative to the upper surface of the gel bed.
Movable adapters intended for fluidized beds and conventional column constructions have long been marketed by Pharmacia Biotech AB, Uppsala, Sweden. These adapters employ hydraulic pressure in accordance with the above.
The main drawbacks of the known techniques are: and adaptor, which results in higher manufacturing costs and a leakage sensitive system. The risk of leakage is affected by the tolerances on the column wall and the adaptor seal, sealing pressure and the resistance of the seal to temperature and chemicals. This has led to demands for extremely small tolerances with regard to the column wall and to the adaptor. clean the systems. Pockets readily form. (primarily in regard of column diameters larger than 1 m). (due to the rod mounted on earlier described movable adapters). (due to the requirement of stationary seals on the earlier described movable adapters). that may have agglomerated on the bottom surface of the net. These layers grow at times and form "cakes" which impede the throughflow of liquid. adaptor which faces towards the matrix in the case of larger diameters (>1.5 m), because those nets that are commercially available ar
REFERENCES:
patent: 3143500 (1964-08-01), Damgaard
patent: 3402126 (1968-09-01), Cioffi
patent: 4233158 (1980-11-01), Wachsmuth
patent: 4460467 (1984-07-01), Ueda
patent: 5415765 (1995-05-01), Banham et al.
Nessler Cynthia L.
Pharmacia Biotech AB
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