U.S. patent application number 10/482711 was filed with the patent office on 2005-08-11 for endpiece for a chromatography column.
Invention is credited to Bellqvist, Peter, Davis, John, Gebauer, Klaus, Pichl, Ulf, Salven, Owe.
Application Number | 20050173324 10/482711 |
Document ID | / |
Family ID | 9917919 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050173324 |
Kind Code |
A1 |
Salven, Owe ; et
al. |
August 11, 2005 |
ENDPIECE FOR A CHROMATOGRAPHY COLUMN
Abstract
A liquid transfer system (100) comprising a net (170) and a net
support (160), wherein, the net (170) is integrally joined with the
net support (160). The net (170) and the net support (160) are
preferably joined by welding, such as contact welding or by welding
at a lower edge (400) of a number of welding-holes (350) that
extends through the net support (160).
Inventors: |
Salven, Owe; (Uppsa;a,
SE) ; Gebauer, Klaus; (Uppsala, SE) ;
Bellqvist, Peter; (Uppsala, SE) ; Davis, John;
(Uppsala, SE) ; Pichl, Ulf; (Uppsala, SE) |
Correspondence
Address: |
AMERSHAM BIOSCIENCES
PATENT DEPARTMENT
800 CENTENNIAL AVENUE
PISCATAWAY
NJ
08855
US
|
Family ID: |
9917919 |
Appl. No.: |
10/482711 |
Filed: |
December 30, 2003 |
PCT Filed: |
July 1, 2002 |
PCT NO: |
PCT/GB02/02999 |
Current U.S.
Class: |
210/198.2 ;
422/70 |
Current CPC
Class: |
G01N 30/603 20130101;
B01D 15/22 20130101; G01N 30/6017 20130101 |
Class at
Publication: |
210/198.2 ;
422/070 |
International
Class: |
B01D 015/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 4, 2001 |
GB |
0116345.5 |
Claims
1-13. (canceled)
14. A liquid transfer system (100) comprising a net (170) and a net
support (160), wherein the net (170) is integrally joined with the
net support (160) by welding at the lower edge (400) of a number of
welding-holes (350) that extend through the net support (160).
15. The liquid transfer system (100) of claim 14, wherein the lower
edge (400) is provided with a welding-protrusion (410) that extends
in the plane of the net support (160) towards the middle of the
welding hole (350).
16. The liquid transfer system (100) of claim 14, further
comprising a plurality of flow-plugs (420) arranged in the
welding-holes (350) to reduce excess volume.
17. The liquid transfer system (100) of claim 14, wherein the net
support (160) is rigid and supported only at its outer
perimeter.
18. The liquid transfer system (100) of claim 17, wherein the net
support (160) is a stainless steel plate with a ratio between
thickness and diameter of between 8:1500 and 10:1500
19. The liquid transfer system (100) of claim 14, wherein the net
support (160) is provided with threaded structures (620), whereby
the net support (160) is secured to a distribution system (130) by
screws (610) that extend through holes in the distribution system
(130) and engage said threaded structures (620).
20. The liquid transfer system (100) of claim 14, wherein the net
support (160) supports a distribution arrangement (150) formed by a
disc shaped distribution element (510) and a distribution gap
(520).
21. The liquid transfer system (100) of claim 20, wherein the
distribution arrangement (150) is supported by the net support
(160) through a number of spacing elements (530) that are provided
in between the net support (160) and the distribution arrangement
(150).
22. The liquid transfer system (100) of claim 14, further
comprising a central nozzle (310) that is integrally joined with
the net (170) and the net support (160).
23. The liquid transfer system of claim 14, wherein said welding
holes (350) do not extend through the net (170).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to chromatography columns.
More specifically, the invention relates to a net for large-scale
chromatography columns.
BACKGROUND OF THE INVENTION
[0002] Chromatography columns often contain a net to prevent media
from escaping from the end cells which are used for radially
distributing the fluid flowing in from a central inlet at one end
of the column and for radially collecting the fluid for subsequent
outputting from a central outlet at the opposite end of the column.
These nets extend across substantially the whole internal diameter
of the column. In the prior art the nets have been made of polymer
materials and have been attached (with a supporting backing plate
if required) to the central inlet resp. central outlet by means of
screws or bolts. The screws or bolts are mounted with their heads
on the side of the net facing away from the inlet, resp. outlet,
and they pass through suitably sized holes in the net and are
screwed into suitably threaded axial holes in the wall of the
central inlet resp. outlet.
[0003] Alternatively nets have been attached by being mounted on a
central inlet or outlet tubular port provided with an internal
thread and a stop flange positioned on the outside of the port at a
distance from the end where the net is to be mounted which is less
than the thickness of the net. The net is then positioned against
the flange with the end of the port extending into a central
opening in the net. The net is held in place by a threaded end
piece which has a tubular portion provided with a thread adapted to
mate with the thread on the inside of the port, and a flange at one
end which pushes the net against the flange on the port when the
end piece is screwed up into the port.
[0004] One problem with existing arrangements is that it is
difficult to give the net proper support, due to the flexible
nature of the net. As a consequence, the net may bend if the flow
of sample media through the cell is high. In fact, it is common
that the net bends to such an extent that it gets plastically
deformed, which is highly undesirable as it influences the
characteristics of the bed and thus the flow characteristics for
the sample. Therefore, the net limits the flow for such
columns.
[0005] Another problem is that the heads of the mounting screws,
resp. the end pieces, project into the bed media and interfere with
the packing of the bed media. This may also lead to undesirable
fluid-flow characteristics at the top/bottom of the bed. The heads
may also cause dead volumes, i.e. spaces where fluid circulation is
slow or non-existent, where particles can collect and this makes
cleaning difficult and can lead to sanitary problems.
[0006] As used herein and in the appended claims: The term "fluid
system" is intended to designate the apparatus in which liquid is
either introduced to or withdrawn from a cell at a zone
approximately transverse the direction of flow through the cell.
The term "cell" is intended to include the terms "vessel" and
"column", as well as any other structure utilised by practitioners
of the separation arts, to effect a separation and/or extraction of
components from an admixture by bringing the admixture into contact
with solid or liquid exchange media, above referred to as the
packing. "Cross-sectional zone" (or region) refers to a region
within a cell bounded by cross sections of the cell-oriented
transverse (typically approximately normal) the longitudinal
direction of flow through the cell. "Longitudinal direction of
flow" refers to the direction of flow from an inlet towards an
outlet within a cell. "Longitudinal" is used consistently to
designate the dominant flow path of fluid through a cell without
regard to direction. "Flow connection system" refers to a system of
channels or paths that connect two points in a fluid circuit. While
the skilled person realises that columns may be arranged in many
different orientations, for the sake of convenience and clarity of
description, it will be assumed that the upper end of the column is
the inlet end while the bottom end is the outlet end. "Distribution
system" refers to structure through which fluids are introduced to
a cell and "collection system" refers to structure used to withdraw
fluids from a cell, in each instance from a cross-sectional
zone.
SUMMARY OF THE INVENTION
[0007] The object of the invention is to provide a new way to
support the net in a large scale fluid system, which overcomes the
drawbacks of the prior art systems. This is achieved by the liquid
transfer system as defined in claim 1.
[0008] One advantage with such a liquid transfer system is that the
net is better supported, whereby plastic deformation of the net may
be avoided, and the system may be used at increased flow rates.
[0009] Another advantage is that the proposed liquid transfer
system is that no parts oif the system interfere with the bed.
[0010] Still a further advantage is that the proposed liquid
transfer system reduces the risk for sanitary problems, due to the
simple design comprising few interconnected elements.
[0011] Still a further advantage is that the proposed liquid
transfer system simple and therefore cheap to produce.
[0012] Embodiments of the invention are defined in the dependent
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0013] FIG. 1 shows schematically a conventional separator system
in cross-section.
[0014] FIG. 2 shows schematically a second prior art separator
system.
[0015] FIGS. 3a-3c show arrangements for fixation of the net to the
net support according to the invention.
[0016] FIG. 4 shows another arrangement for fixation of the net to
the net support according to the invention.
[0017] FIG. 5 shows a first embodiment of the present
invention.
[0018] FIG. 6 shows an alternative embodiment of the present
invention.
[0019] FIG. 7 shows another alternative embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIG. 1 shows schematically a conventional separator system
100 in cross-section. As both ends of such a system often are
substantially identical and therefore often either end can be used
as the inlet end while the other end is used as the outlet end,
only one end is shown. The separator system 100 is essentially
rotationally symmetric and it comprises sidewalls 110, and a
distribution system 130. The distribution system 130 comprises an
inlet 140, and a distribution arrangement 150, for example radially
extending ribs, for evenly distributing the mobile phase over the
cross-section of the column 100 at the inlet end, and a similar
arrangement at the outlet end (not shown) for evenly collecting the
mobile phase at the outlet end from the cross-section of the
column. The distribution system 130 is terminated by a net support
160, which for instance may be a perforated plate. To prevent the
packing from entering the distribution system 130, and to further
enhance the distribution, a fine net 170 (mesh) or an equivalent
filter material is arranged below the net support 160 facing the
packing. As been described above, the net 170 and the net support
160 are attached to the distribution system 130 by screws 180, and
in that they are clamped around their outer circumferences between
the sidewalls 110 and the distribution system 130. To reduce
leakage, sealing means such as O-rings 190, 200 are provided at
each screw 180 and around the perimeter of the system
respectively.
[0021] As mentioned above this arrangement suffers from sanitary
problems, e.g. matter collecting in dead volumes, and the screws
may cause undesirable fluid-flow characteristics in the bed.
Furthermore, in order to achieve acceptable fixation of the net 170
a large number of screws 180 is needed, especially for large
diameter columns.
[0022] FIG. 2 shows schematically another prior art separator
system 300. This system differs from the system above in that it
comprises a central nozzle 310 that can be used to inject slurry or
cleaning fluid into the column. The net support 160 and the net 170
therefore each has a central hole with a diameter that is slightly
larger than the outer diameter of the central nozzle 310. The
central nozzle 310 is further used to centrally fixate the net
support 160 and the net 170 by a flange 320 on the outer perimeter
of the central nozzle 310, and a second flange 330 on the portion
of the central nozzle that extends into the bed. Due to this a
lesser number of screws 180 is needed, depending on the size of the
system, but the problem relating to screws interfering with the bed
still remain.
[0023] The present invention avoids these problems by integrally
joining the net 170 with the net support 160, such that the net is
rigidly fixed to the net support 160, creating an integrated net
arrangement By forming the net support 160 of a material, which is
compatible with the material of the net 170, they may for example
be joined together by welding.
[0024] There are a number of possible ways to weld the net 170 to
the net support 160 e.g. contact welding, continuos or partial
welding along a lower edge 400 of a number of welding-holes 350 in
the net support 160, together with welding along the outer
perimeter of the net. FIGS. 3a-3c show examples of arrangements of
welding-holes 350 providing a sufficient fixation of the net. In
FIG. 3a the welding holes are arranged as slots along a circle that
is concentric with the net support 160. In FIG. 3b the welding
holes are arranged as radially extending slots, and in FIG. 3c the
slots of FIG. 3a are substituted by circular holes. If the
welding-hole arrangement is made such that the holes cover a
sufficiently large percent of the area of the system, no extra
fluid passages are needed, i.e. the over all perforation of the net
support 160 is omitted. To achieve an optimal welded joint or seam,
the lower edge 400 of the welding-holes 350 whereto the net 170 is
to be welded, may be provided with a small welding-protrusion 410
as is shown in FIG. 4. The welding-protrusion 410 extends in the
plane of the net support 160 towards the middle of the welding hole
350, and acts as a material source in the welding process whereby
unwanted recesses may be avoided at the edge 400.
[0025] One aspect that has to be addressed when designing the net
support 160 is that excess volume due to wide holes or other hollow
structures should be avoided. The net support 160 should further be
adapted to the flow characteristics of the system. However, it may
be necessary to make the holes in which the net is to be welded
relatively wide as it is difficult to reach down and weld if the
hole is to narrow. If the net support 160 has a thickness of about
8 mm a suitable width may be in the magnitude of 20 mm. The
welding-protrusion 410 further facilitates the welding as the upper
part of the welding holes is given a larger diameter. To reduce the
excess volume in the welding holes 350 and to match the flow
characteristics, a flow-plug 420 or the like may be provided in the
hole. The flow-plug 420 is conveniently made of a machinable or
mouldable material, e.g. plastic, and is designed such that the
flow path through the welding-hole 350 is divided into one or more
smaller paths, that match the flow characteristics of the system.
Preferably, the flow-plug 420 is a structure that is centred in the
welding hole 350, such that smaller paths are created between the
sides of the flow-plug 420 and the walls of the welding hole
350.
[0026] According to a first embodiment, which is shown in FIG. 5,
the net support 160 is formed such that it is rigid enough to be
supported only at its outer perimeter. By this all supporting
screws and the like may be omitted, whereby interference with the
bed is reduced to a minimum. There are several ways in which such a
rigid net support 160 may be obtained, such as choosing a more
rigid material or increasing the thickness of the material it is
made from. As large scale systems may have a column diameter of 400
millimetres up to 2 meters or more, the thickness of the net
support 160 have to be appropriate selected for each column
diameter. If, for example, a stainless steel plate is used as the
net support 160 for a 500 mm column, a thickness of about 3 mm
would be useful at normal flow rates, but for a 1.5 m column the
thickness of the steel-plate should be 8 to 10 mm. According to
this example, a relationship between the column diameter and the
thickness of a stainless steel net support 160 is about 500:3.
However, it should be noted that the rigidity is further highly
dependent on the design of the welding-hole 350 arrangement.
Further, if the system is used at higher flow rates, the thickness
may have to be increased.
[0027] Such a rigid net support 160 may also be formed such that it
supports the distribution arrangement 150, such as shown in FIG. 6.
In this embodiment the distribution arrangement 150 is comprised of
a disc shaped distribution element 510 and a distribution gap 520
that is terminated by the net support 160. A number of spacing
elements 530 are provided in between the net support 160 and the
distribution arrangement 150, which elements 530 support the
distribution element 510 and defines the height of the distribution
gap 520. Similar spacing elements 540 are provided in between the
distribution element 510 and a main body of the distribution
arrangement 150, thereby defining a distribution channel 550. The
spacing elements 530, 540 may be provided separate from, or may be
integrally formed on the surface on the comprised parts.
[0028] According to another embodiment, which is shown in FIG. 7,
the net support 160 is supported at its outer perimeter together
with a number of support screws 610 that are evenly spaced to
additionally support the net support 160. However, in this
embodiment no screws 610 are in direct contact with the bed, as the
net support 160 is provided with threaded structures 620 and the
screws 610 extends through holes in the distribution system to
engage the threaded structures 620. Further, due to that the net
170 is welded to the net support 160, a relatively small number of
screws are needed to achieve full support of the net 170. The
threaded structures 620 may e.g. be threaded holes in the net
support 160 or threaded structures that protrude from the upper
surface of the net support 160. Sleeves 630 are provided to set the
right distance between the distribution arrangement 150 and the net
support 160. If the sleeves 630 are made of a material having
sealing properties, e.g. a suitable plastic material, additionally
sealing means may be omitted, thus achieving improved sanitary
properties.
[0029] Either one of the above embodiments may further be adapted
for use together with a central nozzle 310, whereby additional
rigidity is achieved. In one special embodiment of this type, the
central nozzle 310 is integrally joined with the net 170 and the
net support 160, whereby many sanitary problems and other problems
of prior art are solved.
[0030] It should be noted that the present invention is also
applicable to columns with non-circular cross-sections, e.g. square
or rectangle cross sections, and therefore the term "ring" is not
intended to be limited to circular means for retaining a net but is
also intended to include means for retaining a net having other
shapes e.g. square, rectangular etc.
[0031] The present invention is not limited to use with metal nets
and metal means for retaining a net welded together but is also
applicable to plastic nets and plastic means for retaining a net
that may also be welded together. While the invention has been
illustrated by the use of welding to join the net and means for
supporting the net together it is also conceivable to use any other
inherently leak-proof means of joining the net and means for
retaining a net such as soldering, brazing, gluing or the like,
although welding is the preferred method as it does not introduce
any impurities or unwanted substances into the column. It is also
conceivable that the nets and means for retaining a net may be
formed integrally, for example, by being cast, sintered or moulded
in one piece.
* * * * *