Liquid purification or separation – With means to add treating material – Chromatography
Reexamination Certificate
2003-01-10
2004-04-13
Therkorn, Ernest G. (Department: 1723)
Liquid purification or separation
With means to add treating material
Chromatography
C210S281000, C210S656000, C210S659000
Reexamination Certificate
active
06719899
ABSTRACT:
FIELD OF THE INVENTION
This specification relates to methods and apparatus for the control of fluid flow, e.g in chromatography, i.e. apparatus and methods for separating substances by passing a mobile phase through a stationary or retained phase to cause separation of mobile phase components.
BACKGROUND
Chromatography is a well-established and valuable technique in both preparative and analytical work as well as in purification generally. Typical industrial chromatography apparatus has an upright housing in which a bed of packing material, usually particulate, rests against a permeable retaining layer. Fluid mobile phase enters through an inlet e.g at the top of the column, usually through a porous, perforated, mesh or other restricted-permeability layer, moves through the packing bed and is taken out at an outlet, typically below a restricted-permeability layer.
Changing the bed of packing material, because it is spent or in order to run a different process, is an arduous task particularly with big industrial columns which can be hundreds of litres in volume. The existing bed has usually become compacted and difficult to remove. The housing must be dismantled, the compacted packing mass disrupted and then removed. Furthermore, the new bed must be very evenly packed if the column is to be effective: the fresh material must be added carefully while maintaining a flow of liquid. Usually the apparatus must be kept clean, particularly with biological products where high system sterility may be needed for weeks or even months. One small contamination can be disastrous.
Conventionally, many hours have been needed to change the spent packing in a big column.
GB-A-2258415 describes a column which can be packed and unpacked without taking it apart, using special supply and discharge valves in the top and bottom plates of the housing. The packing supply valve has a spray nozzle which can be retracted into the top plate, with the spray openings closed by a seal on the plate, or advanced to project into the column bed space, freeing the openings for a slurry of packing material to be pumped in. The discharge valve has an advanceable nozzle with radially-directed spray openings at its enlarged head, positioned coaxially within a wider bore of the bottom plate. When retracted, the head fits in the bore to seal itself and the bore. To empty the column, the nozzle is advanced and buffer liquid pumped through it. The advanced nozzle head breaks up the packed medium and the pumped-in buffer carries it out through the larger bore, now opened.
There are difficulties in maintaining long-term sanitary conditions with these valve assemblies.
THE INVENTION
We now propose further developments.
In one aspect we provide separation apparatus having a column housing whose housing wall defines an enclosed bed space which in use contains a bed of packing material. The housing wall includes end walls at opposite ends (in terms of an operational fluid flow direction) of the bed space and having inlet and outlet openings for fluid communication to and from the bed space in use. An access valve device communicates with the bed space through the housing wall at an access location. This valve device has first and second adjacent fluid-flow conduits, each having an exterior connection and an interior opening adjacent the housing wall interior. The valve device is controllably adjustable, from outside the housing wall, between
a first, closed condition in which the first and second conduits are both isolated from the bed space;
a second, partially-open condition in which the device puts the first conduit in communication with the bed space but isolates the second conduit from the bed space, and
a third, open condition in which the device puts the first and second conduits both in communication with the bed space.
An access valve of this type offers a number of possible operational advantages. Some are described later. One feature it can offer is packing and unpacking a bed space through a single housing wall installation. The relevant processes may be as follows.
To unpack, the valve is moved to the third condition in which both the first and second conduits are open to the bed space. Fluid is forced in through the first conduit to disrupt and disperse the packed bed, the flowable dispersion of the packing material then flowing out through the second conduit.
Preferred features for these purposes include the following.
The opening of the first conduit may have a spray nozzle or other restriction, fixed or adjustable, to help disrupt the bed by flow velocity. Having plural outlet openings also helps to reach a larger region of the bed space and clear it more effectively.
The access valve device preferably comprises a probe which, from a retracted condition recessed into the housing wall, can be advanced into the bed space to disrupt material therein. The disrupting probe is preferably a movable valve element defining one or both of the conduits, preferably the first conduit at its outlet. (which may be at or through the head of the probe e.g. as in GB-A-2258415).
The opening of the second conduit may form an outlet from the bed space. Desirably it is a single aperture. Desirably it has cross-sectional area at least a substantial proportion of the cross-sectional flow area within the second conduit itself. Desirably the cross-sectional area of the second conduit through the valve device is generally larger than that of the first conduit.
To pack, the access valve device can be adjusted to the second, partially-open condition and packing material forced in through the first conduit, typically as a dispersion of particles in carrier fluid. Carrier fluid escapes from the bed space through an outlet remote from the valve device, while packing material is retained.
Thus, a bed of new packing material can be packed against a permeable end retainer at a housing wall location spaced from and preferably opposed to that of the valve device, by maintaining a flow of carrier fluid through the accumulating bed and out through the end retainer. This flow of carrier fluid can accompany the injection of bed material through the first conduit.
The valve device preferably has relatively movable valve parts or elements which are movable in or into face-to-face sealing contact with one another, and defining the first and second conduits. A pair of such elements may be sufficient to define the first and second conduits and also sealing portions or lands sufficient for shutting off their inward openings for the three conditions mentioned above. Respective spaced sealing portions on one part or element can sealingly engage a single sealing portion, or plural differently-spaced sealing portions, on the other relatively movable part or element to provide the first and second conditions.
The relative movement between the valve elements passing between the three conditions may be linear (typically in the direction through the housing wall, preferably perpendicularly), rotational (typically around a direction axis as specified above) or a combination of these e.g. moved linearly by a screw thread action. The three conditions desirably correspond to three spaced stations along a predetermined single rotational, linear or combination (e.g. helical) path or track for such relative movement.
For simplicity one such valve element may have a single sealing land which in the closed condition isolates the first conduit from the bed space and in the partially-open condition isolates the second conduit from the bed space. This land may be on a said valve element fixed relative to the housing wall, provided at or adjacent a mouth of the valve device. The openings of the first and second conduits can then be defined by one or more further valve elements which is/are slidably moveable relative to that sealing land.
Valves as proposed above are also usable to govern flow into/out of any vessel or conduit; not only separation apparatus housings.
It is a particularly desirable feature for a component of a separator apparatus, and also in other contexts, that
Davis John
Hofmann Martin John
Amersham Biosciences AB
Smith , Gambrell & Russell, LLP
Therkorn Ernest G.
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