Small volume rotary filter
AssigneeMembrex, Inc.
InventorsIosif Shmidt, Mario Badiali
Life of this patent
Estimating the term…
Abstract
An improved method and apparatus for filtration includes an outer stationary body, an inner rotating body defining a gap with the outer body for receiving a fluid sample, the surface of one of the bodies defining the gap being a filter. The rotation of the inner body creates Taylor vortices which continuously displace occluded solute on the filter surface. The filter can be a membrane. In one embodiment the device may be used to filter very small volumes of fluid such as are handled in clinical and other laboratories.
Claims19
A rotary vertical filtration device for separating small volumes of liquid into permeate and concentrate portions, the concentrate not filtered by the end of separation being the retentate, said device having a very small minimum retentate volume and no bottom dynamic seal and comprising:
- (a) a rotor member having a top portion, an essentially cylindrical or conical outer wall, a vertical longitudinal central axis of rotation, and a bottom wall through which permeate cannot be removed;
- (b) a housing with an essentially cylindrical or conical having a top, a side, and a bottom defined by (i) a top housing member, (ii) an essentially cylindrical or conical housing inner wall larger in diameter than the rotor member, and (iii) a bottom housing member, the rotor member being rotatably connected to the housing and being within the cylindrical or conical cavity, the cavity having a vertical longitudinal axis substantially parallel to the longitudinal axis of the rotor member, the essentially cylindrical or conical housing inner wall corresponding to and being closely spaced from the corresponding portion of the cylindrical or conical outer wall of the rotor member to define an essentially cylindrical or conical narrow gap between said inner and outer walls;
- (c) a filter that allows permeate to pass through it mounted on the cylindrical or conical outer wall of the rotor member or on the cylindrical or conical inner wall of &:he housing, the filter having a filtration area whose lower extent is very close to the bottom housing member to minimize the minimum retentate volume of the cavity, which retentate cannot be filtered because that minimum volume is below the lower extent of the filtration area;
- (d) entry means to allow liquid to enter the gap;
- and
- (e) means to rotate the rotor member so that the calculated Taylor number for liquid in the gap is greater than about 40.
A batch rotary vertical filtration device for separating small volumes of liquid into permeate and concentrate portions, the concentrate not filtered by the end of separation being the retentate, said device having a very small minimum retentate volume and no bottom dynamic seal and comprising:
- (a) a rotor member having a top portion, an essentially cylindrical or conical outer wall, a vertical longitudinal central axis of rotation, and a bottom wall through which permeate cannot be removed;
- (b) a housing with an essentially cylindrical or conical cavity having a top, a side, and a bottom defined by (i) a top housing member, (ii) an essentially cylindrical or conical housing inner wall larger in diameter than the rotor member, and (iii) a bottom housing member, the rotor member being rotatably connected to the housing and being within the cylindrical or conical cavity, the cavity having a vertical longitudinal axis substantially parallel to the longitudinal axis of the rotor member, the essentially cylindrical or conical housing inner wall corresponding to and being closely spaced from the corresponding portion of the cylindrical or conical outer wall of the rotor member to define an essentially cylindrical or conical narrow gap between said inner and outer walls;
- (c) a filter that allows permeate to pass through it mounted on the cylindrical or conical outer wall of the rotor member or on the cylindrical or conical inner wall of the housing, the filter having a filtration area whose lower extent is very close to the bottom housing member to minimize the minimum retentate volume of the cavity, which retentate cannot be filtered because that minimum volume is below the lower extent of the filtration area;
- (d) entry means to allow liquid to enter the gap;
- and
- (e) means to rotate the rotor member so that the calculated Taylor number for liquid in the gap is greater than about 40;
- wherein the permeate is recovered after rotation has stopped.
A process for separating small volumes of liquid into permeate and concentrated portions, the concentrate not filtered by the end of separation being the retentate, said process comprising:
- (a) providing a vertical rotary filtration device having a very small minimum retentate volume and no bottom dynamic seal and comprising:
- (i) a rotor member having a top portion, an essentially cylindrical or conical outer wall, a vertical longitudinal central axis of rotation, and a bottom wall through which permeate cannot be removed;
- (ii) a housing with an essentially cylindrical or conical cavity having a top, a side, and a bottom defined by (A) a top housing member, (B) an essentially cylindrical or conical housing inner wall larger in diameter than the rotor member, and (C) a bottom housing member, the rotor member being rotatably connected to the housing and being within the cylindrical or conical cavity, the cavity having a vertical longitudinal axis substantially parallel to the longitudinal axis of the rotor member, the essentially cylindrical or conical housing inner wall corresponding to and being closely spaced from the corresponding portion of the cylindrical or conical outer wall of the rotor member to define an essentially cylindrical or conical narrow gap between said inner and outer walls;
- (iii) a filter that allows permeate to pass through it mounted on the cylindrical or conical outer wall of the rotor member or on the cylindrical or conical inner wall of the housing, the filter having a filtration area whose lower extent is very close to the bottom housing member to minimize the minimum retentate volume of the cavity, which retentate cannot be filtered because that minimum volume is below the lower extent of the filtration area;
- (iv) entry means to allow liquid to enter &:he gap;
- and
- (v) means to rotate the rotor member so that the calculated Taylor number for liquid in the gap is greater than about 40;
- (b) placing liquid to be filtered in the gap;
- and
- (c) rotating the rotor member to separate the liquid into permeate and concentrate portions.
Dependencies are inferred from the claim text.