Couette membrane filtration apparatus for separating suspended components in a fluid medium using high shear
First Claim
1. An apparatus for filtering a fluid suspension containing particles of living matter origin capable of being damaged if subjected to shear stress above a predetermined level, comprisinga first surface of revolution,a membrane comprising a second surface of revolution coaxial with and spaced form he first surface said first and second surface forming a means for defining a shear gap of predetermined radial dimensions between the surfaces, said dimensions increasing along axial lengths of said surfaces,inlet means for introducing the fluid suspension into the gap,means for rotating one of said surfaces about its axis of revolution relative to the other surface at an angular velocity such that shear stress below said level is imposed on the fluid suspension in the gap, whereby fluid is separated from the fluid suspension and passes through pores define by the membrane,first outlet means for collecting fluid passing through the membrane, and other outlet means for removing fluid form the gap remotely from said inlet means, the viscosity of the fluid remaining in the gap increasing in a direction toward said other outlet means,and said means defining said shear gap to have gap radial dimensions between said first and said second surfaces increasing in said direction toward the other outlet means in such relation to aid viscosity increase in said direction that the shear stress in the fluid suspension at and along the membrane surface is maintained substantially constant.
0 Assignments
0 Petitions
Accused Products
Abstract
The present invention provides significant improvements in the design and performance of a specific type of Rotary Membrane Filter (RMF) apparatus which has the capability of separating particles from a fluid having the same and nearly the same density as the particles by utilizing shear to achieve separation, not centrifugal forces. A particular application for the apparatus is in the processing of fluid suspensions in which the suspensions contain fragile particles which are subject to damage due to excessive shear stresses. The prior art describes processing at constant shear rate, whereas the present invention provides the design and optimization of operation of such an apparatus at constant shear stress, which is maintained at a value below that at which significant damage to the fragile particles is encountered. The use of the invention in plasmapheresis (blood separations) is described in detail, it being understood that the teachings of the invention are also directly applicable to other fluids containing fragile particles. The application of the RMF in a continuous flow processing system designed to extract blood plasma from a donor is described, including return of corpuscular components to the donor.
-
Citations
63 Claims
-
1. An apparatus for filtering a fluid suspension containing particles of living matter origin capable of being damaged if subjected to shear stress above a predetermined level, comprising
a first surface of revolution, a membrane comprising a second surface of revolution coaxial with and spaced form he first surface said first and second surface forming a means for defining a shear gap of predetermined radial dimensions between the surfaces, said dimensions increasing along axial lengths of said surfaces, inlet means for introducing the fluid suspension into the gap, means for rotating one of said surfaces about its axis of revolution relative to the other surface at an angular velocity such that shear stress below said level is imposed on the fluid suspension in the gap, whereby fluid is separated from the fluid suspension and passes through pores define by the membrane, first outlet means for collecting fluid passing through the membrane, and other outlet means for removing fluid form the gap remotely from said inlet means, the viscosity of the fluid remaining in the gap increasing in a direction toward said other outlet means, and said means defining said shear gap to have gap radial dimensions between said first and said second surfaces increasing in said direction toward the other outlet means in such relation to aid viscosity increase in said direction that the shear stress in the fluid suspension at and along the membrane surface is maintained substantially constant.
-
14. An apparatus for filtering plasma from whole blood comprising
an elongated housing having an interior surface of revolution of a first predetermined profile which is tapered axially of said interior surface, an elongated membrane filter having pores and an exterior surface of revolution of a second predetermined profile which is tapered axially of said exterior surface and rotatably disposed within the housing, said interior and exterior surfaces forming a means for defining a narrow annular gap between the interior surface of the housing and the exterior surface of the membrane filter, said exterior and interior surfaces being coaxial, and means for rotating the membrane filter about its axis of revolution at an angular velocity such that at any location on the membrane near a pore or pores the product of the filter angular velocity and radius at said location, divided by the local gap thickness, has predetermined relation to local blood viscosity, said angular velocity being below that at which significant damage to re blood cells is encountered, whereby plasma is separated from the whole blood introduced into the gap and passes through the membrane, there being inlet means to pass whole blood into the gap, first outlet means for collecting plasma passing through the membrane, and other outlet means remote from said inlet means to remove from the gap blood from which plasma has been removed via the membrane, said local blood viscosity in the gap increasing in a direction toward said other outlet means, said means defining said gap to have gap radial dimensions between said exterior and interior surfaces increasing in said direction toward the other outlet means in such relation to said viscosity increase in said direction that the shear stress in the blood in the gap at and along the membrane surface is maintained substantially constant.
-
26. An apparatus for filtering fluid suspensions comprising:
-
an elongated hollow container having an interior wall with a first predetermined tapering profile; an elongated core element disposed within the container having a second predetermined tapering profile, said profiles forming a means for defining a gap having a thickness which varies in the direction of elongation in a pre-determined manner between the interior wall and the core element;
said interior wall an said core element being co-axial,inlet means locate at one end of the apparatus; means for introducing a fluid suspension through the inlet means into the gap; means for rotating the core element about its axis of rotation at a predetermined angular velocity within the container such that, due to the geometry and configuration of the gap, essentially uniform shear stress is imposed on the fluid suspension over the entire surface extent of the core element; first outlet means located at the inlet end of the apparatus for removing fluid extracted from the fluid suspension; second outlet means located at the end of the apparatus opposite the inlet end for removing the remaining portion of the fluid suspension; membrane means disposed over the exterior surface of the core element for filtering and separating the fluid from the fluid suspension when the core element is rotated, the membrane having an exterior surface; and means for communicating the filtered fluid from the side of the membrane opposite the fluid suspension to the first outlet means, the viscosity of the fluid suspension in the gap increasing in a direction toward said second outlet means, and said means defining said gap to have gap radial dimensions between said interior wall and the exterior surface of the membrane increasing in said direction toward the second outlet means in such relation to said viscosity increase in said direction that the shear stress in the fluid suspension at and along the membrane surface is maintained substantially constant. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
-
-
45. An apparatus for filtering plasma from whole blood comprising:
-
a tapered elongated housing having an interior surface of revolution with a first predetermined profile; semipermeable membrane means applied to and covering the interior surface of the housing of the housing; a tapered elongated spinner element having a surface of revolution of a second predetermined profile rotatably disposed with the housing, the membrane means and the surface of the element forming a means defining a narrow gap having radial dimensions varying in a predetermined manner in the direction of elongation;
the membrane means and the surface of the element being coaxial;means for rotating the spinner element about its axis of revolution at an angular velocity and local radius is related to the uniform ratio of local gap dimension to local blood viscosity and immediately below the velocity at which significant damage to rd blood cells is encountered, there being inlet means to pass whole blood into the gap, and first outlet means remote from said inlet means to remove from the gap blood from which plasma has been removed via the membrane, the viscosity of the blood in the gap increasing in a direction toward the outlet means, and said means defining said gap to have gap radial dimensions increasing in said direction toward the outlet means in such relation to said viscosity increase in said direction that the shear stress in the blood in the gap at and along the membrane surface is maintained substantially constant. - View Dependent Claims (46, 47, 48, 49)
-
-
50. An apparatus for filtering fluid suspension comprising:
-
a first stationary surface of revolution; a second surface of revolution rotatable about its axis of revolution membrane means covering the stationary surface and having a membrane surface, said membrane surface and said second surface forming a means for defining a gap of predetermined radial dimensions inlet means for introducing a fluid suspension into the gap; means for rotating the second surface at a predetermined angular velocity such that fluid is separated from the fluid suspension and passes through the membrane; and first outlet means for collecting fluid passing through the membrane; and
other outlet means for removing fluid from the gap remotely from said inlet means, the viscosity of the fluid remaining in the gap increasing in direction toward said other outlet means,the first and second surfaces being coaxial, and said means defining said gap to have gap radial dimensions between said first surface and said membrane surface increasing in said direction toward the other outlet means in such relation to said viscosity increase in said direction that the shear stress in the fluid suspension at an along the membrane surface is maintained substantially constant.
-
- 51. An apparatus according to clam 50 wherein said second surface of revolution is incorporated into a rotatable core element and said first stationary surface of revolution is incorporated into the interior surface of a container for housing the rotating core element.
-
54. An apparatus for filtering a fluid suspension containing particles of living matter origin capable of being damaged if subjected to shear stress above a predetermined level, comprising
(a) a first surface of revolution, (b) a membrane comprising a second surface of revolution spaced from said first surface, said first surface and said membrane surface forming a means for defining a gap region radially between a surface portion of the membrane and a substantial surface portion of the first surface, (c) inlet means for introducing said fluid suspension into the gap, first outlet means for collecting fluid passing from the gap through the membrane via pores defined by the membrane, and other outlet means for removing fluid from the gap remotely from said inlet means, (d) means for rotating one of the surfaces relative to the other surface at an angular velocity such that shear stress is imposed on the fluid suspension in the gap, and the viscosity of the fluid suspension remaining in the gap increases in a direction toward the other outlet means, (e) and said means defining said gap to have gap radial dimensions increasing in said direction toward the other outlet means in such relation to said viscosity increase in said direction that the shear stress at and along said membrane surface is maintained substantially constant and below said predetermined level.
-
62. In apparatus for separating fluid from a fluid suspension using a couette membrane filter having facing coaxial surfaces which together form a means for defining a gap therebetween, there being inlet means for introducing fluid into the gap, first outlet means for collecting fluid passing through the membrane, and other outlet means for removing fluid from the gap remotely from said inlet means, the combination comprising
(a) the filter including a membrane having pores to pass the fluid through the membrane from the gap side of the membrane to the opposite side thereof, (b) means to rotate one of said surfaces coaxially relative to the other, (c) means at said opposite side of the membrane for varying the resistance to flow of fluid passing through the membrane such that resistance to such flow increases at locations at said opposite side of the membrane corresponding to locations of gap increasing radial dimension, (d) and said means defining said gap to have increasing gap radial dimensions being in such relation to increase of fluid viscosity directionally toward said other outlet means that the shear stress in the fluid suspension at and along the membrane surface is maintained substantially constant.
Specification