Pumping or mixing system using a levitating magnetic element

• US 6,416,215 B1
• Filed: 12/14/1999
• Issued: 07/09/2002
• Est. Priority Date: 12/14/1999
• Status: Expired due to Term

• Current Assignee: University Of Kentucky Research Foundation (University of Kentucky)
• Original Assignee: University Of Kentucky Research Foundation (University of Kentucky)
• Inventors: Terentiev, Alexandre N.
• Primary Examiner(s): SOOHOO, TONY GLEN
• Application Number:
  US09/460,600
• Time in Patent Office: 938 Days
• Field of Search: 366/273, 366/274, 366/331, 366/325.5, 416/3, 416/500, 310/93, 310/103, 310/90.5, 417/420, 505/879, 505/888, 505/889, 505/892, 505/910, 505/911, 505/166, 505/165
• US Class Current: 366/273
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/419 the force acting on the blood contacting member being permanent magnetic, e.g. from a rotating magnetic coupling between driving and driven magnets
• CPC Class Codes: F16C 32/0438 with a superconducting body, e.g. a body made of high temperature superconducting material such as YBaCuO
• CPC Class Codes: F16C 37/005 of magnetic bearings
• CPC Class Codes: F16C 39/06 using magnetic means
• CPC Class Codes: Y10S 505/879 Magnet or electromagnet
• CPC Class Codes: Y10S 505/892 Magnetic device cooling

Abstract

A system capable of pumping or mixing relatively warm fluids using a rotating magnetic element or bearing levitated by a cold superconducting element is disclosed. The magnetic element or bearing carries at least one impeller and is placed in a fluid vessel positioned external to the outer wall of a cryostat or other housing for the superconducting element. A separate cooling source thermally linked to the superconducting element provides the necessary cooling to create the desired superconductive effects and induce levitation in the magnetic element or bearing. The outer wall or housing defines a chamber around the cold superconducting element that thermally isolates it from the vessel. To ensure that the desired level of thermal isolation is provided, this chamber is evacuated or filled with an insulating material. This thermal isolation allows for placement of the superconducting element in close proximity to the wall or housing adjacent to the vessel to achieve a significant reduction in the separation distance from the magnetic element or bearing. This enhances the magnetic stiffness and loading capacity of the levitating element or bearing. However, since the superconducting element is thermally isolated from the outer wall or housing, the vessel, and hence the magnetic element/bearing and fluid contained therein, are not exposed to the cold temperatures required to produce the desired superconductive effects and the resultant levitation. By using means external to the vessel to rotate and/or stabilize the magnetic element/bearing levitating in the fluid, the desired pumping or mixing action is provided.

Claims

1. A system for pumping or mixing a fluid in a vessel, comprising:

a magnetic element for placement in the vessel;

a superconducting element for levitating said magnetic element;

a wall defining a chamber around the superconducting element, said chamber thermally isolating the superconduction element from the vessel;

a cooling source thermally linked to said superconducting element;

a motive device for rotating said magnetic element,

whereby the fluid is pumped or mixed by the rotation of the magnetic element.

2. The system for pumping or mixing a fluid according to claim 1, wherein a vacuum is maintained in the chamber around said superconducting element to minimize thermal transfer to said wall and provide the desired thermal isolation.

3. The system for pumping or mixing a fluid according to claim 2, wherein said vacuum is at least 10⁻

3 torr.

4. The system for pumping or mixing a fluid according to claim 1, wherein said superconducting element is a high temperature superconducting element.

5. The system for pumping or mixing a fluid according to claim 4, wherein said high temperature superconducting element is fabricated of melt-textured Yttrium-Barium Copper Oxide (YBCO).

6. The system for pumping or mixing a fluid according to claim 1, wherein said cooling source is kept at a temperature of between 4.2 to 130 Kelvin.

7. The system for pumping or mixing a fluid according to claim 6, wherein said cooling source is kept at a temperature of between approximately 77 to 78 Kelvin.

8. The system for pumping or mixing a fluid according to claim 1, wherein said wall is the outer wall of a cryostat and said cooling source is a chamber in said cryostat holding liquid nitrogen.

9. The system for pumping or mixing a fluid according to claim 1, wherein said cooling source is a refrigerator.

10. The system for pumping or mixing a fluid according to claim 1, wherein said thermal link is provided by a rod extending between said superconducting element and said cooling source.

11. The system for pumping or mixing a fluid according to claim 1, wherein said levitating magnetic element is a magnetic bearing that further includes a first permanent magnet positioned adjacent to said superconducting element but external to said wall.

12. The system for pumping or mixing a fluid according to claim 11, wherein said first permanent magnet is disc shaped and polarized in the vertical direction to produce a symmetrical magnetic field.

13. The system for pumping or mixing a fluid according to claim 11, wherein said magnetic bearing further includes a second permanent magnet spaced from said first permanent magnet for forming a magnetic coupling with a drive magnet forming a part of said motive device, whereby said magnetic coupling serves to both transmit driving torque from said drive magnet to said magnetic bearing and stabilize the levitation of said magnetic bearing.

14. The system for pumping or mixing a fluid according to claim 13, wherein said magnetic bearing further includes at least one impeller mounted on a shaft extending substantially vertically between said first and second permanent magnets.

15. The system for pumping or mixing a fluid according to claim 13, wherein said motive device for said magnetic bearing includes a motor for rotating said drive magnet.

16. The system for pumping or mixing a fluid according to claim 13, wherein said second permanent magnet includes at least two submagnets that correspond to opposite polarity forming a part of said drive magnet, whereby said cooperating submagnets serve to stabilize said magnetic bearing during rotation.

17. The system for pumping or mixing a fluid according to claim 1, wherein said wall is below said magnetic element and the vessel rests atop said wall.

18. The system for pumping or mixing a fluid according to claim 1, wherein a gap is provided between said superconducting element and an inner surface of said wall of approximately 0.01 to 5 millimeters.

19. The system for pumping or mixing a fluid according to claim 1, wherein the vessel includes an inlet and an outlet, and further including at least one impeller associated with said magnetic element that creates an enhanced pumping action that forces fluid to move from said inlet to said outlet.

20. The system for pumping or mixing a fluid according to claim 1, wherein said vessel is completely sealed and said magnetic element serves to mix the fluid only.

21. The system for pumping or mixing a fluid according to claim 1, wherein the vertical center axis of rotation of the magnetic element is offset from the vertical center axis of the vessel.

22. A system for mixing a fluid, comprising:

a vessel for holding the fluid;

a magnetic element positioned in said vessel;

a superconducting element;

a housing defining a chamber around said superconducting element for thermally isolating said superconducting element from said vessel;

a cooling source thermally linked to said superconducting element; and

a motive device to rotate said magnetic element,

whereby the superconducting element is positioned adjacent to the vessel for levitating the magnetic element in the vessel and the rotation of the magnetic element creates the mixing action in the fluid.

23. The mixing system according to claim 22, wherein said chamber surrounding said superconducting element is evacuated to minimize thermal transfer to said housing and provide the desired thermal isolation.

24. The mixing system according to claim 22, wherein said vessel includes an inlet and an outlet, and said magnetic element includes at least one impeller that creates an enhanced pumping action that forces fluid to move from said inlet to said outlet.

25. The mixing system according to claim 22, wherein said vessel is completely sealed from the outside environment.

26. The mixing system according to claim 25, wherein said vessel and magnetic element are disposable.

27. A method of levitating and rotating and rotating a magnetic element in a vessel for the intended use of pumping or mixing at least a fluid, including a non-cryogenic fluid comprising:

placing the magnetic element in the vessel;

levitating the magnetic element in the vessel using a superconducting element positioned in an evacuated or insulated chamber and thermally linked to a cooling source; and

rotating the magnetic element in the vessel.

28. The method according to claim 27, further including the steps of placing said magnetic element in the vessel prior to introducing a fluid.

29. The method according to claim 27, including the step of completely sealing the vessel prior to rotating said magnetic element.

30. The method according to claim 27, further including the step of disposing of said magnetic element and/or said vessel when pumping or mixing is complete.

31. The method according to claim 27, further including the step of reusing the magnetic element and/or said vessel when pumping or mixing is complete.

32. An assembly for holding a fluid in a mixing system wherein a superconducting element levitates a mixing element and a motive device rotates the mixing element, comprising:

a sealed vessel capable of holding the fluid;

wherein the mixing element includes a magnet and is positioned in said sealed vessel such that it is capable of levitating in a non-contact fashion relative to the vessel in the absence of the fluid,

whereby said magnetic mixing element may be levitated in the vessel by the superconducting element and rotated by the motive device without the need for a shaft penetrating into the vessel and may be disposed of along with the vessel or reused when the mixing operation is complete.

33. The assembly according to claim 32, wherein the fluid is introduced into the vessel prior to sealing.

34. The assembly according to claim 32, wherein the fluid is introduced into the vessel after sealing.

35. A method of pumping or mixing a fluid, comprising:

placing a pumping or mixing element in a vessel and sealing the vessel;

levitating the magnetic element in the vessel using a superconducting element placed in a superconducting state in accordance with a field cooling protocol;

introducing the fluid into the vessel;

rotating the magnetic element,

whereby the active rotation of the levitating, magnetic pumping or mixing element serves to pump or mix the fluid in the vessel when present.

36. The method according to claim 35, wherein the vessel is formed of a disposable material, and further including the step of disposing of the vessel after at least a portion of the fluid is retrieved.

37. The method according to claim 35, wherein the step of levitating the pumping or mixing element includes positioning the superconducting element in an evacuated or insulated chamber and thermally linking the superconducting element to a cooling source.

38. The method according to claim 35, wherein the pumping or mixing element is a magnetic bearing including a levitation magnet for positioning adjacent to the superconducting element and at least two alternating polarity submagnets, and wherein the step of rotating the superconducting element includes positioning a motive device including a drive magnet structure adjacent to the vessel to form a magnetic coupling with the submagnets.

39. A system for pumping or mixing a fluid in a vessel, comprising:

a pumping or mixing structure for placement in the vessel, said pumping or mixing structure comprising first and second magnets and a support for supporting the magnets in a spaced configuration;

a superconducting element positioned adjacent to the vessel and the first magnet for levitating the pumping or mixing structure in the vessel;

a cryostat including a chamber for thermally isolating the superconducting element from the vessel;

a cooling source thermally linked to said superconducting element;

a motive device comprising one or more drive magnets for forming a magnetic coupling with the second magnet and rotating said magnetic pumping or mixing structure,

whereby the fluid is pumped or mixed by the rotation of the pumping or mixing structure.

40. The system according to claim 39, wherein the pumping or mixing structure further comprises at least one impeller or vane for enhancing the pumping or mixing action provided.

41. A system for pumping or mixing a fluid in a vessel, comprising:

a pumping or mixing structure for placement in the vessel, said pumping or mixing structure comprising a shaft carrying a levitation magnet at one end, at least one pair of alternating polarity driven magnets at the opposite end, and at least one impeller;

a superconducting element positioned adjacent to the vessel and the levitation magnet for levitating the pumping or mixing structure in the vessel;

a cryostat for thermally isolating the superconducting element from the vessel;

a cooling source thermally linked to the superconducting element;

a motive device including a motor for rotating a pair of alternating polarity driving magnets that form a magnetic coupling with the at least one pair of alternating polarity driven magnets,

whereby the rotation of the driving magnets serves to rotate the pumping or mixing structure via the magnetic coupling with the driven magnets.

42. The system according to claim 41, wherein the pumping or mixing structure comprises two pair of alternating polarity driven magnets and the motive device includes two pair of alternating polarity driving magnets.

43. A system for pumping or mixing a fluid, comprising:

a vessel having a first portion and a second portion;

a pumping or mixing structure for placement in the vessel, said pumping or mixing structure comprising a levitation magnet structure positioned adjacent to a first portion of the vessel and a driven magnet structure positioned adjacent to the second portion of the vessel;

a superconducting element positioned adjacent to the vessel and the levitation magnet structure for levitating the pumping or mixing structure;

a motive device including a motor for rotating one or more driving magnets that form a magnetic coupling with the driven magnet structure of said pumping or mixing structure;

a cryostat including a wall for supporting the vessel and defining a chamber for thermally isolating the superconducting element from the vessel and a cooling source thermally linked to the superconducting element in the chamber;

whereby the rotation of the driving magnet serves to rotate the pumping or mixing structure via the magnetic coupling.

44. The system according to claim 43, wherein the first and second portions of the vessel are spaced in a vertical direction.

45. A system for pumping or mixing a fluid in a vessel, comprising:

a pumping or mixing structure for placement in the vessel, said pumping or mixing structure comprising a shaft carrying a first magnet at one end, at least one pair of alternating polarity driven magnets at the opposite end, and at least one impeller;

a superconducting element positioned adjacent to the vessel and the first magnet for levitating the pumping or mixing structure in the vessel;

a cryostat including a wall defining a chamber for thermally isolating the superconducting element from the vessel and a cooling source thermally linked to the superconducting element in the chamber;

a motive device including a motor for rotating a pair of alternating polarity driving magnets that form a magnetic coupling with the at least one pair of alternating polarity driven magnets,

whereby the rotation of the driving magnets serves to rotate the pumping or mixing structure via the magnetic coupling with the driven magnets.

46. An assembly for holding a fluid for intended use in a pumping or mixing system having a levitation device that levitates a pumping or mixing structure and a motive device including a driving magnet structure rotates the pumping or mixing structure, comprising:

a vessel capable of holding the fluid;

wherein the pumping or mixing structure comprises a shaft carrying a first magnet at one end, at least one pair of alternating polarity driven magnets at the opposite end, and at least one impeller;

whereby the first magnet of said pumping or mixing structure may be levitated in the vessel in a non-contact fashion by the levitation device and the alternating polarity driven magnets may be rotated by driving magnet of the motive device, both without the need for a shaft penetrating into the vessel.

47. The assembly according to claim 46, wherein the vessel is formed of a disposable material.

48. The assembly according to claim 46, wherein the vessel is sealed after the pumping or mixing element is positioned therein.

49. The assembly according to claim 46, wherein the vessel is unsealed prior to use to introduce a fluid therein.

50. The assembly according to claim 46, wherein the vessel is selected from the group consisting of an open-top container, a container having an inlet and an outlet, and a sealed container.

51. A structure for intended use in mixing a fluid using a system wherein a superconducting element levitates a mixing element and a motive device rotates the mixing element, comprising:

a mixing vessel for holding the fluid during mixing, said vessel having a sealable opening, no pre-defined outlet, and a substantially planar bottom surface;

wherein the mixing element includes a levitation magnet and is positioned in the vessel such that it is capable of levitating in a non-contact fashion substantially and entirely above the planar bottom surface in the absence of a fluid;

whereby the mixing element may be levitated in the vessel by the superconducting element and rotated by the motive device without the need for a shaft penetrating into the vessel and may be disposed of along with the vessel or reused when the mixing operation is complete.

52. The structure according to claim 51, wherein the sealable opening is provided in an upper portion of the vessel.

53. The structure according to claim 51, wherein the motive device includes a driving magnet structure, and the mixing element comprises a shaft carrying a disc-shaped permanent magnet at one end corresponding to the superconducting element, at least one pair of alternating polarity driven magnets at the opposite end corresponding to the driving magnet structure of the motive device, and at least one impeller.

54. A structure for intended use in pumping or mixing a fluid in a vessel in a non-contact fashion using a levitation device external to the vessel for providing a levitating force and a motive device external to the vessel for imparting rotary motion including a driving magnet structure, comprising:

a levitation magnet structure positioned adjacent to the levitation device;

a driven magnet structure positioned adjacent to the motive device, said driven magnet structure forming a magnetic coupling with the driving magnet structure;

a connector for connecting the levitation and driven magnet structures,

whereby supplying the levitation and rotation of the structure externally avoids the need for shafts penetrating into or through the vessel or corresponding mechanical support bearings or seals.

55. The structure according to claim 54, wherein the driven magnet structure comprises at least one pair of alternating polarity magnets, whereby the magnets each form a portion of the magnetic coupling with the driving magnet structure on the motive device.

56. The structure according to claim 54, wherein the connector is a shaft that maintains the levitation and driving magnets in a vertically spaced relationship.

57. The structure according to claim 54, further including at least one impeller on the connector.

58. A method of levitating and rotating a magnetic structure in a vessel for the intended use of pumping or mixing at least a fluid, including a non-cryogenic fluid, comprising:

placing the magnetic structure in the vessel, said magnetic structure comprising a shaft carrying a levitation magnet at one end, at least one pair of alternating polarity driven magnets at the opposite end, and at least one impeller;

levitating the magnetic structure in the vessel using a superconducting element positioned in an evacuated or insulated chamber adjacent to the levitation magnet and thermally linked to a separate cooling source; and

rotating the magnetic structure in the vessel by forming a magnetic coupling between a driving magnet structure on the motive device and the alternating polarity driven magnets of the magnetic structure.

59. A system for pumping or mixing a fluid in a vessel, comprising:

a magnetic element for placement in the vessel;

a superconducting element for levitating said magnetic element;

a structure defining a chamber around the superconducting element, said chamber being evacuated or insulated to thermally isolate the superconducting element from the vessel;

a closed-cycle refrigerator thermally linked to said superconducting element;

a motive device for rotating said magnetic element,

whereby the fluid is pumped or mixed by the rotation of the magnetic element.

60. The system according to claim 59, wherein the motive device includes a driving magnet structure, and the magnetic element comprises a shaft carrying a disc-shaped permanent magnet at one end corresponding to the superconducting element, at least one pair of alternating polarity driven magnets at the opposite end corresponding to the driving magnet structure of the motive device, and at least one impeller for creating a pumping or mixing action in the fluid.