Rotary annular crossflow filter, degasser, and sludge thickener

• US 20090159523A1
• Filed: 12/20/2007
• Published: 06/25/2009
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Vorsana, Inc.
• Original Assignee: McCutchen Co.
• Inventors: McCutchen, Wilmot H.
• Granted Patent: US 7,757,866 B2
• Time in Patent Office: Days
• US Class Current: 210/360.100
• CPC Class Codes: B01D 2315/02 Rotation or turning
• CPC Class Codes: B01D 63/16 Rotary, reciprocated or vibrated modules
• CPC Class Codes: C02F 1/001 Processes for the treatment of water whereby the filtration technique is of importance C02F1/44 takes precedence; construction of filters in general B01D24/00 - B01D41/00
• CPC Class Codes: C02F 1/20 by degassing, i.e. liberation of dissolved gases degasification of liquids in general B01D19/00; arrangement of degassing apparatus in boiler feed supply F22D
• CPC Class Codes: C02F 1/385 by centrifuging suspensions centrifuges B04B
• CPC Class Codes: C02F 11/127 by centrifugation
• CPC Class Codes: C02F 2301/026 Spiral, helicoidal, radial
• CPC Class Codes: C02F 2303/04 Disinfection

Abstract

A rotating annular crossflow filter shears radially outward flowing axial feed between counter-rotating coaxial centrifugal impellers. A radial impedance of flow at the impeller periphery slows the radially outward flow and increases residence time of feed between the impellers. Shear lift ejects solids from the boundary layer at the filter surface, and ejected solids collect by centrifugation at the impeller periphery, where they thicken into a sludge and are extruded. Gases, oils, floating solids, and fractions having a specific gravity less than water evolve into radial vortices and are sucked radially inward and out from between the impellers by an axial pump. Three way phase separation proceeds continuously in one pass through a simple mechanical device having a long residence time for feed in the processing zone.

Opposing rugose portions of counter-rotating impeller surfaces cause audio frequency pressure pulses. At the impeller periphery, the pressure pulses milk liquid out of sludge. At the portion of the radial passage prior to the filter, pressure pulses evolve gases and degassed cavitation bubbles inactivate microbes. Degassing of the high energy forced periodic cavitation bubbles between the impellers removes the cushion of noncondensibles which would otherwise absorb energy on compression, therefore implosion becomes extremely violent and a barrage of high pressure pulses and ultraviolet light pulses inactivates microbes.

Applications include field water purification, municipal and industrial wastewater degassing and sludge thickening, swimming pool filtration, effluent dewatering, wine and beverage degassing and clarification, fruit crushing, olive oil dewatering, produced brine and drilling mud processing, manure slurry dewatering and degassing, and recovery of solvents and fine suspended solids from fluid mixtures such as wastewater from machining operations.

Claims

1. An apparatus for continuous three way phase separation of a fluid mixture, comprising:

counter-rotatable approximately disk shaped parallel centrifugal impellers, the impellers having a common axis of rotation at their center and defining between them a radial passage, the radial passage having a radial impedance for increasing residence time of fluid within the radial passage;

at least one of said impellers comprising at least one annular high shear crossflow filter disposed approximately parallel to said radial passage and distal to said impeller axis of rotation;

means connected to the impellers for causing counter-rotation about the axis of rotation at approximately equal but opposite angular velocity;

an axial suction pump;

an axial exhaust conduit communicating with the axial suction pump and with the radial passage at said impeller axis of rotation;

a feed conduit communicating with a fluid mixture feed source and with the radial passage at the axis of rotation.

2. The apparatus of claim 1, comprising an axial suction pump communicating with the axial exhaust conduit.

3. The apparatus of claim 2, wherein said axial suction pump is a steam eductor.

4. The apparatus of claim 1, comprising a shear thickening section at the periphery of the impellers and distal to the filter with respect to the axis of rotation.

5. The apparatus of claim 4, wherein said shear thickening section comprises rugose impeller portions.

6. The apparatus of claim 1, wherein said means for causing counter-rotation comprise a drive wheel and a motor connected thereto, the drive wheel engaging the impellers simultaneously at their periphery.

7. The apparatus of claim 1, wherein the impellers comprise opposite rugose portions between the filter and the axis of rotation.

10. The apparatus of claim 1, comprising a shear thickening section at the periphery of the radial passage.

11. The apparatus of claim 10, wherein said shear thickening section comprises opposed rugose portions of the centrifugal impeller and said surface.

8. Apparatus for microbial inactivation by cavitation, comprising:

at least one rotatable centrifugal impeller, the impeller having an axis of rotation at its center and comprising a rugose portion and an annular high shear crossflow filter, said filter disposed distal to said rugose portion with respect to the axis of rotation;

means connected to the impeller for causing rotation of the impeller about the axis of rotation and thereby causing flow of a fluid radially outward away from said axis of rotation and over said rugose portion to said filter;

a surface disposed approximately parallel to said impeller, the surface comprising a rugose portion opposing at least part of said rugose portion of the impeller and the surface and the impeller defining between them a radial passage, the radial passage having a radial impedance;

an axial exhaust conduit communicating with the radial passage at the axis of rotation;

an axial feed conduit communicating with the radial passage at the axis of rotation.

9. The apparatus of claim 8, comprising an axial suction pump communicating with the axial exhaust conduit.

12. The apparatus of claim 8, wherein said surface is a rotatable rugose centrifugal impeller connected to means for causing it to rotate in an opposite direction to said impeller.

13. An apparatus for continuous three way phase separation of a fluid mixture, comprising:

a centrifugal impeller, the impeller having an axis of rotation at its center, and the impeller comprising an annular high shear crossflow filter distal to the axis of rotation;

a static casing disposed opposite to said impeller and its filter such that the impeller and the casing define between them a radial passage, the radial passage having a radial impedance for increasing residence time of fluid within the radial passage and over the annular filter;

means connected to the impeller for causing rotation of the impeller and its annular filter about the axis of rotation and thereby causing flow of a fluid radially outward away from said axis of rotation and over the annular filter to the radial impedance;

an axial exhaust conduit communicating with the radial passage at the axis of rotation;

an axial feed conduit communicating with the radial passage at the axis of rotation.

14. The apparatus of claim 13, comprising an axial suction pump communicating with the axial exhaust conduit.

15. The apparatus of claim 14, wherein the axial suction pump is a steam eductor.

16. The apparatus of claim 13, comprising a check valve on the axial exhaust conduit.

17. The apparatus of claim 16, comprising an oil conduit communicating with the axial exhaust conduit before the check valve.

18. The apparatus of claim 13, comprising opposing rugose portions on the impeller and on the casing, the rugose portion on the impeller being between the filter and the axis of rotation.

19. The apparatus of claim 13, comprising means for shear thickening distal to the filter with respect to the axis of rotation.

20. The apparatus of claim 19, wherein said shear thickening means comprise opposed rugose portions on the impeller and on the casing.