Rotating concentric homogeneous turbulence centrifuge

• US 3,998,610 A
• Filed: 12/12/1974
• Issued: 12/21/1976
• Est. Priority Date: 11/15/1971
• Status: Expired due to Term

• Current Assignee: Cominco Ltd. (Quebec)
• Original Assignee: Cominco Ltd. (Quebec)
• Inventors: Leith, William Cumming
• Primary Examiner(s): Krizmanich, George H.
• Application Number:
  US05/532,080
• Time in Patent Office: 740 Days
• Field of Search: 233/2, 233/3, 233/DIG. 1, 233/7, 233/11, 233/23 R, 233/27, 233/31, 233/37, 233/43, 233/1 A, 233/15, 55/17, 55/400
• US Class Current: 95/35
• CPC Class Codes: B01D 59/20 Separation by centrifuging
• CPC Class Codes: B04B 15/02 for cooling, heating, or heat insulating
• CPC Class Codes: B04B 3/00 Centrifuges with rotary bowls in which solid particles or bodies become separated by centrifugal force and simultaneous sifting or filtering
• CPC Class Codes: B04B 5/08 Centrifuges for separating predominantly gaseous mixtures
• CPC Class Codes: Y10S 494/90 involving mixture containing one or more gases

Abstract

A gas centrifuge and method for the separation of isotopic gaseous mixtures, particularly for the enrichment of uranium by the evaporative, concurrent-flow and countercurrent-flow principles using Taylor circular Couette motion. Gaseous isotopes either alone or mixed with a carrier gas, more particularly uranium isotopes in mixture with uranium hexafluoride carrier gas, are fed to a rotor assembly of a gas centrifuge which comprises two concentric cylinders which may be rotated at the same or at different angular velocities and in the same or opposite directions to create centrifugal forces sufficient to diffuse the heavier fraction of the gas mixture to the periphery of the assembly and the lighter fraction towards the axial portion of the assembly. The rotor comprises an inner, perforate, rotatable cylinder and an outer, continuous, smooth-walled, rotatable cylinder concentric with the inner cylinder and defining an annulus therebetween.

Claims

1. A method for separating and enriching mixtures of gases based on differences between the molecular weights of gases in said mixture in a gas centrifuge having an inner, perforate, rotatable cylinder and an outer, continuous, smooth-walled, rotatable cylinder concentric with said inner cylinder defining an annulus therebetween, the radius of the inner cylinder being in the range of from about 0.70 to about 0.95 of the radius of the outer cylinder;

said method comprising the steps of feeding a mixture of gases into said annulus in the centrifuge;

rotating said inner and outer rotatable concentric cylinders at peripheral velocities to separate the mixture of gases into a lighter fraction and a heavier fraction;

establishing a multiple array of cellularly-shaped stationary vortices in the gases in the annulus, whereby the residence time of the gases in the annulus is increased;

removing the lighter fraction from the inner area of the annulus; and

, removing the heavier fraction from the peripheral area of the annulus.

2. A method as claimed in claim 1 wherein the inner cylinder is rotated with an angular velocity in the range of about 1.0 to 3.3 times the angular velocity of the outer cylinder.

3. A method as claimed in claim 2 wherein the inner and outer cylinders are rotated at different angular velocities sufficient to attain peripheral velocities in the range of from about 80 to about 600 meters per second.

4. A method as claimed in claim 2 wherein the inner and outer cylinders are rotated at the same angular velocities in the same direction and wherein the inner and outer cylinders are rotated at an angular velocity sufficient to attain peripheral velocities in the range of from about 400 to about 600 meters per second.

5. A method as claimed in claim 3 wherein the inner and outer cylinders are rotated in the same direction.

6. A method as claimed in claim 5 wherein the inner cylinder is rotated at an angular velocity sufficient to attain a peripheral velocity in the range of from about 400 to about 600 meters per second and the outer cylinder is rotated at an angular velocity sufficient to attain a peripheral velocity in the range of from about 80 to about 570 meters per second.

7. A method as claimed in claim 3 wherein the inner and outer cylinders are rotated in opposite directions.

8. A method as claimed in claim 7 wherein the inner cylinder is rotated at an angular velocity sufficient to attain a peripheral velocity in the range of from about 400 to about 600 meters per second and the outer cylinder is rotated at an angular velocity sufficient to attain a peripheral velocity in the range of from about 80 to about 570 meters per second.

9. A process as claimed in claim 1 wherein the mixture of gases contains one or more of U235 and U238 in uranium hexafluoride.

10. A method as claimed in claim 1 wherein the mixture of gases is fed into said annulus through the inner, perforate cylinder.

11. A method as claimed in claim 1 wherein the mixture of gases is fed directly into the annulus at one end thereof, and said lighter and heavier fractions are removed from the annulus at an opposite end thereof.

12. A method as claimed in claim 1 wherein the mixture of gases is fed directly into the annulus at opposite ends thereof, and said lighter and heavier fractions are removed from the annulus at opposite ends thereof.

13. A gas centrifuge for separating and enriching mixtures of gases based on differences between the molecular weights of gases in said mixture comprising, in combination, an enclosure having a shaft mounted therein for introducing said gas mixture axially into said enclosure, a rotor assembly arranged coaxially around said shaft comprising an outer, imperforate, cylindrical wall and an inner, perforated cylindrical wall coaxial with said shaft, closure means at each end of said cylindrical walls for capping said cylinders whereby an annulus is defined between said cylinders, means for rotating said cylinders at peripheral velocities in the range of from about 80 to about 600 meters per second whereby a mixture of gases introduced axially into said centrifuge is separated into a lighter fraction and a heavier fraction, the radius of the inner cylinder being in the range from about 0.70 to about 0.95 of the radius of the outer cylinder, and means for discharging separated gases from the periphery of the annulus and from the inner portion of the annulus.

14. A gas centrifuge as claimed in claim 13, means for rotating the inner cylinder and means for rotating the outer cylinder independently of each other.