SEPARATION OF FLUIDS BY DIFFUSION THROUGH SEMIPERMEABLE MEMBRANES

• US 3,651,618 A
• Filed: 05/20/1970
• Issued: 03/28/1972
• Est. Priority Date: 05/20/1969
• Status: Expired due to Term

• Current Assignee: Gunter Klein, Johann Neumann
• Original Assignee: Gunter Klein, Johann Neumann
• Inventors: Klein, Gunter, Neumann, Johann
• Primary Examiner(s): Hart, Charles N.
• Application Number:
  US05/039,124
• Time in Patent Office: 678 Days
• Field of Search: 55/16,58 210/23,321
• US Class Current: 95/44
• CPC Class Codes: B01D 53/226 in serial connexion

Abstract

In a process comprising diffusing a fluid through the upstream side of a semipermeable membrane having upstream and downstream sides, to the downstream side, the improvement comprising exposing the downstream side during said diffusing to either a liquid which does not wet the downstream side, or to the vapor of said liquid, whereby the rate of diffusion of said fluid through said membrane is increased and wherein said semipermeable membrane is a microporous sintered material, e.g., polytetrafluoroethylene having a pore diameter of 1-1,000, preferably 5-200 microns.

Claims

2. A process as defined by claim 1 wherein said fluid is a mixture of components having different diffusivities, whereby said fluid is enriched in at least one of said components.

3. A process according to claim 1 wherein the membrane is a lyophobic organic polymer.

4. A process according to claim 1 wherein the membrane is a sintered hydrophobic synthetic material and is exposed on the downstream side to liquid water or saturated steam.

5. A process according to claim 1 wherein said fluid is normally gaseous.

6. A process according to claim 1, further comprising maintaining a temperature gradient across the membrane, the downstream side having the higher temperature.

7. A process according to claim 1, further comprising maintaining a pressure gradient across the membrane, the downstream side having the higher pressure.

8. A process according to claim 1 wherein the membrane has a textured surface.

9. Apparatus suitable for separating a gas into its components, said apparatus comprising a plurality of diffusion cells, each of said cells being subdivided into a gas feed chamber and a gas discharge chamber by a microporous sintered plastic membrane, with said chamber being provided with conduit means for effecting series communication between said cells, said conduit means comprising conduit for connecting the gas discharge chamber of each diffusion cell disposed upstream with the gas feed chamber of the subsequent diffusion cell, and further comprising cooler means and expansion valve disposed serially in association with said conduit.

10. Apparatus according to claim 9, said conduit means further comprising conduit between the gas feed chamber of each diffusion cell with the gas feed chamber of each diffusion cell arranged upstream thereof in the gaseous flowpath.

11. A process as defined by claim 1, said membrane having micropores of about 1 to 1,000 microns in diameter.

12. A process as defined by claim 1, said membrane having micropores of about 5 to 200 microns in diameter.

13. A process as defined by claim 1, said membrance consisting of polytetrafluoroethylene.

14. A process as defined by claim 11, said membrane consisting of polytetrafluoroethylene.

15. A process as defined by claim 1, said membrane comprising at least 50 percent by volume of polytetrafluoroethylene.

16. A process as defined by claim 1, said membrane comprising at least 70 percent by volume of polytetrafluoroethylene.

17. A process as defined by claim 1, said downstream side of said membrane being exposed to said vapor of a liquid which does not wet the downstream side.

18. A process as defined by claim 17, said membrane comprising at least 50 percent by volume of polytetrafluoroethylene and having micropores of a diameter of 1 to 1,000 microns.

19. A process as defined by claim 1, said upstream side of said membrane being dry.

20. A process as defined by claim 19, said membrane comprising at least 50 percent by volume of polytetrafluoroethylene and having micropores of a diameter of 1 to 1,000 microns.