Claims
- 1. A process for separating a mixture of SF6 and N2, the SF6/N2 mixture being obtained from a gas insulated line, comprising introducing the mixture to a mobile membrane separator comprising at least one separating membrane which preferentially passes N2, collecting an SF6 enriched retentate, and forming an N2 enriched permeate, wherein said mixture has an initial SF6 content of from 5 to 50 volume-%, said at least one membrane comprises a polymer matrix composed of a polycarbonate made from a bisphenol in which at least 25% of the bisphenol units in the polymer chain are tetrahalogenated with chlorine or bromine, and said mixture is fed to said membrane separator at a membrane feed pressure of 10 to 13 bar.
- 2. A process according to claim 1, wherein said membrane separator comprising at least one separating membrane comprises at least two separating membrane stages.
- 3. A process according to claim 2, wherein said membrane separator comprising at least two separating membrane stages comprises three separating membrane stages, the retentate of the first membrane stage is fed to the second membrane stage in order to obtain a mixture with a high SF6 content as retentate from the second membrane stage; the permeate of the first membrane stage is introduced into the third membrane stage; the permeate of the second membrane stage and the retentate of the third membrane stage are recirculated to the feed stream of the first membrane stage, and the permeate of the third membrane stage can be released into the environment.
- 4. A process according to claim 1, wherein the process is utilized during the use of the gas insulated line to purify the SF6/N2 mixture.
- 5. A process according to claim 1, wherein the process is utilized after completed use of the gas insulated line in order to recover SF6 prior to disposal of the used gas insulated line.
- 6. A method according to claim 1, wherein said N2 enriched permeate comprises at least about 97% by volume nitrogen.
- 7. A method according to claim 6, wherein said N2 enriched permeate comprises at least about 99% by volume nitrogen.
- 8. A method according to claim 1, wherein said SF6 enriched retentate comprises at least about 95% by volume sulfur hexafluoride.
- 9. A method according to claim 1, further comprising discharging said N2 enriched permeate directly to the atmosphere.
- 10. A system comprising a gas insulated line, a membrane separation stage comprising at least one separating membrane which preferentially passes N2, and at least one connecting line directly connecting the gas insulated line to the membrane separation stage, wherein said membrane separation stage is a mobile membrane separation apparatus, wherein said gas insulated line contains a mixture of SF6 and N2 with an initial SF6 content of from 5 to 50 volume-%, and wherein said at least one connecting line delivers the mixture to said membrane separation stage at a membrane feed pressure of 10 to 13 bar.
- 11. A system according to claim 10, wherein said at least one separating membrane comprising a polymer matrix composed of a polycarbonate made from a bisphenol in which at least 25% of the bisphenol units in the polymer chain are tetrahalogenated with chlorine or bromine.
- 12. A system according to claim 10, further comprising a pump or compressor on said connecting line for moving a gas mixture from said gas insulated line to said membrane separation stage.
- 13. A system according to claim 10, further comprising a discharge line connected to said membrane separation stage to discharge said N2 enriched permeate directly to the atmosphere.
Priority Claims (1)
Number |
Date |
Country |
Kind |
199 23 155 |
May 1999 |
DE |
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of international application no. PCT/EP00/00979, filed Feb. 8, 2000, designating the United States of America, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application no. DE 199 23 155.9, filed May 20, 1999.
US Referenced Citations (17)
Foreign Referenced Citations (3)
Number |
Date |
Country |
754487 |
Jan 1997 |
EP |
853970 |
Jul 1998 |
EP |
885841 |
Dec 1998 |
EP |
Continuations (1)
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Number |
Date |
Country |
Parent |
PCT/EP00/00979 |
Feb 2000 |
US |
Child |
09/988820 |
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US |