Method and apparatus for separation of SF6 from CF4 /air-containing gas stream
AssigneeAmerican Air Liquide, Inc.
InventorYao-En Li
Life of this patent
Estimating the term…
Abstract
A method and apparatus for the separation and recovery of SF6 from a gas mixture consisting essentially of SF6, CF4, and N2. The method and apparatus involve membrane separation to separate N2 from SF6 and CF4, and liquefaction to separate SF6 from CF4.
Claims29
A method for the separation of SF6 from a gas mixture consisting essentially of SF6, CF4, and N2, said method comprising the steps of:
- (a) contacting a gas mixture consisting essentially of SF6, CF4, and N2 with a membrane at conditions effective to obtain a permeate stream rich in N2 and a retentate stream rich in SF6 and CF4;
- (b) liquefying said retentate stream at conditions effective to obtain liquid SF6 and gaseous CF4;
- and
- (c) vaporizing said liquid SF6 to obtain a purified SF6 gas.
A method for purifying and recycling an insulating or dielectric gas mixture from electric power distribution equipment, said method comprising the steps of:
- (a) contacting a gas mixture consisting essentially of SF6, CF4, N2, and SF6 polar decomposition by-products from electric power distribution equipment with an adsorbent at conditions effective to adsorb said by-products and produce a gas mixture depleted in said by-products;
- (b) contacting said gas mixture depleted in said by-products with a membrane at conditions effective to obtain a permeate stream rich in N2 and a retentate stream rich in SF6 and CF4;
- (c) liquefying said retentate stream at conditions effective to obtain liquid SF6 and gaseous CF4;
- (d) vaporizing said liquid SF6 to obtain a purified SF6 gas;
- (e) mixing said purified SF6 gas with at least one of makeup SF6 gas and makeup N2 to form a purified SF6/N2 gas mixture;
- and
- (f) recycling said purified SF6/N2 gas mixture to said electric power distribution equipment.
An apparatus for the separation of SF6 from a gas mixture consisting essentially of SF6, CF4, and N2, said apparatus comprising:
- (a) at least one membrane separation unit which permeates N2 faster than SF6 and CF4;
- and
- (b) means for liquefying a retentate stream comprising SF6 and CF4 from said at least one membrane separation unit to form liquid SF6 and gaseous CF4.
An apparatus for purifying and recycling an insulating or dielectric gas mixture from electric power distribution equipment, said apparatus comprising:
- (a) at least one adsorption unit for adsorbing SF6 polar decomposition by-products from a gas mixture consisting essentially of SF6, CF4, and N2 from electric power distribution equipment;
- (b) at least one membrane separation unit which permeates N2 faster than SF6 and CF4;
- and
- (c) means for liquefying a retentate stream comprising SF6 and CF4 from said at least one membrane separation unit to form liquid SF6 and gaseous CF4;
- (d) a vaporizer for converting said liquid SF6 to a purified SF6 gas;
- (e) a mixer for mixing said purified SF6 gas with at least one of makeup SF6 gas and makeup N2 to form a purified SF6/N2 gas mixture;
- and
- (f) a conduit for recycling said purified SF6/N2 gas mixture to said electric power distribution equipment.
Dependencies are inferred from the claim text.