Apparatus for extracting a gas from a liquid and delivering the gas to a collection station

• US 5,749,942 A
• Filed: 02/14/1997
• Issued: 05/12/1998
• Est. Priority Date: 02/14/1997
• Status: Expired due to Fees

• Current Assignee: Underground Systems, Inc.
• Original Assignee: Raychem Limited (TE Connectivity Limited)
• Inventors: Bliven, David C., Mattis, John Seymour
• Primary Examiner(s): SPITZER, ROBERT H
• Application Number:
  US08/798,283
• Time in Patent Office: 452 Days
• Field of Search: 95/46, 96/4, 96/6, 96/11-14
• US Class Current: 95/46
• CPC Class Codes: B01D 19/0031 by filtration
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 61/00 Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor separation of gases or vapours by diffusion B01D53/22

Abstract

An apparatus (10) and a method are described for extracting gas from a liquid containing dissolved gas. The liquid is pumped from an external reservoir (40) of the liquid into a separation cell (14) by a liquid-pumping chamber (11). In separation cell (14) a permselective membrane (17) effects extraction of the dissolved gas from the liquid. A gas-pumping chamber (23) pumps the extracted gas from the permeate chamber (16) of the separation cell (14) to a collection station (27), where the extracted gas can be analyzed, separated into its individual components, or stored, as desired.

Claims

1. A method for extracting dissolved gas from a gas-containing liquid and delivering the extracted gas to a collection station, comprising the steps of:

(a) providing an external reservoir of a gas-containing liquid having at least one gas dissolved therein;

(b) providing a separation cell partitioned into a feed chamber and a permeate chamber by a permselective membrane which permits the at least one gas to diffuse thereacross but is substantially impermeable to the gas-containing liquid;

(c) circulating the gas-containing liquid between the external reservoir and the feed chamber, the circulating action being provided by a liquid pumping chamber wherein

(i) an elastic first diaphragm forms a wall of the liquid pumping chamber; and

(ii) a reciprocable first actuator is attached to the first diaphragm, the first actuator pressing the first diaphragm inwardly during its forward stroke and pulling the first diaphragm outwardly during its reverse stroke;

(d) permitting the at least one gas to diffuse across the permselective membrane and collect in the permeate chamber as extracted gas;

(e) circulating the extracted gas between the permeate chamber and a collection station, the pumping action being provided by a gas pumping chamber wherein

(i) an elastic second diaphragm forms a wall of the gas pumping chamber; and

(ii) a reciprocable second actuator is attached to the second diaphragm, the second actuator pressing the second diaphragm inwardly during its forward stroke and pulling the second diaphragm outwardly during its reverse stroke;

wherein the reciprocating action of the first and second reciprocable actuators is provided by a lever-and-fulcrum combination in which the lever is connected to the first and second reciprocable actuators such that rocking the lever causes a reciprocating action in the first and second actuators, with the first actuator being in its forward stroke when the second actuator is in its reverse stroke and vice-versa;

the rocking action of the lever being provided by a drive means for rocking the lever.

2. A method according to claim 1, wherein the external reservoir is a transformer.

3. A method according to claim 2, wherein the gas-containing liquid is a hydrocarbon oil or a silicone oil.

4. A method according to claim 2, wherein the at least one gas is selected from the group consisting of carbon monoxide, carbon dioxide, hydrogen, water vapor, methane, ethane, ethylene, and acetylene.

5. A method according to claim 2, wherein the at least one gas is a combination of at least each of carbon monoxide, carbon dioxide, hydrogen, methane, ethane, ethylene, and acetylene.

6. A method according to claim 1, wherein the permselective membrane comprises an amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer.

7. A method according to claim 6, wherein the amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer is perfluoro-2,2-dimethyl-1,3-dioxole homopolymer.

8. A method according to claim 6, wherein the amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer is a copolymer of perfluoro-2,2-dimethyl-1,3-dioxole and at least one comonomer selected from the group consisting of tetrafluoroethylene, perfluoromethyl vinyl ether, vinylidene fluoride, and chlorotrifluoroethylene;

the perfluoro-2,2-dimethyl-1,3-dioxole constituting between 65 and 99 mole % of the copolymer.

9. A method according to claim 1, wherein the permselective membrane is a composite membrane in which a layer of an amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer is supported on a porous support material.

10. A method according to claim 9, wherein the support material is made of vinylidene difluoride homopolymer or copolymer.

11. A method according to claim 1, wherein the permselective membrane comprises polytetrafluoroethylene.

12. An apparatus for extracting dissolved gas from a gas-containing liquid and delivering the extracted gas to a collection station, comprising:

(a) a liquid pumping chamber having a wall formed of an elastic first diaphragm;

(b) a reciprocable first actuator attached to the first diaphragm, the first actuator pressing the first diaphragm inwardly during its forward stroke and pulling the first diaphragm outwardly during its reverse stroke;

(c) a separation cell partitioned into a feed chamber and a permeate chamber by a permselective membrane which, when a gas-containing liquid having at least one gas dissolved therein is introduced into the feed chamber, permits the at least one dissolved gas to diffuse thereacross and collect in the permeate chamber as extracted gas, but is substantially impermeable to the gas-containing liquid;

(d) a first liquid conduit, for connecting the liquid pumping chamber to an external reservoir of the gas-containing liquid;

(e) a second liquid conduit, for connecting the feed chamber to the external reservoir;

(f) a liquid transfer conduit connecting the liquid pumping chamber and the feed chamber;

(g) first and second check valves controlling the flow of the gas-containing liquid through the first liquid conduit and the liquid transfer conduit, respectively;

one of the first and second check valves being oriented to permit flow of the gas-containing liquid into the liquid pumping chamber and the other of the first and second check valves being oriented to permit flow of the gas-containing liquid out of the liquid pumping chamber;

(h) a gas pumping chamber having a wall formed of an elastic second diaphragm;

(i) a reciprocable second actuator attached to the second diaphragm, the second actuator pressing the second diaphragm inwardly during its forward stroke and pulling the second diaphragm outwardly during its reverse stroke;

(j) a first gas conduit, for connecting the gas pumping chamber to an external collection station for extracted gas;

(k) a second gas conduit, for connecting the permeate chamber to the external collection station;

(l) a gas transfer conduit connecting the gas pumping chamber and the permeate chamber;

(m) third and fourth check-valves controlling the flow of extracted gas through the first gas conduit and the gas transfer conduit, respectively;

one of the third and fourth check valves being oriented to permit flow of extracted gas into the gas pumping chamber and the other of the third and fourth check valves being oriented to permit flow of extracted gas out of the gas pumping chamber;

(n) a lever-and-fulcrum combination wherein the lever is connected to the first and second reciprocable actuators such that rocking the lever causes a reciprocating action in the first and second actuators, with the first actuator being in its forward stroke when the second actuator is in its reverse stroke and vice-versa; and

(o) drive means for rocking the lever.

13. An apparatus according to claim 12, wherein the permselective membrane comprises an amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer.

14. An apparatus according to claim 13, wherein the amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer is perfluoro-2,2-dimethyl-1,3-dioxole homopolymer.

15. An apparatus according to claim 13, wherein the amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer is a copolymer of perfluoro-2,2-dimethyl-1,3-dioxole and at least one comonomer selected from the group consisting of tetrafluoroethylene, perfluoromethyl vinyl ether, vinylidene fluoride, and chlorotrifluoroethylene;

the perfluoro-2,2-dimethyl-1,3-dioxole constituting between 65 and 99 mole % of the copolymer.

16. An apparatus according to claim 12, wherein the permselective membrane is a composite membrane in which a layer of an amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer is supported on a porous support material.

17. An apparatus according to claim 16, wherein the support material is made of vinylidene difluoride homopolymer or copolymer.

18. An apparatus according to claim 12, wherein the permselective membrane comprises polytetrafluoroethylene.

19. An apparatus according to claim 12, wherein the permselective membrane is sandwiched between a pair of membrane holders each comprising a perforated base having a rubber edging, the rubber edging gripping the edges of the permselective membrane.

20. An apparatus according to claim 12, wherein the permeate chamber contains a bracing plate which helps prevent the permselective membrane from being distorted by a pressure differential thereacross but permits movement of the extracted gas.