ENVIRONMENTAL CONTROL SYSTEM UTILIZING AN ANION CONDUCTING MEMBRANE

Abstract

An environmental control system employs an electrolysis cell utilizing an anion conducting membrane. A power supply is coupled across the anode and cathode of the electrolysis cell to drive reactions to reduce oxygen and/or carbon dioxide in an output gas flow. A cathode enclosure may be coupled with the electrolysis cell and provide an input gas flow and receive the output gas flow. A first electrolysis cell may be utilized to reduce the carbon dioxide concentration in an output flow that is directed to a second electrolysis cell, that reduces the concentration of oxygen. The oxygen and/or carbon dioxide may be vented from the system and used for an auxiliary purpose. An electrolyte solution may be configured in a loop from a reservoir to the anode, to provide a flow of electrolyte solution to the anode. Moisture from the cathode may be collected and provided to the anode.

Claims

1. (canceled)

2. The environment control system of claim 21, wherein the anion conducting membrane is a composite anion conducting membrane comprising: a) a support material; and b) an anion conducting polymer coupled with the support material attached to the anion conducting polymer.

3. The environment control system of claim 21, wherein the oxygen depletion electrolysis cell reacts with oxygen on the cathode side of the oxygen depletion electrolysis cell to reduce an oxygen concentration in the cathode enclosure.

4. (canceled)

5. (canceled)

6. The environment control system of claim 21, wherein carbon dioxide is reacted on the cathode side of the carbon dioxide removal electrolysis cell to form HCO3− that is transferred through the anion conducting membrane of the carbon dioxide removal electrolysis cell as HCO.sub.3−, and then reformed via reaction on the anode catalyst layer of the carbon dioxide removal electrolysis cell to form carbon dioxide on the anode side.

7. The environment control system of claim 6, wherein the carbon dioxide on the anode side of the carbon dioxide removal electrolysis cell is vented from the electrolysis cell.

8. The environment control system of claim 21, wherein the electrolyte solution of at least one of the carbon dioxide removal electrolysis cell or the oxygen depletion electrolysis cell comprises hydroxide.

9. The environment control system of claim 21, wherein the electrolyte solution of at least one of the carbon dioxide removal electrolysis cell or the oxygen depletion electrolysis cell comprises a carbonate.

10. The environment control system of claim 21, further comprising an electrolyte solution reservoir wherein the electrolyte of the carbon dioxide removal electrolysis cell flows from electrolyte solution reservoir to the anode and back to the electrolyte solution reservoir to form an electrolyte loop.

11. The environment control system of claim 10, wherein the electrolyte loop comprises a pump to pump the electrolyte solution through the electrolyte loop.

12. The environment control system of claim 11, further comprising a water make-up system to supplies water to the electrolyte loop.

13. The environment control system of claim 12, wherein the water make-up system comprises a water reclamation device coupled with the cathode to produced reclaimed water that is supplied to the water make-up system and the electrolyte loop.

14. The environment control system of claim 13, wherein the water reclamation device comprises a condenser that condenses the water from the cathode.

15. The environment control system of claim 11, wherein oxygen is removed from the electrolyte loop.

16. The environment control system of claim 21, wherein an air moving device increases a flow of oxygen to the cathode catalyst layer of the carbon dioxide removal electrolysis cell.

17. The environment control system of claim 21, further comprising an electrolysis cell heater that heats at least a portion of the carbon dioxide removal electrolysis cell.

18. The environment control system of claim 17, wherein the electrolysis cell heater heats the anode side of the carbon dioxide removal electrolysis cell to improve kinetics of reaction of the anode catalyst layer of the carbon dioxide removal electrolysis.

19. The environment control system of claim 21, further comprising an electrolyte solution heater that heats the electrolyte solution of the carbon dioxide removal electrolysis cell.

20. The environment control system of claim 21, further comprising a scrubber that removes carbon dioxide from the cathode enclosure gas before entry into the cathode of the carbon dioxide removal electrolysis cell.

21. An environmental control system comprising: a cathode enclosure containing a cathode enclosure gas; a carbon dioxide removal electrolysis cell comprising: a) an anion conducting membrane; b) an anode configured on an anode side of the electrolysis cell and comprising: i) an anode catalyst layer; ii) a porous current collector; iii) an electrolyte solution in fluid communication with anode catalyst layer; c) a cathode configured on a cathode side of the electrolysis cell and comprising: i) a cathode catalyst layer; ii) a gas diffusion layer; iii) a cathode gas in fluid communication with the cathode catalyst layer; iv) a cathode enclosure coupled with the cathode; v) an inlet coupled with the cathode enclosure; vi) an outlet; an oxygen depletion electrolysis cell comprising: a) an anion conducting membrane; b) an anode configured on an anode side of the electrolysis cell and comprising: vii) an anode catalyst layer; viii) a porous current collector; ix) an electrolyte solution in fluid communication with anode catalyst layer, c) a cathode configured on a cathode side of the electrolysis cell and comprising: x) a cathode catalyst layer; xi) a gas diffusion layer; xii) a cathode gas in fluid communication with the cathode catalyst layer: xiii) an inlet coupled with the outlet of the carbon dioxide removal electrolysis cell; xiv) an outlet coupled with the cathode enclosure; wherein the cathode enclosure gas is fed to the inlet of the cathode of the carbon dioxide removal cell as an inlet gas and is reacted on the cathode of the carbon dioxide removal cell to produce a reduce carbon dioxide gas having a reduced carbon dioxide concentration from a carbon dioxide concentration of said inlet gas; wherein the reduce carbon dioxide gas passes from the outlet of the cathode of the carbon dioxide removal cell to the inlet of the cathode of the oxygen depletion cell; and wherein the reduce carbon dioxide gas reacts on the cathode of the oxygen depletion electrolysis cell to produce an outlet gas having a reduced oxygen concentration from an oxygen concentration of the reduce carbon dioxide gas; wherein the outlet gas passes from the outlet of the oxygen depletion electrolysis cell to the cathode enclosure; and wherein the environmental control system effectively reduces both carbon dioxide and oxygen levels in the cathode enclosure.

22. An environmental control system of claim 21, wherein the carbon dioxide from the anode of the carbon dioxide removal cell is fed to the enclosure, effectively maintaining a carbon dioxide level in the enclosure while reducing an oxygen level within the cathode enclosure.

23. A method of producing an inert gas flow comprising: providing an environmental control system comprising: a cathode enclosure containing a cathode enclosure gas; a carbon dioxide removal electrolysis cell comprising: a) an anion conducting membrane; b) an anode configured on an anode side of the electrolysis cell and comprising: i) an anode catalyst layer; ii) a porous current collector; iii) an electrolyte solution in fluid communication with anode catalyst layer; c) a cathode configured on a cathode side of the electrolysis cell and comprising: i) a cathode catalyst layer; ii) a gas diffusion layer; iii) a cathode gas in fluid communication with the cathode catalyst layer; iv) a cathode enclosure coupled with the cathode; v) an inlet coupled with the cathode enclosure; vi) an outlet; an oxygen depletion electrolysis cell comprising: a) an anion conducting membrane; b) an anode configured on an anode side of the electrolysis cell and comprising: vii) an anode catalyst layer; viii) a porous current collector; ix) an electrolyte solution in fluid communication with anode catalyst layer; c) a cathode configured on a cathode side of the electrolysis cell and comprising: x) a cathode catalyst layer; xi) a gas diffusion layer; xii) a cathode gas in fluid communication with the cathode catalyst layer: xiii) an inlet coupled with the outlet of the carbon dioxide removal electrolysis cell; xiv) an outlet coupled with the cathode enclosure; flowing the cathode enclosure gas to the inlet of the cathode of the carbon dioxide removal cell as an inlet gas wherein the inlet gas is reacted on the cathode of the carbon dioxide removal cell to produce a reduce carbon dioxide gas having a reduced carbon dioxide concentration from a carbon dioxide concentration of said inlet gas; flowing the reduce carbon dioxide gas from the outlet of the cathode of the carbon dioxide removal cell to the inlet of the cathode of the oxygen depletion cell, wherein the reduce carbon dioxide gas reacts on the cathode of the oxygen depletion electrolysis cell to produce an outlet gas having a reduced oxygen concentration from an oxygen concentration of the reduce carbon dioxide gas; flowing the outlet gas from the outlet of the oxygen depletion electrolysis cell to produce an inert gas flow.

24. The method of claim 23, further comprising providing a cathode enclosure and flowing the outlet gas into the cathode enclosure, wherein the environmental control system effectively reduces both carbon dioxide and oxygen levels in the cathode enclosure.

25. The method of claim 24, wherein the carbon dioxide from the anode of the carbon dioxide removal cell is fed to the cathode enclosure, thereby effectively maintaining a carbon dioxide level in the enclosure while reducing an oxygen level within the cathode enclosure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[0051] FIG. 1 shows an exemplary electrolysis cell diagram for an inerting system.

[0052] FIG. 2 shows an exemplary electrolysis cell diagram showing the operating principle of the inerting system.

[0053] FIG. 3 shows an exemplary electrolysis cell diagram showing the operating principle of the carbon dioxide removal system.

[0054] FIG. 4 shows an exemplary electrolysis cell diagram including an inerting system cathode connected to an enclosure, with an electrolyte loop circulating at the anode.

[0055] FIG. 5 shows an exemplary electrolysis cell diagram including the inerting system cathode connected to an enclosure, with an electrolyte loop circulating at the anode, and a water make-up source.

[0056] FIG. 6 shows an exemplary electrolysis cell diagram with a carbon dioxide removal cell in series with an oxygen removal cell.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0057] Referring to FIG. 1, an electrolysis cell 1 has a cathode 2 on the cathode side 21 and an anode 3 on the anode side 31. The anode and cathode are configured on opposing sides of an anion conducting membrane 10. The cathode is made up of a cathode chamber 4, a cathode gas diffusion layer 5, and a cathode catalyst layer 6. The anode comprises an anode chamber 7, an anode porous current collector 8, and an anode catalyst layer 9. The anion conducting membrane assembly 100 includes the anode catalyst layer, anion conducting membrane and the cathode catalyst layer, and may also include the cathode gas diffusion layer and the anode porous current collector. The anion conducting membrane 10 may be a composite anion conducting membrane and may include a support material 112, such as a support layer or membrane, and an anion conducting polymer 110. A composite anion conducting membrane may be more durable and robust and enable the anion conducting membrane to be made thinner. As shown in FIG. 1, a power supply 70 is coupled across the anode and cathode to produce a potential across the anode and cathode for driving electrolysis. It is to be understood that a power supply is required for the system but is not shown in subsequent figures for clarity.

[0058] Referring to FIG. 2, an electrolysis cell 1 has a cathode 2 and anode 3 configured on opposing sides of an anion conducting membrane 10. Water enters the anode of the system and is transferred across the anion conducting membrane to the cathode where it reacts with oxygen at the cathode side to form hydroxyl ions, as shown in the equation on the cathode side (2H.sub.2O+O.sub.2+4e.sup.−.fwdarw.4OH.sup.−). The hydroxyl ions are transported to the anode of the electrolysis cell and react to form water and oxygen as shown in the equation on the anode side of the electrolysis cell (4OH.sup.−.fwdarw.2H.sub.2O+O.sub.2+4e.sup.−). In this electrolysis cell oxygen is being reduced via reaction on the cathode side of the electrolysis cell. The cathode is made up of a cathode chamber 4, a cathode gas diffusion layer 5, and a cathode catalyst layer 6. The anode comprises an anode chamber 7, an anode porous current collector 8, and an anode catalyst layer 9.

[0059] Referring to FIG. 3, an electrolysis cell 1 has a cathode 2 on the cathode side 21 and an anode 3 on the anode side 31. The anode and cathode are configured on opposing sides of an anion conducting membrane 10. Water enters the anode of the system and is transferred across the anion conducting membrane to the cathode, and reacts with oxygen at the cathode side to form hydroxyl ions, as shown in the equation on the cathode side (2H.sub.2O+O.sub.2+4e.sup.−.fwdarw.4OH.sup.−). The hydroxyl ions react with carbon dioxide to form bicarbonate and carbonate. The hydroxyl ions, carbonate and bicarbonate transport to the anode of the electrolysis cell and react to form water, carbon dioxide, and oxygen. In this electrolysis cell carbon dioxide is being reduced via reaction on the cathode side of the electrolysis cell.

[0060] Also shown in FIG. 3, is an equilibrium reaction that occurs on the cathode side of the electrolysis cell, wherein carbon dioxide and hydroxyl groups react to form bicarbonate, (CO.sub.2+OH.sup.−.fwdarw.HCO.sub.3.sup.−). The bicarbonate ion is transferred across the anion conducting membrane to the anode side where it reforms carbon dioxide and hydroxyl groups (HCO.sub.3.sup.−.fwdarw.CO.sub.2+OH.sup.−).

[0061] Referring to FIG. 4, water and an electrolyte, an electrolyte solution 20, flow in an electrolyte loop 22 from an electrolyte solution reservoir 12 to the anode side 31 of the electrolysis cell 1 and back to the electrolyte solution tank. The electrolyte solution reservoir may be a closed loop for a period of time and may receive additional electrolyte solution periodically as required. On the cathode side, oxygen is removed from the cathode enclosure gas 55, that flows from the cathode enclosure 11 to the cathode. The reaction on the cathode side of the electrolysis cell is 2H.sub.2O+O.sub.2+4e.sup.−.fwdarw.4OH.sup.−, thereby forming a higher concentration of nitrogen in the cathode enclosure 11. Note, that the electrolysis cell 1 may be operated without a cathode enclosure and the cathode may receive a cathode inlet gas flow from the environment.

[0062] Referring to FIG. 5, a water make-up system 13 is attached to the electrolyte loop. The water make-up system adds water to the electrolyte loop 22 as water is transferred across the anion conducting membrane 10 to the cathode. The water make-up system maintains the pH of the electrolyte solution 20 in the electrolyte loop 22. The flow of electrolyte solution in the electrolyte loop may be controlled by the exit flow from the anode, as indicated by the bold arrow exiting the anode. The water make-up system may receive water from a water source 33, or may receive water that has been collected by a water reclamation device 30, such as a condenser. The water collected by the water reclamation device may be pumped by a pump 32 to the water make-up system 13 or electrolyte solution loop 22 through a conduit 34. Note that the water or moisture collected by water reclamation device may flow be gravity from the cathode side 21 to the water make-up system 13 coupled to the anode side 31.

[0063] Also shown in FIG. 5, is an optional electrolyte pump 14 that is connected to the electrolyte loop 22 to force flow of the electrolyte solution 20 to the anode chamber. An optional oxygen removal system 15 is connected to the electrolyte loop to remove additional oxygen from the closed loop. An exemplary oxygen removal system may allow the releast of oxygen from the anode side of the electrolysis cell, such as through venting. An exemplary oxygen removal system may draw oxygen from the head space 28 in the electrolyte solution reservoir 12 and/or may employ a check valve 25 and/or a selectively permeable membrane 27. An exemplary check valve may be a flap or a pressure controlled device that may open periodically or on a controlled schedule. An electrolyte solution sensor 29 may be configured to determine when additional electrolyte or water is required to replenish the system.

[0064] An exemplary electrolyte solution sensor may be a level sensor that detects when the electrolyte solution level drops below a certain level, or may be a pH sensor that measures the pH of the electrolyte solution and initiates replenishment when the pH exceeds a threshold level.

[0065] Carbon dioxide on the anode side may also be released from the anode side of the electrolysis cell, such as through venting from the head space. An exemplary carbon dioxide removal system may draw carbon dioxide from the head space 28 in the electrolyte solution reservoir 12 and/or may employ a check valve 25 and/or a selectively permeable membrane 27. An exemplary check valve may be a flap or a pressure controlled device that may open periodically or on a controlled schedule.

[0066] An electrolyte solution sensor heater 36 may be configured to heat the electrolyte solution 20 and an electrolyte solution temperature sensor 39 may monitor the electrolyte solution temperature and initiate heating through the controller 90, when the electrolyte solution temperature drops below a threshold level. An increased temperature of the electrolyte solution will increase the reaction rate as it improves the kinetics of reaction.

[0067] Also shown in FIG. 5, is an optional an air moving device 16 that is connected to the cathode feed side from the enclosure to improve oxygen flow to the cathode. An air moving device may be a fan, pump or other suitable device.

[0068] As shown in FIG. 5, an optional electrolysis cell heater 51 is configured to heat at least a portion of the cell, such as the anode, or the anode side of the anion conducting membrane assembly 100. An electrolysis cell temperature sensor 59 may monitor the electrolysis cell temperature and initiate heating through the controller 90, when the electrolysis cell temperature drops below a threshold level. An increased temperature of the electrolyte cell, and particularly the anode or the anode cathode layer will increase the reaction rate as it improves the kinetics of reaction.

[0069] A scrubber 40 may be configured between the cathode enclosure 11 and the cathode 2 to reduce and/or remove one or more of the components of the enclosure gas 55, such as carbon dioxide. A scrubber, such as a carbon dioxide scrubber, may be a piece of equipment that absorbs carbon dioxide (CO.sub.2). An exemplary carbon dioxide scrubber may comprise an amine scrubber that utilizes an amine to react with the carbon dioxide, a mineral scrubber that may utilize a mineral or zeolite to react with the carbon dioxide, a sodium hydroxide scrubber that utilizes sodium hydroxide to react with carbon dioxide, a lithium hydroxide that utilizes lithium hydroxide to react with carbon dioxide, an absorptive scrubber that uses an absorber, such as activated carbon or metal-organic frameworks (MOFs) to absorb the carbon dioxide.

[0070] An oxygen sensor 19 may be configured to monitor the oxygen level of the cathode side 21 and/or the cathode enclosure 11. The controller 90 may change the power provided to the electrolysis cell 1 when the oxygen level exceeds a threshold value.

[0071] A controller 90, may interface with the various components of the anion electrolysis cell 1 and may control when the components are turned on or activated as a function of sensor input. A cathode enclosure sensor 19 may monitor the concentration of gases within the cathode enclosure, such as oxygen, nitrogen and/or carbon dioxide and may provide input to the controller 90. The controller may change the potential between the anode and cathode or electrical current thereto to maintain a gas level within a desired gas concentration threshold.

[0072] Referring to FIG. 6, a first electrolysis cell 1 is in series with a second electrolysis cell 1′. The second electrolysis cell 1′ has a cathode 2′ and anode 3′ configured on opposing sides of an anion conducting membrane 10′. The cathode enclosure contains a cathode enclosure gas 55. The first electrolysis cell is carbon dioxide removal cell that receives an inlet gas 56 from the cathode enclosure 11 and removes carbon dioxide via reaction on the cathode to produce a reduce carbon dioxide gas 57. The reduce carbon dioxide gas is then fed to the second electrolysis cell 1′, an oxygen depletion cell, that produces an outlet gas 58 having a reduced oxygen concentration, wherein the reduce carbon dioxide gas is reacted on the cathode of the oxygen depletion cell to reduce an oxygen concentration from that of the reduce carbon dioxide gas. The outlet gas is then fed back to the cathode enclosure. Also, carbon dioxide from the carbon dioxide removal cell may be fed from the anode back to the enclosure, effectively maintaining the carbon dioxide levels in the enclosure while reducing the oxygen levels.

[0073] In an alternative embodiment, the inlet gas to the carbon dioxide reducing cell is from an ambient environment, or another enclosure wherein the inlet gas may be pre-treated or conditioned, such as by scrubbing to protect the catalyst of the catalyst layers. The outlet form the second electrolysis cell, the oxygen depletion cell, may flow to the cathode enclosure and the cathode enclosure may have a release vent, to enable a flow of conditioned and environmentally controlled gas to flow therethrough.

[0074] It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and/or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.