Regenerative carbon dioxide (CO2) removal system

• US 6,709,483 B1
• Filed: 10/07/2002
• Issued: 03/23/2004
• Est. Priority Date: 10/07/2002
• Status: Expired due to Term

• Current Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Hodgson, Edward W. Jr.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US10/265,495
• Time in Patent Office: 533 Days
• Field of Search: 95/51, 95/98, 951/01--05, 951/39, 96/4, 961/27--30, 961/32, 961/34--36, 961/42--44
• US Class Current: 95/51
• CPC Class Codes: B01D 2256/22 Carbon dioxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 2259/4575 in aeroplanes or space ships
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A carbon dioxide (CO₂) adsorption membrane or bed is operative to separate metabolic CO₂ from an exhaust stream from a breathable atmosphere which is discharged from a closed habitable environment. The habitable environment is in a low ambient pressure surrounding. A portion of the scrubbed exhaust gas stream is diverted from the habitable environment and passed through a desorption chamber. The desorption chamber is open to the low ambient pressure surrounding to maintain a pressure which is slightly greater than the pressure in the ambient surrounding so that the desorption chamber gas stream will exit the system into the ambient surroundings. When the diverted exhaust gas enters the low pressure desorption pressure chamber its CO₂ partial pressure content is reduced. The reduced CO₂ partial pressure content of the gas stream in the desorption chamber enables the desorption chamber gas stream to remove CO₂ from the adsorption membrane or bed.

Claims

1. A method for stripping metabolic carbon dioxide (CO₂) from a CO₂ sorbent material, said method comprising;

a) the step of providing a gas stream which contains metabolic CO₂;

b) the step of volumetrically expanding a portion of said gas stream so as to reduce CO₂ partial pressure in the portion of said gas stream to a CO₂ partial pressure which is operative to strip CO₂ from said sorbent material; and

c) the step of passing said portion of said gas stream past said CO₂ sorbent material so as to strip CO₂ from said CO₂ sorbent material.

2. The method of claim 1 further comprising the step of providing a vent for discharging CO₂-containing gas to a low pressure ambient environment.

3. The method of claim 1 wherein said portion of the gas stream is operative to remove CO₂ from said sorbent at the same rate that the sorbent removes metabolic CO₂ from the gas stream.

4. The method of claim 1 wherein the CO₂-containing gas stream is derived from a habitable environment which is pressurized to a pressure of approximately 200 mm Hg and the ambient environment has an ambient pressure in the range of about 6 to about 9 mm Hg.

5. The method of claim 1 wherein said sorbent material is a CO₂-permeable membrane.

6. The method of claim 1 wherein said sorbent material is a porous material which is coated with a CO₂ adsorbent material.

7. A method for removing metabolic carbon dioxide (CO₂) from a breathable atmosphere which is contained in a dosed habitable environment, said method comprising:

a) the step of removing a portion of the atmosphere from said habitable environment to form a gas stream;

b) the step of passing the gas stream through a CO₂ adsorbant station so as to remove CO₂ from the gas stream to form an essentially CO₂-free gas stream;

c) the step of returning a first portion of the essentially CO₂-free gas stream to the habitable environment; and

d) the step of passing a second volumetrically expanded portion of the essentially CO₂-free gas stream through a CO₂ desorption station so as to lower CO₂ partial pressure in said volumetrically expanded portion of said essentially CO₂-free gas stream to a level that will result in desorption of CO₂ from said adsorbant station.

8. The method of claim 7 wherein said adsorption station and said desorption station are disposed on opposite sides of a common CO₂ sorbent material.

9. The method of claim 8 wherein said sorbent material is a CO₂-permeable membrane.

10. The method of claim 8 wherein said sorbent material is a porous material which is coated with a CO₂ adsorbent material.

11. The method of claim 7 further comprising a vent for discharging gas from said desoyption station to the low pressure ambient environment.

12. The method of claim 7 wherein the desorption station is operative to remove CO₂ from a sorbent at the same rate that the sorbent removes metabolic CO₂ from the gas stream.

13. The method of claim 7 wherein the habitable environment is pressurized to a pressure of approximately 200 mm Hg and the ambient environment has an ambient pressure in the range of about 6 to about 9 mm Hg.

14. The method of claim 7 wherein the ratio between the gas pressure at the adsorption station and the desorption station is about 7.5:

1.

15. The method of claim 7 wherein the ratio between the gas pressure at the adsorption station and the desorption station is about 12:

1.

16. An assembly for removing metabolic carbon dioxide (CO₂) from a breathable gas stream, which stream is derived from a closed habitable environment which habitable environment is located in an ambient environment that has an ambient pressure that is lower than the pressure in said habitable environment, said assembly comprising:

a) a CO₂ adsorption station for removing CO₂ from said breathable gas stream thereby creating a low CO₂ partial pressure gas stream;

b) a CO₂ desorption station for removing CO₂ from said adsorption station, said desorption station having a pressure which is between the pressure in said habitable environment and the pressure in said ambient environment;

c) a first line which is operative to transfer said breathable gas stream from said habitable environment to said adsorption station;

d) a second line which is operative to transfer a portion of said low CO₂ partial pressure gas stream from said adsorption station to habitable environment; and

e) a third line which is operative to transfer a remaining portion of said low CO₂ partial pressure gas stream from said adsorption station to said desorption station wherein the volume of said low CO₂ partial pressure gas stream is expanded so as to further lower the partial pressure of CO₂ in said remaining portion of said gas stream.

17. The assembly of claim 16 wherein said adsorption station and said desorption station are disposed on opposite sides of a common CO₂ sorbent material.

18. The assembly of claim 17 wherein said sorbent material is a CO₂-permeable membrane.

19. The assembly of claim 17 wherein said sorbent material is a porous material which is coated with a CO₂ adsorbent material.

20. The assembly of claim 16 further comprising a vent for discharging gas from said desorption station to the low pressure ambient environment.

21. The assembly of claim 16 wherein the desorption station is operative to remove CO₂ from a sorbent at the same rate that the sorbent removes metabolic CO₂ from the gas stream.

22. The assembly of claim 16 wherein the habitable environment is pressurized to a pressure of approximately 200 mm Hg and the ambient environment has an ambient pressure in the range of about 6 to about 9 mm Hg.

23. The assembly of claim 16 wherein the ratio between the gas pressure at the adsorption station and the desorption station is about 7.5:

1.

24. The assembly of claim 16 wherein the ratio between the gas pressure at the adsorption station and the desorption station is about 12:

1.