Thermally linked molecular sieve beds for CO2 removal

• US 7,736,416 B2
• Filed: 02/26/2007
• Issued: 06/15/2010
• Est. Priority Date: 02/26/2007
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Original Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Inventors: Nalette, Timothy A., Rector, Tony
• Primary Examiner(s): Hopkins; Robert A
• Application Number:
  US11/710,730
• Publication Number:
  US 20080202339A1
• Time in Patent Office: 1,205 Days
• Field of Search: 951/20, 951/39, 961/22, 961/30, 961/26, 961/33
• US Class Current: 95/1
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 2259/41 using plural beds of the same adsorbent in series
• CPC Class Codes: B01D 2259/4575 in aeroplanes or space ships
• CPC Class Codes: B01D 2259/65 Employing advanced heat integration, e.g. Pinch technology
• CPC Class Codes: B01D 53/0454 Controlling adsorption controlling temperature swing adsorption B01D53/0462, controlling pressure swing adsorption B01D53/047
• CPC Class Codes: B01D 53/0476 Vacuum pressure swing adsorption
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A carbon dioxide (CO₂) removal system includes a first sorbent bed and a second sorbent bed. Each of the first and second sorbent beds has a molecular sieve sorbent for adsorbing or desorbing CO₂. One of the sorbent beds adsorbs CO₂ and the other of the sorbent beds desorbs CO₂. The first and second sorbent beds are thermally connected to transfer heat between the sorbent beds.

Claims

1. A carbon dioxide (CO₂) removal system comprising:

first and second sorbent beds, each of the sorbent beds having a molecular sieve sorbent for adsorbing or desorbing CO₂;

wherein one of the sorbent beds adsorbs CO₂, the other of the sorbent beds desorbs CO₂, and the first and second sorbent beds are thermally connected to transfer heat exothermically generated by the sorbent bed adsorbing CO₂ to the sorbent bed desorbing CO₂.

2. The system of claim 1, and further comprising a controller, wherein the controller determines which of said beds adsorb CO₂ and which of the sorbent beds desorb CO₂.

3. The system of claim 1, and further comprising a plurality of sorbent beds, wherein each of the plurality of sorbent beds has a molecular sieve sorbent for adsorbing and desorbing CO₂.

4. The system of claim 1, wherein the first and second molecular sieve sorbents are selected from the group consisting of:

a 4A molecular sieve and a 5A molecular sieve.

5. The system of claim 1, and further comprising a third sorbent bed having a desiccant for adsorbing water, wherein the third sorbent bed is positioned upstream of the first sorbent bed and the second sorbent bed.

6. The system of claim 5, wherein the desiccant is a 13X molecular sieve.

7. The system of claim 1, and further comprising a vacuum connected to the first and second sorbent beds for removing CO₂ from the first and second sorbent beds.

8. The system of claim 1, wherein the process is operated substantially isothermally.

9. A system for removing carbon dioxide (CO₂) from a process air stream, the system comprising:

a first sorbent bed having a first molecular sieve;

a second sorbent bed having a second molecular sieve, wherein the second sorbent bed is thermally connected to the first sorbent bed;

an inlet passage connectable to the first sorbent bed and the second sorbent bed;

an inlet valve connected to the inlet passage and switchable between a first position and a second position;

an outlet passage connectable to the first sorbent bed and the second sorbent bed;

an outlet valve connected to the outlet passage and switchable between a first position and a second position;

a carbon dioxide passage connectable to the first sorbent bed and the second sorbent bed; and

a carbon dioxide valve connected to the carbon dioxide passage and switchable between a first position and a second position;

wherein heat generated exothermically by adsorption of CO₂ is transferred between the first sorbent bed and the second sorbent bed.

10. The system of claim 9, and further comprising a vacuum connectable through the carbon dioxide valve to the first sorbent bed and the second sorbent bed.

11. The system of claim 9, wherein the first and second molecular sieves are selected from the group consisting of:

a 4A molecular sieve and a 5A molecular sieve.

12. The system of claim 9, and further comprising a controller for switching each of the inlet valve, the outlet valve, and the carbon dioxide valve between the first position and the second position.

13. The system of claim 9, wherein the first sorbent bed and the second sorbent bed alternate between adsorbing CO₂ and desorbing CO₂.

14. The system of claim 9, wherein the system is operated at ambient temperature.

15. The system of claim 9, and further comprising a third sorbent bed having a desiccant for removing water, wherein the third sorbent bed is positioned upstream of the first sorbent bed and the second sorbent bed.

16. A method for removing carbon dioxide (CO₂) from a process air stream, the method comprising:

supplying the process air stream to a first molecular sieve and a second molecular sieve to cause CO₂ to be adsorbed and removed from the process air stream;

reducing a pressure of one of the first and second molecular sieves to cause CO₂ to be desorbed and removed from the first and second molecular sieves so that that one of the first and second molecular sieves is adsorbing and the other molecular sieve is desorbing; and

transferring exothermically generated heat from the molecular sieve that is adsorbing to the molecular sieve that is desorbing.

17. The method of claim 16, wherein the first molecular sieve and the second molecular sieve alternate between adsorbing and desorbing.

18. The method of claim 16, wherein each of the first molecular sieve and the second molecular sieve is selected from the group consisting of:

a 4A molecular sieve and a 5A molecular sieve.

19. The method of claim 16, and further comprising adsorbing water from the process air stream.

20. The method of claim 19, wherein the water is adsorbed from the process air stream by a desiccant positioned upstream of the first molecular sieve and the second molecular sieve.

21. The method of claim 16, wherein reducing a pressure of one of the first and second molecular sieves comprises using a vacuum.