Method of separating carbon dioxide from a gas mixture using a fluid dynamic instability

• US 6,582,498 B1
• Filed: 05/04/2001
• Issued: 06/24/2003
• Est. Priority Date: 05/04/2001
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Gupta, Neeraj, Saunders, James H., Webb, Paul R., Sass, Bruce M., Barnes, Russell H. Jr., Monzyk, Bruce F.
• Primary Examiner(s): SMITH, DUANE
• Application Number:
  US09/849,944
• Time in Patent Office: 781 Days
• Field of Search: 952/10, 952/11, 952/36, 952/63, 962/02, 962/90, 962/96, 962/99, 962/72, 963/22, 963/27
• US Class Current: 95/211
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/18 Absorbing units; Liquid distributors therefor B01D3/16, B01D3/26, B01D3/30 take precedence; packing elements B01J19/30, B01J19/32
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

In a method of separating carbon dioxide from a gas mixture, a liquid solvent flows down an array of vertical wires with the gas mixture flowing over the liquid. Once on the wire, the liquid quickly breaks up into drops of varying sizes, with each size moving down the wire at a different velocity. Large, faster moving drops overtake the small, slower moving drops to form even larger drops. As the drops fall, new drops are created behind the falling drops. Consequently, drops of a large range of sizes are forming, colliding, and mixing as they travel down the wire. During this process, gas molecules that have adsorbed onto the liquid surface are mixed into the interior of the solvent, resulting in highly effective mass transfer and gas absorption. This enhanced mass transfer allows greater flexibility in the choice of solvent and in the system design.

Claims

1. A method of separating a non-aqueous component from a gas mixture comprising the steps of:

flowing a liquid solvent down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent; and

flowing the gas mixture into contact with the solvent on the wire so that the solvent absorbs the non-aqueous component from the gas mixture, the fluid instability of the solvent increasing the mass transfer rate of the absorption process.

2. A method according to claim 1 wherein the fluid instability includes mixing of the content of the drops such that liquid solvent flows from the surface of the drops into the interior of the drops.

3. A method according to claim 1 wherein the solvent forms drops of different sizes which collide with one another as they flow down the wire, causing mixing of the content of the drops.

4. A method according to claim 1 wherein the gas component is selected from the group consisting of CO₂, NO_X, SO_X, H₂S, COS, HCN, NH₃, alkylene oxide, water vapor, and mixtures thereof.

5. A method according to claim 1 wherein the gas component is selected from the group consisting of CO₂, NO_X, and mixtures thereof.

6. A method according to claim 1 wherein the liquid solvent comprises a secondary or tertiary amine.

7. A method according to claim 1 wherein the liquid solvent comprises a tertiary amine.

8. A method according to claim 7 wherein the tertiary amine comprises methyldiethanolamine.

9. A method according to claim 7 wherein the tertiary amine is mixed with water before flowing the amine down the wire, the mixture comprising, by weight, from about 35% to about 70% amine and from about 30% to about 65% water.

10. A method of separating a component from a gas mixture comprising the steps of:

flowing a liquid solvent down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent, the solvent being reactive with the gas component; and

flowing the gas mixture into contact with the solvent on the wire so that the solvent reacts with and absorbs the gas component, the fluid instability of the solvent increasing the rate of reaction of the solvent with the gas component by at least about 10% compared to the same reaction with the solvent in a fluid stable condition.

11. A method according to claim 10, wherein the fluid instability of the solvent increases the rate of reaction of the solvent with the gas component by at least about 30%.

12. A method according to claim 10 wherein the gas component is selected from the group consisting of CO₂, NO_X, SO_X, H₂S, COS, HCN, NH₃, alkylene oxide, water vapor, and mixtures thereof.

13. A method according to claim 10 wherein the gas component is selected from the group consisting of CO₂, NO_X, and mixtures thereof.

14. A method according to claim 10 wherein the liquid solvent comprises a secondary or tertiary amine.

15. A method according to claim 10 wherein the liquid solvent comprises a tertiary amine.

16. A method according to claim 15 wherein the tertiary amine comprises methyldiethanolamine.

17. A method according to claim 10 wherein the liquid solvent comprises, by weight, from about 35% to about 70% tertiary amine and from about 30% to about 65% water.

18. A method of separating carbon dioxide from a gas mixture comprising the steps of:

flowing a liquid solvent down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent, the solvent being reactive with carbon dioxide; and

flowing a gas mixture containing carbon dioxide into contact with the solvent on the wire so that the solvent reacts with and absorbs the carbon dioxide from the gas mixture, the fluid instability of the solvent increasing the mass transfer rate of the absorption process.

19. A method according to claim 18 wherein the fluid instability includes mixing of the content of the drops such that liquid solvent flows from the surface of the drops into the interior of the drops.

20. A method according to claim 18 wherein the solvent forms drops of different sizes which collide with one another as they flow down the wire, causing mixing of the content of the drops.

21. A method according to claim 18 wherein the liquid solvent comprises a secondary or tertiary amine.

22. A method according to claim 18 wherein the liquid solvent comprises a tertiary amine.

23. A method according to claim 22 wherein the tertiary amine comprises methyldiethanolamine.

24. A method according to claim 18 wherein the liquid solvent comprises, by weight, from about 35% to about 70% tertiary amine and from about 30% to about 65% water.

25. A method of separating a component from a gas mixture comprising the steps of:

flowing a liquid containing a solvent down a wire so that the liquid forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the liquid, the solvent being reactive with the gas component, and the liquid further containing an activator which promotes the reaction of the solvent with the gas component; and

flowing the gas mixture into contact with the solvent on the wire so that the solvent reacts with and absorbs the component from the gas mixture, the fluid instability of the liquid increasing the mass transfer rate of the absorption process.

26. A method according to claim 25 wherein the component is carbon dioxide, the liquid solvent is a tertiary amine, and the activator is selected from the group consisting of monoethanolamine;

piperazine;

2-methylpiperazine;

2,3-dimethylpiperazine;

2,5-dimethylpiperazine;

solutions of primary and secondary amines;

phosphoric acid; and

mixtures thereof.

27. A method according to claim 25 wherein the liquid comprises, by weight, from about 35% to about 70% solvent, from about 30% to about 65% water, and from about 0.2% to about 10% activator.

28. A method of separating a component from a gas mixture comprising the steps of:

flowing a liquid solvent down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent;

exciting the fluid instability of the solvent; and

flowing the gas mixture into contact with the solvent on the wire so that the solvent absorbs the component from the gas mixture, the fluid instability of the solvent increasing the mass transfer rate of the absorption process.

29. A method according to claim 28 wherein the fluid instability of the solvent is excited by changing the flow of liquid solvent on the wire by passive mechanical means.

30. A method according to claim 28 wherein the fluid instability of the solvent is excited by placing obstacles on the wire and passing the flow of solvent over the obstacles.

31. A method according to claim 28 wherein the fluid instability of the solvent is excited by causing motion of the wire.

32. A method according to claim 28 wherein the fluid instability of the solvent is excited by one of vibrating the wire normal to the wire axis, vibrating the wire longitudinally, and rotating the wire.

33. A method according to claim 28 wherein the fluid instability of the solvent is excited by heating the solvent.

34. A method according to claim 28 wherein the component is a non-aqueous component.

35. A method of separating carbon dioxide from a flue gas comprising the steps of:

flowing a liquid solvent down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent, the solvent being reactive with carbon dioxide, and the solvent comprising a mixture of tertiary amine and water; and

flowing a flue gas containing carbon dioxide into contact with the solvent on the wire so that the solvent reacts with and absorbs the carbon dioxide from the flue gas, the fluid instability of the solvent increasing the mass transfer rate of the absorption process.

36. A method of separating a component from a gas mixture comprising the steps of:

flowing a liquid solvent, comprising a mixture of amine and water, down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent; and

flowing the gas mixture into contact with the solvent on the wire so that the solvent absorbs the component from the gas mixture, the fluid instability of the solvent increasing the mass transfer rate of the absorption process;

the method including selecting the amine to have physical properties such that the liquid solvent resists formation of solids and has suitable flow characteristics to flow down the wire sufficient to significantly increase the mass transfer rate.

37. A method of stripping a gaseous component from a liquid solvent containing the component, the method comprising the steps of:

flowing a liquid solvent containing a gaseous component down a wire so that the solvent forms drops which flow down the wire, the flow of the drops down the wire creating fluid instability of the solvent; and

heating the liquid solvent on the wire so that the gaseous component is released from the solvent, the fluid instability of the solvent increasing the mass transfer rate of the stripping process.

38. A method according to claim 37 wherein the fluid instability includes mixing of the content of the drops such that liquid solvent flows from the interior of the drops to the surface of the drops.

39. A method according to claim 37 wherein the gaseous component is selected from the group consisting of CO₂, NO_X, SO_X, H₂S, COS, HCN, NH₃, alkylene oxide, water vapor, and mixtures thereof.