METHOD AND ABSORBENT COMPOSITION FOR RECOVERING A GASEOUS COMPONENT FROM A GAS STREAM

• US 20100229723A1
• Filed: 05/29/2008
• Published: 09/16/2010
• Est. Priority Date: 05/29/2007
• Status: Active Grant

• Current Assignee: University of Regina
• Original Assignee: University of Regina
• Inventors: IDEM, Raphael, TONTIWACHWUTHIKUL, Paitoon, GELOWITZ, Don
• Granted Patent: US 8,388,737 B2
• Time in Patent Office: Days
• US Class Current: 95/162
• CPC Class Codes: B01D 2252/20405 Monoamines
• CPC Class Codes: B01D 2252/2041 Diamines
• CPC Class Codes: B01D 2252/20421 Primary amines
• CPC Class Codes: B01D 2252/20431 Tertiary amines
• CPC Class Codes: B01D 2257/2025 Chlorine
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/406 Ammonia
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2259/65 Employing advanced heat integration, e.g. Pinch technology
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1462 Removing mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents

Abstract

A method and apparatus for recovering a gaseous component from an incoming gas stream is described. The incoming gas stream is contacted with a lean aqueous absorbing medium to absorb at least a portion of the gaseous component from the incoming gas stream to form a lean treated gas stream and a rich aqueous absorbing medium. At least a portion of the gaseous component is desorbed from the rich aqueous absorbing medium at a temperature to form an overhead gas stream and a regenerated aqueous absorbing medium. At least a portion of the overhead gas stream is treated to recover a condensate stream. At least a portion of the condensate stream is used to form a heated stream. At least a portion of the heated stream is recycled back to the desorbing step. Novel absorbing medium compositions to recover carbon dioxide and/or hydrogen sulfide are also described.

Claims

1. A method for recovering a gaseous component from an incoming gas stream, comprising:

a) contacting the incoming gas stream with a lean aqueous absorbing medium to absorb at least a portion of the gaseous component from the incoming gas stream to form a lean treated gas stream and a rich aqueous absorbing medium;

b) desorbing at least a portion of the gaseous component from the rich aqueous absorbing medium at a temperature to form an overhead gas stream and a regenerated aqueous absorbing medium;

c) treating at least a portion of the overhead gas stream to recover a first condensate stream;

d) using at least a portion of the first condensate stream to form a heated stream;

e) recycling at least a portion of the heated stream back to the desorbing step.

2. A method according to claim 1, wherein heat is transferred from the incoming gas stream to the heated stream.

3. A method according to any one of claim 1 or 2, wherein heat is transferred from the overhead gas stream to the heated stream.

4. A method according to any one of claims 1 to 3, further comprising the steps of introducing steam to provide heat for the desorbing step and to form a steam condensate and flashing the steam condensate to form a flashed steam and wherein heat is transferred from the flashed steam to the heated stream.

5. A method according to any one of claims 1 to 4, wherein heat is transferred from the regenerated aqueous absorbing medium to the heated stream.

6. A method according to any one of claims 1 to 5, wherein the heated stream comprises the first condensate stream.

7. A method according to any one of claims 1 to 5, wherein the heated stream comprises the rich aqueous absorbing medium derived by delivering at least a portion of the first condensate stream to the contacting step so that at least a portion of the first condensate stream combines with the lean aqueous absorbing medium to form the rich aqueous absorbing medium.

8. A method according to any one of claims 1 to 5, further comprising the step of treating at least a portion of the lean treated gas stream to recover a second condensate stream and wherein the heated stream comprises a mixed condensate stream derived by combining at least a portion of the first condensate stream with at least a portion of the second condensate stream to form the mixed condensate stream.

9. A method according to claim 1, wherein the heated stream comprises a rich vapor stream and a semi-lean aqueous absorbing medium derived by delivering at least a portion of the first condensate stream to the contacting step so that at least a portion of the first condensate stream combines with the lean aqueous absorbing medium to form the rich aqueous absorbing medium which is subsequently flashed to form the rich vapor stream and the semi-lean aqueous absorbing medium.

10. A method according to claim 9, wherein heat is transferred from the incoming gas stream to at least one of the rich aqueous absorbing medium or the semi-lean aqueous absorbing medium.

12. A method according to any one of claims 9 to 11, further comprising the steps of introducing steam to provide heat for the desorbing step and to form a steam condensate and flashing the steam condensate to form a flashed steam and wherein heat is transferred from the flashed steam to at least one of the rich aqueous absorbing medium or the semi-lean aqueous absorbing medium.

13. A method according to any one of claims 9 to 12, wherein heat is transferred from the regenerated aqueous absorbing medium to at least one of the rich aqueous absorbing medium or the semi-lean aqueous absorbing medium.

14. A method according to claim 1, wherein the heated stream comprises a first rich aqueous absorbing medium portion and a second rich aqueous absorbing medium portion derived by delivering at least a portion of the first condensate stream to the contacting step so that at least a portion of the first condensate stream combines with the lean aqueous absorbing medium to form the rich aqueous absorbing medium which is subsequently split into the first rich aqueous medium portion and the second rich aqueous absorbing medium portion.

15. A method according to claim 14, wherein heat is transferred from the incoming gas stream to at least one of the rich aqueous absorbing medium, the first rich aqueous absorbing medium portion or the second rich absorbing medium portion.

17. A method according to any one of claims 14 to 16, further comprising the steps of introducing steam to provide heat for the desorbing step and to form a steam condensate and flashing the steam condensate to form a flashed steam and wherein heat is transferred from the flashed steam to at least one of the rich aqueous absorbing medium, the first rich aqueous absorbing medium portion or the second rich absorbing medium portion.

18. A method according to any one of claims 14 to 17, wherein heat is transferred from the regenerated aqueous absorbing medium to at least one of the rich aqueous absorbing medium, the first rich aqueous absorbing medium portion or the second rich absorbing medium portion.

19. A method according to claim 1, further comprising the step of treating at least a portion of the lean treated gas stream to recover a second condensate stream and wherein the heated stream comprises a first mixed condensate stream portion and a second mixed condensate stream portion derived by combining at least a portion of the first condensate stream with at least a portion of the second condensate stream to form the mixed condensate stream and subsequently splitting the mixed condensate stream to form the first mixed condensate stream portion and the second mixed condensate stream portion.

20. A method according to claim 19, wherein heat is transferred from the incoming gas stream to at least one of the mixed condensate stream, the first mixed condensate stream portion or the second mixed condensate stream portion.

22. A method according to any one of claims 19 to 21, further comprising the steps of introducing steam to provide heat for the desorbing step and to form a steam condensate and flashing the steam condensate to form a flashed steam and wherein heat is transferred from the flashed steam to at least one of the mixed condensate stream, the first mixed condensate stream portion or the second mixed condensate stream portion.

23. A method according to any one of claims 19 to 22, wherein heat is transferred from the regenerated aqueous absorbing medium to at least one of the mixed condensate stream, the first mixed condensate stream portion or the second mixed condensate stream portion.

24. A method according to any one of claims 1 to 23, further comprising the step of recycling the regenerated aqueous absorbing medium back to the contacting step.

25. A method according to any one of claims 1 to 24, wherein the incoming gas stream is a combustion exhaust gas.

26. A method according to any one of claims 1 to 25, wherein the gaseous component is carbon dioxide.

27. A method according to claim any one of claims 1 to 26, wherein the lean aqueous absorbing medium comprises monoethanolamine, methyldiethanolamine and a suitable solvent.

28. A method according to claim 27, wherein the molar ratio of monoethanolamine to methydiethanolamine is between about 1.5:

1 to about 4;

1 and the total molarity of monoethanolamine and methyldiethanolamine is between about 3 moles/liter to about 9 moles/liter.

29. A method according to claim 28, wherein the molar ratio of monoethanolamine to methydiethanolamine is about 2.5:

1 and the total molarity of monoethanolamine and methyldiethanolamine is about 7 moles/liter.

11. A method according to any one of 9 or 10, wherein heat is transferred from the overhead gas stream to at least one of the rich aqueous absorbing medium or the semi-lean aqueous absorbing medium.

16. A method according to any one of 14 or 15, wherein heat is transferred from the overhead gas stream to at least one of the rich aqueous absorbing medium, the first rich aqueous absorbing medium portion or the second rich absorbing medium portion.

21. A method according to any one of 19 or 20, wherein heat is transferred from the overhead gas stream to at least one of the mixed condensate stream, the first mixed condensate stream portion or the second mixed condensate stream portion.

30. An aqueous absorbing medium for removing a gaseous component from an incoming gas stream, the aqueous absorbing medium comprising monoethanolamine, methyldiethanolamine and a suitable solvent, the molar ratio of monoethanolamine to methydiethanolamine is between about 1.5:

1 to about 4;

1 and the total molarity of monoethanolamine and methyldiethanolamine is between about 3 moles/liter to about 9 moles/liter.

31. An aqueous absorbing medium according to claim 30, wherein the molar ratio of monoethanolamine to methydiethanolamine is about 2.5:

1 and the total molarity of monoethanolamine and methydiethanolamine is about 7 moles/liter.

32. A method for producing an aqueous absorbing medium, comprising:

a) providing monoethanolamine;

b) providing methyldiethanolamine;

c) providing a suitable solvent;

d) combining the monoethanolamine, the methyldiethanolamine and the solvent to form the aqueous absorbing medium;

and wherein the molar ratio of monoethanolamine to methydiethanolamine is between about 1.5;

1 to about 4;

1 and the total molarity of monoethanolamine and methydiethanolamine is between about 3 moles/liter to about 9 moles/liter.

33. A method according to claim 32, wherein the molar ratio of monoethanolamine to methydiethanolamine is about 2.5:

1 and the total molarity of monoethanolamine and methydiethanolamine is about 7 moles/liter.

35. A method according to claim 33, wherein the molar ratio of monoethanolamine to methydiethanolamine is about 2.5:

1 and the total molarity of monoethanolamine and methyldiethanolamine is about 7 moles/liter.

34. A method for removing a gaseous component from an incoming gas stream, comprising contacting the incoming gas stream with an aqueous absorbing medium comprising monoethanolamine, methyldiethanolamine and a suitable solvent, the molar ratio of monoethanolamine to methydiethanolamine is between about 1.5:

1 to about 4;

1 and the total molarity of monoethanolamine and methyldiethanolamine is between about 3 moles/liter to about 9 moles/liter.