Method and absorbent composition for recovering a gaseous component from a gas stream

• US 8,388,737 B2
• Filed: 05/29/2008
• Issued: 03/05/2013
• Est. Priority Date: 05/29/2007
• Status: Active Grant

• Current Assignee: University of Regina
• Original Assignee: University of Regina
• Inventors: Tontiwachwuthikul, Paitoon, Idem, Raphael, Gelowitz, Don
• Primary Examiner(s): Smith, Duane
• Application Number:
  US12/598,598
• Publication Number:
  US 20100229723A1
• Time in Patent Office: 1,741 Days
• Field of Search: 951/62, 951/49, 951/83, 95178-180, 95193-194, 952/09, 951/81, 951/82, 952/32, 952/33, 952/35, 952/36
• US Class Current: 95/180
• 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) flowing the incoming gas stream through a gas-liquid contact apparatus wherein the incoming gas stream is contacted with a cooled lean aqueous absorbing medium thereby transferring at least a portion of the gaseous component from the incoming gas stream to the aqueous absorbing medium thereby forming a lean treated gas stream and a rich aqueous absorbing medium;

b) conveying the rich aqueous absorbing medium from the gas-liquid contact apparatus to a regenerator, the rich aqueous absorbing medium being heated by passage through a first heat-exchanger interposed the gas-liquid contact apparatus and the regenerator;

c) at an elevated temperature in the regenerator, desorbing at least a portion of the gaseous component from the heated rich aqueous absorbing medium at a temperature to form a heated overhead gas stream comprising the gaseous component and a heated regenerated lean aqueous absorbing medium;

d) conveying the a heated regenerated lean aqueous absorbing medium from the regenerator to the gas-liquid contact apparatus by passage through the first heat-exchanger wherein at least a portion of the heat is recovered from the regenerated lean aqueous absorbing medium thereby producing a partially cooled regenerated lean aqueous absorbing medium;

e) flowing the heated overhead gas stream through a second heat exchanger to recover a heated stream and a cooled first condensate therefrom; and

f) commingling the cooled condensate with the partially cooled regenerated lean aqueous absorbing medium thereby providing a cooled lean aqueous absorbing medium to the gas-liquid contact apparatus.

2. A method according to claim 1, wherein prior to flowing the incoming gas stream into the gas-liquid contact apparatus, heat is transferred from the incoming gas stream to the cooled first condensate recovered from the overhead gas stream.

3. A method according to claim 1, wherein the heated stream is flowed through a condenser to recover therefrom a carbon dioxide rich gas stream.

4. A method according to claim 1, 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 claim 1, 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 regenerated lean aqueous absorbing medium is combined with the first condensate stream.

7. A method according to any one of claims 1 to 5, wherein the regenerated lean aqueous absorbing medium combined with at least a portion of the first condensate stream and at least a portion of a second condensate stream recovered from the lean treated gas stream.

8. A method according to any one of claims 1 to 5, wherein the regenerated lean aqueous absorbing medium is combined with at least a portion of the first condensate stream and at least a portion of the second condensate stream and at least a portion of a third condensate stream recovered from the partially cooled regenerated lean aqueous absorbing medium.

9. A method according to claim 1, 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.

10. A method according claim 1, 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.

11. A method according to claim 1, 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.

12. A method according to claim 1, 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.

13. A method according to claim 1, wherein the heated rich aqueous absorbing medium 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.

14. A method according to claim 13, 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.

15. A method according to claim 13, 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.

16. A method according to claim 13, 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.

17. A method according to claim 13, 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.

18. 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.

19. A method according to claim 18, 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.

20. A method according claim 18, 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.

21. A method according to claim 18, 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.

22. A method according to claim 18, 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.

23. A method according to claim 1, wherein the incoming gas stream is a combustion exhaust gas.

24. A method according to claim 1, wherein the gaseous component comprises one or more of carbon dioxide, hydrogen sulphide, sulphur dioxide, chlorine and ammonia.

25. A method according to claim 1, wherein the gaseous component comprises carbon dioxide.

26. A method according to claim 1, wherein the lean aqueous absorbing medium comprises a mixture of monoethanolamine, methyldiethanolamine, and a solvent selected from a group consisting of water, methanol, ethanol, and combinations thereof.

27. A method according to claim 26, 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.

28. A method according to claim 27, 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.