Process for the recovery of CO.sub.2 from flue gases

• US 4,624,839 A
• Filed: 02/19/1985
• Issued: 11/25/1986
• Est. Priority Date: 12/12/1983
• Status: Expired due to Term

• Current Assignee: Fluor Daniel (Japan) Inc. (Fluor Enterprises, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Wolcott, Richard A., Pearce, Roscoe L., Pauley, Charles R.
• Primary Examiner(s): KONOPKA, PAUL
• Application Number:
  US06/702,961
• Time in Patent Office: 644 Days
• Field of Search: 423/220, 423/228, 423/229, 55/68, 55/73
• US Class Current: 423/228
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

There is disclosed a procedure for removing copper inhibitor from a circulating fluid which contains the same, which copper may be lost on the cool side of a gas conditioning system by plating out under certain conditions, by contacting a portion of the circulating hot fluid with an activated carbon bed to sorb the copper in excess of the solubility limits within said fluid, regenerating said carbon bed when saturated by contacting said carbon bed with cool circulating fluid, thus returning copper which may have plated out to the circulating fluid in an amount and in an ionic state which will not plate out in the system, the circulating fluid is also treated on the cool side by mechanical filtration, activated carbon sorption and/or ion exchange to remove physical and chemical impurities, contaminates and degradation products.

Claims

1. In a process for the recovery of carbon dioxide from feed gases containing the same and oxygen, which may also contain sulfur compounds, by contacting the gas with a circulating alkanolamine solution containing copper as an inhibitor, to absorb the CO₂ and thereafter treating said solution rich and CO₂ with heat to release the CO₂ thereby producing a hot lean solution and returning the so treated lean solution after cooling to the contacting step, the improvement which comprises

maintaining an amount of copper in said

circulating solution effective to inhibit corrosion and/or degradation of the solvent

(a) by contacting all or a portion of said cool lean circulating solution with at least one of the following

(1) at least one mechanical filter;

(2) activated carbon bed;

(3) strong base anion exchange resin; and

/or

(4) any combination thereof; and

(b) by

(1) withdrawing a portion of the hot lean solution after the release of the CO₂ by heat and, prior to cooling and/or contact with (a)(1), (2) and/or (3), treating said withdrawn hot portion by passing it through a carbon bed independant of (a)(2) to reduce the dissolved ionic cooper in the hot solution;

(2) stopping said withdrawal of hot lean solution;

(3) contacting said carbon bed with cool lean solution to redissolve the copper from the carbon bed and returning said copper containing lean cool solution to the absorber.

2. A process of claim 1 wherein the alkanol amine is a monoalkanolamine.

3. A process of claim 1 wherein the alkanol amine is monoethanolamine.

4. The process of claim 1 wherein a portion of the circulating solution is withdrawn and blown with an oxygen containing gas and said portion is returned to the alkanolamine circuit.

5. The process of claim 1 wherein the maximum bulk temperature of the heated alkanolamine is no greater than about 260°

F. and is subjected to a heat flux of less than about 10,000 BTU/ft² /hr.

6. The process of claim 1 wherein the bulk temperature of the heated alkanolamine is about 244°

to about 250°

F. and is subJected to a heat flux of less than about 6000 BTU/ft² /hr.

7. The process of claim 1 wherein the copper ion is maintained at between about 50 ppm and about 750 ppm.

8. The process of claim 1 wherein the copper ion is maintained at between about 100 ppm and about 500 ppm.

9. The process of claim 1 wherein the cool circulating solution is subJected to treatment by contact with an activated carbon treater thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

10. The process of claim 1 wherein the circulating solution is subjected to treatment by contact with a mechanical filter thereby to remove one or more of the insoluble iron and solvent degradation products.

11. The process of claim 1 wherein the circulating solution is subjected to treatment by contact with a strong base anion exchange resin thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

12. The process of claim 1 wherein the circulating solution is subjected to treatment by contact with a mechanical filter and an activated carbon treater thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

13. The process of claim 1 wherein the circulating solution is subjected to treatment by contact with a mechanical filter and a strong base anion exchange resin thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

14. The process of claim 1 wherein the cool circulating solution is subjected to treatment by contact with a mechanical filter followed by an activated carbon treater, a second mechanical filter and a strong base anion exchange resin thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

15. The process of claim 1 wherein the feed gas is a flue gas.

16. The process of claim 1 wherein the feed gas is a gas from an internal combustion engine.

17. In a process for the recovery of carbon dioxide from feed gases containing the same and oxygen, which may also contain sulfur compounds, by contacting the gas with a circulating alkanolamine solution, containing copper as an inhibitor, and treating said solution rich in CO₂ with heat to release the CO₂ thereby thereby producing a lean solution and returning the so treated lean solution, after cooling, to the contacting step, the improvement which comprises

maintaining at least 5 parts of copper per million parts solution in said circulating solution;

(a) by contacting all or a portion of said cool lean circulating solution with at least one of the following

(1) at least one mechanical filter;

(2) activated carbon bed;

(3) strong base anion exchange resin; and

/or

(4) any combination thereof; and

(b) by

(1) withdrawing a portion of the hot lean solution after the release of the CO₂ by heat and, prior to cooling and/or contact with (a)(1), (2) and/or (3), treating said withdrawn hot portion by passing it through a carbon bed independant of (a)(2) to reduce the dissolved ionic copper in the hot solution;

(2) stopping said withdrawal of hot lean solution;

(3) contacting said carbon bed with cool lean solution to redissolve the copper from the carbon bed and returning said copper containing lean cool solution to the absorber.

18. A process of claim 17 wherein the alkanolamine is a monoalkanolamine.

19. A process of claim 17 wherein the alkanolamine is monoethanolamine.

20. The process of claim 17 wherein a portion of the circulating solution is withdrawn and blown with an oxygen containing gas and such so-treated stream is returned to the alkanolamine circuit.

21. The process of claim 17 wherein the maximum bulk temperature of the heated alkanolamine is no greater than about 260°

F. and is subjected to a heat flux of less than about 10,000 BTU/ft² /hr.

22. The process of claim 17 wherein the bulk temperature of the heated alkanolamine is about 244°

to about 250°

F. and is subjected to a heat flux of less than about 6000 BTU/ft² /hr.

23. The process of claim 17 wherein the copper ion is maintained at between about 50 ppm and 750 ppm.

24. The process of claim 17 wherein the copper ion is maintained at between about 100 ppm and 500 ppm.

25. The process of claim 17 wherein the cool circulating solution is subjected to treatment by contact with an activated carbon treater thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

26. The process of claim 17 wherein the circulating solution is subjected to treatment by contact with a mechanical filter thereby to remove one or more of the insoluble iron and solvent degradation products.

27. The process of claim 17 wherein the circulating solution is subjected to treatment by contact with a strong base anion exchange bed thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

28. The process of claim 17 wherein the circulating solution is subjected to treatment by contact with a mechanical filter and an activated carbon treater thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

29. The process of claim 17 wherein the circulating solution is subjected to treatment by contact with a mechanical filter and a strong base anion exchange bed thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

30. The process of claim 17 wherein the cool circulating solution is subected to treatment by contact with a mechanical filter followed by an activated carbon treater, a second mechanical filter and a strong base anion exchange resin thereby to remove one or more of the soluble iron, insoluble iron and solvent degradation products.

31. The process of claim 17 wherein the feed as is a flue gas.

32. The process of claim 17 wherein the feed gas is a gas from an internal combustion engine.

33. In a process for the recovery of carbon dioxide from feed gases containing the same and oxygen, which may also contain sulfur compounds, by contacting the gas with a circulating liquid aqueous 5 to 80% by weight alkanolamine solution, containing copper as an inhibitor and treating said solution rich in CO₂ with heat to release the CO₂ thereby producing a hot lean solution and returning the so treated lean solution, after cooling, to the contacting step, the improvement which comprises

maintaining at least 5 parts of copper per million parts solution in said circulating solution;

(a) by contacting all or a portion of said cool lean circulating solution with at least one of the following

(1) at least one mechanical filter;

(2) activated carbon bed;

(3) strong base anion exchange resin; and

/or

(4) any combination thereof; and

(b) by

(1) withdrawing a portion of the hot lean solution after the release of the CO₂ by heat and, prior to cooling and/or contact with (a)(1), (2) and/or (3), treating said withdrawn hot portion by passing it through a carbon bed independant of (a)(2) to reduce the dissolved ionic copper in the hot solution;

(2) stopping said withdrawal of hot lean solution;

(3) contacting said carbon bed with cool lean solution to redissolve the copper from the carbon bed and returnning said copper containing lean cool solution to the absorber.