Process for treating carbon dioxide containing gas

• US 8,277,769 B2
• Filed: 10/14/2011
• Issued: 10/02/2012
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: Saipem SPA (Saipem)
• Original Assignee: CO2 Solutions Inc.
• Inventors: Fradette, Sylvie, Ruel, Jean
• Primary Examiner(s): JOHNSON, EDWARD M
• Application Number:
  US13/273,391
• Publication Number:
  US 20120034680A1
• Time in Patent Office: 354 Days
• Field of Search: 60/395, 607/72, 423/432
• US Class Current: 423/432
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/84 Biological processes
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02E 20/32 Direct CO2 mitigation

Abstract

A process is disclosed for recycling carbon dioxide emissions from a fossil-fuel power plant into useful carbonated species The process primarily comprises the steps of: a) burning the fossil fuel, thereby generating heat and a hot exhaust gas containing CO₂; and b) converting the heat into energy. The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas; and d) biologically transforming the CO₂ contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO₂ exhaust gas and producing useful carbonated species. The low CO₂ exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.

Claims

1. A process comprising:

a) combustion of a fossil fuel, thereby generating heat and a hot exhaust gas containing CO₂;

b) converting said heat into energy;

c) cooling at least a portion of said exhaust gas to produce a cooled exhaust gas; and

d) reducing the amount of CO₂ contained in the cooled exhaust gas by biologically removing said CO₂;

thereby obtaining a low CO₂ exhaust gas, wherein step d) comprises;

contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO₂ to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO₂ and producing a solution containing hydrogen ions and bicarbonate ions; and

wherein said hydration is catalyzed by the enzyme carbonic anhydrase or an analogue thereof.

2. The process of claim 1, wherein the enzyme carbonic anhydrase or the analogue thereof is free in the aqueous liquid phase.

3. The process of claim 2, wherein in step c) the temperature to which the exhaust gas is cooled avoids a given denaturing of free carbonic anhydrase or the analogue thereof.

4. The process of claim 1, wherein the enzyme carbonic anhydrase or the analogue thereof is immobilised on a support which is in suspension in the aqueous liquid phase.

5. The process of claim 4, wherein in step c) the temperature to which the exhaust gas is cooled avoids a given denaturing of immobilized carbonic anhydrase.

6. The process of claim 1, wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a matrix which is in suspension in the aqueous liquid phase.

7. The process of claim 1, wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a matrix or immobilized on supports which are mounted within a reactor.

8. The process of claim 1, wherein step d) comprises adding cations to the solution and adjusting the pH of the solution to precipitate a carbonated species of the cation.

9. The process of claim 8, wherein the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.

10. A process comprising:

cooling at least a portion of a CO₂ containing gas to produce a cooled CO₂ containing gas; and

reducing the amount of CO₂ contained in the cooled CO₂ containing gas by biologically removing the CO₂;

thereby obtaining a low CO₂ gas, comprising contacting an aqueous liquid phase with the cooled CO₂ containing gas to cause at least a portion of the CO₂ to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO₂ and producing a solution containing hydrogen ions and bicarbonate ions; and

wherein the hydration is catalyzed by the enzyme carbonic anhydrase or an analogue thereof.

11. The process of claim 10, wherein the enzyme carbonic anhydrase or the analogue thereof is free in the aqueous liquid phase.

12. The process of claim 11, wherein the temperature to which the exhaust gas is cooled avoids a given denaturing of free carbonic anhydrase or the analogue thereof.

13. The process of claim 10, wherein the enzyme carbonic anhydrase or the analogue thereof is immobilised on a support which is in suspension in the aqueous liquid phase.

14. The process of claim 13, wherein the temperature to which the exhaust gas is cooled avoids a given denaturing of immobilized carbonic anhydrase.

15. The process of claim 10, wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a matrix which is in suspension in the aqueous liquid phase.

16. The process of claim 10, wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a matrix or immobilized on supports which are mounted within a reactor.

17. The process of claim 10, comprising adding cations to the solution and adjusting the pH of the solution to precipitate a carbonated species of the cation.

18. The process of claim 17, wherein the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.

19. The process of claim 10, wherein the CO₂ containing gas comprises hot exhaust gas generated by combustion of fossil fuel.

20. A process comprising:

pre-treating a CO₂ containing gas to remove contaminants and produce a contaminant reduced gas;

reducing the amount of CO₂ contained in the contaminant reduced gas by biologically removing the CO₂, thereby obtaining a low CO₂ gas, comprising contacting an aqueous liquid phase with the contaminant reduced gas to cause at least a portion of the CO₂ to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO₂ and producing a solution containing hydrogen ions and bicarbonate ions; and

wherein the hydration is catalyzed by the enzyme carbonic anhydrase or an analogue thereof.

21. The process of claim 20, wherein the contaminants removed are selected from the group consisting of ash, NO_x and SO₂.

22. The process of claim 20, wherein the pre-treating comprises scrubbing the CO₂ containing gas.

23. The process of claim 22, wherein the scrubbing is performed while cooling the CO₂ containing gas to produce a cooled CO₂ containing gas with a temperature sufficiently low to allow feeding directly into the step of biologically removing the CO₂.

24. The process of claim 20, wherein the CO₂ containing gas is cooled to a temperature sufficiently low so as to maintain a desired catalytic effect of the enzyme carbonic anhydrase or the analog thereof.

25. The process of claim 24, wherein the temperature to which the CO₂ containing gas is cooled avoids a given denaturing of free carbonic anhydrase.

26. The process of claim 24, wherein the temperature to which the CO₂ containing gas is cooled avoids a given denaturing of immobilized carbonic anhydrase.

27. The process of claim 20, wherein the enzyme carbonic anhydrase or the analogue thereof is free in the aqueous liquid phase;

immobilised on a support which is in suspension in the aqueous liquid phase;

entrapped inside a matrix which is in suspension in the aqueous liquid phase;

or entrapped inside a matrix or immobilized on supports which are mounted within a reactor.

28. The process of claim 20, comprising adding cations to the solution and adjusting the pH of the solution to precipitate a carbonated species of the cation.

29. The process of claim 28, wherein the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.

30. The process of claim 20, wherein the CO₂ containing gas comprises hot exhaust gas generated by combustion of fossil fuel.

31. The process of claim 30, wherein heat is removed from the hot exhaust gas prior to reducing the amount of CO₂ contained therein and the heat is recycled.

32. A process comprising:

generating a CO₂ containing gas;

ensuring that the CO₂ containing gas is a low temperature CO₂ containing gas having a temperature sufficiently low so as to maintain a desired catalytic effect of carbonic anhydrase or analog thereof;

reducing the amount of CO₂ contained in the low temperature CO₂ containing gas by biologically removing said CO₂, thereby obtaining a low CO₂ gas, comprising;

contacting an aqueous liquid phase with the low temperature CO₂ containing gas to cause at least a portion of the CO₂ to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO₂ and producing a solution containing hydrogen ions and bicarbonate ions; and

wherein said hydration is catalyzed by the carbonic anhydrase or the analogue thereof.

33. The process of claim 32, wherein the CO₂ containing gas is cooled to produce the low temperature CO₂ containing gas.

34. The process of claim 33, wherein the CO₂ containing gas comprises hot exhaust gas generated by combustion of fossil fuel and wherein heat is removed from the hot exhaust gas in a heat exchanger to produce the low temperature CO₂ containing gas.