Process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species

• US 20100021981A1
• Filed: 09/28/2009
• Published: 01/28/2010
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: Saipem SPA (Saipem)
• Original Assignee: CO2 Solutions Inc.
• Inventors: Ruel, Jean, Fradette, Sylvie
• Granted Patent: US 8,066,965 B2
• Time in Patent Office: Days
• US Class Current: 435/168
• 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;

the process being characterized in that it comprises the steps of;

c) cooling said exhaust gas; and

d) reducing the amount of CO₂ contained in the cooled exhaust gas by biologically transforming said CO₂ into carbonated species;

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

catalyzing the hydration of at least a portion of the CO₂ contained in the exhaust gas and producing a solution containing hydrogen ions and carbonate ions; and

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

2. A process as defined in claim 1, wherein step d) comprises:

adding to said solution cations, and adjusting the pH of the solution to precipitate a carbonated species of said cation.

3. A process as claimed in claim 2, characterized in that the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.

4. A process as defined in claim 3, characterized in that said cations are Ca++ and the carbonated species is CaCO₃.

5. A process as defined in claim 1, characterized in that the carbonated species comprise precipitates.

6. A process as defined in claim 1, characterized in that the carbonated specie comprise solid precipitates.

7. A process as defined in claim 1, characterized in that the carbonated specie consist of solid precipitates.

8. A process as defined in claim 1, wherein step d) comprises the step of:

feeding liquid H₂O and at least a portion of the exhaust gas into a bioreactor containing therein a reaction chamber filled with said enzyme carbonic anhydrase or said analog thereof.

9. A process as defined in claim 1, characterized in that the enzyme carbonic anhydrase or said analog thereof is immobilized on solid supports packing the bioreactor.

10. A process as defined in claim 1, wherein step d) comprises the step of:

feeding at least a portion of the exhaust gas into a bioreactor containing therein a reaction chamber filled with said enzyme carbonic anhydrase or said analog thereof in suspension in a liquid phase.

11. A process as defined in claim 10, wherein the enzyme is free in the liquid phase.

12. A process as defined in claim 10, wherein the enzyme is immobilised on a solid support which is in suspension in the aqueous liquid.

13. A process as defined in claim 10, wherein the enzyme is entrapped inside a matrix which is in suspension in the aqueous liquid.

14. A process as defined in claim 1, wherein the enzyme is entrapped inside a matrix in the reactor.

15. A process as defined in claim 1, wherein the cooling of the exhaust gas comprises passing the exhaust gas through a heat exchanger.

16. A process as defined in claim 15, wherein heat removed by the heat exchanger is recovered to convert into energy.

17. A process as defined in claim 1, wherein the cooling of the exhaust gas is performed while removing additional contaminants contained in the exhaust gas.

18. A process as defined in claim 17, wherein the additional contaminants are removed from the exhaust gas by scrubbing.

19. A process as defined in claim 18, wherein the additional contaminants removed by scrubbing are selected from the group consisting of ash, NO_x and SO₂.

20. A process as defined in claim 1, characterized in that, in step c), the exhaust gas is cooled to a temperature sufficiently low so as to maintain a catalytic effect of the enzyme carbonic anhydrase or said analog thereof.

21. A process as defined in claim 1, characterized in that it comprises, prior to step d) of reducing, the step of:

removing from the exhaust gas additional contaminants contained in the exhaust gas.

22. A process as defined in claim 21, characterized in that said additional contaminants are selected from the group consisting of ash, NO_x and SO₂.

23. A process as defined in claim 1, characterized in that step c) of cooling is performed by means of a heat exchanger that removes heat from said cooled exhaust gas, the heat removed being recycled in step b) of the process.