Process for treating carbon dioxide containing gas
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 CO 2 ; 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 CO 2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO 2 exhaust gas and producing useful carbonated species. The low CO 2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.
1. A process comprising:
a) combustion of a fossil fuel or biomass, thereby generating heat and a hot exhaust gas containing CO 2 ;
b) using said heat to produce steam from water in a steam generator;
c) cooling at least a portion of said exhaust gas to produce a cooled exhaust gas; and
d) reducing the amount of CO 2 contained in the cooled exhaust gas, thereby obtaining a low CO 2 exhaust gas, wherein the step of reducing the amount of CO 2 comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO 2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO 2 and producing a solution containing hydrogen ions and bicarbonate ions; and wherein said hydration is catalyzed by 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 1 , wherein the enzyme carbonic anhydrase or the analogue thereof is immobilised on a support which is in suspension in the aqueous liquid phase.
4. The process of claim 1 , wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a solid.
5. The process of claim 4 , where the solid comprises a solid matrix.
6. 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.
7. The process of claim 1 , wherein the steam produced in step b) is used to produce electricity.
8. The process of claim 7 , wherein the steam produced in step b) is provided to a heat recovery steam generator system.
9. 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.
10. The process of claim 9 , wherein the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.
11. The process of claim 1 , wherein the step of reducing the amount of CO 2 in the cooled exhaust gas comprises biologically removing said CO 2 .
12. A process comprising:
combustion of a fossil fuel or biomass, thereby generating heat and a CO 2 containing exhaust gas;
using said heat to produce steam from water in a steam generator;
reducing the amount of CO 2 contained in the CO 2 containing exhaust gas, thereby obtaining a low CO 2 gas, comprising contacting an aqueous liquid phase with the CO 2 containing exhaust gas to cause at least a portion of the CO 2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO 2 and producing a solution containing hydrogen ions and bicarbonate ions; and wherein the hydration is catalyzed by carbonic anhydrase or an analogue thereof.
13. The process of claim 12 , wherein the enzyme carbonic anhydrase or the analogue thereof is free in the aqueous liquid phase.
14. The process of claim 12 , wherein the enzyme carbonic anhydrase or the analogue thereof is immobilised on a support which is in suspension in the aqueous liquid phase.
15. The process of claim 12 , wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a solid.
16. The process of claim 15 , where the solid comprises a solid matrix.
17. The process of claim 12 , wherein the enzyme carbonic anhydrase or the analogue thereof is entrapped inside a matrix or immobilized on supports which are mounted within a reactor.
18. The process of claim 12 , comprising adding cations to the solution and adjusting the pH of the solution to precipitate a carbonated species of the cation.
19. The process of claim 12 , wherein the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.
20. The process of claim 12 , wherein the CO 2 containing gas comprises exhaust gas generated by combustion of fossil fuel or biomass.
21. A process comprising:
pre-treating a CO 2 containing gas to remove contaminants and produce a contaminant reduced gas;
reducing the amount of CO 2 contained in the contaminant reduced gas, thereby obtaining a low CO 2 gas, by contacting an aqueous liquid phase with the contaminant reduced gas to cause at least a portion of the CO 2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO 2 and producing a solution containing hydrogen ions and bicarbonate ions; and wherein the hydration is catalyzed by carbonic anhydrase or an analogue thereof.
22. The process of claim 21 , wherein the contaminants removed are selected from the group consisting of ash, NO x and SO 2 .
23. The process of claim 21 , wherein the pre-treating comprises scrubbing the CO 2 containing gas.
24. The process of claim 23 , wherein the scrubbing is performed while cooling the CO 2 containing gas to produce a cooled CO 2 containing gas with a temperature sufficiently low to allow feeding directly into the step of biologically removing the CO 2 .
25. The process of claim 21 , wherein the CO 2 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.
26. The process of claim 25 , wherein the temperature to which the CO 2 containing gas is cooled avoids a given denaturing of free carbonic anhydrase.
27. The process of claim 25 , wherein the temperature to which the CO 2 containing gas is cooled avoids a given denaturing of immobilized carbonic anhydrase.
28. The process of claim 21 , 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.
29. The process of claim 21 , comprising adding cations to the solution and adjusting the pH of the solution to precipitate a carbonated species of the cation.
30. The process of claim 29 , wherein the cations are selected from the group consisting of calcium, barium, magnesium and sodium ions.
31. The process of claim 21 , wherein the CO 2 containing gas comprises hot exhaust gas generated by combustion of fossil fuel or biomass.
32. The process of claim 31 , wherein heat is removed from the hot exhaust gas prior to reducing the amount of CO 2 contained therein and the heat is recycled.
33. A process comprising:
generating a CO 2 containing gas;
ensuring that the CO 2 containing gas has a temperature sufficiently low so as to maintain a desired catalytic effect of carbonic anhydrase or analog thereof;
reducing the amount of CO 2 contained in the CO 2 containing gas, thereby obtaining a low CO 2 gas, comprising:
contacting an aqueous liquid phase with the CO 2 containing gas to cause at least a portion of the CO 2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO 2 and producing a solution containing hydrogen ions and bicarbonate ions; and wherein said hydration is catalyzed by the carbonic anhydrase or the analogue thereof.
34. The process of claim 33 , wherein the CO 2 containing gas is subjected to a cooling step.
35. The process of claim 33 , wherein the CO 2 containing gas comprises hot exhaust gas generated by combustion of fossil fuel or biomass and wherein heat is removed from the hot exhaust gas in a heat exchanger prior to reducing the amount of CO 2 contained therein.
36. A process comprising:
generating steam using heat derived from combustion;
cooling an exhaust gas containing CO 2 to produce a cooled exhaust gas, said exhaust gas being derived from the combustion;
reducing the amount of CO 2 contained in the cooled exhaust gas, thereby obtaining a low CO 2 exhaust gas, wherein the step of reducing the amount of CO 2 comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO 2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO 2 and producing a solution containing hydrogen ions and bicarbonate ions; and wherein said hydration is catalyzed by carbonic anhydrase or an analogue thereof.
37. A process comprising:
cooling an exhaust gas containing CO 2 to produce a cooled exhaust gas, said exhaust gas being derived from combustion for producing heat used to generate steam;
reducing the amount of CO 2 contained in the cooled exhaust gas, thereby obtaining a low CO 2 exhaust gas, wherein the step of reducing the amount of CO 2 comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO 2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO 2 and producing a solution containing hydrogen ions and bicarbonate ions; and wherein said hydration is catalyzed by carbonic anhydrase or an analogue thereof.