Coal Fired Flue Gas Treatment and Process

• US 20090090277A1
• Filed: 10/09/2007
• Published: 04/09/2009
• Est. Priority Date: 10/09/2007
• Status: Active Grant

• Current Assignee: Ceramatec, Inc.
• Original Assignee: Ceramatec, Inc.
• Inventors: Boxiey, Chett, Joshi, Ashok V.
• Granted Patent: US 7,655,202 B2
• Time in Patent Office: Days
• US Class Current: 106/709
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/501 by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
• CPC Class Codes: B01D 53/60 Simultaneously removing sulfur oxides and nitrogen oxides
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 22/064 of the alkaline-earth metals
• CPC Class Codes: C04B 22/085 containing nitrogen in the anion, e.g. nitrites
• CPC Class Codes: C04B 22/10 containing carbon in the anion
• CPC Class Codes: C04B 22/14 containing sulfur in the anion, e.g. sulfides
• CPC Class Codes: C04B 28/006 containing mineral polymers, e.g. geopolymers of the Davidovits type
• CPC Class Codes: Y02P 40/10 Production of cement, e.g. improving or optimising the production methods; Cement grinding
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10S 106/01 Fly ash

Abstract

A process for treating flue gas containing fly ash and carbon dioxide is disclosed. In the process, carbon dioxide and fly ash are contacted with an aqueous metal hydroxide solution to convert carbon dioxide into a metal carbonate, and wherein the metal carbonate and the metal hydroxide cause the fly ash to undergo a geopolymerization reaction and form a geopolymerized fly ash. The geopolymerized fly ash is recovered for disposal or for further use, such as a concrete additive.

Claims

1. A process of treating flue gas comprising fly ash and carbon dioxide, the process comprising:

contacting the carbon dioxide and the fly ash with an aqueous metal hydroxide solution to convert carbon dioxide into a metal carbonate, and wherein the metal carbonate and the metal hydroxide cause the fly ash to undergo a geopolymerization reaction and form a geopolymerized fly ash; and

recovering the geopolymerized fly ash.

2. The process according to claim 1, further comprising drying the geopolymerized fly ash.

3. The process according to claim 2, wherein the geopolymerized fly ash is dried by a dryer selected from a spray dryer, a drum dryer, a belt dryer, and combinations thereof.

4. The process according to claim 1, further comprising granulating the geopolymerized fly ash.

5. The process according to claim 3, wherein the geopolymerized fly ash is granulated by spray drying.

6. The process according to claim 3, wherein the geopolymerized fly ash is granulated by crushing.

7. The process according to claim 3, wherein the geopolymerized fly ash is a concrete additive.

8. The process according to claim 1, wherein the recovered geopolymerized fly ash is directly cast into a mold.

9. The process according to claim 1, wherein the recovered geopolymerized fly ash is directly added to a concrete mixture comprising Portland cement and aggregate.

10. The process according to claim 1, further comprising separating the fly ash from the flue gas and adding fly ash to the metal carbonate.

11. The process according to claim 1, wherein the flue gas further comprises oxides of nitrogen (NOx), and the process further comprises the step of:

contacting the NOx with the aqueous metal hydroxide solution to convert the NOx into a metal nitrite or a metal nitrate; and

mixing the fly ash with the metal nitrite or metal nitrate.

12. The process according to claim 1, wherein the flue gas further comprises oxides of sulfur (SOx), and the process further comprises the step of:

contacting the SOx with the aqueous metal hydroxide solution to convert the SOx into a metal sulfite or a metal sulfate; and

mixing the fly ash with the metal sulfite or metal sulfate.

13. The process according to claim 1, wherein the metal hydroxide comprises an alkali metal hydroxide.

14. The process according to claim 1, wherein the metal hydroxide comprises an alkaline earth metal hydroxide.

15. The process according to claim 1, wherein the metal hydroxide comprises slaked lime.

16. A process of treating flue gas comprising fly ash, carbon dioxide, NOx, and SOx, the process comprising:

separating the fly ash from the flue gas;

contacting the carbon dioxide, NOx, and SOx with an aqueous metal hydroxide solution to convert carbon dioxide into a metal carbonate, to convert the NOx to a metal nitrite or a metal nitrate, and to convert the SOx to a metal sulfite or metal sulfate; and

mixing the fly ash with the aqueous metal hydroxide solution and the metal carbonate, metal nitrite or metal nitrate, and metal sulfite or metal sulfate, to initiate a geopolymerization reaction and form a geopolymerized fly ash.

17. The process according to claim 16, further comprising recovering the geopolymerized fly ash.

18. The process according to claim 16, further comprising drying the geopolymerized fly ash.

19. The process according to claim 16, further comprising granulating the geopolymerized fly ash.

20. The process according to claim 16, wherein the aqueous metal hydroxide solution comprises an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof.

21. A process of treating flue gas comprising fly ash, carbon dioxide, NOx, and SOx, the process comprising:

separating the fly ash from the flue gas;

contacting the NOx with an aqueous metal hydroxide solution to convert the NOx to a metal nitrite or a metal nitrate;

contacting the SOx with an aqueous metal hydroxide solution to convert the SOx to a metal sulfite or metal sulfate;

contacting the carbon dioxide with an aqueous metal hydroxide solution to convert carbon dioxide into a metal carbonate; and

mixing the fly ash with the aqueous metal hydroxide solution and the metal carbonate, metal nitrite or metal nitrate, and metal sulfite or metal sulfate, to initiate a geopolymerization reaction and form a geopolymerized fly ash.

22. The process according to claim 21, further comprising recovering the geopolymerized fly ash.

23. The process according to claim 22, further comprising drying the geopolymerized fly ash.

24. The process according to claim 22, further comprising granulating the geopolymerized fly ash.

25. The process according to claim 21, wherein the aqueous metal hydroxide solution comprises an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof.