METHOD AND SYSTEMS FOR REMOVING MERCURY FROM COMBUSTION EXHAUST GAS

• US 20080069749A1
• Filed: 09/18/2006
• Published: 03/20/2008
• Est. Priority Date: 09/18/2006
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Liu, Ke, Deluga, Gregg Anthony, Kulkarni, Parag Prakash, Lissianski, Vitali Victor, Zamansky, Vladimir M.
• Granted Patent: US 7,767,174 B2
• Time in Patent Office: Days
• US Class Current: 423/210
• CPC Class Codes: B01D 2251/206 Ammonium compounds
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 53/8665 Removing heavy metals or compounds thereof, e.g. mercury

Abstract

A method for facilitating reducing mercury in a fluid stream using a catalytic bed assembly including at least a first catalytic bed. The method includes receiving a flow of fluid including mercury at the catalytic bed assembly; injecting a flow of a compound including ammonia and a first mercury oxidizer upstream of the first catalytic bed; and oxidizing the mercury using the mercury oxidizer and the catalytic bed assembly.

Claims

1. A method of reducing mercury in a fluid stream using a catalytic bed assembly including at least a first catalytic bed, said method comprising:

receiving a flow of fluid including mercury at the catalytic bed assembly;

injecting a flow of a compound including ammonia and a first mercury oxidizer upstream of the first catalytic bed; and

oxidizing the mercury using the mercury oxidizer and the catalytic bed assembly.

2. A method in accordance with claim 1 wherein injecting a flow of a compound comprises injecting a flow of an ammonium halide compound.

3. A method in accordance with claim 1 wherein injecting a flow of a compound comprises injecting a flow of at least one of ammonia chloride, ammonia bromide, or ammonia iodide.

4. A method in accordance with claim 1 wherein injecting a flow of a compound comprises injecting a mixture of at least one of ammonia chloride, ammonia bromide, and ammonia iodide with at least one of urea and NH₃ solution.

5. A method in accordance with claim 1 further comprising injecting a second mercury oxidizer including at least one of CaCl₂, CaBr₂, MgCl₂, MgBr₂, NaCl, NaBr, KCl, and KBr upstream of the catalytic bed assembly.

6. A method in accordance with claim 5 wherein injecting a second mercury oxidizer comprises injecting the second mercury oxidizer when a temperature of the flow of fluid is between about 371°

C. (700°

F.) and 649°

C. (1200°

F.).

7. A method in accordance with claim 5 wherein injecting a second mercury oxidizer comprises injecting the second mercury oxidizer when a temperature of the flow of fluid is between about 482°

C. (900°

F.) and 649°

C. (1200°

F.).

8. A method in accordance with claim 5 wherein injecting a second mercury oxidizer comprises injecting the second mercury oxidizer when a temperature of the flow of fluid is between about 427°

C. (800°

F.) and 538°

C. (1000°

F.).

9. A method in accordance with claim 1 wherein the catalytic bed assembly includes an ammonia oxidation catalyst bed, said method further comprises injecting a mercury oxidation catalyst upstream of the ammonia oxidation catalyst bed.

10. A method in accordance with claim 9 further comprising increasing the efficiency of at least one of the ammonia oxidation catalytic bed and the first catalytic bed by decomposing ammonium chloride to ammonia ions and chloride ions and reducing nitrogen oxides to nitrogen and water using the ammonia ions.

11. A method in accordance with claim 1 further comprising injecting at least one of fly ash and active carbon particles in the flow of fluid.

12. A catalytic bed assembly comprising:

a select catalyst reduction (SCR) catalytic bed configured to facilitate at least one of a reduction reaction of nitrogen oxides and an oxidation reaction of mercury; and

a first injection port positioned upstream of said SCR catalytic bed, said injection port configured to inject a flow of mercury oxidizer.

13. A catalytic bed assembly in accordance with claim 12 wherein said SCR catalytic bed comprises at least one catalyst configured to facilitate at least one of;

decomposition of ammonium chloride to NH₄⁺ and Cl^—

; and

reduction of NO_x to N₂ and H₂O via the NH₄⁺.

14. A catalytic bed assembly in accordance with claim 12 further comprising an ammonium oxidation catalyst bed positioned downstream of said SCR catalyst bed.

15. A catalytic bed assembly in accordance with claim 14 further comprising a second injection port positioned upstream of said ammonia oxidation catalytic bed.

16. A catalytic bed assembly in accordance with claim 15 wherein said second injection port is configured to inject a quantity of a mercury oxidation catalyst.

17. A catalytic bed assembly in accordance with claim 15 wherein said second injection port is positioned downstream said SCR catalytic bed and upstream said ammonia oxidation catalytic bed.

18. A combustion chamber exhaust system comprising:

a combustion chamber configured to combust materials including mercury such that mercury exits the combustion chamber in a fluid flow stream;

an SCR catalytic bed configured to facilitate at least one of a reduction reaction of nitrogen oxides and an oxidation reaction of mercury; and

a first injection port positioned upstream of said SCR catalytic bed, said injection port configured to inject a flow of mercury oxidizer.

19. A catalytic bed assembly in accordance with claim 18 further comprising an ammonium oxidation catalyst bed positioned downstream of said SCR catalyst bed.

20. A catalytic bed assembly in accordance with claim 19 further comprising a second injection port positioned upstream of said ammonium oxidation catalytic bed.

21. A catalytic bed assembly in accordance with claim 20, wherein second said injection port configured to inject a quantity of mercury oxidation catalyst.

22. A catalytic bed assembly in accordance with claim 18 further comprising an oxidizing agent sub-system coupled in flow communication with said first injection port, said oxidizing agent sub-system configured to form and store at least one mercury oxidizer.