Methods for removal of mercury from flue gas

• US 8,309,046 B2
• Filed: 04/07/2011
• Issued: 11/13/2012
• Est. Priority Date: 04/07/2010
• Status: Active Grant

• Current Assignee: Calgon Carbon Corporation (Kuraray Company Limited)
• Original Assignee: Calgon Carbon Corporation (Kuraray Company Limited)
• Inventors: Pollack, Nicholas R., Hayden, Richard A.
• Primary Examiner(s): VANOY, TIMOTHY C
• Application Number:
  US13/082,337
• Publication Number:
  US 20110250111A1
• Time in Patent Office: 586 Days
• Field of Search: 423/210, 502/400, 502/416, 502/417
• US Class Current: 423/210
• CPC Class Codes: B01D 2251/108 Halogens or halogen compounds hydrogen halides B01D2251/50
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2251/60 Inorganic bases or salts
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/25 Coated, impregnated or composite adsorbents
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01D 53/10 with dispersed adsorbents
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01J 20/0288 Halides of compounds other than those provided for in B01J20/046
• CPC Class Codes: B01J 20/046 containing halogens, e.g. halides
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/28057 Surface area, e.g. B.E.T specific surface area
• CPC Class Codes: B01J 20/28069 Pore volume, e.g. total pore volume, mesopore volume, micropore volume
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3234 Inorganic material layers
• CPC Class Codes: B01J 20/3236 containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• CPC Class Codes: B03C 3/017 Combinations of electrostatic separation with other processes, not otherwise provided for
• CPC Class Codes: C10L 10/00 : Use of additives to fuels or fires for particular purposes additives for liquid carbonaceous fuels characterised by their chemical nature C10L1/10; using binders for briquetting solid fuels C10L5/10; using additives to improve the combustion of solid fuels C10L9/10
• CPC Class Codes: F23J 7/00 : Arrangement of devices for supplying chemicals to fire
• CPC Class Codes: Y02E 20/12 : Heat utilisation in combustion or incineration of waste
• CPC Class Codes: Y02P 20/129 : Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]

Abstract

Methods and systems for reducing mercury emissions are provided herein. The methods, generally, include the steps of burning a heavy metal containing fuel source and introducing sorbent materials and introducing one or more halogen compounds into the combustion chamber and/or exhaust stream to remove the heavy metal.

Claims

1. A method for reducing heavy metal emissions comprising:

burning a heavy metal containing fuel in a combustion chamber;

introducing molecular halogen or one or more halogen precursors into the combustion chamber or an exhaust stream produced as a result of the burning of the heavy metal containing fuel; and

introducing a sorbent having a mean particle diameter of less than 15 μ

m into an exhaust stream resulting from burning of the heavy metal containing fuel in the combustion chamber;

wherein the halogen and sorbent material are introduced at a ratio of from about 0.7 to about 5.7 moles of halogen per pound (lb) of sorbent material.

2. The method of claim 1, wherein the halogen and sorbent material are introduced at a ratio of from about 0.8 to about 3.1 moles of halogen per pound (lb) of sorbent material.

3. The method of claim 1, wherein the halogen and sorbent material are introduced at a ratio of about 2.0 moles of halogen per pound (lb) of sorbent material.

4. The method of claim 1, wherein the sorbent material is activated carbon.

5. The method of claim 1, wherein the one or more halogen precursors are selected from the group consisting of calcium hypochlorite, calcium hypobromite, calcium hypoiodite, calcium chloride, calcium bromide, calcium iodide, magnesium chloride, magnesium bromide, magnesium iodide, sodium chloride, sodium bromide, sodium iodide, ammonium chloride, ammonium bromide, ammonium iodide, potassium tri-chloride, potassium tri-bromide, and potassium tri-iodide.

6. The method of claim 1, wherein the halogen precursor is selected from the group consisting of calcium bromide (CaBr₂), ammonium bromide (NH₄Br), and combinations thereof.

7. The method of claim 1, wherein the halogen precursor are in an aqueous solution.

8. The method of claim 1, wherein the halogen precursor is a solid.

9. The method of claim 1, wherein the halogen or halogen precursor is a gas.

10. The method of claim 1, wherein the halogen or halogen precursor is introduced into the exhaust stream having a temperature greater than about 1000°

F.

11. The method of claim 1, wherein the sorbent material has a mean particle diameter (MPD) of from about 2 μ

m to 10 μ

m.

12. The method of claim 1, wherein the sorbent material is injected into the exhaust stream at a rate selected from the group consisting of less than about 5 pounds per million actual cubic (lbs/MMacf), less than about 4 lbs/MMacf, less than about 3, lbs/MMacf, and less than about 1 lbs/MMacf.

13. The method of claim 1, wherein the sorbent material is injected into the exhaust stream at a rate of less than 100 pounds/hr.

14. The method of claim 1, wherein the sorbent material is injected upstream of an air pre-heater (APH).

15. The method of claim 1, wherein about 90% of the mercury in the fuel source is removed.

16. The method of claim 1, wherein the fuel source is coal.

17. The method of claim 1, wherein the halogen or halogen precursor is introduced into the combustion chamber.

18. The method of claim 1, wherein the halogen precursor is applied to the fuel before the fuel is introduced into the combustion chamber.

19. The method of claim 1, wherein the halogen is applied to the sorbent material.

20. The method of claim 17, wherein the sorbent material has a mean particle diameter (MPD) of from about 2 μ

m to 10 μ

m.

21. The method of claim 17, wherein the halogen is provided to the sorbent material at a concentration of from about 0.7 moles of halogen per pound of sorbent material to about 5.7 moles of halogen per pound of sorbent material.

22. The method of claim 17, wherein the halogen is provided to the sorbent material at a concentration of from about 0.8 moles of halogen per pound of sorbent material to about 3.1 moles of halogen per pound of sorbent material.

23. The method of claim 17, wherein sorbent material has a mean particle diameter (MPD) of about 6 μ

m and the halogen is applied to the sorbent material to produce a final concentration of about 2.0 moles of halogen per pound of sorbent material.

24. The method of claim 17, wherein the sorbent material is activated carbon having a particle diameter (MPD) of about 6 μ

m and the halogen is applied to the activated carbon to produce a final concentration of about 2.0 moles of halogen per pound of sorbent material.

25. The method of claim 17, wherein the halogen is applied to the sorbent material by wet impregnation.

26. The method of claim 17, wherein the halogen is applied to the sorbent material by combining dry activated carbon with dry halogen salt.

27. The method of claim 26, wherein the halogen salt is selected from the group consisting of calcium bromide (CaBr₂), ammonium bromide (NH₄Br) and combinations thereof.

28. A flue gas sorbent comprising:

a sorbent material having a mean particle diameter (MPD) of less than about 15 μ

m; and

one or more halogens associated with the sorbent material at a ratio of from about 0.7 to about 5.7 moles of halogen per pound (lb) of sorbent material.

29. The flue gas sorbent of claim 28, wherein the one or more halogens are associated with the sorbent material at a ratio of from about 0.8 to about 3.1 moles of halogen per pound (lb) of sorbent material.

30. The flue gas sorbent of claim 28, wherein the one or more halogens are associated with the sorbent material at a ratio of about 2.0 moles of halogen per pound (lb) of sorbent material.

31. The flue gas sorbent of claim 28, wherein the sorbent material has a mean particle diameter (MPD) of from about 2 μ

m to 10 μ

m.

32. The flue gas sorbent of claim 28, wherein sorbent material has a mean particle diameter (MPD) of about 6 μ

m and the halogen is associated with the sorbent material at a final concentration of about 2.0 moles of halogen per pound of sorbent material.

33. The flue gas sorbent of claim 28, wherein the sorbent material is activated carbon having a particle diameter (MPD) of about 6 μ

m and the halogen is associated with the activated carbon at a final concentration of about 2.0 moles of halogen per pound of sorbent material.

34. The flue gas sorbent of claim 28, wherein the halogen is applied to the sorbent material by wet impregnation.

35. The flue gas sorbent of claim 28, wherein the halogen is applied to the sorbent material by combining dry activated carbon with dry halogen salt.

36. The flue gas sorbent of claim 35, wherein the halogen salt is selected from the group consisting of calcium bromide (CaBr₂), ammonium bromide (NH₄Br) and combinations thereof.