Sorbents for the oxidation and removal of mercury

• US 10,343,114 B2
• Filed: 05/14/2018
• Issued: 07/09/2019
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Midwest Energy Emissions Corp.
• Original Assignee: Midwest Energy Emissions Corp.
• Inventors: Olson, Edwin S., Holmes, Michael J., Pavlish, John H.
• Primary Examiner(s): Orlando, Amber R
• Application Number:
  US15/978,760
• Publication Number:
  US 20180257031A1
• Time in Patent Office: 421 Days
• Field of Search: None
• CPC Class Codes: B01D 2251/108 Halogens or halogen compounds
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 2259/128 Solid reactants
• CPC Class Codes: B01D 53/10 with dispersed adsorbents
• CPC Class Codes: B01D 53/346 Controlling the process
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/83 with moving reactants
• CPC Class Codes: B01D 53/96 Regeneration, reactivation or recycling of reactants
• CPC Class Codes: B01J 20/0262 Compounds of O, S, Se, Te
• CPC Class Codes: B01J 20/027 Compounds of F, Cl, Br, I
• CPC Class Codes: B01J 20/04 comprising compounds of alkali metals, alkaline earth metals or magnesium
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/10 comprising silica or silicate
• CPC Class Codes: B01J 20/106 Perlite
• CPC Class Codes: B01J 20/12 Naturally occurring clays or bleaching earth
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/223 containing metals, e.g. organo-metallic compounds, coordination complexes
• CPC Class Codes: B01J 20/28004 : Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/3416 : of sorbents or filter aids comprising free carbon, e.g. activated carbon
• CPC Class Codes: B01J 2220/42 : Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32

Abstract

A promoted carbon and/or non-carbon base sorbent are described that are highly effective for the removal of mercury from flue gas streams. The promoted sorbent comprises a carbon and/or non-carbon base sorbent that has reacted with and contains forms of halogen and halides. Optional components may be added to increase and/or preserve reactivity and mercury capacity. These may be added directly with the base sorbent, or in-flight within a gas stream (air, flue gas, etc.), to enhance base sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The promoted sorbent can be regenerated and reused. Base sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active base sorbent into the mercury contaminated gas stream are described.

Claims

1. A method of separating mercury from a mercury-containing gas, the method comprising:

combusting coal in a combustion chamber, to provide the mercury-containing gas, wherein the mercury-containing gas comprises a halogen or halide promoter comprising HBr, Br⁻

, or a combination thereof, wherein

the coal comprises added Br₂, HBr, Br⁻

, or a combination thereof, added to the coal upstream of the combustion chamber, or

the combustion chamber comprises added Br₂, HBr, Br⁻

, or a combination thereof, or

a combination thereof;

injecting a sorbent material comprising activated carbon into the mercury-containing gas downstream of the combustion chamber;

contacting mercury in the mercury-containing gas with the sorbent, to form a mercury/sorbent composition;

separating the mercury/sorbent composition from the mercury-containing gas, to form a cleaned gas;

monitoring the mercury content of the cleaned gas; and

controlling, in response to the monitored mercury content of the cleaned gas, an injection rate of injecting the sorbent into the mercury-containing gas, the sorbent composition, or a combination thereof, so that the mercury content of the cleaned gas is maintained at or below a desired level.

2. The method of claim 1, comprising removing greater than 70 wt % of the mercury in the mercury-containing gas.

3. The method of claim 1, comprising removing greater than 70 wt % of the mercury in the mercury-containing gas on the sorbent.

4. The method of claim 1, wherein the sorbent in the mercury-containing gas comprises about 1 g to about 30 g of the halogen or halide promoter per 100 g of the sorbent material.

5. The method of claim 1, wherein the combustion chamber comprises the halogen or halide promoter.

6. The method of claim 1, wherein the coal comprises added Br₂, HBr, Br⁻

, or a combination thereof, added to the coal upstream of the combustion chamber.

7. The method of claim 1, wherein the promoter is contacted with the sorbent in vapor form, gaseous form, liquid form, or in an organic solvent.

8. The method of claim 1, further comprising injecting a secondary material into the mercury-containing gas downstream of the combustion chamber.

9. The method of claim 8, wherein the secondary material comprises a halogen, a compound derived from a halogen, a hydrohalide, a compound comprising a Group V or Group VI element and a molecular halogen, or a combination thereof.

10. The method of claim 1, wherein the sorbent material injected into the mercury-containing gas further comprises a non-carbon sorbent material.

11. The method of claim 10, wherein the non-carbon sorbent material comprises at least one of a porous felsic material, a vesicular felsic material, a porous basaltic material, a vesicular basaltic material, a clay-based compound, an alkaline compound, a calcium hydroxide compound, a sodium acetate compound, and a bicarbonate compound.

12. The method of claim 1, wherein the activated carbon comprises powdered activated carbon, granular activated carbon, or a combination thereof.

13. The method of claim 1, wherein the sorbent material injected into the mercury-containing gas is substantially free of halogen and halide promotion.

14. The method of claim 1, wherein the sorbent material injected into the mercury-containing gas is a promoted sorbent obtained by contacting a base sorbent with another halogen or halide promoter.

15. The method of claim 1, wherein the combustion chamber comprises a boiler.

16. The method of claim 1, wherein the mercury-containing gas is a flue gas.

17. The method of claim 1, wherein the injection of the sorbent material into the mercury-containing gas occurs upstream of an air pre-heater.

18. The method of claim 1, wherein the injection of the sorbent material into the mercury-containing gas occurs upstream of a particulate separator or a scrubber.

19. The method of claim 1, wherein the coal comprises added halide sorbent enhancement additive.

20. The method of claim 1, wherein the combustion chamber comprises added Br₂, HBr, Br⁻

, or a combination thereof.

21. The method of claim 1, wherein the coal comprises added sorbent enhancement additive that comprises Br⁻

.

22. The method of claim 21, wherein the sorbent enhancement additive comprises a bromide compound.

23. A method of separating mercury from a mercury-containing gas, the method comprising:

combusting coal in a combustion chamber, to provide the mercury-containing gas, wherein the mercury-containing gas comprises a halogen or halide promoter comprising HBr, Br⁻

, or a combination thereof, wherein

the coal comprises added Br₂, HBr, Br⁻

, or a combination thereof, added to the coal upstream of the combustion chamber, or

the combustion chamber comprises added Br₂, HBr, Br⁻

, or a combination thereof, or

a combination thereof;

injecting a sorbent material comprising activated carbon into the mercury-containing gas downstream of the combustion chamber;

contacting mercury in the mercury-containing gas with the sorbent, to form a mercury/sorbent composition; and

separating the mercury/sorbent composition from the mercury-containing gas, to form a cleaned gas.

24. A method of separating mercury from a mercury-containing gas, the method comprising:

combusting coal in a combustion chamber, to provide the mercury-containing gas, wherein the mercury-containing gas comprises a halogen or halide promoter comprising HBr, Br⁻

, or a combination thereof, wherein

the coal comprises added Br₂, HBr, Br⁻

, or a combination thereof, added to the coal upstream of the combustion chamber, or

the combustion chamber comprises added Br₂, HBr, Br⁻

, or a combination thereof, or

a combination thereof;

injecting a sorbent material comprising activated carbon into the mercury-containing gas downstream of the combustion chamber such that the activated carbon reacts with the halogen or halide promoter in the mercury-containing gas to form a promoted sorbent;

contacting mercury in the mercury-containing gas with the promoted sorbent, to form a mercury/sorbent composition;

separating the mercury/sorbent composition from the mercury-containing gas, to form a cleaned gas;

monitoring the mercury content of the cleaned gas; and

controlling, in response to the mercury content of the cleaned gas,

an injection rate of injecting the sorbent into the mercury-containing gas,

a rate of addition to the coal or the combustion chamber of the added Br₂, HBr, the bromide compound, or a combination thereof, or

a combination thereof,

so that the mercury content of the cleaned gas is maintained at or below a desired level.

25. A method of separating mercury from a mercury-containing gas, the method comprising:

combusting coal in a combustion chamber, to provide the mercury-containing gas, wherein

the coal comprises added Br₂, HBr, a bromide compound, or a combination thereof, added to the coal upstream of the combustion chamber, or

the combustion chamber comprises added Br₂, HBr, a bromide compound, or a combination thereof, or

a combination thereof,

injecting a sorbent material comprising activated carbon into the mercury-containing gas downstream of the combustion chamber;

contacting mercury in the mercury-containing gas with the sorbent, to form a mercury/sorbent composition; and

separating the mercury/sorbent composition from the mercury-containing gas, to form a cleaned gas.

26. The method of claim 25, wherein the coal comprises the added Br₂, HBr, the bromide compound, or a combination thereof, added to the coal upstream of the combustion chamber.

27. The method of claim 25, wherein the combustion chamber comprises the added Br₂, HBr, the bromide compound, or a combination thereof.

28. The method of claim 25, further comprising

monitoring the mercury content of the cleaned gas;

and

controlling, in response to the mercury content of the cleaned gas,

an injection rate of injecting the sorbent into the mercury-containing gas,

a rate of addition to the coal or the combustion chamber of the added Br₂, HBr, the bromide compound, or a combination thereof, or

a combination thereof,

so that the mercury content of the cleaned gas is maintained at or below a desired level.

29. The method of claim 25, wherein the mercury-containing gas comprises about 1 g to about 30 g of the element bromine per 100 g of the sorbent.

30. The method of claim 25, wherein the mercury/sorbent composition comprises the element bromine, the sorbent material, and mercury.