Method and apparatus for removing mercury from a flue gas stream

Patent metadata

Field	Value
Publication number	US-10471386-B2
Application number	US-201615040345-A
Country	US
Kind code	B2
Filing date	Feb 10, 2016
Priority date	Feb 10, 2016
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

The present invention relates generally to the field of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) and, in particular to a new and useful method and apparatus for capturing, oxidizing, lowering the concentration and/or level of, and/or eliminating mercury present in any flue gas and/or combustion gas stream. In one embodiment, the method and/or apparatus of the present invention is applied to boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices that have connected thereto at least one type of flue gas, or combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber).

First claim

What is claimed is:

1. A method for oxidizing elemental mercury present in a flue gas, or combustion gas, stream wherein the method comprises the steps of:
(I) burning at least one fuel so as to yield a mercury-containing flue gas, or combustion gas, stream wherein at least a portion of the mercury in the mercury-containing flue gas, or combustion gas, stream is elemental mercury;
(II) injecting one or more halogen-containing compounds into the mercury-containing flue gas, or combustion gas, stream in order to oxidize at least a portion of the elemental mercury in the mercury-containing flue gas, or combustion gas, stream into oxidized mercury and form one or more corresponding mercury halide compounds;
(III) injecting one or more sulfur-containing compounds and/or sulfide salt compounds into at least one air quality control device in order to convert the one or more mercury halide compounds into one or more mercury-sulfur compounds that is, or are, insoluble in an aqueous environment or an aqueous-based environment;
(IV) supplying at least one control device and one or more real-time mercury sensing devices, or sensors, wherein the at least one control device is operatively connected to the one or more real-time mercury sensing devices, or sensors, in order to provide real-time data on at least two of: (i) oxidized mercury concentration level in the flue gas, or combustion gas, stream, (ii) elemental mercury concentration level in the flue gas, or combustion gas, stream, and/or (iii) mercury speciation levels in the flue gas, or combustion gas, stream;
(V) using the real-time data from Step (IV) to determine the amount of both of: (a) the one or more halogen-containing compounds that are injected in Step (II), and (b) the one or more sulfur-containing compounds and/or sulfide salt compounds that are injected in Step (III) into the at least one air quality control device.

2. The method of claim 1 , wherein the at least one fuel is selected from at least one fossil fuel.

3. The method of claim 2 , wherein the at least one fossil fuel is coal.

4. The method of claim 1 , wherein the fuel is at least one biomass fuel.

5. The method of claim 1 , wherein the fuel is a mixture of at least one fossil fuel and at least one biomass fuel.

6. The method of claim 1 , wherein the one or more halogen-containing compounds are selected from one or more chlorine-containing compounds, one or more bromine-containing compounds, one or more iodine-containing compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.

7. The method of claim 6 , wherein the one or more chlorine-containing compounds are selected from one or more inorganic chlorine compounds, organic chlorine-containing compounds, one or more diatomic chlorine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.

8. The method of claim 6 , wherein the one or more bromine-containing compounds are selected from one or more inorganic bromine compounds, organic bromine-containing compounds, one or more diatomic bromine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.

9. The method of claim 6 , wherein the one or more iodine-containing compounds are selected from one or more inorganic iodine compounds, organic iodine-containing compounds, one or more diatomic iodine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.

10. The method of claim 6 , wherein the one or more halogen-containing compounds are selected from a combination of at least one chlorine-containing compound in combination with at least one bromine-containing compound and in further combination with at least one iodine-containing compound.

11. The method of claim 6 , wherein the one or more halogen-containing compounds are selected from any suitable combination of one or more alkali-metal halide compounds, one or more alkali-metal halogen-containing compounds, one or more alkali-earth halogen-containing compounds, one or more compounds that contain at least two different halogens, one or more compounds that contain at least one halogen and oxygen, one or more compounds that contain at least one halogen and hydrogen, one or more diatomic halogen-containing compounds, one or more organic compounds that contain therein at least one atom of chlorine, bromine, and/or iodine, or any combination of two or more thereof, or even all three thereof.

12. The method of claim 6 , wherein the one or more halogen-containing compounds are selected from NaCl, NaBr, NaI, KCl, KBr, KI, NaClO 2 , NaClO 3 , NaClO 4 , NaBrO 3 , NaIO 3 , NaIO 4 , Na 5 IO 6 , Na 3 H 2 IO 6 , KClO, KClO 3 , KClO 4 , KBrO 3 , KIBr 2 , KIO 3 , KIO 3 .HIO 3 , KIO 3 .2HIO 3 , KIO 4 , KI 3 .½H 2 O, MgCl 2 , MgBr 2 , MgI 2 , CaCl 2 , CaBr 2 , CaI 2 , Ca(ClO 3 ) 2 , (CaClO 4 ) 2 , Ca(BrO 3 ) 2 , Ca(IO 3 ) 2 , BrCl, IBr, IBr 3 , ICl, ICl 3 , ClO 2 , Cl 2 O 7 , Cl 2 O, ClO 4 , Cl 2 O 8 , BrO 2 , Br 2 O, Br 3 O 8 , IO 2 , I 2 O 4 , I 2 O 5 , I 4 O 9 , HCl, HClO 3 , HClO 4 , HBr, HBrO 3 , HI, HIO 3 , Cl 2 , Br 2 , I 2 , or any suitable combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.

13. The method of claim 1 , wherein the one or more sulfur-containing compounds and/or sulfide salt compounds are selected from sulfidic waste water, kraft caustic liquor, kraft carbonate liquor, potassium sulfide, sodium sulfide, sodium hydrogen sulfide (NaHS), thioacetamide, or any combination of two or more thereof, three of more thereof, four or more thereof, or even five or more thereof.

14. The method of claim 13 , wherein the one or more sulfur-containing compounds and/or sulfide salt compounds are supplied as an aqueous solution.

15. The method of claim 1 , wherein the one or more halogen-containing compounds are injected at a rate of between about 0.5 ppm to about 250 ppm based on the amount of mercury present in the fuel source.

16. The method of claim 1 , wherein the one or more halogen-containing compounds are injected at a rate of between about 2.5 ppm to about 225 ppm based on the amount of mercury present in the fuel source.

17. The method of claim 1 , wherein the one or more halogen-containing compounds are injected at a rate of between about 5 ppm to about 212.5 ppm based on the amount of mercury present in the fuel source.

18. The method of claim 1 , wherein the one or more halogen-containing compounds are injected at a rate of between about 17.5 ppm to about 150 ppm based on the amount of mercury present in the fuel source.

19. The method of claim 1 , wherein the one or more halogen-containing compounds are injected at a rate of between about 32.5 ppm to about 75 ppm based on the amount of mercury present in the fuel source.

20. The method of claim 1 , wherein the at least about 50 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogen-containing compounds.

21. The method of claim 1 , wherein the at least about 75 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogen-containing compounds.

22. The method of claim 1 , wherein the at least about 85 weight percent of the elemental mercury in the flue gas, or combustion gas, stre

Assignees

• Babcock & Wilcox Power Generat
• Babcock & Wilcox Co

Inventors

• Feeney Steven
• Gadgil Mandar R

Classifications

• F23J2215/60

  Heavy metals; Compounds thereof · CPC title

• F23J15/003

  for supplying chemicals to fumes, e.g. using injection devices · CPC title

• B01D2257/602

  Mercury or mercury compounds · CPC title

• F23J2219/40

  Sorption with wet devices, e.g. scrubbers · CPC title

• F23J15/04

  using washing fluids {(scrubbers for removing solids only F23J15/022)} · CPC title