Method for controlling elemental mercury emissions

• US 20020068030A1
• Filed: 12/05/2000
• Published: 06/06/2002
• Est. Priority Date: 03/31/1999
• Status: Active Grant

• Current Assignee: Babcock & Wilcox Company (Babcock International Group PLC)
• Original Assignee: Babcock & Wilcox Company (Babcock International Group PLC)
• Inventors: Downs, William, Nolan, Paul S., Bailey, Ralph T.
• Granted Patent: US 6,855,859 B2
• Time in Patent Office: Days
• US Class Current: 423/210
• CPC Class Codes: B01D 2251/10 Oxidants
• CPC Class Codes: B01D 2251/50 Inorganic acids
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 47/06 Spray cleaning
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: F01N 13/004 specially adapted for marine propulsion, i.e. for receiving simultaneously engine exhaust gases and engine cooling water for submerged exhausting F01N13/12; treating exhaust by using liquids F01N3/04
• CPC Class Codes: F23J 15/003 for supplying chemicals to fumes, e.g. using injection devices
• CPC Class Codes: F23J 15/02 of purifiers, e.g. for removing noxious material traps for solid residues F23J3/04
• CPC Class Codes: F23J 15/04 using washing fluids scrubbers for removing solids only F23J15/022
• CPC Class Codes: F23J 2215/60 Heavy metals; Compounds thereof
• CPC Class Codes: F23J 2217/102 electrostatic
• CPC Class Codes: F23J 2219/40 Sorption with wet devices, e.g. scrubbers
• CPC Class Codes: F23J 2219/60 Sorption with dry devices, e.g. beds

Abstract

Chlorine and sulfide species are separately introduced to a flue gas passing through a scrubber in order to remove the elemental and oxidized mercury from the gas through the precipitation of mercuric sulfide at near 100% efficiency.

Claims

1. A method for controlling total mercury emissions in a flue gas comprising:

providing a flue gas at a selected temperature and having a quantity of elemental mercury;

treating the flue gas to convert the elemental mercury to oxidized mercury with at least one of;

chlorine and aqueous chlorine species; and

removing the oxidized mercury from the flue gas subsequent to and separately from the chlorine treatment step.

2. A method according to claim 1, wherein the aqueous chlorine species comprises an oxi-acid.

3. A method according to claim 2, wherein the removing mercury step comprises treating the flue gas with at least one of:

hydrogen sulfide gas and an aqueous sulfide species.

4. A method according to claim 1, wherein the selected temperature of the flue gas is between 125°

C. and 200°

C.

5. A method according to claim 1, wherein the removing mercury step comprises treating the flue gas with at least one of:

hydrogen sulfide gas and an aqueous sulfide species.

6. A method according to claim 5, wherein the selected temperature of the flue gas is between 125°

C. and 200°

C.

7. A method according to claim 2, wherein the selected temperature of the flue gas is between 125°

C. and 200°

C.

8. A method according to claim 2, wherein the oxi-acid is at least one of:

Cl₂O, ClO₂, ClO₄, ClO, HClO, HClO₂, HClO₃, and HClO₄.

9. A method according to claim 8, wherein the selected temperature is selected to allow use of aqueous species and low-temperature gases for use in the treating the flue gas to convert the elemental mercury to oxidized mercury.

10. A method according to claim 1, wherein the selected temperature is sufficient to allow use of aqueous species and low-temperature gases in the treating the flue gas to convert the elemental mercury to oxidized mercury.

11. A method according to claim 10, wherein substantially all of the elemental mercury is converted to oxidized mercury.

12. A method according to claim 1, wherein substantially all of the elemental mercury is converted to oxidized mercury.

13. A method according to claim 2, wherein substantially all of the elemental mercury is converted to oxidized mercury.

14. A method according to claim 4, wherein substantially all of the elemental mercury is converted to oxidized mercury.

15. A method according to claim 5, wherein substantially all of the elemental mercury is converted to oxidized mercury.

16. A method according to claim 8, wherein substantially all of the elemental mercury is converted to oxidized mercury.

17. A method according to claim 9, wherein substantially all of the elemental mercury is converted to oxidized mercury.

18. A method according to claim 1, wherein the aqueous chlorine species comprises a salt of an oxi-acid.