Complexation and removal of mercury from flue gas desulfurization systems

Patent metadata

Field	Value
Publication number	US-9764280-B2
Application number	US-201615241207-A
Country	US
Kind code	B2
Filing date	Aug 19, 2016
Priority date	Aug 21, 2015
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A method for the reduction and prevention of mercury emissions into the environment from combusted fossil fuels or other off-gases with the use of hypobromite is disclosed. The hypobromite is used for the capture of mercury from the resulting flue gases using a flue gas desulfurization system or scrubber. The method uses hypobromite in conjunction with a scrubber to capture mercury and lower its emission and/or re-emission with stack gases. The method allows the use of coal as a cleaner and environmentally friendlier fuel source as well as capturing mercury from other processing systems.

First claim

What is claimed is:

1. A method for reducing mercury emissions, comprising:
providing a gas stream comprising mercury; and
passing the gas stream into a scrubber comprising a scrubber liquor and hypobromite.

2. The method of claim 1 , wherein the hypobromite is mixed with a carrying agent selected from: limestone slurry, lime slurry, sodium-based alkali solution, trona-based solution, sodium carbonate solution, sodium hydroxide solution, and water.

3. The method of claim 2 , wherein the carrying agent is limestone slurry.

4. The method of claim 2 , wherein the carrying agent is water.

5. The method of claim 1 , further comprising mixing a bromine salt and an oxidant to form the hypobromite.

6. The method of claim 5 , wherein the oxidant is sodium hypochlorite.

7. The method of claim 1 , further comprising providing an antimicrobial agent which includes sodium bromide, sodium hypochlorite, and sulfamic acid.

8. The method of claim 1 , wherein the mercury is from combusted coal.

9. The method of claim 1 , wherein the scrubber is a wet scrubber selected from a spray tower system, a jet bubblers system, and a co-current packed tower system.

10. The method of claim 1 , wherein the hypobromite is added to the scrubber liquor and then added to the scrubber.

11. The method of claim 1 , wherein the hypobromite is added to the scrubber containing the scrubber liquor.

12. The method of claim 1 , wherein the hypobromite is added to virgin liquor then added to the scrubber.

13. The method of claim 1 , wherein the hypobromite is added to a make-up liquor then added to the scrubber.

14. The method of claim 1 , wherein the hypobromite is added to a return liquor then added to the scrubber.

15. The method of claim 1 , wherein the hypobromite is added to a reclaimed liquor then added to the scrubber.

16. The method of claim 1 , wherein the hypobromite is added to a liquor injected directly into flue gases then added to the scrubber.

17. The method of claim 1 , wherein the hypobromite is added to a recirculation loop of the scrubber liquor.

18. The method of claim 1 , wherein the hypobromite is added to a low solids return to the scrubber from a scrubber purge stream.

19. The method of claim 1 , wherein the hypobromite is added to an aqueous stream introduced into the scrubber, wherein the aqueous stream is selected from a demister and make-up water stream.

20. The method of claim 1 , wherein the mercury is from an incinerator, cement kiln, or an ore refinery.

Assignees

• Ecolab Usa Inc

Inventors

• Denny Nicholas R
• Keiser Bruce A
• Dotzauer David M
• Carlson Wayne M

Classifications

• B01D2251/108

  Halogens or halogen compounds · CPC title

• B01D53/1493

  Selection of liquid materials for use as absorbents · CPC title

• B01D2258/0291

  from waste incineration plants · CPC title

• F23J15/04

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

• B01D2258/0283

  Flue gases · CPC title