Reducing mercury emissions from the burning of coal

• US 8,920,158 B2
• Filed: 01/24/2014
• Issued: 12/30/2014
• Est. Priority Date: 03/17/2005
• Status: Active Grant

• Current Assignee: Nox Ii Ltd. (Arthur J Gallagher & Company)
• Original Assignee: Nox Ii Ltd. (Arthur J Gallagher & Company)
• Inventors: Comrie, Douglas C.
• Primary Examiner(s): VANOY, TIMOTHY C
• Application Number:
  US14/163,671
• Publication Number:
  US 20140141380A1
• Time in Patent Office: 340 Days
• Field of Search: 446/20, 446/21, 588/256, 588/257, 588/404, 588/412, 110/203, 110/342, 431/2, 423/210, 423/242.1
• US Class Current: 431/2
• CPC Class Codes: B01D 53/508 by treating the gases with solids
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: C04B 18/065 Residues from coal gasification
• CPC Class Codes: C04B 18/162 Cement kiln dust; Lime kiln dust
• CPC Class Codes: C04B 20/023 Chemical treatment
• CPC Class Codes: C04B 2103/0088 Compounds chosen for their latent hydraulic characteristics, e.g. pozzuolanes
• CPC Class Codes: C04B 28/04 Portland cements
• CPC Class Codes: C04B 40/0039 Premixtures of ingredients
• CPC Class Codes: C04B 40/0608 Dry ready-made mixtures, e.g. mortars at which only water or a water solution has to be added before use
• 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: C10L 10/02 for reducing smoke development
• CPC Class Codes: C10L 9/10 by using additives
• CPC Class Codes: F23J 15/003 for supplying chemicals to fumes, e.g. using injection devices
• CPC Class Codes: F23J 2215/60 Heavy metals; Compounds thereof
• CPC Class Codes: F23J 7/00 Arrangement of devices for supplying chemicals to fire
• CPC Class Codes: F23K 1/00 Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
• CPC Class Codes: F23K 2201/505 with additives
• CPC Class Codes: Y02E 20/32 Direct CO2 mitigation
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10S 423/05 Automatic, including computer, control

Abstract

Sorbent components containing halogen, calcium, alumina, and silica are used in combination during coal combustion to produce environmental benefits. Sorbents such as calcium bromide are added to the coal ahead of combustion and other components are added into the flame or downstream of the flame, preferably at minimum temperatures to assure complete formation of the refractory structures that result in various advantages of the methods. When used together, the components: reduce emissions of elemental and oxidized mercury; increase the level of Hg, As, Pb, and/or CI in the coal ash; decrease the levels of leachable heavy metals (such as Hg) in the ash, preferably to levels below the detectable limits; and make a highly cementitious ash product.

Claims

1. A method of reducing sulfur and mercury emissions that arise from combustion of coal, comprising burning the coal in the presence ofa mercury sorbent comprising a halogen compound andan alkaline powder sorbent comprising a calcium powder and an aluminosilicate material,

wherein the powder sorbent comprises sufficient silica and alumina to form a refractory mixture with calcium sulfate produced by combustion of the coal in the presence of the calcium powder.

2. The method of claim 1, wherein the mercury sorbent comprises a bromine compound or an iodine compound.

3. The method of claim 1, wherein the mercury sorbent comprises calcium bromide.

4. The method of claim 1, wherein the mercury sorbent comprises sodium iodide.

5. The method of claim 1, wherein the alkaline powder sorbent comprises greater than 5% by weight silica and greater than 5% by weight alumina.

6. The method of claim 1, wherein the alkaline powder sorbent comprises kaolin.

7. The method of claim 1, wherein the alkaline powder sorbent comprises calcium montmorillonite.

8. The method of claim 1, wherein the alkaline powder sorbent comprises metakaolin.

9. The method of claim 1, comprising applying the mercury sorbent onto coal before combustion.

10. The method of claim 1, comprising delivering the alkaline powder sorbent into the furnace during combustion.

11. The method of claim 1, comprising adding the alkaline powder sorbent in a location downstream of the furnace where the temperature is greater than 500°

C.

12. The method of claim 1, comprising adding the alkaline powder sorbent in a location downstream of the furnace where the temperature is greater than 800°

C.

13. The method of claim 1, comprising adding the alkaline powder sorbent in a location downstream of the furnace where the temperature is 1500°

F. to 2700°

F.

14. A method of reducing sulfur and mercury emissions arising from combustion of coal, comprising burning the coal in a coal burning facility in the presence of sorbent components comprising a halogen compound, a calcium powder, and an aluminosilicate material, wherein:

1) an alkaline powder sorbent comprising the calcium powder and the aluminosilicate material is added into the facility at a location where the temperature is greater than 500°

C., and

2) the alkaline powder sorbent comprises greater than 5% by weight silica and greater than 5% by weight alumina.

15. The method of claim 14, wherein the temperature at the location where the alkaline powder sorbent is added is greater than 800°

C.

16. The method of claim 14, wherein the temperature at the location where the alkaline powder sorbent is added is 1500-2700°

F.

17. The method of claim 14, wherein the alkaline powder sorbent comprises an aluminosilicate clay.

18. The method of claim 14, wherein the halogen compound comprises calcium bromide.

19. The method of claim 14, wherein the halogen compound comprises sodium iodide.

20. The method of claim 14, comprising adding a mercury sorbent comprising the halogen compound onto the coal before the coal is delivered into a furnace of the coal burning facility.