Sorbents for coal combustion

• US 7,988,939 B2
• Filed: 07/19/2010
• Issued: 08/02/2011
• 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:
  US12/839,154
• Publication Number:
  US 20100323308A1
• Time in Patent Office: 379 Days
• Field of Search: 431/2, 423/210, 423/242.1, 423/244.01, 423/244.07, 423/DIG.5, 445/05, 446/03, 446/04, 446/20, 446/21, 446/22, 446/24, 422/105, 422/108, 422/111
• US Class Current: 423/210
• CPC Class Codes: B01D 2253/104 Alumina
• CPC Class Codes: B01D 2253/11 Clays
• CPC Class Codes: B01D 2257/30 Sulfur compounds
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: B01D 53/30 Controlling by gas-analysis apparatus regulating non electrical variables in general G05D
• CPC Class Codes: B01D 53/485 containing only one sulfur compound other than sulfur oxides or hydrogen sulfide
• 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: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/046 containing halogens, e.g. halides
• CPC Class Codes: B01J 20/06 comprising oxides or hydroxides of metals not provided for in group B01J20/04
• CPC Class Codes: B01J 20/12 Naturally occurring clays or bleaching earth
• CPC Class Codes: B01J 20/16 Alumino-silicates B01J20/12 takes precedence
• CPC Class Codes: B01J 2220/42 Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• 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 15/00 Arrangements of devices for treating smoke or fumes
• CPC Class Codes: F23J 15/025 : using filters
• CPC Class Codes: F23J 15/04 : using washing fluids scrubbers for removing solids only F23J15/022
• 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: Y02P 40/10 : Production of cement, e.g. improving or optimising the production methods; Cement grinding
• CPC Class Codes: Y10S 423/05 : Automatic, including computer, control

Abstract

Sorbent compositions containing halogen and calcium are added to coal to mitigate the release of sulfur and/or other harmful elements, including mercury, into the environment during combustion of coal containing natural levels of mercury.

Claims

1. A method for reducing emissions of sulfur and/or other harmful elements arising from combustion of coal in a coal burning facility, the method comprising:

applying a sorbent composition comprising calcium and bromine onto coal;

burning the coal containing the calcium and bromine sorbent composition to produce ash and combustion gases;

measuring a level of sulfur in the combustion gases; and

adjusting the level of calcium added onto the coal based on the measured level of sulfur.

2. A method according to claim 1, wherein 90% of the mercury in the coal is captured in the ash to prevent its release into the environment.

3. A method according to claim 1, further comprising adjusting the level of bromine added to the coal up or down or leaving the level of bromine unchanged, depending on the level of mercury measured in the combustion gases.

4. A method according to claim 1, wherein the sorbent composition comprises calcium bromide.

5. A method according to claim 4, wherein the sorbent composition comprises an aqueous solution containing 5-60% by weight calcium bromide.

6. A method according to claim 1, wherein the sorbent composition comprises an inorganic salt containing bromine.

7. A method according to claim 1, wherein the sorbent composition comprises an organic bromine compound.

8. A method according to claim 1, wherein the sorbent composition comprises calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, calcium sulfate, calcium bisulfate, calcium nitrate, calcium nitrite, calcium acetate, calcium citrate, calcium phosphate, or calcium hydrogen phosphate.

9. A method according to claim 1, wherein the sorbent composition comprises a calcium mineral.

10. A method according to claim 1, wherein the sorbent composition comprises an organic calcium compound.

11. A method according to claim 1, wherein the sorbent composition comprises a basic powder containing calcium.

12. A method according to claim 11, wherein the basic powder is selected from portland cement, cement kiln dust, and lime kiln dust.

13. A method according to claim 1, wherein the sorbent composition comprises an aluminosilicate clay.

14. A method for reducing the amount of sulfur gases released into the atmosphere from burning coal in the furnace of a coal burning plant, comprising

adding a sorbent to the coal prior to combustion;

delivering the coal into a furnace;

burning the coal in the furnace to produce ash and flue gases;

removing ash from the flue gas by capturing the ash in a particulate removal system disposed in a convective pathway of the plant downstream of the furnace; and

measuring the level of sulfur gases in the flue gas;

wherein the sorbent comprises calcium bromide and the captured ash contains 70% or more by weight of the mercury present in the coal being burned.

15. A method according to claim 14, wherein the coal is lignite coal.

16. A method according to claim 14, wherein the coal is bituminous coal.

17. A method according to claim 14, wherein the coal is anthracite coal.

18. A method according to claim 14, further comprising controlling the rate of the sorbent addition based on the level of sulfur gases determined in the flue gas.

19. A method according to claim 14, comprising adding 0.01-10% by weight of sorbent based on the amount of coal being consumed.

20. A method according to claim 14, comprising adding 0.1-1% by weight of sorbent based on the amount of coal being consumed.

21. A method according to claim 14, comprising adding about 0.3% by weight of sorbent based on the amount of coal being consumed.

22. A method according to claim 14, comprising adding an aqueous solution of calcium bromide onto the coal.

23. A method according to claim 22, comprising delivering the coal to the furnace while the coal is still wet from addition of the aqueous solution.

24. A method according to claim 14, wherein the sorbent further comprises at least 2% by weight of silica and at least 2% by weight of alumina.

25. A method according to claim 14, wherein the sorbent comprises at least one of cement kiln dust, lime kiln dust, and portland cement.

26. A method according to claim 25, wherein the sorbent further comprises aluminosilicate clay.

27. A method according to claim 14, wherein the captured ash contains 90% or more by weight of the mercury present in the coal being burned.