Reducing mercury emissions from the burning of coal

• US 7,776,301 B2
• Filed: 02/12/2010
• Issued: 08/17/2010
• 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:
  US12/705,196
• Publication Number:
  US 20100139482A1
• Time in Patent Office: 186 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: 423/242.1
• 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

Calcium bromide is a component of sorbent compositions that can be added on to coal to reduce the amount of sulfur gases released into the atmosphere from a coal burning facility. The sorbent components are added onto coal before the coal is added into the furnace and combusted. The fuel being burned is any fuel that contains sulfur, such as lignite, bituminous, and anthracite coal. The sorbent can contain other components such as silica, alumina, cement kiln dust, lime kiln dust, Portland cement, and aluminosilicate clay. Sulfur emissions are monitored during combustion of the fuel, and the rate of sorbent addition can be changed or a adjusted based on the monitored sulfur levels.

Claims

1. A method for reducing the amount of sulfur gases released into the atmosphere from 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; and

measuring the level of sulfur gases in the flue gas;

wherein the sorbent comprises calcium bromide.

2. A method according to claim 1, wherein the coal is lignite coal.

3. A method according to claim 1, wherein the coal is bituminous coal.

4. A method according to claim 1, wherein the coal is anthracite coal.

5. A method according to claim 1, further comprising controlling the rate of the sorbent addition based on the level of sulfur gases determined in the flue gas.

6. A method according to claim 1, comprising adding 1 to 9% by weight of sorbent based on the amount of coal being consumed.

7. A method according to claim 1, comprising adding an aqueous solution of calcium bromide onto the coal.

8. A method according to claim 7, comprising delivering the coal to the furnace while the coal is still wet from addition of the aqueous solution.

9. A method according to claim 1, wherein the sorbent further comprises at least 2% by weight of silica and at least 2% by weight of alumina.

10. A method according to claim 1, wherein the sorbent comprises at least one of cement kiln dust, lime kiln dust, and Portland cement.

11. A method according to claim 10, wherein the sorbent further comprises aluminosilicate clay.