Reduction of sulfur emissions from coal-fired boilers

• US 5,122,353 A
• Filed: 03/14/1991
• Issued: 06/16/1992
• Est. Priority Date: 03/14/1991
• Status: Expired due to Term

• Current Assignee: James M. Valentine
• Original Assignee: James M. Valentine
• Inventors: Valentine, James M.
• Primary Examiner(s): HELLER, GREGORY
• Application Number:
  US07/669,670
• Time in Patent Office: 460 Days
• Field of Search: 423/244 A, 423/242 A, 423/242 R, 423/244 R, 110/343, 110/345
• US Class Current: 423/244.05
• CPC Class Codes: B01D 53/508 by treating the gases with solids
• CPC Class Codes: C01F 11/464 Sulfates of Ca from gases containing sulfur oxides
• CPC Class Codes: F23J 15/006 Layout of treatment plant
• CPC Class Codes: F23J 2215/20 Sulfur; 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 7/00 Arrangement of devices for supplying chemicals to fire
• CPC Class Codes: F23K 1/02 Mixing solid fuel with a liquid, e.g. preparing slurries

Abstract

SO_x reduction treatments involving sorbent addition to coal-fired boilers is improved by retrofitting the boiler to burn fuel oil-in-water emulsions as a replacement for at least a portion of the coal. The ratio SO_x removed to particulates produced can be significantly increased.

Claims

1. A process for decreasing SO_x produced by a coal-fired boiler comprising a plurality of burners, the process comprising:

providing as at least one of the burners, a burner capable of burning an emulsified, pumpable fuel;

supplying to at least one of said burners an emulsified, pumpable fuel comprising from 10 to 70% of a continuous water phase and a discontinuous fluid hydrocarbon phase comprising at least 1% sulfur by weight;

burning said fuel, thereby creating a combustion effluent including SO_x ; and

contacting the combustion effluent with a SO_x sorbent selected from the group consisting of the hydroxides, oxides, and carbonates of calcium, magnesium, barium, sodium, and aluminum and mixtures of these.

2. A process according to claim 1 wherein at least a portion of the SO_x sorbent is injected with the fuel.

3. A process according to claim 2 wherein a portion of the SO_x sorbent is injected with the oil phase of the fuel.

4. A process according to claim 2 wherein a portion of the SO_x sorbent is injected with the water phase of the fuel.

5. A process according to claim 1 wherein at least a portion of the SO_x sorbent is injected as an aqueous mixture.

6. A process according to claim 1 wherein at least a portion of the SO_x sorbent is injected dry into the combustion effluent.

7. A process according to claim 1 wherein at least a portion of the SO_x sorbent is injected into a heat exchanger convective zone.

8. A process according to claim 1 wherein at least a portion of the SO_x sorbent is injected into duct work after an air heater section.

9. A process according to claim 1 wherein the total solids loading through the boiler is less than 125% increase over the baseline coal ash loading.

10. A process of claim 9 wherein the oil-in-water emulsion fuel is of a bitumen-in-water type comprising 25 to 70% water, ash of 0.04 to 0.25%, sulfur of 2.4 to 2.9% and a heating value of 12,100 to 13,000 Btu/lbs.

11. A process of claim 9 wherein the sorbents are injected in the fuel prior to combustion;

with the fuel in the combustion zone, in the heat exchanger convective zone;

in a separate reactor zone;

in the duct work after the air heater;

or upstream of a particulate collection device.

14. A process of claim 9 wherein the oil-in-water emulsion and sorbent are used on a new boiler specifically to allow for minor modification to established coal-fired boiler design criteria.

12. A process of 9 wherein the oil-in-water emulsion fuel has been biologically treated prior to combustion to liberate organic sulfur from the fuel in a water-soluble sulfate form.

13. A process of claim 12 wherein the liberated sulfate is partially or completely reacted with the sorbents in the fuel prior to combustion.