CONTROL OF WET SCRUBBER OXIDATION INHIBITOR AND BYPRODUCT RECOVERY

• US 20190076781A1
• Filed: 11/13/2018
• Published: 03/14/2019
• Est. Priority Date: 04/11/2012
• Status: Active Grant

• Current Assignee: ARQ Solutions Incorporated
• Original Assignee: ADA-ES, Inc. (Advanced Emissions Solutions, Inc.)
• Inventors: Sjostrom, Sharon, Baldrey, Kenneth E., Senior, Constance
• Granted Patent: US 10,758,863 B2
• Time in Patent Office: Days
• CPC Class Codes: B01D 15/08 Selective adsorption, e.g. chromatography
• CPC Class Codes: B01D 2257/202 Single element halogens
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/346 Controlling the process
• CPC Class Codes: B01D 53/40 Acidic components B01D53/44 takes precedence
• CPC Class Codes: B01D 53/50 Sulfur oxides B01D53/60 takes precedence
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/68 Halogens or halogen compounds
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: B01D 53/8665 Removing heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/96 Regeneration, reactivation or recycling of reactants
• CPC Class Codes: Y10S 210/914 Mercury

Abstract

The present disclose is directed to a method for controlling iodine levels in wet scrubbers, and, in particular, recirculating wet scrubbers by removing the iodine from the scrubbing solution, such as by using ion exchange, absorption, adsorption, precipitation, filtration, solvent extraction, ion pair extraction, and an aqueous two-phase extraction.

Claims

1. A method, comprising:

receiving a waste gas comprising an acid gas and at least one of elemental iodine and an iodine-containing composition;

passing the waste gas through a wet scrubber to remove at least a portion of the acid gas and the at least one of elemental iodine and an iodine-containing composition from the waste gas and form a scrubbing solution comprising at least one of an acid derived from the acid gas and a derivative thereof and at least one of elemental iodine and an iodine-containing composition;

removing, from the scrubbing solution, at least a portion of the at least one of elemental iodine and an iodine-containing composition, thereby reducing a concentration of the at least one of elemental iodine and an iodine-containing composition in the scrubbing solution; and

applying at least some of the removed at least a portion of the at least one of the elemental iodine and the iodine-containing composition to coal, wherein the coal and the removed at least a portion of the at least one of the elemental iodine and the iodine-containing composition are combusted to form the waste gas.

2. The method of claim 1, wherein the waste gas comprises elemental mercury and further comprising:

contacting an iodine-containing additive with the waste gas upstream of the wet scrubber to oxidize elemental mercury in the waste gas to a non-elemental mercury, wherein the removed at least a portion of the at least one of elemental iodine and iodine-containing composition is contacted with the waste gas upstream of the wet scrubber.

3. The method of claim 1, wherein the waste gas comprises elemental mercury and further comprising:

contacting an iodine-containing additive with a mercury-containing feed material, wherein the waste gas is derived from the mercury-containing feed material and wherein the removed at least a portion of the at least one of elemental iodine and iodine-containing composition is contacted with the mercury-containing feed material.

4. The method of claim 1, wherein the at least a portion of the at least one of elemental iodine and an iodine-containing composition is removed from the scrubbing solution by one or more of ion exchange, absorption, adsorption, precipitation, filtration, solvent extraction, ion pair extraction, and an aqueous two-phase extraction.

5. The method of claim 1, wherein the removing step comprises passing at least a portion of the scrubbing solution through a carbonaceous material to collect onto the carbonaceous material the at least one of elemental iodine and an iodine-containing composition.

6. The method of claim 1, wherein, after the removing step, the scrubbing solution is returned to the wet scrubber and wherein the wet scrubber is a flue-gas desulfurization scrubber.

7. The method of claim 6, wherein a flow of the scrubbing solution is controlled at a rate to maintain overall iodine concentration in the scrubber solution at less than about 100 ppm.

8. The method of claim 6, wherein a flow of an input scrubbing solution through is stopped when a concentration of the at least one of iodine and iodine-containing composition in an output scrubbing solution is at least a predetermined threshold and/or a difference between concentrations of the at least one of iodine and iodine-containing composition in the input and output scrubbing solutions is at least a predetermined threshold.

9. The method of claim 8, wherein the flow through the input scrubbing solution is stopped automatically by a microprocessor and a flow of the output scrubbing solution through is initiated automatically by the microprocessor in response to an absolute value of the concentration of the at least one of iodine and iodine-containing composition in the output scrubbing solution reaching the at least a predetermined threshold.

10. The method of claim 4, wherein the at least a portion of the at least one of elemental iodine and an iodine-containing composition is removed from the scrubbing solution by an organic solvent.

11. The method of claim 10, wherein the organic solvent is a hydrocarbon solvent.

12. The method of claim 10, wherein the scrubbing solution and the organic solvent are immiscible, wherein the one or more of the iodine and the iodine-containing compositions have different relative solubilities in scrubbing solution and the organic solvent, and wherein removal is removal is effected by the different relative solubilities of the one or more of the iodine and the iodine-containing compounds in the immiscible scrubbing solution and the organic solvent.

13. The method of claim 4, wherein the one or more of the iodine and the iodine-containing compositions are extracted from one liquid phase into another liquid phase.

14. The method of claim 4, wherein the solvent extraction is effected without a chemical change by one or more of a solvation mechanism, an ion exchange mechanism, an ion-pair extraction, and an aqueous two-phase extraction.

15. A method, comprising:

receiving a waste gas comprising an acid gas and elemental mercury;

contacting an iodine-containing additive with the waste gas upstream of a wet scrubber to oxidize elemental mercury in the waste gas to a non-elemental mercury passing the waste gas through a wet scrubber to remove at least a portion of the acid gas and at least one of elemental iodine and an iodine-containing composition derived from the iodine-containing additive and form a scrubbing solution comprising at least one of an acid and salt derived from the acid gas and the at least one of elemental iodine and an iodine-containing composition;

removing, from the scrubbing solution, at least a portion of the at least one of elemental iodine and an iodine-containing composition, thereby reducing a concentration of the at least one of elemental iodine and an iodine-containing composition in the scrubbing solution; and

applying at least some of the removed at least a portion of the at least one of the elemental iodine and the iodine-containing composition to coal, wherein the coal and the removed at least a portion of the at least one of the elemental iodine and the iodine-containing composition applied to the coal are combusted to form the received waste gas.

16. The method of claim 15, wherein the at least a portion of the at least one of elemental iodine and an iodine-containing composition is removed from the scrubbing solution by one or more of ion exchange, absorption, adsorption, precipitation, filtration, solvent extraction, ion pair extraction, and an aqueous two-phase extraction.

17. The method of claim 16, wherein, after the removing step, the scrubbing solution is returned to the wet scrubber and wherein the wet scrubber is a flue-gas desulfurization scrubber.

18. The method of claim 15, wherein a flow of the scrubbing solution is controlled at a rate to maintain an overall iodine concentration in the scrubber solution at less than about 100 ppm.

19. The method of claim 15, wherein a flow of an input scrubbing solution through a first bed is stopped when a concentration of the at least one of iodine and iodine-containing composition in an output scrubbing solution is at least a predetermined threshold and/or a difference between concentrations of the at least one of iodine and iodine-containing composition in the input and output scrubbing solutions is at least a predetermined threshold.

20. A method, comprising:

receiving a waste gas comprising at least one of elemental iodine and an iodine-containing composition;

passing the waste gas through a wet scrubber to remove the at least one of elemental iodine and an iodine-containing composition from the waste gas and form a scrubbing solution comprising the at least one of elemental iodine and an iodine-containing composition; and

removing, from the scrubbing solution, at least a portion of the at least one of elemental iodine and an iodine-containing composition by one or more of ion exchange, absorption, adsorption, precipitation, filtration, solvent extraction, ion pair extraction, and an aqueous two-phase extraction, thereby reducing a concentration of the at least one of elemental iodine and an iodine-containing composition in the scrubbing solution; and

applying the removed at least a portion of the at least one of elemental iodine and an iodine-containing composition to coal, wherein the coal and the removed at least a portion of the at least one of elemental iodine and an iodine-containing composition applied to the coal are combusted to form the received waste gas.