Flue gas purification method

• US 20040062697A1
• Filed: 10/01/2002
• Published: 04/01/2004
• Est. Priority Date: 10/01/2002
• Status: Abandoned Application

• Current Assignee: Airborne Pollution Control Inc.
• Original Assignee: Airborne Pollution Control Inc.
• Inventors: Johnson, Dennis, Schaaf, Stephen, Bichel, Joe, Mortson, Murray
• Application Number:
  US10/260,465
• Publication Number:
  US 20040062697A1
• Time in Patent Office: Days
• US Class Current: 423/235
• CPC Class Codes: B01D 53/60 Simultaneously removing sulfur oxides and nitrogen oxides
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A method of scrubbing SO_x, NO_x compounds and other air toxins from a flue gas stream. In the method, two distinct unit operations are amalgamated to scrub SO_x, NO_x and other air toxins compounds from a flue gas stream. More specifically, there is a dry scrubbing operation and a wet scrubbing operation. The dry injection scrubbing operation involves contacting a flue gas stream containing SO_x and NO_x compounds with a sorbent for removing substantially all of the SO_x and NO_x compounds present in the stream. The second wet scrubbing operation involves contacting the stream to remove any residual SO_x, NO_x compounds, and other air toxins remaining in the stream.

Claims

1. A method of scrubbing SO_x and NO_x compounds from a flue gas stream, comprising:

a dry injection scrubbing operation and a wet scrubbing operation, said dry injection scrubbing operation including;

contacting a flue gas stream containing SO_x and NO_x compounds with a sorbent for removing substantially all of the SO_x and a large amount of NO_x compounds present in said stream; and

said wet scrubbing operation including;

contacting said stream to remove any residual SO_x and NO_x compounds remaining in said stream.

2. The method as set forth in claim 1, wherein said sorbent is a sodium based sorbent selected from the group consisting of sodium bicarbonate, sodium carbonate, sodium hydroxide, or combinations thereof.

3. The method as set forth in claim 1, wherein said sorbent is a calcium based sorbent selected from the group consisting of calcium carbonate, calcium bicarbonate, calcium hydroxide and combinations thereof.

4. The method as set forth in claim 1, wherein said sorbent is a magnesium based sorbent selected from the group consisting of magnesium carbonate, magnesium bicarbonate, magnesium hydroxide and combinations thereof.

5. The method as set forth in claim 1, wherein said sorbent comprises a combination of sodium, magnesium and calcium sorbents.

6. The method as set forth in claim 1, wherein said dry injection scrubbing operation produces sodium sulfate, sodium sulfite, sodium fluoride, sodium chloride, sodium nitrite, sodium carbonate and/or sodium nitrate.

7. The method as set forth in claim 1, wherein said SO_x and NO_x compounds include SO₂, SO₃, NO₂, N₂O₃, N₂O₅, N_xO_y and dimers thereof.

8. The method as set forth in claim 1, further including the step of recirculating unreacted sorbent for use in said wet scrubbing operation.

9. The method as set forth in claim 1, wherein said method further includes the step of oxidizing said flue gas stream.

10. The method as set forth in claim 9, wherein said method further includes the step of oxidizing said stream subsequent to treatment in either or both of said wet scrubbing operation and said dry scrubbing operation.

11. The method as set forth in claim 1, wherein said step of oxidizing includes the use of an oxidant selected from the group consisting of hydrogen peroxide, ozone, NaClO_x, where x is 1 through 4, or a combination thereof.

12. The method as set forth in claim 1, further including the step of reducing air toxic compounds present in said flue gas by reaction with said dry injection scrubbing operation and said wet scrubbing operation and oxidant addition.

13. A method of scrubbing SO_x and NO_x compounds from a flue gas stream, comprising:

a dry injection scrubbing operation and a wet scrubbing operation, said dry injection scrubbing operation including;

contacting a flue gas stream containing SO_x and NO_x compounds with a sorbent for removing substantially all of the SO_x and a large amount of NO_x compounds present in said stream;

said wet scrubbing operation including;

contacting said stream to remove any residual SO_x and NO_x compounds remaining in said stream; and

recirculating unreacted sorbent to said wet scrubbing operation.

14. The method as set forth in claim 13, further including the step of oxidizing said stream.

15. The method as set forth in claim 13, wherein said sodium based sorbents are selected from the group consisting of sodium based sorbents, calcium based sorbents, magnesium based sorbents and combinations thereof.

24. The method as set forth in claim 13, wherein said stream from said wet scrubbing operation is polished in a wet electrostatic precipitator.

16. A method of scrubbing SO_x and NO_x compounds from a flue gas stream, comprising:

a dry injection scrubbing operation and a wet scrubbing operation, said dry injection scrubbing operation including;

contacting a flue gas stream containing SO_x and NO_x compounds with a sorbent for removing substantially all of the SO_x and a large amount of NO_x compounds present in said stream; and

said wet scrubbing operation including;

scrubbing said stream from said dry injection scrubbing operation in the presence of an oxidant to remove any residual SO_x and NO_x compounds remaining in said stream.

17. The method as set forth in claim 16, further including the step of recirculating unreacted sorbent to said wet injection scrubbing operation.

18. The method as set forth in claim 16, wherein said oxidant is selected from the group consisting of hydrogen peroxide, ozone, NaClO_x, where x is 1 through 4, or a combination thereof.

19. The method as set forth in claim 16, wherein said stream from said dry injection scrubbing operation is exposed to oxidant.

20. The method as set forth in claim 16, wherein said stream from said dry injection scrubbing process produces sodium sulfate, sodium sulfite, sodium fluoride, sodium chloride, sodium nitrite, sodium carbonate and/or sodium nitrate.

23. the method as set forth in claim 16, wherein said stream from said wet scrubbing operation is polished in a wet electrostatic precipitator.

21. A method of scrubbing SO_x and NO_x compounds from a flue gas stream, comprising:

a wet injection scrubbing operation and a wet scrubbing operation, said wet injection scrubbing operation including;

contacting a flue gas stream containing SO_x and NO_x compounds with a sorbent solution for removing substantially all of the SO_x and a large amount of NO_x compounds present in said stream; and

said wet scrubbing operation including;

contacting said stream to remove any residual SO_x and NO_x compounds remaining in said stream.

22. The method as set forth in claim 21, wherein said stream from said wet scrubbing operation is polished in a wet electrostatic precipitator.

25. The method as set forth in claim 22, further including removing other air toxins and fine particulate matter in said electrostatic precipitator.