Method and apparatus for removing sulfur oxides from gas

• US 10,675,584 B2
• Filed: 08/15/2019
• Issued: 06/09/2020
• Est. Priority Date: 03/15/2017
• Status: Active Grant

• Current Assignee: Jiangnan Environmental Protection Group Inc.
• Original Assignee: Jiangnan Environmental Protection Group Inc.
• Inventors: Luo, Jing, Xu, Changxiang
• Primary Examiner(s): Vanoy, Timothy C
• Application Number:
  US16/541,351
• Publication Number:
  US 20190374906A1
• Time in Patent Office: 299 Days
• CPC Class Codes: B01D 2009/0086 Processes or apparatus therefor
• CPC Class Codes: B01D 2247/04 Regenerating the washing fluid recovering paint spray booth B05B14/462
• CPC Class Codes: B01D 2251/10 Oxidants
• CPC Class Codes: B01D 2252/102 Ammonia
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/406 Ammonia
• CPC Class Codes: B01D 47/06 Spray cleaning
• CPC Class Codes: B01D 51/10 Conditioning the gas to be cleaned
• CPC Class Codes: B01D 53/501 by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
• CPC Class Codes: B01D 53/502 characterised by a specific solution or suspension
• CPC Class Codes: B01D 53/504 characterised by a specific device
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: B01D 53/96 Regeneration, reactivation or recycling of reactants
• CPC Class Codes: B01D 9/0018 Evaporation of components of the mixture to be separated
• CPC Class Codes: C01C 1/24 Sulfates of ammonium C01C1/14 takes precedence

Abstract

Methods, apparatus, and compositions for cleaning gas. The use of segmented multistage ammonia-based liquid spray with different oxidation potentials to remove sulfur compounds from gas. The use of different oxidation potentials may reduce unwanted ammonia slip.

Claims

1. A method for cleaning a gas, the method comprising:

feeding the gas into a first chamber that includes;

a first liquid spray array; and

a second liquid spray array, the first liquid spray array and the second liquid spray array being located at different locations within the first chamber;

producing an ammonia bearing liquid at a first source;

producing an ammonia bearing liquid at a second source;

supplying the ammonia bearing liquid produced at the first source to the first liquid spray array;

supplying the ammonia bearing liquid produced at the second source to the second liquid spray array, the first source and the second source being configured so that the first source produces ammonia bearing liquid that has a different sulfur absorbing capacity than that produced by the second source, the first source and the second source being located within a second chamber, the second chamber including an oxidizing chamber;

spraying the gas with a first ammonia bearing liquid from the first liquid spray array; and

spraying the gas with a second ammonia bearing liquid from the second liquid spray array.

2. The method of claim 1 wherein the first source produces ammonia bearing liquid having an ammonia concentration that is different from the ammonia concentration of the liquid produced by the second source.

3. The method of claim 1 wherein at least one of the ammonia bearing liquid of the first source and the ammonia bearing liquid of the second source has a pH greater than 4.6.

4. The method of claim 1 wherein the first chamber is configured to be maintained at an operating temperature between 30°

C. (86°

F.) and 70°

C. (158°

F.).

5. The method of claim 1 further comprising fluidically communicating the oxidizing chamber with the first chamber via an oxidizing chamber conduit.

6. The method of claim 5 wherein the oxidizing chamber includes the first source and the second source.

7. The method of claim 6 wherein the oxidizing chamber is providing, for a fraction of the ammonia bearing liquid, a residence time within the oxidizing chamber of at least 20 minutes.

8. The method of claim 5 further comprising:

the oxidizing chamber having;

an oxidizing gas input; and

a gas-liquid contactor inside the oxidizing chamber, the gas-liquid contractor positioned to be;

in gaseous communication with the oxidizing gas input; and

in fluidic communication with the oxidizing chamber conduit.

9. The method of claim 8 further comprising delivering through the oxidizing gas input no less than 20% more than the minimum stoichiometric amount required to oxidize the ammonia bearing liquid for which the gas-liquid contactor is configured to contact.

10. A method of cleaning gas, the method comprising:

spraying a first ammonia bearing liquid on a gas stream at a first location in the stream; and

spraying a second ammonia bearing liquid on the gas stream at a second location in the stream, wherein;

the first liquid has a first sulfur absorbing capacity;

the second liquid has a second sulfur absorbing capacity; and

the first sulfur absorbing capacity differs from the second sulfur absorbing capacity, and

prior to the sprayings, oxidizing the first and second liquids together in a common solution for different periods of time.

11. The method of claim 10 wherein:

the first liquid has a first oxidation rate;

the second liquid has a second oxidation rate; and

the first and second oxidation rates are different.

12. The method of claim 10 further comprising:

passing the gas from the second location through a liquid-vapor separator; and

spraying the gas with particle washing liquid.

13. The method of claim 10 further comprising passing the gas stream into a reactor at the beginning of a cleaning process and out of the reactor at an end of the cleaning process, the first and second locations being disposed in the reactor;

wherein, between the beginning of the cleaning process and the end of the cleaning process;

more than 98% of the gas stream sulfur is absorbed; and

more than 99% of ammonia added to the reactor is recovered.

14. The method of claim 10 further comprising:

spraying the gas stream with a pre-washing liquid prior to spraying the gas stream with the first liquid; and

,

after spraying the first liquid and the second liquid;

recirculating the first liquid and the second liquid along a first liquid circuit; and

recirculating the pre-washing liquid along a pre-washing circuit;

wherein the oxidation rate in the first liquid circuit and the oxidation rate in the pre-washing liquid circuit are different.

15. The method of claim 14 wherein:

the oxidation rate of the liquid of the first liquid circuit is greater than 96%; and

the oxidation rate of the liquid of the pre-washing circuit is greater than 99%.

16. A method of adjusting a gas cleaning process in a gas stream by:

selecting, from an array of ammonia feed points arranged along an ammonia fluid circuit, a feed point at which to inject ammonia; and

injecting the ammonia.

17. The method of claim 16 wherein the feed point is at a port of a circulation pump.

18. The method of claim 17 wherein the pump delivers fluid to a spray layer.

19. The method of claim 16 wherein the injecting comprises:

applying pressure to anhydrous ammonia with a liquid ammonia pump; and

dispersing the anhydrous ammonia into a solution flow.

20. The method of claim 19 wherein the dispersing comprises mixing the anhydrous ammonia into the solution with a mixer.