Method for removing contaminants from exhaust gases

• US 20150044116A1
• Filed: 10/21/2014
• Published: 02/12/2015
• Est. Priority Date: 10/15/2012
• Status: Active Grant

• Current Assignee: Messer Industries USA, Inc. (Messer Industries GmbH)
• Original Assignee: Linde AG (Linde Plc)
• Inventors: Suchak, Naresh J.
• Granted Patent: US 9,440,188 B2
• Time in Patent Office: Days
• US Class Current: 423/235
• CPC Class Codes: B01D 2251/104 Ozone
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/50 Sulfur oxides B01D53/60 takes precedence
• CPC Class Codes: B01D 53/56 Nitrogen oxides B01D53/60 takes precedence
• CPC Class Codes: B01D 53/60 Simultaneously removing sulfur oxides and nitrogen oxides
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/75 Multi-step processes
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: B01D 53/83 with moving reactants
• CPC Class Codes: F01N 2240/38 an ozone (O3) generator, e.g. for adding ozone after generation of ozone from air
• CPC Class Codes: F01N 3/04 using liquids
• CPC Class Codes: F23J 15/02 of purifiers, e.g. for removing noxious material traps for solid residues F23J3/04
• CPC Class Codes: F23J 15/04 using washing fluids scrubbers for removing solids only F23J15/022
• CPC Class Codes: F23J 2219/20 Non-catalytic reduction devices
• CPC Class Codes: F23J 2219/40 Sorption with wet devices, e.g. scrubbers
• CPC Class Codes: F23J 2219/50 Sorption with semi-dry devices, e.g. with slurries
• CPC Class Codes: F23J 2219/60 Sorption with dry devices, e.g. beds
• CPC Class Codes: F23J 2900/15003 : Supplying fumes with ozone
• CPC Class Codes: Y02A 50/20 : Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02E 20/32 : Direct CO2 mitigation
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies

Abstract

In a method for removing a portion of contaminants, such as nitrogen oxides, from an exhaust gas stream of a combustion process, the exhaust gas stream is conveyed through a gas distributor at an inlet of a wet horizontal spray scrubber. A distributor separates the gas stream into a plurality of spaced apart partitioned gas streams. The gas stream is partitioned in the chamber of the scrubber without the need for any physical partitions or obstructions positioned in the chamber. A preselected number of the partitioned gas streams are mixed with ozone to oxidize the contaminants in the gas streams. The oxidized gas streams are then sprayed with an aqueous medium to capture the oxidized contaminants and remove them from the treated gas streams. The treated gas streams are then recombined with the untreated gas streams. Excess ozone present in the treated gas streams is consumed by oxidation of contaminants in the untreated gas streams before the combined gas stream is released to the atmosphere. The partitioned gas streams selected for mixing with ozone directly correlates to the amount of nitrogen oxides that are desired to be removed from the exhaust gas stream.

Claims

1. A method for the partial removal of contaminants from process gas stream comprising the steps of:

conveying a process gas stream to an inlet of a scrubber,

distributing the process gas stream evenly across the scrubber inlet,

forming at the scrubber inlet a flow pattern of a plurality of process gas streams partitioned from one another,

feeding ozone into contact with selected ones of the partitioned gas streams in the scrubber to oxidize contaminants in the partitioned gas streams,

removing the oxidized contaminants from the selected partitioned gas stream, and

recombining the selected partitioned gas streams substantially free of contaminants with the remaining partitioned gas streams containing contaminants.

2. A method as set forth in claim 1 which includes

conveying a stream of untreated process gas through the scrubber inlet into a horizontally positioned scrubbing zone of the scrubber, and

dividing the gas stream at the scrubber inlet free of any physical obstruction in the scrubber extending the length of the scrubber from the inlet to the outlet into a plurality of gas streams separated from one another.

3. A method as set forth in claim 1 which includes,

conveying the process gas stream the inlet of a horizontal wet spray scrubber.

4. A method as set forth in claim 1 which includes,

distributing the process gas stream entering the scrubber inlet evenly throughout the width of the scrubber inlet.

5. A method as set forth in claim 1 which includes,

partitioning the process gas stream entering the scrubber at the inlet into a plurality of separated rows of process gas streams extending from the inlet to the outlet of the scrubber.

7. A method as set forth in claim 1 which includes,

treating a preselected percentage of the process gas stream entering the scrubber by feeding ozone into contact with selected ones of the partitioned gas streams to oxidize contaminants in the partitioned gas streams.

9. A method as set forth in claim 1 which includes,

positioning nozzles for supplying ozone to the scrubber oppositely of the selected partitioned gas streams for oxidation of a preselected percentage of the contaminants in the process gas stream.

10. A method set forth in claim 7 which includes,

spraying the treated process gas stream with an aqueous medium emitted from rows of scrubbing nozzles aligned with selected rows of partitioned gas streams containing oxidized contaminants.

11. A method as set forth in claim 1 which includes,

capturing the oxidized contaminants removed from the selected partitioned gas streams in a capture device selected from the group consisting of a fabric filter, wet and dry electrostatic precipitators, a wet scrubber, a dry scrubber, a bag house, condensing surfaces, and a mist separator.

6. A method as set forth in claim which includes,

positioning rows of scrubbing nozzles in spaced relation extending from the scrubber inlet to the scrubber outlet across the width of the scrubber, and

partitioning the process gas stream into a flow pattern forming a plurality of spaced apart rows of gas streams aligned with the rows of scrubbing nozzles.

8. A method as set forth in claim 6 which includes,

positioning the rows of scrubbing nozzles in parallel spaced relation across the width of the scrubber and extending the length of the scrubber from the inlet to the outlet, and

partitioning the flow of process gas through the scrubber in a flow pattern of partitioned gas streams aligned with the parallel rows of scrubbing nozzles.

12. A method for the partial removal of contaminants from a process gas stream comprising the steps of:

conditioning the process gas stream emitted from a combustion process,

separating the process gas stream into a plurality of spaced apart partitioned gas streams containing contaminants,

injecting ozone into one or more of the partitioned gas streams to mix ozone with the contaminants in a preselected percentage of the entire process gas stream,

oxidizing the contaminants in the selected partitioned gas stream by mixing with ozone,

capturing the oxidized contaminants in a separation device to remove the contaminants from the selected partitioned gas stream, and

reuniting the selected partitioned gas stream substantially free of contaminants with the remaining partitioned gas streams containing contaminants.

13. A method as set forth in claim 12 which includes,

conveying the conditioned process gas stream to an inlet of a scrubber,

distributing the process gas stream at the inlet into a flow pattern forming the plurality of partitioned gas streams, and

feeding ozone into contact with selected ones of the partitioned gas streams to oxidize the contaminants therein.

14. A method as set forth in claim 12 which includes,

dividing the conditioned process gas stream at the scrubber inlet free of any physical obstruction in the scrubber extending the length of the scrubber from the inlet to an outlet into the partitioned gas streams.

15. A method as set forth in claim 12 which includes,

distributing the process gas stream entering an inlet of a scrubber evenly throughout the width of the scrubber into the plurality of partitioned gas streams containing contaminants, and

maintaining a flow pattern of partitioned gas streams from the inlet through a chamber of the scrubber to an outlet thereof.

16. A method as set forth in claim 12 which includes,

mixing a preselected percentage of the partitioned gas stream with ozone corresponding to the selected percentage of NO_x to be removed from the gas stream.

17. A method as set forth in claim 12 which includes,

removing the oxidized contaminants from the partitioned gas stream by contacting the oxidized contaminants with an aqueous scrubbing medium.

18. Apparatus for the partial removal of contaminants from a process gas stream comprising:

a scrubber having an inlet and an outlet with a chamber positioned there between,

said chamber being free of any obstructions diverting the flow of the process gas stream from said inlet through said chamber to said outlet,

a gas distributor positioned at said inlet section for receiving and evenly distributing the process gas stream across said inlet entering said chamber into a flow pattern of separated gas streams extending from said inlet to said outlet,

a source of ozone positioned at said inlet for injecting ozone into selected ones of said separated gas streams to oxidize a preselected percentage of the gas stream flowing through said chamber,

a capture device positioned in said chamber for receiving the oxidized gas streams before exiting through said outlet to remove the oxidized contaminants from the gas streams, and

said outlet receiving the gas stream free of contaminants for mixing with the gas stream containing contaminants.

19. Apparatus for the partial removal of contaminants from a process gas stream as set forth in claim 18 in which,

said separated gas streams are divided by said gas distributor into a plurality of partitioned gas streams spaced apart in substantially parallel relation extending from said inlet through said chamber to said outlet.

20. Apparatus for the partial removal of contaminants from a process gas stream as set forth in claim 19 which includes,

a preselected number of nozzles positioned downstream of said gas distributor in said chamber and positioned oppositely of selected ones of said separated gas streams for injecting ozone into said selected gas streams to oxidize a preselected percentage of the contaminants present in the process gas stream entering said scrubber.