DOSING AND MIXING ARRANGEMENT FOR USE IN EXHAUST AFTERTREATMENT

• US 20150218996A1
• Filed: 01/30/2015
• Published: 08/06/2015
• Est. Priority Date: 01/31/2014
• Status: Active Grant

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Hoppenstedt, Bruce, Whitten, Matthew S., Brandl, Mark Thomas, Schiller, Stephen Ronald
• Granted Patent: US 9,528,415 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B01F 2025/931 Flow guiding elements surrounding feed openings, e.g. jet nozzles
• CPC Class Codes: B01F 23/2132 using nozzles
• CPC Class Codes: B01F 25/10 Mixing by creating a vortex flow, e.g. by tangential introduction of flow components
• CPC Class Codes: B01F 25/25 Mixing by jets impinging against collision plates
• CPC Class Codes: B01F 25/3141 with additional mixing means other than injector mixers
• CPC Class Codes: B01F 25/43211 using a simple by-pass for separating and recombining the flow, e.g. by using branches of different length
• CPC Class Codes: F01N 2240/20 a flow director or deflector
• CPC Class Codes: F01N 2410/00 By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
• CPC Class Codes: F01N 2470/24 Concentric tubes or tubes being concentric to housing, e.g. telescopically assembled
• CPC Class Codes: F01N 2610/01 the substance being catalytic material in liquid form
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/1453 Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
• CPC Class Codes: F01N 3/206 Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents F01N3/2066 takes precedence
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 3/2892 Exhaust flow directors or the like, e.g. upstream of catalytic device

Abstract

A dosing and mixing arrangement including an exhaust conduit defining a central axis; a mixing conduit positioned within the exhaust conduit; a dispersing arrangement (e.g., a mesh) disposed at the upstream end of the mixing conduit; an injector coupled to the exhaust conduit and configured to direct reactants into the exhaust conduit towards the mesh; and an annular bypass defined between the mixing conduit and the exhaust conduit for allowing exhaust to bypass the upstream end of the mixing conduit and to enter the mixing conduit downstream of the mesh.

Claims

1. A dosing and mixing arrangement comprising:

an exhaust conduit through which exhaust can flow;

an injector mount coupled to the exhaust conduit and configured to receive an injector to direct reactants into the exhaust conduit to be carried by the exhaust;

a dispersing arrangement disposed within the exhaust conduit downstream of the injector mount, the dispersing arrangement extending across an entire width of the exhaust conduit, the dispersing arrangement having an upstream face and a downstream face, the dispersing arrangement including a first region that is configured to break up droplets of the reactants as a first portion of the exhaust flows through the first region, the dispersing arrangement also having a second region, the second region being less restrictive than the first region; and

a bypass passage for allowing a second portion of the exhaust to bypass the first portion of the dispersing arrangement and to continue flowing through the exhaust conduit downstream of the first portion of the dispersing arrangement, wherein the second region of the dispersing arrangement at least partially covers and restricts access to the bypass passage.

2. The dosing and mixing arrangement of claim 1, wherein the dispersing arrangement includes a mesh.

3. The dosing and mixing arrangement of claim 1, further comprising a mixing apparatus that imparts a rotation to the first and second portions of the exhaust flowing downstream of the dispersing arrangement.

4. The dosing and mixing arrangement of claim 3, wherein the mixing apparatus includes a mixing conduit positioned within the exhaust conduit downstream of the dispersing arrangement, the mixing conduit defining an axial inlet at which the first portion of the exhaust is received and the mixing conduit defining at least one radial inlet at which the second portion of the exhaust is received.

5. A dosing and mixing arrangement comprising:

an exhaust conduit defining a central axis;

a mixing conduit positioned within the exhaust conduit, the mixing conduit extending along the central axis from an upstream end to a downstream end;

a dispersing arrangement for dispersing reactants disposed at the upstream end of the mixing conduit; and

a bypass for allowing exhaust to bypass the upstream end of the mixing conduit and to enter the mixing conduit downstream of the dispersing arrangement;

wherein an interior of the mixing conduit is devoid of structure in longitudinal alignment with an upstream face of the dispersing arrangement.

6. The dosing and mixing arrangement of claim 5, wherein the dispersing arrangement includes a mesh.

7. The dosing and mixing arrangement of claim 6, wherein the mesh includes metal wires having transverse cross-dimensions of no more than 0.01 inches.

8. The dosing and mixing arrangement of claim 5, wherein the bypass is defined between the mixing conduit and the exhaust conduit.

9. The dosing and mixing arrangement of claim 5, wherein the bypass includes an annular passage.

10. The dosing and mixing arrangement of claim 5, wherein the mixing conduit includes a structure to impart turbulence to exhaust flowing into the mixing conduit from the annular bypass.

11. The dosing and mixing arrangement of claim 5, wherein the mixing conduit defines a plurality of apertures therethrough at a location downstream of the dispersing arrangement, the apertures being configured to allow exhaust bypassing the upstream end of the mixing conduit.

12. The dosing and mixing arrangement of claim 11, wherein the plurality of apertures includes a first set of apertures at a first axial location along the mixing conduit.

13. The dosing and mixing arrangement of claim 12, wherein the first set of apertures direct at least some exhaust from the bypass into the mixing conduit to carry droplets of the reactants away from an inner surface of the mixing conduit at one side of the mixing conduit.

14. The dosing and mixing arrangement of claim 12, wherein the plurality of apertures includes a second set of apertures at a second axial location downstream of the first axial location.

15. The dosing and mixing arrangement of claim 14, wherein the first set of apertures extends around less than a circumference of the mixing conduit, and wherein the second set of apertures extends around the circumference of the mixing conduit second set of apertures.

16. The dosing and mixing arrangement of claim 14, wherein a first plurality of louvers are disposed at the first set of apertures and a second plurality of louvers are disposed at the second set of apertures, the second plurality of louvers having a different circumferential component than the first plurality of louvers.

17. The dosing and mixing arrangement of claim 5, wherein the dispersing arrangement includes a first region and a second region that is less restrictive than the first region, the first region extending across the upstream end of the mixing conduit and the second region at least partially restricting access to the bypass.

18. The dosing and mixing arrangement of claim 17, wherein the second region extends at least partially across an annular opening that extends between a circumference of the first region and an inner surface of the exhaust conduit.

19. The dosing and mixing arrangement of claim 18, wherein the second region at least partially restricts access to the entire bypass.

20. The dosing and mixing arrangement of claim 17, wherein the first region includes a first mesh and the second region includes a second mesh, the second mesh being less restrictive to flow than the first mesh, the second mesh extending at least partially across an annular opening that extends between a circumference of the first region and an inner surface of the exhaust conduit.

21. The dosing and mixing arrangement of claim 20, wherein the second mesh extends across the first region and fully across the annular opening.

22. A dosing and mixing arrangement comprising:

an exhaust conduit defining a central axis;

a mixing conduit positioned within the exhaust conduit, the mixing conduit extending from an upstream end to a downstream end, the mixing conduit including a reduced diameter section towards the upstream end and an expanding diameter section towards the downstream end, the reduced diameter section having a sidewall spaced radially inwardly from the exhaust conduit, the expanding diameter section defining a plurality of apertures forming an exhaust entry region for allowing exhaust to enter the mixing conduit;

a dispersing arrangement for dispersing reactants at the upstream end of the mixing conduit; and

wherein an upstream face of the dispersing arrangement defines a first circumference and wherein no portion of the mixing conduit extends inwardly beyond the first circumference.

23. The dosing and mixing arrangement of claim 22, wherein louvers are provided at the apertures.

24. The dosing and mixing arrangement of claim 22, wherein the reduced diameter section defines a plurality of apertures forming another exhaust entry region, wherein the exhaust entry regions are axially spaced from one another.