Dosing and mixing arrangement for use in exhaust aftertreatment

Patent metadata

Field	Value
Publication number	US-9670811-B2
Application number	US-201113166582-A
Country	US
Kind code	B2
Filing date	Jun 22, 2011
Priority date	Jun 22, 2010
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A dosing and mixing arrangement is disclosed herein. The arrangement includes a mixing tube having a constant diameter along its length. At least a first portion of the mixing tube includes a plurality of apertures. The arrangement also includes a swirl structure for causing exhaust flow to swirl outside of the first portion of the mixing tube in one direction along a flow path that extends at least 270 degrees around a central axis of the mixing tube. The arrangement is configured such that the exhaust enters an interior of the mixing tube through the apertures as the exhaust swirls along the flow path. The exhaust entering the interior of the mixing tube through the apertures has a tangential component that causes the exhaust to swirl around the central axis within the interior of the mixing tube. The arrangement also includes a doser for dispensing a reactant into the interior of the mixing tube.

First claim

What is claimed is:

1. A dosing and mixing unit comprising:
a swirl housing having a curved side wall that defines a curved flow-deflection surface within the swirl housing, the dosing and mixing unit also including an inlet pipe that projects outwardly from the swirl housing and an outlet pipe that projects outwardly from the swirl housing, the inlet pipe having a free end adapted for connection to a pipe, wherein the swirl housing defines an open space that extends from the inlet pipe to the curved side wall such that flow from the inlet pipe impinges directly against the curved side wall;
a mixing tube having a constant diameter along its length, the mixing tube including a plurality of apertures;
the curved side wall of the swirl housing curving circumferentially along and opposing an outer surface of the mixing tube, the inlet pipe being oriented to direct exhaust flow toward the curved side wall such that the inlet pipe and the curved side wall cooperate to define a swirl structure for causing exhaust flow to swirl outside of the mixing tube in one rotational direction along a flow path that extends at least 270 degrees around a central axis of the mixing tube, wherein the exhaust enters an interior of the mixing tube through the apertures as the exhaust swirls along the flow path, and wherein the exhaust entering the interior of the mixing tube through the apertures swirls around the central axis within the interior of the mixing tube;
a source of aqueous urea; and
a doser coupled to the source of aqueous urea and disposed adjacent an end of the mixing tube, the doser being configured to dispense aqueous urea from the source of aqueous urea into the interior of the mixing tube for mixing with the swirling exhaust within the interior of the mixing tube.

2. The dosing and mixing unit of claim 1 , further comprising an SCR substrate positioned downstream from the mixing tube.

3. The dosing and mixing unit of claim 1 , wherein the swirl structure has a cross-section that gradually decreases along the flow path.

4. The dosing and mixing unit of claim 1 , wherein the curved side wall of the swirl housing is arranged to transition progressively closer to the outer surface of the mixing tube as the surface extends in a circumferential direction of exhaust flow.

5. The dosing and mixing unit of claim 1 , wherein the apertures are circular.

6. The dosing and mixing unit of claim 1 , wherein the apertures are arranged in rows that extend along a length of the mixing tube.

7. The dosing and mixing unit of claim 1 , further comprising a stop wall that forces the exhaust flow to enter the mixing tube so that the flow path extends approximately 360° around mixing tube.

8. The dosing and mixing unit of claim 1 , wherein the mixing tube includes a first portion that includes the apertures and also includes a second portion that does not have any apertures.

9. The dosing and mixing unit of claim 8 , wherein the mixing tube has a first end positioned adjacent the first portion and a second end positioned adjacent the second portion, and wherein the second portion forms the outlet pipe of the dosing and mixing unit.

10. The dosing and mixing unit of claim 9 , wherein the first end of the mixing tube is closed to exhaust flow and wherein the doser is mounted at the first end of the mixing tube.

11. The dosing and mixing unit of claim 1 , wherein the swirl structure further includes a baffle within the swirl housing.

12. The dosing and mixing unit of claim 11 , wherein the baffle extends across a majority of a diameter of the mixing tube.

13. The dosing and mixing unit of claim 1 , wherein the swirl housing contains an aftertreatment substrate positioned upstream from the mixing tube, and wherein the swirl structure further includes a baffle positioned between the aftertreatment substrate and the mixing tube, and wherein the dosing and mixing unit is incorporated into an exhaust treatment system, the exhaust treatment system including an SCR substrate positioned downstream from the dosing and mixing unit and connected to the dosing and mixing unit by a piped connection.

14. The dosing and mixing unit of claim 13 , wherein the aftertreatment substrate is selected from the group consisting of a diesel particulate filter and a catalytic converter.

15. The dosing and mixing unit of claim 1 , wherein the swirl housing includes opposite first and second end walls, wherein the curved side wall extends between the opposite end walls, wherein the inlet pipe projects outwardly from the curved side wall of the swirl housing, wherein the outlet pipe projects outwardly from the first end wall of the swirl housing, and wherein the doser is mounted at the second end wall of the swirl housing.

16. The dosing and mixing unit of claim 15 , wherein the inlet pipe is attached to the curved side wall of the swirl housing and extends outwardly from the curved side wall of the swirl housing in an angled tangential direction in relation to a central axis of the mixing tube.

17. The dosing and mixing unit of claim 16 , wherein the inlet pipe is oriented to have an axial component and a transverse component relative to the central axis of the mixing tube.

18. The dosing and mixing unit of claim 15 , wherein the outlet pipe is co-axial with the mixing tube.

19. The dosing and mixing unit of claim 18 , wherein the outlet pipe is formed by an outer portion of the mixing tube that extends outwardly beyond the first end wall.

20. The dosing and mixing unit of claim 1 , wherein the side wall extends between opposite ends of the swirl housing, wherein the swirl structure includes a plurality of flow baffles spaced about a circumference of the mixing tube, wherein the flow baffles are arranged between the outer surface of the mixing tube and an interior of the side wall, and wherein the flow baffles are separate and spaced from the mixing tube.

21. The dosing and mixing unit of claim 20 , wherein the apertures of the mixing tube are circular.

22. The dosing and mixing unit of claim 20 , wherein the apertures are smaller than the flow baffles.

23. The dosing and mixing unit of claim 20 , wherein the flow baffles extend from at least one of the ends of the swirl housing.

Assignees

• De Rudder Korneel
• Chauvin Corine
• Donaldson Co Inc

Inventors

• De Rudder Korneel
• Chauvin Corine

Classifications

• F01N2470/18

  the axis of inlet or outlet tubes being other than the longitudinal axis of apparatus · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title

• F01N2610/1453

  Sprayers or atomisers; Arrangement thereof in the exhaust apparatus · CPC title

• F01N3/36

  Arrangements for supply of additional fuel · CPC title

• F01N2470/02

  Tubes being perforated · CPC title