Dosing and mixing arrangement for use in exhaust aftertreatment

Patent metadata

Field	Value
Publication number	US-9707525-B2
Application number	US-201414180953-A
Country	US
Kind code	B2
Filing date	Feb 14, 2014
Priority date	Feb 15, 2013
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A method for causing exhaust gas flow to flow at least 270 degrees in a first direction about a perforated tube using a baffle plate having a main body with a plurality of flow-through openings and a plurality of louvers positioned adjacent to the flow-through openings. The method includes deflecting a first portion of the exhaust gas flow with the main body of the baffle plate. The method also includes allowing a second portion of the exhaust gas flow to flow through the flow-through openings of the baffle plate. The method also deflects the second portion of the exhaust gas flow at a downstream side of the main body with the louvers hereby causing the second portion of the exhaust gas flow to flow in the first direction about the perforated tube.

First claim

What is claimed is:

1. A method for causing exhaust gas flow to flow at least 270 degrees in a first direction about a perforated tube using a baffle plate having a main body that defines a plurality of flow-through openings, the baffle plate also including a plurality of louvers positioned adjacent to the flow-through openings, the main body of the baffle plate having an upstream side and a downstream side, the louvers being positioned at the downstream side of the main body of the baffle plate and the downstream side of the main body of the baffle plate facing toward the perforated tube, the method comprising:
deflecting a first portion of the exhaust gas flow with the upstream side of the main body of the baffle plate thereby causing the first portion of the exhaust gas flow to flow through an open flow area defined at least partially by the baffle plate and around the perforated tube in the first direction;
allowing a second portion of the exhaust gas flow to flow through the flow-through openings of the baffle plate from the upstream side of the main body to the downstream side of the main body; and
deflecting the second portion of the exhaust gas flow at the downstream side of the main body with the louvers thereby causing the second portion of the exhaust gas flow to flow in the first direction about the perforated tube.

2. The method of claim 1 , wherein the upstream side of the main body has a convex curvature and the downstream side of the main body has a concave curvature.

3. The method of claim 2 , wherein the convex and concave curvatures curve partially around the perforated tube.

4. The method of claim 1 , further comprising injecting a reactant within an interior of the perforated tube such that the reactant is mixed with the exhaust gas flow within the interior of the perforated tube.

5. The method of claim 4 , further comprising reacting the reactant at a NOx treatment substrate positioned downstream from the perforated tube.

6. The method of claim 5 , wherein the NOx treatment substrate is selected from the group consisting of a lean NOx catalyst substrate, a SCR substrate, a SCRF substrate, and a NOx trap substrate.

7. The method of claim 6 , wherein the NOx treatment substrate is an SCR substrate and the reactant is selected from the group consisting of ammonia and urea.

8. The method of claim 1 , wherein the first portion of the exhaust gas flow is larger than the second portion of exhaust gas flow.

9. The method of claim 1 , wherein the first portion of the exhaust gas flow flows around an end of the main body of the baffle plate when the first portion flows through the open flow area.

10. A dosing and mixing arrangement comprising:
a housing including a main housing body that defines a central housing axis, the main housing body having a length that extends along the central housing axis between first and second opposite ends of the main housing body, the housing also including an inlet adjacent the first end of the main housing body and an outlet adjacent the second end of the main housing body;
a perforated tube forming the outlet of the housing, the perforated tube defining a tube axis aligned at an angle relative to the central housing axis;
an exhaust treatment substrate disposed in the housing;
the main housing body defining an interior volume that extends between the exhaust treatment substrate and the perforated tube, the interior volume defining a transverse cross-sectional area that is transverse relative to the central housing axis;
a baffle plate positioned within the interior volume between the perforated tube and the inlet, the baffle plate having a main plate body having an upstream side that faces toward the inlet and a downstream side that faces toward the perforated tube, the main plate body defining a plurality of flow-through openings that extend through the main plate body between the upstream and downstream sides of the main plate body, the baffle plate also including a plurality of louvers positioned adjacent to the flow-through openings at the downstream side of the main plate body, the main plate body having a connected edge that is connected to an interior of the main housing body and a free edge that extends across the interior volume of the main housing body, the main plate body being sized and shaped to coincide with only a portion of the transverse cross-sectional area of the interior volume such that an open flow area is defined between the free edge and the interior of the main housing body; and
wherein a first portion of exhaust gas flow through the housing is directed though the open flow area and then in a first rotational direction around the perforated tube, and wherein a second portion of the exhaust gas flow passes through the flow-through openings and is deflected in the first rotation direction about the perforated tube by the louvers.

11. The dosing and mixing arrangement of claim 10 , wherein the main plate body has a first cross-dimension measured in a first orientation that is perpendicular with respect to the central housing axis and that is within a plane that includes the central housing axis and is perpendicular to the tube axis, wherein the transverse cross-sectional area of the interior volume of the main housing body has a second cross-dimension measured along the first orientation, and wherein the first cross-dimension is no more than 80 percent of the second cross-dimension.

12. The dosing and mixing arrangement of claim 10 , further comprising an exhaust treatment substrate positioned within the main housing body, the baffle plate being positioned between the perforated tube and the exhaust treatment substrate.

13. The dosing and mixing arrangement of claim 10 , wherein the open flow area is larger than a total area defined by the flow-through openings.

14. The dosing and mixing arrangement of claim 10 , wherein at least 10% of the perforated tube overlaps with the open flow area.

15. The dosing and mixing arrangement of claim 10 , wherein the free edge is parallel to the tube axis.

16. The dosing and mixing arrangement of claim 10 , wherein the second end of the main housing body includes a curved portion that curves partially around the perforated tube.

17. The dosing and mixing arrangement of claim 10 , further comprising a reactant dispenser for dispensing a reactant within an interior of the perforated tube such that the reactant is mixed with the exhaust gas flow within the interior of the perforated tube.

18. The dosing and mixing arrangement of claim 10 , wherein the baffle plate is configured to cause the exhaust gas flow to flow circumferentially in one direction around at least 270 degrees of an exterior of the perforated tube.

19. A dosing and mixing arrangement comprising:
a mixing tube having an interior, an exterior, and at least a first portion defining a first plurality of apertures, the first portion surrounding a tube axis of the mixing tube;
a swirl structure including at least one plate curving partially around the tube axis of the mixing tube, the plate defining a plurality of baffles and a second plurality of apertures positioned adjacent to the baffles, the plate causing exhaust flow to move both around the plate and also through the second plurality of apertures and to swirl outside the exterior of the first portion of the mixing tube in one rotational direction along a flow path that extends at least 270 degrees around a central axis of mixing tube and into the interior of the mixing tube through the first plurality of apertures; and
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Assignees

• Donaldson Co Inc

Inventors

• De Rudder Korneel
• Le Merdy Stéphane

Classifications

• F01N2240/20

  a flow director or deflector · CPC title

• F01N2470/04

  characterised by shape, disposition or dimensions of apertures · CPC title

• F01N3/0842

  Nitrogen oxides · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title

• F01N3/035

  with catalytic reactors · CPC title