CN109404103B

CN109404103B - Mixing device

Info

Publication number: CN109404103B
Application number: CN201810775603.7A
Authority: CN
Inventors: 王聪; 童毅君; 陈智; 毛伟; 王林
Original assignee: Tenneco Suzhou Emission System Co Ltd
Current assignee: Tenneco Suzhou Emission System Co Ltd
Priority date: 2016-06-03
Filing date: 2016-06-03
Publication date: 2021-02-19
Anticipated expiration: 2036-06-03
Also published as: WO2017206945A1; CN107461250A; CN109404103A

Abstract

A mixing device is used in an engine exhaust aftertreatment system and comprises a mixing pipe and a connecting pipe communicated with the mixing pipe. The mixing tube comprises a hollow inner cavity, a plurality of fins surrounding the periphery of the inner cavity and distributed along the circumferential direction, and a plurality of grooves corresponding to the fins. The mixing tube assembly further comprises a flow guide tube positioned in the connecting tube, the flow guide tube is fixed on the inner wall of the connecting tube, a gap is reserved between the outer surface of the flow guide tube and the inner wall of the connecting tube, and a plurality of through holes penetrating through the outer surface of the flow guide tube are formed. So set up, reduced the urea volume that directly carries out the contact with the pipe wall of connecting pipe, reduced the risk of urea crystallization.

Description

Mixing device

The present application is a divisional application filed on 2016, 3/6, and under the name of 201610388059.1, entitled "engine exhaust gas aftertreatment system".

Technical Field

The invention relates to a mixing device, and belongs to the technical field of engine exhaust aftertreatment.

Background

Engine exhaust aftertreatment systems (e.g., diesel exhaust aftertreatment systems) are primarily devices used to treat or evolve toxic and harmful substances in the exhaust. The toxic substances in the exhaust gas mainly comprise hydrocarbons, carbon monoxide, nitrogen oxides, particulate matters and the like.

The prior art has adopted a combination of a Diesel Oxidation Catalyst (DOC), a diesel particulate trap (DPF), and a Selective Catalytic Reduction (SCR) to improve the efficiency of exhaust treatment. In one scheme, the oxidation type catalytic converter and the particle catcher are arranged in series in a first shell, and a first cavity communicated with the first shell is additionally arranged; the selective catalytic reducing agent is arranged in the second shell, and a second cavity communicated with the second shell is additionally arranged; the first and second chambers are then connected in series by means of a mixing tube. The exhaust gas and urea droplets are mixed in the mixing pipe, and the mixture then enters the second chamber and passes through the selective catalytic reduction agent to reduce the harmful substances. However, urea droplets injected from the urea nozzle tend to directly contact the wall of the mixing tube, thereby causing crystallization.

Disclosure of Invention

The invention aims to provide a mixing device capable of reducing the risk of urea crystallization.

In order to achieve the purpose, the invention adopts the following technical scheme: the utility model provides a mixing arrangement for among the engine exhaust aftertreatment system, mixing arrangement include the hybrid tube and with the connecting pipe that the hybrid tube is linked together, the hybrid tube includes hollow interior cavity, centers on a plurality of fins that the periphery of interior cavity just distributed along circumference and corresponding to a plurality of fluting of a plurality of fins, the hybrid tube subassembly is still including being located honeycomb duct in the connecting pipe, the honeycomb duct is fixed just on the inner wall of connecting pipe the surface of honeycomb duct with the clearance has between the inner wall of connecting pipe, a plurality of through-holes that run through have on the surface of honeycomb duct.

As a further improvement of the present invention, the draft tube includes a first end proximate to the mixing tube and a second end opposite the first end, wherein the second end is open.

The honeycomb duct is cylindrical, the first end is provided with a plurality of claws expanding outwards, the claws are welded and fixed on the inner wall of the connecting pipe, and a groove for exhaust to pass through is formed between every two adjacent claws.

As a further improved technical scheme of the invention, the flow guide pipe is in a round table shape, the diameter of the first end is larger than that of the second end, and the first end is welded and fixed on the inner wall of the connecting pipe.

As a further improved technical scheme of the invention, the mixing pipe and the connecting pipe are welded and fixed together.

As a further improved technical scheme of the invention, the mixing pipe assembly further comprises an outer pipe sleeved on the periphery of the connecting pipe.

Compared with the prior art, the urea crystallization device has the advantages that the amount of urea directly contacting with the pipe wall of the connecting pipe is reduced by arranging the flow guide pipe, and the risk of urea crystallization is reduced.

Drawings

FIG. 1 is a schematic perspective view of an engine exhaust aftertreatment system of the present invention.

Fig. 2 is a perspective view of fig. 1 from another angle.

Fig. 3 is a left side view of fig. 1.

Fig. 4 is a partially exploded perspective view of fig. 1.

Fig. 5 is a partial exploded perspective view of fig. 4 at another angle.

Fig. 6 is an exploded perspective view of the mixing tube assembly of fig. 1 in a first embodiment.

Fig. 7 is a perspective view of the draft tube of fig. 6.

Fig. 8 is an exploded perspective view of the mixing tube assembly of fig. 1 in a second embodiment.

Fig. 9 is a schematic sectional view of the engine exhaust aftertreatment system of the first embodiment taken along line a-a in fig. 3.

FIG. 10 is a schematic cross-sectional view of the engine exhaust aftertreatment system of the first embodiment taken along line B-B of FIG. 3.

FIG. 11 is a schematic cross-sectional view of the engine exhaust aftertreatment system of the second embodiment taken along line A-A of FIG. 3.

FIG. 12 is a schematic cross-sectional view of the engine exhaust aftertreatment system of the second embodiment taken along line B-B of FIG. 3.

Detailed Description

Referring to fig. 1 to 12, the present invention discloses an engine exhaust aftertreatment system 100, which includes a first aftertreatment component 1, a first mixing chamber component 2 communicated with the first aftertreatment component 1, a second aftertreatment component 3 arranged side by side with the first aftertreatment component 1, a second mixing chamber component 4 communicated with the second aftertreatment component 3, and a mixing pipe assembly 5 communicated with the first and second

mixing chamber components

2, 4. The first post-processing assembly 1 and the second post-processing assembly 3 are connected in series by the first and second

mixing chamber assemblies

2 and 4 and the mixing tube assembly 5.

In the illustrated embodiment of the invention, the first aftertreatment assembly 1 includes a first housing 11, a oxidation catalytic converter (DOC)12 mounted within the first housing 11, a particulate trap (DPF)13 mounted within the first housing 11, and an exhaust gas inlet 14 upstream of the oxidation catalytic converter 12. Wherein the oxidation catalyst 12 is located upstream of the particulate trap 13 to provide a suitable temperature when the particulate trap 13 is regenerated.

In the illustrated embodiment of the invention, the second aftertreatment component 3 includes a second housing 31, a Selective Catalytic Reduction (SCR)32 mounted within the second housing 31, and an exhaust gas outlet 33 located downstream of the SCR 32.

In the illustrated embodiment of the invention, the first mixing chamber element 2 is substantially identical in shape to the second mixing chamber element 4. The first mixing chamber assembly 2 is configured to direct exhaust from the first aftertreatment assembly 1 to the mixing tube assembly 5. The first mixing chamber assembly 2 is provided with a urea nozzle mounting part 21 at a position facing the mixing pipe assembly 5 for mounting a urea nozzle (not shown).

Referring to fig. 6, in the first embodiment of the present invention, the mixing tube assembly 5 includes a mixing tube 51 at least partially disposed in the first mixing chamber assembly 2, a connecting tube 52 communicated with the mixing tube 51, and a guide tube 53 disposed in the connecting tube 52. Wherein the mixing tube 51 includes a hollow inner cavity 511, a plurality of fins 512 surrounding the periphery of the inner cavity 511 and distributed along the circumferential direction, a plurality of slots 513 corresponding to the plurality of fins 512 and communicating with the inner cavity 511, and a plurality of openings 514 located at one side of the fins 512 and close to the urea nozzle mounting part 21. The draft tube 53 is fixed on the inner wall of the connecting tube 52, a gap is formed between the outer surface 531 of the draft tube 53 and the inner wall of the connecting tube 52, and a plurality of through holes 532 are formed on the outer surface 531 of the draft tube 53. In the illustrated embodiment of the present invention, the through hole 532 has a circular shape.

The draft tube 53 includes a first end 533 proximate to the mixing tube 51 and a second end 534 opposite the first end 533, wherein the second end 534 is open.

Referring to fig. 6, 7, 9 and 10, the duct 53 is cylindrical, the first end 533 has a plurality of outwardly extending claws 535, the claws 535 are welded and fixed to the inner wall of the connecting pipe 52, and a slot 536 is formed between two adjacent claws 535 for exhaust to pass through.

Referring to fig. 8, 11 and 12, the fluid guide tube 53 is in a circular truncated cone shape, the diameter of the first end 533 is larger than that of the second end 534, and the first end 533 is welded and fixed on the inner wall of the connecting tube 52.

In the illustrated embodiment of the present invention, the mixing pipe 51 and the connecting pipe 52 are welded and fixed together. The mixing tube assembly 5 further includes an outer tube 54 sleeved around the connecting tube 52. Preferably, a heat insulating material such as heat insulating cotton may be disposed between the connection pipe 52 and the outer pipe 54, so as to achieve heat preservation and reduce the risk of urea crystallization.

When the engine exhaust aftertreatment system 100 of the invention is used, at least part of the urea solution sprayed out is in direct contact with the flow guide pipe 53 because the flow guide pipe 53 is at least partially positioned in the spraying area of the urea nozzle (see the upper and lower included angle areas shown in fig. 9 or fig. 11), so that urea liquid drops are crushed, and the risk of urea crystallization is reduced. If there are urea droplets remaining on the wall of the draft tube 53 or a small amount of urea crystals precipitated, they can be blown off outward by the swirling flow of the exhaust gas passing through the through holes 532. Further, since a gap is provided between the outer surface 531 of the draft tube 53 and the inner wall of the connection tube 52, the exhaust gas can blow off the urea crystals through the gap.

In addition, the above embodiments are only used for illustrating the invention and not for limiting the technical solutions described in the invention, and the understanding of the present specification should be based on the technical personnel in the field, and although the present specification has described the invention in detail by referring to the above embodiments, the ordinary skilled in the art should understand that the technical personnel in the field can still make modifications or equivalent substitutions to the present invention, and all the technical solutions and modifications thereof without departing from the spirit and scope of the present invention should be covered in the claims of the present invention.

Claims

1. The utility model provides a mixing arrangement for among the engine exhaust aftertreatment system, mixing arrangement include the hybrid tube and with the connecting pipe that the hybrid tube is linked together, mixing arrangement is used for cooperateing with the urea nozzle, the hybrid tube includes hollow interior cavity, centers on the periphery of interior cavity and along a plurality of fins that circumference distributes and corresponding to a plurality of flutings of a plurality of fins, its characterized in that: the mixing pipe assembly further comprises a flow guide pipe positioned in the connecting pipe, the flow guide pipe is fixed on the inner wall of the connecting pipe, an annular gap is formed between the outer surface of the flow guide pipe and the inner wall of the connecting pipe, and a plurality of through holes are formed in the outer surface of the flow guide pipe; the urea nozzle is used for spraying urea liquid drops into the mixing device, and the through holes of the flow guide pipe are at least partially positioned in the spraying area of the urea nozzle so as to break the urea liquid drops; the honeycomb duct comprises a first end close to the mixing tube and a second end opposite to the first end, the first end is provided with a plurality of claw parts which expand outwards, a slot for exhaust to pass through is formed between every two adjacent claw parts, and the slot is communicated with the gap; the mixing device includes an annular airflow opening between an outer surface of the second end and an inner wall of the connecting tube, the annular airflow opening being in communication with the gap such that a portion of the exhaust gas passing through the slot can flow directly out of the annular airflow opening along the gap.

2. The mixing device of claim 1, wherein: the second end is open and is suspended in the connecting pipe.

3. The mixing device of claim 1, wherein: the honeycomb duct is cylindrical, and the claw parts are welded and fixed on the inner wall of the connecting pipe; the exhaust gas passing through the slots can flow into the flow guide pipe from the gaps and the through holes so as to blow away urea droplets or precipitated urea crystals remaining on the flow guide pipe.

4. A mixing device according to claim 3, wherein: the honeycomb duct is round platform form, the diameter of first end is greater than the diameter of second end, just first end welded fastening is in on the inner wall of connecting pipe.

5. The mixing device of claim 1, wherein: the mixing pipe and the connecting pipe are welded and fixed together.

6. The mixing device of claim 1, wherein: the mixing pipe assembly further comprises an outer pipe sleeved on the periphery of the connecting pipe.