CN216922273U

CN216922273U - SCR aftertreatment mixer and engine using same

Info

Publication number: CN216922273U
Application number: CN202220054881.5U
Authority: CN
Inventors: 郑碧莹; 张军; 霍翠英; 邵冠磊
Original assignee: Weichai Power Co Ltd; Weichai Power Emission Solutions Technology Co Ltd
Current assignee: Weichai Power Co Ltd; Weichai Power Emission Solutions Technology Co Ltd
Priority date: 2022-01-10
Filing date: 2022-01-10
Publication date: 2022-07-08
Anticipated expiration: 2032-01-10

Abstract

The utility model relates to the technical field of automobile engines, and discloses an SCR (selective catalytic reduction) aftertreatment mixer which comprises a cyclone tube, a metal wire mesh and a rectifying plate, wherein the cyclone tube is provided with an inlet end, an outlet end and cyclone holes uniformly distributed in the circumferential direction of the tube wall, and the inlet end of the cyclone tube is communicated with a urea outlet; the wire mesh forms a cone cylinder structure with gradually reduced outer diameter along the airflow flowing direction, and the inlet end of the wire mesh is connected with the outlet end of the cyclone tube; the axial arrangement of cowling panel perpendicular to woven wire is in woven wire's exit end, and a plurality of rectification holes of cowling panel face equipartition. According to the utility model, through the matching of the swirl tube, the wire mesh and the rectifying plate, the mixing uniformity between the urea spray and the waste gas can be enhanced, the concentration uniformity of NH3 in the mixer in the mixed gas is improved, and the crystallization risk is reduced. The metal wire mesh can enhance the heat exchange capability of the mixer, reduce the attachment points of the liquid drops and improve the evaporation and decomposition rate of the urea liquid drops. The metal wire mesh is of a cone-shaped cylinder structure, so that the heat exchange area can be increased, and the heat exchange capacity is enhanced.

Description

SCR aftertreatment mixer and engine using same

Technical Field

The utility model relates to the technical field of automobile engines, in particular to an SCR (selective catalytic reduction) aftertreatment mixer and an engine using the same.

Background

The main measures for reducing the NOx emission of the diesel vehicle comprise two technical routes: 1) exhaust Gas Recirculation (EGR) technology: exhaust gas recirculation can reduce the maximum combustion temperature of the engine, thereby reducing NOx emission, but the high EGR rate weakens the output power of the engine and influences the combustion efficiency; 2) selective Catalytic Reduction (SCR) technology. The SCR system mainly comprises a catalyst, a urea supply system (UDS for short), a control system (ECU, sensors, wire harnesses, etc.), and corresponding connecting pipelines. The SCR system basic working principle: the exhaust gas flows out of a turbocharger turbine and enters an exhaust pipe, a certain amount of urea aqueous solution is sprayed into the exhaust pipe in a mist form by a urea spraying unit arranged on the exhaust pipe, urea liquid drops are subjected to hydrolysis and pyrolysis reaction under the action of high-temperature exhaust gas to generate required reducing agent ammonia (NH3), and the ammonia (NH3) selectively reduces nitrogen oxides (NOx) into nitrogen (N2) under the action of a catalyst. The SCR system has the advantages of high NOx conversion rate, wide temperature window, sulfur poisoning resistance, good thermal stability and the like.

The SCR aftertreatment mixer is a device arranged between an exhaust pipe and an SCR carrier, and is mainly used for improving the mixing uniformity between urea spray and exhaust gas and improving the NOx conversion efficiency. However, the mixing uniformity between the urea spray and the exhaust gas of the SCR aftertreatment mixer in the prior art is not sufficient, and urea deposition and crystallization are generated in the long-term use process, so that the SCR aftertreatment mixer is blocked, and the risk of SCR failure is caused.

Therefore, how to provide an SCR aftertreatment mixer to reduce the crystallization rate is a technical problem to be solved by those skilled in the art.

Disclosure of Invention

To address one or more of the problems of the prior art, or at least to provide a useful alternative, the present invention provides an SCR aftertreatment mixer to reduce crystallization rates. In addition, the utility model also provides an engine with the SCR aftertreatment mixer.

The utility model discloses an SCR aftertreatment mixer, which comprises

The cyclone tube is provided with an inlet end, an outlet end and cyclone holes uniformly distributed in the circumferential direction of the tube wall, and the inlet end of the cyclone tube is communicated with the urea outlet;

the wire mesh forms a cone structure with gradually-reduced outer diameter along the airflow flowing direction, and the inlet end of the wire mesh is connected with the outlet end of the cyclone tube;

the fairing, the fairing perpendicular to the axial of wire mesh arrange in the exit end of wire mesh, just a plurality of rectification holes of fairing face equipartition.

As a preferred scheme of SCR aftertreatment blender, still set up the baffle between cyclone tube and the wire mesh, the baffle is perpendicular to the axial arrangement of cyclone tube.

As a preferred scheme of the SCR aftertreatment mixer, the outer diameters of the baffle plate and the rectifying plate are the same.

Preferably, the cyclone tube and the baffle plate are hermetically welded, and/or the baffle plate and the wire mesh are hermetically welded.

As a preferable aspect of the SCR aftertreatment mixer, the wire mesh includes a mesh cylinder and a support member provided along a circumferential direction of the mesh cylinder.

As a preferable mode of the SCR aftertreatment mixer, the support member is at least one fixing ring provided in a circumferential direction of the mesh cylinder.

As a preferred solution for the SCR aftertreatment mixer, the mesh of the wire mesh is gradually reduced in the direction of the gas flow.

As a preferred variant of the SCR aftertreatment mixer, the axial projection of the wire mesh is located in the region of the fairing plate in which the fairing holes are provided.

As a preferable mode of the SCR aftertreatment mixer, the rectifying holes are radially distributed along the center of the rectifying plate.

The utility model also discloses an engine which comprises the SCR after-treatment mixer, wherein the SCR after-treatment mixer is any one of the SCR after-treatment mixers.

The utility model discloses an SCR aftertreatment mixer and an engine using the same, which have the following beneficial effects:

(1) according to the utility model, through the matching of the swirl tube, the wire mesh and the rectifying plate, the mixing uniformity between the urea spray and the waste gas can be enhanced, the concentration uniformity of NH3 in the mixer in the mixed gas is improved, and the crystallization risk is reduced, so that the requirements of post-treatment emission in the four stages of national six and non-road are met.

(2) Compared with a plate hole structure, the metal wire mesh has a finer mesh structure, and the metal wires are arranged among meshes, so that the heat exchange capacity of the mixer is enhanced, the attachment points of liquid drops are reduced, the evaporation and decomposition rate of the urea liquid drops is improved, and the problem that the urea liquid drops collide with the wall and are crystallized due to incomplete urea decomposition is solved. And because the metal wire is thinner, the cutting effect to urea can be formed, the secondary crushing effect of the urea aqueous solution is improved, the mixing degree of the mixed gas is enhanced, and the mixing uniformity is enhanced.

(3) The metal wire mesh is in a conical cylinder structure, and compared with a straight cylinder structure, the contact area of the metal wire mesh and urea can be obviously increased, so that the heat exchange area is increased, and the heat exchange capacity of the mixer is enhanced. And, along with the whole area increase of wire mesh, set up the mesh number on the wire mesh and also increase thereupon, also better to the crushing effect of urea.

(4) In order to avoid the problem that urea cannot be crushed because the urea directly flows through the outside of the metal wire mesh, the partition plate is arranged between the spiral flow pipe and the metal wire mesh, so that the urea is ensured to flow into the spiral flow pipe from the spiral flow holes and is crushed and flows out through the metal wire mesh, the evaporation and decomposition rate of urea droplets is improved, and the problem that the urea droplets collide with the wall and are crystallized due to incomplete urea decomposition is avoided.

(5) In order to reduce the adhesion of the urea liquid on the rectifying plate after the urea is crushed, the utility model also arranges that the area of the rectifying hole of the rectifying plate is larger than the axial projection area of the wire mesh, so that the crushed urea liquid is completely led out from the rectifying hole, and the evaporation and decomposition rate of the urea liquid drops is accelerated.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model and not to limit the utility model. In the drawings:

fig. 1 is a schematic structural view of an SCR aftertreatment mixer disposed in a mounting chamber according to an embodiment of the utility model.

FIG. 2 is a schematic diagram of an SCR aftertreatment mixer according to an embodiment of the utility model.

Description of reference numerals:

1-cyclone tube, 11-cyclone hole, 12-guide vane;

2-a separator;

3-wire mesh, 31-support;

4-rectifying plate, 41-rectifying hole.

Detailed Description

In order to more clearly explain the overall concept of the present invention, the following detailed description is given by way of example in conjunction with the accompanying drawings.

It should be noted that in the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and thus the scope of the present invention is not limited by the specific embodiments disclosed below.

In addition, in the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate orientations and positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; either directly or indirectly through intervening media, either internally or in any other relationship. However, the direct connection means that the two bodies are not connected through a transition structure, but connected through a connection structure to form a whole. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The specific scheme is as follows:

as shown in fig. 1 and fig. 2, the SCR aftertreatment mixer disclosed in this embodiment is installed in a box-type mixer for use, and includes a cyclone tube 1, a wire mesh 3, and a rectifying plate 4. The cyclone tube 1 is provided with an inlet end, an outlet end and cyclone holes 11 uniformly distributed in the circumferential direction of the tube wall, the inlet end of the cyclone tube 1 is communicated with a urea outlet, and the cyclone holes 11 are used for passing strong rotating airflow to the SCR aftertreatment mixer; the metal wire mesh 3 forms a cone structure with gradually-reduced outer diameter along the airflow flowing direction, the metal wire mesh 3 is mainly surrounded by metal wires, fine through holes are formed on the surface of the metal wire mesh 3, and the inlet end of the metal wire mesh 3 is connected with the outlet end of the cyclone tube 1; the rectifying plate 4 is arranged at the outlet end of the wire mesh 3 in a manner of being perpendicular to the axial direction of the wire mesh 3, and a plurality of rectifying holes 41 are uniformly distributed on the surface of the rectifying plate 4.

The cooperation of swirl tube 1, wire mesh 3, cowling panel 4 is passed through to this embodiment, can strengthen mixing uniformity between urea spraying and the waste gas, improves the concentration uniformity of NH3 in the blender in the mist, reduces the crystallization risk to satisfy six countries and non-road four-stage aftertreatment emission demand.

Wire mesh 3 in this embodiment has more fine mesh structure for the pore structure, and because be the wire between each mesh, when urea sprays, reinforcing blender heat transfer ability reduces the liquid drop attachment point, promotes the evaporation decomposition rate of urea liquid drop, avoids urea to decompose incompletely and leads to the urea liquid drop to hit the wall crystallization problem. And because the metal wire is thinner, the cutting effect to urea can be formed, the secondary crushing effect of the urea aqueous solution is improved, the mixing degree of the mixed gas is enhanced, and the mixing uniformity is enhanced.

In this embodiment, the wire mesh 3 is a conical cylinder structure, and compared with a straight cylinder structure, the contact area with urea can be significantly increased, so that the heat exchange area is increased, and the heat exchange capability of the mixer is enhanced. Moreover, as the whole area of the wire mesh 3 is increased, the number of meshes arranged on the wire mesh 3 is increased, and the urea crushing effect is better.

The specific structure of the cyclone tube 1 is not limited in this application, and in some embodiments, it may be a straight tube structure, or other shape. Whirl hole 11 is for setting up in whirl pipe 1 circumference, have the hole that is used for guide vane 12, and the length direction in hole is whirl pipe 1's axial direction to can utilize great flow area to spray urea, make urea evaporate fast at the rear end.

The working process of the embodiment is as follows:

engine tail gas gets into cyclone tube 1 from the entry end, and the leading-in air current of cyclone tube 1 lateral part to under the effect of guide vane 12 of lateral wall, improve air current intensity. The urea spray enters from the side of the cyclone tube 1, so that the air flow generates cyclone, the urea spray is dispersed, and after the urea is mixed with the engine exhaust, the urea is fully reacted and enters the metal wire mesh 3. In the area of the wire mesh 3, the urea liquid drops rotating at high speed under the action of the rotational flow collide with the wires of the wire mesh 3 at high speed to generate crushing, so that the mixing degree of the mixed gas is enhanced, and the mixing uniformity is enhanced. In addition, the metal wire mesh 3 structure that is the cone shape can show the area of contact who improves urea spraying and blender, increases heat transfer area, strengthens blender heat transfer ability, reduces the problem that the blender was blockked up in the urea crystallization. And along with the radial size of the cone structure along the airflow direction shrinks gradually, the urea spray is easier to contact with the metal wire mesh 3, and the crushing effect of the spray is further improved. The provided rectifying plate 4 can guide the spray flowing out of the wire mesh 3 along the direction of the rectifying hole 41, namely, the spray is quickly discharged along the axial direction of the pipeline, so that the mixing path is increased, the mixing effect is improved, and the crystallization risk is reduced.

Further, as shown in fig. 1 and 2, in one embodiment, a partition plate 2 is further disposed between the cyclone tube 1 and the wire mesh 3, and the partition plate 2 is perpendicular to the axial direction of the cyclone tube 1. Baffle 2 sets up between cyclone tube 1 and wire mesh 3, can block the air current, avoids taking place to mix inhomogeneous problem because of the air current directly gets into in the space at wire mesh 3 place. And the air current flow direction that gets into from the entry end of cyclone tube 1 is perpendicular to baffle 2, can take place backward flow in baffle 2 department, makes the urea spraying dispersion.

Those skilled in the art can understand that the present application does not limit the specific shape of the partition board 2, and it can be any shape, such as circular (circular ring), on the premise of ensuring the sealing connection with the inner wall of the box-type mixer gas channel, the periphery of the circular ring is sealed with the inner wall of the box-type mixer gas channel, and the center of the circular ring is provided with the cyclone tube 1 and forms a sealing connection with the cyclone tube 1.

Further, in one embodiment, cyclone tube 1 and baffle 2 are hermetically welded, and baffle 2 and wire mesh 3 are hermetically welded. Through above-mentioned seal structure in order to avoid the air current to flow from the clearance between cyclone tube 1, baffle 2 or wire mesh 3, improve the crushing efficiency and the mixing efficiency of urea liquid drop.

It can be understood by those skilled in the art that the cyclone tube 1, the partition plate 2, and the wire mesh 3 can be welded to form a sealing structure, or can be formed into a sealing structure by other methods, such as arranging the cyclone plate and the partition plate 2 as an integral structure. In addition, can also form the cover with whirl pipe 1 and wire mesh 3 and establish welded relation to with baffle 2 seal welding in whirl pipe 1 periphery. Moreover, the seal welding of the cyclone tube 1 and the partition plate 2 and the seal welding of the partition plate 2 and the wire mesh 3 can be independently arranged respectively.

In order to avoid that urea droplets flow out with the gas flow in an undesired manner in the gap, in one embodiment the partition plate 2 and the fairing plate 4 have the same outer diameter. With this structure, on the one hand can do benefit to the assembly of SCR aftertreatment blender, on the other hand can reduce the problem of air current leakage. In addition, because the external diameter of baffle 2 and cowling panel 4 is the same, when fixing the installation cavity, can form radial supporting effect respectively in baffle 2 department, cowling panel 4 department, guarantee the working process, the stability of SCR aftertreatment blender.

As shown in fig. 1, 2, in order to further improve the stability of the SCR aftertreatment mixer, in one embodiment the wire mesh 3 comprises a mesh cylinder and a support 31 arranged circumferentially along the mesh cylinder. Because SCR aftertreatment blender can be because reasons such as exhaust emission, whirl leading-in at the course of the work, and the air current that leads to SCR aftertreatment blender to locate is not regular air current, but can improve urea liquid drop and tail gas mixing efficiency's dispersed air current, through set up support piece 31 in the periphery of a net section of thick bamboo, can form the radial cramping effect to a net section of thick bamboo, improves the stability of a net section of thick bamboo.

The structure of the supporting member 31 is not particularly limited, and in one embodiment, the supporting member 31 is a fixing ring disposed on the circumferential direction of the net cylinder, and the fixing ring forms a tightening action on the net cylinder in the radial direction (radially inward and radially outward). It will be appreciated by those skilled in the art that the number of the supporting members 31 may be plural, that is, plural fixing rings are distributed on the periphery of the wire-net 3 along the axial direction, which provides a better supporting function for the wire-net 3 structure with a larger axial length.

In an embodiment, which is not shown in the drawings, the supporting member 31 may be a fixing ring disposed inside the wire mesh 3, and the structure thereof is similar to the above structure, and will not be described herein again.

In an embodiment, not shown, the support member 31 may be a support rod disposed inside the wire mesh 3 and radially supporting the inner wall of the wire mesh 3, so as to prevent inward deformation of the wire mesh 3 by radial support.

In addition, the supporting member 31 may also be another structure that is engaged with the inner wall of the installation chamber, such as a supporting rod disposed outside the wire mesh 3, and is supported radially to prevent the wire mesh 3 from deforming outwards.

As shown in fig. 1 and 2, in one embodiment, in order to improve the breaking effect of the urea spray at the end (the outlet end of the wire 3), the mesh size of the wire 3 is gradually reduced in the flow direction of the gas flow, so that the urea spray is broken further at the end along the stroke of the gas flow. In addition, the centrifugal force of urea liquid drops at the center is low, the crushing efficiency is relatively low, and in combination with the embodiment, the metal wire net 3 is in a cone structure, when the outer diameter of the outlet end of the metal wire net 3 is gradually narrowed, the centrifugal force of the urea liquid drops is formed, and fluid thrust along the axial direction can also be formed, so that the crushing efficiency of the urea liquid drops which are not crushed completely at the center can be improved, the mixing effect is improved, and the crystallization risk is reduced.

As shown in fig. 1 and 2, in one embodiment, the axial projection of the wire mesh 3 is located in the area of the flow straightening plate 4 where the flow straightening holes 41 are provided. In order to reduce the adhesion of the urea liquid on the rectifying plate 4 after the urea is crushed, in this embodiment, the area of the rectifying holes 41 of the rectifying plate 4 is larger than the axial projection area of the wire mesh 3, so that the axial projection of the wire mesh 3 is located in the area of the rectifying plate 4 where the rectifying holes 41 are arranged, so that the crushed urea liquid is completely led out from the rectifying holes 41, and the evaporation and decomposition rate of the urea liquid drops is increased.

As mentioned above, the flow-regulating plate 4 is arranged to guide the spray from the wire mesh 3 in the direction of the flow-regulating hole 41, i.e. to discharge quickly in the axial direction of the pipeline, so as to increase the mixing path, and in order to further improve the mixing path, in one embodiment, the flow-regulating holes 41 are distributed radially along the center of the flow-regulating plate 4, so as to improve the crushing effect of the urea aqueous solution, effectively reduce the particle size, promote more sufficient mixing of ammonia gas and exhaust gas, and further reduce the crystallization risk.

The utility model also discloses an engine, which comprises the SCR after-treatment mixer, wherein the SCR after-treatment mixer is the SCR after-treatment mixer disclosed by any one of the embodiments, so that the engine comprising any one of the embodiments also has all the technical effects, and the details are not repeated herein.

It will be understood by those skilled in the art that the present invention can also be applied to an automobile using the engine disclosed in the above embodiment, that is, an automobile including the engine disclosed in the above embodiment, which also has all the technical effects described above.

The technical solutions protected by the present invention are not limited to the above embodiments, and it should be noted that the combination of the technical solution of any one embodiment and the technical solution of one or more other embodiments is within the protection scope of the present invention. Although the utility model has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the utility model. Accordingly, such modifications and improvements are intended to be within the scope of the utility model as claimed.

Claims

1. An SCR aftertreatment mixer, comprising

the wire mesh forms a cone cylinder structure with gradually reduced outer diameter along the airflow flowing direction, and the inlet end of the wire mesh is connected with the outlet end of the cyclone tube;

2. An SCR aftertreatment mixer according to claim 1 wherein a baffle is provided between the swirl tube and the wire mesh, the baffle being arranged perpendicular to the axial direction of the swirl tube.

3. An SCR aftertreatment mixer according to claim 2 wherein the external diameters of the baffle and the fairing are the same.

4. An SCR aftertreatment mixer according to claim 2 wherein said swirl tube and said baffle, and/or said baffle and said wire mesh, are seal welded.

5. An SCR aftertreatment mixer according to claim 1 wherein the wire mesh comprises a mesh cylinder and a support circumferentially disposed along the mesh cylinder.

6. An SCR aftertreatment mixer according to claim 5, wherein the support is at least one retaining ring disposed circumferentially of the mesh cylinder.

7. An SCR aftertreatment mixer according to claim 1 wherein the mesh size of the wire mesh is progressively reduced in the direction of flow of the gas stream.

8. An SCR aftertreatment mixer according to claim 1 wherein the axial projection of the wire mesh is located in the region of the fairing plate where the fairing holes are provided.

9. An SCR aftertreatment mixer according to claim 1 wherein the flow rectifier holes are distributed radially along the centre of the flow rectifier plate.

10. An engine comprising an SCR aftertreatment mixer, wherein the SCR aftertreatment mixer is an SCR aftertreatment mixer according to any one of claims 1-9.