Exhaust gas aftertreatment mixing device and its packaging

Abstract

An exhaust gas post-treatment mixing device comprises a housing and a mixing assembly located in the housing, wherein the housing is provided with a mounting seat for mounting a urea nozzle, the mixing assembly comprises a pre-mixer, a cone located downstream of the pre-mixer, and at least one layer of a crushing plate installed in the cone, the pre-mixer can guide the exhaust gas to form a swirl to enter the cone, and the crushing plate is provided with a plurality of perforations for crushing urea droplets ejected from the urea nozzle. Such an arrangement increases the distance and time of urea evaporation, improves the uniformity of airflow mixing, and reduces the risk of crystallization.

Description

Technical Field

[0001] The invention relates to an exhaust gas post-processing mixing device and packaging thereof, belonging to the technical field of engine exhaust gas post-processing. Background Art

[0002] Studies have shown that the uniformity of ammonia distribution in the pipeline of the exhaust aftertreatment system (such as the selective catalytic reduction system, SCR system) has an important impact on the overall performance and durability of the system. If the ammonia distribution is uneven, it will lead to excessive ammonia in local areas, which is easy to cause ammonia leakage, and in other areas where the ammonia is thin, the nitrogen oxide (NOx) conversion efficiency will be too low. Long-term uneven distribution of ammonia will cause uneven aging of the catalyst, thereby affecting the overall performance of the catalyst. In addition, the uneven distribution of urea droplets will cause the temperature of the local pipe wall or mixing structure to be too low, forming crystals, which will block the exhaust pipe in severe cases and cause the engine power performance to decrease.

[0003] Therefore, it is necessary to provide a novel exhaust gas aftertreatment mixing device and its packaging to solve the above technical problems. Summary of the invention

[0004] The object of the present invention is to provide an exhaust gas post-treatment mixing device with strong anti-crystallization ability and an exhaust gas post-treatment package having the exhaust gas post-treatment mixing device.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an exhaust gas aftertreatment mixing device, comprising a shell and a mixing assembly located in the shell, wherein the shell is provided with a mounting seat for mounting a urea nozzle, the mixing assembly comprises a premixer, a cone located downstream of the premixer, and at least one layer of a crushing plate installed in the cone, the premixer can guide the exhaust gas to form a swirl to enter the cone, and the crushing plate is provided with a plurality of perforations for crushing urea droplets sprayed from the urea nozzle.

[0006] As a further improved technical solution of the present invention, the crushing plate is provided with a first area located on one side and a second area located on the other side, the perforations include a plurality of first perforations penetrating the first area and a plurality of second perforations penetrating the second area, and the apertures of the first perforations and the second perforations are different.

[0007] As a further improved technical solution of the present invention, the crushing plate is fixed in the conical tube, and the crushing plate is arc-shaped.

[0008] As a further improved technical solution of the present invention, the crushing plate has several layers.

[0009] As a further improved technical solution of the present invention, the diameter of the conical tube in the exhaust gas flow direction gradually decreases, and the conical tube has a first end face close to the premixer and a second end face away from the premixer, wherein the plane where the first end face is located is inclined with respect to the axis of the shell.

[0010] As a further improved technical solution of the present invention, the mixing assembly includes a cylindrical sleeve connected to the second end surface.

[0011] As a further improved technical solution of the present invention, the mixing assembly includes a porous plate located downstream of the cylindrical sleeve and spaced apart from the cylindrical sleeve.

[0012] As a further improved technical solution of the present invention, the premixer is roughly disc-shaped, and includes a narrow groove extending in the radial direction to tear the premixer into a first part located on one side of the narrow groove and a second part located on the other side of the narrow groove, wherein the first part and the second part are staggered to form a swirl channel.

[0013] As a further improved technical solution of the present invention, the mounting seat is located between the premixer and the cone tube, so that the crushing plate is located within the injection angle of the urea nozzle.

[0014] The present invention also relates to an exhaust gas after-treatment package, which includes a first after-treatment carrier assembly, a second after-treatment carrier assembly located downstream of the first after-treatment carrier assembly, and a third after-treatment carrier assembly located downstream of the second after-treatment carrier assembly. The exhaust gas after-treatment package also includes an exhaust gas after-treatment mixing device located between the second after-treatment carrier assembly and the third after-treatment carrier assembly, and the exhaust gas after-treatment mixing device is the aforementioned exhaust gas after-treatment mixing device.

[0015] Compared with the prior art, the present invention provides a pre-mixer to allow exhaust gas to enter in a swirling manner, and urea is sprayed onto the crushing plate and crushed before mixing with the rotating airflow. This arrangement increases the distance and time for urea evaporation, improves the uniformity of airflow mixing, and reduces the risk of crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a three-dimensional schematic diagram of the exhaust gas aftertreatment mixing device of the present invention.

[0017] Figure 2 yes Figure 1 Left view of .

[0018] Figure 3 yes Figure 1 Right view of .

[0019] Figure 4is a partially exploded perspective view of the mixing assembly.

[0020] Figure 5 Yes Figure 2 Left view after the pre-mixer in .

[0021] Figure 6 yes Figure 1 3D exploded view of .

[0022] Figure 7 yes Figure 1 Schematic diagram of the cross section along line AA. DETAILED DESCRIPTION

[0023] Please refer to Figures 1 to 7 As shown, the present invention discloses an exhaust gas post-treatment mixing device 100, which is used in a post-treatment system such as SCR to treat the exhaust gas of an engine. The exhaust gas post-treatment mixing device 100 comprises a housing 1 and a mixing assembly 2 installed in the housing 1.

[0024] In the illustrated embodiment of the present invention, the housing 1 is cylindrical and is provided with a mounting seat (not shown) for mounting a urea nozzle 11 to spray urea into the mixing assembly 2 .

[0025] The mixing assembly 2 includes a premixer 3 , a cone 4 located downstream of the premixer 3 , at least one layer of a crushing plate 5 installed in the cone 4 , and a porous plate 6 located downstream of the cone 4 .

[0026] The premixer 3 can guide the exhaust gas to form a swirl flow so as to enter the cone 4. In the illustrated embodiment of the present invention, the premixer 3 is substantially disc-shaped, and includes a radially extending slot 30 to tear the premixer 3 into a first portion 31 located on one side of the slot 30 and a second portion 32 located on the other side of the slot 30, wherein the first portion 31 is staggered from the second portion 32 to form a swirl channel 33.

[0027] Please refer to Figure 7As shown, the mounting seat is located between the premixer 3 and the cone 4, so that the crushing plate 5 is located within the injection angle of the urea nozzle 11. The crushing plate 5 is provided with a plurality of perforations for crushing the urea droplets ejected from the urea nozzle 11. The crushing plate 5 is provided with a first area 51 located on one side and a second area 52 located on the other side, and the perforations include a plurality of first perforations 511 penetrating the first area 51 and a plurality of second perforations 521 penetrating the second area 52, and the apertures of the first perforations 511 and the second perforations 521 are different. The crushing plate 5 is fixed in the cone 4, and the crushing plate 5 is arc-shaped. In order to achieve better crushing, in the illustrated embodiment of the present invention, the crushing plate 5 has a plurality of layers.

[0028] The diameter of the tapered tube 4 in the exhaust gas flow direction is gradually reduced to adjust the flow rate of the exhaust gas mixture. The tapered tube 4 has a first end face 41 close to the premixer 3 and a second end face 42 away from the premixer 3, wherein the plane where the first end face 41 is located is inclined to the axis of the housing 1. Such an arrangement can form a relatively large inlet area.

[0029] The mixing assembly 2 comprises a cylindrical sleeve 43 connected to the second end surface 42. The porous plate 6 is located downstream of the cylindrical sleeve 43 and spaced apart from the cylindrical sleeve 43. The porous plate 6 is used to distribute the exhaust mixture to improve the conversion efficiency.

[0030] The present invention also relates to an exhaust gas aftertreatment package, which includes a first aftertreatment carrier assembly (not shown), a second aftertreatment carrier assembly (not shown) located downstream of the first aftertreatment carrier assembly, and a third aftertreatment carrier assembly (not shown) located downstream of the second aftertreatment carrier assembly. The exhaust gas aftertreatment mixing device 100 is located between the second aftertreatment carrier assembly and the third aftertreatment carrier assembly. Preferably, the first aftertreatment carrier assembly is an oxidation catalyst (DOC), the second aftertreatment carrier assembly is a diesel particulate filter (DPF), and the third aftertreatment carrier assembly is a selective catalytic reducer (SCR).

[0031] The above embodiments are only used to illustrate the present invention but not to limit the technical solutions described in the present invention. The understanding of this specification should be based on the technicians in the relevant technical field. Although this specification has described the present invention in detail with reference to the above embodiments, ordinary technicians in the field should understand that technicians in the relevant technical field can still modify or replace the present invention with equivalents, and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. An exhaust gas post-treatment mixing device, comprising a housing and a mixing assembly located in the housing, wherein the housing is provided with a mounting seat for mounting a urea nozzle, characterized in that: The mixing assembly comprises a premixer, a cone tube located downstream of the premixer, and at least one layer of a crushing plate installed in the cone tube, wherein the premixer can guide the exhaust gas to form a swirl flow so as to enter the cone tube, and the crushing plate is provided with a plurality of perforations for crushing urea droplets ejected from the urea nozzle; the crushing plate has a plurality of layers; the crushing plate is fixed in the cone tube, and the crushing plate is arc-shaped; the diameter of the cone tube in the exhaust gas flow direction is successively reduced, and the cone tube has a first end face close to the premixer and a second end face away from the premixer, wherein the plane where the first end face is located is inclined with respect to the axis of the shell.

2. The exhaust gas post-treatment mixing device according to claim 1, characterized in that: The crushing plate is provided with a first area on one side and a second area on the other side, the perforations include a plurality of first perforations penetrating the first area and a plurality of second perforations penetrating the second area, and the first perforations and the second perforations have different apertures.

3. The exhaust gas post-treatment mixing device according to claim 1, characterized in that: The mixing assembly includes a cylindrical sleeve connected to the second end surface.

4. The exhaust gas post-treatment mixing device according to claim 3, characterized in that: The mixing assembly includes a perforated plate located downstream of the cylindrical sleeve and spaced apart from the cylindrical sleeve.

5. The exhaust gas post-treatment mixing device according to claim 1, characterized in that: The premixer is substantially disc-shaped and comprises a radially extending slot to tear the premixer into a first portion located on one side of the slot and a second portion located on the other side of the slot, wherein the first portion is staggered from the second portion to form a swirl channel.

6. The exhaust gas post-treatment mixing device according to claim 1, characterized in that: The mounting seat is located between the premixer and the cone tube, so that the crushing plate is located within the spray angle of the urea nozzle.

7. An exhaust gas aftertreatment package, comprising a first aftertreatment carrier assembly, a second aftertreatment carrier assembly located downstream of the first aftertreatment carrier assembly, and a third aftertreatment carrier assembly located downstream of the second aftertreatment carrier assembly, characterized in that: The exhaust gas after-treatment package further includes an exhaust gas after-treatment mixing device located between the second after-treatment carrier assembly and the third after-treatment carrier assembly, and the exhaust gas after-treatment mixing device is the exhaust gas after-treatment mixing device according to any one of claims 1 to 6.

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