CN112177725A

CN112177725A - Mixing chamber subassembly and tail gas aftertreatment encapsulation

Info

Publication number: CN112177725A
Application number: CN202011285895.XA
Authority: CN
Inventors: 凌睿; 严才宝; 吴涛涛; 王长林; 郑鑫
Original assignee: Tenneco Suzhou Emission System Co Ltd
Current assignee: Tenneco Suzhou Emission System Co Ltd
Priority date: 2020-11-17
Filing date: 2020-11-17
Publication date: 2021-01-05

Abstract

A mixing chamber assembly includes a mixing chamber housing and a mixing tube assembly mounted within the mixing chamber housing. The mixing chamber shell is provided with a first cavity and a second cavity. The mixing tube assembly includes a swirl tube positioned in the first cavity and a connecting tube positioned in the second cavity. The cyclone tube is provided with a first inner cavity, a plurality of cyclone plates and an airflow inlet corresponding to the cyclone plates. Mix the pipe assembly and still including being located in first cavity and part surround the arc of spinning disk to make tail gas need walk around the arc just can be certainly air inlet gets into the cyclone tube. So set up, avoided a large amount of directness of tail gas to towards the whirl pipe to cause the inhomogeneous of air current distribution, be favorable to improving the ability of anti urea crystallization. The invention also relates to an exhaust aftertreatment package comprising the mixing chamber assembly.

Description

Mixing chamber subassembly and tail gas aftertreatment encapsulation

Technical Field

The invention relates to a mixing cavity assembly and an exhaust aftertreatment package, and belongs to the technical field of engine exhaust aftertreatment.

Background

Studies have shown that the degree of uniformity of ammonia distribution in the lines of an exhaust aftertreatment system (e.g., a selective catalytic reduction system, SCR system) has a significant impact on the overall performance and durability of the system. The uneven distribution of ammonia over time can result in uneven catalyst aging, thereby affecting the overall performance of the catalyst. In addition, the uneven distribution of urea liquid drops can cause that the temperature of a local pipe wall or a mixed structure is too low, crystals are formed, and a tail gas pipe is blocked when the temperature is serious, so that the power performance of an engine is reduced.

Disclosure of Invention

The invention aims to provide a mixing cavity assembly with good urea crystallization resistance and an exhaust aftertreatment package.

In order to achieve the purpose, the invention adopts the following technical scheme: a mixing cavity assembly comprises a mixing cavity shell and a mixing tube assembly arranged in the mixing cavity shell, wherein the mixing cavity shell is provided with a first opening communicated with a first post-processing carrier assembly, a second opening communicated with a second post-processing carrier assembly, a first cavity communicated with the first opening and a second cavity communicated with the second opening; the mixing tube assembly comprises a swirl tube located in the first cavity and a connecting tube located in the second cavity; the cyclone tube is provided with a first inner cavity, a plurality of cyclone plates and an airflow inlet corresponding to the cyclone plates, the first inner cavity is communicated with the first cavity through the airflow inlet, the connecting tube is provided with a second inner cavity communicated with the first inner cavity, and the second inner cavity is communicated with the second cavity; mix the pipe assembly and still including being located in first cavity and part surround the arc of spinning disk to make tail gas need walk around the arc just can be certainly air inlet gets into the cyclone tube.

As a further improved technical scheme of the invention, the cross section of the arc-shaped plate is C-shaped.

As a further improved technical scheme of the invention, the central axis of the arc-shaped plate is parallel to the central axis of the cyclone tube, and the mixing cavity assembly comprises an arc-shaped airflow channel positioned between the arc-shaped plate and the cyclone tube.

As a further improved technical scheme of the invention, the mixing cavity shell is provided with a mounting seat for mounting a urea nozzle, and the urea nozzle is used for spraying atomized urea liquid drops into the cyclone tube.

As a further improved technical scheme of the present invention, the mixing chamber housing is provided with a first mounting surface which is close to the mounting seat and located inside the first cavity, one end of the arc-shaped plate is provided with a first mounting claw fixed on the first mounting surface and a slot located beside the first mounting claw, and the slot is communicated with the arc-shaped airflow channel.

As a further improved technical scheme of the invention, the mixing cavity shell is provided with a partition plate positioned between the first cavity and the second cavity, and the other end of the arc-shaped plate is provided with a second mounting claw fixed on the partition plate.

As a further improved technical solution of the present invention, the mixing chamber assembly includes an end assembly located in the second chamber and at the bottom of the connecting pipe, and the end assembly includes a bottom wall, a peripheral wall extending upward from the periphery of the bottom wall, and a buffer chamber enclosed by the bottom wall and the peripheral wall.

As a further development of the invention, the circumferential wall is provided with a first side wall facing the second aftertreatment carrier assembly, the first side wall being provided with a number of first gas flow perforations through which a gas flow flows.

As a further improved technical scheme of the invention, the mixing pipe assembly comprises a urea crushing pipe positioned in the first inner cavity and the second inner cavity, the urea crushing pipe extends along the axial direction, a plurality of urea crushing grooves are arranged on the outer wall of the urea crushing pipe, and the length of the urea crushing grooves along the axial direction is greater than the width of the urea crushing grooves along the radial direction perpendicular to the axial direction.

The invention also discloses an exhaust aftertreatment package which comprises a first aftertreatment carrier component, a second aftertreatment carrier component, a third aftertreatment carrier component positioned at the upstream of the first aftertreatment carrier component and a mixing cavity component for connecting the first aftertreatment carrier component and the second aftertreatment carrier component, wherein the first aftertreatment carrier component is a diesel particle trap, the second aftertreatment carrier component is a selective catalytic reducing agent, the third aftertreatment carrier component is a diesel oxidation catalyst, and the mixing cavity component is the mixing cavity component.

Compared with the prior art, the tail gas can enter the cyclone tube from the airflow inlet only by bypassing the arc-shaped plate through arranging the arc-shaped plate partially surrounding the cyclone sheet; so set up, avoided certainly the air current that first opening flowed in directly dashes in a large number to the whirl pipe to cause the inhomogeneous of air current distribution, be favorable to improving the ability of anti urea crystallization.

Drawings

FIG. 1 is a schematic view of an exhaust aftertreatment package of the present invention.

FIG. 2 is a perspective view of a mixing chamber assembly of the present invention in one embodiment.

Fig. 3 is a partially exploded perspective view of fig. 2.

Fig. 4 is a perspective view of the mixing chamber housing of fig. 2 removed.

Fig. 5 is an exploded perspective view of fig. 4.

Fig. 6 is a front view of the urea break pipe of fig. 5.

Fig. 7 is a schematic sectional view taken along line a-a in fig. 2.

Fig. 8 is a schematic sectional view taken along line B-B in fig. 2.

Detailed Description

Referring to fig. 1, the present invention discloses an exhaust gas aftertreatment package, which includes a first aftertreatment carrier assembly 1, a second aftertreatment carrier assembly 2, a third aftertreatment carrier assembly 3 located upstream of the first aftertreatment carrier assembly 1, and a mixing chamber assembly 4 connecting the first aftertreatment carrier assembly 1 and the second aftertreatment carrier assembly 2. In one embodiment of the invention, the first aftertreatment carrier component 1 is a diesel particulate trap (DPF), the second aftertreatment carrier component 2 is a Selective Catalytic Reduction (SCR) and the third aftertreatment carrier component 3 is a Diesel Oxidation Catalyst (DOC).

The mixing chamber assembly 4 includes a mixing chamber housing 5 and a mixing tube assembly 6 mounted within the mixing chamber housing 5. The mixing chamber housing 5 is provided with a first opening 51 for communicating with a first aftertreatment carrier assembly 1, a second opening 52 for communicating with a second aftertreatment carrier assembly 2, a first cavity 53 communicating with the first opening 51, a second cavity 54 communicating with the second opening 52, and a partition 55 between the first cavity 53 and the second cavity 54.

The mixing tube assembly 6 comprises a cyclone tube 61 located in the first cavity 53, a connecting tube 62 located in the second cavity 54, an arc-shaped plate 63 located in the first cavity 53 and partially surrounding the cyclone tube 61, a urea crushing tube 64 installed in the cyclone tube 61 and the connecting tube 62, and a urea crushing plate 65 fixed at the bottom of the connecting tube 62 and located at the bottom of the urea crushing tube 64.

The cyclone tube 61 is provided with a first inner cavity 611, a plurality of cyclones 612 and an air inlet 613 corresponding to the cyclones 612. The first inner cavity 611 communicates with the first cavity 53 through the gas flow inlet 613. The connecting pipe 62 is provided with a second inner cavity 621 communicated with the first inner cavity 611, and the second inner cavity 621 is communicated with the second cavity 54. The wall of the connecting pipe is provided with a plurality of air flow perforations 622. The curved plate 63 partially surrounds the swirl plate 612, so that the exhaust gas from the first opening 51 can pass through the curved plate 63 to enter the swirl tube 61 from the gas inlet 613. In the illustrated embodiment of the invention, the arcuate plate 63 is C-shaped in cross-section. The central axis O1 of the arc-shaped plate 63 is parallel to the central axis O2 of the cyclone tube 61, and the mixing chamber assembly 4 includes an arc-shaped airflow channel 60 between the arc-shaped plate 63 and the cyclone tube 61.

The mixing chamber shell 5 is provided with a mounting seat 531 for mounting a urea nozzle 7, and the urea nozzle 7 is used for spraying atomized urea liquid drops into the cyclone tube 61. The mixing chamber housing 5 is provided with a first mounting surface 532 close to the mounting seat 531 and located inside the first cavity 53.

One end of the arc plate 63 is provided with a first mounting claw 631 fixed to the first mounting surface 532, and the other end of the arc plate 63 is provided with a second mounting claw 632 fixed to the partition plate 55. The arc plate 63 is further provided with a slot 630 at the side of the first mounting jaw 631, and the slot 630 communicates with the arc air flow path 60 to adjust the back pressure. In the illustrated embodiment of the present invention, the first mounting claws 631 are provided in plurality, and the slot 630 is located between two adjacent first mounting claws 631.

In addition, the mixing chamber assembly 4 includes an end assembly 8 located within the second chamber 54 and at the bottom of the connecting tube 62. The end assembly 8 is substantially "boat-shaped". The end assembly 8 includes a bottom wall 81, a peripheral wall 82 extending upwardly from the periphery of the bottom wall 81, and a buffer chamber 83 defined by the bottom wall 81 and the peripheral wall 82. The peripheral wall 82 is provided with a first side wall 821 facing the second aftertreatment carrier assembly 2, a second side wall 822 disposed opposite to the first side wall 821, a first arc-shaped wall 823 between the first side wall 821 and the second side wall 822, and a second arc-shaped wall 824. The first side wall 821 is provided with a plurality of first flow apertures 825 for allowing a mixed flow of off-gas and urea droplets to pass therethrough, thereby facilitating the direction of the mixed flow towards the end face of the downstream second aftertreatment carrier assembly 2. The second side wall 822 is not perforated to avoid dead space by the mixture flow to the side away from the second aftertreatment carrier assembly 2. The first and second

curved walls

823, 824 are configured to swirl the mixed gas flow, thereby increasing the mixing distance and enhancing the evaporation of urea droplets. Preferably, the bottom wall 81 is inclined, and one end of the bottom wall 81 close to the first side wall 821 is lower than one end close to the second side wall 822; with this arrangement, even if a liquid film is formed, the liquid film flows out to the second aftertreatment support element 2 side along the inclined bottom wall 81, thereby preventing urea crystallization due to continuous accumulation of the liquid film. Preferably, the bottom of the first side wall 821 is provided with a diversion channel 826 to facilitate the liquid to flow out; meanwhile, the guide groove 826 can also adjust the uniformity of the mixed air flow when the mixed air flow flows out of the buffer cavity 83.

In addition, the mixing chamber assembly 4 may further include a regulating plate 84 disposed in the buffer chamber 83, and the regulating plate 84 is provided with a plurality of through holes 841, so that further crushing of the urea droplets can be performed. The adjusting plate 84 has a bottom 842, wherein an end of the bottom 842 near the first side wall 821 is lower than an end near the second side wall 822. With this arrangement, even if a liquid film is formed, the liquid film flows out to the second aftertreatment support element 2 side along the inclined bottom 842, thereby preventing urea crystallization due to continuous accumulation of the liquid film.

The mixing chamber assembly 4 is further provided with a gas flow distribution plate 85, the gas flow distribution plate 85 is provided with a plurality of second gas flow perforations 851, and the gas flow distribution plate 85 and the first side wall 821 are located on the same side of the buffer chamber 83. So configured, the mixed gas flow of the exhaust gas and the urea droplets can pass through the first gas flow perforation 825 and the second gas flow perforation 851, thereby facilitating the uniform distribution of the mixed gas flow on the end face of the second aftertreatment carrier assembly 2.

Broken pipe 64 of urea is located first interior cavity 611 with in the second interior cavity 621, broken pipe 64 of urea extends along axial M, be equipped with a plurality of broken grooves 641 of urea on broken pipe 64's the outer wall of urea, broken groove 641 is followed axial M's length L is greater than along the perpendicular to axial M's radial N's width W. The urea break tank 641 facilitates further breaking up the urea particles into smaller particles, thereby reducing the risk of urea crystallization and improving ammonia uniformity. In addition, when the urea droplets form a liquid film in a part of the urea breaking groove 641, the liquid film can also move along the axial direction M by the blowing of the air flow and/or the gravity. The moving liquid film facilitates the absorption of the temperature of the gas stream and thus the evaporation of itself. The design avoids the liquid film staying in a part for a long time, thereby greatly reducing the risk of urea crystallization. Even if the liquid film accumulated in the urea breaking pipe 64 drops into the end assembly 8 due to the fact that the liquid film cannot be evaporated in time, the liquid film can be broken again through the through hole 841 in the adjusting plate 84, evaporation of urea liquid drops is facilitated, and the risk of urea crystallization is reduced.

When in use, the tail gas of the diesel engine passes through the third aftertreatment carrier component 3 and the first aftertreatment carrier component 1 and enters the first cavity 53 through the first opening 51; since the arc plate 63 covers the cyclone plate 612 facing the first opening 51, the exhaust gas from the first opening 51 bypasses the arc plate 63 to enter the cyclone tube 61 through the gas inlet 613. With the arrangement, the tail gas flowing from the first opening 51 is prevented from directly rushing to the cyclone tube 61 in a large amount, so that the uneven distribution of the gas flow is caused, and the improvement of the anti-urea crystallization capacity is facilitated. In the process, most of the tail gas enters the cyclone tube 61 from the gas inlet 613 facing away from the first opening 51 on both sides or from the gas inlet 613 facing the first opening 51 through the arc-shaped gas channel 60; a small portion of the exhaust flows from slots 630 to swirl tube 61. The tail gas is guided by the cyclone plate 612 to rotate and enter the cyclone tube 61; the tail gas and urea liquid drops are mixed in the cyclone tube 61 and form a downward rotating airflow; during the downward flow of the gas flow, the urea liquid drops are further crushed by the urea crushing pipe 64; subsequently, a part of the mixed gas flow further collides with the urea breaker plate 65, thereby further breaking the urea droplets; a portion of the mixed gas stream continues downwardly until it contacts the bottom wall 81 of the end module 8; at this time, a part of the mixed gas flow is blocked by the bottom wall 81, and turns around and flows upward; the swirling mixed air flow generates swirling flow along the first arc-shaped wall 823 and the second arc-shaped wall 824, and flows uniformly to the end face of the second aftertreatment carrier assembly 2 through the first air flow penetration holes 825 and the second air flow penetration holes 851.

The above embodiments are only 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 with reference to the above embodiments, the technical personnel in the field 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. A mixing cavity assembly comprises a mixing cavity shell and a mixing tube assembly arranged in the mixing cavity shell, wherein the mixing cavity shell is provided with a first opening communicated with a first post-processing carrier assembly, a second opening communicated with a second post-processing carrier assembly, a first cavity communicated with the first opening and a second cavity communicated with the second opening; the method is characterized in that: the mixing tube assembly comprises a swirl tube located in the first cavity and a connecting tube located in the second cavity; the cyclone tube is provided with a first inner cavity, a plurality of cyclone plates and an airflow inlet corresponding to the cyclone plates, the first inner cavity is communicated with the first cavity through the airflow inlet, the connecting tube is provided with a second inner cavity communicated with the first inner cavity, and the second inner cavity is communicated with the second cavity; mix the pipe assembly and still including being located in first cavity and part surround the arc of spinning disk to make tail gas need walk around the arc just can be certainly air inlet gets into the cyclone tube.

2. The mixing chamber assembly of claim 1, wherein: the cross section of the arc-shaped plate is C-shaped.

3. The mixing chamber assembly of claim 2, wherein: the center pin of arc with the center pin of whirl pipe is parallel, the hybrid chamber subassembly is including being located the arc with the arc air current passageway between the whirl pipe.

4. The mixing chamber assembly of claim 3, wherein: the mixing chamber shell is provided with a mounting seat for mounting a urea nozzle, and the urea nozzle is used for spraying atomized urea liquid drops into the cyclone tube.

5. The mixing chamber assembly of claim 4, wherein: the mixing chamber shell is provided with a first mounting surface which is close to the mounting seat and located on the inner side of the first cavity, one end of the arc-shaped plate is provided with a first mounting claw fixed on the first mounting surface and a slot located beside the first mounting claw, and the slot is communicated with the arc-shaped airflow channel.

6. The mixing chamber assembly of claim 5, wherein: the mixing cavity shell is provided with a partition plate located between the first cavity and the second cavity, and the other end of the arc-shaped plate is provided with a second mounting claw fixed on the partition plate.

7. The mixing chamber assembly of claim 1, wherein: the mixing cavity assembly comprises an end assembly which is positioned in the second cavity and positioned at the bottom of the connecting pipe, and the end assembly comprises a bottom wall, a peripheral wall and a buffer cavity, wherein the peripheral wall extends upwards from the periphery of the bottom wall, and the buffer cavity is enclosed by the bottom wall and the peripheral wall.

8. The mixing chamber assembly of claim 7, wherein: the peripheral wall is provided with a first side wall facing the second aftertreatment carrier assembly, and the first side wall is provided with a plurality of first airflow perforations through which airflow flows.

9. The mixing chamber assembly of claim 1, wherein: mix the pipe assembly including being located first interior cavity with the broken pipe of urea in the cavity in the second, the broken pipe of urea extends along the axial, be equipped with the broken groove of a plurality of urea on the outer wall of the broken pipe of urea, the broken groove of urea is followed axial length is greater than along the perpendicular to axial radial width.

10. An exhaust aftertreatment package comprising a first aftertreatment carrier component, a second aftertreatment carrier component, a third aftertreatment carrier component located upstream of the first aftertreatment carrier component, and a mixing chamber component connecting the first aftertreatment carrier component with the second aftertreatment carrier component, wherein the first aftertreatment carrier component is a diesel particulate trap, the second aftertreatment carrier component is a selective catalytic reduction agent, the third aftertreatment carrier component is a diesel oxidation catalyst, characterized in that: the mixing chamber assembly of any one of claims 1 to 9.