WO2019019723A1

WO2019019723A1 - Engine exhaust after-treatment package and application thereof

Info

Publication number: WO2019019723A1
Application number: PCT/CN2018/084366
Authority: WO
Inventors: 李军良; 王天宇
Original assignee: 天纳克（苏州）排放系统有限公司
Priority date: 2017-07-27
Filing date: 2018-04-25
Publication date: 2019-01-31
Also published as: CN107178413A

Abstract

Provided is an engine exhaust after-treatment package (100), comprising a first after-treatment assembly (1), a first cavity assembly (2) located downstream of the first after-treatment assembly (1), and a mixing pipe (5) in communication with the first cavity assembly (2), wherein the mixing pipe (5) comprises a first mixer (51) and a mounting base (53) for mounting a urea nozzle. The engine exhaust after-treatment package (100) further comprises a fine fiber element (6) located in the mixing pipe (5), wherein the fine fiber element (6) is used for exhaust gas and urea droplets to pass through same, so as to further break up and evaporate the urea droplets. Application of the fine fiber element (6) in the engine exhaust after-treatment package (100) is further provided. With such an arrangement, the engine exhaust after-treatment package achieves a relatively strong crystallization resistance capability.

Description

Engine exhaust aftertreatment package and application

The present application claims the priority of the Chinese patent application filed on July 27, 2017, the application number of which is hereby incorporated by reference. .

Technical field

The invention relates to an engine exhaust aftertreatment package and application, and belongs to the technical field of engine exhaust aftertreatment.

Background technique

Mixer metal structures are currently used in the industry to achieve the mixing of urea droplets and exhaust gases. Generally, a structure such as a perforated plate, a fin, or the like is disposed in the mixer, and the urea droplet collides with the mixer of the metal structure to break the urea droplet into smaller droplets to facilitate evaporation and pyrolysis on the metal surface. . The current situation is due to the escalation of emission regulations, making the current urea injection strategy more aggressive, such as starting a larger urea injection volume at lower temperatures and smaller exhaust flow rates. There is a relationship between heat conservation, one is the heat required for evaporation and pyrolysis of urea droplets, and the other is the heat from the upstream. Due to the radicalization of the above-described injection strategy, the ratio between the total heat carried by the exhaust gas and the heat required for the urea solution to fully evaporate and pyrolyze is continuously reduced. The industry uses a ratio called EER to describe the relationship between this heat. In general, the crystallization risk of a mixer with an EER value above 150 is extremely low. If the EER is not that high, but if the structure of the mixer is optimized, its anti-crystallization ability will be improved. This is also the research and development direction of most companies in the industry, namely how to optimize the structural design of the mixer.

Referring to Figures 1 and 2, a perforated plate 1' is provided in the mixer 3'. The perforated plate 1' is provided with a plurality of openings 2' through which a mixture of exhaust gas and urea droplets is passed. On the one hand, the urea droplets hitting the orifice plate 1' facilitate the crushing thereof to obtain a smaller volume of urea droplets, thereby facilitating its evaporation and pyrolysis. On the other hand, in order to ensure that the perforated plate 1' has sufficient mechanical strength, the material portion between the openings 2' is unavoidable. It can be understood that on the back side of the perforated plate 1', the flow velocity of the gas flow is relatively low, and it is easy to form a local low velocity region M. Both theoretical and experimental results demonstrate that the possibility of urea crystallization occurring in the low velocity zone M is extremely high.

Therefore, it is necessary to provide a new type of solution to solve the above technical problems.

Summary of the invention

It is an object of the present invention to provide an engine exhaust aftertreatment package that is more resistant to crystallization and to the use of a fine fiber component in the engine exhaust aftertreatment package.

To achieve the above object, the present invention adopts the following technical solution: an engine exhaust aftertreatment package including a first aftertreatment component located downstream of the first aftertreatment component and in communication with the first aftertreatment component a first cavity assembly, and a mixing tube in communication with the first cavity assembly, wherein the mixing tube includes a first mixer and a mount for mounting a urea nozzle, the urea nozzle for A mixer sprays atomized urea droplets, the first mixer comprising a plurality of sheets disposed in a stack, the engine exhaust aftertreatment package further comprising a fine fiber element located in the mixing tube, the fine fibers An element is located downstream of the first mixer, wherein the fine fiber element is used to pass the exhaust gas and the urea droplets to further increase fragmentation and evaporation of the urea droplets.

As a further improved technical solution of the present invention, each of the plates is provided with an inclined portion that extends obliquely downstream of the exhaust direction.

As a further improvement of the technical solution of the present invention, at least one of the plurality of plates is longer than the other plates, and the plate is stamped to form a plurality of protrusions and a notch corresponding to the protrusions.

As a further improved technical solution of the present invention, the mixing tube is provided with a bulge on which the mounting seat is located.

As a further improved technical solution of the present invention, the mixing tube includes a second mixer located downstream of the first mixer, and the fine fiber element is located downstream of the second mixer.

As a further improved technical solution of the present invention, the fine fiber element is steel wool or foam metal.

As a further improved technical solution of the present invention, the engine exhaust aftertreatment package is provided with a plurality of fixing bars for fixing the fine fiber elements.

As a further improved technical solution of the present invention, the engine exhaust aftertreatment package further includes a second aftertreatment component disposed side by side with the first aftertreatment component and a second cavity located upstream of the second aftertreatment component a body assembly, the mixing tube being coupled between the first cavity assembly and the second cavity assembly; the first aftertreatment component and the second aftertreatment component being coupled by the first cavity The assembly, the mixing tube, and the second cavity assembly are connected in series.

As a further improved technical solution of the present invention, the first aftertreatment component comprises a diesel oxidation catalyst and/or a diesel particulate trap, and the second aftertreatment component comprises a selective catalytic reducing agent.

The invention further relates to the use of a fine fiber element in the above described engine exhaust aftertreatment package.

Compared with the prior art, the present invention allows the urea droplets to be sufficiently broken and mixed on the surface and inside of the fine fiber member by providing the fine fiber member. In addition, due to the small wire diameter of the fine fiber element, the void is complicated, and the heat transfer area is large, which is beneficial to the full heat exchange between the urea droplets and the exhaust gas, thereby facilitating evaporation and pyrolysis of the urea droplets, and improving the anti-crystallization. ability.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic cross-sectional view showing the addition of a perforated plate in a mixing tube in the prior art.

Figure 2 is a schematic cross-sectional view of the perforated plate of Figure 1 with the flow direction of the mixture of exhaust gas and urea droplets and the dead zone on the back side.

3 is a perspective view of the engine exhaust aftertreatment package of the present invention.

Fig. 4 is a partially exploded perspective view of Fig. 3;

Figure 5 is a further exploded perspective view of Figure 4.

Figure 6 is a perspective view of the mixing tube of Figure 5.

Figure 7 is a left side view of Figure 6.

Figure 8 is a right side view of Figure 6.

Figure 9 is a schematic cross-sectional view taken along line A-A of Figure 7.

Figure 10 is a schematic cross-sectional view taken along line B-B of Figure 7.

Figure 11 is an exploded perspective view of the mixing tube of Figure 6.

Detailed ways

Referring to Figures 3 through 11, the present invention discloses an engine exhaust aftertreatment package 100 for use in an aftertreatment system such as an SCR to treat the exhaust of the engine. In the illustrated embodiment of the present invention, the engine exhaust aftertreatment package 100 includes a first aftertreatment component 1 , a first cavity component 2 in communication with the first aftertreatment component 1 , and the first a second aftertreatment assembly 3 in which the aftertreatment assembly 1 is arranged side by side, a second cavity assembly 4 in communication with the second aftertreatment assembly 3, and a mixing tube that communicates the first and

second cavity assemblies

2, 4 5. The first aftertreatment component 1 and the second aftertreatment component 3 are connected in series by the first and

second cavity components

2, 4 and the mixing tube 5.

In the illustrated embodiment of the present invention, the first aftertreatment assembly 1 includes a first housing 11, a second housing 12, and an oxidation type catalytic converter (DOC) installed in the first housing 11. a particulate trap (DPF) installed in the second casing 12, and an exhaust inlet 15 upstream of the oxidizing catalytic converter. Wherein the oxidizing catalytic converter is located upstream of the particle trap to provide a suitable temperature when the particulate trap is regenerated.

In the illustrated embodiment of the present invention, the second aftertreatment assembly 3 includes a third housing 31, a selective catalytic reducing agent (SCR) installed in the third housing 31, and the selective An exhaust outlet 33 downstream of the catalytic reducing agent.

In the illustrated embodiment of the invention, the first cavity assembly 2 and the second cavity assembly 4 are substantially identical in shape. The first cavity assembly 2 is for directing exhaust gas from the first aftertreatment assembly 1 to the mixing tube 5. The second cavity assembly 4 shares the third housing 31 with the second aftertreatment assembly 3.

The mixing tube 5 includes a first mixer 51, a second mixer 52 located downstream of the first mixer 51, and a mount 53 for mounting a urea nozzle (not shown). The urea nozzle is for injecting atomized urea droplets to the first mixer 51.

The first mixer 51 includes a plurality of sheets 511 stacked in a stack, and each of the sheets 511 is provided with an inclined portion 512 that extends obliquely downstream of the exhaust direction. At least one of the plurality of plates 511 is longer than the other plates, and the plate is stamped to form a plurality of protrusions 513 and a notch 514 corresponding to the protrusions to facilitate the breakage of the urea particles.

The mixing tube 5 is provided with a ridge 54 on which the mounting seat 53 is located.

In the illustrated embodiment of the invention, by providing a two-stage mixer, the mixing distance is increased, reducing the risk of urea crystallization. Of course, in other embodiments it is also possible to provide only one mixer.

The engine exhaust aftertreatment package 100 further includes a fine fiber element 6 located in the mixing tube 5, wherein the fine fiber element 6 is used to pass the exhaust gas and the urea droplets to further increase The urea droplets are broken and evaporated. In the illustrated embodiment of the invention, the fine fiber element 6 is steel wool or foam metal, and the fine fiber element 6 is located downstream of the second mixer 52. The engine exhaust aftertreatment package 100 is provided with a plurality of fixing bars 7 that fix the fine fiber elements 6. Of course, in other embodiments, the fine fiber element 6 may also be a mesh steel wire or a ceramic porous material or the like.

The present invention utilizes a 3D porous structure or a multi-voided structure of a fine fiber element 6 (e.g., steel wool), the exhaust gas and the urea droplets pass through the fine fiber element 6, so that the urea droplets are sufficiently formed on the surface and inside of the steel wool. Broken and mixed. In addition, the steel wool has a small wire diameter, a complicated void, and a large specific surface area. Because of its large specific surface area, it can create a larger heat exchange area in a limited space, which is beneficial to the full heat exchange between urea droplets and exhaust gas, which facilitates evaporation and pyrolysis of urea droplets and improves resistance to crystallization. ability. The back pressure of the system can be adjusted accordingly by adjusting the density of the fine fiber element 6.

Compared with the structures of the porous tube and the fins in the prior art, the wire diameter of the fine fiber element 6 of the present invention is very small (for example, less than 1 mm), so that the occurrence of the leeward side can be avoided, thereby reducing the risk of urea crystallization. The pioneering invention of the present invention solves both the problem of the low speed zone and the heat exchange problem, with outstanding substantial features and significant progress.

In addition, the above embodiments are only for illustrating the present invention and are not intended to limit the technical solutions described in the present invention. The understanding of the present specification should be based on those skilled in the art, although the present specification has been carried out with reference to the above embodiments. DETAILED DESCRIPTION OF THE INVENTION However, those skilled in the art should understand that the invention may be modified or equivalently replaced by those skilled in the art without departing from the spirit and scope of the invention. It is intended to be included within the scope of the appended claims.

Claims

An engine exhaust aftertreatment package including a first aftertreatment component, a first cavity component downstream of the first aftertreatment component and in communication with the first aftertreatment component, and the first a mixing tube in communication with the cavity assembly, wherein the mixing tube includes a first mixer and a mount for mounting a urea nozzle, the urea nozzle for injecting atomized urea droplets to the first mixer The first mixer comprises a plurality of sheets arranged in a stack, characterized in that the engine exhaust aftertreatment package further comprises a fine fiber element located in the mixing tube, the fine fiber element being located in the first mixer Downstream, wherein the fine fiber element is used to pass the exhaust gas and the urea droplets to further increase the fracture and evaporation of the urea droplets.
The engine exhaust aftertreatment package according to claim 1, wherein each of the plates is provided with an inclined portion that extends obliquely downstream of the exhaust direction.
The engine exhaust aftertreatment package of claim 1 wherein at least one of said plurality of sheets is longer than the other sheets, said sheet being stamped to form a plurality of raised portions and corresponding to said raised portions. gap.
The engine exhaust aftertreatment package of claim 1 wherein said mixing tube is provided with a ridge portion, said mounting seat being located on said ridge portion.
The engine exhaust aftertreatment package of claim 1 wherein said mixing tube comprises a second mixer downstream of said first mixer, said fine fiber element being located in said second mixer Downstream.
The engine exhaust aftertreatment package of claim 1 wherein said fine fiber component is steel wool or metal foam.
The engine exhaust aftertreatment package of claim 1 wherein said engine exhaust aftertreatment package is provided with a plurality of fixed bars that secure said fine fiber elements.
The engine exhaust aftertreatment package of claim 1 wherein said engine exhaust aftertreatment package further comprises a second aftertreatment component disposed side by side with said first aftertreatment component and at said second a second cavity assembly upstream of the aftertreatment assembly, the mixing tube being coupled between the first cavity component and the second cavity component; the first aftertreatment component and the second post process The assembly is connected in series by the first cavity assembly, the mixing tube, and the second cavity assembly.
The engine exhaust aftertreatment package of claim 8 wherein said first aftertreatment component comprises a diesel oxidation catalyst and/or a diesel particulate trap, said second aftertreatment component comprising a selective catalytic reduction Agent.
A use of a fine fiber element in an engine exhaust aftertreatment package, characterized in that the engine exhaust aftertreatment package is the engine exhaust aftertreatment package of any one of claims 1 to 8.