A tail gas aftertreatment close-coupled diffusion cyclonic concha mixer

Abstract

The present application belongs to the field of diesel engine exhaust aftertreatment technology, and particularly relates to a tail gas aftertreatment close-coupled diffusion type cyclone shell mixer. The air inlet end of the mixer is connected with the air outlet end of a DOC assembly, and the air outlet end is connected with the air inlet end of an SDPF assembly. The DOC assembly and the SDPF assembly are arranged in a double "V" shape as a whole. A nozzle assembly is arranged on the mixer, which comprises a nozzle base and a nozzle mounted on the nozzle base. The nozzle is in communication with the inside of the mixer. A front breaking diffusion guide plate and a rear cyclone plate are arranged in the mixer in sequence along the air flow direction. The front breaking diffusion guide plate is provided with breaking guide fins and pressure relief holes, and the rear cyclone plate is provided with guide openings. The mixer of the present application can be arranged in a three-dimensional "V" shaped compact twisted space. The diffusion type baffle structure in the mixer can match the breaking of various types of urea atomized droplets, and at the same time, the diffusion is guided to the outer layer, thereby reducing the risk of urea crystallization and increasing the flow mixing distance.

Description

Technical Field

[0001] This invention belongs to the field of diesel engine exhaust aftertreatment technology, specifically relating to an exhaust aftertreatment tightly coupled diffusion vortex shell mixer. Background Technology

[0002] In recent years, with government incentives, entrepreneurship has been on the rise, leading to a year-on-year increase in sales of light-duty commercial vehicles—mini-trucks / pickups. At the same time, the space available for after-processors in these small diesel vehicles is being continuously reduced.

[0003] The current mainstream approach is to directly install the aftertreatment system (EDS) inside the engine compartment and coat the SCR catalyst onto the wall-flow particulate filter (DPF), thus forming the SDPF. This tightly coupled SDPF not only improves thermal efficiency for NOx reduction during cold starts but also increases the overall SCR volume, further reducing catalyst support and encapsulation costs. However, because the SDPF simultaneously contains both the NOx-removing SCR reaction and the passive regeneration reaction for soot removal, these competing reactions accelerate carbon buildup in the SDPF, leading to a faster increase in back pressure, increased active regeneration frequency, and exacerbated aging issues.

[0004] Therefore, for mixers designed to match this type of lightweight, tightly coupled post-processor, they not only need to be placed in a compact, twisted space, but also need to possess the following capabilities:

[0005] 1. The ability to break down urea droplets;

[0006] 2. The ability to decompose urea crystals;

[0007] 3. The mixing capacity of ammonia;

[0008] 4. Mixing ability of carbon soot solid particles;

[0009] 5. Mixing capacity of exhaust temperature.

[0010] Existing technologies only utilize structural decomposition and mixing within a compact space. The path is short, the decomposition is incomplete, and it is easy to aggregate and form urea crystals. The mixing capacity is limited. At the same time, the differences in physical properties of exhaust gas, urea droplets, and soot solid particles are not fully considered, and they are not treated separately. As a result, they are only superior in one aspect and cannot simultaneously possess the above five capabilities. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a tightly coupled diffusion-type swirl-shell mixer for exhaust gas aftertreatment. This mixer can be arranged in a compact, three-dimensional "V"-shaped twisted space. The diffuser baffle structure within the mixer can match the breakup of various urea atomized droplets, while simultaneously guiding the flow to the outer layer, reducing the risk of urea crystallization, increasing the flow mixing distance, and cohesive mixing with the downstream swirl structure, further improving exhaust temperature and the mixing of ammonia and soot particles.

[0012] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows:

[0013] A tightly coupled diffusion swirl-shell mixer for exhaust gas aftertreatment, wherein the inlet end of the mixer is connected to the outlet end of the DOC component, and the outlet end of the mixer is connected to the inlet end of the SDPF component, and the DOC component and SDPF component are arranged in a double "V" shape.

[0014] The mixer is provided with a nozzle assembly, which includes a nozzle base and a nozzle mounted on the nozzle base, and the nozzle communicates with the interior of the mixer.

[0015] Inside the mixer, a front-mounted break-diffusion guide plate and a rear-mounted swirl plate are arranged sequentially along the airflow direction. The front-mounted break-diffusion guide plate is provided with break-diffusion guide fins and pressure relief holes, and the rear-mounted swirl plate is provided with a guide opening.

[0016] Furthermore, the mixer includes an upper shell and a lower shell, the bottom ends of the front breaking and diffusing guide plate and the rear swirl plate are connected to the lower shell, and the top ends of the front breaking and diffusing guide plate and the rear swirl plate are connected to the upper shell.

[0017] Furthermore, the pre-crushing diffusion guide plate is arc-shaped, with a central angle ε of 45-75°, determined based on the outer cylinder profile of the DOC assembly and the inner profile of the mixer.

[0018] Furthermore, the distribution angle γ of the breaking guide fins on the front breaking diffuser plate is adapted to the atomization cone angle of the nozzle, and the opening angle δ of the breaking guide fins is 15°-30°.

[0019] Furthermore, the breaking guide fins are disposed in the middle part of the front breaking diffuser plate, and the pressure relief holes are distributed on the outer periphery of the breaking guide fins.

[0020] Furthermore, the flow guide opening is cat ear-shaped, the bottom surface of the flow guide opening is a quarter ellipse, the central ridge is involute, the angle λ between the starting line of the ridge and the outlet edge is 30-60°, and the inward rotation angle θ of the outlet edge is 10-20°.

[0021] Furthermore, a large opening is provided in the middle of the rear swirl plate, and the flow guide opening is arranged around the large opening on the periphery of the rear swirl plate. The ratio of the total area of ​​the large opening to the flow guide opening is 0.8-1.

[0022] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0023] (1) The mixer of the present invention is in a three-dimensional “V” shape (the angles formed by the axis of the DOC component and the axis of the SDPF component in different view directions are α and β respectively), which can be arranged in a compact twisted space and improve the thermal efficiency of the engine to facilitate NOx emission reduction under cold start.

[0024] (2) The mixer of the present invention has a simple structure, few internal components, and is easy to manufacture.

[0025] (3) The mixer structure of the present invention has multiple pressure relief holes, resulting in low back pressure and easy reduction of oil consumption.

[0026] (4) The pre-combustion diffusion guide plate in the mixer of the present invention has a pre-combustion diffusion guide plate with a pre-combustion diffusion guide plate arranged according to the number of nozzle holes to force the crushed urea particles to move outward, which can not only reduce the aggregation of urea crystals, but also increase the urea decomposition diffusion path. In addition, especially for four-hole nozzles, due to the superposition of four atomizing cone angles, the cross-section of the cone angle is easily rectangular, and the distribution angle γ of the pre-combustion diffusion guide plate is adapted to the atomizing cone angle of the nozzle. In addition, the pre-combustion diffusion guide plate is arc-shaped, which makes it easy to match and install with the DOC end cylinder.

[0027] (5) The mixer of the present invention has a rear swirl plate with cat-ear-shaped guide openings around its periphery and an involute central ridge, which can maximize the use of space to increase the guide area. Because the cat-ear openings taper inward at an angle θ, they work in conjunction with the urea particles diffused to the periphery from the upstream, making the entire urea flow path exhibit a dispersion-aggregation trend. This maximizes the flow path and improves the mixing capacity. In addition, the large opening in the middle can drive the exhaust gas to enter from the middle of the SDPF, avoiding the failure problem caused by the mainstream being off-center; at the same time, the temperature deviation on the SDPF is smaller, so as to reduce the risk of accelerated aging due to temperature accumulation during regeneration and soot removal.

[0028] (6) The mixer of the present invention not only utilizes the axial direction of the path, but also fully acts in the radial direction, which extends the path and expands the crushing, decomposition and mixing capacity. At the same time, considering the differences in physical properties, it performs diversion treatment for exhaust gas, urea droplets and carbon soot solid particles, thus comprehensively improving the performance of the mixer. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the exhaust gas aftertreatment tightly coupled diffusion vortex shell mixer in an embodiment of the present invention.

[0030] Figure 2 yes Figure 1 Schematic diagram of the double "V" shaped structure angle of the tightly coupled diffusion vortex shell mixer for mid-stage exhaust gas aftertreatment.

[0031] Figure 3 yes Figure 1 A schematic diagram of the exploded structure of a tightly coupled diffusion vortex-shell mixer for mid-stage exhaust gas aftertreatment.

[0032] Figure 4 yes Figure 1 Cross-sectional view of a tightly coupled diffusion vortex-shell mixer for mid-stage exhaust gas aftertreatment.

[0033] Figure 5 yes Figure 1 An exploded view of the application of a tightly coupled diffusion vortex-shell mixer in the mid-stage exhaust gas aftertreatment system.

[0034] Figure 6 yes Figure 1 A schematic diagram of the structure of the pre-crushing diffusion guide plate in the tightly coupled diffusion vortex shell mixer for exhaust gas aftertreatment.

[0035] 6A is a top view of the front-mounted crushing and diffusion guide plate; 6B is a front view of the front-mounted crushing and diffusion guide plate.

[0036] Figure 7 yes Figure 1 Schematic diagram of the application principle of the pre-crushing diffusion guide plate in the tightly coupled diffusion vortex shell mixer for exhaust gas aftertreatment.

[0037] 7A is the diagram showing the direction of urea entering the broken guide fins; 7B and 7C are the atomization cone angles ζ and η of the four-hole nozzle.

[0038] Figure 8 yes Figure 1 Schematic diagram of the application principle of the post-swirling plate in the tightly coupled diffusion swirling shell mixer for exhaust gas aftertreatment.

[0039] 8A is a diagram showing the flow path of urea in the guide opening; 8B is a diagram showing the flow path of urea in the large opening.

[0040] Explanation of reference numerals in the attached drawings: 1-DOC assembly; 2-nozzle assembly; 3-mixing device; 4-SDPF assembly; 2-1-nozzle; 2-2-nozzle base; 2-3-urea atomizing cone angle; 3-1-upper shell; 3-2-lower shell; 3-3-front crushing and diffusion guide plate; 3-4-rear swirl plate; 3-3-1-crushing guide fins; 3-3-2-pressure relief hole; 3-4-1-guide opening; 3-4-2-large opening. Detailed Implementation

[0041] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "inner" and "outer", "upper" and "lower", "left" and "right" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention.

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] Example 1

[0044] like Figure 1-3 As shown, a tightly coupled diffusion swirl-shell mixer for exhaust gas aftertreatment is provided. The inlet end of the mixer 3 is connected to the outlet end of the DOC component 1, and the outlet end of the mixer 3 is connected to the inlet end of the SDPF component 4. The DOC component 1 and the SDPF component 4 are arranged in a double "V" shape.

[0045] like Figure 2 As shown in Figure A, from the main view of the tightly coupled diffusion vortex-shell mixer for exhaust gas aftertreatment, the angle formed by the axis of DOC component 1 and the axis of SDPF component 4 is α, where 30°≤α≤75°.

[0046] like Figure 2 As shown in Figure B, from the top view of the tightly coupled diffusion swirl-shell mixer for exhaust gas aftertreatment, the angle formed by the axis of DOC component 1 and the axis of SDPF component 4 is β, 0°≤β≤45°; the above double “V” shaped arrangement structure allows the mixer to adapt to more compact and complex arrangement spaces.

[0047] The mixer 3 is provided with a nozzle assembly 2, which includes a nozzle base 2-2 and a nozzle 2-1 mounted on the nozzle base 2-2. The nozzle 2-1 is in communication with the interior of the mixer 3.

[0048] Inside the mixer 3, a front-mounted crushing and diffusion guide plate 3-3 and a rear-mounted swirl plate 3-4 are arranged sequentially along the airflow direction. The front-mounted crushing and diffusion guide plate 3-3 is provided with crushing guide fins 3-3-1 and pressure relief holes 3-3-2, and the rear-mounted swirl plate 3-4 is provided with a guide opening 3-4-1.

[0049] Opening a pressure relief hole 3-3-2 on the front-mounted crushing and diffusion guide plate 3-3 can reduce back pressure. The hole diameter can be adjusted according to the back pressure requirements.

[0050] like Figure 4 and 5 As shown, the mixer 3 includes an upper shell 3-1 and a lower shell 3-2. The bottom ends of the front crushing and diffusion guide plate 3-3 and the rear swirl plate 3-4 are connected to the lower shell 3-2, and the top ends of the front crushing and diffusion guide plate 3-3 and the rear swirl plate 3-4 are connected to the upper shell 3-1.

[0051] The pre-crushing diffusion guide plate 3-3 is arc-shaped with a central angle ε of 45-75°. ε is determined based on the outer cylinder profile of DOC component 1 and the inner profile of mixer 3, and the mixing chamber is filled as much as possible.

[0052] The crushing guide fin 3-3-1 is located at the wall contact position of the nozzle 2-1 on the front crushing diffuser guide plate 3-3.

[0053] like Figure 6 and 7 As shown, taking the four-hole nozzle 2-1 as an example, the distribution angle γ of the breaking guide fin 3-3-1 is set according to the atomization cone angle ζ&η of the nozzle 2-1, and the opening angle δ of the breaking guide fin 3-3-1 is 15°-30°, so that the urea atomized droplets are guided to the periphery of the mixing chamber as much as possible.

[0054] The distribution angle γ of the break-through guide fin 3-3-1 represents the angle between the axis of the break-through guide fin 3-3-1 and the horizontal line. The break-through guide fin 3-3-1 is arranged in a symmetrical manner.

[0055] To demonstrate the advantages of this invention, a four-hole nozzle is used as an example for description, such as... Figure 4 and 5 As shown, the four injection holes of nozzle 2-1 are arranged in a rectangular pattern. After urea is injected from the four-hole nozzle, the atomized urea particles form a cone shape, creating a urea atomization cone angle 2-3. Projecting the atomized cone shape from two different perspectives yields two angles, ζ and η, as shown. Figure 7 As shown.

[0056] like Figure 8As shown, the flow guide opening 3-4-1 is cat ear-shaped, the bottom surface of the flow guide opening 3-4-1 is a quarter ellipse, the central ridge is involute, the angle λ between the starting line of the ridge and the outlet edge is 30-60°, and the inward rotation angle θ of the outlet edge is 10-20°.

[0057] A large opening 3-4-2 is provided in the middle part of the rear swirl plate 3-4, and a flow guide opening 3-4-1 is arranged around the large opening 3-4-2 on the periphery of the rear swirl plate 3-4. The ratio of the total area of ​​the large opening 3-4-2 to the flow guide opening 3-4-1 is 0.8-1.

[0058] The installation process of mixer 3 is as follows: First, weld the bottom ends of the front crushing and diffusion guide plate 3-3 and the rear swirl plate 3-4 to the lower shell 3-2. Then, weld the upper shell 3-1 to the lower shell 3-2. From the gas outlet side, weld the other side of the rear swirl plate 3-4 to the upper shell 3-1 to form the entire mixing chamber.

[0059] The work process is as follows Figure 4 and 5 As shown, after the exhaust gas enters the mixer 3 from the DOC assembly 1, part of the airflow carrying soot directly passes through the pressure relief hole 3-3-2 on the lower shell 3-3, while the other part of the exhaust gas carrying ejected urea droplets interacts with the breaking guide fins 3-3-1. The urea droplets are broken down by impacting the wall and are also guided to move towards the periphery of the mixing chamber. At the same time, the soot solid particles, being heavier, are also deflected outwards. Then, the droplets that have moved to the periphery and have not been broken down continue to fall along the wall of the mixing chamber onto the guide opening 3-4-1 of the rear swirl plate 3-4. They are further broken down by the guide opening 3-4-1 and are also swirled inwards by the guide opening 3-4-1. Furthermore, because the rear swirl plate 3-4 has a large opening 3-4-2 in the middle, some soot solid particles will enter the SDPF assembly 4 through the large opening 3-4-2, while the other part will swirl in through the guide opening 3-4-1. Throughout the process, the urea droplets exhibit a dispersion-aggregation flow path, maximizing the flow path and enhancing mixing capacity. Simultaneously, the movement process involves two stages of breakup and decomposition, making urea less prone to deposition. Furthermore, the exhaust gas and soot are diverted to the SDPF module 4 more evenly, resulting in more stable and reliable regeneration.

[0060] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A tightly coupled diffusion-type vortex-shell mixer for exhaust gas aftertreatment, characterized in that, The air inlet of the mixer (3) is connected to the air outlet of the DOC assembly (1), and the air outlet of the mixer (3) is connected to the air inlet of the SDPF assembly (4). The DOC assembly (1) and the SDPF assembly (4) are arranged in a double "V" shape. The mixer (3) is provided with a nozzle assembly (2), the nozzle assembly (2) includes a nozzle base (2-2) and a nozzle (2-1) installed on the nozzle base (2-2), the nozzle (2-1) being in communication with the interior of the mixer (3); The mixer (3) is provided with a front breaking and diffusion guide plate (3-3) and a rear swirl plate (3-4) in sequence along the airflow direction. The front breaking and diffusion guide plate (3-3) is provided with breaking guide fins (3-3-1) and pressure relief holes (3-3-2). The rear swirl plate (3-4) is provided with a guide opening (3-4-1). The distribution angle γ of the crushing guide fins (3-3-1) on the front crushing diffuser plate (3-3) is adapted to the atomizing cone angle of the nozzle (2-1), and the opening angle δ of the crushing guide fins (3-3-1) is 15°-30°. The crushing guide fin (3-3-1) is located in the middle part of the front crushing diffuser plate (3-3), and the pressure relief hole (3-3-2) is distributed on the outer periphery of the crushing guide fin (3-3-1).

2. The exhaust gas aftertreatment tightly coupled diffusion vortex-shell mixer according to claim 1, characterized in that, The mixer (3) includes an upper shell (3-1) and a lower shell (3-2). The bottom ends of the front crushing and diffusion guide plate (3-3) and the rear swirl plate (3-4) are connected to the lower shell (3-2), and the top ends of the front crushing and diffusion guide plate (3-3) and the rear swirl plate (3-4) are connected to the upper shell (3-1).

3. The exhaust gas aftertreatment tightly coupled diffusion vortex-shell mixer according to claim 1, characterized in that, The pre-crushing diffusion guide plate (3-3) is arc-shaped, and the central angle ε of the arc is 45-75°, which is determined according to the outer cylinder outline of the DOC component (1) and the inner outline of the mixer (3).

4. The exhaust gas aftertreatment tightly coupled diffusion vortex-shell mixer according to claim 1, characterized in that, The flow guide opening (3-4-1) is cat ear-shaped. The bottom surface of the flow guide opening (3-4-1) is a quarter ellipse. The central ridge is in the form of an involute. The angle λ between the starting line of the ridge and the outlet edge is 30-60°. The inward rotation angle θ of the outlet edge is 10-20°.

5. The exhaust gas aftertreatment tightly coupled diffusion vortex-shell mixer according to claim 1 or 4, characterized in that, The rear swirl plate (3-4) has a large opening (3-4-2) in the middle part, and the flow guide opening (3-4-1) is arranged around the large opening (3-4-2) on the periphery of the rear swirl plate (3-4). The ratio of the total area of ​​the large opening (3-4-2) to the flow guide opening (3-4-1) is 0.8-1.

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