A post-processing package

Abstract

This application relates to a post-treatment package, comprising: a DOC unit, a DPF particulate filter unit, a mixer unit, and an SCR unit connected sequentially along the exhaust flow direction; wherein, the mixer unit includes: a mixer cylinder and a swirl assembly, the mixer cylinder is provided with a nozzle seat, a mixing chamber is formed inside the mixer cylinder, the mixing chamber is divided into an upper layer, a middle layer, and a lower layer, the upper layer, the middle layer, and the lower layer are interconnected, one end of the mixer cylinder is a mixer inlet, and the other end is a mixer outlet; the swirl assembly is disposed inside the mixing chamber and divides the mixer inlet into a first inlet and a second inlet, the first inlet and the second inlet are spaced apart, the first inlet is connected to the upper layer, the second inlet is connected to the lower layer, and the upper layer, the middle layer, and the lower layer are all connected to the mixer outlet. In this invention, the upper airflow carrying urea and the lower airflow form a countercurrent in the middle layer, promoting the breakup and evaporation of urea droplets, accelerating the uniformity of ammonia mixing, and reducing the formation of urea crystals.

Description

Technical Field

[0001] This application relates to the field of engine exhaust purification, and in particular to an aftertreatment package. Background Technology

[0002] Selective catalytic reduction (SCR) technology refers to the use of ammonia, ammonia water, urea or hydrocarbons as reducing agents to selectively reduce NOx to N2 under conditions where the oxygen concentration is more than two orders of magnitude higher than the NOx concentration, thereby achieving the treatment of exhaust gas to meet the China VI emission standards.

[0003] The mixer unit, located in the diesel engine aftertreatment system before the SCR catalyst, promotes the breakup and evaporation of urea droplets and the conversion of urea to ammonia. The SCR mixer unit improves the uniformity of NH3 concentration at the SCR catalyst inlet and exhaust velocity. Incomplete breakup and evaporation of urea droplets leads to a decrease in NOx conversion rate and the formation of urea crystals that clog the internal structure. Uneven distribution of ammonia concentration and exhaust velocity also reduces NOx conversion efficiency and causes uneven catalyst aging, affecting the performance of the SCR catalyst. Existing mixer designs generally suffer from simple structures, poor urea solution breakup and evaporation, and a tendency to form urea crystals. Summary of the Invention

[0004] This application provides a post-processing packaging method to solve the problems of urea solution breakage, poor evaporation, and easy formation of urea crystals in related technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a post-treatment package comprising: a DOC unit, a DPF particulate filter unit, a mixer unit, and an SCR unit connected sequentially along the direction of exhaust flow; wherein, the mixer unit comprises: a mixer cylinder and a swirl assembly, the mixer cylinder being provided with a nozzle seat, a mixing chamber being formed within the mixer cylinder, one end of the mixer cylinder being a mixer inlet, and the other end being a mixer outlet; the swirl assembly being disposed inside the mixing chamber, the swirl assembly dividing the mixer inlet into a first inlet and a second inlet, and dividing the mixing chamber into an upper layer, a middle layer, and a lower layer, the upper layer, the middle layer, and the lower layer being interconnected, a gap being present between the first inlet and the second inlet, the first inlet being connected to the upper layer, the second inlet being connected to the lower layer, and the upper layer, the middle layer, and the lower layer all being connected to the mixer outlet; the mixer unit is configured such that the airflow entering the upper layer from the first inlet and the airflow entering the lower layer from the second inlet flow in opposite directions, forming a countercurrent in the middle layer, and flowing out from the mixer outlet.

[0006] In some embodiments, the swirl assembly includes: a rectifier, a mixer swirl unit, and a flow-blocking structure. The rectifier is disposed at the mixer inlet to divide the mixer inlet into a first inlet and a second inlet. The mixer swirl unit includes a first mixing element and a second mixing element, which are respectively disposed in the upper and lower layers. Swirl holes are formed on the surfaces of both the first and second mixing elements. The flow-blocking structure is disposed outside the mixer swirl unit and has an arc-shaped inner surface for changing the airflow direction.

[0007] In some embodiments, the rectifier is a cylindrical structure and is sealed on the inlet side of the mixer. The top and bottom ends of the rectifier and the outlet side of the mixer are provided with openings. The top and bottom ends of the rectifier are respectively connected to the first mixer and the second mixer.

[0008] In some embodiments, the height of the rectifier gradually decreases from the center of the rectifier to the edge of the rectifier.

[0009] In some embodiments, the flow-guiding structure includes: a first flow-guiding structure and a second flow-guiding structure, the inner surface including a first inner surface disposed on the first flow-guiding structure, the first flow-guiding structure being sleeved on the outside of the first mixing component, and a gap between the first inner surface and the outer surface of the first mixing component, the first flow-guiding structure having a first opening, the first opening being at least partially located at the first inlet; the inner surface also includes a second inner surface disposed on the second flow-guiding structure, the second flow-guiding structure being sleeved on the outside of the second mixing component, the second inner surface being at least partially located at the second inlet, the first opening and the second opening having opposite orientations.

[0010] In some embodiments, the gap between the first inner surface and the outer surface of the first mixture gradually decreases from one end of the first opening to the other end; and the gap between the second inner surface and the outer surface of the second mixture gradually decreases from one end of the second opening to the other end.

[0011] In some embodiments, the isolation and flow guiding structure further includes a third flow guiding structure, which is connected between the first and second flow guiding structures and has an "S" shape, and forms a flow guiding port on the isolation and flow guiding structure, the flow guiding port being connected to the mixer outlet.

[0012] In some embodiments, guide plates are fixedly connected to the inner walls of both the first and second mixing components. The guide plates are located on one side of the swirling holes, and are inclined to form a swirling channel with the swirling holes. The guide plates on the first mixing component and the guide plates on the second mixing component have different inclination directions.

[0013] In some embodiments, the mixer unit further includes:

[0014] A swirl plate is disposed inside the mixing chamber and located at the mixer outlet. A guide hole is provided on the swirl plate near its edge.

[0015] In some embodiments, the middle portion of the swirl plate near the mixer inlet protrudes toward the SCR unit.

[0016] The beneficial effects of the technical solution provided in this application include:

[0017] This application provides a post-processing encapsulation system consisting of a mixer cylinder and a swirl assembly that work together to split the exhaust gas flow into two opposing airflows, with the upper and lower airflows flowing in opposite directions. Urea is injected into the upper airflow through a nozzle seat, and the upper and lower airflows carrying urea form a countercurrent in the middle layer. This bidirectional countercurrent airflow promotes the breakup and evaporation of urea droplets, accelerates the uniformity of ammonia mixing, and reduces the formation of urea crystals. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of this application;

[0020] Figure 2 This is a schematic diagram of airflow provided in an embodiment of this application;

[0021] Figure 3 This is a schematic diagram of the mixer unit structure provided in an embodiment of this application;

[0022] Figure 4 for Figure 3 Sectional view of AA;

[0023] Figure 5 A top view of the mixer unit provided in an embodiment of this application;

[0024] Figure 6 for Figure 5 BB section view;

[0025] Figure 7 This is a schematic diagram of the mixer unit structure provided in an embodiment of this application;

[0026] Figure 8 This is a schematic diagram of the swirl assembly structure provided in an embodiment of this application;

[0027] Figure 9 A schematic diagram of a first type of mixer swirl unit provided in the embodiments of this application;

[0028] Figure 10 This is a schematic diagram of the rectifier structure provided in an embodiment of this application;

[0029] Figure 11 This is a schematic diagram of the partition and flow guiding structure provided in the embodiments of this application;

[0030] Figure 12 This is a schematic diagram of the swirl plate structure provided in an embodiment of this application;

[0031] Figure 13 A schematic diagram of a second type of mixer swirl unit provided in an embodiment of this application;

[0032] Figure 14 This is a schematic diagram of the outer cylinder and swirl plate structure provided in an embodiment of this application.

[0033] In the diagram: 1. DOC unit;

[0034] 2. DPF particulate filter unit;

[0035] 3. Mixer unit; 31. Mixer cylinder; 310. Flanged edge; 311. Nozzle seat; 312. Outer cylinder; 313. Upper layer; 314. Middle layer; 315. Lower layer; 32. Swirl assembly; 320. Mixer swirl unit; 3200. Swirl orifice; 3201. Guide plate; 3202. First mixing component; 3203. Second mixing component; 321. Rectifier; 322. Isolation guide structure; 3220. First guide structure; 3221. Second guide structure; 3222. Third guide structure; 3223. Inner surface; 3224. Guide port; 33. Swirl plate; 330. Guide hole;

[0036] 4. Urea nozzle;

[0037] 5. SCR unit;

[0038] 6. Clamps. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] See Figures 1 to 14 This application provides a post-processing packaging method that can solve the problems of urea solution breakage, poor evaporation, and easy formation of urea crystals in related technologies.

[0041] Selective catalytic reduction (SCR) technology refers to the use of ammonia, ammonia water, urea or hydrocarbons as reducing agents to selectively reduce NOx to N2 under conditions where the oxygen concentration is more than two orders of magnitude higher than the NOx concentration, thereby achieving the treatment of exhaust gas to meet the China VI emission standards.

[0042] Mixer unit 3 is located in the diesel engine aftertreatment system, before the SCR catalyst, and is used to promote the breakup and evaporation of urea droplets and the conversion of urea to ammonia. SCR mixer unit 3 is used to improve the uniformity of NH3 concentration at the SCR catalyst inlet and exhaust velocity. Incomplete breakup and evaporation of urea droplets will lead to a decrease in NOx conversion rate and the formation of urea crystals that clog the internal structure. Uneven distribution of ammonia concentration and exhaust velocity will also reduce NOx conversion efficiency and cause uneven catalyst aging, affecting the performance of the SCR catalyst. Existing mixer designs generally suffer from simple structures, poor urea solution breakup and evaporation, and a tendency to form urea crystals.

[0043] To address the problems of urea solution breakage, poor evaporation, and easy formation of urea crystals, this application provides a post-treatment package, which includes: a DOC unit 1, a DPF particulate filter unit 2, a mixer unit 3, and an SCR unit 5 connected sequentially along the exhaust flow direction; wherein, the mixer unit 3 includes: a mixer cylinder 31 and a swirl assembly 32, the mixer cylinder 31 is provided with a nozzle seat 311, a mixing chamber is formed inside the mixer cylinder 31, one end of the mixer cylinder 31 is the mixer inlet, and the other end is the mixer outlet; the swirl assembly 32 is disposed inside the mixing chamber, and the swirl assembly 32... The mixer inlet is divided into a first inlet and a second inlet, and the mixing chamber is divided into an upper layer 313, a middle layer 314 and a lower layer 315. The upper layer 313, the middle layer 314 and the lower layer 315 are interconnected. There is a gap between the first inlet and the second inlet. The first inlet is connected to the upper layer 313 and the second inlet is connected to the lower layer 315. The upper layer 313, the middle layer 314 and the lower layer 315 are all connected to the mixer outlet. The mixer unit 3 is configured such that the airflow entering the upper layer 313 from the first inlet and the airflow entering the lower layer 315 from the second inlet flow in opposite directions and form a countercurrent in the middle layer 314, and flow out from the mixer outlet.

[0044] The DOC unit 1, DPF particle collection unit, mixer unit 3, and SCR unit 5 are cylindrical in shape. The DOC unit 1 and the DPF particle collection unit are connected by a clamp 6, the DPF particle collection unit and the mixer unit 3 are connected by a clamp 6, and the mixer unit 3 and the SCR unit 5 are connected by a clamp 6.

[0045] The exhaust flow direction and urea mixing process are as follows: The exhaust gas flow first flows through DOC unit 1 and DPF particulate filter unit 2 before entering mixer unit 3. When the exhaust gas flow enters the mixer unit 3, the swirl assembly 32 and mixer cylinder 31 work together to split the airflow into two opposing airflows. The swirl assembly 32 promotes the rotation of the airflow. The opposing flow means that the upper layer 313 airflow rotates clockwise and the lower layer 315 airflow rotates counterclockwise, or the upper layer 313 airflow rotates counterclockwise and the lower layer 315 airflow rotates clockwise. Urea is injected into the upper layer 313 airflow through nozzle seat 311. In the middle layer 314, the rotating airflow of the upper layer 313 carrying urea forms an opposition with the rotating airflow of the lower layer 315. Then, it flows into SCR unit 5 from the mixer outlet and finally flows out through SCR unit 5.

[0046] In this application, a spatial structure is utilized to form a counter-current airflow field that facilitates the rapid breakup, evaporation, hydrolysis, and uniform distribution of the urea solution. This promotes the breakup and evaporation of urea droplets and the conversion of urea to ammonia, reducing the risk of urea crystallization. It also achieves a uniform distribution of ammonia concentration and exhaust velocity at the inlet of the SCR unit 5 and reduces the overall back pressure of the mixer unit 3. Specifically, in this application, the mixer cylinder 31 and the swirl assembly 32 work together to divide the exhaust airflow into two opposing airflows, with the upper layer 313 airflow and the lower layer 315 airflow flowing in opposite directions. Urea is injected into the upper layer 313 airflow through the nozzle seat 311. The urea-laden upper layer 313 airflow and the lower layer 315 airflow form a counter-current in the middle layer 314. This bidirectional counter-current airflow promotes the breakup and evaporation of urea droplets, accelerates ammonia mixing uniformity, and reduces urea crystal formation.

[0047] The mixer body 31 includes an outer cylinder 312, and a mixing chamber is formed inside the outer cylinder 312. A nozzle seat 311 is provided at the top of the outer cylinder 312 to connect the inside and outside of the outer cylinder 312. A urea nozzle 4 is fixed on the nozzle seat 311. Urea enters the outside of the outer cylinder 312 through the urea nozzle 4. Mixer body flanges 310 are fixed on both sides of the outer cylinder 312. The mixer body flanges 310 can be connected to the outer cylinder 312 by welding or can be integrally formed with the outer cylinder 312.

[0048] Based on the above embodiments, in this embodiment, the swirl assembly 32 includes: a rectifier 321, a mixer swirl unit 320, and a flow-blocking structure 322. The rectifier 321 is disposed at the mixer inlet to divide the mixer inlet into a first inlet and a second inlet. The mixer swirl unit 320 includes a first mixer 3202 and a second mixer 3203, which are respectively disposed inside the upper layer 313 and the lower layer 315. Swirl holes 3200 are provided on the surfaces of the first mixer 3202 and the second mixer 3203. The flow-blocking structure 322 is disposed outside the mixer swirl unit 320, and the flow-blocking structure 322 is provided with an arc-shaped inner surface 3223 for changing the airflow direction.

[0049] Specifically, the rectifier 321 is disposed between the first mixer 3202 and the second mixer 3203. The rectifier 321, together with the first mixer 3202 and the second mixer 3203, divides the mixing cavity into an upper layer 313, a middle layer 314 and a lower layer 315. The first mixer 3202 is located in the upper layer 313, the rectifier 321 is located in the middle layer 314, and the second mixer 3203 is located in the lower layer 315.

[0050] The first mixing component 3202 and the second mixing component 3203 have the same structure and are symmetrically arranged relative to the middle layer 314. Since the first mixing component 3202 and the second mixing component 3203 have the same structure, the description here will focus on the first mixing component 3202, and will not elaborate on the second mixing component 3203: The first mixing component 3202 has a cylindrical structure with openings at both the top and bottom. The nozzle seat 311 is located at the top opening of the first mixing component 3202, and swirling holes 3200 are formed on the surface of the first mixing component 3202. The top of the first mixing component 3202 is attached to and welded to the top of the inner wall of the mixing chamber, and the bottom of the second mixing component 3203 is attached to and welded to the bottom of the inner wall of the mixing chamber. The first mixing element 3202 is disposed in the upper layer 313, and the second mixing element 3203 is disposed in the lower layer 315. Part of the airflow from the DPF particulate trap unit 2 enters the upper layer 313 through the first inlet, and then enters the middle layer 314 through the swirl hole 3200 of the first mixing element 3202 and the bottom opening of the first mixing element 3202. The other part enters the lower layer 315 through the second inlet, and then enters the middle layer 314 through the swirl hole 3200 of the second mixing element 3203 and the top opening of the second mixing element 3203, thus counteracting the airflow in the upper layer 313.

[0051] To provide sufficient mixing space, the rectifier 321 is designed as a cylindrical structure. The rectifier 321 is sealed on the inlet side of the mixer, and openings are provided at its top, bottom, and outlet sides. The top and bottom of the rectifier 321 are connected to the first mixer 3202 and the second mixer 3203, respectively. Specifically, the top of the rectifier 321 is welded to the first mixer 3202, and the opening at the top of the rectifier 321 connects to the opening at the bottom of the first mixer 3202. The bottom of the rectifier 321 is welded to the second mixer 3203, and the opening at the bottom of the rectifier 321 connects to the opening at the top of the second mixer 3203. Therefore, a portion of the airflow enters the cavity of the rectifier 321 through the bottom opening of the first mixer 3202 and the top opening of the rectifier 321, while another portion of the airflow enters the cavity of the rectifier 321 through the top opening of the second mixer 3203 and the bottom opening of the rectifier 321, and then flows out through the opening of the rectifier 321 on the side of the mixer outlet.

[0052] Furthermore, from the center of the rectifier 321 to its edge, the height of the rectifier 321 gradually decreases, that is, the rectifier 321 has a flat design, providing sufficient anti-mixing space to promote the mixing of urea and exhaust gas, achieve the goal of ammonia uniformity and reduce urea crystallization, while the flat space increases the airflow space and reduces airflow pressure loss.

[0053] To facilitate the formation of swirling airflows entering the upper layer 313 and the lower layer 315, a flow-guiding structure 322 is provided, comprising a first flow-guiding structure 3220 and a second flow-guiding structure 3221. The inner surface 3223 includes a first inner surface disposed on the first flow-guiding structure 3220, which is fitted over the first mixing component 3202, with a gap between the first inner surface and the outer surface of the first mixing component 3202. The first flow-guiding structure 3220 has a first opening, at least partially located at the first inlet. The inner surface 3223 also includes a second inner surface disposed on the second flow-guiding structure 3221, which is fitted over the second mixing component 3203, with a gap between the second inner surface and the outer surface of the second mixing component 3203. The second flow-guiding structure 3221 has a second opening, at least partially located at the second inlet, with the first and second openings facing opposite directions.

[0054] Taking the upper 313 airflow rotating clockwise and the lower 315 airflow rotating counterclockwise as an example:

[0055] Specifically, such as Figure 8 and Figure 11 As shown, the first flow guiding structure 3220 covers the outside of the first mixing component 3202 and has a gap between it and the outer surface of the first mixing component 3202. The first opening faces forward, and a part of the first opening is located at the first inlet. The arc-shaped first inner surface on the first flow guiding structure 3220 is used to change the direction of airflow. Therefore, the airflow entering from the first inlet enters the first mixing component 3202 through the uncovered swirling hole 3200 at the first opening, and then flows out from the swirling hole 3200 away from the first inlet. Due to the obstruction of the first guide structure 3220, the airflow between the first mixing component 3202 and the first guide structure 3220 re-enters the first mixing component 3202 through the swirling hole 3200, and then flows into the rectifier 321 through the bottom opening of the first mixing component 3202. A portion of the airflow enters from the gap between the first mixing component 3202 and the first guide structure 3220, flows into the first mixing component 3202 away from the first opening, and enters the first mixing component 3202 through the swirling hole 3200 there, and then flows into the rectifier 321 through the bottom opening of the first mixing component 3202. Since the first opening faces forward, the airflow rotates clockwise.

[0056] The second flow guide structure 3221 covers the outside of the second mixing component 3203 and has a gap between it and the outer surface of the second mixing component 3203. The second opening faces backward and a part of the second opening is located at the second inlet. The arc-shaped second inner surface on the second flow guide structure 3221 is used to change the direction of airflow. Therefore, the airflow entering from the second inlet enters the second mixing component 3203 through the uncovered swirling hole 3200 at the second opening, and then flows out from the swirling hole 3200 on the second mixing component 3203 away from the second inlet. Due to the obstruction of the second guide structure 3221, the airflow located between the second mixing component 3203 and the second guide structure 3221 re-enters the second mixing component 3203 through the swirling hole 3200, and then flows into the rectifier 321 through the bottom opening of the second mixing component 3203. A portion of the airflow enters from the gap between the second mixing component 3203 and the second guide structure 3221, flows into the second mixing component 3203 away from the second opening, and enters the second mixing component 3203 through the swirling hole 3200 there, and then flows into the rectifier 321 through the top opening of the second mixing component 3203. Because the second opening faces rearward, the airflow rotates counterclockwise.

[0057] The airflow in the upper layer 313 rotates clockwise, and the airflow in the lower layer 315 rotates counterclockwise. The first mixing component 3202 and the second mixing component 3203, together with the first guide structure 3220 and the second guide structure 3221, promote the rotation of the airflow.

[0058] The structure of the swirl holes 3200 on the first mixing component 3202 and the second mixing component 3203 is not limited, and can be square holes, circular holes, elliptical holes, or irregularly shaped holes, etc. In order to guide the airflow, guide plates 3201 are fixedly connected to the inner walls of both the first mixing component 3202 and the second mixing component 3203. The guide plates 3201 are located on one side of the swirl holes 3200, and the guide plates 3201 are inclined and form a swirl channel with the swirl holes 3200. The guide plates 3201 on the first mixing component 3202 and the guide plates 3201 on the second mixing component 3203 have different inclination directions. Specifically, when the upper layer 313 airflow rotates clockwise, one end of the guide plate 3201 located inside the first mixing component 3202 is fixed to the inner wall of the first mixing component 3202 and is disposed on one side of the swirling hole 3200, while the other end is inclined clockwise toward the side of the swirling hole 3200 adjacent to the swirling hole 3200; when the lower layer 315 airflow rotates counterclockwise, one end of the guide plate 3201 located inside the second mixing component 3203 is fixed to the inner wall of the second mixing component 3203 and is disposed on one side of the swirling hole 3200, while the other end is inclined counterclockwise toward the side of the swirling hole 3200 adjacent to the swirling hole 3200.

[0059] like Figure 8As shown, further, from one end of the first opening to the other end, the gap between the first inner surface and the outer surface of the first mixing component 3202 gradually decreases; from one end of the second opening to the other end, the gap between the second inner surface and the outer surface of the second mixing component 3203 gradually decreases. Here, one end of the first opening is the airflow inlet, and one end of the second opening is also the airflow inlet. Because the gap between the first inner surface and the outer surface of the first mixing component 3202 gradually decreases, and the gap between the second inner surface and the outer surface of the second mixing component 3203 gradually decreases, the airflow passes through the first mixing component 3202 or the second mixing component 3203 evenly, thereby making the airflow more balanced, achieving uniform mixing of urea and exhaust gas, and reducing the formation of urea crystals.

[0060] In the above embodiments, the first flow guiding structure 3220 and the second flow guiding structure 3221 are separate. Alternatively, based on the above embodiments, in this embodiment, the isolation flow guiding structure 322 further includes a third flow guiding structure 3222, which is connected between the first flow guiding structure 3220 and the second flow guiding structure 3221 and has an "S" shaped structure. A flow guiding port 3224 is formed on the isolation flow guiding structure 322, and the flow guiding port 3224 is connected to the mixer outlet.

[0061] Specifically, the top of the first flow guiding structure 3220 is welded to the inner wall of the outer cylinder 312, and the bottom is welded to the top of the rectifier 321; the bottom of the second flow guiding structure 3221 is welded to the inner wall of the outer cylinder 312, and the top is welded to the bottom of the rectifier 321. In addition to welding, the mixer swirl unit 320, the rectifier 321, and the isolation flow guiding structure 322 can also be connected by riveting, screwing, snap-fitting, or clamping.

[0062] In this embodiment, the first flow guide structure 3220 and the second flow guide structure 3221 are connected by the third flow guide structure 3222, making the isolation flow guide structure 322 an integral structure for easy installation. After the third flow guide structure 3222 is connected to the first flow guide structure 3220 and the second flow guide structure 3221, the isolation flow guide structure 322 is S-shaped. The third flow guide structure 3222 avoids the opening of the rectifier 321 on the mixer outlet side, forming a guide port 3224, so that the airflow from the rectifier 321 flows through the guide port 3224 and then flows out from the mixer outlet.

[0063] Based on the above embodiments, in this embodiment, the mixer unit 3 further includes a swirl plate 33, which is disposed inside the mixing chamber and located at the mixer outlet. A guide hole 330 is provided on the swirl plate 33 near its edge.

[0064] Specifically, the guide hole 330 can be set as a semi-circle, and a connector is provided on the side of the swirl plate 33 near the mixer outlet. The connector covers one side of the guide hole 330, forming a "dumpling" structure with the guide hole 330. After the airflow passes through the "dumpling" structure, it forms a swirling flow and enters the SCR unit 5, achieving uniform ammonia distribution and reducing urea crystallization. At the same time, the middle part of the swirl plate 33 near the mixer inlet protrudes towards the SCR unit 5, cooperating with the swirl assembly 32 to effectively alleviate and disperse the airflow, while adjusting the airflow direction so that the airflow flowing towards the middle part is dispersed to the guide hole 330 opened near the edge of the swirl plate 33, promoting the mixing of urea and exhaust gas, achieving the goal of uniform ammonia distribution, and reducing urea crystallization.

[0065] Therefore, the mixing chamber is divided into two independent components along the airflow direction: one is the swirl assembly 32, and the other is the swirl plate 33. The two components are independent of each other, which increases the flexibility of the arrangement.

[0066] The exhaust gas flow first passes through DOC unit 1 and DPF particulate filter unit 2, then enters mixer unit 3, and finally exits through SCR unit 5.

[0067] When the exhaust airflow enters the mixer unit 3, the swirl assembly 32 and the mixer cylinder 31 work together to split the airflow into two opposing airflows. The upper airflow 313 rotates clockwise, and the lower airflow 315 rotates counterclockwise. The swirl assembly 320 in the mixer promotes the rotation of the airflow. Urea is injected into the upper airflow 313. Inside the rectifier 321, the clockwise rotating airflow of the upper airflow 313 containing urea and the counterclockwise rotating airflow of the lower airflow 315 form an opposition. The subsequent exhaust airflow flows out of the rectifier 321 and flows to the middle part of the swirl plate 33. It works with the rectifier 321 to effectively alleviate and disperse the airflow. Since the swirl plate 33 has a "dumpling" structure guide hole 330 on its side, the airflow forms a swirl after passing through the "dumpling" structure guide structure and enters the SCR unit 5.

[0068] Therefore, this application utilizes the mixer cylinder 31 and the swirl assembly 32 to split, swirl, and counter-current the exhaust gas, promoting the crushing, evaporation, and mixing of urea. Finally, through the specially shaped swirl plate 33, the atomized urea droplets are fully mixed with the airflow, resulting in good uniform ammonia distribution.

[0069] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and 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 of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0070] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0071] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A post-processing packaging, characterized in that, It includes: The DOC unit (1), DPF particulate filter unit (2), mixer unit (3) and SCR unit (5) are connected sequentially along the direction of exhaust flow. The mixer unit (3) includes: - Mixer cylinder (31), on which a nozzle seat (311) is provided, and a mixing chamber is formed inside the mixer cylinder (31). One end of the mixer cylinder (31) is the mixer inlet, and the other end is the mixer outlet; - Swirl assembly (32), the swirl assembly (32) is disposed inside the mixing chamber, the swirl assembly (32) divides the mixer inlet into a first inlet and a second inlet, and divides the mixing chamber into an upper layer (313), a middle layer (314) and a lower layer (315), the upper layer (313), the middle layer (314) and the lower layer (315) are interconnected, there is a gap between the first inlet and the second inlet, the first inlet is connected to the upper layer (313), the second inlet is connected to the lower layer (315), and the upper layer (313), the middle layer (314) and the lower layer (315) are all connected to the mixer outlet; The mixer unit (3) is configured such that the airflow entering the upper layer (313) from the first inlet and the airflow entering the lower layer (315) from the second inlet flow in opposite directions and form a counterflow in the middle layer (314) before flowing out from the mixer outlet; The swirl assembly (32) includes: A rectifier (321) is disposed at the mixer inlet to divide the mixer inlet into a first inlet and a second inlet; The mixer swirl unit (320) includes a first mixing element (3202) and a second mixing element (3203). The first mixing element (3202) and the second mixing element (3203) are respectively disposed inside the upper layer (313) and the lower layer (315). Swirl holes (3200) are opened on the surface of the first mixing element (3202) and the second mixing element (3203). A flow-guiding structure (322) is provided outside the swirl unit (320) of the mixer. The flow-guiding structure (322) has an arc-shaped inner surface (3223) for changing the direction of airflow. The flow-guiding structure (322) includes: The first flow guiding structure (3220) has an inner surface (3223) including a first inner surface disposed on the first flow guiding structure (3220). The first flow guiding structure (3220) is sleeved on the outside of the first mixing component (3202), and there is a gap between the first inner surface and the outer surface of the first mixing component (3202). The first flow guiding structure (3220) has a first opening, and the first opening is at least partially located at the first inlet. The second flow guiding structure (3221) and the inner surface (3223) further include a second inner surface disposed on the second flow guiding structure (3221). The second flow guiding structure (3221) is sleeved on the outside of the second mixing component (3203), and there is a gap between the second inner surface and the outer surface of the second mixing component (3203). The second flow guiding structure (3221) has a second opening, which is at least partially located at the second inlet. The first opening and the second opening face opposite directions. The flow-guiding structure (322) further includes: The third flow guide structure (3222) is connected between the first flow guide structure (3220) and the second flow guide structure (3221) and has an "S" shaped structure. A flow guide port (3224) is formed on the partition flow guide structure (322), and the flow guide port (3224) is connected to the mixer outlet. The inner walls of the first mixing component (3202) and the second mixing component (3203) are both fixedly connected with guide plates (3201). The guide plates (3201) are located on one side of the swirling hole (3200). The guide plates (3201) are inclined and form a swirling channel with the swirling hole (3200). The guide plates (3201) on the first mixing component (3202) and the guide plates (3201) on the second mixing component (3203) have different inclination directions.

2. The post-processing packaging as described in claim 1, characterized in that: The rectifier (321) is a cylindrical structure and is sealed on the inlet side of the mixer. The top and bottom of the rectifier (321) and the outlet side of the mixer are all provided with openings. The top and bottom of the rectifier (321) are respectively connected to the first mixer (3202) and the second mixer (3203).

3. The post-processing packaging as described in claim 2, characterized in that: The height of the rectifier (321) gradually decreases from the center to the edge of the rectifier (321).

4. The post-processing packaging as described in claim 1, characterized in that: From one end of the first opening to the other end of the first opening, the gap between the first inner surface and the outer surface of the first mixing component (3202) gradually decreases; From one end of the second opening to the other end of the second opening, the gap between the second inner surface and the outer surface of the second mixing element (3203) gradually decreases.

5. The post-processing packaging as described in claim 1, characterized in that, The mixer unit (3) further includes: Swirl plate (33) is disposed inside the mixing chamber and located at the mixer outlet. A guide hole (330) is provided on the swirl plate (33) near the edge.

6. The post-processing packaging as described in claim 5, characterized in that: The middle portion of the swirl plate (33) near the mixer inlet protrudes toward the SCR unit (5).

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