Exhaust pipe integrated SCR mixer and post-processing system

Abstract

The utility model discloses an exhaust pipe integrated type SCR mixer which comprises a front mixing pipe and a rear mixing pipe, a first extension pipe and a second extension pipe are arranged at the front end of the front mixing pipe, a pipe opening of the first extension pipe serves as an air inlet of the mixer, and a nozzle mounting hole is formed in a pipe opening of the second extension pipe and used for mounting a nozzle for spraying a reducing agent. The first extension pipe, the second extension pipe and the front mixing pipe form a Y-shaped structure, the rear end of the front mixing pipe is connected with the front end of the rear mixing pipe, and the rear end of the rear mixing pipe serves as a gas outlet of the mixer. According to the exhaust pipe integrated SCR mixer and the post-processing system, the preceding-stage mixer and the exhaust pipe are integrated, so that the pressure of a compact space can be effectively reduced, meanwhile, the preceding-stage mixer is closer to an outlet of a supercharger, the temperature drop is small, the system can quickly reach the spraying starting temperature of a reducing agent under the low-temperature condition, and the system can quickly reach the spraying starting temperature of the reducing agent. The low-temperature De-Nox conversion capability is improved, and the crystallization resistance of the mixer is improved.

Description

Technical Field

[0001] This utility model relates to the field of vehicle exhaust gas treatment technology, and in particular to after-treatment systems, specifically to an exhaust pipe integrated SCR mixer and after-treatment system. Background Technology

[0002] As domestic diesel vehicle emission regulations continue to be upgraded, stricter requirements are being placed on vehicle exhaust after-treatment systems and their core component, the mixer. As a key component of the after-treatment system, the performance of the mixer directly affects NOx emissions.

[0003] The mixer needs to ensure thorough mixing of exhaust gas and the reducing agent (such as urea solution) to improve the conversion efficiency of the SCR system. The mixer also needs good heat exchange performance to ensure that the urea solution rapidly vaporizes and mixes thoroughly with the exhaust gas during injection, which helps improve the conversion efficiency of the SCR system and reduce urea consumption. Because the "China VI" emission standard imposes stricter emission limits under low-temperature and low-load conditions, and the injection volume is increased, the risk of crystallization in the mixer increases. Excessive crystal formation can clog the aftertreatment channels, leading to increased back pressure in the aftertreatment system, insufficient vehicle power, and the risk of emissions exceeding regulatory limits.

[0004] For diesel engines upgrading to China VII emission standards, a dual urea injection system is one of the key solutions. Compared to China VI aftertreatment systems, this system requires the addition of urea injection at the aftertreatment inlet, as well as a pre-mixer and SCR catalyst, posing significant challenges to the aftertreatment system's capabilities. Utility Model Content

[0005] In view of the shortcomings of the existing technology, this utility model provides an exhaust pipe integrated SCR mixer and aftertreatment system.

[0006] To achieve the above objectives, the first aspect of this utility model provides an exhaust pipe integrated SCR mixer with the following technical solution: it includes a front mixing pipe and a rear mixing pipe, the front end of the front mixing pipe is provided with a first extension pipe and a second extension pipe, the opening of the first extension pipe serves as the air inlet of the mixer, the opening of the second extension pipe is provided with a nozzle mounting hole for installing a nozzle for injecting reducing agent, the first extension pipe, the second extension pipe and the front mixing pipe form a Y-shaped structure, the rear end of the front mixing pipe is connected to the front end of the rear mixing pipe, and the rear end of the rear mixing pipe serves as the air outlet of the mixer.

[0007] Preferably, swirl vanes are provided inside the premixing tube.

[0008] Preferably, the rear end of the post-mixing tube is provided with a flexible tube for connection to the end cap of the SCR.

[0009] Preferably, the inner wall of the front mixing pipe is provided with an arc-shaped baffle.

[0010] Preferably, the central axis of the second extension pipe forms an angle of 0-90 degrees with the central axis of the front mixing pipe, and the central axis of the first extension pipe forms an angle of 0-175 degrees with the central axis of the front mixing pipe.

[0011] The second aspect of the utility model provides a kind of post-processing system, its main feature is, including the exhaust pipe integrated SCR mixer of the described.

[0012] Preferably, the post-processing system includes a pre-processor, a DOC, a DPF, a post-mixer, a post-processor, the inlet of the post-mixer is connected with the DPF, the DOC and the pre-processor in sequence, the outlet of the post-mixer is connected with the post-processor, the exhaust pipe integrated SCR mixer is connected with the end cover of the pre-processor, and the pre-processor and the post-processor are both SCR or ASC.

[0013] The exhaust pipe integrated SCR mixer and the post-processing system can effectively reduce the pressure of the compact space by integrating the front mixer with the exhaust pipe, and the front mixer is closer to the outlet of the supercharger, so that the temperature drop is smaller, which is beneficial to the system to quickly reach the spray temperature of the reducing agent under low temperature conditions, improve the low-temperature De-Nox conversion capacity, and the close proximity to the outlet of the supercharger reduces the temperature drop, which is beneficial to the evaporation of urea and the prevention of crystallization deposition, and improves the anti-crystallization performance of the mixer. BRIEF DESCRIPTION OF DRAWINGS

[0014] To more clearly illustrate the technical scheme in the embodiments of the utility model, the following briefly introduces the drawings needed to be used in the embodiments.

[0015] Figure 1 It is the structural schematic diagram of the post-processing system of the utility model.

[0016] Figure 2 It is the principle schematic diagram of the post-processing system of the utility model.

[0017] Figure 3 It is the structural schematic diagram of the exhaust pipe integrated SCR mixer of the utility model.

[0018] Figure 4 It is the principle schematic diagram of the exhaust pipe integrated SCR mixer of the utility model. DETAILED DESCRIPTION

[0019] In order to more clearly describe the technical content of the utility model, the following further describes in combination with specific embodiments.

[0020] As Figures 1 to 2The specific embodiment of the aftertreatment system is shown in the utility model. The aftertreatment system comprises a preprocessor 4, a DOC 8, a DPF 5, a post-mixer 3, an aftertreatment device 9, the inlet of the post-mixer 3 is sequentially connected with the DPF 5, the DOC 8 and the preprocessor 4, the outlet of the post-mixer 3 is connected with the aftertreatment device 8, and the preprocessor 4 and the aftertreatment device 9 are both SCR or ASC. The aftertreatment system of the utility model is provided with a front-stage mixer, which is an exhaust pipe integrated SCR mixer 1 connected with the end cover of the preprocessor 4.

[0021] The preprocessor 4, the DOC 8, the DPF 5, the post-mixer 3 and the aftertreatment device 9 can be connected through flanges, clamps 6 and welding. The DOC (Diesel Oxidation Catalyst) is a diesel oxidation catalyst, the DPF (Diesel Particulate Filter) is a diesel particulate filter, the SCR (Selective Catalytic Reduction) is a selective catalytic reduction device, and the ASC (Ammonia Slip Catalyst) is an ammonia oxidation catalyst. The DOC, the DPF, the SCR and the ASC all contain catalyst carriers.

[0022] As shown in Figure 2 The exhaust gas enters the aftertreatment system through the gas inlet of the exhaust pipe integrated SCR mixer 1, sequentially passes through two-stage injection, the reducing agent is mixed with the high-temperature exhaust gas in the pipe mixer through the nozzle 2, and the nitrogen oxide and the ammonia gas are reduced under the action of the front-stage SCR catalyst. The reducing agent is mixed with the high-temperature exhaust gas in the post-mixer through the nozzle 7, and the nitrogen oxide and the ammonia gas are reduced under the action of the post-stage SCR catalyst, and the exhaust gas meeting the requirements is discharged.

[0023] As shown in Figure 3 and Figure 4As shown in the figure, the embodiment of the exhaust pipe integrated SCR mixer 1 provided by the utility model. Among them, the exhaust pipe integrated SCR mixer 1 includes the front mixing pipe 18 and the rear mixing pipe 14, the front end of the front mixing pipe 18 is provided with the first extension pipe 19 and the second extension pipe 11, the pipe opening of the first extension pipe 19 is used as the air inlet 16 of the exhaust pipe integrated SCR mixer 1, the pipe opening of the second extension pipe 11 is provided with a nozzle mounting hole for mounting the nozzle 2 for spraying reducing agent, and the nozzle 2 is mounted on the nozzle mounting hole through the nozzle seat 10.The first extension pipe 19, the second extension pipe 11 and the front mixing pipe 18 form a Y-shaped structure, the rear end of the front mixing pipe 18 is connected with the front end of the rear mixing pipe 14, and the rear end of the rear mixing pipe 14 is used as the air outlet of the mixer.The rear end of the rear mixing pipe 14 is provided with a flexible pipe 17 to be connected with the end cover of the SCR to generate a reduction reaction.Through the flexible pipe 17, the exhaust pipe integrated SCR mixer 1 is conveniently mounted on the end cover, mixed gas enters the SCR through the end cover to generate a reduction reaction, and different installation requirements are realized by changing the pipeline direction.

[0024] Therefore, in the mixer of the utility model, the tubular mixer is integrated on the exhaust pipe, the engine exhaust body enters the tubular mixer through the outlet of the supercharger 15, mixes with the reducing agent sprayed by the nozzle and exchanges heat, realizes the national seven double-injection system structure, saves the arrangement space, solves the problem that the space arrangement of the front-stage mixer and the aftertreatment system of the national seven is challenging, the front-stage mixer is closer to the outlet of the engine supercharger 15, the urea spraying temperature can be reached in advance, the De-NOx conversion efficiency is improved, and the requirements of further reducing the nitrogen oxide content and reducing the urea spraying temperature of the national seven are met.

[0025] In the mixer of the utility model, the first extension pipe 19 and the second extension pipe 11 and the front mixing pipe 18 form a Y-shaped structure, wherein the central axis of the second extension pipe 11 and the central axis of the front mixing pipe 18 can form an included angle of 0-90 degrees, and the central axis of the first extension pipe 19 and the central axis of the front mixing pipe 18 can form an included angle of 0-175 degrees.

[0026] As shown in the figure, the front mixing pipe 18 is provided with a cyclone vane 13, so that the gas passing through the cyclone vane forms a cyclone effect, contacts and mixes with the reducing agent sprayed by the nozzle to exchange heat, and evaporates the urea into ammonia gas. Figure 3 The cyclone vane can rotate in the clockwise direction or the counterclockwise direction, and the number of vanes can be 2-30, further enhancing the rotation effect of the high-temperature gas and the reducing agent and enhancing the mixing.

[0027] As shown in the figure, the front mixing pipe 18 is provided with a cyclone vane 13, so that the gas passing through the cyclone vane forms a cyclone effect, contacts and mixes with the reducing agent sprayed by the nozzle to exchange heat, and evaporates the urea into ammonia gas. Figure 3As shown, the inner wall of the front mixing pipe 18 is provided with an arc-shaped baffle 12. The baffle is fixed inside the front mixing pipe and has a gap in the middle. The baffle can effectively smooth the airflow, facilitate the evaporation of urea, avoid the urea from directly colliding with the pipe wall and adhering, reduce the adhesion and deposition of urea, and reduce the risk of crystallization.

[0028] The exhaust pipe integrated SCR mixer 1 of the utility model is also a low-back-pressure mixer, solves the problem of poor engine fuel economy caused by high back pressure of the mixer and the aftertreatment system, has excellent crystallization performance, solves the problem of urea crystallization in the mixer, has low temperature drop, high urea evaporation efficiency, and high De-NOx conversion efficiency.

[0029] The exhaust pipe integrated SCR mixer and the aftertreatment system of the utility model can effectively reduce the pressure of the compact space by integrating the front-stage mixer with the exhaust pipe, the front-stage mixer is closer to the supercharger outlet, the temperature drop is smaller, is beneficial to the system to quickly reach the reducing agent spray temperature under low-temperature conditions, improves the low-temperature De-Nox conversion capacity, and is beneficial to the evaporation of urea and the prevention of crystallization deposition due to the close proximity to the supercharger outlet and the reduced temperature drop, and improves the crystallization resistance of the mixer.

[0030] In this specification, the utility model has been described with reference to its specific embodiments. However, it is obvious that various modifications and changes can still be made without departing from the spirit and scope of the utility model. Therefore, the specification and drawings should be considered as illustrative rather than restrictive.

Claims

1. An exhaust pipe integrated SCR mixer characterized by, The exhaust pipe integrated SCR mixer comprises a front mixing pipe and a rear mixing pipe, a first extension pipe and a second extension pipe are arranged at the front end of the front mixing pipe, the pipe opening of the first extension pipe serves as an air inlet of the mixer, the pipe opening of the second extension pipe is provided with a nozzle mounting hole for mounting a nozzle for spraying a reducing agent, the first extension pipe and the second extension pipe form a Y-shaped structure with the front mixing pipe, the rear end of the front mixing pipe is connected with the front end of the rear mixing pipe, and the rear end of the rear mixing pipe serves as an air outlet of the mixer.

2. The exhaust pipe integrated SCR mixer of claim 1, wherein, The front mixing pipe is provided with a rotational flow vane.

3. The exhaust pipe integrated SCR mixer of claim 1, wherein, The rear end of the rear mixing pipe is provided with a flexible pipe for connecting with an end cover of an SCR.

4. The exhaust pipe integrated SCR mixer of claim 1, wherein, The inner wall of the front mixing pipe is provided with an arc-shaped baffle.

5. The exhaust pipe integrated SCR mixer of claim 1, wherein, The central axis of the second extension pipe forms an angle of 0-90 degrees with the central axis of the front mixing pipe, and the central axis of the first extension pipe forms an angle of 0-175 degrees with the central axis of the front mixing pipe.

6. An aftertreatment system characterized by, The exhaust pipe integrated SCR mixer comprises any one of claims 1-5.

7. The aftertreatment system of claim 6, wherein, The aftertreatment system comprises a pre-treater, a DOC, a DPF, a rear mixer, an after-treater, the inlet of the rear mixer is connected with the DPF, the DOC and the pre-treater in sequence, the outlet of the rear mixer is connected with the after-treater, the exhaust pipe integrated SCR mixer is connected with an end cover of the pre-treater, and the pre-treater and the after-treater are both SCR or ASC.

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