Mixing pipe assembly, mixer and exhaust aftertreatment system

Abstract

The utility model relates to a mixing pipe component, including outer rotational flow pipe, inner rotational flow pipe, mixing outer layer pipe, mixing middle layer pipe and mixing inner layer pipe, the inside of mixing inner layer pipe forms first mixing chamber, mixing inner layer pipe and mixing middle layer pipe form second mixing chamber, mixing middle layer pipe and mixing outer layer pipe form third mixing chamber, mixing inner layer pipe and mixing middle layer pipe form second mixing chamber, mixing inner layer pipe and mixing middle layer pipe form second mixing chamber, mixing middle layer pipe and mixing outer layer pipe form third mixing chamber, mixing inner layer pipe and mixing middle layer pipe form second mixing chamber. The pipe wall of the outer cyclone pipe is provided with an outer cyclone window which is used as a gas inlet, the pipe wall of the inner cyclone pipe is provided with an inner cyclone window, the top end of the outer cyclone pipe and the top end of the inner cyclone pipe are each provided with a first pipe jacking opening, and the first pipe jacking openings are used for allowing a reducing agent to flow in; and a second pipe jacking opening is formed in the top end of the mixing inner-layer pipe, and mixed gas of gas and a reducing agent flows into the second pipe jacking opening. The utility model further provides a corresponding mixer and an exhaust aftertreatment system, airflow distribution and back pressure can be effectively adjusted, the mixing efficiency of urea and waste gas is improved, urea consumption is reduced, and crystallization is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas treatment, in particular to a mixing tube assembly, a mixer and an exhaust gas after-treatment system. Background Art

[0002] The mixer is a key component of the exhaust after-treatment system, directly impacting NOx emissions. Due to the continuous upgrading of relevant domestic regulations, the performance requirements for mixers are becoming increasingly stringent. On the one hand, to maximize the conversion efficiency of the SCR system, exhaust gas and reducing agent (such as urea-water solution) must be thoroughly mixed in the mixer. On the other hand, to reduce urea consumption, the mixer must have good heat exchange performance to ensure that the urea-water solution can be quickly vaporized during injection and fully mixed with the exhaust gas.

[0003] Furthermore, current exhaust after-treatment systems face an increased risk of crystallization in the mixer. This is primarily due to the stricter emission limits set by the China VI standard under low-temperature and low-load conditions. This increased injection volume leads to significant crystallization. This increased crystallization can clog the after-treatment channels, increasing backpressure in the after-treatment system and causing vehicle power loss. This also creates the risk of emissions exceeding regulatory limits.

[0004] In general, the main technical difficulties of the current exhaust after-treatment system are:

[0005] 1) High back pressure in the after-treatment system leads to poor engine fuel economy;

[0006] 2) Urea crystallization in the mixer;

[0007] 3) The mixing efficiency of urea and exhaust gas is low, and the De-NOx conversion efficiency is low.

[0008] Therefore, it is hoped that the existing exhaust after-treatment system can be improved to solve the above-mentioned major technical difficulties at the same time. Utility Model Content

[0009] In view of the deficiencies of the existing prior art, the utility model provides a mixing tube assembly, a mixer and an exhaust after-treatment system.

[0010] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a mixing tube assembly, which has the following technical solutions: comprising an outer vortex tube, an inner vortex tube, a mixing outer layer tube, a mixing middle layer tube and a mixing inner layer tube, the inner vortex tube is located in the outer vortex tube, the mixing middle layer tube is located in the mixing outer layer tube, the mixing inner layer tube is located in the mixing middle layer tube, the outer vortex tube is connected to the top end of the mixing outer layer tube, the inner vortex tube is connected to the top end of the mixing middle layer tube, and the interior of the mixing inner layer tube forms a first A mixing chamber, a second mixing chamber is formed between the mixing inner layer tube and the mixing middle layer tube, a third mixing chamber is formed between the mixing middle layer tube and the mixing outer layer tube, an outer vortex window is provided on the tube wall of the outer vortex tube, and the outer vortex window is used for the inlet of gas, an inner vortex window is provided on the tube wall of the inner vortex tube, a first top pipe opening is provided on the top of the outer vortex tube and the inner vortex tube, and the first top pipe opening is used for the inflow of reducing agent, a second top pipe opening is provided on the top of the mixing inner layer tube, and the second top pipe opening is used for the inflow of a mixed gas of gas and reducing agent.

[0011] Preferably, the wall of the mixed inner layer tube is provided with a plurality of grooves, and the wall of the mixed middle layer tube is provided with a plurality of first openings.

[0012] Preferably, the slot is a slot-shaped opening, and the first opening is a circular hole-shaped opening.

[0013] Preferably, both the outer swirl window and the inner swirl window are provided with swirl sheets.

[0014] Preferably, the bottom ends of the outer mixing tube, the middle mixing tube and the inner mixing tube all have bottom tube openings, and the lower tube wall of the outer mixing tube is provided with several second openings, and each bottom tube opening and the second opening serve as a mixed gas outflow outlet of the mixing tube assembly.

[0015] Preferably, the second opening is a circular hole.

[0016] Preferably, the mixing tube assembly includes an arc plate arranged at each bottom pipe port, and at least one side of the arc plate has a concave channel, so that the mixed gas flowing out from each bottom pipe port flows out through the concave channel.

[0017] The second aspect of the present invention provides a mixer, which mainly comprises an outer shell, a sealing plate, a nozzle, and a mixing tube assembly. The outer shell and the sealing plate surround a mixing chamber, the mixing chamber is provided with a baffle, and the baffle separates the mixing chamber into an upper chamber and a lower chamber. The sealing plate is provided with an air inlet corresponding to the upper chamber and an air outlet corresponding to the lower chamber. The mixing tube assembly extends downward from the upper chamber and passes through the baffle to the lower chamber. The outer swirl window of the outer swirl tube is located in the upper chamber, and the nozzle is installed on the first top pipe opening.

[0018] The third aspect of the present invention provides an exhaust gas after-treatment system, the main feature of which is that it includes the mixer.

[0019] Preferably, the system includes a DOC and an air intake subassembly, a DPF subassembly, an SCR and an air outlet subassembly, the DOC and air intake subassembly, the DPF subassembly and the air inlet of the mixer are connected, the DPF subassembly is located between the DOC and air intake subassembly and the air inlet of the mixer, and the SCR and air outlet subassembly are connected to the air outlet of the mixer.

[0020] The mixing tube assembly, mixer and exhaust gas after-treatment system of the present invention can effectively adjust the airflow distribution and back pressure, improve the mixing efficiency of urea and exhaust gas, reduce urea consumption and reduce crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments.

[0022] Figure 1 It is a schematic structural diagram of the exhaust gas after-treatment system of the present utility model.

[0023] Figure 2 This is a simplified diagram of the principle of the exhaust after-treatment system of the present utility model.

[0024] Figure 3 This is a schematic structural diagram of the mixer of the present invention.

[0025] Figure 4 This is a schematic diagram illustrating the working principle of the mixer of the present invention.

[0026] Figure 5 This is an exploded schematic diagram of the mixer of the present invention.

[0027] Figures 6A to 6C This is a schematic structural diagram of a mixing tube assembly in a mixer of the present invention.

[0028] Figure 7This is a schematic diagram illustrating the working principle of the mixing tube assembly in the mixer of the present invention.

[0029] Reference numerals

[0030] 1DOC and intake sub-assembly; 2DPF sub-assembly; 3Mixer; 4Clamp; 5SCR and exhaust sub-assembly; 6Strap bracket; 7Reductant nozzle; 9Mixer tube assembly; 901External swirl tube; 902Outer mixing tube; 903Inner swirl tube; 904Middle mixing tube; 905Inner mixing tube; 10Heat shield; 11Insulation cotton; 12Outer shell; 13Baffle; 14Arm plate; 15Seal plate; 16Nozzle mounting seat; 17Nozzle seat seal plate. DETAILED DESCRIPTION

[0031] In order to more clearly describe the technical content of the present invention, it is further described below in conjunction with specific embodiments.

[0032] like Figures 1 to 5 The figure shows a specific embodiment of the exhaust after-treatment system of the present invention. The exhaust after-treatment system includes the mixer 3, a DOC and an air intake subassembly 1, a DPF subassembly 2, an SCR and an air outlet subassembly 5. The DOC (Diesel Oxidation Catalyst) is a diesel oxidation catalyst, the DPF (Diesel Particulate Filter) is a diesel particulate filter, and the SCR (Selective Catalytic Reduction) is a selective catalytic reduction device. The DOC, DPF, and SCR subassemblies all contain catalyst carriers. The DOC and air intake subassembly 1 and the DPF subassembly 2 are connected to the air inlet of the mixer 3. The DPF subassembly 2 is located between the DOC and air intake subassembly 1 and the air inlet of the mixer 3. The SCR and air outlet subassembly 5 are connected to the air outlet of the mixer 3. The DOC and the air intake sub-assembly 1, the DPF sub-assembly 2, the mixer 3, the SCR and the air outlet sub-assembly 5 can be connected and fixed by flanges, clamps or welding.

[0033] In this embodiment, two clamps 4 are used, one clamp 4 is used to fix the connection between the mixer and the DPF sub-assembly, and the other clamp is used to fix the connection between the mixer and the SCR and the gas outlet sub-assembly 5, so as to achieve the function of connection fixation and sealing.

[0034] In this embodiment, a strap bracket 6 is used to achieve installation and fixation of the after-treatment system to the vehicle. On the one hand, it is fixed to the outer surface of the after-treatment system through a strap, and on the other hand, it is connected to the installation position of the vehicle through the mounting holes on the strap bracket.

[0035] like Figure 2As shown, based on the connection relationship of the various components of the exhaust after-treatment system of the present invention, the engine's high-temperature exhaust gas (exhaust) passes through the internal cavity formed by the DOC and the intake sub-assembly 1, the DPF sub-assembly 2, the mixer 3, the SCR and the exhaust sub-assembly 5 in sequence, and the engine's high-temperature exhaust gas and the reducing agent are mixed inside the mixer 3, and the catalytic reduction reaction is carried out in the rear-stage SCR and the exhaust sub-assembly 5, and then the exhaust gas that meets the requirements is discharged.

[0036] like Figures 3 to 5 FIG. 1 shows an embodiment of a mixer 3 of the present invention. The mixer 3 includes an outer shell 12, a sealing plate 15, and a mixing tube assembly 9. The outer shell 12 and the sealing plate 15 surround a mixing chamber. In this embodiment, a heat insulating cotton 11 and a heat insulating cover 10 are sequentially arranged on the outside of the outer shell 12.

[0037] The mixing chamber is provided with a baffle 13, which can be fixed to the inner surface of the outer shell 12. The baffle 13 divides the mixing chamber into two cavities, the upper part being the upper cavity and the lower part being the lower cavity. The sealing plate 15 is provided with an air inlet corresponding to the upper cavity and an air outlet corresponding to the lower cavity. The mixing tube assembly 9 extends downward from the upper cavity and passes through the baffle 13 to the lower cavity, that is, the mixing tube assembly 9 penetrates between the upper cavity and the lower cavity.

[0038] A reductant nozzle 7 is disposed at the top of the outer housing 12 for spraying a reductant, such as a urea-water solution, into the top of the mixing tube assembly 9. The reductant nozzle 7 is secured to a nozzle mounting bracket 16, which is in turn mounted on a nozzle mounting plate 17. The nozzle mounting plate 17 is located at the top of the outer vortex tube 901. The reductant nozzle 7 sprays the reductant into the interior of the mixing tube assembly 9.

[0039] like Figures 5 to 7The figure shows an embodiment of a mixing tube assembly 9 of the present invention. The mixing tube assembly 9 includes an outer vortex tube 901, an inner vortex tube 903, a mixing outer tube 902, a mixing middle tube 904 and a mixing inner tube 905. The inner vortex tube 903 is located in the outer vortex tube 901, the mixing middle tube 904 is located in the mixing outer tube 902, the mixing inner tube 905 is located in the mixing middle tube 904, the outer vortex tube 901 is connected to the top end of the mixing outer tube 902, the inner vortex tube 903 is connected to the top end of the mixing middle tube 904, the interior of the mixing inner tube 905 forms a first mixing chamber a, and the mixing inner tube 905 and the mixing middle tube 904 are connected to each other. A second mixing chamber b is formed between the layer tubes 904, and a third mixing chamber c is formed between the mixing middle layer tube 904 and the mixing outer layer tube 902. The wall of the outer swirl tube 901 is provided with an outer swirl window, which is used for the inlet of the gas. The wall of the inner swirl tube 903 is provided with an inner swirl window. The outer swirl tube 901 and the inner swirl tube 903 can form a rotating form when the gas enters the mixing tube assembly. The outer swirl window and the inner swirl window can both be provided with swirl blades to enhance the swirl effect. The swirl blades can be set to face outward or inward. The blade window of the inner swirl tube 903 can also remove the swirl blades, leaving only the window for gas to pass through. While ensuring the swirl speed of the gas in the mixing tube, the outer tube diameter can be increased, the mixing chamber volume can be increased, and the back pressure can be effectively reduced.

[0040] The top of the outer vortex tube 901 and the inner vortex tube 903 are both provided with a first top pipe opening for the flow of reducing agent. The top of the mixing inner layer tube 905 is provided with a second top pipe opening for the flow of a mixed gas of gas and reducing agent.

[0041] like Figure 5 and Figure 6A As shown, the wall of the mixed inner layer tube 905 is provided with a plurality of slots, and the wall of the mixed middle layer tube 904 is provided with a plurality of first openings. The slots are groove-shaped openings, and the first openings are circular hole-shaped openings.

[0042] The outer mixing tube 902, middle mixing tube 904, and inner mixing tube 905 all have bottom openings at their bottom ends. Several second openings are provided in the lower wall of the outer mixing tube 902. Each bottom opening and the second openings serve as outlets for the mixed gas in the mixing tube assembly. The slots in the inner mixing tube 905, the first opening in the middle mixing tube 904, and the second openings in the outer mixing tube 902 all function to regulate airflow and backpressure. Specifically, the second opening in the lower chamber of the outer mixing tube 902 serves as one portion of the outlet, while the bottom openings of the outer mixing tube 902, middle mixing tube 904, and inner mixing tube 905 serve as another portion of the outlet. The mixed gas flows out through the second openings and the bottom channel formed by the bottom opening and the curved plate. Furthermore, the slots, first openings, and second openings effectively enhance urea droplet breakup, promote mixing of urea with high-temperature exhaust gas, improve the energy absorption rate of the urea liquid, and reduce the risk of crystallization.

[0043] The gas enters the interior of the mixing tube assembly 9 through the outer swirl tube 901 and the inner swirl tube 903, where it swirls and flows, mixing thoroughly with the reductant injected from the nozzle 7. The mixed gas enters the second mixing chamber b through the first mixing chamber a, and then enters the third mixing chamber c through the second mixing chamber b. The mixed gas in each mixing chamber ultimately flows out through the mixed gas outlet. The bottom pipe openings and the second opening on the outer mixing tube 902 serve as the mixed gas outlet, and then flows into the lower chamber, flows out, and enters the SCR and the gas outlet assembly for discharge.

[0044] The above-mentioned arrangement of the present invention effectively increases the mixing effect of airflow and urea under low-load and easy-crystallization conditions; the mixing chamber formed between two adjacent layers of tubes is conducive to increasing the mixing space, improving the urea evaporation rate, and reducing the generation of crystals. The multi-layer tube structure can effectively reduce the generation of crystals and can generate more ammonia to react with nitrogen oxides for reduction. In addition, it is conducive to increasing the mixing space, improving the urea evaporation rate, and can effectively improve the uniformity index of gas and ammonia before SCR (selective catalytic reducer), thereby improving the reduction reaction ability with nitrogen oxides. In addition to the three-layer mixing tube provided by the present invention, it can also be transformed into a four-layer mixing tube.

[0045] like Figure 5 As shown, the mixing tube assembly 9 includes an arc plate 14 disposed at each bottom tube port. Concave channels are formed on either side of the arc plate 14, allowing the mixed gas flowing out of each bottom tube port to flow out through the concave channels. Within the mixing tube assembly 9, the mixed gas flows out through the arc plate 14. In addition to securing and supporting the mixing tube assembly 9, the arc plate 14 effectively prevents crystallization and deposits, regulates airflow direction, and improves the uniformity of the exhaust gas and ammonia before the SCR process.

[0046] The mixing tube assembly, mixer and exhaust gas after-treatment system of the present invention can effectively adjust the airflow distribution and back pressure, improve the mixing efficiency of urea and exhaust gas, reduce urea consumption and reduce crystallization.

[0047] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it is apparent that various modifications and variations may be made without departing from the spirit and scope of the present invention. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

Claims

1. A mixing tube assembly, characterized in that: The flask has a plurality of inner tubes, each of which is connected to the outer tube, and the outer tube has a plurality of inner tubes, each of which is connected to the outer tube. The flask has a plurality of inner tubes, each of which is connected to the outer tube. The flask has a plurality of inner tubes, each of which is connected to the outer tube.

2. The mixing tube assembly according to claim 1, wherein: The wall of the mixed inner layer tube is provided with a plurality of slots, and the wall of the mixed middle layer tube is provided with a plurality of first openings.

3. The mixing tube assembly according to claim 2, wherein: The slot is a slot-shaped opening, and the first opening is a circular hole-shaped opening.

4. The mixing tube assembly according to claim 1, wherein: The outer swirl window and the inner swirl window are both provided with swirl sheets.

5. The mixing tube assembly according to claim 1, wherein: The bottom ends of the outer mixing tube, the middle mixing tube and the inner mixing tube all have bottom tube openings. The lower tube wall of the outer mixing tube is provided with several second openings. Each bottom tube opening and the second openings serve as the mixed gas outflow outlet of the mixing tube assembly.

6. The mixing tube assembly according to claim 5, wherein: The second opening is a circular hole.

7. The mixing tube assembly according to claim 5, wherein: The mixing tube assembly comprises an arc plate arranged at each bottom pipe port, and at least one side of the arc plate has a concave channel, so that the mixed gas flowing out of each bottom pipe port flows out through the concave channel.

8. A mixer, characterized in that: It includes an outer shell, a sealing plate, a nozzle, and a mixing tube assembly according to any one of claims 1 to 7, wherein the outer shell and the sealing plate surround and form a mixing chamber, the mixing chamber is provided with a baffle, the baffle separates the mixing chamber into an upper chamber and a lower chamber, the sealing plate is provided with an air inlet corresponding to the upper chamber and an air outlet corresponding to the lower chamber, the mixing tube assembly extends downward from the upper chamber and passes through the baffle to the lower chamber, the outer swirl window of the outer swirl tube is located in the upper chamber, and the nozzle is installed on the first top pipe opening.

9. An exhaust gas after-treatment system, characterized in that: Comprising the mixer according to claim 8.

10. The exhaust gas after-treatment system according to claim 9, characterized in that: The system includes a DOC and an air intake subassembly, a DPF subassembly, an SCR and an air outlet subassembly. The DOC and air intake subassembly, the DPF subassembly and the air inlet of the mixer are connected. The DPF subassembly is located between the DOC and air intake subassembly and the air inlet of the mixer. The SCR and air outlet subassembly are connected to the air outlet of the mixer.

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