Post-treatment mixer and tail gas post-treatment device

Abstract

The utility model relates to the technical field of tail gas after-treatment, in particular to an after-treatment mixer and a tail gas after-treatment device. The post-treatment mixer comprises a gas inlet pipe, a rotational flow pipe arranged at the top of the gas inlet pipe, and an evaporation plate group, a rotational flow bottom bowl baffle and a rectifying plate which are sequentially arranged in the gas inlet pipe; the rotational flow bottom bowl baffle comprises a frustum protruding towards the front side and a margin plate on the outer ring of the frustum, and rotational flow holes and rotational flow blades are arranged on the margin plate. The rectifying plate comprises an arc-shaped plate protruding towards the rear side and an annular plate on the outer circle of the arc-shaped plate, rectifying holes are formed in the arc-shaped plate and the annular plate, and the rectifying holes in the arc-shaped plate are sparser than the rectifying holes in the annular plate. The utility model solves the problems of high back pressure, poor mixing uniformity, steel wool crystallization and the like of the existing mixer.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas post-processing, in particular to a post-processing mixer and a tail gas post-processing device. Background Art

[0002] The existing mixer is mainly composed of an air inlet baffle, a swirl tube, a Z-type baffle, steel wool and an air outlet baffle. After the urea and tail gas are mixed, the airflow will rotate along the swirl direction and enter the SCR through the steel wool.

[0003] The steel wool in the mixer of this structure causes high back pressure and poor overall mixing uniformity, resulting in insufficient NOx conversion efficiency. In addition, the steel wool structure itself easily causes urea to react to form ammonium salts, which is not conducive to the passage of PN (Particle Number), and some steel wool structures have crystallization and detachment problems. Utility Model Content

[0004] In view of the deficiencies in the prior art, the purpose of the embodiments of the utility model is to provide a post-processing mixer to solve the problems of the prior art mixers such as high back pressure, poor mixing uniformity and crystallization of steel wool.

[0005] In order to achieve the above purpose, the embodiment of the utility model provides the following technical solutions:

[0006] A post-treatment mixer comprises: an air intake pipe, a swirl pipe arranged at the top of the air intake pipe, and an evaporation plate group, a swirl bottom bowl baffle and a rectifying plate arranged in sequence in the air intake pipe; the swirl bottom bowl baffle comprises a frustum protruding toward the front side and an edge plate of the outer ring of the frustum, and swirl holes and swirl blades are arranged on the edge plate; the rectifying plate comprises an arc plate protruding toward the rear side and an annular plate of the outer ring of the arc plate, and both the arc plate and the annular plate are provided with rectifying holes, and the rectifying holes on the arc plate are arranged more sparsely than the rectifying holes on the annular plate.

[0007] Optionally, the air inlet pipe is cylindrical, the front end of the cylindrical air inlet pipe is closed, and an air inlet hole is arranged on the cylinder wall of the air inlet pipe.

[0008] Optionally, the air inlet holes are arranged on the wall of the air inlet pipe in a circular array around the axis of the air inlet pipe, and are arranged in more than two rows along the axial direction of the air inlet pipe.

[0009] Optionally, a mounting hole is provided on the wall of the air inlet pipe, and the swirl tube is installed on the mounting hole of the wall. The swirl tube is conical as a whole, and the conical swirl tube includes a large end and a small end, and the large end of the swirl tube is connected to the wall of the air inlet pipe.

[0010] Optionally, a swirl groove is opened on the tube wall of the swirl tube, and the swirl grooves are arranged in a circular array along the tube wall of the swirl tube. A swirl plate is provided at each swirl groove, and the swirl plate forms a predetermined angle with the tube wall of the swirl tube.

[0011] Optionally, the evaporation plate group includes a first evaporation plate and a second evaporation plate, both of which are provided with through holes, the first evaporation plate is rectangular, arranged along the axial direction of the intake pipe, and the plate surface of the first evaporation plate faces the swirl tube, and the second evaporation plate is circular, arranged along the radial direction of the intake pipe, and located on the rear side of the first evaporation plate.

[0012] Optionally, two first evaporation plates are provided, and the two first evaporation plates are arranged in parallel.

[0013] Optionally, a conical baffle is further provided at the rear side of the second evaporation plate, the conical baffle comprising a conical plate and a support plate, the diameter of the conical plate gradually increases along the airflow direction, and the front end of the conical plate is open and connected to the air inlet pipe.

[0014] Optionally, a support frame is provided at the bottom side of the front end of the intake pipe wall, and the intake pipe is fixed by the support frame and the support plate of the conical baffle.

[0015] The embodiment of the utility model further provides an exhaust gas post-treatment device, comprising the post-treatment mixer as described above.

[0016] One or more technical solutions provided in the embodiments of the present utility model have at least the following technical effects or advantages:

[0017] The post-treatment mixer of the utility model is provided with structures such as a swirl tube, an evaporation plate group, a swirl bottom bowl baffle and a rectifying plate, etc., which removes the steel wool structure, avoids the obstruction of the steel wool to the airflow, reduces the back pressure of the mixer, avoids the problem of steel wool crystallization and escape, and improves the mixing uniformity through the comprehensive effect of the evaporation plate group, the swirl bottom bowl baffle and the rectifying plate. In addition, the bottom bowl cone in the middle of the swirl bottom bowl baffle ensures that the airflow flows backward along its contour, thereby sweeping the droplets that may exist here, and the swirl blades in the outer circle will form a gas swirl effect again to further mix the urea droplets. At the same time, the arc plate in the middle of the rectifying baffle protrudes backward, and the rectifying holes on the arc plate are arranged more sparsely than the rectifying holes on the ring plate. Through the cooperation with the swirl bottom bowl baffle, the airflow coming out of the outer circle of the swirl bottom bowl baffle is guided to converge to the middle, thereby ensuring the uniformity of the airflow of the entire cross section, improving the uniformity of the SCR end face flow field, and in this process, the tail gas and ammonia are further mixed to promote the uniformity of ammonia distribution.

[0018] Additional advantages of the present invention will be given in the following description, and some will become apparent from the following description or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0020] Figure 1 It is a schematic diagram of an exhaust gas post-treatment device provided by an embodiment of the utility model;

[0021] Figure 2 It is a schematic diagram of a post-processing mixer provided in an embodiment of the utility model;

[0022] Figure 3 It is a schematic diagram of an air intake pipe provided by an embodiment of the utility model;

[0023] Figure 4 It is a schematic diagram of a cyclone tube provided in an embodiment of the utility model;

[0024] Figure 5 It is a schematic diagram of a first evaporation plate provided in an embodiment of the utility model;

[0025] Figure 6 It is a schematic diagram of a second evaporation plate provided in an embodiment of the utility model;

[0026] Figure 7 It is a schematic diagram of a conical baffle provided by an embodiment of the utility model;

[0027] Figure 8 This is a schematic diagram of a swirl bottom bowl baffle provided in an embodiment of the utility model;

[0028] Fig. 9 It is a schematic diagram of a rectifier plate provided in an embodiment of the utility model;

[0029] In the figure: 1, swirl tube; 11, swirl groove; 12, swirl plate; 2, air inlet pipe; 21, mounting hole; 22, air inlet hole; 23, support frame; 3, first evaporation plate; 5, conical baffle; 51, support plate; 52, conical plate; 6, second evaporation plate; 7, swirl bottom bowl baffle; 71, edge plate; 72, cone; 73, swirl hole; 74, swirl blade; 8, rectifying plate; 81, ring plate; 82, arc plate; 83, rectifying hole;

[0030] In order to show the positions of various parts, the distances or sizes between them are exaggerated and the schematic diagram is for reference only. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] SCR (Selective Catalytic Reduction) technology: a technology that uses ammonia and NOx to undergo a catalytic reduction reaction to eliminate nitrogen oxides in diesel engine exhaust.

[0033] SCR mixer: It is installed between the exhaust pipe and the SCR carrier, mainly used to improve the mixing uniformity between urea spray and exhaust gas, increase ammonia evaporation, and improve NOx conversion efficiency.

[0034] In order to solve the problems of high back pressure, poor mixing uniformity and steel wool crystallization of the existing mixer, the utility model proposes a post-processing mixer.

[0035] like Figure 1 , Figure 2 As shown, in one embodiment of the utility model, a post-treatment mixer is proposed, comprising: an air inlet pipe 2, a swirl tube 1 arranged on the top of the air inlet pipe 2, and an evaporation plate group, a swirl bottom bowl baffle 7 and a rectifying plate 8 arranged in sequence in the air inlet pipe 2, wherein the sequential arrangement refers to the sequential arrangement from front to back along the flow direction of the airflow. In addition, the front and rear mentioned in the utility model are also relative to the flow direction of the airflow, and the "front" refers to the front side or upstream of the airflow, and the "rear" refers to the rear side or downstream of the airflow.

[0036] The swirl bottom bowl baffle 7 includes a frustum 72 protruding toward the front side and an edge plate 71 on the outer ring of the frustum 72. Figure 8 As shown, the swirl bottom bowl baffle 7 is divided into two parts in the radial direction, including a cone 72 located at the radial center, the cone 72 protrudes to the front side of the airflow, and an annular edge plate 71 is provided on the outer circle of the cone 72. The edge plate 71 is provided with swirl holes 73 and swirl blades 74. The swirl holes 73 are arranged in a circle along the annular edge plate 71, and a swirl blade 74 is provided at the position of each swirl hole 73. The swirl blade 74 is set at a certain angle to the edge plate 71 so as to make the airflow swirl.

[0037] The two main features of the swirl bottom bowl baffle 7 structure are: the 360-degree circumferential swirl blades 74 and the smooth transition bottom bowl cone 72 in the middle. The smooth bottom bowl structure ensures that the airflow flows backward along its contour, thereby sweeping away the droplets that may exist here; the swirl blades 74 will form a gas swirl effect again to further mix the urea droplets.

[0038] The rectifying plate 8 comprises an arc-shaped plate 82 protruding toward the rear side and an annular plate 81 on the outer ring of the arc-shaped plate 82. Fig. 9 As shown, the rectifying plate 8 is also divided into two parts, inner and outer parts, in the radial direction, including an arc plate 82 located in the radial center, and the arc plate 82 protrudes toward the rear side of the airflow, and an annular plate 81 is arranged on the outer circle of the arc plate 82, and rectifying holes 83 are arranged on both the arc plate 82 and the annular plate 81, and the rectifying holes 83 on the arc plate 82 are arranged more sparsely than the rectifying holes 83 on the annular plate 81.

[0039] The porous rectifying plate 8 plays the role of exhaust rectification, ensuring the uniformity of the flow field in front of the SCR catalyst. Moreover, the porous rectifying baffle has an arc-shaped structure in the middle, and the arc-shaped contour protrudes toward the rear of the mixer. The rectifying plate 8 has rectifying holes 83, and the opening rule is that the rectifying holes 83 on the surroundings are relatively sparse, and the rectifying holes 83 in the middle are denser. The rectifying plate 8 cooperates with the swirl bottom bowl baffle 7 to guide the airflow coming out of the swirl bottom bowl baffle 7 from the surroundings to converge in the middle, thereby ensuring the uniformity of the airflow of the entire cross section, improving the uniformity of the SCR end face flow field, and in this process, further mixing the exhaust gas and ammonia to promote the uniformity of ammonia distribution.

[0040] like Figure 2 , Figure 3 As shown, the air intake pipe 2 is cylindrical, the front end of the cylindrical air intake pipe 2 is closed, and an air intake hole 22 is provided on the cylinder wall of the air intake pipe 2. The air intake holes 22 are arranged on the cylinder wall of the air intake pipe 2 in a circular array around the axis of the air intake pipe 2, and more than two rows are arranged along the axial direction of the air intake pipe 2. In this embodiment, the air intake holes 22 are arranged in two rows.

[0041] The front end of the porous air inlet pipe 2 has two rows of openings evenly spaced 360 degrees around it, guiding part of the airflow to flow in from here (the rest of the airflow enters through the swirl tube 1), thereby ensuring a higher axial airflow velocity near the wall surface, and sweeping from front to back, reducing the possibility of residual liquid film on the wall surface, especially on the bottom wall surface facing the urea nozzle, thereby reducing the risk of crystallization.

[0042] Further, such as Figure 2 , Figure 4As shown, a mounting hole 21 is provided on the wall of the intake pipe 2, and the swirl tube 1 is installed on the mounting hole 21 of the wall. The swirl tube 1 is tapered as a whole, and the tapered swirl tube 1 includes a large end and a small end, and the large end of the swirl tube 1 is connected to the wall of the intake pipe 2. A swirl groove 11 is provided on the wall of the swirl tube 1, and the swirl groove 11 is arranged in a circular array along the wall of the swirl tube 1. A swirl plate 12 is provided at each swirl groove 11, and the swirl plate 12 is at a predetermined angle to the wall of the swirl tube 1. The swirl tube 1 structure guides the airflow to form a swirl, thereby diffusing the cone angle of the urea droplet spray, dispersing the droplets, and preventing aggregation to form large droplets and thus crystallization.

[0043] like Figure 2 , Figure 5 , Figure 6 As shown, the evaporation plate group includes a first evaporation plate 3 and a second evaporation plate 6, both of which are provided with through holes, the first evaporation plate 3 is rectangular, the first evaporation plate 3 is arranged along the axial direction of the intake pipe 2, and the plate surface of the first evaporation plate 3 faces the swirl tube 1, and the second evaporation plate 6 is circular, the second evaporation plate 6 is arranged along the radial direction of the intake pipe 2, and is located at the rear side of the first evaporation plate 3. Among them, the first evaporation plate 3 is provided with two pieces, and the two first evaporation plates 3 are arranged in parallel. Through the evaporation plate group composed of the first evaporation plate 3 and the second evaporation plate 6, the three-stage heat exchange evaporation decomposition structure increases the heating area of ​​the spray droplets, which is conducive to the thermal decomposition process of urea molecules, that is, it is conducive to the generation of ammonia.

[0044] like Figure 2 , Figure 7 As shown, a conical baffle 5 is further provided at the rear side of the second evaporation plate 6, and the conical baffle 5 includes a conical plate 52 and a support plate 51. The diameter of the conical plate 52 gradually increases along the flow direction of the airflow, and the front end of the conical plate 52 is open and connected to the intake pipe 2. A support frame 23 is provided at the bottom side of the front end of the intake pipe 2 wall, and the intake pipe 2 is installed in the exhaust gas after-treatment device through the support frame 23 and the support plate 51 of the conical baffle 5.

[0045] The utility model proposes a combined mixer structure that balances space compactness and urea mixing uniformity, maintains a low back pressure, improves urea evaporation, improves the uniformity of ammonia distribution and the uniformity of exhaust gas flow field, and significantly improves the NOx conversion efficiency of exhaust pollutants. The structure is compact and simple, and components are easy to assemble and arrange.

[0046] Based on the above-mentioned post-treatment mixer, an embodiment of the utility model also provides an exhaust gas after-treatment device, in which the after-treatment mixer described in the above-mentioned embodiment is arranged. Since the above-mentioned post-treatment mixer has the above-mentioned technical effect, the technical effect of the exhaust gas after-treatment device using the post-treatment mixer please refer to the above-mentioned embodiment.

[0047] Although the above describes the specific implementation methods of the utility model in combination with the accompanying drawings, it is not intended to limit the scope of protection of the utility model. Technical personnel in the relevant field should understand that on the basis of the technical solution of the utility model, various modifications or deformations that can be made by technical personnel in this field without creative work are still within the scope of protection of the utility model.

Claims

1. A post-processing mixer, characterized in that, It includes: an air inlet pipe, a swirl pipe arranged on the top of the air inlet pipe, and an evaporation plate group, a swirl bottom bowl baffle and a rectifying plate arranged in sequence in the air inlet pipe; The swirl bottom bowl baffle includes a frustum protruding toward the front side and an edge plate on the outer ring of the frustum, and swirl holes and swirl blades are provided on the edge plate; the rectifying plate includes an arc-shaped plate protruding toward the rear side and an annular plate on the outer ring of the arc-shaped plate, and both the arc-shaped plate and the annular plate are provided with rectifying holes, and the rectifying holes on the arc-shaped plate are arranged more sparsely than the rectifying holes on the annular plate.

2. The post-processing mixer according to claim 1, characterized in that The air inlet pipe is cylindrical, the front end of the cylindrical air inlet pipe is closed, and an air inlet hole is provided on the cylinder wall of the air inlet pipe.

3. The post-processing mixer according to claim 2, characterized in that The air inlet holes are arranged on the wall of the air inlet pipe in a circular array around the axis of the air inlet pipe, and are arranged in more than two rows along the axial direction of the air inlet pipe.

4. The post-processing mixer according to claim 3, characterized in that The wall of the air inlet pipe is provided with a mounting hole, and the swirl tube is mounted on the mounting hole of the wall. The swirl tube is tapered as a whole, and includes a large end and a small end. The large end of the swirl tube is connected to the wall of the air inlet pipe.

5. The post-processing mixer according to claim 4, characterized in that The wall of the cyclone tube is provided with swirl grooves, which are arranged in a circumferential array along the wall of the cyclone tube. A swirl plate is provided at each swirl groove, and the swirl plate forms a predetermined angle with the wall of the cyclone tube.

6. The post-processing mixer according to claim 1, characterized in that The evaporation plate group includes a first evaporation plate and a second evaporation plate, both of which are provided with through holes. The first evaporation plate is rectangular and arranged along the axial direction of the intake pipe, with the plate surface of the first evaporation plate facing the swirl tube. The second evaporation plate is circular and arranged along the radial direction of the intake pipe and located on the rear side of the first evaporation plate.

7. The post-processing mixer according to claim 6, characterized in that There are two first evaporation plates, and the two first evaporation plates are arranged in parallel.

8. The post-processing mixer according to claim 6, characterized in that A conical baffle is further provided on the rear side of the second evaporation plate. The conical baffle comprises a conical plate and a support plate. The diameter of the conical plate gradually increases along the flow direction of the airflow. The front end of the conical plate is open and connected to the air inlet pipe.

9. The post-processing mixer according to claim 8, characterized in that A support frame is provided at the bottom side of the front end of the intake pipe wall, and the intake pipe is fixed by the support frame and the support plate of the conical baffle.

10. An exhaust gas post-treatment device, characterized in that: The invention comprises a post-processing mixer as described in any one of claims 1 to 9.

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