CN211737255U

CN211737255U - Mixer and engine exhaust aftertreatment system

Info

Publication number: CN211737255U
Application number: CN202020317518.9U
Authority: CN
Inventors: 王杰; 史金良; 狄剑超
Original assignee: Faurecia Emissions Control Technologies Development Shanghai Co Ltd
Current assignee: Faurecia Emissions Control Technologies Development Shanghai Co Ltd
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2020-10-23
Anticipated expiration: 2030-03-13

Abstract

The utility model relates to a blender and engine exhaust aftertreatment system. The mixer comprises a mixing channel, wherein one end of the mixing channel is an inlet end, and the other end of the mixing channel is an outlet end; allowing the engine exhaust gas and the reducing agent solution to enter from the inlet end, mix in the mixing passage, and then to exit from the outlet end; a first swirler; and a second swirler; the first swirler and the second swirler are positioned in the mixing channel, the first swirler is positioned at the inlet end and is used for performing swirling action on the engine exhaust to form swirling flow, and the swirling flow is mixed with the reducing agent solution to form a first mixed fluid; the second swirler is located downstream of the first swirler for swirling the first mixed fluid to form a second mixed fluid for discharge from the outlet end.

Description

Mixer and engine exhaust aftertreatment system

Technical Field

The utility model relates to an exhaust-gas treatment field especially relates to a blender and engine exhaust aftertreatment system.

Background

In recent years, emission and oil consumption regulations of engines are becoming strict, strict oil consumption regulations limit that the engines need to be fully combusted, and the full combustion is at the cost of increased nitrogen oxide content in exhaust gas, which is limited by strict emission regulations, for example, in European 'Euro VI' diesel engine emission standards, diesel particulate emission should be lower than 10mg/kwh, and nitrogen oxide emission should be lower than 460 mg/kwh. Therefore, under the increasingly strict emission and fuel consumption standards and the requirements of engine miniaturization and light weight, the exhaust gas after-treatment system should be correspondingly improved, such as an engine exhaust gas recirculation system is added, but the temperature of the engine is reduced, part of fuel oil is not fully combusted, unburned hydrocarbon and particulate matter emission are increased, so that under the increasingly strict emission and fuel consumption standards and the requirements of engine miniaturization and light weight, the exhaust gas after-treatment system must be correspondingly improved to meet the requirements of government regulations.

Engine exhaust aftertreatment systems treat hot exhaust gases produced by the engine through various upstream exhaust components to reduce exhaust pollutants. The various upstream exhaust components may include one or more of the following: pipes, filters, valves, catalysts, mufflers, etc. For example, an upstream exhaust component directs exhaust gases into a Diesel Oxidation Catalyst (DOC) having an inlet and an outlet. Downstream of the Diesel oxidation catalyst, a Diesel Particulate Filter (DPF) may be arranged. Downstream of the diesel oxidation catalyst and the optional diesel particulate filter is a Selective Catalytic Reduction (SCR) catalyst having an inlet and an outlet. The outlet passes the exhaust to a downstream exhaust component. A mixer (mixer) is positioned downstream of the outlet of the DOC or DPF, upstream of the inlet of the SCR catalyst. Inside the mixer, the exhaust gas forms a swirling flow (swirl), and a doser (doser) is used for injecting a reducing agent such as a urea aqueous solution into the exhaust swirling flow from the upstream of the SCR catalyst so that the mixer can sufficiently mix the urea and the exhaust gas together, and the mixture is discharged into the SCR catalyst to perform a reduction reaction to generate nitrogen and water so as to reduce the nitrogen oxide emission of the engine.

In the prior art, in order to ensure the uniformity of the mixing of the exhaust swirling flow and the urea, for example, in the utility model patent with publication number CN208106533U, a swirler with blades is arranged at the inlet end of the mixer, but the inventor finds in practice that when the design of arranging one swirler only at the inlet end is faced with the upgrading of emission regulations, lower exhaust temperature, more compact space and higher urea injection amount, more urea aqueous solution is difficult to be completely decomposed, so as to generate crystals, block the mixer, increase the exhaust back pressure of the exhaust post-treatment system, and influence the performance of the exhaust post-treatment system.

Therefore, there is a need in the art for a mixer with good mixing uniformity and low urea crystallization rate and an engine exhaust aftertreatment system with low exhaust backpressure and low nox emissions.

SUMMERY OF THE UTILITY MODEL

It is an object of the present invention to provide a mixer.

It is another object of the present invention to provide an engine exhaust aftertreatment system.

According to the utility model discloses a blender of aspect includes: one end of the mixing channel is an inlet end, and the other end of the mixing channel is an outlet end; allowing the engine exhaust gas and the reducing agent solution to enter from the inlet end, mix in the mixing passage, and then to exit from the outlet end; a first swirler; and a second swirler; the first swirler and the second swirler are positioned in the mixing channel, the first swirler is positioned at the inlet end and is used for performing swirling action on the engine exhaust to form swirling flow, and the swirling flow is mixed with the reducing agent solution to form a first mixed fluid; the second swirler is located downstream of the first swirler for swirling the first mixed fluid to form a second mixed fluid.

In one or more embodiments of the mixer, a first tube is included that provides the mixing channel, one end of the first tube being an inlet end and the other end of the first tube being an outlet end; the first swirler comprises a first swirler body and a plurality of first swirling vanes which are positioned at an opening on the side wall of the first swirler body and distributed along the side wall, and the first swirler body is sleeved inside the first pipe body; the second swirler includes a plurality of second swirler vanes.

In one or more embodiments of the mixer, the axes of the first duct, the first swirler, and the second swirler are coincident, a first gap exists between the first swirler and an inner wall surface of the mixing passage, and a downstream end of the first gap is sealed.

In one or more embodiments of the mixer, the first swirler body is a second tube, and the first swirl vanes are distributed in a single section or multiple sections in an axial direction of the second tube; the second swirler is of a fan structure, and the second swirl vanes are fan blades with curved surfaces.

In one or more embodiments of the mixer, the number of the first swirl vanes is 2-30 in each axial section of the second pipe body, the included angle between each first swirl vane and the side wall opening of the second pipe body is 0-175 °, and the number of the second swirl vanes is 2-30.

In one or more embodiments of the mixer, the number of the first swirl vanes in each section is 10-20, the included angle between each first swirl vane and the side wall opening of the second pipe body is 30-60 degrees, and the number of the second swirl vanes is 5-12.

In one or more embodiments of the mixer, the first swirler body is a first cone, and the first swirl vanes are distributed in a single section or multiple sections in an axial direction of the first cone; the second swirler is of a fan structure, and the second swirl vanes are fan blades with curved surfaces.

In one or more embodiments of the mixer, the number of the first swirl blades in each section of the first cone in the axial direction is 2-30, the included angle between each first swirl blade and the side wall opening of the second tube body is 0-175 °, and the number of the second swirl blades is 2-30.

According to the utility model discloses an engine exhaust aftertreatment system of aspect, including the ration charging means to and as above arbitrary one the blender, the reductant solution that the ration charging means sprayed is urea solution.

The utility model discloses an advance effect includes but is not limited to, downstream through at first swirler sets up the second swirler, exert the whirl effect with reducing agent solution at the first cyclone body of first swirler formation to exhaust, both can make exhaust more abundant with reducing agent solution's heat exchange, also can smash reducing agent solution further through the second swirler, make urea solution decompose fully, avoid the urea crystallization and lead to blockking up the blender, increase exhaust aftertreatment system's exhaust backpressure, thereby influence exhaust aftertreatment system's performance. Meanwhile, the mixing uniformity of the exhaust and the reducing agent solution is good, the treatment efficiency of the nitrogen oxide is high, and the emission of the nitrogen oxide of an exhaust aftertreatment system is low.

Drawings

The above and other features, properties and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings, it being noted that the drawings are given by way of example only and are not drawn to scale, and should not be taken as limiting the scope of the invention, which is actually claimed, wherein:

fig. 1 is a schematic view of the internal structure of a mixer according to a first embodiment.

Fig. 2 is a structural diagram from the external perspective of the mixer according to the first embodiment.

Fig. 3A and 3B are schematic structural views of the mixer according to the first embodiment from an upstream side view and a downstream side view, respectively.

Fig. 4 is a schematic view of the flow inside the mixer according to the first embodiment.

Fig. 5A and 5B are schematic diagrams of the second swirler of the mixer according to the first embodiment, respectively in a side view and an external view.

Fig. 6 is a schematic flow diagram of a second cyclone of the mixer according to the first embodiment.

Fig. 7 is a schematic view of the internal structure of the mixer according to the second embodiment.

Fig. 8A and 8B are schematic structural views of the mixer according to the second embodiment from an upstream side view and a downstream side view, respectively.

Fig. 9 is a schematic view of the flow inside the mixer according to the second embodiment.

Reference numerals:

100-mixer

10-mixing channel

101-inlet end

102-outlet end

103-first tube

1-first cyclone

11-a second tube body,

111. 112-side wall opening

12-first swirl vane

13-first cone

2-second swirler

21-second swirl vane

210-curved surface

20-exhaust of gases

30-urea solution

40-first mixed fluid

50-second Mixed fluid

Detailed Description

The following discloses many different embodiments or examples for implementing the subject technology described. Specific examples of components and arrangements are described below to simplify the present disclosure, but these are merely examples and are not intended to limit the scope of the present invention.

It is to be noted that upstream and downstream in the following embodiments refer to relative positions in terms of the flow direction of exhaust gas in the exhaust aftertreatment system.

First embodiment

Referring to fig. 1 to 6, in a first embodiment, a mixer 100 of an exhaust aftertreatment system comprises a mixing channel 10, a first swirler 1 and a second swirler 2, the mixing channel 10 having an inlet end 101 at one end and an outlet end 102 at the other end, the first swirler 1 and the second swirler 2 being located in the mixing channel 10, the first swirler 1 being located at the inlet end 101 and the second swirler 2 being located downstream of the first swirler 1. As shown in fig. 4, engine exhaust 20 and a reducing agent solution, typically a urea solution 30, sprayed from a doser of an exhaust aftertreatment system, enters at an inlet end 101, typically in the form of a spray (spray). The exhaust gas 20 forms a swirling flow (swirling) after the first cyclone 1 passes through the swirling action of the first cyclone 1, the swirling flow is mixed with the urea solution 30 to form a first mixed fluid 40, the first mixed fluid 40 of the exhaust gas and the urea solution passes through the second cyclone 2 located downstream of the first cyclone 1 to perform a swirling action again to form a second mixed fluid 50, and the second mixed fluid 50 is output from the outlet end 102. The beneficial effect that so set up lies in, has reduced urea crystallization, avoids the increase of exhaust back pressure. The principle is that the inventor has found in practice that if the mixer 100 is provided with the first swirler 1 only at the inlet end 101 of the mixing channel 10, a liquid film and thus urea crystals may be formed on the wall surface of the mixing channel 10 when the emissions regulations are upgraded, the exhaust gas temperature is lower, the space is more compact, and the urea injection amount is higher. This problem has not been solved by the means of reducing the diameter of the mixing channel to increase the velocity of the exhaust gas, as is common in the art. On the other hand, by providing the second cyclone 2 downstream of the first cyclone 1, as shown in fig. 6, the first mixed fluid 40 formed by the first cyclone 1 is subjected to secondary swirling, the flow direction of the fluid is changed, and the liquid film on the wall surface of the mixing passage 10 is significantly reduced, so that the heat exchange between the exhaust gas in the mixed fluid and the urea solution is more sufficient, and the droplets of the urea solution can be further broken by the secondary swirling action, thereby further promoting the decomposition of the urea solution and reducing the possibility of forming the liquid film and crystals. It will be appreciated by those skilled in the art that in one or more embodiments, the number of cyclones 1 is not limited to the two cyclones shown in fig. 1 and 2, and that if emission regulations are more stringent and mixing conditions such as exhaust gas temperature, mixing space and urea injection amount are more stringent, a third cyclone may be provided downstream of the second cyclone, and so on, and not limited to the number shown in the figures.

With continued reference to fig. 1 and 2, in the first embodiment, the mixing channel 10 is embodied in a mixer 100 comprising a first tube 103, the first tube 103 providing the mixing channel 10, one end of the first tube 103 being an inlet end 101, and the other end of the first tube 103 being an outlet end 102; the first swirler 1 includes a first swirler body, which in the first embodiment is specifically configured as a second tube 11, and a plurality of first swirl vanes 12 located at a sidewall opening 111 of the second tube 11 and distributed along the sidewall. The first swirl vanes 12 may be distributed in a single segment along the axial direction of the second pipe 11 as shown in the first embodiment of fig. 1 and 2, or may be distributed in multiple segments, illustratively, for example, a plurality of vane segments are adjacently distributed along the axial direction of the second pipe 11, and each vane segment is provided with the first swirl vanes 12. The second tube 11 is sleeved inside the first tube 103; the specific structure of the second cyclone 2 may be a fan structure, but not limited to this, and may also be a structure similar to the first cyclone 1. The second swirler 2 includes a plurality of second swirler vanes 21. The fan structure has the advantages that the urea solution 30 and the exhaust gas 20 can be mixed as much as possible in the stage of the rotational flow effect of the first cyclone 1, and the urea solution 30 and the exhaust gas 20 can be mixed effectively in the stage of the rotational flow effect of the second cyclone 2.

With continued reference to fig. 1 and 2, in the first embodiment, the axes of the first tube 103, the first cyclone 1 and the second cyclone 2 are coincident, so that the airflow movement is facilitated, a first gap G1 exists between the first cyclone 1 and the inner wall surface of the mixing channel 10, and the downstream end of the first gap G1 is sealed to prevent the unmixed exhaust gas or urea solution from directly flowing into the first cyclone 2.

Referring to fig. 1, 3A, 3B, 5A, 5B and 6, in the first embodiment, the number of the first swirl blades 12 in each section may be set to 2 to 30, an included angle between each first swirl blade 12 and the side wall opening 111 of the second pipe 11 may be set to 0 to 175 °, the number of the second swirl blades 21 may also be set to 2 to 30, and the second swirl blades 21 are 210 fan blades having curved surfaces, so that a mixing path of the urea solution and the exhaust gas may be increased, mixing may be more sufficient, and droplets of the urea solution may be more favorably broken. Preferably, the number of each section of the first swirl blades 12 is 10 to 20, the included angle between each first swirl blade 12 and the side wall opening of the second pipe body 11 is 30 to 60 degrees, and the number of the second swirl blades 21 is 5 to 12, which is selected according to the actual engineering requirement.

Second embodiment

The second embodiment is modified from the first embodiment described above, and only the modified portions will be described below.

As shown in fig. 7 to 9, in the second embodiment, the first swirler 1 has a specific structure that the first swirler body is a first cone 13, the first swirl vanes 12 are distributed along the tapered surface of the first cone 13, as shown in fig. 8A and 8B, in the second embodiment, the number of the first swirl vanes 12 in each segment may be set to be 2 to 30, the included angle between each first swirl vane 12 and the side wall opening 112 of the first cone 13 may be set to be 0 to 175 °, and the number of the second swirl vanes 21 may also be set to be 2 to 30. Preferably, the number of the first swirl blades 12 in each section is 10-20, the included angle between each first swirl blade 12 and the side wall opening 112 of the first cone 13 is 30-60 °, and the number of the second swirl blades 21 is 5-12, which is selected according to the actual engineering requirement.

As can be seen from the above, the mixer and the exhaust gas aftertreatment system described in the above embodiments have the beneficial effects that, by disposing the second cyclone at the downstream of the first cyclone and applying a cyclone effect to the first cyclone formed by the exhaust gas and the reducing agent solution in the first cyclone, not only can the heat exchange between the exhaust gas and the reducing agent solution be more sufficient, but also the reducing agent solution can be further broken up by the second cyclone, so that the urea solution is sufficiently decomposed, the blockage of the mixer due to urea crystallization is avoided, and the exhaust back pressure of the exhaust gas aftertreatment system is increased, thereby affecting the performance of the exhaust gas aftertreatment system. Meanwhile, the mixing uniformity of the exhaust and the reducing agent solution is good, the treatment efficiency of the nitrogen oxide is high, and the emission of the nitrogen oxide of an exhaust aftertreatment system is low.

Although the present invention has been described in the above embodiments, it is not intended to limit the present invention, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention for optimizing the mixing of the exhaust gas and the urea solution by changing the flow direction of the first mixed fluid, for example, the third cyclone is further provided downstream of the second cyclone, and the specific form of the cyclone is not limited to the structures described in the first and second embodiments, as long as the cyclone can induce the swirling action. Therefore, any modification, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention, all without departing from the content of the technical solution of the present invention, fall within the scope of protection defined by the claims of the present invention.

Claims

1. A mixer for mixing engine exhaust with a reductant solution, comprising:

one end of the mixing channel is an inlet end, and the other end of the mixing channel is an outlet end; allowing the engine exhaust gas and the reducing agent solution to enter from the inlet end, mix in the mixing passage, and then to exit from the outlet end;

a first swirler;

and a second swirler;

the first swirler and the second swirler are positioned in the mixing channel, the first swirler is positioned at the inlet end and is used for performing swirling action on the engine exhaust to form swirling flow, and the swirling flow is mixed with the reducing agent solution to form a first mixed fluid; the second swirler is located downstream of the first swirler for swirling the first mixed fluid to form a second mixed fluid.

2. The mixer of claim 1, including a first tube providing the mixing channel, one end of the first tube being an inlet end and the other end of the first tube being an outlet end; the first swirler comprises a first swirler body and a plurality of first swirling vanes which are positioned at an opening on the side wall of the first swirler body and distributed along the side wall, and the first swirler body is sleeved inside the first pipe body; the second swirler includes a plurality of second swirler vanes.

3. The mixer of claim 2, wherein the axes of the first tube, the first swirler, and the second swirler are coincident, a first gap exists between the first swirler and an inner wall surface of the mixing passage, and a downstream end of the first gap is sealed.

4. The mixer of claim 2, wherein the first swirler body is a second tube, and the first swirl vanes are distributed in a single stage or multiple stages in an axial direction of the second tube; the second swirler is of a fan structure, and the second swirl vanes are fan blades with curved surfaces.

5. The mixer according to claim 4, wherein the number of the first swirl vanes is 2 to 30 in each section of the second pipe body in the axial direction, each of the first swirl vanes forms an angle of 0 to 175 ° with the side wall opening of the second pipe body, and the number of the second swirl vanes is 2 to 30.

6. The mixer of claim 5, wherein each of the first swirl vanes is 10-20, each of the first swirl vanes is 30-60 ° from the side wall opening of the second tube, and the second swirl vanes is 5-12.

7. The mixer of claim 2, wherein the first swirler body is a first cone, and the first swirl vanes are distributed in a single or multiple stages in an axial direction of the first cone; the second swirler is of a fan structure, and the second swirl vanes are fan blades with curved surfaces.

8. The mixer according to claim 7, wherein the number of the first swirl blades is 2-30 in each section of the first cone in the axial direction, each of the first swirl blades forms an angle of 0-175 ° with the side wall opening of the first cone, and the number of the second swirl blades is 2-30.

9. The mixer of claim 8, wherein each of the first swirl vanes is 10-20, each of the first swirl vanes is 30-60 ° from the side wall opening of the first cone, and the second swirl vanes is 5-12.

10. An engine exhaust aftertreatment system comprising a doser, further comprising a mixer according to any of claims 1 to 9, the doser spraying a reducing agent solution which is a urea solution.