CN211397693U

CN211397693U - Mixer and engine exhaust aftertreatment system

Info

Publication number: CN211397693U
Application number: CN202020142046.8U
Authority: CN
Inventors: 刘鹏; 王杰; 高健
Original assignee: Faurecia Emissions Control Technologies Development Shanghai Co Ltd
Current assignee: Faurecia Emissions Control Technologies Development Shanghai Co Ltd
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2020-09-01
Anticipated expiration: 2030-01-20
Also published as: FR3106369A3; FR3106369B3

Abstract

The utility model relates to a blender and engine exhaust aftertreatment system. Wherein the mixer includes an outer housing having a first inlet end that receives engine exhaust; and an inner housing located inside the outer housing, the inner housing having a reductant chamber for receiving reductant sprayed toward the mixer; wherein a chamber wall of the reductant chamber comprises a porous wall, a gap between the porous wall and the outer housing defining an exhaust gas passage such that a portion of the engine exhaust gas entering the mixer from the first inlet end enters the reductant chamber from the porous wall and another portion flows through the exhaust gas passage.

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. Within the mixer, the exhaust gas produces a swirling or rotational motion. A doser (doser) is used to inject a reductant, such as an aqueous urea solution, into the exhaust stream upstream of the SCR catalyst such that the mixer can thoroughly mix the urea and exhaust together for discharge into the SCR catalyst for reduction to produce nitrogen and water to reduce the nitrogen oxide emissions of the engine. However, there are still improvements in the existing mixers, such as further improvement in the uniformity of mixing of exhaust gas with urea, reduction in urea crystallization, and the like.

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 nitrogen oxide 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.

A mixer according to one aspect of the present invention for an engine exhaust aftertreatment system includes an outer housing having a first inlet end receiving engine exhaust; and an inner housing located inside the outer housing, the inner housing having a reductant chamber for receiving reductant sprayed toward the mixer; wherein a chamber wall of the reductant chamber comprises a porous wall, a gap between the porous wall and the outer housing defining an exhaust gas passage such that a portion of the engine exhaust gas entering the mixer from the first inlet end enters the reductant chamber from the porous wall and another portion flows through the exhaust gas passage.

In one or more embodiments of the mixer, the outer housing comprises an outer tube body and a first inlet end upstream of the outer tube body; the inner housing includes an inner tube body and a second inlet end upstream of the inner tube body, the inner tube body and the second inlet end providing the reductant chamber; wherein a side of the first inlet end has an opening to receive the engine exhaust gas such that a majority of the engine exhaust gas enters the mixer from the side of the first inlet end; the porous wall includes an upstream porous wall located on a side of the second inlet end and a downstream porous wall located on a side of the inner pipe body, the exhaust gas passage includes a passage defined by a gap between the downstream porous wall and the outer pipe body, and the upstream porous wall is at least partially disposed opposite the opening.

In one or more embodiments of the mixer, the opening is provided with vanes at an opening edge of one side thereof to induce swirl of the engine exhaust gas entering the mixer from the opening, a portion of the engine exhaust gas entering the reductant chamber from through the upstream porous wall.

In one or more embodiments of the mixer, a side of the first inlet end includes a first tapered surface having the opening; the side of the second inlet end includes a second tapered surface having an upstream porous wall.

In one or more embodiments of the mixer, the inner housing and the outer housing are fixedly connected through a fixing member, and two ends of the fixing member are fixedly connected with the inner housing and the outer housing, respectively, so that the inner housing is fixed.

In one or more embodiments of the mixer, the mixer further includes an outer shroud surrounding the outer shell outside of the outer shell, the outer shroud including a flow directing section that forms a flow directing region with the first inlet end such that the engine exhaust is directed into the mixer from the first inlet end.

In one or more embodiments of the mixer, the outer casing further comprises an insulation section, the flow guide section is located upstream of the insulation section, and an insulation gap is defined between the insulation section and the outer casing; a sealing element is arranged between the flow guiding section and the heat insulation section to prevent the engine exhaust from entering the heat insulation gap.

According to an aspect of the utility model relates to an engine exhaust aftertreatment system, including the ration charging means, and above arbitrary one the blender, the ration charging means with reductant liquid to the reductant cavity sprays.

In one or more embodiments of the engine exhaust system, the injection port of the doser has a heating gap with the first inlet end such that a small portion of the engine exhaust enters the mixer through the heating gap.

In one or more embodiments of the engine exhaust system, the length of the inner housing is at least the spray distance over which the doser sprays the reducing agent.

In one or more embodiments of the engine exhaust system, the reductant liquid is a urea solution.

The utility model discloses an advance effect includes but is not limited to, through setting up the cavity wall of the reductant cavity of blender to porous structure, the exhaust gets into the reductant cavity from porous structure, has adjusted the air current motion of exhaust in the reductant cavity, has optimized the air current and has sprayed the mixture between the spraying of urea solution for air current and urea solution spraying mixing area increase, improves the heat exchange of urea solution spraying and exhaust, makes the urea spraying be more easily decomposed, reduces the urea crystallization; meanwhile, a part of exhaust gas flows through the exhaust channel, so that the porous wall can be heated, the heat radiation of urea solution spray in the reducing agent chamber is increased, and the urea solution sprayed on the porous wall can be heated to prevent the urea solution from crystallizing; and, for the urea solution sprayed to the holes of the porous wall, the urea solution can be blown into the reducing agent chamber by the exhaust gas flow so as to be fully mixed with the gas flow in the reducing agent chamber. The nitrogen oxide treatment of the exhaust aftertreatment system adopting the mixer is efficient and has less emission.

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 an internal structure of a mixer according to an embodiment.

Fig. 2 is a side view of the mixer according to fig. 1.

Fig. 3 is a schematic view of the internal gas flow of the mixer according to fig. 1.

Reference numerals:

1-Mixer

10-exhaust of gases

11-outer casing

110-outer tube body

111-first inlet end

112-opening

113-blade

12-inner shell

120-inner pipe body

121-reducing agent chamber

1210-porous wall

1211-upstream porous wall

1212-downstream porous wall

122-second inlet end

13-exhaust channel

14-fixing piece

15-outer cover

151-flow guiding section

152-insulating section

153-sealing element

100-flow guiding area

16-heat insulation gap

2-quantitative feeder

20-reducing agent

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 noted that references to "one embodiment," "an embodiment," and/or "some embodiments" in the following description mean that a particular feature, structure, or characteristic described in connection with at least one embodiment of the application is included. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one or more embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, some features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.

Referring to fig. 1 and 3, in one embodiment, an exhaust aftertreatment system includes a mixer 1 and a doser 2. The exhaust gas 10 is mixed in the mixer 1 with a reducing agent 20 sprayed by the doser 2, the reducing agent 20 being an aqueous urea solution. The mixer 1 comprises an outer housing 11 and an inner housing 12 located inside the outer housing 11. The outer housing 11 has a first inlet end 111 that receives the engine exhaust 10, which forms a vortex (swirling) at the first inlet end 111. The inner housing 12 has a reductant chamber 121 for receiving reductant 20 sprayed by the doser 2. Wherein the chamber wall of the reducing agent chamber 121 includes a porous wall 1210, and a gap between the porous wall 1210 and the outer casing 11 defines an exhaust gas passage 13, so that, as shown in fig. 3, the exhaust gas 10 enters the mixer 1 from the first inlet end 111, a swirl is generated at the first inlet end 111, as indicated by arrows, a part of the exhaust gas 10 enters the reducing agent chamber 121 from the porous wall 1210, and another part flows through the exhaust gas passage 13 and is discharged. The arrangement has the advantages that the chamber wall of the reducing agent chamber 121 is of a porous structure, the exhaust gas 10 enters the reducing agent chamber from the porous structure, the airflow movement of the exhaust gas 10 in the reducing agent chamber 121 is adjusted, the mixing between the airflow and the spray spraying the urea solution is optimized, the mixing area of the airflow and the urea solution spray is increased, the heat exchange between the urea solution spray and the exhaust gas is improved, the urea spray is easier to decompose, and the urea crystallization is reduced; meanwhile, a part of the exhaust gas flows through the exhaust passage 13, so that the porous wall can be heated to increase the heat radiation to the urea solution spray in the reducing agent chamber 121, and the urea solution sprayed on the porous wall can be heated to prevent the urea solution from crystallizing; also, the urea solution sprayed to the pores of the porous wall may be purged into the reducing agent chamber 121 with the flow of exhaust gas so as to be sufficiently mixed with the flow of gas inside the reducing agent chamber 121. Preferably, as shown in fig. 3, the length of the inner shell 12 is at least the spraying distance L of the doser 2 spraying the urea solution, so that the sprayed urea solution is sufficiently heated and mixed. The inner housing 12 may be fixed by a fixing member 14 as shown in fig. 1, two ends of the fixing member 14 are respectively fixedly connected with the inner housing 12 and the outer housing 11, and the specific position of the fixing member 14 may be located at the downstream end of the inner housing 12 as shown in fig. 1, but not limited thereto, for example, the fixing member 14 may also be simultaneously disposed at other positions, etc., and adjusted according to the specific fixing requirements in the actual engineering.

Referring to fig. 1 to 3, in some embodiments, the specific structure of the outer shell 11 and the inner shell 12 may be that the outer shell 11 includes an outer tube body 110 and a first inlet end 111 located upstream of the outer tube body 110; the inner housing 12 includes an inner tube body 120 and a second inlet end 122 located upstream of the inner tube body 120, the inner tube body 120 and the second inlet end 122 forming a reductant chamber 121. The way in which the exhaust gas 10 enters is side intake. Referring specifically to fig. 1 and 2, the side of the first inlet end 111 has an opening 112 that receives the exhaust gas 10 such that a majority of the exhaust gas 10 enters the mixer 1 from the side of the first inlet end 111. The majority of this means that the exhaust gas having a mass flow rate (massflow) of 60% or more, preferably 80% to 90%, enters from the side of the first inlet end portion 111. The remaining part of the gas flow, as shown in fig. 3, enters the mixer 1 from the heating gap G formed between the injection orifice of the doser 2 and the first inlet end 111, so that the injection orifice region of the doser 2 is heated and urea crystallization in this region is reduced. The porous wall 1210 includes an upstream porous wall 1211 located on the side of the second inlet end 122 and a downstream porous wall 1212 located on the side of the inner tube body 120, the exhaust gas passage 13 includes a passage defined by a gap between the downstream porous wall 1211 and the outer tube body 110, at least a portion of the upstream porous wall 1211 is located opposite to the opening 112, such that a portion of the exhaust gas entering from the opening 112 on the side of the first inlet end 111 enters the reducing agent chamber 121 directly from the second inlet end 122 through the upstream porous wall 1211, and a portion of the exhaust gas flows through the exhaust gas passage 13, enters the reducing agent chamber 121 through the downstream porous wall 1212, or flows directly through the exhaust gas passage 13 and is discharged therefrom. The beneficial effect of such setting is that, part of the exhaust starts to mix with the sprayed urea solution at the head of the reducing agent chamber 121, that is, the position of the second inlet end 122, so that the exhaust and the urea solution fully exchange heat, and the exhaust and the ammonia gas decomposed by the urea solution are fully mixed, and meanwhile, part of the exhaust flows through the exhaust passage 13, the reducing agent chamber 121 is continuously heated, the heating temperature of the reducing agent chamber is maintained, and the sufficient temperature is ensured in the mixing process of the urea solution and the exhaust in a long mixing path, and urea crystallization is reduced. Meanwhile, the mixer is more compact in the direction of the exhaust flow direction by adopting a side air inlet vortex structure, and the overall miniaturization of an exhaust aftertreatment system is facilitated. Referring to FIG. 2, exhaust gas 10 enters from opening 112 inducing swirl in exhaust gas 10. The specific structure of the opening 112 for inducing the exhaust gas swirl may be that the opening 112 is provided with a vane 113 at an opening edge of one side thereof, and the swirl motion of the exhaust gas is induced by the vane 113 structure. It will be appreciated that other configurations for inducing swirl may be used, and are not limited to the configuration of the vanes 113 to induce swirl depicted in FIG. 2.

With continued reference to fig. 1 and 3, in one or more embodiments, a specific configuration of the first inlet end 111 and the second inlet end 122 may be that the side of the first inlet end 111 includes a first tapered surface 1110, the first tapered surface 1110 having an opening 112; the sides of the second inlet end 122 include a second tapered face 1221, the second tapered face 1221 having an upstream porous wall 1211. The first inlet end 111 and the second inlet end 122 are provided with a tapered structure, which has the beneficial effect that the exhaust swirling can be further strengthened, and the heat exchange between the exhaust and the urea solution can be further increased.

With continued reference to fig. 1 and 3, in some embodiments, mixer 1 may further include an outer shroud 15, where outer shroud 15 surrounds outer housing 11 outside of outer housing 11. In some embodiments, the shroud 15 includes a flow guide section 151, the flow guide section 151 and the first inlet end 111 forming the flow guide region 100 such that the exhaust gas 10 is directed into the mixer 1 from the first inlet end 111. In some embodiments, the outer casing 15 may further include an insulation section 152, wherein the flow guide section 151 is located upstream of the insulation section 152, and the insulation section 152 and the outer casing 11 define an insulation gap 16 therebetween; a sealing member 153 is arranged between the flow guiding section 151 and the heat insulation section 152 to prevent the exhaust gas 10 from entering the heat insulation gap 16 to cause the heat loss of the exhaust gas.

As can be seen from the above, the beneficial effects of the mixer and the exhaust gas aftertreatment system described in the above embodiments include, but are not limited to, by setting the chamber wall of the reducing agent chamber 121 to be a porous structure, the exhaust gas 10 enters the reducing agent chamber from the porous structure, the airflow movement of the exhaust gas 10 in the reducing agent chamber 121 is adjusted, the mixing between the airflow and the spray spraying the urea solution is optimized, the mixing area of the airflow and the urea solution spray is increased, the heat exchange between the urea solution spray and the exhaust gas is improved, the urea spray is more easily decomposed, and the urea crystallization is reduced; meanwhile, a part of the exhaust gas flows through the exhaust passage 13, so that the porous wall can be heated to increase the heat radiation to the urea solution spray in the reducing agent chamber 121, and the urea solution sprayed on the porous wall can be heated to prevent the urea solution from crystallizing; the urea solution sprayed to the holes of the porous wall may be purged into the reducing agent chamber 121 by the flow of the exhaust gas, and may be sufficiently mixed with the flow of the gas in the reducing agent chamber 121. The exhaust gas post-treatment system adopting the mixer 1 and the quantitative feeder 2 has high nitrogen oxide treatment efficiency and less emission.

Although the present invention has been described with reference to the above embodiments, it is not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. 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 an engine exhaust aftertreatment system, comprising:

an outer housing having a first inlet end receiving engine exhaust; and

an inner housing located inside the outer housing, the inner housing having a reductant chamber for receiving reductant sprayed toward the mixer;

wherein a chamber wall of the reductant chamber comprises a porous wall, a gap between the porous wall and the outer housing defining an exhaust gas passage such that a portion of the engine exhaust gas entering the mixer from the first inlet end enters the reductant chamber from the porous wall and another portion flows through the exhaust gas passage.

2. The mixer of claim 1,

the outer housing includes an outer tube body and a first inlet end upstream of the outer tube body;

the inner housing includes an inner tube body and a second inlet end upstream of the inner tube body, the inner tube body and the second inlet end providing the reductant chamber;

wherein a side of the first inlet end has an opening to receive the engine exhaust gas such that a majority of the engine exhaust gas enters the mixer from the side of the first inlet end; the porous wall includes an upstream porous wall located on a side of the second inlet end and a downstream porous wall located on a side of the inner pipe body, the exhaust gas passage includes a passage defined by a gap between the downstream porous wall and the outer pipe body, and the upstream porous wall is at least partially disposed opposite the opening.

3. The mixer of claim 2, wherein the opening is provided with vanes at an opening edge on one side thereof to induce swirl of the engine exhaust gas entering the mixer from the opening, a portion of the engine exhaust gas entering the reductant chamber from passing through an upstream porous wall.

4. A mixer according to claim 2 or 3, wherein a side of the first inlet end portion comprises a first tapered surface having the opening; the side of the second inlet end includes a second tapered surface having an upstream porous wall.

5. The mixer of claim 1, wherein the inner housing and the outer housing are fixedly connected by a fixing member, and both ends of the fixing member are fixedly connected with the inner housing and the outer housing, respectively, so that the inner housing is fixed.

6. The mixer of claim 1 further comprising an outer shroud surrounding the outer housing outside of the outer housing, the outer shroud including a flow directing section that forms a flow directing region with the first inlet end such that the engine exhaust is directed into the mixer from the first inlet end.

7. The mixer of claim 6 wherein the outer shroud further comprises an insulation section, the inducer being upstream of the insulation section, the insulation section defining an insulation gap with the outer shell; a sealing element is arranged between the flow guiding section and the heat insulation section to prevent the engine exhaust from entering the heat insulation gap.

8. An engine exhaust aftertreatment system comprising a doser, further comprising a mixer according to any of claims 1 to 7, the doser spraying reductant liquid into the reductant chamber.

9. The engine exhaust aftertreatment system of claim 8, wherein the doser injection orifice and the first inlet end portion have a heating gap such that a small portion of the engine exhaust enters the mixer through the heating gap.

10. The engine exhaust aftertreatment system of claim 8, wherein the length of the inner housing is at least a spray distance of the doser spraying the reductant.

11. The engine exhaust aftertreatment system of claim 8, wherein the reductant liquid is a urea solution.