CN214887318U - Mixer and exhaust gas aftertreatment system - Google Patents

Abstract

The utility model relates to a blender and engine exhaust after-treatment system. Wherein the mixer comprises a housing having an air inlet, an air outlet, and a jet; and the mixing piece is used for providing a mixing channel of the mixer, a port at one end of the mixing piece corresponds to the jet orifice, so that the spray enters the mixing channel from the port, the periphery of the side surface of the mixing channel from the port is provided with a hole structure, the side surface of the mixing channel is communicated with the air inlet, and the waste gas enters the mixing channel from the side surface of the mixing channel through the hole structure.

Description

Mixer and exhaust gas aftertreatment system

Technical Field

The utility model relates to an engine exhaust aftertreatment system especially relates to a blender and exhaust aftertreatment system.

Background

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 gas 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) reactor having an inlet and an outlet. The outlet passes the exhaust gas 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. The exhaust gas enters a mixer, and an injector (injector) is used for injecting a urea aqueous solution spray into the exhaust gas flow from the upstream of the SCR so that the mixer can mix the urea and the exhaust gas together sufficiently and uniformly, and the urea and the exhaust gas are discharged into the SCR to carry out reduction reaction to generate nitrogen and water so as to reduce the emission of nitrogen oxides of an engine.

However, there are still improvements in the existing mixers, such as further improvement in the uniformity of mixing of the exhaust gas with the 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.

Another object of the utility model is to provide an engine exhaust aftertreatment system.

According to the utility model discloses a blender of aspect for engine exhaust aftertreatment system, include: a housing having an air inlet, an air outlet, and a jet orifice; and the mixing piece is used for providing a mixing channel of the mixer, a port at one end of the mixing piece corresponds to the jet orifice, so that the sprayed spray enters the mixing channel from the port, the periphery of the side surface of the mixing channel from the port is provided with a hole structure, the side surface of the mixing channel is communicated with the air inlet, and the waste gas enters the mixing channel from the side surface of the mixing channel through the hole structure.

In one or more embodiments of the mixer, the mixing member includes a conical section, the hole structure includes a porous wall surface of the conical section, and a port of a small end of the conical section corresponds to the ejection port.

In one or more embodiments of the mixer, the porous wall of the conical section comprises a first porous region, a second porous region, the first porous region being closer to the small end of the conical section than the second porous region, the pores of the first porous region having a pore size smaller than the pores of the second porous region, the pores of both the first porous region and the second porous region having an equivalent diameter of less than 12 mm.

In one or more embodiments of the mixer, the porous structure further comprises a porous baffle plate disposed adjacent to a side of the conical section where the porous wall faces the inlet, such that the exhaust gas passes through the porous baffle plate and then passes through the porous wall to enter the mixing channel.

In one or more embodiments of the mixer, the porous region of the porous baffle is aligned with the length of the porous wall of the conical section.

In one or more embodiments of the mixer, the mixer further comprises a partition dividing a space inside the housing into a first chamber and a second chamber, the first chamber comprising the gas inlet and the second chamber comprising the gas outlet, the first and second chambers being communicated through a communication port of the partition; and the port at the other end of the mixing piece corresponds to the communication port.

In one or more embodiments of the mixer, the partition includes a first plate body located at one side of the mixing part, a second plate body located at the other side of the mixing part, and a third plate body connecting the first plate body and the second plate body, the third plate body having the communication port, the mixing part including a mixing part connection section welded to the third plate body; the porous baffle of the mixing piece comprises a porous baffle connecting section which is welded with the third plate body.

In one or more embodiments of the mixer, the first plate, the second plate, and the third plate of the partition have a stepped structure, and the first plate and the second plate vertically extend in opposite directions from the third plate, respectively.

In one or more embodiments of the mixer, the ports at the two axial ends of the housing are the air inlet and the air outlet, respectively, and the injection port is disposed on the side wall of the housing.

According to the utility model discloses an engine exhaust after treatment system of an aspect, including as above any one the blender, and the sprayer, the sprayer corresponds the jet installation makes the urea solution spraying that the sprayer sprays follow the port of the one end of mixing member gets into the mixing channel.

In one or more embodiments of the exhaust gas after-treatment system, the exhaust gas after-treatment system is an in-line exhaust gas after-treatment system or a U-shaped exhaust gas after-treatment system.

The utility model discloses an advance effect includes but is not limited to, through have the hole structure in the periphery of the side that the mixing channel rises from this port, make waste gas get into the mixing channel from the side of mixing channel all around comparatively evenly, avoid waste gas direct to get into the spray that strikes the spraying that just got into the mixing channel from the side of mixing channel, and avoid most waste gas direct to get into the mixing channel from the side of mixing channel and the position that is closest to the air inlet, improved the mixing homogeneity in waste gas and urea spraying in the blender, make urea fully pyrolysis, reduce urea crystallization rate; the nitrogen oxide treatment of the engine exhaust gas post-treatment 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 block diagram of an engine exhaust aftertreatment system according to an embodiment.

Fig. 2 is a block diagram of the engine exhaust aftertreatment system shown in fig. 1.

FIG. 3 is a schematic diagram of a mixer and eductor according to an embodiment.

FIG. 4 is a schematic view of a combination structure of a mixing element, a porous baffle, and a partition of the mixer according to an embodiment.

Fig. 5 is a schematic structural view of a mixing part of the mixer of the embodiment.

FIG. 6 is a schematic diagram of the structure of the perforated baffle of the mixer of an embodiment.

FIG. 7 is a schematic view of a structure of a partition of the mixer of the embodiment.

Reference numerals:

100-exhaust gas aftertreatment system

101-diesel oxidation catalyst

102-diesel particulate trap

103-selective catalytic reduction reactor

1-Mixer

11-shell

C1-first Chamber

C2-second Chamber

111-air intake

112-air outlet

113-mounting base

12-hybrid part

T-hybrid channel

120-conical section

1201-porous wall

12011-first porous region

12012-second porous region

1202-Small end

121. 122-port

123-hybrid connection segment

13-hole structure

131-porous baffle

1310-porous region

1311 porous baffle connecting section

14-separating element

140-communication port

141-first plate body

142-second plate body

143-third plate body

2-ejector

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 2, in one embodiment, the exhaust aftertreatment system 100 may be an in-line configuration, i.e., an in-line exhaust aftertreatment system. The Catalytic converter comprises a Diesel Oxidation Catalyst 101 (DOC), a Diesel Particulate Filter 102 (DPF), a mixer 1 and a Selective Catalytic Reduction reactor 103 (SCR) which are sequentially distributed from upstream to downstream in an axial direction. The diesel oxidation catalyst and the diesel particulate trap described above are terms commonly used in the art, but are not limited to DOC and DPF, which can only be used in exhaust gas after-treatment systems of diesel engines. Referring to fig. 1 and 2, the exhaust gas sequentially passes through a diesel oxidation catalyst 101 to treat unburned hydrocarbon and carbon monoxide in the exhaust gas, a diesel particulate trap 102 treats particulate pollutants in the exhaust gas and then enters a mixer 1 to be mixed with the urea solution sprayed by an injector 2, the mixed gas flow flows out of the mixer 1 and then enters a selective catalytic reduction reactor 103, and the mixed gas flow is subjected to a reduction reaction under the action of a catalyst to generate nitrogen and water to treat nitrogen oxides in the exhaust gas. It is to be understood that the exhaust aftertreatment system 100 is not limited to that described above, and that the particulate trap 102 may be omitted, for example, in some exhaust aftertreatment systems. The exhaust gas aftertreatment system is not limited to the in-line configuration shown in the drawing, and may be, for example, a U-shaped configuration in which one side of the mixer 1 is connected approximately vertically to the diesel particulate trap 102 and the diesel oxidation catalyst 101, and the other side is connected approximately vertically to the selective catalytic reduction reactor 103.

As shown in fig. 3, the mixer 1 comprises a housing 11 and a mixing element 12 located inside the housing 11. The housing 11 has an air inlet 111, an air outlet 112 and an injection port (not visible in the figure due to the view angle of the drawing) of the mixer 1. The axial two ends of the housing 11 are respectively an air inlet 111 and an air outlet 112, and the jet orifice is arranged on the side wall of the housing 11.

Exhaust gas enters from the inlet 111, mixes with the urea spray in the mixing element 12 and exits from the outlet 112. As shown in fig. 3, the injection port is provided with a mounting seat 113, the injector 2 is provided on the mounting seat 113, and urea spray is injected into the mixer, that is, the injector 2 is attached to the injection port. The mixing element 12 provides a mixing channel T for the urea spray and the exhaust gases. As shown in fig. 3 to 5, a port 121 at one end of the mixing piece 12 corresponds to an injection port so that urea spray injected from the injector 2 enters the mixing passage T from the port 121, the mixing passage T has a hole structure 13 on the periphery of the side surface from the port 121, the side surface of the mixing passage communicates with the intake port 111, and as shown in fig. 4, the flow direction of exhaust gas is exemplified by the direction of an arrow, and the exhaust gas enters the mixing passage T from the side surface of the mixing piece 12, i.e., the side surface of the mixing passage T, through the hole structure 13.

This has the advantage that, by having a hole structure 13 at the periphery of the side of the mixing channel from the port, so that the waste gas can enter the mixing channel T more uniformly from the periphery of the side surface of the mixing channel, the waste gas flow is prevented from directly entering the urea spray jet which impacts the urea spray jet just sprayed into the mixing channel from the side surface of the mixing channel, and to avoid that a large part of the exhaust gases enters the mixing channel directly from the side of the mixing channel closest to the inlet opening, so that the urea spray is fully extended and uniformly mixed with the surrounding waste gas, the mixing uniformity of the waste gas and the urea spray in a mixer is improved, the urea is fully pyrolyzed, the crystallization rate of the urea is reduced, in addition, because the exhaust gas and the urea are uniformly and fully mixed in a spraying manner and the urea is fully pyrolyzed, the nitrogen oxide treatment of the SCR of the engine exhaust gas post-treatment system is efficient, and the emission of the engine exhaust gas post-treatment system is less.

With continued reference to fig. 3, 4, and 5, in some embodiments, the mixing member 12 may include a conical section 120, the hole structure 130 includes a porous wall 1201 of the conical section 120, and the port of the small end 1202 of the conical section 120 corresponds to the injection port, i.e., the urea spray injected by the injector 2 enters the mixing channel from the port of the small end 1202 of the conical section 120, and the conical section structure may be adapted to extend the spray of urea spray to promote sufficient mixing of the exhaust gas and the urea spray.

With continued reference to FIG. 5, in one embodiment, the tapered section 120 may further include a perforated wall 1201 that includes a first perforated region 12011 and a second perforated region 12012, the first perforated region 12011 being closer to the small end 1202 of the tapered section than the second perforated region 12012, the first perforated region 12011 having smaller apertures than the second perforated region 12012, so as to reduce the risk of back pressure increase that may result from the perforated region while ensuring uniformity of mixing, i.e., the first perforated region 12011 closer to the small end 1202 is closer to the initial stage of the urea spray entering the mixing section 12, the first perforated region 12011 having smaller apertures may better prevent the exhaust from directly impacting the spray and may cause the exhaust to more uniformly mix with the urea spray from all around, and the urea spray may already partially mix with the exhaust when it reaches the corresponding second perforated region 12012, the pore size of the second porous region 12012 may be increased relative to the first porous region 12011 as appropriate to reduce exhaust backpressure. Generally, the equivalent diameters of the holes of the first porous region 12011 and the second porous region 12012 are smaller than 12mm to ensure the effect of preventing the exhaust gas from impacting the spray, where the "equivalent diameter" refers to the area of the holes corresponding to the diameter, the structure of the holes may be holes of other shapes besides circular holes, the length ratio of the first porous region 12011 and the second porous region 12012, and the minimum diameter of the holes may be flexibly determined according to the specific mixing effect, back pressure, and other factors, and the optimal value may be determined by simulation, experiment, and the like.

Referring to fig. 3-6, in some embodiments, the porous structure 13 may include a porous baffle 131 in addition to the porous wall 1201 of the conical section 120, and the porous baffle 131 is disposed adjacent to the side of the porous wall 1201 of the conical section facing the gas inlet 111, such that the exhaust gas passes through the porous baffle 131 and then passes through the porous wall 1201 to enter the mixing channel. It will be appreciated that the provision of the perforated baffle 131 further reduces the impact of the exhaust gas on the spray. It should be noted that although the hole structure 130 of the embodiment shown in fig. 3 to 6 includes the porous baffle 131 and the porous wall 1201, the porous baffle 131 may be omitted according to practical situations, for example, the holes of the porous wall 1201 are dense enough and uniform, the hole diameter is small enough to meet practical requirements of preventing impact and mixing uniformly, and in this case, the porous baffle 131 is not needed. If the need for preventing impact and mixing uniformity is further increased, a perforated baffle 131 may be added to further optimize the effect. Additionally, referring to fig. 3 and 4, the porous region 1310 of the porous baffle 131 is aligned with the length of the porous wall 1201 of the tapered section 120, it being understood that alignment herein means substantially the same, not strictly aligned. This allows for easier assembly of the mixer 1, with the porous baffle 131 and the conical section 120 positioned such that the porous region 1310 and the porous wall 1201 are aligned during assembly. However, it will be understood by those skilled in the art that the relative positional relationship between the porous region 1310 and the porous wall 1201 is not limited to alignment, and the mixing effect of the exhaust gas and the urea spray can be adjusted by changing the positional relationship between the two.

Referring to fig. 3 to 7, in one or more embodiments, the mixer 1 further includes a partition 14 disposed inside the housing 11, as shown in fig. 3, the partition 14 may be welded to an inner wall surface of the housing 11, the partition 14 divides a space inside the housing 11 into a first chamber C1 and a second chamber C2, the first chamber C1 includes an air inlet 111, the second chamber C2 includes an air outlet 112, and the first chamber C1 and the second chamber C2 are communicated through a communication port 140 of the partition 14; the port 122 at the other end of the mixing member 12 corresponds to the communication port 140, that is, the exhaust gas enters the mixing member from the first chamber C1, and the mixed gas flow in which the exhaust gas and the urea spray are mixed is output from the port 122 at the other end of the mixing member 12 to the second chamber C2 through the communication port 140 to be output from the gas outlet 112. The provision of the partition member has an advantageous effect in that almost all of the exhaust gas flows into the interior of the mixer element 12 from the side, and the mixed gas flow also flows out from the gas outlet 112 almost entirely, reducing flow loss of the exhaust gas flow and the mixed gas flow due to reverse flow of the gas flow and the like.

With continued reference to fig. 3-7, in some embodiments, the specific structure of the partition 14 may include a first plate body 141 on one side of the mixing piece 12, a second plate body 142 on the other side of the mixing piece 12, and a third plate body 143 connecting the first plate body 141 and the second plate body 142, the third plate body 143 having a communication port 140, the mixing piece 12 including a mixing piece connecting section 123 welded with the third plate body 143; porous baffle 131 of mixing element 12 includes a porous baffle attachment section 1311, which is welded to third plate 143. This makes the mixer 1 easy to machine and assemble and structurally robust. In addition, as shown in fig. 4, the communication port 140 may further include a connection pipe to more firmly connect the mixing member 12 and the porous baffle 131. In some embodiments, as shown in fig. 7, the first plate 141, the second plate 142, and the third plate 143 may have a stepped structure, and the first plate 141 and the second plate 142 respectively vertically extend from the third plate 143 in opposite directions, so that the partition 14 is structurally stable. However, it will be understood by those skilled in the art that the specific structure of the partition 14 is not limited to the above step structure, and for example, the partition may be connected in a curve with smooth transition, and the first plate 141, the second plate 142, and the third plate 143 are connected to form a structure similar to an S-shape.

As can be seen from the above, the mixer and the exhaust gas aftertreatment system introduced by the above embodiments have the beneficial effects that, by having the hole structure at the periphery of the side surface of the mixing channel from the port, the exhaust gas enters the mixing channel more uniformly from the periphery of the side surface of the mixing channel, the exhaust gas is prevented from directly entering the spray beam impacting the spray just entering the mixing channel from the side surface of the mixing channel, and most of the exhaust gas is prevented from directly entering the mixing channel from the side surface of the mixing channel closest to the air inlet, so that the mixing uniformity of the exhaust gas and the urea spray in the mixer is improved, the urea is fully pyrolyzed, and the urea crystallization rate is reduced; the nitrogen oxide treatment of the engine exhaust gas post-treatment system adopting the mixer is efficient and has 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 (11)

1. A mixer for an exhaust aftertreatment system, comprising:

a housing having an air inlet, an air outlet, and a jet orifice; and

the mixing piece is used for providing a mixing channel of the mixer, a port at one end of the mixing piece corresponds to the jet orifice, so that the sprayed spray enters the mixing channel from the port, the periphery of the side surface of the mixing channel from the port is provided with a hole structure, the side surface of the mixing channel is communicated with the air inlet, and the waste gas enters the mixing channel from the side surface of the mixing channel through the hole structure.

2. The mixer of claim 1 wherein the mixing element includes a conical section and the hole structure includes a porous wall of the conical section, the port at the small end of the conical section corresponding to the jet orifice.

3. The mixer of claim 2 wherein the porous wall of the conical section comprises a first porous region, a second porous region, the first porous region being closer to the small end of the conical section than the second porous region, the pores of the first porous region having a pore size smaller than the pores of the second porous region, the equivalent diameters of the pores of the first and second porous regions each being less than 12 mm.

4. The mixer of claim 2 wherein the cell structure further comprises a porous baffle disposed adjacent a side of the porous wall of the conical section facing the inlet such that exhaust gas passes through the porous baffle and then through the porous wall into the mixing channel.

5. The mixer of claim 4, wherein the porous region of the porous baffle is aligned with the length of the porous wall of the conical section.

6. The mixer according to any one of claims 1 to 5, further comprising a partition dividing a space inside the housing into a first chamber including the gas inlet and a second chamber including the gas outlet, the first and second chambers communicating through a communication port of the partition; and the port at the other end of the mixing piece corresponds to the communication port.

7. The mixer of claim 6, wherein the divider comprises a first plate on one side of the mixing element, a second plate on the other side of the mixing element, and a third plate connecting the first and second plates, the third plate having the communication port, the mixing element comprising a mixing element connecting section welded to the third plate; the porous baffle of the mixing piece comprises a porous baffle connecting section which is welded with the third plate body.

8. The mixer of claim 7, wherein the first, second and third plates of the divider are stepped, the first and second plates extending perpendicularly in opposite directions from the third plate, respectively.

9. The mixer according to claim 1, wherein the ports at both axial ends of the housing are the air inlet and the air outlet, respectively, and the injection port is provided in a side wall of the housing.

10. An exhaust gas after-treatment system comprising the mixer according to any one of claims 1 to 9, and an injector installed corresponding to the injection port such that a urea solution spray injected by the injector enters the mixing passage from a port at one end of the mixing member.

11. The exhaust aftertreatment system of claim 10, wherein the exhaust aftertreatment system is an in-line exhaust aftertreatment system or a U-shaped exhaust aftertreatment system.

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