Two-stage mixer

Abstract

A two-stage mixer can include a directing element and a mixing element. The directing element can be configured to be fixedly mounted to an interior of an exhaust duct. The mixing element can be configured to be fixedly mounted to the interior of the exhaust duct in a location downstream of the directing element. The mixing element can include a center disc, a plurality of mounting arms extending radially from the center disc, and a plurality of vanes extending radially from the center disc. At least one mounting arm of the plurality of mounting arms can include a fin extending therefrom, and at least one vane of the plurality of vanes can include a fin extending therefrom.

Description

Technical Field

[0001] The present invention generally relates to a mixer for two or more fluids, and for example to a two-stage mixer for homogenizing the flow of two or more fluids in an exhaust aftertreatment system. Background Technology

[0002] In the exhaust aftertreatment system, a reducing agent injector introduces a reducing agent (e.g., urea solution, anhydrous ammonia, ammonia water, and / or the like) into the exhaust manifold, which directs the exhaust flow from the engine to the Selective Catalytic Reduction (SCR) module. Once the exhaust flow enters the SCR module, the reducing agent selectively reacts with nitrogen oxides (NOx) in the exhaust flow to convert NOx into other compounds that meet emission standards, such as nitrogen dioxide (N2), water (H2O), carbon dioxide (CO2), and / or the like.

[0003] However, once the reducing agent is introduced into the exhaust stream, it tends to settle onto the surfaces of the exhaust pipe and, over time, may form crystalline deposits that impede the flow of exhaust gas. Furthermore, the reducing agent introduced by the reducing injector tends to mix non-uniformly with the exhaust stream, which can cause unwanted compounds to pass through the SCR module. For example, because the exhaust stream contains too little reducing agent in some sections, the exhaust aftertreatment system may emit excessive amounts of nitrogen oxides and therefore fail to meet emission standards. As a further example, because the exhaust stream contains excessive reducing agent in other sections, the exhaust aftertreatment system may emit unreacted ammonia (NH3), commonly referred to as an ammonia leak.

[0004] Korean Patent KR 101717603 B1 (“'603 Patent”) discloses an attempt to improve the performance of an exhaust aftertreatment system, which was granted to Song Il Hwan on April 5, 2017. Specifically, the '603 Patent discloses a mixer device for distributing a reducing agent before exhaust gas enters an SCR device. The mixer device includes a housing portion and a mixing unit disposed inside the housing portion. The mixing unit has an inner tube, an outer tube, a first blade portion disposed between the outer tube and the housing portion, and a second blade portion disposed between the inner tube and the outer tube. One or more support portions may also be provided to connect the inner and outer tubes to each other and support them on the inner circumferential side of the housing portion. For example, the support portions may be divided into vertical support portions supporting in the longitudinal direction and horizontal support portions supporting in the transverse direction.

[0005] The two-stage mixer of the present invention is intended to overcome one or more of the above-mentioned problems. Summary of the Invention

[0006] In some implementations, the two-stage mixer includes a guide element configured to be fixedly mounted inside an exhaust duct; and a mixing element configured to be fixedly mounted inside the exhaust duct at a location downstream of the guide element. The mixing element includes: a central disk; a plurality of mounting arms extending radially from the central disk, wherein each of the plurality of mounting arms has a first side edge having a first length, and wherein at least one of the plurality of mounting arms has a fin extending from the first side edge; and a plurality of blades extending radially from the central disk, wherein each of the plurality of blades has a second side edge having a second length less than the first length, and wherein at least one of the plurality of blades has a fin extending from the second side edge.

[0007] In some implementations, the two-stage mixer includes an exhaust duct having an interior; a guide element fixedly mounted to the interior of the exhaust duct, the guide element comprising a planar body; and a mixing element fixedly mounted to the interior of the exhaust duct at a location downstream of the guide element, the mixing element comprising: a central disk; a plurality of mounting arms extending radially from the central disk and fixedly fastened to the interior of the exhaust duct, wherein each of the plurality of mounting arms has a first side edge and a plurality of blades, the first side edge having a first fin extending therefrom, the plurality of blades extending radially from the central disk, wherein each of the plurality of blades has a second side edge, the second side edge having a second fin extending therefrom.

[0008] In some implementations, the exhaust aftertreatment system includes a reducing agent injector configured to inject a reducing agent into an exhaust stream; a guiding element configured to be disposed within the exhaust stream to separate and guide the reducing agent droplets along the exhaust stream; and a mixing element configured to be disposed downstream of the exhaust stream and spaced apart from the guiding element to distribute the droplets within the exhaust stream, the mixing element including: a central disk, a plurality of mounting arms extending radially from the central disk and having a first length, and a plurality of blades extending radially from the central disk and having a second length less than the first length. Attached Figure Description

[0009] Figure 1 This is a diagram of an exemplary power system.

[0010] Figure 2 yes Figure 1 A perspective view of the two-stage mixer of the power system.

[0011] Figure 3 yes Figure 2 A front view of a two-stage mixer.

[0012] Figure 4 yes Figure 2A top view of a two-stage mixer.

[0013] Figure 5 yes Figure 2 A side view of a two-stage mixer. Detailed Implementation

[0014] This invention relates to a two-stage mixer applicable to any system involving the mixing of two or more fluids. For example, the system can be a power system, an exhaust aftertreatment system, etc. The system can be implemented in vehicles, such as motor vehicles, rail vehicles, ships, aircraft, and / or the like.

[0015] To simplify the following description, the same reference numerals may be used to denote the same features. The figures may not be drawn to scale.

[0016] Figure 1 This is a diagram of an exemplary powertrain 100. The powertrain 100 includes an engine 102 and an exhaust aftertreatment system 104 fluidly connected via an exhaust manifold 106. The engine 102 may be an internal combustion engine, such as a diesel engine, a gasoline engine, and / or the like. The engine 102 is configured to discharge exhaust gas into the exhaust manifold 106 to form an exhaust stream. The exhaust stream may include emission compounds such as nitrogen oxides (NOx), particulate matter, hydrocarbons, and / or the like.

[0017] An exhaust aftertreatment system 104, located downstream of engine 102, is configured to reduce or remove emission compounds in the exhaust stream to meet emission standards. To treat NOx in the exhaust stream, exhaust aftertreatment system 104 includes a reductant delivery module 108, an SCR module 110, and a two-stage mixer 112 therebetween. In some implementations, exhaust aftertreatment system 104 may further include a diesel particulate filter (DPF) to treat particulate matter in the exhaust stream, and / or a diesel engine oxidation catalyst (DOC) to treat hydrocarbons in the exhaust stream.

[0018] The reducing agent delivery module 108 includes a storage tank 114, a reducing agent injector 116, and a pump 118 fluidly connected therebetween. The storage tank 114 is configured to store a reducing agent therein. The reducing agent is a fluid configured to react with NOx in the exhaust stream to convert NOx into other compounds, such as nitrogen dioxide (N2), water (H2O), carbon dioxide (CO2), and / or the like. For example, the reducing agent may be a urea solution (e.g., diesel exhaust fluid (DEF)), anhydrous ammonia, ammonia water, etc.

[0019] Pump 118 is configured to pressurize the reducing agent and deliver it from tank 114 to reducing agent injector 116 at a flow rate substantially proportional to the exhaust flow velocity. Reducing agent injector 116 is fixedly mounted on exhaust duct 106 and configured to distribute the reducing agent from tank 114 into the exhaust flow via an inlet in exhaust duct 106. The reducing agent can enter the exhaust flow in a direction 120 substantially perpendicular to the flow direction 122 of the exhaust flow.

[0020] The SCR module 110, located downstream of the inlet, includes a catalyst configured to receive the exhaust flow and reduce the NOx concentration therein. To allow the exhaust flow to pass through, the SCR module 110 may have a honeycomb or other porous structure. This will be discussed below. Figure 2-5 The two-stage mixer 112, described in detail, is fixedly installed in the exhaust pipe 106 between the engine 102 and the SCR module 110. The two-stage mixer 112 is configured to mix the reducing agent supplied by the reducing agent injector 116 with the exhaust flow before the exhaust flow enters the SCR module 110.

[0021] As mentioned above, providing Figure 1 As an example, other examples may differ from those regarding... Figure 1 The described instance. Figure 1 The number and arrangement of the devices shown are provided as examples. In reality, with Figure 1 Compared to the device shown, there can be additional devices, fewer devices, different devices, or devices with different configurations. Furthermore, it can be implemented within a single device. Figure 1 The two or more devices shown, or can Figure 1 The single device shown can be implemented as multiple distributed devices. For example, the reducing agent delivery module 108 may include multiple reducing agent injectors to distribute the reducing agent into the exhaust stream.

[0022] Figure 2-5 This is a diagram of a two-stage mixer 112 located within a portion of the exhaust duct 106. Figure 2 This is a perspective view of the two-stage mixer 112. Figure 3 This is a front view of the two-stage mixer 112. Figure 4 This is a top view of the two-stage mixer 112. Figure 5 This is a side view of the two-stage mixer 112.

[0023] like Figure 2-5As shown, the two-stage mixer 112 includes a guide element 202 and a mixing element 204 fixedly mounted to the interior 206 of the exhaust duct 106. The guide element 202 is configured and disposed within the exhaust duct 106 to facilitate a first-stage mixing of the reducing agent with the exhaust flow. The first stage of mixing includes breaking down the droplets of the reducing agent and guiding the droplets toward the mixing element 204. The mixing element 204 is configured and disposed within the exhaust duct 106 to facilitate a second-stage mixing of the reducing agent with the exhaust flow. The second-stage mixing includes further breaking down the droplets of the reducing agent and generating eddies and tumbling motions in the exhaust flow to uniformly mix the reducing agent with the exhaust.

[0024] The guide element 202 includes a planar body 208 having a plurality of mounting tabs 210 extending therefrom for attachment to an exhaust duct 106. The planar body 208 includes an upper surface 212, a lower surface 214, and an outer peripheral surface 216 connecting the upper surface 212 to the lower surface 214. The outer peripheral surface 216 includes a first side 218, a second side 220, a third side 222, and a fourth side 224. The first side 218 of the outer peripheral surface 216 is integrally connected to a first subset of the plurality of mounting tabs 210. The third side 222 of the outer peripheral surface 216, opposite the first side 218, is integrally connected to a second subset of the plurality of mounting tabs 210. The plurality of mounting tabs 210 are securely attached to the interior 206 of the exhaust duct 106 (e.g., by welding, brazing, and / or similar methods).

[0025] Although four mounting tabs are shown (e.g., in...) Figure 4 (In the context of the text, this seems to be a fragmented and nonsensical collection of characters. A more accurate translation would require the full context.)

[0026] To receive and break up the microdroplets of reducing agent injected into the exhaust stream, the guide element 202 is aligned with the reducing agent injector 116. For example, as Figure 2 and 5 As shown, the fourth side 224 of the guide element 202 can be positioned closer to the reducing agent injector 116 than the second side 220 of the guide element 202. To guide the microdroplets of the reducing agent toward the central portion of the mixing element 204, the guide element 202 is disposed within the exhaust duct 106 such that the first side 218 and the third side 222 extend in a direction substantially parallel to the central axis 226 of the exhaust duct 106. Furthermore, as... Figure 2 and 5As shown, the guide element 202 can be positioned closer to the lower side of the exhaust pipe 106, such that the central axis 226 of the exhaust pipe 106 is located between the reducing agent injector 116 and the guide element 202.

[0027] The guide element 202 can be formed from a single integral piece of a corrosion-resistant material (e.g., stainless steel). Figure 4 As shown, to securely fix it within the exhaust duct 106, the width "W" of the guide element 202 is in the range of approximately 60% to approximately 100% of the diameter "D" of the exhaust duct 106. In some implementations, the width "W" of the guide element 202 can be in the range of approximately 80% to approximately 95% of the diameter "D" of the exhaust duct 106. In some implementations, to deflect the microdroplets of the reducing agent toward the mixing element 204 while also preventing the formation of deposits on the guide element 202, the length "L" of the guide element 202 is substantially equal to the diameter "D" of the exhaust duct 106. For example, if the diameter "D" of the exhaust duct 106 is 5 inches, the width "W" of the guide element 202 can be approximately 4.5 inches, and the length "L" of the guide element 202 can be approximately 5 inches. Other sizes and shapes of the guide element 202 are also possible.

[0028] like Figure 2-5 As further shown, the hybrid element 204 includes a central disk 228 having a plurality of mounting arms 230 and a plurality of blades 232 extending radially therefrom. The central disk includes a front surface 234, a rear surface 236, and a circumferential surface 238 connecting the front surface 234 to the rear surface 236. The plurality of mounting arms 230 are substantially equidistantly spaced around the circumferential surface 238 of the central disk 228. The plurality of blades 232 are substantially equidistantly spaced around the circumferential surface 238 of the central disk 228 and are circumferentially offset from the plurality of mounting arms 230. Thus, when viewed from a direction facing the front surface 234 of the central disk 228, the plurality of mounting arms 230 and the plurality of blades 232 are alternately arranged around the circumferential surface 238 of the central disk 228.

[0029] For descriptive purposes, the structure of a single mounting arm 230 and a single blade 232 of the hybrid element 204 is described below. However, it should be understood that each mounting arm may have the same or similar structure as the mounting arm 230 described below. Similarly, each blade may have the same or similar structure as the blade 232 described below.

[0030] The mounting arm 230 has a first side edge 240, a second side edge 242, and an outer edge 244 connecting the first side edge 240 to the second side edge 242. The first side edge 240 is integrally connected to a first fin 246, which extends slightly toward the adjacent blade 232. Figure 4As shown, in order to generate vortices and / or tumbling motion in the exhaust flow, fins 246 are bent at an angle "α" relative to the mounting arm 230 in the flow direction 122 of the exhaust flow. Angle "α" can range from approximately 0 degrees to approximately 90 degrees. In some implementations, angle "α" can range from approximately 20 degrees to approximately 40 degrees. For example... Figure 3 As shown, the first side edge 240 and the second side edge 242 have a first length "L1" that allows the mounting arm 230 to be securely fixed to the exhaust pipe 106. The outer edge 244 is fixedly attached to the interior 206 of the exhaust pipe 106 by welding, brazing, or the like.

[0031] Blade 232 has a first side edge 248, a second side edge 250, and an outer edge 252 connecting the first side edge 248 to the second side edge 250. The first side edge 248 is integrally connected to a second fin 254, which extends slightly toward the adjacent mounting arm 230. Similar to what has been described above with respect to the first fin 246, the second fin 254 is bent at an angle “α” relative to blade 232 in the flow direction 122 of the exhaust flow. Figure 3 As shown, in order to minimize flow restriction, the first side edge 248 and the second side edge 250 have a second length "L2" that is less than the first length "L1" of the mounting arm 230.

[0032] Although the mixing element 204 is shown as having three mounting arms 230 with three corresponding first fins 246 and three blades 232 with three corresponding second fins 254, it should be understood that the mixing element 204 may have different numbers of mounting arms, first fins, blades, and second fins (e.g., four, five, and / or the like). In some implementations, the guide element 204 may have a simplified design (e.g., with fewer or no fins, fewer or no blades, and / or the like). Furthermore, although the first fins 246 and second fins 255 are shown extending counterclockwise around the central disk 228 (e.g., when viewed from a direction facing the front surface 234 of the central disk 228), it should be understood that the first fins 246 and second fins 254 may extend clockwise around the central disk 228 (e.g., by alternatively providing them on the second side edges 242 and 250).

[0033] To ensure uniform mixing of the reducing agent with the exhaust flow, a mixing element 204 is mounted within the exhaust duct 106 such that the front surface 234 of the central disk 228 is substantially perpendicular to the upper surface 212 of the planar body 208 of the guide element 202. In this position, the mixing element 204 is configured to deflect a portion of the exhaust flow, thereby generating turbulence in the airflow, which accelerates the formation of ammonia. To allow the reducing agent to disperse throughout the cross-section of the exhaust duct 106, the mixing element 204 is positioned downstream of the guide element 202 to define a gap 256 between the second side 220 of the guide element 202 and the front surface 234 of the central disk 228. The length “L3” of the gap 256 ranges from approximately 10% to approximately 200% of the diameter “D” of the exhaust duct 106. For example, if the diameter “D” of the exhaust duct 106 is 5 inches, the length “L3” of the gap 256 can range from approximately 0.5 inches to approximately 10 inches.

[0034] The hybrid element 204 is integrally formed from a single piece of corrosion-resistant material (e.g., stainless steel). The center disk 228, multiple mounting arms 230, and multiple blades 232 can be substantially planar. Other sizes and shapes of the hybrid element 204 are also possible.

[0035] As mentioned above, providing Figure 2-5 As an example, other examples may differ from those regarding... Figure 2-5 The described instance. Figure 2-5 The number and arrangement of components shown are provided as an example. In reality, with... Figure 2-5 Compared to those shown, there may be additional components, fewer components, components of different shapes, components of different sizes, or components with different configurations. For example, the center disc 228 may have a polygonal shape (e.g., hexagonal) instead of a circular shape. As another example, the multiple mounting arms 230 and / or the multiple blades 232 may be substantially rectangular in shape rather than tapered.

[0036] Industrial applicability

[0037] The two-stage mixer 112 of the present invention is particularly suitable for systems used to mix two or more fluids, such as exhaust aftertreatment system 104. Exhaust aftertreatment system 104 can be implemented in vehicles propelled by internal combustion engines, such as motor vehicles, rail vehicles, ships, aircraft and / or the like.

[0038] Due to its structure and arrangement relative to the reducing agent injector 116, the two-stage mixer 112 offers several advantages. For example, because the two-stage mixer 112 is positioned within the exhaust duct 106 to deflect and redirect the reducing agent droplets as they enter the exhaust flow, it suppresses the formation of deposits within the exhaust aftertreatment system 104. Consequently, the two-stage mixer 112 is configured to prevent flow blockage of the exhaust flow, which could potentially damage the exhaust aftertreatment system 104. Furthermore, the two-stage mixer 112 is capable of uniformly mixing the reducing agent with the exhaust flow under varying conditions. For example, the two-stage mixer 112 is effective under high flow conditions (e.g., an exhaust flow velocity of approximately 11,800 kg / hr and a reducing agent velocity of approximately 31 kg / hr) and low flow conditions (e.g., an exhaust flow velocity of approximately 2,000 kg / hr and a reducing agent velocity of approximately 6 kg / hr), in linear sections of the exhaust duct 106, in curved sections of the exhaust duct 106, and so on. In addition, due to its simple design, the two-stage mixer 112 is cost-effective, easy to manufacture and install, and easy to adjust to suit different applications.

[0039] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise forms disclosed. Modifications and variations can be made based on the foregoing disclosure, or can be derived from practice of the implementations. Furthermore, any implementations described herein can be combined unless the foregoing disclosure expressly provides for reasons why one or more implementations cannot be combined. Although specific combinations of features are stated in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. While each dependent claim listed below may be directly subordinate to only one claim, the disclosure of various implementations includes combinations of each dependent claim with each other claim in the claim set.

[0040] As used herein, “a,” “an,” and “set” are intended to include one or more items and are interchangeable with “one or more.” Furthermore, as used herein, the article “described” is intended to include one or more items mentioned in conjunction with the article “described” and is interchangeable with “one or more.” Additionally, the phrase “based on” is intended to mean “at least partially based on,” unless otherwise expressly stated. Moreover, as used herein, the term “or,” when used in a series, is intended to be inclusive and is interchangeable with “and / or” unless otherwise expressly stated (e.g., if used in combination with “any one” or “only one”). Further, spatially relative terms such as “below,” “under,” “above,” “on top,” etc., may be used herein for descriptive purposes to describe the relationship of one element or feature to another element or feature as shown in the figures. Spatially relative terms are intended to include different orientations of the device, apparatus, or element in use or operation, other than those shown in the figures. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptors used in this paper may be interpreted accordingly.

Claims

1. A two-stage mixer comprising: Exhaust pipe; A guide element configured to be fixedly mounted inside the exhaust duct; as well as A mixing element configured to be fixedly mounted to the interior of the exhaust duct at a location downstream of the guide element, the mixing element comprising: Central plate, Multiple mounting arms extending radially from the central disk, Each of the plurality of mounting arms has a first side edge, the first side edge having a first length, and Multiple blades extending radially from the central disk, Each of the plurality of blades has a second side edge having a second length less than the first length; each of the plurality of mounting arms has a first fin extending from the first side edge, the first fin extending from the plurality of mounting arms at an angle ranging from 20 degrees to 40 degrees.

2. The two-stage mixer according to claim 1, wherein: The plurality of mounting arms are spaced substantially equidistant from each other around the circumferential surface of the central disk; and The plurality of blades are spaced substantially equidistantly around the circumferential surface of the central disk and are circumferentially offset from the plurality of mounting arms.

3. The two-stage mixer according to claim 1 or 2, wherein the guiding element comprises a planar body and has: The width of the exhaust pipe is within the range of 80% to 95% of its diameter; and The length is substantially equal to the diameter of the exhaust pipe.

4. The two-stage mixer according to claim 1 or 2, wherein: Each of the plurality of blades has a second fin extending from the second side edge.

5. The two-stage mixer according to claim 1 or 2, wherein: The guiding element and the mixing element are spaced apart along the exhaust pipe to define a gap therebetween; and The gap has a length ranging from 10% to 200% of the diameter of the exhaust pipe.

6. An exhaust aftertreatment system, comprising: A reducing agent injector configured to inject a reducing agent into an exhaust stream; A guiding element configured to be disposed within the exhaust flow to separate and guide the droplets of the reducing agent along the exhaust flow; as well as A mixing element configured to be positioned downstream of the exhaust flow and spaced apart from the guiding element to distribute the droplets within the exhaust flow, the mixing element comprising: Central plate, and A plurality of mounting arms extending radially from the central disk and having a first length, and A plurality of blades extending radially from the central disk and having a second length less than the first length; Each of the plurality of mounting arms has a first fin extending from the mounting arm along the flow direction of the exhaust flow, the first fin extending from the plurality of mounting arms at an angle ranging from 20 degrees to 40 degrees.

7. The exhaust aftertreatment system according to claim 6, further comprising: A selective catalytic reduction module configured to receive and process the exhaust stream after the droplets have been distributed within the exhaust stream by the mixing element.

8. The exhaust aftertreatment system according to claim 6 or 7, wherein, The central disk, the plurality of mounting arms, and the plurality of blades are substantially planar.

9. The exhaust aftertreatment system according to claim 6 or 7, wherein: Each of the plurality of blades has a second fin extending from the blade along the flow direction of the exhaust flow.

10. The exhaust aftertreatment system according to claim 9, wherein: The second fin extends from the plurality of blades at the angle stated.

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