Geometrically induced double-layer cyclone single-hole urea nozzle with simple processing process

Abstract

The application discloses a single-hole rotational flow urea nozzle with geometrically induced vortex line cavitation, which comprises a ball valve, a valve seat, a rotational flow sheet, a flow converging sheet, an outer shell and a hole plate, the valve seat is fixedly connected with the inner wall of the outer shell, an annular protrusion is arranged in the valve seat, a through hole is arranged in the middle of the annular protrusion and is communicated with both ends of the annular protrusion, a sealing ball is arranged at one end of the annular protrusion, and the sealing ball is fixed at one end of the ball valve; the ball valve is movably connected with the inner wall of the outer shell, and a gap for fluid flow is arranged between the ball valve and the outer shell; the other end of the annular protrusion is sequentially provided with the rotational flow sheet, the flow converging sheet and the hole plate, the rotational flow sheet is abutted against the annular protrusion, and a plurality of rotational flow channels which are inclined relative to the axis of the rotational flow sheet are arranged on the rotational flow sheet; and the flow converging sheet is provided with a flow converging channel. The rotational flow sheet provided with the rotational flow channels cooperates with the flow converging sheet, so that the spray cone angle is smaller and the spray is uniformly distributed in the circumferential direction under the working condition of determining the flow of the nozzle.

Description

Technical Field

[0001] This invention relates to the field of diesel engine exhaust aftertreatment technology, specifically a geometrically induced double-layer swirling single-hole urea nozzle with a simple manufacturing process. Background Technology

[0002] Selective catalytic reduction (SCR) systems remove NOx from exhaust gases by injecting a reducing agent containing ammonia into the exhaust pipe. The thoroughly mixed reducing agent and flue gas react in the SCR reactor under the action of a catalyst. Considering safety and economic factors, SCR systems typically use a 32.5% urea aqueous solution as the reducing agent, which is injected into the exhaust pipe through a swirl nozzle.

[0003] Swirl nozzles are mechanical atomizing nozzles that use pressure-driven, geometrically induced centrifugal swirl to create atomizing flow. They offer excellent atomization and are widely used in thermal power equipment. In aero-gas turbines, swirl nozzles are extensively used in the main combustion chamber as starting and operating nozzles to meet the requirements of low-speed, low-flow-rate conditions. With increasingly stringent emission regulations for internal combustion engines, swirl nozzles have also received widespread attention in gasoline direct injection systems and diesel engine exhaust aftertreatment systems to improve fuel efficiency and emission characteristics in automobiles. Furthermore, swirl nozzles have demonstrated strong applicability in numerous applications across various fields, including gas cooling, metal surface treatment, food processing, and plant protection.

[0004] Existing urea nozzles are difficult to achieve good atomization, resulting in uneven distribution and a large spray cone angle. When the urea solution is sprayed into the exhaust pipe, the sprayed urea is prone to hitting the pipe walls, forming a liquid film on the pipe walls, which in turn causes urea crystallization, clogging the exhaust pipe and causing excessive exhaust emissions. In severe cases, it can even damage the engine. Therefore, there is an urgent need to design a urea nozzle to solve this problem. Summary of the Invention

[0005] To address the problems of uneven urea nozzle distribution, large spray cone angle, and easy collision of urea spray with the pipe wall, forming a liquid film on the pipe wall and causing urea crystallization, a geometrically induced double-layer swirling single-hole urea nozzle with a simple processing technology is provided. By eccentrically connecting the swirling flow channel set obliquely downstream to the confluence cavity, a spray with a smaller spray cone angle and uniform circumferential distribution is obtained under the condition of a fixed nozzle flow rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A geometrically induced double-layer swirl single-orifice urea nozzle with a simple processing technology includes a ball valve, a valve seat, a swirl vane, a housing, and an orifice plate. The valve seat is sealed and fixed to the inner wall of the housing. An annular protrusion is provided inside the valve seat, with a through hole connecting both ends of the annular protrusion in the middle. A sealing ball is provided at one end of the annular protrusion and fixed to one end of the ball valve. The ball valve is movably connected to the inner wall of the housing, and a gap for fluid flow is provided between the ball valve and the housing. When the ball valve moves to the point where the sealing ball abuts against one end of the annular protrusion, the sealing ball seals the through hole in the middle of the annular protrusion. The other end of the annular protrusion... One end abuts against a swirl vane. The end of the swirl vane near the annular protrusion has multiple branch channels extending from the axis to the outer surface. The other end of the swirl vane has a confluence cavity that does not completely penetrate the swirl vane. The confluence cavity has multiple swirling channels extending to the outer surface of the swirl vane in the circumferential direction. The swirling channels are eccentrically connected to the confluence cavity. The depth of the swirling channels gradually decreases from the outer surface of the swirl vane to the confluence cavity. The outer surface of the swirl vane has multiple lateral channels connecting the branch channels and the swirling channels. The end of the swirl vane with the confluence cavity abuts against an orifice plate. The orifice plate has spray holes connecting the confluence cavity to the outside.

[0008] Furthermore, the ball valve is provided with a first positioning pin hole and a second positioning pin hole, and the space between the first positioning pin hole and the second positioning pin hole is perpendicular to each other. Positioning pins are pin-connected to both the first positioning pin hole and the second positioning pin hole, and there is a gap between the positioning pin and the inner wall of the outer shell.

[0009] Furthermore, the sealing ball has multiple planes parallel to the axis in the circumferential direction; the outer surface of the swirl vane has multiple axially penetrating notches to form a lateral flow channel.

[0010] Furthermore, a conical surface is provided at one end of the annular protrusion near the sealing ball, and the larger end of the conical surface on the annular protrusion is positioned directly opposite the sealing ball. When the sealing ball abuts against the conical surface on the annular protrusion, it seals the through hole in the middle of the annular protrusion.

[0011] Furthermore, the number of lateral flow channels, swirling flow channels, and split flow channels are equal, and the swirling flow channels are set directly opposite the split flow channels. Multiple swirling flow channels and split flow channels are evenly arranged on the swirling vanes.

[0012] Furthermore, the widths of the swirling channel and the branching channel are equal, and are 0.5-0.9 times the inner wall radius at the location where the swirling vane is installed on the valve seat.

[0013] Furthermore, the total area of ​​the radial cross-sections of the multiple lateral channels on the swirl vane is 10%-15% of the radial cross-section of the swirl vane.

[0014] Furthermore, a guide cavity is provided at one end of the swirl vane near the annular protrusion, which connects the flow distribution channel and the through hole in the middle of the annular protrusion, and multiple flow distribution channels converge in the guide cavity.

[0015] Furthermore, the swirling flow channel is tangent to the confluence cavity.

[0016] Furthermore, the number of lateral flow channels, swirling flow channels, and branch flow channels is set to 3-6.

[0017] The beneficial effects of this invention are:

[0018] In this invention, fluid enters the swirl vane's distribution channel through the central through-hole of the annular protrusion, and is evenly divided into multiple streams by the distribution channels. The divided fluid, located around the swirl vane, moves downstream under pressure, flowing through lateral channels into the swirl channels. The fluid flows through the swirl channels, which are angled downstream, and simultaneously achieves axial and circumferential tangential velocities when converging in the confluence cavity. After converging in the confluence cavity, it is directly ejected from the orifice plate, forming a hollow swirl with tangential velocity and a large initial axial velocity. The hollow swirl forms a hollow conical liquid film outside the nozzle; after the film breaks, a fine and evenly distributed swirl spray of droplets is obtained. Its overall flow channel is short, resulting in a stronger swirl effect and a smaller spray cone angle.

[0019] The lateral flow channel in this invention makes the fluid flow more uniform and stable, resulting in a more uniform distribution of droplets in the space during atomization and a smaller spray cone angle; it also reduces the energy loss of fluid flow, thereby enhancing the atomization effect and forming finer droplets.

[0020] The nozzle structure described in this invention is simple and easy to install and operate. Furthermore, both the first and second positioning pin holes in this invention are pin-connected with positioning pins. These positioning pins restrict the radial movement of the ball valve, preventing it from wobbling in the radial direction and affecting fluid flow. Additionally, a gap exists between the positioning pin and the inner wall of the outer casing, ensuring that the positioning pin does not restrict the axial movement of the ball valve. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the explosion of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention.

[0022] Figure 2 This is a cross-sectional view of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention.

[0023] Figure 3 This is a cross-sectional view of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention after the installation of the positioning pin.

[0024] Figure 4 This is a schematic diagram showing the connection between the geometrically induced double-layer swirling single-orifice urea nozzle valve seat, swirling vane, and orifice plate of the present invention.

[0025] Figure 5 This is a three-dimensional schematic diagram of the swirl vanes of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention. Figure 1 .

[0026] Figure 6 This is a three-dimensional schematic diagram of the swirl vanes of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention. Figure 2 .

[0027] Figure 7 This is a three-dimensional schematic diagram of the swirl vanes of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention. Figure 3 A portion of the image has been cut off.

[0028] Figure 8 This is a cloud diagram of the liquid phase volume fraction in the inner flow section of the geometrically induced double-layer swirling single-hole urea nozzle of the present invention.

[0029] Figure 9 This is a pressure cloud diagram of the inner flow section of the double-layer swirling single-hole urea nozzle of the present invention.

[0030] In the figure, 1. Ball valve, 11. First locating pin hole, 12. Second locating pin hole, 13. Sealing ball, 2. Valve seat, 21. Annular protrusion, 3. Swirl vane, 31. Diverting channel, 32. Swirl channel, 33. Guide cavity, 34. Merging cavity, 35. Lateral channel, 4. Outer shell, 5. Orifice plate, 51. Spray hole. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] like Figure 1-4As shown, the geometrically induced double-layer swirl single-hole urea nozzle of the present invention, with its simple processing technology, includes a ball valve 1, a valve seat 2, a swirl vane 3, a housing 4, and an orifice plate 5. The valve seat 2 is sealed and fixed to the inner wall of the housing 4. An annular protrusion 21 is provided inside the valve seat 2, and a through hole connecting the two ends of the annular protrusion 21 is provided in the middle of the annular protrusion 21. A sealing ball 13 is provided at one end of the annular protrusion 21 and is fixed to one end of the ball valve 1. The ball valve 1 is movably connected to the inner wall of the housing 4, and a gap for fluid flow is provided between the ball valve 1 and the housing 4. A conical surface is provided at the end of the annular protrusion 21 near the sealing ball 13, and the larger end of the conical surface on the annular protrusion 21 is positioned directly opposite the sealing ball 13. When the sealing ball 13 abuts against the conical surface on the annular protrusion 21, it seals the through hole in the middle of the annular protrusion 21. The other end of the ball valve 1 is connected to the solenoid valve (not shown in the diagram) and is used to control the lifting and lowering of the ball valve 1. When the ball valve 1 is seated, the sealing ball 13 abuts against the conical surface on the annular protrusion 21. The sealing ball 13 has multiple planes parallel to the axis in the circumferential direction to avoid collision or friction with the valve seat 2. The ball valve 1 is provided with a first positioning pin hole 11 and a second positioning pin hole 12, and the first positioning pin hole 11 and the second positioning pin hole 12 are spatially perpendicular to each other. Positioning pins are pinned to both the first positioning pin hole 11 and the second positioning pin hole 12. The positioning pins can restrict the radial movement of the ball valve 1, prevent the ball valve 1 from shaking in the radial direction, make the fluid flow more stable, and make the spray more stable. There is a gap between the positioning pin and the inner wall of the outer shell 4, so that the positioning pin does not restrict the axial movement of the ball valve 1.

[0033] The other end of the annular protrusion 21 abuts against the swirl vane 3, in combination. Figure 5-7As shown, the swirl vane 3 has multiple diversion channels 31 that extend from the axis to the outer surface at one end near the annular protrusion 21. The swirl vane 3 has a guide cavity 33 that connects the diversion channels 31 and the through hole in the middle of the annular protrusion 21 at one end near the annular protrusion 21. The multiple diversion channels 31 converge in the guide cavity 33. At the other end of the swirl vane 3, a confluence cavity 34 is provided, which does not completely penetrate the swirl vane 3. Multiple swirl channels 32 are uniformly arranged circumferentially in the confluence cavity 34, extending to the outer surface of the swirl vane 3. The swirl channels 32 are eccentrically connected to the confluence cavity 34, and the depth of the swirl channels 32 gradually decreases from the outer surface of the swirl vane 3 towards the confluence cavity 34, forming a downstream-sloping structure. This allows the fluid to simultaneously obtain axial velocity and circumferential tangential velocity. Furthermore, when some fluid flows along the downstream-sloping swirl channels 32, it flows along the downstream-sloping structure, reducing the impact between the fluid and the orifice plate 5, reducing energy loss in the fluid flow, and improving fluid flow stability, resulting in a smaller spray cone angle. When the swirl channels 32 are tangential to the confluence cavity 34, the fluid obtains a greater circumferential tangential velocity. Multiple axially penetrating notches are provided on the outer surface of the swirl vane 3, forming lateral channels 35 that connect the diversion channel 31 and the swirl channel 32. The total radial cross-sectional area of ​​the multiple lateral channels 35 on the swirl vane 3 is 10%-15% of the radial cross-sectional area of ​​the swirl vane 3. On the one hand, by setting the lateral channels 35 as notches axially penetrating the swirl vane 3 on the outer surface, the area of ​​the lateral channels 35 is guaranteed, making the fluid flow more uniform and stable when the fluid flows through the lateral channels 35. The more uniform and stable fluid flow results in a more uniform distribution of droplets in space during atomization, and the resulting spray cone angle is smaller. On the other hand, when the nozzle described in this invention is working, there is impact friction between the various parts, especially when the nozzle is started and stopped. The impact friction between the various parts will cause wear on the parts themselves and also lose the energy of the fluid flow. The notches on the swirl vane 3 reduce the contact area between the swirl vane 3 and the valve seat 2, which can reduce the wear between the swirl vane 3 and the valve seat 2, and at the same time reduce the energy loss of the fluid flow. The number of lateral flow channels 35, swirling flow channels 32, and branching flow channels 31 are all equal, ranging from 3 to 6, with the swirling flow channels 32 positioned directly opposite the branching flow channels 31. The widths of the swirling flow channels 32 and branching flow channels 31 are equal, being 0.5 to 0.9 times the inner wall radius of the swirling vane 3 mounted on the valve seat 2, and decreasing as the number of swirling flow channels 32 increases. This ensures more uniform flow among the multiple fluid streams passing through each swirling flow channel 32 and branching flow channel 31, resulting in a more uniform distribution of droplets in space during atomization. One end of the swirling vane 3, which has a manifold 34, abuts against an orifice plate 5. The orifice plate 5 is fixed to the outer casing 4 and has spray holes 51 connecting the manifold 34 to the outside. The fluid flows through the swirling channel 32, which is set at an angle to the downstream, and can simultaneously obtain axial velocity and circumferential tangential velocity. After converging in the confluence cavity 34, it is directly ejected from the orifice plate 5, forming a hollow swirling flow with tangential velocity and a large initial axial velocity.The hollow swirl forms a hollow conical liquid film outside the nozzle 51. After the liquid film breaks, a swirling spray with a fine and uniformly distributed droplet distribution can be obtained. Its overall flow channel is short, resulting in a stronger swirling effect and a smaller spray cone angle. With the same droplet distribution, a spray with a smaller cone angle is less likely to hit the walls, effectively inhibiting urea crystallization.

[0034] During nozzle installation, the locating pins are first inserted into the first locating pin hole 11 and the second locating pin hole 12, and then the ball valve 1 with the sealing ball 13 fixed inside the outer casing 4 is placed inside. The valve seat 2, the swirl vane 3, and the orifice plate 5 are then installed into the outer casing 4 in sequence, wherein the outer wall of the valve seat 2 and the inner wall of the outer casing 4 are sealed and fixed using an interference fit. Finally, the orifice plate 5 and the outer casing 4 are fixed together, such as by welding. The nozzle of this invention has a simple structure and is easy to install and operate.

[0035] When the nozzle of the present invention is not working, the sealing ball 13 at one end of the ball valve 1 abuts against the conical surface on the annular protrusion 21 to seal the through hole in the middle of the annular protrusion 21. During operation, the solenoid valve connected to the other end of ball valve 1 is activated, controlling ball valve 1 to rise, and the sealing ball 13 moves away from the annular protrusion 21. A 32.5% urea aqueous solution is pressurized by the urea pump and moves downstream along the annular gap formed between ball valve 1 and housing 4. The fluid flows through valve seat 2 and enters the diversion channel 31 of swirl vane 3 through the through hole in the middle of the annular protrusion 21. The fluid is evenly divided into multiple streams by multiple diversion channels 31. The diverted fluid is located around swirl vane 3 and moves downstream under pressure. It flows through the lateral channel 35 to the swirl channel 32. The fluid flows through the swirl channel 32, which is set obliquely downstream. When the fluid merges in the confluence cavity 34, it can simultaneously obtain axial velocity and circumferential tangential velocity. That is, the swirl channel 32 set obliquely downstream, together with the confluence cavity 34, causes the fluid to rotate. A low pressure appears on the central axis inside the nozzle. The pressure cloud diagram is as follows. Figure 8 As shown. Local low pressure causes a large amount of air to be drawn back from outside the nozzle into the interior of the swirl vanes, forming an air nucleus. The fluid is squeezed to the edge of nozzle 51, forming an annular liquid film, which, after being ejected, produces a hollow cone spray. Numerical calculations based on the Reynolds time-averaged method yield the following liquid phase volume fraction in the inner section of the double-layer swirl single-orifice urea nozzle: Figure 9 As shown in the figure, the spray cone angle is extracted and compared with a nozzle without a downward-sloping flow channel. The cone angle is reduced by approximately 5°, which is a 10% reduction.

[0036] The examples described are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the protection scope of the present invention.

Claims

1. A swirl-flow single-orifice urea nozzle, characterized in that: The system includes a ball valve (1), a valve seat (2), a swirl vane (3), a housing (4), and an orifice plate (5). The valve seat (2) is sealed and fixed to the inner wall of the housing (4). An annular protrusion (21) is provided inside the valve seat (2). A through hole is provided in the middle of the annular protrusion (21) to connect the two ends of the annular protrusion (21). A sealing ball (13) is provided at one end of the annular protrusion (21), and the sealing ball (13) is fixed to one end of the ball valve (1). The ball valve (1) is movably connected to the inner wall of the housing (4), and a gap for fluid flow is provided between the ball valve (1) and the housing (4). When the ball... When the valve (1) moves to the point where the sealing ball (13) abuts against one end of the annular protrusion (21), the sealing ball (13) seals the through hole in the middle of the annular protrusion (21); the other end of the annular protrusion (21) abuts against the swirl vane (3), and the swirl vane (3) is provided with multiple diversion channels (31) extending from the axis to the outer surface at one end near the annular protrusion (21), and the other end of the swirl vane (3) is provided with a confluence cavity (34) that does not completely penetrate the swirl vane (3), and the confluence cavity (34) is provided with multiple swirl channels (32) extending to the outer surface of the swirl vane (3) in the circumferential direction. The swirling channel (32) is eccentrically connected to the confluence cavity (34). The depth of the swirling channel (32) gradually decreases from the outer surface of the swirling vane (3) towards the confluence cavity (34). The outer surface of the swirling vane (3) is provided with multiple lateral channels (35) connecting the branch channel (31) and the swirling channel (32). The outer surface of the swirling vane (3) is provided with multiple axially penetrating notches to form lateral channels (35). One end of the confluence cavity (34) on the swirling vane (3) abuts against the orifice plate (5). The orifice plate (5) is provided with spray holes connecting the confluence cavity (34) and the outside. (51); the number of the lateral flow channels (35), swirling flow channels (32) and splitting flow channels (31) are equal, and the swirling flow channels (32) are set directly opposite the splitting flow channels (31); multiple swirling flow channels (32) and splitting flow channels (31) are evenly arranged on the swirling plate (3); the swirling plate (3) is provided with a guide cavity (33) connecting the splitting flow channels (31) and the middle through hole of the annular protrusion (21) at one end near the annular protrusion (21), and multiple splitting flow channels (31) converge in the guide cavity (33); the swirling flow channels (32) are tangent to the confluence cavity (34).

2. The swirl-flow single-orifice urea nozzle according to claim 1, characterized in that: The ball valve (1) is provided with a first positioning pin hole (11) and a second positioning pin hole (12), and the first positioning pin hole (11) and the second positioning pin hole (12) are perpendicular to each other in space. Positioning pins are pin-connected to both the first positioning pin hole (11) and the second positioning pin hole (12), and there is a gap between the positioning pin and the inner wall of the outer shell (4).

3. The swirl-flow single-orifice urea nozzle according to claim 1, characterized in that: The sealing ball (13) has multiple planes parallel to the axis in the circumferential direction.

4. The swirl-flow single-orifice urea nozzle according to claim 1, characterized in that: The annular protrusion (21) has a conical surface at one end near the sealing ball (13), and the larger end of the conical surface on the annular protrusion (21) is positioned directly opposite the sealing ball (13). When the sealing ball (13) abuts against the conical surface on the annular protrusion (21), it seals the through hole in the middle of the annular protrusion (21).

5. The swirl-flow single-orifice urea nozzle according to claim 1, characterized in that: The widths of the swirling channel (32) and the diversion channel (31) are equal, and are 0.5-0.9 times the inner wall radius of the valve seat (2) where the swirling vane (3) is installed.

6. The swirl-flow single-orifice urea nozzle according to claim 1, characterized in that: The total area of ​​the radial cross-section of the multiple lateral channels (35) on the swirl vane (3) is 10%-15% of the radial cross-section of the swirl vane (3).

7. The swirl-flow single-orifice urea nozzle according to claim 1, characterized in that: The number of lateral flow channels (35), swirling flow channels (32) and split flow channels (31) is set to 3-6.

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