Efficient anti-crystallization cyclone mixer for tail gas aftertreatment

Abstract

The efficient anti-crystallization rotational flow mixer comprises a left cylinder, a urea nozzle, a rotational flow pipe and a spiral pipe, the rotational flow pipe is conical, arranged in the left cylinder and communicated with the urea nozzle, and the spiral pipe is also conical, arranged in the left cylinder and communicated with the rotational flow pipe; two rows of blades which are uniformly distributed along the circumferential direction are arranged on the cyclone pipe; a spiral concave-convex structure is arranged on the inner wall of the spiral pipe; the problems that in traditional premixing, the flow speed is too high, the mixing time is insufficient, the pressure is unbalanced, and airflow exchange is blocked are solved through cooperation of the diffusion taper of the rotational flow pipe, double rows of reverse blades and an airflow exchange cavity of the left barrel, tail gas and urea are premixed more sufficiently, and no mixing blind area exists. The problems of adhesion and transportation of urea crystals are solved in a targeted mode through the contracted conical structure and the spiral concave-convex structure of the spiral pipe, and the crystallization risk under the low-temperature working condition is greatly reduced in combination with flow field adjustment of the left barrel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tail gas treatment systems, and particularly relates to a high-efficiency anti-crystallization cyclone mixer for tail gas aftertreatment. BACKGROUND

[0002] With the advancement of the national seventh emission standard of diesel engines, the requirement for the efficiency of urea selective catalytic reduction (urea-SCR) technology for tail gas aftertreatment is increasingly stringent, and the core lies in improving the mixing uniformity of urea and tail gas, inhibiting the deposition of urea crystallization, and simultaneously controlling the exhaust back pressure.

[0003] Current development of urea mixers mostly focuses on the breaking and decomposition of urea droplets, and generally adopts the design of layer-by-layer stacked porous pipes, which not only leads to complex structure and large assembly difficulty, but also significantly increases the exhaust back pressure and affects the power performance of the engine. In addition, the existing mixers have some obvious defects. First, the premixing effect is poor. The traditional cyclone structure is mostly single-row blade or equal-diameter design. Either the airflow cannot penetrate the top of the urea spray cone to form a mixing blind area, or the airflow excessively squeezes the spray to cause droplet agglomeration, making it difficult to achieve uniform premixing. Second, the anti-crystallization ability is insufficient. The broken urea droplets are easy to adhere to the pipe wall. The existing structure lacks active flushing and efficient transport design, and the heating area is limited. The problem of crystallization deposition is prominent under low-temperature working conditions, which easily blocks the channel and causes ammonia leakage. Third, the mixing space is compressed by the porous pipe structure, further limiting the full reaction of gas and liquid, and finally leading to the difficulty in improving the NO X conversion efficiency, which cannot meet the requirements of the national seventh emission standard. SUMMARY

[0004] The present application aims to overcome the deficiencies in the prior art and provide a high-efficiency anti-crystallization cyclone mixer for tail gas aftertreatment.

[0005] The application provides a high-efficiency anti-crystallization cyclone mixer for tail gas aftertreatment, comprising: a left cylinder communicating with a tail gas inlet pipeline; a urea nozzle arranged on one side of the left cylinder for spraying atomized urea; a cyclone pipe arranged in the left cylinder and communicating with the urea nozzle, the cyclone pipe being tapered, the pipe diameter of the cyclone pipe being larger farther away from the urea nozzle; a spiral pipe arranged in the left cylinder, communicating with the cyclone pipe and coaxially extending with the cyclone pipe, the spiral pipe also being tapered, the pipe diameter of the spiral pipe being smaller farther away from the cyclone pipe; two rows of circumferentially uniformly distributed blades are arranged on the pipe wall of the cyclone pipe along the axial direction of the cyclone pipe, the first row of blades close to the urea nozzle are arranged in an outward turning form, and the second row of blades close to the spiral pipe are arranged in an inward turning form; the tapered diffusion structure of the cyclone pipe and the two rows of reverse blades cooperate to not only increase the intake volume to adapt to the flow demand of the tail gas, but also guide the precise mixing of the tail gas and the urea to avoid the extrusion or mixing blind area of the spray form; the inner wall of the spiral pipe is provided with a spiral concave-convex structure, the spiral concave-convex structure comprises spiral ribs and spiral grooves protruding along the inner wall, the spiral ribs and the spiral grooves are alternately and continuously distributed to form a spiral channel with concave-convex interlaced, and the spiral grooves extend spirally along the flow direction of the gas; the tapered contraction structure of the spiral pipe and the spiral concave-convex structure cooperate to not only accelerate the airflow and enhance the transport capacity of the crystalline, but also increase the heating and sliding area by the tire vortex formed by the spiral grooves to reduce the adhesion of the crystalline; during the working process, the first row of blades can guide the tail gas to deeply contact the urea and expand the gas-liquid contact range, and the second row of blades can inhibit the excessive extrusion of the tail gas on the spray to avoid the droplet agglomeration, the two cooperate to make the tail gas and the atomized urea form uniform cyclone pre-mixing, then flow into the spiral pipe, and then realize the urea crushing and anti-crystallization through the tapered contraction acceleration and the spiral action.

[0006] Further, the outward turning angle α of the first row of blades is 25°-35°, the inward turning angle β of the second row of blades is 20°-30°, and α>β; and / or, the first row of blades and the second row of blades one-to-one correspond, the two blades corresponding to the conical generatrix are adjacent, and the openings formed by the two blades are connected to each other; and / or, the coverage rate of the first row of blades in the circumferential direction of the cyclone pipe is 40%-60%, and the coverage rate of the second row of blades in the circumferential direction of the cyclone pipe is 50%-70%; and / or, the axial chord length of the first row of blades and the second row of blades is 0.2-0.5 times the local diameter of the cyclone pipe; and / or, the axial length of the first row of blades and the second row of blades and the opening degree thereof in the circumferential direction are configured to enable the tail gas to form uniform cyclone pre-mixing in the cyclone pipe while maintaining the exhaust back pressure of the system within a predetermined range; and / or, the inlet and outlet diameter ratio of the cyclone pipe is 1.2-1.8, which is helpful for reducing the speed and pressure of the incoming flow to create stable flow field conditions for the subsequent fine gas-liquid pre-mixing realized by the two rows of reverse blades.

[0007] Further, the helical pitch L of the helical concave-convex structure is 15-25 mm, so as to ensure that the tire vortex is formed in the helical groove; and / or, the groove depth of the helical concave-convex structure is 0.2-0.4 times of the helical pitch L; and / or, the ratio of the inlet diameter to the outlet diameter of the helical pipe is 1.5-2.

[0008] Further, the high-efficiency anti-crystallization cyclone mixer for tail gas aftertreatment provided by the application further comprises a spin-mixing pipe, the spin-mixing pipe is arranged in the left cylinder and communicates with the cyclone pipe, and the helical pipe is arranged in the spin-mixing pipe; at least one row of windows is arranged on the pipe wall of the spin-mixing pipe and is uniformly distributed in the circumferential direction, and the windows are located downstream of the helical pipe; the windows have a configuration of outward protrusion and one-side opening; the windows are used for wedging the tail gas inward, which can not only supplement heat to reduce the crystalline deposits on the inner wall of the helical pipe, but also guide the tail gas and the gas-liquid mixture flowing out of the helical pipe to uniformly converge in the circumferential direction, so as to enhance the cyclone effect of the gas flow and promote the decomposition of urea and the uniform mixing of gas and liquid.

[0009] Further, the opening height of the window is 10-15 mm; and / or, the opening direction of the window is arranged at an angle with the axial direction of the spin-mixing pipe, and the angle between the two is 30-45°.

[0010] Further, the high-efficiency anti-crystallization cyclone mixer for tail gas aftertreatment provided by the application further comprises a right cylinder, the right cylinder is arranged downstream of the left cylinder and is arranged in a separated mode with the left cylinder, and the right cylinder communicates with the tail gas outlet pipeline; a first mounting hole is arranged on the right side wall of the left cylinder facing the right cylinder, a second mounting hole opposite to the first mounting hole is arranged on the left side wall of the right cylinder facing the left cylinder, and the left cylinder and the right cylinder are sealingly connected through the communication pipeline penetrating the first mounting hole and the second mounting hole; the right cylinder is used for receiving the gas-liquid mixture after the gas-liquid mixture converges through the spin-mixing pipe and the communication pipeline, and providing a mixing buffer space for the gas-liquid mixture.

[0011] Further, the communication pipeline comprises a sleeve, a gasket and a bushing connected in sequence, the gasket is pressed between the sleeve and the bushing, and the three are fastened through a clamp; the sleeve communicates with the spin-mixing pipe; the bushing communicates with the right cylinder; the communication pipeline is used for rectifying and damping the gas flow from the left cylinder and providing thermal expansion compensation between the left cylinder and the right cylinder.

[0012] Further, the volume of the right cylinder is greater than that of the left cylinder; the volume of the right cylinder is 1.5-3 times of the volume of the left cylinder, which is used for providing sufficient gas flow development space and ensuring sufficient mixing residence time, so as to ensure that the ammonia gas and the tail gas are uniformly mixed.

[0013] Further, the high-efficiency anti-crystallization cyclone mixer for tail gas aftertreatment provided by the application further comprises: a transition pipe, one end of which is connected with the communication pipe and the other end of which penetrates into the right cylinder through the second mounting hole; and a flow guide hole plate, which is arranged at the gas outlet end of the transition pipe in the right cylinder; wherein the cyclone pipe, the spiral pipe, the rotation-increasing mixing pipe, the communication pipe and the transition pipe constitute a mixed gas conveying pipe, which is used to promote the mixing of the tail gas and the urea entering the left cylinder and to guide the gas-liquid mixture into the right cylinder; the flow guide hole plate serves as an output window of the mixed gas conveying pipe; a plurality of flow guide vanes are arranged on the flow guide hole plate in a linear direction, the linear direction being perpendicular to the axial direction of the mixed gas conveying pipe, the flow guide vanes being arranged in an everted form and used to guide the gas-liquid mixture flowing out of the mixed gas conveying pipe to form a radial cyclone flow, which further cooperates with the wide space of the right cylinder to form a buffer, so as to prolong the residence time of the gas-liquid mixture, improve the mixing uniformity of the ammonia gas and the tail gas, and reduce the risk of excessively high local ammonia concentration.

[0014] Further, the upper part of the flow guide hole plate is provided with four involute flow guide vanes, the eversion angles of the four flow guide vanes monotonously changing along the arrangement direction thereof, which are used to compensate for the non-uniformity of the circumferential airflow generated by the spiral pipe and the rotation-increasing mixing pipe; and / or, the eversion angle δ of the flow guide vanes is 50°-90°; and / or, the upper side of the transition pipe is provided with a notch, the axial length of the notch accounting for 1 / 2 of the transition pipe, the top of the flow guide hole plate is provided with an axial flow guide piece, the axial flow guide piece being folded towards the transition pipe so that the axial flow guide piece faces the notch, and the included angle ε between the axial flow guide piece and the flow guide hole plate is 30°-60°; and / or, the upper part of the flow guide hole plate is provided with four flow guide vanes, the widths of the four flow guide vanes being consistent, the heights of the two flow guide vanes arranged in the middle being consistent and higher than those of the other two flow guide vanes arranged on the two sides, the heights of the other two flow guide vanes arranged on the two sides being consistent, a pressure relief through hole being arranged in the height difference area between the two flow guide vanes with different heights, and the pressure relief through hole being used to balance the pressure before and after the flow guide hole plate; and / or, at least one row of small holes is arranged below the flow guide vanes on the flow guide hole plate, the diameters of the small holes being 2mm-10mm, and the total opening area of the small holes accounting for 10%-25% of the area of the flow guide hole plate.

[0015] This application provides a high-efficiency anti-crystallization swirling mixer for exhaust gas aftertreatment, including a left cylinder, a urea nozzle, a swirling tube, and a spiral tube. The swirling tube is conical, located inside the left cylinder, and connected to the urea nozzle. The spiral tube is also conical, located inside the left cylinder, and connected to the swirling tube. The swirling tube has two rows of blades evenly distributed circumferentially. The inner wall of the spiral tube has a spiral concave-convex structure. Through the diffusion cone of the swirling tube and the double rows of counter-rotating blades, in conjunction with the airflow exchange chamber of the left cylinder, the problems of insufficient mixing time due to excessive flow velocity and obstructed airflow exchange due to pressure imbalance in traditional premixing are solved, allowing exhaust gas and urea to be premixed more fully and without mixing blind spots. Through the contraction cone and spiral concave-convex structure of the spiral tube, the problems of urea crystal adhesion and transport are specifically solved. Combined with the flow field adjustment of the left cylinder, the risk of crystallization under low temperature conditions is significantly reduced. The swirling tube and the spiral tube are coaxially integrated inside the left cylinder, which ensures mixing efficiency while avoiding the problem of increased flow resistance caused by complex structures, and balances premixing uniformity, anti-crystallization ability, and flow field stability. Attached Figure Description

[0016] Figure 1 A schematic diagram of a high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment provided in this application; Figure 2 for Figure 1 The exploded view of the structure of a high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment is shown below. Figure 3 for Figure 1 The diagram shows a cross-sectional view of a high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment. Figure 4 for Figure 1 The exploded view of the high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment shown is omitted, with the left cylinder, right cylinder and connecting pipes removed. Figure 5 for Figure 1 The diagram shows the structure of the cyclone tube in the high-efficiency anti-crystallization cyclone mixer used for exhaust gas aftertreatment; Figure 6 for Figure 1 The diagram shows the structure of the spiral tube in a high-efficiency anti-crystallization cyclone mixer used for exhaust gas aftertreatment. Figure 7 for Figure 1 The diagram shown is a schematic of the structure of the swirling mixing tube in the high-efficiency anti-crystallization swirling mixer used for exhaust gas aftertreatment. Figure 8 for Figure 1 The diagram shows the structure of the orifice plate in the high-efficiency anti-crystallization cyclone mixer used for exhaust gas aftertreatment. Detailed Implementation

[0017] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0018] This application provides a high-efficiency anti-crystallization swirling mixer for exhaust gas aftertreatment, comprising: a left cylinder 1, connected to the exhaust gas inlet pipe; a urea nozzle 3, disposed on one side of the left cylinder 1, for spraying atomized urea; a swirling tube 10, disposed inside the left cylinder 1 and connected to the urea nozzle 3, the swirling tube 10 being conical, with its diameter increasing the further away from the urea nozzle 3; and a spiral tube 20, disposed inside the left cylinder 1, connected to the swirling tube 10, and extending coaxially with the swirling tube 10. The swirl tube 10 is also cone-shaped, with its diameter decreasing as it moves further away from the swirl tube 10 and spiral tube 20. Along the axial direction of the swirl tube 10, two rows of blades are evenly distributed circumferentially on its wall. The first row of blades 11, closer to the urea nozzle 3, is arranged in an outward-facing configuration, while the second row of blades 12, closer to the spiral tube 20, is arranged in an inward-facing configuration. The cone-shaped diffuser structure of the swirl tube 10, combined with the double-row counter-rotating blades, can both increase the intake volume to meet the exhaust gas flow requirements and guide the exhaust gas flow. The gas and urea are precisely mixed to avoid squeezing or mixing blind spots in the spray pattern. The inner wall of the spiral tube 20 is provided with a spiral concave-convex structure, which includes spiral ridges raised along the inner wall and spiral grooves 21 recessed. The spiral ridges and spiral grooves 21 are distributed alternately and continuously to form a spiral channel with alternating concave and convex shapes. The spiral grooves 21 extend spirally along the gas flow direction. The conical contraction structure and the spiral concave-convex structure of the spiral tube 20 work together to accelerate the airflow and enhance the transport capacity of crystals. They can also scour the tube wall through the tire vortex formed by the spiral grooves 21, increase the heating and sliding area, and thus reduce the adhesion of crystals. During operation, the first row of blades 11 can guide the exhaust gas to deeply contact the urea and expand the gas-liquid contact range. The second row of blades 12 can inhibit the excessive squeezing of the exhaust gas and prevent droplet agglomeration. The two work together to make the exhaust gas and atomized urea form a uniform swirling premix before flowing into the spiral tube 20. Through the conical contraction acceleration and spiral action, the urea is broken up and anti-crystallization is achieved.

[0019] For details, please refer to Figure 1 In the illustrated embodiment, the left cylinder 1 is a cylindrical structure with an open top (for connecting to the exhaust gas intake pipe) and a closed bottom, used to provide the chamber required for airflow exchange in the swirl tube 10. The left cylinder 1 acts as a "pressure accumulator" and "recirculation buffer" in the process of mixing exhaust gas and urea, and can dynamically adjust the airflow state inside and outside the swirl tube 10, creating a stable flow field environment for subsequent premixing and crushing mixing.

[0020] Combined with reference Figure 3 A urea nozzle 3 is provided on the left side of the left cylinder 1, and a swirl tube 10 is located inside the left cylinder 1. The injection direction of the urea nozzle 3 is collinear with the axial direction of the swirl tube 10. The swirl tube 10 is generally in the shape of a diffused cone. The diameter of the swirl tube 10 increases as it moves away from the urea nozzle 3. The small end of the swirl tube 10 is connected to the injection end of the urea nozzle 3.

[0021] Combined with reference Figure 4 and Figure 5 Along the axial direction of the cyclone tube 10, two rows of blades are arranged on its tube wall in sequence. The first row of blades 11 near the urea nozzle 3 is outward-facing, and the second row of blades 12 is inward-facing.

[0022] The first row of blades 11 is located at the small end of the swirl tube 10, close to the spray outlet of the urea nozzle 1. After the spray cone is ejected from the nozzle, the cone tip is the core area close to the nozzle, which is also the area where the spray droplets are most concentrated and the particle size is relatively small. The installation position of the first row of blades 11 can directly act on the airflow that has just come into contact with the spray. Due to the narrow pipe cross section at this position, the airflow velocity is relatively high when it flows through (30%-50% higher than the large end). The outward-opening shape of the first row of blades 11 can guide the airflow to make a compound spiral motion of circumferential rotation and axial forward (away from the nozzle) along the blade tilt direction. This outward-opening guiding method can maximize the swirling intensity of the airflow and make the airflow form a strong spiral propulsion force.

[0023] Specifically, the spray cone emitted by the urea nozzle 1 is conical, with the apex being the core area closest to the nozzle where the droplets are most concentrated. The strong swirling flow guided by the first row of blades 11 does not directly impact the center of the spray cone, but instead spirals along the outer contour of the spray cone. The negative pressure generated by the swirling flow envelops the spray cone, and the spiraling airflow can penetrate the airflow resistance on the outer side of the spray cone, penetrating deep into the apex area along the cone surface. This avoids the problem of the airflow merely circling around the outside of the spray cone and failing to contact the core droplets.

[0024] More specifically, when the spray is first ejected from the nozzle, the cone angle is small and the droplets are concentrated. The swirling flow guided by the first row of blades 11 that opens outward from the tube can precisely fit the initial contour of the spray cone. Through helical shear force, the airflow can fully contact the fine droplets at the top of the spray cone, laying the foundation for subsequent gas-liquid mixing.

[0025] The second row of blades 12 is located at the larger end of the swirl tube 10. The pipe cross-section at this location is wide, resulting in a relatively low airflow velocity, thus forming a "flow field buffer section." At this point, the airflow has already formed a swirl by the first row of blades 11 and contacted the top of the spray cone, requiring no further penetration. The inward-curving shape of the second row of blades 12, converging towards the central axis, is opposite to the outward-opening guiding direction of the first row of blades 11. This forces the airflow to undergo a combined motion of circular rotation and axial inward (near the inner wall of the pipe). This motion counteracts some of the spiral kinetic energy propelling the airflow forward, preventing it from continuing to penetrate deeper into the spray cone.

[0026] It's easy to understand that if the strong swirling flow continues to penetrate deeply, it will exert radial pressure on the spray cone, causing the cone angle to decrease and droplets to agglomerate (large droplets are difficult to break up). The second row of inward-turning blades guides the airflow towards the inner side of the pipe wall, creating a "protective swirling flow" on the outside of the spray cone. This prevents the airflow from directly compressing the spray cone and also envelops and blends the spray from the outside, maintaining the integrity of the spray cone's cone angle and the uniformity of droplet distribution.

[0027] During operation, the exhaust gas enters the swirl tube 10 from the left cylinder 1. Since the swirl tube 10 has a gradually expanding conical structure, the exhaust gas flows inside and gradually slows down as the cone diffuses. This not only prolongs the effective contact and mixing time between the urea droplets and the airflow, but also allows the pressure distribution inside the tube to better match the airflow movement as the static pressure recovers. At the same time, the first row of outward-curving blades at the small end guides the airflow to form a strong swirling flow, penetrating deep into the core droplet at the cone apex along the outer contour of the spray cone. Meanwhile, the second row of inward-curving blades at the large end guides the airflow in the opposite direction to flow towards the inner side of the tube wall, inhibiting the airflow from penetrating too deeply to avoid squeezing and damaging the spray shape. Finally, through the all-round contact of "cone apex penetration" and "outer wrapping", the exhaust gas and urea spray are gently blended and uniformly premixed, laying the foundation for the secondary crushing of the spiral tube 20 and the heat replenishment and confluence of the swirling mixing tube 30.

[0028] Continue to refer to Figures 1 to 3 The spiral tube 20 is located inside the left cylinder 1 and is coaxially positioned downstream of the vortex tube 10. The spiral tube 20 has a tapered structure, and its diameter decreases as it moves further away from the vortex tube 10. The large end of the spiral tube 20 is sealed to the large end of the vortex tube 10.

[0029] Combined with reference Figure 6 The inner wall of the spiral tube 20 is provided with a spiral groove 21 that extends continuously along its axial direction. The spiral groove 21 is the outward concave part of the inner wall of the spiral tube 20. A relatively convex spiral ridge is formed between two adjacent spiral grooves 21. The alternating and continuous spiral ridges and spiral grooves 21 constitute a spiral concave-convex structure.

[0030] The conical contraction structure of the spiral tube 20 can increase the airflow speed, thereby enhancing the internal airflow's ability to transport crystals. The spiral concave-convex structure can both form a tire vortex through the spiral groove 21 to scour the tube wall and increase the heating and sliding area, thereby reducing the adhesion of urea crystals on the tube wall.

[0031] In one embodiment, after the exhaust gas enters the left cylinder 1 through the intake pipe, it flows into the gradually expanding cone-shaped swirl tube 10 through the opening formed by the folding blades. The urea nozzle 3 simultaneously sprays atomized urea into the swirl tube 10. The exhaust gas and atomized urea initially meet in the tube. The diffusion cone of the swirl tube 10 causes the airflow velocity to gradually decrease and the static pressure to recover. The first row of outward-folding blades 11 guides part of the airflow to spiral deep along the outside of the spray cone and accurately contact the core droplet at the top of the cone. The second row of inward-folding blades 12 guides the airflow in the opposite direction to flow towards the inside of the tube wall and inhibits the airflow from going too deep. This forms a dynamic airflow exchange of outward penetration and inward return flow. While avoiding excessive compression and deformation of the spray shape, it completely eliminates the mixing blind zone and achieves full premixing of gas and liquid.

[0032] The premixed gas-liquid mixture then enters the coaxially connected spiral tube 20. Its contraction structure can gradually increase the airflow speed and enhance its transport capacity for crystals. The spiral concave-convex structure can also generate stable tire vortices through the spiral groove 21, continuously scouring the tube wall to reduce the adhesion of crystals. At the same time, it increases the heating and sliding area between the airflow and the tube wall, further breaking down the incompletely refined urea particles.

[0033] The high-efficiency anti-crystallization swirling mixer for exhaust gas aftertreatment provided in this application solves the problems of insufficient mixing time and pressure imbalance in traditional premixing by using the diffusion cone and double-row counter-rotating blades of the swirling tube 10 in conjunction with the airflow exchange chamber of the left cylinder 1. This allows for more thorough premixing of exhaust gas and urea without any mixing blind spots. The constricting cone and spiral concave-convex structure of the spiral tube 20 specifically solves the problems of urea crystal adhesion and transport. Combined with the flow field adjustment of the left cylinder 1, it significantly reduces the risk of crystallization under low-temperature conditions. The swirling tube 10 and the spiral tube 20 are coaxially integrated in the left cylinder 1, which ensures mixing efficiency while avoiding the problem of increased flow resistance caused by complex structures, and balances premixing uniformity, anti-crystallization ability and flow field stability.

[0034] Optionally, the outward turning angle α of the first row of blades 11 is 25°~35°, and the inward turning angle β of the second row of blades 12 is 20°~30°, and α>β.

[0035] For the first row of blades 11, the lower limit of 25° can provide sufficient tangential thrust, allowing the airflow to obtain sufficient spiral kinetic energy and penetrate deep into the core droplet at the top of the cone along the outer contour of the spray cone, avoiding insufficient swirling intensity due to the angle being too small, which would prevent it from being unable to overcome the resistance on the outer side of the spray cone; the upper limit of 35° can prevent the swirling from being too violent, preventing excessive impact on the spray cone that has just been sprayed, while controlling the airflow resistance and preventing the initiation of local eddies.

[0036] For the second row of blades 12, the lower limit of 20° can provide sufficient reverse guiding force to entrain the airflow in the left cylinder 1 cavity into the swirl tube 10, counteracting the swirl propulsion kinetic energy guided by the first row of blades 11, and preventing the airflow from continuing to penetrate deep and compress the spray pattern; the upper limit of 30° can prevent the reverse guiding force from being too strong, avoiding obstructing the smooth flow of air in the tube or causing the back pressure to rise, while ensuring that the entrained airflow can form a stable dynamic exchange with the mainstream in the tube.

[0037] The reason for designing α > β is that the first row of blades 11 requires a stronger swirling guiding force to achieve penetration contact, while the second row of blades 12 only needs a moderate reverse force to achieve suppression and buffering. The angle difference between the two can form a balanced airflow field of "outward penetration" and "inward return flow", which not only ensures full contact between the exhaust gas and urea spray in all directions, but also protects the integrity of the spray shape and avoids mixing blind zones, while maintaining the stability of the flow field inside the pipe, making the conversion of dynamic pressure to static pressure smoother.

[0038] Optionally, the first row of blades 11 and the second row of blades 12 correspond one-to-one, with two blades along the generatrix of the cone being adjacent to each other, and the openings formed by the two are interconnected.

[0039] For details, please refer to Figure 5 In the illustrated embodiment, the cyclone tube 10 is generally conical, and its cone generatrix is ​​the inclined contour line of the cone surface connecting the edge of the cone apex and the edge of the cone bottom. The number of blades in the first row of blades 11 and the second row of blades 12 is the same, and the two rows of blades are arranged in a one-to-one correspondence; along each cone generatrix direction of the cyclone tube 10, a corresponding first row of blades 11 and a corresponding second row of blades 12 are arranged adjacent to each other, the openings formed by the two are interconnected, and the folding directions of the blades are opposite.

[0040] The adjacent arrangement along the cone generatrix allows the airflow guided by the first row of blades 11 to directly enter the effective range of the corresponding second row of blades 12 as soon as it completes the "outward penetration" action of the spray cone. It is then promptly "drawn in" and recirculated, forming a continuous and uninterrupted dynamic airflow exchange. This avoids the formation of stagnant zones in the gaps between the blades (reducing the risk of urea droplet accumulation or crystallization). The interconnected openings of the two blades allow the airflow in the left cylinder 1 to smoothly enter the connecting area of ​​the two rows of blades along the direction of the cone generatrix, ensuring the continuity of airflow circulation. It also eliminates airflow obstruction between the blades, allowing the exhaust gas and atomized urea to simultaneously receive the guiding force of the two rows of blades within the same cone surface area. This avoids excessive compression and deformation of the spray pattern and completely eliminates the mixing blind zone, improving premixing uniformity. At the same time, this arrangement adapted to the cone generatrix also allows the airflow to form a spiral mixing motion along the cone surface, enhancing the gas-liquid contact effect.

[0041] Optionally, the first row of blades 11 has a coverage rate of 40% to 60% around the 10th circumference of the cyclone tube, and the second row of blades 12 has a coverage rate of 50% to 70% around the 10th circumference of the cyclone tube.

[0042] It should be explained that the circumferential direction of the cyclone tube 10 refers to the direction in which it circles around the conical axis of the cyclone tube 10, that is, the direction in which it is distributed circumferentially along the tube wall of the cyclone tube 10.

[0043] It should also be explained that the coverage of the swirling tube 10 in the circumferential direction refers to the proportion of the projected arc length of the blade on the circumference of the corresponding position of the swirling tube 10 to the total circumference length of the swirling tube at that position. It is inversely related to the degree of openness (degree of openness = 1 - coverage), and directly affects the degree of obstruction of the airflow channel, the swirling intensity and the exhaust back pressure.

[0044] The reason for setting the circumferential coverage of the first row of blades 11 to 40%~60% is that the degree of openness corresponding to this range can ensure sufficient airflow channel space to reduce flow resistance and avoid excessive obstruction leading to increased exhaust back pressure. It can also effectively guide the axial airflow to "throw" it toward the center of the swirl tube and force it into the urea spray cone to achieve initial gas-liquid mixing.

[0045] If the coverage is less than 40% (too high an opening), the blades will not have enough guiding force, making it difficult for the airflow to penetrate deep into the spray; if it is more than 60% (too low an opening), it will result in excessive resistance and easily create turbulent flow.

[0046] The reason for setting the circumferential coverage of the second row of blades 12 to 50%~70% is that the opening degree corresponding to this range is relatively low. The lower opening degree can enhance the guiding and inhibiting effect of the blades on the airflow. On the one hand, it can axially constrain the high-speed airflow from the first row of blades 11 to prevent excessive squeezing of the spray and droplet aggregation. On the other hand, it can enhance the effect of the high-temperature airflow drawn in from the left cylinder 1 in order to supplement heat and assist urea decomposition.

[0047] If the coverage is less than 50% (too high an opening), the airflow guiding and entrainment capabilities are weak; if it is higher than 70% (too low an opening), it will easily obstruct airflow and increase back pressure.

[0048] Optionally, the axial chord length of the first row of blades 11 and the second row of blades 12 is 0.2 to 0.5 times the local diameter of the cyclone tube 10.

[0049] It should be explained that the axial chord length of the blade refers to the projected length of the blade along the axis of the swirl tube 10. It is a key dimension for measuring the range of action of the blade in the airflow path and directly affects the duration of the blade's guidance or control of the airflow.

[0050] It should also be explained that the local diameter of the cyclone tube 10, since the cyclone tube 10 has a conical structure, refers to the diameter of the cyclone tube at the actual installation position of the blades. That is, the first row of blades 11 is installed at the small end of the cyclone tube, and its "local diameter" is the diameter of the small end. The second row of blades 12 is installed at the large end, and its "local diameter" is the diameter of the large end.

[0051] The reason for setting the axial chord length of the first row of blades 11 and the second row of blades 12 to 0.2 to 0.5 times the local diameter of the cyclone tube 10 is that this range can balance the blade function and airflow resistance. Specifically, a chord length of more than 0.2 times ensures that the blades have sufficient axial working length, so that the first row of blades 11 can fully guide the airflow to cut into the urea spray to achieve mixing, and the second row of blades 12 can effectively suppress the airflow from excessively compressing the spray; a chord length of less than 0.5 times can prevent the blades from excessively blocking the airflow channel, avoiding the increase in exhaust back pressure due to narrow channel, and at the same time avoiding the airflow staying in the blade area for too long, causing energy loss.

[0052] Optionally, the axial length of the first row of blades 11 and the second row of blades 12, and their circumferential opening, are configured to maintain the exhaust back pressure of the system within a predetermined range while forming a uniform swirling premix in the swirling tube 10.

[0053] It should be explained that the exhaust back pressure of the system refers to the reverse pressure generated by the exhaust gas when it flows through the exhaust aftertreatment system (including the mixer provided in this application) due to pipeline resistance, component obstruction, etc. This pressure directly affects the engine exhaust efficiency. If it is too high, it will lead to a decrease in engine power and an increase in fuel consumption. Its predetermined range is mainly determined by the engine rated power (the higher the power, the lower the back pressure needs to be to match the exhaust flow), the China VII emission standard for diesel engines (it needs to meet the back pressure limit under a specific exhaust flow), the overall pipeline layout of the aftertreatment system (pipeline diameter, number of bends) and the design of the upstream exhaust manifold. Usually, the exhaust back pressure of the aftertreatment system matched with the China VII diesel engine needs to be controlled within 15 kPa.

[0054] The axial length and circumferential openness of the first row of blades 11 and the second row of blades 12 are in a synergistic balance with uniform swirling premixing and exhaust back pressure.

[0055] Specifically, in terms of axial length, the first row of blades 11 needs to be long enough to cover the cone angle of the urea spray, ensuring that the guiding airflow fully intervenes in the spray core and achieves premixing. If it is too short, it will result in a large premixing blind zone; if it is too long, it will extend into the center of the flow channel, increase resistance, and cause the back pressure to rise. The second row of blades 12 needs to act on the periphery of the flow channel to regulate the airflow on the pipe wall. If it is too long, it will interfere with the core airflow that has been initially mixed, destroy the premixing uniformity, and increase the resistance.

[0056] In terms of circumferential openness, although a low degree of openness (high coverage) can enhance the guiding capacity and form a stronger ordered vortex to improve the premixing uniformity, it will reduce the airflow channel and increase resistance, resulting in excessive back pressure. Although a high degree of openness (low coverage) can reduce back pressure, it will weaken the vortex intensity due to insufficient guiding capacity, and will not be able to achieve uniform premixing.

[0057] Taking the embodiment adapted to a 12L National VII diesel engine as an example, the local diameter of the small end (at the first row of blades 11) of the swirl tube 10 is 40mm, and the local diameter of the large end (at the second row of blades 12) is 70mm. The axial length of the first row of blades 11 is 16mm (0.4 times the local diameter) and the circumferential coverage is 50% (50% openness). The axial length of the second row of blades 12 is 21mm (0.3 times the local diameter) and the circumferential coverage is 60% (40% openness). In this configuration, the first row of blades 11 can fully guide the airflow to cut into the 40mm spray cone to achieve vigorous gas-liquid mixing. The second row of blades 12 can gently entrain the airflow in the left cylinder 1 and suppress the excessive compression of the spray by the airflow. Finally, the uniformity of the exhaust gas and urea mixing reaches 92%, with no mixing blind zone. The measured exhaust back pressure of the system is 12kPa, which is within the predetermined range. This satisfies the premixing requirements and avoids the back pressure affecting the engine performance.

[0058] Optionally, the inlet and outlet diameter ratio of the swirl tube 10 is 1.2 to 1.8, which helps to slow down and reduce the pressure of the incoming flow, creating stable flow field conditions for subsequent fine gas-liquid premixing achieved by double-row counter-rotating blades.

[0059] The inlet and outlet diameter ratio of the cyclone tube 10 refers to the ratio of the diameter of its inlet end (the small end near the urea nozzle 3) to the diameter of its outlet end (the large end near the spiral tube 20).

[0060] If the ratio is less than 1.2, the diffusion degree is close to that of a straight pipe. The reduction in airflow velocity is limited and the static pressure recovery is insufficient. This will not only shorten the contact time between the exhaust gas and urea, but also hinder the deep guidance of the exhaust gas by the first row of blades 11 and the suppression of the exhaust gas by the second row of blades 12 due to the excessive pressure inside the pipe, resulting in uneven premixing.

[0061] If the ratio is greater than 1.8, the flow channel expands too quickly, and the airflow is prone to break away from the pipe wall to form a vortex dead zone. The stagnation of airflow in the dead zone will cause energy loss, and may also cause urea droplets to accumulate in the dead zone to form local agglomeration, which will disrupt the stability of the premixed flow field.

[0062] A ratio range of 1.2 to 1.8 can both reduce airflow and restore static pressure through appropriate diffusion, providing sufficient time and a stable pressure environment for the blades to guide gas-liquid mixing, and avoid airflow separation problems caused by excessive expansion of the flow channel.

[0063] Optionally, the pitch L of the spiral groove 21 is 15mm to 25mm to ensure that a tire vortex is formed within the spiral groove 21.

[0064] It should be explained that a tire vortex refers to an independent rotating flow structure, resembling a miniature donut, formed by airflow constrained by the spiral concave-convex structure of the inner wall of the helical tube 10, with a closed-loop rotation axis. For details, please refer to... Figure 6 Multiple tire vortices are arranged continuously along the extension direction of the spiral groove 21 and can move forward synchronously with the main airflow. Each tire vortex exists stably in the local space of a single spiral groove 21, rather than being distributed continuously across grooves.

[0065] The tire vortex enhances the anti-crystallization ability and urea breakup effect of the spiral tube 20. On the one hand, the tire vortex rotates at high speed in the spiral groove 21, which can continuously flush away the incompletely decomposed urea droplets or tiny crystals attached to the bottom and walls of the groove, preventing crystals from accumulating and blocking the channel in the groove. On the other hand, the rotating tire vortex will form a shearing effect with the main airflow, further breaking up the larger urea droplets remaining after premixing, while expanding the gas-liquid contact area and assisting the decomposition of urea into NH3 and HNCO.

[0066] It should also be explained that the pitch L refers to the distance between two adjacent spiral edges (or two adjacent spiral grooves 21) along the axis of the spiral tube 20 in the spiral concave-convex structure. It determines the existence stability, rotation intensity and overall scouring effect of the tire vortex.

[0067] As is easily understood, the spiral groove 21 is the carrier of the tire vortex, and the size of the pitch L directly corresponds to the axial length of a single spiral groove 21. Generally speaking, the larger the pitch L, the more spacious the axial space of a single spiral groove 21; the smaller the pitch L, the narrower the axial space of a single spiral groove 21. Since the tire vortex needs sufficient axial space to form a stable rotation, it cannot develop and take shape if the space is insufficient.

[0068] Because the spiral tube 20 is a constricting cone, the exhaust gas is in an accelerated flow state inside the spiral tube 20. If the pitch L is too small, the axial space of the spiral groove 21 is narrow, and the high-speed main airflow is prone to generate strong shear force on the small vortices initially formed in the groove, directly dispersing them, resulting in the tire vortex not being able to exist stably. If the pitch L is too large, the main airflow is prone to cross the spiral groove 21 and flow directly along the surface of the spiral edge, making it difficult to form a low-pressure backflow zone (the driving force for the formation of tire vortex) in the groove, and thus it is also impossible to generate an effective tire vortex.

[0069] In addition, the pitch L also determines the number of spiral grooves 21 (i.e., the number of tire vortices) within a unit length of spiral tube 20. Generally speaking, the smaller the pitch L, the more tire vortices there are per unit length, but stability needs to be balanced; the larger the pitch L, the fewer tire vortices there are per unit length, and the overall scouring coverage area will be reduced.

[0070] Tests revealed that when the pitch L ≥ 15 mm, the axial space of the spiral groove 21 is sufficient to accommodate the development of tire vortices. Under the exhaust gas velocity, a low-pressure recirculation zone can be formed in the groove, driving the airflow to rotate and form a tire vortex of suitable size. Moreover, this space can resist the shear force of the main airflow, preventing the vortex from being dispersed. If L < 15 mm, the space in the groove is narrow, the low-pressure recirculation zone cannot be formed stably, and the initially generated tiny vortices will be directly destroyed by the high-speed mainstream, losing their scouring and breaking effects.

[0071] When the pitch L≤25mm, a sufficient number of spiral grooves 21 can be retained within the unit length of the spiral tube 20. For example, 4 to 6 tire vortices can be formed in a 100mm long spiral tube, which can achieve continuous and dense flushing of the tube wall and avoid local groove sections without flushing and crystal accumulation due to insufficient number of vortices. If L>25mm, the number of tire vortices within the unit length is insufficient, there are gaps in the flushing coverage, and the main airflow is easy to cross the grooves, making it difficult to form effective rotation within the grooves, and the flushing effect is greatly weakened.

[0072] Optionally, the groove depth of the helical concave-convex structure is 0.2 to 0.4 times the pitch L.

[0073] If the groove depth is less than 0.2 times the pitch L, the longitudinal space inside the groove is too shallow and cannot provide the space required for the complete annular rotation of the tire vortex. The airflow is difficult to form a sufficiently strong backflow vortex inside the groove, and the generated tire vortex will be easily dispersed by the mainstream airflow due to its incomplete structure. It not only loses the ability to effectively scour the groove wall, but also cannot help break up urea droplets, resulting in weak anti-crystallization and mixing effects.

[0074] If the groove depth is greater than 0.4 times the pitch L, the excessive depth of the groove will lead to excessive vortex development. On the one hand, the loose vortex structure will disperse the rotational energy, making it difficult for the scouring force to concentrate on the groove wall, thus reducing its anti-crystallization efficiency. On the other hand, an excessively deep groove will increase the distance between the vortex inside the groove and the mainstream airflow, making it difficult for the mainstream to drive the vortex to move synchronously. This can easily create a dead zone at the bottom of the groove, where undecomposed urea droplets may accumulate and crystallize, violating the original intention of the anti-crystallization design.

[0075] The ratio range of 0.2 to 0.4 times provides the longitudinal space that perfectly matches the annular structure of the tire vortex, ensuring the integrity of the vortex and the appropriate rotation intensity. It also allows the vortex to maintain close interaction with the mainstream airflow flowing along the spiral groove, enabling the vortex to obtain continuous rotational power from the mainstream and to efficiently scour the groove wall and shear urea droplets through its own rotation.

[0076] Optionally, the ratio of the inlet and outlet diameters of the spiral tube 20 is 1.5 to 2.

[0077] If the ratio is less than 1.5, the degree of contraction is insufficient and the airflow acceleration is not obvious. It cannot provide enough kinetic energy to transport crystals, nor can it form an effective low-pressure zone to drive the tire vortex.

[0078] If the ratio is greater than 2, excessive contraction will cause the airflow speed to increase sharply, which can easily cause the airflow to separate from the pipe wall and form a vortex dead zone. This will cause crystals to accumulate in the dead zone and may also disrupt the stable rotation of the tire vortex. At the same time, excessive contraction will increase airflow resistance and lead to an increase in exhaust back pressure.

[0079] A ratio of 1.5 to 2 times allows for moderate and stable acceleration of the airflow within the spiral tube through conical contraction. Specifically, when the inlet receives the premixed gas-liquid mixture flowing out of the swirl tube 10, the flow velocity is still at a moderate level. After contraction at a ratio of 1.5 to 2 times, the airflow velocity can be increased to a level sufficient to carry incompletely decomposed urea crystal particles, preventing the crystals from settling and adhering to the tube wall due to insufficient kinetic energy. At the same time, this acceleration will create a suitable low-pressure zone within the spiral groove 21, providing driving force for the stable generation of tire vortices, allowing the airflow to form a moderately intense rotating scouring within the groove.

[0080] The high-efficiency anti-crystallization swirling mixer for exhaust gas aftertreatment provided in this application also includes a swirling mixing tube 30, which is located inside the left cylinder 1 and connected to the swirling tube 10. The spiral tube 20 is located inside the swirling mixing tube 30. The tube wall of the swirling mixing tube 30 is provided with at least one row of windows 31 evenly distributed in the circumferential direction. The windows 31 are located downstream of the spiral tube 20. The windows 31 are convex outward and open on one side. The windows 31 are used to wedge the exhaust gas inward, which can not only supplement heat to reduce the crystal deposits on the inner wall of the spiral tube 20, but also guide the exhaust gas and the gas-liquid mixture flowing out of the spiral tube 20 to flow evenly in the circumferential direction, thereby enhancing the swirling effect of the airflow, promoting the decomposition of urea and the uniform mixing of gas and liquid.

[0081] For details, please refer to Figures 1 to 4 In the illustrated embodiment, the swirling mixing tube 30 is a cylindrical pipe structure coaxial with the swirling tube 10 and the spiral tube 20. Its inner diameter is adapted to the maximum outer diameter of the spiral tube 20 (i.e., the outer diameter of the inlet end of the spiral tube 20). A row of windows 31 are evenly opened around the circumference of the tube wall. (Refer to reference...) Figure 7 Window 31 is a single-sided open configuration that protrudes outward, with the open side facing the direction of the upstream heat flow inside the left cylinder 1.

[0082] Continue to refer to Figure 3 One end of the swirling mixing tube 30 is sealed to the swirling tube 10. The larger end of the swirling tube 10 is inserted into the air inlet of the swirling mixing tube 30. At the same time, the spiral tube 20 is located inside the air inlet of the swirling mixing tube 30 and is sealed to the larger end of the swirling tube 10. During operation, the airflow in the swirling tube 10 first flows into the spiral tube 20, is accelerated by the spiral tube 20, and then enters the downstream section of the swirling mixing tube 30.

[0083] Continue to refer to Figure 3 On the swirling mixing tube 30, the window 31 is located downstream of the spiral tube 20 so that the hot gas flow entering from the window and the gas-liquid mixture flowing out from the spiral tube 20 can form a confluence.

[0084] Because the spiral tube 20 is a tapered structure that gradually narrows along the airflow direction, a ring-shaped gap is naturally formed between the inner wall of the swirling mixing tube 30 and the outer wall of the spiral tube 20. This gap extends continuously along the axial direction of the swirling mixing tube 30, from the connection end of the swirling tube 10 and the swirling mixing tube 30 to the outlet end of the spiral tube 20, forming a complete heat flow channel.

[0085] Continue to refer to Figure 3 The volume of the inner cavity of the left cylinder 1 is greater than the volume of the swirl tube 10 and the swirling mixing tube 30. The swirl tube 10 and the swirling mixing tube 30 are both suspended inside the left cylinder 1 so that the airflow can enter the tube evenly through the annularly distributed blades and windows 31.

[0086] During operation, the exhaust gas entering the left cylinder 1 is premixed with atomized urea in the inlet swirl tube 10, then accelerated and swirled by the spiral tube 20 before entering the swirling mixing tube 30. The exhaust gas is a gas with residual heat, which is cooled by the urea, as urea is prone to crystallization at low temperatures. The window 31 allows another portion of the hot exhaust gas entering the left cylinder 1 to directly enter the swirling mixing tube 30 without premixing with urea. At this time, the exhaust gas can wedge into the annular gap through the window 31, forming a circling hot flow along the gap. This can uniformly heat the tube wall of the spiral tube 20, assisting in the decomposition of residual urea crystals on the tube wall, and the buffering effect of the annular gap can also prevent the hot flow from directly impacting the gas-liquid mixture flowing out of the spiral tube 20, thus avoiding flow field turbulence. Meanwhile, the heat flow guided by window 31 and the gas-liquid mixture flowing out of spiral tube 20 achieve circumferential uniform convergence in the downstream section of the swirling mixing tube 30. The incorporation of heat flow can not only supplement the heat required for urea decomposition, but also enhance the swirling intensity of the airflow, further break up the incompletely decomposed urea droplets, and improve the uniformity of gas-liquid mixing.

[0087] Optionally, the opening height of window 31 is 10mm to 15mm.

[0088] The opening height of window 31 refers to the vertical distance between the lower and upper edges of the opening of window 31 along the radial direction of the swirling mixing tube 30 (i.e., perpendicular to the axis of the swirling mixing tube 30 and pointing towards the inside and outside of the tube wall). It directly determines the cross-sectional area of ​​the channel through which upstream heat flow is allowed to enter window 31.

[0089] If the opening height is less than 10mm, the cross-sectional area of ​​the channel through which the heat flow enters is too small. The upstream heat flow in the left cylinder 1 cannot wedge into the annular gap in sufficient quantity. Not only will it fail to provide sufficient heat to the wall of the spiral tube 20 to assist in crystallization and decomposition, but the insufficient heat flow will also result in incomplete surrounding heat flow in the annular gap, weakening the uniform heating effect on the spiral tube 20. At the same time, the small amount of heat flow entering will also make it difficult to enhance the airflow swirling effect.

[0090] If the opening height is greater than 15mm, the excessive channel cross-sectional area will cause excessive heat flow to rush into the annular gap. On the one hand, it will break the flow field balance in the swirling mixing tube 30, causing turbulent vortices to be generated when the gas-liquid mixture flowing out of the spiral tube 20 merges with the heat flow, which will disrupt the uniform mixing of gas and liquid. On the other hand, the impact of excessive heat flow may also increase the exhaust back pressure. At the same time, the excessive protrusion of the window 31 will occupy too much space in the left cylinder 1, interfering with the overall flow field of the left cylinder 1.

[0091] An opening height of 10mm to 15mm ensures sufficient cross-sectional area for the heat flow channel, allowing the upstream heat flow to smoothly enter the annular gap to reheat the wall of the spiral tube 20 and assist in crystallization and decomposition. It also avoids flow field problems caused by excessive or insufficient heat flow. At the same time, it is adapted to the width of the annular gap between the swirling mixing tube 30 and the spiral tube 20 to ensure that the heat flow and gas-liquid mixture converge uniformly downstream, effectively enhancing the swirling effect.

[0092] Optionally, the opening direction of window 31 is set at an angle to the axial direction of the swirling mixing tube 30.

[0093] The opening direction of window 31 is tilted to adapt to the flow trend of airflow in the left cylinder 1. This improves the efficiency of heat flow introduction while ensuring the stability of the flow field in the annular gap and the swirling mixing tube 30, thereby enhancing the heat replenishment, anti-crystallization, and mixing effects.

[0094] From the perspective of airflow motion logic, refer to Figure 3 The hot exhaust gas in the left cylinder 1 (which does not enter the swirl tube 10 and has a higher temperature) flows downward and to the right. If the opening of window 31 is parallel or perpendicular to the axis, it will form an opposition (perpendicular or opposite) to the direction of the hot flow. This will either cause a surge in resistance and generate local vortices when the hot flow is introduced, or it will make it difficult for the hot flow to wedge into the annular gap because the opening in the forward direction cannot effectively capture the hot flow.

[0095] The inclined design allows the open end of window 31 to follow the flow trend of heat flow, forming a "guided" inlet, which can significantly reduce the flow resistance of heat flow into the annular gap, ensuring that heat flow can smoothly and sufficiently enter the gap, thereby quickly forming a heat flow channel around the wall of the spiral tube 20, and then uniformly heating the tube wall and assisting in the decomposition of residual crystals.

[0096] Meanwhile, the inclined design optimizes the convergence process of the heat flow and the gas-liquid mixture. The gas-liquid mixture flowing out of the spiral tube 20 flows along the axial direction of the swirling mixing tube 30 and has a certain spiral motion tendency. The inclined heat flow enters along the tangential direction of the annular gap, forming a "co-current superposition" with the gas-liquid mixture rather than an impact. In this way, the original flow state of the gas-liquid mixture is not disrupted, and the heat flow and the gas-liquid mixture are smoothly converged in the downstream section of the swirling mixing tube through the guidance of the inclined direction, which further enhances the swirling intensity of the overall airflow and promotes the breakup of undecomposed urea droplets and the uniform mixing of gas and liquid.

[0097] In one specific embodiment, the angle γ between the opening direction of the window 31 and the axial direction of the swirling mixing tube 30 is 30°~45°.

[0098] An angle of 30° or more allows the opening of window 31 to form a suitable entry angle, which avoids the opening being too close to the axis and the heat flow being difficult to wedge in effectively when the angle is too small (such as <30°), and also guides the heat flow smoothly into the gap by tilting the direction, reducing flow resistance; while an angle of less than 45° can prevent the opening from being too radially biased, and avoid the heat flow from forming a violent impact with the wall of window 31, which would cause local eddies.

[0099] An angle of 30° to 45° allows the heat flow entering the annular gap to flow along the tangential direction of the gap, forming a "co-current superposition" with the gas-liquid mixture flowing out of the spiral tube 20. In this way, the tangential motion of the heat flow not only does not disrupt the original flow state of the gas-liquid mixture, but also supplements it with swirling momentum, further enhancing the swirling intensity of the overall airflow and promoting the breakup of incompletely decomposed urea droplets and uniform mixing with the gas and liquid. If the angle is <30°, the heat flow direction is too axial, and the enhancing effect on the swirling during convergence is weak, failing to fully optimize the mixing effect. If the angle is >45°, the heat flow direction is too radial, and it is easy to form radial impact with the gas-liquid mixture during convergence, leading to turbulent flow field.

[0100] The high-efficiency anti-crystallization swirling mixer for exhaust gas aftertreatment provided in this application also includes a right cylinder 2, which is located downstream of the left cylinder 1 and is arranged separately from the left cylinder 1. The right cylinder 2 is connected to the exhaust gas outlet pipe. The right side wall of the left cylinder 1 facing the right cylinder 2 is provided with a first mounting hole, and the left side wall of the right cylinder 2 facing the left cylinder 1 is provided with a second mounting hole opposite to the first mounting hole. The left cylinder 1 and the right cylinder 2 are sealed and connected by a connecting pipe 40 passing through the first mounting hole and the second mounting hole. The right cylinder 2 is used to receive the gas-liquid mixture after it has been drawn together by the swirling mixing pipe 30 and the connecting pipe 40, and to provide it with a mixing buffer space.

[0101] For details, please refer to Figures 1 to 3 In the illustrated embodiment, both the left cylinder 1 and the right cylinder 2 are cylindrical structures with open tops (for connecting to the exhaust gas inlet or outlet pipe) and closed bottoms. The left cylinder 1 contains a swirl tube 10, a spiral tube 20, and a swirling mixing tube 30, coaxially arranged inside, forming a high-pressure, high-turbulence reaction chamber. The right side wall of the left cylinder 1 has a first mounting hole coaxial with the axis, the diameter of which matches the outer diameter of the connecting pipe 40. The left cylinder 1 is used to receive and constrain the airflow to complete premixing, crushing, and preliminary anti-crystallization treatment inside.

[0102] Continue to refer to Figures 1 to 3 The right cylinder 2 is located downstream of the left cylinder 1, forming a low-pressure, large-space homogenization chamber. A second mounting hole, coaxial with and directly opposite the first mounting hole in the left cylinder 1, is located on the left side wall of the right cylinder 2. The diameter of the second mounting hole is the same as that of the first mounting hole. The right cylinder 2 is used to receive the pre-treated gas-liquid mixture and provide a final mixing space for it.

[0103] Continue to refer to Figures 1 to 3The diameter of the connecting pipe 40 is smaller than the inner diameter of the left and right cylinders. One end of the pipe passes through the first mounting hole and is sealed and fixed to the left cylinder 1, and is sealed and connected to the outlet end of the swirling mixing pipe 30. The other end passes through the second mounting hole and is sealed and fixed to the right cylinder 2. In use, the exhaust gas enters the left cylinder 1, and under the synergistic action of the swirling pipe 10, the spiral pipe 20 and the swirling mixing pipe 30, the gas-liquid premixing, urea crushing and anti-crystallization treatment are completed. Then the gas-liquid mixture is rectified and merged through the connecting pipe 40 and enters the right cylinder 2. In the large volume space of the right cylinder 2, the swirling development and molecular-level uniform mixing are completed, and finally the gas flows to the subsequent SCR catalyst through the exhaust pipe.

[0104] The function of the left cylinder 1 is to achieve forced mixing of exhaust gas and urea, break up urea droplets, perform preliminary decomposition, and prevent crystallization on the pipe wall through the internal swirl tube 10, spiral tube 20, and swirling mixing tube 30, using a high-pressure, high-turbulence environment. The airflow velocity inside the left cylinder 1 is high (usually 15-25 m / s), the turbulence intensity is large, and the pressure fluctuation is significant, making it a high-energy, strong-interference working area.

[0105] The function of the right cylinder 2 is to provide a stable and open low-pressure space, allowing the airflow, which has undergone preliminary treatment by the left cylinder 1, to fully develop and diffuse with its swirling momentum, achieving a uniform molecular-level mixing of ammonia and exhaust gas. The airflow velocity inside the right cylinder 2 is low (typically 5-10 m / s), the flow field is stable, and the resistance is small, making it a calm and stable nurturing zone.

[0106] The left cylinder 1 and right cylinder 2 are designed as separate units connected by a connecting pipe 40 to avoid functional conflicts. If they were made into a single cavity, the high-intensity turbulence, vortex shedding, and pressure pulsations within the left cylinder 1 would directly impact the right cylinder 2, destroying the large-scale swirling flow that should be developing in an orderly manner within the right cylinder 2, preventing uniform mixing. If the left and right cylinders were eliminated entirely, and the mixed gas delivery pipe were directly connected upstream and downstream, the lack of the high-pressure forced pretreatment space of the left cylinder 1 would result in insufficient urea mixing and breakup. Simultaneously, the lack of the large-volume final mixing space of the right cylinder 2 would prevent the airflow from completing swirling development and homogenization, ultimately leading to NO... X Conversion efficiency has dropped significantly.

[0107] The presence of the connecting pipe 40 serves two purposes: it isolates the flow field interference between the left and right cylinders through a split structure and it enables a stable transition of airflow. On one hand, since the diameter of the connecting pipe 40 is smaller than the volume of the inner cavity of the left cylinder 1, it creates a local contraction, which dampens the turbulent airflow from the left cylinder 1, smooths the pressure fluctuations in the airflow, and achieves impedance matching from the high pressure and high turbulence of the left cylinder 1 to the low pressure and stable flow field of the right cylinder 2. On the other hand, it can forcibly constrain the mainstream airflow flowing out of the spiral tube 20 to meet the high-temperature bypass airflow entering the swirling mixing tube 30 through the window 31, and constrain the two airflows within a defined flow channel to complete the initial mixing and flow orientation, avoiding disorderly collisions between the two airflows in an unconstrained state that would lead to energy dissipation, thus preparing the flow field for the subsequent entry of the airflow into the right cylinder 2.

[0108] In one embodiment, the connecting pipe 40 includes a sleeve 41, a gasket 42, and a bushing 43 connected in sequence. The gasket 42 is pressed between the sleeve 41 and the bushing 43, and the three are fastened by a clamp 44. The sleeve 41 is connected to the swirling mixing pipe 30. The bushing 43 is connected to the right cylinder 2. The connecting pipe 40 is used to rectify and dampen the airflow from the left cylinder 1 and to provide thermal expansion compensation between the left cylinder 1 and the right cylinder 2.

[0109] For details, please refer to Figure 2 and Figure 3 In the illustrated embodiment, the connecting pipe 40 is a modular sealing structure, assembled from a sleeve 41, a gasket 42, a bushing 43, and a clamp 44. Each component is coaxial with the swirl tube 10, the spiral tube 30, and the swirling mixing tube 30 to ensure smooth airflow transition. One end of the sleeve 41 passes through the first mounting hole and is sealed and connected to the outlet end of the swirling mixing tube 30 (e.g., by welding or flange connection). The other end has a radially extending flange face, and the inner side of the flange face has a mounting groove that matches the gasket 42.

[0110] Continue to refer to Figure 2 and Figure 3 One end of the bushing 43 is inserted into the second mounting hole and sealed and fixed with the right cylinder 2. The other end of the bushing facing the sleeve 41 is also provided with a flange surface with a mounting groove so as to cooperate with the sleeve 41 to clamp the gasket 42.

[0111] Continue to refer to Figure 2 and Figure 3 The gasket 42 is an annular seal made of a high-temperature resistant elastic material (such as graphite or high-temperature resistant elastomer), with a thickness suitable for the mating gap between the pipe 41 and the bushing 43. It can produce elastic deformation under pressure to achieve a seal.

[0112] Continue to refer to Figure 2 and Figure 3The clamp 44 is a ring-shaped stainless steel component with a groove on its inner side that matches the flange faces of the sleeve 41 and the bushing 43. After the sleeve 41, gasket 42, and bushing 43 are installed in place, the clamp 44 is fitted onto the outside of the joint of the three components and circumferentially tightened with bolts to compress the three components into a sealed whole.

[0113] The connecting pipe 40, consisting of sleeve 41, gasket 42, bushing 43, and clamp 44, enables airflow rectification and convergence. The sleeve 41's pipe diameter is adapted to the outlet diameter of the swirling mixing pipe 30, forcibly confining the mainstream gas-liquid mixture flowing out of the spiral pipe 20 and the high-temperature bypass airflow flowing in from the window 31 within the pipe space. This prevents unconstrained diffusion of the two airflows, avoiding disorderly collisions and energy dissipation. Simultaneously, the linear structure of the pipe smooths pressure fluctuations in the highly turbulent airflow within the left cylinder 1, acting as a damping and rectifying mechanism, allowing the airflow to enter the right cylinder 2 in a stable flow state, laying the foundation for subsequent final mixing.

[0114] The gasket 42 is made of an elastic material with relatively low thermal conductivity. It is sandwiched between the sleeve 41 that connects the high temperature zone of the left cylinder 1 and the bushing 43 that connects the low temperature zone of the right cylinder 2, forming a controllable thermal resistance. This effectively blocks the radiative heat transfer from the high temperature wall of the left cylinder 1 to the right cylinder 2, preventing the temperature inside the right cylinder 2 from becoming too high, which could lead to premature thermal decomposition of urea or unnecessary oxidation of ammonia. This helps maintain a suitable temperature environment for gas-liquid molecular-level mixing in the right cylinder 2.

[0115] In addition, since the left cylinder 1 is close to the engine exhaust pipe, it has a high operating temperature, large vibration, and significant thermal expansion; the right cylinder 2 is connected to the aftertreatment system, and its operating conditions are relatively stable with a smaller thermal expansion. The elastic deformation capability of the gasket 42 and the flexible fastening method of the clamp 44 can absorb the thermal displacement difference caused by the uneven thermal expansion between the left cylinder 1 and the right cylinder 2, avoid structural cracking or sealing failure caused by the accumulation of thermal stress under rigid connection, and at the same time buffer the vibration transmitted by the left cylinder 1 to protect the stable final mixing flow field in the right cylinder 2 from being disturbed.

[0116] Optionally, the volume of the right cylinder 2 is greater than the volume of the left cylinder 1.

[0117] The right cylinder 2 is designed to have a larger volume than the left cylinder 1 because the difference in volume is necessary for both to fulfill their respective key functions.

[0118] Specifically, the left cylinder 1 needs to rely on structures such as the swirl tube 10 and the spiral tube 20 to forcibly intervene in the airflow and urea spray within a relatively compact space. The small volume design can ensure that the airflow maintains a high speed (15-25m / s) and a strong turbulent state within the left cylinder 1, allowing the double-row blades of the swirl tube 10 to effectively guide gas-liquid mixing and the tire vortex of the spiral tube 20 to efficiently scour and resist crystallization. If the volume of the left cylinder 1 is too large, the airflow speed will decrease, thereby weakening the shear force and swirling intensity of the forced intervention.

[0119] The right cylinder 2 needs to provide sufficient space and time for the gas-liquid mixture, which is still in a chaotic state after pretreatment by the left cylinder 1, to achieve uniform mixing at the molecular level. At this point, the larger volume of the right cylinder 2 allows the gas flow velocity to drop sharply (to 5-10 m / s) after entering through the narrow channel of the left cylinder 1, extending the hydrodynamic residence time and creating conditions for turbulence decay and molecular diffusion of NH3 and exhaust gases, thus avoiding uneven mixing due to insufficient residence time. Simultaneously, the large volume promotes the full development of swirl. If the volume of the right cylinder 2 is similar to or smaller than that of the left cylinder 1, the swirl will be exhausted before it can fully act on all gas clusters, failing to achieve uniform mixing. Furthermore, the large volume can absorb the instantaneous velocity and concentration fluctuations caused by the high turbulence in the left cylinder 1, providing a stable inlet gas flow rate and concentration for the downstream SCR catalyst. This is crucial for improving the catalyst's NO content. X Conversion efficiency and lifespan are key factors.

[0120] In one specific embodiment, the volume of the right cylinder 2 is 1.5-3 times that of the left cylinder 1, which is used to provide sufficient space for airflow development and ensure sufficient mixing residence time, thereby ensuring that the ammonia gas and the exhaust gas are mixed evenly.

[0121] A volume of 1.5 times that of the left cylinder 1 represents the lower limit for the right cylinder 2 to achieve basic mixing and buffering effects. When the volume of the right cylinder 2 is 1.5 times that of the left cylinder 1, the flow velocity after entering the right cylinder 2 from the left cylinder 1 (high velocity, high turbulence) can be reduced to 1 / 3 to 1 / 2 of that in the left cylinder 1. This provides at least 0.3 to 0.5 seconds of residence time for the gas-liquid mixture (meeting the basic time required for the diffusion of NH3 and exhaust gas molecules), and allows the large-scale swirling flow from the mixed gas delivery pipe to fully expand (the swirling diameter can cover more than 2 / 3 of the cross-section of the right cylinder 2), avoiding swirling contraction and mixing blind zones due to insufficient space. At the same time, a volume of 1.5 times can also initially buffer the velocity and pressure fluctuations from the left cylinder 1, ensuring the stability of the downstream SCR catalyst intake. If the volume is less than 1.5 times, the aforementioned effects of velocity reduction, residence, swirling development, and buffering will be significantly weakened.

[0122] Three times is the upper limit to avoid over-design. If the volume of the right cylinder 2 exceeds three times, although it can further extend the residence time and enhance the buffering effect, it will cause the airflow velocity in the right cylinder 2 to be too low, which will easily form a local stagnation zone on the cylinder wall. This will cause the incompletely decomposed urea droplets to accumulate and crystallize in the stagnation zone. At the same time, the excessive volume will increase the material cost and the vehicle installation space (especially the space of the after-treatment system of commercial vehicles is limited), and the pressure loss may also increase slightly due to the excessively long airflow path.

[0123] The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment provided in this application further includes: a transition pipe 50, one end of which is connected to the connecting pipe 40, and the other end of which passes through the second mounting hole into the right cylinder 2; a guide plate 60, which is disposed at the gas outlet end of the transition pipe 50 in the right cylinder 2; wherein, the cyclone pipe 10, the spiral pipe 20, the cyclone mixing pipe 30, the connecting pipe 40 and the transition pipe 50 constitute a mixed gas delivery pipe, which is used to promote the mixing of exhaust gas entering the left cylinder 1 with urea and can guide the gas-liquid mixture into the left cylinder 1. Right cylinder 2; the guide plate 60 is used as the output window of the mixed gas conveying pipe; the guide plate 60 is provided with multiple guide vanes 61 distributed at intervals along a straight direction, the straight direction being perpendicular to the axial direction of the mixed gas conveying pipe. The guide vanes 61 are arranged in an outward-facing form to guide the gas-liquid mixture flowing out of the mixed gas conveying pipe to form a radial swirling flow, which further cooperates with the wide space of the right cylinder 2 to form a buffer, so as to prolong the residence time of the gas-liquid mixture, improve the mixing uniformity of ammonia and tail gas, and reduce the risk of excessive local ammonia concentration.

[0124] For details, please refer to Figures 1 to 4 In the illustrated embodiment, the transition pipe 50 is a cylindrical high-temperature resistant pipe (made of the same material as the connecting pipe 40, which is stainless steel 304) that is coaxial with other components of the mixed gas conveying pipe. One end of the pipe is welded or flanged and sealed to the outlet end of the connecting pipe 40. The pipe diameter is the same as the diameter of the connecting pipe 40 (to ensure that there is no sudden change in airflow). The other end extends into the right cylinder 2 after passing through the second mounting hole.

[0125] Combined with reference Figure 8 The orifice plate 60 is a circular plate structure, which is covered by a circumferentially distributed skirt on the outlet end face of the transition pipe 50. Multiple guide vanes 61 are distributed at intervals on the orifice plate 60 along a straight line perpendicular to the axis of the mixed gas delivery pipe. All guide vanes 61 are outwardly flared (the vanes are inclined away from the mixed gas delivery pipe), and the inclination angle is adapted to the airflow outflow direction so as to guide the airflow to form a swirling flow that diffuses radially along the right cylinder 2.

[0126] The mixed gas conveying pipe, consisting of a swirl tube 10, a spiral tube 20, a swirling mixing tube 30, a connecting pipe 40, and a transition pipe 50, is a gas-liquid mixing and transmission channel that runs through the left cylinder 1 to the right cylinder 2. Specifically, the swirl tube 10 is a diffuser cone-shaped pipe with double rows of counter-rotating blades on its wall for forced premixing of exhaust gas and atomized urea; the spiral tube 20 is a constricting cone-shaped pipe with a spiral concave-convex structure on its inner wall for urea breakup and anti-crystallization; the swirling mixing tube 30 is a cylindrical pipe with a window 31 on its wall, forming an annular gap with the internal spiral tube 20 for heat replenishment and flow convergence; one end of the connecting pipe 40 connects to the swirling mixing tube 30, and the other end connects to the transition pipe 50, for rectification, thermal management, and sealing.

[0127] Although the guide plate 60 is not the main body of the conveying pipe, it is the functional output window of the conveying pipe. Through the outward-curving guide vanes 61, it can transform the straight airflow from the transition pipe 50 into a radially diffused swirling flow, allowing the gas-liquid mixture to form a "spiral diffusion" motion in the right cylinder 2 instead of disordered diffusion. In this way, the residence time of the airflow in the right cylinder 2 can be extended, and the gas-liquid mixture can be forced to mix fully in the swirling flow, thereby avoiding excessively high local ammonia concentration (such as ammonia concentration accumulation near the axis of the transition pipe 50).

[0128] In one specific embodiment, a portion of the exhaust gas enters the small end of the cyclone tube 10 from the left cylinder 1, where it encounters the atomized urea sprayed from the urea nozzle 3. Under the action of the diffusion cone of the cyclone tube 10, the exhaust gas velocity decreases. The first row of outward-facing blades 11 "throws" a portion of the exhaust gas toward the central area of ​​the cyclone tube 10, forcibly cutting into the urea spray cone to achieve initial mixing. The second row of inward-facing blades 12 "entrains" the high-temperature exhaust gas from the left cylinder 1 back into the cyclone tube 10, forming a dynamic airflow exchange, ultimately completing uniform premixing. The premixed gas-liquid mixture flows into the spiral tube 20. The contracting cone shape of the spiral tube 20 causes the airflow velocity to rise again, thereby enhancing the transport capacity for crystalline particles. At the same time, the spiral concave-convex structure on its inner wall can form a stable tire vortex in the spiral groove 21, continuously flushing the residual urea crystals on the tube wall and simultaneously shearing the incompletely broken droplets, achieving anti-crystallization and secondary crushing. The gas-liquid mixture after cyclone treatment enters the cyclone mixing tube 30. The window 31 on the wall allows hot exhaust gas to be wedged inward. The hot gas surrounds the spiral tube 20, providing uniform heating to the tube wall and aiding in the decomposition of residual crystals. Simultaneously, it merges with the mainstream gas-liquid mixture downstream of the swirling mixing pipe 30, further enhancing the swirling intensity. The merged gas flow enters the connecting pipe 40. The confined flow channels of the sleeve 41 and bushing 43 rectify and dampen the gas flow, smoothing pressure fluctuations. The gasket 42 blocks the high temperature of the left cylinder 1, preventing the temperature inside the right cylinder 2 from exceeding 350℃ and causing ammonia oxidation. The gas flow passes through the transition pipe 50 and is smoothly guided to the right cylinder 2. Finally, it is transformed into radial swirling flow through the outward-facing blades 61 of the guide plate 60 and diffuses and develops in the wide space of the right cylinder 2. The swirling motion prolongs the residence time of the gas-liquid mixture, enabling molecular-level uniform mixing of ammonia and exhaust gas. This allows the local ammonia concentration deviation to be controlled within ±10%, fully meeting the National VII emission standards for NO. X The need for conversion efficiency.

[0129] In one embodiment, the upper part of the flow guide plate 60 is provided with four gradually opening flow guide blades 61. The outward turning angle of the four flow guide blades 61 changes monotonically along their arrangement direction, which is used to compensate for the circumferential airflow non-uniformity generated by the spiral tube 20 and the swirling mixing tube 30.

[0130] It should be explained that after the airflow passes through the spiral tube 20, the swirling mixing tube 30, and the connecting pipe 40, the cross-sectional velocity is unevenly distributed with a high center and a low edge, and may have an asymmetric swirling component.

[0131] If the number of guide vanes 61 is less than 4 (e.g., 2-3), a flow guidance blind zone will appear in the pipe cross-section, and some airflow cannot be guided, easily forming local vortices; if there are more than 4 (e.g., 5-6), the channel will be excessively blocked, increasing flow resistance and even causing airflow separation, leading to increased back pressure. However, 4 guide vanes 61 are evenly arranged in a straight line, which can completely cover the airflow cross-section, with no blind zone and no increased resistance. At the same time, it provides sufficient adjustment units for "customized flow guidance" and compensates for uneven flow through angle differences.

[0132] For details, please refer to Figure 8 In the illustrated embodiment, four guide vanes 61 are spaced apart in the left-right direction, and the outward turning angle of the guide vanes 61 decreases as they move to the right.

[0133] The reason for the gradually changing outward angle of the guide vanes 61 is that the radially involute layout allows the four guide vanes 61 to uniformly cover the airflow cross-section. This adapts to the velocity differences between the airflow center and the edge, ensuring that the guiding force of the guide vanes 61 on the airflow in different areas is precisely matched with the incoming flow velocity. This prevents the high-speed airflow in the center from breaking through the vortex due to insufficient guidance, or the low-speed airflow at the edge from separating due to excessive guidance. Furthermore, the reasonable number of guide vanes 61 balances the integrity of the guidance and the flow resistance. It avoids blind spots in the pipe cross-section due to too few vanes, and excessive obstruction of the airflow channel due to too many vanes. At the same time, it provides sufficient units for customized angle adjustment. Combined with the monotonically changing outward angle of the guide vanes 61 along the arrangement direction, it can specifically compensate for the circumferential non-uniformity of the incoming flow. The angle difference of different vanes cancels out the asymmetrical vortex component, allowing the originally turbulent airflow to form a vortex with a central axis and relatively uniform velocity distribution after being guided by the radially involute vanes. This ensures the uniformity of subsequent gas-liquid mixing and the efficiency of the denitrification reaction.

[0134] Optionally, the outward turning angle δ of the guide vane 61 is 50°~90°.

[0135] If the outward turning angle is less than 50°, the tangential guiding force of the guide vane 61 on the airflow is insufficient, and it cannot effectively convert the straight airflow from the transition pipe 50 into radial swirling flow. This will result in weak swirling flow intensity and small diffusion range. After the airflow enters the right cylinder 2, it will be difficult to develop fully, ultimately leading to a shortened mixing residence time and excessively high local ammonia concentration.

[0136] If the outward angle is greater than 90°, the angle between the guide vane 61 and the airflow direction will be too large, which will significantly increase the airflow resistance. This may not only cause the airflow to separate on the blade surface and form local vortices (which will disrupt the flow field stability), but may also lead to an increase in exhaust back pressure, affecting the exhaust efficiency of the engine.

[0137] The range of 50° to 90° provides sufficient tangential thrust to generate a swirling flow of appropriate intensity, while avoiding a surge in drag and turbulence caused by excessive angle. At the same time, this range provides ample angle adjustment space for the four guide vanes 61 to increase in opening along a straight line, which can compensate for the circumferential velocity deviation of the upstream flow through a small angle difference.

[0138] In one specific embodiment, along the straight direction, the outward turning angles of the four guide vanes 61 are 55°, 65°, 75°, and 85°, respectively. Under actual operating conditions, the airflow output from the mixed gas delivery pipe exhibits a circumferential deviation of "increasing flow velocity in a clockwise direction" (the flow velocity is approximately 15 m / s near the 0° circumferential position and approximately 18 m / s near the 270° circumferential position). Therefore, the guide vanes 61 with increasing angles are set accordingly: the 55° vane corresponds to the 0° circumferential region with lower flow velocity, using gentle guiding force to avoid momentum loss of low-speed airflow; the 65° and 75° vanes are adapted to the intermediate flow velocity region, balancing the guiding and momentum transfer; the 85° vane corresponds to the 270° circumferential region with the highest flow velocity, using stronger tangential thrust to convert excess momentum into rotational momentum. Ultimately, this angular distribution allows the tangential velocity components at the exit of all four blades to be stabilized at 12~13 m / s, generating a large vortex with a central axis and a symmetry of over 98%. After the airflow enters the right tube 2, it can complete diffusion mixing within 0.5 seconds and control the local ammonia concentration deviation within ±8%, which satisfies the requirements for mixing uniformity and avoids back pressure increase (the measured back pressure only increased by 1.2 kPa).

[0139] Optionally, a notch is provided on the upper side of the transition tube 50.

[0140] For details, please refer to Figures 2 to 4 In the illustrated embodiment, the transition pipe 50 is a cylindrical high-temperature resistant pipe coaxial with other components of the mixed gas conveying pipe (connecting pipe 40, orifice plate 60). The end of the transition pipe 50 away from the connecting pipe 40 is provided with a notch. The notch is opened along the axial direction of the transition pipe 50 on the upper half of the pipe body, and the length of the notch along the axial direction is consistent with the length of the extension section of the transition pipe 50 in the right cylinder 2. The radial width is about 1 / 4 of the diameter of the transition pipe (ensuring airflow without compromising the structural strength of the pipe body). The edge of the notch is smoothly polished to reduce airflow resistance.

[0141] The high-temperature bypass heat flow entering the swirling mixing tube 30 through window 31 will flow around the gap between the transition tube 50 and the inner wall of the right cylinder 2 to the outside of the transition tube 50. The presence of the gap provides a smooth entry channel for this heat flow, allowing it to merge into the mainstream gas-liquid mixture in the transition tube 50. This avoids the formation of a stagnant zone on the upper side of the transition tube due to the absence of a gap (especially since the upper side is prone to low flow velocity due to gravity and airflow inertia), thus preventing the accumulation and crystallization of incompletely decomposed urea droplets in the stagnant zone. At the same time, the entry of the high-temperature bypass heat flow can supplement heat, assisting in the further decomposition of residual urea and enhancing the foundation of the denitrification reaction.

[0142] In addition, the notch can balance the pressure difference inside and outside the transition pipe 50, avoid excessive pressure inside the pipe causing airflow velocity fluctuations, ensure that the airflow velocity through the guide plate 60 is uniform and the flow state is stable, and create favorable conditions for the guide vane 61 to generate symmetrical radial swirl. Moreover, the design of the notch along the axial length being consistent with the length of the extension section of the transition pipe 50 in the right cylinder 2 and the edge being smoothly polished does not damage the structural strength of the transition pipe 50, and can reduce airflow resistance, ensuring that the airflow path from the transition pipe 50 to the right cylinder 2 is continuous and smooth, and helps the gas-liquid mixture to fully diffuse and mix in the right cylinder 2.

[0143] Furthermore, the axial length of the notch is 1 / 2 of the transition tube 50.

[0144] The total length of the transition tube 50 comprises two parts: a fixed section that connects to the connecting pipe 40, and a heat flow interaction section extending into the right cylinder 2 (the bypass heat flow mainly flows around the tube body in this area). Half the axial width allows the notch to completely cover the heat flow interaction section without touching the fixed section.

[0145] This design ensures that the bypass heat flow (higher temperature, used for heat replenishment and anti-crystallization) flowing around to the outside of the transition pipe 50 can fully merge into the mainstream airflow inside the pipe through the gap, avoiding insufficient heat flow convergence due to the gap being too short (e.g., less than 1 / 2), which would create a stagnant zone in the uncovered area. It also prevents the gap from being too long (e.g., greater than 1 / 2) and extending to the docking fixed section, thus damaging the sealing connection between the transition pipe and the connecting pipe.

[0146] In addition, the 1 / 2 notch width can retain 50% of the complete length of the tube, ensuring that the tube has sufficient rigidity to resist the impact of airflow and the weight load of the guide plate 60, and avoiding insufficient tube strength, deformation or breakage due to excessive notch length; if the notch width exceeds 1 / 2, the complete area of ​​the tube is too small, which is prone to stress concentration at the root of the extension section, which may cause structural failure after long-term use and affect the overall stability of the mixer.

[0147] Optionally, the top of the flow guide plate 60 is provided with an axial flow guide vane 62, which is folded toward the transition tube 50 so that the axial flow guide vane 62 faces the notch.

[0148] For details, please refer to Figures 2 to 4 In the illustrated embodiment, the axial guide vane 62 is a small block of high-temperature resistant stainless steel component integrally formed with the guide plate 60 (the material is the same as that of the guide plate 60, which is suitable for high-temperature exhaust gas conditions). It extends from the center of the top edge of the guide plate 60 along the transition tube 50 and folds inward toward the inside of the transition tube 50, so that the axial guide vane 62 faces the notch and is suspended above the notch.

[0149] The axial guide vane 62 can adapt to the heat flow convergence requirements of the notch, optimize the flow pattern, and enhance the anti-crystallization effect. Specifically, the high-temperature bypass heat flow that flows around to the outside of the transition tube 50 will smoothly flow into the notch along the folding direction towards the inside of the transition tube 50, using the axial guide vane 62 as a guide slope. This avoids the heat flow directly impacting the edge of the notch and forming local eddies, which not only improves the heat flow convergence efficiency but also reduces the risk of urea droplet accumulation in the eddy region.

[0150] Furthermore, the folding angle of the axial guide vane 62 is adapted to the notch, and the bypass hot flow and the mainstream gas-liquid mixture in the transition tube 50 can form a forward superposition rather than a countercurrent, thereby reducing the resistance loss when the airflow converges. At the same time, it avoids the flow velocity fluctuation of the mainstream airflow due to the inflow of hot flow, ensuring the stability of the airflow through the guide plate 60, and creating favorable conditions for the subsequent guide vane 61 to generate symmetrical radial swirl.

[0151] Optionally, the included angle ε between the axial guide vane 62 and the guide orifice plate 60 is 30°~60°.

[0152] If the included angle ε is less than 30°, the axial guide vane 62 will be too close to the end face of the guide orifice plate 60. In this case, the bypass hot flow needs to overcome greater flow resistance to turn along the vane and merge into the mainstream in the transition tube 50. This can easily lead to a sudden drop in the hot flow velocity, and even form a local stagnation zone below the axial guide vane 62. Not only will it fail to provide efficient heat replenishment, but it may also cause droplets to accumulate in the stagnation zone, thus increasing the risk of crystallization. At the same time, the gentle angle has a very weak rectifying effect on the mainstream airflow, and the mainstream is prone to velocity fluctuations due to the influx of hot flow, affecting the subsequent flow guidance of the guide orifice plate 61.

[0153] If the included angle ε is greater than 60°, the axial guide vane will fold steeply, with the guiding direction excessively biased towards the axis of the transition tube 50. At this time, the bypass hot flow will impact the mainstream airflow at a near-vertical angle, forming a strong vortex at the confluence. This not only consumes airflow and increases exhaust back pressure, but also disrupts the straight flow state of the mainstream, resulting in uneven distribution of airflow velocity entering the guide orifice plate (too high velocity at the center and too low velocity at the edges). The resulting vortex will exhibit axial displacement, leading to a significant decrease in the mixing uniformity within the right cylinder 2.

[0154] At an angle of 30° to 60°, the guide channel is moderately inclined, allowing the bypass heat flow to smoothly change direction along the surface of the plate with minimal resistance. This ensures heat replenishment efficiency while avoiding eddies and stagnation. At the same time, the moderately inclined plate helps to rectify the main flow, keeping the velocity deviation of the airflow after convergence within ±5%, thus providing a stable flow field basis for the generation of symmetrical swirling flow by the guide orifice plate 60.

[0155] In one embodiment, the upper part of the flow guide plate 60 is provided with four flow guide blades 61. The four flow guide blades 61 have the same width. The two flow guide blades 61 in the middle have the same height and are higher than the other two flow guide blades 61 on both sides. The other two flow guide blades 61 on both sides have the same height.

[0156] For details, please refer to Figure 8 In the illustrated embodiment, the four guide vanes 60 are aligned on the same straight line at their lower ends and staggered at their upper ends. The two guide vanes 61 in the middle are high (approximately 3 / 4 of the diameter of the guide vane 61), while the other two guide vanes 61 on the sides are low (approximately 1 / 2 of the diameter of the guide vane 61). Because the ventilation openings of the guide vanes 61 are symmetrical, the projection of the four guide vanes 60 onto the surface of the guide vane 61 is generally convex arc-shaped.

[0157] It needs to be explained that the gas-liquid mixture flowing in through the connecting pipe 40 and the transition pipe 50 exhibits a distribution pattern of dense flow rate and sparse flow rate at the center and sparse flow rate at the edges. This is because the central region is the core mainstream airflow that flows directly out of the spiral pipe 20, with a large flow rate and high velocity (usually 18~22 m / s), and carries urea decomposition products, resulting in a higher concentration. Therefore, stronger guiding force is required to effectively convert it into a stable vortex. On the other hand, the side regions are mainly the peripheral airflow formed by the diffusion of the bypass heat flow from the window 31 and the core airflow. The flow rate is small and the velocity is low (usually only 10~15 m / s), and it can follow the vortex without excessive guiding force.

[0158] To address this, a tall blade is positioned in the middle, providing ample tangential guiding force to the core high-speed airflow through a larger blade area. This efficiently converts the linear momentum into rotational momentum, preventing insufficient guiding force from causing the core airflow to break through the vortex and form local turbulence. Short blades are positioned on both sides, which can guide the bypass hot flow and edge airflow to smoothly integrate into the main vortex with appropriate guiding force. This also avoids the blades from blocking the airflow channel due to excessive height (if the blades on both sides are the same height as the middle one, it will excessively impede the low-speed airflow, increase flow resistance, or even cause airflow separation, thus disrupting the flow field stability).

[0159] Meanwhile, the tall blades in the middle and the short blades on both sides respectively guide the core airflow and the edge airflow. The reaction forces generated by the two cancel each other out with the axis of symmetry of the air opening as the center. This can prevent the guide plate 61 from vibrating laterally due to uneven force (especially when the engine operating conditions fluctuate or the airflow speed changes), thus ensuring that the generated vortex axis is always centered and will not shift due to vibration.

[0160] Optionally, a pressure relief through hole 63 is provided in the height difference area between the two guide vanes 61, one high and one low, to balance the pressure before and after the guide plate 60.

[0161] For details, please refer to Figure 8 In the illustrated embodiment, a pressure relief through hole 63 is provided in the triangular fan-shaped area formed by the height difference between the two guide vanes 61 (one tall and one short) on the left side of the flow guide plate 60, and a pressure relief through hole 63 is also provided in the triangular fan-shaped area formed by the height difference between the two guide vanes 61 (one tall and one short) on the right side. The pressure relief through hole 63 is a circular through hole, and the diameter is usually 5~15mm (to adapt to the airflow rate and not damage the structural strength of the orifice plate).

[0162] When the guide plate 60 is working, the airflow in front of the plate (the side closer to the transition pipe 50) is constrained by the transition pipe 50 and is in a "constrained flow" state with relatively high pressure; the airflow behind the plate (the side away from the transition pipe 50) is guided by the guide vanes 61 and is in a swirling diffusion state with relatively low pressure. Especially in the area of ​​the height difference between the two vanes, one high and one low, the airflow will accelerate through due to the flow around the plate (similar to water flowing through a narrow channel), which will further reduce the pressure behind the plate in this area, forming a local low-pressure area.

[0163] If the pressure relief through-hole 63 is not provided, the low-pressure area will produce an adsorption effect. On the one hand, it may cause some of the swirling airflow behind the plate to flow back to the front of the plate, disrupting the stable flow of the mainstream airflow in the transition tube 50, and even causing incompletely decomposed urea droplets to accumulate in the backflow area. On the other hand, the low-pressure area will induce periodic vortex shedding (airflow alternately generates and sheds vortices at the gap). This unstable vortex will impact the swirling flow guided by the guide vane 61, causing the swirling axis to shift and the diffusion to be uneven.

[0164] The pressure relief through-hole 63 can eliminate the above problems through pressure compensation. Specifically, the high-pressure airflow in front of the plate can flow smoothly into the low-pressure area behind the plate through the pressure relief through-hole 63, balancing the pressure difference before and after the orifice plate in real time and avoiding excessive negative pressure in the local low-pressure area; at the same time, the airflow flowing into the pressure relief through-hole 63 can fill the low-pressure space in the high-low difference area, suppress the generation of vortex street and ensure stable diffusion of vortex.

[0165] Optionally, at least one row of small holes 64 is provided on the guide plate 60 below the guide vane 61.

[0166] For details, please refer to Figure 8 In the illustrated embodiment, the lower region of the flow guide plate 60 is provided with two rows of small holes 64. The small holes 64 are circular through holes, with a diameter smaller than the pressure relief through holes 63 at the top. The holes vertically penetrate the flow guide plate 60, and the edges of the holes are rounded to prevent localized eddies or wear when the airflow passes through. The spacing between the upper and lower rows of small holes 64 is approximately 1-2 mm. The two rows of flow guide plates 60 are evenly distributed and arranged in a completely symmetrical layout with the longitudinal central axis of the flow guide plate 60 as the axis of symmetry.

[0167] The small holes 64 help to establish a stable axial pressure gradient. Specifically, when the guide vanes 61 force the airflow to rotate, a low-pressure vortex core is formed at the center of the guide plate 60. The upper pressure relief through holes 63 can provide the main pressure relief outlet for this core. The two rows of small holes 64 at the bottom can establish a secondary, controlled axial pressure relief channel downstream of the vortex core (closer to the mixing space of the right cylinder 2). By continuously releasing a small amount of airflow, it can maintain a smooth and stable low-pressure axis over a longer axial distance, preventing the vortex from diverging or drifting in the right cylinder 2, and ensuring that it can fully diffuse and mix according to the expected trajectory.

[0168] It should be noted that relying solely on the upper pressure relief through-hole 63 for complete pressure relief would cause a sudden increase in local airflow velocity at the pressure relief through-hole 63, which would disrupt the symmetry of the swirling flow. The presence of the lower small holes 64, however, distributes the pressure relief task to different axial positions of the guide plate 60 (the upper pressure relief through-hole 63 handles upstream pressure relief, and the lower small holes 64 handle downstream pressure relief), thus releasing pressure more smoothly in the central low-pressure area and avoiding drastic local pressure surges. This design ensures that the swirling flow intensity is not weakened while effectively controlling the overall back pressure of the mixer, preventing pressure fluctuations from affecting the engine's exhaust efficiency.

[0169] In addition, the lower part of the orifice plate 60 is a high-risk area for urea low-temperature crystallization and carbon soot deposition due to its proximity to the low-temperature end of the bottom of the right cylinder 2. In particular, the leeward side of the blades and the junction of the orifice plate and the transition pipe 50 are prone to forming dead corners of dirt accumulation. The small airflow from the small holes 64 (flowing from the high-pressure area in front of the plate to the low-pressure area behind the plate) can form a "micro-purge airflow" that gently and continuously flushes the surface of the orifice plate and the dead corner area, and promptly removes incompletely decomposed urea droplets and carbon soot particles, thereby achieving self-cleaning of the orifice plate, avoiding dirt accumulation that blocks the flow channel or disrupts the flow field, and ensuring the long-term and stable operation of the orifice plate 60.

[0170] Optionally, the aperture of the small hole 64 is 2mm-10mm, and the total opening area of ​​the small hole 64 accounts for 10%-25% of the area of ​​the guide plate 60.

[0171] Exhaust gas contains carbon soot particles (typically with a maximum diameter of about 1 mm), and urea may also form solid crystal nuclei (with a diameter of about 0.5-1 mm) under low-temperature conditions. If the pore size is less than 2 mm, these tiny particles are easily trapped inside the pores, leading to blockage over time. This results in loss of pressure relief and purging functions, and may also cause localized flow turbulence due to blockage. A lower limit of 2 mm ensures that the pore size is significantly larger than the maximum size of these impurities, allowing them to pass smoothly with the airflow and fundamentally preventing blockage.

[0172] Furthermore, if the orifice diameter is greater than 10 mm, the airflow exiting the small orifice will form a strong jet, whose momentum is sufficient to impact or even tear apart the vortex structure of the main vortex, causing the vortex to diverge and the axis to shift, thus disrupting the mixing uniformity within the right cylinder 2. The upper limit of 10 mm ensures that the orifice diameter is much smaller than the core size of the main vortex (the size of the ventilation opening due to the guide vane 61), allowing the airflow from the small orifice to serve only as a "micro-supplement" and not to interfere with the stable shape of the main vortex.

[0173] A 10% percentage is the minimum guarantee. Even under low engine load (minimum exhaust flow) conditions, a 10% orifice area can provide sufficient airflow to ensure that the airflow from the small holes has sufficient momentum to continuously purge the surface of the orifice plate (especially the leeward side of the blades, the junction of the plate and other dead corners where dirt accumulates), thus preventing urea crystallization and carbon soot deposition. If the percentage is less than 10%, the purge airflow is insufficient, and the self-cleaning function will be lost because it cannot blow away the dirt. At the same time, the pressure relief capacity is weakened, and it is not possible to effectively balance the pressure before and after the orifice plate, which can easily cause vortex street.

[0174] The 25% limit is the upper limit constraint. The orifice plate 60 needs to withstand the high temperature of the exhaust gas (usually 300-500℃) and the impact of the airflow. Too many openings will significantly weaken the rigidity of the plate, especially under thermal stress cycle (cold start-high temperature operation-shutdown cooling), which can easily lead to cracks or deformation. At the same time, if the proportion exceeds 25%, the small holes will "steal" too much of the core airflow that should be used to generate the main vortex, resulting in insufficient main vortex strength and inability to fully diffuse and mix in the right cylinder 2.

[0175] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment, characterized in that, include: Left cylinder (1) is connected to the exhaust gas intake pipe; A urea nozzle (3) is located on one side of the left cylinder (1) and is used to spray atomized urea. A swirl tube (10) is located inside the left cylinder (1) and connected to the urea nozzle (3). The swirl tube (10) is cone-shaped, and the diameter of the swirl tube (10) increases the further away from the urea nozzle (3). A spiral tube (20) is disposed inside the left cylinder (1), connects to the vortex tube (10), and extends coaxially with the vortex tube (10). The spiral tube (20) is also set in a conical shape. The further away from the vortex tube (10), the smaller the diameter of the spiral tube (20). Along the axial direction of the cyclone tube (10), the tube wall of the cyclone tube (10) is provided with two rows of blades evenly distributed in the circumferential direction. The first row of blades (11) near the urea nozzle (3) is arranged in an outward-facing form, and the second row of blades (12) near the spiral tube (20) is arranged in an inward-facing form. The conical diffusion structure and double-row counter-rotating blades of the swirl tube (10) can not only increase the intake volume to meet the flow requirements of the exhaust gas, but also guide the exhaust gas and urea to mix precisely and avoid the squeezing or mixing blind spots of the spray pattern. The inner wall of the spiral tube (20) is provided with a spiral concave-convex structure, which includes a spiral ridge protruding along the inner wall and a spiral groove (21) recessed. The spiral ridge and the spiral groove (21) are distributed alternately and continuously to form a spiral channel with alternating concave and convex sections. The spiral groove (21) extends spirally along the gas flow direction. The conical contraction structure and the spiral concave-convex structure of the spiral tube (20) work together to accelerate the airflow and enhance the transport capacity of the crystals, and also to scour the tube wall through the tire vortex formed by the spiral groove (21), increase the heating and sliding area, and reduce the adhesion of crystals. During operation, the first row of blades (11) can guide the exhaust gas to deeply contact the urea and expand the gas-liquid contact range. The second row of blades (12) can suppress the excessive squeezing of the exhaust gas and prevent droplet aggregation. The two work together to allow the exhaust gas and atomized urea to form a uniform swirling premix, and then flow into the spiral tube (20). Through conical contraction acceleration and spiral action, the urea is broken down and anti-crystallization is achieved.

2. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 1, characterized in that, The outward turning angle α of the first row of blades (11) is 25°~35°, and the inward turning angle β of the second row of blades (12) is 20°~30°, and α>β; And / or, the first row of blades (11) and the second row of blades (12) correspond one-to-one, the two blades corresponding to each other along the generatrix of the cone are adjacent to each other, and the openings formed by the two are interconnected; And / or, the first row of blades (11) has a coverage rate of 40% to 60% in the circumferential direction of the swirl tube (10), and the second row of blades (12) has a coverage rate of 50% to 70% in the circumferential direction of the swirl tube (10); And / or, the axial chord length of the first row of blades (11) and the second row of blades (12) is 0.2 to 0.5 times the local diameter of the cyclone tube (10); And / or, the axial length of the first row of blades (11) and the second row of blades (12), and their circumferential opening, are configured to maintain the exhaust back pressure of the system within a predetermined range while forming a uniform swirling premix in the swirling tube (10). And / or, the ratio of the inlet and outlet diameters of the swirl tube (10) is 1.2 to 1.8, which helps to decelerate and reduce the pressure of the incoming flow, creating stable flow field conditions for subsequent fine gas-liquid premixing achieved by double-row reverse blades.

3. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 1, characterized in that, The pitch L of the spiral concave-convex structure is 15mm~25mm, so as to ensure that a tire vortex is formed in the spiral groove (21); And / or, the groove depth of the spiral concave-convex structure is 0.2 to 0.4 times the pitch L; And / or, the ratio of the inlet and outlet diameters of the spiral tube (20) is 1.5 to 2.

4. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to any one of claims 1-3, characterized in that, It also includes a swirling mixing tube (30), which is located inside the left cylinder (1) and connected to the swirling tube (10), and the spiral tube (20) is located inside the swirling mixing tube (30); The spiral mixing tube (30) has at least one row of windows (31) evenly distributed in the circumferential direction on its tube wall, and the windows (31) are located downstream of the spiral tube (20). The window (31) has an outward protrusion and is open on one side; The window (31) is used to wedge the exhaust gas inward, which can not only supplement heat to reduce the crystal deposits on the inner wall of the spiral tube (20), but also guide the exhaust gas and the gas-liquid mixture flowing out of the spiral tube (20) to flow evenly in the circumferential direction, thereby enhancing the swirling effect of the airflow, promoting the decomposition of urea and the uniform mixing of gas and liquid.

5. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 4, characterized in that, The opening height of the window (31) is 10mm~15mm; And / or, the opening direction of the window (31) is set at an angle to the axial direction of the swirling mixing tube (30), and the angle γ between the two is 30°~45°.

6. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 4, characterized in that, It also includes a right cylinder (2), which is located downstream of the left cylinder (1) and is arranged separately from the left cylinder (1). The right cylinder (2) is connected to the exhaust gas outlet pipe. The left cylinder (1) has a first mounting hole on its right side wall facing the right cylinder (2), and the right cylinder (2) has a second mounting hole opposite to the first mounting hole on its left side wall facing the left cylinder (1). The left cylinder (1) and the right cylinder (2) are sealed together by a connecting pipe (40) passing through the first mounting hole and the second mounting hole. The right cylinder (2) is used to receive the gas-liquid mixture after it has been drawn together by the swirling mixing pipe (30) and the connecting pipe (40), and to provide a mixing buffer space for it.

7. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 6, characterized in that, The connecting pipe (40) includes a sleeve (41), a gasket (42) and a bushing (43) connected in sequence. The gasket (42) is pressed between the sleeve (41) and the bushing (43), and the three are fastened by a clamp (44). The sleeve (41) is connected to the swirling mixing tube (30); The bushing (43) is connected to the right cylinder (2); The connecting pipe (40) is used to rectify and dampen the airflow from the left cylinder (1) and to provide thermal expansion compensation between the left cylinder (1) and the right cylinder (2).

8. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 6, characterized in that, The volume of the right cylinder (2) is greater than the volume of the left cylinder (1); The volume of the right cylinder (2) is 1.5-3 times that of the left cylinder (1), which is used to provide sufficient airflow development space and ensure sufficient mixing residence time, thereby ensuring that ammonia and tail gas are mixed evenly.

9. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 6, characterized in that, Also includes: The transition pipe (50) is connected at one end to the connecting pipe (40) and at the other end is inserted into the right cylinder (2) through the second mounting hole; A flow guide plate (60) is provided at the air outlet end of the transition pipe (50) in the right cylinder (2); The swirl tube (10), the spiral tube (20), the swirling mixing tube (30), the connecting pipe (40), and the transition pipe (50) constitute a mixed gas delivery pipe. The mixed gas delivery pipe is used to promote the mixing of the tail gas entering the left cylinder (1) with urea and can guide the gas-liquid mixture into the right cylinder (2). The flow guide plate (60) serves as the output window of the mixed gas delivery pipe; The guide plate (60) is provided with a plurality of guide vanes (61) spaced apart along a straight line. The straight line is perpendicular to the axial direction of the mixed gas conveying pipe. The guide vanes (61) are arranged in an outward-facing form to guide the gas-liquid mixture flowing out of the mixed gas conveying pipe to form a radial swirling flow. This further works with the wide space of the right cylinder (2) to form a buffer, thereby extending the residence time of the gas-liquid mixture, improving the mixing uniformity of ammonia and tail gas, and reducing the risk of excessively high local ammonia concentration.

10. The high-efficiency anti-crystallization cyclone mixer for exhaust gas aftertreatment according to claim 9, characterized in that, The upper part of the flow guide plate (60) is provided with four gradually opening flow guide blades (61). The outward turning angle of the four flow guide blades (61) varies monotonically along their arrangement direction, which is used to compensate for the circumferential airflow non-uniformity generated by the spiral tube (20) and the swirling mixing tube (30). And / or, the outward turning angle δ of the guide vane (61) is 50°~90°; And / or, the upper side of the transition tube (50) is provided with a notch, the axial length of the notch is 1 / 2 of the transition tube (50), the top of the flow guide plate (60) is provided with an axial flow guide vane (62), the axial flow guide vane (62) is folded toward the transition tube (50) so that the axial flow guide vane (62) faces the notch, and the included angle ε between the axial flow guide vane (62) and the flow guide plate (60) is 30°~60°; And / or, the upper part of the flow guide plate (60) is provided with four flow guide blades (61), the width of the four flow guide blades (61) is the same, the height of the two flow guide blades (61) in the middle is the same and higher than the other two flow guide blades (61) on both sides, the height of the other two flow guide blades (61) on both sides is the same, and a pressure relief through hole (63) is provided in the height difference area between the two flow guide blades (61) that are high and low, the pressure relief through hole (63) is used to balance the pressure in front of and behind the flow guide plate (60); And / or, on the flow guide plate (60), below the flow guide blade (61), there is at least one row of small holes (64), the diameter of the small holes (64) is 2mm-10mm, and the total opening area of ​​the small holes (64) accounts for 10%-25% of the area of ​​the flow guide plate (60).

Images