Rotational flow grit chamber

Abstract

The invention relates to the technical field of sewage treatment, and provides a rotational flow grit chamber. The rotational flow grit chamber comprises a sedimentation tank, a guide cylinder and an inclined water inlet structure. The guide cylinder is suspended in the sedimentation tank, the inclined water inlet structure is tangentially connected with the guide cylinder, and the inclined water inlet structure drains water to the guide cylinder in the direction from high to low. Through the structural arrangement, high-speed water flow tangentially enters the guide cylinder through the oblique water inlet structure, kinetic energy of the high-speed water flow is converted into potential energy through the flow slowing slope, direct impact on internal components can be reduced, meanwhile, the oblique water flow and the rotational flow direction of the guide cylinder cooperate, a stable spiral descending flow state is formed, the short flow phenomenon is avoided, and the service life of the guide cylinder is prolonged. Therefore, local turbulence energy at the water inlet position is effectively reduced, and head loss is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, in particular to a cyclone grit chamber. Background Art

[0002] In the field of municipal and industrial wastewater treatment, cyclone grit chambers are key pretreatment equipment that utilizes centrifugal force to achieve solid-liquid separation. Their flow field stability and hydraulic efficiency directly affect the sand removal effect and system operating energy consumption. Traditional cyclone grit chambers generally adopt an upper water inlet design. In this structural design, on the one hand, the high-level water inlet shortens the effective flow path of the water in the tank, making it difficult to form a complete spiral progressive flow pattern, which is prone to short-circuiting. As a result, some sand particles are discharged with the water flow before completing centrifugal sedimentation. On the other hand, there is a large potential energy difference between the water inlet and the center area of ​​the tank body. The high-speed inflow directly impacts internal components such as the guide plate and sand collecting hopper, inducing a sudden increase in local turbulence intensity and significantly increasing the system head loss. Summary of the Invention

[0003] In view of the above technical problems, the present invention provides a cyclone grit chamber.

[0004] The present invention provides a cyclone sand settling tank, comprising: a sedimentation tank; a guide tube, which is suspended in the sedimentation tank; and an oblique water inlet structure, which is tangentially connected to the guide tube and diverts water to the guide tube along a direction from high to low.

[0005] According to a cyclone grit chamber provided by the present invention, the oblique water inlet structure includes: a direct current section, which is horizontally arranged; an oblique flow section, one end of which is connected to the direct current section, and one end of which extends obliquely downward and is connected to the guide tube.

[0006] According to a cyclone sand settling tank provided by the present invention, the oblique water inlet structure also includes: a variable cross-section tangent section, one end of the variable cross-section tangent section is connected to the oblique flow section, and the other end of the variable cross-section tangent section is tangentially connected to the guide tube, and along the sewage drainage direction, the flow cross-section of the variable cross-section tangent section gradually decreases.

[0007] According to a cyclone sand settling tank provided by the present invention, the guide tube includes: a basic guide section, which is suspended above the sedimentation tank; an extended guide section, which has the same diameter as the basic guide section and is coaxially connected to the lower end of the basic guide section.

[0008] According to a cyclone grit chamber provided by the present invention, the cyclone grit chamber further includes: a central tube, which is sleeved on the inner side of the guide tube at intervals; a reflecting cone, which is located below the guide tube and connected to the lower end of the central tube; and a water outlet gallery, which is circumferentially arranged to the top of the central tube.

[0009] According to the cyclone grit chamber provided by the present invention, the reflecting cone is coaxially arranged with the central tube, and the small end of the reflecting cone is communicated with the lower end of the central tube.

[0010] According to a cyclone sand settling tank provided by the present invention, the central tube includes: a cylinder body, which is sleeved on the inner side of the guide cylinder at intervals, and the lower end of the cylinder body is connected to the small end of the reflecting cone; a connecting hole, which is opened to the side wall of the cylinder body; and a guide vane, which is arranged at the edge of the connecting hole and is inclined toward the inner side of the cylinder body.

[0011] According to a cyclone sand settling tank provided by the present invention, there are multiple communicating holes, and the multiple communicating holes are evenly arrayed on the side wall of the cylinder with the center of the cylinder as the array center; the edge of each communicating hole is provided with the guide wing.

[0012] According to the cyclone grit chamber provided by the present invention, the communicating hole is a rectangular hole, and the guide vanes are provided on all four edges of the rectangular hole.

[0013] According to the cyclone grit chamber provided by the present invention, the cone angle of the reflecting cone is 60°; and the angle between the guide vane and the side wall of the cylinder is 15°.

[0014] The vortex grit chamber provided by the present invention includes a sedimentation tank, a guide tube, and an oblique water inlet structure. The guide tube is suspended in the sedimentation tank, and the oblique water inlet structure is tangentially connected to the guide tube, and the oblique water inlet structure guides water to the guide tube in a direction from high to low. Through this structural setting, high-speed water flows tangentially into the guide tube through the oblique water inlet structure, and the kinetic energy of the high-speed water flow is converted into potential energy through the slow-flow slope, which can reduce the direct impact on internal components. At the same time, the oblique water flow cooperates with the vortex direction of the guide tube to form a stable spiral downward flow state, avoiding short-circuiting, thereby effectively reducing the local turbulent kinetic energy at the water inlet position and reducing head loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the cyclone grit chamber provided by the present invention.

[0017] Figure 2 The figure is a schematic diagram of the top view of the cyclone grit chamber provided by the present invention.

[0018] Figure numerals: 100, guide tube; 110, basic guide section; 120, extended guide section; 200, oblique water inlet structure; 210, direct flow section; 220, oblique flow section; 230, variable cross-section tangent section; 300, central tube; 400, reflecting cone; 500, water outlet corridor; 600, connecting hole. DETAILED DESCRIPTION

[0019] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0020] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0021] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0022] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0023] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, in the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples to make the purpose, technical solutions and advantages of the embodiment of the present invention clearer. The technical solutions in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The following combination Figure 1 and Figure 2 A cyclone grit chamber provided by an embodiment of the present invention is described. It should be understood that the following description is merely an illustrative embodiment of the present invention and does not constitute any particular limitation to the present invention.

[0025] The embodiment of the present invention provides a cyclone sand settling tank, such as Figure 1 and Figure 2 As shown, the cyclone sand settling tank includes: a sedimentation tank; a guide tube 100, which is suspended in the sedimentation tank; an oblique water inlet structure 200, which is tangentially connected to the guide tube 100 and diverts water to the guide tube 100 along a direction from high to low.

[0026] The cyclone grit chamber provided by the present invention comprises a sedimentation tank, a guide tube 100, and an oblique water inlet structure 200. The guide tube 100 is suspended in the sedimentation tank, and the oblique water inlet structure 200 is tangentially connected to the guide tube 100 and diverts water from high to low to the guide tube 100.

[0027] Through this structural setting, firstly, when the high-speed incoming flow descends along the slow-flow slope of the oblique water inlet structure 200, part of the kinetic energy of the water flow is dissipated in a step-by-step manner through the friction resistance of the inclined surface and the accumulation of gravitational potential energy, effectively reducing the instantaneous impact momentum of the inflow fluid on the inner wall of the guide tube 100, thereby suppressing the component vibration and turbulent kinetic energy accumulation caused by high-speed impact; secondly, the oblique water inlet direction and the swirl direction of the guide tube 100 form a fluid mechanics match, significantly enhancing the centrifugal flow field dominated by the circumferential velocity component, forming a stable three-dimensional flow spiral descending along the tube wall. state, avoiding the vertical circulation interference caused by traditional upper water inlet, and reducing the incidence of short-circuit; moreover, the potential energy gradient is used to guide the water flow to smoothly transition to the vortex state, the turbulent kinetic energy peak in the water inlet area decreases, the local vortex scale is reduced, and the energy dissipation caused by turbulent pulsation is reduced, thereby reducing the overall head loss of the system; in addition, the stable spiral flow state extends the effective sedimentation path of sand particles in the centrifugal field, thereby improving the retention rate of sand particles with a particle size greater than or equal to 200μm, while reducing the hydraulic shear strength and inhibiting the secondary suspension of settled sand particles.

[0028] In one embodiment of the present invention, the oblique water inlet structure 200 includes: a direct current section 210, which is horizontally arranged; an oblique flow section 220, one end of which is connected to the direct current section 210, and one end of which extends obliquely downward and is connected to the guide tube 100.

[0029] Furthermore, in one embodiment of the present invention, the oblique water inlet structure 200 also includes: a variable-section tangent section 230, one end of the variable-section tangent section 230 is connected to the oblique flow section 220, and the other end of the variable-section tangent section 230 is tangentially connected to the guide tube 100, and along the sewage drainage direction, the flow cross-section of the variable-section tangent section 230 gradually decreases.

[0030] like Figure 1 As shown, the direct flow section 210 , the oblique flow section 220 and the variable cross-section tangent section 230 are connected in sequence, and the direct flow section 210 is arranged horizontally, the oblique flow section 220 is arranged obliquely from high to low, and the variable cross-section tangent section 230 is tangentially connected to the guide tube 100 .

[0031] Among them, the direct current section 210 serves as the initial rectifying section of the water inlet channel. It eliminates the lateral disturbance caused by the deflection of the incoming fluid direction through the horizontal straight flow channel, maintains the conservation of momentum of the water flow in the horizontal direction, forms a uniform flow velocity distribution, avoids the generation of local turbulence caused by the bending of the flow channel, ensures that the initial high-speed water flow has a stable flow state when entering the oblique water inlet structure 200, provides a flow field basis for the subsequent kinetic energy-potential energy conversion, and reduces the interference of the front turbulence on the overall stability of the system.

[0032] The oblique flow section 220 is tilted downward, for example, at an angle of 23° to the horizontal. As water flows down the inclined surface, it accumulates gravitational potential energy, partially converting its kinetic energy into potential energy. The frictional resistance of the inclined surface creates a laminar boundary layer effect, decreasing the flow velocity along the way and reducing the impact momentum of the inflow. This also reduces the peak shear stress on the wall of the guide tube 100, significantly suppressing component wear.

[0033] The variable-section tangential section 230 has a gradually decreasing flow cross-section and connects tangentially to the guide tube 100. This linear reduction in flow cross-sectional area from the exit of the oblique flow section 220 to the entrance of the guide tube 100 achieves fluid acceleration and tangential momentum enhancement. The tangential connection angle aligns with the swirl direction of the guide tube 100, minimizing momentum exchange losses between the incoming fluid and the swirl. Tangentially entering the guide tube 100 reduces turbulent kinetic energy in the impact zone, increasing the circumferential velocity component of the swirl field and forming a more stable forced vortex core, improving the centrifugal settling efficiency of sand particles.

[0034] In other words, the three-stage structure creates a progressive flow pattern control mechanism of "rectification-deceleration-directional acceleration." The straight section 210 eliminates initial disturbances, the oblique flow section 220 dissipates kinetic energy, and the variable cross-section section enhances tangential momentum. Ultimately, the high-speed water flows into the guide tube 100 in a low-impact, high-tangential flow pattern, reducing inflow impact energy, improving vortex field stability, and enhancing the flow pattern's ability to resist interference.

[0035] In one embodiment of the present invention, the guide tube 100 includes: a basic guide section 110, which is suspended above the sedimentation tank; an extended guide section 120, which has the same diameter as the basic guide section 110 and is coaxially connected to the lower end of the basic guide section 110.

[0036] For example, as shown in the figure, the basic guide section 110 and the extended guide section 120 are cylindrical structures of equal diameter and are coaxially connected. By axially extending the total height of the guide tube 100, a continuous and uniform columnar swirl channel is constructed, which prolongs the effective action time of sand particles in the centrifugal field and, in turn, improves the removal rate of sand particles with a diameter of 200μm or greater.

[0037] In one embodiment of the present invention, Figure 1 and Figure 2As shown, the cyclone grit chamber also includes: a central tube 300, which is spaced apart and sleeved on the inner side of the guide tube 100; a reflecting cone 400, which is located below the guide tube 100 and connected to the lower end of the central tube 300; and a water outlet gallery 500, which is circumferentially arranged to the top of the central tube 300.

[0038] Furthermore, in one embodiment of the present invention, the reflecting cone 400 is coaxially arranged with the central tube 300 , and the small end of the reflecting cone 400 is connected to the lower end of the central tube 300 .

[0039] As can be seen from the embodiment described above, an annular flow channel is formed between the guide tube 100 (outer tube) and the central tube 300 (inner tube), enabling the independent development of a primary vortex (downward on the outside) and a secondary vortex (upward on the inside). The primary vortex spirals downward along the outside of the guide tube 100, while the secondary vortex spirals upward on the inside. A reflecting cone 400 at the bottom of the guide tube 100 forcibly deflects the downward flow of the primary vortex, forming a secondary vortex that rises along the inner wall of the central tube 300. The upward secondary vortex spirals upward around the central tube 300. The velocity difference between the upward vortex on the inside and the downward vortex on the outside creates shear forces at the interface. This shear force separates smaller particles from the water flow and deposits them at the bottom of the tank, improving sand removal efficiency. Clean water then flows out of the upper portion of the sedimentation tank through the outlet gallery 500. The entire sand settling process relies solely on the forces generated by the water flow, eliminating the need for aeration or agitation devices, resulting in a simple structure.

[0040] In one embodiment of the present invention, the cone angle of the reflective frustum 400 may be set to 60°.

[0041] In one embodiment of the present invention, Figure 1 As shown, the central tube 300 includes: a cylinder body, which is sleeved on the inner side of the guide tube 100, and the lower end of the cylinder body is connected to the small end of the reflecting cone 400; a connecting hole 600, which is opened to the side wall of the cylinder body; and a guide vane, which is arranged at the edge of the connecting hole 600, and the guide vane is inclined toward the inner side of the cylinder body.

[0042] Furthermore, in one embodiment of the present invention, there are multiple communicating holes 600, and the multiple communicating holes 600 are evenly arrayed on the side wall of the cylinder with the center of the cylinder as the array center; the edge of each communicating hole 600 is provided with a guide fin.

[0043] More specifically, in one embodiment of the present invention, the communicating hole 600 is a rectangular hole, and guide vanes are provided on all four edges of the rectangular hole.

[0044] The included angle between the guide vane and the side wall of the cylinder is 15°.

[0045] This structural arrangement breaks up the central stagnation zone and evenly distributes the water to the pool wall settling area. The guide vanes optimize the flow field distribution, reduce vortex generation, and reduce head loss. The addition of connecting holes 600 effectively optimizes the hydraulic flow pattern, enhances sand settling performance, and improves the efficiency of sand migration to the pool wall.

[0046] During the specific working process, in the water inlet stage: sewage enters the lower and middle area of ​​the sedimentation tank through the oblique water inlet structure 200, and the water inlet adopts a variable cross-section tangent section 230, that is, a tapered cross-section design, and the water inlet direction is tangent to the guide tube 100, which can ensure that the water flow avoids the positive projection area of ​​the guide tube 100 and avoids direct impact on the inner guide tube 100 and other components, and can also form a stable vortex along the inner wall of the tank after the water flows into the sedimentation tank.

[0047] Cyclone separation stage: After the sewage enters the sedimentation tank, it slowly descends along the guide tube 100. The sand particles in the sewage form a forced vortex in the annular area between the outer wall of the guide tube 100 and the inner wall of the tank body. Under the action of gravity and centrifugal force, the sand particles gradually settle in layers. Coarse sand (particle size ≥ 200μm) moves toward the tank wall and settles in the initial stage of cyclone. Fine sand (particle size 100-200μm) has a slower sedimentation rate and needs to be further separated in the subsequent enhanced stage.

[0048] Enhanced separation stage: When the descending water reaches the reflecting cone 400 at the bottom of the guide tube 100, some of its kinetic energy is converted into pressure energy, causing the water flow to shift from downward to upward, forming a secondary upward vortex. A velocity gradient forms at the interface between the primary downward vortex (outer side) and the secondary upward vortex (inner side), generating shear force that separates fine sand particles from the water flow and accelerates their sedimentation to the pool bottom.

[0049] Sand collection stage: The central tube 300 is designed with multiple evenly distributed rectangular connecting holes 600, and diverter vanes are placed around the edges of these connecting holes 600. These holes break down the boundaries of the central retention zone, directing water toward the pool walls. The diverter vanes adjust the flow field, reducing vortexes and preventing sand accumulation in the central area. The design of these connecting holes 600 and diverter vanes optimizes the sand migration path, allowing settled sand to accumulate by gravity in the sand hopper at the bottom of the pool. A submersible sewage pump is then used to remove the sand, which is periodically activated according to a preset sand removal cycle and transported to a sand-water separator for dehydration. During actual operation, the sand removal cycle can be adjusted based on the actual sand content in the incoming water.

[0050] Drainage stage: The effluent after the mud and sand separation is discharged through the top annular outlet gallery 500. The gallery adopts a gradually expanding cross-section, and the effluent enters the next treatment unit.

[0051] In a specific embodiment of the present invention, the designed processing capacity is 2000m³ / h.

[0052] The traditional hydrocyclone grit chamber requires a 6m diameter chamber, but after optimization, the present invention only requires a 5m diameter chamber, and the floor area is reduced from 30m2 to 22m2.

[0053] During the water inlet stage, sewage enters the middle and lower area of ​​the pool body at an inclination of 23° through the oblique water inlet structure 200. The water inlet adopts a tapered cross-section design, with the inlet width gradually shrinking from 800mm to 500mm, and the flow rate gradually decreasing from 1.2m / s to 0.8m / s. The water inlet direction is designed to be tangential to the pool wall, which can not only ensure that the water flow avoids the positive projection area of ​​the guide tube 100 and avoids direct impact on the guide tube 100 and other components, but also enables the water flow to form a stable vortex along the inner wall of the pool after entering the pool body. CFD simulation shows that this design reduces the turbulent kinetic energy at the water inlet by 45% and the head loss by 30%.

[0054] During the cyclone separation stage, after sewage enters the tank, it forms a cyclone along the inner wall of the tank while slowly descending along the outer wall of the guide tube 100. In this embodiment, by increasing the height of the guide tube 100 by 25%, specifically from 4m to 5m, the cyclone path of the water flow is effectively extended, and the sedimentation time of the sand particles is prolonged by 15%-20%. This forces the sand particles in the sewage to form a forced vortex in the annular area between the outer wall of the tube and the inner wall of the tank, effectively improving the removal rate of fine sand. Under the action of gravity and centrifugal force, the sand particles gradually settle in layers. Coarse sand moves toward the tank wall and settles in the initial stage of the cyclone. Fine sand, due to its slower sedimentation rate, requires further separation in the subsequent intensive stage.

[0055] During the enhanced separation phase, when the descending water reaches the 60° conical reflector cone 400 at the bottom of the guide tube 100, some of its kinetic energy is converted into pressure energy, causing the water flow to shift from downward to upward, forming a secondary upward vortex. A velocity gradient forms at the interface between the primary downward vortex (outer) and the secondary upward vortex (inner), generating shear force that separates fine sand particles from the water flow and accelerates their sedimentation to the pool bottom. CFD simulations show that this design increases the removal rate of sand and gravel with a particle size of 100-200μm from 40% in traditional structures to 65%.

[0056] During the sand collection phase, eight evenly spaced rectangular connecting holes 600 are designed on the wall of the central tube 300. Each connecting hole 600 measures 1000 mm x 200 mm, and diverter vanes with a 15° angle are designed around the edges of the connecting holes 600. These connecting holes 600 break the boundaries of the central retention zone and guide water toward the pool walls. The diverter vanes adjust the flow field, reducing vortexes and preventing sand accumulation in the central area. The design of the connecting holes 600 and diverter vanes optimizes the sand migration path, allowing settled sand to accumulate by gravity in the sand hopper at the bottom of the pool. A submersible sewage pump is used to remove sand, with a preset hourly sand removal cycle to transport the sand to a sand-water separator for dehydration. During actual operation, the sand removal cycle can be adjusted based on the actual sand content of the incoming water.

[0057] In the drainage stage, the effluent after mud and sand separation is discharged through the top annular outlet gallery 500. The gallery adopts a gradually expanding cross-section. In this embodiment, the outlet width is expanded from 500 mm to 800 mm, and the outlet flow rate is 0.5 m / s.

[0058] Based on this, through the optimization of oblique water inlet kinetic energy, the efficient swirl guidance of the guide tube 100 and the uniform design of the central flow field, the sand settling efficiency is significantly improved and the operating cost is reduced. It is especially suitable for large flow conditions and the renovation of old tanks, providing reliable technical support for improving the quality and efficiency of sewage treatment plants.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A cyclone grit chamber, characterized in that: include: sedimentation tanks; A draft tube (100), the draft tube (100) being suspended in the sedimentation tank; An oblique water inlet structure (200), the oblique water inlet structure (200) is tangentially connected to the guide tube (100), and the oblique water inlet structure (200) guides water to the guide tube (100) in a direction from high to low.

2. The cyclone grit chamber according to claim 1, characterized in that: The oblique water inlet structure (200) comprises: A DC section (210), wherein the DC section (210) is arranged horizontally; An oblique flow section (220), one end of which is connected to the straight flow section (210), and one end of which extends obliquely downward and is in communication with the guide cylinder (100).

3. The cyclone grit chamber according to claim 2, characterized in that: The oblique water inlet structure (200) further includes: A variable cross-section tangent section (230), one end of the variable cross-section tangent section (230) is connected to the oblique flow section (220), the other end of the variable cross-section tangent section (230) is tangentially connected to the guide tube (100), and along the sewage drainage direction, the flow cross-section of the variable cross-section tangent section (230) gradually decreases.

4. The cyclone grit chamber according to claim 1, characterized in that: The guide tube (100) comprises: A basic diversion section (110), the basic diversion section (110) being suspended above the sedimentation tank; An extended guide section (120), wherein the extended guide section (120) has the same diameter as the basic guide section (110) and is coaxially connected to the lower end of the basic guide section (110).

5. The cyclone grit chamber according to any one of claims 1 to 4, characterized in that: The cyclone grit chamber also includes: A central tube (300), the central tube (300) being sleeved on the inner side of the guide tube (100) at intervals; a reflecting truncated cone (400), the reflecting truncated cone (400) being located below the guide tube (100) and connected to the lower end of the central tube (300); A water outlet gallery (500) is circumferentially arranged around the top of the central tube (300).

6. The cyclone grit chamber according to claim 5, characterized in that: The reflecting truncated cone (400) is coaxially arranged with the central tube (300), and the small end of the reflecting truncated cone (400) is in communication with the lower end of the central tube (300).

7. The cyclone grit chamber according to claim 5, characterized in that: The central tube (300) comprises: a cylinder, the cylinder being sleeved at intervals on the inner side of the guide cylinder (100), the lower end of the cylinder being connected to the small end of the reflecting cone (400); a communicating hole (600), the communicating hole (600) being opened to the side wall of the cylinder; A guide fin is provided at the edge of the communicating hole (600), and the guide fin is inclined toward the inner side of the cylinder.

8. The cyclone grit chamber according to claim 7, characterized in that: The number of the communicating holes (600) is multiple, and the multiple communicating holes (600) are evenly arrayed on the side wall of the cylinder with the center of the cylinder as the array center; The edge of each communicating hole (600) is provided with the guide fin.

9. The cyclone grit chamber according to claim 8, characterized in that: The communicating hole (600) is a rectangular hole, and the guide vanes are provided on all four edges of the rectangular hole.

10. The cyclone grit chamber according to claim 7, characterized in that: The cone angle of the reflecting cone (400) is 60°; The included angle between the guide fin and the side wall of the cylinder is 15°.

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