A multi-stage filtering and oxygenating integrated device for recirculating aquaculture

Abstract

The application relates to the technical field of water treatment, and specifically discloses a multi-stage filtering and oxygenating integrated device for circulating water aquaculture, which comprises a tank body and a driving motor arranged at the bottom of the tank body, and a multi-stage filtering cavity and an oxygenating cavity are arranged in the tank body from top to bottom; a primary filter cylinder and a secondary filter cylinder are coaxially arranged in the multi-stage filtering cavity; water to be treated passes through the primary filter cylinder and the secondary filter cylinder in sequence and then enters the oxygenating cavity for treatment; a water outlet pipe is further arranged in the oxygenating cavity and is connected with the outside, and is used for discharging the treated water; the device further comprises a coaxial double-drive assembly arranged through the middle part of the tank body, which comprises an oxygenating shaft, a sewage suction shaft, a cleaning assembly, a negative pressure sewage suction element and a rotary coupling mechanism; the device realizes multi-stage deep purification and strong oxygen compensation of the circulating water under the working condition of cleaning, and effectively improves the use effect of the traditional equipment that the filter screen is easy to be blocked and the water is short of oxygen during backwashing.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to a multi-stage filtration and oxygenation integrated device for recirculating aquaculture. Background Technology

[0002] In factory-scale recirculating aquaculture systems, efficient physical filtration and reoxygenation are crucial for maintaining stable water quality and ensuring stocking density. However, due to limitations in conventional technical architectures, existing treatment processes typically separate these two functions, generally adopting a decentralized layout, i.e., setting up independent microfiltration units for solid-liquid separation and aeration equipment for aeration. While this traditional architecture of functional separation is mature, it inevitably suffers from inherent drawbacks such as high pump station construction costs, large equipment footprint, and complex cascading pipelines.

[0003] To address these issues, vertical tank-type integrated filtration and aeration devices have emerged, but their hardware architecture remains immature. In terms of filtration, most adopt a single-stage filter structure, making it difficult to balance filtration accuracy and dirt holding capacity, thus failing to meet the deep purification needs of high-density aquaculture. In terms of drive, to solve the problem of filter clogging, a simple stacking design is often used, namely, additionally configuring independently driven sludge scraping and suction components or high-pressure backwashing water pumps. This multi-power-source stacking structure not only leads to a bulky system size but also significantly increases energy consumption and subsequent maintenance costs.

[0004] Meanwhile, existing devices mostly use independent manual or timed controls for cleaning and aeration, which cannot automatically switch operating conditions according to the degree of filter clogging, making it difficult for the two to work together. Furthermore, their filter cleaning components only have a simple scraping function and lack a turbulence design, which not only results in incomplete cleaning of certain parts of the filter cartridge but also affects the mixing efficiency of water and oxygen. This leads to a disconnect in the device's functions, making it impossible to simultaneously enhance aeration under the high-load conditions of cleaning and sewage discharge. Consequently, it is difficult to meet the combined needs of high-density aquaculture for powerful sewage discharge, deep filtration, and efficient aeration at the same time. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides a multi-stage filtration and oxygenation integrated device for recirculating aquaculture, so as to at least solve one of the problems mentioned in the background art.

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

[0007] A multi-stage filtration and oxygenation integrated device for recirculating aquaculture includes a tank and a drive motor located at the bottom of the tank. The tank has multiple filtration chambers and oxygenation chambers arranged from top to bottom inside.

[0008] The multi-stage filtration chamber is coaxially fitted with a primary filter cartridge and a secondary filter cartridge. The water to be treated passes through the primary filter cartridge and the secondary filter cartridge in sequence and enters the oxygenation chamber for treatment. The oxygenation chamber is also equipped with an outlet pipe that communicates with the outside for discharging the treated water.

[0009] The device further includes a coaxial dual-drive assembly that runs through the middle of the tank, the coaxial dual-drive assembly comprising:

[0010] An oxygenation shaft is connected to the drive motor at one end, and the other end passes through the oxygenation chamber and the multi-stage filtration chamber in sequence.

[0011] The suction shaft is rotatably sleeved on the outside of the shaft body of the oxygenation shaft located inside the multi-stage filtration chamber, and its top end extends to the outside of the tank. An annular discharge gap for conveying waste is formed between its inner wall and the outer wall of the oxygenation shaft.

[0012] The cleaning component is connected to the outside of the suction shaft and communicates with the annular discharge gap. It is used to clean the dirt attached to the surface of the primary filter cartridge and the secondary filter cartridge and transport it into the annular discharge gap.

[0013] A negative pressure suction device is placed on top of the tank and connected to the top of the suction shaft. The internal flow channel of the negative pressure suction device is connected to the annular discharge gap, which is used to generate negative pressure and discharge the dirt when the suction shaft rotates.

[0014] A rotational coupling mechanism is provided at the bottom end of the suction shaft, and the suction shaft is connected to the oxygenation shaft through the rotational coupling mechanism. It is used to control the separation or engagement of the two shafts for synchronous rotation according to the speed of the drive motor.

[0015] Furthermore, the multi-stage filtration chamber and the oxygenation chamber are separated by a partition plate. The first-stage filter cartridge is an inverted conical structure, and its bottom is connected to the partition plate to form a first-stage filtration chamber. An inlet pipe is provided in the first-stage filtration chamber to connect to the outside of the tank. The water to be treated enters the first-stage filtration chamber through the inlet pipe. The second-stage filter cartridge is a straight cylindrical structure, and its top and bottom ends are respectively sealed and connected to the upper part of the inner wall of the multi-stage filtration chamber and the partition plate, forming a second-stage filtration chamber with the first-stage filter cartridge located inside it.

[0016] Furthermore, a clear water gap is formed between the outer wall of the secondary filter cartridge and the inner wall of the tank, and several through holes connected to the oxygenation chamber are opened at the edge of the partition plate at the clear water gap.

[0017] Furthermore, the cleaning assembly includes a first cleaning arm and a second cleaning arm for cleaning the inner walls of the primary filter cartridge and the secondary filter cartridge, respectively. The first cleaning arm and the second cleaning arm are each provided with a guide pipe that communicates with the annular sewage discharge gap.

[0018] One end of the first cleaning arm is connected to the suction shaft, and the other end extends obliquely along the conical generatrix of the primary filter cartridge and fits against the inner wall of the primary filter cartridge.

[0019] One end of the second cleaning arm is connected to the part of the suction shaft that protrudes from the top of the primary filter cartridge, while the other end is bent downward and attached to the inner wall of the secondary filter cartridge.

[0020] Both the first and second cleaning arms have suction slits that are connected to their internal guide pipes on their working surfaces, which are respectively attached to the first-stage and second-stage filter cartridges.

[0021] Furthermore, the working surfaces of the first and second cleaning arms are provided with flexible scrapers located on both sides of the suction slit, and the side of the second cleaning arm facing away from the inner wall of the secondary filter cartridge is provided with protruding turbulence ribs.

[0022] Furthermore, the negative pressure suction component includes a centrifugal impeller and a sludge collection volute covering the outside of the centrifugal impeller;

[0023] The centrifugal impeller includes an upper cover plate, a lower cover plate, and several guide vanes. The lower cover plate is sleeved at the top of the suction shaft. The upper cover plate has a clearance hole in the middle, and the oxygenation shaft passes through the clearance hole and is rotatably connected to the sludge collection volute through a bearing. Several guide vanes are sandwiched between the upper cover plate and the lower cover plate and are arranged in a ring array around the center of the lower cover plate. The centrifugal flow channel inlet formed between adjacent guide vanes is connected to the annular sludge discharge gap in the suction shaft.

[0024] The inner wall of the sludge collecting volute and the centrifugal impeller disk form a diffuser water collecting cavity. A drain pipe extending tangentially and communicating with the diffuser water collecting cavity is also connected to the side wall of the sludge collecting volute.

[0025] Furthermore, the outer wall of the oxygenation shaft located inside the suction shaft is provided with axially extending spiral blades, which divide the annular sewage discharge gap into independent spiral upward flow channels.

[0026] Furthermore, two rotating sealing assemblies are provided axially spaced inside the bottom end of the suction shaft. The two rotating sealing assemblies seal and fill the space between the suction shaft and the oxygenation shaft and enclose a sealed bearing cavity.

[0027] The rotational coupling mechanism is installed inside the sealed bearing cavity, and includes an active disc body fixedly connected to the oxygenation shaft and a driven friction drum coaxially rotatably sleeved outside the active disc body and fixedly connected to the inner wall of the suction shaft.

[0028] Several centrifugal throwing blocks are hinged to the active disc body by pins, and a return spring connects the centrifugal throwing blocks to the active disc body.

[0029] When the drive motor runs at the first speed, the centrifugal sling block remains in a retracted state under the action of the reset spring and separates from the driven friction drum. When the drive motor runs at the second speed, the centrifugal sling block opens outward and rubs against the inner wall of the driven friction drum to drive the suction shaft to rotate synchronously. The second speed of the drive motor is greater than the first speed.

[0030] Furthermore, the oxygenation chamber is also equipped with an oxygenation component, which includes an air diffuser and an aeration disc. The air diffuser is sleeved on the oxygenation shaft and located outside the shaft of the oxygenation chamber. Multiple shearing fins are arrayed on the circumferential sidewall of the air diffuser. The aeration disc is installed at the bottom of the oxygenation chamber and below the air diffuser, and is connected to an external air source through an air inlet pipe that passes through the tank wall.

[0031] Furthermore, the device also includes a differential pressure detection unit and a frequency conversion control unit;

[0032] The differential pressure detection unit includes a first pressure sensor located inside the first-stage filter cartridge and a second pressure sensor located outside the second-stage filter cartridge. The first pressure sensor and the second pressure sensor are used to detect the water pressure values ​​before and after filtration, respectively.

[0033] The frequency conversion control unit is electrically connected to the first pressure sensor, the second pressure sensor, and the drive motor. The frequency conversion control unit is equipped with a calculation and comparison module. The calculation and comparison module is used to receive the pressure values ​​of the two water bodies and calculate the difference between them and compare it with a preset threshold. If the comparison result shows that the difference is greater than the preset threshold, the frequency conversion control unit controls the drive motor to work at a second speed. The high speed drives the suction shaft to clean and enhance the shear oxygen dissolution efficiency of the oxygenation component. If the comparison result shows that the difference is less than the preset threshold, the frequency conversion control unit controls the drive motor to maintain the first speed.

[0034] Compared with the prior art, the technical effects and advantages of the present invention include at least the following:

[0035] 1. This invention utilizes an oxygenation shaft running through the middle of the tank, a suction shaft rotating around the oxygenation shaft, and a centrifugal rotation coupling mechanism located inside a sealed bearing cavity. By adjusting the threshold of the drive motor speed, it achieves the mechanical logic of low-speed independent oxygenation and high-speed linkage cleaning and sewage discharge. This solves the problem that existing single power source devices cannot independently decouple and control the two different load conditions of continuous oxygenation and intermittent sewage discharge, resulting in excessive ineffective energy consumption during non-cleaning periods. It also achieves the effect of flexibly switching between pure oxygenation energy-saving mode and oxygenation + sewage discharge powerful mode using only a single motor.

[0036] 2. This invention utilizes the rigid connection between the oxygenation shaft and the drive motor, combined with the speed triggering characteristics of the centrifugal rotation coupling mechanism, to force the oxygenation components and shear fins at the bottom to enter a high-speed turbulent state simultaneously when the device increases its speed to drive the suction shaft for cleaning. This solves the technical problem of instantaneous oxygen deficiency in water caused by the surge in oxygen consumption due to the disturbance of dirt in the traditional backwashing process. It also realizes the effect of directly converting the high kinetic energy required for mechanical sewage discharge into high shear dissolved oxygen required for biochemical treatment for immediate and safe compensation.

[0037] 3. This invention utilizes an inverted conical primary filter cartridge and a straight cylindrical secondary filter cartridge to construct a tiered filtration system. It is combined with a first and second cleaning arm that are attached to the inner wall of the filter cartridge and have suction slits. The inverted conical surface is used to guide the gravity to achieve initial separation of large particles, and the high flow velocity negative pressure zone near the wall at the suction slits directly captures the stripped dirt. This effectively solves the problem that conventional mechanical scraping methods can easily cause dirt to be dispersed and resuspended in the water, resulting in secondary water pollution. Thus, it achieves precise cleaning and prevention of backflow and diffusion through simultaneous scraping and suction.

[0038] 4. This invention utilizes spiral blades located on the outer wall of the shaft inside the suction shaft to divide the annular discharge gap into a spiral ascending flow channel. The circumferential constraint formed by the spiral blades on the fluid and the axial thrust generated by the rotation assist the fluid transport. This solves the problem that when transporting high-concentration, high-density sludge over long vertical distances, the sludge is prone to slippage and fall back due to gravity, causing blockage of the discharge channel. It also realizes a composite transport of fluid carrying and mechanical rotary propulsion to ensure the continuity and thoroughness of the discharge process. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the external structure of the tank body of the present invention;

[0040] Figure 2 This is a schematic diagram of the internal structure of the tank of the present invention;

[0041] Figure 3 This is a partial structural diagram of the first and second cleaning arms of the present invention;

[0042] Figure 4 This is a schematic diagram of the axial cross-sectional structure of the oxygenation shaft and the suction shaft of the present invention, intended to show the state of the first cleaning arm;

[0043] Figure 5 This is a schematic diagram of the internal structure of the oxygenation shaft and the suction shaft of the present invention, intended to illustrate the state of the annular sewage discharge gap;

[0044] Figure 6 This is a schematic diagram of the internal structure of the sludge collection volute of the present invention;

[0045] Figure 7This is a schematic diagram of the internal structure of the rotary coupling mechanism of the present invention, intended to show the separation state of the active disk and the driven friction drum;

[0046] Figure 8 This is a schematic diagram of the internal structure of the rotational coupling mechanism of the present invention, intended to illustrate the frictional engagement state of the active disc and the driven friction drum;

[0047] Figure 9 This is a three-dimensional structural diagram of the air diffuser of the present invention.

[0048] In the above figures, the reference numerals are as follows: 1. Tank body; 11. Multi-stage filtration chamber; 111. Primary filter cartridge; 112. Secondary filter cartridge; 12. Aeration chamber; 2. Drive motor; 31. Aeration shaft; 311. Spiral blades; 32. Suction shaft; 33. Annular discharge gap; 41. First cleaning arm; 42. Second cleaning arm; 421. Baffle ribs; 431. Suction slit; 432. Guide pipe; 433. Flexible scraper; 511. Upper cover plate; 512. Lower cover plate; 513. Guide blades; 521. Sludge collection volute; 522. Discharge pipe; 61. Active disc; 611. Centrifugal shovel; 62. Driven friction drum; 71. Air diffuser; 711. Shear fins; 72. Aeration disc; 81. First pressure sensor; 82. Second pressure sensor; 91. Inlet pipe; 92. Outlet pipe. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. The embodiments described below are some, but not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0050] In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, materials, or methods are not specifically described to avoid obscuring the invention. Unless otherwise specified, the materials, instruments, and reagents used in the following embodiments are commercially available. Unless otherwise specified, the techniques used in the embodiments are conventional methods well known to those skilled in the art.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0052] Example:

[0053] This embodiment provides a multi-stage filtration and oxygenation integrated device for recirculating aquaculture. Obviously, this device is designed for industrialized recirculating water treatment systems with high-density and intensive characteristics. Specifically, it is usually installed between the return water end of the aquaculture pond and the main circulation network in the aquaculture workshop. As an independent or parallel core unit for water quality control, it is used to perform deep physical solid-liquid separation and efficient dissolved oxygen replenishment on the aquaculture tailwater from the aquaculture pond, which is rich in suspended particles (such as uneaten feed and feces) and has low dissolved oxygen. The purified and reoxygenated water is then fed back into the aquaculture system to maintain the ecological balance and cleanliness of the aquatic environment.

[0054] Specifically, please refer to Figure 1 and Figure 2 As shown, the device includes a tank 1 and a drive motor 2 located at the bottom of the tank 1. The tank 1 has a multi-stage filtration chamber 11 and an oxygenation chamber 12 arranged from top to bottom.

[0055] The multi-stage filtration chamber 11 is coaxially fitted with a primary filter cartridge 111 and a secondary filter cartridge 112. The water to be treated passes through the primary filter cartridge 111 and the secondary filter cartridge 112 in sequence and enters the oxygenation chamber 12 for treatment. The oxygenation chamber 12 is also equipped with an outlet pipe 92 that communicates with the outside for discharging the treated water.

[0056] The device further includes a coaxial dual-drive assembly that runs through the middle of the tank body 1, the coaxial dual-drive assembly comprising:

[0057] The oxygenation shaft 31 is connected to the drive motor 2 at one end, and the other end passes through the oxygenation chamber 12 and the multi-stage filtration chamber 11 in sequence.

[0058] The suction shaft 32 is rotatably sleeved on the outside of the shaft body of the oxygenation shaft 31 located inside the multi-stage filtration chamber 11, and its top end extends to the outside of the tank body 1. An annular discharge gap 33 for conveying waste is formed between its inner wall and the outer wall of the oxygenation shaft 31.

[0059] The cleaning component is connected to the outside of the suction shaft 32 and communicates with the annular discharge gap 33. It is used to clean the dirt attached to the surface of the primary filter cartridge 111 and the secondary filter cartridge 112 and transport it into the annular discharge gap 33.

[0060] A negative pressure suction device is placed on top of the tank 1 and connected to the top end of the suction shaft 32. The internal flow channel of the negative pressure suction device communicates with the annular discharge gap 33, and is used to generate negative pressure and discharge waste when the suction shaft 32 rotates; and

[0061] A rotational coupling mechanism is provided at the bottom end of the suction shaft 32, and the suction shaft 32 is connected to the oxygenation shaft 31 through the rotational coupling mechanism. It is used to control the separation or engagement of the two shafts to rotate synchronously according to the speed of the drive motor 2.

[0062] Understandably, in current land-based factory farming, vertical tank equipment has gradually replaced traditional open earthen ponds due to its smaller footprint. However, researchers have found in practical applications of existing technologies that current vertical devices still generally retain the characteristics of decentralized processing in their structural design. Specifically, to solve the problems of filter cleaning and sewage discharge, existing solutions usually involve installing an independent backwash pump outside the tank or adding an auxiliary geared motor on top. While this design, which relies on adding external auxiliary equipment to maintain operation, achieves the function, it leads to complicated external pipeline connections for a single device. This not only increases the overall construction cost of the pump station but also significantly increases the number of maintenance points for the equipment. At the same time, limited by the diameter of the tank, conventional single-layer filters cannot balance interception accuracy and flow rate in high-density farming, which easily causes frequent clogging.

[0063] Therefore, in order to solve this problem, the applicant proposes the solution described in the above embodiment. By coaxially mounting a primary filter cartridge 111 and a secondary filter cartridge 112 within the multi-stage filtration chamber 11, configuring a coaxial dual-drive assembly including an oxygenation shaft 31, a suction shaft 32, and a rotational coupling mechanism, and utilizing the annular sewage discharge gap 33 formed between the two shafts as an internal conveying channel, the technical problems of redundant external auxiliary drive equipment, complex connection of external sewage pipes 522, and insufficient single-stage filtration purification throughput in existing land-based devices are solved.

[0064] For example, when facing complex operating conditions of circulating water treatment, this embodiment achieves efficient operation of the device through the following mechanism: First, by utilizing the coaxial spatial folding mechanism of multi-stage filter cartridges, without increasing the floor area of ​​tank 1, the effective unfolding area and dirt holding capacity of the filter screen are greatly improved through the tiered combination of primary filter cartridge 111 pre-treatment of large particles and secondary filter cartridge 112 deep purification, thus physically delaying the clogging cycle; Second, based on the power reuse mechanism of coaxial dual drive and rotational coupling, a single motor can cover complex operating conditions. During normal operation, the drive motor 2 only rotates the central aeration shaft 31 to reoxygenate the water. At this time, the coupling mechanism is disengaged, and the suction shaft 32 is stationary, effectively reducing mechanical energy consumption during non-cleaning periods. When cleaning and sewage discharge are required, the coupling mechanism is triggered by adjusting the motor speed, forcibly driving the peripheral suction shaft 32 to rotate synchronously. At this time, the suction component brushes the multi-stage filter cartridges, and the detached dirt directly enters the annular sewage discharge gap 33 between the aeration shaft 31 and the suction shaft 32. It is then discharged vertically along the axis by the centrifugal suction generated by the rotation. This process firstly utilizes the built-in sewage discharge channel, directly eliminating the need for the complex external cleaning water pipes and sewage pumps of traditional devices, allowing the device to be connected to the pipeline network in a minimally sized single-unit form. Secondly, the mechanical coupling logic replaces multi-motor control, which significantly simplifies the electrical control system and reduces the difficulty of later maintenance while ensuring the cleaning power under high load conditions.

[0065] A preferred embodiment based on the above embodiments is as follows: Figure 2 As shown, the multi-stage filtration chamber 11 and the oxygenation chamber 12 are separated by a partition plate. The first-stage filter cartridge 111 is an inverted conical structure, and its bottom is connected to the partition plate to form a first-stage filtration chamber. An inlet pipe 91 is provided in the first-stage filtration chamber to connect to the outside of the tank 1. The water to be treated enters the first-stage filtration chamber through the inlet pipe 91. The second-stage filter cartridge 112 is a straight cylindrical structure, and its top and bottom ends are respectively closed and connected to the upper part of the inner wall of the multi-stage filtration chamber 11 and the partition plate, forming a second-stage filtration chamber with the first-stage filter cartridge 111 located inside it.

[0066] Understandably, this solution addresses the technical problems in existing vertical devices, such as unstable filtration accuracy due to excessive single-stage interception load and the ease with which fine suspended solids can be squeezed through the filter screen by large particles, by setting the primary filter cartridge 111 as an inverted conical structure coaxially covered by the straight cylindrical secondary filter cartridge 112, and by constructing independent filtration chambers through partition plates. Specifically,

[0067] During the operation of the device, firstly, the inverted conical geometry of the primary filter cartridge 111 creates a primary solid-liquid separation zone based on gravity settling. When the water to be treated enters the primary filtration chamber, the guiding effect of the conical surface causes larger, heavier fecal residues to quickly slide and accumulate at the bottom collection port. This effectively removes high-load, large-particle contaminants during the primary filtration stage, preventing them from obstructing or clogging the precision filter media in subsequent processes. Secondly, the nested space between the primary cone and the secondary cylinder creates a coarse filtration system that preserves the fine filter media. The gradient purification system of the filter is as follows: after the water is pretreated by the primary filter cartridge 111, its turbidity has been greatly reduced. Then, it enters the secondary filtration chamber and passes through the secondary filter cartridge 112. This allows the secondary filter cartridge 112 to deeply intercept the micron-sized fine suspended particles remaining in the water. This graded treatment mechanism avoids the phenomenon that soft dirt will deform and permeate through the filter due to accumulation and compression on a single filter screen. It ensures that the water that finally enters the oxygenation chamber 12 has extremely high clarity and low suspended solids content, and achieves deep purification of the circulating water from macroscopic impurities to microscopic particles.

[0068] As a further addition to this embodiment, the pore size of the primary filter cartridge 111 can be configured to be larger than that of the secondary filter cartridge 112, thereby constructing a pore size gradient sequence from the inside out (or from front to back) to the densest along the water flow path. Through this differentiated pore size configuration, the primary filter cartridge 111 is specifically used to intercept large-sized flocculants and fibrous impurities, acting as a high-load coarse filtration layer to reduce most of the solids volume content in the water. Meanwhile, the secondary filter cartridge 112 focuses on intercepting tiny suspended particles that penetrate the primary barrier, acting as a high-precision fine filtration layer. This effectively prevents the problem that a single-stage filter might become rapidly clogged due to excessive load if the pore sizes of the two stages are the same. While ensuring the final effluent accuracy, it significantly balances the dirt-holding pressure of the two filter cartridges and extends the continuous working time of the entire filtration assembly within a single cleaning cycle.

[0069] In a further embodiment, a clear water gap is formed between the outer wall of the secondary filter cartridge 112 and the inner wall of the tank 1. Several through holes communicating with the oxygenation chamber 12 are provided at the edge of the partition plate located within this clear water gap. Figure 2 As shown in the image.

[0070] This embodiment constructs a dedicated purified water flow channel for transitioning from the filtration process to the oxygenation process by setting a clear water gap around the periphery of the secondary filter cartridge 112 and a connecting hole at the edge of the partition plate. This structure effectively utilizes the annular space at the edge of the tank 1 as a water collection buffer zone, collecting the purified water that passes through the entire circumference of the secondary filter cartridge 112 and smoothly guiding it into the oxygenation chamber 12 below through the connecting hole using gravitational potential energy. This not only ensures a smooth connection between the filtration unit and the oxygenation unit in terms of fluid dynamics and achieves strict physical isolation between the inner layer for interception of contaminants and the outer layer for flow guidance, thus eliminating the risk of unfiltered raw water mixing into the oxygenation zone, but also makes the water flow entering the oxygenation chamber 12 more evenly dispersed through a distributed water distribution method, providing a stable hydraulic foundation for subsequent gas-liquid mixing treatment in the oxygenation chamber 12.

[0071] It should be noted that with prolonged continuous operation of the device, the inner walls of the primary filter cartridge 111 and the secondary filter cartridge 112 will inevitably trap and adhere a large amount of residual feed, feces, and suspended flocs. If not cleaned in time, the gradually thickening filter cake layer will lead to a significant increase in transmembrane pressure differential, severely hindering the normal permeation of water. Therefore, this embodiment further proposes the cleaning components described in the following embodiments, which are designed to effectively clean the primary filter cartridge 111 and the secondary filter cartridge 112.

[0072] In this embodiment, as Figure 3 As shown, the cleaning assembly includes a first cleaning arm 41 and a second cleaning arm 42 for cleaning the inner walls of the primary filter cartridge 111 and the secondary filter cartridge 112, respectively. The first cleaning arm 41 and the second cleaning arm 42 are each provided with a guide pipe 432 that communicates with the annular sewage discharge gap 33.

[0073] One end of the first cleaning arm 41 is connected to the suction shaft 32, and the other end extends obliquely along the conical generatrix of the primary filter cartridge 111 and fits against the inner wall of the primary filter cartridge 111.

[0074] One end of the second cleaning arm 42 is connected to the part of the suction shaft 32 that protrudes from the top of the primary filter cartridge 111, while the other end is bent downward and attached to the inner wall of the secondary filter cartridge 112.

[0075] On the working surfaces of the first cleaning arm 41 and the second cleaning arm 42, which are respectively attached to the primary filter cartridge 111 and the secondary filter cartridge 112, there are suction slits 431 that are connected to the internal guide pipes 432.

[0076] Based on the solution described in the above embodiments, by setting a first cleaning arm 41 and a second cleaning arm 42 respectively attached to the inner walls of the primary filter cartridge 111 and the secondary filter cartridge 112, and cooperating with the internally connected suction guide pipe 432, the technical problem of existing devices easily accumulating dirt on the filter screen surface after long-term operation, leading to a decrease in filtration flux and system blockage, is solved. Specifically, multiple first cleaning arms 41 and second cleaning arms 42 can be respectively provided and arranged in an array outside the shaft of the suction shaft 32;

[0077] When the device is cleaning the primary filter cartridge 111 and the secondary filter cartridge 112, the suction shaft 32, driven by the bottom rotation coupling mechanism, starts to rotate along the oxygenation shaft 31, and synchronously drives the first cleaning arm 41 and the second cleaning arm 42 connected to its outside to perform circular motion. At this time, the first cleaning arm 41 strictly follows the inverted conical geometric trajectory of the primary filter cartridge 111 and rotates and scrapes along its inclined generatrix, while the second cleaning arm 42 crosses the internal structure and rotates and scrapes concentrically along the vertical inner wall of the secondary filter cartridge 112. At the same time, the negative pressure suction device at the top is activated, and the negative pressure suction force generated therein is transmitted through the suction shaft 32 and the annular discharge gap 33, along the hollow guide tube 432 to the suction slit 431 on the working surface of the cleaning arm. Since the suction slit 431 is close to the filter screen wall and has a small flow cross-sectional area, the negative pressure airflow transmitted here forms a high-velocity local pressure difference suction zone, which quickly sucks the dirt that has just been mechanically disturbed by the cleaning arm into the guide tube 432, and finally into the annular discharge gap 33 of the suction shaft 32 for discharge.

[0078] Accordingly, this solution utilizes the specific motion trajectory of the first cleaning arm 41 extending along the generatrix of the cone and the second cleaning arm 42 adhering to the cylindrical wall. This allows the device to simultaneously meet the two distinct geometric cleaning requirements of the internal inclined curved surface and the external vertical curved surface through a single rotation of the central suction shaft 32. This ensures effective coverage and cleaning of the entire filtration area of ​​the two-stage filter cartridges without the need for additional drive mechanisms. Secondly, unlike the traditional method of simply scraping dirt into the water and letting it settle naturally by mechanical force, this solution utilizes the high synchronicity of the cleaning and suction actions to create a negative pressure adsorption field near the wall at the suction slit 431. This allows dirt adhering to the inner walls of the primary filter cartridge 111 and the secondary filter cartridge 112 to be sucked into the pipe, thus blocking the path of dirt to diffuse back into the filtrate due to gravity or water flow disturbance. This ensures the thoroughness of the cleaning process and avoids a secondary increase in water turbidity during the cleaning process.

[0079] Based on the above embodiments, it is further necessary to add that flexible scrapers 433 located on both sides of the suction slit 431 are provided on the working surfaces of the first cleaning arm 41 and the second cleaning arm 42, and raised turbulence ribs 421 are provided on the side of the second cleaning arm 42 facing away from the inner wall of the secondary filter cartridge 112. Figure 3 and Figure 4 As shown in the image.

[0080] Understandably, this solution addresses the technical problems of existing rigid cleaning components, such as easy damage to the precision filter screen, difficulty in maintaining a tight seal between the suction port and the filter screen leading to negative pressure suction leakage, and poor water flow in the filter cartridge gaps leading to dirt deposition, by setting flexible scrapers 433 on both sides of the suction slit 431 and adding baffles 421 on the back side of the second cleaning arm 42. Specifically,

[0081] The flexible scrapers 433 on both sides can tightly adhere to the filter screen surface by their own elastic deformation. While flexibly scraping off the attached dirt, they form a relatively closed suction area around the suction slit 431, effectively concentrating the negative pressure suction and preventing the surrounding water flow from diluting the suction. Meanwhile, the turbulence ribs 421 use the rotation of the cleaning arm to drive the water to generate turbulence, breaking the stagnant water layer between the filter cartridges, preventing suspended solids from settling and accumulating in the non-cleaning area, and enhancing the fluid circulation in the cavity.

[0082] It should be noted that in order to clean and discharge the dirt from the surfaces of the primary filter cartridge 111 and the secondary filter cartridge 112, it is usually necessary to configure an additional independent water pump (such as a self-priming pump or a submersible pump) as a power source. This not only increases the hardware cost and energy consumption of the device, but also makes its internal piping connection extremely complex.

[0083] Accordingly, this embodiment further solves the technical problems of high system redundancy and low energy efficiency caused by the need for an external power source for sewage discharge in the prior art by constructing a self-driven negative pressure mechanism composed of a centrifugal impeller disk and a sludge collection volute 521. Its specific structure is described in the following embodiment:

[0084] like Figure 2 and Figure 6 As shown, the negative pressure suction device includes a centrifugal impeller and a sludge collection volute 521 covering the outside of the centrifugal impeller;

[0085] The centrifugal impeller includes an upper cover plate 511, a lower cover plate 512, and a plurality of guide vanes 513. The lower cover plate 512 is sleeved at the top of the suction shaft 32. The upper cover plate 511 has a clearance hole in the middle, and the oxygenation shaft 31 passes through the clearance hole and is rotatably connected to the sludge collection volute 521 through a bearing. The plurality of guide vanes 513 are sandwiched between the upper cover plate 511 and the lower cover plate 512 and are arranged in a ring array around the center of the lower cover plate 512. The centrifugal flow channel inlet formed between adjacent guide vanes 513 is connected to the annular sludge discharge gap 33 in the suction shaft 32.

[0086] The inner wall of the sludge collection volute 521 forms a diffused water collection cavity with the centrifugal impeller disk. A drain pipe 522 extending tangentially and communicating with the diffused water collection cavity is also connected to the side wall of the sludge collection volute 521.

[0087] Understandably, the core mechanism by which the negative pressure suction device constructed in this embodiment achieves pump-free self-priming lies in the ingenious utilization of the synergistic effect of the system internal pressure accumulated under filtration conditions and centrifugal dynamics. Specifically,

[0088] During actual operation of the device, as the water to be treated is continuously pumped in through the inlet pipe 91 and the filter cartridge surface gradually traps dirt, the fluid resistance in the primary filtration chamber gradually transforms into significant system back pressure. This internal positive pressure forces the water to seek a pressure relief path, thereby forcibly pushing it in through the suction slit 431 submerged at the bottom, and overcoming gravity to rise upwards along the guide pipe 432 and the annular discharge gap 33 until it fills the centrifugal impeller channel at the top. This provides the essential initial start-up medium for the centrifugal mechanism. Based on this, when the suction shaft 32 drives the centrifugal impeller in the filled state to rotate at high speed, the fluid in the impeller channel gains high-speed tangential kinetic energy under mechanical thrust and is centrifuged. The force is thrown towards the surrounding sludge collection volute 521, causing an instantaneous fluid deficit at the center of the impeller and forming a high-intensity negative pressure core area. At this time, driven by the dual pressure difference of the positive water pressure push in the primary and secondary filter chambers acting on the suction slit 431 and the negative pressure suction at the center of the top centrifugal impeller disk, the adsorbed sludge mixture is vertically lifted along the suction shaft 32 at an extremely high flow rate and continuously replenished into the center of the impeller. Finally, it is collected and rectified by the sludge collection volute 521 and discharged at high speed along the tangential direction of the discharge pipe 522. This achieves efficient vertical discharge of deep sludge from the land-based device without relying on any external vacuum equipment, using only single-shaft drive, thereby further improving the device's performance.

[0089] For a further preferred embodiment of the above embodiments, please refer to Figure 5 The oxygenation shaft 31 is provided with an axially extending spiral blade 311 on the outer wall of the shaft body inside the suction shaft 32. The spiral blade 311 divides the annular sewage discharge gap 33 into independent spiral upward flow channels.

[0090] This solution effectively solves the technical problem that heavy pollutants are prone to slipping and falling back due to gravity during the vertical long pipe sewage discharge process by setting spiral blades 311 on the outer wall of the oxygenation shaft 31 and constructing the annular sewage discharge gap 33 as a spiral upward flow channel.

[0091] Specifically, when the oxygenation shaft 31 drives the suction shaft 32 and the negative pressure suction component to rotate synchronously, the spiral blades 311 form a circumferential constraint on the fluid. Utilizing the centrifugal force generated by the rotation and the suction force of the negative pressure suction component, the sludge is guided to flow steadily upward along the spiral ascending channel, preventing backflow or circumferential slippage of the sludge within the annular discharge gap 33. This eliminates the potential for blockage in the vertical discharge channel due to the deposition of high-concentration heavy sludge, fundamentally ensuring the continuity and thoroughness of the cleaning and discharge process. This allows the primary filter cartridge 111 and the secondary filter cartridge 112 to quickly return to their optimal permeability state (i.e., complete regeneration) after each cleaning cycle, thereby avoiding sludge residue and secondary clogging of the filter screen caused by poor discharge. This significantly maintains the high-throughput filtration stability of the device under long-term continuous operation and greatly reduces the frequency of downtime maintenance due to discharge system failures.

[0092] As a preferred embodiment of this solution, in Figure 3 As shown in the figure, two rotating sealing assemblies are provided axially spaced inside the bottom end of the suction shaft 32. The two rotating sealing assemblies seal and fill the space between the suction shaft 32 and the oxygenation shaft 31 and enclose to form a sealed bearing cavity.

[0093] Please refer to the details. Figure 7 and Figure 8 The rotational coupling mechanism is installed inside the sealed bearing cavity, and includes an active disc 61 fixedly connected to the oxygenation shaft 31 and a driven friction drum 62 coaxially rotatably sleeved outside the active disc 61 and fixedly connected to the inner wall of the suction shaft 32.

[0094] A plurality of centrifugal throwing blocks 611 are hinged to the active disc 61 by a pin, and a return spring is connected between the centrifugal throwing blocks 611 and the active disc 61.

[0095] When the drive motor 2 runs at the first speed, the centrifugal throwing block 611 remains in a retracted state under the action of the reset spring and is separated from the driven friction drum 62. When the drive motor 2 runs at the second speed, the centrifugal throwing block 611 opens outward and rubs against the inner wall of the driven friction drum 62 to drive the suction shaft 32 to rotate synchronously. The second speed of the drive motor 2 is greater than the first speed.

[0096] Based on the above embodiments, it can be understood that this solution achieves physical isolation of the transmission environment and intelligent switching of operating conditions based on rotational speed by constructing a sealed bearing cavity at the bottom end of the suction shaft 32 and encapsulating the centrifugal rotation coupling mechanism within it. Specifically,

[0097] First, in terms of the construction of the transmission environment, considering that the annular gap between the suction shaft 32 and the oxygenation shaft 31 is mainly used to transport high-concentration sewage mixture, in order to prevent impurities from entering and causing the precision transmission components to jam, this solution uses two axially spaced rotating sealing components to form an independent and closed sealed bearing cavity between the two shafts, which strictly isolates the mechanical components such as the centrifugal throwing block 611, the reset spring and the driven friction drum 62 from the external sewage channel, thereby ensuring that the internal transmission mechanism always operates under clean and lubricated conditions, effectively avoiding mechanical failure caused by sewage corrosion or particle deposition;

[0098] Secondly, this solution utilizes the physical characteristic that centrifugal force is proportional to the square of rotational speed to achieve decoupled control of multiple functions from a single power source. When the device is in the long-cycle daily aeration phase, the drive motor 2 is controlled to run at a lower first speed. At this time, the centrifugal force acting on the centrifugal sling block 611 is less than the preload set by the reset spring. The centrifugal sling block 611 remains in a retracted state under the traction of the spring and is completely separated from the peripheral driven friction drum 62. As a result, the aeration shaft 31 can rotate independently inside the suction shaft 32 to perform aeration and aeration, while the suction shaft 32 connected to the cleaning component remains stationary. This avoids the fluid resistance and mechanical energy consumption caused by the ineffective rotation of the cleaning component during non-cleaning periods, and greatly improves the daily operating energy efficiency ratio of the device.

[0099] When the device enters the cleaning and sewage discharge stage, the control drive motor 2 is accelerated to the second speed. At this time, the increased centrifugal force overcomes the spring resistance, forcing the centrifugal sling block 611 to open outward and press tightly against the inner wall of the driven friction drum 62. The friction force instantly locks the relative position of the two shafts, forcibly driving the suction shaft 32 to rotate synchronously. Thus, by simply adjusting the motor speed, the instantaneous switching from low-consumption oxygenation to powerful cleaning mode can be achieved, simplifying the electrical control system and maintenance difficulty of the equipment.

[0100] In addition, it is particularly important to point out that when the device starts cleaning and discharging, it often means that the primary filter cartridge 111 and the secondary filter cartridge 112 have trapped a large amount of dirt. At this time, the circulating water is in a dangerous critical state of high oxygen consumption and low dissolved oxygen due to the accumulation of high-load pollution. To address this, this solution sets a mechanical logic that requires the suction shaft 32 to rotate only when the speed is increased to the second speed. By utilizing the rigid connection between the oxygenation shaft 31 and the drive motor 2, the oxygenation shaft 31 is forced to enter a high-speed turbulent flow mode in response to the worst water quality conditions caused by blockage. Thus, while restoring the filtration flux using the suction shaft 32, the high-speed rotating oxygenation shaft 31 provides immediate and powerful high-specification dissolved oxygen compensation for severely oxygen-deficient water.

[0101] Obviously, for this solution, the specific values ​​of the first and second speeds are set based on the mass of the centrifugal sling block 611 and the stiffness coefficient of the return spring. The critical speed at which the centrifugal sling block 611 overcomes the preload of the return spring and begins to open outward is set as the threshold speed. To ensure the reliability of the working condition switching, the first speed is set to be less than this threshold speed. At this speed, the centrifugal force is insufficient to overcome the spring tension, ensuring that the centrifugal sling block 611 is always in a fully retracted state. At this time, the suction shaft 32 remains stationary, avoiding malfunctions. The second speed is set to be significantly greater than this threshold speed. At this speed, the centrifugal force generated by the centrifugal sling block 611 is much greater than the spring return force, thereby generating sufficient clamping force to form a rigid friction transmission with the driven friction drum 62, ensuring that the output torque can overcome the load resistance generated when the cleaning component scrapes the filter screen. At the same time, although the drive motor 2 operates at a low speed at the first speed... At the second rotational speed, the first rotational speed setting must still meet the minimum linear velocity requirement for the normal operation of the aeration components. That is, at the first rotational speed, the diffuser wheel 71 and shear fins 711 driven by the aeration shaft 31 still have sufficient rotational kinetic energy to break up bubbles and form radial turbulence to ensure the basic dissolved oxygen demand of the aquaculture water. When switching to the second rotational speed, as the rotational speed increases, the frequency of bubble breaking by the shear fins 711 and the intensity of water mixing will be greatly increased. This excess dissolved oxygen capacity is just used to compensate for the water disturbance and short-term high oxygen consumption caused by cleaning and sewage discharge, thereby achieving dynamic matching between dissolved oxygen supply and actual working conditions at different rotational speeds.

[0102] As a further optional implementation of this solution, such as Figure 2 As shown, an oxygenation component is also provided inside the oxygenation chamber 12. The oxygenation component includes an air diffuser 71 and an aeration disc 72, specifically as follows: Figure 9 As shown, the diffuser wheel 71 is sleeved on the oxygenation shaft 31 and located outside the shaft of the oxygenation chamber 12. Multiple shearing fins 711 are arrayed on the circumferential side wall of the diffuser wheel 71. The aeration disc 72 is installed at the bottom of the oxygenation chamber 12 and located below the diffuser wheel 71, and is connected to an external air source through an air inlet pipe passing through the wall of the tank 1.

[0103] This solution effectively solves the problem of low oxygen dissolution efficiency caused by the rapid rise and large diameter of bubbles in the prior art by setting an oxygenation assembly including a diffuser wheel 71, shear fins 711, and aeration disc 72 in the oxygenation chamber 12. Specifically,

[0104] An external air source enters the aeration disc 72 at the bottom through the air inlet pipe, initially releasing macroscopic bubbles. As these bubbles rise, they must pass through the diffuser wheel 71 located above. At this point, the shearing fins 711, rotating with the oxygenation shaft 31, act like high-speed cutting blades, subjecting the rising bubble cluster to high-frequency physical impacts and shearing, forcibly breaking the large-diameter bubbles into extremely small micron-sized bubbles. This process significantly increases the contact surface area between the gas and liquid phases, allowing oxygen in a unit volume of air to dissolve more quickly into the water.

[0105] Meanwhile, the rotation of the diffuser 71 creates a strong radial turbulence field in the oxygenation chamber 12, causing the broken microbubbles to be carried by the water flow and no longer simply rise vertically, but diffuse in a spiral shape with the water flow. This significantly extends the movement path and residence time of the bubbles in the water. Especially under high-speed cleaning conditions, due to the doubled rotation speed of the shear fins 711, the breaking and stirring effect reaches its peak, thus ensuring that the device can achieve a saturated oxygen supply, thereby significantly improving the oxygen utilization rate and the final dissolved oxygen content of the water.

[0106] As a further preferred option, the edge profile of each shear fin 711 is spiral-shaped.

[0107] Based on the above embodiments, it should be further added that the device also includes a differential pressure detection unit and a frequency conversion control unit;

[0108] exist Figure 2 As shown in the figure, the differential pressure detection unit includes a first pressure sensor 81 located inside the first-stage filter cartridge 111 and a second pressure sensor 82 located outside the second-stage filter cartridge 112. The first pressure sensor 81 and the second pressure sensor 82 are used to detect the water pressure values ​​before and after filtration, respectively.

[0109] The frequency conversion control unit is electrically connected to the first pressure sensor 81, the second pressure sensor 82, and the drive motor 2 (not shown in the figure). The frequency conversion control unit is equipped with a calculation and comparison module. The calculation and comparison module is used to receive two water pressure values ​​and calculate the difference between them and compare it with a preset threshold. If the comparison result shows that the difference is greater than the preset threshold, the frequency conversion control unit controls the drive motor 2 to work at a second speed. The high speed drives the suction shaft 32 to clean and enhance the shear oxygen dissolution efficiency of the oxygenation component. If the comparison result shows that the difference is less than the preset threshold, the frequency conversion control unit controls the drive motor 2 to maintain the first speed.

[0110] Based on the above embodiments, this solution cleverly constructs an integrated intelligent closed-loop control system combining monitoring, decision-making, and execution by introducing a differential pressure detection unit and a frequency conversion control unit, thereby achieving dynamic and precise matching between the device's operating energy consumption and purification requirements. Specifically:

[0111] First, it achieves on-demand cleaning based on the actual degree of filter clogging. The device uses a first pressure sensor 81 and a second pressure sensor 82 to monitor the transmembrane pressure difference between the inner side of the primary filter cartridge 111 and the outer side of the secondary filter cartridge 112 in real time. This pressure difference directly reflects the current physical clogging status of the filter (i.e., the thickness of the filter cake layer). When the calculation and comparison module determines that the pressure difference exceeds the preset threshold, it indicates that the filter cartridge has been substantially clogged. The frequency conversion control unit then commands the drive motor 2 to increase to the second speed, which directly triggers the aforementioned centrifugal coupling action to drive the suction shaft 32 to perform mechanical cleaning and negative pressure sewage discharge. Compared with the traditional time control mode, this pressure difference-based triggering logic avoids ineffective backwashing when the filter is not clogged and also eliminates overcurrent interruption caused by not reaching the designated time when the filter is severely clogged.

[0112] Secondly, it achieves dual-effect synergistic regulation of energy consumption and dissolved oxygen. That is, when the pressure difference is lower than the preset threshold, the motor is controlled to maintain the first speed. At this time, the rotation coupling mechanism is disengaged, the suction shaft 32 is stationary, and the device is in a low-energy pure oxygenation standby mode, saving operating costs to the maximum extent. Once the second speed is triggered for backwashing, in addition to restoring the filtration flux, the high speed simultaneously drives the shear fins 711 of the oxygenation component to rotate at high speed. This is not only for cleaning, but also to cope with the high pollution load and low dissolved oxygen risk of the water body represented by the high pressure difference. By instantaneously enhancing the shear oxygenation efficiency, it achieves automatic safety compensation for water quality fluctuations during cleaning, thereby greatly improving the device's performance.

[0113] Finally, to ensure the sufficiency of disclosure and feasibility of implementation of this solution, it should be specifically noted that: the first pressure sensor 81, the second pressure sensor 82, the drive motor 2, and the frequency conversion control unit (including its internal calculation and comparison module) mentioned in this embodiment are all mature general-purpose electrical and electronic components that can be directly purchased through market channels in the prior art. Specifically,

[0114] The frequency conversion control unit can be implemented in hardware using a programmable logic controller (PLC), a microcontroller (MCU), or an industrial frequency converter with integrated logic control functions. The calculation and comparison module and related control logic are actually preset computer programs or logic algorithms running in the aforementioned hardware processor. Those skilled in the art only need to follow the clear control strategy and logic flow disclosed in this specification—comparing the detected differential pressure value with a preset threshold and switching the motor speed based on the comparison result—and combine conventional programming techniques to write the above control logic into general-purpose control hardware and implement it. No creative effort or improvement of the hardware structure is required. Therefore, the above description of the electrical control part is clear, complete, and has industrial applicability.

[0115] Furthermore, it is understandable that, in order to ensure the mechanical stability and fluid tightness of the device, although not all bearings and seals are shown in the accompanying drawings of this specification, in this solution, all connections between rotating and stationary parts (or relatively rotating parts) are provided by default with suitable rotating support structures (such as rolling bearings or sliding bushings); similarly, all interfaces involving fluid isolation (such as the dynamic fit part where the oxygenation shaft 31 passes through the clearance hole of the upper cover plate 511) are strictly sealed by suitable rotary sealing components (such as mechanical seals, skeleton oil seals or combined sealing rings) to ensure the airtightness and watertightness of the device during operation.

[0116] In addition, it should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are all schematic diagrams, which are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0117] Furthermore, the directional terms such as above, below, left, right, and center used in this specification are merely for clarity of description and are not intended to limit the scope of implementation of this invention. Any changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered within the scope of implementation of this invention.

Claims

1. A multi-stage filtration and aeration integrated device for recirculating aquaculture, the device comprising a tank and a drive motor located at the bottom of the tank, characterized in that, The tank body is equipped with multiple filtration chambers and oxygenation chambers from top to bottom; The multi-stage filtration chamber is coaxially fitted with a primary filter cartridge and a secondary filter cartridge. The water to be treated passes through the primary filter cartridge and the secondary filter cartridge in sequence and enters the oxygenation chamber for treatment. The oxygenation chamber is also equipped with an outlet pipe that communicates with the outside for discharging the treated water. The device further includes a coaxial dual-drive assembly that runs through the middle of the tank, the coaxial dual-drive assembly comprising: An oxygenation shaft is connected to the drive motor at one end, and the other end passes through the oxygenation chamber and the multi-stage filtration chamber in sequence. The suction shaft is rotatably sleeved on the outside of the shaft body of the oxygenation shaft located inside the multi-stage filtration chamber, and its top end extends to the outside of the tank. An annular discharge gap for conveying waste is formed between its inner wall and the outer wall of the oxygenation shaft. The cleaning component is connected to the outside of the suction shaft and communicates with the annular discharge gap. It is used to clean the dirt attached to the surface of the primary filter cartridge and the secondary filter cartridge and transport it into the annular discharge gap. A negative pressure suction device is placed on top of the tank and connected to the top of the suction shaft. The internal flow channel of the negative pressure suction device is connected to the annular discharge gap, which is used to generate negative pressure and discharge the dirt when the suction shaft rotates. A rotary coupling mechanism is provided at the bottom end of the suction shaft, and the suction shaft is connected to the oxygenation shaft through the rotary coupling mechanism. It is used to control the separation or engagement of the two shafts to rotate synchronously according to the speed of the drive motor. The bottom end of the suction shaft is provided with two rotating sealing components spaced axially. The two rotating sealing components seal and fill the space between the suction shaft and the oxygenation shaft and form a sealed bearing cavity. The rotational coupling mechanism is installed inside the sealed bearing cavity, and includes an active disc body fixedly connected to the oxygenation shaft and a driven friction drum coaxially rotatably sleeved outside the active disc body and fixedly connected to the inner wall of the suction shaft. Several centrifugal throwing blocks are hinged to the active disc body by pins, and a return spring connects the centrifugal throwing blocks to the active disc body. When the drive motor runs at the first speed, the centrifugal sling block remains in a retracted state under the action of the reset spring and separates from the driven friction drum. When the drive motor runs at the second speed, the centrifugal sling block opens outward and rubs against the inner wall of the driven friction drum to drive the suction shaft to rotate synchronously. The second speed of the drive motor is greater than the first speed.

2. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 1, characterized in that: The multi-stage filtration chamber and the oxygenation chamber are separated by a partition plate. The first-stage filter cartridge is an inverted conical structure, and its bottom is connected to the partition plate to form a first-stage filtration chamber. An inlet pipe is provided in the first-stage filtration chamber to connect to the outside of the tank. The water to be treated enters the first-stage filtration chamber through the inlet pipe. The second-stage filter cartridge is a straight cylindrical structure, and its top and bottom ends are respectively closed and connected to the upper part of the inner wall of the multi-stage filtration chamber and the partition plate, forming a second-stage filtration chamber with the first-stage filter cartridge located inside it.

3. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 2, characterized in that: A clear water gap is formed between the outer wall of the secondary filter cartridge and the inner wall of the tank. Several through holes connected to the oxygenation chamber are opened at the edge of the partition plate at the clear water gap.

4. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 2, characterized in that: The cleaning assembly includes a first cleaning arm and a second cleaning arm for cleaning the inner walls of the primary filter cartridge and the secondary filter cartridge, respectively. The first cleaning arm and the second cleaning arm are each provided with a guide pipe that communicates with the annular sewage discharge gap. One end of the first cleaning arm is connected to the suction shaft, and the other end extends obliquely along the conical generatrix of the primary filter cartridge and fits against the inner wall of the primary filter cartridge. One end of the second cleaning arm is connected to the part of the suction shaft that protrudes from the top of the primary filter cartridge, while the other end is bent downward and attached to the inner wall of the secondary filter cartridge. Both the first and second cleaning arms have suction slits that are connected to their internal guide pipes on their working surfaces, which are respectively attached to the first-stage and second-stage filter cartridges.

5. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 4, characterized in that: The working surfaces of the first and second cleaning arms are provided with flexible scrapers located on both sides of the suction slit, and the side of the second cleaning arm facing away from the inner wall of the secondary filter cartridge is provided with protruding turbulence ribs.

6. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 1, characterized in that: The negative pressure suction device includes a centrifugal impeller and a sludge collection volute covering the outside of the centrifugal impeller. The centrifugal impeller includes an upper cover plate, a lower cover plate, and several guide vanes. The lower cover plate is sleeved at the top of the suction shaft. The upper cover plate has a clearance hole in the middle, and the oxygenation shaft passes through the clearance hole and is rotatably connected to the sludge collection volute through a bearing. Several guide vanes are sandwiched between the upper cover plate and the lower cover plate and are arranged in a ring array around the center of the lower cover plate. The centrifugal flow channel inlet formed between adjacent guide vanes is connected to the annular sludge discharge gap in the suction shaft. The inner wall of the sludge collecting volute and the centrifugal impeller disk form a diffuser water collecting cavity. A drain pipe extending tangentially and communicating with the diffuser water collecting cavity is also connected to the side wall of the sludge collecting volute.

7. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 6, characterized in that: The oxygenation shaft is located inside the suction shaft. On the outer wall of the shaft body, a spiral blade extending along the axial direction is provided. The spiral blade divides the annular sewage discharge gap into independent spiral upward flow channels.

8. The multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 1, characterized in that: The oxygenation chamber is also equipped with an oxygenation component, which includes an air diffuser and an aeration disc. The air diffuser is sleeved on the oxygenation shaft and located outside the shaft of the oxygenation chamber. Multiple shearing fins are arrayed on the circumferential sidewall of the air diffuser. The aeration disc is installed at the bottom of the oxygenation chamber and below the air diffuser, and is connected to an external air source through an air inlet pipe that passes through the tank wall.

9. A multi-stage filtration and aeration integrated device for recirculating aquaculture as described in claim 1, characterized in that: The device also includes a differential pressure detection unit and a frequency conversion control unit; The differential pressure detection unit includes a first pressure sensor located inside the first-stage filter cartridge and a second pressure sensor located outside the second-stage filter cartridge. The first pressure sensor and the second pressure sensor are used to detect the water pressure values ​​before and after filtration, respectively. The frequency conversion control unit is electrically connected to the first pressure sensor, the second pressure sensor, and the drive motor. The frequency conversion control unit is equipped with a calculation and comparison module. The calculation and comparison module is used to receive the pressure values ​​of the two water bodies and calculate the difference between them and compare it with a preset threshold. If the comparison result shows that the difference is greater than the preset threshold, the frequency conversion control unit controls the drive motor to work at a second speed. The high speed drives the suction shaft to clean and enhance the shear oxygen dissolution efficiency of the oxygenation component. If the comparison result shows that the difference is less than the preset threshold, the frequency conversion control unit controls the drive motor to maintain the first speed.

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