Microbubble shellfish purification and temporary culture system and method based on cross rotational flow shear coupling

Abstract

The invention discloses a microbubble shellfish purification and temporary culture system and method based on cross rotational flow shear coupling, and belongs to the technical field of aquaculture purification. The system comprises a circulating water pump, a temporary culture box body and a gas-liquid coupling jet device arranged at an inlet of the box body. A turbulent flow core with crossed rotational flow grooves is arranged in the jet device, so that circulating water and sucked gas form high-speed rotating turbulent flow when flowing through and collide and shear, micro-bubbles are generated in situ and then are tangentially jetted into the box body, and a water body is driven to form rotational flow. A bearing net plate with an arc-shaped flow guide hole and an inverted-cone-shaped sewage collecting funnel bottom are arranged in the box body, a double-channel sewage discharging assembly is arranged in the center of the bottom, and directional sewage discharging and clear liquid circulation are achieved. According to the device, independent aeration equipment is not needed, efficient cleaning and oxygenation are achieved through the synergistic effect of microbubbles and rotational flow, meanwhile, shellfish stress is avoided, and cross contamination is effectively prevented.

Description

Technical Field

[0001] This invention relates to shellfish holding equipment, and more particularly to a microbubble shellfish purification and holding system and method based on cross-swirling shear coupling. Background Technology

[0002] Shellfish, such as oysters, scallops, and clams, typically require temporary holding and purification before being sold to remove mud, pathogens, and metabolic waste. Traditional holding methods often involve simple flowing water tanks or stacked net cages. However, shellfish secrete large amounts of mucus during purification, which, combined with feces, easily adheres to the bottom of the holding tank or the surface of the shells. If water circulation is poor, the shellfish will re-inhale these contaminants, leading to "secondary pollution" and seriously affecting food safety indicators. Furthermore, traditional cleaning methods rely on manual rinsing, which is labor-intensive and can easily cause stress and shell closure in shellfish, reducing purification efficiency. Shellfish temporary holding mainly faces three major challenges: "difficult-to-remove mucus, low dissolved oxygen, and cross-contamination." Specific problems are as follows:

[0003] The specific issues are as follows:

[0004] 1. Existing microbubble aeration technology typically requires separate air compressors and microbubble generators, resulting in high equipment costs, complex piping, and difficult maintenance. Traditional bottom aeration produces large-diameter bubbles that rise rapidly, making it impossible for them to remain in the water for extended periods or penetrate deep into the folds of shellfish for effective cleaning.

[0005] 2. The flow pattern is monotonous. Most existing tanks have a flat bottom structure, and the water flow cannot remove sticky dirt from the bottom. If a strong water flow is directly applied to the aquaculture water, it can easily cause shellfish to close their shells and stop filtering and purifying.

[0006] 3. Traditional Venturi jets mostly adopt T-shaped or right-angled Y-shaped structures, resulting in significant kinetic energy loss at the confluence of fluids, leading to insufficient swirling driving force and poor gas-liquid mixing uniformity.

[0007] 4. Existing patent CN117678544A, "An Ecological Purification and Temporary Holding Device for Shellfish," discloses a stacked temporary holding rack that uses a water pump to draw water to the top layer, which then flows down layer by layer, combining microalgae and filter cotton for purification. This patent relies on gravity laminar flow and filter cotton interception. Laminar flow cannot remove viscous metabolites, the filter material is easily clogged, and it causes secondary pollution.

[0008] 5. Existing patent US20150373954A1 discloses a recirculating aquaculture system that uses airlift and biological filters for water treatment, but the bubble generator is independent and located at the bottom. The upflow impacts the ventral surface of the shellfish, causing shell-closing stress, and the large bubbles cannot penetrate deep into the folds for cleaning. Summary of the Invention

[0009] To address the aforementioned issues, this invention discloses a microbubble shellfish purification and temporary holding system and method based on cross-swirling shear coupling. The system utilizes a cross-swirling shear gas-liquid coupling jet generator to generate microbubbles in situ, and achieves self-cleaning and cross-contamination prevention through flexible swirling flow, thus creating a shellfish circulating water purification and temporary holding system.

[0010] A microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling includes a circulating water pump, a temporary holding tank, and a gas-liquid coupling jet ejector located at the inlet of the temporary holding tank. The gas-liquid coupling jet ejector has a turbulence core inside, and at least one set of cross-swirling grooves are formed on the surface of the turbulence core. Each cross-swirling groove consists of at least two sets of left-handed and right-handed spiral grooves with opposite rotation directions, forming multiple cross-collision points on the surface of the turbulence core. When the circulating water and the inhaled gas flow through the cross-swirling grooves, they form a high-speed rotating turbulent flow and collide and shear within the mixing chamber of the jet ejector, generating microbubbles which are then tangentially injected into the temporary holding tank. A support mesh plate is provided inside the tank; a sludge collection funnel is located below the support mesh plate; a dual-channel sludge discharge assembly is located at the center of the tank bottom.

[0011] As a preferred embodiment, the geometric parameters of the turbulence core are determined through fluid dynamics optimization: the length-to-diameter ratio (L / D) is preferably 1.5-2.2. This range ensures sufficient development of the swirling flow and controllable pressure loss. When L / D < 1.5, the swirling flow is insufficient, leading to uneven gas-liquid mixing; when L / D > 2.2, the flow channel is too long, increasing the system pressure loss by more than 30%. The helix angles of the left and right helical grooves are set to 45°-60°, causing the two fluids with opposite directions of rotation to collide inelasticly at the intersection point at an angle of 90°-120°. This design enables the two swirling flows to generate high-intensity shear at the collision point, effectively overcoming the surface tension of the liquid, thereby forcibly breaking the inhaled air mass into micron-sized bubbles.

[0012] Furthermore, the jet ejector includes an inlet, a premixing chamber, a swirl generation zone, a main mixing chamber, and an accelerating nozzle connected in sequence; the inlet is used to connect circulating water and is connected to the inlet end of the premixing chamber; the premixing chamber has an air intake port on its cavity; the swirl generation zone is located in the lower part of the premixing chamber, and the turbulence core is provided in the swirl generation zone, with the cross swirl groove formed on the surface of the turbulence core; the main mixing chamber is located in the lower part of the swirl generation zone and is connected to it, and the accelerating nozzle is located at the outlet of the main mixing chamber; the cross swirl groove is used to force the fluid to generate rotational motion to overcome the surface tension of the liquid phase;

[0013] The accelerating nozzle employs a three-section Venturi structure, consisting of an upstream expansion section, a middle contraction throat, and a downstream diffusion section. The expansion section connects to the main mixing chamber, and its inner diameter gradually decreases from the inlet end to the throat; the throat is the minimum flow cross-section. The diffusion section gradually expands from the throat to the outlet end, with a diffusion angle α of 5°-15°. This structure creates a low-pressure zone in the throat through the Venturi effect, causing secondary atomization of bubbles under high-speed jet flow. Simultaneously, the diffusion section slows down the flow velocity, preventing bubbles from re-coalescing after bursting. The pressure drop effect promotes secondary atomization of the bubble nuclei.

[0014] Furthermore, the dual-channel sewage overflow assembly includes an inner pipe and an outer pipe arranged concentrically. The inner pipe serves as a sewage discharge channel, with its upper inlet directly connected to and penetrating the opening at the lowest point of the sewage collection funnel, and its lower end serving as a sewage outlet for discharging collected sewage. The outer pipe serves as an overflow channel, fitted around the inner pipe, forming an annular flow path between them. The upper part of the outer pipe has at least one overflow opening, and its lower end is connected to a return water pipe for guiding the overflowing clear liquid back to the circulation system. In this invention, the inner pipe connects to the lowest point of the funnel for sewage discharge, and the outer pipe connects to the upper part of the housing for overflowing clear liquid.

[0015] Furthermore, the supporting mesh plate is provided with several arc-shaped guide holes, and the arrangement direction of the guide holes is consistent with the swirling direction inside the box.

[0016] Furthermore, the system does not contain a separate electric microbubble generator; the microbubbles are generated in situ by the jet injector using the kinetic energy of water.

[0017] A microbubble-based method for the purification and temporary holding of shellfish based on cross-swirling shear coupling includes the following steps:

[0018] Step S1: Start and initialize the system, and set the quiet mode frequency threshold fquiet and the self-cleaning mode frequency threshold fclean;

[0019] Step S2: In the quiet mode, run the circulating water pump with fquiet to generate microbubbles with an average particle size of 50–80 μm, maintain high dissolved oxygen in the tank and avoid stress on the shellfish;

[0020] Step S3: When the system triggers the cleaning command, switch to self-cleaning mode and run the circulating water pump at fclean (45–60Hz) to generate microbubbles with an average particle size of 10–30μm to peel off the mucus on the surface of shellfish.

[0021] Step S4: During operation, the system monitors the dissolved oxygen and turbidity values ​​of the water in real time and adaptively fine-tunes the pump frequency f to ensure that the microbubble particle size remains stable within the target range.

[0022] Furthermore, the pump frequency setting is based on a preset correspondence between the pump frequency and the microbubble particle size; this correspondence is obtained through system calibration and satisfies the following: in static mode, the average microbubble particle size is maintained at 50–80 μm to prolong the residence time of the bubbles in the water and improve dissolved oxygen mass transfer efficiency; in self-cleaning mode, the average microbubble particle size is compressed to 10–30 μm to enhance the local shear force when the bubbles burst, thereby achieving physical peeling of mucus from the shellfish surface.

[0023] The beneficial effects of this invention are:

[0024] 1. By confining the intense air-water shearing within the nozzle, the direct impact on shellfish in the aquaculture water is avoided, thus achieving both the highly efficient cleaning ability of microbubbles and ensuring a quiet living environment for the shellfish.

[0025] 2. The swirling flow field driven by the gas-liquid mixture, combined with the inverted conical funnel bottom, enables the automatic collection and discharge of sludge, solving the problem of sedimentation dead zones in traditional flat-bottomed boxes.

[0026] 3. The central dual-channel design ensures that the contaminated bottom water is directly discharged, and only the upper clear liquid is recycled, completely eliminating cross-contamination between layers.

[0027] 4. Completely eliminating the need for external air pumps and compressors, the system relies solely on the Venturi self-priming effect driven by a circulating water pump and cross-swirling shear coupling to achieve efficient in-situ microbubble generation. This design not only significantly reduces equipment costs and maintenance complexity but also avoids the pollution risks that may be introduced by external air sources, truly achieving green purification with zero dependence on air sources.

[0028] 5. High microbubble generation efficiency: Through optimized helix angle and aspect ratio design, combined with a specific area shrinkage ratio K, 10–80 μm microbubbles can be efficiently prepared without the need for an external air compressor.

[0029] 6. This invention abandons the traditional extensive operation mode of continuous aeration + fixed frequency, and adopts dual-mode variable frequency control based on a gas-liquid shear-breaking dynamic model. The system generates microbubbles with different functions as needed according to the physiological needs of shellfish. During the resting phase, large bubbles are output to achieve a long residence time for efficient oxygenation, while during the self-cleaning phase, small bubbles are output to obtain high shear force for deep peeling. This effectively avoids ineffective aeration and excessive cleaning, saving energy compared to traditional continuous operation while significantly reducing stress on shellfish.

[0030] 7. This invention actively collects dirt through cross-swirling flow and generates microbubbles in situ to achieve deep cleaning, avoiding cross-contamination without the need for filter media; the removal rate of E. coli and the sand removal rate of this system are significantly better than those of traditional flat-bottomed boxes.

[0031] 8. This invention uses a sludge collection funnel bottom and a dual-channel sludge discharge assembly to automatically collect sludge and separate the clear and turbid in real time using swirling centrifugal force, achieving continuous self-cleaning without dead corners.

[0032] 9. This invention completely confines the gas-liquid shearing process inside the ejector, outputting only a flexible vortex of 0.08-0.25 m / s, which ensures deep penetration of microbubbles while avoiding stress reactions. Attached Figure Description

[0033] Figure 1 1. A cross-sectional view of the cross-swirling jet generator of the present invention;

[0034] Figure 2 The diagram shows the swirl-flow temporary storage system and its internal flow field of the present invention.

[0035] Figure 3 1. A detailed view of the central dual-channel component of this invention;

[0036] Figure 4 Diagram of shellfish purification and temporary holding device system;

[0037] Figure 5 Flowchart of dual-modal control based on flow field-particle size mapping model.

[0038] List of reference numerals in the attached diagram:

[0039] 100-Circulating power system; 110-Circulating water pump; 120-Inlet water pipe; 130-Air inlet pipe; 140-Flow regulating valve; 200-Gas-liquid coupling jet device; 210-Premixing chamber; 220-Turbulence core; 221-Left-hand spiral groove; 222-Right-hand spiral groove; 230-Main mixing chamber; 240-Air intake port; 250-Accelerating nozzle; 260-Liquid inlet; 300-Temporary holding tank body; 310-Tangential water inlet; 320-Arc-shaped guide plate; 330-Bottom of sludge collection funnel; 340-Outer shell of the tank; 400-Dual-channel sewage discharge assembly; 410-Inner pipe sewage discharge port; 420-Outer pipe overflow port; 430-Synchronous control valve; 440-Return water pipe. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0041] Example 1

[0042] like Figure 1-5The present embodiment describes a swirling shellfish temporary holding and purification system driven by a cross-swirling gas-liquid coupling jet.

[0043] The system is driven by a circulating power system. First, the circulating water pump 110 is started by the control system, which delivers circulating water pre-filled with nutrient solution or purifying agent to the subsequent devices via the inlet pipe 120. Air is automatically drawn into the jet injector through the air inlet pipe 130, which is connected to the atmosphere, and the air intake 240. A flow regulating valve 140 is installed on the pipeline to adjust the water pressure and flow rate entering the jet injector according to different temporary curing stages, such as the static curing stage or the self-cleaning stage.

[0044] Water flows into the gas-liquid coupling jet device 200. The water first enters the premixing chamber 210, where, under pressure drop, it automatically draws in external air through the air intake 240. Subsequently, the gas-liquid mixture enters the core swirling generation zone, which is equipped with a turbulence core 220. In this embodiment, the diameter D of the turbulence core 220 is preferably 20-40 mm, and the length-to-diameter ratio is preferably 1.8:1.

[0045] Verification of the effectiveness of the technical solution in this embodiment

[0046] experimental group Aspect Ratio L / D Helix angle α Average bubble size d32 System pressure loss Example 1 1.8 55° 22μm 0.25 Comparative Example 1 1.2 55° 150μm 0.16 Comparative Example 2 1.8 30° 320μm 0.19

[0047] The surface of the turbulence core is provided with four left-handed spiral grooves 221 and four right-handed spiral grooves 222, which are intersected, with a spiral helix angle α set to 55°. The ratio of groove depth h to groove width w is set to 1:1.3. This design causes the two fluids with opposite directions of rotation to collide inelasticly at the intersection point at an angle of approximately 110°. When the mixed flow is forced into the cross grooves at a pressure of approximately 0.25 MPa, the water flow is split into multiple high-speed, opposing streams. These streams undergo high-frequency, violent impacts at the intersection point, instantly tearing the air apart within the main mixing chamber 230.

[0048] Finally, the mixed stream is ejected through the accelerating nozzle 250. To achieve optimal secondary atomization, the total flow cross-sectional area S of the cross-swirling channel is designed. groove The throat cross-sectional area S of the acceleration nozzle 250 nozzle The ratio K = 0.68. At this point, the flow velocity instantly increases to 15-22 m / s, and the shearing and fragmentation effect generated by the high-speed jet produces a milky white microbubble emulsion with an average particle size of 30-50 μm.

[0049] The system in this embodiment does not require an external air source and relies entirely on the Venturi self-priming effect: when high-speed water flows through the acceleration nozzle 250, a momentary negative pressure of -0.08 MPa to -0.22 MPa is formed in the throat, and ambient air is automatically drawn in through the air intake 240.

[0050] The cross-swirling groove structure further enhances the intake stability—the opposing vortex cores formed by the left and right spiral grooves generate a periodic low-pressure zone in the mixing chamber, effectively suppressing the coalescence of air nuclei and ensuring that the intake air remains uniformly dispersed even at high frequency operation.

[0051] Actual measurements show that when the pump frequency increases from 20 Hz to 50 Hz, the air intake increases by about 2.8 times, with the air-to-water volume ratio increasing from 1:18 to 1:10, providing a sufficient air source for compressing the microbubble particle size from 65 μm to 22 μm.

[0052] Microbubble water is injected tangentially into the inner side of the holding tank body 300 through the tangential inlet 310, driving the water inside the tank to form a swirling field rotating around the central axis. The shellfish are placed on the arc-shaped guide plate 320. The guide holes on the plate 320 are aligned with the swirling direction, ensuring that the microbubbles can fully penetrate to the shellfish's gills for purification and oxygenation, while also guiding the water flow carrying shed mucus, fecal matter, and other pollutants downwards along the rotational trajectory. Under the combined action of centrifugal force and gravity, the pollutants converge towards the lowest point in the center of the collection funnel 330.

[0053] The dual-channel drainage component 400, located at the center of the tank bottom, is responsible for the final solid-liquid separation. In pulse self-cleaning mode, the drainage path is opened via a synchronous control valve 430. Heavy contaminants accumulated at the bottom of the funnel are directly discharged from the system through the inner pipe drainage port 410. Simultaneously, the purified liquid at the top flows back through the concentrically designed outer pipe overflow port 420 and enters the next cycle via the return water pipe 440. This concentric pipe design with internal drainage and external overflow ensures in-situ self-cleaning and efficient drainage without stopping the circulation.

[0054] Example 2:

[0055] This embodiment demonstrates the system's operational logic during actual temporary maintenance, mainly including a static maintenance mode and a pulse self-cleaning mode, which are automatically switched by the intelligent control unit (PLC) according to preset logic:

[0056] 1. Quiet mode (low-frequency continuous operation):

[0057] Operating parameters: The water pump is set to operate at a low frequency of 20 Hz, and the volume ratio of air to circulating water drawn in by the jet injector is controlled at 1:15-1:20. A stable swirling flow field is formed within the tank, with the tangential flow velocity in the area supporting the mesh plate maintained at 0.08-0.12 m / s, and the axial flow velocity in the central area approximately 0.05 m / s. This flow velocity range can maintain a dissolved oxygen concentration >6.0 mg / L, meeting the filter-feeding requirements of shellfish, while avoiding excessive flow velocity that could cause shell-closing stress. Microbubbles are evenly distributed under the action of the swirling flow, allowing them to penetrate into the gill folds of the shellfish for gentle cleaning.

[0058] Dissolved oxygen control logic: The system automatically fine-tunes the water pump frequency to increase the air-water mixing intensity to compensate for oxygen consumption when the detected value is lower than the set threshold based on real-time feedback from the dissolved oxygen sensor; when dissolved oxygen is sufficient, the frequency is reduced to save energy.

[0059] 2. Pulse mode (high-frequency intermittent operation):

[0060] Operating parameters: Every 4 hours, the control system drives the water pump to switch to 50Hz high-frequency operation for 5-10 minutes. During this time, the air-to-water volume ratio of the jet injector increases to 1:8-1:12, and the microbubble concentration increases significantly. The tangential flow velocity inside the tank increases to 0.15-0.25 m / s. This flow velocity can effectively remove mucus and feces from the surface of shellfish, while preventing damage from rolling.

[0061] Sewage discharge action: When the pulse mode is started, the control valve 430 is opened synchronously. The secondary flow effect generated by the swirling field is used to directionally collect the bottom dirt to the center opening of the dirt collection funnel, and then quickly discharge it from the system through the inner pipe 420.

[0062] 2. Automatic mode switching logic

[0063] The system supports multi-condition trigger switching:

[0064] (1) Timed baseline: The default cycle is "rest for 230 minutes - self-cleaning for 10 minutes";

[0065] (2) Water quality feedback: When the turbidity sensor detects a value that is consistently below 5 NTU for 30 minutes, it is determined that the metabolic products have decreased and the resting period is automatically extended to 6 hours.

[0066] (3) Dissolved oxygen protection: When dissolved oxygen <4.0 mg / L, the pump frequency is forcibly increased to 30 Hz to maintain basic oxygenation, with higher priority than other logic.

[0067] The above operating parameters are typical examples of working conditions. In practical applications, the system can dynamically and specifically adjust the frequency and bubble size according to the fluid dynamics mapping model to achieve on-demand purification (see Example 3).

[0068] Example 3:

[0069] This embodiment, based on Embodiment 2, introduces a dual-mode variable frequency control method based on the flow field shearing and breaking mechanism, utilizing a pump frequency regulation strategy based on a fluid dynamics mapping model. The system's built-in control unit is constructed based on Hinze's turbulent breaking theory. 32 The energy transfer efficiency function η(f) was obtained by calibrating with the CFD simulation software Fluent using a correlation model with the flow field parameters and in combination with the geometric characteristics of the jet in this system (length-to-diameter ratio of the turbulent core L / D=1.8, helix angle α=55°, and area shrinkage ratio K=0.68).

[0070] The fluid dynamics mapping model satisfies the following nonlinear relationship:

[0071]

[0072] Where, d 32 σ is the Sauter mean diameter of the microbubbles; σ is the surface tension of the water; ρ is the density of the water; P in P is the inlet pressure of the ejector; η(f) is the energy transfer efficiency function related to the pump frequency f; the control system changes the inlet pressure P by adjusting the frequency f. in Therefore, the bubble particle size d can be precisely controlled based on the above model. 32 This allows it to switch between the mass transfer particle size (50–80 μm) required for oxygenation and the stripping particle size (10–30 μm) required for cleaning as needed; where P in It exhibits a monotonically increasing nonlinear relationship with f, and this relationship is predetermined through system calibration.

[0073] In static mode, the water pump operates at a frequency of 25 Hz, with an inlet pressure P. in Maintaining a pressure of 0.18 MPa, the calculated d32 ≈ 65 μm. Bubbles of this size rise slowly and remain in the chamber for over 120 seconds, significantly improving gas-liquid mass transfer efficiency. Actual dissolved oxygen levels were stable at 7.8 mg / L, with a shell-closing rate of less than 9%.

[0074] In self-cleaning mode, the water pump frequency jumps to 50Hz, P in Increased to 0.25 MPa, d 32 Compressed to 22μm, these microbubbles can penetrate deep into the gill folds of shellfish and generate localized microjet streams upon rupture, stripping away sticky pseudofeces. Combined with a 0.22m / s tangential vortex, the sand removal rate reaches 98.2%, and the E. coli removal rate reaches 3.8log.

[0075] The system also incorporates PID fine-tuning: when water temperature changes cause a change in σ, the dissolved oxygen sensor provides a deviation signal, and the PID module compensates for the pump frequency f by ±2Hz to ensure d 32 Fluctuations are less than ±5μm. The PID module is only used to compensate for environmental disturbances (such as changes in water temperature causing changes in σ), while the main control logic is still dominated by the physical model.

[0076] This method is significantly different from the simple control logic in existing technologies that are based solely on dissolved oxygen or incubation time.

[0077] Example 4:

[0078] Purification effect comparison test

[0079] Three thousand Manila clams of similar size (shell length 30±2mm) were randomly divided into three groups of 1,000 clams each. A 24-hour purification experiment was conducted under the same conditions of water temperature 20±1℃ and salinity 28±1‰.

[0080] Group A (this invention): Using this system, the rest / pulse operation alternates, with pulses occurring 4 hours / time × 6 times;

[0081] Group B (Traditional Flow): Flat-bottomed tank, water exchange rate 50% / h, no active aeration;

[0082] Group C (bottom aeration): combination of flat-bottomed box and microporous aeration disc, air volume 1.0L / min, water exchange rate 20% / h.

[0083] The sediment content, microbial indicators, and shellfish stress status were measured before and after the experiment. The results are shown in the table below:

[0084] index Group A (This invention) Group B (flowing) Group C (Aeration) Detection methods Results Analysis Sand removal rate (%) 98.2±1.3 85.6±2.7 76.3±3.1 Gravimetric determination The swirling flow effectively removes the slime-laden mud and sand, leaving no blind spots. E. coli removal rate (log) 3.8±0.2 2.1±0.3 2.5±0.4 GB4789.3-2016 Microbubbles penetrate deep into the gill folds of shellfish to detach attached bacteria, while a swirling flow field, combined with the bottom of a collection funnel, ensures targeted discharge of waste, preventing secondary contamination. Closed-shell stress generation rate (%) 8.5±1.2 35.2±3.5 42.7±4.1 Visual statistics The flexible vortex prevents bubbles from directly impacting the ventral side of shellfish, significantly reducing mechanical stimulation. Average dissolved oxygen in water (mg / L) 7.8±0.3 5.2±0.4 6.5±0.3 HJ 506-2009 30-50 μm microbubbles have a long residence time and high dissolution efficiency.

[0085] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling, characterized in that, The device includes a circulating water pump (110), a temporary holding tank (300), and a gas-liquid coupling jet (200) located at the inlet of the temporary holding tank (300). The gas-liquid coupling jet (200) has a turbulence core (220) inside, and at least one set of cross swirling grooves are formed on the surface of the turbulence core (220). The cross swirling grooves are composed of at least two sets of left spiral grooves (221) and right spiral grooves (222) with opposite directions of rotation. The two sets of spiral grooves form multiple cross collision points on the surface of the turbulence core (220). When the circulating water and the gas being drawn in flow through the cross swirling grooves, they form a high-speed rotating turbulence and collide and shear in the mixing chamber of the jet (200), generating microbubbles which are then injected tangentially into the temporary holding tank (300).

2. The microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 1, characterized in that, The box (300) is equipped with a support mesh plate (320) inside; a sludge collection funnel bottom (330) is provided below the support mesh plate (320); the temporary holding box (300) is equipped with a support mesh plate (320) inside; and a dual-channel sludge discharge assembly (400) is provided at the center of the bottom of the box.

3. The microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 1, characterized in that, The jet injector (200) includes an inlet (260), a premixing chamber (210), a swirling zone, a main mixing chamber (230), and an accelerating nozzle (250) connected in sequence. The inlet (260) is used to connect to circulating water and is connected to the inlet end of the premixing chamber (210). An air intake (240) is provided on the cavity of the premixing chamber (210). The swirling zone is located at the lower part of the premixing chamber (210), and the turbulence core (220) is provided in the swirling zone. The cross swirling groove is opened on the surface of the turbulence core (220). The main mixing chamber (230) is located at the lower part of the swirling zone and is connected to it. The accelerating nozzle (250) is located at the outlet of the main mixing chamber (230).

4. The microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 3, characterized in that, The specific design parameters of the turbulence core (220) meet the following conditions: the helix angle α of the left helical groove (221) and the right helical groove (222) is set to 5°-60°, so that the two fluids with opposite directions of rotation collide at the intersection with an angle of 90°-120°.

5. A microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 4, characterized in that, The ratio of the groove depth h to the groove width w of the spiral groove is 1:1.2 to 1:1.5; the total flow cross section S of the cross swirl groove groove With the acceleration nozzle (250) throat cross-sectional area S nozzle The area shrinkage ratio K is S nozzle / S groove The K value ranges from 0.6 to 0.

75.

6. The microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 2, characterized in that, The dual-channel sewage overflow assembly (400) includes an inner pipe (410) and an outer pipe (420) arranged concentrically. The inner pipe (410) is a sewage discharge channel, with its upper inlet directly connected to and penetrating the opening at the lowest point of the bottom (330) of the sewage collection funnel, and its lower end serving as a sewage outlet (410) for discharging the collected sewage. The outer pipe (420) is an overflow channel, sleeved on the outside of the inner pipe (410), forming an annular flow channel between the two. The upper part of the outer pipe (420) is provided with at least one overflow opening (420), and the lower end of the outer pipe (420) is connected to the return water pipe (440) for guiding the overflowing clear liquid back to the circulation system.

7. The microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 2, characterized in that, The bearing mesh plate (320) is provided with a number of arc-shaped guide holes, and the arrangement direction of the guide holes is consistent with the swirling direction inside the box (300); the box (300) is provided with a tangential water inlet (310).

8. The microbubble shellfish purification and temporary holding system based on cross-swirling shear coupling according to claim 1, characterized in that, The system does not have an independent electric microbubble generator; the microbubbles are generated in situ by the gas-liquid coupling jet generator (200) using the kinetic energy of water.

9. A microbubble-based method for the purification and temporary holding of shellfish based on cross-swirling shear coupling, applied to a microbubble-based method for the purification and temporary holding of shellfish based on cross-swirling shear coupling as described in any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Start and initialize the system, and set the quiet mode frequency threshold fquiet and the self-cleaning mode frequency threshold fclean; Step S2: In the quiet mode, run the circulating water pump (110) with fquiet to generate microbubbles with an average particle size of 50–80 μm, maintain high dissolved oxygen in the tank and avoid stress on the shellfish; Step S3: When the system triggers the cleaning command, it switches to self-cleaning mode and runs the circulating water pump (110) at 45–60Hz to generate microbubbles with an average particle size of 10–30μm to peel off the mucus on the surface of shellfish. Step S4: During operation, the system monitors the dissolved oxygen and turbidity values ​​of the water in real time and adaptively fine-tunes the pump frequency f to ensure that the microbubble particle size remains stable within the target range.

10. A microbubble-based method for the purification and temporary holding of shellfish based on cross-swirling shear coupling according to claim 9, characterized in that, The pump frequency setting is based on a preset correspondence between the pump frequency and the microbubble size. This correspondence is obtained through system calibration and satisfies the following: In static mode, the average microbubble size is maintained at 50–80 μm to prolong the residence time of bubbles in the water and improve dissolved oxygen mass transfer efficiency. In self-cleaning mode, the average particle size of microbubbles is compressed to 10–30 μm to enhance the local shear force when the bubbles burst, thereby achieving physical removal of mucus from the surface of shellfish.

Images