JP2021019509A - Closed type land-based aquaculture apparatus and land-based aquaculture method using the same - Google Patents

Abstract

To provide a closed type land-based aquaculture apparatus that can stimulate aquaculture products without problems, while preventing excessive generation of fine air bubbles with cavitation processing of aquaculture water and a land-based aquaculture method using the same.SOLUTION: An oxygen concentration in aquaculture water decreased due to consumption by aquaculture products is covered by an oxygen dissolution mechanism, and the oxygen concentration of the aquaculture water is maintained in 2.5 ppm or more and 7 ppm or less being less than a saturation value. The aquaculture water is guided to a cavitation nozzle by a pump for cavitation processing through piping 181 for cavitation processing, and is circulated at a specified flow rate where a cross-sectional average flow rate in the cavitation processing unit becomes 8 m/sec or more, and thereby the cavitation processing is performed. The oxygen concentration of the aquaculture water is maintained to less than a saturation value daringly, and thereby the excessive generation of fine air bubbles with the cavitation is prevented, and also the air bubbles adhere to gills of the aquaculture products and such failures as obstruction of taking the dissolved oxygen can be prevented effectively.SELECTED DRAWING: Figure 1A

Description

The present invention relates to a closed aquaculture apparatus and a land aquaculture method using the same.

Various closed-type aquaculture methods have been proposed in which aquaculture water is filtered and circulated in an aquaculture pond on land to cultivate crustaceans such as shrimp and crabs or aquaculture such as fish. On the other hand, it has been proposed to promote the growth of aquaculture products such as shrimp by culturing while forming fine bubbles such as microbubbles and nanobubbles in the aquaculture water. For example, in Patent Documents 1 and 2, a cavitation nozzle in which a screw member is arranged in a throttle hole is used to generate fine bubbles. Here, in the case of fish and crustaceans that take in dissolved oxygen by gill respiration, it is recognized that it is advantageous that the oxygen concentration in the aquaculture water is as high as possible. In addition, since the cavitation nozzle consumes dissolved oxygen by boiling under reduced pressure to form fine bubbles, it is considered that the oxygen concentration in the aquaculture water should be high in order to compensate for the loss of dissolved oxygen due to the floating of coarse bubbles. ..

In Patent Documents 1 and 2, air (oxygen) or ozone is mixed with aquaculture water by an aspirator, and further subjected to supersaturation pressure dissolution treatment in a tank before being guided to a cavitation nozzle. Therefore, it is considered that the oxygen concentration of the aquaculture water in the aquaculture pond is maintained at a saturated value (8 ppm), and the fine bubbles containing a large amount of oxygen generated by cavitation are the aquaculture water having a saturated oxygen concentration. In some cases, re-dissolution does not proceed easily, so it is considered that the state of bubbles is maintained until loss due to levitation. These oxygen microbubbles are expected to function as a so-called "oxygen reservoir" that supplements the consumption of dissolved oxygen by the aquaculture product.

Japanese Unexamined Patent Publication No. 2011-240206 Japanese Unexamined Patent Publication No. 2012-40448

"Analysis of Nano Bubbles in Nano Bubbles" Nanotech Japan Bulletin Vol. 8, No. 4, 2015

However, as a result of detailed examination by the present inventor, when a large amount of fine bubbles are suspended in the aquaculture water, the bubbles adhere to the gills of the aquaculture such as fish, shrimp and crab, and the uptake of dissolved oxygen is returned. It has been found that the growth of the aquaculture is rather hindered by the inhibition, and in severe cases, the aquaculture may die to a considerable extent.

The subject of the present invention is a closed-type aquaculture apparatus capable of promoting the growth of aquaculture products without problems while preventing excessive generation of fine bubbles due to cavitation treatment of aquaculture water, and onshore using the aquaculture apparatus. To provide aquaculture methods.

In order to solve the above problems, the closed land aquaculture apparatus of the present invention accommodates aquaculture water and aquaculture animals consisting of shellfish or fish in the aquaculture pond, and uses a main pump to draw the aquaculture water from the aquaculture pond. Aquaculture water in a closed land-based aquaculture system for feeding aquaculture animals by feeding them into the aquaculture pond while guiding them to a filter tank and returning the organic residue floating in the aquaculture water to the aquaculture pond for circulation. An oxygen dissolution mechanism that dissolves while supplying an oxygen-containing gas to the aquaculture water so that the oxygen concentration of the aquaculture water is maintained at 2.5 ppm or more and 7 ppm or less, and the inflow port of the aquaculture water communicates with the aquaculture pond, and the other end is aquaculture. A cavitation treatment pipe that serves as a return port for water to the aquaculture pond and a nozzle flow path that is provided in the middle of the cavitation treatment pipe and has an aquaculture water inlet at one end and an aquaculture water outlet at the other end are formed. In addition, a part of the nozzle flow path is defined as a cavitation processing unit, and a plurality of screw members are assembled to the nozzle body in the cavitation processing unit so that the tip end side of the leg protrudes inside the flow path. The aquaculture water is circulated from the aquaculture water inlet to the aquaculture water outlet, and the aquaculture water is brought into contact with the screw valley formed on the outer peripheral surface of the leg of the screw member at the cavitation treatment section while accelerating. A cavitation nozzle that performs cavitation treatment based on reduced pressure precipitation of dissolved air on the aquaculture water, and a cavitation nozzle provided in the middle of the cavitation treatment pipe, the aquaculture water is supplied to the cavitation nozzle so that the average cross-sectional flow velocity in the cavitation treatment section is 8 m / sec or more. It is characterized by being equipped with a cavitation processing pump that is distributed at a specified flow rate.

Further, the land-based aquaculture method of the present invention uses the closed-type land-based aquaculture apparatus of the present invention to accommodate aquaculture water and aquaculture animals in the aquaculture pond, and uses a main pump to transfer the aquaculture water from the aquaculture pond to a filter tank. It is characterized in that the organic residue floating in the aquaculture water is filtered, returned to the aquaculture pond and circulated, and the feed is put into the aquaculture pond to breed the aquaculture animals.

The oxygen-containing gas that can be used in the present invention is, for example, air, oxygen gas, or oxygen-enriched air obtained by concentrating oxygen with a well-known oxygen concentrator or the like, and the balance other than oxygen is composed of an inert gas such as nitrogen. It is good to do. The oxygen concentration in the oxygen-containing gas is not particularly limited as long as it corresponds to the atmospheric composition, for example, 20% by volume or more.

In the present invention, the oxygen concentration in the aquaculture water, which decreases due to consumption by the aquaculture product, is supplemented by the oxygen dissolution mechanism, and the oxygen concentration in the aquaculture water is maintained at 2.5 ppm or more and 7 ppm or less, which is less than the saturation value. Then, the cavitation treatment is performed by guiding the cultured water to the cavitation nozzle through the cavitation treatment pipe by the cavitation treatment pump and circulating it at a specified flow rate at which the average cross-sectional flow velocity in the cavitation treatment section is 8 m / sec or more. By intentionally keeping the oxygen concentration of the aquaculture water below the saturation value, excessive generation of fine bubbles due to cavitation is suppressed, and bubbles adhere to the gills of the aquaculture product, which hinders the uptake of dissolved oxygen. Can be effectively prevented.

Then, by securing a specified flow rate at which the average cross-sectional flow velocity is 8 m / sec or more in the cavitation processing section, the growth of the aquaculture product is promoted even though the oxygen concentration of the aquaculture water is set lower than that of the prior art. Etc. can be planned without any problem. If the flow velocity of the cavitation processing unit is secured within the above range, cavitation accompanied by the generation of fine bubbles can be confirmed especially at the screw valley position of the screw member. However, when the oxygen concentration of the aquaculture water is less than the saturation value as described above, bubbles generated by forced decompression supersaturation precipitation by cavitation (particularly those having a bubble diameter of 100 nm or more) pass through the nozzle. When it was returned to the aquaculture pond, redissolution proceeded rapidly, and it was found that most of the bubbles became unobservable after a few minutes by a well-known bubble size measurement method (for example, using a laser scattering particle size meter). ing.

It is clear that the use of such aquaculture water makes it difficult for fine bubbles to adhere to the gills of the aquaculture product. However, if the absolute value of the oxygen concentration in the aquaculture water is lowered, there is a concern that the activity of the aquaculture product will be significantly impaired. However, as a result of detailed studies by the present inventors, when aquaculture water in which the oxygen concentration is suppressed within the above range is cavitation-treated, it is compared with normal aquaculture water having a higher oxygen concentration (culture without cavitation treatment). It was found that the activity and growth activity of the aquaculture product were enhanced to the same extent or higher, and that the exhaustion peculiar to oxygen deficiency was hardly observed.

Although the detailed mechanism is unknown, no effective observation method has been found at this time, and ultrafine products peculiar to cavitation treatment of less than 10 nm are involved, and the penetration of dissolved oxygen-containing water into living tissues. The sex may have improved significantly. For example, the effect of improving permeability obtained by cavitation treatment of tap water or the like does not change significantly even about one day after the cavitation treatment, so that the product may be continuously present in water for a certain period of time. It is also considered to have a morphology.

Further, even when oxygen bubbles having a diameter of 100 nm or more are reduced in size due to re-dissolution, there is a high possibility that the above-mentioned products will remain in the water instead of being completely dissolved and extinguished in the end. For example, in Non-Patent Document 1, as a result of freezing nanobubble water in which outside air and water are mixed by a swirling flow and observing with an ultrahigh pressure electron microscope, a large amount of bubble-like products having an average diameter of about 7 nm are present. Has been reported. The composition of the observed product, whether or not it is a bubble, etc. are not clear, and the causal relationship with the action and effect of the present invention is unknown, but bubbles are precipitated starting from fine nucleation. In the case of cavitation-treated water, similar fine products are likely to be observed at higher densities. Even if the product is mainly composed of oxygen gas, it is presumed that the surface tension of extremely miniaturized bubbles becomes considerably high pressure, so that it is a solid compound (hide) of oxygen and water. Rate, etc.).

In any case, it has been empirically revealed that there is a significant difference in the activity and growth activity of the aquaculture product between the cavitation-treated aquaculture water and the normal aquaculture water. If the permeability of water itself, which mediates the absorption of dissolved oxygen (for example, the permeability to capillaries in the absorbing organs of dissolved oxygen such as the gills of aquatic organisms) is improved, the water has a slightly lower oxygen concentration. However, it is also speculated that the cultured product can efficiently absorb a limited amount of dissolved oxygen, and the cultured product can maintain good activity and growth activity.

If the oxygen concentration of the aquaculture water is less than 2.5 ppm, the oxygen absorption amount of the aquaculture product will be insufficient even if the improvement of the oxygen absorption efficiency by the cavitation treatment is taken into consideration, resulting in problems such as decreased activity and poor growth. It is easy to connect and increase the mortality rate of aquaculture. On the other hand, when the oxygen concentration of the aquaculture water exceeds 7 ppm, excessive generation of bubbles (particularly those having a bubble diameter of 100 nm or more) due to the cavitation treatment tends to occur, and the activity activity of the aquaculture product tends to decrease. When the aquaculture water is dissolved while supplying an oxygen-containing gas by an oxygen dissolution mechanism, the oxygen concentration of the aquaculture water is more preferably maintained at 3 ppm or more and 6 ppm or less.

If the average cross-sectional flow velocity in the cavitation treatment section is less than 8 m / sec, the effect achieved by the cavitation treatment is insufficient, and the effect of maintaining the activity of the aquaculture is remarkable even if the culture water is hypoxicized as described above. It disappears. In particular, the cross-sectional average flow velocity falls below the above lower limit when the oxygen concentration of the aquaculture water is lowered to, for example, 3.5 ppm or less due to factors such as the breeding density of the aquaculture being set high. It is especially prone to weakness and death due to lack of oxygen in the aquaculture. The average cross-sectional flow velocity in the cavitation processing section is more preferably secured at 9 m / sec or more.

The cavitation nozzle is formed so that the nozzle flow path has a circular cross section, and each cavitation processing portion has a screw pitch and a screw valley depth of 0.20 mm or more and 0.40 mm or less, and a nominal screw diameter M of 1 as a screw member. A plurality of screw members of 0.0 mm or more and 2.0 mm or less are arranged, and within 70% of the radius of the nozzle flow path from the cross-sectional center of the nozzle flow path by projection on a plane orthogonal to the central axis of the nozzle flow path. The value of 70% valley point area density is 1.6 when the total number of valley points located in the region is defined as 70% valley point area density divided by the cross-sectional area of the nozzle flow path. It is desirable to use the one secured at least ² pieces / mm.

When a cavitation nozzle with a 70% valley point area density value of less than 1.6 pieces / mm ² is used, the cavitation treatment effect is insufficient, and the effect of maintaining the activity of the aquaculture product even if the aquaculture water is hypoxicized. May not be noticeable. There is no particular upper limit to the upper limit of the value of the 70% valley point area density of the cavitation nozzle, but it can be appropriately set as long as the pressure loss increases due to the extreme increase in the number of threads arranged in the cavitation processing section and the flow velocity is not insufficient (for example). 5, 5 pieces / mm ² ). The value of the 70% valley point area density is more preferably secured at 2.0 pieces / mm ² or more.

When using a cavitation nozzle having the above configuration, the specified flow rate of aquaculture water for the cavitation nozzle is when the amount of water stored in the aquaculture pond is V1 and the flow rate of the cavitation nozzle per hour is V2.
K = V2 / V1 × 100 (%)
It is preferable to adjust so that the distribution circulation ratio K represented by is 2% or less. Even if slightly coarse bubbles of 100 nm or more are generated at the cavitation nozzle, the above-mentioned coarseness can be achieved by keeping the flow rate (specified flow rate) of the aquaculture water per hour to 2% or less of the total volume of the aquaculture water in the aquaculture pond. It is possible to promote the re-dissolution of various bubbles, and it is possible to more effectively suppress the above-mentioned problems caused by the adhesion of the cultured material to the gills and the like. And, despite the fact that the distribution circulation ratio K of the cavitation nozzle to the total volume of the aquaculture water is an extremely small value, by adopting the cavitation nozzle having the above configuration, the activity and growth activity of the aquaculture product are maintained extremely well. It becomes possible. If the distribution / circulation ratio K becomes too small, the effect of improving the activity and growth activity of the aquaculture product becomes insufficient. The lower limit of the distribution circulation ratio K varies depending on the 70% valley point area density of the cavitation nozzle and the set flow velocity, but for example, it is preferable to secure a value of 0.5% or more so as not to impair the above effect.

The oxygen dissolution mechanism can be configured to include a multiphase flow supply unit that supplies a multiphase flow of the oxygen-containing gas and the culture water to the cavitation nozzle in order to dissolve the oxygen-containing gas at the cavitation nozzle. The cavitation nozzle used in the present invention causes cavitation by squeezing in the screw valley when the aquaculture water collides with the screw member and detours downstream thereof, so that the dissolved gas component of the aquaculture water is generated. Is supersaturated by negative pressure and vigorously agitates the aquaculture water while precipitating bubbles, creating a turbulent flow area. At this time, by mixing the gas phase (gas) with the culture water supplied to the turbulent flow area to form a mixed phase flow, the gas-liquid mixing and stirring proceed by the above stirring, and the culture water of the gas phase component (oxygen-containing gas) Dissolution into the gas can be effectively promoted.

In this case, when the mixed phase flow collides with the screw member, if the entire inner space of the screw valley is covered with large bubbles, the contact efficiency between the culture water containing the dissolved gas and the screw valley decreases, and the cavitation efficiency. (That is, the thread valley loses its function as a thread valley that is effective as a cavitation point). As a result, the formation of a turbulent flow region that generates a driving force for mixing and stirring the gas phase components becomes less remarkable, leading to a decrease in gas dissolution efficiency.

Therefore, a hollow outer cylinder member having an inflow port at one end and an outflow port at the other end, and a spiral flow path provided inside the outer cylinder member and connecting the inflow port and the outflow port are formed into the spiral flow path. A flow path forming member is provided so that the spiral axis of the path is formed along the central axis of the outer cylinder member, and the spiral flow path is connected to the nozzle flow path of the cavitation nozzle on the culture water inlet side of the cavitation nozzle. The provided gas-liquid mixer can be provided, and the mixed-phase flow supply unit can be configured to supply the mixed-phase flow to the inlet of the gas-liquid mixer. As a result, the mixed-phase flow flows through the spiral flow path of the gas-liquid mixer, and the centrifugal force of the spiral flow forcibly causes stirring and mixing of the gas phase and the liquid phase, so that the gas phase has fine bubbles. It is supplied to the screw member of the cavitation nozzle in a crushed state. As a result, the contact efficiency between the aquaculture water and the screw valley is increased, and the gas dissolution efficiency can be increased.

It is desirable that the gas-liquid mixer is configured such that the screw pitch of the screw member is h (mm) and the bubbles are finely pulverized to a bubble diameter of 1.5 h or less. If the bubble diameter obtained by fine pulverization with a gas-liquid mixer exceeds 1.5 h, the effect of improving the gas dissolution efficiency may not be remarkable. The bubble diameter is more preferably 1.0 h or less. Further, although the lower limit of the bubble diameter is not limited, in the case of mixing and stirring by a gas-liquid mixer having a spiral flow path, about 0.2 h may be the limit of pulverization.

The flow path forming member of the gas-liquid mixer can be configured as a twisted plate member in which the metal plate is twisted so that the central axis in the width direction of the strip-shaped metal plate is a spiral axis. By using such a twisted plate member, a spiral flow path of a gas-liquid mixer can be easily and inexpensively formed. Further, by using the twisted plate member, the spiral flow path is formed by the first spiral flow path formed by the space between the first main surface of the twisted plate member and the cylindrical inner peripheral surface of the outer cylinder member. It can be configured to consist of a second spiral flow path formed by a space between the second main surface of the torsion plate member and the cylindrical inner peripheral surface of the outer cylinder member. As a result, two spiral flows having different rotation phases can be formed on both sides of the torsion plate member, and the pulverization efficiency of the gas phase can be further improved by a simple structure.

The total length of the outer cylinder member is preferably defined so that the spiral flow path includes a spiral section having one or more cycles. If the spiral section included in the spiral flow path is less than one cycle, the gas-liquid mixer's gas-phase pulverization efficiency may decrease, and the gas dissolution efficiency in the cavitation nozzle on the downstream side may become insufficient. The overall length of the outer cylinder member is preferably defined so that the spiral flow path includes a spiral section having 1.5 cycles or more, more preferably 2 cycles or more.

Further, the inner diameter of the cylindrical inner peripheral surface of the outer cylinder member is Dx (mm), the spiral period length of the torsion plate member is λ (mm), and the value of λ / Dx is set to 1.5 or more and 4 or less. It is good to be there. If the value of λ / Dx exceeds 4, the total length of the outer cylinder member becomes too large when securing the number of cycles of the spiral flow path required to secure the gas-phase crushing efficiency of the gas-liquid mixer. In some cases. If the value of λ / Dx is less than 1.5, the flow resistance of the spiral flow path formed by the torsion plate member becomes too large, the gas-liquid mixer's gas-phase crushing efficiency decreases, and cavitation on the downstream side occurs. The gas dissolution efficiency in the nozzle may be insufficient.

The effect of enhancing the activity and growth activity of the aquaculture product of the aquaculture water can be achieved independently of the oxygen dissolution process by passing the aquaculture water containing oxygen through the cavitation nozzle. Therefore, the oxygen dissolution mechanism is provided separately from the cavitation nozzle, and is a well-known air diffuser that injects an oxygen-containing gas supplied from the outside to the aquaculture water that fills the aquaculture pond so that the average bubble diameter is 0.5 mm or more. It can also be configured to include. Here, it is the fine bubbles of about 100 nm to 30 μm that are concerned about adverse effects due to the adhesion of the aquaculture product to the gills and the like, and the well-known air diffuser is advantageous in that such bubbles are unlikely to be generated. .. However, since the oxygen dissolution efficiency is inferior to that of the cavitation nozzle, it can be said that it is desirable to use it together with oxygen dissolution by the cavitation nozzle. When the circulation circulation ratio K of the cavitation nozzle to the total volume of aquaculture water is small as described above, it may not be possible to maintain the desired oxygen concentration only by the oxygen dissolving capacity of the cavitation nozzle. From this viewpoint as well, it is desirable to use oxygen dissolution by the air diffuser and oxygen dissolution by the cavitation nozzle together.

In this case, it is further preferable to set the supply flow rate of the oxygen-containing gas to the aquaculture water by the air diffuser to be larger than the supply flow rate of the oxygen-containing gas to the cavitation nozzle. By keeping the supply flow rate of the oxygen-containing gas to the cavitation nozzle low, the abundance density of the above-mentioned fine bubbles in the aquaculture pond can be reduced, and the adverse effect due to the adhesion of the aquaculture material to the gills and the like can be more effectively suppressed.

Next, the cavitation nozzle uses the vacuum boiling effect generated when water passes through the narrow drawing hole of the nozzle to generate fine bubbles, and in principle, the flow velocity in the drawing hole of the water to be treated is about 10 m / sec or more. It is necessary to secure the above high speed. However, when this cavitation nozzle is arranged in the circulation path with the filtration tank as described above, when the flow resistance of the culture water to the circulation path increases due to the accumulation of organic residue in the filtration tank, the culture water passing through the cavitation nozzle There is a problem that the flow velocity is insufficient and the amount of fine bubbles generated by cavitation is insufficient. In this case, even if a separate circulation path for cavitation treatment is provided, when the aquaculture water is directly sucked into the nozzle, the floating organic residue clogs the throttle hole and the generation of fine bubbles is similarly inhibited. Therefore, in order to prevent this, a new filtration part must be provided at the entrance of the circulation route on the aquaculture pond side after all, and no problem can be solved.

In order to solve this, a cavitation treatment filter unit, which is provided at the inlet of the cavitation treatment pipe and prevents floating substances in the culture pond from flowing into the cavitation treatment pipe, and a cavitation treatment pipe are provided. The flow rate of liquid sent to the cavitation nozzle by the cavitation processing pump is set to the specified flow rate by compensating for the flow rate loss due to the accumulation of suspended matter on the flow rate detection unit that detects the flow rate of the circulating culture water and the cavitation processing filtration unit. It is desirable to further add a cavitation flow control unit to control to the apparatus of the present invention. A cavitation flow rate control unit is provided to monitor the flow rate of the cavitation processing pipe in the flow rate detection unit and to supplement the flow rate of the liquid sent to the cavitation nozzle within the above specified range when suspended matter accumulates in the cavitation processing filtration unit. As a result, even when the organic residue is deposited on the filtration portion and the flow resistance is increased, the advantageous effect on the incubated material can be stably maintained.

Here, the main pump and the cavitation processing pump may have different configurations, or the main pump may also be used as the cavitation processing pump. Further, the filtration unit for cavitation treatment may be provided separately from the filtration tank, or both may be used in combination.

For example, the following configuration can be adopted. That is, in this configuration, the inlet of the culture water communicates with the filtration tank, and the other end side is provided at the inlet of the main pipe for filtration and the inlet of the main pipe for filtration as the return port of the culture water to the culture pond. , An auxiliary filtering unit for suppressing the inflow of suspended matter in the filtration tank into the main filtration pipe is provided, and the main pump is provided on the main filtration pipe. Further, the cavitation processing pipe is provided so as to branch from the filtration main pipe on the downstream side of the main pump and to open a return port to the fishpond at a position different from the filtration main pipe. Then, a distribution valve is provided that adjusts the distribution ratio between the main filtration pipe and the cavitation processing pipe according to the valve opening degree. The cavitation flow rate control unit adjusts the opening of the distribution valve so that the distribution ratio of the cultured water to the cavitation processing pipe increases when the water flow rate of the main pump decreases due to the accumulation of suspended matter in the auxiliary filtering unit. It is configured to adjust and control. In the above configuration, the main pump is used as the cavitation processing pump and the auxiliary filtering unit is also used as the cavitation processing filtering unit, which greatly simplifies the device configuration and controls the output of the main pump. Even without this, the flow rate of the cavitation processing pipe can be stably maintained within the specified range by the opening degree of the distribution valve.

The details of the action and effect of the present invention have already been described in the column of "Means for Solving the Problem" and will not be repeated here.

The conceptual diagram which shows an example of the closed type land aquaculture apparatus of this invention. A cross-sectional view and a side view showing an example of a gas-liquid mixer used in the closed land aquaculture apparatus of FIG. 1A. FIG. 1 is a cross-sectional view showing an example of a cavitation nozzle used in the closed land aquaculture apparatus of FIG. 1A. FIG. 3 is an axial sectional view showing a screw member layout on each screw arrangement surface of the cavitation nozzle of FIG. 1C. FIG. 2 is an enlarged axial sectional view showing a main part of FIG. In the cavitation nozzle of FIG. 1C, a cross-sectional view of a main part of the cavitation nozzle in which four sets of surface screws having the layout of FIG. 2 are arranged in the direction of the central axis. The cross-sectional view of the main part of the cavitation nozzle which also arranged 8 sets. FIG. 5 is a cross-sectional view of a main part showing a structure in which one of the face screw sets is rotated by 45 ° in the cavitation nozzle of FIG. 1C. FIG. 6 is a cross-sectional view of a main part of the cavitation nozzle of FIG. 1C, in which one of the face screw sets is the layout of FIG. In the structure of FIG. 7, a cross-sectional view of a main part of a cavitation nozzle in which a face screw set is divided into a pair of screw members orthogonal to each other and arranged at different positions in the central axis direction. FIG. 6 is a cross-sectional view of a main part of a cavitation nozzle in which two pairs of surface screw sets similar to the cavitation nozzle of FIG. 7 are arranged in the central axis direction. A cross-sectional view showing a state in which a Venturi ejector is connected to a gas-liquid mixer of the closed land aquaculture apparatus of FIG. 1A. The block diagram which shows an example of the electric structure of the cavitation flow rate control part. The flowchart which shows the processing flow of the flow rate control program. The flowchart which shows the processing flow of an oxygen concentration control program. A cross-sectional view of a main part of a 2-hole type cavitation nozzle. The figure explaining the dimensional relationship of each part of the cavitation nozzle used in the experimental example. The schematic diagram which shows the modification of the distribution valve. FIG. 6 is a conceptual diagram showing a modified example of the closed land aquaculture apparatus of FIG. 1A.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1A is a conceptual diagram showing an example of a closed land aquaculture device according to an embodiment of the present invention together with a usage pattern. The closed aquaculture device 300 accommodates the aquaculture water W and the aquaculture SP composed of shellfish or fish in the aquaculture pond 250, and uses the main pump 175 to transfer the aquaculture water W from the aquaculture pond 250 to the filter tank 252. The purpose is to feed the aquaculture SP by feeding the feed into the aquaculture pond 250 while filtering the organic residue floating in the aquaculture water W and returning it to the aquaculture pond 250 for circulation.

The aquaculture SP is a shrimp in this embodiment, but may be another crustacean such as a crab. In addition to crustaceans, fish such as red sea bream, tuna, yellowtail, trout, salmon, blowfish and carp may be used. In addition, the type of shrimp when the cultured product SP is a shrimp is, for example, a shrimp belonging to the family Penaeid shrimps, from Penaeid shrimps, Banamei shrimp, Giant tiger prawn (commonly known as black tiger prawn), Penaeus semisulcatus and Chinese white shrimp (commonly known as Taisho shrimp). It is the one to be selected. The aquaculture water W is selected from seawater (salinity: 3.0 to 4.0% by mass), brackish water (salinity: 0.05 to 3.0% by mass) and fresh water, depending on the type of aquaculture. It is selected as appropriate.

The closed land aquaculture apparatus 300 is provided with an oxygen dissolution mechanism that dissolves the aquaculture water W while supplying an oxygen-containing gas so that the oxygen concentration of the aquaculture water W is maintained at 2.5 ppm or more and 7 ppm or less (described later). .. It also has the following components.
Cavitation treatment pipe 181: The inflow port of the aquaculture water W communicates with the aquaculture pond 250, and the other end side serves as a return port of the aquaculture water W to the aquaculture pond 250.
-Cavitation nozzle 1: The structure will be described in detail later.
-Cavitation processing pump: In this embodiment, the main pump 175 is also used. It is provided in the middle of the cavitation treatment pipe 181 (a part of the inflow port side of the main filtration pipe 180 is also used as the cavitation treatment pipe), and the culture water W is applied to the cavitation nozzle 1 in the cross section of the cavitation treatment section. It is circulated at a specified flow rate having an average flow rate of 8 m / sec or more.
-Cavitation processing filtration unit: The auxiliary filtering unit 253f corresponds to this, and is provided at the inflow port of the main filtration pipe (cavitation processing pipe) 180, and the suspended matter in the culture pond 250 is inside the cavitation processing pipe 181. Suppress inflow.
-Flow rate detection unit 182: It is composed of an ultrasonic flow meter or the like, and detects the flow rate of the culture water W flowing in the cavitation processing pipe 181 on the downstream side of the cavitation nozzle 1, for example. Control unit 185 (cavitation flow rate control unit): The flow rate of liquid sent to the cavitation nozzle 1 by the cavitation processing pump 181p is set to the above-mentioned specified flow rate in a form of compensating for the flow rate loss due to the accumulation of suspended matter on the cavitation processing filtration unit 253f. To control.

Specifically, in the present embodiment, a filtration main pipe 180 is provided in which the inflow port of the aquaculture water W communicates with the filtration tank 252 and the other end side serves as a return port of the aquaculture water W to the aquaculture pond 250. In addition, an auxiliary filtering unit 253f made of a metal net or the like is provided at the inflow port of the main filtration pipe 180 to prevent suspended matter in the filtration tank 252 from flowing into the main filtration pipe 180. There is. Further, the main pump 175 is provided on the main filtration pipe 180. On the other hand, the cavitation processing pipe 181 branches from the filtration main pipe 180 on the downstream side of the main pump 175, and opens a return port to the fishpond 250 at a position different from the filtration main pipe 180. Provided.

Further, the closed type land aquaculture apparatus 300 is provided with a distribution valve 183 that adjusts the distribution ratio between the main filtration pipe 180 and the cavitation processing pipe 181 according to the valve opening degree. In the present embodiment, the distribution valve 183 is configured as a proportional control type electromagnetic three-way valve provided at a branch point between the main filtration pipe 180 and the cavitation processing pipe 181. As shown in FIG. 16, the distribution valve 183 is branched. It may be configured as a pair of proportional control valves 183A and 183B individually provided in the main piping 180 for filtration and the piping 181 for cavitation processing on the downstream side of the point. The cavitation flow rate control unit 185 distributes the culture water W to the cavitation treatment pipe 181 so as to increase when the water supply flow rate of the main pump 175 decreases due to the accumulation of suspended matter on the auxiliary filtering unit 253f. The opening degree of the valve 183 is adjusted and driven. In the above configuration, the main pump 175 is also used as the cavitation processing pump, and the auxiliary filtering unit 253f is also used as the cavitation processing filtering unit.

In the aquaculture water discharged from the outlet pipe 250e of the aquaculture pond 250, coarse suspended matter is settled and removed in the settling tank 251 and the aquaculture water W overflowing from the settling tank 251 is guided to the filtration tank 252. A filter 252f made of a non-woven fabric, a porous resin, or the like is arranged in the filtration tank 252, and the aquaculture water W that has passed through the filter 252f flows down from the filtration tank 252 to the buffer layer 253. In the filter tank 252, a breeding medium layer of aerobic microorganisms (for example, porous ceramic) can be interposed in the filter 252f, and it can be configured as a biofilter for decomposing organic suspended matter. On the other hand, the inlet side end of the main filtration pipe 180 is immersed in the buffer layer 253, and the opening is covered by the auxiliary filtering portion 253f composed of a metal net or the like. With the long-term use of the fishpond 250, suspended matter that could not be completely removed by the filter 252f flows into the buffer layer 253 from the filtration tank 252. The suspended matter is separated by the auxiliary filtering unit 253f and is prevented from entering the main filtering pipe 180.

Next, the cavitation processing pipe 181 is provided with a mixed phase flow supply unit 165, a gas-liquid mixer 150, and a cavitation nozzle 1 in this order from the upstream side. The culture water W is mixed with air as an oxygen-containing gas from the gas supply source 170 through the gas supply pipe 171 at the mixed phase flow supply unit 165, and the air introduced by the gas-liquid mixer 150 is further pulverized. , At least a part of the gas is dissolved by the cavitation nozzle 1 and returned to the culture water pond 250. The gas-liquid mixer 150 cooperates with the cavitation nozzle 1 to form a part of the oxygen dissolution mechanism.

FIG. 1B shows a configuration example of the gas-liquid mixer 150. The gas-liquid mixer 150 includes an outer cylinder member 151 and a flow path forming member 155. The outer cylinder member 151 is formed in a hollow cylindrical shape having an inflow port 159 at one end and an outflow port 160 at the other end. The material is, for example, metal or plastic such as polyvinyl chloride, and stainless steel is used in this embodiment. Joints for connecting to other piping elements, and male threaded portions 152 in this embodiment are formed at both ends of the outer cylinder member 151.

On the other hand, the flow path forming member 155 is provided inside the outer cylinder member 151, and the spiral flow paths 157 and 158 connecting the inflow port 159 and the outflow port 160 are provided with the spiral axis HC of the spiral flow path 157 and 158. It is formed along the central axis of the outer cylinder member 151. In the present embodiment, the flow path forming member 155 is a twisted plate member (hereinafter, also referred to as a twisted plate member 155) obtained by twisting the metal plate so that the central axis O in the width direction of the strip-shaped metal plate is the spiral axis HC. Can be configured as. As the material of the flow path forming member 155, for example, stainless steel (SUS316, etc.) can be adopted, but when seawater or brackish water is used, it may be composed of a metal having better corrosion resistance to seawater, such as titanium or a titanium alloy. More desirable.

Inside the outer cylinder member 151, the twisted plate member 155 has a first spiral flow path 157 between the first main surface of the twisted plate member 155 and the inner peripheral surface of the outer cylinder member 151, and also the second main surface. A second spiral flow path 158 is formed between the surface and the inner peripheral surface of the outer cylinder member 151. The total length of the outer cylinder member 151 is determined so that the spiral flow path includes a spiral section 156 having one or more cycles and two cycles in the present embodiment. Further, the inner diameter of the cylindrical inner peripheral surface of the outer cylinder member 151 is Dx (mm), the spiral period length of the torsion plate member 155 is λ (mm), and the value of λ / Dx is set to 1.5 or more and 4 or less. Has been done. Dx is, for example, 5 mm or more and 30 mm or less (for example, 15 mm), and the value of λ is, for example, 20 mm or more and 300 mm or less (for example, 50 mm). Further, the thickness of the plate material constituting the twisted plate member 155 is selected within a range not exceeding 1/4 of Dx, for example, in a range of 0.3 mm or more and 4 mm or less (for example, 1 mm).

Further, in the present embodiment, as an oxygen dissolution mechanism, an oxygen-containing gas supplied from the outside to the aquaculture water W which is provided separately from the cavitation nozzle 1 and fills the aquaculture pond 250 has an average cell diameter of 0.5 mm or more. An air diffuser 174 is provided in the aquaculture pond 250. The air diffuser 174 has a well-known configuration such as an air diffuser having a large number of pores or a ceramic, a resin or metal air diffuser having a large number of continuous ventilation holes, or a swirling flow type gas-liquid mixing type diffuser. Therefore, air as an oxygen-containing gas is supplied from the air compressor 170 via the gas supply pipe 173.

Solenoid valves 172 and 184 are provided in the gas supply pipe 171 toward the cavitation nozzle 1 (multiphase flow supply unit 165) and the gas supply pipe 173 toward the air diffuser 174, respectively, and receive control signals from the control unit 185. Is driven to open and close. When the solenoid valves 172 and 184 are opened, air is supplied to the cavitation nozzle 1 and the air diffuser 174, that is, oxygen is dissolved in the aquaculture water. When the solenoid valves 172 and 184 are closed, air is supplied, that is, oxygen is dissolved in the aquaculture water. Processing stops. An oxygen sensor 186 (which is a well-known optical or polarograph type) is provided in the aquaculture pond 250, and the control unit 185 reads the oxygen concentration of the aquaculture water by the oxygen sensor 186 and the oxygen. The solenoid valves 172 and 184 are controlled to open and close so that the concentration is 2.5 ppm or more and 7 ppm or less (preferably 3 ppm or more and 6 ppm or less). In this embodiment, the air supply flow rate to the air diffuser 174 is set to be larger than the air supply flow rate in the cavitation nozzle 1.

Next, FIG. 1C is a cross-sectional view showing an example of the cavitation nozzle 1. The cavitation nozzle 1 includes a nozzle body 2 in which a nozzle flow path 3 is formed. The nozzle body 2 is formed in a cylindrical shape, and one nozzle flow path 3 having a circular cross section is formed through the nozzle body 2 in the direction of the central axis O. The nozzle flow path 3 has a aquaculture water inlet 4 at one end (on the right side of the drawing) and a aquaculture water outlet 5 at the other end, and from the aquaculture water inlet 4 and the aquaculture water outlet 5 at an intermediate position in the flow direction. The small diameter drawing hole 9 is formed so as to form a part of the nozzle flow path 3. The nozzle flow path 3 has an inflow chamber 6 on the aquaculture water inlet 4 side and an outflow chamber 7 on the aquaculture water outlet 5 side of the throttle hole 9. Then, a screw member 10 is assembled in the throttle hole 9 so that the tip end side of the leg portion protrudes inside the flow path to form a cavitation processing portion CV.

The material of the nozzle body 2 is, for example, a resin such as ABS, nylon, polycarbonate, polyacetal, polyvinyl chloride, or PTFE, but is composed of a metal such as titanium or titanium alloy or stainless steel, and ceramics such as alumina. The material of the screw member 10 is, for example, stainless steel such as SUS316, but when seawater or brackish water is used, it is more desirable to use a metal having better corrosion resistance to seawater such as titanium or a titanium alloy. It is also possible to use a ceramic material such as quartz or alumina.

As the screw member 10, a screw member 10 having a screw pitch and a screw valley depth of 0.20 mm or more and 0.40 mm or less and a nominal screw diameter M of 1.0 mm or more and 2.0 mm or less is used. In the present embodiment, as the screw member 10, the No. 0 type 1 pan head machine screw defined in JIS is used. The cavitation processing unit CV is provided with a plurality of virtual screw arrangement surfaces orthogonal to the central axis O of the nozzle flow path 3 along the central axis O, and two surfaces LP1 and LP2 in FIG. 1C. The screw member 10 is arranged so that the longitudinal direction of the leg portion is along the individual screw arrangement surfaces LP1 and LP2. In the embodiment of FIG. 1C, the total number of screw members 10 is 8 (the number may exceed 8 as described later), 2 or more for each screw arrangement surface LP1 and LP2, and 4 in FIG. 1C. It is distributed one by one. It is also possible to form only one screw arrangement surface (face screw set).

In FIG. 1C, the screw members 10 are arranged on the screw arrangement surfaces LP1 and LP2 according to the layout shown in FIG. Specifically, the four screw members 10 on the screw arrangement surfaces LP1 and LP2 are arranged in a cross shape orthogonal to each other, and each of them is formed at a female thread portion on the inner surface of the screw hole 19 formed in the nozzle body 2. The tip of the leg is screwed so as to protrude into the throttle hole 9 from the outer peripheral surface side of the wall portion. The screw hole 19 and the screw member 10 can be set and fixed with an adhesive or the like. FIG. 3 shows a further enlarged view of the inside of the throttle hole 9, and a main distribution region 21 is formed between the screw member 10 and the inner peripheral surface of the throttle hole 9. Further, in each throttle hole 9, a distribution gap 15 is formed at the center position of the cross formed by the four collision portions 10. The tip surfaces of the four collision portions 10 forming the flow gap 15 (FIG. 3) are formed flat, and the flow gap 15 is formed in a square shape in the above projection.

In FIG. 3, the area of the cultured water flow area (cross-sectional area of the nozzle flow path in the cavitation processing section: hereinafter also referred to as the total flow-through cross-sectional area) a on each of the screw arrangement surfaces LP1 and LP2 is outside the projection area of the nozzle flow path. (here, the area of the circular shaft cross-section of the throttle bore 9 in Figure 1C: [pi] d ^2/4 internal diameter as d) the total area of the peripheral edge inside) the S1, the projected area area of the collision portion 10 (four screws member) As S2
a = S1-S2 (Unit: mm ² )
Defined as. In this embodiment, the total area of the main distribution area 21 and the distribution gap 15 corresponds to the total distribution cross-sectional area a. As shown in FIG. 1C, the opening diameters of the aquaculture water inlet 4 and the aquaculture water outlet 5 are larger than the inner diameter of the throttle hole 9. That is, the opening cross-sectional areas of the aquaculture water inlet 4 and the aquaculture water outlet 5 are set to be larger than the total distribution cross-sectional area a. Further, the inner peripheral surfaces of the inflow chamber 6 and the outflow chamber 7 connected to the throttle holes 9 are tapered portions 13 and 14, respectively. The tapered portion 14 on the aquaculture water outlet 5 side and the tapered portion 13 on the aquaculture water inlet 4 side have the same drawing ratio, but the section length is set larger in the tapered portion 14. Then, on each of the screw arrangement surfaces LP1 and LP2, the total circulation cross-sectional area a is secured at 3.8 mm ² or more, and the ratio of the total flow cross-sectional area a to the total cross-sectional area S1 of the nozzle flow path (that is, a / S1 × 100). The in-plane distribution area ratio defined as (%)) is secured at 40% or more.

The depth h of the valley portion 21 appearing on the projected outline of the screw member (collision portion) 10 is secured at 0.2 mm or more. Further, when a circle drawn with a radius corresponding to 70% of the distance to the inner peripheral edge of the nozzle flow path centered on the projection point of the central axis O is defined as the reference circle C ₇₀ , the bottom position of the valley portion 21 is set. Of the valley points represented, the number of valley points located inside the reference circle C ₇₀ (indicated by a circle), that is, projected onto a plane orthogonal to the central axis O from the center of the cross section of the nozzle flow path 3 to the nozzle flow path. The number of valley points located within 70% of the radius of 3 is defined as 70% valley point number N ₇₀ . Then, the value obtained by dividing the value obtained by dividing the value of the 70% number of valley points N ₇₀ for all the screw arrangement surfaces by the cross-sectional area S1 of the nozzle flow path 3 (throttle hole 9) is defined as the 70% valley point area density. In the cavitation nozzle 1 of FIG. 1C, the value of the 70% valley point area density is secured at 1.6 pieces / mm ² or more.

In FIG. 1C, the legs of the screw member 10 between the screw arrangement surfaces LP1 and LP2 adjacent to each other are arranged in a positional relationship in which they overlap each other while matching the longitudinal directions in projection onto a plane orthogonal to the central axis O. There is. Specifically, the surface screw set consisting of four screw members 10 arranged in a cross shape overlaps each other between the screw arrangement surfaces LP1 and LP2 (that is, the central axis O of the cross-shaped face screw set). Peripheral arrangement angle Positional relationship in which the phases match each other: Hereinafter, such an arrangement is referred to as "in-phase arrangement"). Further, the distance dp between the adjacent screw arrangement surfaces LP1 and LP2 is set to, for example, 1.05 dh or more and 2 M or less, where the outer diameter of the screw head 10h in FIG. 2 is dh and the nominal screw diameter of the screw leg portion 10f is M. Has been done.

For the cavitation nozzle 1 of FIG. 1C, for example, water is used as the aquaculture water so that the aquaculture water outlet 5 side is opened and the dynamic pressure at the aquaculture water inlet 4 is about the normal tap pressure (for example, 0.077 MPa). The operation when it is distributed will be described. The water flow is first throttled by the tapered portion 13 and the throttle hole 9, and is formed in the liquid flow region including the main flow region 21 and the flow gap 15 of FIG. 2 formed between the screw member 10 and the inner peripheral surface of the throttle hole 9. It passes through the screw member 10 while colliding with it.

Then, when passing through the outer peripheral surface of the screw member 10, a high-speed region is formed in the thread valley portion and a low-speed region is formed in the screw thread portion. Then, the high-speed region of the screw valley portion becomes a negative pressure region according to Bernoulli's theorem, and cavitation occurs. Since a plurality of screw valleys are formed on the outer periphery of the screw member and eight or more screw members 10 are distributed and arranged on the plurality of screw arrangement surfaces LP1 and LP2, the cavitation is formed in the valley in the throttle hole 9. It will occur at the same time. Then, when the water flow collides with the screw member 10, decompression precipitation of the dissolved air at the screw valley portion occurs violently in a boiling manner, and the water flow violently rubs between the surface of the screw member 10 and the inner surface of the nozzle flow path 3. Stir while doing.

As described above, in the cavitation nozzle 1 of FIG. 1C, the in-plane distribution area ratio is secured at 40% or more, the total distribution cross-sectional area is secured at 3.8 mm ² or more on each screw arrangement surface LP1 and LP2, and further. The distance dp between the adjacent screw arrangement surfaces LP1 and LP2 (face screw set) is secured to be larger than the nominal screw diameter of the screw member 10 used. As a result, even if a plurality of face screw sets are arranged in a row in the direction of the flow path center axis O, the increase in pressure loss of the nozzle can be kept extremely small. As a result, it becomes possible to sufficiently secure the required flow velocity in the cross section even though many screw members are arranged in one nozzle flow path 3. This configuration is particularly advantageous when a large flow rate nozzle with increased efficiency in cavitation processing is desired.

As shown in FIG. 10, the gas-liquid mixer 150 is arranged on the culture water inlet side of the cavitation nozzle 1 so that the spiral flow paths 157 and 158 communicate with the nozzle flow path 3 of the cavitation nozzle 1. Specifically, the threaded portion 152 on the outlet side of the outer cylinder member 151 is screwed into the female threaded portion 16 of the nozzle body 2. A separate piping element (not shown) such as a relay pipe may be interposed between the gas-liquid mixer 150 and the cavitation nozzle 1, but the secondary bubble BS is united while flowing through the separate pipe element. -There is a concern that the gas-liquid mixer 150 and the cavitation nozzle 1 are directly connected as shown in FIG.

Further, the multiphase flow supply unit 165 supplies a mixed phase flow of gas and aquaculture water to the inflow port 159 of the gas-liquid mixer 150. In the present embodiment, the mixed-phase flow supply unit 165 is configured as a venturi ejector, and gas is supplied to the gas supply hole 166 communicating with the throttle hole via the gas introduction joint 167 through the gas supply pipe 171 (FIG. 1A) to mix the phases. A stream is formed. In the present embodiment, the multiphase flow supply unit 165 is also directly connected to the inflow port 159 side of the gas-liquid mixer 150. The mixed phase flow is distributed to the first spiral flow path 157 and the second spiral flow path 158, and the gas phase is pulverized into the secondary bubble BS while forming the first spiral flow TR1 and the second spiral flow TR2, respectively.

The primary bubble BP in the mixed phase flow is mixed and finely pulverized with the aquaculture water by centrifugal force by circulating in the spiral flow paths 157 and 158 of the gas-liquid mixer 150, and the screw member 10 of the cavitation nozzle 1 in FIG. 1C. The screw pitch is h (mm), and the particles are finely pulverized into secondary bubble BS having a bubble diameter of 1.5 h or less (preferably 1 h or less). The aquaculture water containing the secondary bubble BS is supplied to the cavitation nozzle 1 and is dissolved by being caught in the turbulent flow area generated in the cavitation processing unit CV.

By supplying the gas phase in the mixed phase flow to the screw member of the cavitation nozzle 1 in a state of being crushed into finer secondary bubble BS, the contact efficiency between the gas-containing aquaculture water and the screw valley is increased. As a result, the formation of a turbulent flow region that generates a driving force for mixing and stirring the gas phase components becomes remarkable, and the gas dissolution efficiency can be improved. Further, in the cavitation processing section CV, a part of the dissolved gas is immediately reprecipitated by cavitation, so that the cavitation efficiency in the thread valley portion is significantly improved.

Next, FIG. 11 is a block diagram showing an example of the electrical configuration of the control unit 185. The control unit 185 includes a CPU 191 and a ROM 193 that stores a control program (nozzle flow control program 193a and oxygen concentration control program 193b) executed by the CPU 191, a RAM 192 that forms a program execution memory, an input / output unit 194, and the like. It is mainly composed of microcomputer hardware including a bus line 195 to be connected. The above-mentioned distribution valve 183 is connected to the input / output unit 194 via a D / A conversion unit 199 that converts a digital signal indicating an indicated value of a valve opening degree (valve position) into an analog voltage indicated value. Further, the analog sensor outputs of the flow meter 186 and the oxygen sensor 186 are converted into digital signals by the A / D conversion units 196 and 197 and input to the input / output units 194. Further, the solenoid valves 172 and 184 that open and close the supply of air to the air diffuser nozzle 174 and the cavitation nozzle 1 are connected to the input / output unit 194 via the drive circuits 172A and 184A.

Hereinafter, the operation of the closed aquaculture apparatus 300 of FIG. 1A will be described.
First, the aquaculture water W is injected into the aquaculture pond 250. For the control unit 185 of FIG. 11, a specified flow rate range (upper limit value Q) in which the average cross-sectional flow velocity of the aquaculture water W is 8 m / sec or more, preferably 9 m / or more, according to the value of the distribution cross-sectional area of the cavitation nozzle 1. _U, is set with the lower limit _{Q L)} input unit 198 a. Further, the specified oxygen concentration range (upper limit value _CU , lower limit value _CL ) of the aquaculture water W is similarly set by using the input unit 198 according to the number of individuals of the aquaculture SP to be input. These set values are stored in the RAM 192 of FIG.

When the above settings are completed, the operation of the main pump 175 and the control of the flow rate of the cavitation nozzle 1 and the oxygen dissolution in the aquaculture water W by the control unit 185 are started. Then, the flow rate of the cavitation nozzle 1 indicated by the flow meter 182 and the oxygen concentration indicated by the oxygen sensor 186 are controlled within a specified range, and when these values are stable, the aquaculture SP is charged into the aquaculture water W. ..

FIG. 12 is a flowchart showing an example of the processing flow of the flow rate control program. In S101, the opening degree S of the distribution valve 183 in FIG. 1A is set to the default value S0. The default value indicates, for example, that the flow rate of the cavitation nozzle 1 indicates the center value of the specified flow rate range when the auxiliary filtering unit 253f of FIG. 1A is in a new state and the main pump 175 is rotationally driven at the rated output. Can be set as. In S102, the flow rate value Q2 of the flow meter 182 is read. Then compared with the lower limit Q _L and an upper limit Q _U prescribed flow rate range the flow rate value Q2. Since Q2 _{<Q L} if the flow rate in S103 is insufficient proceeds to S104, driving the dispensing valve 183 such that the opening degree S is increased by a predetermined increment ΔS cavitation process pipe 181 side. In the remaining case, the process proceeds to S105, and if Q _U <Q2, the flow rate is excessive. Therefore, in S106, the distribution valve 183 is driven so that the opening degree S is incremented by ΔS toward the cavitation processing pipe 181 side. Then, when Q _L <Q2 <Q _U , the flow rate is appropriate, and the process proceeds to S107 to maintain the current value of the opening degree S of the distribution valve 183. After that, if it is not completed in S108, the process returns to S101 and the following processing is repeated. The upper limit of the flow rate _QU is when the amount of water stored in the pond 250 is V1 and the flow rate of the cavitation nozzle 1 per hour is V2.
K = V2 / V1 × 100 (%)
The distribution circulation ratio K represented by is set so as not to exceed, for example, 2%.

FIG. 13 is a flowchart showing an example of the processing flow of the oxygen concentration control program. In S201, as the default setting state, the solenoid valve 184 on the air diffuser 174 side of FIG. 1A is turned ON (open), and the solenoid valve 172 on the cavitation nozzle 1 side is also turned ON (open). In S202, the oxygen concentration detection value C of the oxygen sensor 186 is read. Then, comparing the oxygen concentration detection value C and the lower limit value C _L and an upper limit C _U prescribed oxygen concentration range. S103 it with the C _{<C L} if the oxygen concentration is insufficient proceeds to S204, the electromagnetic valve 184 of the diffuser portion 174 side is ON (open), cavitation nozzle 1 side of the solenoid valve 172 is also ON (open) Maintain the state of. Go to that case remaining in _S205, since excessive _C U <C if the oxygen concentration, the electromagnetic valve 184 of the diffuser portion 174 side in S206 is set to ON (open), the electromagnetic valve 172 of the cavitation nozzle 1 side OFF As (closed), oxygen dissolution in the cavitation nozzle 1 is suppressed, and the oxygen concentration in the culture water W is lowered. If it is desired to further reduce the oxygen concentration, it is possible to perform a process of turning off (closing) the solenoid valve 184 on the air diffuser 174 side. When C _L <C2 <Q _U , the oxygen concentration is appropriate, and the process proceeds to S207 to turn on (open) the solenoid valve 184 on the air diffuser 174 side, and the solenoid valve 172 on the cavitation nozzle 1 side is intermittent. To maintain the current oxygen concentration value. After that, if it is not completed in S208, the process returns to S201 and the following processing is repeated. Oxygen concentration C in aquaculture water W is fixedly defined within the 4~6ppm central target value C0 for example (e.g. 5 ppm), the upper limit _{C U} example, based on the said center target value C0 is C0 + 0.5~C0 + 2ppm of the value (e.g. 6 ppm), the lower limit _{C L} can be set as the value of the central target value criterion, for example C0-0.5~C0-2ppm the C0 (e.g., 4 ppm).

The oxygen concentration in the aquaculture water W, which decreases due to consumption by the aquaculture SP, is less than the saturation value due to the above control, even if the fluctuation of the oxygen concentration due to a sudden factor is taken into consideration. It will be maintained in the range of 2.5 ppm or more and 7 ppm or less (preferably 3 ppm or more and 8 ppm or less). Then, the cavitation treatment is performed by guiding the cultured water W to the cavitation nozzle 1 and circulating it at a predetermined flow rate at which the average cross-sectional flow velocity in the cavitation treatment unit is 8 m / sec or more. By intentionally keeping the oxygen concentration of the cultured water W below the saturation value, excessive generation of fine bubbles due to cavitation is suppressed, and bubbles adhere to the gills of the cultured product SP to inhibit the uptake of dissolved oxygen. Problems can be effectively prevented. By ensuring a specified flow rate at which the average cross-sectional flow velocity in the cavitation treatment section is 8 m / sec or more, the oxygen concentration of the cultured water W is set lower than that of the prior art, but the cultured product SP Growth promotion can be promoted without any problem.

Hereinafter, various modifications of the cavitation nozzle that can be adopted in the present invention will be described.
FIG. 4 shows a configuration in which four sets of cavitation processing units CV of the cavitation nozzle 1 of FIG. 1C are arranged in the direction of the central axis O with four sets of face screws having the layout shown in FIG. Specifically, the four screw arrangement surfaces LP1 to LP4 are arranged in the direction of the central axis O at the same surface spacing dp as in FIG. 1C, so that the cross-shaped surface screw sets in FIG. 2 overlap each other (that is,). (In phase). In this case, the 16 screw members 10 are distributed to the four screw arrangement surfaces LP1 to LP4. Further, FIG. 5 shows an example of a cavitation processing unit CV in which the surface screw set of FIG. 2 is arranged in phase with the eight screw arrangement surfaces LP1 to LP8. In this case, the 32 screw members 10 are distributed to the eight screw arrangement surfaces LP1 to LP8. The 70% valley point area density of each cavitation processing unit CV can be increased twice in the configuration shown in FIG. 4 and four times in the configuration shown in FIG. 5 as compared with the configuration shown in FIG. As a result, the efficiency of the cavitation treatment is improved, and the above-mentioned effects of the present invention can be achieved more stably.

Next, FIG. 6 shows a state in which a surface screw set similar to that of the cavitation nozzle 1 of FIG. 1C is rotated by 45 °. Then, of the two screw arrangement surfaces LP1 and LP2 of the cavitation nozzle 1 of FIG. 1C, the cross-shaped surface screw set of one screw arrangement surface LP2 is centered with respect to the surface screw set of the other screw arrangement surface LP1. FIG. 7 shows an example of the cavitation processing unit CV in the case where the cavitation processing unit CV is rotated around O by 45 ° to be in the state shown in FIG. The cavitation processing unit CV having the same configuration can achieve 70% valley point area density equivalent to that of FIG. 2, but when the surface spacing dp of the screw arrangement surfaces LP1 and LP2 is the same as the configuration of FIG. 1C, the aquaculture water The pressure loss during distribution will be slightly larger. However, the pressure loss is reduced by appropriately expanding the surface spacing dp, and the cavitation processing capacity is substantially the same as that of the cavitation processing unit CV having the configuration shown in FIG. Further, since the turbulent agitation effect of the aquaculture water is larger than that of FIG. 1C, it is more advantageous for the purpose of dissolving the gas in the aquaculture water by the mixed phase flow supply.

FIG. 8 shows an example of a cavitation processing unit CV in which a face screw set is divided into a pair of screw members orthogonal to each other and arranged so as to be displaced in the direction of the central axis O in the configuration of FIG. Specifically, in the configuration of FIG. 7, the four screw members 10 arranged on the screw arrangement surfaces LP1 and LP2 in FIG. 1C are separated by the nominal screw diameter M of the screw member 10. Two screws orthogonal to each other are dispersed and arranged on the arrangement surfaces LP1, LP1'and LP2, LP2'. That is, it shows an example in which eight screw members 10 are distributed to four screw arrangement surfaces LP1, LP1', LP2, LP2'. Further, the distance between the screw arrangement surface LP1'and the screw arrangement surface LP2 is set to be larger than the nominal screw diameter M (for example, about 1.5M to 2.0M). The 70% valley point area density in this configuration is equivalent to that in FIG.

Further, FIG. 9 shows a cavitation process in which the surface screw set of the layout of FIG. 2 and the surface screw set of the layout of FIG. 6 are alternately arranged on the four screw arrangement surfaces LP1 to LP4, for a total of four sets. An example of the part CV is shown. In this example, 16 screw members 10 are distributed and arranged on each of the four screw arrangement surfaces LP1 to LP4. The 70% valley point area density in this configuration is twice that of the configuration of FIG.

FIG. 14 shows an example of a cavitation nozzle in which two drawing holes 9 are formed in a partition wall portion 8 formed in a cavitation processing section, and four screw members 10 are arranged in a cross shape for each drawing hole 9.

Further, as shown in FIG. 17, the closed type aquaculture apparatus 300 may be configured to provide the cavitation processing pipe 182 and the cavitation processing pump 181p independently of the filtration main pipe 180 and the main pump 175. .. The entrance of the cavitation processing pipe 182 is opened in the aquaculture pond 250, and the cavitation processing filtering unit 181f having the same configuration as the auxiliary filtering unit 253f is provided. The drive input of the cavitation processing pump 181p is made variable by the power supply amplifier 181v, and the output of the power supply amplifier 181v is controlled by the signal from the control unit 185 so that the liquid feed flow rate to the cavitation nozzle 1 becomes the above-mentioned specified flow rate. Maintained in range. Since the remaining configuration is the same as that in FIG. 1, detailed description will be omitted.

The results of various experiments conducted to confirm the effect of the cavitation nozzle will be described below.
(Example 1)
As the cavitation nozzles A and B, those having the shape shown in FIG. 1C were prepared. For the cavitation nozzle A, only one face screw set consisting of the four screws shown in FIG. 2 is arranged, and for the cavitation nozzle B, two face screw sets are arranged so as to overlap each other. FIG. 21 illustrates the dimensional relationship of each part of FIG. 1C. The material of the nozzle body 2 is ABS resin, the inner diameters of the aquaculture water inlet 4 and the aquaculture water outlet 5 are φ20 mm, and the lengths of the inflow chamber 6 and the outflow chamber 7 in the flow direction are 15 mm and 45 mm, respectively. The length of the throttle hole 9 in the cavitation processing section is 12 mm. The inner diameter D of the diaphragm hole 9 was set to φ5.0 mm for the cavitation nozzle A and φ14.0 mm for the cavitation nozzle B. The threaded member adopted is a No. 1 type pan head machine screw having a metric coarse pitch specified in JIS: B0205 (1997), and the material is titanium. The nominal screw diameter of the leg is M1.4 mm.

In addition, the total circulation cross-sectional area a (value obtained by subtracting the area occupied by the screw from the total cross-sectional area of the drawing hole) was calculated on the projected image showing the layout of the screw member in the drawing hole. Furthermore, by counting the 70% valley points residing inside the reference circle C ₇₀ of FIG. 3, by dividing the aperture total cross-sectional area S1 of the hole was calculated for each test nozzle the value of 70% valley dot area densities. For each of the created nozzles A and B, each value of the inner diameter of the throttle hole, the total number of 70% valley points in the in-plane distribution cross-sectional area, the 70% valley point area density, and the distribution circulation ratio K when the total amount of water in the pond is 50 tons. Are summarized in Table 1. The above-mentioned cavitation nozzle, which has a 70% valley point density of 2.0 pieces / mm ² or more for each nozzle, was incorporated into the closed land aquaculture apparatus 300 of FIG. 1A together with the gas-liquid mixer 150 of FIG.

Next, 50 tons (water depth: about 1.5 m) of artificial seawater adjusted so that the salt concentration becomes a brackish water area of 2.0% is injected into the aquaculture pond 250, and the circulation by the main pump 175 is performed at an initial flow rate of 100 L / min. It started at. Then, the opening degree of the distribution valve 183 was controlled by the method already described in detail so that the flow rates of the nozzles A and B were set as shown in Table 1. In addition, the oxygen concentration, which is the control target of the aquaculture water, is set according to the conditions (2.0 ppm to 7.5 ppm, No. 1 (2.0 ppm) and No. 6 (7.5 ppm)) shown in Table 2 below. (Comparative example) was set, and the solenoid valves 184 and 174 of FIG. 1A were driven and controlled to maintain the oxygen concentration of the aquaculture water at each set value. The air ejection flow rate of the air diffuser 174 was set to 50 NL / min (average cell diameter: 0.3 mm). The air supply flow rate to the cavitation nozzle 1 was adjusted so as to be 10% of the water flow rate at the volume flow rate (NL / min) in terms of atmospheric pressure. Furthermore, the value of the hydrodynamic pressure of the cavitation nozzle at the time of the above flow rate setting measured by a pressure gauge (not shown) and the value of the average flow velocity in the throttle hole (cavitation processing unit) calculated from the flow rate value and the total flow cross-sectional area are also shown in the table. It is shown according to 1. Under all conditions, the average flow velocity of the cavitation processing unit is secured at a value of 9 m / sec.

In this state, the juvenile whiteleg shrimp is added so that the individual density is 200 animals / ton, and the juvenile shrimp in the pond is fed with fish meal, krill meal, squid meal and wheat flour according to the degree of shrimp growth. Was administered as appropriate and bred. As the breeding continues, shrimp excrement and leftover feed will float in the aquaculture water as organic residues. By the above circulation of the aquaculture water, the suspended matter is removed to some extent in the filtration tank 252 of FIG. 1A, but if the breeding is continued for a long period of time, the suspended matter that could not be completely removed flows out to the buffer tank side on the downstream side. , Gradually accumulates in the auxiliary filtering unit 253f (cavitation processing filtering unit). As a result, the suction load on the filtration main pipe 180 by the main pump 175 increases, and the circulation flow rate of the filtration main pipe 180 gradually decreases on the upstream side of the branch point with the cavitation processing pipe 1. However, since the configuration of the closed land aquaculture apparatus shown in FIG. 1A is adopted, the distributed flow rate to the cavitation processing pipe 181 (that is, the cavitation nozzle 1) side is set within the specified flow rate range under any condition. I was able to keep it inside. Regarding the filter 252f in the filtration tank 252, when the total flow rate of the main filtration pipe 180 decreased to 30 L / min or less, the circulation was temporarily stopped and replaced with a new one as appropriate. The inside of the filter tank 252 is air-ventilated by an aeration mechanism (not shown), and aerobic microorganisms such as Bacillus, which are involved in humus formation, are propagated to simultaneously humus the filtered organic residue. ing.

The following items were confirmed and evaluated after the lapse of 30 days, 90 days, and 120 days after the start of the above aquaculture test.
(1) COD value Cultured water was sampled and measured by the method specified in JIS K 0102 (2013) 17.
(2) Mean length 30 shrimp being cultivated were randomly selected, and the length of each shrimp was measured to obtain the average value.
(3) Death rate The number of dead shrimp that died and emerged on the aquaculture pond was confirmed every 3 hours, and the death rate was calculated from the total number of deaths up to each day. For comparison, the same experiment was performed in the case where only the gas-liquid mixer 150 was attached to the cavitation processing pipe 181 without using the cavitation nozzle 1 in FIG. 1 (without cavitation processing). The above results are shown in Table 2.

＊は比較例。

* Is a comparative example.

Regarding the oxygen concentrations of Nos. 2 to 5 in which the oxygen concentration of the aquaculture water is within the range of the present invention, by using the aquaculture water subjected to the cavitation treatment, as compared with the case of using the aquaculture water not subjected to the cavitation treatment. It is clear that shrimp grow much faster even if the cultured water shows the same oxygen concentration. In addition, it can be seen that the COD value of the aquaculture water is remarkably lowered by performing the cavitation treatment, and the contamination of the aquaculture water is less likely to proceed. Especially in the low oxygen concentration region of 3 to 4 ppm, the mortality rate of shrimp without cavitation treatment is remarkably high, whereas the mortality rate with cavitation treatment is significantly reduced. Understand.

Further, in the case of the condition of No. 1 (2 ppm) in which the oxygen concentration of the cultured water is lower than the lower limit of the range of the present invention, the mortality rate increases after 120 days even if the cavitation treatment is performed, and the COD value deteriorates. Has been seen. On the other hand, in the case of the condition No. 6 (7.5 ppm) in which the oxygen concentration of the cultured water exceeds the upper limit of the range of the present invention, it can be seen that the mortality rate is higher than that in the case where the cavitation treatment is not performed. The condition of No. 6 is not only that the oxygen concentration is high, but also that the circulation circulation ratio K of the cavitation nozzle 1 to the total volume of the aquaculture water W is large, so that the amount of bubbles grown to about 100 nm to 30 μm in the cavitation nozzle 1 becomes excessive. It was considered that the cause was that these bubbles adhered to the shrimp gills and it became difficult to take in dissolved oxygen.

(Example 2)
The cavitation nozzle was created with the same dimensional relationship as that shown in FIG. 1C, except that the structure of the cavitation processing portion was changed to the form shown in FIG. 14 (two aperture holes 9 were formed). Two types of inner diameters D of each diaphragm hole were prepared: φ3.9 mm (referred to as cavitation nozzle C) and φ4.9 mm (referred to as cavitation nozzle D). Further, for a large flow rate, a cavitation nozzle having a set of aperture holes 9 similar to that shown in FIG. 1C has an inner diameter D of φ9.8 mm (referred to as cavitation nozzle E) and φ15.0 mm (with cavitation nozzle F). Two types (referred to as) were prepared. For the former, two sets of face screws composed of four screws shown in FIG. 2 are used, and for the latter, face screw sets are arranged at each value of 1 to 3 sets in a positional relationship in which they overlap each other. The 70% valley point density of each nozzle is secured at 2.0 pieces / mm ² or more.

These nozzles were incorporated into the closed land aquaculture apparatus shown in FIG. 1A, and the same experiments and evaluations as in Example 1 were carried out under the following test conditions. Under all conditions, the set oxygen concentration with respect to the cultured water was 4 ppm, and the individual density of the cultured product (whiteleg shrimp) was 200 animals / ton. For the cavitation nozzle C, the control flow rate value was set to 4.6 to 6.1 L / min, so that the flow velocity in the cavitation processing unit was adjusted to each value of 7.5 to 9.9 m / sec. For the cavitation nozzle D, the control flow rate value was set to 6.0 to 11.7 L / min, so that the flow velocity in the cavitation processing unit was adjusted to each value of 5.2 to 9.9 m / sec. For the cavitation nozzles E and F, the flow rate in the cavitation processing section was adjusted to 9.9 m / sec by setting the control flow rate values to 33.1 L / min and 86.7 L / min. The amount of water in the aquaculture pond is variously set in the range of 50t to 500t, but the value of the distribution circulation ratio K should be within 0.5% or more and 2% or less depending on the type of cavitation nozzle and the flow rate. Is set to. The above results are shown in Table 3 (the results on the 90th and 120th days are shown for those subjected to cavitation treatment).

Conditions (numbers 51, 53, 54, 56) in which a cavitation nozzle having a 70% valley point area density of 1.6 pieces / mm ² or more is used and a condition that the average flow velocity in the cavitation processing section is 8 m / sec is secured. , 56-58), as is clear from the case where the oxygen concentration of Example 1 was 4 ppm (No. 3) without cavitation, the growth of shrimp was promoted, and the COD value indicating the water quality was well maintained. It can be seen that the mortality rate is also low. On the other hand, in the comparative examples (Nos. 52 and 55) in which the average flow velocity in the cavitation processing section is less than 8 m / sec, it can be seen that the mortality rate is high and the COD value is also deteriorated. Moreover, 70% valley dot area density of the conditions of 1.6 pieces / mm ² Number 59 using the cavitation nozzle below 70% valley dot area densities using 1.6 pieces / mm ² or more cavitation nozzle It can be seen that the growth of shrimp is slightly slower and the mortality rate is also increased compared to the case.

(Example 3)
The same cavitation nozzles A and B as in Example 1 were incorporated into the closed land aquaculture apparatus 300 of FIG. 1A together with the gas-liquid mixer 150 of FIG. 10, and 50 tons of artificial seawater having a salinity of 3.5% (water depth) was added to the fishpond 250. : Approximately 2 m) Injecting and starting circulation by the main pump 175 at an initial flow rate of 100 L / min. Then, while controlling the opening degree of the distribution valve 183 so that the flow rates of the nozzles A and B are the same as those of the first embodiment, the oxygen concentration, which is the control target of the aquaculture water, is 4.0 ppm to 7.5 ppm ( 7.5 ppm) was set to be a comparative example), and the solenoid valves 184 and 174 of FIG. 1A were driven and controlled to maintain the oxygen concentration of the aquaculture water at each set value. The air ejection flow rate of the air diffuser 174 was set to 50 NL / min (average cell diameter: 0.3 mm). The air supply flow rate to the cavitation nozzle 1 was adjusted so as to be 10% of the water flow rate at the volume flow rate (NL / min) in terms of atmospheric pressure. In addition, the value of the hydraulic water pressure of the cavitation nozzle at the time of the above flow rate setting measured by a pressure gauge (not shown) and the value of the average flow velocity in the throttle hole (cavitation processing unit) calculated from the flow rate value and the total flow cross-sectional area are also shown in the table. It is shown according to 1. Under all conditions, the average flow velocity of the cavitation processing unit is secured at a value of 9 m / sec or more.

In this state, juvenile red sea bream was added so as to have an individual density of 40 animals / ton, and sardine-based moist pellets were appropriately administered to red sea bream in the pond according to the degree of growth of red sea bream and bred. .. Also in this embodiment, when the total flow rate of the main filtration pipe 180 drops to 30 L / min or less, the filter 252f in the filtration tank 252 is temporarily stopped from circulating and replaced with a new one as appropriate. Further, the inside of the filter tank 252 is air-ventilated by an aeration mechanism (not shown), and aerobic microorganisms are propagated to simultaneously humus the filtered organic residue.

After the lapse of 240 days and 510 days after the start of the above aquaculture test, the average body weight and mortality rate of red sea bream were measured. For comparison, the same experiment was performed in the case where only the gas-liquid mixer 150 was attached to the cavitation processing pipe 181 without using the cavitation nozzle 1 in FIG. 1 (without cavitation processing). The above results are shown in Table 4.

Regarding the oxygen concentrations of Nos. 101 and 102 in which the oxygen concentration of the cultured water is within the range of the present invention, by using the cultured water subjected to the cavitation treatment, as compared with the case of using the cultured water not subjected to the cavitation treatment. It is clear that red sea bream grows much faster even if the cultured water shows the same oxygen concentration. In particular, in the low oxygen concentration region of 4 ppm, the mortality rate of red sea bream without cavitation treatment is remarkably high, whereas the mortality rate with cavitation treatment is significantly reduced. On the other hand, it can be seen that when the oxygen concentration of the cultured water exceeds the upper limit of the range of the present invention under the condition of No. 103 (7.5 ppm), the mortality rate is higher than that when the cavitation treatment is not performed.

1 Cavitation nozzle 2 Nozzle body 3 Nozzle flow path 5 Culture water outlet 4 Culture water inlet 9 Squeezing hole 10 Thread member 150 Gas-liquid mixer 151 Outer cylinder member 155 Flow path forming member 156 Spiral section 157 First spiral flow path 158 Second Spiral flow path 159 Inflow port 160 Outflow port 165 Multiphase flow supply unit 174 Air diffuser 175 Main pump 180 Main piping for filtration 181 Piping for cavitation processing 181p Pump for cavitation processing 182 Flow detection unit 183 Distribution valve 185 Culture pond 252 Filter tank 253f Auxiliary filtering unit (Cavitation processing filtration unit)
300 Closed land aquaculture equipment W aquaculture water SP aquaculture LP1 to LP4 Screw placement surface CV cavitation treatment unit

Claims (10)

The aquaculture water and the aquaculture animal consisting of shellfish or fish are housed in the aquaculture pond, and the aquaculture water is guided from the aquaculture pond to a filter tank by using a main pump, and the organic residue floating in the aquaculture water is filtered. In a closed aquaculture device for raising the aquaculture animal by feeding feed into the aquaculture pond while returning it to the aquaculture pond and circulating it.
An oxygen dissolution mechanism that dissolves the aquaculture water while supplying an oxygen-containing gas to the aquaculture water so that the oxygen concentration of the aquaculture water is maintained at 2.5 ppm or more and 7 ppm or less.
A cavitation treatment pipe in which the inflow port of the aquaculture water communicates with the aquaculture pond and the other end side serves as a return port of the aquaculture water to the aquaculture pond.
A nozzle flow path provided in the middle of the cavitation treatment pipe, having an inlet for the aquaculture water at one end and an outlet for the aquaculture water at the other end is formed, and a part of the nozzle flow path is cavitation-treated. The aquaculture water inlet is provided with a nozzle body defined as a portion and a plurality of screw members assembled to the nozzle body so that the tip end side of the leg protrudes inside the flow path in the cavitation processing portion. The aquaculture water is circulated from the aquaculture water outlet to the aquaculture water outlet, and the aquaculture water is brought into contact with the aquaculture water formed on the outer peripheral surface of the leg portion of the aquaculture member while accelerating. A cavitation nozzle that performs cavitation treatment based on reduced pressure precipitation of dissolved air,
A cavitation processing pump provided in the middle of the cavitation processing pipe and flowing the cultured water through the cavitation nozzle at a specified flow rate at which the average cross-sectional flow velocity in the cavitation processing unit is 8 m / sec or more.
A closed aquaculture device characterized by being equipped with. The closed-type aquaculture apparatus according to claim 1, wherein the oxygen dissolution mechanism dissolves the aquaculture water while supplying the oxygen-containing gas to the aquaculture water so that the oxygen concentration of the aquaculture water is maintained at 3 ppm or more and 6 ppm or less. The cavitation nozzle is formed so that the nozzle flow path has a circular cross section, and each of the cavitation processing portions has a screw pitch and a screw valley depth of 0.20 mm or more and 0.40 mm or less as the screw member, and a nominal screw. A plurality of screw members having a diameter M of 1.0 mm or more and 2.0 mm or less are arranged, and the nozzle flow path is projected from the cross-sectional center of the nozzle flow path to a plane orthogonal to the central axis of the nozzle flow path. The 70% valley point is defined as the 70% valley point area density obtained by dividing the total number of valley points located in the region within 70% of the radius among all the threaded planes by the cross-sectional area of the nozzle flow path. The closed type onshore culture apparatus according to claim 1 or 2, wherein the one having an area density value of 1.6 pieces / mm ² or more is used. The specified flow rate for the cavitation nozzle is K = V2 / V1 × 100 (%), where the amount of water stored in the pond is V1 and the flow rate of the cavitation nozzle per hour is V2.
The closed-type aquaculture apparatus according to claim 3, wherein the distribution / circulation ratio K represented by the above is adjusted to be 2% or less. Claim 1 to claim 1, wherein the oxygen dissolution mechanism includes a multiphase flow supply unit that supplies a multiphase flow of the oxygen-containing gas and the culture water to the cavitation nozzle in order to dissolve the oxygen-containing gas at the cavitation nozzle. Item 4. The closed land culture apparatus according to any one of Item 4. A hollow outer cylinder member having an inflow port at one end and an outflow port at the other end, and a spiral flow path provided inside the outer cylinder member and connecting the inflow port and the outflow port are spirally formed. The cavitation nozzle is provided with a flow path forming member formed so that the spiral axis of the flow path is along the central axis of the outer cylinder member, and the spiral flow path communicates with the nozzle flow path of the cavitation nozzle. Equipped with a gas-liquid mixer provided on the culture water inlet side of
The closed-type aquaculture apparatus according to claim 5, wherein the mixed-phase flow supply unit supplies the mixed-phase flow to the inlet of the gas-liquid mixer. The oxygen dissolution mechanism is provided separately from the cavitation nozzle, and injects the oxygen-containing gas supplied from the outside into the aquaculture water that fills the aquaculture pond so that the average bubble diameter is 0.1 mm or more and 0.5 mm or less. The closed-type land-based aquaculture apparatus according to any one of claims 1 to 6, further comprising an air diffuser. A cavitation treatment filtration unit provided at the inlet of the cavitation treatment pipe and suppressing the inflow of suspended matter in the aquaculture pond into the cavitation treatment pipe.
A flow rate detection unit that detects the flow rate of the aquaculture water flowing in the cavitation processing pipe, and
It is provided with a cavitation flow rate control unit that controls the flow rate of liquid sent to the cavitation nozzle by the cavitation processing pump to the specified flow rate in a form of compensating for the flow rate loss due to the accumulation of the suspended matter on the cavitation processing filtration unit. The closed type land culture apparatus according to any one of claims 1 to 7. The main pipe for filtration, in which the inflow port of the aquaculture water communicates with the filtration tank and the other end side serves as a return port for the aquaculture water to the aquaculture pond.
The main pump is provided with an auxiliary filtering unit provided at the inlet of the main filtration pipe to prevent suspended matter in the filtration tank from flowing into the main filtration pipe, and the main pump is the main pipe for filtration. As well as being provided on top
The cavitation processing pipe is provided so as to branch from the filtration main pipe on the downstream side of the main pump and to open the return port to the fishpond at a position different from the filtration main pipe. Be,
Further, a distribution valve for adjusting the distribution ratio between the main pipe of the aquaculture water and the cavitation treatment pipe according to the valve opening degree is provided.
The main pump is used as the cavitation processing pump, and the auxiliary filtering unit is also used as the cavitation processing filtering unit.
The cavitation flow rate control unit increases the distribution ratio of the aquaculture water to the cavitation treatment pipe when the water supply flow rate of the main pump decreases due to the accumulation of the suspended matter on the auxiliary filtering unit. The closed type aquaculture apparatus according to claim 7 or 8, wherein the opening degree of the distribution valve is adjusted and controlled. The closed aquaculture apparatus according to any one of claims 1 to 9 is used to accommodate the aquaculture water and the aquaculture animal in the aquaculture pond, and the aquaculture pond is used to cultivate the aquaculture from the aquaculture pond. The feature is that water is guided to the aquaculture tank, the organic residue floating in the aquaculture water is filtered, returned to the aquaculture pond and circulated, and the feed is put into the aquaculture pond to breed the aquaculture animal. Land aquaculture method.

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