Culture system

Abstract

To provide a culture system capable of easily adjusting water temperature.SOLUTION: A culture system includes: a culture tank 1a installed on the land and culturing shellfish in rearing water; an intake source 19a installed on the land, dug to at least 15 m underground and capable of taking the underground water; an input side fluid delay device 15a which is composed of a first pipe embedded in deep underground water 10 m underground or deeper inside the intake source 19a, takes the deep part underground water 10 m underground or deeper from an end of the first pipe as the rearing water, and is capable of passing it inside the first pipe or can cool a heat transfer medium passing inside the first pipe by heat exchange with the deep part underground water; and an output side fluid delay device 5a which is composed of a second pipe embedded in the rearing water and is capable of supplying the rearing water for the inside of the culture tank 1a from the end of the second pipe or of cooling the rearing water by heat exchange with heat transfer medium passing inside the second pipe.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fish and shellfish farming system, and more particularly to a farming system equipped with an aquarium capable of adjusting water temperature in an environment of global warming. [Background technology]

[0002] The number of scallop juveniles in Mutsu Bay in December 2022 was the lowest in the past 10 years, down 36% compared to 2021, putting marine aquaculture at risk. Over the past four or five years, Mutsu Bay has experienced prolonged periods of high water temperatures during the summer, resulting in the death of scallops in marine aquaculture. Land-based aquaculture, unlike marine aquaculture conducted in natural environments, is cultivated in an artificially created environment on land, allowing for the cultivation environment to be controlled. However, with global warming and global warming, controlling water temperature in land-based aquaculture has become increasingly difficult. Land-based aquaculture can be divided into two types: free-flowing and circulating. In the free-flowing type, seawater is continuously drawn in from the natural environment and used as cultivation water. In the circulating type, the cultivation water is purified using a filtration system and then recycled.

[0003] The free-flowing system places an environmental burden on the fish, such as leftover food and excrement, and the water temperature in the breeding tanks is seasonal and can be subject to some temperature control issues. On the other hand, the circulating system places a smaller burden on the environment and allows for water temperature control with a thermostat, but requires the expense of setting up aquaculture facilities such as a temperature control system.

[0004] Patent Document 1 describes a method of adjusting the temperature by pumping groundwater at a temperature of 15°C to 18°C into a heat exchanger tank while circulating water in the aquaculture tank through flexible tubes. Patent Document 2 describes a method of adjusting the temperature of the rearing water by heat exchange with temperature-adjusted water introduced from a water intake source such as a well using a temperature control device in a circulation system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 61-35738 [Patent Document 2] International Publication No. 2015 / 111592 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an aquaculture system that allows for easy water temperature regulation for fish and shellfish even in the face of global warming. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, one aspect of the present invention is an aquaculture system comprising: (a) aquaculture tanks installed on land for cultivating fish and shellfish in rearing water; (b) a water intake source installed on land, excavated at least 15 m underground, and capable of taking in groundwater; (c) a first pipe buried in deep groundwater at a depth of 10 m or less inside the water intake source, wherein the deep groundwater at a depth of 10 m or less can be taken as rearing water from the end of the first pipe and passed through the first pipe, or an input-side fluid delay device capable of cooling the heat transfer medium passing through the first pipe by heat exchange with the deep groundwater; and (d) a second pipe buried in the rearing water, wherein the rearing water can be supplied into the aquaculture tank from the end of the second pipe, or an output-side fluid delay device capable of cooling the rearing water by heat exchange with the heat transfer medium passing through the second pipe. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an aquaculture system that allows for easy water temperature regulation even in the face of global warming. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic bird's-eye view showing an outline of an aquaculture system according to a first embodiment of the present invention as an example. [Figure 2]FIG. 10 is a schematic bird's-eye view showing an outline of an aquaculture system according to a modified example of the first embodiment. [Figure 3] FIG. 10 is a schematic plan view showing an example of an aquaculture system according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a schematic view showing the cross section AA of the water tank shown in FIG. [Figure 5] FIG. 10 is a diagram illustrating an example of a water supply system to an aquaculture system according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional schematic view showing an aquaculture system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, first to fourth embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following explanation. Furthermore, it goes without saying that the drawings also include parts with different dimensional relationships and ratios.

[0011] (First embodiment) As shown in FIG. 1, the aquaculture system according to the first embodiment of the present invention includes a water intake source (freshwater source) 19a, which is a deep well installed on land and drilled at least 15 meters underground; an input fluid delay device 15a, which is located deep within the water intake source 19a and comprises a first pipe that runs around the inside of the side wall of the water intake source 19a along the shape of the side wall; an aquaculture tank 1a installed on land; and an output fluid delay device 5a, which is a first pipe that runs around the inside of the side wall of the aquaculture tank 1a along the shape of the side wall. The aquaculture system according to the first embodiment is a free-flow aquaculture system that uses breeding water stored in the aquaculture tank 1a to cultivate fish and shellfish. The input fluid delay device 15a and the output fluid delay device 5a may have shapes or structures other than helical coils (solenoid coils) as long as they have a fluid delay line structure that can delay the travel time of the fluid passing through them. For example, it may be a structure in which spiral pipes shaped like incense sticks are stacked in multiple layers, or a structure in which serpentine pipes are stacked in multiple layers in a circular pattern. In terms of the spiral coil shape, if the water intake source 19a is cylindrical, the envelope surface of the overall three-dimensional shape of the first pipe of the input fluid delay unit 15a will be a cylindrical surface. If the water intake source 19a is a polygonal prism, such as a square prism, the envelope surface of the spiral coil of the input fluid delay unit 15a will be a polygonal prism surface. If the aquaculture tank 1a is cylindrical, the envelope surface of the overall three-dimensional shape of the second pipe of the output fluid delay unit 5a will be a cylindrical surface. If the aquaculture tank 1a is a polygonal prism, such as a square prism, the envelope surface of the spiral coil of the output fluid delay unit 5a will be a polygonal prism surface.

[0012] The output-side fluid delay device 5a is disposed in the culture water of the aquaculture tank 1a, with one end of the outlet of the output-side fluid delay device 5a in contact with the bottom of the aquaculture tank 1a. Similarly, the input-side fluid delay device 15a is disposed in the water of the water intake source 19a with the bottom of the water intake source 19a in contact with the bottom of the water intake source 19a. Although not shown, an excess water outlet is provided at a predetermined position (height) above the aquaculture tank 1a, and excess culture water poured from the output-side fluid delay device 5a is discharged from the excess water outlet. By providing the excess water outlet, culture water is continuously supplied from the output-side fluid delay device 5a to the aquaculture tank 1a, while the water level in the aquaculture tank 1a is designed to remain constant, forming a free-flowing aquaculture system.

[0013] The aquaculture system according to the first embodiment further includes a water intake pipe 31 connected to the input fluid delay device 15a, a water lifting pump (water intake pump) 11a connected to the water intake pipe 31, and a water supply pipe (first water supply pipe) 32 connected to the water lifting pump 11a. The water intake pipe 31 has its input connected to the output side of the input fluid delay device 15a of the water intake source 19a and rises above the water from underwater in the water intake source 19a. The water lifting pump 11a has its input connected to the output side of the water intake pipe 31, which rises above the water from underwater inside the water intake source 19a. The input side (water inlet) of a first water supply pipe 32 is connected to the output side of the water lifting pump 11a, and the output side of the first water supply pipe 32 is led from above the water into the breeding water in the aquaculture tank 1a and connected to the input side of the output fluid delay device 5a. The water intake pipe 31 and the first water supply pipe 32 are preferably made of a material with low thermal conductivity, and the input side fluid delay device 15a and the output side fluid delay device 5a are preferably made of a material with high thermal conductivity.

[0014] As shown in FIG. 1, the input-side fluid delay device 15a is installed in a deep location in the water of the water intake source 19a, where the water temperature is low. The low-temperature groundwater is pumped up by the water pumping pump 11a from the water intake of the input-side fluid delay device 15a, which is opened at a deep location (bottom), while being delayed at a deep location. The low-temperature groundwater pumped up by the water pumping pump 11a is then pumped into the aquaculture tank 1a as rearing water from the outlet of the output-side fluid delay device 5a. The water intake source 19a is a well drilled to a depth of at least 15 m underground. The temperature of seawater used as rearing water in a typical aquaculture system is high, for example, above 25°C in summer, and low, below 10°C in winter. Seawater temperature is expected to rise further due to global warming. The temperature of the groundwater in the water intake source 19a is approximately constant throughout the year, between 10°C and 25°C, in the local area 10 to 15 meters underground where the input fluid delay device 15a is located, and in local areas deeper than this. If the height of the input fluid delay device 15a is 5 meters, the entire input fluid delay device 15a will fit within the local area 10 to 15 meters underground. The groundwater at a temperature between 10°C and 25°C deep in the water intake source 19a (hereinafter referred to as "deep groundwater") is locally and selectively pumped up by the pumping pump 11a via the input fluid delay device 15a, and the low-temperature groundwater is then injected into the aquaculture tank 1a via the output fluid delay device 5a, thereby adjusting the temperature of the rearing water to between 10°C and 25°C.

[0015] Preferably, deep groundwater from the water intake source 19a is locally and selectively pumped up by the input-side fluid delay device 15a and then injected into the aquaculture tank 1a via the output-side fluid delay device 5a, thereby making it possible to adjust the water temperature to a desired level suitable for the growth of cultured fish and shellfish, such as 12°C to 20°C. As a result, in the aquaculture system according to the first embodiment, the temperature of the rearing water in the aquaculture tank 1a can be maintained at a substantially constant level throughout the year, making it possible to promote the growth of the cultured fish and shellfish.

[0016] As shown in Figure 1, deep groundwater from a water intake source 19a installed outside the aquaculture tank 1a is locally pumped up by a water pump 11a. The water is then injected into the first water supply pipe 32 via a water inlet connected to the water pump 11, and flows as rearing water into the output-side fluid delay device 5a installed in the rearing water of the aquaculture tank 1a. As groundwater with a temperature of 12°C to 20°C flows through the output-side fluid delay device 5a while being delayed, the rearing water in contact with the output-side fluid delay device 5a is efficiently cooled, so that the output-side fluid delay device 5a also functions as a heat exchanger. Specifically, the first water supply pipe 32 connected to the input side of the output-side fluid delay device 5a receives deep groundwater from the water intake source 19a through the inlet of the first water supply pipe 32, and supplies the rearing water to the aquaculture tank 1a through the outlet of the output-side fluid delay device 5a, cooling the rearing water.

[0017] As shown in FIG. 1, the output-side fluid delay device 5a is placed in the culture water in the culture tank 1a, with the lower end of its water inlet in contact with the bottom of the culture tank 1a. The output-side fluid delay device 5a is spirally coiled to fit the shape of the inner wall of the culture tank 1a. The output-side fluid delay device 5a is formed as a heat exchanger using a metal pipe made of corrosion-resistant stainless steel, titanium, or other highly thermally conductive metal, formed into a spiral coil. For example, if the culture tank 1a has an inner diameter of approximately 4 m and a depth of approximately 1 m, the output-side fluid delay device 5a can be configured with a spiral coil inner diameter of approximately 3.5 m and 10 spiral coil stages, resulting in a pipe length of approximately 110 m. The output-side fluid delay device 5a has a multi-stage spiral coil shape, which increases the contact area with the culture water in the culture tank 1a and slows the flow of water, improving heat exchange efficiency while supplying water to the culture tank 1a.

[0018] The aquaculture tank 1a of the aquaculture system according to the first embodiment is preferably installed indoors to block direct sunlight, snow, rain, strong winds, etc. When the aquaculture tank 1a is installed outdoors, it is desirable to provide a simple roof over the aquaculture tank 1a using a waterproof sheet or the like, although this is not shown in the drawings, to provide shading to the aquaculture tank 1a. In the summer when direct sunlight is strong, shading the aquaculture tank 1a can lower the temperature of the aquaculture tank 1a by approximately 2.5°C to 3°C.

[0019] -Modification of the first embodiment- As shown in Fig. 2, an aquaculture system according to a modification of the first embodiment of the present invention is similar to the structure shown in Fig. 1 in that it is a free-flow aquaculture system including a water intake source 19a, which is a deep well drilled at least 15 m underground on land, an input fluid delay device 15a consisting of a first pipe disposed underwater in the water intake source 19a, an aquaculture tank 1a installed on land, and an output fluid delay device 5a consisting of a second pipe disposed in the culture water of the aquaculture tank 1a. Similarly to Fig. 1, the aquaculture system according to the modification of the first embodiment includes a water intake pipe 31 whose input side is connected to the output side of the input fluid delay device 15a, and a water pump 11a whose input side is connected to the output side of the water intake pipe 31. However, the aquaculture system according to the modification of the first embodiment differs from the structure shown in Fig. 1 in that a temperature adjustment device 52 is provided midway along a first water supply pipe 32 whose output side is connected to the input side of the output fluid delay device 5a and whose input side (water inlet) is connected to the output side of the water pumping pump 11a, as shown in Fig. 2. The operation of the temperature adjusting device 52 can be controlled by the central control device 51. The central control device 51 can also control the flow rate of the water pump 11a.

[0020] As described in the aquaculture system according to the first embodiment, deep groundwater typically maintains a temperature of 15–18°C, eliminating the need for a temperature regulator 52. However, fine adjustments to the water temperature may be necessary depending on the type of fish and shellfish and their growth stage. The central control unit 51 can operate the temperature regulator 52 as needed. Furthermore, when a global abnormality, such as an abnormality in the groundwater veins, occurs, the central control unit 51 may operate the temperature regulator 52 to finely adjust the water temperature. The temperature regulator 52 can perform feedback control using information from a temperature sensor installed in the culture water of the aquaculture tank 1a. While a cooling device or heater can be used for temperature control, temperature control can also be achieved by controlling the flow rate of the water flowing through the input-side fluid delay unit 15a and the output-side fluid delay unit 5a. Furthermore, temperature control can also be achieved by utilizing the temperature distribution along the depth direction of the water intake source 19a and providing a depth control means in the water intake source 19a that mechanically adjusts the depth of the input-side fluid delay unit 15a.

[0021] (Second embodiment) As shown in FIG. 3, the aquaculture system according to a second embodiment of the present invention is a free-flow aquaculture system installed on land. The aquaculture system includes a circular aquaculture tank 1b in plan view, an output fluid delay device 5b formed of a second pipe that runs around the inside of the sidewall of the aquaculture tank 1b along the sidewall, and an aeration means 7 positioned inside the spiral coil pattern in plan view. The output fluid delay device 5b may have a shape or structure other than a spiral coil as long as it has a fluid delay line structure that can delay the travel time of the fluid passing through it. Even when the second pipe constituting the output fluid delay device 5b has a spiral coil shape, the circular planar shape shown in FIG. 3 is merely an example and is not limited to a circle. If the aquaculture tank 1b has a circular planar shape, the envelope surface of the entire three-dimensional shape formed by the second pipe constituting the output fluid delay device 5b will be a cylindrical surface. If the planar shape of the culture tank 1b is a polygon such as a rectangle, the envelope surface of the second pipe constituting the output fluid delay device 5b will be the surface of a polygonal cylinder.

[0022] The aquaculture tank 1b contains water 9b for cultivating fish and shellfish, and the output-side fluid delay device 5b is installed in the water 9b. A water supply pipe (first water supply pipe) is installed above the output-side fluid delay device 5b. A water inlet 6a of the water supply pipe is connected to a water pump (water intake pump) 11b installed on land in a water intake source (freshwater source) 19b, such as a well, located outside the aquaculture tank 1b. When the output-side fluid delay device 5b is in a mode where it is expected to function only as a heat exchanger, the other end of the output-side fluid delay device 5b opposite the water inlet 6a has a drain outlet 6b open to the outside, and the fluid flowing through the output-side fluid delay device 5b as a heat transfer medium is not supplied to the inside of the aquaculture tank 1b but is discharged from the drain outlet 6b.

[0023] When the output-side fluid delay device 5b is in a mode in which it functions as a water supply pipe for the culture water 9b, the lower end of the water supply port, which opens at the other end of the output-side fluid delay device 5b opposite the water inlet 6a, is positioned so that it contacts the bottom of the aquaculture tank 1b, and groundwater is supplied from the water supply port into the aquaculture tank 1b. Although not shown in the figure, the input-side fluid delay device is provided at a deep position in the water intake source 19b, which is a deep well excavated at least 15 meters underground, and is made up of a first pipe that runs around the inside of the sidewall of the water intake source 19b, following the shape of the sidewall. The circular planar shape of the water intake source 19b shown in Figure 3 is an example, and the water intake source 19b is not limited to a circular shape.

[0024] The input-side fluid delay device can have a fluid delay line structure capable of delaying the travel time of the fluid passing through it, and the first pipe can have a shape or structure other than a spiral coil. For example, if the input-side fluid delay device has a spiral coil shape, then if the planar shape of the water intake source 19b is circular, the envelope surface of the entire three-dimensional shape of the first pipes constituting the input-side fluid delay device will be a cylindrical surface. If the planar shape of the water intake source 19b is polygonal, the envelope surface of the first pipes constituting the input-side fluid delay device will be a polygonal column surface. If the height of the input-side fluid delay device is 5 m, the entire input-side fluid delay device will fit within a local area 10 to 15 m below the water intake source 19b. Deep groundwater from the water intake source 19b is pumped by the water pumping pump 11b through the input fluid delay device, injected into the water supply pipe inlet 6a connected to the output fluid delay device 5b, and discharged as culture water 9b into the aquaculture tank 1b through the outlet of the output fluid delay device 5b. On the other hand, when the output fluid delay device 5b is used purely as a heat exchanger, the low-temperature deep groundwater injected into the water supply pipe inlet 6a functions as a heat transfer medium and is discharged outside the aquaculture tank 1b through the outlet 6b, as shown in Figure 3. The culture water 9b in contact with the output fluid delay device 5b is cooled by heat exchange with the heat transfer medium. The aeration means 7 is connected to an air pump 12 installed outside the aquaculture tank 1b. The aeration means 7 blows air supplied by the air pump 12 into the aquaculture water 9b.

[0025] As shown in FIGS. 3 and 4, the aquaculture tank 1b includes a main tank 1b o and main tank 1b o Lining tank 1b that covers the inside of i Main tank 1b o As shown in Figures 3 and 4, the main tank 1b is cylindrical, with a side wall having a cylindrical curved surface and a bottom surface that is continuous with the bottom of the side wall. o A shallow cylindrical recess is provided in the center of the bottom of the lining tank 1b. i is the main tank 1b o It is a membrane-like or thin plate-like structure that covers the inside of the side wall and the upper surface of the bottom of the main tank 1b o The center of the main tank 1b is a shallow cylindrical recess, so it is an insulating layer that deforms to form a recess in the center. oMaterials such as concrete or fiber reinforced plastic (FRP) can be used for the lining tank 1b. i A waterproof sheet made of vinyl resin with high heat insulation and high strength can be used for the tank. The side walls of the tank 1b are cylindrically curved, so that the water pressure of the breeding water 9b can be isotropically dispersed. o and lining tank 1b i This double structure can cope with water leakage due to cracks. i This enhances heat retention and insulation, making it possible to cultivate fish at a stable water temperature.

[0026] Sediments such as residual feed and excrement from fish and shellfish cultivated in the culture water 9b settle in the collection unit 3 located in the center of the culture tank 1b. The sediments in the collection unit 3 are removed to the outside of the culture tank 1b via a removal hose 13, using a water pump or other appropriate device. This prevents deterioration of the water quality of the culture water 9b. When removing the sediments, the culture water is also discharged, but it can be replenished using the output-side fluid delay device 5b, or culture water such as seawater can be added through the external water supply pipe 14b.

[0027] As shown in Figures 3 and 4, the output-side fluid delay device 5b is a spiral coil arranged along the inside of the curved inner wall of the aquaculture tank 1b, so that it can be installed by being dropped into the culture water 9b filled in the aquaculture tank 1b. The output-side fluid delay device 5b is a heat exchanger made of a corrosion-resistant metal pipe such as stainless steel or titanium, or a corrosion-resistant resin pipe formed into a spiral coil. For example, if the aquaculture tank 1b has an inner diameter of approximately 4 m and a depth of approximately 1 m, the output-side fluid delay device 5b would have a spiral coil inner diameter of approximately 3.5 m, approximately 10 spiral coil stages, and a pipe length of approximately 110 m. The output-side fluid delay device 5b has a multi-stage spiral coil shape, which increases the contact area with the culture water 9b, thereby improving heat exchange efficiency while supplying water to the aquaculture tank 1b.

[0028] As shown in Figure 3, the output-side fluid delay unit 5b receives locally selected low-temperature deep groundwater from the water intake source 19b and injects it into the aquaculture tank 1b. The water intake source 19b is a deep well drilled to a depth of at least 15 meters underground. For example, the temperature of seawater used as culture water is high (over 25°C) in summer and low (below 10°C) in winter. With global warming, seawater temperatures are expected to rise further. This system can provide deep groundwater with a nearly constant temperature of 10°C to 25°C throughout the year in a localized area 10 to 15 meters underground and even deeper. By locally pumping the low-temperature deep groundwater from the water intake source 19b with the pumping pump 11b and injecting it into the aquaculture tank 1b through the output-side fluid delay unit 5b, the culture water 9b can be adjusted to a temperature between 10°C and 25°C, for example, between 12°C and 20°C, which is suitable for the growth of cultured fish and shellfish.

[0029] Alternatively, deep groundwater from the water intake source 19b can be locally pumped up by the pumping pump 11b, and the groundwater can be passed through the output-side fluid delay unit 5b to act as a heat exchanger, thereby cooling the culture water 9b in the aquaculture tank 1b. When the output-side fluid delay unit 5b acts as a heat exchanger, the deep groundwater passing through the output-side fluid delay unit 5b serves as a heat transfer medium, and the heat transfer medium is discharged to the outside of the aquaculture tank 1b. By using the output-side fluid delay unit 5b as a heat exchanger, it is also possible to adjust the temperature of the culture water 9b to between 10°C and 25°C. As a result, the aquaculture system according to the second embodiment can maintain a substantially constant temperature of the culture water 9b throughout the year, promoting the growth of cultured fish and shellfish.

[0030] As shown in Figures 3 and 4, the aeration means 7 is disposed in the breeding water 9b between the output-side fluid delay unit 5b and the collection unit 3. By aerating air into the breeding water 9b using the aeration means 7, not only does it increase the dissolved oxygen in the breeding water 9b but it also improves heat exchange efficiency by stirring the breeding water 9b near the output-side fluid delay unit 5b. While a single annular air stone is used as the aeration means 7, this is not limited to this. The air stone of the aeration means 7 may be spherical, disc-shaped, or rectangular, and multiple air stones may be provided.

[0031] The aquaculture system according to the second embodiment is preferably installed indoors to block direct sunlight, snow, rain, strong winds, etc. If installed outdoors, it is desirable to provide a simple roof using a waterproof sheet or the like to block out light. In the summer when direct sunlight is strong, shading can lower the temperature of the aquaculture tank 1b by about 2.5°C to 3°C.

[0032] (Third embodiment) The aquaculture system according to the first embodiment is suitable for freshwater fish and shellfish. The aquaculture system according to the second embodiment is suitable for freshwater fish and shellfish if the output-side fluid delay device 5b is used as a water supply pipe, and is suitable for saltwater fish and shellfish if the output-side fluid delay device 5b is used as a heat exchanger through which a heat transfer medium flows. The aquaculture system according to the third embodiment of the present invention will be suitable for saltwater fish and shellfish even if the output-side fluid delay device 5b is used as a water supply pipe for breeding water. As shown in Fig. 5, the aquaculture system according to the third embodiment uses an auxiliary pump 17 to pump seawater from a water intake source (seawater source) 16, such as the ocean. The seawater is then passed through an input fluid delay device 15c, which is a first pipe located underwater in a water intake source (relay water source) 19c, which is a deep well drilled at least 15m underground. The seawater cooled in the water intake source 19c is then supplied to the aquaculture tank 1b through a second water supply pipe (external water supply pipe) 14c. In the aquaculture system according to the third embodiment, the input fluid delay device 15c is used as a heat exchanger, and the seawater is cooled to a low temperature of 15 to 20°C by the input fluid delay device 15c, which is located deep underwater in the water intake source 19c.

[0033] In the aquaculture system according to the third embodiment, seawater pumped by the auxiliary pump 17 is adjusted to a temperature of 15 to 20°C by heat exchange as it passes through the input fluid delay device 15c. The output fluid delay device, which is a second pipe (not shown), is used as a water supply conduit to supply low-temperature seawater to the aquaculture tank 1b. Therefore, the aquaculture system according to the third embodiment can suppress temperature fluctuations in the breeding water 9b as a saltwater fish farming system. In the configuration shown in FIG. 5, low-temperature seawater is continuously supplied to the aquaculture tank 1b as the breeding water 9b, making it possible to operate the system as a free-flowing aquaculture system for saltwater fish and shellfish.

[0034] The culture water 9b must be replenished because some of it is discharged when sediments such as leftover feed and excrement from the farmed fish and shellfish are removed. Furthermore, when the quality of the culture water 9b deteriorates, a significant amount of the culture water 9b must be replaced. Replenishing or replacing the culture water 9b in summer or winter causes temperature fluctuations in the culture water 9b, which can affect the growth of the farmed fish and shellfish. According to the aquaculture system of the third embodiment, low-temperature seawater is continuously supplied to the aquaculture tank 1b as the culture water 9b. Therefore, even when the quality of the culture water 9b deteriorates or a significant amount of the culture water 9b needs to be replaced, fresh seawater can be supplied by flowing over it, making it possible to deal with such situations. To improve heat exchange efficiency, the input-side fluid delay device 15c is, for example, a corrosion-resistant metal or resin pipe formed into a spiral coil with approximately 10 layers and placed in the groundwater of the water intake source 19c.

[0035] (Fourth embodiment) While the first to third embodiments of the present invention have described free-flowing aquaculture systems, the fourth embodiment of the present invention will describe a closed-circulation aquaculture system. Specifically, as shown in Fig. 6, the aquaculture system according to the fourth embodiment purifies the culture water 9c in the aquaculture tank 1c in a circulation system 20 and returns the purified water to the aquaculture tank 1c through circulation paths 23a, 23b, and 23c. By employing a closed-circulation aquaculture system, suspended solids in the culture water 9c can be removed.

[0036] Although not shown, the aquaculture tank 1c shown in FIG. 6 includes an output-side fluid delay device (not shown) formed of a second pipe, which functions as a heat exchanger, similar to the aquaculture system according to the second embodiment. Low-temperature deep groundwater flows through the output-side fluid delay device as a heat transfer medium to cool the culture water 9c in the aquaculture tank 1c. Although not shown, the deep groundwater serving as a heat transfer medium is drawn from a localized area 10 to 15 m from the water intake source, or even deeper, by an input-side fluid delay device (not shown) formed of a first pipe, which is installed in the water intake source, a deep well drilled at least 15 m underground. The circulation system 20 illustrated in FIG. 6 includes a filtration tank 21 that performs physical filtration, biological filtration, and water activation, and a circulation pump 22 that circulates the culture water 9c. The aquaculture system according to the fourth embodiment maintains the temperature of the culture water 9c at a desired low temperature. Furthermore, the culture water 9c is circulated through the filtration tank 21, enabling stable water quality control of the culture water 9c.

[0037] (Other embodiments) As described above, the present invention has been described using first to fourth embodiments. However, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art from this disclosure. Thus, it should be understood that the present invention encompasses various embodiments not described herein. Therefore, the present invention is limited only by the specific aspects of the invention as defined in the appropriate claims from this disclosure. [Explanation of symbols]

[0038] 1a,1b…Aquaculture tank 1b o ...Main tank, 1b i... Lining tank, 3... Collection section, 5a, 5b... Output side fluid delay device, 6a... Water inlet, 6b... Drain outlet, 7... Ventilation means, 8... Air inlet, 9a, 9b... Rearing water, 11... Water pump (water intake pump), 12... Air pump, 13... Removal water pipe, 14c... Second water supply pipe (external water supply pipe), 15a, 15c... Input side fluid delay device, 16... Water intake source (seawater source), 17... Auxiliary pump, 19a, 19b... Water intake source (freshwater source), 20... Circulation system, 21... Filtration tank, 22... Circulation pump, 23a, 23b, 23c... Circulation path

Claims

[Claim 1] Aquaculture tanks are installed on land to cultivate fish and shellfish in breeding water, a water intake source that is installed on land, excavated to a depth of at least 15 m underground, and capable of extracting groundwater; an input-side fluid delay device that comprises a first pipe buried in deep groundwater at a depth of 10 m or less underground inside the water intake source, and that is capable of taking in the deep groundwater at a depth of 10 m or less underground from an end of the first pipe as the rearing water and passing the water through the inside of the first pipe, or that is capable of cooling a heat transfer medium passing through the inside of the first pipe by heat exchange with the deep groundwater; an output-side fluid delay device comprising a second pipe embedded in the rearing water, capable of supplying the rearing water from an end of the second pipe into the inside of the aquaculture tank, or capable of cooling the rearing water by heat exchange with the heat transfer medium passing through the inside of the second pipe; An aquaculture system comprising:

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