Ultrafine bubble generator, water circulation system, and nozzle

Abstract

To provide a generator that can generate ultrafine bubbles without changing a water pH value and retain the generated bubbles in water for a long time, a water circulation system, and a nozzle.SOLUTION: An ultrafine bubble generator 1 is configured such that terahertz waves of a frequency band resonating with water molecules are radiated from an in-water pump 10 and a nozzle 20 irradiated with the terahertz waves in advance, water dividing gravitational mutual actions of adjacent water molecules is activated, and air sucked through the nozzle is micronized to generate and dissolve ultrafine bubbles in the water. Preferably, the nozzle is provided with rectification means for rectifying the flow of a swirl generated in pressure-fed water.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ultrafine bubble generator, water circulation system, and nozzle that generate ultrafine bubbles in water and modify the water's properties to make it suitable for plant growth, aquaculture, cleaning, etc. More specifically, the invention relates to a generator consisting of a submersible pump equipped with a nozzle that discharges water, which generates ultrafine bubbles without changing the pH value of the water, and which can retain the generated bubbles in the water for a long period of time.

[0002] Specifically, the invention relates to a generator, water circulation system, and nozzle that first irradiate a submersible pump and a nozzle with terahertz waves, then emit terahertz waves in a frequency band that resonates with water molecules, disrupting the attractive interactions between adjacent water molecules and activating them. The activated water is then pumped from the pump to the nozzle, generating negative pressure in the air introduction tube extending from the nozzle to suck in air, and micronizing the suctioned air bubbles to generate ultrafine bubbles that are dissolved in the water. [Background technology]

[0003] It has long been known that increasing the dissolved oxygen concentration in agricultural water and fish farming ponds promotes the growth of agricultural crops and farmed fish, and so aeration devices have been installed in water storage tanks to forcibly introduce air into the water and increase the dissolved oxygen concentration. However, conventional aeration devices generate large bubbles in the water, so most of the bubbles rise to the surface in a short time and are released into the atmosphere, leaving only a small amount of air dissolved in the water.

[0004] In recent years, technologies that improve the cleaning power of water by generating finer bubbles in water, and technologies that efficiently increase the concentration of dissolved oxygen, have become increasingly popular. In 2019, the Japanese Industrial Standard (JIS B 8741-1) for fine bubble technology was established, defining fine bubbles as bubbles with a diameter of 1 μm to 100 μm, and ultrafine bubbles as bubbles with a diameter of less than 1 μm.

[0005] Among these microscopic bubbles, ultrafine bubbles have been confirmed to remain in water for long periods of time, from several months to a year, and are expected to be applied in a variety of technological fields, such as agriculture, aquaculture, livestock farming, water quality improvement, and cleaning.However, in water found in nature, adjacent water molecules form clusters due to attractive interactions, which creates large gaps for dissolving bubbles.

[0006] Therefore, when fine bubbles are generated in water using a simple device, they tend to aggregate into bubbles larger than ultrafine bubbles in the gaps between adjacent clusters, and these bubbles tend to dissipate from the water into the atmosphere in a short period of time, making it difficult to stably dissolve fine bubbles in water. Therefore, technologies have been developed to stably dissolve fine bubbles by breaking down the clusters of water molecules.

[0007] Patent Document 1 discloses a technology for a manufacturing device for magnetically activated water containing nanobubbles. According to the technology described in this document, a magnetic field is applied to a liquid to break down clusters of water molecules, a first gas shearing section generates microbubbles in the liquid, and a second gas shearing section further shears the microbubbles to generate ultrafine bubbles.

[0008] According to this document, water is passed through magnetic field lines to generate a weak current in the water, which generates active oxygen in the water and modifies it to have a high redox potential. There is a correlation between redox potential and pH value, and as the redox potential increases, the pH value decreases and the water becomes more acidic. Specifically, test results show that the pH value of water after aeration was 5.2.

[0009] However, according to "Soil pH and Solubility and Utilization of Fertilizer Elements (Non-Patent Document 1)" published by the Ministry of Agriculture, Forestry and Fisheries, the three major nutrients for agricultural crops, nitrogen, phosphorus, potassium, etc., all become difficult to dissolve at pH levels below 5.5, and the technology described in Document 1 has the problem of being unsuitable for plant growth.

[0010] Patent Document 2 discloses a technology for an apparatus for increasing dissolved oxygen in water that aerates fine bubbles into water. According to the technology described in this document, a substance that emits electromagnetic waves in the frequency band of 5 THz to 50 THz is incorporated into a suction filter and a fine bubble generating nozzle that are immersed in water, thereby breaking down clusters of water molecules.

[0011] According to this document, test results show that the pH value of the water after aeration was 8.5. Non-Patent Document 1 shows that when the pH value exceeds 7.5, minerals such as boron, iron, and manganese, as well as phosphorus, become less soluble. A deficiency of these phosphorus and minerals causes diseases such as leaf blight in agricultural crops, so even if the technology described in Document 2 is applied, there is a problem in that plant growth cannot be promoted.

[0012] Patent Document 3 discloses a technology for a water production device containing micro-nano bubbles. According to the technology described in this document, by providing a gas molecule cluster decomposition means using magnetic field lines and a water molecule cluster decomposition means using terahertz waves, micro-nano bubbles generated from an aeration tube placed in water are efficiently dissolved.

[0013] However, the technique described in Document 3 requires a gas molecule cluster decomposition means and a water molecule cluster decomposition means in addition to a pump and an aeration tube, which makes the device complicated. [Prior art documents] [Patent documents]

[0014] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-28595 Patent Document 2: Japanese Patent Application Laid-Open No. 2011-224529 Patent Document 3: Japanese Patent Application Laid-Open No. 2022-64805 [Non-patent literature]

[0015] Non-patent document 1: Ministry of Agriculture, Forestry and Fisheries website, "Soil pH and solubility and availability of fertilizer elements," searched on April 4, 2024, website <https: / / www.maff.go.jp / j / seisan / kankyo / hozen_type / h_sehi_kizyun / attach / pdf / index-10.pdf> Summary of the Invention [Problem to be solved by the invention]

[0016] The problem to be solved by the present invention is to provide an ultrafine bubble generator, a water circulation system, and a nozzle that can generate ultrafine bubbles and extend the dissolution time of the bubbles without changing the pH value of the water. [Means for solving the problem]

[0017] The first invention of the present invention is a nozzle attached to an underwater pump, the nozzle comprising, in order from the upstream side, a straightening means, an air atomization means, and an air suction means, the straightening means having a plurality of spiral flow paths, each of which is evenly arranged around the central axis of the nozzle and is a flow path twisted counterclockwise, the atomization means being provided adjacent to the upstream side of the suction means and being a throttling section which increases the flow rate of water pressurized by the underwater pump, the suction means being an air inlet pipe which introduces air by negative pressure caused by the flow rate, the throttling section functions to convert the air introduced from the air inlet pipe into the nozzle into fine bubbles, and the straightening means rectifies the water containing the fine bubbles so that it is discharged from the nozzle without swirling, and the fine bubbles do not agglomerate into larger bubbles.

[0018] A water flow passing through a straight pipe with low resistance generates a clockwise vortex at the nozzle outlet in the northern hemisphere and a counterclockwise vortex in the southern hemisphere. According to the first invention, the reverse tornado nozzle has multiple thin, twisted flow paths. This increases the area between the flow path walls and the water, causing the flow path walls to act as resistance to the water flow, slowing the flow velocity and rectifying the water flow.

[0019] By increasing the contact area between the water and the flow path wall per unit volume of water and rectifying the water flow with a reverse tornado that increases the contact time between the water and the flow path wall, the generation of vortices at the nozzle outlet is suppressed, and the ultrafine bubbles are prevented from re-aggregating into larger bubbles.

[0020] When the first invention is used in the northern hemisphere, the spiral flow path may be twisted counterclockwise to cancel out the clockwise vortex.

[0021] The first aspect of the invention has the advantageous effect of suppressing the generation of vortices at the nozzle outlet and preventing the generated bubbles from re-aggregating into larger bubbles. The nozzle of the first aspect of the invention is suitable for use in the generator of the fourth aspect of the invention and the water circulation system of the fifth aspect of the invention, which will be described later.

[0022] A second aspect of the present invention is the first aspect of the present invention, characterized in that the spiral flow path is three spiral flow paths, each of which has the same shape. According to the second aspect of the present invention, since the number of spiral flow paths is three and each of which has the same shape, the effect of not significantly reducing the water flow and achieving a rectifying effect is achieved. The cross-sectional shape of the flow path may be circular, but is not limited to this.

[0023] A third aspect of the present invention is the first aspect of the present invention, characterized in that the length of the flow path forming the rectifying means is between two and three times the outer diameter of the flow path, and the phase shift between the inlet and outlet of the spiral flow path is 180 degrees counterclockwise. According to the third aspect of the present invention, since the length of the flow path is between two and three times the outer diameter, and the phase shift between the inlet and outlet is 180 degrees, the flow rate of the pumped water is not reduced and the flow can be rectified over a short distance.

[0024] The fourth invention of the present invention is an ultrafine bubble generator characterized in that the nozzle of the first to third inventions is provided downstream of the discharge outlet provided in the main body of the submersible pump.

[0025] The nozzle is made up of an air introduction pipe that serves as an air suction means, a throttle section that serves as an air atomization means, and a spiral flow path that serves as a flow straightening means, so the structure is simple, the nozzle is less likely to clog, and the generator can be used not only for drinking water but also for aquaculture ponds, etc., making it highly versatile.

[0026] It is also preferable to radiate terahertz waves from the entire submersible pump and nozzle to the water being pumped. In order to radiate terahertz waves, the submersible pump and nozzle need only be machined using a known terahertz wave irradiation device so that they are irradiated with terahertz waves in a frequency band that resonates with water molecules.

[0027] By emitting terahertz waves in the frequency band of 32 THz to 38 THz from the entire submersible pump and nozzle, activated water (hereinafter referred to as activated water) can be produced that is more likely to dissolve ultrafine bubbles, as will be described later in the examples.

[0028] The ultra-fine bubbles generated in activated water by the suction means and the atomization means tend to be bubbles with a diameter of 0.1 μm or less, as will be described later in the bubble count measurement test 1 of the examples, and the generated bubbles are less likely to aggregate, resulting in a longer dissolution time for the bubbles.

[0029] Furthermore, the generator of the present invention hardly changes the pH value when applied to pure water, lake water, tap water, or aquaculture pond water. Therefore, when applied to agricultural water, it is unlikely to inhibit the dissolution of the three major nutrients and minerals, and the high dissolved oxygen concentration makes it suitable for promoting the growth of agricultural crops.

[0030] The fourth aspect of the present invention provides advantageous effects not found in conventional technologies, such as the generation of ultrafine bubbles and the extension of their dissolution time without changing the pH value of the water. Because the pH of the water is not changed, when applied to agricultural water, growth-promoting effects can be easily obtained not only in hydroponic cultivation but also when watering crops in soil cultivation.

[0031] The water circulation system of the fifth aspect of the present invention includes a plurality of the generators of the fourth aspect of the invention, and each of the generators is characterized in that the water discharged from the generator located upstream is sucked in by the generator located downstream, thereby circulating the water.

[0032] According to the fifth aspect of the present invention, a plurality of generators are arranged to circulate water containing dissolved ultrafine bubbles, which has the effect of enabling the water containing dissolved ultrafine bubbles to be ejected over a wide distance.

[0033] Furthermore, because a circulating flow is generated by multiple generators, ultra-fine bubbles can be distributed throughout the entire pond, even when applied to a large aquaculture pond or reservoir, thereby improving water quality and promoting the growth of farmed fish and shellfish. [Effects of the Invention]

[0034] According to the first aspect of the present invention, it is possible to suppress the generation of vortices at the discharge port, and to prevent the generated bubbles from re-aggregating into larger bubbles. According to the second aspect of the present invention, the effect of achieving a straightening effect can be achieved without significantly reducing the water flow.

[0035] According to the third aspect of the present invention, the flow rate of the pumped water is not reduced and the flow can be regulated over a short distance. According to the fourth aspect of the present invention, it is possible to generate ultrafine bubbles without changing the pH value of the water, and to extend the time the bubbles remain dissolved, which is an advantageous effect not available in conventional technologies.

[0036] According to the fifth aspect of the present invention, it is possible to eject water containing dissolved ultra-fine bubbles over a wide distance. [Brief explanation of the drawings]

[0037] [Figure 1] Schematic diagram of the generator (Example 1). [Figure 2] FIG. 2 is an explanatory diagram of a nozzle (Example 1). [Figure 3] FIG. 1 is an explanatory diagram of a nozzle equipped with a flow straightening means (Example 1). [Figure 4] Schematic diagram of a vortex and rectified water (Example 1). [Figure 5] Graph comparing the number of dissolved bubbles (Example 1). [Figure 6] Graph comparing the change in the number of dissolved bubbles over time (Example 1). [Figure 7] FIG. 1 is an explanatory diagram of a water circulation system (Example 2). DETAILED DESCRIPTION OF THE INVENTION

[0038] The submersible pump and nozzle, which have been previously irradiated with terahertz waves, emit terahertz waves in a frequency band that resonates with water molecules, disrupting the attractive interactions between adjacent water molecules and activating the water, thereby atomizing the air drawn into the nozzle and generating ultrafine bubbles that are dissolved in the water. The nozzle is preferably equipped with a rectifying means for rectifying vortices generated in the pumped water. [Example]

[0039] In Example 1, an ultra-fine bubble generator 1 consisting of a submersible pump and a nozzle will be described with reference to Figs. 1 to 6. Fig. 1 shows a schematic diagram of the generator. Fig. 2 shows an explanatory cross-sectional view of the nozzle. Fig. 3(A) shows an explanatory cross-sectional view of a nozzle equipped with a rectifying means. Fig. 3(B) shows an enlarged view of the rectifying means.

[0040] Figure 4 shows an explanatory diagram of a straightening means for straightening the vortex. Figure 4(A) shows the state in which swirled water is being discharged from the nozzle shown in Figure 2, and Figure 4(B) shows the state in which straightened water is being discharged from the nozzle shown in Figure 3(A). Figure 5 shows a graph comparing the number of dissolved bubbles depending on the configuration of the generator. Figure 6 shows a graph comparing the change over time in the number of dissolved bubbles depending on the configuration of the generator.

[0041] The generator 1 consists of a submersible pump 10 and a nozzle 20, which are irradiated with terahertz waves by a terahertz wave irradiation device (Fig. 1). The frequency band of terahertz waves is between 32 THz and 38 THz, which resonates with water molecules. It is particularly suitable to irradiate terahertz waves in a frequency band of around 35 THz.

[0042] The terahertz wave irradiation device is not limited as long as it is a known device. For example, it may be a device that irradiates only terahertz waves, or a device that irradiates terahertz waves while heating. Specifically, just like cooking food in a microwave oven, it is sufficient to house the submersible pump 10 and the nozzle 20 in the terahertz wave irradiation device and irradiate terahertz waves. Terahertz waves are emitted from the submersible pump or the like that is irradiated with terahertz waves.

[0043] The submersible pump 10 comprises a main body 11 that draws water through an intake port and pumps it to a nozzle, an outlet port 12 that protrudes laterally from the main body, and a cable 13 that supplies AC power to the submersible pump (see Figure 1). The size, discharge pressure, etc. of the submersible pump can be determined according to the amount of water to be stored, and are not limited to these.

[0044] The nozzle 20 that ejects water is a tube 23 equipped with an air introduction tube 21 that serves as an air suction means and a throttle section 22 that serves as an air atomization means (see Figure 2), and is attached to the discharge port 12 of the submersible pump and immersed in water. The terahertz waves emitted from the submersible pump 10 and the nozzle 20 disrupt the attractive interaction of water molecules that are pumped between the inside of the submersible pump and the inside of the nozzle, converting the water into activated water.

[0045] The tubular body 23 forming the nozzle may be a single tube or multiple tubes connected together, and the form is not limited. Here, the tubular body 23 comprises, from the upstream side, a first flow rate adjustment tube 24 having a throttle portion, an inner tube 25 fitted into the first flow rate adjustment tube to fix the throttle portion 22 in position, a negative pressure generating tube 26 connected to the tip of the first flow rate adjustment tube, and a second flow rate adjustment tube 27 connected to the tip of the negative pressure generating tube. The material of the tubular body is polyvinyl chloride, but it may also be made of metal such as stainless steel or aluminum, and is not limited to this.

[0046] The first flow rate adjustment pipe 24 has an attachment part 28 at its rear end that is attached to the discharge port 12, and is equipped with a throttle part 22 inside that narrows the inner diameter of the nozzle to increase the flow rate of the activated water pumped from the submersible pump. The throttle part 22 is sandwiched and fixed in position between an insertion part 29 of a negative pressure generating pipe inserted from the tip of the first flow rate adjustment pipe 24 and an inner insertion tube 25 inserted from the rear end of the first flow rate adjustment pipe (see Figure 2).

[0047] The throttle portion 22 may be a thin ring such as a known stainless steel washer. The inner diameter of the throttle portion is preferably, but not limited to, about 1 / 2 to 1 / 3 the outer diameter of the inner tube 25. The activated water pumped from the submersible pump is pumped into the negative pressure generating tube 26 at an increased flow rate by the throttle portion, and the flow of the pumped activated water breaks down the air bubbles sucked into the nozzle 20 from the air inlet tube 21.

[0048] The air introduction pipe 21 is inserted into a hole 30 drilled in the side of the negative pressure generating pipe 26, and the tip opening of the air introduction pipe is immersed in water. The inner diameter of the negative pressure generating pipe 26 is expanded from the rear end to the position of the hole. The flow rate of the activated water is increased by the throttle section 22, generating negative pressure in the negative pressure generating pipe 26, and air is sucked from the air introduction pipe 21 into the nozzle.

[0049] The air sucked into the nozzle and made into bubbles is then atomized by the activated water whose flow rate is increased in the throttle section 22, and some of the bubbles become ultra-fine bubbles 200 and are dissolved in the gaps between adjacent water molecules. The large-diameter bubbles 201 are not dissolved and are pressure-fed to the second flow rate adjustment pipe 27 together with the activated water.

[0050] In the second flow velocity adjustment pipe 27, the inner diameter of the nozzle is narrower than in the negative pressure generating pipe, reducing the amount of water discharged and suppressing the formation of large bubbles, thereby suppressing the aggregation of ultra-fine bubbles. Activated water swirling clockwise from the tip of the nozzle is discharged into the water stored in the water tank 300 (see FIG. 4(A)). This vortex causes some of the ultra-fine bubbles to re-aggregate due to collisions with the air bubbles 201 or with each other, and they rise to the surface of the water and disappear, just like the large air bubbles 201.

[0051] Here, a nozzle equipped with a rectifying means (hereinafter referred to as a rectifying nozzle 40) will be described with reference to Fig. 3. The rectifying means 41 has a plurality of spiral flow paths 42, and is positioned upstream of the throttle section 22. Specifically, the rectifying means is inserted into the inner tube 25 from the upstream side of the first flow rate adjustment pipe 24. Here, the rectifying means is manufactured using a thermosetting resin by a 3D printer, and is irradiated with terahertz waves.

[0052] The straightening nozzle 40 has three spiral flow paths 42 formed at equal intervals around its central axis 43 (see FIG. 3(B)). The spiral flow paths 42 are twisted counterclockwise around the central axis 43 from the inlet 44 to the outlet 45 so that the phase difference is 180 degrees, and straighten the clockwise vortex generated at the discharge port of the submersible pump.

[0053] In the flow straightening means 41, the contact area between the activated water and the flow path wall is increased compared to the nozzle 20 without the flow straightening means, which increases the resistance when the water flows and reduces the flow rate of the activated water. Therefore, to prevent a significant reduction in the flow rate, the length of the flow straightening means 41 is set to be between two and three times its outer diameter. Specifically, the length of the flow straightening means is set to be about 25 mm to about 30 mm, and the diameter is set to be about 10 mm to 15 mm.

[0054] As a result, the straightening nozzle 40 can reduce the flow rate of water within a range that allows negative pressure to be generated, while increasing the contact time between the water and the flow path wall that radiates the terahertz waves, thereby more finely breaking down clusters caused by the attractive interaction of water and generating more ultra-fine bubbles 200 than a nozzle 20 without straightening means (see Figure 3).

[0055] Furthermore, since the vortex is rectified by the rectification means, the activated water containing the fine bubbles is discharged from the rectification nozzle 40 in a non-swirling state, so that the discharged fine bubbles are less likely to collide with each other and are less likely to aggregate into large bubbles with a short dissolution time (see Figure 4(B)).

[0056] (Bubble count test 1) In bubble count measurement test 1, 50 liters of pure water was stored in a rectangular water storage container, and the submersible pump 10 and nozzle 20 were immersed and operated for 30 minutes to measure the number and diameter of bubbles dissolved per mL of water. The test results are shown in Table 1 and Figure 5. The submersible pump had a discharge rate of 80 L / min and a head of 5 m. In each table below, the leftmost column indicates the corresponding test. Table 1 shows the total number of bubbles less than 0.1 μm that remain dissolved for a long time, the number of ultrafine bubbles with a diameter of less than 1 μm as specified in JIS B 8741-1, and the number of other bubbles.

[0057] Each figure in Figure 5 is a graph showing the relationship between bubble diameter and the number of bubbles generated in the generation device for each of the tests below. Figure 5(A) shows the case where terahertz waves were irradiated only to the nozzle (hereinafter referred to as test condition (A)), Figure 5(B) shows the case where terahertz waves were irradiated not only to the nozzle but also to the underwater pump (hereinafter referred to as test condition (B)), and Figure 5(C) shows the case where a rectifying nozzle irradiated with terahertz waves was added to test condition (B) (hereinafter referred to as test condition (C)).

[0058] Measurements of the number and diameter of bubbles were carried out using a laser diffraction particle size distribution analyzer in accordance with Japanese Industrial Standards "JIS B 8741-2" and "JIS Z 8825-1." The test was conducted at the Niigata Prefectural Industrial Technology Research Institute. The test date was March 4, 2024. The measuring device used was the "SALD-7500X10" manufactured by Shimadzu Corporation.

[0059] [Table 1] TIFF2025165448000013.tif49155

[0060] Under test condition (A), it was confirmed that almost all of the bubbles dissolved in the water were ultrafine bubbles with a diameter of less than 1 μm as specified in JIS B 8741-1.On the other hand, the number of ultrafine bubbles less than 0.1 μm, which remain dissolved for a long time, was only 800,114 bubbles / mL, accounting for only about 2.3% of the total number of ultrafine bubbles.

[0061] Under test condition (B), almost all of the dissolved microbubbles were ultrafine bubbles with a diameter of less than 1 μm. The number of ultrafine bubbles was 166,612,662 bubbles / mL, approximately five times that under test condition (A). Furthermore, the number of ultrafine bubbles less than 0.1 μm, which remained dissolved for a longer period of time, was 59,245,921 bubbles / mL, a significant increase of approximately 74 times that of test condition (A).

[0062] Furthermore, the number of bubbles with a diameter of less than 0.1 μm was approximately 35.5% of the total number of ultrafine bubbles, a significant increase of approximately 15 times that of test condition (A). The only difference between test conditions (A) and (B) was whether or not terahertz waves were irradiated to the submersible pump. These results confirmed that irradiating the submersible pump with terahertz waves, in addition to the nozzle, was effective in increasing the number of ultrafine bubbles generated and extending the duration of bubble dissolution.

[0063] Under test condition (C), almost all of the dissolved microbubbles were ultrafine bubbles with a diameter of less than 1 μm. The number of ultrafine bubbles with a diameter of less than 1 μm was 642,050,679 bubbles / mL, approximately 3.8 times that under test condition (B). For ultrafine bubbles with a diameter of less than 0.1 μm, which remain dissolved for a longer period of time, the number was 221,574,322 bubbles / mL, approximately 3.7 times that under test condition (B).

[0064] The only difference between test conditions (B) and (C) is whether or not the nozzle is equipped with a flow straightening device. These results confirm that the spiral flow path that constitutes the flow straightening device, which straightens the vortexes generated in the activated water, is even more effective in suppressing the re-aggregation of fine bubbles. In particular, it was confirmed that there is a significant effect in increasing the number of ultrafine bubbles with a diameter of 0.1 μm or less.

[0065] (pH value measurement test 1) In pH value measurement test 1, the water after bubble number measurement test 1 was used as the measurement target, and the pH value and water temperature were measured. The test results are shown in Table 2. pH value measurement test 1 was conducted by the applicant himself immediately after bubble number measurement test 1. The test machine was a pH meter manufactured by Horiba, Ltd.

[0066] The pH value and water temperature at the start of the test were the pH value and temperature of the pure water stored in the storage container, with the pH value being 6.140 and the water temperature being 10.0°C. At the start of the test, the pH of the pure water was 6.14, which is less than 7.0 because carbon dioxide in the air dissolved in the pure water, causing the pH value to drop.

[0067] [Table 2] TIFF2025165448000014.tif51157

[0068] Under test condition (A), the pH value increased by about 0.11 compared to pure water. Under (B), the pH value decreased by about 0.04 compared to pure water, and under test condition (C), the pH value decreased by about 0.12 compared to pure water. In either case, the pH value of the pure water was hardly changed. According to the present invention, unlike Patent Documents 1 to 3 mentioned above, it is possible to produce water containing a large number of ultra-fine bubbles without changing the pH value of pure water, and it has been demonstrated that this is suitable for promoting the growth of agricultural crops.

[0069] (pH value measurement test 2) In pH value measurement test 2, we verified whether the change in the pH value of water differed depending on the type of water in which ultrafine bubbles were generated. The four types of water tested were pure water, aquaculture water taken from a fish farm in Joetsu City, Niigata Prefecture, tap water from Joetsu City, Niigata Prefecture, and lake water taken from Lake Nojiri in Nagano Prefecture. The test results are shown in Table 3. For the generator, test condition (B) was used, in which terahertz light was irradiated onto the entire nozzle and submersible pump, and the operating time of the submersible pump was standardized to 30 minutes.

[0070] pH measurements were performed using the glass electrode method in accordance with Japanese Industrial Standard "JIS K 0102 12.1." The test was conducted and conducted at the Joetsu Environmental Science Center, a general incorporated foundation. The test date and water intake date were February 7, 2024 for pure water and aquaculture water, and February 19, 2024 for tap water and lake water.

[0071] [Table 3] TIFF2025165448000015.tif41158

[0072] The pH value of pure water increased from approximately 5.8 to 6.0, but the increase was only approximately 0.2. The pH value of aquaculture water increased from approximately 7.4 to 7.6, but the increase was only approximately 0.2. The pH value of tap water decreased from approximately 5.6 to 5.5, but the decrease was only approximately 0.1. The pH value of lake water increased from approximately 6.0 to 6.1, but the increase was only approximately 0.1.

[0073] These test results confirmed that the ultra-fine bubble generator of the present invention causes almost no change in the pH value of raw water, whether it is weakly acidic or weakly alkaline. When applied to agricultural water, ultra-fine bubbles can promote plant growth without inhibiting the absorption of the three major nutrients and minerals essential for crop growth. When applied to aquaculture ponds, the dissolved oxygen concentration can be increased without changing the growth environment of fish and shellfish.

[0074] (Bubble count test 2) In bubble count measurement test 2, the change over time in the number of dissolved bubbles generated was measured in the same manner as in (bubble count measurement test 1). Water ejected from the nozzle of the generator was circulated in a storage container, and the change over time in the number of dissolved bubbles per mL of water was measured. The test results are shown in Table 4 and Figure 6. Specifically, 20 liters of pure water was stored in a cylindrical water storage container, and the submersible pump and nozzle were immersed in the water, and water was ejected toward the cylindrical wall to generate a circulating flow.

[0075] Under test condition (B) of the generator, in which terahertz waves were irradiated onto the entire nozzle and submersible pump, the change in the number of dissolved bubbles generated over time was measured. Table 4 shows the number of bubbles after 30 minutes and 60 minutes under test condition (B). Figure 6(B-1) graphs the number and distribution of bubbles after 30 minutes, and Figure 6(B-2) graphs the number and distribution of bubbles after 60 minutes.

[0076] [Table 4] TIFF2025165448000016.tif30150

[0077] According to the results of bubble count test 2, under test condition (B), the number of bubbles increased even after 30 minutes, and even after 60 minutes (see Figure 6(B-2)), the number of bubbles with a diameter of less than 1 μm was approximately 9.4 times higher, and the number of bubbles with a diameter of less than 0.1 μm was approximately 16.4 times higher, compared to the number after 30 minutes (see Figure 6(B-1)). These results confirmed that the generator of the present invention is effective in generating and maintaining ultrafine bubbles in an environment where water is continuously circulated, such as an aquaculture pond. [Example]

[0078] In the second embodiment, a water circulation system 100 will be described with reference to Fig. 7. Fig. 7 shows a plan view of a water circulation system in which generators are arranged in a ring shape in an aquaculture pond.

[0079] In the water circulation system 100, multiple generators are arranged in a ring shape to fit the area of ​​the aquaculture pond. For example, in a 20m long and 4m wide aquaculture pond, the generators are arranged at intervals of approximately 2m. The water discharged from the nozzles of each generator 1 is directed toward the adjacent generator downstream so that a circulating flow of water is created.

[0080] As shown in the above-mentioned bubble count measurement test 2, the generator 1 of the present invention can significantly increase the number of ultrafine bubbles by circulating ultrafine bubble-containing water. In the water circulation system 100, multiple generators 1, 1... are arranged in a ring shape to circulate ultrafine bubble-containing water, so that re-aggregation of ultrafine bubbles can be prevented and the dissolved oxygen concentration can be efficiently increased even in aquaculture ponds with large volumes.

[0081] (others) The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical scope of the present invention is not limited to the above description, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0082] 1...Generator, 100...Water circulation system, 10...Submersible pump, 20...Nozzle, 11...Main body, 12...Outlet, 13...Cable 21...air introduction pipe, 22...throttling portion, 23...pipe body, 24...first flow rate adjustment pipe, 25... internal intubation tube, 26... negative pressure generating tube, 27... second flow rate adjusting tube, 28... attachment part, 29...insertion portion, 30...hole, 40... flow straightening nozzle, 41... flow straightening means, 42... spiral flow path, 43... central axis, 44...Inlet, 45...Outlet, 200...Ultra-fine bubbles, 201...Air bubbles, 300...Water tank

Claims

1. An ultra-fine bubble generator consisting of a submersible pump equipped with a nozzle for discharging water, A generating device in which terahertz waves in a frequency band of 32 THz or more and 38 THz or less are irradiated onto the underwater pump and the nozzle by a terahertz wave irradiation device, The nozzle includes an air suction means and an air atomization means, the suction means comprises an air introduction tube, The air introduction pipe introduces the air into the nozzle by negative pressure generated by the water flow pressure-fed by the submersible pump, The submersible pump and the nozzle radiate terahertz waves in the frequency band that resonate with water molecules to the pumped water, thereby disrupting the attractive interaction between adjacent water molecules and activating the water; the atomizing means comprises a throttle portion provided adjacent to the upstream side of the air inlet pipe, The throttle section micronizes the introduced air to generate ultrafine bubbles, which are dissolved in the water. A generating device characterized by:

2. the nozzle is provided with a flow straightening means for straightening a vortex generated at a discharge port by the pressure-fed water, the flow straightening means is composed of a plurality of spiral flow paths provided upstream of the suction means, each of the spiral flow paths is evenly distributed around the central axis of the nozzle and is spirally twisted in a direction opposite to the rotation direction of the vortex; The pressurized water is rectified and discharged from the spiral flow path.

2. The generator of claim 1.

3. A water circulation system, The apparatus includes a plurality of the generators according to claim 1 or claim 2, The water discharged from the generator disposed upstream of each of the generators is sucked into the generator disposed downstream of each of the generators, thereby circulating the water.

2. The generator of claim 1.

4. A nozzle attached to a submersible pump, the nozzle includes, in order from the upstream side, a flow straightening means for straightening a vortex generated at a discharge port by the pressure-fed water, an air atomizing means, and an air suction means; the flow straightening means has a plurality of spiral flow paths, each of the spiral flow paths is evenly distributed around the central axis of the nozzle and is spirally twisted in a direction opposite to the rotation direction of the vortex; the suction means comprises an air introduction tube, The air introduction pipe introduces the air into the nozzle by negative pressure generated by the water flow pressure-fed by the submersible pump, the atomizing means comprises a throttle portion provided adjacent to the upstream side of the air inlet pipe, The throttle section atomizes the introduced air to generate fine bubbles, which are dissolved in the water. A nozzle characterized by:

5. The spiral flow path is characterized in that it is made up of three spiral flow paths, each of which has the same shape.

5. The nozzle of claim 4.

6. the length of the flow path forming the rectifying means is set to be two to three times the outer diameter of the flow path, The phase shift of the inlet and outlet of the spiral flow path is 180 degrees counterclockwise.

6. The nozzle according to claim 4 or claim 5.

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