Method and apparatus for generating high-concentration ultrafine bubble water, and method for effectively utilizing ultrafine bubble water.

Abstract

Suppressing methane gas emissions from paddy rice cultivation is extremely important as a measure against global warming. The challenge here is to achieve both improved rice productivity and environmental protection. Specifically, this involves developing a device that can generate large quantities of high-concentration ultrafine bubble (UFB) water in a short time, by adding methane gas emission suppression to the UFB water. [Solution] The UFB generating apparatus of the present invention incorporates a variable-speed rotary stirring device into a UFB generation tank, and this tank is filled with sandy material. By supplying gas and water to this tank at high pressure, the sandy material layer of gas, water, and sandy material is liquefied. By rapidly rotating this liquefied layer with the rotary stirring device, the gas is confined in the pore water of the liquefied layer and then finely fragmented. Furthermore, by using sandy steel slag as the sandy material, in addition to the UFB effect, methane generation due to silica, lime, and iron oxide is suppressed and crop yields are improved.

Description

Technical Field

[0001] The present invention relates to a method for producing a large amount of high-concentration ultrafine bubble water, a production apparatus therefor, and a method for effectively utilizing ultrafine bubble water.

Background Art

[0002] An urgent theme in global environmental issues is global warming. The Act on Promotion of Global Warming Countermeasures specifies the achievement of carbon neutrality in 2050, and efforts to combat global warming are regulated by law. In addition, the Japanese government announced in April 2021 that it aims to reduce greenhouse gas emissions by 46% compared to 2013 by 2030, and will continue to challenge itself to reach a further 50% reduction. It can be said that efforts to combat global warming are now an important mission common to all industries and sectors.

[0003] Fine bubbles are a general term for microbubbles with a particle size of 100 μm to 1 μm and ultrafine bubbles with a particle size of less than 1 μm. Fine fine bubbles have characteristic properties that cannot be obtained with ordinary milli- and centibubbles. For example, aeration uses air millibubbles to supply oxygen and is used for water purification. Similarly, if fine bubbles are used, they will stay in water longer than ordinary millibubbles. Therefore, the amount of oxygen scattered into the atmosphere is small, and the supply of oxygen lasts longer. In particular, ultrafine bubbles can stay in water for a long time, sometimes for several months.

[0004] A particularly notable function of microbubbles is the function of generating free radicals when they disappear and decomposing various chemical substances present in an aqueous solution. The notable function of ultrafine bubbles is a gas encapsulation function according to the purpose. For example, air has effects such as improving the efficiency of washing, cleaning, and hydroponics, oxygen has effects such as fish farming, activating microorganisms, and increasing the amount of dissolved oxygen, and nitrogen has effects such as preventing oxidation and maintaining freshness. In addition, the bioactive function has the effect of facilitating the absorption of nutrients from the roots and promoting plant growth in agriculture, and the effect of increasing the amount of dissolved oxygen in the fish farming pond and improving productivity in fish farming.

[0005] Currently, the use of fine bubbles is expanding in many fields, including food, medicine, agriculture, fisheries, manufacturing, and the environment. Many fine bubble application technologies align with one of the 17 Sustainable Development Goals (SDGs) set by the United Nations in 2015, and are expected to be effective technologies for achieving the SDGs.

[0006] Methane, one of the greenhouse gases, has a greenhouse effect about 27 times greater than carbon dioxide, and rice cultivation accounts for about 42% of methane emissions in Japan. Methods to reduce methane emissions from rice cultivation include mid-season drainage and intermittent irrigation, which involve introducing air into the soil. These methods require that irrigation and drainage be easy. However, such favorable conditions are not always available. Therefore, the use of ultrafine bubbles (sealing in air or oxygen) is expected to be another method to make paddy soil aerobic.

[0007] There are concerns that global warming will have various impacts on farmland, agricultural water, and land improvement facilities. One example of the impact of rising temperatures on agricultural water is the expected increase in eutrophication and algal blooms due to rising water temperatures in dam reservoirs and ponds. The use of ultrafine bubbles (using air or oxygen) is being considered as a countermeasure against algal blooms.

[0008] Various devices have been developed to generate ultrafine bubbles, also known as microbubbles or ultrafine bubbles. For example, methods for generating nano-sized bubbles with high stability in liquid include surfactant-added micropore methods and ultrasonic cavitation methods. Ultrafine bubble generators that utilize bubble generation through flow path shapes such as high-speed swirling, pressurized dissolution, and ejector types are also known.

[0009] When using micropores or ultrasound as methods for generating ultrafine bubbles as described above, it is difficult to produce high-quality, high-density bubbles, and the flow rate is limited. Therefore, there are problems with cost and other constraints regarding the feasibility of applying these technologies in the aforementioned fields. Furthermore, while ultrafine bubble generators that use bubble generation actions based on flow path shapes such as high-speed swirling, pressurized dissolution, and ejector types can generate ultrafine bubbles relatively easily, there is a problem in obtaining ultrafine bubbles of sufficient density to achieve high performance in each field. (See Patent Document 1)

[0010] In 2022, a new technology was announced that solved the problem of generating ultrafine bubbles at high density, which is the issue described above. This new technology's ultrafine bubble generation method is a turbulent, high-pressure bursting method using a special nozzle. This method generates ultrafine bubbles down to the nanoscale by cutting, severing, and crushing bubbles. Furthermore, it successfully generates ultrafine bubbles more efficiently than conventional technologies, resulting in reduced running costs. Its features include high quality, low running costs, high-volume generation in a short time, a greater number of ultrafine bubbles than existing commercially available products, and the ability to control bubble size and flow rate from micro to nanoscale. (See Patent Document 1)

[0011] Ultrafine bubble generators can be operated in two ways: batch operation and continuous operation. Batch operation involves completely replacing the contents of the device each time, allowing for thorough cleaning and ensuring hygiene. Larger generators are suitable for mass production, but the generator and equipment costs are high. There is high demand for these in industries where hygiene is paramount, such as pharmaceuticals and food. In contrast, continuous operation uses a special nozzle to continuously generate bubbles. This method is relatively inexpensive. However, as described in Patent Document 1, devices capable of short-time, high-volume production have recently become available. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Patent No. 7092358 [Overview of the project] [Problems that the invention aims to solve]

[0013] Reducing methane gas emissions is extremely important as a measure against global warming. Here, the major challenge is to achieve both improved agricultural productivity and measures against global warming. Specifically, we consider paddy rice cultivation (paddy rice) to reduce methane gas emissions. The reason is that if the challenges in large-scale paddy rice cultivation can be solved by utilizing ultrafine bubbles, productivity improvements can be expected in crop agriculture and fisheries as well. It can also be applied to improving the water quality of canals, lakes, and reservoirs. It should be noted that the ultrafine bubble generator needs to be capable of generating large quantities in a short time, which is necessary for large-scale paddy rice cultivation. The large-scale generation referred to here is different from the scale of conventional methods. It is a large-scale generation that has limitations with special nozzle methods.

[0014] The aim is to reduce methane emissions from rice cultivation and improve productivity through the use of ultrafine bubble water (with air or oxygen encapsulation). While there are expectations for the use of ultrafine bubbles, there are challenges in its operation. These are cost and energy consumption. Costs include the cost of specialized ultrafine bubble water generation equipment and ancillary equipment. Energy consumption includes the operation of the generation equipment, pump operation, and maintenance costs, and applying it to large-scale paddy rice cultivation will require a large initial investment. Cost-effectiveness must be achieved. The challenges in paddy rice cultivation can be summarized as follows: (1) a large amount of ultrafine bubble water is required. (2) The effect must be commensurate with the expenditure. (3) Environmental evaluation regarding the suppression of methane gas generation is required. Furthermore, and this is a challenge unique to paddy rice cultivation, in order to maximize the effect of ultrafine bubbles, it is necessary to find a method for uniformly distributing them in the paddy field. This is to ensure that the ultrafine bubbles are efficiently distributed to the root zone of the rice plants.

[0015] The objective of this invention in paddy rice cultivation is the rational reduction of initial and running costs. This is a common challenge for all businesses. Ideally, the cost-effectiveness of the environmental assessment regarding methane gas emission suppression should be achieved even without considering it. The means that the invention aims to solve

[0016] The problems of the present invention will be reorganized from the perspective of solutions. (1) A generator for the large-scale use of ultrafine bubble water, (2) manufacturing costs of the generator, (3) operating costs, and (4) maintenance costs. Ultimately, the goal is to develop a device that is highly efficient, as inexpensive as possible, and capable of generating large quantities of fine bubble water in a short time. When considering (1), (2) to (4) also become relevant. The requirements for the generator are (1) to enable mass production beyond that of batch-type devices, (3) for easy transport and movement of the device in paddy rice cultivation work, and (4) for infrequent malfunctions and easy repair if malfunctions occur. Meeting these conditions, (2) the generator needs to be for large-scale use, easily transportable and moveable, have few malfunctions, and have reduced manufacturing costs.

[0017] The solution to this problem is a generator that continuously produces large quantities of high-concentration fine bubble water. The effects of high concentration and continuous generation significantly reduce the size of the generator, thereby lowering manufacturing costs and making it easier to transport and move. For example, the generator can be made small enough to be mounted on a light truck. Maintenance costs will be reduced by simplifying the structure of the generator so that it is less prone to breakdowns and easier to repair.

[0018] In the method for generating high-concentration ultrafine bubble water, the fine bubble water generation tank of the fine bubble water generation apparatus incorporates a rotary stirring device powered by a variable-speed motor, and this tank is filled with sand-like material, and the internal pressure of this tank can be maintained at a constant pressure. By supplying gas and water to this tank individually or as a mixed fluid at high pressure, the sand-like material layer of gas, water, and sand-like material is liquefied, and this liquefied layer can be rapidly rotated by the rotary stirring device. As a result, the gas is confined in the pore water of the liquefied layer and fragmented into ultrafine particles. Furthermore, by significantly increasing the permeability coefficient of the sand-like material through liquefaction, the time it takes for ultrafine bubble water to pass through the generation tank (generation time) is greatly reduced. Thus, the method for generating high-concentration ultrafine bubble water of the present invention is characterized by making maximum use of sand-like material and liquefaction. Note that the gas-water fluid is a newly added pore in addition to the initial pore. The amount of sand-like material to be filled is calculated by subtracting the equivalent amount of the supplied gas-water fluid.

[0019] In the aforementioned method for generating high-concentration ultrafine bubble water, a high-pressure jet of a gas-water mixed fluid is impacted onto a sandy layer from the nozzle of the fine bubble water generation tank to diffuse the gas. Simultaneously, this layer is transformed into a liquefied sandy layer of gas, water, and sand. A rotary agitator is rotated at the required time and high speed, and the interaction between the agitator blades and baffle plates fixed to the tank generates multiple horizontal shear surfaces and countless small, intense vortices in the liquefied sandy layer. This breaks down the gas trapped in the pore water of the sandy layer into ultrafine particles, thereby generating a large quantity of high-concentration ultrafine bubble water in a short time. Furthermore, the generation of ultrafine bubbles of any size is achieved by controlling the required rotation time and rotation speed of the rotary agitator. The characteristic feature of the present invention is that, in the liquefied sandy layer, the interaction between the agitator blades and baffle plates breaks down the gas trapped in the pore water into ultrafine particles.

[0020] The fundamental feature of the fine bubble water generation method of the present invention is that the fine bubble water generation tank, i.e., the stirring tank, is filled with sand-like material. In addition to sand, sand-like steel slag is used depending on the purpose. For food-related applications, hygienic sand-like material is used. There are three purposes for filling the fine bubble water generation tank with sand-like material. First, the specific gravity (≒3) of the sand-like particles is high; second, the liquefaction of the sand-like material is utilized; and third, gas is trapped in the pore water. During liquefaction, the sand-like material is added to the gas-water fluid (fluid specific gravity ≤1), resulting in a mixed fluid of gas, water, and sand-like material (fluid specific gravity ≒2). The stirring and mixing of the fluid with the added sand-like material fragments the gas into ultrafine particles through the interaction of the stirring blades and baffle plates. The power of gas fragmentation with added sand-like particles is proportional to the mass of the mixed fluid, so it is approximately twice as powerful. Furthermore, the energy of stirring and mixing is proportional to the square of the rotational speed. However, the power of crushing gas, water, and sandy materials cannot be evaluated by mass alone. This is due to the effect of confining the gas within the pore water and then crushing it. The use of liquefaction enabled high-speed rotation by reducing the shear force of the sandy material layer. Another important function is that it significantly increased the permeability coefficient, greatly shortening the passage time of ultrafine bubble water through the fiber bubble water generation tank, i.e., the ultrafine bubble water generation time. This will be described in detail in the section on embodiments for carrying out the invention.

[0021] Herein lies a description of the liquefaction method of the present invention. Liquefaction is defined as "a phenomenon in which liquefaction occurs when excess pore water pressure is generated due to some cause, and the excess pore water pressure becomes equal to the total stress, that is, when the effective stress becomes zero. During a major earthquake, liquefaction is observed in loose sandy ground. This is because the ground is repeatedly subjected to shear force by the earthquake vibration, compressing its volume and generating excess pore water pressure. The fine bubble water generation tank of the present invention is capable of maintaining a constant internal pressure. By supplying a gas-water mixed fluid at high pressure, the pore water pressure in the saturated sandy layer of gas, water, and sandy material is raised to the excess pore water pressure that causes liquefaction. For example, if the thickness of the saturated sandy layer in the tank is 0.5 m and the unit weight of this layer in water is 8.34 kN / m³ 3 Therefore, the effective stress at the bottom of the tank is 4.17 kN / m2 (0.04 atmospheres). The pore water pressure needs to be increased to this level.

[0022] Next, we will explain the mass production of high-concentration ultrafine bubbles according to the present invention. The method for generating fine bubbles according to the present invention is classified as a high-speed swirling method of a mixture of liquefied gas, water, and sand-like material. The principle is that in the vortices generated on the back of the plate and multiple horizontal shear surfaces due to the interaction of the stirring blade and baffle plate, the gas, which is confined in the pore water, is drawn into collisions and friction between sand-like particles, and is fragmented into ultrafine particles to generate ultrafine bubbles. The generation method of the present invention reliably fragments the gas into ultrafine particles even when the mixing ratio of gas and water is high. The bubble size, ranging from micro to nano size, is controlled by the rotation time and rotation speed. Ultrafine bubbles are generated at high speed rotation.

[0023] Here is an explanation of the interaction between the impeller and the baffle plate. The rotating surface of the impeller and the fixed surface of the baffle plate are in a positional relationship where they do not overlap when rotating. The mixed fluid of gas, water, and sandy material creates circular horizontal shear surfaces at the upper and lower ends of the baffle plate. In addition, negative pressure is generated on the back surface of the baffle plate, and countless small vortices are generated from its upper and lower ends, creating countless localized shear points. As mentioned above, the countless fine particles of sandy material draw in gas, collide and rub against each other, and are broken down into ultrafine particles. Without the baffle plate, the mixed fluid of gas, water, and sandy material would simply swirl. Gas fragmentation would hardly occur. The baffle plate has notches at its upper and lower ends. This increases and complicates the countless localized shear points of the vortices.

[0024] Next is an explanation of the mechanism for generating high-concentration ultrafine bubble water according to the present invention. As described above, innumerable sand-like particles entrain the gas confined in the gaps at horizontal shear planes and numerous local shear points, collide and rub against each other, and finely crush the gas. The gas crushing effect by the sand-like fine particles has a power that cannot be evaluated only by the mass of the sand-like particles and the mass of the gas-water-sand-like mixed fluid. This is contributed by the narrow gaps and the mass of the sand-like material. Here, compare the streamline shapes in the swirling of the gas-water mixed fluid and the gas-water-sand-like mixed fluid. The linear disturbances of both passing through the baffle plate that obstructs the flow are very different. The disturbance of the gas-water only mixed fluid is small. In contrast, the disturbance of the gas-water-sand-like mixed fluid with a large mass is intense. The gas confined in the gaps of the sand-like material has nowhere to escape. It is surely crushed into ultrafine gas, that is, high-concentration ultrafine bubble water. In the case of the gas-water mixed fluid with a small mass, most of the gas is pushed away by the dynamic water pressure generated by the baffle plate and does not reach shear, resulting in low-concentration ultrafine bubble water.

[0025] In the above-mentioned fine bubble water generating device, the generating device consists of a fine bubble water generating tank, a pressurized water supply device, and a pressurized gas supply device. A rotary stirring device powered by a variable speed motor is incorporated in the fine bubble water generating tank. Also, the fine bubble water generating tank is a special stirring tank, and its structure is relatively simple. The configuration of this tank is partitioned by a horizontal porous plate through which only gas and liquid can pass at either the top or bottom, or both, of the tank. It has a two- or three-tier structure of the main body tank and the connection tank. A baffle plate is fixed in the main body tank, filled with sand-like material, and a relief valve for restricting the water pressure of the fine bubble water is installed at the outlet of the fine bubble water in the connection tank. The device of the present invention is characterized in that it can maintain an excessive interstitial water pressure that reaches liquefaction of the interstitial water pressure of saturated sand-like material and can perform high-speed swirling with such a configuration.

[0026] Note that there are many possible combinations of the stirring blade and the baffle plate in terms of their shapes, dimensions, and arrangements. Also, in the horizontal perforated plate, the passage of gas and water causes an increase in water pressure due to the low water permeability of this plate. If it is a small-sized fine bubble water generating device, the effective stress of the saturated sand-like material is small and the excess pore water pressure that causes liquefaction is also small, so the relief valve can be omitted. In addition, a regulator is installed in each supply device. The role of this is to keep the fluctuating pressure within a certain range.

[0027] It is convenient that the set pressure of the relief valve is the pressure at which the saturated sand-like material liquefies due to excess pore water pressure. The shear resistance of the sand-like material is lost and the high-speed rotation of the rotary stirring device becomes easy. However, as described above, the relief valve can be omitted when stirring is easy. Note that there are two types of gas and water supply methods: individual fluid supply and mixed fluid supply. In the case of the mixed supply method, gas and water are mixed before being supplied to the fine bubble water generating tank. First, the pressurized water supply device is connected to the jet outlet of the connection tank of the fine bubble water generating tank with a pressurized water hose. Then, the pressurized gas supply device is connected to the middle of the pressurized water hose with a pressurized gas hose, where they become a mixed fluid. In contrast, in the case of the individual supply method, water is connected to the jet outlet of the connection tank with a pressurized water hose. And gas is connected inside the horizontal porous plate. In this case, the horizontal porous plate requires a large thickness, so it is stacked in two layers. Also, the supply devices for pressurized water and pressurized gas can adjust their respective flow rates and pressures. Although it will be described later, gas dissolution can be promoted by increasing the gas pressure.

[0028] In the aforementioned method for generating high-concentration ultrafine bubble water, the gas pressure used to create the gas-water mixed fluid is set even higher than the water pressure to facilitate the mixing of gas and water at the joints of each pumping pipe, thereby significantly increasing gas dissolution. Furthermore, the pumping water volume and pumping gas volume are set to the mixing ratio considering the gas solubility. A key feature of the present invention's method for generating high-concentration ultrafine bubble water is setting the gas pressure high and determining the mixing ratio while considering the gas solubility. Note that, according to Henry's Law, if the temperature is constant, the mass of gas dissolved in a given amount of solvent is proportional to the pressure of that gas.

[0029] In the method for generating microbubble water that generates free radicals, the rotation time and rotation speed of the rotary stirring device are set to target the diameter of microbubbles that are most likely to generate free radicals in the fine bubble water generation device described above. The characteristic of the microbubble water generation method of the present invention is that it targets the diameter of fine bubbles that are most likely to generate free radicals. Free radicals are most likely to be generated in microbubbles with a diameter in the range of approximately 1 μm to 10 μm.

[0030] In a method for producing high-concentration ultrafine bubble water containing substances leached from steel slag, by using sandy steel slag as the sandy material in the fine bubble water production tank, high-concentration ultrafine bubble water is produced that, in addition to the effects of ultrafine bubbles, also has the effects of suppressing methane generation due to silica, lime, and iron oxide, and improving crop health and yield. The characteristic of the ultrafine bubble water production method of the present invention lies in the combined effect of the effects of high-concentration ultrafine bubble water and the effects of steel slag.

[0031] In a method for effectively utilizing the aforementioned high-concentration ultrafine bubble water containing eluted steel slag for paddy rice cultivation, the amount of ultrafine bubble water injected relative to the inflow of paddy water is determined based on a planned dilution ratio at the upstream part of the water inlet of the paddy field cultivation area, both at the initial water inlet and at the water inlet after mid-season drainage. By uniformly dispersing the ultrafine bubble water underwater throughout the paddy field cultivation area using the flow of the incoming water, the planned high-concentration ultrafine bubble water containing silicic acid, lime, and iron ions, along with oxygen and nitrogen, is efficiently distributed to the root zone of the rice plants. The characteristic feature of this invention lies in the underwater dispersal of the high-concentration ultrafine bubble water using the flow of the incoming water. Note that the ultrafine bubble water of this invention is highly concentrated. It will be used after being appropriately diluted.

[0032] The most important aspects of effectively utilizing ultrafine bubble (UFB) water containing leached steel slag in paddy rice cultivation are: (1) uniformly distributing the UFB water throughout the entire paddy field; and (2) ensuring that the leached substances from the steel slag and the UFB reach the rice root zone. (1) utilizes the flow of incoming water. (2) involves distributing the water underwater during the initial water inflow of the paddy field and again after the mid-season drainage. The leached substances from the steel slag and the UFB are distributed to the rice root zone using the flow of incoming water. This is done during the initial water inflow of the paddy field and again after the mid-season drainage. At this time, the paddy field is particularly dry after the mid-season drainage. The purpose of mid-season drainage is to remove gases (methane and hydrogen sulfide) from the paddy field and replenish oxygen to improve root growth. The soil is dried until cracks appear. When water is introduced under these conditions, the leached substances from the steel slag and the oxygen and nitrogen UFB will be efficiently distributed to the rice root zone.

[0033] The advantages of using steel slag include the presence of silica, lime, and iron oxide. Silicic acid, when absorbed by rice plants, strengthens their leaves and stems and increases the efficiency of photosynthesis. Silicic acid is also expected to reduce stress on the rice plants. Lime adjusts the soil pH and increases alkalinity, allowing nutrients in the soil to be absorbed more efficiently by the rice plants. Iron oxide is converted into iron ions through reduction reactions in paddy soil, which are then absorbed by the rice roots. Iron is an important mineral for rice growth. Furthermore, iron is important because it suppresses methane emissions through reduction reactions in paddy soil. In addition, it is known that iron-reducing bacteria involved in iron reduction and methane-producing bacteria involved in methane production are in a competitive relationship.

[0034] In a method for effectively utilizing fine bubble water to improve the water quality of canals, lakes, ponds, etc., the aforementioned high-concentration ultrafine bubble water generator is used. The rotational stirring device is controlled to target the diameter of the fine bubbles that generate free radicals, and the rotation time and speed are set to produce this diameter. The speed is then periodically changed within a certain range around this rotation speed. This alternately generates high-concentration microbubble water and high-concentration ultrafine bubble water, which generate free radicals with different lifespans. Fine bubble water incorporating the water quality improvement effects of both is then sprayed into the water. The characteristic of this method of effective utilization is that it generates fine bubbles with different lifespans to prolong the free radical effect and the oxygen fine bubble effect.

[0035] To summarize the water quality improvement and algal bloom control effects of oxygen fine bubbles (oxygen microbubbles and oxygen ultrafine bubbles), they involve increased oxygen supply and physical effects. Increasing the amount of oxygen-supplying oxygen fine bubbles increases the oxygen concentration in the water. This promotes the activity of microorganisms other than algae, playing a balance that suppresses the growth of algae. Secondly, when fine bubbles are generated in water, their movement and buoyancy also have the effect of breaking down algal colonies. In other words, oxygen fine bubbles not only directly destroy algal cells, but also have a multifaceted effect of improving overall water quality and preventing excessive algal blooms.

[0036] Free radicals are most frequently generated in microbubbles with a diameter of approximately 1 μm to 10 μm. Diameters smaller than approximately 1 μm are in the ultrafine bubble region. Therefore, the standard fine bubble diameter here is 1 μm. By targeting 1 μm and periodically changing the rotation speed within a constant range, microbubble water with free radical generation and ultrafine bubble water are alternately generated. The constant range is, for example, 10 μm to 10 -1 It is μm.

[0037] This device incorporates a miniaturized high-concentration ultrafine bubble water generator, as described above, into electrical appliances that require water for their function, effectively utilizing the effects of free radicals. The effects of free radicals are as described above. Examples include evaporative coolers. It can also be installed in water tanks in apartment buildings to improve hygiene management. Furthermore, fine bubbles are said to have the effect of making water taste smoother. Effects of the invention

[0038] The present invention provides a method for generating high-concentration fine bubble water, in which liquefied gas, water, and sand-like material are rapidly rotated in a generation tank using a rotary agitator. The gas is confined within the interstitial water of the sand-like material, and is then fragmented into ultrafine particles by the interaction of the agitator blades and baffle plates, generating a large quantity of high-concentration ultrafine bubbles in a short time. Furthermore, the bubble size, ranging from micro to nano-sized, is controlled by the rotation time and rotation speed. This makes it possible to provide the ultrafine bubble water required even in large-scale paddy rice cultivation.

[0039] Furthermore, the fine bubble water is filled into the production tank of the fine bubble water generating apparatus of the present invention. sandy substanceBy using sandy steel slag, it is possible to generate large quantities of highly concentrated ultrafine bubble water containing substances dissolved from the steel slag in a short time. The dissolved substances include silica, lime, and iron oxide, and in addition to the effects of ultrafine bubbles, it also has effects such as suppressing methane gas generation and improving crop health and yield, making it an effective method for paddy rice cultivation.

[0040] Furthermore, by targeting a bubble diameter of 1 μm and controlling the rotation time and rotation speed of the water-gas mixture to generate fine bubbles of this diameter, and by periodically changing the rotation speed within a certain range, mainly at a speed that yields a high rate of fine bubble generation, high-concentration microbubble water and high-concentration ultrafine bubble water are alternately generated, generating a large amount of free radicals in a very short time. This generates fine bubbles with different lifespans, prolonging the free radical effect and oxygen fine bubble effect, and is an effective method for improving the water quality of canals, lakes, reservoirs, etc. in a short period of time. [Brief explanation of the drawing]

[0041] [Figure 1] Vertical cross-sectional view of the large-scale ultrafine bubble water generation tank of the present invention [Figure 2] Similarly, a vertical cross-sectional view of a medium-sized ultrafine bubble water generation tank. [Figure 3] A vertical cross-sectional view of a small ultrafine bubble water generation tank. [Figure 4] Similarly, horizontal cross-sectional view (cross-sectional view along line AA in Figures 1-3) [Figure 5] Similarly, a schematic diagram showing the overall configuration of a large-scale ultrafine bubble water generator. [Modes for carrying out the invention]

[0042] The embodiments of the present invention will be described below with reference to Figures 1 to 5.

[0043] Figure 1 is a vertical cross-sectional view of the large ultrafine bubble (UFB) water generation tank of the present invention. The UFB water generation tank is a special agitated tank. In the figure, 2 is the UFB water generation tank, 20 is the rotary agitator, 200 is the motor, 201 is the transmission, 202 is the agitator blade, 203 is the baffle plate, 21 is the main tank, 22 is the connecting tank, 23 is the horizontal porous plate, 24 is the relief valve, and 50 is the automatic gate valve. Figure 1 shows an example of a large UFB water generation tank 2. Its structure is a three-tiered structure with the main tank 21 and connecting tanks 22 above and below it, and the agitator blade 202 and baffle plate 203 are arranged in three stages. There are also two methods for supplying gas and water: an individual method and a mixed method. The example in Figure 1 is the individual supply method. In the case of the individual supply method, it is a three-tiered structure, and in the case of mixed supply, it is a two-tiered structure. Also, the UFB water flow can be upward or downward, and the example in Figure 1 is downward. They can be used for different purposes, such as agriculture, environmental applications, and electrical appliances. Note that although the horizontal porous plate 23 appears to be separated into two pieces in the diagram, the plate is actually a single, donut-shaped sheet.

[0044] Figure 2 is a vertical cross-sectional view of a medium-sized UFB water generation tank 2, which also shows an example of a medium-sized tank 2. Its structure is a two-tiered structure with a connecting tank 22 below the main tank 21, and the stirring blades 202 and baffle plates 203 are arranged in two stages. The supply method is a mixing method, and the UFB water flows downwards.

[0045] Figure 3 is a vertical cross-sectional view of a small UFB water generation tank 2, which also shows an example of a small tank 2. Its structure is a two-tiered structure with a connecting tank 22 on top of the main tank 21, and the stirring blade 202 and baffle plate 203 are in a single stage. The supply method is a mixing method, and the UFB water flow is upward. In the case of a small tank, the relief valve 24 is omitted.

[0046] Figure 4 is a horizontal cross-sectional view (cross-sectional view along line AA in Figures 1-3). The baffle plate 203 shown in the figure consists of four plates fixed to a hollow tube at the center, with the opposite ends fixed to the generation tank 2. The stirring blade 202 and the baffle plate 203 are both plate-shaped, but numerous combinations are possible based on their shape, dimensions, and arrangement. For example, the shape of the stirring blade 202 can be screw-shaped instead of plate-shaped. While the plate shape has a small cavitation effect that generates fine bubbles, it has the advantage of low vibration, noise, and erosion. There are pros and cons to each. Intermediate shapes can also be considered.

[0047] Figure 5 is a schematic diagram illustrating the overall configuration of a large-scale ultrafine bubble water generator. In the figure, 1 is the ultrafine bubble (UFB) water generator, 3 is the pressurized water supply device, 30 is the raw water, 31 is the pressurized water hose, 4 is the pressurized gas supply device (compressor), 40 is the buffer tank, 41 is the pressurized gas hose, and 50 is the automatic shut-off valve. The large-scale UFB water generator 1 in Figure 5 is intended for the effective use of high-concentration ultrafine bubble water in paddy rice cultivation and for improving the water quality of canals, lakes, reservoirs, etc. The work process for effective utilization will be explained using paddy rice cultivation as an example.

[0048] Here, we consider the time it takes for UFB water to pass through the sandy layer filling the main tank 21 of the UFB water generation tank 2, that is, the time it takes for the pore water to be replaced = the UFB water generation time. The main tank is assumed to have a height of 0.8m and an inner diameter of 1.6m. Assuming a pore ratio of 0.3 in the sandy material, a permeability coefficient k of 0.1 to 0.01 cm / s, and a pumping pressure of 0.5 MPa (0.5 atmospheres), the time is 0.64 minutes when k=0.1 and 6.4 minutes when k=0.01. When liquefaction occurs, the permeability coefficient increases by 2 to 10 times with increasing severity. If it increases by 5 times, the time is 0.13 minutes when k=0.1 and 1.3 minutes when k=0.01. If the air-gas mixing ratio is 1 / 3, then 0.37 m³ of ultrafine bubble water containing 25% will be produced in 1 minute. 3 It is generated. Changing the height of the main body will significantly change the passage time. It is advisable to plan according to the application. Here, we wanted a high-speed turning time of 1 minute, so we chose this height.

[0049] The work process is as follows: First, the sandy material is sandy steel slag. The sealed gas is air. Here, the raw water 30 is irrigation water. The pressurized water supply device 3 is installed upstream of the water inlet of the paddy field cultivation area, and the UFB water injection point is downstream of this supply device 3. The pore ratio of the sandy material is about 0.3. The conditions for generating UFB water are an air-to-water ratio of 1 / 3 and a swirling time of about 1 minute. The work process is as follows: (1) Open the three automatic gate valves 50, pressurize the air-gas to fill the entire main tank 21 with the air-water fluid, and saturate the sandy material. (2) Rapidly swirl the liquefied air-water-sandy material for about 1 minute. (3) The pore water is automatically replaced every 1.3 minutes. Air-water is continuously pressurized to push out the air-UFB water, and the sandy material is saturated with new air-water. Repeat the above process. Furthermore, the structural characteristics of the UFB water generation device 1 vary greatly depending on factors such as the height of the UFB water generation tank 2 and the combination of the stirring blades 202 and baffle plates 203. [Explanation of Symbols]

[0050] 1. Ultrafine bubble (UFB) water generator 2 UFB water generation tanks 20 Rotary stirring device 200 Variable Speed ​​Motor 201 transmission 202 Stirring blade 203 Baffle Plate 21 Main Tank 22 Connecting Tanks 23 Horizontal porous panels 24 Relief valves 3. Pressurized water supply device 30 Raw water 31 Pressurized water hose 4. Pressurized gas supply device (compressor) 40 Buffer Tanks 41 Pressurized gas hose 50 Automatic gate valve

Claims

1. A method for generating high-concentration ultrafine bubble water, characterized in that the fine bubble water generation tank of the fine bubble water generation apparatus incorporates a rotary stirring device powered by a variable-speed motor, and this tank is filled with sandy material, and the internal pressure of this tank can be maintained at a constant pressure, and by supplying gas and water to this tank individually or as a mixed fluid at high pressure, the sandy material layer of gas, water and sandy material is liquefied, and this liquefied layer is made to be rotated at high speed by the rotary stirring device, and the gas is fragmented into ultrafine particles while the gas is confined in the pore water of the liquefied layer, and the water permeability coefficient of the sandy material is greatly increased by liquefaction, thereby greatly shortening the time that the ultrafine bubble water passes through the generation tank, and thus the method for generating high-concentration ultrafine bubble water is characterized in that it makes maximum use of sandy material and liquefaction.

2. A method for generating high-concentration ultrafine bubble water according to claim 1, wherein a high-pressure jet of a gas-water mixed fluid is impacted onto a sandy material layer from the nozzle of a fine bubble water generation tank to diffuse the gas and make this layer a liquefied sandy material layer of gas, water, and sandy material; a rotary stirring device is rotated at the required high speed to generate multiple horizontal shear surfaces and countless small, violent vortices in the liquefied sandy material layer through the interaction of the stirring blades and baffle plates fixed to the tank, thereby ultra-finely fragmenting the gas trapped in the pore water of the sandy material and generating a large amount of high-concentration ultrafine bubble water in a short time; the generation of ultrafine bubbles of any size is achieved by controlling the required rotation speed and rotation time of the rotary stirring device, and the method for generating high-concentration ultrafine bubble water is characterized by ultra-finely fragmenting the gas trapped in the pore water through the interaction of the stirring blades and baffle plates in the liquefied sandy material layer.

3. The fine bubble water generating apparatus according to claim 1 comprises a fine bubble water generating tank incorporating a rotary stirring device, a pressurized water supply device, and a pressurized gas supply device, wherein the fine bubble water generating tank is partitioned at either its top or bottom, or both, by a horizontal porous plate through which only gas and liquid can pass, and has a two- or three-tiered structure consisting of a main tank and a connecting tank, the main tank is fitted with a baffle plate and filled with sand-like material, and the outlet of the fine bubble water in the connecting tank is fitted with a relief valve to limit the water pressure of the fine bubble water as needed, and the ultrafine bubble water generating apparatus is characterized in that, with this configuration, the pore water pressure of the saturated sand-like material can maintain an excess pore water pressure that reaches liquefaction and can rotate at high speed.

4. A method for generating high-concentration ultrafine bubble water according to claim 1, characterized in that the gas pressure in the gas-water mixed fluid is set higher than the water pressure to facilitate the mixing of gas and water at the joints of each pumping pipe, thereby increasing gas dissolution, and the amount of pumped water and pumped gas are set in a mixing ratio considering the gas solubility.

5. A method for generating microbubble water that generates free radicals, characterized in that the fine bubble water generating apparatus of claim 1 controls the rotation speed and rotation time of the required rotary stirring device to target the diameter of microbubbles that are likely to generate free radicals.

6. A method for producing high-concentration ultrafine bubble water containing substances eluted from steel slag, characterized in that, by using sandy steel slag as the sandy material in the fine bubble water production tank of claim 1, the ultrafine bubble water is produced that, in addition to the effect of high-concentration ultrafine bubbles, has the effect of suppressing methane generation by silica, lime, and iron oxide, and improving crop health and yield.

7. A method for effectively utilizing high-concentration ultrafine bubble water for paddy rice cultivation according to claim 6, characterized in that, at the time of the first water inflow into the paddy field and at the time of water inflow after mid-season drainage, the amount of ultrafine bubble water to be injected is determined based on a planned dilution ratio at the upstream part of the water inlet of the paddy field cultivation area, and the ultrafine bubble water is uniformly sprayed underwater throughout the paddy field cultivation area using the flow of the incoming water, thereby efficiently distributing the planned ultrafine bubbles of silica, lime, iron ions, oxygen, and nitrogen to the root zone of the rice plants.

8. A method for effectively utilizing fine bubble water to improve the water quality of canals, lakes, ponds, etc., characterized in that a high-concentration ultrafine bubble water generating device of claim 1 is used, the rotation stirring device is controlled to target the diameter of fine bubbles that generate free radicals, the rotation time and rotation speed are set to generate this diameter, and the speed is periodically changed within a certain range around this rotation speed, thereby alternately generating high-concentration microbubble water and high-concentration ultrafine bubble water that generate free radicals with different lifespans, and fine bubble water incorporating the water quality improvement effects of both is sprayed into the water.

9. A device that incorporates a miniaturized high-concentration ultrafine bubble water generating device according to claim 1 into electrical appliances that require water for their function, thereby effectively utilizing the effects of free radicals.

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