JP7516163B2 - Ultra-fine bubble-containing liquid manufacturing device and method for manufacturing ultra-fine bubble-containing liquid - Google Patents

Description

The present invention relates to an apparatus for producing liquid containing ultra-fine bubbles and a method for producing liquid containing ultra-fine bubbles.

In recent years, technologies have been developed that utilize the properties of minute bubbles, such as microbubbles with diameters of micrometers and nanobubbles with diameters of nanometers. In particular, the usefulness of ultra-fine bubbles (hereinafter also referred to as "UFB") with diameters of less than 1.0 μm has been confirmed in a variety of fields.

Patent Document 1 discloses an apparatus that generates a high concentration of fine bubbles of a desired gas by providing a pressure dissolving section that pressurizes and dissolves a desired gas in a liquid, and a fine bubble generating section that sprays the liquid from a nozzle to generate fine bubbles, in the same liquid circulation path.

Patent No. 6104201

In the configuration of Patent Document 1, dissolution of the desired gas and generation of fine bubbles are carried out simultaneously in parallel in the same circulation path. That is, the circulation conditions such as the liquid flow rate and pressure are the same in both the pressurized dissolution process and the fine bubble generation process. However, the circulation conditions that are preferable for dissolving the desired gas in the liquid and the circulation conditions that are preferable for generating fine bubbles are not necessarily the same. Furthermore, such preferable circulation conditions change independently depending on the combination of liquid and gas used. For this reason, in the configuration of Patent Document 1, it was not always possible to efficiently generate a liquid containing fine bubbles of the desired gas.

The present invention was made to solve the above problems. Its purpose is to efficiently produce a liquid containing ultra-fine bubbles of a desired gas.

To this end, the present invention provides an apparatus for producing ultra-fine bubble-containing liquid, comprising: a dissolving means for dissolving a specific gas in a liquid; an ultra-fine bubble generating means for generating ultra-fine bubbles in the liquid in which the specific gas has been dissolved; and a circulation control means for controlling the circulation of the liquid in a liquid circulation path including the dissolving means and the ultra-fine bubble generating means, wherein the circulation control means circulates the liquid according to a first condition that determines the state of the circulating liquid when the dissolving means is operated in the circulation path that passes through the dissolving means, and circulates the liquid according to a second condition that is different from the first condition when the ultra-fine bubble generating means is operated in the circulation path that passes through the ultra-fine bubble generating means.

The present invention makes it possible to efficiently produce a liquid containing ultra-fine bubbles of a desired gas.

FIG. 1 illustrates an example of a UFB generating device. FIG. 2 is a schematic configuration diagram of a pre-treatment unit. 2A and 2B are schematic diagrams of a dissolving unit and diagrams for explaining a dissolved state of a liquid. FIG. 2 is a schematic diagram of a T-UFB generation unit. FIG. 4 is a diagram for explaining details of a heating element. 1A and 1B are diagrams for explaining the state of film boiling in a heating element. FIG. 1 is a diagram showing how UFB is generated with the expansion of film boiling bubbles. FIG. 1 is a diagram showing how UFB is generated as film boiling bubbles shrink. FIG. 1 illustrates how reheating a liquid produces UFB. FIG. 1 is a diagram showing how UFB is generated by shock waves generated when bubbles generated by film boiling collapse. FIG. 2 is a diagram illustrating an example of the configuration of a post-processing unit. 1 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a first embodiment. FIG. 2 is a block diagram showing a control configuration in the UFB-containing liquid manufacturing apparatus. 4 is a flowchart illustrating a process for producing a UFB-containing liquid according to the first embodiment. FIG. 11 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a second embodiment. 10 is a flowchart illustrating a process for producing a UFB-containing liquid according to a second embodiment. 10 is a flowchart illustrating a modified example of the second embodiment. FIG. 13 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a third embodiment. 10 is a flowchart illustrating a process for producing a UFB-containing liquid according to a third embodiment. FIG. 13 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a fourth embodiment. 13 is a flowchart illustrating a process for producing a UFB-containing liquid according to a fourth embodiment. 13 is a flowchart illustrating a modified example of the fourth embodiment. FIG. 13 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a fifth embodiment. FIG. 13 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a sixth embodiment. 13 is a flowchart illustrating a process for producing a UFB-containing liquid according to a sixth embodiment. FIG. 13 is a schematic configuration diagram illustrating a modified example of the UFB-containing liquid manufacturing apparatus according to the sixth embodiment. FIG. 13 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus according to a seventh embodiment. 13 is a flowchart illustrating a UFB-containing liquid manufacturing process according to the seventh embodiment.

<<Example of schematic configuration of UFB generating device>>
1 is a schematic diagram of a UFB generator applicable to the present invention. The UFB generator 1 includes a pre-treatment unit 100, a dissolving unit 200, a T-UFB generation unit 300, a post-treatment unit 400, and a recovery unit 500. A liquid W such as tap water supplied to the pre-treatment unit 100 is subjected to a process specific to each unit in the above order, and is recovered as a T-UFB-containing liquid in the recovery unit 500. The function and configuration of each unit will be described below. Although details will be described later, in this specification, UFB generated by utilizing film boiling caused by sudden heat generation is called T-UFB (Thermal-Ultra Fine Bubble).

Figure 2 is a schematic diagram of the pretreatment unit 100. The pretreatment unit 100 performs degassing on the supplied liquid W. The pretreatment unit 100 mainly includes a degassing vessel 101, a shower head 102, a vacuum pump 103, a liquid inlet 104, a liquid circulation passage 105, and a liquid outlet 106. Liquid W, such as tap water, is supplied to the degassing vessel 101 from the liquid inlet 104 via a valve 109. At this time, the shower head 102 provided on the degassing vessel 101 atomizes the liquid W and sprays it into the degassing vessel 101. The shower head 102 is for promoting the vaporization of the liquid W, but a centrifuge or the like can also be used as a mechanism for promoting vaporization.

After a certain amount of liquid W has been stored in the degassing vessel 101, the decompression pump 103 is operated with all valves closed to discharge the gas components that have already been vaporized and also promote the vaporization and discharge of the gas components dissolved in the liquid W. At this time, the internal pressure of the degassing vessel 101 may be reduced to approximately several hundred to several thousand Pa (1.0 Torr to 10.0 Torr) while checking the pressure gauge 108. Gases that are degassed by the degassing unit 100 include, for example, nitrogen, oxygen, argon, and carbon dioxide.

The above-described degassing process can be repeatedly performed on the same liquid W by using the liquid circulation path 105. Specifically, the valve 109 of the liquid inlet path 104 and the valve 110 of the liquid outlet path 106 are closed, and the valve 107 of the liquid circulation path 105 is opened, and the shower head 102 is operated. As a result, the liquid W stored in the degassing container 101 and degassed once is sprayed again into the degassing container 101 via the shower head 102. Furthermore, by operating the decompression pump 103, the vaporization process by the shower head 102 and the degassing process by the decompression pump 103 are repeatedly performed on the same liquid W. Then, each time the above-described repeated process is performed using the liquid circulation path 105, the gas components contained in the liquid W can be gradually reduced. When the liquid W degassed to the desired purity is obtained, the valve 110 is opened, and the liquid W is sent to the dissolving unit 200 via the liquid outlet path 106.

In FIG. 2, the degassing unit 100 is shown, which vaporizes the dissolved material by reducing the pressure of the gas section, but the method of degassing the dissolved liquid is not limited to this. For example, a heat-boiling method may be adopted in which the liquid W is boiled to vaporize the dissolved material, or a membrane degassing method may be adopted in which hollow fibers are used to increase the interface between the liquid and the gas. As a degassing module using hollow fibers, the SEPAREL series (manufactured by Dainippon Ink Co., Ltd.) is commercially available. This uses poly-4-methylpentene-1 (PMP) as the raw material for the hollow fiber membrane, and is mainly used for the purpose of degassing air bubbles from inks supplied to piezoelectric heads. Furthermore, two or more of the vacuum degassing method, the heat-boiling method, and the membrane degassing method may be used in combination.

Figures 3(a) and (b) are schematic diagrams of the dissolving unit 200 and diagrams for explaining the dissolved state of the liquid. The dissolving unit 200 is a unit that dissolves a desired gas in the liquid W supplied from the pre-processing unit 100. The dissolving unit 200 mainly includes a dissolving container 201, a rotating shaft 203 to which a rotating plate 202 is attached, a liquid inlet path 204, a gas inlet path 205, a liquid outlet path 206, and a pressure pump 207.

The liquid W supplied from the pretreatment unit 100 is supplied to the dissolution container 201 through the liquid inlet 204 and stored there. On the other hand, the gas G is supplied to the dissolution container 201 through the gas inlet 205.

When a predetermined amount of liquid W and gas G are stored in the dissolution vessel 201, the pressure pump 207 is operated to raise the internal pressure of the dissolution vessel 201 to about 0.5 MPa. A safety valve 208 is provided between the pressure pump 207 and the dissolution vessel 201. In addition, the gas G supplied to the dissolution vessel 201 is turned into bubbles by rotating the rotating plate 202 in the liquid via the rotating shaft 203, thereby increasing the contact area with the liquid W and promoting dissolution in the liquid W. This operation is continued until the solubility of the gas G reaches almost the maximum saturated solubility. At this time, a means for lowering the temperature of the liquid may be provided in order to dissolve as much gas as possible. In addition, in the case of a gas that is difficult to dissolve, it is also possible to raise the internal pressure of the dissolution vessel 201 to 0.5 MPa or more. In that case, it is necessary to optimize the material of the vessel for safety reasons.

When liquid W is obtained in which the components of gas G are dissolved at the desired concentration, the liquid W is discharged via the liquid outlet path 206 and supplied to the T-UFB generation unit 300. At this time, the back pressure valve 209 adjusts the flow pressure of the liquid W so that the pressure during supply does not become higher than necessary.

Figure 3(b) is a schematic diagram showing how the gas G mixed in the dissolution container 201 dissolves. The bubbles 2 containing the components of the gas G mixed in the liquid W dissolve from the part in contact with the liquid W. As a result, the bubbles 2 gradually shrink, and the gas-dissolved liquid 3 is present around the bubbles 2. Because of the buoyancy acting on the bubbles 2, the bubbles 2 move to a position away from the center of the gas-dissolved liquid 3, or separate from the gas-dissolved liquid 3 to become residual bubbles 4. In other words, the liquid W supplied to the T-UFB generation unit 300 via the liquid outlet 206 contains a mixture of the gas-dissolved liquid 3 surrounding the bubbles 2 and the gas-dissolved liquid 3 and the bubbles 2 separated from each other.

In the figure, the gas-dissolved liquid 3 means "a region in the liquid W where the dissolved concentration of the mixed gas G is relatively high." The gas components actually dissolved in the liquid W have the highest concentration around the bubbles 2 or at the center of the region even when separated from the bubbles 2, and the concentration of the gas components decreases continuously the further away from that position. That is, in FIG. 3(b), the region of the gas-dissolved liquid 3 is surrounded by a dashed line for the purpose of explanation, but in reality, no such clear boundary exists. In addition, in this embodiment, it is acceptable for gas that is not completely dissolved to exist in the liquid in the form of bubbles.

Figure 4 is a schematic diagram of the T-UFB generation unit 300. The T-UFB generation unit 300 mainly comprises a chamber 301, a liquid inlet passage 302, and a liquid outlet passage 303, and the flow from the liquid inlet passage 302 through the chamber 301 toward the liquid outlet passage 303 is formed by a flow pump (not shown). As the flow pump, various pumps such as a diaphragm pump, a gear pump, and a screw pump can be used. The liquid W introduced from the liquid inlet passage 302 contains a gas-dissolved liquid 3 of the gas G mixed in by the dissolving unit 200.

An element substrate 12 with a heating element 10 is disposed on the bottom surface of the chamber 301. When a predetermined voltage pulse is applied to the heating element 10, bubbles 13 (hereinafter also referred to as film boiling bubbles 13) are generated in the area in contact with the heating element 10 due to film boiling. Then, as the film boiling bubbles 13 expand and contract, ultra-fine bubbles (UFB11) containing gas G are generated. As a result, UFB-containing liquid W containing a large number of UFB11 is discharged from the liquid discharge path 303.

Figures 5(a) and (b) are diagrams showing the detailed structure of the heating element 10. Figure 5(a) shows a cross-sectional view of the vicinity of the heating element 10, and figure 5(b) shows a cross-sectional view of the element substrate 12 of a wider area including the heating element 10.

As shown in Fig. 5A, the element substrate 12 includes a thermal oxide film 305 as a heat storage layer and an interlayer film 306 that also functions as a heat storage layer, which are laminated on the surface of a silicon substrate 304. A _SiO2 film or a SiN film can be used as the interlayer film 306. A resistive layer 307 is formed on the surface of the interlayer film 306, and wiring 308 is partially formed on the surface of the resistive layer 307. The wiring 308 can be an Al alloy wiring such as Al, Al-Si, or Al-Cu. A protective layer 309 made of a _SiO2 film or _{a Si3N4 film} is formed on the surfaces of the wiring 308, the resistive layer 307, and the interlayer film 306.

On the surface of the protective layer 309, a cavitation-resistant film 310 is formed in the area corresponding to the heat application portion 311 that will eventually become the heating element 10, and around the area, to protect the protective layer 309 from chemical and physical shocks associated with the heat generation of the resistance layer 307. On the surface of the resistance layer 307, the area where the wiring 308 is not formed is the heat application portion 311 where the resistance layer 307 generates heat. The heat-generating portion of the resistance layer 307 where the wiring 308 is not formed functions as the heating element (heater) 10. In this way, the layers in the element substrate 12 are formed sequentially on the surface of the silicon substrate 304 by semiconductor manufacturing technology, and the silicon substrate 304 is thus provided with the heat application portion 311.

The configuration shown in the figure is an example, and various other configurations are applicable. For example, a configuration in which the stacking order of the resistive layer 307 and the wiring 308 is reversed, and a configuration in which an electrode is connected to the underside of the resistive layer 307 (a so-called plug electrode configuration) are applicable. In other words, as described below, any configuration is acceptable as long as it can heat the liquid with the thermal action portion 311 and cause film boiling in the liquid.

Figure 5 (b) is an example of a cross-sectional view of a region including a circuit connected to wiring 308 in the element substrate 12. An N-type well region 322 and a P-type well region 323 are partially provided on the surface layer of the silicon substrate 304, which is a P-type conductor. A P-MOS 320 is formed in the N-type well region 322 and an N-MOS 321 is formed in the P-type well region 323 by the introduction and diffusion of impurities such as ion implantation by a general MOS process.

The P-MOS 320 is composed of a source region 325 and a drain region 326 formed by partially doping N-type or P-type impurities into the surface layer of the N-type well region 322, and a gate wiring 335. The gate wiring 335 is deposited on the surface of the N-type well region 322, except for the source region 325 and the drain region 326, via a gate insulating film 328 having a thickness of several hundred angstroms.

The N-MOS 321 is composed of a source region 325 and a drain region 326 formed by partially doping N-type or P-type impurities into the surface layer of the P-type well region 323, and a gate wiring 335. The gate wiring 335 is deposited on the surface of the P-type well region 323, excluding the source region 325 and the drain region 326, via a gate insulating film 328 having a thickness of several hundred Å. The gate wiring 335 is made of polysilicon having a thickness of 3000 Å to 5000 Å deposited by the CVD method. The P-MOS 320 and N-MOS 321 form the C-MOS logic.

In the P-type well region 323, an N-MOS transistor 330 for driving an electrothermal conversion element (heat generating resistor element) is formed in a portion different from the N-MOS 321. The N-MOS transistor 330 is composed of a source region 332 and a drain region 331 partially formed on the surface layer of the P-type well region 323 by processes such as the introduction and diffusion of impurities, and a gate wiring 333. The gate wiring 333 is deposited on the surface of the P-type well region 323 in the portion excluding the source region 332 and the drain region 331 via a gate insulating film 328.

In this example, an N-MOS transistor 330 is used as the driving transistor for the electrothermal conversion element. However, the driving transistor is not limited to the N-MOS transistor 330, and may be any transistor capable of driving multiple electrothermal conversion elements individually and capable of obtaining the fine structure described above. Also, in this example, the electrothermal conversion element and its driving transistor are formed on the same substrate, but they may be formed on separate substrates.

Between each element, such as between P-MOS 320 and N-MOS 321, and between N-MOS 321 and N-MOS transistor 330, oxide film isolation regions 324 are formed by field oxidation with a thickness of 5000 Å to 10000 Å. Each element is isolated by this oxide film isolation region 324. In the oxide film isolation region 324, the part corresponding to the thermal action portion 311 functions as the first heat storage layer 334 on the silicon substrate 304.

An interlayer insulating film 336 made of a PSG film or a BPSG film having a thickness of about 7000 Å is formed on the surface of each element of the P-MOS 320, the N-MOS 321, and the N-MOS transistor 330 by the CVD method. After the interlayer insulating film 336 is flattened by heat treatment, an Al electrode 337 which becomes a first wiring layer is formed through a contact hole penetrating the interlayer insulating film 336 and the gate insulating film 328. An interlayer insulating film 338 made of a SiO ₂ film having a thickness of 10000 Å to 15000 Å is formed on the surface of the interlayer insulating film 336 and the Al electrode 337 by the plasma CVD method. On the surface of the interlayer insulating film 338, a resistive layer 307 made of a TaSiN film having a thickness of about 500 Å is formed by the co-sputtering method in a portion corresponding to the heat application portion 311 and the N-MOS transistor 330. The resistive layer 307 is electrically connected to an Al electrode 337 near the drain region 331 through a through hole formed in an interlayer insulating film 338. An Al wiring 308 is formed on the surface of the resistive layer 307 as a second wiring layer that serves as wiring to each electrothermal conversion element. The wiring 308, the resistive layer 307, and the protective layer 309 on the surface of the interlayer insulating film 338 are made of a SiN film having a thickness of 3000 Å formed by a plasma CVD method. The cavitation-resistant film 310 deposited on the surface of the protective layer 309 is made of at least one metal selected from Ta, Fe, Ni, Cr, Ge, Ru, Zr, Ir, etc., and is made of a thin film having a thickness of about 2000 Å. As the resistive layer 307, various materials such as TaN, CrSiN, TaAl, WSiN, etc. other than the above-mentioned TaSiN can be used as long as they can cause film boiling in liquid.

6(a) and (b) are diagrams showing the state of film boiling when a predetermined voltage pulse is applied to the heating element 10. Here, the case where film boiling is caused under atmospheric pressure is shown. In FIG. 6(a), the horizontal axis indicates time. The vertical axis of the lower graph indicates the voltage applied to the heating element 10, and the vertical axis of the upper graph indicates the volume and internal pressure of the film boiling bubbles 13 generated by film boiling. Meanwhile, FIG. 6(b) shows the state of the film boiling bubbles 13 in correspondence with timings 1 to 3 shown in FIG. 6(a). Each state will be explained below along the time. Note that, as will be described later, the UFB 11 generated by film boiling is mainly generated near the surface of the film boiling bubbles 13. The state shown in FIG. 6(b) shows the state in which the UFB 11 generated in the generation unit 300 is supplied again to the dissolving unit 200 via the circulation path, as shown in FIG. 1, and the liquid is supplied again to the liquid path of the generation unit 300.

Before a voltage is applied to the heating element 10, the chamber 301 is kept at approximately atmospheric pressure. When a voltage is applied to the heating element 10, film boiling occurs in the liquid in contact with the heating element 10, and the generated bubbles (hereinafter referred to as film boiling bubbles 13) expand due to the high pressure acting from the inside (timing 1). The bubbling pressure at this time is considered to be approximately 8 to 10 MPa, which is close to the saturated vapor pressure of water.

The voltage application time (pulse width) is approximately 0.5 μsec to 10.0 μsec, but even after the voltage is no longer applied, the film boiling bubble 13 continues to expand due to the inertia of the pressure obtained at timing 1. However, inside the film boiling bubble 13, the negative pressure generated by the expansion gradually increases, acting in a direction that causes the film boiling bubble 13 to contract. Eventually, at timing 2 when the force of inertia and the negative pressure are balanced, the volume of the film boiling bubble 13 reaches a maximum, after which it rapidly contracts due to the negative pressure.

When the film boiling bubbles 13 disappear, they do not disappear over the entire surface of the heating element 10, but in one or more extremely small areas. Therefore, in the heating element 10, a force greater than that generated when the film boiling bubbles 13 disappear is generated in the extremely small area where the film boiling bubbles 13 disappear (timing 3) than when the bubbles bubble at timing 1.

The generation, expansion, contraction and disappearance of the film boiling bubbles 13 as described above are repeated each time a voltage pulse is applied to the heating element 10, and each time a new UFB 11 is generated.

Next, using Figures 7 to 10, we will explain in more detail how UFB11 is generated during the processes of generation, expansion, contraction, and disappearance of film boiling bubbles 13.

Figures 7(a) to (d) are schematic diagrams showing how UFB11 is generated with the generation and expansion of film boiling bubbles 13. Figure 7(a) shows the state before a voltage pulse is applied to the heating element 10. Liquid W mixed with gas-dissolved liquid 3 flows inside the chamber 301.

Figure 7(b) shows how a voltage is applied to the heating element 10, and film boiling bubbles 13 are uniformly generated over almost the entire area of the heating element 10 in contact with the liquid W. When a voltage is applied, the surface temperature of the heating element 10 rises rapidly at a rate of 10°C/μsec or more, and when it reaches approximately 300°C, film boiling occurs and film boiling bubbles 13 are generated.

The surface temperature of the heating element 10 continues to rise to about 600-800°C while the pulses are still being applied, and the liquid around the film boiling bubble 13 is also rapidly heated. In the figure, the region of liquid located around the film boiling bubble 13 and rapidly heated is shown as the unfoamed high temperature region 14. The gas-dissolved liquid 3 contained in the unfoamed high temperature region 14 exceeds the thermal solubility limit and precipitates to become UFB. The precipitated bubbles have a diameter of about 10 nm to 100 nm and have high gas-liquid interface energy. Therefore, they do not disappear in a short time, but float independently in the liquid W. In this example, the bubbles generated by thermal action when the film boiling bubble 13 is generated and expands are called the first UFB 11A.

Figure 7 (c) shows the process of the film boiling bubble 13 expanding. Even after the application of the voltage pulse to the heating element 10 is terminated, the film boiling bubble 13 continues to expand due to the inertia of the force obtained when it was generated, and the unfoamed high-temperature region 14 also moves and diffuses due to inertia. In other words, in the process of the film boiling bubble 13 expanding, the gas-dissolved liquid 3 contained in the unfoamed high-temperature region 14 precipitates as new bubbles, becoming the first UFB 11A.

Figure 7 (d) shows the state when the film boiling bubble 13 has reached its maximum volume. The film boiling bubble 13 expands due to inertia, but as it expands, the negative pressure inside the film boiling bubble 13 gradually increases, acting as a negative pressure that tries to contract the film boiling bubble 13. Then, when this negative pressure balances with the force of inertia, the volume of the film boiling bubble 13 reaches its maximum, and then it begins to contract.

During the contraction stage of the film boiling bubble 13, there is a UFB (second UFB 11B) that is generated by the process shown in Figures 8(a) to (c), and a UFB (third UFB) that is generated by the process shown in Figures 9(a) to (c). These two processes are thought to coexist.

Figures 8(a) to (c) are diagrams showing how UFB 11 is generated as film boiling bubble 13 contracts. Figure 8(a) shows the state in which film boiling bubble 13 has started to contract. Even after film boiling bubble 13 starts to contract, the surrounding liquid W still has an inertial force in the direction of expansion. Therefore, the extreme periphery of film boiling bubble 13 is subjected to an inertial force acting in a direction away from heating element 10 and a force acting toward heating element 10 as film boiling bubble 13 contracts, resulting in a reduced pressure region. In the figure, such a region is shown as unfoamed negative pressure region 15.

The gas-dissolved liquid 3 contained in the unfoamed negative pressure region 15 exceeds the pressure dissolution limit and precipitates as bubbles. The precipitated bubbles have a diameter of about 100 nm, and do not disappear in a short time thereafter, but float independently within the liquid W. In this example, the bubbles precipitated in this way due to the pressure action when the film boiling bubbles 13 contract are referred to as second UFB11B.

Figure 8 (b) shows the process of the film boiling bubble 13 shrinking. The speed at which the film boiling bubble 13 shrinks is accelerated by the negative pressure, and the unfoamed negative pressure region 15 also moves as the film boiling bubble 13 shrinks. That is, in the process of the film boiling bubble 13 shrinking, the gas-dissolved liquid 3 at the point where the unfoamed negative pressure region 15 passes through is precipitated one after another, becoming the second UFB 11B.

Figure 8 (c) shows the state just before the film boiling bubbles 13 disappear. Due to the accelerated contraction of the film boiling bubbles 13, the movement speed of the surrounding liquid W also increases, but pressure loss occurs due to the flow path resistance in the chamber 301. As a result, the area occupied by the unfoamed negative pressure region 15 becomes even larger, and a large number of second UFBs 11B are generated.

Figures 9(a) to (c) are diagrams showing how UFB is generated by reheating liquid W when film boiling bubbles 13 contract. Figure 9(a) shows the state in which the surface of the heating element 10 is covered with contracting film boiling bubbles 13.

Figure 9(b) shows a state in which the film boiling bubble 13 has contracted and part of the surface of the heating element 10 has come into contact with the liquid W. At this time, there is still enough heat remaining on the surface of the heating element 10 that film boiling will not occur even if the liquid W comes into contact with it. In the figure, the region of the liquid that is heated by contact with the surface of the heating element 10 is shown as the unfoamed reheated region 16. Although film boiling will not occur, the gas-dissolved liquid 3 contained in the unfoamed reheated region 16 will precipitate out beyond its thermal solubility limit. In this example, the bubbles generated by reheating the liquid W as the film boiling bubble 13 contracts are referred to as the third UFB 11C.

Figure 9 (c) shows a state in which the film boiling bubble 13 has further contracted. As the film boiling bubble 13 becomes smaller, the area of the heating element 10 in contact with the liquid W becomes larger, so the third UFB 11C is generated until the film boiling bubble 13 disappears.

Figures 10(a) and (b) show how UFB is generated by the impact (a type of cavitation) that occurs when film boiling bubbles 13 generated by film boiling collapse. Figure 10(a) shows the state just before the film boiling bubble 13 disappears. The film boiling bubble 13 contracts rapidly due to the negative pressure inside, and is surrounded by an unfoamed negative pressure region 15.

Figure 10(b) shows the state immediately after the film boiling bubble 13 disappears at point P. When the film boiling bubble 13 disappears, the impact causes an acoustic wave to spread concentrically starting from point P. An acoustic wave is a general term for elastic waves that propagate regardless of whether they are gas, liquid, or solid, and in this example, they are propagated alternately between the dense and dense liquid W, i.e., the high pressure surface 17A and the low pressure surface 17B of the liquid W.

In this case, the gas-dissolved liquid 3 contained in the unfoamed negative pressure region 15 is resonated by the shock waves generated when the film boiling bubbles 13 collapse, and undergoes a phase transition beyond the pressure dissolution limit when the low pressure surface 17B passes. In other words, at the same time as the film boiling bubbles 13 collapse, a large number of bubbles precipitate in the unfoamed negative pressure region 15. In this example, the bubbles generated by the shock waves generated when the film boiling bubbles 13 collapse are referred to as the fourth UFB 11D.

The fourth UFB 11B, which is generated by the shock wave generated when the film boiling bubble 13 collapses, appears suddenly in an extremely narrow thin-film region in an extremely short time (less than 1 μS). Its diameter is much smaller than the first to third UFBs, and its gas-liquid interfacial energy is higher than the first to third UFBs. For this reason, the fourth UFB 11D is thought to have different properties and produce different effects from the first to third UFBs 11A to 11C.

In addition, since the fourth UFB11D is generated uniformly throughout the concentric spherical region through which the shock wave propagates, it will be present uniformly within the chamber 301 from the time it is generated. At the time the fourth UFB11D is generated, a large number of the first to third UFBs are already present, but the presence of these first to third UFBs does not significantly affect the generation of the fourth UFB11D. Furthermore, it is thought that the generation of the fourth UFB11D will not cause the first to third UFBs to disappear.

As described above, it is assumed that UFB11 is generated in multiple stages from when the film boiling bubble 13 is generated by the heat generated by the heating element 10 until it disappears. The first UFB11A, the second UFB11B, and the third UFB11C are generated near the surface of the film boiling bubble generated by film boiling. Here, "nearby" refers to an area within about 20 μm from the surface of the film boiling bubble. The fourth UFB11D is generated in an area where a shock wave generated when the bubble disappears (disappears) propagates. In the above example, an example is shown where the film boiling bubble 13 disappears, but this is not the only way to generate UFB. For example, by communicating with the atmosphere before the generated film boiling bubble 13 disappears, UFB can be generated even if the film boiling bubble 13 is not consumed.

Next, we will explain the residual characteristics of UFB. The higher the temperature of the liquid, the lower the solubility of the gas components, and the lower the temperature, the higher the solubility of the gas components. In other words, the higher the temperature of the liquid, the more the phase transition of the dissolved gas components is promoted, making it easier for UFB to be generated. The temperature of the liquid and the solubility of gas are inversely proportional, and as the temperature of the liquid rises, gas that exceeds its saturated solubility becomes bubbles and precipitates in the liquid.

For this reason, when the temperature of the liquid rises suddenly from room temperature, the solubility characteristics drop dramatically and UFBs begin to be produced. And the higher the temperature, the lower the thermal solubility characteristics become, resulting in a situation in which a lot of UFBs are produced.

Conversely, when the temperature of the liquid drops from room temperature, the solubility of the gas increases, making the generated UFB more likely to liquefy. However, this temperature is well below room temperature. Furthermore, even if the temperature of the liquid drops, once generated UFB has high internal pressure and high gas-liquid interfacial energy, so it is extremely unlikely that high pressure will act on the gas-liquid interface to destroy it. In other words, once generated, UFB will not disappear easily as long as the liquid is stored at room temperature and pressure.

In this example, the first UFB 11A described in Figures 7(a) to (c) and the third UFB 11C described in Figures 9(a) to (c) can be said to be UFBs generated by utilizing the thermal dissolution properties of such gases.

On the other hand, in terms of the relationship between liquid pressure and solubility characteristics, the higher the liquid pressure, the higher the gas solubility characteristics, and the lower the pressure, the lower the solubility characteristics. In other words, the lower the liquid pressure, the more the gas dissolved in the liquid is promoted to undergo a phase transition to gas, making it easier for UFB to be generated. When the liquid pressure is reduced from normal pressure, the solubility characteristics drop sharply and UFB begins to be generated. And the lower the pressure, the lower the pressure solubility characteristics become, resulting in a situation where a lot of UFB is generated.

Conversely, when the pressure of the liquid increases from normal pressure, the solubility properties of the gas increase, making the generated UFB more likely to liquefy. However, this pressure is much higher than atmospheric pressure, and even if the pressure of the liquid increases, the UFB once generated has high internal pressure and high gas-liquid interfacial energy, so it is highly unlikely that high pressure will act to destroy the gas-liquid interface. In other words, once generated, UFB will not easily disappear as long as the liquid is stored at room temperature and pressure.

In this example, the second UFB 11B described in Figures 8(a) to (c) and the fourth UFB 11D described in Figures 10(a) to (c) can be said to be UFBs generated by utilizing the pressure dissolution characteristics of such gases.

Above, the first to fourth UFBs, which are generated by different factors, have been explained individually, but the above-mentioned generation factors occur simultaneously in association with the phenomenon of film boiling. For this reason, at least two or more types of UFBs among the first to fourth UFBs may be generated simultaneously, and these generation factors may cooperate with each other to generate UFBs. However, all generation factors have in common that they are brought about by the volume change of film boiling bubbles generated by the film boiling phenomenon. In this specification, such a method of generating UFBs using film boiling caused by sudden heat generation is referred to as a T-UFB (Thermal-Ultra Fine Bubble) generation method. In addition, UFB generated by the T-UFB generation method is referred to as T-UFB, and liquid containing T-UFB generated by the T-UFB generation method is referred to as a T-UFB-containing liquid.

Most of the bubbles generated by the T-UFB generation method are 1.0 μm or less, and millibubbles and microbubbles are difficult to generate. That is, according to the T-UFB generation method, UFB is generated predominantly and efficiently. In addition, the T-UFB generated by the T-UFB generation method has a higher gas-liquid interfacial energy than the UFB generated by the conventional method, and does not disappear easily as long as it is stored at room temperature and normal pressure. Furthermore, even if new T-UFB is generated by new film boiling, the disappearance of the previously generated T-UFB due to the impact is suppressed. In other words, it can be said that the number and concentration of T-UFB contained in the T-UFB-containing liquid have hysteresis characteristics with respect to the number of times film boiling occurs in the T-UFB-containing liquid. In other words, the concentration of T-UFB contained in the T-UFB-containing liquid can be adjusted by controlling the number of heating elements arranged in the T-UFB generation unit 300 and the number of times voltage pulses are applied to the heating elements.

Referring again to FIG. 1, once the T-UFB-containing liquid W having the desired UFB concentration is generated in the T-UFB generation unit 300, the UFB-containing liquid W is supplied to the post-treatment unit 400.

Figures 11(a) to (c) are diagrams showing an example of the configuration of the post-treatment unit 400. The post-treatment unit 400 removes impurities contained in the UFB-containing liquid W in stages, in that order: inorganic ions, organic matter, and insoluble solids.

11A shows a first post-treatment mechanism 410 for removing inorganic ions. The first post-treatment mechanism 410 includes an exchange container 411, a cation exchange resin 412, a liquid introduction passage 413, a water collection pipe 414, and a liquid discharge passage 415. The exchange container 411 contains the cation exchange resin 412. The UFB-containing liquid W generated in the T-UFB generation unit 300 is injected into the exchange container 411 via the liquid introduction passage 413 and absorbed into the cation exchange resin 412, where cations as impurities are removed. Such impurities include metal materials peeled off from the element substrate 12 of the T-UFB generation unit 300, such as SiO ₂ , SiN, SiC, Ta, Al ₂ O ₃ , Ta ₂ O ₅ , and Ir.

The cation exchange resin 412 is a synthetic resin in which functional groups (ion exchange groups) have been introduced into a polymer matrix having a three-dimensional mesh structure, and the synthetic resin has spherical particles of about 0.4 to 0.7 mm. The polymer matrix is generally a copolymer of styrene-divinylbenzene, and the functional groups can be, for example, methacrylic acid and acrylic acid. However, the above material is only an example. As long as the desired inorganic ions can be effectively removed, the above material can be changed in various ways. The UFB-containing liquid W that has been absorbed by the cation exchange resin 412 and from which the inorganic ions have been removed is collected by the water collection tube 414 and sent to the next process via the liquid outlet 415.

11B shows a second post-treatment mechanism 420 for removing organic matter. The second post-treatment mechanism 420 includes a storage container 421, a filter 422, a vacuum pump 423, a valve 424, a liquid inlet passage 425, a liquid outlet passage 426, and an air suction passage 427. The inside of the storage container 421 is divided into two regions, upper and lower, by the filter 422. The liquid inlet passage 425 is connected to the upper region of the two regions, and the air suction passage 427 and the liquid outlet passage 426 are connected to the lower region. When the vacuum pump 423 is driven with the valve 424 closed, the air in the storage container 421 is discharged through the air suction passage 427, the inside of the storage container 421 becomes negative pressure, and the UFB-containing liquid W is introduced from the liquid inlet passage 425. Then, the UFB-containing liquid W in a state in which impurities have been removed by the filter 422 is stored in the storage container 421.

The impurities removed by the filtration filter 422 include organic materials that may be mixed in the tubes and each unit, such as organic compounds containing silicon, siloxane, and epoxy. Filter membranes that can be used for the filtration filter 422 include sub-μm mesh filters that can remove even bacteria, and nm mesh filters that can remove even viruses.

After a certain amount of UFB-containing liquid W is stored in the storage container 421, the vacuum pump 423 is stopped and the valve 424 is opened, and the T-UFB-containing liquid in the storage container 421 is sent to the next process via the liquid outlet path 426. Note that, although vacuum filtration is used here as a method for removing organic impurities, other filtration methods using a filter, such as gravity filtration or pressure filtration, can also be used.

Figure 11 (c) shows a third post-treatment mechanism 430 for removing insoluble solids. The third post-treatment mechanism 430 includes a settling vessel 431, a liquid inlet passage 432, a valve 433, and a liquid outlet passage 434.

First, with the valve 433 closed, a predetermined amount of UFB-containing liquid W is stored in the settling container 431 from the liquid introduction path 432 and left for a while. During this time, solid matter contained in the UFB-containing liquid W settles to the bottom of the settling container 431 due to gravity. Furthermore, among the bubbles contained in the UFB-containing liquid, relatively large bubbles such as microbubbles also rise to the liquid surface due to buoyancy and are removed from the UFB-containing liquid. When the valve 433 is opened after a sufficient amount of time has passed, the UFB-containing liquid W from which solid matter and large bubbles have been removed is sent to the recovery unit 500 via the liquid outlet path 434. Here, an example in which three post-processing mechanisms are applied in sequence is shown, but this is not limited to this, and any post-processing mechanism may be appropriately adopted as needed.

Refer to FIG. 1 again. The T-UFB-containing solution W from which impurities have been removed in the post-treatment unit 400 may be sent directly to the recovery unit 500, or may be returned to the dissolution unit 200. In the latter case, the gas dissolution concentration of the T-UFB-containing solution W, which has decreased due to the generation of T-UFB, can be replenished to a saturated state in the dissolution unit 200. If new T-UFB is then generated in the T-UFB generation unit 300, the UFB content concentration of the T-UFB-containing solution can be further increased based on the above-mentioned characteristics. In other words, the UFB content concentration can be increased by the number of times the solution circulates through the dissolution unit 200, the T-UFB generation unit 300, and the post-treatment unit 400, and after the desired UFB content concentration is obtained, the UFB-containing solution W can be sent to the recovery unit 500.

The recovery unit 500 recovers and stores the UFB-containing liquid W sent from the post-treatment unit 400. The T-UFB-containing liquid recovered by the recovery unit 500 becomes a highly pure UFB-containing liquid from which various impurities have been removed.

In the recovery unit 500, several stages of filtering may be performed to classify the UFB-containing liquid W according to the size of the T-UFB. In addition, since the T-UFB-containing liquid W obtained by the T-UFB method is expected to be at a temperature higher than room temperature, the recovery unit 500 may be provided with a cooling means. Such a cooling means may be provided as part of the post-processing unit 400.

The above is an overview of the UFB generating device 1, but the multiple units shown in the figure can of course be modified, and it is not necessary to prepare all of them. Depending on the type of liquid W and gas G used, and the intended use of the T-UFB-containing liquid to be generated, some of the above-mentioned units may be omitted, or further units may be added in addition to the above-mentioned units.

For example, if the gas contained in the UFB is atmospheric air, the degassing unit 100 and the dissolving unit 200 can be omitted. Conversely, if it is desired to contain multiple types of gas in the UFB, a dissolving unit 200 may be further added.

In addition, the unit for removing impurities as shown in Figures 11(a) to (c) may be provided upstream of the T-UFB generation unit 300, or may be provided both upstream and downstream. When the liquid supplied to the UFB generation device is tap water, rainwater, or contaminated water, the liquid may contain organic or inorganic impurities. If liquid W containing such impurities is supplied to the T-UFB generation unit 300, there is a risk that the heating element 10 may be altered or salting out may occur. By providing a mechanism as shown in Figures 11(a) to (c) upstream of the T-UFB generation unit 300, the above-mentioned impurities can be removed in advance.

<<Liquids and gases that can be used for T-UFB-containing liquid>>
Here, the liquid W that can be used to generate the T-UFB-containing liquid will be described. Examples of the liquid W that can be used include pure water, ion-exchanged water, distilled water, physiologically active water, magnetically active water, lotion, tap water, seawater, river water, sewage water, lake water, groundwater, and rainwater. Mixed liquids containing these liquids can also be used. Mixed solvents of water and water-soluble organic solvents can also be used. The water-soluble organic solvent to be used by mixing with water is not particularly limited, but specific examples include the following: C1-4 alkyl alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; Amides such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide, and N,N-dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Cyclic ethers such as tetrahydrofuran and dioxane. Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol. Glycols such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and thiodiglycol. Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane. These water-soluble organic solvents may be used alone or in combination of two or more.

Examples of gas components that can be introduced by the dissolution unit 200 include hydrogen, helium, oxygen, nitrogen, methane, fluorine, neon, carbon dioxide, ozone, argon, chlorine, ethane, propane, and air. Mixtures of some of the above may also be used. Furthermore, the dissolution unit 200 does not necessarily have to dissolve substances in a gaseous state, and may melt liquids or solids composed of desired components into liquid W. Dissolution in this case may be natural dissolution, dissolution by application of pressure, or dissolution involving hydration, ionization, or chemical reaction due to ionization.

<<Effects of the T-UFB generation method>>
Next, the features and effects of the T-UFB generation method described above will be explained in comparison with conventional UFB generation methods. For example, in conventional bubble generation devices, such as the Venturi system, a mechanical pressure reduction structure such as a pressure reduction nozzle is provided in a part of the flow path, and liquid is made to flow through this pressure reduction structure at a predetermined pressure to generate bubbles of various sizes in the area downstream of the pressure reduction structure.

In this case, buoyancy acts on relatively large bubbles such as millibubbles and microbubbles among the bubbles generated, and they eventually rise to the liquid surface and disappear. Furthermore, UFBs that are not buoyant do not have a large gas-liquid interfacial energy and may disappear along with millibubbles and microbubbles. In addition, even if the above-mentioned pressure reduction structures are arranged in series and the same liquid is repeatedly passed through the pressure reduction structures, it is not possible to store a number of UFBs corresponding to the number of repetitions for a long period of time. In other words, it was difficult to maintain the UFB concentration at a specified value for a long period of time in UFB-containing liquid generated by conventional UFB generation methods.

In contrast, in the T-UFB generation method using film boiling, a sudden temperature change from room temperature to about 300°C and a sudden pressure change from normal pressure to about several megapascals are locally generated in the immediate vicinity of the heating element. The heating element is a quadrilateral with a side length of about tens to hundreds of μm. It is about 1/10 to 1/1000 of the size of a conventional UFB generator. Furthermore, the gas-dissolved liquid present in the extremely thin film region on the surface of the film boiling bubble instantaneously (in an extremely short time of less than microseconds) exceeds the thermal solubility limit or pressure solubility limit, causing a phase transition and precipitating as UFB. In this case, bubbles of relatively large size such as millibubbles and microbubbles are hardly generated, and the liquid contains UFB with a diameter of about 100 nm at an extremely high purity. Furthermore, the T-UFB generated in this way has a sufficiently high gas-liquid interface energy, so it is not easily destroyed under normal environments and can be stored for a long period of time.

In particular, the configuration of this embodiment, which uses the film boiling phenomenon that can form a gas interface locally on the liquid, can form an interface in a portion of the liquid present near the heating element without affecting the entire liquid region. The resulting thermally and pressure-sensitive region can be made extremely localized. As a result, the desired UFB can be generated stably. In addition, by circulating the liquid and applying further UFB generation conditions to the generated liquid, new UFB can be generated with minimal impact on existing UFB. As a result, UFB liquid of the desired size and concentration can be produced relatively easily.

Furthermore, because the T-UFB production method has the above-mentioned hysteresis characteristics, it is possible to increase the content concentration to the desired concentration while maintaining a high purity. In other words, the T-UFB production method makes it possible to efficiently produce a UFB-containing liquid that is highly pure, highly concentrated, and can be stored for a long period of time.

<<Specific applications of T-UFB-containing liquid>>
In general, the uses of ultra-fine bubble-containing liquids are classified according to the type of gas contained therein. Any gas can be converted into UFB as long as it can dissolve in the liquid in amounts of PPM to BPM. As an example, it can be applied to the following purposes.

- UFB-containing liquids containing air can be ideally used for cleaning in industrial, agricultural, and medical applications, as well as for growing plants and agricultural and marine products.

- UFB-containing liquids containing ozone can be used effectively for cleaning applications in industrial, agricultural, fisheries and medical fields, as well as for disinfection, sterilization and elimination purposes, and for environmental purification of wastewater and contaminated soil.

- Nitrogen-containing UFB-containing liquids can be used effectively for cleaning applications in industrial, agricultural, fisheries and medical fields, as well as for disinfection, sterilization and elimination purposes, and for environmental purification of wastewater and contaminated soil.

- UFB-containing liquids that contain oxygen can be used for cleaning purposes in industrial, agricultural, and medical applications, as well as for cultivating plants and agricultural and marine products.

- UFB-containing liquids containing carbon dioxide can be used effectively for cleaning applications in industrial, agricultural, fishery and medical fields, as well as for disinfection, sterilization and eradication purposes.

- UFB-containing liquids containing perfluorocarbon, a medical gas, can be ideally used for ultrasonic diagnosis and treatment. In this way, UFB-containing liquids can be effective in a wide range of fields, including medicine, pharmaceuticals, dentistry, food, industry, agriculture, and fisheries.

In order to ensure that the effects of the UFB-containing liquid are quickly and reliably achieved in each application, the purity and concentration of the UFB contained in the UFB-containing liquid are important. In other words, by using the T-UFB production method, which can produce UFB-containing liquid with high purity and the desired concentration, greater effects than ever before can be expected in a variety of fields. Below is a list of applications for which the T-UFB production method and T-UFB-containing liquid are expected to be suitable.

(A) Liquid purification applications - By installing a T-UFB generating unit in a water purifier, it is expected that the water purification effect and the purification effect of pH adjustment liquid can be improved. In addition, a T-UFB generating unit can be installed in a carbonated water server, etc.

- By installing a T-UFB generating unit in a humidifier, aroma diffuser, coffee maker, etc., it is expected that the humidification effect, deodorization effect, and fragrance diffusion effect in the room can be improved.

- The dissolution unit produces a UFB-containing liquid by dissolving ozone gas. This can be used in dental treatment, burn treatment, and wound care when using an endoscope, and is expected to improve medical cleaning and disinfection effects.

- By installing a T-UFB generation unit in the water tank of an apartment building, it is expected that the purification effect and chlorine removal effect of drinking water stored for long periods of time can be improved.

- In the brewing process of sake, shochu, wine, etc., where high-temperature sterilization is not possible, it is expected that low-temperature sterilization can be performed more efficiently than before by using a T-UFB-containing liquid that contains ozone and carbon dioxide.

- During the manufacturing process of specified health foods and functional foods, low-temperature sterilization is possible by mixing the raw materials with a UFB-containing liquid, making it possible to provide safe and functional foods without compromising flavor.

- In fish and pearl farms, by placing a T-UFB generation unit in the supply route of seawater or freshwater for farming, it is expected that the spawning and growth of fish and shellfish will be promoted.

- By installing a T-UFB generation unit in the food preservation water purification process, it is expected that the preservation conditions of food ingredients can be improved.

- By installing a T-UFB generation unit in a decolorizer for decolorizing pool water, groundwater, etc., a higher decolorization effect can be expected.

- By using a liquid containing T-UFB to repair cracks in concrete components, it is expected that the effectiveness of the crack repair will be improved.

- By adding T-UFB to liquid fuels used in equipment that uses liquid fuels (automobiles, ships, airplanes, etc.), it is expected that the energy efficiency of the fuels will be improved.

(B) Cleaning Applications In recent years, UFB-containing liquid has been attracting attention as cleaning water for removing dirt and other substances adhering to clothes. By disposing the T-UFB generation unit described in the above embodiment in a washing machine and supplying a UFB-containing liquid with higher purity and better penetration than conventional liquids to the washing tub, it is expected that the cleaning power can be further improved.

- By installing a T-UFB generation unit in a bath shower or toilet flushing machine, it is expected to have a cleaning effect on the human body and other living things in general, as well as to promote the removal of contaminants such as limescale and mold from the bathroom or toilet.

- By installing a T-UFB generation unit in windshield washers for automobiles, high-pressure cleaners for cleaning wall materials, car washes, dishwashers, food washing machines, etc., it is expected that the cleaning effect of each machine will be further improved.

- When cleaning and maintaining factory manufactured parts, such as in the deburring process after press processing, using a liquid containing T-UFB is expected to improve the cleaning effect.

-When manufacturing semiconductor devices, it is expected that the polishing effect will be improved by using a T-UFB-containing liquid as the polishing water for wafers. In addition, in the resist removal process, it is expected that the use of a T-UFB-containing liquid will promote the removal of resist that is difficult to remove.

- By installing a T-UFB generation unit in equipment used to clean and disinfect medical devices such as medical robots, dental treatment devices, and organ storage containers, it is expected that the cleaning and disinfection effects of these devices will be improved. It can also be applied to the treatment of living organisms.

(C) Pharmaceutical Uses - By adding T-UFB-containing liquid to cosmetics, it is possible to promote penetration into subcutaneous cells and significantly reduce additives such as preservatives and surfactants that have adverse effects on the skin. As a result, it is possible to provide safer and more functional cosmetics.

- By using a high-concentration nanobubble formulation containing T-UFB as a contrast agent for medical examination equipment such as CT and MRI, it is possible to efficiently utilize reflected light from X-rays and ultrasound, obtaining more detailed images and using it for the early diagnosis of malignant tumors.

- By using high-concentration nanobubble water containing T-UFB in an ultrasound treatment device known as HIFU (High Intensity Focused Ultrasound), the ultrasound irradiation power can be reduced, allowing for more non-invasive treatment. In particular, it becomes possible to reduce damage to normal tissue.

-UFB-containing high-concentration nanobubbles are used as seeds to modify phospholipids that form liposomes in the negatively charged region surrounding the bubbles, and nanobubble formulations can be created that incorporate various medical substances (such as DNA and RNA) via the phospholipids.

- As a treatment for regenerating dental pulp and dentin, when a medicine containing high-concentration nanobubble water generated by T-UFB is pumped into a dental canal, the penetrating action of the nanobubble water allows the medicine to penetrate deep into the dentinal tubules, promoting the sterilization effect and enabling root canal treatment of infected dental pulp to be performed quickly and safely.

The following describes in detail an embodiment of the present invention.

(First embodiment)
12 is a schematic diagram of an ultra-fine bubble-containing liquid manufacturing apparatus 2000 (hereinafter referred to as UFB-containing liquid manufacturing apparatus 2000) in the first embodiment. The UFB-containing liquid manufacturing apparatus 2000 in this embodiment mainly includes a liquid supply unit 600, a gas dissolving unit 800, a first storage chamber 900, and an ultra-fine bubble generating unit 1000 (hereinafter referred to as UFB generating unit 1000). The liquid supply unit 600, the gas dissolving unit 800, and the UFB generating unit 1000 correspond to the pre-treatment unit 100, the dissolving unit 200, and the T-UFB generating unit 300 in FIG. 1, respectively. Each unit is connected to each other by a pipe 700, and a liquid W is circulated by a pump 701 arranged in the middle of the pipe 700. In FIG. 12, solid arrows indicate the flow of liquid, and dashed arrows indicate the flow of gas.

The liquid supply unit 600 mainly includes a liquid storage unit 601, two pumps 602 and 603, and a degassing unit 604. The liquid W stored in the liquid storage unit 601 is sent to the first storage chamber 900 by the pumps 602 and 603 via the degassing unit 604. Inside the degassing unit 604, a membrane is provided through which gas can pass but liquid cannot. Only gas passes through the membrane due to the pressure of the pumps 602 and 603, separating the gas and the liquid, and the liquid W is directed toward the first storage chamber 900, while the gas is discharged to the outside. There is a possibility that various gases are dissolved in the liquid stored in the liquid storage unit 601. However, by removing the dissolved gases by the degassing unit 604 before sending the liquid to the first storage chamber 900, the dissolution efficiency of the gas dissolution process performed later can be improved.

The gas dissolving section 800 includes a gas supply section 804, a pre-treatment section 801, a junction section 802, and a gas-liquid separation chamber 803. The gas supply section 804 may be a cylinder that stores the desired gas G, but may also be a device that can continuously generate the desired gas G. For example, if the desired gas G is oxygen, the device can take in air, remove nitrogen, and continuously pump out the gas from which the nitrogen has been removed.

The gas G supplied from the gas supply unit 804 is subjected to a process such as discharge by the pretreatment unit 801, and then merges with the liquid W flowing out from the first storage chamber 900 at the merging unit 802. At this time, a part of the gas G dissolves in the liquid W. The merged gas G and liquid W are separated again by the gas-liquid separation chamber 803, and only the gas G that has not dissolved in the liquid W is discharged to the outside. The liquid W with the dissolved gas G is then sent to the UFB generation unit 1000 by the pump 701. In addition, a solubility sensor 805 for detecting the solubility of the gas G in the liquid W is provided downstream of the gas-liquid separation chamber 803.

The UFB generating unit 1000 generates UFB in the flowing liquid W. Various methods for generating UFB can be used, such as the Venturi method, but in this embodiment, the T-UFB method described with reference to Figures 4 to 10 is used. A filter 1001 is disposed upstream of the UFB generating unit 1000 to prevent impurities, debris, etc. from flowing into the UFB generating unit 1000. By removing impurities, debris, etc., the efficiency of generating UFB in the UFB generating unit 1000 can be improved. The UFB-containing liquid W generated in the UFB generating unit 1000 is stored in the first storage chamber 900 through the piping 700.

The first storage chamber 900 contains a mixture of liquid W supplied from the liquid supply unit 600, liquid W in which the desired gas G has been dissolved in the gas dissolution unit 800, and a UFB-containing liquid in which T-UFB has been generated in the UFB generation unit 1000.

The temperature sensor 905 detects the temperature of the liquid contained in the first storage chamber 900. The liquid level sensor 902 is disposed at a predetermined height in the first storage chamber 900 and detects the liquid level of the liquid W. The UFB concentration sensor 906 detects the UFB concentration of the liquid W contained in the first storage chamber 900. The valve 904 is opened when the liquid W contained in the first storage chamber 900 is discharged into an external container. Although not shown in the figure, a stirring means may be provided inside the first storage chamber 900 to make the temperature of the liquid W and the distribution of the UFB uniform.

The cooling unit 903 cools the liquid W contained in the first storage chamber 900. In order to efficiently dissolve the desired gas G in the gas dissolving unit 800, it is preferable that the temperature of the liquid W supplied to the gas dissolving unit 800 is as low as possible. In addition, by keeping the temperature of the circulating liquid W low, it is possible to suppress the temperature rise of the UFB generating unit 1000, which generates UFB using film boiling, and to extend the life of the UFB generating unit 1000. In this embodiment, the temperature of the liquid is detected by the temperature sensor 905, and the temperature of the liquid W supplied to the gas dissolving unit 800 is adjusted to 20°C or less using the cooling unit 903.

The configuration of the cooling unit 903 is not particularly limited, but it is possible to adopt, for example, a system using a Peltier element or a system that circulates liquid cooled by a chiller. In the latter case, a cooling pipe that circulates the cooling liquid may be wrapped around the outer periphery of the first storage chamber 900 as shown in FIG. 12, or the first storage chamber 900 may have a hollow structure and the cooling pipe may be disposed within the hollow structure. Also, the cooling pipe may be immersed in the liquid W in the first storage chamber 900.

With the above configuration, in this embodiment, a circulation path is formed for the liquid W that flows from the first storage chamber 900, through the gas dissolving section 800 and the UFB generating section 1000, and then returns to the first storage chamber 900.

In FIG. 12, pump 701 is disposed between gas dissolving section 800 and UFB generating section 100 to promote circulation of the entire circulation path, but the position and number of pumps are not limited to this. The pump may be disposed, for example, between UFB generating section 1000 and first storage chamber 900, or may be disposed both between gas dissolving section 800 and UFB generating section 100 and between UFB generating section 1000 and first storage chamber 900. Furthermore, pumps and valves required for the operation of each section may be provided in the configuration of each section. However, it is preferable to use a pump with small pulsation and flow rate variation so as not to impair the generation efficiency of UFB.

In addition, the recovery path and valve 904 for recovering the liquid W may be provided at another position in the liquid circulation path, rather than in the first storage chamber 900. Furthermore, if the temperature rise of the UFB generation unit 1000 is rapid, the UFB generation unit 1000 may also be provided with a cooling unit similar to that of the first storage chamber 900.

The solubility sensor 805, temperature sensor 905, and UFB concentration sensor 906 do not necessarily have to be provided at the positions shown in FIG. 12. These sensors may be provided at other positions within the circulation path. Furthermore, the sensors may be provided at multiple positions within the circulation path, and an average value may be output.

It is preferable that components that come into contact with the UFB-containing liquid, such as the piping 700, pump 701, filter 1001, first storage chamber 900, and liquid-contacting parts of the UFB generation unit 1000, are made of highly corrosion-resistant materials. For example, fluororesins such as polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA), metals such as SUS316L, and other inorganic materials can be suitably used. This makes it possible to suitably generate UFB even when using highly corrosive gas G or liquid W.

Figure 13 is a block diagram for explaining the control configuration of the UFB-containing liquid manufacturing apparatus 2000 of this embodiment. The CPU 2001 controls the entire apparatus according to a program stored in the ROM 2002, using the RAM 2003 as a work area.

The pump control unit 2004, under the instruction of the CPU 2001, controls the operation of various pumps including pumps 602, 603, and 701 included in the circulation path shown in FIG. 12. The valve control unit 2005, under the instruction of the CPU 2001, controls the opening and closing of various valves including valve 904. The sensor control unit 2005, under the instruction of the CPU 2001, controls various sensors including the solubility sensor 805, liquid level sensor 902, temperature sensor 905, and UFB concentration sensor 906, and provides the detection values of the various sensors to the CPU 2001.

For example, when the UFB-containing liquid manufacturing apparatus 2000 starts operating, the CPU 2001 drives the pumps 602 and 603 until the liquid level sensor 902 detects the liquid level, causing a predetermined amount of liquid to be stored in the first storage chamber 900. When the UFB concentration detected by the UFB concentration sensor 906 reaches a predetermined value, the CPU 2001 causes the pump control unit 2004 to stop the operation of the pump 701 and the valve control unit 2005 to open the valve 904, thereby discharging the liquid W contained in the first storage chamber 900.

Figure 14 is a flow chart for explaining the steps executed by the CPU 2001 when producing a desired UFB-containing liquid in the UFB-containing liquid manufacturing apparatus 2000. When this process starts, the CPU 2001 first stores a predetermined amount of liquid in the first storage chamber 900 (S01).

Specifically, the CPU 2001 operates the pumps 602 and 603 while monitoring the detection of the liquid level sensor 902. As a result, the liquid W stored in the liquid supply unit 600 is sent to the first storage chamber 900 while being degassed in the degassing unit 604. Then, when the liquid level sensor 902 detects the liquid level, the CPU 2001 stops the operation of the pumps 602 and 603. As a result, a predetermined amount of liquid W is stored in the first storage chamber 900.

Next, the CPU 2001 starts adjusting the temperature of the liquid W contained in the first storage chamber 900 (S02). Specifically, the CPU 2001 operates the cooling unit 903 while monitoring the temperature detected by the temperature sensor 905. Then, when the temperature detected by the temperature sensor 905 becomes 20° C. or lower, the process proceeds to S03.

In S03, the CPU 2001 operates the gas dissolving unit 800 and drives the pump 701 under first circulation conditions to circulate the liquid W while monitoring the detection of the solubility sensor 805. In this embodiment, the first circulation conditions are suitable circulation conditions for dissolving the gas G in the liquid W. In this embodiment, such first circulation conditions are a liquid flow rate of 300 to 3000 mL/min and a flow pressure of 0.2 to 0.6 MPa in the circulation path. That is, in S03, the CPU 2001 causes the pump control unit 2004 to drive the pump 701 so that such flow rate and flow pressure are maintained.

For example, if the UFB generation unit is configured like a Venturi system, that is, a system that generates UFB by passing the liquid through a specific flow path structure, it is not possible to stop the generation of UFB without stopping the flow of the liquid, and bubbles of an unintended size may be generated. However, since the present embodiment employs the T-UFB system, UFB will not be generated in the UFB generation unit 1000 unless a voltage is applied to the heating element (heater). In other words, by not operating the UFB generation unit 1000 in S03, it is possible to efficiently increase only the solubility of gas G in the circulating liquid W under the first circulation conditions without generating UFB.

When the solubility sensor 805 detects a predetermined solubility, the CPU 2001 stops the operation of the gas dissolving unit 800 and the pump 701 (S04). This stops the circulation of the liquid W, and the first storage chamber 900 becomes a state in which the liquid W in which the desired gas G dissolves at the desired solubility is stored.

In S05, the CPU 2001 drives the pump 701 under second circulation conditions to circulate the liquid W. In this embodiment, the second circulation conditions are circulation conditions suitable for causing the UFB generating unit 1000 to generate UFB. In this embodiment, such second circulation conditions are a liquid flow rate of 10 to 300 mL/min in the circulation path and a flow pressure of 0.1 to 0.3 MPa. That is, in S02, the CPU 2001 causes the pump control unit 2004 to drive the pump 701 so that such flow rate and flow pressure are maintained.

Furthermore, the CPU 2001 operates the UFB generation unit 1000 while monitoring the detection of the UFB concentration sensor 06. At this time, the CPU 2001 does not operate the gas dissolving unit 800. In other words, in the circulating liquid W, the UFB concentration is efficiently increased under the second circulation conditions.

When the UFB concentration sensor 906 detects a predetermined UFB concentration, the CPU 2001 stops the operation of the UFB generation unit 1000 and the pump 701 (S06). This stops the circulation of the liquid W, and the first storage chamber 900 becomes a state in which the UFB-containing liquid W containing the UFB of the desired gas G at the desired concentration is stored.

In S07, the CPU 2001 opens the valve 904 and discharges the UFB-containing liquid W contained in the first storage chamber 900 into an external recovery container. At this time, the CPU 2001 may discharge all of the liquid W contained in the first storage chamber 900, or may discharge only a portion of the liquid W.

In S08, the CPU 2001 determines whether the liquid W collected in the collection container has reached the target amount. If the target amount has not been reached, the CPU 2001 returns to S01 and repeats steps S01 to S07. On the other hand, if it is determined in S08 that the target amount has been reached, this process ends.

According to the present embodiment described above, the process of dissolving the desired gas G and the process of generating UFB are separate processes, and the liquid is circulated under circulation conditions suitable for each process. Specifically, in the process of dissolving the desired gas G, the liquid is circulated at a relatively fast flow rate and high pressure in order to promote dissolution of the gas at the junction 802. On the other hand, in the process of generating UFB, the T-UFB method that utilizes film boiling is adopted, and therefore the liquid is circulated under conditions suitable for the occurrence of film boiling, that is, at a slower flow rate and lower pressure (approximately atmospheric pressure) than the first circulation conditions. This makes it possible to generate a UFB-containing liquid of the desired gas G more efficiently than before.

The specific values of the flow rate and pressure in the first and second circulation conditions described above can be changed in various ways depending on the type of gas G and liquid W. For example, the flow rate and pressure in the first circulation condition and the flow rate and pressure in the second circulation condition can be made different depending on the combination of the type of gas G and the type of liquid W. In this case, a table in which the drive parameters of the pump 701 corresponding to the combination of gas G and liquid W for each of the first and second circulation conditions can be stored in advance in the ROM. In this way, the CPU 2001 can set appropriate drive parameters for each of the first and second circulation conditions based on the combination of gas G and liquid W used.

The first and second circulation conditions may also include conditions other than flow rate and pressure, such as temperature. In this case, the CPU 2001 will set the adjusted temperature of the liquid W to different values in S03 and S05.

For example, the second circulation condition may be set at a lower temperature than the first circulation condition. Depending on the length of the piping from the first storage chamber 900 to the UFB generation unit 1000, there is a possibility of a slight temperature rise. This may cause some of the gas G dissolved in the liquid W to precipitate as bubbles, which may reduce the efficiency of UFB generation, and the higher the solubility of the gas, the greater the amount of bubbles generated due to the temperature rise. By setting the liquid temperature during UFB generation lower than that during dissolution and preventing the liquid temperature from rising above 20°C while the liquid W is being supplied from the first storage chamber 900 to the UFB generation unit 1000, the occurrence of such problems can be suppressed and UFB can be generated stably.

Second Embodiment
15 is a schematic diagram of a UFB-containing liquid manufacturing apparatus 2000 according to the second embodiment. The UFB-containing liquid manufacturing apparatus 2000 according to the present embodiment is different from the first embodiment shown in FIG. 12 in that two circulation paths are provided for the first storage chamber 900. The circulation path A indicated by the arrow A in the figure is a circulation path that returns from the first storage chamber 900 to the first storage chamber 900 via the gas dissolving unit 800, and is driven by the first pump 702. The circulation path B indicated by the arrow B is a circulation path that returns from the first storage chamber 900 to the first storage chamber 900 via the UFB generating unit 1000, and is driven by the second pump 703.

By providing two such circulation paths, the UFB-containing liquid manufacturing apparatus 2000 of this embodiment can carry out the process of dissolving the desired gas G and the process of generating UFB using independent circulation paths set to circulation conditions suitable for each process.

Figure 16 is a flow chart for explaining the process executed by the CPU 2001 when producing a desired UFB-containing liquid in the UFB-containing liquid manufacturing apparatus 2000 of this embodiment. In the UFB-containing liquid manufacturing apparatus 2000 of this embodiment, the control configuration is the same as that of the first embodiment shown in the block diagram of Figure 13.

In Figure 16, S11 and S12 are the same as S01 and S02 described in Figure 14, so their explanation will be omitted here.

In S13, the CPU 2001 operates the gas dissolving unit 800 and drives the first pump 702 under the first circulation condition to start circulating the liquid W in the circulation path A. The contents of the first circulation condition are the same as those in the first embodiment. Then, such circulation in the circulation path A is continued until the solubility sensor 805 detects a predetermined solubility. When the solubility sensor 805 detects the predetermined solubility, the CPU 2001 stops the operation of the gas dissolving unit 800 and the first pump 702 (S14).

Meanwhile, the CPU 2001 starts circulation on circulation path B (S15). Specifically, the second pump 703 is driven under the second circulation condition, and the UFB generation unit 1000 is operated. The content of the second circulation condition is also the same as that of the first embodiment. Then, this circulation on circulation path B continues until the UFB concentration sensor 906 detects a predetermined UFB concentration. When the UFB concentration sensor 906 detects the predetermined UFB concentration, the CPU 2001 stops the operation of the UFB generation unit 1000 and the second pump 703 (S16).

When both circulation in circulation path A and circulation in circulation path B have stopped, the CPU 2001 proceeds to S17, opens the valve 904, and discharges the liquid W contained in the first storage chamber 900 into an external recovery container. The following steps are the same as those in the flowchart described in FIG. 14, and therefore will not be described here.

Figure 17 is a flowchart for explaining a modified example of the second embodiment. The difference from the flowchart in Figure 16 is that S19 is provided in circulation path A, and S14 is moved to the end of the flow. In this example, when the solubility sensor 805 detects a predetermined solubility, the CPU 2001 switches the circulation conditions of circulation path A from the first circulation conditions to the third circulation conditions (S19) while maintaining the operation of the gas dissolving unit 800.

In this modified example, the third circulation condition is a condition for replenishing the gas solubility in the liquid that is reduced by the generation of UFB. The conditions may be the same as the first circulation conditions, but a slower flow rate and lower pressure than the first circulation conditions may be used in order not to destroy the generated UFB. Alternatively, the flow rate and pressure may be the same as the first circulation conditions, and circulation and stopping under the first circulation conditions may be periodically repeated. In any case, according to this modified example, the gas solubility in the liquid W can be maintained at a suitable value regardless of the UFB content concentration, and the generation efficiency of UFB can be further improved.

As described above, according to the second embodiment described with reference to Figures 15 to 17, both circulation paths A and B are shorter than the circulation paths shown in the first embodiment, so each process can be completed in a shorter time than in the first embodiment. In addition, the process of dissolving gas G using circulation path A and the process of generating UFB using circulation path B can be performed under circulation conditions suitable for each path, making it possible to produce the desired UFB-containing liquid more efficiently.

In addition, according to this embodiment, the path (circulation path A) through which the liquid flows at a relatively high flow rate and high pressure can be made shorter than in the first embodiment, making it possible to realize a UFB-containing liquid manufacturing device that is less expensive and smaller, and is also expected to facilitate maintenance.

Third Embodiment
18 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus 2000 according to the third embodiment. The UFB-containing liquid manufacturing apparatus 2000 according to the present embodiment differs from the second embodiment shown in FIG. 15 in that a second storage chamber 950 is added.

The second storage chamber 950 is smaller than the first storage chamber 900, and has a volume of about 1/100 to 1/5 of the first storage chamber 900. The second storage chamber 950 is also preferably formed of a material with high corrosion resistance, like the first storage chamber 900, and for example, fluororesins such as PTFE and PFA, metals such as SUS316L, and other inorganic materials can be suitably used. The second storage chamber 950 has a configuration similar to that of the first storage chamber 900, and is equipped with a temperature sensor 955, a liquid level sensor 952, and a cooling unit 953. However, in this embodiment, the UFB concentration sensor 956 for detecting the UFB concentration and the piping and valve 954 for discharging the UFB-containing liquid to an external container are provided only in the second storage chamber 950, not in the first storage chamber 900. In addition, it is preferable to keep the piping between the first storage chamber 900 and the second storage chamber 950 as short as possible so that the liquid temperature does not rise when the liquid W is supplied from the first storage chamber 900 to the second storage chamber 950.

Circulation path A indicated by arrow A in the figure is a circulation path that returns from the first storage chamber 900 via the gas dissolving section 800 to the first storage chamber 900, and is driven by the first pump 702. Circulation path B indicated by arrow B in the figure is a circulation path that returns from the second storage chamber 950 via the UFB generating section 1000 to the second storage chamber 950, and is driven by the third pump 704. Furthermore, the path indicated by arrow C in the figure is a path for sending liquid W from the first storage chamber 900 to the second storage chamber 950, and is driven by the fourth pump 705.

In the UFB-containing liquid manufacturing apparatus 2000 of this embodiment, the circulation path A for dissolving the desired gas G and the circulation path B for generating UFB are independent and do not merge with each other. Therefore, even if liquid is simultaneously flowed through these two circulation paths, the circulation conditions such as flow rate and pressure do not affect each other, and conditions suitable for each circulation path can be maintained with high precision. For example, the flow rate and pressure of the first circulation condition may be faster and higher than those of the first and second embodiments in order to further increase the efficiency of dissolving the gas into the liquid W. In addition to the flow rate and pressure, the liquid temperature of the circulation path may also be included in the circulation conditions, and the temperatures adjusted for the circulation paths A and B may be different. That is, a temperature suitable for dissolving the desired gas G may be set under the first circulation condition, and a temperature lower than that may be set under the second circulation condition.

Figure 19 is a flow chart for explaining the process executed by the CPU 2001 when producing a desired UFB-containing liquid in the UFB-containing liquid manufacturing apparatus 2000 of this embodiment. In the UFB-containing liquid manufacturing apparatus 2000 of this embodiment, the control configuration is the same as that of the first embodiment shown in the block diagram of Figure 13.

In Figure 19, S21 and S22 are the same as S01 and S02 described in Figure 14, so we will not repeat the explanation here.

In S23, the CPU 2001 operates the gas dissolving unit 800 and drives the first pump 702 under the first circulation condition to start circulation in the circulation path A. At this time, the CPU 2001 does not operate the third pump 704 and the fourth pump 705. The contents of the first circulation condition may be the same as those in the first embodiment, or may be a faster flow rate and a higher pressure than those in the first embodiment. Then, such circulation in the circulation path A continues until the solubility sensor 805 detects the predetermined solubility.

When the solubility sensor 805 detects a predetermined solubility, the CPU 2001 sends a portion of the liquid W contained in the first storage chamber 900 to the second storage chamber 950 (S24). Specifically, first, the operation of the gas dissolving unit 800 and the first pump 702 is stopped. Then, while monitoring the detection of the liquid level sensor 952 provided in the second storage chamber 950, the fourth pump 705 is operated, and when the liquid level sensor 952 detects the liquid level, the fourth pump 705 is stopped. As a result, a predetermined amount of liquid W is stored in the second storage chamber 950.

Next, the CPU 2001 supplies the amount of liquid W sent to the second storage chamber 950 in S24 from the liquid supply unit 600 back to the first storage chamber 900 (S26). That is, the CPU 2001 operates the pumps 602 and 603 until the liquid level sensor 902 detects the liquid level.

When the temperature detected by the temperature sensor 905 falls below 20°C, the CPU 2001 resumes the operation of the gas dissolving unit 800 and drives the first pump 702 under the third circulation condition to circulate the liquid W through the circulation path A (S27). In this embodiment, the third circulation condition is a suitable condition for replenishing the gas solubility that has been reduced by the inflow and outflow of the liquid W performed in S24 and S29 to the desired solubility again. The flow rate and pressure may be the same as those of the first circulation condition, or may be different from those of the first circulation condition. In addition, the flow rate and pressure may be the same as those of the first circulation condition, and circulation and stopping under the first circulation condition may be intermittently repeated.

When the solubility sensor 805 detects a predetermined solubility, the CPU 2001 stops the operation of the gas dissolving unit 800 and the first pump 702 (S28). However, stopping the operation of the first pump 702 is not essential. In other words, in the subsequent steps, circulation path A may be left circulating.

Meanwhile, in parallel with S26 to S28, the CPU 2001 also performs circulation control of the circulation path B. First, the CPU 2001 starts temperature adjustment of the liquid W contained in the second storage chamber 950 (S25). Specifically, the cooling unit 953 is operated while monitoring the temperature detected by the temperature sensor 955. At this time, the temperature range of the second circulation condition may be equal to 10°C or less as the first circulation condition, but may be set to a lower temperature for the same reason as described in the first embodiment. In addition, if the second storage chamber 950 is formed of SUS316L or the like having a relatively high thermal conductivity, cooling of the second storage chamber 950 may be started before S24. As a result, the temperature adjustment under the second circulation condition can be performed while maintaining the liquid temperature of the liquid W supplied to the second storage chamber 950 at 20°C or less, so that the dissolved gas G is prevented from precipitating as bubbles, and UFB can be efficiently generated.

When the CPU 2001 confirms that the temperature detected by the temperature sensor 955 is within the temperature range of the second circulation condition described above, it drives the third pump 704 under the second circulation condition to circulate the liquid W through the circulation path B, and starts the operation of the UFB generation unit 1000 (S29). The content of the second circulation condition may be the same as that of the first embodiment, or may be a condition different from that of the first embodiment. In any case, it is sufficient that a flow rate and pressure suitable for generating UFB are set. The CPU 2001 continues this circulation through the circulation path B until the UFB concentration sensor 956 provided in the second storage chamber 950 detects a predetermined UFB concentration.

When the UFB concentration sensor 956 detects a predetermined UFB concentration, the CPU 2001 stops the operation of the UFB generation unit 1000 and the third pump 704 (S30). The CPU 2001 then opens the valve 954 and discharges the liquid W contained in the second storage chamber 950 into an external collection container (S31).

Here, in the first storage chamber 900, the time required from when the supply of new liquid from the liquid supply unit 600 begins until the desired gas G is dissolved in the liquid to the desired solubility (the time required for S27) is T1. In addition, in the second storage chamber 950, the time required from when the supplied liquid W is made into a UFB-containing liquid of the desired concentration until the discharge into the collection container is completed (the time required for S25 to S31) is T2. At this time, in this embodiment, it is assumed that T1≦T2 is satisfied. By satisfying the above condition, when the discharge from the second storage chamber 950 to the collection container is completed, the first storage chamber 900 contains liquid W in which the desired gas is dissolved at the desired dissolution concentration, and the UFB generation process can be continued without waste.

In S32, the CPU 2001 determines whether the liquid W collected in the collection container has reached the target amount. If the target amount has not been reached, the CPU 2001 returns to S24 and again sends the liquid from the first storage chamber 900 to the second storage chamber 950. At this time, the liquid stored in the first storage chamber 900 is a liquid in which the desired gas has already been dissolved at the desired solubility.

On the other hand, if it is determined in S32 that the amount of liquid W collected in the collection container has reached the desired amount, this process ends.

According to the present embodiment described above, the process of dissolving gas G through circulation path A and the process of generating UFB through circulation path B can be carried out simultaneously in parallel under circulation conditions suitable for each. Furthermore, since circulation paths A and B are independent and do not merge with each other, it is possible to maintain conditions suitable for each circulation flow path with even greater precision.

Fourth Embodiment
20 is a schematic diagram of a UFB-containing liquid manufacturing apparatus 2000 in the fourth embodiment. The UFB-containing liquid manufacturing apparatus 2000 of this embodiment is different from the third embodiment shown in FIG. 18 in that a path indicated by an arrow D in the figure is added. The path indicated by the arrow D in the figure is a path for sending the liquid W from the second storage chamber 950 to the first storage chamber 900, and is driven by a fifth pump 706. In addition, the second storage chamber 950 of this embodiment is provided with a lower limit sensor 957 for managing the lower limit of the liquid level, in addition to a liquid level sensor 952 for managing the upper limit of the liquid level. The fourth pump 705 for sending the liquid W from the first storage chamber 900 to the second storage chamber 950 and the fifth pump 706 for sending the liquid W from the second storage chamber 950 to the first storage chamber 900 may be the same pump, or may have different liquid sending capabilities.

According to this embodiment having the above configuration, the liquid W in the UFB production process in the circulation path B can be returned to the gas dissolution process in the circulation path A. In other words, the gas solubility that has decreased due to the production of UFB can be adjusted back to an appropriate solubility by returning it to the circulation path A.

Figure 21 is a flow chart for explaining the process executed by the CPU 2001 when producing a desired UFB-containing liquid in the UFB-containing liquid production apparatus 2000 of this embodiment. In the UFB-containing liquid production apparatus 2000 of this embodiment, the control configuration is the same as that of the first embodiment shown in the block diagram of Figure 13.

In FIG. 21, steps S41 to S45 are the same as steps S21 to S25 described in FIG. 19, so the description here is omitted. However, in S44, the CPU 2001 does not stop the first pump 702, and keeps the circulation in the circulation path A.

In S46, the CPU 2001 drives the third pump 704 under the second circulation condition to circulate the liquid W through the circulation path B, and starts the operation of the UFB generation unit 1000.

Next, the CPU 2001 determines whether the UFB concentration sensor 956 has detected a predetermined UFB concentration (S47). If it is determined that the predetermined UFB concentration has not been reached, a portion of the liquid W contained in the second storage chamber 950 is returned to the first storage chamber 900 (S48). Specifically, the fifth pump 706 is operated while monitoring the detection of the lower limit sensor 957 provided in the second storage chamber 950, and the operation of the fifth pump 706 is stopped when the lower limit sensor 957 detects the liquid level. This causes a predetermined amount of liquid W to be returned from the second storage chamber 950 to the first storage chamber 900.

When the solubility sensor 805 detects a predetermined solubility, the CPU 2001 sends a portion of the liquid W stored in the first storage chamber 900 back to the second storage chamber 950 (S49). Specifically, the fourth pump 705 is operated while monitoring the detection of the liquid level sensor 952 provided in the second storage chamber 950, and the operation of the fourth pump 705 is stopped when the liquid level sensor 952 detects the liquid level. This causes a predetermined amount of liquid W to be sent from the first storage chamber 900 to the second storage chamber 950. Then, the steps of S48 and S49, i.e., the steps of flowing in and out of the liquid W between the first storage chamber 900 and the second storage chamber 950, are repeated until the UFB concentration sensor 956 detects the predetermined UFB concentration.

When it is determined in S47 that the UFB concentration sensor 956 has detected a predetermined UFB concentration, the CPU 2001 stops the UFB generation unit 1000 and circulation through circulation path B (S50). Then, the valve 954 is opened, and the liquid W contained in the second storage chamber 950 is discharged into an external recovery container (S51).

In S52, the CPU 2001 determines whether the liquid W collected in the collection container has reached the target amount. If the target amount has not been reached, the CPU 2001 returns to S41 and repeats steps S41 to S51. On the other hand, if it is determined in S52 that the target amount has been reached, the CPU 2001 stops the circulation of the circulation path A and the operation of the gas dissolving unit 800 (S53), and the process ends.

According to the present embodiment described above, the gas dissolution process in the circulation path A and the UFB production process in the circulation path B can be continuously performed regardless of the movement of the liquid W between the first storage chamber 900 and the second storage chamber 950 or the discharge of the liquid from the second storage chamber 950. Therefore, the production efficiency of the UFB-containing liquid can be further improved compared to the embodiment described above.

In the present embodiment shown in FIG. 20, the transport rate of the fourth pump 705 and the transport rate of the fifth pump 706 are made equal, and furthermore, by operating them simultaneously, a new circulation path CD having the paths of arrows C and D can be formed. In this case, the first storage chamber 900 and the second storage chamber 950 can be regarded as one large storage chamber, and the form is substantially the same as that of the second embodiment described in FIG. 15. In such a case, an independent circulation condition may be set for the circulation path CD. That is, while the circulation path A is circulated under the first circulation condition and the circulation path B is circulated under the second circulation condition, the circulation path CD may be circulated under a circulation condition different from both the first circulation condition and the second circulation condition.

In addition, in the present embodiment shown in FIG. 20, while both the fourth pump 705 and the fifth pump 706 are stopped, a configuration similar to that of the third embodiment described in FIG. 18 can be realized. That is, in the UFB-containing liquid manufacturing apparatus 2000 of the present embodiment shown in FIG. 20, the manufacturing method of the second embodiment and the manufacturing method of the third embodiment can be switched depending on various circumstances such as the type of UFB-containing liquid to be produced and environmental conditions.

Figure 22 is a flow chart for explaining a modified example of the fourth embodiment. In this modified example, after supplying liquid W from the first storage chamber 900 to the second storage chamber 950 (S44), the liquid is circulated in the circulation path A under the third circulation condition to continue dissolving the gas (S54). Meanwhile, the temperature adjustment of the second storage chamber 950 is started (S55), and the circulation path CBD is circulated under the second circulation condition (S56). The details of the circulation operation at this time are the same as those described in Figure 21. If the temperature of the second storage chamber 950 is set to a different temperature from that of the first storage chamber 900, for example, if the temperature of the second storage chamber 950 is set to 15°C and the temperature of the first storage chamber is set to 20°C, the process may proceed to S56 without waiting for the temperature of the second storage chamber 950 to reach 15°C.

When it detects that the values of the solubility sensor 805, the temperature sensor 905, and the temperature sensor 955 have all reached the predetermined values, the CPU 2001 operates the UFB generation unit 1000 (S57). Then, when it determines that the UFB concentration sensor 956 has detected the predetermined UFB concentration, the CPU 2001 stops the UFB generation unit 1000 and the pumps 704, 705, and 706 to stop the circulation in the circulation path CBD.

Then, the valve 954 is opened, and the liquid W contained in the third storage chamber 960 is discharged into an external recovery container (S51). These operations are then repeated until the desired amount of UFB-containing liquid is obtained, in the same manner as described in FIG. 21.

20, while the liquid W is being supplied from the first storage chamber 900 to the second storage chamber 950 and while the liquid temperature in the second storage chamber 950 reaches a predetermined value, the liquid temperature may rise above the temperature adjusted in the first storage chamber 900, causing the solubility of the gas G to decrease. Even in such a case, according to this modified example, UFB generation can be started in S57 after steps S54 and S56, so that UFB can be generated stably and efficiently regardless of the length of the path C or the material of the second storage chamber 950.

Fifth Embodiment
Fig. 23 is a schematic diagram of a UFB-containing liquid manufacturing apparatus 2000 according to the fifth embodiment. The UFB-containing liquid manufacturing apparatus 2000 according to the present embodiment is different from the fourth embodiment shown in Fig. 20 in that the route from the UFB generation unit 1000 back to the first storage chamber 900 does not pass through the second storage chamber 950.

In the UFB-containing liquid manufacturing apparatus 2000 of this embodiment, when the desired UFB-containing liquid is manufactured, the process executed by the CPU 2001 is the same as that described in FIG. 22. However, the notation of the circulation path CBD in S56 in FIG. 22 is now the circulation path CB. The flow rates of paths C and B may be the same or different, but if they are different, the flow rate of path C is set to be greater than that of path B.

When the amount of heat generated in the UFB generating unit 1000 becomes relatively large, the temperature of the liquid W rises and the dissolved gas G may precipitate as bubbles. If these bubbles are returned to the second storage chamber 950 as shown in FIG. 20, the liquid temperature in the second storage chamber 950 may change, or the bubbles sent from the UFB generating unit 1000 may be supplied to the UFB generating unit 1000 again. In this case, there is a concern that the UFB generation efficiency in the UFB generating unit 1000 may be impaired, and this concern becomes even greater when a gas with high solubility is selected.

In this embodiment, the liquid that passes through the UFB generation unit 1000 returns to the first storage chamber 900, which avoids the above concerns and allows efficient UFB generation to continue.

The capacity of the first storage chamber 900 is sufficiently larger than that of the second storage chamber 950, and is therefore less susceptible to temperature changes. In addition, by positioning the end position of path C at a position higher than the tip position of path B, the possibility of air bubbles entering the second storage chamber 950 and being supplied to the UFB generating unit 1000 is reduced, and more stable UFB generation can be achieved. This type of piping positional relationship can also be applied to the first storage chamber 900. By positioning the end positions of paths A and B at a position higher than the tip of path C, it is possible to further suppress the entry of air bubbles into the second storage chamber 950.

Sixth Embodiment
24 is a schematic diagram of a UFB-containing liquid manufacturing apparatus 2000 according to the sixth embodiment. The UFB-containing liquid manufacturing apparatus 2000 according to the present embodiment is configured to directly supply the liquid W from the first storage chamber 900 to the UFB generation unit 1000, and supply the liquid W from the UFB generation unit 1000 to the first storage chamber 900 via a third storage chamber 960.

The third storage chamber 960, like the second storage chamber 950, is smaller than the first storage chamber 900 and has a volume of about 1/100 to 1/5 of the first storage chamber 900. The third storage chamber 960 is made of a highly corrosion-resistant material such as fluororesins such as PTFE and PFA, metals such as SUS316L, and other inorganic materials. The third storage chamber 960 is also provided with liquid level sensors 962, 967, a UFB concentration sensor 966 for detecting the UFB concentration, and a pipe and valve 964 for discharging the UFB-containing liquid to an external container. The third storage chamber 960 is downstream of the UFB generation unit 1000, so no cooling unit is required, but a cooling unit may be provided depending on the purpose.

The third storage chamber 960 is provided with a UFB filter 968 at a position below the height of the liquid level sensor 967, and the interior of the third storage chamber 960 is divided into a UFB-containing liquid storage chamber 960a and a liquid storage chamber 960b by the UFB filter 968. The hole diameter of the UFB filter 968 is about 1 μm. The circulation path BD is configured so that the end of path B is located in the UFB-containing liquid storage chamber 960a and the end of path D is located in the liquid storage chamber 960b. With this configuration, of the UFB-containing liquid supplied from the UFB generation unit 1000, UFB is stored inside the UFB-containing liquid storage chamber 960a, and liquid W that does not contain UFB moves into the liquid storage chamber 960b and is further supplied to the first storage chamber 900.

In the UFB-containing liquid manufacturing apparatus 2000 of this embodiment, the flow chart of the process executed by the CPU 2001 when manufacturing the desired UFB-containing liquid is as shown in FIG. 25, and is almost the same as that described in FIG. 17. The flow rates of paths B and D may be the same or different. When the flow rates of paths B and D are different, the flow rate of path D is set to be greater than the flow rate of path B.

While the UFB generating unit 1000 is generating UFB, the liquid is circulated in the circulation path A under the third circulation conditions to dissolve the gas (S19). In the case of this embodiment, the UFB generated in the UFB generating unit 1000 does not flow into the first storage chamber 900, so there is no risk of the circulating UFB being destroyed at the junction 802 or the like. Therefore, the third circulation condition does not need to be set to a flow rate or pressure lower than the first circulation condition in order to prevent destruction of the UFB, and can be freely set.

In this embodiment, once the UFB is generated, it remains in the UFB-containing liquid storage chamber 960a without passing through various paths or the UFB generation unit 1000. Therefore, by controlling the operating time of the UFB generation unit 1000, it is possible to stably produce a UFB-containing liquid of the desired concentration.

When the CPU 2001 determines that the UFB concentration sensor 966 has detected a predetermined UFB concentration, it first stops the operation of the UFB generation unit 1000 and the pump 705 to stop the supply of liquid W only to path B (S61). Then, when the liquid level sensor 967 detects the liquid level, the CPU 2001 stops the pump 706 to stop the flow of liquid W in path D (S62). After that, the CPU 2001 opens the valve 964 and discharges the liquid W contained in the third storage chamber 960 into an external recovery container (S17).

The present embodiment described above is particularly effective when using gas G with a relatively low solubility and producing a highly concentrated UFB-containing liquid by repeatedly circulating through circulation path A.

Figure 26 is a schematic diagram of a UFB-containing liquid manufacturing apparatus 2000 as a modified example of the sixth embodiment. While the UFB filter 968 is arranged horizontally in Figure 24, the UFB filter 968 is arranged vertically in Figure 26.

In the case of FIG. 24, if air bubbles get into the UFB-containing liquid storage chamber 960a, the air bubbles that rise due to buoyancy may block the UFB filter 968, reducing the effective area of the UFB filter 968. In contrast, in this flexible configuration, the air bubbles that rise due to buoyancy are released to the atmosphere, so the effective area of the UFB filter 968 is maintained and stable circulation operation can be continued. In addition, by making the volume of the UFB-containing liquid storage chamber 960a larger than the volume of the liquid storage chamber 960b, the amount of UFB-containing liquid that can be collected at one time can be increased.

Seventh embodiment
FIG. 27 is a schematic configuration diagram of a UFB-containing liquid manufacturing apparatus 2000 according to the seventh embodiment.

The UFB-containing liquid manufacturing apparatus 2000 of this embodiment is configured to supply liquid W from the first storage chamber 900 to the UFB generation unit 1000 via the second storage chamber 950, and supply liquid W from the UFB generation unit 1000 to the first storage chamber 900 via the third storage chamber 960.

The configurations and functions of the second storage chamber 950 and the third storage chamber 960 are the same as those described above, and the capacity of the first storage chamber 900 is formed to be sufficiently larger than the sum of the capacities of the second storage chamber 950 and the third storage chamber 960.

Figure 28 is a flowchart of the process executed by the CPU 2001 when producing a desired UFB-containing liquid in the UFB-containing liquid production apparatus 2000 of this embodiment. Figure 28 is almost the same as the flowchart described in Figure 22. When the CPU 2001 determines that the UFB concentration sensor 966 has detected a predetermined UFB concentration, it first stops the operation of the UFB generation unit 1000 and the pump 705 to stop the supply of liquid W only to path CB (S71). Then, when the liquid level sensor 967 detects the liquid level, the CPU 2001 stops the pump 706 to stop the supply of liquid W to path D (S72). After that, the CPU 2001 opens the valve 964 and discharges the liquid W contained in the third storage chamber 960 to an external recovery container (S51).

The configuration of this embodiment makes it possible to efficiently generate UFB in the UFB generating unit 1000 and produce a high-concentration UFB-containing liquid, regardless of the type of gas G. Although FIG. 27 shows a case where one type of gas G is connected, it is also suitable for a case where multiple gases G are connected in a switchable manner.

700 Pipe 800 Gas dissolving section 1000 UFB generating section 2001 CPU

Claims (20)

A dissolving means for dissolving a predetermined gas in a liquid;
an ultra-fine bubble generating means for generating ultra-fine bubbles in the liquid having the predetermined gas dissolved therein;
a circulation control means for controlling the circulation of the liquid in a liquid circulation path including the dissolving means and the ultra-fine bubble generating means;
A chamber for containing a liquid;
An apparatus for producing ultra-fine bubble-containing liquid, comprising:
The circulation control means includes:
When the dissolving means is operated in the circulation path passing through the dissolving means, the liquid is circulated according to a first condition that determines the state of the circulating liquid, and when the ultra-fine bubble generating means is operated in the circulation path passing through the ultra-fine bubble generating means, the liquid is circulated according to a second condition that is different from the first condition,
a first circulation path that runs from the storage chamber through the dissolving means and returns to the storage chamber without passing through the ultra-fine bubble generating means, the liquid is circulated according to the first condition when the dissolving means is operated;
An apparatus for manufacturing ultra-fine bubble-containing liquid, characterized in that in a second circulation path that runs from the storage chamber through the ultra-fine bubble generating means and back to the storage chamber without passing through the dissolving means, the liquid is circulated according to the second condition when the ultra-fine bubble generating means is operated. The circulation control means is configured to control the circulation path from the storage chamber through the dissolving means and the ultra-fine bubble generating means to the storage chamber,
2. The apparatus for producing ultra-fine bubble-containing liquid according to claim 1, wherein when the dissolving means is operated and the ultra-fine bubble generating means is not operated, the liquid is circulated according to the first condition, and when the dissolving means is not operated and the ultra-fine bubble generating means is operated, the liquid is circulated according to the second condition. The ultra-fine bubble-containing liquid manufacturing device according to claim 1 or 2, further comprising a liquid supply means for supplying liquid to the storage chamber, and a discharge means for discharging liquid from the storage chamber. A dissolving means for dissolving a predetermined gas in a liquid;
an ultra-fine bubble generating means for generating ultra-fine bubbles in the liquid having the predetermined gas dissolved therein;
a circulation control means for controlling the circulation of the liquid in a liquid circulation path including the dissolving means and the ultra-fine bubble generating means;
a first chamber and a second chamber for containing a liquid;
a means for supplying liquid from the first chamber to the second chamber;
An apparatus for producing ultra-fine bubble-containing liquid, comprising:
The circulation control means includes:
When the dissolving means is operated in the circulation path passing through the dissolving means, the liquid is circulated according to a first condition that determines the state of the circulating liquid, and when the ultra-fine bubble generating means is operated in the circulation path passing through the ultra-fine bubble generating means, the liquid is circulated according to a second condition that is different from the first condition,
a first circulation path that runs from the first storage chamber through the dissolving means and returns to the first storage chamber without passing through the ultra-fine bubble generating means, circulating liquid according to the first condition when the dissolving means is operated;
an ultra-fine bubble-containing liquid manufacturing apparatus comprising: a second circulation path that runs from the second storage chamber through the ultra-fine bubble generating means and back to the second storage chamber without passing through the dissolving means, and the liquid is circulated in accordance with the second condition when the ultra-fine bubble generating means is operated. The apparatus for producing ultra-fine bubble-containing liquid according to claim 4, further comprising a means for supplying the liquid in which ultra-fine bubbles have been generated by the ultra-fine bubble generating means from the second storage chamber to the first storage chamber. The ultra-fine bubble-containing liquid manufacturing device according to claim 5, characterized in that the circulation control means circulates the liquid through a third circulation path consisting of a path for supplying liquid from the first storage chamber to the second storage chamber and a path for supplying liquid from the second storage chamber to the first storage chamber according to circulation conditions different from the first conditions and the second conditions. The ultra-fine bubble-containing liquid manufacturing device according to any one of claims 4 to 6, characterized in that the circulation control means circulates the first circulation path and the second circulation path simultaneously. The apparatus for producing ultra-fine bubble-containing liquid according to claim 7, characterized in that the circulation control means circulates the liquid in the first circulation path according to the first condition when the ultra-fine bubble generating means is not operated, and circulates the liquid in the first circulation path according to a third circulation condition different from the first condition when the ultra-fine bubble generating means is operated. The volume of the second storage chamber is smaller than the volume of the first storage chamber,
9. The apparatus for producing ultra-fine bubble-containing liquid according to claim 4, further comprising: a liquid supplying means for supplying liquid to the first storage chamber; and a discharge means for discharging liquid from the second storage chamber. A dissolving means for dissolving a predetermined gas in a liquid;
an ultra-fine bubble generating means for generating ultra-fine bubbles in the liquid having the predetermined gas dissolved therein;
a circulation control means for controlling the circulation of the liquid in a liquid circulation path including the dissolving means and the ultra-fine bubble generating means;
at least one of a first supply means for supplying liquid from a first storage chamber for storing liquid to the ultra-fine bubble generating means via a second storage chamber for storing liquid, and a second supply means for supplying liquid from the ultra-fine bubble generating means to the first storage chamber via a third storage chamber for storing liquid;
An apparatus for producing ultra-fine bubble-containing liquid, comprising:
The circulation control means includes:
When the dissolving means is operated in the circulation path passing through the dissolving means, the liquid is circulated according to a first condition that determines the state of the circulating liquid, and when the ultra-fine bubble generating means is operated in the circulation path passing through the ultra-fine bubble generating means, the liquid is circulated according to a second condition that is different from the first condition,
a first circulation path that runs from the first storage chamber through the dissolving means and returns to the first storage chamber without passing through the ultra-fine bubble generating means, circulating liquid according to the first condition when the dissolving means is operated;
a second circulation path that passes from the first storage chamber through the ultra-fine bubble generating means and returns to the first storage chamber without passing through the dissolving means;
An apparatus for producing liquid containing ultra-fine bubbles, characterized in that when the ultra-fine bubble generating means is operated, the liquid is circulated in accordance with the second condition. The second supply means is provided,
the third storage chamber is provided with a filter that divides the inside of the third storage chamber into an ultra-fine bubble storage chamber connected to the ultra-fine bubble generating means and a liquid storage chamber connected to the first storage chamber,
11. The apparatus for producing liquid containing ultra-fine bubbles according to claim 10, wherein the ultra-fine bubble storage chamber has a discharge means for discharging the liquid. The ultra-fine bubble-containing liquid manufacturing device according to claim 11, characterized in that the filter is arranged vertically. The apparatus for producing ultra-fine bubble-containing liquid according to claim 11 or 12, characterized in that the volume of the ultra-fine bubble storage chamber is larger than the volume of the liquid storage chamber. The ultra-fine bubble-containing liquid manufacturing device according to any one of claims 10 to 13, characterized in that the sum of the volumes of the second storage chamber and the third storage chamber is smaller than the volume of the first storage chamber. The ultra-fine bubble-containing liquid manufacturing device according to any one of claims 10 to 14, characterized in that the first condition and the second condition determine at least one of the following conditions: flow rate, pressure, and temperature of the liquid. The apparatus for producing ultra-fine bubble-containing liquid according to claim 15, characterized in that the first condition determines a flow velocity faster than the second condition. The apparatus for producing ultra-fine bubble-containing liquid according to claim 15 or 16, characterized in that the first condition specifies a pressure higher than the second condition. The apparatus for producing ultra-fine bubble-containing liquid according to any one of claims 15 to 17, characterized in that the second condition determines a temperature lower than that of the first condition. The apparatus for producing ultra-fine bubble-containing liquid according to any one of claims 1 to 18, characterized in that the circulation control means circulates the liquid according to the first condition and the second condition by controlling the operation of a pump arranged in the circulation path. The apparatus for producing ultra-fine bubble-containing liquid according to any one of claims 1 to 19, characterized in that the ultra-fine bubble generating means generates ultra-fine bubbles by generating heat in a heating element to cause film boiling at the interface between the liquid and the heating element.

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