Device for manufacturing fine bubble-containing liquid, method for manufacturing fine bubble-containing liquid, and fine bubble-containing liquid

Abstract

[Problem] To produce more efficiently a fine bubble-containing liquid in high concentration. [Solution] An ultra fine bubble (UFB) production device 1 is provided with a fine bubble (FB) generation device 10, an FB tank 50, a dead-end filtration filter 507, and a cross-flow filter section 605. The FB generation device 10 generates fine bubbles using a liquid and a gas that have been supplied. The FB tank 50 and the dead-end filtration filter 507 remove fine bubbles that have diameters of a prescribed value or greater from a fine bubble-containing liquid that contains the fine bubbles. The cross-flow filter section 605 raises the fine bubble concentration of the fine bubble-containing liquid from which the fine bubbles with diameters of the prescribed value or greater have been removed.

Description

Microbubble-containing liquid manufacturing apparatus, microbubble-containing liquid manufacturing method, and microbubble-containing liquid

[0001] The present invention relates to an apparatus for producing a microbubble-containing liquid, a method for producing a microbubble-containing liquid, and the microbubble-containing liquid.

[0002] In recent years, technologies have been developed that utilize the properties of fine bubbles (air bubbles), such as microbubbles with diameters of micrometers and nanobubbles with diameters of nanometers. In particular, the usefulness of Ultra Fine Bubbles (trademark) (hereinafter also referred to as "UFB"), which have a diameter of less than 1.0 μm, has been confirmed in various fields. For example, Patent Document 1 describes an apparatus that generates fine bubbles by ejecting a pressurized liquid, in which a gas is pressurized and dissolved by a pressure dissolution method, from a nozzle, and then returns the liquid to a pressure dissolution section and ejects it again from the nozzle, thereby increasing the concentration of Fine Bubbles (trademark) (hereinafter also referred to as "FB").

[0003] JP 2017-080691 A

[0004] In the apparatus described in Patent Document 1, the pressurized dissolution section and the FB generation nozzle are arranged in the same circulation path, so the dissolution conditions and the FB generation conditions are the same. Patent Document 1 also describes a configuration in which only UFBs of a certain size are recovered using a separation membrane, and a configuration in which once-produced UFB water is concentrated by vacuum evaporation to increase the concentration of UFBs. However, depending on the combination of gas and liquid used and the FB generation method, the optimal conditions for dissolution and UFB generation, such as flow rate and pressure, may differ. If the optimal conditions for dissolution and UFB generation differ, both dissolution and UFB generation may not be performed under the most efficient conditions, and highly concentrated UFB water may not be produced. Furthermore, many currently known UFB generation methods generate microbubbles (hereinafter also referred to as "MB") and UFBs in a mixed state. According to ISO / TC281, MB is defined as having a particle size ranging from 1.0 μm to 100.0 μm. MB has high buoyancy and is known to rise to the water surface and disappear within a few minutes to a few tens of minutes, depending on the particle size, or to disappear due to cavitation bursting. On the other hand, UFB is defined according to ISO / TC281 as having a particle size of 1.0 μm or less. It has been demonstrated that UFB is strongly affected by Brownian motion and can remain in liquid for long periods of time. In other words, because MB and UFB have different physical properties, producing highly concentrated UFB water requires that MB be excluded and UFB be selectively dissolved. Thus, with conventional technology, it has been difficult to efficiently produce a highly concentrated liquid containing fine bubbles (liquid containing ultrafine bubbles).

[0005] An object of the present invention is to more efficiently produce a highly concentrated microbubble-containing liquid.

[0006] In order to achieve the above object, an apparatus for producing a microbubble-containing liquid according to one aspect of the present invention is characterized by comprising: a microbubble generating means for generating microbubbles using a supplied liquid and gas; a bubble removing means for removing microbubbles having a diameter equal to or larger than a predetermined value from the microbubble-containing liquid containing the microbubbles; and a concentration increasing means for increasing the microbubble concentration in the microbubble-containing liquid from which the microbubbles having a diameter equal to or larger than the predetermined value have been removed.

[0007] According to the present invention, a highly concentrated microbubble-containing liquid can be produced more efficiently.

[0008] FIG. 1 is a schematic diagram showing the configuration of a UFB generator 1 according to a first embodiment; FIG. 2 is a flowchart showing the flow of a UFB-containing liquid manufacturing process; FIG. 3 is a schematic diagram showing the correlation between gas solubility and device operation time; FIG. 4 is a schematic diagram showing the correlation between UFB concentration and device operation time; FIG. 5 is a schematic diagram showing the correlation between the amount of UFB water produced and device operation time; FIG. 6 is a schematic diagram showing the configuration of a UFB generator 1 according to a second embodiment; FIG. 7 is a schematic diagram showing the configuration of a UFB generator 1 according to a third embodiment; and FIG. 8 is a schematic diagram showing the configuration of a UFB generator 1 according to a fourth embodiment.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [First embodiment] [Configuration] Fig. 1 is a schematic diagram showing the configuration of a UFB generator 1 according to a first embodiment. The UFB generator 1 shows one embodiment of an apparatus for producing a microbubble-containing liquid according to the present invention.

[0010] As shown in FIG. 1 , the UFB generator 1 includes an FB generator 10, a gas supply unit 20, a liquid supply tank 30, an ultrapure water supply tank 40, an FB tank 50, a UFB tank 60, and a control unit 70. Each component except the control unit 70 is connected by piping capable of transporting liquids and gases, as described below. The gas supply unit 20 has a function of supplying a desired gas selected as a gas constituting the UFB, such as oxygen, ozone, carbon dioxide, or nitrogen, to the FB generator 10. The gas supply unit 20 can be configured as a cylinder for storing the desired gas, or it can be configured as a gas generator capable of continuously generating the desired gas. For example, if the desired gas is oxygen, oxygen can be continuously generated by taking in air and removing unnecessary nitrogen, and the generated oxygen can be sent to the FB generator 10 using a built-in pump.

[0011] The gas supply unit 20 is provided with a gas supply container 204 that stores a desired gas, and the gas supplied from the gas supply container 204 can be adjusted to a set pressure by a regulator 201 that adjusts the pressure and supplied to the FB generator 10. The gas whose pressure has been adjusted by the regulator 201 is supplied to the FB generator 10 via a gas supply pipe 203. At this time, a filter 202 that removes impurities can be appropriately installed depending on the purity of the gas stored in the gas supply container 204, and when a low-purity gas is used, impurities are removed by the filter 202.

[0012] The ultrapure water supply tank 40 stores ultrapure water 401 produced by an ultrapure water production apparatus (not shown, for example, Mill-Q manufactured by Merck KGaA). The ultrapure water 401 stored in the ultrapure water supply tank 40 is delivered by a pump 403. The ultrapure water 401 delivered from the pump 403 is delivered to a degassing unit 404 via a pipe 402 communicating with the degassing unit 404.

[0013] In the degassing section 404, gas dissolved in the ultrapure water 401 delivered from the pump 403 is removed. A membrane (not shown) that allows only gas to pass through is installed inside the degassing section 404, and the dissolved gas contained in the ultrapure water 401 is separated from the liquid (ultrapure water) as the gas passes through the membrane. The separated dissolved gas is sucked by the pump 406 and exhausted from the exhaust section 405. By removing the dissolved gas from the supplied ultrapure water 401 in this way, it becomes possible to dissolve the desired gas in the liquid to the maximum extent in the FB generator 10 described below.

[0014] The ultrapure water 401 from which dissolved gases have been degassed is delivered to the liquid supply tank 30 via a pipe 407. The liquid supply tank 30 has a function of storing the liquid 301. The liquid 301 stored in the liquid supply tank 30 is a mixture of the liquid (ultrapure water) delivered from the ultrapure water supply tank 40 and the UFB-containing liquid produced in the FB tank 50 and the UFB tank 60 (described later). A liquid level sensor (not shown) is installed in the liquid supply tank 30 as needed, and the supply of liquid to the liquid supply tank 30 is stopped when the liquid level reaches a predetermined height (detection height of the liquid level sensor). A cooling unit 302 is disposed around the entire or part of the periphery of the liquid supply tank 30, and is configured to be able to cool the liquid 301 in the liquid supply tank 30. Generally, the lower the temperature of the liquid, the higher the solubility of gases can be. Therefore, a lower liquid temperature is preferable. In this embodiment, the liquid temperature detected by a temperature sensor (not shown) is controlled to be approximately 10°C or less.

[0015] The configuration of the cooling unit 302 is not particularly limited as long as it can control the liquid 301 to a desired temperature. For example, a cooling device such as a Peltier element or a system that circulates a cooling liquid cooled to a low temperature by a chiller (not shown) can be employed. In this case, a cooling pipe through which the cooling liquid can circulate can be installed so as to surround the outer periphery of the liquid supply tank 30, or a container that accumulates the liquid 301 in the liquid supply tank 30 can be made hollow so that the cooling liquid passes through the hollow portion. Alternatively, a cooling pipe can be disposed in a storage space where the liquid 301 is stored, and the cooling pipe can be configured to pass through the liquid 301 stored in the liquid supply tank 30. In this way, by controlling the liquid 301 to a low temperature and making it easy for gas to dissolve, the FB generator 10 can efficiently dissolve the gas and improve the FB generation efficiency. The liquid 301 stored in the liquid supply tank 30 is sucked by a pump 304 and supplied to the FB generator 10 via a pipe 303.

[0016] The liquid supply tank 30 is also provided with an outlet 306 for extracting the UFB-containing liquid, and the UFB concentration of the liquid 301 is managed by a concentration sensor (not shown) or the like. When the UFB concentration reaches a predetermined value, a valve 305 installed at the outlet 306 is opened to extract the UFB-containing liquid. The outlet 306 may be located at any location other than the liquid supply tank 30, and may be located downstream of the cross-flow filter unit 605, for example. The interior of the liquid supply tank 30 may be stirred using a stirrer or the like to reduce unevenness in the temperature and solubility of the liquid 301.

[0017] The FB generator 10 mixes gas supplied from the gas supply unit 20 with liquid 301 supplied from the liquid supply tank 30 to generate FB. Methods for generating FB include swirling flow, Venturi, pressurized dissolution, or improved or mixed versions thereof, and are not particularly limited as long as FB can be generated. For example, various methods for generating FB, such as the swirling liquid flow, static mixer, mechanical shear, micropore, ejector, Venturi, pressurized dissolution, heated precipitation, mixed vapor condensation, and electrolysis methods described in "Introduction to Fine Bubbles" (Himuro Shozo et al., published November 28, 2016, Nikkan Kogyo Shimbun), can be used. Note that while FIG. 1 shows a configuration in which a pump 304 is disposed upstream of the FB generator 10, the pump's location is not limited thereto, and the pump can be installed at any location to efficiently generate FB. That is, the pump can be located downstream of the FB generator 10 or both upstream and downstream of the FB generator 10 .

[0018] The FB water 501 generated by the FB generator 10 is stored in the FB tank 50 via piping 504. The FB generator 10 can also be installed inside the FB tank 50, in which case the piping 504 is unnecessary. The FB water 501 stored in the FB tank 50 contains a mixture of MB 502 with a diameter of greater than 1.0 μm and 100.0 μm or less and UFB 503 with a diameter of 1.0 μm or less. In this embodiment, the required UFB is one with a diameter of 1.0 μm or less. Therefore, once a certain amount of FB water 501 has been filled in the FB tank 50 (when a predetermined water level is detected by a liquid level sensor, not shown), the FB water 501 in the FB tank 50 is allowed to stand by for approximately 30 minutes (i.e., the operation of the FB generator 10 is stopped). Generally, FB water 501, which contains a mixture of MB 502 and UFB 503, is cloudy and visible to the naked eye. It is known that MB 502 disappears within a few minutes to several tens of minutes due to buoyancy and cavitation. By leaving FB water 501 for approximately 30 minutes, MB 502 disappears, resulting in FB water 501 with improved UFB 503 purity. Furthermore, preferably, only a colorless, transparent liquid (UFB water 601) is pumped from FB tank 50 to UFB tank 60 via pump 506 and piping 505. At this time, MB 502 is trapped using a dead-end filter 507 with a filter diameter of 0.2 μm or 0.4 μm. As a result, UFB water 601 containing only UFB 602 with a diameter of 1.0 μm or less is stored in UFB tank 60. However, since impurities and bubbles of 1.0 μm or larger are trapped in the dead-end filter 507, a cleaning function (not shown) for the dead-end filter 507 may be provided so that the filter can be cleaned periodically. The waste liquid after cleaning is sent to a waste liquid outlet 508.

[0019] It is also possible to integrate the FB tank 50 and the UFB tank 60 to simplify the configuration of the UFB generator 1. In this case, it becomes impossible to perform filtering by dead-end filtration, and it becomes necessary to manage the time and state of the disappearance of MB 502 by time management, but it is possible to generate UFB water 601.

[0020] The UFB water 601 accumulated in the UFB tank 60 is sent to the crossflow filter section 605 via a pump 603 and a pipe 604. By employing a crossflow filtration method, the UFB concentration can be efficiently concentrated. In crossflow filtration, the supplied liquid passes through a filter membrane with positive pressure relative to the permeate side. If the pore size of the membrane is set smaller than that of the UFB 602, only water passes through the membrane and is sent to a pump 606 and a waste liquid port 607. As a result, the UFB 602 concentration in the UFB water 601 that has passed through the crossflow filter section 605 is higher than the UFB 602 concentration in the UFB water 601 in the UFB tank 60, and the UFB water 601 is returned to the liquid supply tank 30 via a pipe 608.

[0021] The control unit 70 is configured with an information processing device such as a PC (Personal Computer) or a PLC (Programmable Logic Controller), and controls the overall operation of the UFB generator 1. For example, the control unit 70 acquires detection values ​​from each sensor and controls the operation of the FB generator 10, the gas supply unit 20, and each pump according to these detection values ​​and set conditions. With the above-described configuration, a highly concentrated UFB-containing liquid can be efficiently generated by circulating the liquid through the liquid supply tank 30, the FB generator 10, the FB tank 50, the UFB tank 60, and the liquid supply tank 30.

[0022] In the above-described device configuration, the types of gases and liquids are not limited and can be freely selected within a range suitable for the purpose. Furthermore, the parts in contact with the gas (pipes 203, 303, 402, 407, 504, pumps 304, 403, 406, filter 202, liquid supply tank 30, and liquid-contacting parts of the FB generator 10) are preferably made of highly corrosion-resistant materials, such as fluorine-based resins such as polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA), metals such as SUS316L, and other inorganic materials. This allows for the efficient generation of FB even from highly corrosive gases and liquids. Furthermore, it is desirable to use pumps 304, 403, and 406 with minimal pulsation and flow rate variation to avoid impairing FB generation efficiency. This allows for the efficient production of FB-containing liquid with minimal FB concentration variation.

[0023] [UFB-containing liquid manufacturing process] Next, a process for manufacturing a UFB-containing liquid using the UFB generator 1 (UFB-containing liquid manufacturing process) will be described. FIG. 2 is a flowchart schematically illustrating the flow of the UFB-containing liquid manufacturing process. In the UFB-containing liquid manufacturing process, in step S1, a liquid for an FB generation process is supplied to the FB generator 10. The liquid for the FB generation process is liquid 301 supplied from a liquid supply tank 30, and in the initial operation of the UFB generator 1, the liquid is ultrapure water 401 from which dissolved gases have been degassed. After the UFB generator 1 starts operating, the UFB concentration in the liquid 301 increases as the process progresses.

[0024] In step S1, the use of ultrapure water 401 from which dissolved gases have been degassed makes it possible to dissolve the desired gas in the liquid to the maximum extent possible within the FB generator 10. Furthermore, the liquid 301 supplied from the liquid supply tank 30 is controlled to a low temperature (for example, 10°C or lower), making it easy for the gas to dissolve in. Therefore, in the FB generator 10, the gas can be efficiently dissolved and the FB generation efficiency can be improved.

[0025] Next, in step S2, the liquid for FB generation processing is subjected to FB generation processing in the FB generator 10. The liquid for FB generation processing 301 and gas from the gas supply unit 20 are supplied to the FB generator 10, and FB is generated by, for example, spraying gas from an FB generation nozzle into the liquid for FB generation processing 301.

[0026] Next, in step S3, an MB removal process is performed to remove MB 502 from the FB water 501 generated by the FB generator 10. Specifically, because the FB water 501 generated by the FB generator 10 contains a mixture of MB 502 and UFB 503, the FB water 501 is allowed to stand in the FB tank 50 for approximately 30 minutes. This causes the MB 502 in the FB water to disappear, resulting in FB water 501 with improved UFB 503 purity. Furthermore, when the FB water 501 is sent from the FB tank 50 to the UFB tank 60, the MB 502 is removed by the dead-end filter 507. As a result, UFB water 601 from which MB 502 has been removed is accumulated in the UFB tank 60.

[0027] Next, in step S4, a UFB concentration process is performed on the UFB water 601 accumulated in the UFB tank 60 to increase the concentration of UFB 602. Specifically, the UFB water 601 delivered from the UFB tank 60 is subjected to a process in which (a portion of) the water is removed in the cross-flow filter unit 605 to increase the UFB 602 concentration. The UFB water 601 with an increased UFB 602 concentration in step S4 is delivered to the liquid supply tank 30 as a liquid for the FB generation process. This process is repeated until UFB water 601 with the desired UFB 602 concentration is obtained.

[0028] As described above, the UFB generator 1 according to this embodiment can increase the UFB concentration without undergoing a process that causes a large loss of UFB, such as heating, and can mass-produce UFB water with a high UFB concentration. Therefore, it is possible to more efficiently produce a highly concentrated microbubble-containing liquid.

[0029] Furthermore, the UFB generator 1 according to this embodiment includes a means for selecting bubble size (dead-end filter 507), and a 0.2 μm filter can be used as the selection means. Generally, liquids that pass through a 0.2 μm filter can be used as sterilized liquids. However, whether or not liquids that pass through a 0.2 μm filter can be used as sterilized liquids also depends on the environment of the device. Since the process performed by the UFB generator 1 according to the present invention does not include a process that contaminates liquids that pass through a 0.2 μm filter, sterilized high-concentration UFB water can be produced in large quantities. Therefore, the high-concentration UFB water produced by the present invention can be used in applications requiring purity, such as medical applications.

[0030] Furthermore, due to the measurement limitations of measuring instruments, it is currently not possible to accurately measure the concentration of UFB water of 100 nm or less. However, by using a high-speed atomic force microscope (high-speed AFM: MS-NEX manufactured by Biomolecular Measurement Laboratory), it has been observed that UFB of 60 nm or less also exists.

[0031] Furthermore, in fields such as cell culture, it is known that the gaps between three-dimensional cell aggregates (such as spheroids and organoids) are extremely narrow (100 nm or less), and research is being conducted based on the idea that fine UFBs can have specific effects, so the high-concentration UFB water produced by the present invention is highly useful in such fields as well.

[0032] [Verification of Effects] Next, the effects of the present invention will be verified. Here, UFB water produced by the present invention will be compared with UFB water produced by Patent Document 1. Figure 3 is a schematic diagram showing the correlation between gas solubility and device operation time. Note that Figure 3 compares the correlation between gas (oxygen) solubility and device operation time in UFB water produced by the present invention and UFB water produced by the technology described in Patent Document 1.

[0033] As shown in Figure 3, in the method of Patent Document 1, the gas solubility was supersaturated when UFB water was prepared, but the reduced pressure evaporation method using the concentration-enhancing means simultaneously evaporates the gas dissolved in the liquid, and the longer the operating time, the amount of gas dissolved in the liquid falls below the saturated concentration (the dashed line in Figure 3), ultimately resulting in a significantly low gas solubility. As a result, the gas contained in the UFB dispersed in the liquid moves into the liquid (due to the disruption of the equilibrium state within the liquid), shortening the life of the UFB concentration (the time during which the UFB concentration is maintained), and in some applications, the function may no longer be fulfilled.

[0034] On the other hand, in the present invention, even if the device is operated for a long time, the dissolved concentration of gas (oxygen) can be maintained at almost the initial state. Therefore, the equilibrium state in the liquid is not disturbed, and the gas in the UFB does not move into the liquid, so the UFB concentration is stable over the long term. In other words, the UFB concentration can be maintained for a long period of time in the UFB water produced by the present invention.

[0035] Fig. 4 is a schematic diagram showing the correlation between UFB concentration and device operation time, comparing the correlation between UFB concentration and device operation time in UFB water produced by the present invention and UFB water produced by the technology described in Patent Document 1.

[0036] As shown in Figure 4, in the method of Patent Document 1, MB and UFB are mixed, so as the operating time increases, the effects of MB occur. That is, MB clogs the filter, and the short defoaming action (MB disappears in a short time) inhibits the high concentration of UFB, resulting in a decrease in the proportional relationship between time and UFB concentration.

[0037] On the other hand, in the present invention, because a means for selecting bubble size (dead-end filter 507) is provided, MB does not have an effect even if the device is operated for a long time. Therefore, the UFB concentration increases in proportion to the device operation time. As a result, high-concentration UFB water can be stably produced.

[0038] Fig. 5 is a schematic diagram showing the correlation between the amount of UFB water produced and the operation time of the apparatus, comparing the amount of UFB water produced by the present invention with the amount of UFB water produced by the technology described in Patent Document 1 and the operation time of the apparatus.

[0039] As shown in Figure 5, in the method of Patent Document 1, most of the liquid UFB water evaporates due to the reduced pressure evaporation method, and furthermore, because the UFB water is not replenished, the amount of UFB water obtained decreases as the operation time of the device increases. Therefore, in order to obtain a large amount of UFB water, it is necessary to prepare UFB water in an amount 100 to 1,000 times or more the desired amount of UFB water before operating the device to increase the concentration, making it difficult to mass-produce UFB water.

[0040] On the other hand, in the present invention, since the liquid is removed from the UFB water and circulated without the liquid evaporation process, the amount of UFB produced increases proportionally with the operating time of the device. In other words, the present invention is a method suitable for mass production of high-concentration UFB water.

[0041] Second Embodiment Next, a second embodiment of the present invention will be described. Fig. 6 is a schematic diagram showing the configuration of a UFB generator 1 according to the second embodiment. The UFB generator 1 according to this embodiment differs from the UFB generator 1 according to the first embodiment in the configuration for concentrating UFB water. Therefore, for the configuration shown in Fig. 6 that is similar to the UFB generator 1 of the first embodiment shown in Fig. 1, the description of the first embodiment should be referred to, and the following description will mainly focus on the differences.

[0042] 6, in the UFB generation apparatus 1 according to this embodiment, UFB water 611 is sent from a UFB tank 60A to a cross-flow filter unit 615 via a pump 613 and a pipe 614. In the cross-flow filter unit 615, only water passes through the membrane, and the passed water is discharged from a waste liquid port 617 via a pump 616. Meanwhile, in this embodiment, unlike the first embodiment, the UFB water 611 filtered by the cross-flow filter unit 615 is returned to the UFB tank 60A via a pipe 619 rather than to the liquid supply tank 30.

[0043] That is, in this embodiment, only the UFB 612 is concentrated and stored in the UFB tank 60A without going through the FB generator 10. A cooling unit 618 is disposed around the entire or part of the outer periphery of the UFB tank 60A, and is configured to be able to cool the UFB water 611. As described above, the lower the temperature of the liquid, the higher the solubility of gases can be, so a lower liquid temperature is preferable, and in this embodiment, the liquid temperature is controlled to be approximately 10°C or less using a temperature sensor (not shown).

[0044] The configuration of the cooling unit 618 is not particularly limited as long as it can control the UFB water 611 to the desired temperature. For example, a cooling device such as a Peltier element, or a system that circulates a cooling liquid cooled to a low temperature by a chiller (not shown), can be used. In this case, a cooling pipe through which the cooling liquid can circulate can be installed so as to surround the outer periphery of the UFB tank 60A, or a container that accumulates the liquid in the UFB tank 60A can be made hollow so that the cooling liquid passes through the hollow portion. Alternatively, the cooling pipe can be arranged in a storage space where the UFB water 611 is stored, and the cooling pipe can pass through the UFB water 611 stored in the UFB tank 60A.

[0045] With the above-described configuration, UFB water 611 processed in the liquid supply tank 30, FB generator 10, FB tank 50, and UFB tank 60A in that order is circulated in UFB tank 60A (circulation treatment in cross-flow filter section 615), thereby efficiently producing a highly concentrated UFB-containing liquid.

[0046] [Third Embodiment] Next, a third embodiment of the present invention will be described. Fig. 7 is a schematic diagram showing the configuration of a UFB generator 1 according to the third embodiment. The UFB generator 1 according to this embodiment differs from the UFB generator 1 according to the first embodiment in the configuration for concentrating UFB water. Therefore, for the configuration shown in Fig. 7 that is similar to the UFB generator 1 of the first embodiment shown in Fig. 1, the description of the first embodiment shall be referred to, and the following description will mainly focus on the differences.

[0047] 7, in the UFB generation apparatus 1 according to this embodiment, UFB water 621 is sent from the UFB tank 60B to the cross-flow filter unit 625 via a pump 623 and a pipe 624. In the cross-flow filter unit 625, only water passes through the membrane, and the passed water is discharged from a waste liquid port 627 via a pump 626. Meanwhile, unlike the first embodiment, in this embodiment, the UFB water 621 filtered by the cross-flow filter unit 625 is returned to the UFB tank 60B via a pipe 629 rather than to the liquid supply tank 30.

[0048] That is, in this embodiment, only the UFB 622 is concentrated and stored in the UFB tank 60B without passing through the FB generator 10. A temperature control unit 628 is disposed around the entire or part of the outer periphery of the UFB tank 60B, allowing for temperature control of the UFB water 621. A liquid level sensor (not shown) is disposed in the UFB tank 60B, and when the liquid level reaches a predetermined height, the UFB water 621 is heated to 20 to 30°C. The UFB tank 60B is then depressurized via a pump 630, and the evaporated liquid (excluding the UFB 622) is discharged to an outlet 631. At this time, a rotor or the like may be disposed in the UFB tank 60B to move the liquid level, thereby efficiently promoting evaporation of the liquid.

[0049] With the above-described configuration, UFB water 621 processed in the liquid supply tank 30, FB generator 10, FB tank 50, and UFB tank 60B in that order is circulated in UFB tank 60B (circulation treatment in cross-flow filter section 625), and by reducing the pressure in UFB tank 60B, only liquid is discharged from UFB tank 60B, thereby efficiently producing a highly concentrated UFB-containing liquid.

[0050] [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. FIG. 8 is a schematic diagram showing the configuration of a UFB generator 1 according to the fourth embodiment. The UFB generator 1 according to this embodiment differs from the UFB generator 1 according to the first embodiment in the configuration for concentrating UFB water. Like the UFB generator 1 according to the second embodiment, the UFB generator 1 according to this embodiment highly concentrates the UFB-containing liquid by circulating it in a cross-flow filter unit 645. However, the UFB generator 1 according to this embodiment differs in that the UFB 642 passes through the filter membrane along with a small amount of liquid in the cross-flow filter unit 645. Therefore, for the configuration shown in FIG. 8 that is similar to the UFB generator 1 according to the first embodiment shown in FIG. 1 and the UFB generator 1 according to the second embodiment shown in FIG. 6, the descriptions of the first and second embodiments should be referred to. Here, the differences will be mainly described.

[0051] As shown in Figure 8, in the UFB generator 1 of this embodiment, UFB water 641 is sent from the UFB tank 60C to the cross-flow filter unit 645 via a pump 643 and a pipe 644. In this embodiment, unlike the first embodiment, the cross-flow filter unit 645 is configured such that the filter diameter is adjusted so that concentrated UFB water 641 containing UFB 642 passes through the filter membrane. The concentrated UFB water 641 is then returned to the UFB tank 60C via a pump 649 and a pipe 650, rather than to the liquid supply tank 30. Most of the water separated from the UFB water 641 in the cross-flow filter unit 645 is discharged from an outlet 647 via a pump 646.

[0052] With the above-described configuration, UFB water 641 that has been processed in the liquid supply tank 30, FB generator 10, FB tank 50, and UFB tank 60C in that order is circulated in UFB tank 60C (circulation treatment in cross-flow filter section 645), thereby efficiently producing a highly concentrated UFB-containing liquid.

[0053] [Variation 1] In the first embodiment, a method for producing a large amount of sterilized high-concentration UFB water was described. Specifically, a method for sterilizing high-concentration UFB water was described in which UFB water is filtered using a 0.2 μm filter. In addition to this sterilization method, the following methods can be used to produce sterilized high-concentration UFB water. 1. Sterilization Method Using UV Irradiation: High-concentration UFB water can be sterilized by irradiating it for 10 minutes or more with a low-pressure mercury lamp that efficiently emits UV light with a wavelength of around 260 nm (e.g., 253.7 nm), which has a strong bactericidal effect. 2. Pulsed Light Sterilization Method: High-concentration UFB water can be sterilized using a pulsed light sterilization treatment device (e.g., PLS2K02-04, manufactured by Iwasaki Electric Co., Ltd.). In pulsed light sterilization equipment, compressed energy is released into a xenon lamp over a calculated time period of 200 to 300 μs, increasing the radiation intensity per unit time by more than 1,000 times that of low-pressure ultraviolet lamps. This performance can be utilized to achieve in-line sterilization of microorganisms. 3. Ultrashort wavelength (222 nm) ultraviolet sterilization method: By combining an excimer lamp with a peak wavelength of 222 nm with a special optical filter, ultraviolet light is emitted that blocks wavelengths above 230 nm, which are harmful to humans, allowing for sterilization of high-concentration UFB water. 4. Autoclave sterilization method: High-concentration UFB water can be sterilized by using saturated steam to create a high temperature and pressure inside (the high-concentration UFB water environment). Items to be sterilized are sterilized by exposing them to steam at 115 to 135°C in an environment exceeding 1 atmosphere.

[0054] [Variation 2] Each of the sterilization methods shown in the first embodiment and Variation 1 can be used alone to sterilize the high-concentration UFB water of the present invention, but multiple sterilization methods can also be used in combination depending on the application. For example, a container containing high-concentration UFB water can be sterilized by autoclave sterilization, and the high-concentration UFB water can be sterilized only by filtration using a 0.2 μm filter, and the container sterilized by autoclave sterilization can be filled with high-concentration UFB water sterilized using a 0.2 μm filter. As another example, the high-concentration UFB water filled in the container can be sterilized together with the container using pulsed light sterilization.

[0055] The present invention can be modified, improved, etc. as appropriate within the scope of the effects of the present invention, and is not limited to the above-described embodiment. For example, in the above-described embodiment, the specific numerical values ​​shown in the description of each step are merely examples, and values ​​within an appropriate range are selected depending on the specific configuration of the UFB generator 1 and the gas and liquid used to generate UFB. The values ​​selected at this time can be experimental values, simulation results, etc.

[0056] Furthermore, the present invention can be implemented by appropriately combining the above-described embodiments. The control processes in the above-described embodiments can be executed by either hardware or software. In other words, it is sufficient that the UFB generator 1 has a function capable of executing the above-described processes, and the functional and hardware configurations for realizing these functions are not limited to the above-described examples.

[0057] The above embodiment shows an example of application of the present invention and does not limit the technical scope of the present invention. In other words, the present invention can be modified in various ways, such as by omission or substitution, without departing from the gist of the present invention, and various embodiments other than the above embodiment can be adopted. The various embodiments and modifications that the present invention can adopt are included in the scope of the invention described in the claims and their equivalents.

[0058] The UFB generator 1 configured as described above includes the FB generator 10, the FB tank 50, the dead-end filter 507, and the cross-flow filter unit 605. The FB generator 10 generates fine bubbles using supplied liquid and gas. The FB tank 50 and the dead-end filter 507 remove fine bubbles having a diameter equal to or larger than a predetermined value from a microbubble-containing liquid containing fine bubbles. The cross-flow filter unit 605 increases the microbubble concentration of the microbubble-containing liquid from which microbubbles having a diameter equal to or larger than a predetermined value have been removed. This increases the microbubble concentration without undergoing a process that results in a significant loss of microbubbles (UFB), and enables the mass production of UFB water with a high microbubble concentration. This makes it possible to more efficiently produce a highly concentrated microbubble-containing liquid.

[0059] The cross-flow filter unit 605 separates a part of the liquid in the microbubble-containing liquid from the microbubbles using a filter, thereby increasing the microbubble concentration of the microbubble-containing liquid, thereby making it possible to increase the microbubble concentration of the microbubble-containing liquid without causing a large loss of microbubbles (UFB).

[0060] The cross-flow filter unit 605 circulates the microbubble-containing liquid and processes it through the filter, thereby making it possible to repeat the process of increasing the concentration of microbubbles (UFB) as necessary, and easily increasing the concentration of microbubbles.

[0061] The cross-flow filter unit 605 circulates the microbubble-containing liquid and processes it through the filter, and also removes the liquid from the microbubble-containing liquid in a reduced pressure environment, thereby enabling efficient production of a highly concentrated microbubble (UFB)-containing liquid.

[0062] The cross-flow filter unit 605 circulates the microbubble-containing liquid, filters it, and sterilizes it, making it possible to easily produce a microbubble-containing liquid that can be used in applications requiring cleanliness, such as medical applications.

[0063] The fine bubbles generated by the FB generator 10 include microbubbles with diameters greater than 1.0 μm and ultrafine bubbles with diameters of 1.0 μm or less. The FB tank 50 and the dead-end filter 507 remove the microbubbles, allowing the microbubbles and ultrafine bubbles to be easily separated.

[0064] 1 UFB generator, 10 FB generator, 20 gas supply unit, 30 liquid supply tank, 40 ultrapure water supply tank, 50 FB tank, 60, 60A, 60B, 60C UFB tank, 70 control unit, 507 dead-end filter, 605, 615, 625, 645 cross-flow filter unit

Claims

1. An apparatus for producing a fine-bubble-containing liquid, comprising: a fine-bubble generating means for generating fine bubbles using supplied liquid and gas; a bubble removing means for removing fine bubbles having a diameter of a predetermined value or more from the fine-bubble-containing liquid containing the fine bubbles; and a concentration increasing means for increasing the fine bubble concentration in the fine-bubble-containing liquid from which the fine bubbles having a diameter of the predetermined value or more have been removed.

2. The apparatus for producing micro-bubble-containing liquid as described in claim 1, characterized in that the concentration increasing means increases the micro-bubble concentration of the micro-bubble-containing liquid by separating a portion of the liquid in the micro-bubble-containing liquid from the micro-bubbles using a filter.

3. The apparatus for producing liquid containing fine bubbles according to claim 2, characterized in that the concentration increasing means circulates the liquid containing fine bubbles and treats it through the filter.

4. The apparatus for producing a micro-bubble-containing liquid as described in claim 2 or 3, characterized in that the concentration increasing means circulates the micro-bubble-containing liquid and treats it with the filter, while removing the liquid from the micro-bubble-containing liquid by a reduced pressure environment.

5. The apparatus for producing fine-bubble-containing liquid according to claim 2 or 3, characterized in that the concentration increasing means circulates the fine-bubble-containing liquid and treats it through the filter, and also sterilizes the fine-bubble-containing liquid.

6. The apparatus for producing fine bubble-containing liquid as described in claim 1 or 2, characterized in that the fine bubbles generated by the fine bubble generating means include microbubbles having a diameter larger than 1.0 μm and ultrafine bubbles having a diameter of 1.0 μm or less, and the bubble removing means removes the microbubbles.

7. A method for producing a fine bubble-containing liquid, comprising: a fine bubble generating step of generating fine bubbles using supplied liquid and gas; a bubble removing step of removing fine bubbles having a diameter of a predetermined value or more from the fine bubble-containing liquid containing the fine bubbles; and a concentration increasing step of increasing the fine bubble concentration in the fine bubble-containing liquid from which the fine bubbles having a diameter of the predetermined value or more have been removed.

8. A fine-bubble-containing liquid produced by a fine-bubble-containing liquid producing apparatus comprising: a fine-bubble generating means for generating fine bubbles from supplied liquid and gas; a bubble removing means for removing fine bubbles having a diameter of a predetermined value or more from the fine-bubble-containing liquid containing the fine bubbles; and a concentration increasing means for increasing the fine bubble concentration in the fine-bubble-containing liquid from which the fine bubbles having a diameter of the predetermined value or more have been removed.

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