Ultra-fine bubble suspension manufacturing method and manufacturing device

Abstract

A manufacturing method for an ultrafine bubble suspension according to one embodiment includes: (A) a step for supplying, into a mixing container, a first fluid and a second fluid that condenses more easily than the first fluid; (B) a step for mixing the first fluid and the second fluid in a vapor phase inside the mixing container; and (C) a step for selectively condensing the second fluid after the step (B).

Description

[Technical field]

[0001] The present invention relates to a technology for producing an ultra-fine bubble suspension. [Background technology]

[0002] There is a technique for producing water containing fine bubbles with particle sizes at the micro- or nano-level by swirling a gas-liquid mixture fluid and shearing the gas-liquid mixture fluid (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-272739 A Summary of the Invention [Problem to be solved by the invention]

[0004] An ultra-fine bubble suspension is a suspension in which a large number of tiny bubbles exist in a liquid, each with a diameter of 1 μm or less. Generally, it is known as ultra-fine bubble water, which is water containing a large number of tiny air bubbles, and because it has characteristics different from those of water or carbonated water, its use in various industrial fields is being considered.

[0005] One method for producing ultra-fine bubble water is to use physical swirling or shearing forces to pulverize a gas-containing liquid to produce water containing minute bubbles, as described in the above-mentioned Patent Document 1. However, this method produces many bubbles with larger diameters in addition to ultra-fine bubbles with diameters of 1 μm or less, making it difficult to control. For this reason, it is difficult to produce an ultra-fine bubble suspension in which the number density of ultra-fine bubbles is controlled to a preset value.

[0006] An object of the present invention is to provide a technology for producing ultra-fine bubbles that can be easily controlled. [Means for solving the problem]

[0007] A method for producing an ultra-fine bubble suspension according to one embodiment of the present invention comprises the steps of: (A) supplying a first fluid and a second fluid that is more easily condensed than the first fluid into a mixing vessel; (B) mixing the first fluid and the second fluid in the gas phase in the mixing vessel; (C) after step (B), selectively condensing the second fluid; Includes.

[0008] Another embodiment of the method for producing an ultra-fine bubble suspension comprises the steps of: (A) supplying a first fluid and a second fluid that is more easily condensed than the first fluid into a mixing vessel; (B) removing from the mixing vessel an ultra-fine bubble suspension in which the second fluid has been selectively condensed; In the step (A), the first fluid is supplied through a first valve, the second fluid is supplied through a second valve, the first fluid and the second fluid are mixed in the gas phase in the mixing vessel, and the second fluid is selectively condensed. The ultra-fine bubble suspension extracted in the step (B) contains the second fluid in the liquid phase and ultra-fine bubbles of the first fluid in the gas phase present in the second fluid.

[0009] Another embodiment of an apparatus for producing an ultra-fine bubble suspension includes a mixing vessel capable of mixing a first fluid and a second fluid in the gas phase, a first flow path for introducing the first fluid in a gaseous state into the mixing vessel, a second flow path for introducing the second fluid in a gaseous state into the mixing vessel, an exhaust path for discharging a portion of the gas in the mixing vessel to the outside, and a condensation mechanism for selectively condensing the second fluid, which is easier to condense than the first fluid. Effect of the Invention

[0010] According to a representative embodiment of the present invention, the production of ultra-fine bubbles can be easily controlled. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic diagram of the behavior of non-ultra-fine bubbles and ultra-fine bubbles present in water. [Diagram 2] FIG. 1 is an explanatory diagram showing a schematic diagram of the relationship between the degree of dispersion of gas molecules mixed in liquid molecules and bubble growth, showing a case where the concentration distribution of the gas molecules is uniform. [Diagram 3] FIG. 1 is an explanatory diagram that illustrates the relationship between the degree of dispersion of gas molecules mixed in liquid molecules and bubble growth, showing a case where the concentration distribution of gas molecules is unevenly distributed. [Figure 4] FIG. 1 is an explanatory diagram showing an example of an apparatus for producing an ultra-fine bubble suspension. [Diagram 5] FIG. 5 is an explanatory diagram that illustrates a state in which one of the two types of fluids introduced into the mixing vessel shown in FIG. 4 is selectively liquefied. [Figure 6] FIG. 5 is a flow diagram showing an example of a process for producing an ultra-fine bubble suspension using the production apparatus shown in FIG. [Figure 7] FIG. 13 is an explanatory diagram showing a state in which a new fluid is supplied to a mixing container while an ultra-fine bubble suspension remains. [Figure 8] FIG. 7 is an explanatory diagram showing the state inside the mixing vessel after the second condensation step shown in FIG. 6 is completed. [Figure 9] FIG. 1 is a time chart showing the supply state of a condensable fluid and a non-condensable fluid, and the temperature profile in a mixing vessel during the production process of an ultra-fine bubble suspension. [Figure 10] FIG. 10 is a time chart showing a modified example of FIG. 9. [Figure 11] FIG. 11 is an explanatory diagram showing an example of a manufacturing apparatus for manufacturing an ultra-fine bubble suspension according to the time chart shown in FIG. [Figure 12] 10 is a time chart of a method for producing an ultra-fine bubble suspension, which is another modified example of the method shown in FIG. 9 . [Figure 13] FIG. 13 is an explanatory diagram showing a state of a temperature increasing process in the production apparatus for carrying out the process for producing the ultra-fine bubble suspension shown in FIG. 12. [Figure 14] FIG. 13 is an explanatory diagram showing a state of a pressurizing process in the production apparatus for carrying out the production process of the ultra-fine bubble suspension shown in FIG. [Figure 15] FIG. 13 is an explanatory diagram showing a state of a depressurization process in the production apparatus for carrying out the process for producing the ultra-fine bubble suspension shown in FIG. 12. [Figure 16] FIG. 13 is an explanatory diagram showing a state of a second heating step in the production apparatus for carrying out the process for producing the ultra-fine bubble suspension shown in FIG. 12. [Figure 17] 10 is a time chart of a method for producing an ultra-fine bubble suspension, which is another modified example of the method shown in FIG. 9 . [Figure 18] FIG. 18 is an explanatory diagram showing a production apparatus used in the method for producing the ultra-fine bubble suspension shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In the following description, the terms "condensable fluid" and "non-condensable fluid" may be used. Based on the pressure and temperature at which the ultra-fine bubble suspension is taken out, a fluid that is a gas is defined as a "non-condensable fluid", and a fluid that is a liquid at the above pressure and temperature is defined as a "condensable fluid".

[0013] <About Ultrafine Bubbles> Figure 1 is an explanatory diagram showing a model of the behavior of non-ultra-fine bubbles and ultra-fine bubbles present in water. In the example shown in Figure 1, the liquid 10 is water. The ultra-fine bubbles 20A and the non-ultra-fine bubbles 20B are air bubbles. Various substances can be used for the liquid and air bubbles in the ultra-fine bubble suspension produced by the technology described below, but the following embodiment will be described by way of example with the liquid 10 being water and the ultra-fine bubbles 20A being air.

[0014] In the example shown in FIG. 1, a plurality of bubbles 20, including ultra-fine bubbles 20A and non-ultra-fine bubbles 20B, are present in the liquid 10. The ultra-fine bubbles 20A and non-ultra-fine bubbles 20B can be distinguished from each other by the diameter of the bubbles 20. The ultra-fine bubbles 20A have a bubble diameter D1 of less than 1 μm. The non-ultra-fine bubbles 20B have a bubble diameter D2 of 1 μm or more. Since the ultra-fine bubbles 20A have a small bubble diameter, they have a shape that can be regarded as almost a sphere. On the other hand, the non-ultra-fine bubbles 20B may have various shapes, such as an ellipsoidal sphere, as shown in FIG. 1. For convenience, the minor axis of the ellipsoidal sphere is shown as the bubble diameter D3 in FIG. 1, but the bubble diameter D2 of the non-ultra-fine bubbles 20B is defined as the diameter of the non-ultra-fine bubbles 20B when converted into a sphere. The bubble diameter D1 of the ultra-fine bubbles 20A is defined as the diameter of each bubble 20 converted into a sphere, similar to the above-mentioned bubble diameter D3.

[0015] As shown diagrammatically by arrows in FIG. 1, non-ultra-fine bubbles 20B rise toward the liquid surface 10t due to buoyancy generated in the liquid 10, and burst at the liquid surface 10t.

[0016] The ultra-fine bubbles 20A have a small bubble diameter D1 of 1 μm or less, and therefore can stably maintain their own shape in the liquid 10. Furthermore, because the ultra-fine bubbles 20A have a small bubble diameter D1, the floating speed of the ultra-fine bubbles 20A calculated by Stokes' equation is slower than the random movement speed of the ultra-fine bubbles 20A in all directions due to Brownian motion. As a result, the ultra-fine bubbles 20A do not float toward the liquid surface 10t, and can remain suspended in the liquid 10 for a long period of time.

[0017] Among the non-ultra-fine bubbles 20B, those with a relatively small bubble diameter D2 (for example, 100 μm or less) are called microbubbles, and may be collectively called fine bubbles, including the ultra-fine bubbles 20A. They can be visually identified as follows. That is, water containing microbubbles is cloudy. On the other hand, water containing only ultra-fine bubbles 20A is colorless and transparent. This is because the bubble diameter D1 of the ultra-fine bubbles 20A is small, and therefore most of the ultra-fine bubbles 20A do not scatter visible light.

[0018] <Method of mixing fluids> Next, a method of mixing fluids will be described. Figures 2 and 3 are explanatory diagrams that show the relationship between the degree of dispersion of gas molecules mixed in liquid molecules and the growth of bubbles. Figure 2 shows a state in which gas molecules are uniformly dispersed (in other words, a state in which the dissolved gas concentration distribution is uniform), and Figure 3 shows a state in which gas molecules are unevenly distributed in a certain area (in other words, a state in which the dissolved gas concentration distribution is unevenly distributed). In Figures 2 and 3, in order to improve the discrimination between liquid molecules 11 and gas molecules 21, water molecules 21 are shown in white, and gas molecules 21 and ultra-fine bubbles 20A and non-ultra-fine bubbles 20B formed by the gas molecules 21 growing into bubbles are given patterns that are darker than those of water molecules 21. The upper figures in Figures 2 and 3 show a state in which gas molecules 21 are dissolved in a liquid made of liquid molecules 11 (referred to as an initial state). The lower figures in Figures 2 and 3 show a state after the gas molecules have grown into bubbles. In the following description, liquid molecules 11 refer to molecules of a substance that is liquid in a standard state, such as water, and gas molecules 21 refer to molecules that are gaseous in a standard state, such as oxygen and nitrogen.

[0019] In order to produce an ultra-fine bubble suspension, it is necessary to mix at least two kinds of fluids, such as water and air, and disperse the molecules of one fluid in the other fluid. As shown in FIG. 2, when the gas molecules 21 are uniformly dispersed in the initial state (upper diagram in FIG. 2), bubble nuclei (see bubble nuclei 24 shown in FIG. 5 described later) are formed at many places in the liquid. The bubble nuclei are formed by integrating a plurality of fine bubbles formed by vaporization of the gas molecules 21, and are fine bubbles that become the nuclei of bubble growth. When the bubble nuclei are formed, they integrate with the surrounding gas molecules 21, and the bubble diameter grows. However, when the gas molecules 21 are uniformly dispersed, bubble nuclei generation occurs more predominantly than bubble growth. For this reason, some of the many bubble nuclei grow to a size where the bubble diameter D1 (see FIG. 1) exceeds 1 μm, but the proportion of such cases is small. When the bubble nuclei generation and bubble growth progress, the vaporized gas molecules 21 become insufficient. At this time, bubbles that have grown to a diameter D2 or larger of the non-ultra-fine bubbles 20B shown in Figure 1 rise to the surface of the liquid or disappear in the liquid, resulting in a large number of ultra-fine bubbles 20A in the liquid.

[0020] On the other hand, as shown in FIG. 3, in the initial state (upper diagram in FIG. 3), when the gas molecules 21 are unevenly distributed, a bubble nucleus (not shown) is formed in a place where the density of the gas molecules 21 is high. When a bubble nucleus is formed, the bubble nucleus is likely to be integrated with the surrounding gas molecules 21, so that bubble growth occurs more predominantly than bubble nucleation. As a result, as shown in FIG. 3, the gas molecules 21 vaporized in the liquid are likely to grow into bubbles with a large bubble diameter (for example, the size of the non-ultra-fine bubbles 20B shown in FIG. 1). Since the large bubbles rise to the liquid surface and disappear as described above, or disappear in the liquid, as a result, the ultra-fine bubbles 20A (see FIG. 2) are unlikely to remain in the liquid. Furthermore, in a place where the density of the gas molecules 21 is low, the gas molecules 21 are not supersaturated with respect to the equilibrium concentration with respect to the liquid molecules 11, and therefore are unlikely to vaporize. For this reason, in a place where the density of the gas molecules 21 is low, the gas molecules 21 remain in the liquid while remaining dissolved in the liquid. Therefore, in the example shown in FIG. 3, it is difficult to efficiently generate the ultra-fine bubbles 20A (see FIG. 2).

[0021] 2 and 3, it is clear that in order to stably form ultra-fine bubbles 20A, it is important to control the distribution of gas molecules 21 dispersed in liquid molecules 11 as uniformly as possible. However, in the case of a gas-liquid mixing method in which a gaseous fluid and a liquid fluid are mixed as a method for mixing two types of fluids, or a liquid-liquid mixing method in which two types of fluids are mixed in a liquid state, it is difficult to stably control the state in which gas molecules 21 are uniformly dispersed, as shown in FIG.

[0022] Therefore, the inventors of the present application have focused on the point of homogenizing the dispersion state of the gas molecules 21 and have found a method of mixing two or more types of fluids in the gas phase, in other words, a method of mixing two or more types of fluids in a gaseous state. In a gaseous state, the kinetic energy of the thermal motion of the molecules constituting the fluid is greater than in a liquid state. For this reason, in the case of a method of mixing in the gas phase, it is easier to homogenize the gas molecules 21 compared to the above-mentioned gas-liquid mixing method and liquid-liquid mixing method. Then, if the liquid molecules 11 are rapidly liquefied in a state in which the gas molecules 21 are homogenously dispersed, a large number of ultra-fine bubbles 20A are trapped in the liquid, and an ultra-fiber suspension is obtained.

[0023] That is, the method for producing an ultra-fine bubble suspension described below includes the steps of (A) supplying each of a first fluid and a second fluid into a mixing vessel, (B) mixing the first fluid and the second fluid in the gas phase in the mixing vessel, and (C) selectively condensing the second fluid, which is easier to condense than the first fluid, after step (B). This allows the ultra-fine bubble suspension to be produced in a controlled state. There are several methods for mixing two or more types of fluids in the gas phase and for selectively agglomerating and liquefying some of the two or more types of fluids. Below, several representative methods examined by the present inventors will be described in order.

[0024] <Cooling method> First, an embodiment in which a cooling method is adopted as a method for selectively condensing a condensable fluid will be described. Fig. 4 is an explanatory diagram showing an example of an apparatus for producing an ultra-fine bubble suspension. Fig. 5 is an explanatory diagram showing a state in which one of two types of fluids introduced into the mixing vessel shown in Fig. 4 is selectively liquefied. Fig. 6 is a flow diagram showing an example of a process for producing an ultra-fine bubble suspension using the apparatus shown in Fig. 4.

[0025] The manufacturing apparatus 100 shown in FIG. 4 has a mixing vessel 30 that contains the fluid 22 and the fluid 12. The fluid 22 is a non-condensable fluid such as air. The fluid 12 is a condensable fluid such as water. The method of gasifying (evaporating) the condensable fluid is not particularly limited. For example, a boiler used in a factory or the like can be used as a source of water vapor. Alternatively, when the manufacturing apparatus 100 is equipped with a heating device (not shown) that heats and evaporates the fluid 12 in a liquid state, various fluids can be used regardless of the type of the fluid 12. The manufacturing apparatus 100 has a flow path 31 that introduces the fluid 22 in a gaseous state into the mixing vessel 30, a flow path 32 that introduces the fluid 12 in a gaseous state (such as a state of water vapor) into the mixing vessel 30, and an exhaust path 33 that exhausts a part of the gas (mixture of the fluids 12 and 22) in the mixing vessel 30. The exhaust path 33 is provided to suppress a sudden rise in pressure inside the mixing vessel 30, but when the pressure inside the mixing vessel 30 is low, gas may not be discharged from the exhaust path 33.

[0026] In the example shown in FIG. 4, the manufacturing apparatus 100 has a cooling unit 40 as a condensation mechanism unit that selectively condenses the fluid 12, which is easier to condense than the fluid 22. The cooling unit 40 is disposed around the mixing container 30 and has a function of cooling the fluid 12 and the fluid 22 in the mixing container 30 from the surroundings. The cooling unit 40 is, for example, a heat exchanger with a hollow structure, and has a flow path 42 for flowing a refrigerant 41 inside. The refrigerant 41 can selectively condense the fluid 12 as long as it is a fluid with a lower temperature than the gaseous fluid 12. However, as described later, in order to efficiently generate ultra-fine bubbles, it is preferable that the condensation time of the fluid 12 is short. Therefore, it is preferable to use a liquid, such as cold water, that has a large heat capacity and a large temperature difference with the gaseous fluid 12 as the refrigerant 41. When the fluid 12 is water vapor, even if the fluid 12 is water at about 5 to 10 degrees Celsius, the temperature difference ΔT with the fluid 12 can be sufficiently large. Furthermore, when the temperature difference ΔT is to be made even larger, an antifreeze liquid that is a liquid containing a component that lowers the freezing point may be used as the coolant 41.

[0027] As shown in FIG. 4, it is preferable that the flow paths 31, 32 and the exhaust path 33 are provided with valves 31V, 32V and 33V, respectively. The flow path 31 is provided with a valve 31V for adjusting the flow rate (flow velocity) of the fluid 22, and the flow path 32 is provided with a valve 32V for adjusting the flow rate (flow velocity) of the fluid 12. The exhaust path 33 is provided with a valve 33V for adjusting the flow rate of the exhaust gas. By controlling the open / closed state (opening degree) of the valves 31V, 32V and 33V, it is possible to control the pressure inside the mixing container 30 and the flow rates of the fluids 12 and 22. From the viewpoint of controlling the pressure of the mixing container 30 and the flow paths of each fluid, it is preferable that a pressure gauge 30PG capable of measuring the pressure inside the mixing container 30, and pressure gauges 31PG, 32PG and 33PG capable of measuring the pressure of each flow path are provided. Moreover, from the viewpoint of controlling the condensation speed of fluid 12, it is preferable that at least the flow rate (flow velocity) of fluid 12 and the flow rate (flow velocity) of fluid 22 are adjusted in accordance with the cooling performance of cooling section 40 serving as the condensation mechanism. In other words, it is preferable that the operation of valve 31V, the operation of valve 32V, and the operation of cooling section 40 serving as the condensation mechanism are controlled in conjunction with each other.

[0028] In the method for producing an ultra-fine bubble suspension using the production apparatus 100 shown in Fig. 4, for example, the following process is performed. First, in a fluid supplying step (see Fig. 6), the fluids 22 and 12 are each supplied into the mixing vessel 30. In the example shown in Fig. 4, the fluids 22 and 12 are each supplied into the mixing vessel 30 in a gaseous state. In the example shown in Fig. 4, the fluids 22 and 12 are each supplied into the mixing vessel 30 via flow paths 31 and 32 that are independent of each other.

[0029] Next, in the fluid mixing step (see FIG. 6), the fluids 22 and 12 are mixed in the gas phase in the mixing vessel 30. When the fluids 12 and 22 are supplied in the gas state into the mixing vessel 30 as in this embodiment, the concentration distribution of the fluids 12 and 22 in the mixing vessel 30 becomes almost uniform without any special mixing treatment due to the convection generated when the fluids 12 and 22 are supplied. However, in order to shorten the time until the concentration distribution becomes uniform, a treatment such as shaking may be performed. Alternatively, for example, when the concentration distribution becomes uneven in some places due to the large capacity of the mixing vessel 30, a stirring device (not shown) may be placed in the mixing vessel 30. However, as far as the inventors of the present application have confirmed experimentally, if the structure of the mixing vessel 30 is as shown in FIG. 4, no particular time is required until the concentration distribution becomes uniform after the fluids 12 and 22 are supplied, even without any special mixing treatment. For this reason, as will be described later as a modified example, the ultra-fine bubble suspension can be continuously produced.

[0030] Next, in the condensation step (see FIG. 6), the fluid 12, which is easier to condense than the fluid 22, is selectively condensed. When the condensation of the fluid 12 starts, droplets 13 containing non-condensable molecules 23 constituting the fluid 22 are generated as shown in FIG. 5, and the droplets 13 fall toward the bottom of the mixing vessel 30. As a result, the fluid 22 in a liquid state (hereinafter, sometimes referred to as condensate) containing a large number of non-condensable molecules 23 accumulates at the bottom of the mixing vessel 30. In the condensate accumulated at the bottom of the mixing vessel 30, the non-condensable molecules 23 become supersaturated with respect to the equilibrium concentration with respect to the molecules of the fluid 12 (hereinafter, referred to as condensate molecules in this paragraph). In the supersaturated state, the vaporization of the non-condensable molecules 23 progresses in the fluid 12 in a liquid state. At this time, the non-condensable molecules 23 vaporized in the condensate molecules combine to generate bubble nuclei 24, and bubble growth occurs in which bubbles with small distances combine to grow into larger bubbles. However, in the case of this embodiment, since the fluid 12 is dispersed so that the concentration distribution is uniform in the gas mixing process, bubble nucleation occurs more predominantly than bubble growth. Therefore, as explained with reference to FIG. 2, the frequency of bubble growth in which the bubble diameter D1 of the bubble nuclei 24 becomes larger than 1 μm due to bubble growth (bubble expansion is suppressed) is suppressed. Ultra-fine bubbles 20A having a size where Brownian motion is dominant compared to buoyancy do not rise to the surface and remain in the liquid phase, while bubbles having a size where buoyancy is dominant (non-ultra-fine bubbles 20B shown in FIG. 1) rise to the surface and leave the liquid phase. As a result, only the ultra-fine bubbles 20A remain in the condensate. This is the ultra-fine bubble suspension UFB1 shown in FIG. 7, which will be described later.

[0031] In the example shown in FIG. 4, the mixed fluid of the fluids 12 and 22 contained in the mixing vessel 30 is cooled by the cold energy of the refrigerant 41 flowing through the cooling section 40 as described above. The fluid 12 condenses at the temperature of the refrigerant 41, but the fluid 22 does not condense at the temperature of the refrigerant 41 and maintains its gaseous state. Therefore, the fluid 12 is selectively condensed. At this time, the gaseous fluid 22 dispersed in the fluid 12 is trapped by the liquefied fluid 12, and bubble growth occurs in the liquefied fluid 12 as explained with reference to FIG. 2. As a result, as shown in FIG. 5, an ultra-fine bubble suspension UFB1 in which a large number of ultra-fine bubbles 20A are dispersed in the liquefied fluid 12 is obtained at the bottom of the mixing vessel 30. Details will be described later, but as a result of the study by the inventors of the present application, it has been found that the number density of the ultra-fine bubbles 20A in the ultra-fine bubble suspension UFB1 is proportional to the condensation rate, which is a function of the condensation rate of the fluid 12, which is a condensable gas. Therefore, from the viewpoint of improving the yield of the ultra-fine bubbles 20A, it is preferable to increase the condensation rate. When the ultra-fine bubble suspension UFB1 is produced by a batch method, the cooling efficiency inside the mixing vessel 30 can be improved by intermittently supplying the high-temperature fluid 12. Therefore, it is preferable to perform the condensation step with at least the valve 32V of the valves 31V, 32V, and 33V in a closed state.

[0032] The ultra-fine bubble suspension UFB1 produced at the bottom of the mixing vessel 30 shown in Fig. 5 is taken out from the mixing vessel 30 (suspension taking out step shown in Fig. 6). The method for taking out the ultra-fine bubble suspension UFB1 is not particularly limited, and for example, a liquid collection flow path (not shown) may be connected to the mixing vessel 30, or the top of the mixing vessel 30 may be a removable lid, and the ultra-fine bubble suspension UFB1 inside may be taken out by removing the lid. After the ultra-fine bubble suspension UFB1 is taken out, the valves 31V, 32V, and 33V shown in Fig. 4 are opened again, and the fluids 12 and 22 are newly supplied into the mixing vessel 30 (second fluid supply step shown in Fig. 6). Thereafter, the above-mentioned processes from the fluid supply step to the suspension taking out step are repeated.

[0033] In the above, a method for performing the suspension removal step for each cycle has been described. However, as a modified example, multiple cycles can be performed successively with the ultra-fine bubble suspension UFB1 (see FIG. 7) remaining in the mixing vessel 30. FIG. 7 is an explanatory diagram showing a state in which a new fluid is supplied to the mixing vessel with the ultra-fine bubble suspension remaining. FIG. 8 is an explanatory diagram showing the state inside the mixing vessel after the second condensation step shown in FIG. 6 has been completed. FIG. 9 is a time chart showing the supply states of the condensable fluid and non-condensable fluid and the temperature profile inside the mixing vessel during the process of producing an ultra-fine bubble suspension.

[0034] As described above, the ultra-fine bubbles 20A shown in Fig. 7 have a small bubble diameter D1 (see Fig. 1), and are therefore not easily destroyed even when an external force is applied from outside the suspension. Therefore, even if new fluids 12 and 22 are supplied to the mixing vessel 30 while the ultra-fine bubble suspension UFB1 remains in the mixing vessel 30, most of the ultra-fine bubbles 20A that have already been generated will remain.

[0035] That is, the manufacturing method of the ultra-fine bubble suspension UFB1 according to the modified embodiment is as follows. After the first liquid supply to first condensation steps shown in Fig. 6 are completed, the manufacturing method of the ultra-fine bubble suspension UFB1 according to the modified embodiment further includes the following steps: (D) a second fluid supply step of newly supplying the fluid 22 (see Fig. 7) and the fluid 12 (see Fig. 7) into the mixing vessel 30 (see Fig. 7) in which the ultra-fine bubble suspension UFB1 (see Fig. 7) is contained; (E) a second fluid mixing step of mixing the newly supplied fluid 22 and the fluid 12 in the gas phase in the mixing vessel 30 after the step (D); and (F) a second condensation step of selectively condensing the fluid 12, which is easier to condense than the fluid 22, after the step (E). The ultra-fine bubble suspension UFB1 is not taken out of the mixing vessel 30 before the step (D). The suspension removal step of removing the ultra-fine bubble suspension UFB1 from the mixing vessel 30 is performed after the steps (D) to (F) are performed one or more times. The steps (D) to (F) can be repeatedly performed until the volume of the accumulated ultra-fine bubble suspension UFB1 exceeds the allowable amount (e.g., 50%) of the capacity of the mixing vessel 30 shown in Fig. 8 and the convection of the newly supplied fluids 12 and 22 becomes unstable.

[0036] According to the above modification, the ultra-fine bubble suspension UFB1 only needs to be taken out once every several cycles, which improves the production efficiency compared to the case where the ultra-fine bubble suspension UFB1 is taken out every cycle. As shown in Fig. 7, when the fluids 12 and 22 are newly supplied to the mixing vessel 30 while the ultra-fine bubble suspension UFB1 remains, the attachment positions of the flow paths 31 and 32 are preferably above the center in the height direction of the mixing vessel 30. Since the ultra-fine bubble suspension UFB1 accumulates at the bottom of the mixing vessel 30, if the flow paths 31 and 32 are attached at the top of the mixing vessel 30, the gaseous fluids 12 and 22 can be convected without being hindered by the remaining ultra-fine bubble suspension UFB1.

[0037] The above-mentioned method for producing an ultra-fine bubble suspension can be represented by the time chart shown in Fig. 9. In the example shown in Fig. 9, the fluid 22 is continuously supplied into the mixing vessel 30 (see Fig. 4) at a constant flow rate. The fluid 12, which is a condensable fluid, is supplied intermittently. At the start of the temperature-raising step P1, the valve 32V shown in Fig. 4 is opened, and the fluid 12 is supplied to the mixing vessel 30 in a gaseous state (e.g., water vapor) for a time (temperature-raising time) T1. During the temperature-raising step P1, the fluid 12, which is hotter than the temperature inside the vessel, flows into the mixing vessel 30, and the temperature inside the vessel rises.

[0038] Next, at the end of the temperature increasing step P1, in other words, at the start of the cooling step P2, the valve 32V shown in FIG. 4 is closed, and the supply of the fluid 12 is stopped during the time (cooling time) T2 of the cooling step P2. As shown in FIG. 4, the cooling section 40 is arranged around the mixing container 30, and the refrigerant 41 flows through the flow path 42 of the cooling section 40. Therefore, when the supply of the high-temperature fluid 12 is stopped, the temperature inside the mixing container 30 drops. The fluid 22 has a smaller heat capacity than the fluid 12, and is less likely to affect the change in the temperature inside the container. Therefore, in the example shown in FIG. 9, the fluid 22 is continuously supplied to the mixing container 30 even during the cooling step P2. When the internal pressure inside the mixing container 30 increases during the cooling step P2, excess gas is discharged from the exhaust path 33.

[0039] 9, the cooling step P2 also serves as a step of newly supplying the fluid 22 into the mixing vessel 30. Therefore, if the time T2 of the cooling step P2 is extremely short, the amount of the fluid 22 in the mixing vessel 30 may be insufficient when the heating step P1 is next performed. Therefore, it is preferable to set the time T2 so that the spatial time calculated by the following formula is 1 or more.

[0040] That is, the spatial time τ is calculated by the formula "τ=Q×(T2) / V" using the flow rate Q (volume) of the non-condensable gas per unit time and the cooling time T2, which are the maximum capacity V of the mixing vessel 30. If the spatial time τ calculated by the above formula is 1 or more, the fluid 22 will not be insufficient in the second heating step P1. Therefore, if the spatial time τ is 1 or more, the number density of the ultra-fine bubbles 20A in the obtained ultra-fine bubble suspension UFB1 will be significantly increased compared to when the spatial time τ is less than 1. On the other hand, if the spatial time τ is 1 or more, the number density of the ultra-fine bubbles will not change significantly whether the spatial time τ is 2 or 10. Therefore, from the viewpoint of shortening the working time, it is preferable to set the time T2 so that the spatial time τ is 1 or more and close to 1.

[0041] Next, after most of the fluid 12 in the mixing container 30 has liquefied, the supply of the gaseous fluid 12 is started again as the heating step P1. The timing of switching from the cooling step P2 to the heating step P1 can be determined according to the state of the fluid 12 in the mixing container 30, so the temperature inside the container may be higher than the temperature at the start of the initial heating step P1. Thereafter, the heating step P1 and the cooling step P2 are alternately repeated to obtain an ultra-fine bubble suspension UFB1 (see FIG. 8) in the container 30.

[0042] <Continuous manufacturing method> Next, as a modification of the batch type described above, a method of continuously producing and extracting an ultra-fine bubble suspension will be described. Fig. 10 is a time chart showing a modification of Fig. 9. Fig. 11 is an explanatory diagram showing an example of a production apparatus for producing an ultra-fine bubble suspension according to the time chart shown in Fig. 10.

[0043] The mixing vessel 30 of the production apparatus 101 shown in Fig. 11 differs from the production apparatus 101 described using Fig. 4 in that, in addition to the flow paths 31, 32 and the exhaust path 33, the mixing vessel 30 has a liquid discharge path 34 for discharging the ultra-fine bubble suspension UFB1 obtained by condensing the fluid 12 to the outside. In the example shown in Fig. 11, the production apparatus 101 also differs from the production apparatus 100 shown in Fig. 4 in that it has a thermometer 30TM for measuring the temperature inside the vessel.

[0044] The method for producing an ultra-fine bubble suspension using the production apparatus 101 is carried out, for example, according to the time chart shown in FIG. 10. The time chart shown in FIG. 10 differs from the time chart shown in FIG. 9 in that each of the fluids 12 and 22 is continuously (successively) supplied to the mixing vessel 30 in a gaseous state from the start of the temperature increasing step P3. In addition, the time chart shown in FIG. 10 differs from the time chart shown in FIG. 9 in that the supply of the gaseous fluid 12 is not stopped, and there is no cooling step P2 shown in FIG. 9, and the temperature inside the vessel is continuously maintained at a temperature lower than the dew point 12DP of the fluid 12. Note that the fluid 22 is continuously supplied into the mixing vessel 30 (see FIG. 4) at a constant flow rate, as in the time chart shown in FIG. 10. However, the value of the inflow amount S per unit time may differ from that shown in FIG. 10.

[0045] In the temperature rise process P3 shown in Fig. 11, the gaseous fluid 12 flows into the mixing vessel 30 for a time (temperature rise time) T3, thereby increasing the temperature inside the vessel. When the inflow amount S of the fluid 12 per unit time and the cooling performance of the cooling section 40 shown in Fig. 11 reach an equilibrium state, the increase in the temperature inside the vessel stops, and the continuous production process P4 is started. The temperature inside the vessel during the continuous production process P4 can be controlled by adjusting the inflow amount S of the fluid 12 per unit time, the inflow amount Q of the fluid 22 per unit time, and the cooling performance of the cooling section 40 (for example, the temperature and flow rate of the refrigerant 41, or the efficiency of heat exchange between the cooling section 40 and the mixing vessel 30, etc.). 11, the inflow rate S of fluid 12 per unit time, the inflow rate Q of fluid 22 per unit time, and the cooling performance of cooling section 40 are controlled so that the temperature difference between the temperature inside the container during continuous production process P4 and the dew point 12DP of fluid 12 is a value that allows continuous liquefaction of fluid 12. The time T4 for which continuous production process P4 is continued can be set arbitrarily.

[0046] The fluids 12 and 22 that flow continuously in a gaseous state are successively condensed to become droplets 13 containing non-condensable molecules 23 made of the fluid 22, as shown in FIG. 11. The droplets 13 fall toward the bottom of the mixing vessel 30. At the bottom of the mixing vessel 30, the non-condensable molecules 23 are vaporized as described with reference to FIG. 5. However, in the condensed liquid, bubble nucleation occurs more predominantly than bubble growth, so that an ultra-fine bubble suspension UFB1 containing ultra-fine bubbles 20A at a high concentration is obtained. The ultra-fine bubble suspension UFB1 generated at the bottom of the mixing vessel 30 shown in FIG. 11 is continuously taken out from a liquid discharge path 34 to the outside (liquid discharge step). A valve 34V that adjusts the discharge of the ultra-fine bubble suspension UFB1 is attached to the liquid discharge path 34. The discharge amount (discharge speed) of the ultra-fine bubble suspension UFB1 discharged from the liquid discharge path 34 can be controlled by controlling the opening of the valve 34V.

[0047] In this modified example, the ultra-fine bubble suspension UFB1 is continuously produced, and therefore the production efficiency can be further improved compared to the example shown in Fig. 9. In this modified example, the temperature inside the mixing vessel 30 needs to be lower than the dew point 12DP shown in Fig. 10. Therefore, as shown in Fig. 11, it is preferable that a thermometer 30TM for measuring the temperature inside the mixing vessel 30 is attached to the mixing vessel 30 so that the temperature inside the vessel can be monitored.

[0048] <Pressure method> Next, as an example of an embodiment in which the fluid 12 is selectively condensed by a method other than the cooling method described with reference to Figures 4 to 11, an embodiment in which the fluid 12 is condensed by pressurizing the inside of a mixing container will be described. Figure 12 is a time chart of a method for producing an ultra-fine bubble suspension, which is another modified example of Figure 9. Figures 13 to 16 are explanatory diagrams showing the respective states of the temperature increasing step, pressurizing step, and depressurizing step in a production apparatus for carrying out the production process of the ultra-fine bubble suspension shown in Figure 12.

[0049] The method for producing an ultra-fine bubble suspension shown in Fig. 12 differs from the method for producing an ultra-fine bubble suspension described with reference to Figs. 4 to 11 in that the fluid 12 is selectively condensed by pressurizing the inside of a mixing vessel 30 (see Fig. 13) containing gaseous fluids 12 and 22. A production apparatus 102 shown in Figs. 13 to 16 has the same structure as the production apparatus 100 shown in Fig. 4, except that the cooling unit 40 shown in Fig. 4 is not attached around the mixing vessel 30. Therefore, a duplicated description will be omitted.

[0050] As shown in Fig. 12, in the case of this modification, as a preparation step, the fluid 22 is supplied into the mixing container 30 (see Fig. 13). In this preparation step, the valve 32V shown in Fig. 13 is closed, and the valves 31V and 33V are open. The inflow amount Q of the fluid 22 per unit time in the preparation step is not particularly limited. Also, if the exhaust path 33 is open, the pressure in the mixing container 30 hardly increases.

[0051] Next, in the temperature increasing step P5 shown in FIG. 12, as shown in FIG. 13, the valve 32V is opened and the fluid 12 is supplied in a gaseous state into the mixing container 30 for a time (temperature increasing time) T5 (see FIG. 12). In the example shown in FIG. 13, in the temperature increasing step P5 (see FIG. 12), the valves 31V and 33V are closed and only the valve 32V is opened. However, since the temperature increasing step P5 is not a step for pressurizing, for example, the valve 31V may be opened to continue supplying the fluid 22. Alternatively, the valve 33V may be opened with a reduced opening to gradually discharge excess gas. As shown in FIG. 12, in the temperature increasing step P5, the pressure inside the container rises slightly, but a sudden pressure rise does not occur as in the next pressurizing step P6. In addition, although the profile of the temperature inside the container is not shown in FIG. 12, in the temperature increasing step P5, by introducing gaseous fluid 12, the temperature inside the container increases at a steeper angle than in the temperature increasing step P5 shown in FIG.

[0052] Next, in the pressurizing step P6, as shown in FIG. 14, the valve 31V is opened and the non-condensable fluid 12 is supplied for a time (pressurizing time) T6 to increase the internal pressure of the mixing container 30. In the pressurizing step P6, the valves 32V and 33V are closed, and only the valve 31V is opened to perform pressurization. As the internal pressure of the mixing container 30 increases, the fluid 12 inside the mixing container 30 condenses and falls toward the bottom of the mixing container 30 as droplets 13. At this time, similar to the example described using FIG. 5, the non-condensable molecules 23 of the gaseous fluid 22 around the fluid 12 are trapped inside the droplets 13, and ultra-fine bubbles 20A are formed at the bottom of the mixing container 30. In the pressurizing step P6, it is not necessary to adiabatically compress the gas inside the mixing container 30. Therefore, by pressurizing the inside of the mixing container 30, the temperature inside the container increases. Although not shown, the mixing container 30 may be cooled by contacting a refrigerant to suppress an excessive temperature increase.

[0053] Next, in the depressurization step P7, as shown in Fig. 15, the valve 31V is closed and the valve 33V is opened to discharge the gas (mainly the fluid 22) inside the mixing container 30 through the exhaust path 33 for a time (depressurization time) T7. As a result, the pressure inside the mixing container 30 is gradually reduced. The time T7 of the depressurization step P7 is longer than the time T6 of the pressurization step P6. While the internal pressure of the mixing container 30 is gradually reduced, most of the fluid 12 is liquefied, and the ultra-fine bubble suspension UFB1 is obtained. In addition, the temperature inside the container decreases in the depressurization step P7.

[0054] Fig. 12 shows a time chart for one cycle of producing an ultra-fine bubble suspension UFB1 (see Fig. 15) by the pressurization method. However, as in the example shown in Fig. 9, the cycle of the temperature increasing step P5, the pressurization step P6, and the depressurization step P7 may be carried out multiple times before the ultra-fine bubble suspension UFB1 is taken out. In this case, as shown in Fig. 16, in the second temperature increasing step P5, a new gaseous fluid 12 is supplied into the mixing vessel 30 while the ultra-fine bubble suspension UFB1 produced in the first cycle remains at the bottom of the mixing vessel 30.

[0055] <Decompression method> Next, as an example of an embodiment in which the fluid 12 is selectively condensed by a method other than the cooling method described with reference to Figures 4 to 11 and the pressurizing method described with reference to Figures 12 to 16, an embodiment in which the fluid 12 supplied in a liquid state to a mixing vessel is vaporized by reducing the pressure, mixed, and then condensed will be described. Figure 17 is a time chart of a method for producing an ultra-fine bubble suspension, which is another modified example of the method shown in Figure 9. Figure 18 is an explanatory diagram showing a production apparatus used in the method for producing the ultra-fine bubble suspension shown in Figure 17.

[0056] 18, the manufacturing apparatus 103 of this modified example has a storage section 50 that stores the fluid 22 and the fluid 12, a cylinder section 51 that can change the volume inside the storage section 50, a fluid introduction path 52 that communicates with the storage section 50 and introduces the fluid 22 and the fluid 12 into the storage section 50, and a valve 52V attached to the fluid introduction path 52. The cylinder section 51 is inserted into the storage section 50 and is movable up and down along the inner wall of the storage section 50. The fluid introduction path 52 communicates with the storage section 50.

[0057] The manufacturing process of the ultra-fine bubble suspension shown in Fig. 17 differs from the cooling method described with reference to Figs. 4 to 11 or the pressurizing method described with reference to Figs. 12 to 16 in that the fluid 12 in a liquid state is introduced into the container 50, which is a mixing container, and then the fluid 12 is vaporized in the container 50 to mix the fluids 12 and 22 in a gaseous state in the container 50. In other words, in the case of this modification, the above-mentioned step (A) includes a step (A1) of supplying the fluid 22 in a gaseous state and the fluid 12 in a liquid state into the mixing container (container 50), and a step (A2) of reducing the pressure in the container 50 while the container 50 is sealed after the above-mentioned step (A1), thereby vaporizing the fluid 12. In addition, in the case of this modification, the fluid 12 is selectively condensed by pressurizing the container 50 while the container 50 is sealed.

[0058] Specifically, the manufacturing process of the ultra-fine bubble suspension shown in Fig. 17 includes an apparatus preparation step P11, a gas suction step P12, a liquid suction step P13, a depressurization step P14, a gas mixing step P15, a pressurization step P16, and a suspension removal step P17. The operations performed in each step will be explained in detail below, and the reference numerals for each part of the manufacturing apparatus 103 are shown in Fig. 18.

[0059] In the apparatus preparation process P11, the manufacturing apparatus 103 shown in Fig. 18 is prepared. At this point, the cylinder portion 51 is inserted to the deepest part of the storage portion 50, and the capacity of the space surrounded by the storage portion 50 and the cylinder portion 51 is almost zero.

[0060] In the gas suction step P12, the cylinder portion 51 is raised to suck in the fluid 22 in a gaseous state. In this embodiment, since the fluid 12 is air as described above, simply opening the valve 52V and raising the cylinder portion 51 increases the volume of the space surrounded by the cylinder portion 51 and the storage portion 50, and as a result, the surrounding air (fluid 22) flows in from the fluid introduction path 52. The valve 52V is opened from the device preparation step P11 to the liquid suction step Next, in the liquid suction step P13, the tip portion of the fluid introduction path 52 is immersed in the liquid-state fluid 22 contained in the container. When the cylinder part 51 is raised in this state, the volume of the space surrounded by the cylinder part 51 and the storage part 50 further increases, and accordingly, the liquid-state fluid 12 around the tip of the fluid introduction path 52 flows in from the fluid introduction path 52.

[0061] Next, in the depressurization step P14, the valve 52V is closed to seal the space surrounded by the cylinder portion 51 and the storage portion 50. At the start of the depressurization step P14, the pressure inside the container is approximately the same as atmospheric pressure. In this step, the cylinder portion 51 is gradually raised to further increase the volume of the space surrounded by the cylinder portion 51 and the storage portion 50. At this time, since the space is now a sealed space, the pressure inside the container is reduced, and the fluid 12 contained therein is vaporized. The degree of depressurization is not particularly limited as long as it is possible to vaporize most of the fluid 12, but it is possible to set the pressure inside the container to a low vacuum (10 4 ~10 2 Pa) ~ Medium vacuum (10 2 ~10 -1 It is preferable to reduce the pressure to about 100 Pa. In this process, the fluid 12 is evaporated, and the heat of vaporization is removed, so the temperature inside the storage unit 50 is reduced. In order to prevent a part of the fluid 12 (water in this embodiment) from freezing due to the temperature drop, it is preferable to place a heat source (not shown) around the storage unit 50 and reduce the pressure in a warm state.

[0062] Next, in the gas mixing step P15, the fluids 12 and 22 sealed in the space surrounded by the cylinder section 51 and the storage section 50 are mixed to obtain a mixed gas with a uniform concentration distribution of the fluid 22, as described with reference to FIG. 2. This step is performed with the valve 52V in a closed state following the depressurization step P14. As described above, when the fluids 12 and 22 are in a gaseous state, the fluids 12 and 22 are easily dispersed. However, in the case of this modified example, the gas mixing step P15 is performed in a sealed state, and therefore, the mixing time can be shortened by performing a shaking operation to generate gas convection inside.

[0063] Next, in the pressurizing step P16, the cylinder part 51 is lowered to pressurize the space surrounded by the cylinder part 51 and the storage part 50. As described later, according to the study by the inventor of the present application, it has been found that the faster the condensation speed, the higher the number density of the ultra-fine bubbles 20A (see FIG. 2). Therefore, by shortening the pressurizing time in the pressurizing step P16 and applying pressure rapidly, the yield of the ultra-fine bubbles 20A can be improved. In the pressurizing step P16, the gaseous fluid 12 is successively condensed to become droplets 13 containing non-condensable molecules 23 (see FIG. 11) made of the fluid 22. The droplets 13 fall to the bottom of the storage part 50, and in the condensate accumulated at the bottom of the storage part 50, as described with reference to FIG. 2 and FIG. 5, bubble nucleation occurs more predominantly than bubble growth, resulting in the ultra-fine bubble suspension UFB1. As shown in FIG. 17, the pressurizing time in the pressurizing step P16 is at least shorter than the depressurizing time in the depressurizing step P14. Since this step is carried out after the depressurization step P14, and since it is a process for relatively increasing the internal pressure, it is described as the pressurization step P16. However, the internal pressure after pressurization is approximately the same as atmospheric pressure, and does not become a high-pressure state.

[0064] Next, in the suspension removal process P17, the valve 52V is opened and the ultra-fine bubble suspension UFB1 accumulated at the bottom of the storage section 50 is removed to the outside via the fluid introduction path 52. In this modification, the storage section 50 is sealed and depressurized and pressurized. In addition, since the supply path for the gaseous fluid 22 and the liquid fluid 12 and the discharge path for the ultra-fine bubble suspension UFB1 are common, after one cycle of the processes shown in Fig. 17 is performed, the suspension removal process P17 is performed for each cycle.

[0065] As described above, in the case of the various manufacturing methods of the present embodiment, the ultra-fine bubble suspension UFB1 can be stably manufactured with a simple manufacturing apparatus. Moreover, each of the above-mentioned manufacturing apparatuses is configured to have a small number of moving parts. For example, the manufacturing apparatus 100 shown in FIG. 4, the manufacturing apparatus 101 shown in FIG. 11, and the manufacturing apparatus 102 shown in FIG. 13 each have moving parts of about valves 31V, 32V, and 33V. Moreover, the manufacturing apparatus 103 shown in FIG. 18 has moving parts of about valve 52V and cylinder unit 51. By configuring the apparatus in this way with a small number of moving parts, the risk of equipment failure can be reduced.

[0066] <Number density setting> By the way, the inventors of the present application have experimentally evaluated the above-mentioned various embodiments and found that there is a proportional relationship between the condensation rate of the fluid 12 and the number density of the ultra-fine bubbles 20A contained in the obtained ultra-fine bubble suspension UFB1. If the materials of the fluids 12 and 22 are changed, the proportionality coefficient changes, but the proportional relationship itself is established.

[0067] In detail, the condensation rate and condensation speed are defined as follows: Condensation rate = (mass of condensed liquid) / (amount of condensable gas supplied to the mixing vessel) Condensation rate is defined as (condensation rate) / (time required for condensable gas to condense).

[0068] For example, in the example shown in Fig. 9, the mass of the condensed liquid is measured and used by measuring the mass of the ultra-fine bubble suspension UFB1 (see Fig. 5) obtained after the first cooling step P2. Also, the amount of condensable gas supplied into the mixing vessel is calculated and used by multiplying the flow rate (mass) per unit time of the gaseous fluid 12 supplied to the mixing vessel 30 (see Fig. 4) by the supply time T2 of the fluid 12. Also, the time required for condensation of the condensable gas is calculated and used by summing the times T1 and T2.

[0069] Also, in the example shown in FIG. 10, an arbitrary period included in the continuous production process P4 can be selected, and the calculation can be performed using the above-mentioned values ​​within the selected period.

[0070] The number density of ultra-fine bubbles in the ultra-fine bubble suspension UFB1 can be measured, for example, as follows: In the nanoparticle tracking method, a representative measurement method, the ultra-fine bubble suspension is irradiated with a two-dimensional planar laser beam, and the number density is determined by photographing the scattered laser light spots from the ultra-fine bubbles undergoing Brownian motion and counting the number of ultra-fine bubbles in the field of view.

[0071] Based on the above findings, it is possible to manufacture an ultra-fine bubble suspension UFB1 in which the number density of ultra-fine bubbles is controlled by controlling the manufacturing conditions of the ultra-fine bubble suspension UFB1. This makes it possible to provide an ultra-fine bubble suspension UFB1 in which ultra-fine bubbles are distributed at an optimum number density depending on the application.

[0072] The above manufacturing method can be expressed as follows: That is, the manufacturing method of the ultra-fine bubble suspension of this modified example includes a step of setting a target range for the number density of ultra-fine bubbles 20A in the ultra-fine bubble suspension UFB1 to be obtained, prior to the above step (A). In the above step (C), the condensation speed of the fluid 12 is controlled to obtain an ultra-fine bubble suspension UFB1 containing ultra-fine bubbles 20A with a number density within the target range.

[0073] The present invention is not limited to the above-described embodiments and examples, and may be modified without departing from the gist of the present invention. Various modifications can be made within a wide range. For example, in the above, an example was described in which air was used as the non-condensable fluid and water was used as the condensable fluid, but various modifications can be applied to the non-condensable fluid and the condensable fluid. As the non-condensable fluid, for example, an inert gas such as nitrogen or a rare gas, or a fluid having radical molecules such as ozone can be used. As the condensable fluid, for example, fuel-based oil or food-based oil can be exemplified. Also, for example, although various modifications have been described above, a part of the embodiment can be combined with another embodiment and applied. [Industrial Applicability]

[0074] The present invention can be used for ultra-fine bubble suspensions that are utilized in various industrial fields. [Explanation of symbols]

[0075] 10: liquid, 10t: liquid surface, 11: liquid molecules, 12, 22: fluid, 12DP: dew point, 13: droplets, 20: bubbles, 20A: ultrafine bubbles, 20B: non-ultrafine bubbles, 21: gas molecules, 23: non-condensable molecules, 24: bubble nuclei, 30: mixing vessel, 30PG, 31PG, 32PG, 33PG: pressure gauge, 30TM: thermometer, 31, 32, 42: flow path, 31V, 32V, 33V, 34V, 52V: valve, 33: exhaust path, 34: liquid exhaust path, 40: cooling section, 41: refrigerant, 50: storage section, 51: cylinder section , 52: Fluid introduction path, 100, 101, 102, 103: Manufacturing equipment, D1, D2: Bubble diameter, P1, P3, P5: Heating process, P2: Cooling process, P4: Continuous production process, P6: Pressurization process, P7: Depressurization process, P11: Equipment preparation process, P12: Gas suction process, P13: Liquid suction process, P14: Depressurization process, P15: Gas mixing process, P15: Next gas mixing process, P15: Gas mixing process in a sealed state, P16: Pressurization process, P17: Suspension removal process, Q, S: Inflow amount, T1 to T7: Time, UFB1: Ultra-fine bubble suspension

Claims

1. (A) supplying a first fluid and a second fluid that is more easily condensed than the first fluid into a mixing vessel; (B) mixing the first fluid and the second fluid in the gas phase in the mixing vessel; (C) after step (B), selectively condensing the second fluid; Including, In the step (A), each of the first fluid and the second fluid is supplied into the mixing vessel in a gaseous state, In the step (C), the second fluid is selectively condensed by pressurizing the inside of the mixing vessel.

2. (A) supplying a first fluid and a second fluid, the second fluid being more easily condensed than the first fluid, into a mixing vessel; (B) mixing the first fluid and the second fluid in the gas phase in the mixing vessel; (C) after step (B), selectively condensing the second fluid; Including, The step (A) comprises: (A1) supplying the first fluid in a gaseous state and the second fluid in a liquid state into the mixing vessel; (A2) after the step (A1), a step of reducing the pressure inside the mixing container while the mixing container is sealed, and vaporizing the second fluid; Including, In the step (C), the inside of the mixing container is pressurized while the inside of the mixing container is sealed, thereby selectively condensing the second fluid.

3. The method for producing an ultra-fine bubble suspension according to claim 2, The mixing vessel comprises: a container that contains the first fluid and the second fluid; A cylinder portion capable of changing a volume inside the accommodation portion; a fluid introduction path that communicates with the storage portion and introduces the first fluid and the second fluid into the storage portion; A valve attached to the fluid introduction path; The method for producing an ultra-fine bubble suspension comprising the steps of:

4. (A) supplying a first fluid and a second fluid that is more easily condensed than the first fluid into a mixing vessel; (B) removing from the mixing vessel an ultra-fine bubble suspension in which the second fluid has been selectively condensed; Including, In the step (A), the first fluid is provided through a first valve; the second fluid is provided through a second valve; In the mixing vessel, the first fluid and the second fluid are mixed in the gas phase, and the second fluid is selectively condensed; The ultra-fine bubble suspension extracted in the step (B) includes: The second fluid is in a liquid phase, and ultra-fine bubbles of the first fluid are present in the second fluid and are in a gas phase. The method includes a step of setting a target range for the number density of ultra-fine bubbles in the ultra-fine bubble suspension to be obtained, prior to the step (A), A method for producing an ultra-fine bubble suspension, wherein in the step (A), a condensation rate of the second fluid is controlled to obtain an ultra-fine bubble suspension having ultra-fine bubbles with a number density within the target range.

5. a mixing vessel capable of mixing the first fluid and the second fluid in a gas phase; a first flow path for introducing the first fluid in a gaseous state into the mixing vessel; a second flow path for introducing the second fluid in a gaseous state into the mixing vessel; an exhaust path for exhausting a part of the gas in the mixing vessel to the outside; a condensation mechanism that selectively condenses the second fluid that is more easily condensed than the first fluid; having The condensation mechanism selectively condenses the second fluid by pressurizing the inside of the mixing container.

6. A mixing vessel capable of mixing a first fluid and a second fluid in a gas phase, a first flow path for introducing the first fluid in a gaseous state into the mixing vessel; a second flow path for introducing the second fluid in a gaseous state into the mixing vessel; an exhaust path for exhausting a part of the gas in the mixing vessel to the outside; a condensation mechanism that selectively condenses the second fluid that is more easily condensed than the first fluid; having The apparatus further includes a liquid discharge path for taking out the ultra-fine bubble suspension, A first valve is attached to the first flow path to adjust the flow rate of the first fluid, A second valve is attached to the second flow path to adjust the flow rate of the second fluid, a valve for regulating the discharge of the ultra-fine bubble suspension is attached to the liquid discharge path; An apparatus for producing an ultra-fine bubble suspension, wherein the operation of the first valve, the operation of the second valve, and the operation of the condensation mechanism are controlled in conjunction with each other.

7. A mixing vessel capable of mixing a first fluid and a second fluid in a gas phase, a first flow path for introducing the first fluid in a gaseous state into the mixing vessel; a second flow path for introducing the second fluid into the mixing vessel in a liquid state; an exhaust path for exhausting a part of the gas in the mixing vessel to the outside; The mixing vessel comprises: reducing a pressure inside the mixing container while the mixing container is sealed, thereby vaporizing the second fluid; pressurizing the mixing vessel while the mixing vessel is sealed, thereby selectively condensing the second fluid; This is an ultra-fine bubble suspension manufacturing device that can

8. A mixing vessel capable of mixing a first fluid and a second fluid in a gas phase, a fluid introduction path capable of introducing the first fluid into the mixing vessel in a gaseous state and introducing the second fluid into the mixing vessel in a liquid state; A valve attached to the fluid introduction path; having The mixing vessel comprises: a container that contains the first fluid and the second fluid; A cylinder portion capable of changing a volume inside the accommodation portion; having The mixing vessel comprises: reducing a pressure inside the container while the mixing container is sealed, thereby vaporizing the second fluid; selectively condensing the second fluid by pressurizing the inside of the container while the inside of the mixing container is sealed; is possible, The fluid introduction path is connected to the storage section and is capable of introducing the first fluid and the second fluid into the storage section of the mixing vessel.

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