Microbubble generator

Abstract

To provide a fine bubble generation device which can improve density of fine bubbles by bringing liquid into contact with a gas generating medium plural times without providing a pump for returning liquid to the upstream side.SOLUTION: A fine bubble generation device comprises: a plurality of liquid storage containers 21A, 21B which store liquid; a liquid passage 22 in which liquid flows; a gas supply device 23 which pressure-feeds and supplies gas to the liquid passage 22; and a bubble generating medium 24 which discharges the gas pressure-fed by the gas supply device 23 into liquid in the liquid passage 22 as fine bubbles. The plurality of liquid storage containers 21A, 21B are respectively connected to openings 22a, 22b provided in the liquid passage 22. The inside of the liquid storage container 21A is pressurized by supplying a portion of the gas from the gas supply device 23 to the liquid storage container 21A, and liquid is moved from the liquid storage container 21A to the liquid storage container 21B.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the technology of microbubble generators.

Background Art

[0002] In recent years, technologies using microbubbles with a bubble size (diameter) of less than 100 μm at normal temperature and normal pressure in liquids such as tap water, lakes, marshes, rivers, and seawater have attracted attention. Microbubbles have physicochemical properties such as an extremely large surface area characteristic and a self-pressurization effect, and by taking advantage of these properties, technologies for use in wastewater purification, cleaning, gas dissolution, stirring and the like have been developed.

[0003] As a microbubble generator with the above properties, a microbubble generator is known that includes a passage for flowing liquid, a compression device for pumping gas to the passage, and a bubble generation medium that releases the gas pumped by the compression device as microbubbles into the liquid in the passage (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] Conventional bubble generation media have a gas inlet for receiving gas pumped by a compression device and an internal space serving as a gas passage, with one end of the internal space being a closed end formed to be closed. By forming in this way, gas that enters the liquid in the passage through the fine pores of the bubble generation medium is released as microbubbles.

[0006] When using water as the liquid, conventional liquid passages only allow the liquid to flow in one direction. Therefore, if water containing microbubbles is to be introduced into the passage to increase the gas concentration, it is necessary to recirculate the water discharged from the downstream side back up from the upstream side. Furthermore, a separate liquid pumping mechanism, such as a pump, is required to circulate the liquid.

[0007] Therefore, in view of these problems, the present invention provides a microbubble generating device that can improve the concentration of microbubbles by bringing the liquid into contact with the gas generating medium multiple times without providing a pump to return the liquid to the upstream side. [Means for solving the problem]

[0008] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0009] In other words, the present invention provides a microbubble generating device comprising: a plurality of liquid storage containers for storing liquid; a passage for flowing liquid; a gas supply device for pressurizing and supplying gas to the passage; and a bubble generating medium for releasing the gas pressurized by the gas supply device as microbubbles into the liquid in the passage, wherein each of the plurality of liquid storage containers is connected to an opening provided in the passage, and a portion of the gas is supplied from the gas supply device to one of the liquid storage containers to pressurize the inside of the liquid storage container, thereby moving the liquid from one liquid storage container to the other. The gas supply device then supplies a portion of the gas to the other liquid storage container to pressurize it, thereby moving the liquid from the other liquid storage container to the first liquid storage container. It is.

[0010] Furthermore, in the present invention, a branch valve may be provided in the gas passage connecting the gas supply device and the plurality of liquid storage containers.

[0011] Furthermore, in the present invention, the gas supplied from the gas supply device is oxygen. An ozone generator may be installed in the middle of the gas supply passage that sends gas from the gas supply device to the bubble generating medium.

[0012] Furthermore, in the present invention, a neutralizing agent may be placed between the branch valve and the liquid storage container. [Effects of the Invention]

[0013] The present invention provides the following effects:

[0014] In the present invention, by supplying a portion of the gas from a gas supply device to pressurize the liquid storage container and moving the liquid from one liquid storage container to the other, the liquid can be brought into contact with the gas generating medium multiple times without the need for a pump to return the liquid to the upstream side, thereby improving the concentration of fine bubbles. [Brief explanation of the drawing]

[0015] [Figure 1] A schematic front view showing a microbubble generating device according to the first embodiment. [Figure 2] A partial front cross-sectional view showing a microbubble generating medium according to the first embodiment. [Figure 3] An enlarged cross-sectional view showing a microbubble generating medium according to the first embodiment. [Figure 4] A perspective view showing a unit of a tube and bubble generating medium according to the first embodiment. [Figure 5] A schematic front view showing a microbubble generating device used when pumping gas into a liquid storage container according to the first embodiment. [Figure 6] A schematic front view showing a microbubble generating device used when pumping gas into a liquid storage container according to the first embodiment. [Figure 7] A schematic front view showing a microbubble generating device used when pumping gas into a liquid storage container according to the first embodiment. [Figure 8] A schematic front view showing a microbubble generating device equipped with a sensor according to the first embodiment. [Modes for carrying out the invention]

[0016] Next, embodiments of the invention will be described. First, the overall configuration of a fine bubble generating device 1 according to an embodiment of the present invention will be described with reference to Figure 1. The fine bubble generating device 1 is a device for generating fine bubbles in a liquid. Here, the fine bubbles refer to bubbles having a size (diameter) of several hundred nanometers to several tens of micrometers at normal temperature and normal pressure. The applications of the fine bubble generating device 1 are, for example, for aquaculture or wastewater treatment. In aquaculture, oxygen is supplied to oxidize and purify nitrogen compounds such as ammonia and urea that inhibit growth when cultivating fish and shellfish. Further, in aquaculture, the supplied oxygen imparts activity to fish and shellfish and promotes their growth. In wastewater treatment, oxygen, ozone or the like is supplied to perform oxidative decomposition treatment of organic matter contained in wastewater.

[0017] As shown in Figure 1, the fine bubble generating device 1 includes a plurality of liquid storage containers 21A and 21B that store liquid, a liquid passage 22 through which the liquid flows, a gas supply device 23 that pressure-feeds and supplies gas to the liquid passage 22, and a bubble generating medium 24 that releases the gas pressure-fed by the gas supply device 23 into the liquid in the liquid passage 22 as fine bubbles.

[0018] The liquid storage containers 21A and 21B are containers that store liquid in which gas is dissolved or coexists as fine bubbles. The liquid storage containers 21A and 21B are pressure-resistant containers having a volume of several liters to more than ten liters, and are formed of, for example, PET. A sealing lid 21a is provided at the upper part of the liquid storage container, which seals the gas and liquid inside the liquid storage containers 21A and 21B. Here, "dissolved" means a state in which gas is dissolved and present in the liquid. In addition, "coexisting" means a state in which gas is present as fine bubbles in the liquid. The liquid stored in the liquid storage containers 21A and 21B is water for a fine bubble generating device for aquaculture, and sewage for a fine bubble generating device for wastewater treatment.

[0019] In the microbubble generator 1 for aquaculture, by cultivating fish and shellfish in a liquid containing dissolved gas or coexisting as microbubbles, aerobic bacteria that decompose the waste products of the fish and shellfish can be activated, thereby purifying the liquid. In addition, by supplying sufficient oxygen, the immunity of the cultivated fish and shellfish can be improved, and their growth can be promoted.

[0020] In a microbubble generator for wastewater treatment, wastewater is treated in a liquid containing dissolved gas or coexisting as microbubbles. This activates bacteria and other organisms that decompose organic matter in the wastewater, thereby purifying the liquid.

[0021] The liquid passage 22 is a component for passing liquid through. The first opening 22a of the liquid passage 22 is connected to the sealed lid 21a of the liquid storage container 21A, and the second opening 22b of the liquid passage 22 is connected to the sealed lid 21a of the liquid storage container 21B. In addition, the middle section of the liquid passage 22 is composed of a tube 25 that houses the bubble generating medium 24 inside.

[0022] The gas supply device 23 is a device that pressurizes and supplies gas to the bubble generating medium 24 provided in the liquid passage 22, and comprises a gas storage container 27 and an on-off valve 28. The gas supplied from the gas supply device 23 is air, oxygen, ozone, or hydrogen peroxide if it is a microbubble generating device 1 for aquaculture, and a gas with oxidizing properties if it is a microbubble generating device 1 for wastewater treatment, such as oxygen, ozone, or hydrogen peroxide. The gas in the gas storage container 27 is stored under high pressure, and the gas is pressurized and sent to the gas supply passage 31 by opening and closing the on-off valve 28.

[0023] The on / off valve 28 is a switching valve that adjusts the pressure of the high-pressure gas in the gas storage container 27 and either discharges or stops it, and is a valve that reduces the pressure of the high-pressure gas in the gas storage container 27 and supplies it into the gas supply passage 31.

[0024] Furthermore, the gas supply device 23 may have a configuration other than one comprising a gas storage container 27 and an on-off valve 28, as long as it is capable of pressurizing and supplying gas. For example, it can be configured with a compressor that compresses and supplies atmospheric air.

[0025] The gas supply passage 31 is a passage for pressurizing gas from the gas supply device 23 to the bubble generating medium 24 provided in passage 22. The upstream end of the gas supply passage 31 is connected to the on-off valve 28, and the downstream end is connected to the internal space 24a of the bubble generating medium 24.

[0026] A branch passage 31a is provided in the middle of the gas supply passage 31, and the storage container side supply passage 31b extends from the branch passage 31a. The storage container side supply passage 31b is a passage for supplying high-pressure gas to the liquid storage containers 21A and 21B.

[0027] A check valve 36 to prevent backflow of gas and a pressure regulating valve 37a to adjust the gas pressure are provided in the middle of the gas supply passage 31. The check valve 36 is a valve that prevents the pumped gas from flowing back towards the gas supply device 23. The pressure regulating valve 37a is a valve that regulates the gas pressure when pumping the gas to the bubble generating medium 24. The gas pressure regulated by the pressure regulating valve 37a is higher than atmospheric pressure, specifically greater than 0.1 MPa and 0.8 MPa or less.

[0028] Furthermore, an ozone generator 35 is provided in the middle of the gas supply passage 31, downstream of the check valve 36. The ozone generator 35 is a device that generates ozone from oxygen, and the method of ozone generation is not limited. For example, it may be a device that generates ozone from oxygen molecules by ultraviolet irradiation, or a device that generates ozone from oxygen molecules by silent discharge.

[0029] Furthermore, a pressure regulating valve 37b is provided in the middle of the supply passage 31b on the storage container side to adjust the gas pressure. The pressure regulating valve 37b is a valve that adjusts the gas pressure when it is pumped to the liquid storage containers 21A and 21B. The gas pressure adjusted by the pressure regulating valve 37b is higher than atmospheric pressure, specifically greater than 0.1 MPa and 0.8 MPa or less.

[0030] A four-port valve 32, which is a branch valve that supplies gas to either the liquid storage container 21A or 21B, is located in the middle of the supply passage 31b on the storage container side. A discharge pipe 34 for discharging gas to the outside is located in one of the ports of the four-port valve 32. The four-port valve 32 is configured as a closed-center valve as shown in the figure, but it is not limited to this and may also be configured as an open-center valve.

[0031] As shown in Figures 1 and 2, the bubble-generating medium 24 is located inside the tube 25 that constitutes the middle section of the liquid passage 22. The bubble-generating medium 24 has an internal space 24a for passing gas through and is positioned so as to be horizontal or lower with respect to the direction in which the liquid flows through the tube 25 (direction of the black-colored arrow in Figure 2). In this embodiment, the bubble-generating medium 24 is positioned so that its downstream side is inclined downward with respect to the longitudinal direction of the tube 25.

[0032] Furthermore, the bubble-generating medium 24 is made of a carbon-based porous material and, as shown in Figure 3, has numerous fine pores 24b with diameters ranging from several micrometers to tens of micrometers. In addition, the bubble-generating medium 24 is a conductor, and the bubbles generated from the bubble-generating medium 24 are negatively charged. In other words, the microbubbles become negatively charged when they pass through the conductive bubble-generating medium 24, as free electrons are added to them. This negative charge causes the bubbles to repel each other, preventing them from merging and forming larger bubbles. Carbon-based porous materials are inorganic materials consisting solely of carbon or a composite material containing carbon and ceramics. Furthermore, a film several nanometers thick is formed on the surface of the carbon-based porous material. This film is made of an inorganic material containing silicon.

[0033] The pipe 25 and the bubble generating medium 24 can also be provided as a unit 41, as shown in Figure 4. The unit 41, in which the bubble generating medium 24 is placed inside the pipe 25, is configured to be connectable in series in a direction parallel to the direction of the liquid flowing inside the pipe 25 (in the direction of the black-colored arrow in Figure 2). That is, cylindrical connecting parts 42 are provided at both ends of the pipe 25, and the units 41 are connected in series via the connecting parts 42. In this embodiment, three units 41 are connected. With this configuration, even if a liquid already contains coexisting microbubbles, the microbubble generating device 1 can supply even more microbubbles. For example, in a method that generates microbubbles using shear force, if shear force is applied continuously, the microbubbles recombine, so the amount of coexisting microbubbles actually decreases. In contrast, by arranging the bubble-generating medium 24 in series in the direction of liquid flow, the time the liquid is in contact with the bubble-generating medium 24 is increased, allowing for the effective use of the liquid flow and enabling the coexistence of high-concentration fine bubbles with less power. Furthermore, because the bubble-generating medium 24 is arranged in series, the fine bubbles can coexist without recombining. This configuration makes it possible to increase the amount of fine bubbles coexisting in the liquid.

[0034] Next, a method for generating microbubbles using two liquid storage containers 21A and 21B and a gas supply device 23 will be described. First, as shown in Figure 5, the 4-port valve 32 is operated to pressurize a portion of the gas supplied from the gas supply device 23 to the liquid storage container 21A. A portion of the gas pressurized from the gas supply device 23 passes through the branch passage 31a and the storage container side supply passage 31b, enters from the inlet side of the 4-port valve 32, and is sent to the liquid storage container 21A. The liquid from the liquid storage container 21A flows into the pipe 25 of the liquid passage 22.

[0035] Meanwhile, oxygen is supplied under pressure from the gas supply device 23. The oxygen supplied under pressure from the gas supply device 23 is supplied into the ozone generator 35 through the gas supply passage 31. Ozone is generated from the oxygen in the ozone generator 35, and the ozone is supplied to the internal space 24a of the bubble generating medium 24. The ozone supplied to the bubble generating medium 24 passes through fine holes 24b with a diameter of several micrometers to tens of micrometers provided in the bubble generating medium 24, becomes microbubbles, and is released into the liquid in the tube 25. The microbubbles released into the liquid are separated from the surface of the bubble generating medium 24 by the surrounding liquid flow (flow in the direction of the arrows in Figure 2) the moment they are released onto the surface of the bubble generating medium 24. At this time, since the bubble generating medium 24 is positioned horizontal or lower with respect to the liquid flow in the tube 25, the microbubbles tend to move downward when separating from the surface of the bubble generating medium 24 (direction of the white-colored arrows in Figure 2), and tend to accumulate at the bottom. This configuration allows the microbubbles to move into the liquid independently without merging with any microbubbles that are generated later or from the surrounding pores 24b.

[0036] The liquid containing dissolved ozone or fine bubbles flows from the downstream end of pipe 25 into the other liquid storage container 21B. The liquid containing dissolved ozone or fine bubbles is stored in the liquid storage container 21B.

[0037] Next, as shown in Figure 6, the 4-port valve 32 is operated to pump a portion of the gas supplied from the gas supply device 23 to the liquid storage container 21B. Meanwhile, the gas in the liquid storage container 21A is discharged through the discharge pipe 34. A portion of the gas pumped from the gas supply device 23 passes through the branch passage 31a and the storage container side supply passage 31b, enters from the inlet side of the 4-port valve 32, and is sent to the liquid storage container 21B side. The liquid from the liquid storage container 21B side flows into the pipe 25 of the liquid passage.

[0038] Meanwhile, oxygen is supplied under pressure from the gas supply device 23. The oxygen supplied under pressure from the gas supply device 23 is supplied into the ozone generator 35 through the gas supply passage 31. Ozone is generated from the oxygen in the ozone generator 35, and the ozone is supplied to the internal space 24a of the bubble generating medium 24. The ozone supplied to the internal space 24a passes through fine holes 24b, which are several μm to tens of μm in diameter, provided in the bubble generating medium 24, and is released into the liquid in the tube 25 as microbubbles. The microbubbles released into the liquid are separated from the surface of the bubble generating medium 24 by the surrounding liquid flow (flow in the direction of the arrows in Figure 2) the moment they are released onto the surface of the bubble generating medium 24. At this time, since the bubble generating medium 24 is positioned horizontal or lower with respect to the liquid flow in the tube 25, the microbubbles tend to move downward when separating from the surface of the bubble generating medium 24 (in the direction of the white-colored arrows in Figure 2), and tend to accumulate at the bottom. This configuration allows the microbubbles to move into the liquid independently without merging with any microbubbles that are generated later or from the surrounding pores 24b.

[0039] Liquid containing dissolved ozone or coexisting as fine bubbles flows from one end of pipe 25 into the other end, liquid storage container 21A. The liquid containing dissolved ozone or coexisting as fine bubbles is stored in liquid storage container 21A.

[0040] Furthermore, as shown in Figure 7, the 4-port valve 32 is operated to pressurize and again pump a portion of the gas supplied from the gas supply device 23 to the liquid storage container 21A. Meanwhile, the gas in the liquid storage container 21B is discharged through the discharge pipe 34. At this time, the liquid storage device 21B contains ozone that was not dissolved and evaporated from the water. This ozone-containing gas is decomposed into harmless oxygen by a neutralizing agent 38 provided midway through the supply passage 31b on the storage container side and discharged through the discharge pipe 34.

[0041] With this configuration, the movement of liquid from liquid storage container 21A to liquid storage container 21B and vice versa can be achieved solely by the gas pressure of the gas supply device 23. Furthermore, since the bubble generating medium 24 can generate fine bubbles with separation as long as a water flow is present, it is possible to create a liquid with a high concentration of dissolved gas through the reciprocal movement of the liquid flow. The dissolved concentration will be 90% or higher. In addition, since more ozone generated from the bubble generating medium 24 is dissolved or coexists as fine bubbles, the amount of excess ozone generated is reduced, and the amount of ozone that needs to be treated when discharged to the outside is reduced. As a result, by simply placing the neutralizing agent 38 between the 4-port valve 32 and the liquid storage containers 21A and 21B, ozone can be rendered harmless and discharged without the need for a large decomposition device.

[0042] Furthermore, the switching of the 4-port valve 32 can also be automated by placing level sensors 55 as sensors in the liquid storage containers 21A and 21B. The level sensors 55 are sensors that measure the liquid level and output to the control device 56 when the liquid level reaches a predetermined height. For example, when the 4-port valve 32 is in a position to pump a portion of the gas supplied from the gas supply device 23 to the liquid storage container 21A, the control device 56 switches the 4-port valve 32 to a position where a portion of the gas supplied from the gas supply device 22 is pumped to the liquid storage container 21B when the liquid level in the other storage container 21B reaches a predetermined height. Note that the sensors are not limited to level sensors 55, as long as they can detect when pumping to the liquid storage containers 21A and 21B has ended. For example, the sensors may be photoelectric sensors that detect when pumping has ended, weight sensors that detect changes in the weight of the containers, or pressure sensors that detect changes in the pumping pressure. By configuring it in this way, it becomes possible to automatically produce a liquid containing a large amount of ozone as fine bubbles simply by pouring liquid into the liquid storage containers 21A and 21B.

[0043] As described above, the microbubble generator 1, which is one embodiment of the present invention, is a microbubble generator comprising a plurality of liquid storage containers 21A and 21B for storing liquid, a liquid passage 22 for flowing liquid, a gas supply device 23 for pressurizing and supplying gas to the liquid passage 22, and a bubble generating medium 24 for releasing the gas pressurized by the gas supply device 23 as microbubbles into the liquid in the liquid passage 22. The plurality of liquid storage containers 21A and 21B are each connected to openings 22a and 22b provided in the liquid passage 22, and a portion of the gas is supplied to the liquid storage container 21A from the gas supply device 23 to pressurize the inside of the liquid storage container 21A, thereby moving the liquid from the liquid storage container 21A to the liquid storage container 21B. With this configuration, the movement of liquid from liquid storage container 21A to liquid storage container 21B and vice versa can be performed solely by the gas pressure of the gas supply device 23. Therefore, fine bubbles can be generated with a simple configuration without the need to prepare a separate pump for liquid transfer. Furthermore, by performing a return movement from liquid storage container 21B to liquid storage container 21A after the movement from liquid storage container 21A to liquid storage container 21B, the opportunities for liquid to come into contact with each bubble-generating medium 24 can be increased, thereby improving the dissolved gas concentration in the liquid.

[0044] Furthermore, a 4-port valve 32, which is a branch valve, is provided in the storage container side supply passage 31b that connects the gas supply device 23 to the multiple liquid storage containers 21A and 21B. With this configuration, the gas supplied from the gas supply device 23 can be supplied individually to each liquid storage container 21A and 21B, and the gas inside each liquid storage container 21A and 21B can be discharged individually.

[0045] Furthermore, the gas supplied from the gas supply device 23 is a gas containing oxygen or nitrogen, and an ozone generator 35 is installed in the middle of the gas supply passage 31 that sends the gas from the gas supply device 23 to the bubble generating medium 24. By configuring it in this way, ozone, which has sterilizing and oxidizing effects, can be generated from the microbubble generating medium 24 and dissolved in the liquid or coexist as microbubbles.

[0046] Furthermore, a neutralizing agent 38 is provided between the 4-port valve 32 and the liquid storage containers 21A and 21B. This configuration allows for the neutralization of ozone evaporated from the liquid within the liquid storage container before discharge. Furthermore, because the dissolved ozone concentration is higher than usual and the amount of excess ozone generated is low, it can be discharged as non-toxic oxygen without the need for a large ozone decomposition device.

[0047] In this embodiment, the branch passage 31a is configured to move liquid from liquid storage container 21A to liquid storage container 21B and vice versa by pressurizing the gas supplied from the gas supply device. However, the embodiment is not limited to this configuration, and a compressor may be provided as a separate air supply means at the upstream end of the storage container side supply passage 31b. In this configuration as well, a liquid pressurizing means such as a large pump for circulating the liquid is not required, thus reducing costs.

[0048] Furthermore, the technical scope of the present invention is not limited to the embodiments described above, but broadly extends to the entire scope of the technical idea that the present invention truly intends, as will become clear from the matters described herein and in the drawings. [Explanation of Symbols]

[0049] 1. Microbubble Generator 21A / 21B Liquid Storage Containers 22 Liquid passage 23 Gas supply device 24 Bubble-generating medium 25 tubes 27 Gas storage containers 28. Shut-off valves 31 Gas supply passage 31a Branch road 31b Supply passage on the storage container side 32 4-port valve (branch valve) 34 Discharge pipe 35. Ozone Generator 36 Check valve 37a Pressure Regulating Valve 37b Pressure Regulating Valve 38 Neutralizing agent 41 units 55 Level Sensor 56 Control device

Claims

1. A microbubble generating device comprising: a plurality of liquid storage containers for storing liquids; a passage for flowing liquids; a gas supply device for pressurizing and supplying gas to the passage; and a bubble generating medium for releasing the gas pressurized by the gas supply device as microbubbles into the liquid in the passage, Each of the aforementioned liquid storage containers is connected to an opening provided in the passage, A portion of the gas from the gas supply device is supplied to one of the liquid storage containers to pressurize the inside of the liquid storage container, and the liquid is moved from one liquid storage container to the other. A portion of the gas from the gas supply device is supplied to the other liquid storage container to pressurize the inside of the other liquid storage container, and the liquid is moved from the other liquid storage container to the first liquid storage container. A microbubble generating device characterized by the following features.

2. A branch valve is provided in the gas passage connecting the gas supply device and the plurality of liquid storage containers. The microbubble generating apparatus according to feature 1.

3. The gas supplied from the gas supply device is a gas containing oxygen or nitrogen. An ozone generator is installed in the middle of the gas supply passage that sends gas from the gas supply device to the bubble generating medium. The microbubble generating apparatus according to feature 2.

4. A neutralizing agent is placed between the branch valve and the liquid storage container. The microbubble generating apparatus according to feature 3.

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