Foam generator

Abstract

To provide a foam generator capable of generating fine bubbles with a sufficient particle number concentration. [Solution] The foam generator is a foam generator having a flow path through which liquid flows from upstream to downstream, comprising: a first flow path section having a base opening into which liquid can flow from the outside; a second flow path section connected to the downstream side of the first flow path section and into which liquid can flow from the first flow path section; a gas inlet section connected to the first flow path section and the second flow path section, respectively, and into which gas can flow from the first flow path section and the second flow path section; and a third flow path section connected to the downstream side of the second flow path section and into which liquid can flow from the second flow path section, wherein the first flow path section has an open plate having a plurality of openings into which liquid can flow, and a diameter-reducing section provided on the downstream side of the open plate and decreasing in diameter toward the downstream side, the second flow path section has an expanding section that increases in diameter toward the downstream side, and a constricting section that forms an annular flow path along the inner circumferential surface of the expanding section, and the third flow path section has a flow path wider than the annular flow path formed by the constricting section.

Description

Technical Field

[0001] The present invention relates to a bubble generator.

Background Art

[0002] Conventionally, a gas heater, a gas welder, or a gas cutter that emits a flame to a workpiece using a mixed gas obtained by mixing a gas such as oxygen and a fuel gas for heating is known (for example, Patent Document 1). In such a gas heater, a gas welder, or a gas cutter, for example, a mixer unit is provided in which a flow path through which oxygen flows, a flow path through which fuel gas flows, and a flow path through which these flow paths merge and a mixed gas flows are formed.

[0003] The inventors of the present application have discovered that fine bubbles can be generated by mixing a gas and a liquid using the above-described mixer unit. Fine bubbles are fine bubbles having a diameter of less than 100 μm mixed in a liquid. For example, fine bubbles having a diameter of 1 μm or more and less than 100 μm are called microbubbles, and fine bubbles having a diameter of less than 1 μm are called ultrafine bubbles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when fine bubbles such as ultrafine bubbles are generated using the mixer unit of a conventional gas heater, a gas welder, or a gas cutter, there is a possibility that the particle number concentration of the generated fine bubbles is insufficient. The particle number concentration indicates the number of fine bubbles per unit amount of a gas-liquid mixed fluid containing the fine bubbles.

[0006] Based on the above circumstances, the present invention aims to provide a foam generator capable of generating fine bubbles with a sufficient particle number concentration. [Means for solving the problem]

[0007] To solve the above problems, this invention proposes the following means. The foam generator of the present invention is a foam generator having a flow path through which liquid flows from an upstream side to a downstream side, comprising: a first flow path section having a base end opening into which the liquid can flow from the outside; a second flow path section connected to the downstream side of the first flow path section and into which the liquid can flow from the first flow path section; a gas inlet section connected to the first flow path section and the second flow path section, respectively, and into which gas can flow into the first flow path section and the second flow path section; and a third flow path section connected to the downstream side of the second flow path section and into which the liquid can flow from the second flow path section, wherein the first flow path section has an open plate having a plurality of openings into which the liquid can flow, and a reduced diameter section provided on the downstream side of the open plate and reducing in diameter toward the downstream side; the second flow path section has an enlarged diameter section that expands in diameter toward the downstream side, and a constricted section that forms an annular flow path along the inner circumferential surface of the enlarged diameter section; and the third flow path section has a flow path wider than the annular flow path formed by the constricted section. [Effects of the Invention]

[0008] The foam generator of the present invention provides a foam generator that can generate fine bubbles with a sufficient particle number concentration. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a foam generator according to this embodiment. [Figure 2] This diagram schematically shows the first perforated plate of the foam generator. [Figure 3] This diagram schematically shows the gas inlet pipe of the foam generator. [Figure 4] This diagram schematically shows the second perforated plate of the foam generator. [Figure 5]This graph shows the results of particle number concentration measurements. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a cross-sectional view showing the foam generator 100 according to this embodiment.

[0011] The foam generator 100 comprises a first flow path section 10, a gas inlet section 20, a second flow path section 30, a third flow path section 40, and a fourth flow path section 50.

[0012] As shown in Figure 1, the foam generator 100 is substantially cylindrical in shape with a central axis (axis) O. A liquid such as water can flow through the internal space of the foam generator 100. The foam generator 100 is mainly made of metal or the like, and the liquid flowing inside the foam generator 100 does not leak out to the outside from any part other than a predetermined opening. The foam generator 100 only needs to be made of a material that is impermeable to liquids and gases, and may be made of resin, for example.

[0013] In this embodiment, as shown in Figure 1, the direction in which the axis O of the foam generator 100 extends is defined as "axial direction (flow direction) A". The axial direction A is the direction in which the liquid mainly flows inside the foam generator 100.

[0014] Furthermore, the side of the foam generator 100 from which the liquid flowing inside the foam generator 100 flows out through the tip opening 50h is defined as the "tip side (downstream side) A1" in the axial direction A, and the side opposite to tip side A1 is defined as the "base end side (upstream side) A2" in the axial direction A.

[0015] Furthermore, the direction perpendicular to the axial direction A is defined as the "radial direction R," the side approaching axis O is defined as the "inner R1" in the radial direction R, and the opposite side is defined as the "outer R2" in the radial direction R.

[0016] The first flow path portion 10 includes a proximal end flow path portion 11, a first perforated plate (perforated plate) 12, and a reduced diameter portion 13. The first flow path portion 10 is a portion where liquid can flow from the outside of the bubble generator 100 into the inside of the bubble generator 100. The liquid supplied to the bubble generator 100 may be water, or may be a nutrient solution, a cleaning solution, a coolant solution, or the like.

[0017] The proximal end flow path portion 11 forms a flow path that communicates with a proximal end opening 10h provided on the upstream side A2 of the first flow path portion 10. The proximal end opening 10h is an opening through which liquid can flow from the outside in the bubble generator 100.

[0018] In the present embodiment, the proximal end flow path portion 11 has a cylindrical shape centered on the axis O. The proximal end flow path portion 11 does not necessarily have to be exactly cylindrical. For example, it is formed by a tapered screw that tapers toward the tip side A1 and a cylindrical member.

[0019] The first perforated plate 12 is provided on the downstream side A1 of the proximal end flow path portion 11. The first perforated plate 12 has a plurality of openings 12a, 12b that penetrate the first perforated plate 12 in the axial direction A and through which the liquid flowing from the upstream side A2 to the downstream side A1 of the first perforated plate 12 can pass. The plurality of openings of the first perforated plate 12 include a main opening 12a and sub-openings 12b.

[0020] FIG. 2 is a diagram schematically showing the first perforated plate 12. FIG. 2 is a view of the first perforated plate 12 seen from the axial direction A. In the present embodiment, the first perforated plate 12 has a main opening 12a and eight sub-openings 12b.

[0021] The main opening 12a is, for example, a circular opening centered on the axis O. In the present embodiment, the main opening 12a is an opening provided at the center of the first perforated plate 12, which is a plate material having a circular shape when viewed from the axial direction A.

[0022] The sub-openings 12b are arranged to surround the main opening 12a when viewed from the axial direction A. In this embodiment, the first opening plate 12 is provided with eight sub-openings 12b arranged at equal intervals around the main opening 12a around the axis O. Furthermore, the radial distance R from the axis O to each sub-opening 12b is equal to one another.

[0023] The number and arrangement of the sub-holes 12b are not limited to those described above. In this embodiment, the sub-holes 12b have a smaller diameter than the main holes 12a.

[0024] The diameter-reducing section 13 is provided on the downstream side A1 of the first open plate 12 and its diameter decreases toward the downstream side A1. Preferably, the diameter-reducing section 13 communicates with all of the multiple openings 12a and 12b provided in the first open plate 12. The gas inlet section 20 will be described later.

[0025] The second flow channel section 30 comprises a small-diameter section 31, an enlarged-diameter section 32, and a constricted section 33. The second flow channel section 30 is connected to the downstream side A1 of the first flow channel section 10. Liquid can flow into the second flow channel section 30 from the first flow channel section 10.

[0026] The small-diameter portion 31 is connected to the downstream side A1 of the reduced-diameter portion 13 and communicates with the opening of the downstream side A1 of the reduced-diameter portion 13. In this embodiment, the diameter of the small-diameter portion 31 is equivalent to the diameter of the opening of the downstream side A1 of the reduced-diameter portion 13. Furthermore, the small-diameter portion 31 has a generally constant size in the axial direction A.

[0027] The enlarged diameter section 32 is connected to the downstream side A1 of the small diameter section 31 and communicates with the opening A1 on the downstream side of the small diameter section 31. The enlarged diameter section 32 expands in diameter toward the downstream side A1. In this embodiment, the diameter of the opening A2 on the upstream side of the enlarged diameter section 32 is the same as the diameter of the opening A1 on the downstream side of the reduced diameter section 13.

[0028] The narrowed diameter section 13 of the first flow path section 10 and the widened diameter section 32 of the second flow path section 30 are connected to the gas inlet section 20, respectively.

[0029] The gas inlet 20 is a part of the foam generator 100 that can mix a gas such as oxygen with the liquid flowing inside the foam generator 100. The gas supplied from the gas inlet 20 to the foam generator 100 may be oxygen, air, nitrogen, carbon dioxide, etc. The gas inlet 20 comprises a gas flow path 21 and a gas inlet pipe 22.

[0030] The gas flow path 21 forms a flow path that extends radially R, for example, and communicates with a gas inlet 20h provided on the outside R2 of the gas flow path 21. The gas inlet 20h is an opening in the bubble generator 100 that allows gas to flow in from the outside.

[0031] The gas inlet pipe 22 connects the gas flow path 21 to the first flow path section 10 and the second flow path section 30, respectively. In this embodiment, the gas inlet section 20 has a plurality of gas inlet pipes 22.

[0032] Figure 3 is a schematic diagram of the gas inlet pipe 22. Figure 3 is a view of the gas inlet pipe 22 from the inside R1.

[0033] As shown in Figure 1, the gas inlet 20 is provided on the outer R2 of the small-diameter portion 31. The small-diameter portion 31 shown in Figure 3 is the surface of the small-diameter portion 31 facing the gas inlet 20. As shown in Figure 3, at least a portion of the surface of the small-diameter portion 31 facing the gas inlet 20 is surrounded by a portion of the reduced-diameter portion 13 and a portion of the enlarged-diameter portion 32.

[0034] The inner opening R1 of the gas inlet pipe 22 communicates with the reduced diameter section 13 and the expanded diameter section 32, respectively. In this embodiment, the gas inlet section 20 has eight gas inlet pipes 22. For example, of the eight gas inlet pipes 22, four gas inlet pipes 22 connect the gas flow path 21 to the reduced diameter section 13, and four gas inlet pipes 22 connect the gas flow path 21 to the expanded diameter section 32.

[0035] The throttling portion 33 is provided in the internal space of the enlarged diameter portion 32. In this embodiment, the throttling portion 33 is a cylindrical member with axis O as its central axis. As shown in Figure 1, the throttling portion 33 is provided downstream A1 of the gas inlet pipe 22 connected to the enlarged diameter portion 32.

[0036] An annular gap is provided between the outer circumferential surface of the constricted portion 33 and the inner circumferential surface of the enlarged diameter portion 32. When the liquid flows through the enlarged diameter portion 32 from the upstream side A2 to the downstream side A1, the liquid flows into the gap (flow channel) formed between the outer circumferential surface of the constricted portion 33 and the inner circumferential surface of the enlarged diameter portion 32 when it reaches the position where the constricted portion 33 is located.

[0037] When the enlarged portion 32 is frustoconical and the constricted portion 33 is cylindrical, a ring-shaped flow path is formed between the inner circumferential surface of the enlarged portion 32 and the constricted portion 33. The liquid flowing from the upstream side A2 to the downstream side A1 through the second flow path 30 passes through the small-diameter portion 31, then through the flow path that enlarges towards the downstream side A1 formed by the enlarged portion 32, and flows into the flow path that is constricted into an annular shape by the constricted portion 33.

[0038] In the following explanation, the ring-shaped flow path formed between the inner circumferential surface of the enlarged diameter portion 32 and the constricted portion 33 will also be referred to as the first annular flow path (annular flow path).

[0039] The third flow channel section 40 comprises a large-diameter section 41, a shaft member 42, and a second open plate (open plate) 43. The third flow channel section 40 is connected to the downstream side A1 of the second flow channel section 30. Liquid can flow into the interior of the third flow channel section 40 from the second flow channel section 30.

[0040] The large-diameter portion 41 is connected to the downstream side A1 of the enlarged diameter portion 32 and communicates with the opening of the downstream side A1 of the enlarged diameter portion 32. In this embodiment, the diameter of the large-diameter portion 41 is equivalent to the diameter of the opening of the downstream side A1 of the enlarged diameter portion 32. Furthermore, the large-diameter portion 41 has a generally constant size in the axial direction A.

[0041] The shaft member 42 is provided in the internal space of the large-diameter portion 41. In this embodiment, the shaft member 42 is a cylindrical member with the shaft O as its central axis. As shown in Figure 1, the shaft member 42 is connected to the downstream side A1 of the constricted portion 33.

[0042] In the axial direction A, the dimensions of the large-diameter portion 41 and the dimensions of the shaft member 42 are equivalent. However, the dimensions of the large-diameter portion 41 and the dimensions of the shaft member 42 do not need to be exactly the same. An annular gap is provided between the outer circumferential surface of the shaft member 42 and the inner circumferential surface of the large-diameter portion 41.

[0043] The liquid flowing from the upstream side A2 to the downstream side A1 through the large-diameter section 41 flows through the gap (flow channel) formed between the outer circumferential surface of the shaft member 42 and the inner circumferential surface of the large-diameter section 41.

[0044] When the large-diameter portion 41 is cylindrical and the shaft member 42 is columnar, a ring-shaped flow path is formed between the inner circumferential surface of the large-diameter portion 41 and the shaft member 42.

[0045] In the following explanation, the ring-shaped flow path formed between the inner circumferential surface of the large-diameter portion 41 and the shaft member 42 will also be referred to as the second annular flow path (annular flow path).

[0046] Here, the diameter of the shaft member 42 is smaller than the diameter of the constricted portion 33. Therefore, in the radial direction R, the area of ​​the second annular flow path is larger than the area of ​​the first annular flow path described above.

[0047] The second perforated plate 43 is provided on the downstream side A1 of the shaft member 42 and the large diameter portion 41. The second perforated plate 43 has a plurality of small openings 43a that penetrate the second perforated plate 43 in the axial direction A and communicate with the large diameter portion 41. Preferably, the large diameter portion 41 communicates with all of the plurality of small openings 43a provided in the second perforated plate 43.

[0048] Figure 4 is a schematic diagram of the second perforated plate 43. Figure 4 is a view of the second perforated plate 43 from the upstream side A2. In this embodiment, the second perforated plate 43 has 12 small openings 43a.

[0049] In this embodiment, as shown in Figure 4, the twelve small openings 43a are arranged at equal intervals around the axis O, and the radial distance R from the axis O to each small opening 43a is equal to one another. Furthermore, the small openings 43a are provided outside R2 of the axis member 42. Preferably, the small openings 43a are provided outside R2 of the constricted portion 33.

[0050] The fourth channel section 50 comprises a downstream diameter-reducing section 51, a protruding section 52, and a tip channel section 53. The fourth channel section 50 is connected to the downstream side A1 of the third channel section 40. Liquid can flow into the interior of the fourth channel section 50 from the third channel section 40.

[0051] The downstream diameter-reducing portion 51 is provided on the downstream side A1 of the second open plate 43 and communicates with a plurality of small openings 43a provided in the second open plate 43. Preferably, the downstream diameter-reducing portion 51 communicates with all of the plurality of small openings 43a provided in the second open plate 43. The downstream diameter-reducing portion 51 is reduced in diameter toward the downstream side A1. The protruding portion 52 will be described later.

[0052] The tip channel section 53 is connected to the downstream side A1 of the downstream diameter reduction section 51 and communicates with the opening of the downstream side A1 of the downstream diameter reduction section 51. In this embodiment, the tip channel section 53 has a substantially constant size in the axial direction A.

[0053] The protruding portion 52 is a part that protrudes inward R1 at the boundary between the downstream diameter-reducing portion 51 and the tip flow channel portion 53. The flow channel formed in the fourth flow channel portion 50 has its radial area R narrowed by the protruding portion 52 at the boundary between the downstream diameter-reducing portion 51 and the tip flow channel portion 53.

[0054] The tip channel section 53 communicates with the tip opening 50h provided on the downstream side A1 of the fourth channel section 50. The tip opening 50h is an opening that allows liquid to flow out from inside the foam generator 100 to outside the foam generator 100.

[0055] In this way, the foam generator 100 has flow channels formed inside by the first flow channel section 10, the second flow channel section 30, the third flow channel section 40, and the fourth flow channel section 50, through which liquid can flow. The flow channels formed in the foam generator 100 communicate with the outside of the foam generator 100 through the base end opening 10h on the upstream side A2 and the tip opening 50h on the downstream side A1.

[0056] Next, the operation of the foam generator 100 will be described. The operation of the foam generator 100, as described below, involves flowing a liquid such as water through a channel formed in the foam generator 100 and mixing a gas such as oxygen with the liquid flowing inside the foam generator 100 to generate fine bubbles.

[0057] In this embodiment, microbubbles are, for example, fine bubbles. Fine bubbles are microbubbles with a diameter of less than 100 μm that are mixed in a liquid. For example, microbubbles with a diameter of 1 μm or more and less than 100 μm are called microbubbles, and microbubbles with a diameter of less than 1 μm are called ultrafine bubbles.

[0058] First, liquid is introduced into the foam generator 100. Specifically, liquid is introduced from the base end opening 10h into the channel formed in the first channel section 10.

[0059] At this time, liquid flows from the base end opening 10h into the base end flow channel 11. The liquid that flows into the base end flow channel 11 flows from the upstream side A2 to the downstream side A1 and flows into the multiple openings 12a and 12b provided in the first open plate 12.

[0060] The first perforated plate 12 has a main opening 12a located in the center of the first perforated plate 12, and a plurality of sub-openings 12b arranged at equal intervals around axis O, surrounding the main opening 12a. Liquid flows into the main opening 12a and the plurality of sub-openings 12b.

[0061] The liquid that passes through the main opening 12a and the multiple sub-openings 12b flows into the constricted diameter section 13. The liquid that flows into the constricted diameter section 13 from the main opening 12a flows mainly in the axial direction A. The liquid that flows into the constricted diameter section 13 from the sub-openings 12b flows along the inner circumferential surface of the constricted diameter section 13 toward the inner side R1 and the downstream side A1. As a result, vortices are generated in the liquid flowing through the constricted diameter section 13.

[0062] Furthermore, gas flows into the first flow path section 10 from the gas inlet section 20. Specifically, gas flows into the narrowed diameter section 13 from the gas inlet pipe 22. The gas flowing into the narrowed diameter section 13 flows into the gas flow path 21 from the gas inlet 20h, and then flows into the narrowed diameter section 13 through the gas inlet pipe 22 which connects the gas flow path 21 and the narrowed diameter section 13.

[0063] In the narrowed diameter section 13, by adding gas to the liquid where a vortex is generated, the gas can be stirred within the liquid, causing it to become finer and promoting its dissolution in the liquid. In the following description, a fluid in which liquid and gas are mixed will be referred to as a gas-liquid mixed fluid.

[0064] The gas-liquid mixed fluid generated by the mixing of liquid and gas in the narrowed diameter section 13 flows from the first flow path section 10 into the second flow path section 30. Specifically, the gas-liquid mixed fluid flows from the narrowed diameter section 13 into the small diameter section 31.

[0065] Here, since the reduced diameter section 13 is reduced in diameter toward the downstream side A1, the area of ​​the flow path through which the gas-liquid mixed fluid flows gradually narrows in the radial direction R from the reduced diameter section 13 to the small diameter section 31.

[0066] Therefore, the pressure of the gas-liquid mixed fluid decreases as it flows from the reduced-diameter section 13 to the small-diameter section 31. At this time, bubbles are generated and expand in the gas-liquid mixed fluid due to the gas mixed in the liquid.

[0067] Next, the gas-liquid mixed fluid flows from the small-diameter section 31 into the widened-diameter section 32. Here, since the widened-diameter section 32 widens toward the downstream side A1, the area of ​​the flow path through which the gas-liquid mixed fluid flows gradually increases in the radial direction R from the small-diameter section 31 to the widened-diameter section 32.

[0068] Therefore, as the gas-liquid mixed fluid flows from the small-diameter section 31 to the wide-diameter section 32, the pressure that was reduced by flowing from the narrow-diameter section 13 to the small-diameter section 31 is restored. At this time, the gas bubbles contained in the gas-liquid mixed fluid collapse and become finer.

[0069] Furthermore, gas flows into the enlarged diameter section 32 from the gas inlet pipe 22. The gas flowing into the enlarged diameter section 32 flows into the gas flow path 21 from the gas inlet 20h, and then flows into the enlarged diameter section 32 through the gas inlet pipe 22, which connects the gas flow path 21 and the enlarged diameter section 32.

[0070] By supplying additional gas to the gas-liquid mixed fluid at the enlarged diameter section 32, the gas-liquid mixed fluid that flows from the small diameter section 31 to the enlarged diameter section 32 and the gas supplied at the enlarged diameter section 32 are agitated.

[0071] After additional gas is supplied to the gas-liquid mixed fluid in the enlarged diameter section 32, it flows into the flow path of the first annular channel formed between the constricted section 33 and the inner circumferential surface of the enlarged diameter section 32. In the enlarged diameter section 32, the pressure of the gas-liquid mixed fluid decreases as it flows into the first annular channel.

[0072] Next, the gas-liquid mixed fluid flows from the first annular channel into the third channel section 40. The gas-liquid mixed fluid that has flowed into the third channel section 40 flows into the second annular channel formed between the shaft member 42 and the inner circumferential surface of the large-diameter section 41.

[0073] In the radial direction R, the area of ​​the second annular channel is larger than the area of ​​the first annular channel. Therefore, the gas-liquid mixed fluid recovers pressure as it flows from the first annular channel into the second annular channel. At this time, the bubbles contained in the gas-liquid mixed fluid collapse and become finer. In addition, vortices are generated in the gas-liquid mixed fluid flowing through the second annular channel, and the bubbles contained in the gas-liquid mixed fluid are stirred.

[0074] Next, the gas-liquid mixed fluid flows from the second annular channel of the large-diameter section 41 through a plurality of small openings 43a provided in the second open plate 43 into the fourth channel section 50. Specifically, the gas-liquid mixed fluid flows from the small openings 43a into the downstream reduced-diameter section 51.

[0075] In the gas-liquid mixed fluid flowing downstream A1 through the downstream diameter-reduced section 51, the gas-liquid mixed fluid flowing inside R1 relative to the protrusion 52 mainly flows in the axial direction A. Furthermore, around the area where the gas-liquid mixed fluid mainly flows in the axial direction A, vortices are generated as the gas-liquid mixed fluid collides with the protrusion 52, promoting the miniaturization of bubbles contained in the gas-liquid mixed fluid.

[0076] The gas-liquid mixed fluid, whose bubbles have been refined in the downstream diameter-reducing section 51, flows into the tip channel section 53 and flows out of the bubble generator 100 from the tip opening 50h on the downstream side A1 of the tip channel section 53.

[0077] Thus, the liquid flowing inside the foam generator 100 becomes a gas-liquid mixed fluid when gas flows in from the gas inlet 20. Furthermore, the gas-liquid mixed fluid flowing inside the foam generator 100 becomes a gas-liquid mixed fluid containing fine bubbles as the bubbles are repeatedly refined.

[0078] The microbubbles generated by the bubble generator 100 are, for example, ultrafine bubbles with a diameter of less than 1 μm. By using the bubble generator 100, a gas-liquid mixed fluid containing ultrafine bubbles (for example, ultrafine bubble water) can be produced.

[0079] The foam generator 100 of this embodiment includes a first flow channel section 10 having a base end opening 10h into which liquid can flow from the outside; a second flow channel section 30 connected to the downstream side A1 of the first flow channel section 10 and into which liquid can flow from the first flow channel section 10; a gas inlet section 20 connected to the first flow channel section 10 and the second flow channel section 30, respectively, and into which gas can flow in the first flow channel section 10 and the second flow channel section 30; and a third flow channel section 40 connected to the downstream side A1 of the second flow channel section 30 and into which liquid can flow from the second flow channel section 30.

[0080] The first flow channel section 10 includes an open plate (first open plate) 12 having a plurality of openings 12a, 12b into which liquid can flow, and a diameter-reducing section 13 provided on the downstream side A1 of the open plate 12 and reducing in diameter toward the downstream side A1.

[0081] The second flow channel section 30 has an enlarged diameter section 32 that widens toward the downstream side A1, and a constricted section 33 that forms an annular flow channel (first annular flow channel) along the inner circumferential surface of the enlarged diameter section 32. The third flow channel section 40 has a flow channel (second annular flow channel) that is wider than the annular flow channel (first annular flow channel) formed by the constricted section 33.

[0082] With a bubble generator 100 configured in this way, gas is supplied to the first flow channel 10 and the second flow channel 30 to generate a gas-liquid mixed fluid. Furthermore, the expansion section 32, the first annular flow channel, and the second annular flow channel repeatedly accelerate and decelerate the flow velocity of the gas-liquid mixed fluid, thereby repeatedly expanding and bursting the bubbles in the gas-liquid mixed fluid. In addition, the opening plate 12, the reduction section 13, the first annular flow channel, and the second annular flow channel generate vortices in the gas-liquid mixed fluid, which can stir the bubbles contained in the gas-liquid mixed fluid.

[0083] As a result, the bubble generator 100 can generate microbubbles (e.g., ultrafine bubbles) with a sufficient particle number concentration (number of microbubbles per unit volume of gas-liquid mixed fluid).

[0084] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the spirit of the present invention are also included. Furthermore, the components shown in the above-described embodiment and the following modifications can be combined as appropriate.

[0085] (Variation 1) In the above embodiment, the fourth channel section 50 includes a downstream diameter reduction section 51, a protruding section 52, and a tip channel section 53, but the configuration of the fourth channel section is not limited thereto. The fourth channel section may, for example, include a foam core.

[0086] In the fourth flow channel section, the foam core is provided, for example, in the internal space of the downstream diameter reduction section 51. The foam core is an agitation unit having multiple openings through which liquid can pass, and capable of agitating bubbles contained in the liquid (gas-liquid mixed fluid). The foam core is also called a foam plug.

[0087] When the fourth flow channel is equipped with a foam core, the gas-liquid mixed fluid that flows into the fourth flow channel from the small opening 43a is discharged downstream to A1 through the foam core. At this time, at A1 downstream of the foam core, at least a portion of the gas-liquid mixed fluid is recovered to A2 upstream by the negative pressure generated around the main flow in the gas-liquid mixed fluid, and then discharged again downstream to A1 through the foam core. This promotes the miniaturization of bubbles contained in the gas-liquid mixed fluid.

[0088] (Modification 2) In the above embodiment, the first perforated plate 12 has one main perforation 12a and eight sub-perforations 12b, but the configuration of the first perforated plate is not limited thereto.

[0089] The first perforated plate may have a plurality of main perforations, or it may have fewer than eight or nine or more secondary perforations. The diameters of the main perforations and the secondary perforations may be equal, or the diameter of the main perforations may be smaller than the diameter of the secondary perforations. Furthermore, the shape of the perforations (main perforations, secondary perforations) in the first perforated plate is not particularly limited; they may be round (circular) or polygonal.

[0090] (Variation 3) In the above embodiment, the gas inlet section 20 has eight gas inlet pipes 22, of which four gas inlet pipes 22 connect the gas flow path 21 to the narrowed diameter section 13, and four gas inlet pipes 22 connect the gas flow path 21 to the widened diameter section 32. However, the configuration of the gas inlet section is not limited to this.

[0091] The number of gas inlet pipes in the gas inlet section may be less than eight or nine or more. Furthermore, the number of gas inlet pipes connecting the gas flow path to the narrowed diameter section and the number of gas inlet pipes connecting the gas flow path to the widened diameter section may be different from each other.

[0092] (Modification 4) In the above embodiment, the second perforated plate 43 has 12 small holes 43a, but the configuration of the second perforated plate is not limited thereto.

[0093] The number of small openings in the second perforated plate may be less than 12 or 13 or more. Furthermore, the small openings do not have to be equally spaced around axis O, and may be located inside R1 beyond the throttling portion. Also, the shape of the small openings in the second perforated plate is not particularly limited; they may be round (circular) or polygonal.

[0094] The present invention will be described in detail with reference to the following examples. The present invention is not limited to the following examples.

[0095] (Examples) In the embodiment, a gas-liquid mixed fluid containing fine bubbles was generated using the bubble generator 100 of the above embodiment. The conditions for generating the fine bubbles were as follows.

[0096] The liquid used to produce the gas-liquid mixed fluid was water. The gas used to mix with the water to produce the gas-liquid mixed fluid was dry air.

[0097] The tank capacity was set to 8.8L. The tank capacity refers to the amount of water contained in the tank that supplies water to the bubble generator 100.

[0098] The water circulation time was set to 20 minutes. The water circulation time is the time during which the water in the water tank is circulated inside the bubble generator 100, with the inlet (base opening 10h) and outlet (tip opening 50h) of the bubble generator 100 connected to the water tank, respectively.

[0099] The water flow rate was set to 8.0 L / min. The water flow rate is the amount (L) of water supplied to the foam generator 100 per unit time (min).

[0100] The gas flow rate was set to 3.0 L / min. The gas flow rate is the amount (L) of dry air supplied to the foam generator 100 per unit time (min). The gas pressure of the dry air supplied to the foam generator 100 was set to 0.05 MPa.

[0101] The gas supply time was set to 20 minutes. The gas supply time is the time during which dry air was supplied to the water flowing through the internal space of the foam generator 100.

[0102] (Comparative Example 1) In Comparative Example 1, a gas-liquid mixed fluid containing fine bubbles was generated using the mixer section of a conventional gas heater. In this case, water was flowed through the channel through which oxygen flows when using a conventional gas heater, and dry air was flowed through the channel through which fuel gas flows, thereby mixing the water and dry air.

[0103] In Comparative Example 1, the conditions for generating microbubbles were the same as in the Example, except for the water flow rate. The water flow rate in Comparative Example 1 was set to the flow rate that could be processed by the mixer section of the conventional gas heater used in Comparative Example 1.

[0104] (Comparative Example 2) In Comparative Example 2, a gas-liquid mixed fluid containing microbubbles was generated using a conventional nozzle commercially available as a nozzle capable of generating ultrafine bubbles.

[0105] The nozzle used in Comparative Example 2 was a general-purpose bubble-generating nozzle equipped with a gas supply unit, with a discharge rate of 10 L / min. The conditions for generating fine bubbles in Comparative Example 2 were the same as those in the Example.

[0106] (Comparative Example 3) In Comparative Example 3, a gas-liquid mixed fluid containing microbubbles was generated using a commercially available adapter for a fully automatic washing machine that is capable of generating ultrafine bubbles.

[0107] The adapter used in Comparative Example 3 generates microbubbles using a method called cavitation. This method generates a swirling flow in the water passing through the adapter, causing the air contained in the water to turn into bubbles, thereby generating microbubbles.

[0108] Therefore, when generating microbubbles with the adapter of Comparative Example 3, the supply of dry air is unnecessary. Accordingly, in the microbubble generation conditions of Comparative Example 3, the generation conditions other than the gas flow rate and gas pressure were the same as those of the example.

[0109] (experiment) Using the above-described examples and Comparative Examples 1-3, a gas-liquid mixed fluid containing ultrafine bubbles was generated, and the particle number concentration (bubbles / mL) of the generated gas-liquid mixed fluid was measured.

[0110] Furthermore, the water treatment rate (L / min) for the Examples and Comparative Examples 1-3 was measured. The water treatment rate represents the amount (L) of the gas-liquid mixed fluid containing ultrafine bubbles produced by the Examples and Comparative Examples 1-3 under the above production conditions, per unit time (min).

[0111] (Experimental results) Figure 5 is a graph showing the results of particle number concentration measurements in the experiment described above.

[0112] When ultrafine bubbles were generated using the bubble generator 100 of the example, the particle number concentration of the ultrafine bubbles was 82,800,000 particles / mL. The water treatment rate at this time was 8.2 L / min.

[0113] When ultrafine bubbles were generated using the mixer section of Comparative Example 1, the particle number concentration of the ultrafine bubbles was 56,000,000 particles / mL. The water treatment rate at this time was 1.3 L / min.

[0114] When ultrafine bubbles were generated using the nozzle of Comparative Example 2, the particle number concentration of the ultrafine bubbles was 62,700,000 particles / mL. The water treatment rate at this time was 8.0 L / min.

[0115] When ultrafine bubbles were generated using the adapter of Comparative Example 3, the particle number concentration of the ultrafine bubbles was 37,600,000 particles / mL. The water treatment rate at this time was 8.0 L / min.

[0116] As shown in Figure 5, the bubble generator 100 of the example was able to generate ultrafine bubbles with a higher particle number concentration than Comparative Examples 1-3.

[0117] Furthermore, the bubble generator 100 of the example was able to generate a gas-liquid mixed fluid containing ultrafine bubbles with a larger water treatment volume than Comparative Examples 1-3.

[0118] Thus, the bubble generator 100 of the embodiment can generate fine bubbles (in this case, ultrafine bubbles) with a sufficient particle number concentration, and furthermore, can produce a gas-liquid mixed fluid containing fine bubbles with a sufficient amount of water treatment. [Explanation of symbols]

[0119] 100 Foam Generator 10 First flow channel 10h Proximal opening 11 Proximal channel section 12 Perforated plate (first perforated plate) 12a Main hole (hole) 12b Sub-hole (hole) 13 Reduced diameter part 20 Gas inlet 22 Gas inlet pipe 30 Second flow path section 31 Small diameter section 32 Expanded diameter part 33 Aperture section 40 Third flow path section 42 Shaft member 43a Small hole 50 Fourth flow path section O Center axis (axis) Axis (flow direction) A1 Tip side (downstream side) A2 Proximal side (upstream side) R radial direction

Claims

1. A foam generator having a flow path through which liquid flows from the upstream side to the downstream side, A first channel section having a base end opening into which the liquid can flow in from the outside, A second flow channel is connected to the downstream side of the first flow channel and into which the liquid can flow from the first flow channel, A gas inlet is connected to the first flow channel and the second flow channel, respectively, and into which gas can be introduced into the first flow channel and the second flow channel, A third flow channel is connected to the downstream side of the second flow channel and into which the liquid can flow from the second flow channel, Equipped with, The first flow channel section comprises an open plate having a plurality of openings into which the liquid can flow, and a diameter-reducing section provided on the downstream side of the open plate and decreasing in diameter toward the downstream side. The second flow channel section has an enlarged diameter section that widens toward the downstream side, and a constricted section that forms an annular flow channel along the inner circumferential surface of the enlarged diameter section. The third flow channel has a wider flow channel than the annular flow channel formed by the constricted portion. Foam generator.

2. The first flow channel section has a base end flow channel section through which the liquid flowing in from the base end opening flows, The perforated plate is provided on the downstream side of the base end flow channel portion, The opening in the aforementioned opening plate has a smaller diameter than the base end flow channel portion. The foam generator according to claim 1.

3. The opening in the perforated plate includes a main opening provided on the central axis of the base end flow channel and a plurality of sub-openings provided surrounding the main opening when viewed from the axial direction in which the central axis extends. The aforementioned secondary opening has a smaller diameter than the aforementioned main opening. The foam generator according to claim 2.

4. The second flow channel section has a small diameter section that connects the downstream opening of the reduced diameter section with the upstream opening of the enlarged diameter section. The foam generator according to claim 3.

5. The gas inlet section has a gas inlet pipe into which the gas can be introduced into the reduced diameter section and the expanded diameter section, respectively. The foam generator according to claim 4.

6. The aforementioned throttling portion is provided on the central axis and downstream of the gas inlet pipe. The foam generator according to claim 5.

7. The third flow channel section is connected to the downstream side of the constricted section and has a shaft member whose radial dimension intersecting the axial direction is smaller than that of the constricted section. The foam generator according to claim 6.

8. The third flow channel is provided on the downstream side of the shaft member and surrounding the central axis when viewed from the axial direction, and has a small opening into which the liquid can flow. The foam generator according to claim 7.

9. The third channel section is connected to the downstream side and comprises a fourth channel section in which a foam core is provided. A foam generator according to any one of claims 1 to 8.

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