JP2013000626A - Fine air bubble generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a conventional microbubble generator or minute air bubble generator makes rotation in a water flow inside a cylinder and generates fine air bubbles in the water flow by catching air sucked therein, and in this case it is likely that excessive energy is consumed for rotation of water or a flow is impeded.SOLUTION: Contrary to the conventional device, the water flow is travelled straight, and a flow of air caught in it is rotated to generate the fine air bubbles in the water flow. This has an advantage of requiring less energy in rotating the air flow as compared with the water flow. That is, an inflow passage in which a pressurized liquid passes is narrowed in the middle to have a cone shape, and an insertion member is inserted therein so that a clearance between a tapered part outer wall of the insertion member and an inner wall of the cone-shaped part serves as a distribution passage of gas sucked from a gas inflow passage. The gas is mixed with a high-speed liquid ahead of the insertion member while swirling when passing through the distribution passage to be turned into the fine air bubbles, and is emitted from a discharge passage at high speed.

Description

  The present invention relates to a microbubble generator having a very simple structure for generating microbubbles, micro / nanobubbles or nanobubble-class microbubbles in a liquid, and in particular, lake water, seawater, swamp water, bath water, etc. It is related to things suitable for water purification.

  Conventionally, many devices for generating fine bubbles in water, such as microbubble generators and microbubble generators, have been filed. Many of these are those that cause rotation of the water flow in the cylinder and entrain the air sucked into the water flow to generate fine bubbles in the water flow. In this case, there is a possibility that excessive energy is consumed or the flow is obstructed by the rotation of water.

  On the other hand, a microbubble generator of a type in which the water stream goes straight has also been proposed (Patent Document 1, Patent Document 2). However, in the case of Patent Document 1, air is discharged from the ring slit, and it is doubtful whether water and bubbles are sufficiently mixed. In addition, in the case of Patent Document 2, the air suction groove is formed in the direction of contact with the flowing water passage in the nozzle member. In addition, since the whole is welded, it is difficult to disassemble, and after one year, there is a defect that fine bubbles are hardly generated due to clogging.

  That is, in order to generate and contain fine bubbles in the water flow flowing in the cylinder, in general, gas is entrained in the rotating flow (vortex) of water, and the vortex is stopped. It is said that it is necessary to say that the generated gas is diffused. An important point is how to entrain gas in the vortex. This is the method employed by most conventional microbubble generators.

Japanese Patent No. 3968737 JP 2008-23513 A

  In the present invention, contrary to the above, the water flow advances straight, and the flow of air entrained in the water flow is rotated to generate fine bubbles in the water flow. Gas spin requires less energy than liquid rotation, and has the advantage of generating fine bubbles more efficiently.

  The present invention has been made from such a point of view. The gas is sucked by using the suction force of the liquid (direct current) flowing through the cylinder, and swirled while the gas passes through the narrow mortar-shaped gap, or swirled. The rotation of the gas flow is actively caused by using a plate, a spiral groove or a ridge, and mixed with the liquid to generate fine bubbles. Since the gap is not a hole but a slit, clogging due to dust is less likely to occur. Further, unlike Patent Document 2, the amount of gas mixed in water is large, and there is an advantage that a large amount of fine bubbles are generated. In addition, even if clogged, it can be easily disassembled, so that it is easy to repair.

  Since the liquid is mainly water and the gas is mainly air, hereinafter, the liquid may be described as water and the gas may be described as air. The gas often uses ozone or carbon monoxide for sterilization. The water may be clean water, river water, free water in a port, aquaculture pond, reservoir, garden pond, water in a closed water area such as a lake, or any water such as a bath or hot spring. However, it is necessary to remove dust before suction.

  The microbubble generator of the present invention has no noise generating part in principle, and the mechanical operating part is only a land pump or a submersible pump, and is not affected by fluctuations in the amount of water or water level, and the efficiency of oxygen transfer from air to water There is an advantage that the amount of air is small and high. A pump having a lift of about 25 m and a pressure of about 0.15 to 0.3 Mpa is sufficient.

  The basic structure of the fine bubble generating device of the present invention includes an inflow path through which pressurized liquid passes, a gas inflow path for high-speed suction of gas, and a discharge path for discharging liquid containing fine bubbles at high speed. At the same time, the middle of the inflow path is narrowed into a bowl shape, and an insertion member is inserted into the bowl portion. The outer wall of the insertion member has the same taper as the inner wall of the mortar part, and has a dimension away from the inner wall by a predetermined distance. The inner surface of the insertion member is shaped like a mortar and serves as a liquid flow path. The gap between the outer wall of the tapered portion of the insertion member and the inner wall of the scallop portion serves as a flow path for the gas sucked from the gas inflow path. The gas is mixed with the high-speed liquid around the throat or in front of the protrusion from the protrusion of the insertion member while swirling while passing through the gas flow passage to form fine bubbles, and is discharged from the discharge path at high speed. The discharge path is composed of a diffuser and a nozzle.

  Such a simple structure is easy to maintain and inspect, and has the advantage of being inexpensive and miniaturized. In addition, pressurized water is fed in a large amount by a pipe with an inner diameter of 3.3 cm or another pipe with a larger inner diameter, and is sent in a straight line, so that it can be ejected 7 m to 10 m or more away from the discharge path. The oxygen inside can be sufficiently diffused in water.

  The angle (θ in FIG. 1A) of the scalloped portion or the constricted portion of the insertion member is 60 ° to 120 °, and more preferably 70 ° to 100 °.

  The main body portion (main body portion including the inflow path, the gas inflow path, and the discharge path) of the fine bubble generator can be formed by plastic extrusion, metal cutting, or plastic cutting. However, extrusion molding is not suitable because the mold cost is not so large. In addition, when the gas is ozone, it corrodes if it is a metal other than titanium, so that most preferable is cutting out plastic, and in particular cutting out Teflon resin (polytetrafluoroethylene resin, registered trademark of DuPont). However, there is a concern about wear due to the use of plastic. In this case, it is preferable to use titanium cutting. In the case of cutting, there is an advantage that the diameter and length of the inflow channel can be freely adjusted.

  A flange is attached to both sides of the main body, and the flange of the insertion member is pressed with one flange, and the flange of the diffuser is pressed with the other flange. A packing is attached inside each flange. Each flange is assembled with four bolts and nuts to assemble the main body. The inflow path is formed by inserting a pipe into the hole of one flange, and liquid is pressed into the pipe from a submersible pump or a land pump. The discharge path 4 is composed of a diffuser. A nozzle is attached to the outside of the diffuser, and a liquid containing fine bubbles is discharged from the nozzle at a high speed. In addition, the inner surface of the diffuser has a gentle spreading slope toward the front.

  If the inner diameter of the diffuser is parallel or expands about 3 ° toward the front (the direction in which the liquid flows), the discharge of the liquid R2 is not very successful. If it is even more constricted, clogging will occur and release will not be successful. According to the experiments by the present inventors, the spread angle (α in FIGS. 4 (a) and 5 (a)) is about 6 °, that is, the emission is 6 ° ± 0.1 to 0.2 °. Can do the most skillful. If the angle is more than 10 °, it is not released well.

  If a swirl plate or a spiral groove or protrusion is provided on the outer wall of the taper portion of the insertion member, the swirling flow can be positively caused in the gas sucked from the gas inflow path 3, and the high-speed liquid and fine Mixing with bubbles is more powerful. The size of the gas flow passage 7, that is, the size of the gap between the outer wall of the tapered portion of the insertion member and the inner wall of the mortar portion is preferably about 1.0 to 1.5 mm. The size of the gap is preferably about 1.0 to 2.5 mm. The thickness of the swivel plate and the spiral ridge is also about 1.0 to 2.5 mm. In the case of providing a spiral groove, the size of the gap is preferably about 1.0 to 1.5 mm, and the depth of the groove is preferably about 0.5 mm. In the case where a swivel plate or a spiral protrusion or groove is provided, there is a high possibility that finer fine bubbles (nano bubbles, micro / nano bubbles) are generated. When there is no swivel plate, it seems that microbubble class fine bubbles are generated.

  A discharge passage is used as a throat, and a diffuser is provided in front of the throat to discharge liquid containing fine bubbles from the diffuser at a high speed, or a buffer tank is provided in front of the diffuser, and a gas-liquid mixture is supplied in the buffer tank. After the pressure is reduced and the gas (fine bubbles) is pressurized and dissolved, the liquid containing the fine bubbles can be discharged at high speed. Alternatively, if a discharge tank having a discharge passage as a throat and having a large diameter in front of the throat is provided, the flow rate of the mixture of liquid and fine bubbles is reduced in the reaction tank, and the gas (fine bubbles) is dissolved under pressure. As a result, the fine bubbles can be mixed better. In this case, the diffusion tank is connected to a diffuser having a smaller diameter, and a liquid containing fine bubbles is discharged at high speed therefrom. If an orifice having a hole diameter smaller than that of the diffuser is provided between the reaction tank and the diffuser, the bubbles can be further refined. The spreading angle from the throat of the reaction tank (β in FIG. 5B) may be the same as or somewhat wider than θ in FIG. That is, it is 60 ° to 120 °, and more preferably 80 ° to 100 °.

  In any type of fine bubble generating device described above, the gas inflow path opens at a position between the vicinity of the root of the scalloped portion provided in the liquid inflow path and the middle position. The gas is sucked from the gas inflow path by the suction force of the pressurized liquid flowing through the liquid inflow path, and swirls through the gas flow path formed between the outer wall of the tapered portion of the insertion member and the inner wall of the mortar. It is mixed with the high-speed liquid in front of the protruding portion of the insertion member to form fine bubbles, which are discharged at high speed from the discharge path.

  If a valve such as a needle valve or a ball valve is provided in this gas inflow path, the diameter and concentration (number of bubbles) of bubbles generated by adjusting the amount of gas passing through the inflow path can be made variable. it can. In addition, if a check valve is incorporated in the gas inflow path, when the inflow of pressurized liquid stops, liquid containing foreign substances such as dust enters the gas inflow path, and the inflow of pressurized liquid is started. It is possible to prevent the gas passage from being obstructed.

  As described above, the fine bubble generating apparatus of the present invention is configured to cause a water stream to travel straight in the apparatus and rotate the flow of air entrained in the apparatus to generate fine bubbles in the water stream. Therefore, there is an advantage that the air stream requires less energy to rotate than the water stream. In addition, the structure is very simple, can be manufactured easily, can be obtained at low cost, and there are few failures.

An example of this invention microbubble generator is shown, (a) is a longitudinal cross-sectional view of a microbubble generator, (b) is a front view of an insertion member. Example 1 The other example of this invention microbubble generator is shown, (a) is a longitudinal cross-sectional view of a microbubble generator, (b) is a front view of an insertion member. (C) is a front view of a further different insertion member. (Example 2) The modification which has the discharge path which lengthened the length of the discharge path in the microbubble generator of FIG. 1 or FIG. 2 is shown, (a) is a longitudinal cross-sectional view, (b) is explanatory drawing which shows the turning state of gas. It is. (Example 3) It is a longitudinal cross-sectional view of the other example from which this invention microbubble generator differs. Example 4 FIG. 4 shows still another example of the microbubble generator of the present invention, where (a) is a longitudinal sectional view, (b) is a longitudinal sectional view of the same, and is an explanatory diagram of liquid pressure, and (c) is a gas swirling state. It is explanatory drawing. (Example 5)

  It has an inflow path through which pressurized liquid passes, a gas inflow path for high-speed suction of gas, and a discharge path for discharging liquid containing fine bubbles at high speed, and the middle of the inflow path is constricted in a slab shape. Therefore, an insertion member is inserted into the mortar. The gap between the outer wall of the tapered portion of the insertion member and the inner wall of the slab portion becomes a flow path for the gas sucked from the gas inflow path, and the gas swirls while passing through the gas flow path while the insertion member It is mixed with a high-speed liquid in front of the protruding portion to form fine bubbles, which are discharged from the discharge path at high speed.

  FIG. 1 shows an example of a basic fine bubble generating apparatus according to claim 1 of the present invention. FIG. 1 (a) is a longitudinal sectional view of the fine bubble generating apparatus, and FIG. 1 (b) is a front view of an insertion member. It is. This fine bubble generating device 1 includes an inflow passage 2 through which a pressurized liquid R1 passes, a gas inflow passage 3 for sucking the gas K at a high speed, and a discharge passage for discharging the liquid R2 containing the fine bubbles MB at a high speed. 4 is provided. Then, the middle of the inflow path 2 is narrowed into a mortar shape, and the mortar portion 5 has an outer wall portion having the same taper as the inner wall 5a of the mortar portion and a size separated from the inner wall 5a by a predetermined distance. An insertion member (nozzle) 6 having 6b is inserted. The inner surface 6a of the insertion member is shaped like a slab and serves as a flow path for the liquid R1, and a gap between the tapered outer wall 6b of the insertion member 6 and the inner slab part inner wall 5a is formed from the gas inflow passage 3. It becomes the flow path 7 of the gas K to be sucked. The gas K is swirled while passing through the gas flow passage 7 and mixed with the high-speed liquid in front of the protrusion 6 c of the insertion member 6 to form fine bubbles MB, and is discharged from the discharge path 4 at high speed. The discharge path 4 includes a diffuser 8.

  The angle θ of the scalloped portion or the constricted portion of the insertion member is 60 ° to 120 °, and more preferably 70 ° to 90 °. In the case of FIG. 1A, θ is 80 °. Moreover, the internal diameter of the protrusion part 6c is 6-8 mm, and the internal diameter of the beginning of the diffuser 8 is about 10 mm. The inlet of the gas inflow passage has an inner diameter of 10 mm, and the inner diameter of the portion in contact with the insertion member 6 is about 6 mm.

  The main body portion of the microbubble generator 1 can be formed by plastic extrusion, metal cutting, or plastic cutting. However, extrusion molding is not suitable because the mold cost is not so large. In addition, when the gas K is ozone, it corrodes if it is a metal, so that the most preferable is the cutting of plastic, particularly the cutting of Teflon resin (registered trademark) or the cutting of titanium. In the case of cutting out, there is an advantage that the diameter and length of the inflow passage 2 can be freely set.

  The flanges 9 and 10 are attached to both sides of the main body, the flange 9 holds the flange 6d of the insertion member 6, and the flange 10 presses the flange 8a of the diffuser 8. Reference numerals 11 and 12 are packings. Each flange 9, 10 is fastened with four bolts 13 and nuts 13 'to assemble the main body. The inflow path 2 is formed by inserting a pipe 14 into the hole 9 a of the flange 9, and the liquid R 1 is pressed into the pipe 14 from a submersible pump or a land pump P. The discharge path 4 includes a diffuser 8. A nozzle 15 is attached to the outside of the diffuser 8, and the liquid R <b> 2 containing the fine bubbles MB is discharged from the nozzle 15 at a high speed. Note that the inner surface 8b of the diffuser 8 has a gentle spreading inclination (α) toward the front (the direction in which the liquid R1 flows, rightward in the figure).

  FIG. 1B is a front view of the insertion member 6. Reference numeral 6b denotes an outer wall of the tapered portion of the insertion member 6, reference numeral 6c denotes a protruding portion, and reference numeral 6d denotes a flange.

  Next, FIG. 2 shows an example of the fine bubble generator shown in claim 2 of the present invention, wherein (a) is a longitudinal sectional view of the fine bubble generator, and (b) is a front view of the insertion member. This microbubble generator 1 'is provided with a swirl plate 16 that positively causes a swirl flow in the gas K drawn from the gas inflow passage 3 on the outer wall 6'b of the insertion member 6' (FIG. 2 ( 4), the other shapes and dimensions are the same as those of the insertion member 6 in FIG. The configuration other than the insertion member 6 'is the same as that in FIG. The dimension of the gas flow passage 7 is about 1 to 1.5 mm in the case of FIG. 1 and about 1.0 to 2.5 mm in the case of FIG. The thickness of the swivel plate 16 is also about 1.0 to 2.5 mm.

  In the case of the insertion member 6 ′ in FIG. 2B, the gas K is forcibly swirled while passing through the gas flow passage 7 by the swivel plate 16, and high-speed in front of the protrusion 6 ′ c of the insertion member 6 ′. It is mixed with the liquid to form fine bubbles MB, and is discharged from the discharge path 4 at a high speed. In addition, in the case of the insertion member 6 ″ shown in FIG. 2 (c), a spiral groove 16 ′ or a protrusion is provided on the taper portion outer wall 6′′b. Are mixed to form fine bubbles MB and discharged from the discharge passage 4 at high speed. Therefore, in the apparatus shown in FIGS. 2B and 2C, the gas flow is directed to the right, and the high-speed liquid and the fine bubbles MB are mixed more strongly. However, the resistance to mixing is greater than in the case of FIG. As shown in FIGS. 2B and 2C, in the case where the outer wall 6′b or 6 ″ b of the taper portion is provided with a swivel plate or a spiral protrusion or groove, the generated fine bubbles are finer ( Nanobubbles, micro-nanobubbles) are likely to occur.

  A microbubble generator 1 ″ shown in FIG. 3 (a) shows a modification in which an elongated throat 17 is incorporated at the tip of the protruding portions 6c, 6′c, 6 ″ c of the insertion member of FIG. 1 or FIG. . Then, pressurization is performed in the long throat 17 to increase the solubility of the fine bubbles MB, the fine bubbles MB are sheared at the next orifice 18, and the fine bubbles MB are saturated and discharged at the diffuser 8 portion. . What is shown in the lower part of FIG. 3A is a diagram showing the fluctuation of the pressure applied to the liquid R1 inside the fine bubble generating device 1 ″. That is, the pressure of the liquid R1 fed to the mortar portion 5 gradually decreases and becomes a vacuum state in the vicinity of the insertion member protruding portion 6c, is pressurized at the throat 17 portion, is sheared at the orifice 18 portion, and is fined at the diffuser 8. The bubble MB becomes saturated and becomes atmospheric pressure.

  FIG. 3B schematically shows the flow of the gas K in the flow passage 7 (the gap between the tapered outer wall 6b of the insertion member and the inner wall 5a of the sliding bowl) and the movement of the fine bubbles MB at the discharge tip 6c. It is explanatory drawing shown. Here, in the flow passage 7, the gas K (rightward) gradually rotates faster, is entrained in the liquid R <b> 1 in the vicinity of the discharge portion distal end 6 c, becomes a fine bubble MB, and is discharged from the discharge path 4.

  4 directly connects the diffuser 8 to the throat 17 and provides a buffer tank 19 in front of the diffuser 8 to discharge the liquid R2 containing a large amount of fine bubbles MB from the buffer tank 19 at high speed. Is. What is shown in the lower part of FIG. 4 is a diagram showing fluctuations in pressure applied to the liquid R <b> 1 inside the microbubble generator 30. That is, the pressure of the liquid R1 sent to the mortar part 5 (nozzle part) gradually decreases, becomes negative pressure (vacuum suction) at the throat 17 part, is pressurized at the diffuser 8 part, and is hydrostatically sheared at the puffer tank 19. Is done.

  Next, FIG. 5 (a) shows an example of a longitudinal sectional view of the fine bubble generating apparatus according to claim 5 of the present invention. This fine bubble generating device 40 has a discharge passage 4 of the fine bubble generating device 1 shown in FIG. 1 as a throat 17 and a reaction tank 20 having a large diameter in front of the throat 17. In this reaction tank 20, the flow rate of the mixture of the liquid and the fine bubbles MB (liquid R2) is reduced, the gas is dissolved under pressure, and then the liquid R2 containing the fine bubbles is sent from the diffuser 8 having a reduced diameter at a high speed. To be released.

  In this fine bubble generating device 40, since the pressure of the mixture of the fine bubbles MB (liquid R2) is reduced in the reaction tank 20 to perform gas pressure dissolution, the solubility of the fine bubbles MB is further improved and the concentration of the fine bubbles MB is increased. High fine bubbles are generated.

  In FIG. 5A, if an orifice 18 having a smaller diameter than that of the diffuser 8 is provided between the reaction tank 18 and the diffuser 8, the bubbles MB can be further refined (claims of the present invention). 6). The orifice 18 may be formed by narrowing the base of the diffuser 8 or may be fitted with an orifice plate.

  FIG. 5B is a diagram showing fluctuations in pressure applied to the liquid R1 in the fine bubble generating device 40 in FIG. That is, the pressure of the liquid R1 fed to the mortar portion 5 gradually decreases and becomes a vacuum state in the vicinity of the insertion member protruding portion 6c, is pressurized in the region of the reaction tank 20 and is sheared in the portion of the orifice 18 to form a cluster. The microbubbles MB become saturated and become atmospheric pressure by the diffuser 8. The spreading angle from the throat of the reaction tank (β in FIG. 5B) may be a little wider than θ in FIG. That is, it is 60 ° to 120 °, and more preferably 80 ° to 100 °. In the case of FIG. 5B, α is 90 °.

  FIG. 5C schematically shows the flow of the gas K in the flow passage 7 (the gap between the tapered outer wall 6b of the insertion member and the inner wall 5a of the sliding bowl) and the movement of the fine bubbles MB at the discharge tip 6c. It is explanatory drawing shown. Here, in the flow passage 7, the gas K gradually rotates (toward the right), is entrained in the liquid R <b> 1 in the vicinity of the discharge portion distal end 6 c, becomes a fine bubble MB, and is discharged from the discharge path 4.

  Further, in each of the above embodiments, if the inner diameter of the diffuser 8 extends in parallel or about 3 degrees toward the front (the direction in which the liquid R1 flows, rightward in the figure), the liquid R2 cannot be discharged very well. If it is even more constricted, clogging will occur and release will not be successful. As a result of experiments by the present inventors, it has been found that when the spread angle is around 6 °, that is, 6 ° ± 0.1 to 0.2 °, the release can be most accomplished. On the other hand, when the angle is 10 ° or more, it is not released well (claim 7).

  Next, the gas inflow path 3 is opened to a position between the vicinity of the root of the mortar portion 5 provided in the inflow path 2 and a middle position. Then, the gas K is sucked from the gas inflow path 3 by the suction force of the pressurized liquid R1 flowing through the inflow path 2, and the gas K formed between the tapered outer wall 6b of the insertion member 6 and the inner wall 5a of the slide bowl is formed. While swirling through the flow passage 7, it is mixed with the high-speed liquid in front of the protruding portion 6 c of the insertion member 6 to become a fine bubble MB, and is discharged from the discharge path 4 at high speed.

  If a valve 31 such as a needle valve or a ball valve is provided in the gas inflow path 3, the diameter and concentration (number of bubbles) of bubbles generated by adjusting the amount of gas passing through the inflow path are made variable. be able to. Further, if the check valve 32 is incorporated in the gas inflow path 3, when the inflow of the pressurized liquid is stopped, the liquid containing foreign matters such as dust is mixed in the gas inflow path, and the inflow of the pressurized liquid is prevented. It is possible to prevent gas passage from being hindered when started (claims 8 and 9 of the present invention).

  In the middle of the inflow path through which the pressurized liquid passes, the insertion member is fitted into the portion, and the gap between the outer wall of the tapered portion of the insertion member and the inner wall of the scallop-shaped portion is inserted into the gas inflow path. Since the gas is swirled while passing through the flow passage, the gas is mixed with the high-speed liquid in the front of the insertion member to form fine bubbles and discharged from the discharge passage at high speed. Is provided, and a fine bubble generating device with less energy loss is provided.

1, 1 ′, 1 ″, 30, 40 Fine bubble generator 2 Inflow path R1 Pressurized liquid 3 Gas inflow path 31 Bubble 32 Check valve K Gas 4 Discharge path R2 Liquid containing fine bubbles MB Fine bubbles 5 Sliding Bowl part 5a Inner wall of sliding bowl part 6, 6 ', 6 "Insert member 6a, 6'a, 6" a Inner surface 6b, 6'b, 6 "b Taper part outer wall 6c, 6'c, 6' ′ C Projection 6d ・ 6′d ・ 6′′d 鍔 7 Gas K flow path 8 Diffuser θ Angle of sliding bowl and constriction of insertion member α Expansion angle of diffuser β Expansion from throat of the reaction tank Angle 8a 鍔 8b Inner surface 9 Flange 9a Hole 10 Flange 11 Packing 12 Packing 13 Bolt 13 'Nut 14 Pipe P Submersible pump or Onshore pump 15 Nozzle 16 Swivel plate 17 Throat 18 Orifice 19 Buffer tank 20 Reaction tank

Claims (9)

  Equipped with an inflow path through which pressurized liquid passes, a gas inflow path for high-speed suction of gas, and a discharge path for releasing liquid containing fine bubbles at high speed, and the middle of the inflow path is constricted in a slab shape And an insertion member that is inserted into the scallop-shaped part and has an outer wall that is the same taper as the inner wall of the scallop-shaped part and that is separated from the inner wall by a predetermined distance, and the inner surface of the insertion member is A scallop-like liquid flow path and a gap between the outer wall of the taper portion of the insertion member and the inner wall of the scallop-shaped portion are used as a gas flow passage sucked from the gas inflow passage, and the gas flows A fine bubble generator characterized by being mixed with a high-speed liquid in front of an insertion member while turning while passing through a path to form fine bubbles and discharged at high speed from a discharge path.   Provided on the outer wall of the tapered portion of the insertion member is a swirling plate or a spiral groove or ridge that positively causes a swirling flow in the gas sucked from the gas inflow passage. The fine bubble generating device according to claim 1, wherein the gas swirled in is mixed with a high-speed liquid in front of the insertion member.   The fine bubble generator according to claim 1 or 2, wherein a discharge passage is used as a throat, a diffuser is provided in front of the throat, and a liquid containing fine bubbles is discharged from the diffuser at a high speed.   A buffer tank is provided in front of the diffuser. After the gas (fine bubbles) is dissolved under pressure by reducing the flow rate of the mixture of liquid and fine bubbles in the buffer tank, the liquid containing fine bubbles is released at high speed. The fine bubble generating apparatus according to claim 3, wherein   A discharge tank having a discharge path as a throat and a rectification tank having a large diameter in front of the throat is provided, and the flow rate of the mixture of liquid and microbubbles is reduced in the reaction tank to perform gas (microbubble) pressure dissolution. The fine bubble generating device according to claim 1 or 2, wherein a liquid containing fine bubbles is discharged at a high speed from a diffuser having a reduced diameter.   6. The fine bubble generating apparatus according to claim 5, wherein an orifice having a smaller hole diameter than that of the diffuser is provided between the reaction tank and the diffuser to further refine the bubbles.   The microbubble generator according to claim 3, claim 4, claim 5 or claim 6, wherein the inner diameter of the diffuser has an angular spread of about 6 ° toward the front.   The diameter and concentration (number of bubbles) of the generated bubbles can be varied by adjusting the amount of gas passing through the inflow path for sucking the gas at high speed by using a valve such as a needle valve or a ball valve. Item 8. The fine bubble generating device according to any one of Items 7 to 9.   In order to prevent a liquid containing foreign substances such as dust from entering the gas inflow passage when the inflow of the pressurized liquid is stopped and inhibiting the gas passage when the inflow of the pressurized liquid is started, The microbubble generator according to any one of claims 1 to 8, wherein a check valve is attached to the gas inflow passage.

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