JP2008023435A - Microbubble generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microbubble generator capable of suppressing running costs or installation costs, and further effectively generating microbubbles. <P>SOLUTION: The microbubble generator 1 includes a casing 2 having a channel 23 allowing a liquid fluid to pass through from one end 21 to the other end 22, an acceleration means 3 for accelerating the liquid fluid passing through the channel 23 toward the other end 22 of the casing 2, and a gas/liquid mixing means for introducing a gas to the casing 2. According to the microbubble generator 1, a shock wave is generated inside a divergent nozzle part 7, so that bubbles contained in the liquid fluid are finely pulverized by this shock wave to generate microbubbles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microbubble generator that generates fine bubbles in a liquid fluid.

  The following Patent Documents 1 and 2 each disclose an apparatus for generating bubbles. Fine bubbles having a diameter of about 50 μm, called microbubbles, are widely used for sterilization of domestic water or wastewater treatment. In addition, there are various devices for generating microbubbles, and the type of liquid fluid and the main components of microbubbles generated in the liquid fluid can be appropriately selected depending on the application. For example, when microbubbles made of air are generated in aquaculture ponds, the dissolution of oxygen into water can be promoted, or in hot water circulating between a bathtub and a purification device in a public bath, microbubbles made of chlorine or ozone. If bubble is supplied, the hot water can be sterilized.

The principle of microbubble generation is as follows. That is, when the liquid fluid is vigorously accelerated, countless portions where the pressure is lower than the saturated vapor pressure are scattered in the liquid fluid, and the liquid fluid is vaporized in these portions to form cavities (fine bubbles). This cavity disappears when the flow velocity of the liquid fluid decreases, but when the gas is mixed in the liquid fluid as bubbles with a diameter of several millimeters in advance and these are accelerated together, the gas mixed in the liquid fluid fills the cavity, Float in liquid fluid as microbubbles.
JP 2003-126665 A Japanese Patent Laid-Open No. 06-165806

  In the case where microbubbles are generated by introducing, for example, a liquid fluid discharged from a pump into a conventional generator, the amount of microbubbles generated per predetermined time is limited. In order to increase this generation amount, the flow rate of the liquid fluid introduced into the generator or the volume of gas mixed in the liquid fluid must be increased. In practice, however, the upper limit of the flow rate of the liquid fluid is 15 to 30. Liter per minute is common, and the proportion of gas in the liquid fluid is in the range of about 1 to 10 percent void fraction.

  Even if the conventional generator is enlarged so as to exceed the upper limit exemplified here, no particular effect is recognized. This is because if the volume of the gas increases with an increase in the flow rate of the liquid fluid, the gas is less likely to disperse in the liquid fluid. Therefore, even if cavitation occurs, all of the gas forms microbubbles. It is thought that this is not possible. As a result, part of the gas is discharged from the generator as bubbles with a diameter of several millimeters. Further, since the flow rate of the liquid fluid is a value inherent to the generator, one generator cannot be used in the flow rate range of 15 to 30 liters per minute as described above. For this reason, in the prior art, unless a plurality of generators having different specifications are prepared, the flow rate of the liquid fluid cannot be increased or decreased.

  Furthermore, when liquid fluid is pressurized with a powerful pump as described above, the physical strength of piping, etc. for supplying liquid fluid to the generator is lost in addition to excessive energy loss. Must be increased. For this reason, the running cost of the generator rises, and further increases the equipment cost of the whole plant to which the generator is applied.

  Accordingly, an object of the present invention is to provide a microbubble generator that can keep running costs or equipment costs low and can efficiently generate microbubbles.

  The present invention includes a casing having a flow path through which liquid fluid can pass from one end to the other end, acceleration means for accelerating the liquid fluid toward the other end of the flow path, and gas-liquid mixing for introducing gas into the casing The accelerating means introduces the liquid fluid into the flow path of the casing from a direction intersecting an axial flow direction through which the liquid fluid passes through the casing. An inlet, a cone-shaped portion formed with a throat portion that narrows the cross-sectional area of the flow path from one end to the other end of the casing; and the throat portion provided in the throat portion so as to be displaceable in the axial direction. And a divergent nozzle portion connected to the cone-shaped portion and having a cross-sectional area of the flow path that increases toward the other end of the casing. To.

  Further, in the microbubble generator according to the present invention, the valve body is connected to an advancing / retreating rod having a thread portion extending in the axial direction and screwed to one end of the casing, and the advancing / retreating rod is connected to the casing. The valve body can be displaced in the axial flow direction by rotating it.

  Furthermore, the microbubble generator according to the present invention is characterized in that a vent passage is formed in the forward / backward rod and the valve body so as to penetrate each in the axial direction, and gas can be introduced into the vicinity of the throat portion through the vent passage. And

  Furthermore, in the microbubble generator according to the present invention, an ejection hole for ejecting gas from the ventilation passage is formed in the advance / retreat rod, and an annular member rotatably attached around the advance / retreat rod is provided from the inside thereof. A small hole penetrating the outside is formed, and the small hole of the annular member matches the ejection hole of the advance / retreat rod in the process of rotating the annular member.

  When liquid fluid discharged from, for example, a pump or the like is supplied to the introduction port of the microbubble generator according to the present invention, the swirl flow toward the other end of the casing is caused by swirling along the inner peripheral surface of the casing. Form. And since the cross-sectional area of the flow path is gradually reduced by the cone-shaped portion, the flow velocity of the liquid fluid that forms the swirling flow increases as it goes from one end of the casing to the other end. At the same time, bubbles of cavitation are generated as the pressure of the liquid fluid drops to the saturated water vapor pressure.

  As described above, since the cone-shaped portion can be configured very simply and the liquid fluid can be accelerated based on the squeezing effect, the manufacturing cost can be reduced in addition to the miniaturization of the microbubble generator. Further, since the liquid fluid smoothly follows the inner peripheral surface of the casing, there is an advantage that the pressure loss of the liquid fluid is small.

  Furthermore, according to the microbubble generator according to the present invention, the throat portion can be appropriately narrowed by displacing the valve body that regulates the liquid fluid passing through the throat portion in the axial flow direction. The flow velocity of the liquid fluid passing through the can be further increased. Further, when the valve body is connected to an advance / retreat rod having a thread portion that extends in the axial direction and is screwed to one end of the casing, the valve body can be displaced immediately by simply rotating the advance / retreat rod with respect to the casing. . Therefore, according to the microbubble generator, the displacement amount of the valve body can be adjusted by the simple operation as described above, so that the degree of pressure, flow rate, or viscosity when the liquid fluid is introduced into one end of the casing is adjusted. Even if the fluid changes, microbubbles can be generated satisfactorily.

  On the other hand, the gas-liquid mixing means mixes gas such as air into the liquid fluid as bubbles. For example, an air passage that penetrates each of the advancing and retracting rod and the valve body in the axial flow direction may be formed, and gas may be introduced into the vicinity of the throat portion through the air passage. In this case, the amount of gas introduced near the throat portion is arbitrary. Below, the ratio of the gas (bubble) which occupies it with respect to the cross-sectional area of a throat part is defined as a void fraction. Further, it is known that the speed at which sound waves propagate through a liquid fluid (hereinafter referred to as “in-liquid sound speed”) depends on the void ratio of the liquid fluid.

  Since the sound velocity in the liquid is determined based on the void ratio of the liquid fluid passing through the throat portion, the flow velocity of the liquid fluid passing through the throat portion can be matched with the sound velocity in the liquid by displacing the valve body as described above. . As described above, when the liquid fluid that has passed through the throat portion at the sound speed in the liquid reaches the divergent nozzle portion, the flow velocity of the liquid fluid is rapidly decelerated. Thereby, a shock wave is generated inside the divergent nozzle portion, and bubbles contained in the liquid fluid are finely pulverized by the shock wave to generate microbubbles.

  Therefore, according to the microbubble generator, a large amount of microbubbles can be generated efficiently. In addition, since it is not necessary to increase the output of the pump or to strengthen the piping etc. accompanying the increase in the flow rate of liquid fluid and the volume of gas as in the prior art, the running cost of the microbubble generator is reduced. It is also possible to reduce equipment costs such as improving a plant to which the microbubble generator is applied.

  In addition, an ejection hole for ejecting gas from the ventilation path may be formed in the advance / retreat rod, and a small hole penetrating from the inside to the outside may be formed in the annular member rotatably attached around the advance / retreat rod. In this case, in the process of rotating the annular member that receives the rotational force from the swirling liquid fluid, the gas is allowed to flow into the liquid fluid in a state of being divided into fine bubbles, so that the generation of microbubbles can be assisted. .

  The “liquid fluid” to be described below may be mainly composed of water, oil, alcohol, fuel, slurry, beverage, medicine, or the like, and “gas” is a general term for all gases other than air. Further, the physical or chemical properties such as temperature, pressure, flow rate, viscosity, etc. of the liquid fluid or gas are not limited at all.

  As shown in FIGS. 1 to 3, the microbubble generator 1 includes a casing 2 having a flow path 23 through which a liquid fluid can pass from one end 21 to the other end 22, and a liquid fluid passing through the flow path 23 other than the casing 2. Accelerating means 3 for accelerating toward the end 22 and gas-liquid mixing means to be described later for introducing gas into the casing 2 are provided.

  The direction of the arrow with “OUT” in FIGS. 1 and 2 coincides with the axial flow direction in which the liquid fluid passes through the casing 2. The casing 2 is formed by connecting an introduction block 24, an acceleration block 25, and a discharge block 26 in the order described here. For example, if a part of the casing 2 is worn by the slurry, only that part can be replaced. The flow path 23 has a cone-shaped part 5, a throat part 6, and a divergent nozzle part 7, and is formed consistently inside the introduction block 24, the acceleration block 25, and the discharge block 26. Hereinafter, when the “cross-sectional area of the flow path 23” is described, it means the cross-sectional area of the cone-shaped portion 5, the throat portion 6, or the divergent nozzle portion 7 unless otherwise specified.

  The introduction block 24 has an introduction port 28 opened at the back of a hose union 27 provided on the side thereof, and for example, liquid fluid discharged from a pump or the like is introduced via a hose connected to the hose union 27 or the like. When supplied to the port 28, this liquid fluid is introduced into the flow path 23 from the direction of the arrow marked “IN” in FIGS. In other words, the liquid fluid flows into the flow path 23 inside the introduction block 24 from the direction orthogonal to the axial flow direction. As shown in FIG. 4, the flow path 23 in each of the introduction block 24 and the acceleration block 25 forms a cone-shaped inner peripheral surface that is smoothly connected to each other. A section of the flow path 23 corresponding to the inside of the inner peripheral surface is the cone-shaped portion 5. Instead of the hose union 27, a short pipe in which a pipe screw is formed may be applied.

  The cone-shaped portion 5 has a shape that decreases in diameter as it goes from one end 21 to the other end 22 of the casing 2, and a portion where the diameter is minimized is the throat portion 6. In addition, a valve body 9 fixed to the front portion of the advance / retreat rod 8 is inserted into the throat portion 6. The advance / retreat rod 8 is a rod that extends in the axial direction. The introduction block 24 is provided with a guide sleeve 29 for guiding the advance / retreat rod 8 in the axial direction, and a threaded portion 81 formed on the outer periphery of the advance / retreat rod 8 is screwed to a female screw (not shown) formed on the inner periphery thereof. is doing.

  The valve body 9, the cone-shaped portion 5, and the advance / retreat rod 8 described so far are elements constituting the acceleration means 3 of the microbubble generator 1. By operating the handwheel handle 82 attached to the rear part of the advance / retreat rod 8 and rotating the advance / retreat rod 8 relative to the casing 2, the valve element 9 can be freely displaced in the axial direction. FIG. 4 shows a state in which the valve body 9 is displaced (advanced) so as to approach the throat portion 6, and FIG. 5 shows a state in which the valve body 9 is displaced (retracted) away from the throat portion 6. .

  As shown in FIG. 6, the advancing / retreating rod 8 and the valve body 9 are each formed with an air passage 4 that penetrates each of them in the axial direction and opens to the end face 41 at the tip of the advancing / retreating rod 8. Said gas-liquid mixing means mixes gas, such as air sent from a compressor etc., for example as a bubble in liquid fluid. The air passage 4 is responsible for the function of the gas-liquid mixing means. Further, a pump capable of supplying a fluid formed by mixing liquid and gas to the inlet 28 may be applied as the gas-liquid mixing means. Reference numeral 40 indicates an introduction hole opened at the rear part of the advance / retreat rod 8.

  Next, a usage example of the microbubble generator 1 will be described with reference to FIGS. For example, when the liquid fluid discharged from a pump or the like is supplied to the inlet 28 of the casing 2 after the microbubble generator 1 is submerged in a liquid stored in a water tank or the like, the liquid fluid is supplied to the inner periphery of the cone-shaped portion 5. A swirl flow toward the other end 22 of the casing 2 is formed while swirling vigorously along the surface. Then, as the liquid fluid that forms the swirl flows in the cone-shaped portion 5 toward the other end 22, the cross-sectional area of the flow path 23 is gradually reduced, so that the axial flow direction of the liquid fluid and the flow velocity in the swirl direction are The acceleration is accelerated from one end 21 to the other end 22 of the casing 2. These flow rates are the fastest when the liquid fluid passes through the throat section 6.

  As described above, when the liquid fluid passes through the throat portion 6 or immediately before, the pressure of the liquid fluid drops and falls below the saturated water vapor pressure, so that bubbles due to cavitation are generated, and microbubbles are simultaneously generated. appear. In particular, at a position close to the swirling center of the swirling flow, the pressure of the liquid fluid drops remarkably, so that the above-described cavitation is promoted and microbubbles are easily generated. In addition, the liquid fluid is accelerated in the cone-shaped portion 5 to further promote cavitation. For example, if tap water ejected from a tap is applied as a liquid fluid, the bubbles previously contain air that has been dissolved in tap water.

  Further, if the valve body 9 is displaced in the above-described manner and the valve body 9 is advanced to approach the throat portion 6, the throat portion 6 is narrowed by the valve body 9 and the flow velocity of the liquid fluid passing through the throat portion 6 is reached. Can be further accelerated. On the contrary, if the valve body 9 is retracted away from the throat portion 6, the flow rate of the liquid fluid passing through the throat portion 6 can be suppressed. That is, the flow rate when the liquid fluid passes through the throat portion 6 largely depends on the pressure, flow rate, or degree of viscosity at which the liquid fluid is introduced into the one end 21 of the casing 2, but as illustrated in FIGS. By displacing the valve body 9 in the axial direction, the throat portion 6 can be appropriately narrowed, and the flow rate of the liquid fluid passing through the throat portion 6 can be set to 20 to 30 m / s, for example.

  On the other hand, the amount of gas mixed into the liquid fluid by the gas-liquid mixing means is arbitrary, but in this embodiment, the ratio of bubbles in the cross-sectional area of the throat portion 6 is 30 as a void ratio. Set to ˜40%. In this case, a gas such as air sent from a compressor or the like is introduced into the air passage 4 through the introduction hole 40 of the advance / retreat rod 8. As a result, the gas flows through the ventilation path 4 toward the front portion of the advance / retreat rod 8, and is mixed as bubbles into the liquid fluid near the throat portion 6. In addition, the amount of gas sent from the compressor or the like to the ventilation path 4 may be adjusted using a flow rate adjusting valve, or when the water depth for sinking the microbubble generator 1 is shallow as described above, the compressor or the like. May be omitted, and the liquid fluid passing through the throat portion 6 may cause the gas to be self-primed.

  By the way, it is known that the sound velocity in liquid is 20 to 30 m / s when the void ratio of the liquid fluid mainly composed of water is 30 to 40 percent. That is, the void ratio of the liquid fluid is determined in such a manner that the flow velocity when the liquid fluid passes through the throat portion 6 and the sound velocity in liquid in the liquid fluid are substantially matched.

  Further, the liquid fluid that has passed through the throat portion 6 at a subsonic velocity reaches the divergent nozzle portion 7. Since the divergent nozzle portion 7 has a shape that increases in diameter toward the other end 22 of the casing 2 and expands the cross-sectional area of the flow path 23, the flow velocity of the liquid fluid is rapidly decelerated in the middle of the divergent nozzle portion 7. Thereby, since a shock wave is generated inside the divergent nozzle portion 7, bubbles contained in the liquid fluid are finely pulverized by the shock wave, and microbubbles are generated. This is considered to be due to the pressure difference at this time, because the cross-sectional area of the flow path 23 increases in the middle of the divergent nozzle portion 7 and the pressure of the liquid fluid rapidly increases.

  Therefore, according to the microbubble generator 1, a large amount of microbubbles can be generated efficiently. In addition, since it is not necessary to increase the output of the pump or to reinforce the piping or the like accompanying the increase in the flow rate of liquid fluid and the volume of gas as in the prior art, the running cost of the microbubble generator 1 is reduced. In addition, it is possible to reduce equipment costs such as improving a plant to which the microbubble generator 1 is applied.

  Next, the ventilation path 4 shown to Fig.7 (a) is demonstrated. The inner diameter of the air passage 4 is 1 to 3 mm, but the diameter of the air passage 4 opened to the end face 41 of the tip of the advance / retreat rod 8 is preferably a pinhole 42 having a diameter of 1 mm or less. This is because the size of the bubbles released from the air passage 4 into the liquid fluid is 1 mm or less, so that the bubbles are surely induced to be crushed by the shock wave, and the generation of microbubbles is supported. It will be. Alternatively, as shown in FIG. 2B, a porous ventilation material 43 may be fitted to the end surface 41 of the tip of the advance / retreat rod 8.

  Further, as shown in FIG. 8A, an annular hole 44 for ejecting gas from the air passage 4 is formed at an appropriate position on the peripheral surface of the advance / retreat rod 8, and the ring is attached around the advance / retreat rod 8 to be rotatable. A small hole 46 penetrating from the inside to the outside may be formed in the member 45. In this case, since the flow velocity of the liquid fluid includes a velocity component in the swirl direction, the annular member 45 rotates around the advance / retreat rod 8 by the rotational force received from the liquid fluid. Reference numeral 47 indicates a notch of the annular member 45 that functions as a blade. A blade may project from the annular member 45.

  Further, in the process in which the advance / retreat rod 8 rotates, when the position of the small hole 46 of the annular member 45 matches the ejection hole 44 of the advance / retreat rod 8, as shown in FIG. Flows into the liquid fluid through the ejection hole 44 and the small hole 46, but the small hole 46 of the annular member 45 has a different position with respect to the ejection hole 44 of the advance / retreat rod 8 as shown in FIG. Sometimes the gas flow is interrupted. By repeating the above, the gas that intermittently flows into the liquid fluid in a short cycle is released as fine bubbles in the liquid fluid, so that the generation of microbubbles can be assisted for the same reason as above. .

  It should be noted that the present invention can be implemented in variously modified, modified, or modified forms based on the knowledge of those skilled in the art without departing from the spirit of the present invention. In the above description, specific numerical values are enumerated as the flow rate and the void rate of the liquid fluid, but if the flow rate of the liquid fluid can be set at a high speed of 30 m / s or more, the void rate is set to 30 to 40 percent. It is not necessary to limit to the range. Moreover, the material of the casing 2 or the acceleration means 3, the dimension of each part which comprises the flow path 23, or an angle is a design matter.

  As shown in FIG. 9, the inlet 28 is formed in the end face of the one end 21 of the casing 2 so that the liquid fluid can flow into the flow path 23 inside the introduction block 24 from a direction obliquely intersecting the axial flow direction. May be. The forward / backward rod 8 may be rotated by a motor or the like, and the forward / backward movement of the forward / backward rod 8 may be realized using a latch mechanism or a rack and pinion mechanism.

  The present invention is a technique useful for generating a large amount of microbubbles simply and immediately, and expands the availability of microbubbles in a wide range of fields ranging from environmental measures, chemical industry, and medical welfare, for example. It is. The microbubble generator can also be used for mixing different gases or liquids in addition to gas-liquid mixing.

The side view which fractured | ruptured a part of microbubble generator concerning Example 1 of this invention. The front view of the microbubble generator which concerns on Example 1 of this invention. The perspective view of the microbubble generator which concerns on Example 1 of this invention. Sectional drawing which shows one usage example of the microbubble generator which concerns on Example 1 of this invention. Sectional drawing which shows the other usage example of the microbubble generator which concerns on Example 1 of this invention. The perspective view of the advancing / retreating rod applied to the microbubble generator which concerns on Example 1 of this invention, and a valve body. (A) is sectional drawing which shows an example of the gas-liquid mixing means applied to the microbubble generator which concerns on Example 1 of this invention, (b) is sectional drawing which shows another example. (A) is sectional drawing which shows the other form of the gas-liquid mixing means applied to the microbubble generator based on Example 1 of this invention, (b) is the YY sectional view taken on the line which shows an example of the operation | movement, ( c) YY sectional view which shows the other example of the operation | movement. The perspective view which saw through the flow path of the microbubble generator of the other form which concerns on this invention.

Explanation of symbols

1: Microbubble generator 2: Casing 3: Acceleration means 4: Ventilation path (gas-liquid mixing means)
5: Cone-shaped part 6: Throat part 7: Wide nozzle part 8: Advance and retreat rod 9: Valve body 21: One end 22: Other end 23: Flow path 28: Inlet 44: Ejection hole 45: Ring-shaped member 46: Small hole 81 : Screw part

Claims (4)

A casing having a flow path through which liquid fluid can pass from one end to the other; acceleration means for accelerating the liquid fluid toward the other end of the flow path; and gas-liquid mixing means for introducing gas into the casing. A microbubble generator,
The accelerating means introduces the liquid fluid into a flow path of the casing from a direction intersecting an axial flow direction through which the liquid fluid passes through the casing;
A cone-shaped portion that forms a throat portion that squeezes the cross-sectional area of the flow path from one end of the casing to the other end;
A valve body provided in the throat portion so as to be freely displaceable in the axial direction, and regulating the liquid fluid passing through the throat portion;
A divergent nozzle portion connected to the cone-shaped portion and having a cross-sectional area of the flow path that widens toward the other end of the casing;
A microbubble generator comprising:   The valve body is connected to an advancing / retreating rod having a thread portion extending in the axial direction and screwed to one end of the casing, and rotating the advancing / retreating rod with respect to the casing, the valve body is moved to the shaft. The microbubble generator according to claim 1, wherein the microbubble generator can be displaced in a flow direction.   3. The microbubble generator according to claim 2, wherein an air passage that penetrates the advance / retreat rod and the valve body in the axial direction is formed, and gas can be introduced to the vicinity of the throat portion through the air passage. 4. .   An ejection hole for ejecting gas from the ventilation path is formed in the advance / retreat rod, and a small hole penetrating from the inside to the outside is formed in an annular member rotatably attached around the advance / retreat rod, and the annular member The microbubble generator according to claim 3, wherein a small hole of the ring-shaped member is matched with an ejection hole of the advance / retreat rod in a process of rotating.

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