JP7614131B2 - Gas swirling shear device and microbubble generator - Google Patents

Description

The present invention relates to a gas swirling shear device for generating nano-level fine bubbles, and a fine bubble generating device using the same.

Conventionally, there is known a swirling liquid flow type air bubble generating device that generates a strong swirling liquid flow in a cylindrical container to break down air bubbles into small particles (see, for example, Patent Document 1).

Patent No. 6792254

Patent Document 1 describes a configuration in which a spiral groove is formed on the inner surface of a cylindrical container in a bubble generating device, and the inclination angle of the fluid introduction hole and the inclination angle of the spiral groove are aligned to efficiently produce fine bubbles. However, with the above configuration, it is not possible to ensure a sufficient difference in flow speed between the inner and outer periphery sides within the cylindrical container, and therefore it is not possible to sufficiently increase the efficiency of generating fine bubbles.

The present invention has been made in consideration of the above-mentioned circumstances, and the problem that the present invention aims to solve is to provide a gas swirling shear device and a micro-bubble generator that can improve the efficiency of generating micro-bubbles by ensuring a flow rate difference between the inner and outer periphery of a cylindrical container.

Below, we explain the means to solve the above problems.

The gas swirling shear device according to the present invention comprises a tubular member having a cylindrical inner peripheral surface, a first end wall member closing one end side of the tubular member in the axial direction, a second end wall member closing the other end side of the tubular member in the axial direction, and a fluid swirling chamber partitioned by the tubular member, the first end wall member, and the second end wall member, and a fluid inlet hole for introducing a gas-liquid mixed fluid into the fluid swirling chamber is formed penetrating the tubular member at a position close to the second end wall member in the axial direction of the tubular member, a fluid discharge hole penetrating the second end wall member is formed along the central axis of the inner peripheral surface of the tubular member, and a fluid inlet pipe is connected to the fluid inlet hole, and the fluid inlet pipe is formed along the tangential direction of the inner peripheral surface of the tubular member when viewed in the axial direction of the tubular member, and is formed inclined toward the side of the second end wall member as it moves away from the tubular member radially outward when viewed from the side of the tubular member.

The microbubble generating device according to the present invention comprises the above-mentioned gas swirling shearing device, a vortex pump connected to the fluid inlet of the gas swirling shearing device and producing a gas-liquid mixed fluid, a disperser connected to the fluid outlet of the gas swirling shearing device and dispersing and discharging the fluid in which the gas has been micronized by the gas swirling shearing device, and a liquid storage tank for immersing the disperser in liquid.

The gas swirling shear device and micro-bubble generator of the present invention have the effect of improving the efficiency of micro-bubble generation by ensuring a flow velocity difference between the inner and outer periphery of the cylindrical container.

FIG. 1 is a diagram showing a schematic configuration of a micro-bubble generating device. FIG. 2 is a perspective view showing a gas swirling shear device. FIG. 2 is a front view showing a gas swirling shear device. FIG. 2 is a side cross-sectional view showing a gas swirling shear device. 5 is a cross-sectional view taken along line AA in FIG. 4 . FIG. 2 is a front cross-sectional view of a gas swirling shear device showing fluid flow. FIG. 2 is a side cross-sectional view of a gas swirling shear device showing fluid flow. 4A and 4B are side cross-sectional views of a gas swirling shear device and a comparative example showing the flow velocity distribution of a fluid.

First, a micro-bubble generating device (hereinafter, simply referred to as the "generator") 10 according to one embodiment of the present invention will be described with reference to FIG. 1. The generator 10 has a vortex pump 12 for producing a gas-liquid mixture, a gas swirling shearing device (hereinafter, simply referred to as the "shearing device") 14 for receiving the gas-liquid mixture produced by the vortex pump 12 and micronizing the gas contained in the gas-liquid mixture at the nano level, and a disperser 16 for dispersing and releasing the fluid in which the gas has been micronized by the shearing device 14. The disperser 16 is immersed in the liquid in the liquid storage tank 36, and disperses and releases the micronized gas bubbles into the liquid L in the liquid storage tank 36. The liquid in the liquid storage tank 36 is also supplied to the vortex pump 12 via a pipe 38.

The vortex pump 12 has a housing 20 and an impeller 22 that is housed in the housing 20 and driven to rotate. The housing 20 is provided with a liquid suction hole 24, a gas suction hole 26, and a discharge hole 28. The liquid suction hole 24 is connected to a pipe 38 and guides the liquid sucked from the liquid storage tank 36 to the inside of the housing 20. The gas suction hole 26 is connected to the liquid suction hole 24 and guides the gas into the liquid flowing through the liquid suction hole 24.

The liquid and gas sucked into the housing 20 are mixed by the rotation of the impeller 22, and the mixed gas-liquid fluid is discharged from the discharge hole 28. The discharge hole 28 is formed with a smaller diameter than the liquid suction hole 24, so that the fluid discharge speed to the shearing device 14 is increased.

A pipe 30 is connected to the gas suction hole 26, and a solenoid valve 32 is attached to the pipe 30. When the vortex pump 12 is driven, the solenoid valve 32 is closed, and is opened a certain time (e.g., 60 seconds) after the pump is started. This is to minimize the occurrence of cavitation inside the pump due to the gas being sucked into the pump.

As shown in Figures 2 to 5, the shearing device 14 includes a tubular member 40 having a cylindrical inner peripheral surface, a first end wall member 42 that closes one end side in the axial direction of the tubular member 40, and a second end wall member 44 that closes the other end side in the axial direction of the tubular member 40. The shearing device 14 also includes a fluid swirling chamber 46 that is partitioned by the tubular member 40, the first end wall member 42, and the second end wall member 44.

A fluid introduction hole 48 is formed on the side of the cylindrical member 40 to introduce the gas-liquid mixture fluid into the fluid swirl chamber 46 in the tangential direction of the inner surface of the fluid swirl chamber 46. The fluid introduction hole 48 is formed penetrating the cylindrical member 40 at a position closer to the second end wall member 44 in the axial direction of the cylindrical member 40. In addition, a fluid discharge hole 50 is formed in the second end wall member 44 along the central axis of the inner peripheral surface of the cylindrical member 40, penetrating the second end wall member 44.

A fluid introduction pipe 49 that is connected to the fluid introduction hole 48 is attached to the outer peripheral surface of the cylindrical member 40, and the fluid introduction pipe 49 is connected to a pipe extending from the discharge hole 28 of the vortex pump 12. As shown in Figures 3 and 5, the fluid introduction pipe 49 is formed along the tangent direction of the inner peripheral surface of the cylindrical member 40 when viewed in the axial direction of the cylindrical member 40.

As shown in FIG. 4, the fluid introduction pipe 49 is inclined toward the second end wall member 44 as it moves radially outward from the cylindrical member 40 when viewed from the side of the cylindrical member 40 (in this embodiment, the angle between the fluid introduction pipe 49 and the side of the cylindrical member 40 is 75 degrees). Furthermore, a fluid discharge pipe 51 that is connected to the fluid discharge hole 50 is attached to the second end wall member 44, and the fluid discharge pipe 51 is connected to a pipe extending between the second end wall member 44 and the distributor 16.

The disperser 16 has a tubular member 60 with a cylindrical inner surface and end wall members 62 that close both ends of the tubular member 60. The disperser 16 has a fluid inlet 64 in the axial center of the tubular member 60 that is connected to the fluid discharge hole 50 of the shearing device 14, and a fluid outlet 66 that is provided through the end wall member along the axis of the tubular member.

The fluid discharged from the fluid discharge hole 50 of the shearing device 14 flows into the disperser 16 through the fluid inlet 64 of the disperser 16, and while rotating, it is split into both sides in the axial direction and is dispersed and discharged from the fluid outlet 66 into the liquid in the liquid storage tank.

To operate the generator 10, the vortex pump 12 is driven to draw in the liquid in the liquid reservoir, creating a flow of liquid that circulates through the vortex pump 12, the shear device 14, the disperser 16, and the liquid reservoir 36.

After a certain time, for example 60 seconds, after the vortex pump 12 is driven, the solenoid valve 32 is opened, air is sucked in through the pipe 30, and a gas-liquid mixed fluid is introduced into the pump housing. The gas-liquid mixed fluid introduced into the pump housing is driven along the inner circumferential surface of the housing by the action of the impeller and discharged through the discharge hole 28, during which time the gas in the fluid is subjected to shear forces caused by turbulence generated within the fluid, causing it to break down into fine particles.

The gas-liquid mixture fluid from the discharge hole 28 is introduced into the fluid swirling chamber 46 of the shearing device 14, where it is turned into a swirling flow and subjected to a strong shearing force, further breaking down the gas inside. This strong shearing force in the shearing device 14 makes it possible to break down many gas particles to the nano level.

The gas-liquid mixture discharged from the shearing device 14 is released into the liquid storage tank 36 while being re-formed into a swirling flow by the disperser 16. Therefore, the air bubbles are also refined in this disperser.

In this embodiment, the liquid circulates from the liquid storage tank through the vortex pump 12, the shearing device 14, and the disperser 16, but the liquid may be supplied to the vortex pump 12 from a location other than the liquid storage tank 36. However, by using a circulation system as in the illustrated example, the gas is repeatedly atomized, making it possible to obtain finer bubbles.

As described above, in the shearing device 14 according to this embodiment, the fluid introduction pipe 49 is formed along the tangential direction of the inner peripheral surface of the cylindrical member 40 when viewed in the axial direction of the cylindrical member 40. As a result, the gas-liquid mixture fluid introduced into the fluid swirling chamber 46 flows while swirling within the fluid swirling chamber 46, as shown by the arrow in FIG. 6.

The fluid introduction pipe 49 is formed so as to incline toward the second end wall member 44 as it moves away from the cylindrical member 40 radially outward when viewed from the side of the cylindrical member 40. As a result, as shown by the arrow in FIG. 7, the gas-liquid mixture fluid introduced into the fluid swirl chamber 46 flows toward the first end wall member 42 while swirling around the outer periphery of the fluid swirl chamber 46. The gas-liquid mixture fluid that hits the first end wall member 42 flows around the axial center of the fluid swirl chamber 46 toward the second end wall member 44, and is discharged from the fluid discharge hole 50 and the fluid discharge pipe 51.

In this way, in the shearing device 14 according to this embodiment, the fluid introduction pipe 49 is positioned closer to the second end wall member 44 and is configured to be inclined toward the second end wall member 44. This makes it possible to increase the flow velocity difference (the sum of the flow velocities in the opposite directions) between the flow (first flow) of the gas-liquid mixed fluid that swirls around the outer periphery inside the fluid swirl chamber 46 and heads toward the first end wall member 42, and the flow (second flow) of the gas-liquid mixed fluid that hits the first end wall member 42 and heads toward the second end wall member 44.

The results of a simulation conducted by the applicant regarding the flow rate difference in the shearing device 14 will be explained using Figure 8. In this simulation, a discharge flow rate of 25 to 32 L/min and a discharge pressure of 0.60 to 0.65 MPa were used, which are close to the values measured in the actual machine test.

Figure 8(a) shows the results of a simulation performed on the shearing device 14 according to this embodiment. Figure 8(b) shows the results of a simulation performed on a shearing device of a conventional shape in which the fluid introduction pipe is not inclined, as a comparative example. As shown in Figure 8(a), the shearing device 14 according to this embodiment resulted in a significantly higher flow velocity in the outer periphery compared to the flow velocity in the axial center inside the fluid swirling chamber 46. Also, as shown in Figures 8(a) and (b), the shearing device 14 according to this embodiment was able to increase the flow velocity difference in the fluid swirling chamber 46 compared to shearing devices of a conventional shape.

In this way, in the shearing device 14 according to this embodiment, by forming the fluid introduction pipe 49 at a position closer to the second end wall member 44, as shown in FIG. 7, it is possible to increase the flow rate difference between the first flow and the second flow and to increase the distance over which the two flows intersect. This increases the shear force that the gas-liquid mixture fluid receives in the fluid swirl chamber 46 and lengthens the time that the gas-liquid mixture fluid receives the shear force.

In the shearing device 14 according to this embodiment, the flow velocity difference in the fluid swirl chamber 46 is increased as described above, thereby strengthening the shear force that the gas-liquid mixture fluid receives. In addition, in the shearing device 14 according to this embodiment, the time that the gas-liquid mixture fluid receives the shear force is lengthened. This improves the efficiency of generating fine bubbles in the fluid swirl chamber 46.

The applicant also generated ultra-fine bubble water (water containing many fine bubbles) using the shearing device 14 according to this embodiment and a shearing device of a conventional shape, and compared the cleaning performance. Specifically, two stainless steel plates with NaCl attached were fixed in parallel with a gap of 1 mm, attached to a mixer, and cleaning was performed in the generated water at a constant rotation speed. When comparing the time until the cleaning rate reached 100%, this embodiment was able to reduce the cleaning time by about 44% compared to the conventional shape. In addition, the cleaning speed after 10 seconds from the start of cleaning, when the difference in cleaning speed is likely to occur, was 2.02%/sec for this embodiment and 0.83%/sec for the conventional technology. In other words, this embodiment was able to increase the cleaning speed compared to the conventional shape.

The applicant also generated ultra-fine bubble water using the shearing device 14 according to this embodiment and a shearing device of a conventional shape, and compared the number of microbubbles contained therein. In terms of the number of microbubbles with a most frequent diameter of around 75 nm, this embodiment was able to generate approximately 1.8 times as many microbubbles as the conventional shape. In terms of the total number of microbubbles, this embodiment was able to generate approximately 1.6 times as many microbubbles as the conventional shape.

As described above, the shearing device 14 and generator 10 according to this embodiment can increase the efficiency of generating fine bubbles compared to conventional shapes. Therefore, the ultra-fine bubble water generated using the generator 10 can have increased cleaning power compared to conventional shapes.

10. Generator (microbubble generator)
12. Vortex pump
14 Shearing device (gas swirling shearing device)
16 Disperser 20 Housing
22 Impeller 24 Liquid suction hole
26 Gas suction hole 28 Discharge hole
30 Pipe 32 Solenoid valve
36 Liquid storage tank 38 Pipe
40: Cylindrical member 42: First end wall member
44 Second end wall member 46 Fluid swirl chamber
48 Fluid introduction hole 49 Fluid introduction pipe
50 Fluid discharge hole 51 Fluid discharge pipe
60 Cylindrical body 64 Fluid inlet
66 Fluid outlet L Liquid

Claims (2)

A tubular member having a cylindrical inner circumferential surface;
a first end wall member that closes one end side in an axial direction of the cylindrical member;
a second end wall member that closes the other end side in the axial direction of the cylindrical member;
a fluid swirling chamber defined by the cylindrical member, the first end wall member, and the second end wall member,
a fluid inlet hole for introducing a gas-liquid mixture fluid into the fluid swirling chamber is formed through the cylindrical member at a position near the second end wall member in the axial direction of the cylindrical member,
a fluid discharge hole penetrating the second end wall member is formed along a central axis of an inner circumferential surface of the cylindrical member;
a fluid introduction pipe is connected to the fluid introduction hole,
The fluid introduction pipe is formed along a tangential direction of the inner peripheral surface of the tubular member when viewed in the axial direction of the tubular member, and is formed inclined toward the side of the second end wall member as it moves radially outward from the tubular member when viewed in a side direction of the tubular member. A gas swirling shear device according to claim 1;
a vortex pump connected to the fluid inlet of the gas swirling shear device to produce a gas-liquid mixed fluid;
a disperser connected to the fluid discharge hole of the gas swirl shear device and dispersing and discharging the fluid whose gas has been atomized by the gas swirl shear device;
A liquid storage tank for immersing the disperser in liquid.

Images