JP2003117365A - Micro-bubble producing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce fine uniform micro-bubbles economically by pressurizing and stirring gas liquid mixed fluid having high gas incorporated ratio with a pump and breaking the gas finely to efficiently dissolve the gas into the liquid. SOLUTION: A liquid intake pipe 6 and a gas intake pipe 7 are connected to a suction port 4 of the gas liquid mixing pump 1 through an intake pipe 5. A discharge pipe 16 is connected to the discharge port 15 of the gas liquid mixing pump 1 and a resistor 2 is provided on the discharge pipe 16. A barrier plate is provided inside the resistor 2 and a crescentic orifice is formed in the lower part thereof. In the gas liquid mixing pump 1, an annular fluid passage made narrower in the diameter direction is formed on the inner circumference of a casing and a many stirring blades projecting in the fluid passage are provided on the outer circumference of an impeller. The rotational speed of the gas liquid mixing pump 1 is controlled by an inverter 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for generating micro bubbles used for improving water quality and the like.

[0002]

2. Description of the Related Art Generally, microbubbles are generated by mixing a liquid and a gas, pressurizing them to dissolve the gas in the liquid, and then rapidly depressurizing the gas-liquid mixed fluid.
2. Description of the Related Art Conventionally, there is known a device that pressurizes a gas-liquid mixed fluid with a pump, restricts a discharge side pipe line of the pump with a valve, and discharges the gas-liquid mixed fluid that has passed through the valve from an aerator to generate microbubbles.

[0003]

However, this conventional device has the following problems. (1) When 7% to 8% or more of gas is mixed with the liquid, the discharge pressure of the pump decreases, so it is necessary to limit the mixing ratio of the gas, and the microbubble generation efficiency was poor. (2) In order to sufficiently dissolve the gas in the liquid, it is necessary to pressurize the gas-liquid mixed fluid in the pump and piping equipment for a long period of time, which increases the power consumption of the pump and is uneconomical. (3) Since the valve is provided on the discharge side of the pump, gas is accumulated on the upstream side of the valve, and large bubbles are mixed in the micro bubbles, which tends to cause non-uniformity.

Therefore, an object of the present invention is to provide an apparatus capable of economically and efficiently generating fine and uniform micro bubbles.

[0005]

In order to solve the above-mentioned problems, a micro-bubble generator of the present invention uses a gas-liquid mixing pump for sucking a mixed fluid of liquid and gas, and a discharge fluid of the gas-liquid mixing pump. A resistor for applying resistance and an inverter for controlling the rotation speed of the gas-liquid mixing pump are provided, and a narrow annular fluid passage is formed in the radial direction on the inner circumference of the casing of the gas-liquid mixing pump, and on the outer circumference of the impeller. The invention is characterized in that a large number of stirring blades projecting in the fluid passage are provided.

Here, in order that the gas-liquid mixing pump can efficiently pressurize and agitate the mixed fluid having a high gas mixture ratio of about 10%, and stably discharge it, the respective parts of the gas-liquid mixing pump are as follows. It is preferable to design (A) Design the thickness of the impeller to be 35 to 45% of the width of the pressure passage. (B) Design the outer diameter of the impeller to be 91% or more of the inner diameter of the casing. (C) Design the length of the stirring blade to be 4 to 6.5% of the outer diameter of the impeller. (D) Design the deviation between the center of the suction port and the discharge port and the center of the impeller to be 20% or less of the thickness of the impeller.

Further, it is desirable that a barrier plate is provided on the resistor and a half-moon shaped orifice is formed under the barrier plate in that fine and uniform micro bubbles can be generated.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the micro-bubble generating device of this embodiment generates a micro-bubble by applying a resistance to a gas-liquid mixing pump 1 for sucking a mixed fluid of liquid and gas and a discharge fluid of the gas-liquid mixing pump 1. It is provided with a resistor 2 for generating and an inverter 3 for controlling the rotation speed of the gas-liquid mixing pump 1.

A liquid suction pipe 6 and a suction pipe 7 are connected to a suction port 4 of the gas-liquid mixing pump 1 via a suction pipe 5. A vacuum gauge 8 is provided on the suction pipe 5, and the suction pipe 6
A suction pressure adjusting valve 9 is provided above. An air control unit 10 is provided on the intake pipe 7, and a flow rate adjusting valve 11, a flow meter 12, and a check valve 13 are built in the unit 10.

A discharge pipe 16 is connected to the discharge port 15 of the gas-liquid mixing pump 1, and a pressure gauge 17 and the resistor 2 are provided on the discharge pipe 16. As shown in FIG. 4, a barrier plate 18 that gives resistance to the discharge fluid is incorporated inside the resistor 2, and an orifice 19 that allows the discharge fluid to pass through is formed in the barrier plate 18. According to the resistor 2, micro bubbles can be generated with a simple and inexpensive structure.

The opening area of the orifice 19 is determined in consideration of the discharge pressure and discharge amount of the gas-liquid mixing pump 1, the passage area of the resistor 2, the generated pressure of microbubbles, and the like. Also,
The site and shape of the orifice 19 are determined in consideration of the fact that the gas in the mixed fluid is transformed into microbubbles efficiently and visually by the rapid depressurization. 4 to 7 show examples of the orifice 19 having the same opening area but different parts and shapes.

(1) The orifice 19 shown in FIG.
It is formed in the shape of a half moon at the bottom of. This orifice 19
Since it is open to the lower part of the barrier plate 18, the bubbles are aggregated in the upper part of the upstream side of the barrier plate 18 as a lump and enlarged to a certain volume, and then gradually discharged from the orifice 19. At this time, since the orifice 19 is opened at one corner of the barrier plate 18, the flow after passing through the orifice 19 becomes irregular, and during the non-rectification, large bubbles are repeatedly collided and finely crushed. Further, even if a gas mass generated due to unevenness in the middle of the pipe flows into the resistor 2, there is no possibility that the gas mass stays in the upper portion of the upstream side of the barrier plate 18 and passes through the orifice 19 as a mass. Therefore, there is an advantage that fine and uniform microbubbles having a good appearance can be generated.

(2) The orifice 19 shown in FIG.
It is formed in the shape of a half moon at the top of the. This orifice 19
Has an opening at one corner of the barrier plate 18, so that bubbles can be finely crushed, but since it opens at the upper part of the barrier plate 18, large bubbles are easily mixed into the microbubbles. (3) The orifice 19 shown in FIG. 6 is formed in a circular shape at the center of the barrier plate 18. According to this orifice 19, micro bubbles are generated, but the sizes of the bubbles are not uniform,
Especially large bubbles are noticeable. (4) The orifice 19 shown in FIG.
It is formed in one circular shape. Also in this case, as in FIG. 6, the bubble size is non-uniform and large bubbles are mixed. Therefore,
According to the orifice 19 shown in FIGS. 5, 6 and 7, there is a drawback that the appearance of the microbubbles becomes poor.

As shown in FIGS. 2 and 3, the gas-liquid mixing pump 1 has a structure similar to a cascade pump (overflow pump, Wesco pump). The casing 21 includes a main body portion 22 and a lid portion 23, and the main body portion 22 has a rotary shaft 2
4 is supported, and the impeller 25 is mounted on the rotary shaft 24.

An impeller 25 is provided on the main body 22 and the lid 23.
Protruding portions 22a and 23a are provided on both side surfaces of the casing 21 so as to face each other with a slit therebetween, and an annular fluid passage 26 that is narrow in the radial direction is formed on the inner periphery of the casing 21 on the outer peripheral side thereof.
A partition wall 23b projecting above the fluid passage 26 is formed on the inner periphery of the lid portion 23, and the suction port 4 is provided on both sides of the partition wall 23b.
The discharge port 15 communicates with the fluid passage 26.

A large number (for example, 60 on one side and 120 on both sides) of stirring blades 27 projecting into the fluid passage 26 are provided on the outer periphery of the impeller 25. Then, as the impeller 25 rotates, the gas-liquid mixed fluid is sucked from the suction port 4 by the frictional force of the stirring blade 27, pressurized and stirred on the fluid passage 26, and then discharged from the discharge port 15. There is.

The stirring blade 27 is formed by obliquely cutting both side surfaces of the outer peripheral portion of the impeller 25. Thereby, the width of the stirring blade 27 is designed to be equal to the thickness t of the impeller 25. Further, the inner diameter of the stirring blade 27 is designed to be equal to the inner diameter of the fluid passage 26.

The thickness t of the impeller 25 is designed to be 35 to 45% of the width M of the fluid passage 26. If it is 45% or more, when about 10% of gas is mixed, the discharge amount and discharge pressure become unstable, and the pressure may decrease over time, and discharge may become impossible. If it is 35% or less, 15% or more of the gas can be mixed, but the discharge amount of the pump is reduced.

The outer diameter d of the impeller 25 is the casing 21.
It is designed to be 91% or more of the inner diameter D of the (cover portion 23).
If it is less than 91%, the gas mixture ratio of 7 to 8% is the limit, and if a gas of more than that is mixed, the pressure will decrease over time, and ejection may be impossible.

The length h of the stirring blade 27 is designed to be 4 to 6.5% of the outer diameter d of the impeller 25. If it is 6.5% or more, when about 10% of gas is mixed, fluctuations in the discharge amount and the discharge pressure become large and unstable, and the pressure may decrease over time and discharge may become impossible. When it is 4% or less, 10 to 15% or more of gas can be mixed, but the discharge amount of the pump is reduced.

The centers of the suction port 4 and the discharge port 15 and the impeller 2
The deviation S from the center of 5 is designed to be 20% or less of the thickness t of the impeller 25. If it is 20% or more, when a gas of about 10% is mixed, the fluctuation of the discharge amount and the discharge pressure becomes large and unstable, which makes it difficult to handle the pump.

In the microbubble generator constructed as described above, the rotation speed of the gas-liquid mixing pump 1 is controlled by the inverter 3 and the discharge pressure of the pump 1 is measured by the pressure gauge 1.
The optimum pressure is adjusted according to the indicated value of 7. In this case, it is not necessary to provide a valve on the discharge pipe 16 of the gas-liquid mixing pump 1, and there is no possibility that the gas accumulated on the upstream side of the valve will become large bubbles and be mixed into the micro bubbles.

The suction pressure of the liquid is adjusted to the optimum pressure by the suction pressure adjusting valve 9 on the suction pipe 6 according to the value indicated by the vacuum gauge 8. Further, the gas suction amount is adjusted to about 10% of the pump discharge amount by the flow control valve 11 of the air control unit 10 according to the instruction value of the flow meter 12. Then, the mixed fluid of gas and liquid is automatically sucked into the pump 1 through the suction pipe 5 by the suction force of the gas-liquid mixing pump 1.

Therefore, the suction pressure (vacuum degree), the discharge pressure, and the gas amount (mixing ratio) of the gas-liquid mixed fluid are changed by adjusting the opening degree of both valves 9 and 11 and the frequency adjustment of the inverter 3, and the micro pressure is changed. The size and amount of bubbles can be optimally adjusted with simple operations. In addition, since the check valve 13 is provided in the air control unit 10, even if the pump 1 is stopped after the required gas amount is determined, there is no possibility that the liquid will flow backward, and the device can be operated under the same operating conditions. It has the advantage of being restartable.

The gas-liquid mixed fluid is sucked from the suction port 4 of the pump 1 into the fluid passage 26, where it is pressurized and stirred by the stirring blade 27, and the gas is crushed and simultaneously dissolved in the liquid. It is pressure-fed to the discharge port 15 side. According to the gas-liquid mixing pump 1 of this embodiment, the following operational effects can be obtained.

(1) Since the stirring blade 27 projects into the fluid passage 26, the fluid friction of the stirring blade 27 is increased to
It is possible to pressurize and agitate a gas-liquid mixed fluid having a high gas mixture ratio of about 0% in a short time, finely pulverize the gas and at the same time efficiently dissolve it in the liquid, and then discharge it at a high pressure. Therefore, the power consumption of the gas-liquid mixing pump 1 can be suppressed. (2) Since the fluid passage 26 is formed to be narrow in the radial direction, a high-speed swirl flow is generated in the passage 26 as the impeller 25 rotates, and the gas is rapidly stirred in this high-speed swirl flow while the casing 21 and the stirring blades are agitated. It can be repeatedly collided with 27 and finely crushed. (3) Since the fluid passage 26 is formed to be narrow in the radial direction, the passage length is extended compared to a pump having the same passage volume, the pressurization / stirring distance of the gas-liquid mixed fluid is secured to be long, and the gas is efficiently supplied. It can be crushed and dissolved.

(4) Since both side surfaces of the outer peripheral portion of the impeller 25 are obliquely cut and the stirring blade 27 is formed short, the volume of the groove of the cutting portion which acts to blow the mixed fluid by centrifugal force is reduced, It is possible to reduce the amount of gas that adheres and returns to it, and thus to prevent gas from staying on the suction port 4 side. (5) Since the centers of the suction port 4 and the discharge port 15 and the center of the impeller 25 are located in substantially the same plane, an equal amount of gas-liquid mixed fluid is supplied to the fluid passages 26 on both sides of the impeller 25. It can be introduced and uniformly pressurized and stirred.

The fluid discharged from the gas-liquid mixing pump 1 flows into the resistor 2 through the discharge pipe 16 and is pressurized on the upstream side of the barrier plate 18. The pressurization accelerates the dissolution of gas. Then, the discharged fluid passes from the lower portion of the barrier plate 18 through the half-moon shaped orifice 19, and repeatedly collides due to non-rectification under rapid depressurization to be transformed into uniform fine bubbles and discharged as micro bubbles.

The present invention is not limited to the above-described embodiment, and as illustrated below, the shape and configuration of each part may be appropriately changed without departing from the gist of the present invention. It is possible. (1) In the gas-liquid mixing pump 1 shown in FIG. 3, the impeller 2
5 Triangular section of the outer periphery is cut off, and each stirring blade 27
Should be provided separately from each other. (2) Design the width M of the stirring blade 27 to be slightly wider than the thickness t of the impeller 25. (3) The stirring blade 2 is provided on the inner peripheral surface of the lid portion 23 of the casing 21.
Providing a fixed blade facing 7 (4) A spiral stirring blade is provided inside the resistor 2.

[0030]

As described in detail above, according to the present invention,
The rotation speed of the gas-liquid mixing pump was controlled by the inverter, and the stirring blades of the impeller were projected into the narrow fluid passage in the radial direction of the pump casing. It exerts an excellent effect that the gas is finely pulverized by being pressured and stirred, and the gas is efficiently dissolved in the liquid, so that fine and uniform micro bubbles can be economically generated.

[Brief description of drawings]

FIG. 1 is an overall block diagram of a micro-bubble generator showing an embodiment of the present invention.

FIG. 2 is a front view showing a main part of a gas-liquid mixing pump.

FIG. 3 is a sectional view of the pump.

FIG. 4 is a sectional view of a resistor showing an orifice.

FIG. 5 is a sectional view showing another embodiment of the orifice.

FIG. 6 is a cross-sectional view showing another embodiment of the orifice.

FIG. 7 is a sectional view showing another embodiment of the orifice.

[Explanation of symbols]

1 ... Gas-liquid mixing pump, 2 ... Resistor, 3 ... Inverter, 4 ... Suction port, 5 ... Suction pipe, 15 ... Discharge port,
16 ... Discharge pipe, 18 ... Barrier plate, 19 ... Orifice, 21 ... Casing, 25 ... Impeller, 26 ... Fluid passage, 27 ... Agitation blade

Claims (6)

[Claims] 1. A gas-liquid mixing pump for sucking a mixed fluid of liquid and gas, a resistor for imparting resistance to the discharge fluid of the gas-liquid mixing pump, and an inverter for controlling the rotation speed of the gas-liquid mixing pump. A micro-bubble generating device characterized in that a narrow annular fluid passage is formed in an inner circumference of a casing of a gas-liquid mixing pump in a radial direction, and a large number of stirring blades projecting into the fluid passage are provided on an outer circumference of an impeller. 2. The thickness of the impeller is set to be 35 to 4 of the width of the fluid passage.
The microbubble generator according to claim 1, which is designed to be 5%. 3. The outer diameter of the impeller is 91 times the inner diameter of the casing.
The microbubble generator according to claim 1, which is designed to have a content of at least%. 4. The length of the stirring blade is 4 to the outer diameter of the impeller.
The microbubble generator according to claim 1, which is designed to be 6.5%. 5. The microbubble generator according to claim 1, wherein the center of the suction port and the discharge port of the gas-liquid mixing pump and the center of the impeller are designed to be 20% or less of the thickness of the impeller. 6. The microbubble generator according to claim 1, wherein the resistor is provided with a barrier plate, and a half-moon shaped orifice is formed in a lower portion of the barrier plate.