JP5547157B2 - Stirrer - Google Patents

Description

  The present invention generally relates to a stirring device. More specifically, the present invention relates to a stirring device that can efficiently stir a liquid in consideration of energy saving.

  The inventor has proposed various stirring devices that can efficiently stir a fluid without requiring a mechanical drive source (see Patent Documents 1 to 4).

Japanese Patent No. 3058876 Japanese Patent No. 4195782 Japanese Patent No. 4384477 Japanese Patent No. 4710070

  In the above-described stirring device, liquid or liquid can be stirred by constantly blowing gas or liquid into the liquid in the container. However, the present invention is not limited to the device proposed in the above-mentioned Patent Document, particularly Patent Document 1. An object of the present invention is to provide an apparatus that enables efficient stirring of liquid while considering energy saving.

With reference to FIG. 3, the operation principle of the stirring device of the present invention will be described. When a liquid is filled into a cylindrical container having a single-hole nozzle at the bottom, and a gas is blown into the liquid from the single-hole nozzle, a rising bubble jet is formed. In addition, it has been found that a swirling phenomenon that is favorable for stirring of the liquid occurs by the rising bubble jet under a certain condition. That is, there is an inner diameter of the cylindrical container D, with the difference in height between the single-hole nozzle and the liquid level to H _1, D and H ₁ relationship between about 0.3 <H ₁ / D <about 1 In some cases, a swirling phenomenon occurs in which the radial displacement of the bubble jet is relatively small and the cycle is short, and the liquid in the cylindrical container behaves like sloshing. Here, sloshing refers to a phenomenon in which vibration of a liquid is induced when a container is vibrated in an axial direction or a radial direction. The above-mentioned swirling phenomenon is presumed to be induced by periodic vibration from gas to liquid accompanying the generation and rise of bubbles.

In addition, when the present inventor ejects liquid from a single-hole nozzle into the liquid when the relationship between D and H ₁ is about 0.3 <H ₁ / D <about 1.7, an upward jet is formed. It has been found that the same phenomenon occurs as when the above gas is blown into the liquid.

  Since the above-mentioned swirl phenomenon is induced by periodic vibration of the liquid by bubbles (or liquid), in order to generate a swirl phenomenon that is preferable for stirring of the liquid, the gas (or liquid to be blown in) ) Is not less than the critical value and not more than the extent that bubbles (or liquid) blow through the liquid surface. The term “blow-through” used in this specification refers to a phenomenon in which gas (or liquid) blown into a liquid from a nozzle creates an air column (or liquid column) and exits from the liquid surface to the outside. I mean.

The inventor calculated the critical value of the flow rate of the gas (or liquid) as follows. According to the research on sloshing, it is said that a wave in the liquid surface is induced by the vibration of the container, and this wave is transmitted to the inside of the liquid through the viscosity, and the movement in the liquid occurs. Therefore, it is presumed that the turning stops when the wave phenomenon on the liquid surface is suppressed. According to the inventors' experiment, it can be concluded that the main part of the excitation force will be the force exerted on the liquid almost periodically as bubbles (or liquid) rise and exit the liquid surface. This force is assumed to depend on the inertial force of the rising liquid. Also, surface tension will be involved in the force to stop the wave motion. The present inventor has found that the swirling phenomenon that is preferable for the stirring of the liquid if the Weber number W _e = ρ _L Q ² / (σ _L D ³ ) defined as the ratio of the inertial force and the surface tension of the liquid is 10 ⁻⁵ or more. It was confirmed by experiment that this occurs. That is, the Weber number W _e = 10 ⁻⁵ in the above formula becomes a critical value. Here, ρ _L is the density of the liquid, Q is the gas flow rate (or the liquid ejection flow rate), σ _L is the surface tension of the liquid, and D is the inner diameter of the cylindrical container.

  On the other hand, when the liquid above the single-hole nozzle turns in one direction as indicated by the arrow A in FIG. 3B, the liquid below the single-hole nozzle is shown in FIG. As shown by the arrow B in FIG. The swirl flow B below the single-hole nozzle stabilizes the swirl flow A above the single-hole nozzle, and a decrease in the speed or turbulence of the swirl flow A occurs due to the injection of solid matter or the like into the swirl flow A. However, if the swirl flow B exists, the original state can be easily restored. For this reason, although not essential, it is preferable to provide a region having a certain depth below the single-hole nozzle.

  As described above, a liquid is filled into a cylindrical container having a single-hole nozzle at the bottom, and gas is blown into the liquid from the single-hole nozzle (or the liquid is ejected), so that the liquid can be obtained under certain conditions. It has been found that a favorable swirling phenomenon occurs in the agitation of this, but since this apparatus requires constant blowing of gas (or blowing of liquid), it is not necessarily satisfactory from the viewpoint of efficiency. It was hard to say that there was. Therefore, the present invention has developed an apparatus that satisfactorily stirs the liquid in the container without constantly injecting gas (or ejecting liquid).

  Since the swirling phenomenon of the liquid in the agitator described above is based on the premise that gas is blown into the liquid (or liquid is ejected), when a certain period of time elapses after the gas is blown (or liquid is ejected). The turning is expected to stop. In the present invention, focusing on this point, an apparatus has been developed that enables efficient stirring of liquid while considering energy saving by controlling the gas blowing time (or liquid blowing time).

  After the swirling phenomenon caused by the injection of gas into the liquid (or the injection of liquid) reaches a steady state, the vibration of the liquid in the container is observed after the injection of gas (or the injection of liquid) is stopped. The time until disappearance is defined as the turning stop time, and this turning stop time is obtained experimentally.

FIG. 4 shows an experimental apparatus used for this experiment. In the experiment, three types of acrylic cylindrical containers having an inner diameter D = 80 mm, 123 mm, and 200 mm were used, and air was controlled from a nozzle having an inner diameter d _n = 2 mm with a mass flow meter, and the flow rate Q _A = 20 to 300 cm ^3. Infused in the range of / s. In addition, since the dispersion | variation will become large when the measurement of turning stop time is performed visually, a probe was used. That is, a single needle probe was installed at a position 0.5 mm above the stationary liquid surface 5 mm inside from the side wall of the cylindrical container, and the output signal of this probe was recorded with a pen recorder. The electrode at the tip of the probe is periodically immersed in the liquid, and the output voltage at that time becomes 5V. However, when the swirling of the liquid stops, the output voltage becomes 0V over one period. Therefore, the time required for the output voltage to become zero is defined as the turning stop time T _{S, A.}

FIG. 5 shows the measurement results of this experiment, with the vertical axis representing the swirl stop time T _{S, A} (s) and the horizontal axis representing the blown gas flow rate Q _A (cm ³ / s). The measured values of D = 80 mm and 123 mm are slightly different because the gas blow-through occurs in the high gas flow rate region, but the turning stop time T _{S, A} becomes longer as the gas flow rate Q _A is larger. Yes. This is because the larger the gas flow rate Q _A is, the larger the kinetic energy of the liquid given from the gas is, and it takes time to stop the rotation.

FIG. 6 is an arrangement of the experimental measurement results using dimensionless numbers. In FIG. 6, the horizontal axis represents the dimensionless number Re ^1/2 · (H _L Q _A / D ^7/2 g ^1/2 ) obtained by dimensional analysis, and the vertical axis represents the dimensionless number T _{S, A} Q _A. / show the D ^3.
Here, Re [= (Q _A ² / g) ^2/5 (g / D) ^1/2 / ν _L ] is a measure of the expansion of bubbles in the radial direction (Q _A ² / g) ^{1 / 5} Reynolds number with ^1/2 (g / D) ^1/2 as the representative length and (Q _A ² / g) ^1/5 (g / D) ^1/2 as the representative speed. It is a dimensionless number that describes the motion of a liquid.
(G / D) ^1/2 is a measure of the turning cycle, g is the acceleration of gravity (mm / s ² ), ν _L is the kinematic viscosity (mm ² / s) of the liquid, and H _L is the water depth (mm). is there. H _L Q _A / D ^7/2 g ^1/2 is derived in consideration of the input energy per unit time of the following equation, and is a dimensionless number that describes the motion of the liquid excluding the bubble jet part. is there.
ε = (ρ _L −ρ _g ) · g · H _L · Q _A
T _{S, A} Q _A / D ³ is the reciprocal of the Strouhal number with the superficial velocity being the representative velocity.

From the experiment, the turning stop time T _{S, A} is obtained by the following equation (1).

T _{S, A} Q _A / D ³ = 11 Re ^1/2 · (H _L Q _A / D ^7/2 g ^1/2 ) (1)

However, 0.02 <Re ^1/2 · (H _L Q _A / D ^7/2 g ^1/2 ) <2

  In the above example, the swirl phenomenon is caused by blowing gas into the liquid from the nozzle, but swirling can also be performed by ejecting liquid from the nozzle into the liquid at a flow rate of a certain critical value or more instead of gas. A phenomenon can be caused. In gas injection, sufficient time is required for the buoyancy acting on the bubbles to induce the circulation of the liquid, whereas in the ejection of the liquid, the inertial force of the liquid can be used as it is. The time to reach is expected to be significantly shortened. In addition, in the agitation by blowing in gas, if the gas flow rate is increased, a blow-through phenomenon occurs.Therefore, it is predicted that the input energy cannot be used efficiently for the agitation. It is not.

  Similar to the example of gas blowing, after the swirling phenomenon caused by the ejection of the liquid into the liquid reaches a steady state, the time from when the ejection of the liquid is stopped until the vibration of the liquid in the container is not observed, The turning stop time is defined, and this turning stop time is obtained experimentally.

FIG. 7 shows an experimental apparatus used for this experiment. In the experiment, five types of acrylic containers having an inner diameter D = 100 mm, 130 mm, 150 mm, 200 mm, and 309 mm were used as the cylindrical container, and an inner diameter d _n = 5 mm, 10 mm as a nozzle installed at the bottom center of the cylindrical container. , 13 mm, and 15 mm were used. The periphery of the cylindrical container was covered with a container having a square cross section, and the space between them was filled with ion exchange water. Then, by adjusting the output of the pump at the inverter, to adjust the flow rate Q _L of blowing water. At that time, water was discharged from four drains provided at the bottom of the cylindrical container and circulated so that the water surface in the cylindrical container was constant. In the experiment, the water flow rate is set in the range of 0 to 750 cm ³ / s, the value obtained by dividing the water depth H _L by the inner diameter D of the cylindrical container is defined as the aspect ratio, and is changed in the range of 0 to 1.5. It was.

The vertical axis is the swivel stop time T _{S, L} , the horizontal axis is the jet water flow rate Q _L , FIG. 8A shows a cylindrical container, FIG. 8B shows a nozzle, and FIG. The experimental result according to aspect ratio is shown. It is considered that the swirl stop time T _{S, L} is hardly affected by the water flow rate, the nozzle inner diameter, and the aspect ratio, and depends only on the inner diameter D.

FIG. 9 is an arrangement of experimental measurement results using dimensionless numbers. In FIG. 9, the vertical axis represents the turn stop time T _{S, L} (s) made dimensionless by using the container inner diameter D (mm) and the gravitational acceleration g (mm / s ² ), and the horizontal axis represents the corrected Rossby number Ro. Indicates _m .
Here, modified Rossby number Ro _m is representative of a ratio between the inertia force of the liquid to pivot the inertial force with the jet, the turning stop time T _{S, L} does not depend on the modified Rossby number Ro _m, or less (2) can be approximated with a deviation of ± 25%.

T _{S, L} (g / D) ^0.5 = 500 (2)

^{_{Ro m = Q L 2 / (}} gd n 2 D 3)

A stirring apparatus comprising a cylindrical container having an inner diameter D or a polygonal container having a polygonal planar shape having an inscribed circle diameter D according to claim 1, wherein the container is to be stirred. A liquid is contained, and a nozzle for blowing a gas into or ejecting a liquid into the liquid is disposed at an approximate center of the container and oriented upward at a depth H ₁ from the liquid surface. The ratio H ₁ / D between the depth H ₁ and the inner diameter or the inscribed circle diameter D is in the range of 0.3 to _{1 in} the case of gas blowing, and in the range of 0.3 to 1.7 in the case of liquid ejection. And the flow rate Q of the gas blown into the liquid from the nozzle or the flow rate Q of the jetted liquid is ρ _L Q ² / (σ _L D ³ ) = 10 ⁻⁵ (where ρ _L is the density of the liquid , sigma _L is at least the flow rate satisfying the surface tension) of the liquid, and the liquid column of bubbles or liquid in the gas the liquid A stirrer having a flow rate that does not blow through the liquid surface is equal to or less than a flow rate, a valve for allowing or blocking air blowing or liquid blowing into the container, and a valve driving unit for opening and closing the valve. A valve control unit for outputting a valve open / close signal to the valve drive unit, and outputting a valve open signal or a valve close signal from the valve control unit to the valve drive unit according to a preset condition. It is configured to allow or block air blowing or liquid blowing,
When the preset condition is air blowing, after stopping the air blowing,
T _{S, A} Q / D ³ = 11Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 )
However, 0.02 <Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 ) <2
At the time T _{S, A} (where Re is the Reynolds number obtained by (Q ² / g) ^2/5 (g / D) ^1/2 / ν _L , g is the gravitational acceleration) ,
In the case of liquid ejection, after stopping the liquid ejection,
T _{S, L} (g / D) ^0.5 = 500
Time obtained by the T _S, during the course of the _L,
It is characterized by restarting air blowing or liquid blowing .

A stirring apparatus comprising a cylindrical container having an inner diameter D or a polygonal container having a polygonal planar shape with an inscribed circle diameter D according to claim 2 , wherein the container is to be stirred. A liquid is contained, and a nozzle for blowing a gas into or ejecting a liquid into the liquid is disposed at an approximate center of the container and oriented upward at a depth H ₁ from the liquid surface . The ratio H ₁ / D between the depth H ₁ and the inner diameter or the inscribed circle diameter D is in the range of 0.3 to _{1 in} the case of gas blowing, and in the range of 0.3 to 1.7 in the case of liquid ejection. And the flow rate Q of the gas blown into the liquid from the nozzle or the flow rate Q of the jetted liquid is ρ _L Q ² / (σ _L D ³ ) = 10 ⁻⁵ (where ρ _L is the density of the liquid , sigma _L is at least the flow rate satisfying the surface tension) of the liquid, and the liquid column of bubbles or liquid in the gas the liquid A stirrer having a flow rate that does not blow through the liquid surface is equal to or less than a flow rate, a valve for allowing or blocking air blowing or liquid blowing into the container, and a valve driving unit for opening and closing the valve. A valve control unit for outputting a valve open / close signal to the valve drive unit, and outputting a valve open signal or a valve close signal from the valve control unit to the valve drive unit according to a preset condition. It is configured to allow or block air blowing or liquid blowing, and when the preset condition is air blowing, after the air blowing is stopped,
T _{S, A} Q / D ³ = 11Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 )
However, 0.02 <Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 ) <2
From the time T _{S, A} (where Re is (Q ² / g) ^2/5 (g / D) ^1/2 / ν _L and g is the gravitational acceleration) At the time
In the case of liquid ejection, after stopping the liquid ejection,
T _{S, L} (g / D) ^0.5 = 500
When a desired time elapses from the time T _{S, L} obtained by
It is characterized by restarting air blowing or liquid blowing .

  According to the stirring device of the present invention, depending on the application, the gas or the liquid is blown only when necessary without blowing the gas or the liquid at all times. Can be implemented. Since the stirring device of the present invention does not require a drive source such as a propeller, the structure is extremely simple. Therefore, the manufacturing cost and maintenance cost of the device can be kept low, and the time and labor required for maintenance and inspection can be reduced. Can be reduced.

1 is an overall schematic diagram showing a stirring device according to a preferred embodiment of the present invention. It is a schematic diagram for demonstrating the operation | movement aspect of the stirring apparatus of FIG. It is a figure for demonstrating the principle of operation of the stirring apparatus of FIG. It is the figure which showed the experimental device implemented in order to obtain | require the rotation stop time in the case of blowing in gas in the stirring apparatus of FIG. It is the graph which showed the measurement result of the experiment implemented using the experimental apparatus shown in FIG. It is the graph which arranged the measurement result of FIG. It is the figure which showed the experimental apparatus implemented in order to obtain | require the rotation stop time in the case of making a liquid eject in the stirring apparatus of FIG. It is the graph which showed the measurement result of the experiment implemented using the experimental apparatus shown in FIG. It is the graph which arranged the measurement result of FIG.

Next, a stirring device according to a preferred embodiment of the present invention will be described with reference to the drawings. A stirrer according to a preferred embodiment of the present invention generally indicated by reference numeral 10 in FIG. 1 includes a cylindrical container 12 having a side wall 12a and a bottom wall 12b. The inner diameter of the cylindrical container 12 is D as shown in FIG. A liquid to be stirred is contained in the cylindrical container 12 so that the height from the bottom wall 12b to the liquid level is H ₁ + H ₂ .

Near the center of the bottom wall 12b of the cylindrical container 12, a nozzle 14a oriented upward at a depth H ₁ from the liquid surface is disposed, and an air introduction pipe 14 extending from the nozzle 14a includes an air compressor. (Not shown). Thereby, air is blown into the liquid from the nozzle 14 a via the air introduction pipe 14.

The ratio H ₁ / D between the depth H ₁ from the liquid level to the nozzle 14 a and the inner diameter D of the cylindrical container 12 is in the range of about 0.3 to about 1. Preferably, the ratio H ₁ / D is about 0.5.

  The stirring device 10 also includes a valve 16 disposed in the air introduction pipe 14, a valve drive unit 18 for driving the valve 16 to open and close, and a valve control unit 20 for outputting a valve open / close signal to the valve drive unit 18. It has. The valve controller 20 outputs a valve open signal or a valve close signal to the valve drive unit 18 according to preset conditions, thereby driving the valve drive unit 18 to open and close the valve 16 to thereby open the cylinder from the nozzle 14a. Air can be blown into the shaped container 12 or stopped. The valve 16, the valve drive unit 18, and the valve control unit 20 may be of a known type.

FIG. 2 is a schematic diagram for explaining an operation mode of the stirring device 10. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the degree of swirling of the liquid in the cylindrical container 12. Also, <1> on the horizontal axis in FIG. 2 is the time when the air starts to be blown into the liquid, <2> is the time when the swirling phenomenon of the liquid reaches a steady state, and <3> is the air flow into the liquid. When the blowing is stopped, <4> indicates the time when the liquid swirling phenomenon stops. Therefore, the time from <3> to <4> is the turning stop time T _{S, A.}

In the operation of the agitator 10, the air blowing resumption timing is the following three types.
(A) When the turning of the liquid stops after stopping the blowing of air, the blowing of air is resumed almost simultaneously (see FIG. 2B).
In this case, after stopping the blowing of air, the blowing of air is resumed when the time T _{S, A} that satisfies the above equation (1) has elapsed.
(B) After the air blowing is stopped and the swirling of the liquid is stopped, the air blowing is resumed after a predetermined time t has elapsed (see FIG. 2C).
In this case, after stopping the blowing of air, the blowing of air is resumed after the elapse of time T _{S, A} + t that satisfies the above equation (1).
(C) Air blowing is stopped and air blowing is resumed before the liquid rotation stops (see FIG. 2D).
In this case, after stopping the blowing of air, the blowing of air is resumed before the time T _{S, A} that satisfies the above equation (1) elapses.
Which of (A) to (C) is set can be selected as desired by the user depending on the use of the stirring device or the like, but the case of (C) is most preferable.

  By repeatedly stopping and restarting air blowing, efficient liquid agitation is achieved while saving energy (reducing the amount of air blown, reducing air blowing power, etc.) compared to the case of constantly blowing air. can do.

  Although the stirring device 10 has been described in relation to the case where air is blown, a gas other than air may be blown, or a liquid may be blown instead of air.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say, it is something.

  For example, in the above-described embodiment, the planar shape of the cylindrical container 12 is a circle, but a polygonal container (not shown) whose planar shape is an n-gon (n ≧ 3) is used instead of the cylindrical container 12. May be. In this case, D is the diameter of an inscribed circle of n-gon.

DESCRIPTION OF SYMBOLS 10 Stirrer 12 Cylindrical container 14 Air introduction pipe 14a Nozzle 16 Valve 18 Valve drive part 20 Control means

Claims (2)

A stirrer provided with a cylindrical container having an inner diameter D or a polygonal container having a polygonal plane shape with an inscribed circle diameter D, in which the liquid to be stirred is contained, substantially at the center of the container, is oriented upward at a depth H ₁ from the liquid surface, the nozzle is arranged for ejecting the blown or liquid gas in the liquid, the depth H ₁ and the inner diameter or inner The ratio H ₁ / D with the contact circle diameter D is in the range of 0.3 to _{1 in} the case of gas blowing, and in the range of 0.3 to 1.7 in the case of liquid ejection, and the liquid is discharged from the nozzle. The flow rate Q of the gas blown into or the flow rate Q of the jetted liquid is ρ _L Q ² / (σ _L D ³ ) = 10 ⁻⁵ (where ρ _L is the density of the liquid and σ _L is the surface tension of the liquid. ) And a flow rate that does not blow through the liquid surface of the liquid. In the stirring apparatus or less,
A valve for allowing or blocking air blowing or liquid blowing into the container;
A valve drive unit for opening and closing the valve;
A valve control unit for outputting a valve opening / closing signal to the valve driving unit,
By outputting No. valve open signal or the valve closing signal to the valve drive unit from the valve control unit, it is configured to or block allow ejection of blowing or liquid in the air in accordance with conditions set in advance ,
When the preset condition is air blowing, after stopping the air blowing,
T _{S, A} Q / D ³ = 11Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 )
However, 0.02 <Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 ) <2
At the time T _{S, A} (where Re is the Reynolds number obtained by (Q ² / g) ^2/5 (g / D) ^1/2 / ν _L , g is the gravitational acceleration) ,
In the case of liquid ejection, after stopping the liquid ejection,
T _{S, L} (g / D) ^0.5 = 500
Time obtained by the T _S, during the course of the _L,
A device characterized by resuming air blowing or liquid blowing . A stirrer provided with a cylindrical container having an inner diameter D or a polygonal container having a polygonal plane shape with an inscribed circle diameter D, in which the liquid to be stirred is contained, substantially at the center of the container, is oriented upward at a depth H ₁ from the liquid surface, the nozzle is arranged for ejecting the blown or liquid gas in the liquid, the depth H ₁ and the inner diameter or inner The ratio H ₁ / D with the contact circle diameter D is in the range of 0.3 to _{1 in} the case of gas blowing, and in the range of 0.3 to 1.7 in the case of liquid ejection, and the liquid is discharged from the nozzle. The flow rate Q of the gas blown into or the flow rate Q of the jetted liquid is ρ _L Q ² / (σ _L D ³ ) = 10 ⁻⁵ (where ρ _L is the density of the liquid and σ _L is the surface tension of the liquid. ) And a flow rate that does not blow through the liquid surface of the liquid. In the stirring apparatus or less,
A valve for allowing or blocking air blowing or liquid blowing into the container ;
A valve drive unit for opening and closing the valve ;
A valve control unit for outputting a valve opening / closing signal to the valve driving unit ,
By outputting a valve opening signal or a valve closing signal from the valve control unit to the valve driving unit, the air blowing or the liquid blowing is allowed or blocked according to preset conditions. ,
When the preset condition is air blowing, after stopping the air blowing,
T _{S, A} Q / D ³ = 11Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 )
However, 0.02 <Re ^1/2 · (H ₁ Q / D ^7/2 g ^1/2 ) <2
From the time T _{S, A} (where Re is (Q ² / g) ^2/5 (g / D) ^1/2 / ν _L and g is the gravitational acceleration) At the time
In the case of liquid ejection, after stopping the liquid ejection,
T _{S, L} (g / D) ^0.5 = 500
When a desired time elapses from the time T _{S, L} obtained by
A device characterized by resuming air blowing or liquid blowing .

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