JPH05317606A - Ultrasonic defoaming device and continuous defoaming method using this device - Google Patents

Abstract

PURPOSE:To improve the consumption unit of liquid at the time of cyclically using a foamable liquid and to prevent the pollution of an ambient environment. CONSTITUTION:The foam building up on a liquid surface is detected by a foam detecting sensor 42. Ultrasonic waves are emitted from an ultrasonic transmitter 46 by the foam detection signal from the foam detecting sensor 42 to destroy the froth on the liquid surface. This ultrasonic defoaming device is provided in the middle of a circulating pipeline. As a result, the need for the defoaming liquid is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic defoaming device and a continuous defoaming method using the same, and more particularly, to improving the basic unit of liquid when circulating a foaming liquid and preventing environmental pollution. The present invention relates to a suitable ultrasonic defoaming device and a continuous defoaming method using the same.

[0002]

2. Description of the Related Art Conventionally, when circulating a foaming liquid,
A general circulation line as shown in FIG. 1 was used.

In this circulation line, the liquid is stored in the reserve tank 10, the pressure is raised by the liquid feed pump 14 from the liquid feed nozzle 12 provided in the lower portion of the reserve tank 10, and the liquid passes through the liquid feed line 16. And is pumped to the liquid use place 18. The remaining liquid used at the liquid use place 18 is pressurized again by the return pump 20 and returned to the reserve tank 10 through the return pipe line 22.

Such foaming in the circulation pipe mainly occurs between the liquid use place 18 and the return pipe 22, and the liquid mixed with the foam returns to the reserve tank 10. Therefore, if the circulation is continued, the reserve tank 10 will be discharged. The space is filled with bubbles and overflows from the opening 10A. The bubbles of the effervescent liquid were hard to disappear even when they went out of the tank, and the surroundings were contaminated, and the leakage continued, resulting in a large loss of the liquid.

Conventionally, as a countermeasure against this, as shown in FIG. 2, a nozzle 1 for discharging bubbles is attached to a lid 11 of a reserve tank 10.
1A was provided, the foam was guided to the adjacent defoaming tank 24, and the defoaming liquid was sprayed from the nozzle 24A to break the foam (break the foam). As the defoaming liquid, water or a circulating liquid was used.However, when water is used, the liquid mixed with water cannot be reused, so the loss of the liquid is unavoidable, and even if the circulating liquid itself is used, it is not Bubbles remained and again it was difficult to reuse.

In addition to the above, as a method and apparatus for spraying a liquid to destroy bubbles, Japanese Patent Laid-Open No. 123100/123100 discloses that the bubbles of the treatment liquid generated during the cleaning of the steel sheet are of the same type as this treatment liquid and By injecting a lower temperature processing liquid,
It has been proposed to effectively defoam to prevent the bubbles from flowing out and to collect them as a treatment liquid. Further, as the same type, in Japanese Patent Laid-Open No. 3-153887, the upper layer portion of a foamed alkali cleaning liquid which is washed with oil stains of a metal material is introduced into an overflow tank, and the foamed portion in the overflow tank is atomized. A method has been proposed in which water is sprayed to defoam the foamed portion while maintaining the cleaning property of the alkaline cleaning liquid in the storage tank.

Further, as a device for mechanically breaking bubbles,
Japanese Examined Patent Publication No. 2-20001 with a motor provided with blades,
Installed in a float with legs arranged at the outer periphery of the plate blades at intervals, the floating vane defoaming device that rotates the plate blades in the space closest to the water surface removes bubbles generated on the water surface. A defoaming device has been proposed that defoams by colliding with a blade.

Further, as a combination of a method of mechanically breaking bubbles and a method of spraying a liquid to break bubbles,
In JP-A-64-56897, the plating solution is sprayed on the bubbles on the upper surface of the plating solution and the bubbles are stirred to surely eliminate the bubbles of the fine particle dispersion type electroplating solution, and to continuously use the plating bath for a long time. A method for enabling the above is proposed.

In addition to this, a bubble separating device for separating bubbles from a liquid has been proposed in Japanese Patent Laid-Open No. 52-20703.

[0010]

As described above, various measures have been proposed. However, in either case, the device is complicated or the effect is insufficient, so that the simplicity and the certainty of the effect are not ensured. There was a problem in terms.

In recent years, the diversification of the types of circulating liquids has been extremely remarkable, and the proportion of foaming liquids such as resin-based materials has also increased, and the demand for continuous defoaming devices for circulation lines has increased. ing.

The present invention has been made in view of such a situation as described above, and can be easily adopted in existing equipment, and there is no contamination of the surroundings, and an ultrasonic wave capable of improving the basic unit of circulating fluid is used. An object is to provide a defoaming device and a continuous defoaming method using the same.

[0013]

SUMMARY OF THE INVENTION The present invention provides an ultrasonic defoaming apparatus which uses a bubble detection sensor for detecting the presence of bubbles rising on the liquid surface and a bubble detection signal from the bubble detection sensor. The object is achieved by including an ultrasonic wave transmitter that irradiates ultrasonic waves to destroy bubbles on the liquid surface.

Further, in a continuous defoaming method of a piping path in which a foaming liquid in a reserve tank is pressure-fed by a liquid-feeding pump, a part of it is used, and the rest is returned to the reserve tank by a return pump for cyclical use. , A bubble-removing tank is provided in the middle of the circulation line to release the pressure of the liquid, keep the liquid level constant, and detect bubbles that grow and rise on the liquid surface with the bubble detection sensor. By the bubble detection signal,
The same problem was achieved by intermittently irradiating ultrasonic waves from an ultrasonic transmitter installed above the liquid level to defoam, and returning the defoamed liquid to the reserve tank by its own weight without pressure feeding. It is a thing.

[0015]

In the present invention, the presence of bubbles rising on the liquid surface is detected by the bubble detection sensor, and the ultrasonic wave is emitted from the ultrasonic transmitter according to the bubble detection signal from the bubble detection sensor. I try to destroy the bubbles. Therefore, it is possible to break bubbles with a relatively simple configuration that only requires a bubble detection sensor and an ultrasonic transmitter, and can be easily adopted in existing equipment.
Bubbles do not leak out and contaminate the surrounding area. Furthermore,
Since the defoaming liquid is unnecessary, the unit consumption of the circulating liquid can be improved.

According to the present invention, the foam generated in the system is not returned to the reserve tank, but a defoaming tank is provided in the middle of the circulation line to release the pressure of the liquid and keep the liquid level constant. Let the bubbles grow freely. Next, the raised bubble is detected by the bubble detection sensor, and the ultrasonic wave is intermittently emitted from the ultrasonic transmitter installed above the liquid surface toward the bubble by the bubble detection signal from the bubble detection sensor. When foaming is performed and the foam is suppressed to a certain level and returned to the reserve tank by its own weight without sending the defoamed liquid under pressure, it is possible to ensure continuous defoaming of the circulation line. Moreover, when returning from the defoaming tank to the reserve tank, foaming does not occur again by a pump or the like.

The reason for irradiating the ultrasonic waves intermittently instead of continuously is that defoaming can be achieved in an extremely short time by using ultrasonic waves having an appropriate output and frequency, and If you continue to irradiate meaninglessly, instead of foaming,
This is because aggregation of dissolved components, which is another action of ultrasonic waves, causes adverse effects such as having an adverse effect on the liquid composition, and also shortens the life of the ultrasonic vibrator.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The first embodiment of the present invention is as shown in FIG.
Reserve tank 10, liquid feed pump 14, liquid feed line 16,
The defoaming tank 30 according to the present invention is provided with the treated liquid between the return pipe 22 and the reserve tank 10 in the same circulation pipe as the conventional one having the liquid use place 18, the return pump 20 and the return pipe 22. The defoaming tank 30 is provided at a level necessary for returning to the reserve tank by its own weight, and the defoaming tank 30 and the reserve tank 10 having a closed structure are connected by a siphon pipe 34.

On the side surface of the defoaming tank 30, there is provided a bubble detection sensor 42 for detecting the rise of bubbles from the liquid surface to a certain height and generating a bubble detection signal. As the bubble detection sensor 40, for example, a photoelectric sensor or a capacitance sensor that detects transmitted light can be used.

The ultrasonic transmitter 4 including an ultrasonic vibration element 48 and a horn 50 is provided above the defoaming tank 30.
6 is attached to face the liquid surface. This horn 5
0 is manufactured in a shape that resonates at the frequency of the ultrasonic wave supplied from the ultrasonic transmitter 44.

Further, near the liquid surface in the defoaming tank 30, a reflection screen 52 having a through hole through which bubbles can pass.
Is provided so as to cover the entire liquid surface. The reflective screen 52 for mechanically separating the liquid and the bubbles may be in the liquid or on the liquid surface. The distance between the reflection screen 52 and the tip surface (the lower surface in the figure) of the horn 50 of the ultrasonic transmitter 46 is set at 1 of the ultrasonic transmission frequency so that a standing wave is generated between the reflection screen 52 and the horn 50. The distance is set to an odd multiple of / 4 wavelength.

The operation of the embodiment will be described below.

The chemical liquid in the reserve tank 10 is carried to the liquid use place 18 by the liquid feed pump 14 and used. The used chemical liquid is returned to the defoaming tank 30 by the return pump 20. At this time, bubbles are mainly generated between the liquid use place 18 and the return pipe line 22.

Therefore, bubbles are generated on the liquid surface of the chemical solution collected in the defoaming tank 30, and when the bubble detection sensor 42 detects that the amount of the bubbles has increased to a certain height, ultrasonic waves are transmitted. The electric energy of ultrasonic waves is applied from the container 44 to the ultrasonic vibration element 46, and the ultrasonic vibration element 46 vibrates at the corresponding frequency. Since the horn 50 is manufactured in a shape that resonates at this frequency, the ultrasonic vibration is amplified and the pressure amplitude of the ultrasonic wave is applied to the liquid surface from the tip surface of the horn 50.

Since bubbles on the liquid surface in the defoaming tank 30 are pushed up by the chemical liquid containing bubbles and new bubbles which are sequentially sent, the bubbles on the upper side have a longer standing time. The bubble film (foam film) 50 generally has the drainage action shown in FIG. 4, and the film thickness becomes thinner and weaker during the drainage work as the bubble film with time elapses, and finally the electrical repulsion between the molecules. The strength of the foam film is maintained by the force. Therefore, it is easier to rupture the bubbles when the ultrasonic waves are applied after the bubbles grow and the film becomes thinner, than when the bubbles immediately after the generation are irradiated with the ultrasonic waves.

Then, the bubble detection sensor 42 indicates that the bubbles in the defoaming tank 30 increase with time and the height thereof increases.
And sends a transmission command to the ultrasonic transmitter 44.

As shown in FIG. 5, the ultrasonic transmitter 44 intermittently oscillates ultrasonic waves, and in synchronization with this, ultrasonic wave pressure amplitude is emitted from the tip surface of the horn 50. Since the pressure amplitude of the applied ultrasonic waves is close to a plane wave and has a sharp directivity, it overlaps with the pressure amplitude reflected by the reflection screen 52, and a standing wave as shown in FIG. 6 is generated. Therefore, if the pressure at the antinode of the standing wave is equal to or higher than the strength of the foam film, the foam there is destroyed and returns to the original liquid.

If the distance between the horn 50 and the screen 52 is properly selected, a plurality of antinodes of the pressure amplitude of the standing wave are generated, so that the amount of bubble breakage increases. In addition, due to the above-mentioned drainage action, the upper liquid is more likely to be broken.

Here, the reason why the ultrasonic wave is intermittently radiated is
This is because the pressure amplitude of ultrasonic waves is so strong that if irradiation is continued even after foam breaking, cavitation will occur in the liquid and foaming will be promoted.

When the bubbles are broken and the bubbles are reduced as described above, the bubble detection signal output from the bubble detection sensor 42 is turned off, and the transmission of ultrasonic waves is stopped.

Thereafter, this operation is repeated.

The chemical solution that has been defoamed in the defoaming tank 30 returns to the reserve tank 10 through its siphon tube 32 by its own weight and is circulated.

Next, the second embodiment of the present invention will be described in detail.

In this second embodiment, the defoaming tank 30 used in the same circulation path as in the first embodiment is shown in FIG.
As shown in FIG. 5, the reflection screen 52 is omitted, and the liquid surface 32 in the defoaming tank 30 is used to reflect ultrasonic waves.

In the second embodiment, a standing wave effective for breaking bubbles does not occur unless the distance between the tip surface of the horn 50 and the liquid surface 32 is an odd multiple of 1/4 wavelength. Therefore, in the second embodiment, the level of the liquid surface 32 is constantly monitored by the liquid level detector 60, and the contact 62 is closed when the liquid surface 32 becomes an odd multiple of ¼ wavelength. Further, when the bubble detection sensor 42 detects a bubble in this state, the contact 64 is closed,
The ultrasonic wave irradiation command of the ultrasonic wave transmitter 44 is turned on, the intermittent irradiation in FIG. 5 is started, and the bubbles are broken until the output of the bubble detection sensor 42 or the liquid level detector 60 is turned off.

In this second embodiment, the defoaming tank 3
It is not necessary to provide the reflective screen 52 in 0.

Next, a third embodiment of the present invention will be described in detail.

In the third embodiment, as shown in FIG. 8, an ultrasonic transmitter 46 is provided in the return conduit 22 without using the defoaming tank 30 in the same circulation conduit as the conventional one. It is a thing.

In the third embodiment, a flow sensor 70 and a reflection screen 52 are provided from the upstream side in the middle of the return pipe 22 in a horizontal state, and the end face of the return pipe 22 is T-shaped, An ultrasonic transmitter 46 is provided at a position facing the reflection screen 52. The distance between the tip surface of the horn 50 and the reflection screen 52 is a distance that is an odd multiple of a quarter wavelength of the ultrasonic oscillation frequency, as in the first embodiment.

In the third embodiment, when liquid is sent by the return pump, bubbles are always mixed therein, so the flow rate sensor 70 as a bubble detection sensor detects the presence of the chemical liquid, Send a transmission command to the ultrasonic transmitter. Then,
A standing wave is generated between the reflection screen 52 and the tip surface of the horn 50, and the bubbles passing through the reflection screen 52 are broken. The liquid medicine returned to the liquid is dropped into a reserve tank and is circulated for use.

According to the third embodiment, there is no need to provide a defoaming tank, and it is only necessary to provide the reflection screen 52, the ultrasonic transmitter 46, etc. in the middle of the return conduit 22, so that the present invention can be applied to existing equipment. Is extremely easy.

[0043]

As described above, according to the present invention, it is not necessary to open the reserve tank and the defoaming tank, and the leakage of bubbles is eliminated, so that the contamination of the surroundings can be completely prevented.
Further, since the liquid after the foam breaking can be reused, the unit consumption is improved. Furthermore, the structure is simple and can be easily adopted in existing equipment. Further, when the ultrasonic waves are intermittently applied, there is an excellent effect that the running cost is extremely low.

[Brief description of drawings]

FIG. 1 is a pipeline diagram showing the configuration of a general circulation pipeline.

FIG. 2 is a sectional view of an essential part showing the configuration of an example of a conventional defoaming device.

FIG. 3 is a pipeline diagram showing a configuration of a circulation pipeline in which the first embodiment of the ultrasonic defoaming apparatus according to the present invention is adopted.

FIG. 4 is a diagram for explaining the principle of the present invention.

FIG. 5 is a time chart showing the irradiation state of ultrasonic waves in the example of the present invention.

FIG. 6 is a diagram for explaining a generation state of a standing wave in the above embodiment.

FIG. 7 is a sectional view showing the structure of a defoaming tank according to a second embodiment of the present invention.

FIG. 8 is a sectional view showing the configuration of the main parts of a third embodiment of the present invention.

[Explanation of symbols]

 10 ... Reserve tank 14 ... Liquid feed pump 16 ... Liquid feed pipe 18 ... Liquid use place 20 ... Return pump 22 ... Return pipe 30 ... Defoaming tank 32 ... Liquid level 34 ... Siphon pipe 42 ... Bubble detection sensor 44 ... Super Sound wave transmitter 46 ... Ultrasonic wave transmitter 52 ... Reflective screen 60 ... Liquid level detector 70 ... Flow rate sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiyuki Iwatani 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (no address) Inside the Mizushima Steel Works, Kawasaki Steel Co., Ltd. (72) Inventor Shigeyoshi Adachi Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Prefecture 1-chome (no street number) Kawasaki Steel Co., Ltd. Mizushima Works

Claims (7)

[Claims] 1. A bubble detection sensor for detecting the presence of bubbles rising on a liquid surface, and an ultrasonic wave which is irradiated with ultrasonic waves by a bubble detection signal from the bubble detection sensor to destroy bubbles on the liquid surface. An ultrasonic defoaming device, comprising: a sound wave transmitter. 2. The ultrasonic defoaming device according to claim 1, wherein the ultrasonic wave is intermittently applied. 3. The ultrasonic defoaming device according to claim 1, wherein the ultrasonic wave is irradiated after the bubble has grown and the foam film has become thin. 4. The ultrasonic transducer according to any one of claims 1 to 3, wherein the ultrasonic transducer is disposed so as to face a liquid surface, and an ultrasonic standing wave is generated between the liquid surface and the transducer. , An ultrasonic defoaming device characterized by breaking bubbles in its belly. 5. The method according to any one of claims 1 to 3,
A reflecting plate having a through hole through which the bubbles can pass is arranged to face the oscillator, and a standing wave of ultrasonic waves is generated between the reflecting plate and the oscillator, and the bubbles are broken in the belly. Ultrasonic defoaming device. 6. The ultrasonic defoaming device according to claim 5, wherein the reflection plate is disposed at a liquid surface position. 7. A continuous defoaming method for a piping path, wherein a foaming liquid in a reserve tank is pressure-fed by a liquid feed pump, a part of the liquid is used, and the rest is returned to the reserve tank by a return pump for circulation. , A defoaming tank is installed in the middle of the circulation line to release the pressure of the liquid, keep the liquid level constant, and detect bubbles that grow and rise on the liquid level with the bubble detection sensor. A bubble detection signal is used to intermittently irradiate ultrasonic waves from an ultrasonic transmitter installed above the liquid surface to defoam, and the defoamed liquid is returned to the reserve tank by its own weight without pressure feeding. Continuous defoaming method in circulating circulation line.