JPH0566514B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for producing ultrafine frozen particles.

(Prior art) Various structures have been proposed as devices for producing frozen grains such as fine ice grains used as abrasive grains and polishing materials for surface treatments such as blasting and cleaning. However, generally, as shown in FIG.
A sprayer 5 to which a supply pipe 3 for supplying a liquid to be frozen such as water and a drive gas introduction pipe 4 are connected is disposed on the top of the unit, and the liquid to be frozen is mixed with the drive gas introduced from the introduction pipe 4. By spraying from the sprayer 5 toward the liquid surface of the refrigerant 2, the atomized liquid to be frozen, that is, the fine liquid 6a... is frozen by heat exchange with the refrigerant 2, and fine frozen particles 6b... are obtained. It is normal to configure it like this.

(Problems to be Solved by the Invention) In the conventional device having such a configuration, the fine droplet liquid 6a is obtained by the atomizing action of the drive gas, so there is a limit to the work that can be done to reduce the diameter of the atomizing nozzle. Naturally, there is a limit to the miniaturization of the particle size of the fine particle liquid 6a, and at most the lower limit of the particle size is
It is only possible to produce frozen particles 6b of about 30 μm.

Therefore, since the frozen particles 6b which can be produced by the conventional apparatus as described above have a particle size within a relatively large range of 30 μm or more, the problem remains that the range of use thereof is inevitably limited. In particular, in recent years, by spraying ultra-fine frozen material onto the surface of the workpiece, it has become possible to remove fine foreign matter, dust, crushed pieces, burrs, etc. that adhere to various surfaces, which was previously considered difficult, and especially for delicate or delicate objects. The possibility of cleaning, blasting, etc. of items that require precision processing has opened up, and for this reason, there has been a strong demand for the production of ultrafine frozen particles with a particle size of several μm.
Despite such demands, conventional devices have not been able to meet these demands.

Moreover, in the conventional device, as mentioned above, the fine particle liquid 6
Since the particle size of a to frozen particles 6b is relatively large at about 30 μm, the amount of solidification heat per unit particle size is large,
Since the heat exchange efficiency with the refrigerant 2 is low and a relatively long cooling time is required, in order to ensure freezing, the temperature difference between the liquid to be frozen or the particulate liquid 6a... and the refrigerant 2 must be made considerably large. This has led to problems such as the need for a special pre-cooling device for rapidly cooling the liquid 3 to be frozen, which leads to an increase in the size of the entire manufacturing device and an unavoidable increase in cost.

By the way, if the mixing ratio of the drive gas to the liquid to be frozen in the sprayer 5 is made extremely large,
Although it is possible to promote the atomization of the liquid to be frozen by spraying, the minimum particle size is to produce frozen particles 6b with a particle size of about 5 to 10 μm, and in this case, it is necessary to produce a fine particle liquid with a uniform particle size. 6a... Therefore, it was difficult to obtain frozen grains 6b... For example, if water is used as the liquid to be frozen and nitrogen is used as the drive gas, and the volume ratio of gas to water is increased to reduce the particle size to about 5 μm,
The volume ratio is calculated as 1:1900, and an increase in the drive gas will inevitably lead to a dramatic increase in the amount of refrigerant 2 used, which will significantly reduce the refrigerant usage per unit amount of frozen particles 6b. Since this increases the number of particles and makes industrialization economically difficult, it cannot be practically adopted as a solution to the above-mentioned technical problems.

In view of the actual state of the prior art, the present invention provides ultrafine particles suitable for removing fine foreign matter, dust, debris, burrs, etc. from various surfaces, cleaning delicate or precision-processed articles, and blasting. An object of the present invention is to provide an apparatus for producing ultrafine frozen grains that can easily and reliably obtain frozen grains having a uniform particle size.

(Means for Solving the Problems) In order to achieve the purpose of solving the above-mentioned problems, the apparatus for producing ultrafine frozen particles of the present invention includes a sealed container containing a liquid to be frozen, and an ultrasonic wave applied to the liquid to be frozen. an ultrasonic means that generates and suspends ultrafine mist, which is a mist-like ultrafine liquid, in the sealed container by applying vibrational energy; The apparatus includes a transfer means and a freezing means for freezing the ultrafine mist transferred by the transfer means by heat exchange with a refrigerant.

(Function) According to this configuration, by applying ultrasonic vibration energy to the liquid to be frozen in the sealed space above the surface of the liquid to be frozen in the closed container, the atomizing action by the drive gas in the conventional device is improved. It is possible to generate and suspend uniformly ultrafine frozen liquid droplets in the form of a mist, that is, ultrafine mist, which would otherwise be impossible to obtain. This ultra-fine mist is transferred outside the sealed container and can be frozen as a mist-like fine particle through heat exchange with the refrigerant, resulting in uniform ultra-fine particles that were considered impossible with conventional equipment. (Particle size 3μ
It became possible to obtain frozen grains, that is, ultra-fine frozen grains of about 1.0 m). In this case, the ultrafine mist that is frozen by heat exchange with the refrigerant is obtained only by the action of vibrational energy from ultrasonic waves, and is ultrafine with a uniform particle size. The heat exchange efficiency of the refrigerant is dramatically high, and it is possible to reliably and rapidly freeze the refrigerant without a large temperature difference between the refrigerant and the refrigerant.

(Example) Hereinafter, the structure of the present invention will be specifically explained based on each example shown in FIGS. 1 to 3.

In the manufacturing apparatus of the first embodiment shown in FIG.
11 is a closed container, 12 is an ultrasonic means, 13 is a transfer means, and 14 is a freezing means.

A predetermined amount of a frozen liquid 16 such as water supplied from a frozen liquid supply pipe 15 is stored in the sealed container 11, and a sealed space 11a of a predetermined capacity is provided above the liquid level. Note that the liquid level height of the liquid to be frozen 16 is maintained within a certain range by controlling the opening and closing of the electromagnetic valve 15a according to the value detected by the liquid level detector 29.

The ultrasonic means 12 moves the liquid to be frozen 16 in the closed container 11
It consists of a vibrator 17a that sends ultrasonic waves into the space 11a and its control device 17b.By sending the ultrasonic waves from the vibrator 17a into the liquid to be frozen 6, the liquid to be frozen is introduced into the space 11a by the action of the vibration energy. Ultra-fine mist 16a with uniform particle size and ultra-fine particles...
It is configured to generate. Note that the frequency of the ultrasonic wave emitted from the vibrator 17a is
It is desirable to set the settings appropriately depending on the properties of the liquid to be frozen 16, the diameter of the desired fine particles, the temperature, and other conditions. For example, when the liquid to be frozen is water, liquefied nitrogen is used as the refrigerant to form the desired ultrafine frozen particles. In an example in which the diameter is 3 μm, the frequency should be approximately 1700 Hz at a water temperature of 30°C.

The transfer means 13 may be one in which a transfer gas supply pipe 18 and a transfer pipe 19 are respectively connected to the upper part of the closed container 11 and communicate with the space 11a. By supplying the transfer gas, the ultrafine mist 16a generated in the space 11a is transferred to the outside of the closed container 11 via the transfer pipe 19, with the mist carried on the wind along with the transfer gas. good.

Alternatively, as shown in FIG. 4, a fan 31 may be provided within the system for transfer. In the above embodiment, the pressure of the transfer gas supplied from the transfer gas supply pipe 18 was set to about 100 mm of water column pressure.

The freezing means 14 includes a frozen grain production container 21 containing a predetermined amount of a refrigerant 20 such as liquefied nitrogen, and an air outlet 2 connected to the transfer pipe 19 in the upper part of the container 21.
2, the ultrafine mist 16a sent along with the transfer gas inside the transfer pipe 19 is transferred to the air outlet 22.
By blowing it out toward the refrigerant 20, the ultra-fine frozen particles 16b are frozen by heat exchange with the refrigerant 20. In addition, frozen grain production container 2
1 is provided with a frozen particle removal means 23 such as a screw conveyor extending from the inside of the refrigerant 20 to an upper part outside the container 21, and takes out the ultrafine frozen particles 16b . , used as abrasive grains for blasting, etc.

According to the manufacturing apparatus configured as above, ultrafine mist 16a having a uniform particle size is obtained by the ultrasonic means 12, and is frozen by heat exchange with the refrigerant 20, so that the liquid to be frozen is It is possible to produce ultra-fine and uniformly sized frozen material 16b (approximately 3 μm in particle size), which was completely impossible with the conventional method of atomizing and freezing with a drive gas. .

Moreover, since the particle size is extremely small, the efficiency of heat exchange with the refrigerant 20 is extremely high, making it possible to significantly reduce the size and simplicity of the entire device compared to conventional devices, and reduce costs. The reduction is also significant. For example, in the conventional device shown in FIG. 6, it is necessary to pre-cool the liquid to be frozen in a pre-cooling device before supplying it to the sprayer 5, and the cooling area, that is, the ejection surface of the sprayer 5 and the liquid level of the refrigerant 2, However, in the embodiment of the present invention, there is no need to install such a precooling device, and the distance H between the outlet 22 and the refrigerant 20 may be 100 to 200 mm. Furthermore, in conventional methods, the liquid to be frozen is often sprayed in a conical shape from a nozzle, as shown in Figure 6.
In many cases, it was necessary to increase the diameter of the container 1, but in the case of the present invention, it is sufficient to simply blow out the atomized liquid to be frozen, and the diameter of the frozen particle production container 21 is also relatively small. It's okay. Therefore, the entire manufacturing apparatus including the frozen grain manufacturing container 21 can be drastically downsized and simplified, and it is easy to avoid adhesion of frozen substances to the inner surface of the container 21.

In addition, in the manufacturing apparatus according to the present invention, as described above, the efficiency of heat exchange with the refrigerant is extremely high, and the liquid to be frozen 16 becomes ultra-fine and becomes atomized before the freezing process by the freezing means 14. Because there are
As in the second or third embodiment described below, by devising the configuration of the freezing means 14, the pumping energy by the transfer means 13 can be directly used as frozen particle injection energy for blasting, cleaning processing, etc. It is also possible. Furthermore, liquefied nitrogen 20 as a refrigerant is added to the ultrafine mist 1.
By directly exchanging heat with 6a..., the ultra-fine frozen particles 16b...
Therefore, the liquefied nitrogen 20 changes from a liquid to a gas, and this gas can be directly used as injection energy.

That is, in the manufacturing apparatus of the second embodiment shown in FIG. 2, the overall pressure including the pumping force of the transfer means 13 is set to a high pressure of about 2 to 10 kg/cm ² , and the freezing means 14 is Different from the first embodiment, it is composed of a nozzle pipe 24 connected to the transfer pipe 19 and a spray pipe 25 for spraying refrigerant into the nozzle pipe 24, and the other configurations are the same as in the first embodiment. And so.

According to this manufacturing apparatus, the ultrafine mist 16a transferred from the transfer pipe 19 into the nozzle pipe 24...
The spray pipe 25 is located within the pumping region within the nozzle pipe 24.
After being frozen by exchanging heat with the sprayed refrigerant, the particles are injected from the nozzle pipe 24 onto the object to be treated as ultra-fine frozen particles 16b.

Furthermore, in the manufacturing apparatus of the third embodiment shown in FIG. A vibrator 28a that emits ultrasonic waves and a control device 28b thereof are provided at the bottom, and the other configurations are the same as those of the second embodiment. Note that the liquid level height of the refrigerant 20 is maintained within a certain range by controlling the opening and closing of the solenoid valve 33a of the refrigerant supply pipe 33 according to the value detected by the liquid level detector 32.

When such a manufacturing apparatus is used, ultrafine refrigerant 20a is generated in the upper space 26a of the closed container 26 in the form of a mist due to the action of ultrasonic waves. Thereafter, the ultrafine frozen particles 16b... are injected from the nozzle pipe 24 by the same action as in the second embodiment.

As described above, in an embodiment having a configuration such as the second or third embodiment, the vaporized gas after exchanging the heat of the refrigerant with the pumping energy by the transfer means 13 is used to inject the ultrafine frozen particles 16b... onto the object to be processed. The conveyor 23 for taking out finely frozen particles can be used as a jetting force in the conventional method or as in the embodiment shown in FIG.
Such means can be omitted, and an extremely simple blasting device can be provided.

In each of the above examples, the liquid to be frozen may include various liquids such as water, fruit juice liquid, chemical liquid, liquefied carbon dioxide, chlorine, ammonia, and fluorocarbon-based liquefied gas, depending on the purpose of the frozen particles. Can be used.

Further, as the refrigerant, liquefied nitrogen, liquefied carbon dioxide, liquefied air, liquefied oxygen, liquefied argon gas, liquefied freon gas, etc. can be used. When using liquefied gas such as liquefied carbon dioxide, it is desirable that the closed containers 11 and 26 be constructed as vacuum insulated containers.

In each of the embodiments described above, the ultrafine mist 16a is transferred to the outside of the container 11 via the transfer pipe 19 by supplying a transfer gas into the container 11 from the transfer gas supply pipe 18. However, as shown in FIG.
By blowing air into the container 1, the ultrafine mist 16a carried by the wind is transferred to the container 1 via the transfer pipe 19.
1 may be transferred outside.

When using the manufacturing apparatus according to the present invention, by changing the frequency of the ultrasonic waves sent into the liquid to be frozen 16 by the vibrator 17a,
The particle size of b can be adjusted as appropriate. for example,
When producing frozen particles using the apparatus of the present invention using water as the liquid to be frozen and liquefied nitrogen as the refrigerant, the particle size of the ultrafine frozen particles (μ
When the relationship between the two was plotted with m) on the hard axis and the frequency (Hz) of the ultrasonic wave generating vibrator on the horizontal axis, a graph as shown in FIG. 5 was obtained. Freezing liquid,
If you prepare the experimental data by changing the refrigerant, oscillator frequency, and temperature and plotting in the same way,
Conditions such as obtaining frozen particles of a desired particle size can be easily found.

(Effects of the Invention) The apparatus for producing ultrafine frozen particles of the present invention applies ultrasonic action to the liquid to be frozen, thereby uniformly turning the liquid into ultrafine particles and exchanging heat with the refrigerant while suspended in a mist. Because of this structure, it is possible to easily and reliably produce uniform and ultra-fine frozen particles that cannot be obtained with conventional equipment, and it is possible to easily realize ultra-precision processing using frozen particles, which has been particularly strongly demanded in recent years. It becomes a means to obtain.

Moreover, since the ultrafine liquid or ultrafine frozen particles are uniform and ultrafine, the efficiency of heat exchange with the refrigerant is extremely high, so the configuration of the freezing means can be significantly simplified and the entire device can be made compact. This invention is industrially valuable because it can be miniaturized and the cost can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional side view showing one embodiment of the manufacturing apparatus according to the present invention, FIG. 2 is a view similar to FIG. 1 showing another embodiment, and FIG. 3 is a diagram showing still another embodiment. 1, FIG. 4 is a schematic longitudinal sectional side view of the main part showing a modified example of the transfer means, and FIG. 5 is a graph showing the relationship between the frequency of the vibrator and the particle size of frozen particles. , FIG. 6 is a diagram similar to FIG. 1 showing a conventional manufacturing apparatus. 11... Airtight container, 12... Ultrasonic means, 13
...Transfer means, 14...Freezing means, 16...Liquid to be frozen, 16a...Ultrafine mist, 16b...Ultrafine frozen particles.

Claims (1)

[Claims] 1. An airtight container containing a liquid to be frozen, and ultrasonic means for generating and suspending ultrafine mist, which is an atomized ultrafine liquid, in the airtight container by applying ultrasonic vibrational energy to the liquid to be frozen. , comprising a transfer means for transferring the suspended ultrafine mist to the outside of the closed container in an air current, and a freezing means for freezing the ultrafine mist transferred by the transfer means by heat exchange with a refrigerant. Features: Ultra-fine frozen grain manufacturing equipment.