JPH05133683A - Drying device utilizing ultrasonic wave - Google Patents

Abstract

PURPOSE:To obtain a drying device utilizing ultrasonic wave, which is capable of removing moisture and the like contained in a specimen efficiently at a normal temperature in a short period of time to effect drying work. CONSTITUTION:Air stream is generated by a fan in the vicinity of a specimen to be dried while rectangular oscillating plates 2 are driven by ultrasonic driving sources 3, 4 so as to generate bending oscillation in the lengthwise directions thereof and radiate ultrasonic wave from the oscillating plates 2. Further, the ultrasonic wave, emitted from the oscillating plates 2, is reflected toward the specimen 1 by reflecting members 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying apparatus using ultrasonic waves for removing moisture and the like from a sample containing the moisture and performing drying and dehydration.

[0002]

2. Description of the Related Art Conventionally, as a method for removing moisture and the like from a sample containing moisture and drying and dehydrating the sample, heat is applied to the sample by a heater or the like to evaporate the moisture or the like, and the sample is blown by a blower or the like. There are methods such as applying a stream of air to evaporate water, etc., or to scatter water, exposing the sample to dry outside air, or forcibly separating water with a centrifuge or vibrator. It was A general drying oven uses these methods together, that is, air heated by a heater is applied to a sample by a blower to evaporate water and the like, and the sample is dried by applying force such as vibration and rotary stirring. Are being promoted.

[0003]

However, the above-described conventional drying furnace requires energy for heating, blowing, and exercising, and these energy is effectively used for drying water and the like contained in the sample. Not done,
There has been a problem that a large amount of energy is required to obtain a predetermined drying efficiency and running costs increase.
Also, the heated air is in a high temperature and high humidity state due to the evaporation of moisture from the sample, so it must be quickly removed from the vicinity of the sample, but the removed air is simply discharged to the outside of the room. Therefore, the reuse of heat energy has not been attempted, and this has also been a factor in raising running costs.

Further, depending on the properties of the sample, it is inevitable that the sample itself will be deformed by heating, its state will be changed, or the sample itself will be deformed by blowing air or vibration. In some cases, there is no choice but to loosen the amount of air and the amount of air blown. For example, when performing drying of perishables to be stored at a low temperature close to ice temperature, it is necessary to carefully heat the product so that the temperature rise does not exceed the spoilage temperature. However, if the amount of heating, the amount of air blown, etc. are made gentle, the drying efficiency will decrease correspondingly, and there has been a problem that a long drying time is required.

An object of the present invention is to provide a drying device using ultrasonic waves, which is capable of efficiently removing moisture and the like contained in a sample at room temperature and in a short time and performing a drying operation.

[0006]

To explain the present invention in association with FIG. 1 showing an embodiment, the present invention is applied to a drying device for removing water contained in a sample 1 to be dried and drying. It In the invention of claim 1, a blower for generating an air flow for discharging the water vaporized from the sample 1, a rectangular diaphragm 2, and the diaphragm 2 undergoes bending vibration in a longitudinal direction thereof. The ultrasonic driving sources 3 and 4 which are driven so as to radiate ultrasonic waves from the diaphragm 2, and the reflecting member 8 which reflects the ultrasonic waves radiated from both surfaces of the diaphragm 2 toward the sample 1. The above-mentioned object is achieved by providing. The invention according to claim 2 is the drying device according to claim 1, in which a plurality of the vibration plates 2 are arranged such that their surfaces are parallel to each other.

[0007]

The vibrating plate 2, which is driven by the ultrasonic driving sources 3 and 4 so as to cause bending vibration in the longitudinal direction, radiates ultrasonic waves to the surroundings. Part of the ultrasonic waves emitted from the diaphragm 2 travels directly toward the sample 1, and part of the ultrasonic waves is reflected by the reflector 8 and travels toward the sample 1. The ultrasonic waves propagated to the vicinity of the sample 1 vibrate the air near the surface of the sample 1 and forcibly replace the moist air in the saturated state of the surface layer of the sample 1 with the dry air to promote evaporation / drying. Further, the high sound pressure of the ultrasonic wave also affects the inside of the sample 1, and has the effect of moving moisture inside the sample to the vicinity of the surface and promoting drying. Then, the vapor such as the evaporated water is immediately removed from the vicinity of the sample 1 by the air flow of the blower and is discharged.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 are views showing an embodiment of a drying apparatus using ultrasonic waves according to the present invention, FIG. 1 is a plan view and FIG. 2 is a perspective view.

In these drawings, 1 is a sample to be dried containing water and the like, and 2 is a rectangular vibration plate arranged in the vicinity of the sample 1. In this embodiment, their surfaces are parallel to each other. The two diaphragms 2 are provided so that
Reference numeral 3 is an ultrasonic oscillator (driver) that generates ultrasonic vibrations, and 4 is a horn that transmits ultrasonic vibrations from the ultrasonic oscillators to the diaphragm 2. The horn 4 is the center of one of the diaphragms 2. It is fixed to the part. Reference numeral 5 is a joint fitting for connecting the two diaphragms 2 so that the center thereof vibrates at the position of maximum vibration amplitude.

The ultrasonic oscillator 3, the horn 4, and the joint fitting 5 drive the vibrating plate 2 so that bending vibration predominantly occurs in the longitudinal direction of the vibrating plate 2, and the vibrating plate 2 outputs a predetermined frequency ( Resonance frequency) ultrasonic waves are emitted, and from this viewpoint, the shape and material of the horn 4, the joint fitting 5, the shape and material of the diaphragm 2, the fixing position of the horn 4 and the joint fitting 5, and between the diaphragms 2. The distance, etc. are defined. Such a diaphragm 2, a vibrator 3, a horn 4 and a joint fitting 5 are called a stripe mode rectangular diaphragm type ultrasonic sound source, which was invented by the present inventors as an ultrasonic sound source of large capacity and high efficiency. (See, for example, The Acoustical Society of Japan, 23 , 3/4 merger, pp.83-91 (Sho 42) et al.). In this embodiment, the diaphragm 2, the horn 4, and the joint fitting 5 are made of aluminum alloy (duralumin, etc.) or titanium alloy, which has high fatigue strength and low loss.

Here, the bending vibration is a vibration in which a plate of an elastic body has a surface on which expansion and contraction does not occur and which is deformed so as to bend, and is also called flexural vibration. The bending vibration is generated by the bending wave propagating in a certain direction, and in the present embodiment, the bending wave propagates in the longitudinal direction of the diaphragm 2. A bending wave is a wave that propagates a bending deformation that occurs in a rod-shaped or plate-shaped elastic body, and is a kind of transverse wave in which a plate-shaped object is displaced in a direction perpendicular to a plane. FIG. 3 schematically shows bending vibrations and bending waves when the diaphragm is rectangular.

Reference numeral 6 is a generator for driving the ultrasonic vibrator 3, and drives the ultrasonic vibrator 3 so that the diaphragm 2 vibrates at a predetermined resonance frequency. At this time, since the resonance frequency including the ultrasonic transducer 3, the horn 4, the diaphragm 2, and the joint fitting 5 is changed due to the change of the ambient temperature, the generator 6 feeds back the vibration frequency from the horn 4 and outputs it. It has a frequency control function to keep it within a certain range. In this embodiment, the frequency of the ultrasonic wave radiated from the diaphragm 2 is 20 [kHz] ± 500 [H
z]. An amplifier 7 amplifies the drive signal from the generator 6. The output of the amplifier 7 is determined in relation to the size of the diaphragm 2, and is about 500 [W] in this embodiment.
Output is about 1000 [W].

Reference numeral 8 is an acoustic reflector, which is provided on the opposite side of the sample 1 with the diaphragm 2 in between. The reflecting plate 8 is made of a material having a good reflectance with respect to ultrasonic waves of a frequency emitted from the diaphragm 2. Further, the shape of the reflecting plate 8 is determined so that the ultrasonic waves emitted from the vibrating plate 2 have the same phase on each reflecting plate 8 and the ultrasonic waves are effectively reflected toward the sample 1. ing.
Further, the drying device of the present embodiment is provided with a blower (not shown), and this blower generates a low-speed airflow sufficient to discharge evaporated water in the direction of the arrow in FIG. 1 on the surface of the sample 1. ..

In the correspondence between the claims and the embodiments, the acoustic reflector 8 constitutes a reflecting member.

In the configuration described above, the ultrasonic vibrator 3 is driven via the generator 6 and the amplifier 7, and the ultrasonic vibration generated by the vibrator 3 is passed through the horn 4 and the joint fitting 5 to the diaphragm 2. Is transmitted to the diaphragm 2, the diaphragm 2 is driven so that bending vibration is predominantly generated in the longitudinal direction of the diaphragm 2, and ultrasonic waves are emitted. At this time, since the diaphragm 2 is formed in a rectangular shape in this embodiment, the ultrasonic sound field generated by the diaphragm 2 is as shown in FIG. 4 according to the research results of the present inventors. (For example, Journal of Acoustical Society of Japan, 32 ,
2, pp.83-91 (Sho 51)). Further, the amplitude of the diaphragm 2 at this time is as long as the thickness of the diaphragm 2 is about 1 to 5 [mm].
The vibration plate 2 is about 20 [μm] of aluminum alloy and about 30 [μm] of titanium alloy. According to the diaphragm 2 of this embodiment, the diaphragm having a size as shown in FIG.
It has been confirmed by experiments that the above sound pressure can be generated. For reference, the relationship between the sound pressure level and the effective value of the particle velocity is shown in FIG.

Part of the ultrasonic waves emitted from the diaphragm 2 travels directly toward the sample 1, and part of the ultrasonic waves is reflected by the reflector 8 and travels toward the sample 1. The ultrasonic waves propagated up to the vicinity of the sample 1 are 5 [m / m of the air near the sample 1 (and the air inside the sample 1 if the sample 1 is a porous material).
s] (when the sound pressure level is 160 [dB]) is vibrated at a particle velocity, and the saturated air in the surface layer of Sample 1 is replaced with dry air to evaporate and dry. At this time, it is clear from the experimental results by the present inventors that the temperature inside the sample 1 hardly increases. Then, the vapor such as the evaporated water is immediately removed from the vicinity of the sample 1 by the air flow of the blower and is discharged.

Therefore, according to the present embodiment, the air in the vicinity of the sample 1 is vibrated at a particle velocity of 5 [m / s] (when the sound pressure level is 160 [dB]) by the ultrasonic wave to saturate the surface layer of the sample 1. Since the sample 1 is dried by exchanging the air in the state with dry air, it is possible to remove water and the like more efficiently and dry the sample 1 as compared with the conventional drying furnace. That is, FIGS. 5 to 7 are diagrams showing the results of experiments by the present inventor, and as shown in FIG.
It can be understood that the removal rate of water when ultrasonic drying is added is significantly improved compared to the removal rate of water when air at room temperature is blown. As shown in FIG. 6, the efficiency of this ultrasonic drying can be shortened to 1/4 as compared with that at room temperature, and can be further shortened by using a warm air flow as shown in FIG.

Further, the main purpose of air blowing by the air blower is to remove air with high humidity existing in the vicinity of the sample 1, and since it is not necessary to increase the air blowing speed, it is possible to reduce the running cost. In addition, a sufficient drying effect can be obtained without applying vibration or rotary stirring force to the sample 1, so that running cost can be reduced also from this aspect.

Moreover, as described above, ultrasonic drying does not cause a rise in the temperature inside the sample, so that there is an excellent effect that the sample 1 can be dried at room temperature. As a result, it is possible to efficiently perform drying in a short time without causing deterioration in the drying of perishables and pharmaceuticals that are deteriorated by high temperature and in drying of materials that do not allow air to pass easily such as porous materials such as cotton fibers. Become.

In particular, in this embodiment, the ultrasonic wave radiated from the diaphragm 2 is propagated toward the sample 1 directly or by being reflected by the reflector 8 and the sample 1 is dried by this ultrasonic wave. Therefore, most of the radiated ultrasonic waves are used for drying the sample 1, and efficient drying operation can be performed from this aspect as well. Further, the diaphragm 2 and the like used in the present embodiment is the above-mentioned striped mode rectangular diaphragm type ultrasonic sound source, and since this kind of ultrasonic sound source is a large capacity and highly efficient ultrasonic sound source, from this aspect Can also perform efficient drying.

The details of the drying apparatus using ultrasonic waves of the present invention are not limited to the above-mentioned one embodiment, and various modifications can be made. As an example, the two diaphragms 2 are used in the embodiment, but the number of the diaphragms 2 is not limited, and for example, three or four diaphragms 2 may be provided as shown in FIG. Good. The diaphragm 2 of the present invention has certain conditions such as its dimensions due to the relationship of the resonance frequency, and cannot be unnecessarily widened. Therefore, by increasing the number of the diaphragms 2 instead of widening the diaphragm 2, it is possible to widen the drying range.

At this time, the joint metal fitting 5 connecting the diaphragms 2 is also subject to certain restrictions due to the relationship of the resonance frequency, but as shown in FIG. 13, a convex or concave step is formed in the central portion of the joint metal fitting 5. By providing it, the distance between the diaphragms 2 can be arbitrarily adjusted. That is, FIG. 14 (a)
In the case of a joint metal fitting 5 having a uniform cross-sectional shape such as, the length L ₀ of the joint metal fitting 5 is

[Equation 1] And is uniquely determined by f and c. Further, the distance between the diaphragms 2 is determined by the condition that the diaphragms 2 are connected so that the ultrasonic waves generated from the plurality of diaphragms 2 interfere with each other to strengthen each other. This distance is about 2 of the length of the short side of the diaphragm 2.
To be doubled.

Actually, when the joint fitting 5 is made of duralumin, the sound velocity of duralumin c = 5.0 × 10 ⁵
[cm / s], and assuming that the frequency of the ultrasonic wave generated by the generator 6 is f = 20 [kHz], the length L ₀ of one joint fitting 5 is

[Equation 2] Becomes Further, the number of joint fittings 5 required for connecting the diaphragms 2 can be calculated by substituting the values of the diaphragm shown in FIG.

[Equation 3] Becomes However, strictly speaking, when the length of the short side of the diaphragm 2 is 16.88 [cm], 3.7 [cm] is insufficient even if three joint fittings 5 having a length of 12.5 [cm] are connected. In addition, when the length of the short side is 19.31 [cm], connecting three joint metal fittings 5 having a length of 12.5 [cm] results in an extra 1.1 [cm]. Therefore, it is preferable that the length L of the joint fitting 5 can be arbitrarily set according to the distance between the diaphragms 2.

As shown in FIGS. 14 (b) and 14 (c), if the diameter of the joint metal fitting 5 is two steps (D ₁ , D ₂ ), its length L
Can be arbitrarily determined, and in this case, first, one diameter D ₁ is determined,

[Equation 4] To satisfy D ₂ and the length of each step (half)
It suffices to determine l ₁ and l ₂ . For example, when the length is made longer than the length L ₀ in the case of a uniform cross section (L> L ₀ ), the central portion may be a convex step as shown in FIG. On the other hand, when the length is made shorter than the length L ₀ in the case of a uniform cross section (L <L ₀ ), FIG.
As shown in (c), the central portion may be a concave step.

Further, the diaphragm 2 used in the drying apparatus of the present invention is not limited to a rectangular shape, and the diaphragm 2 may be formed in a cylindrical shape as shown in FIG. 9, for example. In the case of FIG. 9, since the sound field is focused on the center of the diaphragm 2, the sample 1 may be placed at this center. Further, the shape of the reflection plate 8 is not limited to the embodiment, and for example, an arc-shaped reflection plate 8 may be provided as shown in FIG. 10, or a plurality of mountain shapes with different angles as shown in FIG. The reflection plate 8 may be provided.

[0027]

As described above in detail, according to the present invention, the air near the sample is radiated by the ultrasonic waves emitted from the vibrating plate and directly directed to the sample, and reflected by the reflecting plate and directed toward the sample. The moisture in the saturated surface layer of the sample is forcibly exchanged with dry air to accelerate the evaporation of water, so that the removal and drying of water etc. can be performed more efficiently than with a conventional drying oven. In addition to being able to carry out, the running cost can be reduced. Moreover, since ultrasonic drying does not cause the temperature inside the sample to rise, it is possible to dry the sample at room temperature. Therefore, according to the present invention, it is possible to realize a drying apparatus using an ultrasonic wave capable of efficiently removing moisture and the like contained in a sample at room temperature and in a short time and performing a drying operation.

[Brief description of drawings]

FIG. 1 is a plan view showing a drying device using ultrasonic waves according to an embodiment of the present invention.

FIG. 2 is a perspective view of the same embodiment.

FIG. 3 is a diagram showing a vibration mode and a displacement distribution of a striped mode rectangular diaphragm.

FIG. 4 is a diagram showing the angle dependence of an ultrasonic sound field of a striped mode rectangular diaphragm.

FIG. 5 is a diagram showing the relationship between the weight of removed water and the elapsed time.

FIG. 6 is a diagram showing a relationship between water content of a sample and elapsed time.

FIG. 7 is a view similar to FIG.

FIG. 8 is a diagram showing a modification of the diaphragm.

FIG. 9 is a view similar to FIG.

FIG. 10 is a diagram showing a modified example of the reflection plate.

11 is a view similar to FIG.

FIG. 12 is a diagram showing an example of dimensions of a diaphragm.

FIG. 13 is a diagram showing a relationship between sound pressure and an effective value of particle velocity.

FIG. 14 is a diagram showing an example of a joint fitting.

[Explanation of symbols]

 1 sample 2 diaphragm 3 ultrasonic transducer 4 horn 5 joint fitting 6 generator 7 amplifier 8 reflector

Claims (2)

[Claims] 1. A blower for generating an air flow for discharging water vaporized from a sample to be dried, a diaphragm having at least two sides parallel to each other, and bending vibration in the longitudinal direction of the diaphragm. And an ultrasonic wave drive source that emits ultrasonic waves from the diaphragm, and a reflecting member that reflects the ultrasonic waves emitted from the diaphragm toward the sample. Drying device using sound waves. 2. The drying device according to claim 1, wherein a plurality of the vibration plates are arranged so that their surfaces are parallel to each other.