JPH11197491A - Method and device for treating fine particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating fine particles in which sample fine particles contained in sample fluid are continuously concentrated while controlling cavitation and to provide a device in which this technique is used. SOLUTION: A sample solution is introduced from a pipe 21 introducing sample fluid containing a fine particle component to a vessel 31. When ultrasonic wave with very slightly different frequency is irradiated respectively from ultrasonic sound sources 11 and 12 controlled by an ultrasonic wave generation control part 13, a node or an antinode of standing wave in the vessel moves in the direction of the ultrasonic sound source 12. Fine particles dispersed in the sample fluid are concentrated in the vicinity of the ultrasonic sound source 12. Two suction pipes 22 and 23 of the sample solution are fitted to the vicinities of the ultrasonic sound sources 11 and 12 in the downstream parts of the flow of sample fluid. Thereby, both the sample flow free from the fine particle component and the sample flow containing the fine particle component are taken out of the respective suction pipes 22 and 23. Accordingly, fine particles contained in fluid are concentrated and separated uncontactedly and continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a particle processing method and a particle processing apparatus, and more particularly to a particle processing method and a particle processing apparatus suitable for concentrating sample particles in a solution using ultrasonic waves.

[0002]

2. Description of the Related Art It has been known since the 19th century that particles in a fluid can be captured without contact by irradiating ultrasonic waves. When the radiation pressure of the ultrasonic wave is applied to the fine particles, the radiation pressure received by the fine particles is described, for example, by Jonle B.
Of Acoustic Society of America
89 (1991), pp. 2140-2143 (J.
Wu, J. Acoust. Soc. Am. 89 (1991) pp.2140-2143)
Report that a 270 μm diameter polystyrene sphere was successfully captured at the focal point of focused ultrasound. Regarding the principle of capturing fine particles by the radiation pressure of ultrasonic waves, Yoshioka et al.
(55) pp. 167-178 (K. Yosiokaand Y. Kaw)
asima, Acustica 5 (1955) pp.167-178), standing waves,
The magnitude of the ultrasonic radiation pressure received by the fine particles in the traveling wave is calculated in perfect fluid, and the ultrasonic radiation pressure received by the fine particles floating in the standing wave is the volume of the fine particles, the standing wave It is shown that it increases in proportion to the frequency of the ultrasonic wave to be formed. Also, as reported by the inventors in Japanese Patent Application Laid-Open No. 5-296310, a method of introducing ultrasonic waves into a tube through which a fluid is flown to continuously focus fine particles in a certain range, or A method of recovering the fine particles that have been made has also been invented.
As reported in Japanese Patent No. 1977, there has also been invented a fine particle fractionating apparatus for fractionating and collecting fine particles having different particle diameters and fine particles of different materials by combining the radiation pressure of ultrasonic waves and other external force such as an electrostatic field. ing.

It has long been known that, when the frequency of the ultrasonic wave used in the standing wave is gradually changed, the position of the node of the standing wave changes accordingly, and the fine particles move accordingly. Thomas Torto et al. Also published a journal on means for moving and concentrating fine particles trapped in nodes of standing waves by sweeping up and down the frequency of ultrasonic waves actually introduced into a fluid in which ultrasonic particles are dispersed. ·of·
Acoustic Society of America 9
1 (1992) 3152-3156 (TL
Tolt, J. Acoust. Soc. Am. 91 (1992) pp.3152-3156)
In the report. In addition, Ewald Venes and others
No. 5,225,089 (Benes et a) issued a patent relating to a means for concentrating fine particles by increasing the frequency of ultrasonic waves emitted from an ultrasonic irradiation source disposed in a flow path.
l., US Pat.No. 5,225,089, Dateof Patent Jul. 6, 1
993).

It has long been known that the position of a node of a standing wave can be controlled by controlling the phase of a pair of ultrasonic waves radiated to generate a standing wave. In addition, Cornelius Schramme also measures how to measure the physical properties of fine particles by actually applying this technology and observing how much the fine particles follow the movement of the position of the node of the standing wave. US Patent No. 4,74
No. 3,361 (CJ Schram, US Pat. No. 4,743,361,
Date of Patent May 10, 1988). It has long been known that when ultrasonic waves having slightly different frequencies are radiated opposite to each other, the position of a node of a generated standing wave advances due to the minute frequency difference.

[0005]

The above prior art is a technique in which ultrasonic waves are introduced into a solution containing sample fine particles to be concentrated, and the fine particles are concentrated at the nodes or antinodes of the standing wave generated in the solution. The fine particles in the solution are concentrated between the adjacent nodes of the standing wave formed in the solution or between the antinodes, and this width is half of the wavelength λ of the ultrasonic wave, that is, λ / 2.
be equivalent to. Therefore, in a container having a limited volume, when the width of the container is equal to λ / 2, one node or antinode is formed in the container, and all the particles in the container are concentrated in this node or antinode. Therefore, the concentration efficiency is maximized.
However, in this case, the fine particles have a certain distribution width around one node, and it is difficult to completely separate them.In addition, as the width of the flow path becomes wider, the frequency of the ultrasonic wave used must be reduced accordingly. There is. However, since the intensity of the ultrasonic radiation pressure has a linear relationship with the ultrasonic frequency to be used, the intensity of the ultrasonic radiation pressure decreases as the frequency of the ultrasonic wave used decreases. Also, the occurrence of cavitation that damages the sample is promoted as the frequency becomes lower, so that consideration must be given to cavitation suppression.

The present invention introduces an ultrasonic component having a frequency sufficiently higher than the frequency of an ultrasonic wave having a container width of λ / 2, and suppresses cavitation while producing a sample in a sample fluid. It is an object of the present invention to provide a method for treating fine particles that continuously concentrates fine particles and an apparatus using the method.

[0007]

According to the object of the present invention, an ultrasonic component having a frequency sufficiently higher than the frequency of an ultrasonic wave having a container width of λ / 2 is introduced by introducing an ultrasonic component into the sample fluid. In order to realize a method of treating fine particles that continuously concentrates fine particles, the present invention employs a plurality of standing waves generated by ultrasonic waves emitted from a pair of ultrasonic sources facing each other in a rectangular parallelepiped container. Means for slowly moving the sample fluid perpendicularly to the traveling direction of the sample fluid by making each frequency irradiated from the ultrasonic wave source slightly different. Further, in order to suppress the occurrence of cavitation, the present invention has means for using an ultrasonic frequency having a frequency of 500 kHz or more. Alternatively, before introducing the sample fluid into the container for irradiating the ultrasonic waves, a means for degassing dissolved air in the fluid is provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and apparatus for concentrating fine particles in an ultrasonic treatment apparatus according to the present invention will be described below with reference to the schematic diagram of the first embodiment shown in FIG. However, in FIG. 1, the upper surface of the container is seen through to make the structure inside the container easier to understand. In the present apparatus, a pair of ultrasonic sound sources 11 and 12 are arranged on two opposing surfaces of a rectangular parallelepiped container 31 so that the directions of the wave vectors of the ultrasonic waves irradiated to each other are 180 ° opposite to each other. Further, the sample solution is introduced into the container 31 from the tube 21 for introducing the sample fluid containing the fine particle component.

Each of the ultrasonic sound sources 11 and 12 controlled by the ultrasonic wave generation control unit 13

[0010]

(Equation 1)

[0011]

(Equation 2)

When an ultrasonic wave is irradiated, a standing wave in the container becomes

[0013]

(Equation 3)

[0014] Therefore, the nodes or antinodes of the created standing wave move in the direction of the ultrasonic

[0015]

(Equation 4)

As shown in the schematic diagram of FIG. 2, the node 41 of the standing wave generated by the ultrasonic sound sources 11 and 12 travels in the direction of arrow 51. Therefore,
The fine particles 61 dispersed in the sample fluid are first captured by the standing wave 41 when injected into the container 31. Next, as the solution proceeds downstream in the container, the fine particles 61 are gradually concentrated near the ultrasonic sound source 12 by the progress of the standing wave. Therefore, two sample solution suction pipes 22 and 23 are connected to the ultrasonic sound sources 11 and 1 downstream of the flow of the sample fluid, respectively.
By attaching the sample fluid in the vicinity of 2, a sample fluid containing no fine particle component and a sample fluid containing the fine particle component can be taken out from the respective suction pipes 22 and 23.

At this time, it is desirable that the frequency of the ultrasonic wave generated from the ultrasonic sound source be a frequency that is sufficiently shorter than the width of the region in the container where the standing wave is generated. In addition, the frequency used should be set to 5 to suppress the generation of cavitation that could damage the sample.
It may be used at a frequency of 00 kHz or more. This is because the peak pressure Pc of the ultrasonic cavitation threshold value is, with respect to the frequency f of the ultrasonic wave used,

[0018]

(Equation 5)

This is because there is such a relationship.

FIG. 4 is a schematic diagram of a second embodiment of the present invention. The sample fluid containing fine particles is first supplied to the degassing unit 7
1 to remove dissolved air components in the fluid. The deaeration unit 71 is connected to a vacuum pump 72 and is used to maintain the degree of vacuum in the deaeration unit. Next, the sample fluid from which the dissolved air has been removed is passed through the tube 24 to the container 3.
2 is introduced. The sample fluid introduced into the container 32 is
By the same mechanism as shown in the first embodiment, the fine particle component can be concentrated. The fluid containing no fine particle component is sucked from a tube 25 having a suction hole on the surface of the ultrasonic wave source 14, and the fluid containing the fine particle component is sucked from the ultrasonic wave source 15
Is sucked from a tube 26 having a suction hole on the surface of the tube. By having the suction part in the plane of the ultrasonic wave source in this way, the suction part will be directed in the same direction as the traveling direction of the ultrasonic wave,
It will face the normal direction to the nodal or antinode surface of the standing wave. As a result, in this embodiment, it is possible to effectively collect a portion containing the largest amount of fine particle components or a component containing the least amount of fine particle components in the fluid.

[0021]

As described above in detail, the use of the present invention has an effect that fine particles in a fluid can be concentrated and separated continuously without contact.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a first embodiment of the present invention.

FIG. 2 is a top sectional view of the device shown in FIG.

FIG. 3 is a schematic diagram showing a state in which sample particles are concentrated by ultrasonic waves emitted from opposed ultrasonic wave sources according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a basic configuration of a second embodiment of the present invention.

[Explanation of symbols]

11, 12, 14, 15 ... ultrasonic wave generating source, 13 ... ultrasonic wave generating control unit, 21, 22, 23, 24, 25, 26 ...
Pipes, 31, 32: container, 41: node of sound pressure of standing wave, 51
… The moving direction of the node of the sound pressure of the standing wave, 61… fine particles, 71…
Deaeration unit, 72 ... vacuum pump.

Claims (10)

[Claims] 1. A fluid containing fine particles is introduced into a rectangular parallelepiped container through which a fluid containing fine particles flows, and is placed in contact with the fluid in the container, so as to be orthogonal to the flow of the fluid, and
From each of the ultrasonic sources that generate ultrasonic waves having a frequency shifted from each other by a predetermined frequency from each of a pair of ultrasonic sources arranged so as to face each other, change the phase difference of the generated ultrasonic waves with time. By advancing the standing wave generated in the sound field of the fluid in a predetermined direction, the fine particles dispersed in the fluid are concentrated, and among the pair of ultrasonic generating sources arranged to face each other, An ultrasonic wave for irradiating the high-frequency ultrasonic wave of the other of the pair of ultrasonic wave sources by taking out a fluid component in which the fine particles are concentrated from the vicinity of an ultrasonic wave source for irradiating one of the low-frequency ultrasonic waves A method for treating fine particles, comprising taking out a fluid component in which the fine particles are diluted from the vicinity of a source. 2. A rectangular parallelepiped container for flowing a fluid containing fine particles,
A tube for introducing the fluid into the container, a pair of ultrasonic sources arranged in contact with the fluid in the container, arranged perpendicular to the flow of the fluid, and arranged to face each other; By generating ultrasonic waves having frequencies shifted from each other by a predetermined frequency from each of the ultrasonic generating sources, the phase difference of the ultrasonic waves generated from each of the ultrasonic generating sources is changed with time, and generated in the sound field of the fluid. By causing the standing wave to travel in a predetermined direction, an ultrasonic generation control unit that concentrates fine particles dispersed in the fluid, and one of a pair of ultrasonic generation sources arranged so as to face each other A tube for extracting a fluid component in which the fine particles are concentrated from the vicinity of an ultrasonic source that emits low-frequency ultrasonic waves, and an ultrasonic generator that emits high-frequency ultrasonic waves of the other of the pair of ultrasonic sources Near the source A tube for taking out a fluid component the fine particles is diluted from particle processing apparatus characterized by having. 3. The particle processing apparatus according to claim 2, wherein the frequency of the ultrasonic wave generated from the ultrasonic wave generation source is 500 kHz or more. 4. A tube for introducing a fluid containing fine particles,
3. The particle processing apparatus according to claim 2, further comprising a unit for degassing dissolved air in the fluid containing the particles. 5. The method according to claim 1, wherein said fluid is introduced into a rectangular parallelepiped container through which a fluid containing fine particles flows, and each of said pair of ultrasonic generators is disposed in contact with said fluid in said container and opposed to each other. By generating an ultrasonic wave having a frequency shifted by a predetermined frequency, a phase difference of the generated ultrasonic wave is changed with time from each of the ultrasonic wave generating sources, and a standing wave generated in the sound field of the fluid is predetermined. By traveling in the direction of the above, the fine particles dispersed in the fluid are concentrated, and an ultrasonic generation source that irradiates one of the pair of ultrasonic generation sources arranged so as to face each other with a low frequency ultrasonic wave. There is an ultrasonic generation source that takes out a fluid component in which the fine particles are concentrated from a suction port arranged on one surface of the rectangular parallelepiped and irradiates the other of the pair of ultrasonic generation sources with high-frequency ultrasonic waves. Taking out fluid component the fine particles are diluted from a suction opening arranged on one side of the cuboid, fine processing method characterized by. 6. A rectangular parallelepiped container for flowing a fluid containing fine particles,
A tube for introducing the fluid into the container, a pair of ultrasonic sources arranged in contact with the fluid in the container, and facing each other, and a predetermined frequency from each of the ultrasonic sources; By generating an ultrasonic wave having a shifted frequency, the phase difference of the ultrasonic waves generated from each of the ultrasonic generating sources is changed with time, and the standing wave generated in the sound field of the fluid proceeds in a predetermined direction. By doing so, an ultrasonic generation control unit that concentrates the fine particles dispersed in the fluid,
The fine particles are concentrated from a suction port arranged on one surface of the rectangular parallelepiped, which has an ultrasonic wave source for irradiating an ultrasonic wave of a low frequency of one of a pair of ultrasonic wave sources arranged so as to face each other. A pipe for taking out the fluid component
A tube for taking out the fluid component in which the fine particles are diluted from a suction port arranged on one surface of the rectangular parallelepiped, which has an ultrasonic wave source for irradiating the other high frequency ultrasonic wave of the pair of ultrasonic wave sources, A particle processing apparatus comprising: 7. The particle processing apparatus according to claim 6, wherein the frequency of the ultrasonic wave generated from the ultrasonic wave generation source is 500 kHz or more. 8. A tube for introducing a fluid containing fine particles,
7. The fine particle processing apparatus according to claim 6, further comprising: means for degassing dissolved air in the fluid containing the fine particles. 9. A rectangular parallelepiped container for flowing a fluid containing fine particles,
In contact with the fluid in the container, a pair of ultrasonic sources arranged so as to face each other, from each of the ultrasonic sources to generate ultrasonic waves having a frequency shifted from each other by a predetermined frequency, By changing the phase difference of the ultrasonic waves generated from the ultrasonic generation source with time and causing the standing wave generated in the sound field of the fluid to travel in a predetermined direction, the fine particles dispersed in the fluid are concentrated. A particle processing apparatus comprising: an ultrasonic generation control unit. 10. A tube for introducing a sample fluid containing fine particles into a container, first and second ultrasonic sound sources for irradiating ultrasonic waves of slightly different frequencies, and controlling the first and second ultrasonic sound sources. And a node or antinode of the standing wave in the container travels in the direction of the first ultrasonic sound source, and causes fine particles in the sample fluid to be in the vicinity of the first ultrasonic sound source. A fine particle processing apparatus, wherein the fine particles are taken out from a suction tube attached near the first ultrasonic sound source downstream of the flow of the sample fluid.