JP2017109145A - Particle separation method and particle separation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle separation method which can relax applicable conditions.SOLUTION: A particle separation method includes: a step S3 of making water 3 generate air as air bubbles B by irradiation with ultrasonic waves based on a first condition, and keeping a mixed particle group GA containing a first particle P1 and a second particle P2; a step S4 of stopping keeping of the mixed particle group GA by irradiation with ultrasonic waves based on a second condition; and a step S5 of making water 3 generate air as air bubbles B by irradiation with ultrasonic waves based on a third condition, keeping a first particle group G1 containing the first particle P1 at a first antinode position VB1 of the ultrasonic waves, and keeping a second particle group G2 containing the second particle P2 at a second antinode position VB2 of the ultrasonic waves.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a particle separation method and a particle separation apparatus for separating different particles contained in a liquid.

  The process of separating solid particles according to their characteristics is called a solid-solid separation process (see Non-Patent Document 1). As solid-solid separation processes, for example, classification, multiple selection, specific gravity selection, magnetic selection, and the like are known. Classification uses the difference in particle motion in the fluid to separate the particles by their size. In the double selection, two types of particles having different densities are separated by using a liquid having an intermediate value of the densities. Specific gravity sorting uses the sedimentation velocity caused by the difference in density for separation. In magnetic separation, particles are separated using a magnetic force acting on particles arranged in a magnetic field.

  Moreover, the process which isolate | separates a solid-liquid mixture into a solid component and a liquid component is called a solid-liquid separation process (refer nonpatent literature 2). Known solid-liquid separation processes include, for example, sedimentation separation, filtration and centrifugation. Sedimentation separation utilizes the sedimentation phenomenon of particles suspended in a liquid. Filtration uses a filter medium to separate insoluble substances suspended in the liquid into supplemental particles and filtrate. Centrifugation separates particles using centrifugal force.

  In addition, a technique for promoting separation and improving accuracy and efficiency by adding an operation of adding a chemical or the like to these methods is also known.

Nikkan Kogyo Shimbun, Ltd. Particle Dispersion / Agglomeration and Separation in Liquid Phase Chapter 4 Nikkan Kogyo Shimbun, Ltd. Particle Dispersion / Agglomeration and Separation Operation in the Gas Phase Chapter 5-7 Mitome, H., 2001. Micro-bubble and sonoluminescence. Jpn. J. Appl. Phys. 40, 3484-3487.

  However, application conditions are imposed on the various separation techniques described above.

For example, sedimentation separation utilizes sedimentation or flotation of particles due to the difference between particle density and liquid density. Therefore, when the density difference between the particles and the liquid is small, it is difficult to separate the particles. As an example, since the density difference is small between polystyrene particles (density: 1.05 g / cm ³ ) and water (density: 0.998 g / cm ³ ), it is difficult to separate water and polystyrene particles by sedimentation separation. In sedimentation separation, it is also difficult to classify particles having the same density and different diameters by particle diameter.

  Separation membranes and filtration capture particles larger than the joints of the membrane as they pass through the membrane to separate the liquid and particles. Moreover, the particle | grains from which particle diameter differs can also be isolate | separated by selecting suitably the magnitude | size of a joint. However, every time a liquid containing particles passes through the film, the particles remain on the film and accumulate, so that periodic maintenance of the film is necessary.

  Centrifugation uses centrifugal force. For this reason, the centrifugal separator is not suitable for a large apparatus or for separation of particles having different densities.

  A technique using ultrasonic waves for the separation process is also known (Non-Patent Document 3). Separation technology using ultrasonic waves mainly uses ultrasonic waves in the megahertz band, and separates particles by standing waves formed by the ultrasonic waves and their acoustic radiation force. Therefore, when the ultrasonic wave is in the megahertz band, the wavelength of the standing wave is shortened, so that the separation target of particles becomes less than a micrometer. In addition, when the ultrasonic wave is in the megahertz band, particles having a density different from that of the liquid are to be separated.

  Therefore, the separation techniques described above have conditions that can be applied according to each technique. Therefore, it is necessary to select a separation technique according to the properties of the particles to be separated and the properties of the liquid containing the particles. Therefore, in the field of the technology, there has been a demand for an easy-to-use separation technique that eases the application conditions imposed when using the separation technique.

  Then, an object of this invention is to provide the particle | grain separation method and particle | grain separation apparatus which can ease the conditions of applicable object.

  One aspect of the present invention is a particle separation method for separating first particles and second particles contained in a liquid containing dissolved gas, by irradiating the liquid with ultrasonic waves based on the first condition. Generating a dissolved gas in the liquid as bubbles, and generating a first cohesive force for collecting the first particles and the second particles to which the bubbles are attached to the antinodes of the ultrasonic waves, so that the first particles and the bubbles to which the bubbles are attached A first step of maintaining a mixed particle group including two particles, and after the first step, by irradiating the liquid with ultrasonic waves based on the second condition, a second cohesive force weaker than the first cohesive force is obtained. A second step of generating and stopping the maintenance of the mixed particle group, and after the second step, the liquid is irradiated with ultrasonic waves based on the third condition, thereby generating dissolved gas as bubbles in the liquid. And weaker than the first cohesive force, and The third cohesive force stronger than the second cohesive force is generated to maintain the first particle group including the first particles to which the bubbles are attached at the first antinode position of the ultrasonic wave, and the second particles including the second particles to which the bubbles are attached. And a third step of maintaining the two particle groups at the second antinode position of the ultrasonic wave.

  According to this method, first, in the first step, the liquid is irradiated with ultrasonic waves based on the first condition. Bubbles are generated in the liquid by the irradiation of the ultrasonic waves. Next, when an ultrasonic wave acts on the bubbles, a first cohesive force is generated in the bubbles. Due to the first cohesive force, bubbles are collected on the antinode of the ultrasonic wave. Here, when the bubble moves toward the antinode of the ultrasonic wave, the bubble adheres to the first particle or the second particle. In addition, bubbles may be generated directly on the surface of the first particle or the second particle. Since the bubbles gather at the antinodes of the ultrasonic waves by the first cohesive force, the first particles or the second particles to which the bubbles are attached also gather at the antinodes of the ultrasonic waves together with the bubbles to form a mixed particle group. Next, in the second step, the liquid is irradiated with ultrasonic waves based on the second condition. The second cohesive force by the ultrasonic wave based on the second condition is weaker than the first cohesive force. Therefore, the first particles and the second particles cannot maintain the particle group against the gravity and start to settle according to the characteristics of the respective particles. At this time, since the ultrasonic wave irradiated to the liquid is not zero, there are slight bubbles in the liquid. Next, in the third step, the liquid is irradiated with ultrasonic waves based on the third condition. The third cohesive force by the ultrasonic wave based on the third condition is weaker than the first cohesive force, but stronger than the second cohesive force. A force sufficient to form a group again acts on the first particles and the second particles that are settling. And the 1st particle | grains and 2nd particle | grains during sedimentation differ in the speed | rate which settles according to each characteristic. Therefore, when the third cohesive force is applied, the group is again maintained at the position of the antinode of the ultrasonic wave close to each position. Therefore, since the first particles are collected at the first antinode position and the second particles are collected at the second antinode position, the first particles and the second particles are separated. Accordingly, since the particle separation method uses the force generated by the action of ultrasonic waves on the bubbles generated in the liquid, the effects of the characteristics of the first and second particles to be separated and the liquid characteristics are affected. It is hard to receive. Therefore, the particle separation method of the present invention can relax the applicable target conditions.

  The first condition, the second condition, and the third condition define the intensity of the ultrasonic wave, the ultrasonic wave intensity defined by the third condition is smaller than the ultrasonic wave intensity defined by the first condition, and The intensity of the ultrasonic wave defined by the second condition may be larger. These conditions can be easily controlled and set easily. Therefore, the first particles and the second particles can be easily separated.

  The first condition, the second condition, and the third condition are conditions for defining the value of the ultrasonic frequency, and the value defined by the third condition is less than or equal to the value defined by the first condition. And it may be larger than the value defined by the second condition. The first condition, the second condition, and the third condition are conditions for defining the value of the ultrasonic frequency, and the value defined by the third condition is equal to or greater than the value defined by the first condition. Yes, and may be smaller than the value defined by the second condition. These conditions can be easily controlled and set easily. Therefore, the first particles and the second particles can be easily separated.

  In the first step, the second step, and the third step, ultrasonic waves may be irradiated from the bottom side of the container that stores the liquid toward the liquid surface of the liquid. According to these steps, ultrasonic nodes and antinodes are alternately formed in the vertical direction in the liquid. Therefore, the first particle group and the second particle group can be maintained at different antinode positions along the vertical direction.

  Another aspect of the present invention is a particle separation device that separates first particles and second particles contained in a liquid containing dissolved gas, the container containing the liquid, and the liquid contained in the container An ultrasonic irradiation means for irradiating the ultrasonic wave and a control means for controlling the ultrasonic irradiation means, and the control means irradiates the liquid with ultrasonic waves based on the first condition, thereby In addition to generating dissolved gas as bubbles, a first cohesive force is generated that causes the first particles and second particles to which the bubbles are attached to gather in the antinodes of the ultrasonic waves, and includes the first particles and the second particles to which the bubbles are attached. By maintaining the mixed particle group and irradiating the liquid with ultrasonic waves based on the second condition, a second cohesive force that is weaker than the first cohesive force is generated, and the maintenance of the mixed particle group is stopped and the liquid is stopped. By irradiating with ultrasonic waves based on the third condition, First particles containing first particles to which dissolved gas is generated in the body as bubbles and a third cohesive force that is weaker than the first cohesive force and stronger than the second cohesive force is generated. Control is performed so that the group is maintained at the first antinode position of the ultrasonic wave, and the second particle group including the second particles to which bubbles are attached is maintained at the second antinode position of the ultrasonic wave.

  Since this particle separator uses the force generated by the action of ultrasonic waves on the bubbles generated in the liquid, it is affected by the characteristics of the first and second particles to be separated and the liquid characteristics. hard. Therefore, the particle separation device can relax the applicable target conditions.

  The particle separator may further include a particle group moving unit that moves the mixed particle group, the first particle group, and the second particle group. According to this particle group moving means, for example, the separated first particle group and second particle group can be moved to a place such as a discharge port.

  ADVANTAGE OF THE INVENTION According to this invention, the particle | grain separation method and particle | grain separation apparatus which can ease the conditions of applicable object are provided.

It is a figure which shows typically the structure of the particle | grain separator which concerns on this embodiment. It is a figure which shows the main processes of the particle separation method which concerns on this embodiment. It is a figure which shows typically the phenomenon which has arisen in the water tank in the particle separation method. It is a figure which shows typically the phenomenon which has arisen in the water tank in the particle separation method. It is a figure which shows typically the phenomenon which has arisen in the water tank in the particle separation method. It is a figure which shows typically the phenomenon which has arisen in the water tank in the particle separation method. 2 is a photograph for explaining the results of Example 1. FIG. 4 is a photograph for explaining the results of Example 2. FIG. 6 is a photograph for explaining the results of Example 3. FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  First, the particle separator used for the particle separation method of this embodiment is demonstrated. As shown in FIG. 1, the particle separation device 1 separates the first particles P1 and the second particles P2 contained in the water 3 filled in the water tank 2. The particle separation device 1 includes a water tank 2, a control device 7 (control means), an ultrasonic vibration device 8 (ultrasonic irradiation means), and a recovery means 9 (particle group moving means).

  The water tank 2 contains water 3 containing the first particles P1 and the second particles P2 that are to be separated. The water 3 contains air as a dissolved gas.

  The control device 7 generates a control signal that is input to the ultrasonic vibration device 8. The control device 7 includes a condition setting unit 11, a signal generator 12, an amplifier circuit 13, and a matching device 14.

  The condition setting unit 11 sets a driving condition for the ultrasonic vibration device 8. The condition setting unit 11 records various setting data. The setting data includes conditions such as the type of liquid containing particles such as water 3, the type of gas dissolved in the liquid, the type of particles to be separated, and the driving of the ultrasonic vibration device 8 suitable for separation processing under those conditions. Data associated with a condition. The driving conditions include a time history related to the intensity of the ultrasonic waves, a time history related to the frequency of the ultrasonic waves, or the like. The condition setting unit 11 determines the driving conditions of the ultrasonic vibration device 8 to be irradiated based on the liquid used for the separation process, the dissolved gas, the properties of the particles to be separated, and the like.

  The signal generator 12 generates a control signal for driving the ultrasonic vibration device 8 based on the setting data output from the condition setting unit 11. For the signal generator 12, for example, a function generator is used. The amplifier circuit 13 amplifies the control signal generated in the signal generator 12. The matching device 14 matches the impedance between the amplifier circuit 13 and the ultrasonic vibration device 8. The matching device 14 may be provided as necessary.

  The ultrasonic vibration device 8 irradiates the water 3 filled in the water tank 2 with ultrasonic waves. The ultrasonic vibration device 8 radiates an ultrasonic wave having a predetermined frequency and a predetermined intensity based on a control signal input from the control device 7. The control signal is, for example, an AC voltage signal having a predetermined voltage value and frequency, and the ultrasonic vibration device 8 receives the voltage signal and vibrates the vibrator. The ultrasonic vibration device 8 emits an ultrasonic wave having an intensity of 19 kHz or more and 40 kHz or less and an intensity of 60 W or less. As such an ultrasonic vibration device 8, for example, a bolted Langevin type vibrator is used. The ultrasonic vibration device 8 is attached to the bottom of the water tank 2 by adhesion. Note that the ultrasonic vibration device 8 may be in a mode in which the plate to which the vibrator is attached is fixed by flange fastening. The ultrasonic wave irradiated from the ultrasonic vibration device 8 generates a standing wave between the bottom surface of the water tank 2 and the water surface.

  The collection means 9 discharges the separated first particles P1 and second particles P2 to the outside of the water tank 2. The collection unit 9 includes an operation rod 16 and a discharge unit 17. The operating rod 16 moves the separated first particles P1 and second particles P2 to a position where they can be put into the discharge unit 17. The operation rod 16 is, for example, a rod that is inserted into the water from the water surface of the water tank 2. The operation rod 16 is moved in the water tank 2 from the outside of the water tank 2 by an operator or a device such as a robot hand. The discharge unit 17 discharges the particles input to the discharge unit 17 to the outside of the water tank 2.

  Next, the particle separation method using the particle separation apparatus 1 will be described with reference to the procedure shown in FIG. 2 and the phenomenon caused by the procedure.

As shown in part (a) of FIG. 3, first, the water tank 2 is filled with water 3 (step S1). The amount of water 3 is related to the frequency of the irradiated ultrasonic wave. The liquid level in the water tank 2 is set to be higher than the wavelength of the ultrasonic wave traveling in water. Specifically, the liquid level in the water tank 2 is set to 1.5 times or more the wavelength of the ultrasonic wave in water. As an example, the liquid level is 120 mm. The wavelength of the ultrasonic wave in water is expressed by equation (1).

λ: Wavelength of ultrasonic waves in water.
c: Speed of sound.
f: Transmission frequency of ultrasonic waves.
For example, when the water temperature of the water 3 is 20 ° C. and the frequency of the control signal is 20 kHz, the wavelength (λ) is about 74 mm. Therefore, when forming a particle group, the liquid level needs to be at least about 40 mm.

  Next, as shown in part (b) of FIG. 3, the first particles P1 and the second particles P2 are put into the water 3 (step S2). In the present embodiment, the first particle P1 having a diameter of 800 μm as a large particle and the second particle P2 having a diameter of 400 μm as a small particle will be described as an example.

  Next, as shown in part (c) of FIG. 3, the water 3 is irradiated with ultrasonic waves based on the first condition (step S3). In this step S3 (first step), air as dissolved gas is generated as bubbles B. Further, in this step S3, a first cohesive force is generated that causes the first particles P1 and the second particles P2 to which the bubbles B are attached to gather in the ultrasonic antinode VB, and the first particles P1 and the first particles P1 to which the bubbles B are attached are generated. A spherical mixed particle group including two particles P2 is maintained. The first condition is an intensity and a frequency at which air dissolved in the water 3 can appear as bubbles, and an intensity and a frequency at which the first vanaesque force, which is one of the acoustic radiation forces, can act on the bubbles B. is there. For example, the ultrasonic wave radiated from the ultrasonic vibration device 8 is caused by a control signal having an amplitude voltage of 300 mV and a frequency of 19.0 kHz.

  When the water 3 is irradiated with ultrasonic waves, the sound waves propagate in the water tank 2 and a standing wave W is formed in the water tank 2. And the air which was dissolved in the water 3 appears as the bubble B with the change of the sound pressure. The bubble B is generated due to an action similar to a so-called cavitation phenomenon. The bubble B is not a sound pressure fluctuation in which a vapor cavitation bubble is generated, but is caused by cavitation generated by air dissolved in the water 3 and is a kind of gas cavitation. Cavitation refers to a phase change phenomenon from a liquid phase to a gas phase accompanying pressure fluctuation. Cavity means that a cavity is the basis and a cavity (bubble) is formed in the liquid. Some of them are generated by a pump impeller or the like, but in this embodiment, they are generated by sound pressure fluctuations due to ultrasonic waves.

  The bubble B adheres to the first particle P1 and the second particle P2. In addition, there may be a case where the first particles P1 and the second particles P2 are directly generated on the surfaces. Here, when the liquid filled in the water tank 2 is degassed purified water, since there is no core of the bubble B, the bubble B is not generated. There is no restriction | limiting in particular in the kind of gas dissolved in the water 3, What is necessary is just air, a carbon dioxide, and another gas.

  Then, as shown in FIG. 4A, the first particles P1 and the second particles P2 to which the bubbles B are attached begin to gather to the antinodes of sound pressure (positions where the amplitude fluctuation is large) due to the acoustic radiation force. . In the configuration of the present embodiment, the acoustic radiation force acting on the bubble B is larger than the acoustic radiation force acting directly on the first particle P1 and the second particle P2. Accordingly, the movement of the first particles P1 and the second particles P2 in the water tank 2 is dominated by the acoustic radiation force acting on the bubbles B. When the acoustic radiation force acting directly on the first particle P1 and the second particle P2 is dominant, the first particle P1 and the second particle P2 move to the node of sound pressure. However, the acoustic radiation force acting on the particles is very weak, and the first particles P1 and the second particles P2 cannot be lifted against gravity. In this embodiment, since the acoustic radiation force acting on the bubble B is dominant, the first particles P1 and the second particles P2 move to the antinodes of the sound pressure.

Here, the acoustic radiation force that acts on the bubble B is also referred to as a first vanezque force. The first Bianesque force is an acoustic radiation force due to a standing wave sound pressure fluctuation, and is represented by Expression (2).

F _PBF : The magnitude of the first beanesk force.
V: Bubble volume.
∇P: Pressure gradient.
<>: Time average of one cycle of ultrasonic waves to be irradiated

  Induced by the movement of the bubbles B, a liquid phase movement is induced in the water tank 2. The liquid phase motion in the water tank 2 generates an upward flow in which the antinode of the sound pressure is the apex of the cone in the lower central part. From the stomach to the top, an upward flow is generated. On the other hand, the water surface flows in the horizontal direction and descends in the vicinity of the wall surface, forming a circulating flow.

  As shown in part (b) of FIG. 4, the first particles P <b> 1 and the second particles P <b> 2 to which the bubbles B are attached gather in a spherical shape in the vicinity of the sound pressure antinode VB. The state in which the first particles P1 and the second particles P2 are densely packed in a spherical shape is referred to as a mixed particle group GA. In this mixed particle group GA, the spherical shape is maintained by another force in addition to the above-mentioned first vanesque force which is the acoustic radiation force. This other force is called the second beakness force. The second beakness force is a force that attracts bubbles B that vibrate at the same frequency and the same phase. Accordingly, in step S3, the first cohesive force generated due to the ultrasonic wave based on the first condition is a force resulting from the first and second Benessque forces.

  Next, the ultrasonic wave based on 2nd conditions is irradiated with respect to the water 3 (step S4). In step S4 (second step), a second cohesive force that is weaker than the first cohesive force is generated, and the maintenance of the mixed particle group GA is stopped. Specifically, the control device 7 continuously changes the amplitude voltage of the control signal input to the ultrasonic vibration device 8 from 300 mV to 80 mV (second condition). This voltage change is performed in about 5 seconds as an example.

  Here, in the separation method according to this embodiment, in the water tank 2, it is important to form a distribution state in which many small-diameter particles exist in the upper part of the water tank and many large-diameter particles exist in the lower part of the water tank. For example, it is assumed that the voltage is changed stepwise from the first condition to the second condition. According to this step-like change, the bubble motion is weakened rapidly, and the liquid phase motion is also weakened. Therefore, the 1st particle P1 and the 2nd particle P2 will settle in the state where it gathered. On the other hand, when the voltage is gradually lowered from the first condition to the second condition as in the present embodiment, the particles are precipitated from large-diameter particles having a large influence of gravity, and the particle distribution is suitable for separation. Can be.

  As shown in part (c) of FIG. 4, when the sound pressure amplitude due to the ultrasonic wave is reduced, the expansion / contraction motion (interface motion) due to the sound pressure fluctuation of the bubble B is reduced and the bubble diameter is also reduced. As a result, the buoyancy caused by the first and second biasesque forces is reduced. Since the bubble motion including the interfacial motion and the translational motion toward the belly is weakened, the upward flow at the center of the water tank forming the circulating flow in the water tank 2 is weakened. Therefore, the mixed particle group GA that has been aggregated by the antinode VB cannot be settled by the antinode, and gradually collapses and begins to settle against gravity.

Here, the second Vanesque force refers to an acoustic radiation force acting between the bubbles B. When two bubbles move in an interface with the same period and the same phase, they act as attractive forces. On the other hand, when the phase is shifted by 180 °, it acts as a repulsive force. The second Bianesk force is expressed by equation (3).

  As shown in part (a) of FIG. 5, the sedimentation speed varies depending on the particle diameters of the first particles P1 and the second particles P2 according to the Stokes law. Specifically, particles having a large particle size settle faster than particles having a small particle size. That is, particles having a large particle diameter have a high sedimentation rate. Therefore, as time elapses after Step S4 is started, the state shifts to a state in which many large-diameter particles exist below the water tank 2 and small-diameter particles exist above it. For example, the period of applying ultrasonic waves based on the second condition is continued for about 5 seconds.

  That is, in step S4, a time of about 5 seconds is provided to shift from the first condition to the second condition, and the state of the second condition is maintained for about 5 seconds.

  Here, in step S4, the output of the ultrasonic wave based on the second condition is not made zero. For example, when the amplitude voltage is set to 0 mV, the bubbles B attached to the first particles P1 and the second particles P2 are dissolved in the water 3, and only the first particles P1 and the second particles P2 are settled. Or the bubble B which existed in the vicinity of the 1st particle P1 and the 2nd particle P2 melt | dissolves in the water 3, and only the 1st particle P1 and the 2nd particle P2 settle. Then, when the amplitude voltage is increased again, since the bubbles B that carry the particles to the antinodes of the sound pressure do not exist in the vicinity of the first particles P1 and the second particles P2, the first particles P1 and the second particles P2 are instantaneously moved. It cannot be generated. Therefore, in the present embodiment, since the second condition is smaller than the first condition and zero or more, the bubble nuclei of the bubbles B remaining around the first particles P1 and the second particles P2 also move with the particles. Therefore, when the voltage rises, the bubble nuclei instantly grow to generate bubbles B near the particles, and the particles can be quickly pulled to the antinodes of the sound pressure. As a result, more precise separation is possible.

  Next, ultrasonic waves based on the third condition are irradiated to the water 3 (step S5). In this step S5 (third step), air is generated again as water bubbles 3 in the water 3. Further, the first particle group G1 including the first particles P1 to which the bubbles B are attached is maintained at the first antinode position VB1 of the ultrasonic waves. Further, the second particle group G2 including the second particles P2 to which the bubbles B are adhered is maintained at the second antinode position VB2 of the ultrasonic wave. Specifically, the control device 7 continuously changes the amplitude voltage of the control signal input to the ultrasonic vibration device 8 from 80 mV to 140 mV (third condition).

  Here, the ultrasonic wave based on the third condition generates a third cohesive force that is weaker than the first cohesive force but stronger than the second cohesive force. When the second condition is changed to the third condition, the amplitude voltage input to the ultrasonic vibration device 8 increases. Therefore, bubble motion is activated and liquid phase motion is increased. However, when the third cohesive force is equal to the first cohesive force, the first particle group G1 aggregated in the lower part of the water tank 2 is detached from the first antinode position VB1 by the liquid phase motion. . And the 1st particle P1 may reaggregate with the 2nd particle P2 in the 2nd antinode position VB2 in the upper part of water tank 2, and may form mixed particle group GA again.

  As shown in part (b) of FIG. 5, the interfacial motion and translational motion of the bubble B become active as the sound pressure amplitude due to the third condition increases. As the diameter of the bubble B increases, the second Vanesque force, the buoyancy, and the upward flow increase, and the bubble B pulls the first particle P1 and the second particle P2 to reaggregate with the belly of the sound pressure. Here, in the state immediately before step S <b> 5, there are many first particles P <b> 1 that are large-diameter particles in the lower part of the water tank 2, and many second particles P <b> 2 that are small-diameter particles exist in the upper part of the water tank 2. Here, when the ultrasonic wave based on the third condition is irradiated, the particles gather in the nearest belly. Specifically, as shown in part (c) of FIG. 5, the first particles P1 gather at the first antinode position VB1 to form a first particle group G1 in which the first particles P1 are aggregated. The second particles P2 gather at the second antinode position VB2 to form a second particle group G2 in which the second particles P2 are aggregated.

  Next, the first particles P1 and the second particles P2 are discharged (step S6). As shown in part (a) of FIG. 6, when the operation rod 16 is put into the water 3, the bubbles B adhere to the operation rod 16. The bubble B is, for example, a bubble generated by a scratch existing on the surface of the operation rod 16 serving as a bubble nucleus. Further, bubbles B generated around the operation rod 16 are attached to the surface of the operation rod 16.

  Then, the second beakness force acts between the bubble B attached to the operation rod 16 and the bubble B attached to the second particle P2. Therefore, the second particle group G2 is attracted to the movement of the operation rod 16. As shown in part (b) of FIG. 6, after the operating rod 16 is moved to the upper part of the discharge part 17, the amplitude voltage of the control signal is reduced. Then, the second particle group G2 collapses and settles in the discharge unit 17.

  The range in which the second particle group G2 can be moved is a range in which bubbles B are generated and the cohesive force acts effectively. Accordingly, when the second particle group G2 is out of this range, the second particle group G2 reaggregates on the antinode of the sound pressure that was initially aggregated. Therefore, when the discharge unit 17 is provided outside the movable range, the voltage or frequency of the control signal is adjusted. By this adjustment, the movable range can be changed by changing the positions of the nodes and antinodes of the standing wave existing in the water.

  According to the particle separation device 1 and the particle separation method of the present embodiment, in step S3, the water 3 is irradiated with ultrasonic waves based on the first condition. By this irradiation with ultrasonic waves, bubbles B are first generated in the water 3. Next, when an ultrasonic wave acts on the bubble B, a first cohesive force is generated on the bubble B. Due to the first cohesive force, the bubbles B are collected in the antinode VB of the ultrasonic wave. Here, when the bubble B moves toward the antinode VB of the ultrasonic wave, the bubble B adheres to the first particle P1 or the second particle P2. Moreover, the bubble B may generate | occur | produce directly on the surface of the 1st particle P1 or the 2nd particle P2. Since the bubbles B gather at the ultrasonic antinodes VB by the first cohesive force, the first particles P1 or the second particles P2 to which the bubbles B are attached also gather at the ultrasonic antinodes VB together with the bubbles B to form the mixed particle group A. . Next, in step S4, the liquid is irradiated with ultrasonic waves based on the second condition. The second cohesive force by the ultrasonic wave based on the second condition is weaker than the first cohesive force. Accordingly, the first particles P1 and the second particles P2 cannot maintain the particle group against gravity, and start to settle according to the characteristics of the respective particles. At this time, since the ultrasonic wave irradiated to the water 3 is not zero, the water 3 has a small amount of bubbles B. Next, in the third step, the liquid is irradiated with ultrasonic waves based on the third condition. The third cohesive force by the ultrasonic wave based on the third condition is weaker than the first cohesive force, but stronger than the second cohesive force. A force sufficient to form a group again acts on the first particles P1 and the second particles P2 that are being settled. And the 1st particle P1 and the 2nd particle P2 in sedimentation differ in the speed of sedimentation corresponding to each characteristic. Therefore, when the third cohesive force is applied, the group is again maintained at the position of the antinode of the ultrasonic wave close to each position. Therefore, since the first particles P1 are collected at the first antinode position VB1 and the second particles P2 are collected at the second antinode position VB2, the first particles P1 and the second particles P2 are separated. Accordingly, since the particle separation device 1 and the particle separation method use the force generated by the action of ultrasonic waves on the bubbles B generated in the water 3, the first particles P1 and the second particles P2 that are the separation targets. It is hard to be affected by the characteristics of the liquid and liquid. Therefore, the particle separation apparatus 1 and the particle separation method can alleviate the applicable target conditions.

  In addition, the first condition, the second condition, and the third condition are the intensity of the ultrasonic wave, and the ultrasonic wave intensity defined by the third condition is smaller than the ultrasonic wave intensity defined by the first condition, And it is larger than the intensity of the ultrasonic wave defined by the second condition. These conditions can be easily controlled and set easily. Therefore, the first particles and the second particles can be easily separated.

  In step S3, step S4, and step S5, ultrasonic waves are irradiated from the bottom side of the container that stores the liquid toward the liquid surface of the liquid. According to these steps, ultrasonic nodes and antinodes are alternately formed in the vertical direction in the liquid. Therefore, the first particle group G1 and the second particle group G2 can be maintained at different antinode positions along the vertical direction.

  Further, in the particle separation apparatus and the particle separation method according to the present embodiment, ultrasonic waves of several tens of kilohertz band are used instead of megahertz ultrasonic waves. When megahertz band ultrasonic waves are used, the wavelength of the standing wave is shortened according to the above equation (1). Therefore, the diameter of the particles to be separated is reduced. On the other hand, by using ultrasonic waves in the tens of kilohertz band as in the particle separation apparatus and particle separation method according to the present embodiment, it becomes possible to increase the amplitude of sound pressure and to make cavitation bubbles act actively. . Therefore, the particle separation apparatus and the particle separation method according to the present embodiment can classify particles of the same type and different diameters according to particle diameters, and can further operate the classified particle groups.

  In addition, embodiment mentioned above shows an example of the particle separation apparatus and particle separation method which concern on this invention. The particle separation device and the particle separation method according to the present invention are not limited to the particle separation device and the particle separation method according to the embodiment, and may be modified or otherwise changed without changing the gist described in each claim. It may be applied to.

<Modification 1>
For example, in the above embodiment, the intensity of the ultrasonic wave applied to the water 3 in each of steps S3, S4, and S5, in other words, the amplitude voltage of the control signal input to the ultrasonic vibration device 8 is the first condition, the second It was defined as a condition and a third condition. The first condition, the second condition, and the third condition may be conditions for defining the value of the ultrasonic frequency. The condition for defining the value of the ultrasonic frequency is the difference between the frequency of the control signal and the resonance frequency shown in Equation (4). Therefore, the values defined by the first condition, the second condition, and the third condition are absolute values of the difference between the frequency of the control signal and the resonance frequency. The resonance frequency here is a resonance frequency that the vibrator and the water tank have, and is determined by a variable such as a mass of the water tank or the amount of water. As shown in Expression (4), the third difference (| f3-fr |) defined by the third condition is equal to or less than the first difference (| f1-fr |) defined by the first condition. The third difference (| f3-fr |) is larger than the second difference (| f2-fr |) defined by the second condition. In this case, first, the resonance frequency (fr), the first difference, the second difference, and the third difference are given. The first difference, the second difference, and the third difference are set so as to satisfy the condition of Expression (4). From these values, the frequency (f1, f2, f3) of the control signal actually applied is determined.

f1: The frequency of the control signal defined in the first condition.
f2: The frequency of the control signal defined by the second condition.
f3: The frequency of the control signal defined in the third condition.
fr: resonance frequency.

<Modification 2>
Further, the condition for defining the value of the ultrasonic frequency may be the frequency of the ultrasonic wave as shown in Expression (5). The ultrasonic frequency (f3) defined by the third condition is equal to or lower than the ultrasonic frequency (f1) defined by the first condition and the ultrasonic frequency (f1) defined by the second condition (f1). higher than f2). In this case, for example, the frequency of the control signal is set to a resonance frequency of 20.2 kHz as the first condition.

  When the process proceeds from step S3 to step S4, the frequency of the ultrasonic wave changes from the first frequency f1 that is the resonance frequency to the second frequency f2 that is out of the resonance frequency. In the frequency band near the resonance frequency, when the frequency changes, the impedance changes depending on the frequency. Specifically, the impedance is increased. Therefore, since the intensity of the ultrasonic wave that can be applied to the water tank 2 is reduced due to the increase in impedance, the position of the standing wave also changes as the frequency changes. Specifically, the standing position changes based on a change in wavelength (the above formula (1)) due to a change in the intensity and frequency of the ultrasonic wave. Therefore, the change in the stationary position is greatly affected by the expression (1).

  Then, when the ultrasonic wave of the first frequency irradiated in step S4 in which the mixed particle group GA is maintained is changed to the ultrasonic wave of the second frequency in step S5, the first particle P1 and the second particle P2 are sounded. The force on the bubbles B (first beansk force) that has been present in the antinodes of the pressure becomes weak, the outline of the mixed particle group GA becomes unclear, and sedimentation starts. Since the first particle P1, which is a large particle, has a larger settling force than the second particle P2, which is a small particle, the mixed particle group GA is separated from the first particle P1, and settling begins. Therefore, the state where the first particles P <b> 1 (large diameter particles) gather in the lower part of the water tank 2 and the second particles P <b> 2 (small diameter particles) gather in the upper part of the water tank 2 is formed by step S <b> 5.

<Modification 3>
Further, the condition for defining the value of the ultrasonic frequency may be the frequency of the ultrasonic wave as shown in Expression (6). The ultrasonic frequency (f3) defined by the third condition is equal to or higher than the ultrasonic frequency (f1) defined by the first condition and the ultrasonic frequency (f1) defined by the second condition (f1). It is lower than f2). In this case, for example, the frequency of the control signal is set to a resonance frequency of 20.2 kHz as the first condition.

<Modification 4>
Moreover, in the said embodiment, the collection | recovery means 9 using the 2nd Bianesque force was provided. The particle separation device of the present invention may include a recovery device using another principle. For example, the recovery device may be a hollow glass tube that is open at both ends. The glass tube is brought close to the particle group so that the particles enter the glass tube. Then, the other tube end of the glass tube is closed and removed from the water tank. Alternatively, the suction side of the pump may be attached to the other end of the glass tube. You may collect | recover by suck | inhaling particle | grains with water in the state which brought the glass tube close to the particle group.

<Modification 5>
Further, the frequency and amplitude voltage of the control signal described above are examples, and are not limited to these numerical values. Depending on the type of liquid, the type of dissolved gas, and the type of particles to be separated, these numerical values can be selected according to the respective types.

<Example 1>
In Example 1, the operational effect of the particle separation method based on the condition defining the voltage was confirmed. In Example 1, polystyrene having a diameter of 800 μm was used as the first particles. The density of the first particles is 1.05 g / cm ³ and the sedimentation rate is 10.36 mm / s. In Example 1, polystyrene having a diameter of 400 μm was used as the second particles. The density of the second particles is 1.05 g / cm ³ and the sedimentation speed is 4.15 mm / s. As a first condition, the voltage of the control signal was 300 mV. As a second condition, the voltage of the control signal was 80 mV. As a third condition, the voltage of the control signal was 140 mV. The frequency of the control signal is common to the first condition, the second condition, and the third condition, and is 19.0 kHz.

  When Step S3 based on the first condition was executed, the mixed particle group GA was formed in the upper part of the water tank 2, as shown in part (a) of FIG. Next, step S4 was performed immediately after imaging (a) part of FIG. Then, about 5 seconds after the time when the part (a) of FIG. 7 was imaged, the voltage of the control signal changed to 140 mV. At this time, as shown in part (b) of FIG. 7, the first particles P1 began to drop out from the mixed particle group GA. Next, the state of step S4 was maintained for about 5 seconds from the time when the part (b) of FIG. 7 was imaged. That is, the voltage of the control signal was set to a constant value of 140 mV. At this time, the second particles P2 also dropped out, and the mixed particle group GA disappeared. And the state where many 1st particle | grains P1 existed on the bottom side of the water tank 2 and many 2nd particle | grains P2 existed on the upper side appeared as shown in the (c) part of FIG. Next, step S5 based on the third condition was executed. Then, as shown in part (d) of FIG. 7, the formation of the first particle group G1 was started on the bottom side of the water tank 2, and the formation of the second particle group G2 was started on the upper side of the water tank 2. Then, after about 2 seconds from the time when the part (d) in FIG. 7 is imaged, as shown in the part (e) in FIG. 7, the first particle group G1 including the first particles P1 and the second particles Formation of the second particle group G2 containing P2 was completed, and separation was completed.

  Therefore, it has been found that according to the separation method based on the condition defining the voltage, the first particles P1 and the second particles P2 can be separated with high accuracy.

<Example 2>
In Example 2, the movement of the particle group using the operation rod 16 was confirmed. In Example 2, polystyrene having a diameter of 600 μm was used as the first particles. The density of the first particles is 1.05 g / cm ³ and the sedimentation rate is 7.43 mm / s. As a first condition, the voltage of the control signal was 300 mV, and the frequency of the control signal was 20.0 kHz.

  As shown in part (a) of FIG. 8, when the tip of the operation rod 16 was placed in water, bubbles adhered to the operation rod 16. As shown in the parts (b) and (c) of FIG. 8, when the operation rod 16 was brought close to the particle group G, the particle group G was attracted to the operation bar 16 by the second Vanesque force. Then, as shown in (d) and (e) of FIG. 8, when the operating rod 16 is brought closer to the wall surface of the water tank 2, the second vanesque force becomes weak and gravity becomes dominant, and the particle group G separated from the operation rod 16 and lowered to the bottom of the water tank 2. Then, the particle group G again moved to the ultrasonic antinode region.

  Therefore, it has been found that the position of the particle group can be manipulated in the region where the second vanezque force is dominant by using the operation rod 16.

<Example 3>
In Example 3, the effect of the particle separation method based on the conditions defining the frequency was confirmed. In Example 3, polystyrene having a diameter of 800 μm was used as the first particles. The density of the first particles is 1.05 g / cm ³ and the sedimentation rate is 10.36 mm / s. In Example 1, polystyrene having a diameter of 400 μm was used as the second particles. The density of the second particles is 1.05 g / cm ³ and the sedimentation speed is 4.15 mm / s. As a first condition, the frequency of the control signal was 20.2 kHz. As a second condition, the frequency of the control signal was 21.0 kHz. As a third condition, the frequency of the control signal was 20.3 kHz. The amplitude voltage of the control signal is common to the first condition, the second condition, and the third condition, and is 300 mV.

  When Step S3 based on the first condition was executed, the mixed particle group GA was formed in the upper part of the water tank 2, as shown in part (a) of FIG. Next, step S4 was performed immediately after imaging the part (a) of FIG. Then, 5 seconds after the time when the part (a) of FIG. 9 was imaged, the frequency of the control signal changed to 21.0 kHz. At this time, as shown in part (b) of FIG. 9, the first particles P1 began to drop out from the mixed particle group GA. Next, the state of step S4 was maintained for 5 seconds from the time when the part (b) of FIG. 9 was imaged. That is, the frequency of the control signal was set to a constant value of 21.0 kHz. At this time, the second particles P2 also dropped out, and the mixed particle group GA disappeared. And the state where many 1st particle | grains P1 existed in the bottom side of the water tank 2, and many 2nd particle | grains P2 existed on the upper side appeared as (c) part of FIG. 9 showed. Next, step S5 based on the third condition was executed. Then, as shown in part (d) of FIG. 9, the formation of the first particle group G1 was started on the bottom side of the water tank 2, and the formation of the second particle group G2 was started on the upper side of the water tank 2. And after 0.5 second passes from the time when the (d) part of Drawing 9 was imaged, as shown in (e) part of Drawing 9, the 1st particle group G1 containing the 1st particle P1, and the 2nd Formation of the second particle group G2 including the particles P2 was completed, and separation was completed. The frequency of S5 is 20.2 kHz.

  Therefore, it was found that according to the separation method based on the condition defining the frequency, the first particles P1 and the second particles P2 can be separated with high accuracy.

DESCRIPTION OF SYMBOLS 1 ... Particle separator, 2 ... Water tank, 3 ... Water (liquid), P1 ... 1st particle, P2 ... 2nd particle, 7 ... Control apparatus (control means), 8 ... Ultrasonic vibration apparatus (ultrasonic irradiation means) 9, collection means (particle group moving means), B ... bubbles, GA ... mixed particle group, G1 ... first particle group, G2 ... second particle group, VB1 ... first antinode position, VB2 ... second antinode position.

Claims (7)

A particle separation method for separating first particles and second particles contained in a liquid containing dissolved gas,
By irradiating the liquid with ultrasonic waves based on the first condition, the dissolved gas is generated as bubbles in the liquid, and the first particles and the second particles to which the bubbles are attached are applied to the ultrasonic waves. A first step of maintaining a mixed particle group including the first particles and the second particles to which the bubbles are attached by generating a first cohesive force that aggregates on the stomach of
After the first step, by irradiating the liquid with ultrasonic waves based on the second condition, a second cohesive force that is weaker than the first cohesive force is generated, and the maintenance of the mixed particle group is stopped. A second step to
After the second step, by irradiating the liquid with ultrasonic waves based on a third condition, the dissolved gas is generated as bubbles in the liquid, and is weaker than the first cohesive force, and A third cohesive force stronger than the second cohesive force is generated to maintain the first particle group including the first particles to which the bubbles are attached at the first antinode position of the ultrasonic wave, and the bubbles are attached. A third step of maintaining a second particle group including the second particles at a second antinode position of the ultrasonic wave. The first condition, the second condition, and the third condition define the intensity of the ultrasonic wave,
The intensity of the ultrasonic wave defined by the third condition is smaller than the intensity of the ultrasonic wave defined by the first condition and larger than the intensity of the ultrasonic wave defined by the second condition. The particle separation method according to claim 1. The first condition, the second condition, and the third condition are conditions for defining a frequency value of the ultrasonic wave,
2. The particle separation method according to claim 1, wherein a value defined by the third condition is equal to or less than a value defined by the first condition and is greater than a value defined by the second condition. The first condition, the second condition, and the third condition are conditions for defining a frequency value of the ultrasonic wave,
2. The particle separation method according to claim 1, wherein a value defined by the third condition is equal to or greater than a value defined by the first condition and is smaller than a value defined by the second condition.   The said 1st step, the said 2nd step, and the said 3rd step WHEREIN: The said ultrasonic wave is irradiated toward the liquid level of the said liquid from the bottom side of the container which accommodates the said liquid. The particle separation method according to Item. A particle separation device for separating first particles and second particles contained in a liquid containing dissolved gas,
A container containing the liquid;
Ultrasonic irradiation means for irradiating the liquid contained in the container with ultrasonic waves;
Control means for controlling the ultrasonic wave irradiation means,
The control means includes
By irradiating the liquid with ultrasonic waves based on the first condition, the dissolved gas is generated as bubbles in the liquid, and the first particles and the second particles to which the bubbles are attached are applied to the ultrasonic waves. Generating a first cohesive force to gather on the belly of the gas, maintaining the mixed particle group including the first particles and the second particles to which the bubbles are attached,
By irradiating the liquid with ultrasonic waves based on the second condition, a second cohesive force that is weaker than the first cohesive force is generated, and maintenance of the mixed particle group is stopped,
By irradiating the liquid with ultrasonic waves based on the third condition, the dissolved gas is generated as bubbles in the liquid, and is weaker than the first cohesive force and more than the second cohesive force. A strong third cohesive force is generated to maintain the first particle group including the first particles to which the bubbles are attached at the first antinode position of the ultrasonic wave, and includes the second particles to which the bubbles are attached. A particle separation device that performs control to maintain two particle groups at a second antinode position of the ultrasonic wave.   The particle separator according to claim 6, further comprising a particle group moving unit that moves the mixed particle group, the first particle group, and the second particle group.