JP4448264B2 - Particle size distribution measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a particle size distribution measuring apparatus, and more particularly to a laser light diffraction / scattering particle size distribution measuring apparatus.
[0002]
[Prior art]
Particle measurement technology is indispensable for determining and evaluating the performance of powders in a wide range of fields such as medicine, food, ceramics, cosmetics, paints, and pigments, and its importance is increasing day by day. Yes. One of the devices for measuring the particle size distribution of such a granular material is a laser beam diffraction / scattering particle size distribution measuring device.
[0003]
As the laser beam diffraction / scattering particle size distribution measuring device, a pump for circulating a sample solution in which sample particles are dispersed in a dispersion medium in a circulation channel, and sample particles in the sample solution A flow cell for measuring the particle size distribution, a dispersion means for dispersing the sample particles in the dispersion medium, and a state in which the circulation channel is in communication with the discharge channel for discharging the sample solution. Some are provided with a switching valve.
[0004]
In the particle size distribution measuring apparatus having the above configuration, the sample solution in the circulating sample solution is dispersed almost uniformly in the dispersion medium by the dispersing means while the sample solution is circulated in the circulation flow path by the pump. By keeping the pump and the dispersion means driven, the sample particles were scattered by the sample particles in the flow cell while irradiating the flow cell with laser light while maintaining the state where the sample particles were dispersed in the dispersion medium. The laser light is detected by a detector, and the intensity distribution of diffraction and / or scattered light obtained thereby is processed based on the Franhofer diffraction or Mie scattering theory to obtain the particle size distribution of the sample particles.
[0005]
[Problems to be solved by the invention]
However, in the conventional particle size distribution measuring apparatus, since the portion other than the flow cell is formed of an opaque material, the circulation state and the dispersion state of the sample particles in places other than the flow cell can be viewed from the outside. could not. Therefore, stagnant parts where the sample particles do not circulate smoothly, such as stagnation parts where the flow of the sample solution swirls in the circulation channel, gap parts where sample particles are clogged or deposited, uneven parts or step parts Even when sample particles having a specific particle diameter stagnated in such a stagnant portion, it could not be confirmed.
[0006]
Therefore, in the particle size distribution measuring apparatus, a part of the sample particles put into the circulation channel is stagnated at the stagnant portion formed in the circulation channel, and the sample particles are dispersed in an appropriate state in the dispersion medium. In some cases, the target particle size distribution could not be measured correctly.
[0007]
The present invention has been made in consideration of the above-mentioned matters, and the purpose thereof is particle diameter distribution measurement, which can confirm the circulation state and dispersion state of sample particles from the outside, and thus can accurately measure the particle size distribution. Is to provide a device.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a particle size distribution measuring device of the present invention includes a pump for circulating a sample solution in which sample particles are dispersed in a dispersion medium in a circulation channel, In addition to the circulation section, the dispersion means for dispersing the sample particles, and a switching valve for switching the circulation channel to a state communicating with the discharge channel for discharging the sample solution and a state not communicating with the circulation channel are provided. In the particle size distribution measuring apparatus having a flow cell for measuring the particle size distribution of the sample particles in the sample solution, the sample solution is supplied by the circulation unit , and the pipe diameter of the circulation unit is changed to be stepped. Sample particles in at least the sample solution, including a portion where the vortex is likely to be generated due to the difference in flow rate of the sample solution, and a portion where the flow direction of the sample solution changes Is characterized by a stagnation portion is easily formed circulation flow path portion is formed from a transparent material (claim 1).
[0009]
With the above-described configuration, it is possible to provide a particle size distribution measuring apparatus that can confirm the circulation state and dispersion state of sample particles from the outside, and thus can accurately measure the particle size distribution.
[0010]
Moreover, it is preferable that the light-shielding body which prevents that light enters into the flow cell is provided in the state which surrounds the measurement part provided with the flow cell (Claim 2). In this case, it is possible to reliably prevent the problem that the measurement result is adversely affected by the direct incidence of light from the outside to the flow cell, and the light is incident on the inside of the circulation part. also, it is possible to suppress the amount of light reaching the measuring unit including the flow cell the light thereof incident is reflected by the circulating portion.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
1 and 2 are a perspective view and an explanatory view schematically showing a configuration of a particle size distribution measuring apparatus D according to an embodiment of the present invention.
The particle size distribution measuring apparatus D is used for so-called wet measurement, that is, particle size distribution measurement performed in a state where sample particles as powder particles are dispersed in a dispersion medium. Among these, it is used for so-called flow measurement, that is, particle size distribution measurement performed while flowing sample particles.
[0012]
Further, the particle size distribution measuring device D irradiates the sample particles flowing in the flow cell with laser light, detects the laser light scattered by the sample particles in the flow cell with a detector, and obtains diffraction and / or scattering obtained thereby. This is a laser diffraction / scattering particle size distribution measuring device that processes the light intensity distribution based on Franhofer diffraction or Mie scattering theory to obtain the particle size distribution of sample particles.
[0013]
The particle size distribution measuring device D includes a pump 5 for circulating a sample solution 4 in which sample particles 2 as powder particles are dispersed in a dispersion medium 3 in the circulation channel 1, and the dispersion. The dispersion part 9 having the dispersion means 8 for dispersing the sample particles 2 in the medium 3, and the state where the circulation channel 1 communicates with the discharge path 10 for discharging the sample solution 4 and the state where it does not communicate. In addition to the circulating part A provided with a switching valve 11 made of, for example, a solenoid valve, the sample solution 4 is supplied by the circulating part A, and the particle size distribution of the sample particles 2 in the sample solution 4 is measured. It has the measurement part 7 provided with the flow cell 6 for this.
[0014]
The sample solution 4 is a suspension obtained by mixing sample particles 2 as a sample put into the circulation channel 1 and the dispersion medium 3 (for example, pure water or alcohol) for dispersing the sample particles. Is.
[0015]
The said pump 5 consists of a centrifugal pump as a circulation pump, for example. That is, the pump 5 is attached to the rotary shaft 13 provided in the vertical direction in the input chamber 12 for supplying the dispersion medium 3 and the sample particles 2 into the circulation flow path 1 and the lower end of the rotary shaft 13. The blade 14 accommodated in the flow path portion 1a following the bottom of the charging chamber 12, the pulley 15 attached to the upper end of the rotary shaft 13, and the motor 18 and the pulleys 15 and 17 each having the pulley 17 on the output shaft 16 are hung. It consists of a rotation transmission member 19 to be passed, and the sample solution 4 is sent out toward the flow cell 6 by the rotation of the motor 18 in a predetermined direction.
[0016]
A laser light source 20 is provided on one side of the flow cell 6, and a condenser lens 21 and a photodetector 22 are provided on the other side, respectively. The flow cell 6, the laser light source 20, the condenser lens 21 and the light are provided. The measuring unit 7 is formed by the detector 22.
[0017]
The dispersing means 8 is composed of, for example, an ultrasonic probe having an ultrasonic oscillator 8a that is vibrated by an oscillator, and is configured so that its output can be adjusted in a plurality of stages.
[0018]
The switching valve 11 includes a valve block 23 having an introduction port 23a for introducing the sample solution 4, a discharge port 23b for leading out, and a discharge port (not shown) communicating with the discharge passage 10. A block (not shown) that adjusts the flow rate of the sample solution 4 from the discharge port toward the discharge path 10 is capable of approaching and separating from the discharge port of the block 23.
[0019]
The discharge passage 10 is connected to the circulation passage 1 through the discharge port of the switching valve 11.
[0020]
Next, the operation of the particle size distribution measuring apparatus D will be described.
In order to measure the particle size distribution of the sample particles 2 using the particle size distribution measuring device D, first, the dispersion medium 3 is introduced from the introduction chamber 12 into the circulation channel 1 and then the sample particles 2 are introduced. By doing so, the sample solution 4 composed of the sample particles 2 and the dispersion medium 3 is introduced into the circulation channel 1. As described above, the sample solution 4 may be introduced into the circulation channel 1 by introducing the sample particles 2 and the dispersion medium 3 separately, or the sample particles 2 and the dispersion medium 3 may be introduced in advance. May be introduced after mixing to obtain the sample solution 4.
[0021]
Then, the sample solution 4 is circulated in the circulation channel 1 by driving the pump 5. At this time, the sample solution 4 passes through the circulation flow path 1 and flows in the order of the flow path portion 1 a, the flow cell 6 (measurement section 7), the dispersion section 9, and the switching valve 11 following the bottom of the input chamber 12. Become.
[0022]
When the pump 5 is driven, the sample solution 4 circulates in the circulation channel 1, and the sample particles 2 aggregated in the dispersion part 9 are dispersed, whereby the sample particles 2 are circulated in the circulation channel 1. Is dispersed in the dispersion medium 3, and in this state, the particle size distribution of the sample particles 2 is measured in the measurement unit 7. This measurement is performed in a state in which light from the outside is prevented from entering the circulation system including the circulation channel 1 including the channel portion 1a, the flow cell 6 (measurement unit 7), the dispersion unit 9, and the switching valve 11. At this time, for example, the circulation system is surrounded (covered) by a housing made of a wall member that blocks light (not shown).
[0023]
Instead of the configuration for preventing the incidence of light from the outside to all the circulation systems as described above, a light shielding body 24 for preventing the incidence of light from the outside only to the flow cell 6 (measurement unit 7) may be provided. For example, as shown by a broken line in FIG. 2, the light shield 24 is provided in a state of surrounding (covering) the measurement unit 7 including the flow cell 6, the laser light source 20, the condenser lens 21, and the photodetector 22. And a housing made of a wall member that blocks light.
[0024]
After the measurement is completed, the sample solution 4 is discharged from the circulation flow path 1 to the outside through the discharge path 10 by switching the switching valve 11.
[0025]
In the particle size distribution measuring apparatus D of the present invention, in order to confirm the circulation state and dispersion state of the sample particles 2 in the circulation part A, a part or all of the circulation part A is formed of a transparent material. Thus, the circulation state and the dispersion state of the sample particles 2 in the circulation part A can be seen from the outside through the part formed of the transparent material of the circulation part A. In order to allow the measurer to easily see the inside of the circulation part A from the outside, for example, the housing can be configured such that a part or all of the housing is removed, or a cover that can be opened and closed on the housing. Should be provided.
[0026]
The transparent material is a transparent or translucent material, such as acrylic or glass. If a material having chemical resistance such as acid resistance and alkali resistance is used as the transparent material, more versatility can be obtained.
[0027]
Therefore, the sample particles 2 are smoothly circulated in the circulation part A such as a stagnation part where the flow of the sample solution 4 is swirled, a gap part where the sample particles 2 are clogged or deposited, an uneven part or a step part. Even if the sample particle 2 having a specific particle diameter is stagnant in such a stagnant portion, it can be confirmed.
[0028]
Therefore, in the particle size distribution measuring apparatus D, the sample particles 2 put into the circulation part A stay in the stagnation part formed in the circulation part A, and the sample particles 2 are dispersed in an appropriate state in the dispersion medium 3. If not, it can be confirmed and some countermeasures can be taken, and if the dispersion of the sample particles 2 is in an appropriate state, the particle size of interest is confirmed after confirming that. The distribution can be measured correctly.
[0029]
In addition, in the case where a part of the circulation part A is formed from a transparent material, in order to achieve the purpose of finding the stagnation part of the sample particles 2 in the circulation part A, at least the stagnation part is easily formed. Possible parts (for example, a part in which the diameter of the pipe constituting the circulation system is changed to be stepped, a part in which vortex is likely to be generated due to a difference in the flow velocity of the sample solution 4 flowing in the pipe, and the circulation system , A portion where the flow direction of the sample solution 4 changes abruptly, a portion in the switching valve 11, a portion where stagnation may occur in the flow of the sample solution 4, a gap portion where sample particles may be clogged or deposited, unevenness It is desirable to form a part or a step part with a transparent material.
[0030]
In this embodiment, a case body 12a that forms the input chamber 12, the flow path portion 1a, the flow cell 6, a cell holder 6a that holds the flow cell 6, a block body 9a that constitutes the dispersing portion 9, and the valve block 23 A pipe 1b provided between the flow path portion 1a and the upper part of the cell holder 6a, a pipe 1c provided between the lower part of the cell holder 6a and the block body 9a, and between the block body 9a and the valve block 23 A block body (or pipe) 1d provided in the pipe, and a pipe 1e provided between the valve block 23 and the flow path portion 1a are formed of a transparent material.
[0031]
In the particle system distribution measuring apparatus D, the inside of the circulating part A is viewed from the outside through a part formed from a transparent material in order to confirm the circulating state and the dispersed state of the sample particles 2 in the circulating part A. It is possible to determine whether or not the cleaning has been successfully performed when the inside of the circulation part A is cleaned, and it can be performed by visual inspection from the outside through the portion formed from the transparent material. Similarly, it is possible to check the state of contamination of the circulatory system and obtain a guideline for maintenance (for example, cleaning).
[0032]
Of course, in the particle system distribution measuring apparatus D, when the measurer finds a contaminated part in the circulation system, the circulation system is used before the part affects the particle system distribution measurement. It is possible to take measures such as disassembling and cleaning, or cleaning by circulating a cleaning liquid in the circulation system.
[0033]
In order to more easily perform the work of disassembling and cleaning the circulation system when a contaminated part is found as described above, the particle distribution measuring device D is a part formed from a transparent material or All parts may have a structure that can be detached (disassembled) for each part. Here, the above-mentioned parts are, for example, the case body 12a that forms the input chamber 12, the flow path portion 1a, the flow cell 6, the cell holder 6a that holds the flow cell 6, and the dispersion unit 9 in the embodiment. A block body 9a, a valve block 23, a pipe 1b provided between the flow path portion 1a and the upper part of the cell holder 6a, a pipe 1c provided between a lower part of the cell holder 6a and the block body 9a, The block (or pipe) 1d provided between the block body 9a and the valve block 23 and the pipe 1e provided between the valve block 23 and the flow path portion 1a (parts) are meant.
[0034]
【The invention's effect】
As described above, according to the present invention, Ru can check the circulation state and dispersed state of the sample particles from the outside. In particular, it is easy to visually check from the outside whether the sample particles in the sample solution are stagnant in the circulation flow path portion where the sample solution is likely to stagnate and are in an appropriate dispersion state, and take measures such as washing. Therefore, it is possible to prevent a measurement from being performed while the sample particles are not properly dispersed in the dispersion medium, and to provide a particle size distribution measuring apparatus capable of accurately performing a predetermined particle size distribution measurement. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing a configuration of a particle size distribution measuring apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram schematically showing a configuration of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Circulation flow path, 2 ... Sample particle, 3 ... Dispersion medium, 4 ... Sample solution, 5 ... Pump, 6 ... Flow cell, 8 ... Dispersing means, 10 ... Discharge path, 11 ... Switching valve, A ... Circulation part, D ... Particle size distribution measuring device.

Claims (2)

A pump for circulating a sample solution in which sample particles are dispersed in a dispersion medium in the circulation channel, a dispersion means for dispersing the sample particles in the dispersion medium, and a circulation channel are the sample solution In addition to a circulation part provided with a switching valve for switching between a state communicating with a discharge path for discharging the liquid and a state not communicating with each other, the sample solution is supplied by this circulation part, and particles of sample particles in the sample solution In the particle size distribution measuring apparatus having a flow cell for measuring the diameter distribution, in the circulating portion , the portion where the pipe diameter is changed to be stepped, the portion where the vortex is likely to be generated due to the flow rate difference of the sample solution, formed of a transparent material at least a sample solution stagnation portion is easily formed circulation passage portion of the sample particles in the containing portion in which the direction is changed the flow of the sample solution Particle size distribution measuring apparatus, characterized in that the. The particle size distribution measuring apparatus according to claim 1, wherein a light blocking body that prevents light from entering the flow cell is provided so as to surround a measurement unit including the flow cell .

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