JPH08184548A - Dry method particle size distribution measuring apparatus - Google Patents

Abstract

PURPOSE: To obtain a dry method grain size distribution measuring apparatus which can measure the grain size distribution of a sample while excluding the data being detected when the concentration or the conditions of dispersion of a sample flowing through a measuring cell changes significantly. CONSTITUTION: A measuring cell 4 is set under a cap 1 for dropping a sample and air in the measuring cell 4 is made to flow by means of an air suction unit 5 coupled therewith at the lower end thereof so that the sample flows through the measuring cell 4. A laser beam magnifying unit 9 is disposed on one side of the measuring cell 4 a ring detector 10 for detecting the laser light transmitted through the measuring cell 4 is disposed on the other side, and a plurality of photodiodes 16 for detecting the laser lights scattering at different scattering angle from the sample flowing through the measuring cell 4 are arranged on the side thereof. Upper and lower limits are preset for the transmittance of the measuring cell 4 and only the data of transmitting light and scattering light, detected when the transmittance comes within the upper and lower limits, are selected by a CPU 13 and fed to a controller 14 where the grain size distribution of sample is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry particle size distribution measuring apparatus for measuring the particle size distribution of a sample by flowing a sample made of powder, particles or a mixture thereof with air.

[0002]

2. Description of the Related Art As a dry type particle size distribution measuring apparatus for measuring a particle size distribution such as powder and particles, for example, one shown in FIG. 3 is known. In FIG. 3, reference numeral 21 is a cup for containing the sample, and a nozzle 22 for dropping the sample is attached to the lower end of the cup. The reference numeral 23 designates a sample supply cylinder having a small diameter at the lower portion and having openings at the upper and lower ends.
The lower end of the sample is inserted, and the atmosphere flows into the sample supply cylinder 23 through the upper end opening. Reference numeral 24 denotes a measurement cell arranged in the vertical direction. The lower end small diameter portion of the sample supply cylinder 23 is inserted into the opening 24a at the upper end of the measurement cell, and the atmosphere flows into the measurement cell 24 through the opening 24a. The lower end of the measuring cell 24 has a small diameter and is connected to the air suction device 25.

Reference numerals 26 and 26 denote windows provided below the sample supply cylinder 23 and facing the measuring cell 24, through which light rays pass, and a laser light source 27 is disposed facing one window 26. 28 is a plurality of photodiodes arranged to face the windows 26, 26 in order to separately detect scattered light having different scattering angles generated by irradiating the laser light to the sample flowing through the measurement cell 24, When each output signal of each photodiode 28 is input to a control device (not shown) and the number of detection data input to the control device reaches a preset number, the control device calculates the particle size distribution of the sample. It is configured to go and display its particle size distribution.

In the conventional dry particle size distribution measuring apparatus, the laser light emitted from the laser light source 27 enters the measuring cell 24 and is transmitted therethrough. Further, the air in the measurement cell 24 is sucked by the operation of the air aspirator 25, and the air is sucked into the measurement cell 24 through the opening 24a, and the sample supply cylinder 23 is also sucked the air through the upper end opening. The air in the measuring cell 24 is caused to flow. On the other hand, the sample stored by vibrating the cup 21 is stored in the nozzle 22.
From the above, the sample is dropped in a dispersed state to the sample supply tube 23, and the sample is caused to flow from the sample supply tube 23 to the measurement cell 24 by the flowing air. The sample flowing through the measurement cell 24 is adjusted in advance so that its concentration falls within an appropriate range.

As described above, each of the photodiodes 28 detects a plurality of scattered lights having different scattering angles, which are emitted from the sample by being irradiated with the laser light transmitted through the measuring cell 24 in which the sample is flowing. The detection signal is input to the control device. In this way, when the number of times the photodiode 28 inputs the detection data to the control device reaches the set number of times,
The controller calculates the detection data and displays the particle size distribution of the sample. FIG. 4 is a flowchart showing the measurement of the particle size distribution.

The dry type particle size distribution measuring apparatus is, as described above,
The sample contained in the cup 21 and dropped from the nozzle 22 is caused to flow with an air flow, and the particle size distribution is detected. Then, as described above, the sample that drops from the nozzle 22 and flows,
Although the concentration is adjusted in advance so that it falls within the appropriate range, the concentration of the sample flowing through the measurement cell 24 varies within the appropriate range. Therefore, if the particle size distribution of the sample is measured with one-time detection data detected by each photodiode 28 and input to the control device, reproducibility and S
Since the / N becomes poor, the particle size distribution calculation processing of the sample is performed based on the detection data of a plurality of times to measure the particle size distribution, and the reproducibility and S / N are improved as described above. However, the detection data used for the particle size distribution calculation process is
All of the data detected by the photodiode 28 is of interest.

As described above, the sample is preliminarily adjusted so that the concentration of the sample flowing through the measurement cell falls within an appropriate range by comparing the concentration of the sample flowing through the measurement cell 24 with the above-mentioned appropriate range. If it is too low, the S / N of the detection data becomes poor, and if it is too high, the particle size distribution changes due to the multiple scattering of laser light. However, in the conventional dry particle size distribution measuring apparatus, when the sample concentration or the dispersion condition largely changes during the measurement of the particle size distribution, the detected data is also the object of the particle size distribution calculation process. Therefore, there are problems such that the S / N of the particle size distribution of the sample is deteriorated and the reproducibility of the particle size distribution is reduced due to the influence of multiple scattering.

The present invention is intended to solve the above problems and prevents detection data when the concentration or dispersion condition of a sample flowing through a measuring cell is greatly changed from being the object of particle size distribution measurement. Therefore, it is an object of the present invention to obtain a dry particle size distribution measuring device capable of always measuring a particle size distribution having good reproducibility and S / N.

[0009]

The dry particle size distribution measuring apparatus of the present invention drops a powdery or granular sample from a cup, supplies the dropped sample to a measuring cell in which air is flowing, and causes the sample to flow. In a dry particle size distribution measuring apparatus for measuring a particle size distribution of a sample based on detection data of scattered light and / or transmitted light of the sample by allowing a light ray to enter and pass through the measuring cell, scattering of the sample flowing through the measuring cell Scattered light and / or transmitted light only when the upper limit and the lower limit are set in advance for the light amount or the transmittance of the light beam that has passed through the measurement cell in which the sample flows and the upper limit and the lower limit are entered. It is characterized in that the particle size distribution of the powdery granular sample is measured by incorporating the detection data of 1.

[0010]

The dry particle size distribution measuring apparatus of the present invention drops the powdery and granular sample contained in it by the vibration of the cup in a dispersed state, supplies the sample to a measuring cell in which air is flowing, and causes the sample to flow. A light beam such as a laser beam is made incident on the measurement cell and transmitted. Then, only when the detection data of the scattered light scattered by irradiating the sample with the light beam and / or the transmitted light of the flowing sample falls within the preset upper limit value and lower limit value of the scattered light amount or the transmittance, Capture the detection data and measure the particle size distribution of the sample. The measurement of the particle size distribution of the sample based on the captured detection data is performed by capturing the detection data a plurality of times set in advance and performing a particle size distribution calculation process to measure the particle size distribution, or the detection that has been captured once. Measure the particle size distribution based on the data. As described above, since only the detection data when the amount of scattered light or the transmittance falls within the preset upper and lower limits, the particle size distribution with good S / N and reproducibility is always obtained. It is possible to measure.

On the other hand, detection data of scattered light and / or transmitted light that does not fall within the set upper and lower limits is not taken in. Therefore, while measuring the particle size distribution of the powdery granular sample, the concentration of the sample falling from the cup and the dispersion conditions change greatly, the sample concentration flowing through the measuring cell fluctuates greatly, and the scattered light or Even if the detection data of the transmitted light greatly fluctuates to a value that does not fall within the upper limit value and the lower limit value of the amount of scattered light or the transmittance set in advance, the greatly changed detection data is not taken. Therefore, the S / N of the particle size distribution of the sample is deteriorated due to the detection data of the sample when the concentration or dispersion condition of the sample is largely changed, and the reproducibility of the particle size distribution is deteriorated due to the influence of multiple scattering. Can be prevented.

[0012]

EXAMPLE An example of a dry particle size distribution measuring apparatus of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 is a cup for containing a powdery sample, and a nozzle 2 for dropping the sample is attached to a small diameter portion on the lower end side thereof. Reference numeral 3 is a funnel-shaped sample supply cylinder having a lower portion having a smaller diameter and opened at both upper and lower ends, and the lower end side of the cup 1 is inserted into the air intake port 3a of the upper large diameter portion thereof. Reference numeral 4 denotes a measurement cell arranged in the vertical direction. The lower end small diameter portion of the sample supply cylinder 3 is inserted into the opening 4a at the upper end of the measurement cell 4 so that the atmosphere can flow into the measurement cell 4 through the opening 4a. The lower end of the measuring cell 4 has a small diameter and is connected to the air suction device 5.

Reference numerals 6a and 6b denote windows provided below the sample supply cylinder 3 so as to face the measurement cell 4. Reference numeral 7 denotes a He-Ne laser, the laser light of which passes through the reflection mirrors 8 and 8 and the window 6a. A beam expander 9 arranged opposite to the beam expander 9 is configured to enter and transmit the measurement cell 4. Reference numeral 10 denotes a ring-shaped detector formed by arranging photodiodes or the like for detecting the laser light transmitted through the measurement cell 4 in a ring shape. The transmitted light data detected by the ring-shaped detector 10 is the multiplexer 11 and the A / D converter. It is selected by the CPU 13 through 12,
Only the selected transmitted light data is input to the control device 14. The control unit 14 has a display unit that displays the particle size distribution measured based on the captured detection data.
15 are provided. Reference numeral 16 denotes a plurality of photodiodes arranged to face the windows 6a and 6b in order to separately detect scattered light having different scattering angles generated by irradiating the sample flowing in the measurement cell 4 with the laser light. This each photodiode
The scattered light data detected by each of the 16 is also configured to be input to the control device 14 in the same manner as the transmitted light data.

When the CPU 13 sets the upper limit value and the lower limit value of an appropriate range in advance with respect to the transmittance of the light beam which passes through the measuring cell 4 in which the sample flows, when it falls within these upper and lower limit values. Only the detection data of the transmitted light and the scattered light are selected and input to the control device 14. On the other hand, the respective detection data when it does not fall within the upper and lower limit values is configured not to be output to the control device 14. The control device 14 takes in only the detection data selected and inputted by the CPU 13, and when the number of times of the taken detection data reaches a preset number, the granularity is obtained based on the respective detection data. The particle size distribution of the sample is measured by performing distribution calculation processing and displayed on the display unit 15. Reference numeral 17 is a feeder attached to the cup 1, and a motor 18 is used to vibrate the cup 1 via the feeder 17. 19 is a motor 18
Controller, which is connected to the controller 14.

In the dry particle size distribution measuring apparatus, the powdery and granular sample is stored in the cup 1, and the air in the measuring cell 4 is sucked by driving the air suction device 5, and the air is introduced into the measuring cell 4 through the opening 4a. Is sucked in, the air in the sample supply cylinder 3 is sucked, and the air is made to flow into the sample supply cylinder 3 from the suction port 3a, and an air flow is generated in the sample supply cylinder 3 and the measurement cell 4.
Further, the motor 18 is driven by the operation of the control device 14, and the sample is dropped from the nozzle 2 to the sample supply cylinder 3 by the vibration of the cup 1. The dropped sample flows from the sample supply cylinder 3 to the measurement cell 4 by the air flow and is accommodated in the air suction device 5.
Then, the laser beam of the He—Na laser 7 is made incident on the measuring cell 4 in which the sample is flowing by the beam expander 9 and transmitted.

The laser light transmitted through the measuring cell 4 is incident on the ring-shaped detector 10 and is detected, and the detected transmitted light data is the multiplexer 11 and the A / D converter 12.
Then, the data is selected by the CPU 13 as described above and input to the control device 14. On the other hand, each of the plurality of photodiodes 16 detects a plurality of scattered lights having different scattering angles generated by irradiating the sample flowing in the measurement cell 4 with the laser light, and the scattered light data thereof are also transmitted. It is input to the control device 14 in the same manner as the optical data. Then, when the number of acquisitions of each detection data input to the control device 14 reaches the set number, the control device 14 performs a particle size distribution calculation process based on each detection data to measure the particle size distribution of the sample. Display 15
To be displayed. FIG. 2 is a flowchart showing the measurement of the particle size distribution by processing the detection data.

As described above, in the transmitted light data and scattered light data detected by the ring-shaped detector 10 and the plurality of photodiodes 16, respectively, the light transmittance falls within preset upper and lower limits of the light transmittance. Only the detection data at that time is selected by the CPU 13 and input to the control device 14. Based on only the selected detection data, the control device 14
Performs particle size distribution calculation processing to measure the particle size distribution of the sample.
That is, only the data detected when the sample concentration flowing through the measuring cell 4 falls within a preset concentration range is used for measuring the particle size distribution of the sample, and the sample concentration or dispersion flowing through the measuring cell 4 is measured. The detection data obtained when the conditions fluctuate greatly are not used for measuring the particle size distribution. Therefore, it is possible to always measure the S / N and the particle size distribution with good reproducibility.

In the above-mentioned embodiment, the upper limit value and the lower limit value are set in advance for the transmittance of the laser light passing through the measuring cell 4 in which the sample flows, but instead of this light transmittance, the measuring cell 4 is flown. It is also possible to set the upper limit value and the lower limit value in advance for the amount of light that is scattered by irradiating the sample with the laser light. The detection data used for measuring the particle size distribution of the sample may be either the transmitted light data or the scattered light data. As described above, the upper and lower limit values are set in advance for the light transmittance or scattered light amount of the measurement cell, and the particle size distribution measurement of the sample is performed only with the detection data within that range, so the detection conditions for each captured detection data However, it is possible to measure the particle size distribution of the sample with only one piece of detection data, since all of them are performed in good condition. In this case as well, the particle size distribution with good S / N and reproducibility can be measured. it can. In addition, although the transmitted light data is sorted by digital signals, this is an analog circuit equipped with a detection data sorting circuit to measure the particle size distribution of the sample with the data within the upper and lower limit values set by analog. It is also possible to do so.

[0019]

As described above, the dry particle size distribution analyzer of the present invention has an upper limit value and a lower limit value for the amount of scattered light of the sample flowing through the measuring cell or the light transmittance of the sample passing through the measuring cell. The particle size distribution of the powder-granular sample is measured by presetting the detection data of the scattered light and / or the transmitted light only when it falls within the upper and lower limits. That is, the sample concentration flowing in the measurement cell was selected and used only for the data detected when the concentration was in the appropriate range, and the particle size distribution of the sample was measured. The detection data at this time are not used for particle size distribution measurement. Therefore, it is possible to always measure the particle size distribution with good S / N and reproducibility without fear that the S / N and reproducibility are deteriorated due to the detection data when the sample concentration or the dispersion concentration is largely changed. It is possible. Further, it is possible to measure the particle size distribution of the sample on the basis of the detection data obtained by the selection and the acquisition a plurality of times, and the detection data obtained by the selection flow through the measurement cell. Since only the data detected when the condition of the sample concentration to be applied is within the appropriate range, it is possible to measure the particle size distribution of the sample with good S / N and reproducibility even with only one detection data.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a flowchart showing measurement of particle size distribution according to the present invention.

FIG. 3 is a configuration diagram of a conventional example.

FIG. 4 is a flowchart showing measurement of a particle size distribution of a conventional example.

[Explanation of symbols]

1: Cup, 2: Nozzle, 4: Measuring cell, 9: Beam expander, 10: Ring detector, 13: CPU, 14: Controller, 16: Photodiode.

Claims (1)

[Claims] 1. A powder-granular sample is dropped from a cup,
The falling sample is supplied to a measuring cell in which air is flowing to flow, and a light beam is made incident on the measuring cell to be transmitted, and a sample light is transmitted based on detection data of scattered light and / or transmitted light of the sample. In the dry type particle size distribution measuring apparatus for measuring the particle size distribution, the upper limit value and the lower limit value are set in advance for the transmittance of the light scattered through the measuring cell in which the scattered light amount or the sample flowing in the measuring cell flows in advance, A dry-type particle size distribution measuring apparatus, wherein the particle size distribution of a powdery granular sample is measured by taking in detection data of scattered light and / or transmitted light only when it falls within the upper and lower limits.