JPS63279143A - Decanter type particle size distribution measuring apparatus - Google Patents

Abstract

PURPOSE:To prevent possible concordance of a suspension in a measuring cell, by providing an electric cooler on a rotary disc equipped with a measuring cell in such a manner as to change according to revolutions through a draft limiter having an opening growing larger gradually outward. CONSTITUTION:A sample particulate material to be measured is made suspended in a medium liquid and sealed into a measuring cell 1. The cell 1 is mounted on a rotary disc 2 and kept rotatively driven with a motor 3 to determine the density of the sample material by transmitting light measurement. An electronic cooler 11 is arranged in proximity of the rotary disk 2 and current is applied thereto corresponding to revolutions of the rotary disc 2 with a cooling control circuit 12 to blow a cool air against the measuring cell 1. A draft limiter 10 is arranged between the device 11 and the rotary disc 2. Thus, the more friction heat of the cell 1, the larger amount of cool air is blown with an opening so arranged as to grow broader away from the radial center axis of the rotary disc 2 formed on the limiter 10.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a centrifugal sedimentation type particle size distribution measuring device using a liquid phase.

<Conventional technology and its problems> In a particle size distribution measuring device based on centrifugal liquid phase sedimentation method,
Generally, sample particles are dispersed in a medium to create a suspension.
The suspension is sealed in a measurement cell and mounted on a rotating disk.

Then, the particle group is sedimented in the centrifugal force field generated by the rotation of the rotary disk, and the suspension concentration is measured moment by moment (at a predetermined sedimentation distance) using a light transmission method, etc., and the particle size distribution of the sample particles is determined from the change over time. demand.

In such a centrifugal sedimentation type particle size distribution measuring device, when the rotary disk is rotated at high speed, the temperature of the measurement cell increases due to friction with the air. This is not a big problem if the entire measurement cell is heated uniformly, but the outside of the rotary disk, that is, the part far from the center of rotation, has a faster speed and a larger temperature rise, so there is a temperature difference between both ends of the measurement cell. occurs, and a gentle convection occurs in the suspension. Due to this convection, samples with a small difference in specific gravity relative to the medium and small particles have a large effect on the sedimentation rate, causing irregular turbulence in concentration changes and making the obtained particle size distribution inaccurate. .

Conventionally, in order to prevent such phenomena from occurring, outside air was pumped into the measurement chamber to suppress the temperature rise in the measurement cell.
When the rotational speed reached about 10.00 rpm, such air blowing alone was insufficient.

<Means for Solving the Problems> The present invention provides a centrifugal sedimentation type particle size distribution measuring device that can always obtain accurate measurement results without causing the above-mentioned convection even when high-speed rotation is applied. As shown in FIGS. 1 and 2 corresponding to the embodiment, the electronic cooling device is capable of blowing cold air onto the rotating measurement cell 1 mounted on the rotary disk 2. 11, a cooling control circuit 12 that changes the amount of power supplied to the electronic cooling device 11 according to the rotation speed of the rotary disk 20, and a cooling control circuit 12 that is interposed between the cold air discharge port of the electronic cooling device 11 and the rotation locus of the measurement cell 1, A plurality of openings 10a such that the farther away from the rotation center axis C of the rotary disk 2, the larger the amount of cold air passing through the openings 10a.

The present invention is provided with a ventilation restricting body 10 having l Q b, -, 10n.

<Function> Since the amount of temperature rise in the measuring cell 1 is based on the frictional force with the air determined by the rotation speed of the rotary disk 2, the amount of power supplied to the electronic cooling device 11 can be changed in accordance with this rotation speed to cool it down. If the force is controlled, the temperature of the entire measuring cell 1 will not rise regardless of the rotation speed.

Furthermore, due to the intervention of the ventilation restrictor 10, temperature gradients within the measuring cell 1 are eliminated.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of a ventilation restricting body 10 thereof.

The sample particles to be measured are uniformly dispersed in a medium and placed in a suspension state in a measurement cell i formed of a transparent member. This measurement cell 1 is detachably attached to a rotary disk 2 that is rotationally driven by a motor 3. motor 3
is configured such that its rotation speed is controlled by an output from a motor controller 9 based on a rotation speed setting signal supplied from a microcomputer 8.

A light source 4 and a light receiving element 5 facing the light source 4 are disposed at a position a predetermined distance in the radial direction from the rotation center axis C of the rotary disk 2, and the measurement cell 1 mounted on the rotary disk 2 is It is configured to cross between the light source 4 and the light receiving element 5 by its rotation. The rotational position of the measuring cell 1 is detected by a photo ink clubter (not shown) or the like, and the output signal of the light receiving element 5 at the time when the measuring cell 1 crosses between the light source 4 and the light receiving element 5, that is, the measuring cell 1 The transmitted light measurement signal is sent to the amplifier 6 as suspension concentration measurement data. A-D
It is configured so that the data is collected every moment by a microcomputer 8 via a converter 7.

The microcomputer 8 can calculate the particle size distribution of the sample particles using a known calculation method based on the temporal changes in the concentration measurement data.

Now, an electronic cooling device 11 is disposed close to the rotary disk 2, and its cold air outlet faces the rotary disk 2 so that cold air can be blown onto the rotating measurement cell 1. . The electronic cooling device 11 is a known device that includes a Peltier element, a blower, a heat exchanger, etc., and the temperature of the air blown from its discharge port (temperature difference with respect to room temperature) is determined by the current flowing through the Peltier element. The current flowing through this Peltier element is supplied from the cooling control circuit 12.

The cooling control circuit 12 includes a look-up table 12a, a D-A converter 12b for analogizing data from the look-up table 12a, and a D-A converter 12b for analogizing data from the look-up table 12a.
- A current controller 12c such as a power amplifier that outputs a current according to the output of the A converter 12b.

The look-up table 12a takes the rotational speed of the rotary disk 2 as an argument, and outputs from the electronic cooling device 11 the cooling power necessary to resist the heat generation of the measurement cell 1 at each rotational speed and prevent the temperature from rising. It is configured to input the rotation speed setting signal from the microcomputer 8 mentioned above and output the corresponding current data. Generally, the relationship between the number of rotations and the required current cannot be expressed as a negative order number, so this relationship is determined experimentally in advance and written in the look-up table 12a.

A ventilation restrictor 10 is disposed between the cold air outlet of the electronic cooling device 11 and the measurement cell 1 . This ventilation restricting body 1
0, as shown in FIG. 2, a plurality of slit-like openings 10a, 10b are provided in the flat plate material, parallel to each other and extending in directions perpendicular to the radial direction of the rotary disk 2.
, -, f On, each opening 10a, 10b thereof.

The width of −1·, 10n becomes wider as the distance from the rotation center axis C of the rotary disk 2 increases. Therefore, the further away from the axis C, that is, the more the cold air from the electronic cooling device 11 passes through the ventilation restricting body 10 and is blown onto the rotating measuring cell 1.

In the above embodiments of the present invention, the microcomputer 8
When the motor 3 is rotated by giving an arbitrary rotational speed setting signal from Rising is prevented. In addition, in the measurement cell 1,
The further away from the center of rotation, in other words, the areas where more heat is generated due to friction with the air, the more cold air will be blown into the area, and no temperature gradient will occur inside.

Note that the ventilation restricting body 10 is not limited to the above-mentioned embodiments, and for example, as shown in the front view in FIG.
b, ---, 30n may be formed; rather, in this case, cold air can be blown onto the measuring cell 1 with a more ideal distribution. Alternatively, the same effect can be obtained by making the widths of the openings the same and making the arrangement denser as the distance from the rotation center axis C increases.

Furthermore, in the cooling control circuit 12, it goes without saying that a broken line approximation function generation circuit may be provided on the output side of the DA converter 12b in place of the look-up table 12a.

<Effects of the Invention> As explained above, according to the present invention, an electronic cooling device capable of blowing cold air onto a rotating measuring cell is provided, and the amount of power supplied to the electronic cooling device is controlled according to the rotational speed of the measuring cell. In addition, a ventilation restrictor was installed between the cold air discharge port of the electronic cooling device and the rotating measurement cell, so that the amount of cold air passing through increases as the distance from the rotation center axis increases. Regardless of the number of rotations, the temperature rise is always prevented, and since a large amount of cold air is blown onto the measurement cell at locations where a large amount of heat is generated, it is difficult for a temperature gradient to occur inside the measurement cell. As a result, no convection occurs in the suspension within the measurement cell, making it possible to always obtain accurate particle size distribution measurement results.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of a ventilation restricting body 10 thereof. FIG. 3 is a front view of a ventilation restrictor according to another embodiment of the present invention. 1...Measuring cell 2...Rotary disk 3...Motor 4...Light source 5...Light receiving element 8...Microcomputer 9...Motor controller 10...Ventilation restricting body 10a, 10b, --, 10n--Opening portion 11...
Electronic cooling device 12...Cooling control circuit 12a...Look-up table 12b...DA converter 12c...Current controller

Claims (1)

[Claims] A suspension obtained by dispersing sample particles in a medium is housed in a measuring cell, and the measuring cell is mounted on a rotary disk to give it rotation, and the measuring cell is placed at a position a predetermined distance from the central axis of rotation. In this device, the particle size distribution of the sample particles is determined by measuring the concentration change over time of the suspension in the cell. A cooling control circuit that changes the amount of power supplied to the electronic cooling device accordingly, and a cooling control circuit that is interposed between the cold air discharge port of the electronic cooling device and the rotation locus of the measurement cell, and the circuit that changes the amount of power supplied to the electronic cooling device according to the A centrifugal sedimentation type particle size distribution measuring device characterized by comprising a ventilation restricting body having a plurality of openings that allow a large amount of cold air to pass through.