JP2570823B2 - Suspension sampling device for particle size distribution measurement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a liquid phase particle size distribution measuring apparatus based on a laser diffraction method, a light scattering method, a liquid phase sedimentation method, or the like. The present invention relates to a sampling device for performing dispersion and liquid sending to a measurement system.

<Prior Art> In any of the particle size distribution measuring devices based on the above-described measuring methods, the particle size distribution is measured using a suspension in which the powder to be measured is uniformly dispersed in an appropriate medium.

As a sampling device for supplying such a suspension to a measurement system of the device, a device exemplified in FIGS. 3 and 4 has been conventionally used. These conventional devices are:
In each case, a so-called ultrasonic bath equipped with an ultrasonic oscillator 30 (40) is used as a sample tank 31 (41), and the suspension L in the tank is dispersed by ultrasonic irradiation, and a propeller stirrer 32 (4) is used.
While being agitated by 2), the liquid is circulated between the measurement system and the sample tank 31 (41) by the liquid sending pump 33 and the circulation pipe group.

The apparatus shown in FIG. 3 employs a method in which a relatively small propeller 32a is rotated at a high speed and agitated with respect to a sample tank 31, and the apparatus shown in FIG. 4 is a relatively large propeller.
A method is used in which 42a is rotated at a low speed and stirred.

<Problems to be Solved by the Invention> In the method shown in FIG. 3, the cleaning of the inside of the sample tank 31 is relatively easy, but the position of the propeller 32a is appropriately adjusted based on the amount of liquid to be charged into the sample tank 31. If it is not set to a sufficient value, a sufficient stirring effect cannot be obtained. In other words, when the liquid volumes are the same, the propeller 32 as shown in FIG.
If the position of a is too low, relatively large-diameter heavy particles are not lifted by the rotation of the propeller 32a but are pushed around the outlet of the sample tank 31 by the centrifugal force, and mainly light particles are sucked and guided to the measurement system. Conversely, if the position of the propeller 32a is too high as shown in FIG.
The energy of the stirring is not sufficiently transmitted to the entire liquid, and particles remain at the bottom of the sample tank 31.

In the method shown in FIG. 4, although the difference in the effect of the agitation by the liquid amount as described above is hard to appear, mixing of air bubbles is remarkable when the rotation speed of the propeller 42a is increased, and when the liquid amount is considerably small, the propeller 42a It becomes necessary to make the rotation speed extremely low, so that sufficient stirring cannot be achieved. Further, it is relatively difficult to clean the inside of the sample tank 41.

SUMMARY OF THE INVENTION An object of the present invention is to provide a suspension sampling apparatus for particle size distribution measurement that can always obtain an optimum stirring effect and perform accurate and reproducible sampling regardless of the amount of suspension in a sample tank. Is to provide.

<Means for Solving the Problems> In order to achieve the above object, in the present invention, as shown in FIG. 1 corresponding to the embodiment, the height of the propeller 3a of the stirrer 3 in the sample tank 1 is set. A liquid level detector 14 for detecting the level of the suspension L in the sample tank 1 is provided, and a control unit 16 based on the output of the liquid level detector 14 is provided. The drive mechanism 4 is driven in response to the drive command to automatically change the height of the propeller 3a.

<Operation> The control unit 16 controls the output of the liquid level detector 14, that is, the sample tank 1.
A drive command is given to the drive mechanism 4 in order to change the height of the propeller 3a in accordance with the level of the suspension L present in the inside.

The level of the suspension L in the sample tank 1 and the height of the propeller 3a capable of supplying the suspension L with an optimum stirring effect can be determined based on the shape of the sample tank 1 and the like. There is a correlation. The control unit 16 outputs a drive command according to the output of the liquid level detector 14 based on such a correlation, so that the height of the propeller 3a can always be controlled to an optimum height.

<Embodiment> FIG. 1 is an overall configuration diagram of an embodiment of the present invention. An ultrasonic oscillator 2 composed of an ultrasonic oscillator 2a and an ultrasonic oscillation circuit 2b for providing a drive signal to the ultrasonic oscillator 2a is mounted on a sample tank 1 having a liquid outlet 1a at the lower end of the funnel. The suspension L can be irradiated with ultrasonic waves.

The propeller 3 a of the stirrer 3 is inserted into the sample tank 1 from above the sample tank 1. The stirrer 3 includes a propeller 3a, a motor 3b, and a propeller shaft 3c for connecting the propeller 3a, and is configured so that the drive mechanism 4 can change the insertion height of the propeller 3a into the sample tank 1.

That is, the drive mechanism 4 supports the motor 3b of the stirrer 3 and is vertically displaceable along a guide (not shown), and a pinion gear 4b meshing with the rack 4a.
And a pulse motor 4c for rotating this pinion gear 4b
The entire stirrer 3 can be moved up and down by driving the pulse motor 4c.

The liquid outlet 1a of the sample tank 1 communicates with the liquid inlet 6 of the measuring system via the suction pipe 5, and the liquid outlet 7 of the measuring system communicates with the inlet of the liquid pump 8. In addition, a return pipe 9 facing the inside of the sample tank 1 from above the sample tank 1 is provided at the discharge port of the liquid sending pump 8.
Is connected. The liquid sending pump 8 includes a motor control circuit 10
The suspension L is driven by a motor 11 whose ON / OFF is controlled by the liquid supply pump 8, and the suspension L is supplied to the measurement system → the liquid supply pump 8 → the return pipe 9 → the sample tank 1 → the suction pipe 5 → the measurement system. And will circulate. In addition, a drain pipe 13 is connected to the liquid outlet 1 a of the sample tank 1 via an on-off valve 12.

Above the sample tank 1, an ultrasonic liquid level detector 14 is provided. The liquid level detector 12 irradiates a pulse-like ultrasonic signal into the sample tank 1. The reflected signal is incident, and the level of the suspension L in the sample tank 1 can be detected based on the echo time.

The output of the liquid level detector 14 is taken into the control unit 16 via the amplifier 15. The control unit 16 is composed of a microcomputer and its peripheral devices, etc., and has a liquid level detector.
The ultrasonic oscillator 2b and the motor control circuit described above, taking in the data from
It is configured so that an OFF command can be given to 10 and a drive signal can be supplied to the pulse motor 4c of the drive mechanism 4. The control unit 16 also has an alarm device 17 that can issue various alarms based on a command from the control unit 16.
Is connected.

FIG. 2 is a flowchart showing the contents of the program written in the ROM of the control section 16. The operation of each section will be described below with reference to this figure.

In the control unit 16, a liquid level lmin in which the liquid amount in the sample tank 1 is close to 0 and a liquid level lmax immediately before the liquid overflows are set in advance.

The liquid level data 1 from the liquid level detector 14 is collected, for example, at a certain timing including the start of the apparatus driving, and is compared with lmin and lmax. If l is smaller than lmin, that is, if it is determined that the suspension L is hardly contained in the sample tank 1, the ultrasonic oscillator 2 is immediately turned off and an alarm 17 issues an alarm to that effect. Sample tank 1
When the ultrasonic oscillator 2 is driven in a state where no liquid is contained therein, it generally causes damage to the apparatus and performance degradation. However, the above-described operation has caused the liquid to decrease due to forgetting to fill the liquid or for some other reason. Therefore, it is possible to prevent the performance of the apparatus from being deteriorated.

If l is greater than lmax, the liquid feed pump 8 is stopped, and an alarm is issued by the alarm 17 to urge the removal of the excess suspension L.

Now, if l is between lmin and lmax, that is, the suspension L
It is determined that the ultrasonic oscillator 2 may be driven without overflowing. If the liquid level is within an appropriate range, the stirring effect by the propeller 3a is maximized based on the magnitude of l. The optimum height of the propeller 3a to be used and sent from the liquid outlet 1a is determined, and the pulse motor 4c of the drive mechanism 4 is driven based on the optimum height.

Here, the relationship between the liquid level in the sample tank 1 and the optimum height of the propeller 3a is determined by the shape of the sample tank 1, the stirring capacity of the propeller 3a, and the like. The optimal height of the propeller 3a can be immediately determined from the data 1 by storing the data in the control unit 16 in the form of a table or a table. When the optimum height of the propeller 3a is almost proportional to the liquid level, the propeller is calculated by a simple proportional calculation using the data l.
The optimum height of 3a can be determined.

By the above operation, the propeller 3a can always be positioned at the optimum height regardless of the amount of the suspension L in the sample tank 1.

Incidentally, the present invention is not limited to the above embodiments,
The drive mechanism 4 can employ any mechanism other than the rack and pinion system, for example, any mechanism such as a cam mechanism, a ring mechanism, and a crank mechanism. In addition, the motor 3b is fixed without moving the entire agitator 3 up and down. Then, a modification such as changing only the height of the propeller 3a is also possible.

Further, as the liquid level detector 10, it is needless to say that other known liquid level detectors such as a float type can be adopted in addition to the ultrasonic type.

<Effects of the Invention> As described above, according to the present invention, the liquid level in the sample tank containing the suspension is detected, and the propeller height of the stirrer is adjusted according to the detection result. Since the liquid is positioned automatically at the optimum height where the liquid can be sent while maximizing the effect, the liquid can always be sent in the optimal stirring state regardless of the amount of the suspension, and there is no individual difference Accurate particle size distribution measurements with good reproducibility can be obtained.

It should be noted that the liquid level detection data in the present invention is a full-safe method such as preventing the performance of the apparatus from being deteriorated due to the driving of the ultrasonic oscillator when the liquid volume in the sample tank is too small, or preventing overflow due to excessive liquid volume. It can also be used for functions.

[Brief description of the drawings]

1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is a flowchart showing the contents of a program written in a ROM of a control unit 16, and FIGS. 3 and 4 are conventional suspension sampling devices, respectively. FIG. 5 is an explanatory view of the stirring effect by the propeller height of the conventional device. DESCRIPTION OF SYMBOLS 1 ... Sample tank 2 ... Ultrasonic oscillator 3 ... Stirrer 3a ... Propeller 4 ... Drive mechanism 5 ... Suction pipe 8 ... Liquid feed pump 9 ... Return pipe 14 ... Liquid level detector 16 ...... Control unit

Claims (1)

(57) [Claims] An apparatus for supplying a suspension obtained by dispersing a powder to be measured in a medium to a measurement system of a liquid-phase type particle size distribution measuring apparatus, wherein an ultrasonic oscillator is internally provided by an ultrasonic oscillator. , A pipe and a liquid feed pump for circulating the suspension in the sample tank between the measurement system and the sample tank, and a propeller for stirring the suspension in the sample tank A stirrer comprising: a drive mechanism for changing the height of the propeller in the sample tank; a liquid level detector for detecting a liquid level in the sample tank; and a liquid level A suspension sampling device for measuring a particle size distribution, comprising a control unit for giving a drive command to the drive mechanism based on an output of a detector.