JPH07198581A - Method and equipment to analyze grain size in grain and minute grain range - Google Patents

Abstract

PURPOSE: To strictly and accurately obtain measurement values in a reproductive manner by detecting the quantity of a gas flow and keep it constant during sieving process. CONSTITUTION: A cover 4 is removed, sieved material is filled in a strainer 3 and the cover is tightly capped. Compressed air is supplied from a guide pipe 7, the quantity is detected by a nozzle 6 and the humidity and the temperature are measured by a humidity sensor 10 and a temperature sensor 11. The flow speed, humidity and temperature of the supplied air is controlled until the measurement values reach set target values. The supplied air is passed through a grooves nozzle 2 and a sieving cloth for the strainer 3 and fine components are moved with an air stream and carried out of a suction fitted pipe 8. A differential pressure, an air temperature, a relative humidity and a nozzle rotating number are detected as measurement values, a sieving time, a volume flow rate, an air temperature and a nozzle rotating number and direction are input as input values and an aspirator rotating number, a nozzle motor voltage, a heater voltage, a compensator voltage and an operating time are output as control values by a single chip computer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for analyzing the particle size within a fine / fine particle range by a gas jet type sieve, in which a sieved material is charged into a sieving cloth. A gas jet is sucked through a sieving cloth and a sieve by a groove-shaped nozzle rotating downward, fine-grained components are entrained by the gas flow, and vice versa by the gas flow, through a sieving cloth and below the sieving cloth. And a device for carrying out the method.

[0002]

2. Description of the Prior Art So-called laboratory air jet sieves in which a strainer is held in an instrument casing are known in the prior art. The air supply port is pouring under the strainer. The groove-shaped nozzle connected to this air supply port is rotatably supported in a sieving casing and is electrically driven. This groove-shaped nozzle rotates below the sieving cloth of the strainer at a fixed number of revolutions, and the sieving material charged in the sieving cloth swirls and rises. The supplied air is discharged through the discharge fitting pipe, and the fine grain component is carried out through the discharge fitting pipe. This fine-grained component is entrained by the air stream and conveyed through a sieving cloth. The strainer is closed with a lid. Additionally, this device is equipped with a mechanical timer. The sieving time can be adjusted via this. In addition, an indirect air amount adjustment is performed by an outside air throttle provided in the blower connection port or by a rotation speed setting device separately provided in the assembly device that generates negative pressure, and the assembly device is fitted with the air discharge fitting of the device. Connected to the pipe.

Conventional conventional equipment of this kind for laboratory applications is relatively inaccurate, while the mechanical timer has the inaccuracy of having slight adjustment and repeatability, while indirectly. Air volume measurement is only performed,
As a measure for adjusting the air amount, a negative pressure at a limited portion of the exhaust passage is used. However, this negative pressure is geometry dependent and does not allow exact deduction of process-critical parameters. As a result, the measurements on the same instrument are only approximately comparable, and the inference of product load is poorly possible from empirical values.

[0004]

On the basis of this prior art, the object of the invention is to provide a method and a device for carrying out this method, which enable a precise and exactly reproducible measurement value. .

[0005]

The solution according to the method of this problem is specified in claims 1-8. A solution according to the device of this problem is specified in claims 9 to 16.

According to the invention, the drawbacks of the adjustment accuracy are eliminated by the precise detection of the charge air quantity and the control of the volume flow rate of the charge air. The gas supply amount can be detected by a bench lily nozzle and a differential pressure measurement at this nozzle. But other methods of flow measurement, such as Prandtl tubes,
Flow measurements with hot wires or measuring turbines can also be used. In order to ensure measurement accuracy, the humidity and temperature of the supply gas are also detected (the gas is in this case also air in particular).

The feed rate is continuously adjusted to the target value by varying the blower speed, depending on the measured and corrected volumetric flow rate.

The blower can be used in the intake operation or the compression operation, the blower is attached to the exhaust port during the intake operation, and the blower is attached to the intake port during the compression operation. Strict and reproducible measurement of the amount of gas flowing through a channel nozzle is of great importance in being able to compare the sieving results of different instruments, as well as the general requirement for the best analytical quality. Otherwise, especially in the case of products that are sensitive to wear and can be crushed, the results will be very erroneous.

The stepless change of the number of rotations of the nozzle and the change of the shape and the rotation direction of the nozzle aim at the same direction.
The number of rotations of the nozzle is an important criterion for the loading time and loading frequency of the sieve. The nozzles can be replaced with nozzles with different groove geometries or multi-arm nozzles for product compatibility.

While it is known in the art to seal a strainer in a machine to a machine casing in a purely static seal, a pure static seal often results in a leak and thus an erroneous air supply.
This again distorts the measurement result.

The compressed air-loaded annular tube provided according to the invention eliminates this drawback and allows a reliable sealing of the strainer, and thus of the sieving chamber, with respect to the instrument casing, even in the case of large strainer tolerances. It is an essential precondition for a rigorous analysis. In one form of the invention, a diaphragm compressor for generating pressure can be utilized, which is switched in such a way that the shut-off of the compressor causes the annular tube to be switched pressureless by means of a valve. You can The strainer can then be easily removed and reinserted without great expenditure of force.

Changing the height and shape of the sieving chamber by changing the sieving chamber cover (lid) also helps to change the product load.

The inserted lid is preferably flat. However, the lid may also be concavely or convexly curved and / or provided with a structured surface in order to properly regulate and control the flow. The sieving chamber is sealed with an expanded rubber cord or a flat gasket.

In order to achieve comparability of the measurement and analysis results, it must be ensured that the humidity and temperature of the media causing the sieving are also detected and controlled. The control can be carried out by means of heating elements, dryers or air humidifiers provided in the preceding stage. These components are included in the air volume calculation together by temperature and humidity measurement, and the indicated values are corrected. Moreover, they are
It is integrated into the process control system to provide proper conditioning of the screen. In the case of hygroscopic products, the air can be preheated to lower the relative air humidity and thus obtain sieving properties. In the case of electrostatic charging, it is possible to reduce the charging of the sieved product by increasing the air humidity. The measuring time is preset with a precision of seconds and strictly followed. This is especially important for products that are sensitive to dispersion and must not be exposed to strong mechanical loads, for example. In this case, some products only withstand a sieving time of 1 minute, so inaccurate time control significantly impairs the sieving result.

In order to keep the sieving time as short as possible, the exhaust flow is monitored optically and the particle flow is measured. If a certain debris criterion is met, for example 0.1% per minute according to DIN, the measurement is terminated after an adjustable wake time. In this case, it is particularly advantageous for measurement without a set time and thus automation of the measurement sequence.

In order to process large amounts of information and to be able to perform various functions in a reproducible way, all control of the device is carried out by an electronic single chip computer control system. This control system includes the required hardware and software. The adjustment and measurement values are displayed digitally and can be read on an illuminated liquid crystal display. Moreover, the single chip computer realizes the RS-232 interface, through which the print output of the record and the input / output of the PC are possible. By virtue of these interfaces and the technical construction of the laboratory sieving machine, the system still has to automate only strainer replacement and weighing, the basis and construction of an automatic analytical device for controlling the analytical course with a computer. Is an element.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS A schematic embodiment is shown in the drawing and will be explained in more detail below.

The analytical sieving machine consists of a sieving machine casing 1, in which a channel nozzle 2 is rotatably held and can be driven via a drive motor 5. A strainer 3 detachably provided above the groove-shaped nozzle 2 is closed by a sieving chamber lid 4. A bench lily nozzle 6 is connected to the air inlet pipe 7, from which the supply air is sent to the channel nozzle 2. Reference numeral 8 is an intake pipe through which the supply air is sucked. Reference numeral 9 is an annular tube gasket, which can be inflated by a compressor for the purpose of sealing and can be evacuated for the purpose of replacing the strainer 3. As shown in FIG. 2, the humidity sensor 10 and the temperature sensor 1 are arranged in the inlet pipe 7.
1 and the signal detection board 12 are integrated. When operating the analytical sieving device, first the lid 4 is removed and the sieved material is poured into the strainer and the lid is resealed. Subsequently, compressed air is supplied through the introduction fitting tube 7, or intake air is sucked into the apparatus through a suction member connected to the suction fitting tube 8. The amount of air flowing in at the reference numeral 7 is detected in the range of the bench lily nozzle 6 by measuring the differential pressure at this nozzle. Further, the relative air humidity and the supply air temperature are measured by the humidity sensor 10 and the temperature sensor 11. Unless these measured values match the (set) target value, the flow rate of the supply air is reduced or increased, the air humidity is increased or decreased, and the temperature is also increased or decreased until the target value is reached. To be

The supplied air then passes through the channel nozzle 2 by means of which it passes from below through the sieve cloth of the strainer 3. At that time, the sieving material placed on the sieving cloth is also flowed through, the fine-grained components are entrained by the air flow, and are sucked downward through the sieving cloth in the opposite direction to be discharged from the suction fitting tube 8.

The logical combination of input values, measured values and control values with a single chip computer is shown in FIG.
The differential pressure, temperature, relative humidity, and nozzle rotation speed are detected as measured values. The sieving time, volume flow rate, temperature, nozzle rotation speed and nozzle rotation direction are input as input values. Aspirator speed, nozzle motor (nozzle drive motor) voltage, heating device heating voltage, compensator voltage for inflating the annular tube gasket, and operating time are output as control values by a single chip computer. .

Thus, an accurate and repeatable sieving analysis can be performed. Moreover, as a result of the configuration according to the invention, this device can be used as a component in an air jet type automatic sieving analysis device, the analysis process is controlled via a computer, and only a slight strainer exchange and proper weighing are possible. Only must be automated.

The invention is not limited to this embodiment, but can be variously modified within the framework of the disclosure.

All novel individual and combined features disclosed in the specification and / or drawings are considered essential to the invention.

[Brief description of drawings]

1 is a central cross-sectional view of an analytical sieving apparatus.

FIG. 2 is a partially enlarged view.

FIG. 3 is also an enlarged view of another portion.

FIG. 4 is a principle diagram of control of a single chip computer.

[Explanation of symbols]

 1 Casing 3 Strainer 4 Lid 5 Electric Motor 6 Supply Gas Detection Device 7 Gas Inlet 9 Annular Tube Gasket 10, 11 Sensor

Claims (16)

[Claims] 1. A method for analyzing a particle size in a fine / fine particle range by a gas jet type sieve, wherein a sieve material is loaded into a sieving cloth, and the groove shape is rotated below the sieving cloth. A gas jet is blown through a sieving cloth and a sieve by a nozzle, and fine-grained components are entrained by the gas flow,
Moreover, in the case where the gas flow is conveyed backwards through the sieving cloth toward the outlet under the sieving cloth, the gas flow is detected in quantity and is kept constant during the sieving process. The method is characterized by being kept at. 2. The temperature and / or humidity of the gas stream supplied is detected and controlled to a target value.
The method of claim 1. 3. Method according to claim 1, characterized in that the gas supplied is cleaned by a filtering device. 4. The sieving time is set and kept with an accuracy of seconds, and the sieving time is maintained.
The method according to one of 1. 5. A method according to claim 1, characterized in that the amount of particles in the exhaust gas stream is detected and from which debris standards for analysis are derived. 6. The method according to claim 1, wherein the data acquisition and the setpoint control are performed digitally by means of a single chip computer control system. 7. A method as claimed in claim 1, characterized in that the measurement results are recorded by a standard data interface and a printer or other storage device. 8. A method as claimed in claim 1, characterized in that the control of the machine and the recording of the data are performed by a computer via the same interface. 9. A method according to claim 1, comprising a sieving machine with an electrically driven rotating groove nozzle of the strainer, a gas supply and a gas outlet. In the device of (1), the gas inlet (7) is a supply gas amount detecting device (6), preferably a bench lily nozzle, a differential pressure measuring device provided in the nozzle, or a Prandtl tube, a hot wire flowmeter, An apparatus, comprising: a turbine, and a controller connected to an apparatus for generating a supply gas flow to maintain a constant gas amount. 10. A sensor (10, 11) for detecting humidity and temperature, and a supply gas heating device and a humidifying device connected to the sensor (10, 11) are provided in the supply gas flow. An apparatus according to claim 9. 11. Device according to claim 9 or 10, characterized in that a prefilter is mounted in the feed gas stream. 12. A method according to claim 9, characterized in that the analytical measuring time device is provided in the form of a single-chip computer control system and / or in the form of a timer with a second section. Equipment. 13. The device according to claim 9, wherein the device is a component of a gas jet automatic sieving analyzer.
2. The device according to one of 2. 14. The groove nozzle (2) is held exchangeably and can be driven by an electric motor (5) whose rotation speed and direction can be changed. The device according to claim 1. 15. The strainer (3) is designed to be replaceable and has an annular tube gasket (9) connected to the ventilation device and is sealable to the device casing (1). 15. The device according to claim 9, wherein 16. A lid (4) for closing the strainer (3).
Device according to one of claims 9 to 15, characterized in that it is configured as flat, concave or convex.