JPS6117309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and an apparatus for detecting the movement of a moving powder or granule by utilizing the electric charge charged on the moving powder or granule.

Pneumatic transport is one of the methods of transporting powder and granular materials, and is widely used in industry. Methods of determining the transportation status of powder and granular materials in transport pipes include optically detecting the presence of powder using a photoelectric tube attached to a part of the transport pipe, and detecting pressure changes within the transport pipe to detect the presence of powder and granular materials. Conventionally, a method of detecting presence has been employed. In the former optical detection method, in principle, only the presence or absence of powder or granules is detected, so it is not possible to distinguish between normal transportation and clogging. In addition, the latter pressure detection method has the disadvantage that it does not always accurately display the transportation status because the detection output changes not only due to changes in the amount of powder transported, but also due to changes in the amount of air blowing or suction, for example. be. In addition, since the pressure detector is installed between the blower or suction machine and the powder charging inlet, it is limited in space, and since the pressure detector is displayed using a normal air pressure gauge, it must be monitored at the installation location. It also has the disadvantage of not having to be used. Furthermore, as with the former optical detection method, normal transport and clogging due to failure are displayed as the same result. In short, the conventional detection method detects the presence or absence of powder in the transport pipe rather than detecting the transport status, and therefore, as mentioned above, it is possible to detect both clogging due to failure and normal transport. It detects the presence of particles and displays the same result.

The present invention eliminates the above-mentioned drawbacks of conventional detection methods and proposes a method that accurately detects not only the presence or absence of powder or granules, but also the transportation status of powder or granules.

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It is known that powder and granules transported by air are electrically charged due to contact friction between the powder and granules or contact friction between the powder and granules and the walls of a transport pipe. The phenomenon of electrification of powder particles is unfavorable from a safety standpoint, as it can cause a dust explosion, so anti-static measures are taken, such as grounding transport pipes.

The present invention is characterized in that it actively utilizes the electrical charges that the powder and granular material has during transportation, and accurately detects the movement status of the powder and granular material, that is, the transportation status.

According to one aspect of the present invention, charges on a moving particulate material are detected via a detection electrode, amplified in a high frequency band, detected, compared with a predetermined reference value, and displayed as an output. Detection outputs include lighting of indicator lights, driving of alarms,
It can take any desired form such as relay operation.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the principle of the present invention.
A part of the transport pipe 1 through which the charged powder moves is made of an insulating material 1a such as glass or synthetic resin, and a conductive detection electrode 2 is positioned opposite to the insulating material 1a. The detection electrode 2 is made of, for example, a thin steel plate, and its area is appropriately determined depending on the amount of powder moving within the transport pipe 1, the distance from the transport pipe 1, and the like. The electric charge of the powder moving in the transport pipe 1 is applied via the detection electrode 2 to a high input resistance circuit 3 having a wave height limiting effect, and is amplified by a high band amplifier 4, then rectified by a rectifier 5, and then passed to a comparator 6. The comparator is compared with a set value, and only when the input signal to the comparator exceeds the set value, its output is amplified by the power amplifier 7 and displayed as an output. High input resistance circuit 3 is the detection electrode 2
The voltage corresponding to the minute charge of the powder is extracted through the capacitor while limiting the peak value depending on the amount of movement of the powder, and its output is in the form of an impulse. Since the signal extracted by the high input resistance circuit 3 covers a wide frequency band, it is necessary to uniformly amplify the signal over the entire frequency band, and for this purpose, the high band amplifier 4 is provided. The output of the high band amplifier 4 is made into only one polarity component, either positive or negative, by the rectifier 5. The comparator 6 is given in advance a set value corresponding to the charged charge of the powder or granular material, that is, the amount of movement of the powder or granular material, as a reference value, and the rectifier 5
is compared with the output of This set value can be arbitrarily set in accordance with the amount of electric charge of the powder and granular material passing through the transport pipe 1 and the amount of the powder and granular material. The mode of output display may be arbitrary, such as lamp lighting or relay operation.

FIG. 2 is a concrete circuit diagram of the block diagram in FIG. 1.

The high input resistance circuit 3 having a wave height limiting effect is a pair of field effect transistors connected in opposite directions.
It consists of FET1 and FET2, and rectifier 5 consists of diode D. For each polarity of the output of the detection electrode 2, one of the pair of FETs acts as a high input resistance, and the other FET acts as a wave height limiter. Highband amplifier 4 and comparator 6 are of conventional type.
The reference value of the comparator 6 is set by a variable resistor 6a, and the sensitivity of the detection device itself is determined by the setting of this variable resistor 6a. Power amplifier 7 consists of an ordinary transistor TR. A relay Ry and a light emitting diode LED are used as display devices, and the collector of the transistor TR is connected to the relay
Ry is connected to the positive electrode of a power source E through a parallel connection of a light emitting diode LED and a series circuit of a resistor R, and the emitter of the transistor TR is grounded. The light emitting diode LED is conveniently used for adjusting the sensitivity of the detection device. The relay Ry is used to drive an external display device such as an alarm.

In the specific circuit configuration shown in FIG. 2, a pair of reversely connected FETs is illustrated as the high input resistance circuit 3 having a pulse height limiting effect, but the present invention is not limited to this, and other similar elements or circuits may be used. Of course, it can be used.

Furthermore, the present invention is not limited to pneumatic transport, but can also be used in conjunction with a spout that uses gravity to transport powder particles in a falling manner.

In short, the feature of the present invention is to detect the electrical charge possessed by the powder or granule in a non-contact manner by the movement of the powder or granule, and to detect the moving state of the powder or granule.
Reliable effects can be obtained when applied to powder particles of about 6 mm.

According to the present invention, it is possible to detect not only the presence or absence of powder or granules, but also the movement or stoppage of powder or granules, and by using the detection device of the present invention in conjunction with a level detector, normal transportation of powder or granules and clogging can be detected. You can definitely tell the difference. Compared to optical detection methods and pressure detection methods, this method has the advantage that it operates reliably without being affected by things such as deposits on transport pipes or changes in the output of the blower or suction device. Also,
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When considering the transport and transfer of different substances through the same transport system, by detecting the movement of the transported substances as in the present invention, it is possible to completely avoid contamination with transferred substances and shorten the switching time. This is expected to have significant effects, such as increasing the amount of transportation in the same transportation system and improving quality by ensuring that the remaining amount is disposed of reliably. As described above, the present invention, which directly controls the movement or flow of transported substances, will exhibit remarkable effects in controlling the pneumatic transport of powder and granular materials, which is expected to be realized in the near future.

[Brief explanation of the drawing]

FIG. 1 of the accompanying drawings is a block diagram showing the principle of the detection method and device according to the present invention, and FIG. 2 is a specific circuit diagram of the same detection device. DESCRIPTION OF SYMBOLS 1... Transport pipe, 1a... Insulating part, 2... Detection electrode, 3... High input resistance circuit, 4... High band amplifier, 5... Rectifier, 6... Comparator, 7... Power amplifier . 〓〓〓〓〓

Claims (1)

[Claims] 1. An electrically insulating portion is provided in at least a portion of the transport pipe through which the powder particles move while being triboelectrically charged;
A conductive detection electrode is arranged outside the transport pipe in close proximity to the electrically insulating part, and changes in the electrical charge accumulated in the electrically insulating part of the transport pipe due to the movement of the powder or granules are detected. A method of detecting movement of powder by electrically detecting it via the detection electrode. 2. A conductive detection electrode disposed close to an electrically insulating part provided in at least a portion of the transport pipe through which the powder particles move while being triboelectrically charged, and a high input resistor connected to the detection electrode. a high-bandwidth amplifier that amplifies the output of the resistive element, a rectifying element that extracts only the positive polarity component or negative polarity component of the output of the amplifier, and a comparator that compares the output of the rectifying element with a predetermined reference value. 1. A device for detecting movement of powder or granular material, comprising: and a display means operated by the output of the comparator. 3. The detection device according to claim 2, wherein the high input resistance element also has a wave height limiting effect.