JPH0442066A - Potential detection of electrified particle and electrification control device - Google Patents

Abstract

PURPOSE:To enable electrification status of a particle which flows within a container to be directly detected by forming an air curtain in front of a detection head of a potential sensor. CONSTITUTION:A potential detection unit 2 is mounted to a drying bath 1 and the unit 2 detects electrification potential of a particle through a window hole 3 which is provided at a peripheral wall of the drying bath 1, where the unit 2 stores a potential sensor 6 into a metal case 4 and forms an air curtain formation part 10 by performing polymerization-adhesion of a middle plate 8 and a front outer plate 9 at a front wall 7, air which is jetted out of an air jet-out hold 12 flows vertically along cut-out window 14 of the middle plate 8 for forming an air curtain at a front side of a detection hole 11, and it is jetted into the drying bath 1 through the window hole 3 from an air jet-out window 13. Then, the potential sensor 6 enables a detection head 23 to face an inside of the detection hole 11 and the particle does not directly contact the detection head 23 even if the particle is allowed to flow within the drying bath 1 due to hot wind, thus enabling the sensor 6 to detect electrification potential of the particle without contacting it.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a belt for detecting the potential of charged powder in a powder processing device that fluidizes powder with gas such as air, such as a fluidized fluid dryer; The present invention relates to a charge control device that controls the amount of charge according to a detected potential.

[Conventional technology]

It is well known that most particulate matter, with the exception of some materials such as stones and earth, becomes electrically charged in a suspended state, causing a so-called "dust explosion." This risk is particularly high in fluidized fluidized dryers that heat and dry while drying. Fluidized fluidized dryers have tens of times higher drying efficiency than shelf-type hot air dryers that dry powder and granules in a static state, so they are widely used in the pharmaceutical and food processing fields, etc., which dry large quantities of powder and granules. has been done. FIG. 1O shows an example of a conventional fluidized fluidized dryer, 50 is a powder pump, 51 is a granulator, 52 is a drying tank with a built-in filter 53, 54 is a hot air supply source, 55 is a product recovery container,
56 is a product hopper, and 57 and 5B are blowers. Powder 59 is put into the drying tank 52 from the granulator 51 . Hot air is blown into the drying tank 52 from a hot air supply source 54 through a bottom made of a perforated plate or a wire mesh, and is exhausted by a blower 57 through a filter 53, so that the powder and granules 59 are blown inside the drying tank 52. After floating and flowing and being dried in a short time, the product is collected in the product collection container 55. In such a fluidized fluid dryer, the powder and granules 59 are violently fluidized by hot air especially in the drying tank 52, and the powder and granules repeatedly come into contact with each other and with the drying tank wall surface, friction, exfoliation, separation, etc. In reality, the generation of static electricity was much more significant than in the previous example, and there were actual cases where the powder 59 was charged to a high potential and ignited, causing an explosion. However, there is a demand for further refinement of powder and granular materials, and although the risk of explosion due to charged ignition tends to increase with miniaturization, it is not possible to detect static electricity in the violently flowing powder and granular materials as described above. However, due to the harmful effects of powder and granules getting into the detection unit, hot air, etc., and the adverse environment, there is no way to sample the powder and measure the potential manually with a Faraday gauge, etc., and it is not possible to measure the potential automatically in real time. Until now, there was nothing that could be detected properly. Therefore, when drying materials containing flammable organic solvents, etc. in a fluidized fluidized dryer, the concentration of flammable gas is detected and monitored using a flammable gas concentration meter installed in the exhaust section. If the concentration exceeds - 2 ;), is it possible to prevent ignition and explosion by changing the operating conditions or introducing diluted air to reduce the gas concentration? It wasn't.

[Problem to be solved by the invention]

An object of the present invention is to directly, automatically, and accurately measure the electrostatic charge state of the flowing powder or granules in a container where the powder or granules are fluidized by gas, such as a drying tank of a fluidized fluid dryer. An object of the present invention is to provide a potential detection device capable of detecting a potential and a charge control device capable of automatic control to prevent explosion.

[Means to solve the problem]

In the potential detection device according to the present invention, a potential sensor for detecting the charged potential of the flowing powder is attached to a container in which the powder is made to flow by gas, and a detection part of the potential sensor is connected to a window provided in the container. Opposite the hole, around this window hole,
It is provided with an air curtain forming section that injects air to form an air curtain. Further, the charge control i11 device according to the present invention includes, in addition to the above-described configuration, a control device that controls equipment connected to the container according to the output of the potential sensor to adjust the amount of charge on the powder or granular material. It is something.

[For production]

Since an air curtain is formed in front of the detection part of the potential sensor, the powder, granules and gas flowing in the container do not touch the detection part, and they are not blown away from the potential sensor. The potential sensor detects the charged potential of the powder or granular material without any problem through the window hole of the container. By automatically controlling the equipment connected to the container according to the output of the potential sensor, it is possible to adjust the amount of charge on the powder and prevent explosions.

【Example】

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. Figure 2 shows an outline of an example in which a potential detection unit 2 is attached to the outer side of the peripheral wall of a drying tank 1 of a fluidized fluidized dryer, and the potential detection unit 2 detects the charged potential of powder particles flowing in the drying tank 1. shows. FIG. 1 is an enlarged cross-sectional view of a part of the potential detection unit 2 and the drying tank.A window hole 3 for detection is provided in the peripheral wall of the drying tank 1. The charged potential of the powder in the drying tank 1 is detected without contact. As shown in FIGS. 1 and 3 to 6, the potential detection unit 2 includes a metal case 4 whose rear opening is closed with a rear plate 5, a potential sensor 6 mounted inside the case 4, and a potential sensor 6 mounted inside the case 4. A middle plate 8 and a front outer plate 9 are superimposed and adhered to the front wall plate 7 of the case 4 to form the following air curtain forming portion IO. That is, the front wall plate 7 of the case 4 is provided with a circular detection hole 11 and an air injection hole 12 directly above it as shown in FIG. 7, and the front outer plate 9 is provided with a circular detection hole 11 as shown in FIG. A circular air blowing window 13 is provided in the middle plate 8, and a cutout window 14 is further provided in the middle plate 8 as shown in FIG. The air outlet window 13 is larger than the detection hole 11 and is concentric with it, but is not large enough to reach the air injection hole 12. On the other hand, the notch window 14 is larger than the detection hole 11 and is concentric with it. It has a size that includes the injection hole 12, and its lower edge 14a is a semicircle that coincides with the lower half of the periphery of the air blowing window 13, and its upper periphery 14b is in the shape of a rectangular arch. Screw holes 15 are provided in the front wall plate 7, middle plate 8, and front outer plate 9 of the case 4.
are provided at each of the four corners, and the middle plate 8 and front wall plate 9 are screwed to the front wall plate 7 through these screw holes 15. On the other hand, an air supply pipe 16 is arranged inside the case 4. The base end of this air supply pipe 16 is connected to the case 4.
It is connected to an air supply joint 17 fixed to the bottom surface of the cylinder, and its tip is connected to the air injection hole 12. Connect a hose to the air supply joint 17 and install the air supply vibrator 16.
When air is sent from the outside to , the air is injected from the air injection holes 12 . In this case, since the air injection holes 12 are located at a higher position than the air outlet windows 13 of the front outer panel 9,
The air ejected from the air injection holes 12 passes through the cutout window 14 of the middle plate 8 and hits the inner surface of the front outer plate 9.
4 and forms an air curtain in front of the detection hole 11, and the air flows from the air blowing window 13 through the hole 19 of the gasket 18 and the detection window 3 of the drying tank 1 into the drying tank 1.
erupts within. The potential sensor 6 is a conventionally known one that has a vibrator, a detection L plate, a field effect transistor, a resistor, etc. built into the sensor case 2o. A small circular detection head (detection part) 23 is fixed by a mounting bracket 22 with a thin gap 21 formed between the inner side and the sensor case 20 and protrudes from the front surface of the sensor case 20.
is faced into the detection hole 11 with an annular gap 24. The mounting bracket 22 is screwed through screw holes 25 provided in the front outer plate 9, the middle plate 8, and the front wall plate 7. A cable 26 from the potential sensor 6 is pulled out through a cable outlet 27 fixed to the bottom of the case 4. A small hole (not shown) is provided in the middle of the air supply vibrator 16 to inject a part of the air into the internal space of the case 4, and the air ejected into this internal space is detected by the detection head 23. It is ejected forward from the annular gap 24 between the hole 11 and the hole 11 . Since the present potential detection device has the above-described structure, air is injected forward from the annular gap 24 between the detection head 23 and the detection hole 11, and air injected from the air injection hole 12 is directed into the detection hole. An air curtain is formed on the front side of the drying tank 11, and this air is ejected from the air blowing window 13 into the drying tank 1. The body will not flow out of the window hole 3 and directly touch the detection head 23 or enter the case 4, and the body will not flow out of the window hole 3 and directly touch the detection head 23 or enter the case 4.
3, and the potential sensor 6 detects the charged potential of the powder without contact and without any trouble. Therefore, the output of this potential sensor 6 is processed by a control device using a microcomputer or the like, and when the charged potential of the powder or granules increases beyond a predetermined level, for example, the air volume of the exhaust blower 29 of the drying tank 1 or the hot air supply route is determined. Humidification by humidifier 30/W
If the amount etc. are automatically controlled by this control device 28, the amount of charge of the powder or granules can be adjusted to accurately prevent ignition and explosion due to an increase in the potential. Although one example has been shown above in which the drying tank 1 is used to dry powder and granular material with hot air, the present invention is not limited to this and can be used in various powder and granular material processing apparatuses. Further, although the potential sensor 6 and the air curtain forming section 10 are made into a unit independent of the drying tank 1, they may be directly incorporated into the drying tank 1.

【Effect of the invention】

According to the present invention, in a container in which powder or granules are fluidized by gas, such as a drying tank of a fluidized fluid dryer, it is possible to directly, automatically, and accurately check the electrostatic charge state of the flowing powder or granules. Can be detected. Further, by automatically controlling the equipment connected to the container according to the output of the potential sensor, it is possible to adjust the amount of charge on the powder and granules to prevent their explosion.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts of an embodiment in which the potential detection device and charge control device according to the present invention are used in a drying tank, Fig. 2 is an overall external view of the device in use, and Figs. 3 to 6 are its main parts. A front view, a side view, a top view, and a bottom view of the potential detection unit, and FIGS. 7 to 9 are a front view of the case, a front view of the middle plate, and a front view of the front outer plate of the potential detection unit. Also, the first
Figure 0 is a schematic diagram of a conventional fluidized fluidized dryer. 1...Drying tank, 3...Window hole, 6...
...Potential sensor, 10...Air curtain forming section, 23...Detection head, 28...Control'+B device, 29...Port...Exhaust blower, 3o・・・
····humidifier.

Claims (1)

[Claims] 1. A potential sensor for detecting the charged potential of the flowing powder or granule is attached to a container in which the powder or granule is made to flow by gas,
A charged powder characterized in that the detection part of the potential sensor is arranged to face a window hole provided in the container, and an air curtain forming part is provided around the window hole to inject air to form an air curtain. Particle potential detection device. 2. The charged powder or granular material according to claim 1, further comprising a control device that controls a device connected to the container according to the output of the potential sensor to adjust the amount of charge on the powder or granular material. Charge control device.