JPS6118456A - Electrostatic separating apparatus - Google Patents

Abstract

PURPOSE:To obtain the stabilized high separation performance in a separating apparatus in which relative dielectric constant variance and air resistance variance of a discharge period are utilized by making a power receiving electrode of the supporting plate of a conveyer belt to perform discharge on the plane part of the belt and electrifying raw material. CONSTITUTION:Raw material of tobacco conveyed on a conveyor belt 12a is electrified when it is passed between the electrodes which are constituted of the discharge electrodes 20a-20c and a platelike power receiving electrode 22 positioned in the back surface side of belt plus a metallic pulley 14 actuating as the power receiving electrode. Since the conveyer belt 12a is made of polyester- and nylon-base insulating material, the electrified state is stably kept till the discharge end of the belt and the raw material is discharged to the same direction as the proceeding direction. Coulomb force is supplied to the discharged laminas and medium bones within the electrical field formed between the discharge electrode 20c and the conveyor head roller 14 and these are separated by the magnitude of quantity of electrical charge per unit area and the air resistance in the discharge period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic separation device that uses static electricity to separate desired materials from undesired materials. This invention relates to an electrostatic separation device that uses an electrostatic method to separate the remaining leaf veins (hereinafter referred to as midribs) from which the lamina has been peeled off.

Generally, in the cigarette manufacturing process, the raw tobacco leaves are first unraveled one by one, then softened with water and steam in a humidifier, and then separated into lamina and backbone in a deboning machine. It is separated into lamina and midbone.

Conventionally, this type of separator mainly used an air flow method, but this method not only has high running costs, but also uses the difference in air resistance coefficient and area type to perform separation. , those with little difference in these characteristic values,
For example, there was a problem that it was difficult to separate the lamina from the midbone in which the lamina was not completely peeled off and the lamina remained partially.

Therefore, attention is being focused on a separation method using static electricity, which is advantageous in terms of running cost and utilizes the difference in dielectric constant. FIG. 1 shows an example of a conventionally known electrostatic separator. In the figure, metal pulley l.

2 are provided at upper and lower positions, and a conductive endless belt 4 covered with an insulating coating 3 is passed around the belt, and the metal pulley 1 is driven in the direction of arrow M to cause the belt to move. The material to be separated is supplied by a conveyor 5 and charged in a corona electric field by a corona discharge electrode 6.

As described above, the material charged by the corona discharge electrode on the surface of the pulley 1 receives an electrostatic force between it and the pulley 1, and an adsorption force is exerted on the boot I71, but this adsorption force depends on the magnitude of the charge. The materials are separated by utilizing the fact that the discharge trajectory of the material discharged from the belt 4 differs depending on the material.

However, in the conventional device described above, the material is charged at the pulley immediately before being discharged, so if the material bounces on the belt 4 before reaching the pulley, some of the material may be on the belt 4. Some substances are released without being in a sufficiently stable state. For this reason, it is no longer ejected with a uniform force, and even if there is a difference in charge, stable material separation cannot be performed. In particular, the above-mentioned problem becomes noticeable in belts that move at high speeds.

The present invention has been made to solve the problems of the conventional devices described above, and its purpose is to provide an electrostatic separation device that can perform stable separation at high speed.

The device according to the present invention has been made to achieve the object,
A spreading means for spreading the raw material to be separated in the width direction and the traveling direction, a belt conveyor for receiving and transporting the raw material spread by the spreading means, and a belt conveyor for receiving and transporting the raw material spread by the spreading means, and the raw material being transferred by the conveyor is charged and discharged from the conveyor. and a discharge field generating means for applying an electric field to the charged raw material,
In the belt conveyor, the conveyor belt is made of an insulating material, and the hent roller at the raw material discharge end is made of metal, and the discharge field generating means has a receiving plate provided on the back surface of the flat part of the conveyor belt and the hent roller as receiving electrodes, It is characterized by comprising a discharge electrode to which a high voltage is applied between these electrodes.

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

Figure 2 shows a mixed raw material of deboned tobacco mesophyll (hereinafter referred to as lamina) and leaf veins (hereinafter referred to as backbone, which includes the backbone to which the lamina is attached), which is an embodiment of the present invention. The machine that separates the lamina and mid-bone parts is shown. In the figure, reference numeral 10 denotes a raw material spreading device consisting of a vibrating conveyor, which spreads the raw material thinly in the width direction and the traveling direction and supplies it onto a conveyor belt 12a of a belt conveyor 12. The conveyor belt 12 is passed between a pair of metal rollers 14 and 16, and is moved in the direction of the arrow by an electric motor 18 connected to the rollers 16.The conveyor belt 12 may be made of an insulating material in principle, but is preferably made of polyester. , nylon type is better.

The speed of the conveyor belt 12 is high from 100 to 300 m/min, so that the raw material is further stretched thinly on the conveyor belt 12 in the direction of movement.

20a, 20b, and 20c are corona discharge electrodes that may be wire electrodes or needle electrodes, and the discharge electrode 20a is a flat receiving electrode placed on the back side of the flat part of the conveyor bell l-128 near the discharge end of the conveyor 12. The raw material is charged on the flat surface of the conveyor bell 12a by corona discharge due to the high voltage applied between the conveyor bell 12a and the conveyor bell 12a. The discharge electrode 20b performs corona discharge by applying a high voltage between the plate-shaped receiving electrode 22 extending to just before the discharge end of the conveyor 12 and the metal boob IJ14 serving as the receiving electrode, and discharges the raw material immediately before its discharge. It becomes more electrically charged. Further, the discharge electrode 20c is opposed to the head roller 14 of the conveyor at an angle of about 45 degrees in the discharge direction,
An electric field is applied to the raw material immediately after it is released.

As described above, the raw material on the conveyor belt 12a is charged when passing between the electrodes constituted by the discharge electrodes 20a to 20C and the receiving electrodes 22 and 14. This charged state is maintained because the conveyor belt 12a is made of an insulating material. The plate-shaped receiving electrode 22 also serves as a receiving plate for the conveyor belt 12a, and is grounded together with the receiving plate 26 in a portion where corona discharge is not performed.

In addition, 30 is a high voltage source that supplies discharge voltage to the discharge WAs 20a to 20c, 32 is a brush roller that scrapes off the raw material adhering to the belt 12a, and 34 is a belt 12a.
36a is a lamina storage box, 3
6b is a lamina/backbone mixture storage box, 36c is a backbone storage box, and 38 is an adjustable partition wall provided between the storage boxes 36a to 36c.

As a result of the above, the charged lamina and back bone are transferred to the conveyor belt)1
2a is carried to the discharge end, where it is discharged almost in the same direction as the conveyor bell 12a. The ejected lamina and backbone are subjected to Coulomb force within the electric field formed between the discharge electrode 20c and the conveyor hentroller 14, and the lamina with a large amount of charge per unit area weight is attracted to the hentroller 14 side. Hentrolla 1
The lamina that falls near the conveyor belt 12a or adheres to the conveyor belt 12a is scraped off by the brush roller 32 and collected in the lamina storage box 36a.

On the other hand, the backbones with a small amount of electric charge per unit area weight have a discharge force greater than the force due to the electric field, so they fall far from the conveyor 12 in the traveling direction and are collected in the backbone storage box 36c. Most of the lamina and midbone are separated as described above, but there are some lamina and midbone that fall between the two,
These are collected in the lamina/middle bone storage box 36b. Then, separation is performed again using a similar separator, and the separated lamina and backbone are combined with the contents of the storage boxes 36a and 36C.

In the above embodiment, the conveyor 12 is horizontal, but it may be inclined within the range of θ to 30°. In this case, it is advisable to provide a horizontal bar with a height of 5 fi or less, preferably 2 to 3 cranes or less, on the conveyor bell I-12a to prevent the material from slipping.

Further, the polarity of the discharge electrodes 20a to 20c may be either (■) or (e), but it is preferable to set it to (circle) in order to increase the discharge current.

Incidentally, the speed of the conveyor belt 12a influences the amount of air resistance experienced when the raw material is discharged, and the faster the belt speed is, the greater the air resistance is experienced. On the other hand, the higher the belt speed, the shorter the time it takes to pass through the separation electric field, and the smaller the impulse received from the electric field. Therefore, there will be a belt speed at which the separation efficiency is maximum when the voltage is held constant. However, this varies depending on the type of raw material, and for separation of back bone and lamina, the optimum speed is 200 m/min.

The higher the voltage applied to the discharge electrodes 20a to 20C, the greater the amount of charge and the strength of the separation electric field, and the greater the force acting on the raw material. The relationship between voltage and separation efficiency when the belt speed is 200 m/min is that the higher the voltage, the higher the separation efficiency is. be.

The relationship between raw material flow rate and separation efficiency is that the lower the flow rate, that is, the lower the amount of raw material per unit area on the belt, the higher the separation efficiency, but because the belt speed is high, the throughput is over 1200 kg/min, which is conventional It's much larger than that.

As explained above, the present invention utilizes the electrostatic force received in an electric field in proportion to the amount of charge applied to the raw material, and the air resistance that the raw material receives when released into the air from a conveyor belt. However, in the present invention, in particular, the receiving plate of the conveyor belt is used as the receiving electrode to generate electric discharge on the flat surface of the belt to charge the raw material, so that the raw material remains stable until the discharge end of the conveyor belt. The separation performance is significantly improved without causing any variation in the discharge direction of the raw materials.

[Brief explanation of drawings]

FIG. 1 is a simplified diagram showing an example of a conventional electrostatic separator, and FIG. 2 is a side view showing an embodiment of the present invention. IO... Raw material spreading device, 12... Belt conveyor, 12a... Conveyor belt, 14
...Hentrolla, 20a-20C...
- Discharge electrode, 22... Receiving plate.・Patent applicant Japan Monopoly Corporation Director of Research and Development, Japan Monopoly Corporation

Claims (1)

[Claims] A spreading means for spreading the raw material to be separated in the width direction and the traveling direction, a belt conveyor for receiving and transporting the raw material spread by the spreading means, and a belt conveyor for receiving and transporting the raw material spread by the spreading means, and the raw material being transferred by the conveyor is charged and discharged from the conveyor. and a discharge field generating means for applying an electric field to the charged raw material,
In the belt conveyor, the conveyor belt is made of an insulating material, and the head roller at the raw material discharge end is made of metal. An electrostatic separator comprising: and a discharge electrode between which a high voltage is applied.