JPS6023867B2 - Classifier using alternating electric field - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a classification device for classifying powder and granular raw materials using wind power or sieve silk, and more specifically, the present invention relates to a classification device for classifying powder and granular raw materials using wind power or sieve silk, and more specifically, the present invention relates to a classification device that classifies powder and granular materials by using wind power or sieve silk, and more specifically, the present invention relates to a classification device that classifies powder and granular raw materials by using wind power or sieve silk, and more specifically, by classifying powder and granular materials introduced into a housing and to be classified into an alternating electric field. This invention relates to a classification method and apparatus for classifying using guided wind or sieving silk.

In a classification device that uses wind power or a sieve screen, the granular material to be classified may aggregate due to van der Waals force, electrostatic attraction, adhering water, etc., and therefore be discharged as coarse powder. . In addition, in a classifier using wind power, when the concentration of powder raw material increases in the housing that forms the classification space of the classifier, the distribution density of the powder becomes extremely dense within the classification space.
Powder in a space with a dense distribution density settles out as a lump while containing characteristic powder, and is discharged as coarse powder. The main object of the present invention is to provide a classification method and apparatus using wind power or a sieve net with improved classification efficiency.

In the present invention, an inner cylinder 3 is provided in a vertically extending cylindrical housing coaxially with the housing 1, the upper part of the inner cylinder 3 is tapered upward, and the lower part of the inner cylinder 3 is tapered downward. Above the upper part of the inner cylinder 3, the lower end of the short 2 for introducing powder and granules faces, and below the lower part of the inner cylinder 3 is an inlet port for introducing gas from the side of the housing. 4 is provided, and a coarse powder discharge port 6 is provided below the inlet port 4 of the housing 1, and the inner cylinder 3 has a plurality of conductive divided portions 14 to 18 arranged vertically through an electrical insulator 20. An AC power source 21 having three or more phases whose phase order is sequentially determined from bottom to top is connected to each divided portion 14 to 18,
This is a classification device using an alternating electric field, characterized in that a traveling wave alternating electric field is formed sequentially from the bottom to the top in the dark space between the inner cylinder 3 and the housing.

FIG. 1 is an overall system diagram of an embodiment of the present invention.

A chute 2 is provided at the top of the vertically extending cylindrical housing 1, into which powdered raw material to be classified is fed.
As a result, the powder raw material is introduced from above into the housing. Inside the housing, an inner cylinder 3 is provided to promote the dispersion of the powder and granules introduced from the chute 2. This inner cylinder 3 extends vertically coaxially with the housing 1, and has tapered conical ends at both upper and lower ends. is formed. An air inlet 4 is provided at the bottom of the housing 1, from which air is introduced as shown by the arrow. The coarse powder discharged from the coarse powder discharge port 6 provided at the bottom of the ujingu is guided to the crusher 7, crushed, and guided to the chute 2 again. Housing 1
The powder classified inside is led to a cyclone 9 through a chute 8. This cyclone 9 collects fine powder. A flap damper 11 is provided at the bottom of the cyclone 9. The inner cylinder 3 within the conductive housing 1 is vertically divided into six conductive divided parts 14 to 19.

An electrical insulator 20 is interposed between the divided portions 14-19. Relatively upper divided portions 14, 15, 16
are electrically connected to relatively lower divided portions 17, 18, and 19, respectively, and those commonly connected divided portions 16, 19: 15, 18; 14, 17 are Each phase u, v of the power supply (three phases in this example) 21
, w, respectively. The alternating electric field thus formed within the housing 1 in the space between it and the inner cylinder 3 becomes a three-phase traveling wave alternating electric field whose phase order is determined from bottom to top. As a result, the powder introduced from the chute 2 is subjected to an electrostatic force that depends on the electric field strength in the phase direction, that is, from the bottom to the top. Therefore, the final velocity of natural fall of the powder changes depending on the strength of the electric field, and it is thereby possible to control the classified particle size. The housing and the inner tube 3 are supported within the housing by an electrically insulating support member 12.

The support members 12 are arranged at intervals in the circumferential direction so as not to impede the rise of air from the air inlet 4 and the flow of powder and granular material. The frequency of the power supply 21 is, for example, 50~
60Hz, and the electric field strength is, for example, the effective value starvation.
/cm. The raw material introduced from the chute 2 undergoes dielectric polarization due to the alternating electric field.

The time required for each polarization is very short, for example, 1/100 or less, and when the frequency of the AC power source 13 is, for example, 50 to 60Hz as described above, the time required for polarization can be ignored, and the powder The raw material is repeatedly polarized at the same frequency and phase as the AC power source. Therefore, due to the electrostatic force generated by the alternating electric field and the polarized charges, both ends of the granular material are attracted to the electrodes closer to each other along the lines of electric force. Furthermore, powder and granules are generally not perfect spheres, but have various shapes other than spheres, and are therefore subject to rotational moment depending on the direction of the alternating electric field and the distribution of polarized charges. These electrostatic forces cause the aggregated powder particles to split, and after the split, they are charged with opposite signs. The charged powder and granules are vibrated by the alternating electric field, including the case where the powder and granules introduced from the chute 2 are charged in advance.

The vibration of this granular material varies depending on the mass, amount of charge, and shape of the granular material, and vibrations occur with an amplitude and phase unique to each granular material, and the frequency of the vibration of this granular material is The frequency is the same as the frequency of the AC power supply 21. Furthermore, air flows upward from the air inlet 4.

As a result, the powder and granules introduced into the housing 1 from the chute 2 undergo complicated movements. Therefore, the powder particles that have been separated within the housing 1 are individually separated. Moreover, the distribution density of the powder and granules becomes uniform within the housing 1, and the powder and granules are prevented from falling in the form of lumps. Therefore, the fine powder is reliably led from the duct to the cyclone 9 and collected in the bottle, and only the coarse powder is led out from the coarse powder outlet 6 to the crusher 7. Conventionally, the coarse powder from the coarse powder outlet 6 contains agglomerated powder, and therefore
The amount of circulating powder and granules supplied to the machine increases, and work efficiency decreases.

In addition, since the pulverizer 7 contains coarse powder as well as coarse powder, the impact force between the lees powder and the grinding media in the pulverizer 7 is weakened by the coarse powder, reducing the pulverization efficiency. Ta. According to the present invention, since the coarse powder from the target powder outlet 6 does not contain fine powder, the pulverizing capacity of the entire system including the pulverizer 7 is improved, and the reduction in pulverizing efficiency in the pulverizer 7 is prevented. Prevented. As described above, according to the present invention, since an alternating electric field is formed in the classifier, agglomerated particles of the powder to be classified are dispersed.

Further, the powder and granules introduced into the classifier are disturbed by the alternating electric field, and the distribution density of the powder and granules becomes uniform. Therefore, classification efficiency is improved. In addition, since an AC power source is used, unipolar charges are prevented from increasing in the powder raw material as a whole, and therefore, problems due to static electricity do not occur when handling the powder in equipment downstream of the classifier. Further, the power consumption for forming the alternating electric field is extremely low. In addition, a traveling wave alternating electric field is formed in which three or more phases of alternating current power are sequentially determined from bottom to top, and an upward electrostatic force acts on the powder, so that classification can be carried out efficiently. This electric field is formed in the space between the housing and the inner cylinder 3, and in this space there are divided parts 14 to 1.
8 and the electrical insulator do not protrude, so that the powder and granules can be smoothly vibrated and classified, and the powder and granules do not stick together.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention. 1...Housing, 2...Chute, 3...Inner cylinder, 21
...3-phase AC power supply. Figure 1

Claims (1)

[Claims] 1 An inner cylinder 3 is provided coaxially with the housing 1 in a cylindrical housing 1 extending vertically, the upper part of the inner cylinder 3 is tapered upward, and the lower part of the inner cylinder 3 is tapered downward. Above the upper part of this inner cylinder 3, the lower end of the chute 2 for introducing powder and granules faces, and below the lower part of the inner cylinder 3,
An inlet 4 for introducing gas from the side of the housing is provided, and a coarse powder outlet 6 is provided below the inlet 4 of the housing 1.
is provided, and the inner cylinder 3 has a plurality of electrically conductive divided portions 14.
- 18 are arranged vertically with an electrical insulator 20 interposed between them, and each divided part 14 - 18 is connected to an AC power supply 21 having three or more phases whose phase order is determined from bottom to top. A classification device using an alternating electric field, characterized in that a traveling wave alternating electric field is formed in the space between the inner cylinder 3 and the inner cylinder 3.