KR100235290B1 - Fine dust separation method using electromagnetic plate and its apparatus - Google Patents

Abstract

The present invention relates to a method and apparatus for separating an active ingredient from a fine powder in which two or more different material components are mixed. The present invention relates to refining various minerals, particularly unburned carbon and ash in coal ash, which is a waste generated from a coal-fired power plant. An object of the present invention is to provide a method for charging fine powder by using static electricity, which can be used to remove ash from ash, or to remove ash from coal.

The method and apparatus for separating fine particles using the airflow impingement electrostatic separation type of the present invention are characterized in that the fine particles introduced naturally by compressed air expansion are subjected to particles and particle collisions by the strong turbulence in the nozzle (venturi injector), After the first charge due to the collision of, it enters the rotator in the aerosol state in the tangential direction, and the secondary charge is caused by the collision with the rotating body or the collision of particles with the particles by the high-speed rotating vortex, which is uniformly applied to the vertical electric field separator. It is characterized in that the fine particles moved in the direction of the (+) (-) electrode according to the charge polarity is separated into a rotatable central separator.

Description

Separation method and apparatus of fine powder using airflow impact electrostatic separation type

The present invention relates to a method and apparatus for separating fine powder using a triboelectric electrostatic separation type, and more particularly, to a method and apparatus for separating an active ingredient from fine powder in which two or more different material components are mixed. Fine powders using the electrostatic properties of objects that can be used to separate or remove ash from coal and ash from coal ash, especially waste from coal-fired power plants. The present invention relates to a method for charging and disconnecting and an apparatus used therefor.

The electrostatic separation method is used to separate the fine powder mixture by charging the material using the unique electrical properties of each material, such as dielectric, electrical conductivity and work function. It is a very effective separation method.

Therefore, it is very important to selectively charge the materials to be separated. There are several ways to charge the material as follows.

(1) charging by conductive induction

(2) charging by ion or electron bombardment

(3) charging by contact or friction

In the electrostatic induction method, when the conductive particles enter the electric field, they become polarized and then contact the grounded conductors, causing the movement of charges to be charged and repulsed with the same sign as the grounded conductors, while the insulator has no movement of charges. Since it can be separated by attaching with a grounded conductor, it is applied to separating conductive and non-conductive materials.

In the corona discharge method, when a high voltage is applied to the thin metal wire electrode, a corona discharge is generated to ionize the surrounding gas, and the ionized gas collides with the material to charge the material. It can be applied when trying to separate conductive and nonconductive materials because they have the same sign of charge.The charged conductive material releases the charge when it comes in contact with the grounded roller and becomes electrically neutral. The material is detachable because it attaches to a grounded conductor without the transfer of charge with the roller.

Contact or triboelectrification has attracted attention as the most useful method for separating electroconductive fine powder mixtures by electrostatic methods. All materials are made up of chemical bonds, which are due to the energy structure of the electrons. In other words, some electrons have strong bonding force, and some electrons have weak bonding force, which makes them easy to move, and some electrons can be moved by simply applying activation energy.

When two different materials contact or rub against each other, the electrons move to another material until the energy levels are the same at the contact interface of the two materials. Therefore, a material having a high affinity for electrons loses electrons and has a negative charge, while a material having a low affinity for electrons acquires an electron and takes a positive charge. The measure of affinity of each material for electrons is called a work function, which is the energy required to move an electron to infinity on the surface of the material, depending on the chemical composition of the material surface, as shown in Table 1 below. Each substance has a unique value.

If two materials with different work functions come into contact with each other, the electrons are exchanged until the work function difference disappears, so that materials with low work functions have positive charges and those with high materials have negative charges.

Therefore, the method of contact and frictional charging can be classified into two main methods: the method of contacting and rubbing the two materials to be separated and charging each other and the third material, that is, the material having the median work function of the two materials. And a method of rubbing and charging.

In FIG. 1 and FIG. 2, U.S. Patent No. 4,627,579 discloses a sinusoidal use path (FIG. 1; 12) of a sample introduced through a powder injector (FIG. 2, 44, 46) using air or another gas. The particles are charged by the collision of particles and particles in the path 12 and the collision of particles and walls in the path 12 and separated from the rotating drum electrode part (FIG. 1, 70, 72) installed near the bottom of the path. And devices are described. According to this method, as a method of charging particles, a powder is introduced at high speed with air to increase the collision probability of particles (FIG. 1) and a screw feeder inside the rotating blade (FIG. 3; 90) shaft. 2) Powder feed screws 40 and 42 are installed so that the powder comes out into the inlet 86 by centrifugal force of the rotating body and the particles collide with the blade 90 rotating at high speed to charge the particles (FIG. 2). )to be. The charged fine powder is separated by drum electrodes 70 and 72 provided at the bottom of the charging medium.

The problem with this method is that as the particles move through the path of sinusoidal phenomena (Figure 1; 12), the charging performance of the particles may be excellent, but because of the small width of the path, there will be a problem in introducing the powder in large quantities. Judging.

On the other hand, U.S. Patent No. 4,839,032 and Power August (1994), p37-40, charge the particles by fluidizing the particles with a high speed belt (20 m / sec) in an electric field with a distance between the positive and negative electrodes within 1 cm. It describes a method and a device for separating. The powder introduced through the fine powder inlet of the separator is fluidized by a mesh conveyor belt having holes which are moved at high speed in the opposite direction by the rollers, and the fine powder is charged by the contact between the particles and the particles and the belt. The charged particles are taken out from the separator through the fine powder outlet by a belt that is moved to the positive electrode and the negative electrode and then bisected and moved in opposite directions.

The problem of these inventions is that the mesh conveyor belt of polymer material is tensioned at a narrow distance of about 1cm between the (+) electrode and the (-) electrode. The belt life is short and the belt is easily broken, so it is difficult to operate continuously for a long time such as frequent belt replacement.

Accordingly, the present invention has been made to solve the above-mentioned problems, the object is to maximize the charging efficiency of the powder, increase the amount of raw material (powder) injected without a decrease in charging efficiency, yield control The present invention provides a method and apparatus for separating fine powder using a triboelectric electrostatic separation type to facilitate the separation.

In order to achieve the above object, it has the following features.

1. System with separate charging part and separating part

Instead of charging the powder, an electrode having electrostatic attraction according to the polarity of the charged powder passing through the charged part and the charged part made up of the fine powder inlet, the air inlet, the mixed powder nozzle part mixing the same, and the rotating frictional charged material It consists of an electrostatic separator instead of moving in a direction.

The first charged fine powder mixed and mixed is highly efficient by the second charging which is charged once again in the rotating charging body.

2. Increasing the efficiency of contact with fine powder and frictional charging by vigorous stirring by high speed air flow in the venturi injector. As compressed air flows into the compressed air inlet and expands, the suction force is applied to the fine powder inlet. Air and fine powder are introduced and vigorous stirring by high velocity airflow in the converging part and throat increases the number of collisions between particles and particles and the charge amount due to collisions between particles and walls.

The charged fine powder is maintained in the aerosol state by compressed air, and the separation efficiency is high due to the function of preventing the agglomeration of the fine particles.

In addition, the air inlet, the fine powder inlet, and the mixed powder outlet were widened in the transverse direction as shown in FIG. 7 so that the volume of the processing volume was easily increased without using a plurality of circular powder injectors. Therefore, the number of the mixed powder nozzle parts (injector) can be reduced when the processing capacity is increased, and the fine powder is easily introduced and the fine powder is introduced in the entire horizontal direction so that the fine powder can be uniformly dispersed and charged. In addition, in order to improve the charging performance due to the vigorous stirring of the powder, the nozzle part was made into a plate, a circle, and a square to make the vigorous stirring of the particles.

3. Addition of contact frictional charging function in the rotating charging body

The fine powder charged by the mixed powder nozzle unit (venturi injector) is charged collision with the rotating blades of the rotary frictional charged and the turbulence by the high-speed rotating blades to collide with the particles to increase the charging efficiency.

In addition, the rotating blades of the rotating frictional charging body rotate to keep the fine powder and air in an aerosol state, and the separation efficiency is high by preventing agglomeration of the fine powder.

A raw material injector is connected in a tangential direction to the rotating frictional charged body, and the raw material input amount is increased by the rotational suction force of the rotating body.

Brush-type rotating battery (figure 4) improves charging performance by spraying fine powder on the brush so that the fine powder passes through or hits the brush and is charged by the surface energy difference between the fine powder and the brush flesh while passing through the brush. And to prevent the aggregation of fine powder.

The plate-type rotating charging body is sprayed with fine particles on the blades of the plate rotating to prevent the collision of particles and particles by charging due to the difference of surface energy between the fine particles and the plate and by turbulence by the rotation of the plate. And the separation performance is improved by maintaining the dispersibility.

4. Parallel plate type electrostatic separator

A voltage is applied to the parallel and flat electrodes to form an electric field between the electrodes, and when the charged fine powder passes through this portion, an electric field is applied to the fine powder to separate the powder.

5. Removal of fine powder with electrode plate

In order to prevent the reduction of the electric field strength due to the adhesion of the charged powder to the electrode plate and to prevent the electrical breakdown between the electrode plates, the brush made of the insulating cell is moved at regular intervals to remove the powder with the electrode plate.

6. Easy to increase powder processing capacity

The processing capacity can be easily increased by increasing the width in the horizontal direction of the parallel plate type electrode plate and the rotating friction charging unit and by expanding the unit cells in parallel.

7. Easy yield adjustment

By installing a central separator in the middle of the electrostatic separator, the yield can be easily adjusted by the downward movement of the central separator.

The central separator was moved about 2.5cm from side to side using a motor to change the yield.

1 and 2 are schematic diagrams of a conventional fine powder separating apparatus.

3 is a schematic view of a fine powder separating apparatus according to the present invention.

4 and 5 are schematic diagrams showing respective embodiments of the rotating body of the rotating frictional charging body.

6 is a schematic perspective view showing an embodiment of a raw material feeder.

7 is a schematic perspective view showing an embodiment of a raw material feeder.

8 is a schematic diagram of an electrode plate fine powder removing device.

9 is a conceptual diagram for scaling up the processing capacity of a device.

FIG. 10 is a graph showing the results of separation by putting coal ash having different amounts of unburned carbon into a plate rotating friction pad.

* Explanation of symbols for main parts of the drawings

10: air inlet 12: mixed powder moving path

14, 16: triboelectric charging surface support 18, 20: triboelectric charging surface

22: air movement path 40, 42: powder feed screw

44, 46: powder inlet 50, 52: powder inlet

60: charged powder discharge port 70, 72: drum electrode portion

71, 73: powder removal edge 74, 76: powder collection part

75, 77: Drum rotation direction 78: Separator

80: round 82: raw material feeder

86: powder inlet 87: direction of rotation

88: inner wall 90: rotating wing

92: charged powder discharge port 94: powder discharge induction pipe

1: air inlet 2: mixed powder nozzle

3: fine powder injection hole 4: drive motor

5: rotating friction charging body 6: rotating blades

7: Charged powder distributor 8a, 8b: (+) (-) electrode plate

9: yield control plate 10: electrostatic separator

11 brush 12 air cylinder

13a, 13b: cyclone 14a, 14b: fine powder collecting part

15a, 15b: bag house filter 16, 21: rotating shaft

17: brush blade 19, 24: air and fine powder inlet

22 plate blade 18, 23 enclosure

20, 25: distributor 26: circular air inlet

27: fine powder inlet 28: circular mixed powder nozzle

29: plate-type air input unit 30: air input unit

31: injector main body 32: fine powder inlet

34: fine powder injection furnace 35: plate-shaped mixture nozzle

36: circular mixture nozzle part 37: square mixed powder nozzle part

38: mixed powder outlet 39: piston rod

40: flange joint 41: insulating rod support

42: insulating brush 43: insulating rod

44: electrode plate 45: electrostatic separator enclosure

46: air cylinder 47, 51: rotary frictional charging

48, 52: venturi injcctor 49, 53: electrostatic separator

50, 54: cyclone and powder collection port

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Referring to FIG. 3, the fine powder separating apparatus of the present invention is charged with air (1) and charged with fine powder inlet (3) to charge the fine powder and feed it into the rotating frictional charging body (5). It is configured to add the powder. When the mixed powder nozzle part 2 is shown in detail (FIG. 6), when compressed air is introduced into the circular air inlet part 26 having a narrow end, suction force of external air is generated by expansion of the compressed air. The fine powder is fed into the mixed powder nozzle part 2 connected to the fine powder inlet 3 of FIG. The fine powder and the compressed air are entangled by the strong stirring in the nozzle shape of the mixed powder nozzle part 28 of FIG. 6, and the friction and collision degree between the fine powders and the wall of the powder injector 27 (venturi injector) The fine powder makes a strong play. In addition, since the discharge rate of air is high, aggregation of fine powder can be prevented. Each part in FIG. 6 consists of a circular shape. In addition, as shown in FIG. 7, there is a method of increasing the width in the lateral direction of the fine powder input part 32, the air input part 30, and the nozzle part. This method can reduce the number of raw material inlets, distribute the fine powder evenly, and is advantageous for increasing the capacity. In order to obtain a strong charging performance in the mixed powder nozzle part, the cross-sectional shape of the nozzle part may be changed as in the plate shape 35, the circle shape 36, and the square shape 37.

In FIG. 1, the rotating frictional charging body 5 is capable of adjusting the speed of the rotating body 6 at 1000 to 4000 rpm using the driving motor 4 and an inverter. As shown in FIGS. 4 and 5, the rotating body 6 of the rotary frictional charging body 5 has rotating shafts 16 and 21 coupled with the driving motor 4 and the rotating shaft 16 thereof. It is composed of rotary blades (17, 22) to protrude radially from the (21) to maximize the collision with the mixed powder while generating a centrifugal force. The rotary blades 17 and 22 of the rotor 6 may use a stainless steel brush (FIG. 4) and a copper plate or a stainless steel plate (FIG. 5). When the fine powder incident at an angle of about 30 degrees from the outlet 38 of the mixed powder nozzle part is injected between the rotary blades 17, the fine powder passes through the brush or strikes the blade while being charged with contact friction. In addition, the fine powder injected by the rotary blade 22 of another embodiment is charged with the plate of the rotary blade. Brush-shaped rotary blade 17 and plate-shaped rotary blade 22 is fixed to the rotating shaft made of stainless steel to enable a long time operation. Enclosures 18 and 23 of the rotating charger were also made of steel or stainless steel to be firm. Distributors 20 and 25 located in the outlet part of the rotor are adapted to adjust the outlet width to 2 to 5 mm in order to spread the particles evenly and to prevent breakdown between the electrode plate and the high voltage applied part of the electrostatic separator. In order to prevent the use of a material such as acrylic or Teflon or the Teflon coating on the outside of the steel material to be used.

The electrostatic separator for separating the charged powder is provided with a copper electrode plate (+) (-) (8a, 8b in FIG. 3, 44 in FIG. 8) of 10 cm distance from FIGS. 3 and 8 Was applied to adjust the electric field to 1 to 10 kV / cm. Teflon or acrylic plate was used to support the electrode plate. In addition, an insulating brush (11 in FIG. 3; 42 in FIG. 8) was used to remove the powder attached to the electrode plate. In FIG. 8, the insulating brush 42 has an insulating material brush attached to the insulating rod 43, and the brush removes the fine powder attached to the electrode plate. The insulated rod was supported by the piston rod 39 and the flange joint 40 of the air cylinder 46 moving 1 to 10 times per minute by compressed air. In addition, in FIG. 3, the yield control of the fine powder was easily performed by using the rotatable yield control plate 9 having a height of about 10 cm on the electrostatic separator 10 between the electrodes. The yield control panel is controlled by an electric motor (not shown) to move about 2.5 cm from side to side.

The separated powder is introduced into the cyclone and collected by the suction force of the bag filter (B / F) connected to the cyclone 13a, 13b outlet in FIG. 3, and the fine powder collecting portions 14a, 14b are collected. It is collected using. In order to increase the fine powder treatment capacity of the installation, the width of the mixed powder nozzle unit 52, the rotating frictional charged member, the mixed powder nozzle unit 33, and the electrode plate may be increased. It was.

Referring to the operation of the present invention configured as described above are as follows.

When compressed air (air pressure 1 to 3 kgf / cm 2) is introduced into the inlet, a strong external suction force is generated by compression and expansion in the nozzle, and the fine powder mixture is naturally introduced through the raw material inlet. The fine powder introduced together with the compressed air is charged with (+) (-) when the fine powder mixtures with different surface energy are contacted and rubbed with each other due to the strong stirring action, and the rotary frictional charged material in the aerosol state (5 Flows into). The rotary blade 6 rotated at 1000 to 4000 rpm by the drive motor 4 for driving the rotating friction type charged material is charged with powder at the raw material input part using a material having a median surface energy of the fine powder mixture. Once again, the friction between the powders and the rotor blades and the powders is increased to increase the charge amount. The powder is continuously injected into the injection port 7 in the aerosol state by the rapid rotation of the rotating charging body. The charged fine powder is introduced into the vertical electric field separator by passing through the injection holes 7 with a spacing of 2 to 5 mm.

The following embodiments are derived from the configuration and operation of the present invention as described above.

Example 1

The rotational speed of the rotating frictional anti-electric drive motor was introduced at 4000 rpm. Compressed air pressure was 2.0 kgf / ㎠, sample input 54 kg / hr, electrode spacing 10 cm, applied voltage 40 kV, and unburned carbon content of 9.6%. Table 2 shows the results of the comparative experiments of the rotating frictional charged body. The flat frictional charging body has rather good separation performance.

Example 2

The rotating speed of the rotor was 2000 rpm when the flat rotary frictional charged, 2.0 kgf / cm2 of compressed air pressure, 54kg / hr of sample input, 10cm of electrode spacing, applied voltage kV, and coal ash containing 9.6% unburned carbon. Table 3 shows the experimental results at the change of 4000 rpm.

The separation efficiency of rotational speed 2000rpm and 4000rpm was almost equal.

Example 3

The unburned carbon content is 9.6 under the operating conditions of a device with a rotating speed of 2000 rpm for a plate-type rotating friction electret drive motor, 2.0 kgf / cm2 of input compressed air pressure, kg / hr of sample input, 10 cm of electrode spacing, and an applied voltage of 40 kV. Figure 10 shows the unburned carbon separation efficiency according to the yield when the coal ash (%, 6.1%) is added. It was found that the yield could be refined to less than 3% of unburned carbon at the yield of 60% with 9.6% coal ash and 80% yield with 6.1% coal ash.

The present invention described above is not limited to the above-described embodiments and drawings, and it is common knowledge in the art that various molars, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be obvious to those with

Applying the present invention as described above can maximize the charging performance because the fine powder is charged first in the mixed powder inlet and the second charge in the rotating charging body, so as to increase the width of the electrode plate and the rotating friction charging member The charging performance can be maximized the processing capacity in the undegraded state, and also has the effect of increasing the reliability of the process because it is configured to adjust the yield so that a constant flow of powder at all times.

Claims (7)

In the fine powder separator which separates and collects the charged fine powder, the compressed air mixes with the injected fine powder while inflowing and expands, and the fine powder collides with the inflow force of the air to make the primary chargeability. The mixed powder inlet and the mixed powder inlet allow the mixed powder in an aerosol state to flow in a tangential direction, while the introduced mixed powder has a secondary charging property by collision with a rotating body rotating at high speed. A charging unit made of a whole; (+) (-) Electrode plate, which is installed to separate and charge the mixed powder having chargeability that has escaped through the rotary frictional charged separately according to the charge polarity, the mixed powder uniformly flow into each electrode plate Separating device of fine powder using the electrostatic separation type of airflow layers including an electrostatic separator consisting of an electrostatic separator configured to guide. The method according to claim 1, wherein a plurality of venturi injectors are installed one by one, and the compressed air inlet passage extends the raw material inlet in the width direction so that a large amount of mixed powder is evenly introduced and the number of the raw material inlets is reduced. Fine powder separating device using the airflow collision electrostatic separation, characterized in that to improve the charging function. According to claim 1, wherein the friction type friction material is a material having a median work function of the two materials to be separated and comprises a rotary blade in the form of a brush (brush) or plate (plate), the high speed (200) A fine particle separation device using an airflow collision electrostatic separation type, which is hard to increase the charging function due to particle-to-particle collision and particle-to-charge medium collision by rotating. The method according to claim 1, wherein the fine powder charged in the charging unit is uniformly introduced into the vertical electric field separator to branch the fine powder, each moving to the positive (+) (-) electrode, according to the charge polarity to the electrostatic separator. Air flow collision electrostatic separator comprising a yield control plate in the upper portion of the plate to rotate in a predetermined range by the motor drive to adjust the yield of the mixed powder. The airflow collision according to claim 1 or 4, wherein the powder attached to the electrode plate lowers the electric field strength, so that the powder attached to the electrode plate is removed at a predetermined time interval with an insulating brush to improve the fine powder separation performance. Fine powder separator using electrostatic separation type. According to claim 1, Since the powder processing capacity per electrode plate width is limited, in order to increase the fine powder processing capacity, a plurality of electrode plates are installed in parallel and the electrode plate width is extended to increase the powder processing capability. Fine powder separator using airflow impact electrostatic separation type. The fine powder naturally introduced by the expansion of compressed air is first charged by the particle and particle collision and the collision between the particle and the wall by strong agitation in the nozzle (venturi injector). Secondary charging by collision with the rotating body or collision of particles with the high-speed rotating vortex and uniformly flows them into the vertical electric field separator to move the fine powder moving in the direction of the (+) (-) electrode according to the charge polarity. Separation method of fine powder using airflow impingement type electrostatic separation type which separates each with central separation plate.

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