KR101375468B1 - Electric dust collector - Google Patents

Abstract

The present invention provides an electrostatic precipitator capable of efficiently collecting nano-class ultrafine particles such as diesel exhaust particles (DEP) without adding a special apparatus. As a solution for this purpose, in the electric dust collecting device comprising a charging unit and a dust collecting unit arranged in front and rear ends, the dust collecting unit is formed by a flat plate-shaped high voltage electrode and a ground electrode which are arranged in parallel to face each other through a space through which processing air flows. And a plurality of punching holes are distributed and provided on the entire surface of at least one of the electrodes.

Electrostatic precipitator, charging unit, ground electrode, discharge electrode

Description

Electric Dust Collector {ELECTRIC DUST COLLECTOR}

The present invention relates to an electrostatic precipitator for purifying air or gas by removing these contaminants from air or gas contaminated with fine dust in indoors, tunnels, or various suspended particles.

For example, the air in a tunnel of an automobile road is contaminated by fine suspended particles such as fumes contained in exhaust gas discharged from a traffic vehicle, and worn dust of tires or asphalt pavement materials on road surfaces generated by running of the vehicle. It is. In order to remove contaminants such as suspended particles in contaminated air, a two-stage electrostatic precipitator having a charging unit and a dust collecting unit is used.

The electric dust collector of the general two-stage structure is comprised as shown in FIG.

The electrostatic precipitator 10 includes a charging unit 20 and a dust collecting unit 30. The charging unit 20 generates a positive or negative corona discharge by applying a high DC voltage to the flat or linear discharge electrodes 21 and the flat ground electrodes 22 placed in parallel to generate air flowing between the two electrodes. It is ionized and the floating particle contained in this is charged with positive or negative unipolarity. The dust collector 30 forms an electrostatic field by applying a direct current high voltage between the plate-shaped high voltage electrode 31 and the ground electrode 32 placed in parallel, and the ground electrode 32 is charged in the charging unit 20. Suspended particles are attracted by the coulomb force and collected. Thus, when the contaminated air containing the suspended particles is supplied from the inlet 11 of the dust collector 10 upstream of the charging unit 20 by a blower or the like, the outlet of the dust collector 10 downstream of the dust collector 30 ( 12) clean air from which suspended particles have been removed can be taken out.

Such an electrostatic precipitator is used as an electrostatic precipitator for cleaning the air of an automobile road tunnel because the electrostatic precipitator has a high dust collection efficiency even for fine particles of 1 μm or less and is suitable for the treatment of a large flow rate of air.

By the way, in air in car road tunnel. The diesel exhaust particle (DEP) discharged from a diesel car etc. is contained in large quantities. Since DEP is ultrafine particles having a particle diameter of 100 nm or less, nanoparticles having a particle size of 50 nm or less, and a light mass, there is a problem that the DEP cannot be efficiently collected even by an electrostatic precipitator. Since ultrafine particles and nanoparticles such as DEP adversely affect human health, there is a strong demand for efficient collection and removal of these particles.

Conventionally, as a means for improving dust collection efficiency, disperse | distributing and providing many punching holes in a dust collecting pole plate is performed (refer patent document 1).

In patent document 1, the punching hole is provided so that the total opening area may occupy 10 to 50% of the area of the dust collecting plate. And by providing this punching hole, patent document 1 concentrates the electric current from a discharge pole plate in the part between the punching hole, and even if the attached dust is going to grow more, the area of the dust collecting pole plate to attach is small, and Since excessive dust growth is suppressed by the flow of air through the punching hole, dust adhered to the dust collecting plate falls, and growth of dust collection is not observed. It is described as not shown.

Patent Document 1: Japanese Patent No. 3427165

As described above, in the conventional electrostatic precipitator, the invention has been devised to increase the dust collection efficiency by distributing a plurality of punching holes in the dust collecting plate, but it is not considered to increase the dust collection efficiency of the ultrafine particles and nanoparticles.

Accordingly, an object of the present invention is to provide an electrostatic precipitator capable of efficiently collecting ultra-fine particles such as diesel exhaust particles (DEP) or nanoparticles without requiring the addition of a special device to solve such problems. To provide.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention is the electric dust collector which comprised the charging part and the dust collector in front and rear ends, WHEREIN: The said dust collector is a flat plate shape arrange | positioned in parallel and facing through the space through which process air flows. It consists of a high voltage electrode and a ground electrode, disperse | distributes many punching holes in the whole surface of at least one electrode of the said both electrodes, and makes the opening diameter of the said punching hole strong in the electric field intensity of the periphery of the periphery of an opening. Is an area whose value is larger than the area where the electric field strength becomes weak (claim 1).

In the invention according to claim 1, the opening diameter of the punching hole is preferably 2 to 10 mm (claim 2). In the invention according to claim 1 or 2, the punching hole is preferably provided in the high voltage electrode (claim 3). The high voltage electrode and the ground electrode are arranged alternately with each other at predetermined intervals (claim 4).

According to the present invention, the punching hole of the electrode plate is provided by a simple configuration in which a plurality of punching holes are dispersed and provided on the entire surface of at least one electrode of both electrodes of the dust collecting part for collecting the floating particles contained in the process air. Because the electric field is concentrated at the circumferential edge, the electric field between the electrodes of the dust collector is not a uniform electric field, but becomes an unequal electric field distributed in a high electric field and a low electric field. Can be efficiently collected, and the efficiency of collection (dusting) of ultra-fine particles, which is usually difficult to collect, can be increased.

EMBODIMENT OF THE INVENTION The Example which shows embodiment of this invention in drawing is demonstrated.

1 is a configuration diagram showing the basic configuration of an electrostatic precipitator according to an embodiment of the present invention.

In FIG. 1, the code | symbol 10 is the electrical dust collector provided with the charging part 20 and the dust collecting part 30. As shown in FIG. The charging unit 20 generates a corona discharge by applying a high voltage of direct current between the discharge electrode 25 made of stainless steel wires and the flat plate-shaped ground electrode 22 placed in parallel in the body 11. The air flowing in between is ionized and the floating particles contained therein are charged with unipolarity. The dust collecting part 30 forms a electrostatic field by applying a direct current high voltage between the high voltage electrode 35 and the flat ground electrode 32 provided by distributing a plurality of punching holes 35h to the flat electrode placed in parallel. Then, the ground electrode 32 attracts and collects the suspended particles in the air charged by the charging unit 20 by the Coulomb force. Thus, when the polluted air containing the suspended particles is supplied by the blower or the like from the inlet 11 of the dust collecting device 10 located upstream of the charging unit 20, the dust collecting device 10 located downstream of the dust collecting unit 30. The clean air from which the suspended particles have been removed can be taken out from the outlet 12 of).

The electrostatic precipitator 10 according to the present invention basically hardly changes from the conventional electrostatic precipitator. However, the high-voltage electrode 35 of the dust collecting part 30 in this invention consists of flat electrode plates, such as stainless steel, as shown in FIG. 2, disperse | distributes to the whole surface, and many punching holes 35h exist. It differs from the conventional apparatus in that it is provided. This punching hole 35h is preferably provided evenly.

The inventors or the like have provided a plurality of punching holes 35h in the high voltage electrode 35 in the dust collecting part 30 from various experiments, so that the periphery of the opening of the punching hole 35h of the high voltage electrode 35 is provided. The concentration of the electric field occurred, and the knowledge that the finer floating particles can be collected by the concentration of the electric field at the circumferential edge of the punching hole 35h is obtained.

The present invention is based on such knowledge, and the inventors and the like simply provide a plurality of punching holes 35h on the entire surface of at least one electrode of both electrodes 32 and 35 of the dust collecting part 30 to provide a simple configuration. By this, it has been found that the collection efficiency of the ultrafine particles and the nanoparticles in the electrostatic precipitator 10 can be improved, and the removal rate of the diesel exhaust particles (DEP) can be increased by using the air treatment in the tunnel.

Next, the result of the dust collection experiment by the electric dust collector 10 of this invention is demonstrated.

The structure of the dust collection experiment apparatus by the electric dust collector 10 of this invention is shown in FIG. This experimental apparatus collects the diesel exhaust particles contained in the exhaust gas discharged from the diesel engine 50 and purifies the exhaust gas.

The exhaust gas of the diesel engine 50 mixes with the outside air by the air mixer 51 and becomes lean, and is sent to the electrostatic precipitator 10 by the fan 52 at a flow rate of 7 m / s. The electrostatic precipitator 10 processes the exhaust gas sent, separates and collects floating particles such as diesel exhaust particles contained therein, and discharges the purified exhaust gas. In order to measure the dust collection efficiency of the electric dust collector 10, the number of suspended particles can be counted for each particle diameter at an inlet (upstream) and an outlet (downstream) through which the exhaust gas of the dust collector 10 flows. Particle counting devices 61 and 62 are provided.

When the count value of the counter device 61 provided on the upstream side of the electrostatic precipitator 10 is Nu, and the counter value of the counter device 62 provided on the downstream side is Nd, the electrostatic precipitator ( The dust collection efficiency (η) (%) of 10) can be obtained.

 η = (1-Nd / Nu) × 100 (%) (1)

The structure of the specific electrode of the charging part 20 and the dust collecting part 30 of the electric dust collector 10 used for this dust collection experiment is shown in FIG.

The charging unit 20 has a 9.5 mm gap between the ground electrode 22 made of a stainless steel plate electrode having a width x height of 65 mm x 70 mm and a discharge electrode 25 made of a tungsten wire having a diameter of 0.26 mm. It is arrange | positioned. The discharge electrode 25 is supplied with a DC high voltage of -9 kV to the ground electrode 22 to cause negative corona discharge.

The dust collecting part 30 has a 9 mm gap between the high voltage electrode 35 made of stainless steel plate electrodes having the same size as the ground electrode 32 made of stainless steel plate electrodes having a width × height of 160 mm × 70 mm. And parallel to the air flow. A direct current voltage of -7.5 에 is applied to the high voltage electrode 35 with respect to the ground electrode 32.

In the embodiment shown in FIG. 1, the dust collecting part 30 is constituted by one high voltage electrode 35 and two ground electrodes 32, but the present invention is not limited to such a configuration. When there is much air flow, as shown in FIG. 9, the dust collecting part 30 is comprised by the several high voltage electrode 35 and the several ground electrode 32, and each electrode is mutually spaced at predetermined intervals. It is preferable to arrange them alternately. In addition, the electrodes of the charging unit 20 are also arranged alternately.

In Table 1 and Table 2, the specification of the sample electrode used as the high voltage electrode 35 in the dust collection experiment of this invention is shown. In Table 1 and Table 2, the comparison electrode shown by sample number S0 is a flat electrode in which the punching hole was not provided.

[Table 1]

Sample number Aperture diameter
(mm) Numerical aperture Opening total area
(mm ² ) Aperture ratio
(%) Total rim length L (mm) of opening SO 0 0 0 0 0 SA1 2.5 21 103 1.1 165 SA2 5 21 412 4.3 330 SA3 10 21 1649 17.2 659 SA4 13 21 2786 29.0 857

In the sample electrode groups represented by Sample Nos. SA1 to SA4 in Table 1, the number of punching holes 35h provided in a flat electrode having a size of 160 mm x 70 mm was fixed to 21, and the diameters of the holes were 2.5 mm to 13, respectively. It changed between mm. In this case, since the number (opening number) of the punching holes 35h is fixed at 21, as shown in Table 1, as the opening diameter of the hole increases, the total opening area, the opening ratio and the total circumference of the opening are shown. The length L becomes large.

[Table 2]

Sample number Aperture diameter
(mm) Numerical aperture Aperture total area
(mm ² ) Aperture ratio
(%) Total perimeter edge length of opening L (mm) SO 0 0 0 0 0 SB1 2.5 336 1649 17.2 2638 SB2 5 84 1649 17.2 1319 SB3 10 21 1649 17.2 659

The sample electrode groups of Sample Nos. SB1 to SB3 in Table 2 have an opening ratio ((opening total area / electrode area of the punching hole) × 100 () of the punching hole 35h provided in the plate electrode having the same size as the sample electrode of Table 1. %)] Is fixed at 17.2%, and the diameter of the punching hole is changed between 2.5 mm and 10 mm. In this case, since the aperture ratio is fixed at 17.2%, as shown in Table 2, as the aperture diameter of the aperture increases, the number of apertures (the number of apertures) and the total circumferential edge length L of the aperture become smaller. And the total opening area becomes large.

Regarding the electrostatic precipitator 10 in which the sample electrodes SA1 to SA4 and SB1 to SB3 shown in Tables 1 and 2 were used as the high voltage electrodes 35 of the dust collecting section 30, the above-described experimental apparatus (see FIG. 3). Dust collection experiments were conducted respectively, and the dust collection efficiency (η) (%) of the diesel exhaust particles (DEP) (the ultrafine particles and nanoparticles with different particle diameters) was measured.

The measurement result of the concentrated efficiency of the electrostatic precipitator 10 which made the sample electrode group (electrode which fixed the number (opening number) of the punching hole) of the sample numbers SA1-SA4 shown in Table 1 as the high voltage electrode 35 is shown. 5 is shown.

Fig. 5 shows the particle diameter d (nm) of the fine particles collected on the horizontal axis, the dust collection efficiency η (%) on the vertical axis, and the particle diameters of the fine particles of each of the high voltage electrodes S0, SA1 to SA4. It is a graph showing the dust collection efficiency characteristics. The definition of dust collection efficiency (η) is as shown in the above formula (1).

As apparent from FIG. 5, when the sample electrodes SA1 to SA4 provided with punching holes are used for the high voltage electrode 35, the dust collection efficiency with respect to ultrafine particles having a particle diameter of 100 nm or less or nanoparticles of 50 nm or less is known as a punching hole. It becomes high about the case where the comparative electrode S0 which does not provide the high voltage electrode 35 is provided. In addition, in the experiment result, when the sample electrode SA1 (opening diameter 2.5mm) was made into the high voltage electrode 35, the dust collection efficiency of the ultra-fine particle of the particle size of 100 nm vicinity makes the comparison electrode S0 the high voltage electrode 35 There is a part that becomes lower than the case where) is used, but it is considered a measurement error.

Thus, it is thought that the collection efficiency becomes high by providing the punching hole 35h for the following reason.

When the punching hole 35h is provided, a region in which the electric field strength becomes strong near the peripheral edge of the opening is generated, and a region in which the electric field strength becomes weak near the opening center is generated. In the region where the electric field strength is strong, the moving speed of the charged particles is increased, and the dust collection efficiency is improved. The size of the region where the electric field strength becomes strong and the region where the electric field strength becomes weak varies with the size of the opening diameter.

8 is a graph for explaining the relationship between the opening diameter, the area where the electric field strength becomes strong, and the size of the area where the electric field strength becomes weak. In the graph of FIG. 8, a 20 mm x 20 mm ground electrode is arranged on both sides of a 20 mm x 20 mm high voltage electrode, and a punched hole having an opening diameter of 2.5 to 13 mm in the center of the high voltage electrode. the provision, and to measure how changes in any shape by the area of the punched holes that are not arranged flat electrode of the electric field intensity 8.3 × 10 ⁵ V / m than the area of the electric field strength large area, a small area of the opening diameter size, It is interpreted.

The graph of FIG. 8 shows a flat electrode without a punch hole for the area S between the ground electrode and the high voltage electrode (the area between the ground electrode 32 and the high voltage electrode 35 seen from above in FIG. 1). The area ratio [Ss / S × 100 (%)] of the area Ss of the area where the electric field strength becomes stronger than the electric field strength of 8.3 × 10 ⁵ V / m is set to Rs (the area ratio of the area where the electric field strength becomes stronger), The area ratio [Sw / S × 100 (%)] of the area Sw of the area where the electric field strength becomes weak with respect to the area S between the electrode and the high voltage electrode is set to Rw (the area ratio of the area where the electric field strength becomes weak). The opening diameter is taken on the horizontal axis, and the area ratios Rs and Rw are taken on the vertical axis, and the change of the area ratios Rs and Rw with respect to the opening diameter is shown.

As shown in the graph of FIG. 8, when the opening diameter is small, the area where the electric field strength becomes stronger is larger than the area where the electric field strength becomes weak. However, when the opening diameter is larger than 11 mm, the area where the electric field strength becomes stronger becomes smaller than the area where the electric field strength becomes weak. This is considered to be because the opening diameter was sufficiently large for the distance between the ground electrode and the high voltage electrode (9 mm in this experiment).

In view of the above, in order to improve the dust collection efficiency, the area where the electric field strength becomes strong is increased, the moving speed of the charged particles is increased, that is, the opening diameter of the punching hole is increased, and the total circumferential edge length L of the opening is increased. If you lengthen), you can see good thing. In this case, it can be seen that the upper limit of the opening diameter may be determined in consideration of the distance between the ground electrode 32 and the high voltage electrode 35.

And as shown in FIG. 5, the electrostatic precipitator 10 using the sample electrode SA4 with the longest total rim length L of the opening of the punching hole 35h in the high voltage electrode 35 is 857 mm. ), It is possible to obtain a high dust collection performance that the dust collection efficiency of the ultra-fine particles and the nanoparticles having a particle diameter of 30 to 100nm is 60% or more.

However, when the opening diameter of the punching hole is enlarged in order to increase the total circumferential edge length L of the opening, problems such as a decrease in the electrode area and a decrease in the strength of the electrode plate arise.

Next, the measurement result of the dust collection efficiency of the electrostatic precipitator 10 which made the high voltage electrode 35 the 2nd sample electrode group (electrode which made the opening ratio constant) of the sample numbers SB1-SB3 shown in Table 2 FIG. 6 is shown.

FIG. 6 is a graph showing dust collection efficiency characteristics with respect to the particle diameter d (nm) of the fine particles to be collected by the high voltage electrodes S0 and SB1 to SB3 as in FIG. 5 described above.

As is apparent from FIG. 6, when the sample electrodes SB1 to SB3 having the punching holes 35h are used for the high voltage electrode 35 according to the present invention, the dust collection efficiency of ultrafine particles or nanoparticles having a particle diameter of 100 nm or less is used. (η) is 10% or more as compared with the case where the comparative electrode S0 in which the punching hole is not provided is used as the high voltage electrode 35. In particular, in the sample numbers SB1 and SB2 of 2.5 mm or 5 mm, the opening diameter with a long total circumferential edge length L of the opening is 20% higher.

Therefore, according to this fact, it is possible in the present invention to provide more punching holes 35h having a smaller opening diameter and to increase the total circumferential edge length L of the opening to increase dust collection efficiency. I can understand.

Next, based on the result of the dust collection experiment described above in Fig. 7, the opening total circumferential edge length L of the punching hole 35h provided in the plate-shaped electrode when the opening ratio is constant (17,2%) (mm) ) And the dust collection efficiency (η) (%) are shown. The dust collection efficiency here has shown the dust collection efficiency of the whole microparticles | fine-particles irrespective of a particle diameter.

In FIG. 7, when the total circumferential edge length L is 0 mm (flat electrode without a punch hole), the dust collection efficiency is 48%, but as the total circumferential edge length L becomes longer, the dust collection efficiency is improved, and 1319. The saturation tendency is shown above mm. In the dust collection efficiency, the total circumferential edge length L is 74% at 2638 mm. As the total circumferential edge length L becomes longer, the saturation tendency is considered to be because the aperture diameter decreases or the number of numerical apertures increases, so that the distance between the openings decreases, so that the circumferential edge electric field of the opening is relaxed.

From the above results, the dust collection efficiency can be improved by reducing the opening diameter of the punching hole, increasing the numerical aperture, and lengthening the total circumferential edge length L of the opening, but the upper limit of the opening diameter is 60%. In order to obtain%, 10 mm is an upper limit. Further, even when the opening diameter is 2.5 mm or less, the improvement of dust collection efficiency cannot be achieved, and the lower limit is 2 mm in view of the labor of the machining operation and the decrease in strength of the high voltage electrode plate.

In the present invention, not only the punching hole may be provided in the high voltage electrode 35, but the punching hole 35h may be provided in the ground electrode 32 of the dust collecting part 30, or the high voltage electrode 35 and the ground may be provided. The punching hole 35h may be provided in both electrodes of the electrode 32.

As described above, according to the present invention, at least one electrode in the dust collecting portion formed by the high voltage electrode and the ground electrode of the electric dust collector is provided with a simple configuration in which a plurality of punching holes are dispersed and provided in the entire surface of the electrode. It is possible to increase the dust collection efficiency of ultra-fine particles and nanoparticles without adding new energy and devices, so it is applied to electric dust collectors used for air purification in automobile road tunnels where ultra-fine particles or nano particles are generated such as diesel exhaust particles. In this case, the dust collecting performance can be improved, and the device can be miniaturized.

1 is a block diagram showing a basic configuration of an electric dust collector of an embodiment of the present invention.

2 is a front view showing a high voltage electrode used in the present invention.

3 is a block diagram showing a dust collecting experiment apparatus by the electric dust collecting device of the present invention.

Fig. 4 is a perspective view showing the configuration of an embodiment of the charging unit and the electrode of the dust collector of the electric dust collector of the present invention.

FIG. 5 is a graph showing dust collection efficiency with respect to particle diameters of particles to be collected in an electrostatic precipitator using the high voltage electrode of the first sample electrode group of the present invention. FIG.

Fig. 6 is a graph showing dust collection efficiency characteristics with respect to particle diameters of particulates to be collected in the electrostatic precipitator using the high voltage electrode of the second sample electrode group of the present invention.

Fig. 7 is a graph showing the dust collection efficiency characteristics with respect to the total circumferential edge length of the opening of the punching hole of the high voltage electrode of the electrostatic precipitator according to the present invention.

Fig. 8 is a graph for explaining the relationship between the electric field strength and the opening diameter of the perimeter of the opening of the punching hole of the high voltage electrode of the electrostatic precipitator according to the present invention.

9 is a configuration diagram showing a configuration of a plurality of stacked electrostatic precipitators which is another embodiment of the present invention.

10 is a block diagram showing a conventional electric dust collector.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

10: electric dust collector 20: charging unit

22 ground electrode 25 discharge electrode

30: dust collector 32: ground electrode

35 high voltage electrode 35h punching hole

Claims (4)

delete In the electrostatic precipitator comprising the charging unit and the dust collecting unit arranged in front and rear ends, The dust collector is constituted by a plate-shaped high voltage electrode and a ground electrode arranged in parallel to each other through a space in which the processing air flows, and provided with a plurality of punching holes distributed over the entire surface of at least one of the electrodes. Let the opening diameter of the said punching hole be the value of the range from which the area | region which electric field intensity | strength becomes strong near the periphery edge of an opening becomes larger than the area | region where electric field strength becomes weak, The opening diameter of the said punching hole is 2 mm-10 mm, An electrostatic precipitator, wherein the opening total circumferential edge length of the punching hole is 1,319 mm to 2,638 mm. 3. The method of claim 2, The said punching hole is provided in the said high voltage electrode, The electrostatic precipitator characterized by the above-mentioned. delete

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