JP3948415B2 - Electric dust collector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a road tunnel, a roadside, a road intersection, or an industrial and industrial electric dust collector.
[0002]
[Prior art]
Air in automobile tunnels and road intersections contains harmful particles emitted from automobiles, smoke, and airborne particles such as tires and road asphalt abrasion dust that are generated as automobiles run. Therefore, in order to purify the air containing the suspended particles, an electric dust collector has been put into practical use, and is operating in highway tunnels and ventilation stations.
[0003]
For example, a conventional electrostatic precipitator includes a charging unit that charges introduced airborne particles and a dust collecting unit that collects charged airborne particles that have passed through the charging unit. The charging unit includes a discharge line and a ground electrode. When a negative DC high voltage is applied to the discharge line, a negative corona discharge is generated between the parallel opposing ground electrodes. The dust collecting portion is composed of a high voltage electrode and a ground electrode. When a negative DC high voltage is applied to the high voltage electrode, a DC equal electric field is generated between the parallel opposing ground electrodes. When air containing dust particles and other suspended particles is introduced into the electrostatic precipitator by a fan, the suspended particles in the air are charged negatively by passing through the corona discharge area of the charged part, and the DC of the dust collected part. Coulomb force works by the equal electric field and is collected on the ground electrode.
[0004]
Conventionally, a plate-like discharge electrode and a ground electrode are arranged in parallel, thorn-shaped protrusions are formed at a constant pitch at the upstream end of the air flow of the discharge electrode, and the upstream pitch at the downstream end. 2. Description of the Related Art An electrostatic precipitator is known in which thorn-like protrusions are formed at different constant pitches to uniformly generate corona discharge in a charging portion and improve dust collection efficiency (see, for example, Patent Document 1). . There is also known an electric dust collector in which barbed protrusions having the same pitch are formed at the upstream end and the downstream end of the air flow of the discharge electrode (see, for example, Patent Document 2).
[0005]
[Patent Document 1]
JP-A-2002-192014 gazette
[Patent Document 2]
JP-A-10-28897 [0007]
[Problems to be solved by the invention]
However, in the conventional electrostatic precipitator provided with the thorn-shaped protrusions, the corona discharge region only spreads uniformly from the tip of the thorn-shaped protrusion toward the adjacent ground electrode. That is, between adjacent protrusions, the discharge currents repel each other, so that the current density is reduced, and a very low density region is generated. For this reason, the dust collection efficiency was not always high.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide an electric dust collector that can save power and obtain a higher dust collection performance than the conventional one.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is directed to a charging unit that charges the introduced floating particles in the air, and a dust collection that collects the charged floating particles in the air that have passed through the charging unit. The charging unit includes a discharge electrode plate and a ground electrode plate arranged in parallel, and a protrusion having a different protrusion length is provided at an upstream end of the air flow of the discharge electrode plate. A plurality of the protrusions are alternately formed, and a protrusion angle of a short protrusion having a short length among protrusions having different protrusion lengths is larger than a protrusion angle of a long protrusion having a long length among protrusions having a different protrusion length.
[0010]
According to a second aspect of the invention, in the electrostatic precipitator according to the first aspect, a plurality of protrusions having different protrusion lengths are alternately formed at the downstream end of the air flow of the discharge electrode plate.
[0012]
According to a third aspect of the present invention, in the electric dust collector according to the first aspect, a rectangular wave AC high voltage is applied to the dust collecting portion.
[0013]
According to the present invention, by alternately forming a plurality of protrusions with different protrusion lengths on the same side of the discharge electrode plate, a corona discharge region generated between the parallel opposing ground electrodes is generated in a hierarchical manner, thereby Further, the corona discharge region from the projection having the small projection length can be allocated to the region where the current density of the corona discharge between the projections having the large projection length is reduced, and the overall dust collection efficiency can be improved.
[0014]
Here, the protrusions having different protrusion lengths have different protrusion angles , and a plurality of protrusions can be formed on both the upstream side and the downstream side of the discharge electrode. Furthermore, a rectangular wave AC high voltage is applied to the dust collection portion. These also improve the dust collection efficiency.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
FIG. 1 is a plan view showing an electric dust collector according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.
[0017]
The apparatus includes a charging unit 1 and a dust collection unit 11. The charging unit 1 includes a plate-like discharge electrode 2 and a ground electrode 5, and both electrodes 2 and 5 are opposed to each other in parallel. DC high voltage is applied.
[0018]
A plurality of protrusions having different protrusion lengths (long protrusions 3 having a longer length and short protrusions 4 having a shorter length than this) are alternately formed on one side constituting the upstream end of the dust-containing air flow of the discharge electrode 2. ing. Here, the protrusions having different protrusion lengths are not necessarily two types. Also, different protrusion angles (angles of protrusion tips) may be used, and a plurality of protrusions having different protrusion lengths similar to the long protrusions 3 and the short short protrusions 4 are formed on one side constituting the downstream end of the discharge electrode 2. Also good. Here, the protrusion having a different protrusion length on the downstream side may be different from the upstream end.
[0019]
When a negative DC high voltage is applied from the power source 6 to the discharge electrode 2 of the charging unit 1, a negative corona discharge is generated between the parallel facing ground electrode 5. Here, since the protrusion lengths of the protrusions 3 and 4 that are the starting points of the corona discharge are different, the corona discharge region is hierarchical. That is, the corona discharge region in the horizontal plane has the highest current density in the vicinity of the protrusion tip that is the starting point of the corona discharge, and as shown in FIG. 1 to the front (upstream side of the air flow) and radially from the tip of the protrusion toward the ground electrode (indicated by discharge regions 7 and 8 in FIG. 1).
[0020]
Further, when the discharge region in the vertical plane is viewed from the front of the discharge electrode 2, it is as shown in FIG. That is, the discharge region 8 is generated from the projection 4 having a short length in the vicinity of the boundary between the two discharge regions 7 generated from the adjacent projection 3 having a long length, and a portion having a small current density in the air flow direction. Is decreasing. Thus, the corona discharge region can be efficiently generated as a whole by making the corona discharge region hierarchical.
[0021]
The dust collector 11 includes a high voltage electrode 12 and a ground electrode 13, which are opposed to each other in parallel. When a negative DC high voltage is applied to the high-voltage electrode 12 of the dust collector 11 from the DC high-voltage power supply 14, a DC equal electric field is generated between the parallel opposing ground electrodes 13. Here, instead of the DC high voltage power supply 14, a rectangular wave AC high voltage may be applied from the AC high voltage power supply 15.
[0022]
When a rectangular-wave AC high voltage is applied to the high-voltage electrode 12 of the dust collecting portion 11, an AC equal electric field is generated between the parallel-facing ground electrodes 13. The AC equal electric field can suppress the re-scattering phenomenon of the collected particles and improve the dust collection performance.
[0023]
The suspended particles 9 and 10 such as dust are efficiently charged to the negative polarity by passing through the corona discharge region of the charging unit 1, and the DC equal electric field or the AC equal electric field of the dust collection unit 11. , The Coulomb force acts and is collected on the ground electrode 13 (the collected particles are indicated by 16).
[0024]
<Experimental result>
The experimental apparatus is composed of a charging portion and a dust collecting portion, and the charging portion is composed of a plate-like discharge electrode facing the plate-like ground electrode in parallel (other configurations are the same as those in FIG. 1).
Charging part:
Discharge electrode (size): 80mm x 150mm
Ground electrode (size): 100mm x 150mm
Applied voltage: DC (-) 5.0 to 12.0 kV
Dust collector:
High voltage electrode (size): 130mm x 150mm
Ground electrode (size): 150mm x 150mm
[0025]
Here, the shape of the discharge electrode used in the experiment is shown in FIG.
In FIG.
Projection angle of projection A φ1: 30 °
Length of protrusion A L1: 10 mm
Arrangement pitch P of protrusions A in the comparative discharge electrode 1: 10 mm
Arrangement pitch P2 of protrusions A in the comparative discharge electrode 2: 20 mm
Projection angle φ2 of projection B shorter than projection A: 60 °
Protrusion B length L2: 5 mm
Comparative discharge electrode 1: N projections A are formed on the front side Comparative discharge electrode 2: N / 2 projections A are formed on both the front and rear sides of the present invention discharge electrode: Protrusions A and B are alternately formed on the front side. FIG. 4 shows the result of the dust collection experiment using each discharge electrode having such a structure. The charged portion discharge power ratio on the horizontal axis is obtained by setting the discharge power at which the dust collection efficiency is 90% using the comparative discharge electrode 1 to 1.0.
[0026]
As shown in FIG. 4, when the discharge power required for the dust collection efficiency of 90% is 1.0 for the comparative discharge electrode 1, the discharge power of the comparative discharge electrode 2 is about 1.4, and the discharge power of the present invention discharge electrode is about 0. 7 Therefore, it is clear that the discharge electrode of the present invention in which the protrusions A and B having different protrusion lengths and protrusion angles are formed on the same side can obtain a high dust collection efficiency with the lowest discharge power.
[0027]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electric dust collector capable of obtaining high dust collection performance with power saving.
[Brief description of the drawings]
FIG. 1 is a plan view showing an electric dust collector according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is a diagram showing a shape of a discharge electrode.
FIG. 4 is a diagram showing experimental results.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Charging part 2 Discharge electrode 3, 4 Protrusion 5 Ground electrode 6 DC high voltage power supply 7, 8 Corona discharge area 9, 10 Particles

Claims (3)

An electrostatic precipitator comprising a charging unit that charges airborne particles introduced in the air and a dust collection unit that collects charged airborne particles that have passed through the charging unit,
The charging unit has a discharge electrode plate and a ground electrode plate arranged in parallel,
A plurality of protrusions with different protrusion lengths are alternately formed on the upstream end of the airflow of the discharge electrode plate,
An electric dust collector, wherein a projection angle of a short projection having a short length among the projections having different projection lengths is larger than a projection angle of a long projection having a long length among projections having a different projection length.   2. The electrostatic precipitator according to claim 1, wherein a plurality of protrusions having different protrusion lengths are alternately formed at a downstream end of the air flow of the discharge electrode plate.   2. The electric dust collector according to claim 1, wherein a rectangular wave AC high voltage is applied to the dust collector.

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