JP2000197833A - Electric dust collector for tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric dust collector for a tunnel which can improve dust collection efficiency. SOLUTION: In an electric dust collector equipped with a charging part for charging particulates in gas introduced from a tunnel and a dust collection part for collecting the charged particulates in the gas passing through the charging particulates, the charging part has a plate-shaped discharge electrode 5 extending in the flow direction of the particulates and dust collection electrodes 4 arranged opposite to each other and parallel to both sides of the discharge electrode 5, and projections 12 are formed in parallel on the electrode 4 side of the discharge electrode 5. Since the projections 12 are directed to the electrode 4, a region of large electric field strength is formed between it and the electrode 4 to increase a discharge current sufficiently. Even when high flow velocity gas is intruded into a gas charging part, the particulates can be charged efficiently, and the charged particulates can be collected efficiently in the dust collection part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric dust collector for a tunnel for collecting particulate matter and the like in exhaust gas flowing from a tunnel.

[0002]

2. Description of the Related Art In a road tunnel or the like, an exhaust gas generated from an automobile or the like is sucked by a ventilation fan or the like, and an electric dust collector (hereinafter referred to as an electric dust collector for a tunnel) is used for processing the sucked exhaust gas. Used. For example, Japanese Patent Application Laid-Open No.
There is one disclosed in Japanese Patent Application Laid-Open No. 0-28897. The electrostatic precipitator described in this publication includes a charging unit for charging particles in exhaust gas flowing from a tunnel, and a collecting unit for collecting charged particles in a gas to be processed passing through the charging unit. It is a two-stage type having a dust part. The charging unit includes a flat discharge electrode extending in parallel to the flow direction of the exhaust gas, and a flat dust collection electrode disposed in parallel and opposed to both sides of the discharge electrode. A large number of triangular projections are provided at the upstream end and / or the downstream end of the exhaust gas and project in parallel with the flow direction of the exhaust gas.

[0003]

In recent years, however, it has been demanded that the speed of the tunnel ventilation flow be increased (9 m / s or more) in the electric dust collector for tunnels. There is a demand for higher performance of dust collectors, that is, improvement of dust collection efficiency.

[0004] However, in the above-mentioned conventional electric precipitator, the precipitating efficiency has not been sufficient yet from the viewpoint of improving the performance of the electric precipitator.

Accordingly, an object of the present invention is to provide an electric dust collecting apparatus for a tunnel capable of sufficiently improving the dust collecting efficiency.

[0006]

Means for Solving the Problems The present inventors have studied the above-mentioned problems of the conventional electrostatic precipitator and found that the conventional electric precipitator has a triangular projection and a dust collecting electrode. Flowing discharge current is small, uncharged particles among the particles in the exhaust gas occur, and the uncharged particles are not collected in the dust collection portion, so that the dust collection efficiency is still insufficient, which is not enough. It has been found that this is caused by the fact that a large number of triangular projections provided at the upstream end or the upstream / downstream end of the flat discharge electrode project in parallel to the flow direction of the exhaust gas.

In view of the above, the present invention provides a charging section for charging particulate matter in a gas to be processed flowing from a tunnel, and collecting charged particulate matter in the gas to be processed passing through the charging section. An electrostatic precipitator provided with a dust collecting section for charging, a charging section, a flat discharge electrode extending in the flow direction of the particulate matter, and a dust collecting electrode disposed substantially parallel to and opposed to the discharge electrode. And a plurality of projections projecting toward the collection electrode are provided side by side on the discharge electrode.

According to this configuration, since the plurality of protrusions are directed to the dust collecting electrode, a region having a large electric field intensity is formed between the protrusion and the dust collecting electrode, and the discharge current becomes sufficiently large. . For this reason, even if a gas with a high flow rate in the tunnel flows into the charging section, the particulate matter in the gas to be treated is charged efficiently, and the charged particulate matter is efficiently collected in the dust collecting section.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an electric dust collecting apparatus for a tunnel according to an embodiment of the present invention.
In all the drawings, the same or equivalent components are denoted by the same reference numerals.

FIG. 1 is a front view showing a preferred embodiment of an electric dust collector for a tunnel according to the present invention, and FIG. 2 is a sectional view taken along the line II-II of FIG.
FIG. 3 is a rear view of the electric precipitator of FIG. 1. As shown in FIG. 1, the tunnel electric precipitator 10 includes a box-shaped case 1.
The front end (upstream end) to allow the exhaust gas (gas to be processed) flowing in from the front through the ventilation fan
Is formed with a gas inlet 1a, and a gas outlet 1b is formed at the rear end (see FIG. 3). As shown in FIG. 2, inside the case 1, a charging section 2 for charging particles in a gas is disposed at a front portion thereof, and charged particles flowing from the charging section 2 are disposed at a rear portion thereof. A dust collecting section 3 for collecting is arranged, and further a charging section 2 and a dust collecting section 3 are sequentially arranged at a rear portion thereof.

As shown in FIGS. 2 and 3, the dust collecting section 3 has a plurality of plate-shaped dust collecting poles 8b extending substantially in parallel to the gas flow direction, and a flat plate between the dust collecting poles 8b. A discharge electrode 8a is inserted in parallel with the dust collection electrode 8b. The discharge electrode 8a is fixed by a support rod penetrating the case 1, and this support rod is
It is fixed to the case 1 via a pair of support insulators 11a and 11b. Further, a high-voltage DC power supply 7 is connected to the discharge electrode 8a, the dust collection electrode 8b is grounded, and the discharge electrode 8a and the dust collection electrode 8 are connected.
b, a voltage is applied, and the particles charged by the charging unit 2 are collected by the dust collection electrode 8b.

As shown in FIGS. 1 and 2, the charging section 2 has a plurality of rectangular flat plate-shaped dust collecting electrodes 4 extending along the gas flow direction. A discharge electrode 5 is inserted in parallel with the dust collection electrode 4. The interval between adjacent dust collection electrodes 4 is preferably 20 to 40 mm. If the distance between the dust collecting electrodes 4 is less than 20 mm, sparks (spark discharges) due to charge between the dust collecting electrodes 4 and the discharge electrodes 5 increase. Produce,
In addition to the need to fix the dust collection electrode 4 with high accuracy, it is necessary to minimize the deflection of the dust collection electrode 4 due to the high wind speed, which tends to increase the cost. On the other hand, if it exceeds 40 mm, the dust collecting electrode 4 and the discharging electrode 5
In the case where a high voltage is applied between the two, the outer shell (body case) for supporting and fixing the dust collecting electrode 4 and the distance between the metal fitting and the metal fitting for supporting and fixing the discharge electrode 5 are increased to prevent sparking. Is required, and the supporting insulators 11a, 11b
It is necessary to increase the size of the support insulators 11a and 11b in order to impart pressure resistance to the dust collector, and the entire electric dust collector tends to be large.

Further, the thickness of the discharge electrode 5 is preferably set at about 0.1.
3 to 0.6 mm. If it is less than 0.3 mm, a large amount of current will flow at a low voltage, but the stiffness of the discharge electrode 5 itself will be lost, and a strong tensile force will always be applied to the discharge electrode 5 in order to prevent sparks due to vibration due to high wind speed. And there is a tendency for problems of durability and fixing method to occur. On the other hand, if it exceeds 0.6 mm, the effect of the thickness of the discharge electrode 5 (the smaller the thickness of the discharge electrode 5 becomes, the higher the current becomes at a lower voltage and lower) in order to secure a current necessary for charging the particles in the gas. That is, it is necessary to apply a high voltage between the dust collection electrode 4 and the discharge electrode 5, and in this case, the dust collection electrode 4
Shell (main body case), metal fittings and discharge electrodes 5 for supporting and fixing
It is necessary to increase the distance between the support and the metal fitting for supporting and fixing, and the charging unit 2 including the support insulators 11a and 11b tends to be large.

The dust collecting electrode 4 and the discharge electrode 5 are fixed by a pair of support rods penetrating the case 1, and the support rods are fixed to the case 1 via support insulators 6a and 6b. Further, the dust collecting electrode 4 is grounded, and the discharge electrode 5 is connected to the high voltage DC power supply 13 so that corona discharge occurs between the dust collecting electrode 4 and the discharge electrode 5 so that particles in the exhaust gas are charged. Has become. The high-voltage DC power supply 13 is also connected to the discharge electrode 5 of the rear charging unit 2, and the high-voltage DC power supply 7 is also connected to the discharge electrode 8 a of the rear dust collection unit 3. The high-voltage DC power supplies 13 and 7 are provided one by one according to the charging unit 2 and the dust collection unit 3.
Are connected, but one high-voltage DC power supply is
The dust collector 3 may be connected in parallel.

Here, the configuration of the discharge electrode 5 will be described.

As shown in FIG. 4, a plurality of projections 12 are formed on the front end 5a and the rear end 5b of the discharge electrode 5, and the projections 12 are orthogonal to the surface 5c of the discharge electrode 5. It is bent. Therefore, the protrusion 1
2 is directed to the dust collection electrode 4 side. FIG.
As shown in the figure, the particles are directed to both sides of the discharge electrode 5 so as to charge the particulate matter passing through both sides of the discharge electrode 5. The projections 12 are preferably arranged side by side so as to face alternately in the opposite direction from the viewpoint of uniformly charging each side of the discharge electrode 5.

The shape of the projection 12 is not particularly limited as long as it has a pointed portion at its tip.
As shown in (a) to (e), in addition to an isosceles triangular shape, a square shape, a triangular shape, a substantially trapezoidal shape, a spike shape, and a tapered shape as shown in FIG. Here, the tapered shape refers to a shape in which both ends of the isosceles triangle or the triangle are curved in a concave shape to sharpen the tip, and the substantially trapezoidal shape refers to a shape obtained by cutting the tip of the trapezoidal shape and the tapered shape. Say. Of these, the tapered shape is particularly preferable from the viewpoint of reducing the resistance of the exhaust gas to suppress turbulence and improving the discharge characteristics.

Regarding the height of the projection 12,
Of the height of the dust collection electrode 4 to the interval of the dust collection electrode 4 is 0.05 to 0.2
5 is preferred. If the ratio is less than 0.05, the effect of bending of the projections 12 on the discharge characteristics will not be exhibited, and the discharge characteristics will be the same as that of the flat plate electrode. Therefore, it tends to be difficult for the current to flow. A dead zone where the processing gas does not pass through the corona discharge region tends to occur.
Here, the height of the protrusion 12 refers to the distance from the surface 5 c of the discharge electrode 5 to the tip of the protrusion 12.

The front projections 12 and the rear projections 12 are arranged at the same pitch, but are preferably shifted from each other by a half pitch. That is, each of the protrusions 12 at the front end is adjacent to the protrusion 1 at the rear end.
Facing between the two. For this reason, particles that pass between the protrusions 12 at the front end and are not charged tend to be sufficiently charged at the rear end. In addition, the pitch of the protrusion 12 at the front end is preferably 3 to 10 mm. If the pitch is less than 3 mm, the adjacent protrusions 12 will interfere with each other, making it difficult for current to flow, preventing stable corona discharge and reducing the dust collection efficiency. On the other hand, if it exceeds 10 mm, the corona discharge regions corresponding to the respective projections 12 do not overlap, and a location where the discharge current density is extremely low occurs between the projection 12 and the dust collection electrode 4,
There is a tendency that a dead zone where exhaust gas cannot be sufficiently charged is increased and dust collection efficiency is reduced.

Next, the operation of the tunnel electric precipitator 10 having the above configuration will be described.

In the electric dust collector 10 for a tunnel,
Since the plurality of projections 12 are directed to the dust collection electrode 4, a region where the electric field intensity is large is formed between the projections 12 and the collection electrode 4, and the discharge current becomes sufficiently large. For this reason, even if a gas having a high flow velocity (high flow velocity of 9 m / s or more) in the tunnel flows into the charging section 2, the particulate matter in the exhaust gas is efficiently charged, and the charged particulate matter is disposed in a subsequent stage. The dust is collected efficiently by the dust collecting electrode 8a of the dust collecting part 3. As a result, the dust collection efficiency of the electric dust collector 10 is improved. In addition, since the charging unit 2 and the dust collecting unit 3 are further disposed behind the dust collecting unit 3, the length of the dust collecting electrode 8b of the dust collecting unit 3 in the gas flow direction can be reduced. For this reason, the particles charged by the charging unit 2 are less likely to lose their charge in the dust collection unit 3 on the way, and the dust collection efficiency is further improved. Further, the rear portion is charged again with the particles re-scattered at the front portion, and an effect of preventing re-scattering for re-collecting at the rear portion is achieved, so that the performance can be stabilized for a long time.

When the projection 12 has a tapered shape, the resistance of the exhaust gas is reduced, the turbulence is suppressed, and the pressure loss is reduced. Further, since the tip is sharper than the triangular shape, a region where the electric field intensity is large between the protrusion 12 and the dust collecting electrode 4 is formed, and the discharge current flows more sufficiently, and as a result, the electric dust collecting device 10 improves the dust collection efficiency.

The present invention is not limited to the embodiment described above. For example, in the above embodiment, the protrusions 12 formed on the front end 5a and the rear end 5b of the discharge electrode 5 are formed.
Are bent with respect to the front surface 5c. As shown in FIG. 7, the pair of L-shaped members 14 having the projections 12 are connected to the front end and the rear end of the discharge electrode 5, or both surfaces 5c thereof. May be fixed. In this case, the shape of the protrusion 12 is preferably tapered as shown in FIG. Further, the shape of the protrusion 12 is shown in FIG.
As shown in (a) to (d), the shape may be an isosceles triangle, a square, a substantially trapezoid, a right triangle, or the like.

Next, the contents of the present invention will be specifically described with reference to examples.

[0025]

(Embodiment 1) In the charging section 2, nine rectangular flat plate-shaped steel dust collecting electrodes (height: 520 mm, length: 130 m)
m, thickness 0.5 mm) 4 are arranged in parallel at intervals of 40 mm, and a rectangular flat plate-shaped steel discharge electrode (height 410 mm, length 70 mm, thickness 0.3 mm) is provided between the dust collecting electrodes 4.
5 was arranged. The discharge electrode 5 used had a plurality of tapered protrusions 12 at its front end and was bent such that the protrusions 12 were perpendicular to the surface 5c of the discharge electrode 5. The height of each projection 12 was 5 mm, and the pitch between the projections 12 was 8 mm. In the dust collecting section 3, 1
Four rectangular plate-shaped steel dust collecting electrodes (height: 400 mm, length: 540 mm, thickness: 0.5 mm) 8a are arranged in parallel at intervals of 20 mm. A steel discharge electrode (height 390 mm, length 530 mm, thickness 0.5 mm) 8b was arranged. Here, in the charging section 2, each dust collecting electrode 4 was grounded, and each discharge electrode 5 was connected in parallel to a high-voltage DC power supply. On the other hand, in the dust collecting section 3, each dust collecting electrode 8b is grounded, and each dust collecting electrode 8a
About -9.0k connected in parallel with a high voltage DC power supply
A negative potential of V was applied. With respect to such an electrostatic precipitator 10, a voltage was applied between the discharge electrode 5 of the charging unit 2 and the precipitating electrode 4, and a discharge current was measured when the applied voltage was changed. The result is shown in FIG. As shown in FIG. 10, the discharge current was found to be sufficiently large. (Comparative Example 1) As discharge electrodes, length 410 mm, pitch 4
An electrostatic precipitator similar to that of Example 1 was used except that a triangular protrusion having a mm mm protruded in parallel with the gas flow direction.
With respect to this electrostatic precipitator, a voltage was applied between the discharge electrode 5 and the precipitating electrode 4, and the discharge current when the applied voltage was changed was measured. The result is shown in FIG. As shown in FIG. 10, the discharge current when the same voltage was applied was the same as in Example 1.
About 1/2 or less (voltage 9
kV to 11 kV).

[0026]

As described above, according to the present invention, the discharge current flowing between the projection and the dust collection electrode becomes sufficiently large, so that the gas with a high flow velocity in the tunnel flows into the charging section. The particulate matter in the gas to be treated is efficiently charged, and the charged particulate matter is efficiently collected in the dust collecting section. As a result, the dust collection efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a front view showing a preferred embodiment of an electric dust collector for a tunnel according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a rear view of the electric precipitator of FIG. 1;

FIG. 4 is a partial plan view of a charging unit of the electrostatic precipitator of FIG. 1;

FIG. 5 is a front view showing the discharge electrode of FIG. 4;

FIG. 6 is a front view showing a modification of the shape of the protrusion used in the present invention.

FIG. 7 is a plan view showing a modification of the projection used in the present invention.

FIG. 8 is a front view showing another installation mode of the protrusion.

FIG. 9 is a front view showing another modified example of the shape of the protrusion of FIG. 8;

FIG. 10 is a graph showing voltage-current characteristics in Example 1 and Comparative Example 1.

[Explanation of Symbols] 2 ... Electrification unit, 3 ... Dust collection unit, 4 ... Dust collection electrode, 5 ... Discharge electrode, 5
a: upstream end, 10: electric dust collector for tunnel, 12
…protrusion.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Shibata 63-30 Yuyugaoka, Hiratsuka-shi, Kanagawa Prefecture Sumitomo Heavy Industries Machinery Co., Ltd. No. 30 Sumitomo Heavy Industries Machinery Co., Ltd. Hiratsuka Works (72) Inventor Tsutomu Harasaki 2-1-1 Tanidocho, Tanashi-shi, Tokyo Sumitomo Heavy Industries, Ltd. Tanashi Works (72) Inventor Eisaku Murata Haneda, Ota-ku, Tokyo No. 11 Asahicho, EBARA CORPORATION (72) Inventor Nobuyuki Kato 11-1, Haneda Asahimachi, Ota-ku, Tokyo F-term in EBARA CORPORATION (reference) 4D054 AA07 BA02 BB06 BB08 BB12

Claims (4)

[Claims] 1. A charging unit for charging particulate matter in a gas to be processed flowing from a tunnel, and collecting the charged particulate matter in the gas to be processed passing through the charging unit. A charging unit, wherein the charging unit is disposed substantially parallel to and on both sides of the discharge electrode extending in the flow direction of the gas to be treated. An electric dust collecting device for a tunnel, comprising: a dust collecting electrode; and a plurality of protrusions projecting toward the dust collecting electrode on the discharge electrode. 2. The electric dust collecting apparatus for a tunnel according to claim 1, wherein, in the discharge electrode, the plurality of protrusions are arranged at least at an upstream end of the gas to be processed. 3. The electric dust collector for a tunnel according to claim 1, wherein the shape of the projection is a tapered shape. 4. The electric dust collector for a tunnel according to claim 1, wherein the adjacent projections are directed in opposite directions.