JP2018126713A - Electrostatic precipitator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic precipitator which suppresses action of reducing dust collection effect by ion wind, and can improve dust collection efficiency.SOLUTION: An electrostatic precipitator 1 includes dust collecting electrodes 4 which have a plurality of openings and are arranged along a gas flow G direction, and discharge electrodes 5 arranged parallel to the dust collecting electrodes 4. The discharge electrode 5 has a plurality of corona discharge parts 8 for corona discharge which are arranged continuously in the gas flow direction and protrude to only the one dust collecting electrode 4 out of the opposite dust collecting electrodes 4. The plurality of dust collecting electrodes 4 and the plurality of discharge electrodes 5 are arranged alternately in a direction orthogonal to the gas flow G direction. All of the corona discharge parts 8 protrude in a same direction in an upstream area S1 and a downstream area S2 of the gas flow G direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric dust collector.

  2. Description of the Related Art As a conventional electrostatic precipitator, one having a flat plate-shaped dust collecting electrode arranged in parallel along a gas flow and a discharge electrode having a sharp shape arranged in the center thereof is known.

  In the electric dust collector, a high DC voltage is applied between the dust collecting electrode and the discharge electrode, and stable corona discharge is performed on the discharge electrode to charge the dust in the gas flow. It is explained in the conventional dust collection theory that charged dust is collected on the dust collecting electrode by the action of Coulomb force acting on the dust under the electric field between the discharge electrode and the dust collecting electrode.

  Incidentally, the electric dust collectors of Patent Documents 1 and 2 include a plurality of through holes for allowing dust to pass therethrough and a dust collecting electrode having a closed space for collecting dust inside. In Patent Documents 1 and 2, trapped dust is hardly re-scattered by confining dust in a closed space through the through hole.

  The electric dust collector of Patent Document 3 includes a dust collecting electrode including a ground electrode having an aperture ratio of 65% to 85% and a dust collecting filter layer that collects gas. By providing such a dust collecting electrode, in Patent Document 3, an ion wind is generated in a cross section orthogonal to the gas flow, and a spiral gas flow circulating between the discharge electrode and the dust collecting electrode is generated. , Dust is collected efficiently. In Patent Document 3, ion wind is used positively, but this case is intended to collect dust mainly in the dust collection filter layer.

Japanese Patent No. 5761461 Japanese Patent No. 5705461 Japanese Patent No. 4823691

The dust collection efficiency η in the electric dust collector can be calculated by the well-known Deutsche formula (Formula (1)) below. w is a dust collection index (a moving speed of the particulate matter), and f is a dust collection area per unit gas amount.
η = 1−exp (−w × f) (1)

  In the above formula (1), the moving speed w of dust (particulate matter) is determined by the relationship between the force due to the Coulomb force and the viscous resistance of the gas. In Deutsche's formula (the above formula (1)), dust is assumed to move in the electric field from the discharge electrode, and the ionic wind is not directly considered in the influence on the performance. However, there is a precondition that the dust concentration, which is the premise of the performance design, is always uniform in the dust collection space between the discharge electrode and the collection electrode, and the ion wind causes gas turbulence, It is considered as one of the factors that make the dust concentration uniform.

  The ion wind is generated as a result of negative ions generated by corona discharge at the discharge electrode when a negative voltage is applied between the electrodes, and is generated by positive ions in the case of a positive voltage. Hereinafter, a case where a negative voltage is applied will be described in order to consider an industrial electrostatic precipitator as a base, but the same applies to positive cases.

  The ion wind generated at the discharge electrode flows across the gas flow toward the dust collection electrode. The ion wind that reaches the dust collecting electrode is reversed at the dust collecting electrode to change the flow direction. This creates a spiral turbulent flow between the electrodes.

  Of the turbulent flow, the flow from the discharge electrode to the dust collection electrode has an effect of carrying dust to the vicinity of the dust collection electrode. The dust transported to the vicinity of the dust collection pole is finally collected by the Coulomb force.

  However, the ion wind reversed at the dust collection electrode moves the dust in a direction away from the dust collection electrode, which is a collector, and thus has an effect of inhibiting dust collection.

  Patent Document 3 describes an electrostatic precipitator that takes into account the effect of ion wind. However, in this case, the ion wind is sent to the filter layer behind the dust collecting electrode having the opening, and the purpose is to collect dust at a place not affected by the main gas. It is complicated and it is difficult to separate and collect the attached dust by the dry method.

  The present invention has been made in view of such circumstances, and pays attention to an ionic wind that has not been considered in the conventional electrostatic precipitator, and suppresses the separation action of the ionic wind that reduces the dust collection effect. An object of the present invention is to provide an electric dust collector capable of increasing dust collection efficiency.

In order to solve the above problems, the electrostatic precipitator according to the present invention employs the following means.
That is, the electrostatic precipitator according to one aspect of the present invention is driven in rotation by the drive unit to form a plurality of openings, and is arranged in parallel with the dust collecting electrode provided along the gas flow direction. The discharge electrode is provided with a corona discharge portion for corona discharge that protrudes toward the dust collection electrode of only one of the dust collection electrodes facing each other in the gas flow direction. It has several continuously.

By providing a plurality of openings in the dust collecting electrode, a part of the ion wind flowing from the discharge electrode toward the dust collecting electrode is allowed to escape to the back side of the dust collecting electrode. Thereby, the flow which ion wind reverses by a dust collection pole and leaves | separates can be suppressed.
The discharge electrode continuously has a plurality of corona discharge portions for corona discharge that protrude toward only one of the facing dust collection electrodes in the gas flow direction. As a result, ion wind can flow from only one corona discharge part that is continuous in the gas flow direction toward one side, so that interference of ion wind from corona discharge parts adjacent in the gas flow direction is reduced as much as possible. To increase the dust collection efficiency.
Examples of the dust collecting electrode include a discrete dust collecting electrode in which members having a plurality of rigidity are arranged in a gas flow direction at predetermined intervals. Examples of the member having rigidity include a pipe-shaped member. In addition, as another type of dust collecting electrode, for example, a flat plate dust collecting electrode in which a single plate-like body having a plurality of through holes is provided along the gas flow direction can be cited. For example, a punching metal is used as the flat dust collecting electrode.

  Furthermore, in the electric dust collector according to one aspect of the present invention, the plurality of dust collecting electrodes and the plurality of discharge electrodes are alternately arranged in a direction orthogonal to the gas flow direction, In the predetermined region, all of the corona discharge portions of the discharge electrodes protrude in the same direction.

  When a plurality of dust collecting electrodes and a plurality of discharge electrodes are alternately arranged in a direction orthogonal to the gas flow direction, all corona discharge parts are directed in the same direction in a predetermined region in the gas flow direction. Protruding. Thereby, in the whole predetermined area | region, an ionic wind will go to a uniform direction across a some dust collecting electrode, interference of an ionic wind will be suppressed, and dust collection efficiency can be improved.

  Furthermore, in the electrostatic precipitator according to one aspect of the present invention, in the downstream region downstream of the predetermined region, all of the corona discharge portions of the discharge electrodes are directed in the other direction opposite to the one direction. Protruding.

  In the downstream region downstream of the predetermined region, all the corona discharge portions protrude in the other direction opposite to the corona discharge portion in the predetermined region. Thereby, the dust collection efficiency can be further increased by changing the direction of the ion wind biased in one direction in the predetermined region in the other direction in the downstream region.

  According to the electric dust collector of the present invention, the ion wind can be prevented from separating from the dust collecting electrode, and the dust collecting efficiency can be increased.

It is the cross-sectional view which showed the electric dust collector which concerns on one Embodiment of this invention. It is the elements on larger scale which showed the AA arrow of FIG. It is the cross-sectional view which showed the modification of arrangement | positioning of a corona discharge part. It is the cross-sectional view which showed the other modification of arrangement | positioning of a corona discharge part. It is the cross-sectional view which showed the modification of the outer shape of the cross section of the pipe member of a dust collecting electrode. It is the cross-sectional view which showed the electric dust collector using a channel member. It is the cross-sectional view which showed the electric dust collector using a flat type dust collecting electrode. It is the elements on larger scale which showed the mesh belt.

  Hereinafter, an embodiment of an electrostatic precipitator according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross-sectional view of the electrostatic precipitator according to the present embodiment. In FIG. 1, the gas flow G is a horizontal flow and flows from the left side to the right side.

The electric dust collector 1 includes a plurality of dust collecting electrodes 4 arranged along the gas flow G in the casing 2, a plurality of discharge electrodes 5 arranged in parallel to the dust collecting electrode 4, and a power source ( (Not shown).
The casing 2 includes a gas inlet 2a, a main body 2b, and a gas outlet 2c. The gas flowing in from the gas inlet 2a is guided to the main body 2b and collected, and then discharged from the gas outlet 2c to the outside.

  The dust collecting electrodes 4 and the discharge electrodes 5 provided on the main body 2 b of the casing 2 are alternately arranged in a direction orthogonal to the gas flow G. The electric dust collector 1 shown in FIG. 1 is schematically shown, and the sizes and the number of the discharge electrodes 5 and the dust collecting electrodes 4 are not limited to the illustrated example.

  The dust collecting electrode 4 and the discharge electrode 5 are separated from each other and electrically insulated. The discharge electrode 5 is also insulated from the casing 2. The dust collecting electrode 4 is grounded, and a power source is connected to the discharge electrode 5 (not shown). The discharge electrode 5 is at an intermediate position between adjacent dust collecting electrodes 4.

  The dust collecting electrode 4 is a discrete dust collecting electrode in which a plurality of pipe members 4a are arranged in the flow direction of the gas flow G with a predetermined interval. Each pipe member 4a is made of metal having rigidity. Each pipe member 4a is arranged in the vertical direction (perpendicular to the paper surface) so that the axis is orthogonal to the gas flow G. By fixing each pipe member 4a arranged in the gas flow G direction to each other using a common frame, each dust collecting electrode 4 has an independent configuration.

  The discharge electrode 5 is disposed so as to be sandwiched between the dust collection electrodes 4. Each discharge electrode 5 has a mounting substrate 7 and a plurality of corona discharge portions 8. The attachment base material 7 is a rod-shaped or plate-shaped member made of a conductive material. The mounting base material 7 is disposed substantially parallel to the dust collecting electrode 4 facing the mounting base material 7.

  The corona discharge part 8 generates a corona discharge when a voltage is applied to the discharge electrode 5. The corona discharge portion 8 is a protrusion fixed to the mounting base 7 so as to protrude toward the dust collecting electrode 4 facing the tip, and has a tapered shape with a tapered tip. As shown in FIG. 2, a plurality of corona discharge portions 8 are arranged in the direction orthogonal to the gas flow G, that is, in the height direction. Each corona discharge part 8 is arranged so as to be located in the center of the adjacent pipe member 4a in the gas flow G direction. However, the position of the corona discharge part 8 in the gas flow G direction is not limited.

As shown in FIG. 1, the casing 2 is formed by dividing an upstream region S1 and a downstream region S2 in the gas flow G direction. That is, a region where the dust collection electrode 4 and the discharge electrode 5 are not provided is formed between the upstream region S1 and the downstream region S2.
The dust collection electrode 4 and the discharge electrode 5 in the upstream region S1 and the dust collection electrode 4 and the discharge electrode 5 in the downstream region S2 are arranged on the same straight line in the gas flow G direction. Has been. Note that the present invention is not limited to the dust collecting electrodes 4 and the discharge electrodes 5 being arranged on the same straight line in this way, but the dust collecting electrodes 4 and the discharge electrodes 5 in the upstream region S1. On the other hand, the dust collecting electrode 4 and the discharge electrode 5 in the downstream region S2 may be arranged so as to be shifted in a direction orthogonal to the gas flow G direction.

  All of the corona discharge portions 8 in the upstream area S1 are attached in the same direction, that is, upward in the paper surface. On the other hand, all of the corona discharge portions 8 in the downstream area S2 are attached in a direction opposite to the upstream area S1, that is, in a direction on the paper surface.

A shielding plate 3 a is fixed to the casing 2 at an upstream corner in a direction in which the corona discharge portion 8 of the upstream region S1 is directed. Further, a shielding plate 3b is fixed to the casing 2 at an upstream corner portion in the direction in which the corona discharge portion 8 of the downstream region S2 is directed.
The shielding plates 3a and 3b block the gas from flowing between the casing 2 and the dust collecting electrode 4 adjacent to the casing 2, and guide the gas to flow between the other dust collecting electrode 4 and the discharge electrode 5.
The role of the blocking plates 3a and 3b is merely an auxiliary role, and the mounting method and size thereof are not particularly limited, and the shielding plates 3a and 3b may be omitted.

Although not shown, the electric dust collector 1 is provided with a striking device for peeling off the particulate matter adhering to the dust collecting electrode 4. The hammering device has a hammer. When the hammer strikes the dust collecting electrode 4, the particulate matter adhering to the surface is removed by vibration.
In addition, the removal method of the particulate matter from the dust collecting electrode 4 is not limited to the beating using the hitting device. For example, the particulate matter may be removed from the dust collecting electrode 4 by a method of blowing gas to the particulate matter collected by the dust collecting electrode 4 or a method of irradiating a sound wave using a sonic horn. . Further, the particulate matter may be removed from the dust collecting electrode 4 by cleaning with a cleaning liquid performed in a wet type electrostatic precipitator.

Next, operation | movement of the electrostatic precipitator 1 of this embodiment is demonstrated.
In the electrostatic precipitator 1, corona discharge is generated at the tip of the corona discharge portion 8 by applying a voltage to the discharge electrode 5. Particulate matter contained in the gas stream is charged by corona discharge. According to the collecting principle of the conventional electrostatic precipitator, the charged particulate matter has been drawn to the collecting electrode 4 by the Coulomb force and collected on the collecting electrode 4. The effect of ionic wind is acting greatly.

  When corona discharge occurs, negative ions are generated near the corona discharge portion 8, and the negative ions move toward the dust collection electrode 4 by an electric field, thereby generating an ion wind. The ionic wind flowing toward the dust collecting electrode 4 acts to move the particulate matter contained in the gas flow to the vicinity of the dust collecting electrode 4. As a result, the particulate matter having a small particle diameter and not easily charged can be carried into the region where the Coulomb force acts, so that the collection efficiency is improved.

Part of the ion wind containing particulate matter and flowing toward the dust collection electrode 4 passes between the pipe members 4 a of the dust collection electrode 4.
In the upstream region S1, all of the corona discharge portions 8 are directed in one direction (upward in FIG. 1), so that the ion wind is directed in one direction, and the gas flow is indicated by arrows in the entire upstream region S1. In this way, it faces obliquely upward in FIG.
On the other hand, in the downstream region S2, all of the corona discharge portions 8 are directed in the opposite direction (downward in FIG. 1), so that the ion wind is directed in the opposite direction, and the gas flow is the entire downstream region S2. Then, as shown by the arrow, it faces diagonally downward in FIG.

According to this embodiment, there exist the following effects.
By providing a plurality of openings between the pipe members 4 a of the dust collecting electrode 4, a part of the ion wind flowing from the discharge electrode 5 toward the dust collecting electrode 4 is allowed to escape to the back side of the dust collecting electrode 4. Accordingly, it is possible to suppress a flow in which the ionic wind is reversed by the dust collecting electrode 4 and separated.
The discharge electrode 5 has a plurality of corona discharge portions 8 that protrude toward only one of the dust collecting electrodes 4 facing each other in the gas flow G direction. Thereby, since an ion wind can be made to flow only in one direction from the several corona discharge part 8 continuous in the gas flow G direction, interference of the ion wind from the corona discharge part 8 adjacent to a gas flow direction is made possible. The dust collection efficiency can be increased.

  A plurality of dust collecting electrodes 4 and a plurality of discharge electrodes 5 are alternately arranged in a direction orthogonal to the gas flow G direction, and in each of the upstream region S1 and the downstream region S2 in the gas flow G direction, The corona discharge part 8 was made to protrude in the same direction. Thereby, in each area | region S1, S2, the ionic wind will go to a uniform direction across the some dust collection electrode 4, the interference of ionic wind is suppressed, and dust collection efficiency can be improved. .

  In the downstream region S2 downstream of the upstream region S1, all the corona discharge portions 8 protrude in the opposite direction to the corona discharge portion 8 in the upstream region S1. Thus, the dust collection efficiency can be further increased by changing the direction of the ion wind biased in one direction in the upstream region S1 in the other direction in the downstream region S2.

  FIG. 3 shows a modification of the direction of the corona discharge unit 8. In the embodiment shown in FIG. 1, the direction of the corona discharge portion 8 is changed between the upstream region S1 and the downstream region S2, but the present invention is not limited to this. For example, as shown in FIG. 3, the corona discharge part 8 is continuously directed in only one direction (upward in FIG. 3) over a predetermined section in the gas flow direction G (three in FIG. 3 continuously). After that, the corona discharge part 8 may be continuously provided in the opposite direction (downward in FIG. 3). Even with such an arrangement of the corona discharge part 8, it is possible to suppress the interference of the ion wind due to the influence of the adjacent corona discharge part 8, and the ions in the direction intersecting the gas flow G across the plurality of dust collecting electrodes 4. Wind can flow. Therefore, as in another modification shown in FIG. 4, two continuous corona discharge portions 8 may be alternately directed in opposite directions.

  In FIG. 5, the outer shape of the cross section of the pipe member 4a of the dust collecting electrode 4 is not limited to a circular shape. For example, as shown in FIG. 5 (a), it may be a pipe member 4b having a substantially square shape with R at its corners, and a rectangular pipe with R at its corners as shown in FIG. 5 (b). The member 4c may be used, and as shown in FIG. 5C, a channel member 4d having a substantially U-shaped concave shape may be used. That is, when the discrete dust collecting electrode 4 using a plurality of rod-shaped members is employed, the pipe members 4a, 4b, 4c and the channel member 4d have a cross-sectional secondary coefficient of a predetermined value or more so as to ensure rigidity. What is necessary is just to have the cross section made.

  FIG. 6 shows an example in which the concave channel member 4d shown in FIG. 5C is arranged. As shown in the figure, the corona discharge portion 8 is disposed so as to face the convex side of the channel member 4d. By arranging in this way, the ionic wind from the corona discharge part 8 can easily escape to the back side of the channel member 4d. Each corona discharge part 8 is arranged so as to be located in the center of the adjacent channel member 4d in the gas flow G direction. However, the position of the corona discharge part 8 in the gas flow G direction is not limited.

  FIG. 7 shows a case where the dust collection electrode 4 is formed of a flat plate 4e using a punching metal or the like instead of the discrete dust collection electrode 4 using a plurality of rod-shaped members. The flat plate 4e is uniformly formed with through holes 4e1 having substantially the same shape. The shape of the through hole 4e1 may be circular, oval or polygonal. Even in such a flat dust collecting electrode 4, the ion wind can be passed through the dust collecting electrode 4 in the direction perpendicular to the gas flow G direction as in the above-described embodiment.

  Further, as the dust collecting electrode 4, a mesh belt may be used as shown in FIG. The mesh belt has flexibility in which fine metal wires are knitted into a planar shape. The mesh belt is endlessly wound around a plurality of rotating members (rotational drive rollers), and the mesh belt is appropriately moved between the gas flow path and the outside thereof. Dust adhering to the mesh belt is removed by a brush outside the gas flow path.

DESCRIPTION OF SYMBOLS 1 Electric dust collector 2 Casing 2a Gas inlet part 2b Main-body part 2c Gas outlet part 3a, 3b Shielding board 4 Dust collection electrode 4a, 4b, 4c Pipe member 4d Channel member 4e Flat plate 5 Electrode 7 Attachment base material 8 Corona discharge part G gas flow S1 upstream region (predetermined region)
S2 Downstream area

Claims (3)

A plurality of openings, and a dust collecting electrode provided along the gas flow direction;
A discharge electrode arranged in parallel to the dust collection electrode;
With
The electric discharge device, wherein the discharge electrode has a plurality of corona discharge portions for corona discharge that protrude toward only one of the dust collection electrodes facing each other in the gas flow direction. The plurality of dust collecting electrodes and the plurality of discharge electrodes are alternately arranged in a direction perpendicular to the gas flow direction,
2. The electrostatic precipitator according to claim 1, wherein in the predetermined region in the gas flow direction, all of the corona discharge portions of the discharge electrodes protrude in the same direction.   3. The electrostatic precipitator according to claim 2, wherein all of the corona discharge portions of the discharge electrodes protrude toward another direction opposite to the one direction in a downstream region downstream of the predetermined region.

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