WO2020026369A1

WO2020026369A1 - Electrostatic precipitator

Info

Publication number: WO2020026369A1
Application number: PCT/JP2018/028776
Authority: WO
Inventors: 一隆富松; 加藤　雅也; 崇雄田中; 上田　泰稔
Original assignee: 三菱日立パワーシステムズ環境ソリューション株式会社
Priority date: 2018-08-01
Filing date: 2018-08-01
Publication date: 2020-02-06
Also published as: PL436803A1; RU2765787C1; CN112512696A

Abstract

The purpose of the present invention is to provide an electrostatic precipitator in which it is possible to enhance the collection efficiency by suppressing effects in the ionic wind that reduce the collection effectiveness of the device. This electrostatic precipitator 1 comprises plate-shaped collecting electrodes 4 (4a, 4b, 4c, 4b) which have a plurality of through-holes 6 and are arranged along the direction of gas flow, and discharging electrodes (5a, 5b, 5c) which have a plurality of corona discharge parts 8 (8a, 8b) for corona discharge respectively protruding toward the collecting electrode 4 (4a, 4b) opposite thereto and which are arranged parallel to the collecting electrodes 4 (4a, 4b, 4c, 4b), wherein the open area ratio of the collecting electrodes 4 (4a, 4b, 4c, 4b) is 10% to 70%.

Description

Electric dust collector

The present invention relates to an electric precipitator.

As a conventional electric dust collecting device, there is known an electric dust collecting device including a plate-shaped dust collecting electrode arranged in parallel along a gas flow, and a sharp discharge electrode arranged in the center thereof.

(4) In the electric dust collector, a DC high voltage is applied between the dust collecting electrode and the discharge electrode, and a stable corona discharge is applied to the discharge electrode to charge the dust in the gas flow. The conventional dust collection theory explains that the charged dust is collected by 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.

電気 By the way, the electric precipitators of

Patent Documents

1 and 2 are provided with a plurality of through holes for passing dust, and a dust collecting electrode having a closed space for collecting dust therein. In

Patent Documents

1 and 2, trapped dust is hardly re-scattered by confining dust in a closed space via the through hole.

電気 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 for collecting gas. According to Patent Document 3, by providing such a dust collecting electrode, 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. , To collect dust efficiently. In Patent Literature 3, ion wind is positively used, but the purpose of this case is to collect dust mainly in the dust 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 following well-known Deutsche equation (Equation (1)). w is a dust collecting index (moving speed of particulate matter), and f is a dust collecting area per unit gas amount.
η = 1−exp (−w × f) (1)

式 In the above equation (1), the moving speed w of the dust (particulate matter) is determined to be determined by the relationship between the Coulomb force and the viscous resistance of the gas. According to Deutsche's formula (the above formula (1)), dust moves from the discharge electrode into the electric field, and the ion wind is not directly considered in the influence on the performance. However, there is a prerequisite 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 dust collection electrode, and ionic wind causes gas turbulence, It is considered as one of the factors that make the dust concentration uniform.

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

イオン Ion wind generated at the discharge electrode flows across the gas flow toward the dust collection electrode. The ion wind that reaches the dust collection electrode reverses its flow at the dust collection electrode and changes its flow direction. This causes a spiral turbulence between the electrodes.

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

イオン However, the ion wind reversed at the dust collection electrode moves dust in a direction away from the collection electrode, which is a collecting body, and thus has an effect of obstructing dust collection.

唯一 In addition, only Patent Document 3 describes an electric precipitator in consideration of the effect of ion wind. However, in this case, the structure is such that the ion wind is sent to the filter layer behind the dust collecting electrode having an opening, and the purpose is to collect dust at a location not affected by the main gas. It was complicated, and it was difficult to separate and collect the adhered dust by the dry method.

The present invention has been made in view of such circumstances, and focuses on ion wind, which has not been considered in conventional electric dust collectors, and suppresses the departure action of ion wind to reduce the dust collection effect. It is another object of the present invention to provide an electric dust collecting device capable of improving dust collecting efficiency.

The electric dust collecting apparatus according to one aspect of the present invention has a plurality of openings, a dust collecting electrode provided along a gas flow direction, and a corona discharge projecting toward the facing dust collecting electrode. And a discharge electrode having a plurality of corona discharge portions and arranged in parallel with the dust collection electrode, wherein an aperture ratio of the dust collection electrode is 10% or more and 70% or less.

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, it is possible to suppress the flow in which the ion wind is reversed at the dust collection electrode and moves away.
As the dust collecting electrode, for example, a flat plate dust collecting electrode in which a single plate-shaped body having a plurality of through holes is provided along the gas flow direction is exemplified. For example, a punching metal is used as the flat plate dust collecting electrode. Further, as another type of dust collecting electrode, a discrete dust collecting electrode in which a plurality of members having rigidity are arranged at predetermined intervals in a gas flow direction is exemplified. Examples of the rigid member include a pipe-shaped member.
The dust collecting electrode is capable of separating and collecting dust by hammering, similar to a conventional electric dust collecting device.

と When the aperture ratio is less than 10%, the effect of suppressing the separation of the ion wind decreases. If the aperture ratio exceeds 70%, the effective dust collection area decreases, and the dust collection performance decreases. When a flat plate having a plurality of through holes is used as the dust collection electrode, if the aperture ratio is too large, the strength of the dust collection electrode is reduced. By setting the aperture ratio in the above range, the dust collection efficiency is improved while maintaining the strength of the dust collection electrode as compared with a dust collection electrode having no through hole.

In one aspect of the invention, the discharge electrodes are arranged on both sides of the dust collection electrode, respectively, and the corona discharge portion of one discharge electrode and the corona discharge portion of the other discharge electrode are arranged in a gas flow direction. It is preferable that they are arranged in a staggered manner in the intersecting direction.

By arranging the corona discharge portions in a staggered manner, ion wind is generated in the corona discharge portion on one side of the dust collection electrode, and only the electric field acts on the discharge electrode in the opposite position on the other side. As a result, dust that has passed through along with the ion wind that has passed through the through-hole can be collected near the dust collection electrode.

において In one embodiment of the present invention, it is preferable that the dust collecting electrode has a folded plate shape and has a concave portion recessed with respect to the discharge electrode.

By adopting a folded plate shape, the strength of the dust collection electrode increases and the dust collection area also increases. Further, a structure in which a later-described concave portion and a corona discharge portion are opposed to each other becomes possible, and the dust collecting property can be further improved.

In one embodiment of the present invention, the dust collection electrode has a divided structure including a plurality of recessed members, and the plurality of recessed members are combined by alternately changing the direction of the recessed portions with respect to any of the discharge electrodes. It may be.

(4) By forming the dust collecting electrode in a divided structure, it becomes easy to manufacture the dust collecting electrode.

において In one embodiment of the present invention, it is preferable that the corona discharge portion is arranged to face the concave portion.

By arranging the concave part of the dust collection electrode and the corona discharge part of the discharge electrode to face each other, the ion wind effectively acts on the dust collection electrode side in places where the speed is slower than the main gas flow, so that the dust collection Properties can be further improved.

In one embodiment of the present invention, it is preferable that the dust collecting electrode is formed by arranging a plurality of rigid members at predetermined intervals in a gas flow direction.

By forming a plurality of members having rigidity as discrete dust collecting electrodes formed by arranging the members at predetermined intervals in the gas flow direction, it is possible to obtain a dust collecting electrode capable of maintaining rigidity of a predetermined value or more even when the aperture ratio is increased. it can.

ADVANTAGE OF THE INVENTION According to the electric precipitator of this invention, compared with the case where the conventional non-porous precipitator is used, it can suppress that an ion wind separates from a precipitator, and can raise dust collection efficiency. .

2A is a cross-sectional view of the electric precipitator according to the first embodiment, and FIG. 2B is a cross-sectional view taken along line AA of FIG. It is the elements on larger scale of FIG.1 (b). It is the elements on larger scale which show an example of a dust collection electrode. (A) is a cross-sectional view of a modification of the electrostatic precipitator according to the first embodiment, (b) is an AA cut end view of (a), and (c) is a BB cut end face of (a). FIG. 3D is a sectional view taken along the line CC in FIG. (A) is a cross-sectional view of the electric precipitator according to the second embodiment, and (b) is a cross-sectional end view taken along line DD of (a). (A) is a cross-sectional view of the electric precipitator according to the third embodiment, and (b) is an EE cut end view of (a). FIG. 7 is a partially enlarged view of FIG. (A) is a cross-sectional view of the electric precipitator according to the fourth embodiment, and (b) is an FF cut end view of (a). It is a partial cross section of an electric precipitator concerning a 5th embodiment. It is a cross section of an electric precipitator concerning a 6th embodiment. It is a figure explaining the aperture ratio of FIG. It is a cross-sectional view which shows the modification of FIG. It is a cross-sectional view which shows the other modification of FIG. It is a cross-sectional view which shows the modification of the pipe member of FIG. It is the graph which showed the dust collection area ratio of 1st Embodiment with respect to the aperture ratio. It is the graph which showed the dust collection area ratio of 6th Embodiment with respect to the aperture ratio.

Hereinafter, an embodiment of the electric dust collecting apparatus and the dust collecting method according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1A is a cross-sectional view of the electric precipitator according to the present embodiment, and FIG. 1B is an AA cut end view of FIG. 1A. FIG. 2 is a partially enlarged view of FIG. In FIG. 1A, the gas flow G is a horizontal flow, and flows upward from the lower side of the drawing.

The electric dust collecting apparatus 1 includes a plurality of dust collecting electrodes 4 (4a, 4b, 4c, 4d) arranged along the gas flow G, and a plurality of discharge electrodes 5 arranged in parallel with the dust collecting electrodes 4. (5a, 5b, 5c) and a power supply (not shown). The combination of the dust collection electrode 4 (4a, 4b, 4c, 4d) and the discharge electrode 5 (5a, 5b, 5c) is arranged in the casing 2.

A plurality of shielding plates 3 are installed inside the casing 2. The shielding plate 3 blocks gas from flowing between the casing 2 and the dust collecting electrode (4a or 4d) near the casing 2, and the gas flow G flows between the dust collecting electrode 4 and the discharge electrode 5. And play a role to guide the flow.

塵 The dust collection electrode 4 and the discharge electrode 5 extend in a direction intersecting the gas flow G (perpendicular to the paper surface). The electric precipitator 1 shown in FIG. 1 is schematically shown, and the size and the number of the discharge electrodes 5 (5a, 5b, 5c) and the precipitating electrodes 4 (4a, 4b, 4c, 4d) are as follows. , Is not limited to the illustrated example.

塵 The dust collecting electrode 4 and the discharge electrode 5 are separated from each other and are 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 located at an intermediate position between the adjacent dust collection electrodes 4.

The dust collection electrode 4 (4a, 4b, 4c, 4d) is a single plate-shaped member made of a conductive material. The plate surface of the dust collection electrode 4 is disposed substantially parallel to the gas flow G direction.

塵 Each of the dust collecting electrodes 4 (4a, 4b, 4c, 4d) has a plurality of through holes 6. The arrangement and shape of the through holes 6 are not limited and can be arbitrarily changed. The shape of the through hole 6 is, for example, a circle, a long circle, or the like.

The dust collecting electrode 4 (4a, 4b, 4c, 4d) may be, for example, a metal punching metal, a metal mesh belt, or the like. FIG. 3 shows a partially enlarged view of the mesh belt. In a case where the present invention is applied to an electric dust collecting apparatus of a type in which a dust collecting pole is moved by using a rotating member (rotary driving roller), the dust collecting pole 4 may be a mesh belt. By forming the dust collecting electrode in the form of a single mesh belt, the dust can be separated and collected by a brush in combination with the endless belt system.

開口 The aperture ratio of the dust collecting electrode 4 is 10% or more and 70% or less. However, in the case of adopting a hammering method in which dust is removed by hammering the flat dust collecting electrode 4, it is necessary to secure the strength of the flat dust collecting electrode 4, so that the aperture ratio is 35%. It is preferable to set the following. Even when the dust collecting electrode 4 is a flat plate, when dust is removed by a water stream, the flat dust collecting electrode 4 does not need the strength required by the hammering method. 70% or less. The “opening ratio” is the ratio of the opening portion to the total area of each dust collecting electrode 4 when viewed from the front from the discharge electrode 5 side.

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

The corona discharge section 8 generates a corona discharge when a voltage is applied to the discharge electrode 5. The corona discharge section 8 is a projection provided on the mounting base 7 so as to project toward the dust collecting electrode 4 facing the corona discharge section 8. The projection is made of a conductive material. The protrusion has a barbed shape with a tapered tip.

The corona discharge section 8 includes a first corona discharge section 8a and a second corona discharge section 8b. The first corona discharge portions 8a and the second corona discharge portions 8b are arranged in a staggered manner in a direction T intersecting the gas flow G (a direction perpendicular to the plane of FIG. 1A, that is, a height direction of the discharge electrodes 5).

For example, as shown in FIG. 2, in a pair of discharge electrodes 5 (5b, 5c) arranged on both sides of the dust collection electrode 4c, one of the discharge electrodes 5c is on the dust collection electrode 4c side (in FIG. A first corona discharge portion 8a protruding toward the left side is provided, and a second corona discharge portion 8b protruding toward the dust collection electrode 4c side (the right side in the figure) is provided on the other discharge electrode 5b. .

The discharge electrode 5b sandwiched between the

dust collecting electrodes

4b and 4c has a first corona discharge portion 8a protruding toward one dust collecting electrode 4b and a second corona discharge portion 8b protruding toward the other dust collecting electrode 4c. Are installed on the mounting base 7. The first corona discharge portion 8a and the second corona discharge portion 8b facing in different directions are staggered in a direction T intersecting the gas flow G (a direction perpendicular to the paper surface in FIG. 1A, that is, a height direction of the discharge electrode 5). (See FIG. 1B).

In addition, the first corona discharge portion 8a and the second corona discharge portion 8b are not limited to the example of FIG. 1 but are staggered in the gas flow G direction (from the bottom to the top in FIG. 4). Is also good. FIG. 4A is a cross-sectional view of a modified example of the electric dust collector according to the present embodiment, FIG. 4B is an AA cut end view of FIG. 4A, and FIG. 4C is FIG. FIG. 4D is a sectional view taken along line BB of FIG. 4, and FIG. 4D is a sectional view taken along line CC of FIG. 4A.

The plurality of through holes 6 in the dust collecting electrode 4 may be uniformly provided in a range affected by corona discharge generated at the facing discharge electrode 5. Range affected by the corona discharge, and the distance from the projecting tip of the corona discharge portion 8 to the dust collecting electrode and L _d, the area having a spread of about 45 degrees on one side from the projecting tip (diameter 2L _d) .

The electric dust collecting device 1 may be provided with a hammering device (not shown) for separating the particulate matter attached to the dust collecting electrode 4. The hammer has a hammer, and the hammer hammers the dust collecting electrode 4 to peel off and remove the particulate matter attached to the surface by vibration.
The method of removing the particulate matter from the dust collecting electrode 4 is not limited to hammering using a hammer. For example, the particulate matter may be removed from the dust collection electrode 4 by a method of spraying a gas to the particulate matter collected by the dust collection 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 washing with a washing liquid performed in a wet type electric dust collector.

Next, the operation of the electric precipitator 1 of FIG. 1 will be described.
In the electrostatic precipitator 1, a corona discharge is generated at the tip of the corona discharge unit 8 by applying a voltage to the discharge electrode 5. The particulate matter contained in the gas stream is charged by corona discharge. According to the collecting principle of the conventional electric dust collector, the charged particulate matter is drawn to the dust collecting electrode 4 by the Coulomb force and collected on the dust collecting electrode 4, but actually, it is actually collected. The effect of the ion wind is acting greatly.

(4) 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 the electric field (E), and ion wind is generated. The ion wind flowing toward the dust collection electrode 4 acts to move the particulate matter contained in the gas flow to the vicinity of the dust collection electrode 4. Thereby, the particulate matter having a small particle diameter and being hardly charged can be carried into the region where the Coulomb force acts, so that the collection efficiency is improved.

(2) A part of the ion wind including the particulate matter and flowing toward the dust collection electrode 4 passes through the through hole 6 of the dust collection electrode 4 as shown by a thin arrow in FIG. By allowing a part of the ion wind to pass, the reversal of the ion wind at the dust collection electrode 4 is suppressed, and the occurrence of turbulence can be reduced. Thereby, the separation of the particulate matter from the vicinity of the dust collection electrode 4 can be prevented, and the re-scattering of the particulate matter collected by the dust collection electrode 4 can be reduced.

In the pair of discharge electrodes 5 arranged on both sides of the dust collecting electrode 4, the first corona discharge portion 8a and the second corona discharge portion 8b are staggered on opposing surfaces, so that ion wind interferes. Thus, the particulate matter can be effectively moved to the vicinity of the dust collection electrode 4.

In the discharge electrode 5 on one surface side of the dust collecting electrode 4, the corona discharge unit 8 generates ion wind toward the dust collecting electrode 4, but at a position opposite to the other surface side of the dust collecting electrode 4. No ion wind is generated, and a Coulomb force generated by the electric field (E) exerts a force for moving dust to the dust collection electrode (see FIG. 2). Therefore, the particulate matter that has passed through the through-hole 6 due to the ionic wind stays near the back surface of the dust collecting electrode 4 due to the electric field (E) and is collected by the dust collecting electrode 4 due to Coulomb force. The particulate matter not collected here flows along the main gas flow and is efficiently collected in the next stage.

[Second embodiment]
The electric dust collector according to the present embodiment has the same configuration as that of the first embodiment except that the shape of the dust collecting electrode is different. FIG. 5A is a cross-sectional view of the electric precipitator 10 according to the present embodiment, and FIG. 5B is a cross-sectional end view taken along line DD of FIG. 5A.

The electric precipitator 10 is arranged in parallel with the plurality of precipitating poles 14 (14a, 14b, 14c, 14d) arranged along the gas flow G and the precipitating poles 14 (14a, 14b, 14c, 14d). , A plurality of discharge electrodes 5 (5a, 5b, 5c) and a power supply (not shown). The combination of the dust collection electrode 14 (14a, 14b, 14c, 14d) and the discharge electrode 5 (5a, 5b, 5c) is arranged in the casing 2.

The dust collection electrodes 14 (14a, 14b, 14c, 14d) are plate-like members made of conductive materials. Each of the dust collection electrodes 14 has a folded plate shape having the valleys 11. The valley 11 has a structure in which valleys or ridges are alternately repeated in the gas flow direction. The valleys are concave with respect to the facing discharge electrode 5, and the peaks protrude with respect to the discharge electrode. In FIG. 5, a connecting portion between the valley and the peak is referred to as an inclined portion 12. The mountain valley portion 11 can be formed by rolling a plate-shaped member.

塵 Each of the dust collecting electrodes 14 (14a, 14b, 14c, 14d) has a plurality of through holes 16. Each dust collecting electrode (14a, 14b, 14c, 14d) is, for example, a metal punching metal. The through-hole 16 may be provided in a range that is not restricted by the structure, for example, in a linear portion of the inclined portion 12.

The aperture ratio of the dust collection electrode 14 is 10% or more and 70% or less. However, in the case of adopting a hammering method in which dust is removed by hammering the flat dust collecting electrode 4, it is necessary to secure the strength of the flat dust collecting electrode 4, so that the aperture ratio is 35%. It is preferable to set the following. Even when the dust collecting electrode 4 is a flat plate, when dust is removed by a water stream, the flat dust collecting electrode 4 does not need the strength required by the hammering method. 70% or less.
In FIG. 5, the through-hole 16 is provided only in the flat portion of the valley portion 11, and is not provided in the inclined portion 12.

The depth (H) of the valley and valley 11, the distance (X) between the top of the valley and the top of the valley in the valley 11, and the width (Y) of the inclined portion 12 when viewed from the discharge electrode side in front are, for example, 4, H = 30 mm, X = 90 mm, and Y = 30 mm.

塵 The dust collecting poles 14 (14a, 14b, 14c, 14d) have their longitudinal axes arranged substantially parallel to the gas flow direction. The peaks or valleys of the peaks and valleys 11 are preferably arranged so as to face the corona discharge unit 8 provided on the discharge electrode 5.

According to the present embodiment, since the dust collecting electrode 14 is formed in a folded plate shape, ionic wind flowing from the discharge electrode 5 toward the dust collecting electrode 14 can be guided toward the through hole 16. Thereby, the passage of the ion wind through the through hole 16 can be promoted, the reversal at the dust collecting electrode can be suppressed, and the dust collecting efficiency can be improved. When the valley portion of the dust collection electrode 14 and the corona discharge portion 8 of the discharge electrode 5 are arranged to face each other, the ion wind is effectively directed to the dust collection electrode 14 side in the valley portion where the velocity is lower than the flow of the main gas. And the dust collecting property can be further improved.

[Third embodiment]
The electrostatic precipitator according to the present embodiment has the same configuration as the second embodiment except that the arrangement of the corona discharge part of the discharge electrode is different. FIG. 6A is a cross-sectional view of the electric precipitator 20 according to the present embodiment, and FIG. 6B is an EE cut end view of FIG. 6A. FIG. 7 is a partially enlarged view of FIG.

The electric dust collecting device 20 includes a plurality of dust collecting electrodes 14 (14a, 14b, 14c, 14d) arranged along the gas flow G, and a plurality of discharge electrodes arranged in parallel with each dust collecting electrode 14. 25 (25a, 25b, 25c) and a power supply (not shown).

The discharge electrodes 25 (25a, 25b, 25c) each have a mounting base material 27 and a plurality of corona discharge portions 28 (28a or 28b). The mounting base 27 is the same as in the first and second embodiments. The corona discharge unit 28 generates a corona discharge when a voltage is applied to the discharge electrode 25. The corona discharge portion 28 is a projection provided on the mounting base 27 so as to project toward the dust collecting electrode 14 facing the corona discharge portion 28. The projection is made of a conductive material. The protrusion has a barbed shape with a tapered tip.

には The plurality of corona discharge units 28 include a first corona discharge unit 28a and a second corona discharge unit 28b. In the present embodiment, any one of the first corona discharge portion 28a and the second corona discharge portion 28b is provided on an arbitrary mounting base material 27. The first corona discharge portion 28a and the second corona discharge portion 28b have different height positions when disposed on both sides of the dust collection electrode 14. That is, as shown in FIG. 6B, the height positions of the corona discharge portions 28 facing each other across the dust collection electrode 14 are different. Otherwise, the first corona discharge unit 28a and the second corona discharge unit 28b are the same. The “height position” is a direction T crossing the gas flow G in the plane of the plate-shaped member.

(4) The first corona discharge section 28a and the second corona discharge section 28b are staggered in a direction intersecting the gas flow G (see FIGS. 6B and 7). As described above, according to the present embodiment, the height of the corona discharge portions 28 that face each other with the dust collection electrode 14 interposed therebetween is changed so as to be staggered in the direction that intersects the gas flow G. It is possible to prevent the ion wind from interfering between the corona discharge units 28 sandwiching the 14.

[Fourth embodiment]
The electrostatic precipitator according to the present embodiment has the same configuration as the third embodiment except that the arrangement of the corona discharge part of the discharge electrode is different. FIG. 8A is a cross-sectional view of the electric precipitator 30 according to the present embodiment, and FIG. 8B is a sectional view taken along the line FF of FIG. 8A.

The electric precipitator 30 includes a plurality of precipitating poles 14 (14a, 14b, 14c, 14d) arranged along the gas flow G, and a plurality of discharge electrodes arranged in parallel with each precipitating pole 14. 35 (35a, 35b, 35c) and a power supply (not shown).

The discharge electrodes 35 (35a, 35b, 35c) each have a mounting base material 37 and a plurality of corona discharge portions 38 (38a or 38b). The mounting base 37 is the same as in the first and second embodiments. The corona discharge unit 38 generates a corona discharge when a voltage is applied to the discharge electrode 35. The corona discharge part 38 is a projection provided on the mounting base 37 so as to project toward the dust collecting electrode 14 facing the corona discharge part 38. The projection is made of a conductive material. The protrusion has a barbed shape with a tapered tip.

には The plurality of corona discharge units 38 include a first corona discharge unit 38a and a second corona discharge unit 38b. In the present embodiment, only one of the first corona discharge part 38a and the second corona discharge part 38b is disposed on the arbitrary mounting base material 37 at the point where the corona discharge part is disposed.

In FIG. 8, the first corona discharge portion 38a and the second corona discharge portion 38b have different height positions when disposed on both sides of the dust collection electrode 14. That is, as shown in FIG. 8B, the height positions of the corona discharge portions 28 that face each other across the dust collection electrode 14 are different. Otherwise, the first corona discharge unit 28a and the second corona discharge unit 28b are the same. The “height position” is a position in the direction T intersecting the gas flow G in the plane of the plate-shaped member. In addition, it is not limited to FIG. 8, and the first corona discharge portion 38a and the second corona discharge portion 38b may be at the same height position.

The first corona discharge section 38a and the second corona discharge section 38b are staggered in the gas flow direction. In the discharge electrode 35b, a second corona discharge portion 38b protruding toward the dust collection electrode 14a and a second corona discharge portion 38b protruding toward the dust collection electrode 14b are installed on the mounting base 37 in a staggered arrangement. ing.

By arranging the discharge electrodes 35b in which the corona discharge portions 38 are staggered in the gas flow direction to face the folded plate-shaped dust collection electrode 14, the corona discharge portion 38 is selectively directed toward the concave portion of the dust collection electrode 14. Can be placed. Thereby, dust collection efficiency can be further improved.

[Fifth Embodiment]
The electric dust collector according to the present embodiment has the same configuration as the fourth embodiment except that the configuration of the dust collection electrode is different. FIG. 9 is a partial cross-sectional view of the electric precipitator according to the present embodiment.

塵 The dust collecting electrode 44 (44a, 44b) of the present embodiment is composed of a plurality of concave members 41. The concave member 41 is a single plate-shaped member made of a conductive material. Each of the plurality of concave members 41 is a separate and independent member.

(4) The plurality of concave members 41 are arranged such that the direction of the concave surface is alternately changed with respect to an arbitrary discharge electrode (for example, discharge electrode 35a). Each of the plurality of concave members 41 extends in a direction intersecting the gas flow G (perpendicular to the paper surface), and is fixed to a casing (not shown in FIG. 9) at both ends in the longitudinal direction. Thus, the dust collection electrode 44 has a structure in which valleys (recesses) and ridges are alternately repeated in the gas flow direction.

凹部 The adjacent concave members may be in close contact with each other, or may be arranged at intervals. When they are arranged at intervals, a spacer may be provided between the concave members 41. Adjacent concave members need not intersect as shown in FIG.

The recess 41 has a plurality of through holes 46. The through hole 46 is provided so that the opening ratio of the dust collection electrode 14 is 10% or more and 70% or less. Here, the “opening ratio” is a ratio of the opening portion to the total area of the dust collection electrode 4 when viewed from the front from the discharge electrode 5 side. The space between the concave members is not included in the aperture ratio.

In FIG. 9, the height difference between the inside and outside of the adjacent concave material is H, the distance between the adjacent dust collection electrode and the discharge electrode is L ₂ , the shortest distance between the dust collection electrode and the discharge electrode is L _f , the tip of the projection of the corona discharge unit. the distance between and dust collecting electrode L _d, and the corona discharge unit and the first corona discharge portion pitch and the second corona discharge unit pitch / P ₁ the distance between the corona discharge unit arranged in the gas flow direction. The plurality of through holes 46 in the dust collecting electrode 44 may be uniformly provided in a range affected by corona discharge generated at the discharge electrode 35 facing the dust collecting electrode 44. Range affected by the corona discharge, and the distance from the projecting tip of the corona discharge unit 38 to the dust collection electrode 44 and L _d, the area having the spread of approximately 45 degrees to one side from the projecting tip (diameter 2L _d ).

According to the present embodiment, by forming the dust collecting electrode in a divided structure, it becomes easy to manufacture a folded plate-shaped dust collecting electrode.

[Sixth embodiment]
The electric dust collecting apparatus according to the present embodiment has the same configuration as the above-described embodiments except that the configuration of the dust collecting electrode is different.
As shown in FIG. 10, the dust collecting electrodes 64 (64a, 64b) of the electric dust collecting apparatus 60 have a plurality of pipe members 64a1, 64b1 arranged at predetermined intervals in the flow direction of the gas flow G. It is a discrete dust collection electrode. Each of the pipe members 64a1 and 64b1 is made of rigid metal. Each of the pipe members 64a1 and 64b1 is disposed such that the axis is orthogonal to the gas flow G. By fixing each of the pipe members 64a1 and 64b1 arranged in the gas flow G direction using a common frame, each of the

dust collecting electrodes

64b and 64b has an independent configuration.

コロ A corona discharge electrode 68 is provided between each of the

dust collecting electrodes

64a and 64b. Each corona discharge electrode 68 is provided with a first corona discharge section 68a and a second corona discharge section 68b. The first corona discharge section 68a discharges toward one side (upward in FIG. 10) orthogonal to the gas flow G, and the second corona discharge section 68b faces the other side (downward in FIG. 10) orthogonal to the gas flow G. To discharge. The

corona discharge portions

68a and 68b are arranged so as to be located between the adjacent pipe members 64a1 and 64b1 in the gas flow G direction. Further, the

corona discharge portions

68a and 68b are provided so as to face in opposite directions at the same position in the gas flow G direction.

(4) The aperture ratio of the

dust collecting electrodes

64a and 64b is 10% or more and 70% or less. The aperture ratio is determined as shown in FIG. That is, the aperture ratio is a ratio of the

dust collecting electrodes

64a and 64b viewed from the corona discharge electrode 68, and is represented by (Pd) / P × 100 [%]. Here, P is the pitch of the pipe members 64a1 and 64b1 in the gas flow G direction, and d is the outer diameter of the pipe members 64a1 and 64b1.

According to the present embodiment, as compared with the case of using punched metal as in the first embodiment, it is possible to maintain a rigidity equal to or higher than a predetermined value even when the aperture ratio is increased.

FIG. 12 shows a modification in which the arrangement of the

corona discharge portions

68a and 68b is different from that in FIG. As shown in FIG. 11, the first corona discharge portions 64a1 and the second corona discharge portions 64b1 may be provided alternately in the gas flow G direction.

Further, as shown in FIG. 13, only the first corona discharge portions 6a1 are provided continuously (three in FIG. 13) over a predetermined section, and thereafter, the second corona discharge portions 68b are provided continuously. It may be provided. By doing so, it is possible to suppress the interference of the ion wind due to the influence of the adjacent

corona discharge portions

68a and 68b, and to reduce the ion wind in a direction crossing the gas flow G over the plurality of

dust collection electrodes

64a and 64b. Can flow.

Also. The outer shape of the cross section of the pipe members 64a1 and 64b1 used for the

dust collecting electrodes

64a and 64b is not limited to a circular shape. For example, as shown in FIG. 14 (b), it may be a rectangle with a rounded corner, as shown in FIG. 14 (b), or a substantially U-shaped concave shape as shown in FIG. 14 (c). That is, the pipe members 64a1 and 64b1 only need to have a cross section having a quadratic coefficient of a predetermined value or more so as to secure rigidity.

Next, the grounds for setting the aperture ratio of the dust collection electrode will be described.
The electric precipitator having the configuration of the first embodiment was operated under the following conditions to collect dust on the precipitating electrode. That is, a punching metal is used as the dust collecting electrode.

(Experimental conditions)
Electrode interval (distance between dust collection electrodes): 300 mm
Voltage: 35-50kV
Current density: 0.3 to 0.8 mA / m ²
SCA (electrode area / gas amount): 5 to 30 sec / m
Dust concentration: 2-3 g / m ³ N
Dust used: fly ash (average diameter 10 μm)

Fig. 15 shows the relationship between the aperture ratio and the collection efficiency. In the figure, the horizontal axis represents the aperture ratio (%) of the dust collection electrode, and the vertical axis represents the standard value of the dust collection area ratio. The dust collection area ratio indicates the dust collection area when the same dust collection performance is exhibited when the dust collection performance when the aperture ratio is 0% is 1. Therefore, the smaller the dust collection area ratio, the higher the collection efficiency.

Curve C1 shows the dust collection area ratio when the gas flow rate is relatively large, that is, when the gas flow rate is 1 m / s or more. When the aperture ratio is 10% or more, the dust collection area ratio is reduced by about 20%, and the effect of providing the aperture is produced. The dust collection area ratio is lowest around 20%, and then gradually increases when it exceeds 30%. This is because, when the dust collection electrode is a flat plate such as a punching metal, the effect of gas flow on the surface of the dust collection electrode is greater than that of the ion wind, so even if the aperture ratio is increased, the advantage of the ion wind is lost. It is thought to be. In this case, the upper limit of the aperture ratio is determined from the strength of the dust collection electrode. That is, as shown by the curve C3, when the aperture ratio is increased, the intensity ratio of the plate-shaped dust collection electrode decreases. Here, the intensity ratio is a ratio to the intensity when the aperture ratio is 0%. When the aperture ratio becomes 35%, the intensity ratio becomes 0.5, and the intensity becomes half. Considering the case where the dust collecting electrode is hammered, it is considered that the intensity ratio decreases by 0.5. Therefore, the aperture ratio is preferably set to 35%.
Therefore, when a flat dust collecting electrode is used and hammering is performed, the aperture ratio is preferably 10% or more and 35% or less (application range I).

However, when dust is removed by a water flow without hammering the dust collection electrode, there is no need to consider the strength. When the gas flow rate is less than 1 m / s and the gas flow rate is relatively small, the influence of the gas flow on the surface of the dust collection electrode is small. The dust area ratio shows a low value. That is, as shown by the curve C2, the dust collection area ratio shows a low value up to an aperture ratio of 70%. If the aperture ratio exceeds 70%, the absolute value of the dust collection area becomes smaller, so that the dust collection area ratio increases.
Therefore, in the case where a flat dust collecting electrode is used, hammering is not performed, and the gas flow rate is relatively small, the aperture ratio is preferably 10% or more and 70% or less (application range II).
When the corona current is increased, the ion wind is proportional to approximately 1/2 power of the corona current. Therefore, 1 m / s is only a guideline in relation to the above main gas velocity, and is not limited to this. is not.

FIG. 16 shows a dust collection area ratio when a discrete dust collection electrode using the pipe members 64a1 and 64b1 (see FIG. 10) as in the sixth embodiment. As shown in the figure, when the aperture ratio is 10% or more and 70% or less, the dust collection area ratio becomes 0.8 or less. Therefore, the aperture ratio is preferably 10% or more and 70% or less (application range III).

1, 10, 20, 30, 60 Electric precipitator 2 Casing 3

Shielding plates

4, 4a, 4b, 4c, 4d, 14, 14a, 14b, 14c, 14d, 44, 44a, 44b, 64a,

64b

5, 5a, 5b, 5c, 25, 25a, 25b, 25c, 35, 35a, 35b, 35c, 68

Discharge electrodes

6, 16, 46 Through

holes

7, 27, 37

Mounting bases

8, 8a, 8b, 28, 28a, 28b, 38, 38a, 38b, 68a, 68b Corona discharge section 11 Mountain valley section 12 Inclined section 41 Concave section

Claims

A plurality of openings are formed, a dust collecting electrode provided along the gas flow direction,
A discharge electrode having a plurality of corona discharge portions for corona discharge protruding toward the dust collection electrode facing each other, and a discharge electrode arranged in parallel to the dust collection electrode,
With
An electric precipitator, wherein an opening ratio of the precipitating electrode is 10% or more and 70% or less.
The discharge electrodes are respectively arranged on both sides of the dust collection electrode,
2. The electrostatic precipitator according to claim 1, wherein the corona discharge section of one discharge electrode and the corona discharge section of the other discharge electrode are arranged in a staggered manner in a direction intersecting a gas flow direction. 3.
3. The electric dust collector according to claim 1, wherein the dust collecting electrode has a folded plate shape, and has a concave portion recessed with respect to the discharge electrode. 4.
The dust collecting electrode has a divided structure including a plurality of concave materials,
The electrostatic precipitator according to claim 1 or 2, wherein the plurality of concave members are combined with any of the discharge electrodes by changing the direction of the concave portions alternately.
The electric dust collector according to claim 3 or 4, wherein the corona discharge section is disposed to face the recess.
The electric dust collecting apparatus according to claim 1 or 2, wherein the dust collecting electrode is formed by arranging a plurality of rigid members at predetermined intervals in a gas flow direction.