JP6274357B2 - Electric dust collector and exhaust gas purification system - Google Patents

Description

  The present invention relates to an electric dust collector and an exhaust gas purification system.

Electric dust collectors have been used to collect fine particles in exhaust gas in various areas such as various plants and tunnels. Conventionally, in an electrostatic precipitator in which a flat discharge electrode and a flat counter electrode are opposed to each other, the discharge electrode has a thorn-shaped protruding portion at the end like a saw blade (for example, Patent Document 1). reference). The discharge electrode generates a corona discharge between the thorn-shaped protruding portion and the counter electrode, and charges the fine particles by the corona discharge. The dust collecting electrode collects charged fine particles by Coulomb force (see, for example, Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] Japanese Patent No. 2971461

  Corona discharge is generated between the barbed protrusion of the discharge electrode and the counter electrode. Therefore, when the electrostatic precipitator is operated for a long period of time, erosion of the counter electrode may proceed at a specific spot of the counter electrode corresponding to the thorn-shaped protruding portion.

  (General Disclosure of the Invention) An electrostatic precipitator may comprise a first electrode plate and a second electrode plate. The second electrode plate may be provided to face the first electrode plate. The end portion of the second electrode plate may be located inside the end portion of the first electrode plate. The end of the second electrode plate may not have a protruding portion.

  The second electrode plate may have a flat plate shape. The second electrode plate may have a radius of curvature equal to or greater than half of the gap between the first electrode plate and the second electrode plate in all regions.

  The second electrode plate may have a flat plate shape including a straight portion and a corner portion having a radius of curvature.

  The second electrode plate may have a disk shape.

  The second electrode plate may have one or more through openings.

  The one or more through openings may include a plurality of independent through openings.

  The one or more through openings may have a central opening and a peripheral opening. The central opening may be the largest. The peripheral opening may have a smaller opening area than the central opening. The peripheral opening may be arranged around the central opening.

  The second electrode plate may have one or more through openings. At least one of the one or more through openings may have an edge protruding toward the first electrode plate.

  You may have two or more through-openings which have the edge part which protrudes toward the 1st electrode plate. The length that the edge protrudes may be different between the upstream side and the downstream side of the gas introduced into the electrostatic precipitator.

  The length from which the edge protrudes may be longer on the upstream side than on the downstream side.

  A plurality of first units each having a first electrode plate and a second electrode plate may be stacked.

  The gap length between the first electrode plate and the second electrode plate at the end in the stacking direction of the plurality of first units stacked is the first length at the center of the stack in the stacking direction of the first units. The gap length between the electrode plate and the second electrode plate may be larger.

  The electric dust collector may further include a second unit. The second unit may include a third electrode plate and a fourth electrode plate. The fourth electrode plate may be provided to face the third electrode plate. The end portion of the fourth electrode plate may be located inside the end portion of the third electrode plate. The end of the fourth electrode plate may have a protruding portion. A second unit may be provided at least at both ends in the stacking direction of the plurality of stacked first units.

  The exhaust gas purification system may include a scrubber and the electric dust collector described above. The scrubber may purify the exhaust gas. The electric dust collector may be provided upstream of the scrubber.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a perspective view which shows the structure of the electrical dust collector 200 of 1st Embodiment. It is sectional drawing which shows the structure of the electrical dust collector 200 of 1st Embodiment. FIG. 3 is a top view of an AA ′ cross section in FIG. 2. It is a figure which shows the shape of the discharge electrode 100 of 2nd Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 3rd Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 4th Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 5th Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 6th Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 7th Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 8th Embodiment. It is sectional drawing seen from the side surface direction of the discharge electrode 100 of 8th Embodiment. It is a figure which shows the shape of the discharge electrode 100 of 9th Embodiment. It is sectional drawing seen from the side surface direction of the discharge electrode 100 of 9th Embodiment. It is a perspective view which shows the structure of the electrical dust collector 200 of 10th Embodiment. It is a perspective view which shows the structure of the electrical dust collector 200 of 11th Embodiment. It is a perspective view which shows the structure of the electrostatic precipitator 200 of 12th Embodiment. It is a perspective view which shows the structure of the electrostatic precipitator 200 of 13th Embodiment. It is a figure which shows the outline | summary of the exhaust gas purification system.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  In this specification, technical matters will be described using orthogonal coordinate axes of the X axis, the Y axis, and the Z axis. The Cartesian coordinate axis only specifies the relative position of the component, and does not limit a specific direction. For example, the Z axis does not limit the height direction with respect to the ground. Note that the + Z-axis direction and the −Z-axis direction are directions opposite to each other. When the Z axis direction is described without describing positive and negative, it means a direction parallel to the + Z axis and the −Z axis. In the present specification, the “straight line” has an infinite curvature radius.

  FIG. 1 is a perspective view illustrating a configuration of an electric dust collector 200 according to the first embodiment. The electric dust collector 200 collects fine particles in the exhaust gas. The fine particles are soot and dust. The electric dust collector 200 includes a counter electrode 10-1 and a discharge electrode 100. The counter electrode 10-1 as the first electrode plate is an electrode plate having a GND potential and is also referred to as a GND electrode. The discharge electrode 100 as the second electrode plate is a high potential electrode plate. The discharge electrode 100 is provided to face the counter electrode 10-1.

  The electrostatic precipitator 200 of this example includes a counter electrode 10-2 in addition to the counter electrode 10-1 and the discharge electrode 100. The counter electrode 10-1 and the counter electrode 10-2 are arranged so as to sandwich the discharge electrode 100. Thereby, the corona discharge 2 can be generated at the end portions 102 on both surfaces of one discharge electrode 100. However, unlike the present example, the electrostatic precipitator 200 may be configured with only the counter electrode 10-1 and the discharge electrode 100.

  The counter electrode 10-1 and the discharge electrode 100 are set such that the gap length in the Z direction from the discharge electrode 100 to the counter electrode 10-1 is equal to the gap length in the Z direction from the discharge electrode 100 to the counter electrode 10-2. , And the counter electrode 10-2 may be stacked in the Z direction. The counter electrode 10-1, the counter electrode 10-2, and the discharge electrode 100 may be arranged in parallel to the XY plane.

The counter electrode 10-1 and the counter electrode 10-2 (hereinafter may be referred to as the counter electrode 10) and the discharge electrode 100 have a flat plate shape. The thickness of the counter electrode 10 and the discharge electrode 100 may be 1 mm or more and 2 mm or less. The plate areas of the counter electrode 10 and the discharge electrode 100 may be 0.3 m ² or more and 3 m ² or less. For example, the counter electrode 10 and the discharge electrode 100 are flat plates of about 1 m × 1 m. However, the area of the discharge electrode 100 is smaller than the area of the counter electrode 10. The material of the counter electrode 10 and the discharge electrode 100 may be a stainless steel material such as SUS304 in JIS standards.

  The counter electrode 10 of this example is rectangular. The counter electrode 10 of this example has an end 12. The end 12 includes four rectangular sides 14. Here, “end part” means an end part in a direction parallel to the XY plane. However, unlike this example, the counter electrode 10 may have any shape such as a polygon, a circle, and an ellipse. The discharge electrode 100 of this example has a shape that can be approximated by a rectangle. The discharge electrode 100 has an end 102. The end portion 102 of the discharge electrode 100 is located inside the end portion 12 of the counter electrode 10. As shown in FIG. 1, the end portion 102 of the discharge electrode 100 does not include a protruding portion such as a thorn shape.

  A negative high voltage is applied to the discharge electrode 100 of this example by the DC power supply 20. The counter electrode 10 is grounded. As a result, a high electric field region is formed between the discharge electrode 100 and the counter electrode 10.

  Unlike this example, when the discharge electrode 100 has a protruding portion such as a thorn shape, the generation position of the corona discharge 2 is easily fixed at a position immediately below or immediately above the protruding portion. When the electric dust collector 200 is operated for a long period of time, fine particles such as dust are likely to be locally deposited on the counter electrode 10 at a position immediately below or immediately above the protruding portion of the discharge electrode 100. The deposition of fine particles shortens the gap length between the discharge electrode 100 and the counter electrode 10. As a result, in the portion where the gap length is shortened, the electric field is higher than in other portions, and the electric field required for the transition to spark (spark discharge) is likely to be exceeded. When a spark occurs, the counter electrode 10 may be easily eroded.

  Further, when the charged fine particles are attracted and deposited on the counter electrode 10 having different potentials, reverse discharge (back discharge) occurs. When the generation position of the corona discharge 2 is fixed and the charged fine particles are locally deposited at a fixed position, reverse discharge is generated at the fixed position. If the reverse discharge is constantly generated at a certain position, the counter electrode 10 may be partially damaged. In order to suppress such a state, it is necessary to periodically clean the discharge electrode 100 and the counter electrode 10 to remove the fine particles, which increases the maintenance burden.

  On the other hand, according to this example, since there is no projecting portion of the discharge electrode 100, the generation position of the corona discharge 2 is not fixed to a specific spot. Therefore, the corona discharge 2 can be generated over the entire linear area corresponding to the side of the end portion 102 of the discharge electrode 100. Even if the corona discharge 2 is formed in a spot shape, the spot of the corona discharge 2 is not fixed in one place and can move in the area on the line. Therefore, the erosion of the counter electrode 10 can be prevented from proceeding locally. Further, even if the electrostatic precipitator 200 is operated for a long period of time, it is possible to prevent fine particles such as dust from being locally deposited on the discharge electrode 100 and the counter electrode 10. As a result, it is possible to prevent the gap length between the discharge electrode 100 and the counter electrode 10 from being changed due to the deposition of fine particles, so that the occurrence of sparks can be suppressed. Moreover, since fine particles are not deposited locally, the influence of reverse discharge can be reduced.

  FIG. 2 is a cross-sectional view showing the configuration of the electric dust collector 200 of the first embodiment. Due to the corona discharge 2, the fine particles in the exhaust gas are negatively charged between the discharge electrode 100 and the counter electrode 10. The negatively charged fine particles are collected by the counter electrode 10 by Coulomb force.

  FIG. 3 is a top view of the AA ′ cross section in FIG. The discharge electrode 100 includes a straight portion 104 and a corner portion 106 as the end portion 102. “The case where the end portion 102 of the discharge electrode 100 does not have a protruding portion” includes a case where the end portion 102 of the discharge electrode 100 can be approximated by a polygon such as a quadrangle, a pentagon, and a hexagon. The end portion 102 of the discharge electrode 100 may have a shape in which a straight portion 104 corresponding to a polygonal side and a corner portion 106 obtained by smoothing a vertex portion with a curve are connected. The corner 106 has a radius of curvature that is at least half the gap length d between the counter electrode 10 and the discharge electrode 100. The discharge electrode 100 of this example has a radius of curvature that is at least half the gap length d in all regions.

  All the corners 106 of the discharge electrode 100 may have a shape that approximates the shape of an arc-shaped Rogowski electrode. Thereby, the electric field concentration in the corner 106 can be relaxed. The Rogowski electrode is an electrode in which a quasi-equal electric field having substantially the same magnitude of electric field is formed in the corner portion 106 and the straight portion 104. According to the discharge electrode 100 of this example, the end effect (edge effect) of the parallel plate electrode can be relaxed to form a quasi-equal electric field, and the corona discharge 2 is concentrated at one corner 106 of the discharge electrode 100. Can be prevented.

  FIG. 4 is a diagram showing the shape of the discharge electrode 100 of the second embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 of the second embodiment is the same as the electrostatic precipitator 200 of the first embodiment except for the shape of the discharge electrode 100. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals. The discharge electrode 100 of this example is rectangular. The corner 106 is not chamfered. Therefore, the manufacturing process of the discharge electrode 100 can be simplified.

  Also in this example, the end portion 102 of the discharge electrode 100 does not have a protruding portion. In this example, the end portion 102 of the discharge electrode 100 is not necessarily required to have a radius of curvature that is more than half of the gap length d in all regions. The discharge electrode 100 of this example can also reduce the phenomenon that the position where the corona discharge 2 is generated is fixed as compared with the case where the discharge electrode 100 has a protruding portion such as a thorn shape. Unlike the present example, the shape of the discharge electrode 100 may be a convex polygon such as a pentagon or a hexagon that is not chamfered.

  FIG. 5 is a diagram illustrating the shape of the discharge electrode 100 according to the third embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 according to the third embodiment is the same as the electrostatic precipitator 200 according to the first and second embodiments except for the shape of the discharge electrode 100. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  The discharge electrode 100 of this example has a disk shape. That is, the end portion 102 of the discharge electrode 100 is circular. The case where “the end portion 102 of the discharge electrode 100 does not have a protruding portion” includes a case where the end portion 102 of the discharge electrode 100 is formed with a closed curve such as a circle and an ellipse. In this example, the radius of the discharge electrode 100 is larger than the gap length d in the Z direction between the counter electrode 10 and the discharge electrode 100. Therefore, the discharge electrode 100 has a radius of curvature that is at least half the gap length d in all regions.

  According to this example, the end portion 102 of the discharge electrode 100 is formed with a curve having the same curvature radius. Thus, the resulting electric field is substantially the same regardless of the position at the end 102. Therefore, the corona discharge 2 can be generated uniformly over the entire end portion 102 of the discharge electrode 100 without being affected by the corner portion 106. Even if the corona discharge 2 is formed in a spot shape, the spot of the corona discharge 2 is not fixed in one place, but can move randomly along the circular end portion 102. Therefore, the occurrence of sparks can be suppressed and erosion of the discharge electrode 100 can be delayed.

  FIG. 6 is a diagram showing the shape of the discharge electrode 100 of the fourth embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 of the fourth embodiment is the same as the electrostatic precipitator 200 of the first embodiment except that the discharge electrode 100 has a through opening 110. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  The edge 112 of the through opening 110 may have a polygonal shape with a chamfered corner. The edge portion 112 includes a straight edge portion 114 corresponding to four sides of a rectangular shape, and a corner edge portion 116 in which a vertex portion is smoothed with a curve. The corner edge 116 has a radius of curvature that is at least half the gap length d between the counter electrode 10 and the discharge electrode 100. Accordingly, the discharge electrode 100 of this example has a radius of curvature that is not less than half of the gap length d in all regions including not only the end portion 102 but also the central region including the edge 112 of the through opening 110.

  In this example, when a high electric field region is formed between the discharge electrode 100 and the counter electrode 10, the corona discharge 2 is generated not only at the end portion 102 of the discharge electrode 100 but also at the edge portion 112 of the through opening 110. Can be made. Therefore, by using the discharge electrode 100 having the through opening 110, the number of locations where the corona discharge 2 is generated can be increased as compared to the case of using the discharge electrode 100 having no through opening 110. Therefore, in this example, it is possible to improve the dust collection amount (dust collection efficiency) per area of the electric dust collector 200 as compared with the first to third embodiments.

  FIG. 6 shows a case where both the end portion 102 of the discharge electrode 100 and the edge portion 112 of the through opening 110 have a polygonal shape with a chamfered corner portion. However, the discharge electrode 100 of this example is not limited to this case, and may have a through opening 110 having a shape different from the shape of the end portion 102 of the discharge electrode 100.

  FIG. 7 is a diagram showing the shape of the discharge electrode 100 of the fifth embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 according to the fifth embodiment is the same as the electrostatic precipitator 200 according to the third embodiment except that the discharge electrode 100 has a through opening 110. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  In this example, the edge 112 of the through opening 110 is circular. Unlike this example, the edge 112 of the through opening 110 may have an elliptical shape or other shapes. In this example, by using the discharge electrode 100 having the through opening 110, the number of locations where the corona discharge 2 is generated can be increased as compared with the case of using the discharge electrode 100 having no through opening 110.

  FIG. 8 is a view showing the shape of the discharge electrode 100 of the sixth embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 of the sixth embodiment is the same as the electrostatic precipitator 200 of the fifth embodiment except that the shape of the discharge electrode 100 and the shape of the through opening 110 are different. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  The discharge electrode 100 of this example has a plurality of annular portions arranged concentrically. Specifically, the discharge electrode 100 includes a first annular part 101 and a second annular part 103 disposed inside the first annular part 101. Between the 1st ring part 101 and the 2nd ring part 103, the 1st opening part 111 which is an annular | circular shaped opening part is provided. A second opening 113, which is a circular opening, is provided inside the second annular portion 103. In other words, the discharge electrode 100 of this example includes the first opening 111 and the second opening 113 as a plurality of independent through openings 110.

  The end portion 102 of the first annular portion 101 in this example corresponds to the outer periphery of the first annular portion 101 and forms the end portion 102 of the discharge electrode 100. The outer periphery of the first annular portion 101 has a radius that is at least half the gap length d. A first edge 115 that is an edge of the first opening 111 corresponds to the inner periphery of the first annular part 101 and the outer periphery of the second annular part 103. The inner circumference of the first annular portion 101 and the outer circumference of the second annular portion 103 have a radius that is at least half the gap length d. A second edge 117 that is an edge of the second opening 113 corresponds to the inner periphery of the second annular part 103. The inner circumference of the second annular portion 103 also has a radius that is at least half the gap length d. Therefore, the discharge electrode 100 of the present example also has a radius of curvature that is half or more of the gap length d in all regions including not only the end portion 102 but also the central region.

  The discharge electrode 100 of this example includes a plurality of independent through openings 110. Thereby, the location where the corona discharge 2 is generated can be increased as compared with the case where the number of the through openings 110 is one.

  FIG. 9 is a diagram showing the shape of the discharge electrode 100 of the seventh embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 according to the seventh embodiment is the same as the electrostatic precipitator 200 according to the fourth embodiment except that the shape of the discharge electrode 100 and the shape and number of the through openings 110 are different. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  The discharge electrode 100 of this example has a plurality of independent through openings 110. The through opening 110 may have a central opening 140 and a plurality of peripheral openings 146. In this example, one central opening 140 and four peripheral openings 146 are provided. The central opening 140 has the largest opening area among the plurality of through openings 110. Each peripheral opening 146 has an opening area smaller than that of the central opening 140. Each peripheral opening 146 is disposed around the central opening 140.

  In this example, the center edge 122 that is the edge of the center opening 140 has a circular shape. The peripheral edge 123, which is the edge of the peripheral opening 146, has a polygonal shape with a smoothed vertex. However, the shapes of the central edge 122 and the peripheral edge 123 are not limited to this case. The discharge electrode 100 has a radius of curvature equal to or more than half of the gap length d in all regions including not only the end portion 102 but also the central edge portion 122 and the peripheral edge portion 123.

  In general, the electric field concentrates at the end portion 102 of the discharge electrode 100, and the electric field hardly concentrates at the central portion inside the discharge electrode 100. Therefore, a region that is not a high electric field is widened in the central portion inside the discharge electrode 100. However, according to the discharge electrode 100 of this example, the central opening 140 inside the discharge electrode 100 is made larger than the peripheral opening 146. As a result, the electric field strength is increased at the central edge 122 that is the edge of the central opening 140, and the corona discharge 2 can be generated also at the central part of the discharge electrode 100.

  FIG. 10 is a diagram showing the shape of the discharge electrode 100 of the eighth embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 according to the eighth embodiment is the same as the electrostatic precipitator 200 according to the fourth embodiment except for the shape and number of the through openings 110 and the protrusion of the edge 112 of the through openings 110. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  The discharge electrode 100 of this example has a total of four through-openings 110 arranged in 2 rows and 2 columns on the XY plane. However, the number of through openings 110 is not limited to this case, and may be different from the present example. The discharge electrode 100 of this example has a radius of curvature that is not less than half of the gap length d not only in the end portion 102 of the discharge electrode 100 but also in all regions including the edge portion 112 of the through opening 110.

  FIG. 11 is a cross-sectional view of the discharge electrode 100 according to the eighth embodiment viewed from the side surface direction. Specifically, FIG. 11 is a cross-sectional view showing a BB ′ cross section in FIG. In the discharge electrode 100 of the present example, the through opening 110 has an edge 112 that protrudes toward the counter electrode 10. The protruding length of the edge 112 is q.

  In this example, the edge part 112 of the some through-opening part 110 protrudes. However, unlike this example, at least one of the plurality of through openings 110 may have an edge 112 protruding toward the counter electrode 10. Further, one through opening 110 may be provided, and one through opening 110 may have an edge 112 protruding toward the counter electrode 10. The discharge electrode 100 may be formed by machining such as pressing so that the edge 112 of the through opening 110 protrudes. According to the discharge electrode 100 of this example, the corona discharge 2 can be easily generated as compared with the case where the edge 112 does not protrude.

  FIG. 12 is a view showing the shape of the discharge electrode 100 of the ninth embodiment. 3 is a top view of the AA ′ cross section in FIG. The electrostatic precipitator 200 according to the ninth embodiment is different from the electrostatic precipitator 200 according to the eighth embodiment in that the protruding length of the edge 112 of the through opening 110 differs depending on the position in the X direction, and the through opening 110 The edge 112 is the same except that the apex is not rounded. However, the edge 112 of the through opening 110 may be chamfered at the apex. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals. The discharge electrode 100 of this example has a total of nine through-openings 110 arranged in 3 rows and 3 columns on the XY plane. However, the number of through openings 110 is not limited to this case, and may be different from the present example.

  FIG. 13 is a cross-sectional view of the discharge electrode 100 according to the ninth embodiment viewed from the side surface direction. Specifically, FIG. 13 is a cross-sectional view showing a CC ′ cross-section in FIG. The exhaust gas introduced into the electric dust collector 200 flows in the X direction. The discharge electrode 100 of this example has a plurality of through-openings 100 each having an edge 112 protruding toward the counter electrode 10. In the discharge electrode 100 of this example, the protruding length of the edge 112 of the through opening 110 is different between the upstream side and the downstream side of the exhaust gas. Thereby, the ease of generating the corona discharge 2 can be changed between upstream and downstream of the exhaust gas.

  In this example, three rows of through openings 110 are arranged along the X direction. The length by which the edge 112 of the through opening 110 protrudes is q1 upstream, q2 in the middle stream, and q3 downstream. As shown in FIG. 13, q1 is the longest, q3 is the shortest, and q2 is a length between q1 and q3. That is, the length from which the edge 112 protrudes is longer on the upstream side than on the downstream side.

  By making the length from which the edge 112 protrudes longer on the upstream side than on the downstream side, the corona discharge 2 can be more easily generated on the upstream side than on the downstream side. As a result, the upstream region is more likely to collect dust than the downstream region. The concentration of the fine particles contained in the exhaust gas is highest in the upstream region, and decreases as it goes to the downstream region. Therefore, according to this example, dust can be efficiently collected on the upstream side where the concentration of the fine particles is higher than that on the downstream side.

  However, unlike the present example, the downstream side of the protruding length of the edge 112 of the through opening 110 can be made longer than the upstream side to improve the dust collection performance on the downstream side. Thereby, it is possible to prevent the fine particles from being rapidly deposited on the upstream side, and to reduce the uneven deposition of the fine particles on the upstream side and the downstream side. Therefore, an increase in maintenance burden for removing fine particles can be suppressed.

  FIG. 14 is a perspective view showing the configuration of the electric dust collector 200 of the tenth embodiment. The electrostatic precipitator 200 of this example has a configuration in which a plurality of first units 210 each having the counter electrode 10 and the discharge electrode 100 are stacked. In other words, the electrostatic precipitator 200 of this example has redundancy vertically. One counter electrode 10 and one discharge electrode 100 constitute one first unit 210. In this example, the gap lengths between adjacent electrodes may all be the same.

  In this example, the counter electrode 10-1 and the discharge electrode 100-1 constitute one first unit 210. Similarly, the counter electrode 10-2 and the discharge electrode 100-2 constitute one first unit 210. The counter electrode 10-3 and the discharge electrode 100-3 constitute one first unit 210. In this example, three first units 210 are stacked in the Z direction. However, the number of stacked first units 210 is not limited to this case, and the number of stacked layers may be four or more.

  In this example, of the discharge electrode 100-1, the discharge electrode 100-2, and the discharge electrode 100-3, the single counter electrode 10-4 with respect to the discharge electrode 100-3 positioned at the upper end in the stacking direction. Are arranged opposite to each other. The single counter electrode 10-4 may be omitted.

  The counter electrode 10-1 to 10-4 (hereinafter may be referred to as the counter electrode 10) may be the counter electrode 10 described in the first to ninth embodiments. The discharge electrode 100-1 to the discharge electrode 100-3 (hereinafter sometimes referred to as the discharge electrode 100) may be the discharge electrode 100 described in the first to ninth embodiments. Therefore, detailed description of the counter electrode 10 and the discharge electrode 100 is omitted.

  According to this example, since a plurality of the first units 210 are stacked, the dust collection efficiency can be improved as compared with the case of one unit. Even when a plurality of first units are stacked, each discharge electrode 100 constituting the first unit 210 does not have a protruding portion such as a thorn shape. Therefore, the generation position of the corona discharge 2 can be prevented from being fixed.

  FIG. 15 is a perspective view showing the configuration of the electric dust collector 200 of the eleventh embodiment. The configuration of the electrostatic precipitator 200 of this example is different from that of the electrostatic precipitator 200 of the present example, except that the gap length between the counter electrode 10 and the discharge electrode 100 differs depending on the position of the first unit 210 in the stacking direction. The configuration is the same as that of the electric dust collector 200 of the tenth embodiment. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  In this example, the stacking direction of the first units 210 is the Z direction. Among the discharge electrodes 100-1 to 100-3, the discharge electrode 100-3 is located at the upper end in the Z direction. The discharge electrode 100-3 is paired with the counter electrode 10-3. The counter electrode 10-3 and the discharge electrode 100-3 constitute a first unit 210. In this example, the gap length d2 between the counter electrode 10-3 and the discharge electrode 100-3 means the gap length between the counter electrode 10-3 and the discharge electrode 100-3 at the upper end in the Z direction. .

  On the other hand, the gap length d1 between the counter electrode 10-2 and the discharge electrode 100-2 means the gap length between the counter electrode 10-3 and the discharge electrode 100-3 at the center in the Z direction. In this example, the gap length d2 between the counter electrode 10-3 and the discharge electrode 100-3 is larger than the gap length d1 between the counter electrode 10-2 and the discharge electrode 100-2.

  In this example, the discharge electrode 100-1 is located at the lower end in the Z direction among the discharge electrodes 100-1 to 100-3. The gap length between the counter electrode 10-1 and the discharge electrode 100-1 at the lower end in the stacking direction of the plurality of first units 210 stacked may also be d2. Therefore, in this example, the gap length d2 at the upper end portion and the lower end portion in the Z direction is larger than the gap length d1 at the center portion in the Z direction. However, unlike this example, the gap length may be larger at either the upper end or the lower end in the Z direction than at the center.

  In this example, the respective gap lengths between the discharge electrode 100 and the two adjacent counter electrodes 10 are equal. Specifically, the gap length between the discharge electrode 100-1 and the counter electrode 10-1 is equal to the gap length between the discharge electrode 100-1 and the counter electrode 10-2, and is d2. The gap length between the discharge electrode 100-2 and the counter electrode 10-2 is equal to the gap length between the discharge electrode 100-2 and the counter electrode 10-3, and is d1. The gap length between the discharge electrode 100-3 and the counter electrode 10-3 is equal to the gap length between the discharge electrode 100-3 and the counter electrode 10-4, and is d2.

  However, unlike this example, the gap lengths between the discharge electrode 100 and the two adjacent counter electrodes 10 may be different from each other. Specifically, the gap length between the counter electrode 10 on the side close to the end in the Z direction and the discharge electrode 100 among the two adjacent counter electrodes 10 may be increased.

  From the viewpoint of making the gap length near the lower end in the Z direction larger than the gap length in the central portion, the gap length between the discharge electrode 100-1 and the counter electrode 10-1 is set to the discharge electrode 100-1 and the counter electrode. It may be larger than the gap length between 10-2. From the viewpoint of making the gap length near the upper end in the Z direction larger than the gap length in the central portion, the gap length between the discharge electrode 100-3 and the counter electrode 10-4 is set to the discharge electrode 100-3 and the counter electrode. It may be larger than the gap length between 10-3.

  In this example, the case where three first units 210 are stacked has been described. However, unlike the present example, four or more first units 210 may be stacked. In this case, the gap length between the counter electrode 10 and the discharge electrode 100 may be gradually increased from the center in the Z direction toward the upper end or the lower end.

  When a plurality of first units 210 are stacked to form a stacked structure, exhaust gas hardly flows at the end of the first unit 210 in the stacking direction. However, in the electric dust collector 200 of this example, it is possible to facilitate dust collection by widening the gap length at the end of the first unit 210 in the stacking direction.

  FIG. 16 is a perspective view showing the configuration of the electrostatic precipitator 200 of the twelfth embodiment. The electric dust collector 200 of this example is provided with the second unit 220 at least at both ends in the Z direction. Except for this point, the configuration of the electrostatic precipitator 200 of this example is the same as the configuration of the electrostatic precipitator 200 of the tenth embodiment. Accordingly, repeated description of other components is omitted, and similar members are described using the same reference numerals.

  In this example, a plurality of first units 210 are stacked at the center in the Z direction. In this example, two first units 210 are stacked. However, unlike this example, three or more first units 210 may be stacked. The structure of the first unit 210 is the same as that of the tenth embodiment. On the other hand, the second unit 220 is provided at least at both ends in the Z direction.

  At the lower end in the Z direction, the second unit 220 includes an end counter electrode 190-1 and a protruding discharge electrode 180-1. The end counter electrode 190-1 as the third electrode plate is an electrode plate having a GND potential and is also referred to as a GND electrode. The protruding discharge electrode 180-1 as the fourth electrode plate is a high potential electrode plate. The protruding discharge electrode 180-1 is provided to face the end counter electrode 190-1. The protruding discharge electrode 180-1 and the end counter electrode 190-1 may be arranged in parallel to the XY plane.

  The end 182 of the protruding discharge electrode 180-1 is located inside the end 192 of the end counter electrode 190-1. Here, the end portion 182 means an end portion in a direction parallel to the XY plane. A negative high voltage is applied to the protruding discharge electrode 180-1 of this example by the DC power supply 20. The end counter electrode 190-1 is grounded.

  As shown in FIG. 16, the end portion 182 of the protruding discharge electrode 180-1 has a protruding portion 184. The protruding portion 184 may have a triangular shape projected onto the XY plane. The protruding portion 184 of this example has a thorn shape or a saw blade shape. A plurality of protruding portions 184 are provided along the end portion 182. The protruding portion 184 may have a protruding length of about 1 mm to about 5 mm. The pitch may be determined such that 3 to 5 protrusions 184 are provided per 1 cm. In the end portion 182 of the protruding discharge electrode 180-1, the protruding portion 184 may be provided along all sides, or the protruding portion 184 may be provided only along a specific side.

  At the upper end in the Z direction, the second unit 220 includes an end counter electrode 190-2 and a protruding discharge electrode 180-2. The end counter electrode 190-2 is a third electrode plate, and the protruding discharge electrode 180-2 is a fourth electrode plate. The configuration and applied voltage of the second unit 220 at the upper end in the Z direction may be the same as those of the second unit 220 disposed at the lower end.

  In this example, one second unit 220 is provided at each end in the Z direction. However, unlike the present example, a plurality of second units 220 may be provided at the upper and lower ends in the Z direction. However, the first unit 210 is stacked at the center in the stacking direction. It is desirable that the number of stacked second units 220 does not exceed the number of stacked first units 210.

  When a plurality of units are stacked to form a stacked structure, exhaust gas hardly flows at the end of the unit stacking method, and therefore the amount of deposits such as fine particles is small compared to the central portion of the stacked structure. Therefore, at the end of the stacking method, even if the protruding discharge electrode 180 having the conventional thorn-shaped protruding portion 184 is used, the possibility of the occurrence of sparks due to the deposit is higher than that in the central portion of the stacked structure. Low. Therefore, the first unit 210 without the thorn-shaped projecting portion 184 is used at the central portion in the stacking direction while using the protruding discharge electrode 180 having the conventional thorn-shaped projecting portion 184 at least at both ends in the stacking direction. Stacking can actively reduce the occurrence of sparks.

  FIG. 17 is a diagram illustrating an electrostatic precipitator 200 according to the thirteenth embodiment. The electrostatic precipitator 200 of the thirteenth embodiment is the same as the electrostatic precipitator 200 of the first to twelfth embodiments, except that a positive high voltage is applied to the discharge electrode 100 by the DC power supply 20. In the first to twelfth embodiments, the counter electrode 10 (or the end counter electrode 190) is grounded, and a negative high voltage is applied to the discharge electrode 100. On the other hand, in this embodiment, a positive high voltage is applied instead of a negative high voltage in the first to twelfth embodiments.

  Even when a positive high voltage is applied to the discharge electrode 100 by the DC power source 20, since the end portion 102 of the discharge electrode 100 does not have a protruding portion, the position where the corona discharge is generated is fixed directly below or immediately above the protruding portion. Can be prevented. Thereby, it can suppress that a counter electrode is eroded.

  FIG. 18 is a diagram showing an outline of the exhaust gas purification system 400. The exhaust gas purification system 400 removes harmful substances such as sulfur components contained in exhaust gas discharged from a vehicle engine or the like. The exhaust gas purification system 400 includes an electric dust collector 200, a scrubber 300, and a pumping pump 350. The electric dust collector 200 is provided upstream of the scrubber 300. Exhaust gas is introduced into the scrubber 300 from the electric dust collector 200 through the exhaust gas introduction pipe 306. As the electrostatic precipitator 200, the electrostatic precipitator 200 of the first to thirteenth embodiments is used.

  The scrubber 300 includes a reaction tower 302, a nozzle 304, and an exhaust gas introduction pipe 306. The reaction tower 302 has an internal space extending in the height direction. In this example, the height direction refers to a direction extending from the bottom side 308 where the exhaust gas is introduced into the reaction tower 302 to the upper side 310 where the exhaust gas is discharged.

  In the scrubber 300, the exhaust gas introduction pipe 306 is located near the bottom side 308 of the reaction tower 302. The exhaust gas introduction pipe 306 may be provided so that the exhaust gas introduced from the exhaust gas introduction pipe 306 spirally turns along the inner side surface of the reaction tower 302. The radius of the reaction tower 302 may be not less than 0.3 m and not more than 10 m.

  A cleaning water pipe 312 through which cleaning water flows is disposed inside the scrubber 300. In this example, a washing water pipe 312 is disposed near the upper side 310 of the reaction tower 302. The washing water pipe 312 in this example conveys washing water in a direction perpendicular to the height direction of the reaction tower 302. The cleaning water is supplied from the pumping pump 350 to the cleaning water pipe 312.

  The cleaning water pipe 312 is provided with a nozzle 304. The nozzle 304 injects cleaning water 314 from the upper side 310 to the bottom side 308 to treat the exhaust gas. The washing water 314 ejected from the nozzle 304 comes into contact with the exhaust gas passing through the inside of the reaction tower 302 and absorbs sulfur components contained in the exhaust gas. The liquid that has absorbed the sulfur component and the like collects on the bottom side 308 of the reaction tower 302 and is discharged out of the reaction tower 302 as waste water.

According to the exhaust gas purification system 400 of this example, harmful substances that cannot be removed only by the electric dust collector 200 can be removed. Since the electric dust collector 200 of the first to thirteenth embodiments is used for the exhaust gas purification system 400, erosion of the counter electrode 10 due to the occurrence position of the corona discharge 2 being fixed can be suppressed.
The above embodiment is also applied to a two-stage electrostatic precipitator in which a charging unit and a dust collecting unit are configured separately.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

2 .... corona discharge, 10 .... counter electrode, 12 ... end, 14 ... side, 20 ... DC power supply, 100 ... discharge electrode, 101 ... first annular part, 102 ... end, 103 ···· second annular portion, ······ straight portion ··························································: 114 ··· Straight edge, 115 ··· First edge, 116 ·· Square edge, 117 ··· Second edge, 122 · · Central edge, 123 · · · Peripheral edge, 140 · -Central opening, 146-Peripheral opening, 180-Projecting discharge electrode, 182-End, 184-Projecting part, 190-End counter electrode, 192-End, 200-Electric Dust collector 210... First unit 220.. Second unit 300 300 Scrubber 302 Reactor 304 304 Nozzle, 306 ... exhaust gas introducing pipe, 308 ... bottom side, 310 ... upper side, 312 ... washing water pipe, 314 ... washing water, 350 ... pumping pump, 400 ... exhaust gas purifying system

Claims (12)

A first electrode plate;
A second electrode plate provided opposite to the first electrode plate, the end of which is located inside the end of the first electrode plate;
The second electrode plate is an electrode plate that generates a corona discharge with the first electrode plate, and the second electrode is defined when the straight portion is defined to have an infinite radius of curvature. in the entire region of the end portion of the second electrode plate when viewed from a direction perpendicular to the arrangement surface of the plate, the ends will have a more than half the radius of curvature of the gap between the first electrode plate It is composed of only a plurality of curved corners and straight portions connecting the plurality of corners, or a closed curve having a radius of curvature more than half of the gap with the first electrode plate. ,
The second electrode plate has one or more through-openings, and the edge of the second electrode plate in the entire region of the edge of the through-opening when viewed from a direction orthogonal to the arrangement surface of the second electrode plate parts are either composed of only straight portion connecting between the first electrode plate and the curved plurality of corner portions and a plurality of corners with more than half of the radius of curvature of the gap, or the An electrostatic precipitator configured by a closed curve having a radius of curvature of more than half of the gap with the first electrode plate . The electrostatic precipitator according to claim 1, wherein a voltage is applied to the first electrode plate and the second electrode plate, and the first electrode plate is a GND electrode. The electric dust collector according to claim 1, wherein the second electrode plate has a disk shape. The second electrode plate includes a plurality of independent through-opening, electrostatic precipitator according to any one of claims 1 to 3. The one or more through openings are
A central opening with the largest opening area;
The electrostatic precipitator according to claim 4 , wherein the electrostatic precipitator has an opening area smaller than that of the central opening and a peripheral opening disposed around the central opening. At least one of the one or more through-openings has an entire edge surrounding the through-opening facing the first electrode plate when viewed from a direction orthogonal to the arrangement surface of the second electrode plate. The electrostatic precipitator according to any one of claims 1 to 5 . The second electrode plate has a plurality of through-openings, and the plurality of through-openings surround an edge of the through-opening when viewed from a direction perpendicular to the arrangement surface of the second electrode plate. The entire part protrudes toward the first electrode plate,
The length from which the entire edge protrudes differs between the upstream side and the downstream side of the gas introduced into the electrostatic precipitator.
The electric dust collector according to claim 6 . The electrostatic precipitator according to claim 7 , wherein a length of the entire edge projecting is longer on the upstream side than on the downstream side. The electrostatic precipitator according to any one of claims 1 to 8 , wherein a plurality of first units each having the first electrode plate and the second electrode plate are stacked. The gap length between the first electrode plate and the second electrode plate at the end in the stacking direction of the plurality of first units stacked is the center of the stacking direction of the first units stacked in plurality. The electric dust collector according to claim 9 , wherein the electric dust collector is larger than a gap length between the first electrode plate and the second electrode plate. A third electrode plate;
A second unit provided opposite to the third electrode plate and having a fourth electrode plate having an end portion located on an inner side of the end portion of the third electrode plate and an end portion having a protruding portion; Further comprising
The electrostatic precipitator according to claim 9 , wherein the second unit is provided at least at both ends in the stacking direction of the plurality of first units stacked. A scrubber that purifies the exhaust gas;
An exhaust gas purification system comprising: the electric dust collector according to any one of claims 1 to 11 , which is provided upstream of the scrubber.

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