DUST COLLECTING ELECTRODE OF MOVING ELECTRODE TYPE ELECTROSTATIC
PRECIPITATOR
FIELD OF THE INVENTION The present invention relates to a dust collecting electrode of a
moving electrode type electrostatic precipitator and, more particularly,
to a dust collecting electrode of a moving electrode type electrostatic
precipitator in which dust contained in exhaust gas is collected and
removed using moving dust-collecting electrodes.
BACKGROUND OF THE INVENTION
Dust collecting electrodes of existing moving electrode type electrostatic precipitators are each formed of a single dust collecting electrode plate of iron attached, at outer peripheral edge portions thereof, with edge reinforcement members. Generally, to enhance the dust collecting performance of a dust collecting electrode, the length in the gas flow direction (lateral direction) of the dust collecting electrode plate is increased. Increasing the length of the dust collecting electrode plate, however, makes it easier for the dust collecting electrode plate to be bent by its own weight. As a result, it becomes necessary to make the edge reinforcement members thicker to increase the strength of the dust collecting electrode plate.
Making the edge reinforcement members thicker, however, lowers the dust collecting efficiency of the dust collecting electrode. Namely, the dust collecting efficiency of a dust collecting electrode is proportional to the square of apparent electric field strength between the dust collecting electrode and a discharge electrode. The apparent
electric field strength is calculated by dividing the spark voltage by the distance between the discharge electrode and the dust collecting electrode. The spark voltage is determined by factors such as the distance between the discharge electrode and the dust collecting electrode and whether the dust collecting electrode has surface unevenness to cause electric field concentrations. When the edge reinforcement members used for a dust collecting electrode are made thicker, the distance between the dust collecting electrode and the discharge electrode is reduced, and electric field concentrations occur in the edge reinforcement members to lower the spark voltage. This reduces the apparent electric field strength and lowers the dust collecting efficiency.
Hence, an improved dust collecting electrode 10 as disclosed in JP-A No. H10-230187 has been developed which includes, as shown in FIG. 5, reinforcement core members 14 and 16 and a pair of dust collecting electrode plates 12 with the reinforcement core members disposed therebetween. This has made it possible to increase the lateral length of the dust collecting electrode, make the dust collecting electrode free of surface projections and enhance the dust collecting performance of the dust collecting electrode.
SUMMARY OF THE INVENTION The dust collecting electrode described in JP-ANo. H10-230187 having
a box-like structure is, however, heavy with the three horizontal frame
members included to secure mechanical strength of the electrode. This
causes the chains used in the precipitator to wear more and the precipitator to consume more power, whereas there are great needs for lower-cost, lighter, less-power-consuming precipitators.
The present invention made in view of the above problems with existing precipitator techniques provides a dust collecting electrode of a moving electrode type electrostatic precipitator aimed at a large weight reduction while securing mechanical strength. The invention also provides a dust collecting electrode finished to be free of surface unevenness which can be a factor in lowering the spark voltage.
To address the above problems, the present invention provides a dust collecting electrode of a moving electrode type electrostatic precipitator which is attached to, and between, a pair of endless chains and which collects dust in charged gas by moving vertically in a dust chamber together with the moving endless chains. The dust collecting electrode comprises a main plate member having a plurality of laterally extending bent portions and a subsidiary plate member to cover a concave formed by the bent portions of the main plate member. The bent portions of the main plate member are located as reinforcement members in an upper end portion, a lower end portion, and an intermediate portion between the upper and lower end portions, respectively, of the dust collecting electrode.
The main plate member comprises a plurality of arranged U-shaped plate members each having a laterally extending bent-edge portion and a subsidiary plate member structured to cover a concave formed by the bent-edge portions.
The main plate member has a laterally extending bent-edge portion in each of an upper end portion and a lower end portion thereof and a laterally extending bent portion in an intermediate portion between the upper end portion and the lower end portion thereof. The upper and lower bent-edge portions and the intermediate bent portion form a concave which is covered by the subsidiary plate member.
Each of the main plate member and the subsidiary plate member has a laterally extending bent-edge portion in each of an upper end portion and a lower end portion thereof. The bent-edge portions of the main plate member and the bent-edge portions of the subsidiary plate member are joined forming the dust collecting electrode.
According to the present invention, a dust collecting electrode can be reinforced by a bent (bent-edge) portion extending in a lateral direction of the electrode plate, so that the dust collecting electrode can be largely reduced in weight to promote reduction in power consumption.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is an exploded perspective view of a dust collecting electrode
according to a first embodiment of the present invention.
FIG. 1B is a perspective view of the dust collecting electrode according to the first embodiment of the present invention in an assembled state.
FIG. 2A is an exploded perspective view of a dust collecting electrode according to a second embodiment of the present invention.
FIG. 2B is a perspective view of the dust collecting electrode according to the second embodiment of the present invention in an assembled state.
FIG. 3A is an exploded perspective view of a dust collecting electrode according to a third embodiment of the present invention.
FIG. 3B is a perspective view of the dust collecting electrode according to the third embodiment of the present invention in an assembled state.
FIG. 4 is a perspective view of a moving electrode type electrostatic precipitator.
FIG. 5 is an explanatory view of an existing dust collecting
electrode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiments of a dust collecting electrode of a moving electrode
type electrostatic precipitator according to the present invention will
be described in detail below with reference to the accompanying drawings.
FIG. 4 is a perspective view of dust collecting electrodes 10 according
to an embodiment. The dust collecting electrodes 10 are each formed
as a plate which is attached, at both ends thereof, to a pair of endless
chains 13. The chains 13 are each wound tightly around an upper drive
sprocket 4 and a lower driven roller 6.
The drive sprockets 4 are fixed to the output shaft of a sprocket
drive motor 7. The driving force of the sprocket drive motor 7 is
transmitted to the chains 13 via the drive sprockets 4 to turn the chains
13 in the direction indicated by arrows in FIG. 4, eventually causing
the dust collecting electrodes 10 to turn. A discharge electrode 8 is disposed between opposing ones of the dust collecting electrodes 10. The dust collecting electrodes 10 and the discharge electrode 8 are connected to a DC power supply, not illustrated, and a DC voltage is applied across the dust collecting electrodes 10 and the discharge electrode 8. Dust contained in the exhaust gas flowing between the dust collecting electrodes 10 and the discharge electrode 8 is charged by corona discharge occurring between them, causing the charged dust to adhere to the dust collecting electrodes 10 to be collected there.
Embodiment 1
As shown in FIG. 1A, the dust collecting electrode 10 includes main plate members 20 and 21, and a subsidiary plate member 22 . The subsidiary plate member 22 is formed of a flat steel plate having a vertically extending bent portion 22a in each of left and right end portions thereof and plural openings 22b for plug welding arranged horizontally (laterally) along a vertically intermediate portion thereof. Of the two main plate members, the main plate member 20 is formed of a flat steel plate which is half as high as the subsidiary plate member 22 and which has a laterally extending bent-edge portion (bent portion) 20a in each of upper and lower end portions thereof. The other main plate member 21 is also formed of a flat steel plate which is half as high as the subsidiary plate member 22 and which has a laterally extending bent-edge portion (bent portion) 21a in each of upper and lower end portions thereof. The main plate members 20 and 21 having the bent-edge portions 20a and 21a, respectively, each have a concave
With an approximately U-shaped cross-section, and are, in a state of being vertically symmetrically arranged, fixed by welding to the subsidiary plate member 22 such that the concaves are covered by the subsidiary plate member 22.
The bent-edge portions (bent portions) 21a have L-shaped vertical frames 22f or vertical square-pipe frames 22g fixedly welded to their lateral left and right ends, respectively.
As shown in FIG. 1B, the main plate members 20 and 21 are plug-welded (22c) to a vertically intermediate portion of the subsidiary plate member 22 and are spot-welded (22d and 22e) to the vertically extending bent portions 22a and upper and lower laterally extending bent-edge portions of the subsidiary plate member 22. The subsidiary plate member 22 and the vertical frames 22f or 22g are connected by laser welding. The vertically symmetrically arranged main plate members 20 and 21 are laser-welded together where their bent-edge portions 20a and 21a are put together face to face. Thus, the dust collecting electrode 10 with height H and lateral width W is assembled.
The dust collecting electrode 10 assembled as described above has four bent-edge portions (bent portions) 20a and 21a formed by the upper and lower bent portions of the main plate members 20 and 21. With the upper and lower end portions and an intermediate portion between them of the dust collecting electrode 10 reinforced by the bent-edge portions, the dust collecting electrode 10 is enhanced in lateral rigidity not to be easily bent. According to the present embodiment, the dust collecting electrode 10, unlike existing dust collecting electrodes,
requires no lateral reinforcement core member, so that it can be made about 13% lighter than existing comparable dust collecting electrodes. Moreover, the surface of the dust collecting electrode 10 including the main plate members and the subsidiary plate member that are joined by welding can be smoothly finished, so that the dust collecting electrode 10 does not lower the spark voltage.
Embodiment 2
As shown in FIG. 2A, the dust collecting electrode 10 includes a main plate member 23, subsidiary plate members 24, and vertical frames 22g. The main plate member 23 is formed of a flat steel plate which includes bent portions (23b and 23c) extending horizontally (laterally) in a vertically intermediate portion thereof, a flat convex surface 23e, and upper and lower bent-edge portions (bent portions) 23a and 23d extending laterally as long as the flat convex surface 23e. The subsidiary plate members 24, on the other hand, are each formed of a flat steel plate and are fixed by laser welding to the main plate member 23 such that they cover the concaves formed, on both sides of the main plate member 23, by the bent portions 23a to 23d. As shown in FIG. 2B, the main plate member 23 is sided, at each of lateral end portions thereof, by a vertical square-pipe frame 22g laser-welded to the main plate member 23 and the subsidiary plate members 24.
The dust collecting electrode 10 assembled as described above has four bent portions 23a to 23d formed in the main plate member 23 to laterally extend as long as the dust collecting electrode. With the upper and lower end portions and an intermediate portion between them
bf the dust collecting electrode 10 reinforced by the bent portions, the dust collecting electrode 10 is enhanced in lateral rigidity not to be easily bent. According to the present embodiment, the dust collecting electrode 10, unlike existing dust collecting electrodes, requires no lateral reinforcement core member, so that it can be made about 16% lighter than existing comparable dust collecting electrodes. Moreover, the surface of the dust collecting electrode 10 including the main plate member and the subsidiary plate members that are joined by welding can be smoothly finished, so that the dust collecting electrode 10 does not lower the spark voltage.
Embodiment 3
As shown in FIG. 3A, the dust collecting electrode 10 includes a main plate member 25, a subsidiary plate member 26, and an H-shaped frame 27. The main plate member 25 and the subsidiary plate member 26 are identically shaped, so that they are interchangeable. Each of the main plate member 25 and the subsidiary plate member 26 includes, in upper and lower end portions thereof, horizontally (laterally) extending bent-edge portions (bent portions) 25a or 26a. The two plate members are joined with their bent-end portions laid to mutually overlap, holding the H-shaped frame 27 between them. As shown in FIG. 3B, the two plate members and the H-shaped frame 27 are joined by spot welding (26a) and the overlapping bent-edge portions of the two plate members are joined by laser welding (26b) such that the space formed between the two plate members having the bent-edge portions 25a and 26a is closed.
The dust collecting electrode 10 assembled as described above has two each of bent-edge portions 25a and 26a formed in upper and lower end portions of the plate members 25 and 26 to laterally extend as long as the dust collecting electrode and, furthermore, has the H-shaped frame 27 including a laterally extending fixed part. With the upper and lower end portions and an intermediate portion between them of the dust collecting electrode 10 reinforced by the bent-edge portions and the H-shaped frame, the dust collecting electrode 10 is enhanced in lateral rigidity not to be easily bent. According to the present embodiment, the dust collecting electrode 10, unlike existing dust collecting electrodes, requires no lateral reinforcement core member, so that it can be made about 10% lighter than existing comparable dust collecting electrodes. Moreover, the surface of the dust collecting electrode 10 including the main plate member and the subsidiary plate member that are joined by welding can be smoothly finished, so that the dust collecting electrode 10 does not lower the spark voltage.

What is claimed is:
1. A dust collecting electrode of a moving electrode type electrostatic precipitator which is attached to, and between, a pair of endless chains and which collects dust in charged gas by moving vertically in a dust chamber together with the moving endless chains, the dust collecting electrode comprising a main plate member having a plurality of laterally extending bent portions and a subsidiary plate member to cover a concave formed by the bent portions of the main plate member, the bent portions of the main plate member being located as reinforcement members in an upper end portion, a lower end portion, and an intermediate portion between the upper and lower end portions, respectively, of the dust collecting electrode.
2. The dust collecting electrode of a moving electrode type electrostatic precipitator according to claim 1, wherein: the main plate member comprises a plurality of arranged U-shaped plate members each having a laterally extending bent-edge portion and a subsidiary plate member structured to cover a concave formed by the bent-edge portions.
3. The dust collecting electrode of a moving electrode type electrostatic precipitator according to claim 1, wherein the main plate member has a laterally extending bent-edge portion in each of an upper end portion and a lower end portion thereof and a laterally extending bent portion in an intermediate portion between the upper end portion and the lower end portion thereof, the upper and lower bent-edge portions and the intermediate bent portion forming a concave, the concave being covered by the subsidiary plate member.
4. The dust collecting electrode of a moving electrode type electrostatic precipitator according to claim 1, wherein each of the main plate member and the subsidiary plate member has a laterally extending bent-edge portion in each of an upper end portion and a lower end portion thereof, the bent-edge portions of the main plate member and the bent-edge portions of the subsidiary plate member being joined forming the dust collecting electrode.