JPH04235760A - Electrostatic precipitator - Google Patents

Abstract

PURPOSE:To enhance dust collection efficiency and reduce manufacturing cost to increase mass productivity. CONSTITUTION:A collector electrode consists of upright parts 11, 21 as parallel flat plate electrodes, formed by punching and making upright metal plates 10, 20 are set a pair of the 10 and 20 at positions opposed to each other.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic precipitator, and more particularly to an improvement in the collector electrode of a dust collecting section.

0003

[Prior Art] Electrostatic precipitators include an ionizer that generates corona discharge between a discharge electrode and a discharge counter electrode, and charges dust particles in the air with the corona discharge, and an ionizer that uses Coulomb force to charge the dust particles in the air. A dust collecting section consisting of a collector electrode for collecting dust is provided. For the discharge electrode of an ionizer, a needle-like electrode, a thin metal wire stretched by a spring, or the like is used to improve discharge performance. On the other hand, the collector electrode of the dust collecting section is composed of a group of positive and negative parallel plate electrodes including a collection side electrode and an opposing side electrode, which are arranged opposite to each other with a required spacing between them.

In order to efficiently collect charged dust particles with the collector electrode, it is important to create a parallel electric field having a uniform distribution with the parallel plate electrode. For example, in the configuration of a collector electrode consisting of a collection side electrode 1 and an opposing side electrode 2 as shown in FIG. 5(a), the gap between both electrodes 1 and 2 is partially If the area becomes narrower, the electric field in this narrower area becomes stronger and the collection characteristics are improved, but ventilation resistance increases and the amount of ventilation decreases, making it impossible to expect an improvement in dust collection efficiency corresponding to the increase in electric field strength. On the other hand, in areas where the distance between the electrodes 1 and 2 is wide, the electric field becomes weaker, the ventilation resistance decreases, the passing wind speed increases, and the collection characteristics deteriorate.

[0005] Furthermore, it is important that the potential distribution on the electrode plate be uniform, and in the case where a plurality of electrode pairs are used, that the potential difference between each electrode pair be uniform. If the potential distribution on the electrode plate is uneven or the potential difference between each pair of electrodes is uneven, dust particles that enter the area where the electric field is strong will be rapidly collected, but in the latter half of the electrode, The amount of collected dust decreases rapidly, and it is impossible to expect more than a certain amount of collected dust. Conversely, in areas where the electric field is weak, the number of particles that cannot be collected increases. In the end, the further the specifications set at the time of designing the electrostatic precipitator depart, the worse the dust collection efficiency of the entire collector electrode becomes.

[0006] As a countermeasure to this problem, there are methods such as increasing the power supply capacity, but the efficiency of power consumption regarding electrostatic precipitation deteriorates. Furthermore, if the positive and negative electrodes approach each other locally, there is a greater possibility of spark discharge occurring, so countermeasures are required. FIG. 11 shows an example of measuring the relationship between the inter-electrode distance and the edge discharge firing voltage.

FIG. 6 shows a first conventional example having a collector electrode structure in which a means is provided to maintain parallel plate electrodes at regular intervals. In this conventional example, a highly conductive material such as metal is used for the collector electrode, and in order to keep the dust collection side electrode 1 and the opposite side electrode 2 parallel, an insulating spacer 3 is placed between the two electrodes 1 and 2. The structure is sandwiched between. However, in this conventional example, some positively charged dust particles 4a adhere to the surface of the spacer 3 due to Coulomb force, as shown in FIG. 7(a). Since the spacer 3 is an insulator, the electric charge of the dust particles accumulates on the spacer 3, and as a result, the electric field between the electrodes 1 and 2 is weakened. Furthermore, when the dust particles 4b attached to the spacer 3 have conductivity as shown in FIG. 7(b), it is the same as the electrode 2 extending to the spacer.
The electric field is no longer applied to the S portion in the figure.

Furthermore, since the spacer 3 acts as a ventilation resistance, a higher output blower is required in order to increase the amount of air processed per unit time. Since the electrodes 1 and 2 have been manufactured and assembled one by one, it takes time and effort to attach them to a frame, etc., which makes the manufacturing process of the collector electrode more troublesome and increases the manufacturing cost. Further, since the structure is such that each electrode plate contacts a power supply terminal to obtain a potential, variations in contact resistance are likely to occur, and variations in potential difference between each electrode are likely to occur.

FIG. 8 shows a second conventional example having a collector electrode structure in which means are provided to hold the electrodes at regular intervals. In this conventional example, the collection side electrode 5 and the opposing side electrode 6 are manufactured as a pair of electrode strips with an insulating layer 7 in between, and a spacer 8 is stacked on this electrode strip and wound in a spiral shape. It has a structure that is attached to etc. However, even in this conventional example, there are problems caused by some dust particles adhering to the spacer 8, as shown in FIGS. There is a problem with becoming. Furthermore, when assembling a pair of electrode strips into a frame or the like, it is necessary to assemble them in a spiral shape, which is time consuming and similar to the above, the manufacturing process of the collector electrode is troublesome and the manufacturing cost is relatively high.

FIG. 9 shows a third conventional example having a collector electrode structure in which means are provided to hold the electrodes at equal intervals. In this conventional example, both ends of the collection side electrode 1 and the opposing side electrode 2 are supported one by one by a fixed support 9 by a technique such as sandwiching, welding, or adhesion. but,
In this conventional example, when attaching the electrodes 1 and 2 to the fixed support 9 by inserting them into the groove, as shown in FIG. Because only frictional force acts on it, its own weight generates a force in the direction of pulling it out of the groove, making it susceptible to bending. Furthermore, if the lengths of the electrodes 1 and 2 are uneven, if the fixed support 9 is moved closer to firmly hold the shorter electrode, the longer electrode will bend. Further, when the electrodes 1 and 2 are fixed by welding, different internal stresses are generated in the individual electrodes 1 and 2 due to the influence of thermal expansion of the metal plate during welding, which tends to cause deformation. Furthermore, by adhesion, the electrode 1
, 2, there is a possibility that the electrodes 1 and 2 may be subjected to force while the adhesive hardens, or that the electrodes 1 and 2 may move due to a change in the state of the adhesive. In this way, in this conventional example, when attached to the fixed support body 9 by these fixing methods,
Since various external forces act on the electrodes 1 and 2, high machining accuracy is required to make them into uniform shapes.

Further, in this conventional example, as in the first conventional example, the electrodes 1 and 2 were manufactured separately and assembled one by one, so the manufacturing process of the collector electrode was troublesome. The manufacturing cost is relatively high, and since the structure is such that the individual electrode plates 1 and 2 are in contact with the power supply terminal to obtain the potential, variations in contact resistance are likely to occur, resulting in variations in the potential difference between the electrodes 1 and 2. is likely to occur.

0012

[Problems to be Solved by the Invention] In the first conventional example, insulating spacers were used to keep the individual electrode plates parallel, so charged dust particles accumulated on the spacers and caused problems between the electrodes. This weakens the electric field and creates areas where no electric field is applied, reducing dust collection efficiency. Variations occur in the contact resistance between the power supply terminal and the individual electrode plates, which tends to cause variations in the potential difference between the electrodes, and in this respect as well, the dust collection efficiency of the collector electrode as a whole decreases. Since the spacer acts as ventilation resistance, a high-power blower is required to increase the amount of air processed. There was a problem that the manufacturing process of the collector electrode was complicated and the manufacturing cost was relatively high.

In the second conventional example, a pair of electrode bands and a spacer are overlapped to form a spiral structure, so there are the same problems as in the first conventional example due to the use of the spacer, and the collector electrode The problem was that the manufacturing process was complicated and the manufacturing cost was relatively high.

In the third conventional example, both ends of each electrode plate are supported by fixed supports, so when each electrode plate is sandwiched between fixed supports and attached by welding, gluing, etc. The electrode plate is bent, which tends to cause variations in the spacing between the electrodes, reducing the dust collection efficiency of the entire collector electrode. Further, like the first conventional example, there is a problem that the manufacturing process of the collector electrode is complicated and the manufacturing cost is relatively high.

[0015] Accordingly, an object of the present invention is to provide an electrostatic precipitator that has high dust collection efficiency, is inexpensive to manufacture, and is suitable for mass production.

[Configuration of the invention]

[0017]

[Means for Solving the Problems] In order to solve the above problems, the present invention charges dust particles in the air with an ionizer and applies a potential difference between collector electrodes composed of at least one set of parallel plates. The electrostatic precipitator collects the charged dust particles, in which a metal plate is punched and stood up to form a standing part, and a pair of the metal plates are opposed to each other, and the collector is collected by the standing part of each metal plate. The gist is that the electrode is configured.

[0018]

[Operation] Since there is no spacer between the parallel plate electrodes formed in the upright part, there is no problem such as weakening of the electric field between the parallel plate electrodes due to charged dust particles accumulating on the spacer. Since there is no resistance to ventilation, dust collection efficiency is improved. The flat plate electrode formed by the upright part can be cut and raised from a single metal plate in one press punching process as many as necessary to assemble the collector electrode, making it easy to manufacture and assemble the flat plate electrode. Low manufacturing costs are achieved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are diagrams showing an embodiment of the present invention.

First, to explain the structure of the collector electrode of the electrostatic precipitator in this embodiment, as shown in FIG. They are cut and raised in parallel at regular intervals. Each standing portion 11 is supported by the ear portions 12, and the entire metal plate 10 is structured in a lattice shape, with ventilation gaps formed at the punched portions 13.

As shown in FIG. 2, each standing portion 11
, 21 are arranged alternately at equal intervals.
A collector electrode is constructed by arranging a pair of electrodes facing each other and fixing them to the frame 15. In the illustrated example, the upright portion 11 is the collection side electrode, and the other upright portion 21 opposite thereto is the opposite electrode. In this manner, in the collector electrode of this embodiment, a plurality of groups of electrode plates are assembled in parallel at equal intervals by simply fixing a pair of metal plates 10 and 20 to the frame 15 so as to face each other.

The collector electrode in the electrostatic precipitator of this embodiment is constructed as described above, and since there is no spacer between the electrodes formed by the upright portions 11 and 21, charged dust particles accumulate on the spacer. There are no problems such as weakening of the electric field between the electrodes, and the spacer does not act as a resistance to ventilation, so it is possible to improve the dust collection efficiency. The electrode plate formed by each standing portion 11, 21 is a metal plate 10
, 20, there is no variation in potential due to variation in contact resistance between the power supply terminal and each electrode plate, and a collector electrode with uniform electric field distribution can be constructed.
In this respect as well, it is possible to improve the dust collection efficiency of the entire collector electrode. The upright parts 11 and 21, which become the respective electrode plates, are supported by the ear parts obtained by cutting and raising the upright parts 11 and 21. , 21 exert a tensile or compressive force on each other in the longitudinal direction. For this reason, each standing part 1
Compared to the conventional collector electrode, which works in the direction of holding the electrodes 1 and 21 straight, and fixes the individual electrode plates one by one, the rigidity is higher with the same plate thickness, so the electrode plate can be made thinner. This makes it possible to improve dust collection efficiency by increasing the number of electrodes and reducing ventilation resistance.

[0024] Also, the upright portions 11 and 21 serving as electrode plates are 1
It can be processed by press punching in multiple steps, and there is no need to use methods such as welding, gluing, or inserting into grooves, so there is no need to apply different extra forces to each electrode plate, which requires high processing precision. It becomes possible to construct electrode plates having equal intervals without any interference. Furthermore, the number of electrodes required to assemble the collector electrode can be cut and raised from a single metal plate by press processing, making it easy to manufacture the electrode plates. , there is no need to handle a pair of long electrode strips. Therefore, the assembly process of the collector electrode becomes simpler and the manufacturing cost of the collector electrode becomes cheaper.

Next, FIGS. 3 and 4 show a collector electrode structure in another embodiment of the present invention.

In this embodiment, two metal plates each having a plurality of upright portions are assembled on both the collection side and the opposite side, and the pitch between the parallel plate electrodes is 2 times larger than that of the previous embodiment.
It is narrowed to one-fold.

That is, as shown in FIG. 3, two metal plates 10 and 30 each having a plurality of upright portions 11 and 31 cut in parallel at regular intervals are combined, and the first metal plate The raised parts 31 cut and raised from the second metal plate 30 are protruded at equal intervals between the raised parts 11 cut and raised from the plate 10, so that the combined metal plates 10 and 30 have a narrow pitch between electrodes.
is configured. As shown in FIG. 4, a pair of combined metal plates 10, 30 and 20, 40 are arranged facing each other and fixed to the frame 15, thereby forming a collector electrode with a narrow pitch between the parallel plate electrodes. . In the illustrated example, the standing parts 11 and 31 serve as collection side electrodes, and the other standing parts 21 and 41 opposite thereto serve as opposing side electrodes.

The dust collection efficiency of the collector electrode is proportional to the electric field strength rather than its collection mechanism. Since the electric field strength is inversely proportional to the distance between the parallel plate electrodes if the potential difference between them is constant, the collector electrode of this example is
The dust collection efficiency is further improved compared to that of the first embodiment.

[0029]

As explained above, according to the present invention, the standing portions are formed by punching and standing up metal plates, and by making a pair of the metal plates face each other, the standing portions of each of the metal plates are made parallel to each other. Since the collector electrode is configured as a flat plate electrode, there is no spacer between the parallel plate electrodes, eliminating problems such as weakening of the electric field between the parallel plate electrodes due to charged dust particles accumulating on the spacer. Since there is no resistance to ventilation, high dust collection efficiency can be obtained. Furthermore, the flat plate electrode formed in the upright part can be cut and cut from a metal plate in the number required to assemble the collector electrode at the same time by press punching, etc., which simplifies the production and assembly of the collector electrode and reduces manufacturing costs. can be reduced and mass productivity can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an electrode plate for a collector electrode structure cut and raised from a metal plate in an embodiment of an electrostatic precipitator according to the present invention.

FIG. 2 is a diagram showing a collector electrode made up of the electrode plate of FIG. 1;

FIG. 3 is a perspective view showing an electrode plate made of a combination of metal plates for configuring a collector electrode in another embodiment of the present invention.

FIG. 4 is a diagram showing a collector electrode composed of the electrode plate of FIG. 3;

FIG. 5 is a diagram showing lines of electric force when the distances between parallel plate electrodes constituting a collector electrode are not equal.

FIG. 6 is a diagram showing a collector electrode structure in a first conventional example.

FIG. 7 is a diagram for explaining problems in the first conventional example.

FIG. 8 is a diagram showing a collector electrode structure in a second conventional example.

FIG. 9 is a perspective view showing a collector electrode structure in a third conventional example.

FIG. 10 is a diagram for explaining problems in the third conventional example.

FIG. 11 is a characteristic diagram showing an example of measuring the relationship between the distance between parallel plate electrodes in the collector electrode and the voltage at which edge discharge occurs.

[Explanation of symbols]

10, 20, 30, 40 Metal plates 11, 21, 31, 41 Standing portions that serve as flat plate electrodes for collector electrode configuration

Claims (1)

[Claims] 1. An electrostatic precipitator that charges dust particles in the air with an ionizer and collects the charged dust particles by applying a potential difference between collector electrodes composed of at least one set of parallel flat plates. An electrostatic precipitator, characterized in that a metal plate is punched and stood up to form a standing part, a pair of the metal plates are placed opposite each other, and the collector electrode is formed by the standing part of each metal plate.