JP3328683B2 - Air purifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air purifier using an electric dust collection system.

[0002]

2. Description of the Related Art The contents required of a dust collecting section of an air purifying apparatus are such that fine particles can be collected with high efficiency, small and thin, low pressure loss, low running cost, and the like. It is. Considering the conventional dust collection method, it can be roughly classified into a method using mechanical force such as trapping particles in a filter, and a method using electrostatic force such as electric dust collection. The filter method, which is one of the methods for trapping particles using mechanical force, is extremely small particles such as 0.3 μm at the level of a ULPA filter used in a clean room of a semiconductor factory, for example. Although it exhibits a very high dust collection efficiency of more than 99%, it has poor air permeability in principle and exhibits very high pressure loss characteristics. Therefore, in order to ensure the airflow of these high-performance filters, there are problems such as an increase in the size of the blower mechanism, an increase in noise level, and energy loss. Also, the filter system is difficult to clean and regenerate after use due to its structure, and it is necessary to discard it after its life,
Running costs tend to be high. On the other hand, in the electrostatic dust collection method using electrostatic force, although the pressure loss with respect to the gas flow is low in principle, the dust collection efficiency is not necessarily high as compared with the Ulpa filter or the like. At present, various devices have been devised to improve the dust collection efficiency.

First, a general example of a conventional electric dust collector is shown in FIG. In FIG. 2, the discharge electrode 1 is arranged in parallel with the dust collection electrode 2 and the air flow. At the tip of the discharge electrode 1, a needle-like needle end 3 is provided. Power supply 4
Is connected to the discharge electrode 1 and the plus side is
And the ground 5, the electric field concentrates on the needle end 3 of the discharge electrode 1, and the air insulation near the needle end 3 is broken, thereby generating a negative corona discharge. Particles entering this space from the upstream of the air flow pass through the negative ion space generated by the corona discharge, and are negatively charged by mechanisms such as electron attachment and electron impact. And
Coulomb force due to the action of the electric charge and electric field of the particles,
It is led to the dust collecting electrode 2 and trapped. In this general dust collection method, as shown by Deutsche's equation, the larger the electric field strength formed between the discharge electrode 1 and the dust collection electrode 2 and the larger the area of the dust collection electrode 2, the larger the collection. The dust effect is improved. However, even when the electric field strength is increased, the upper limit is the spark discharge starting voltage, which usually takes a considerable safety factor, so that the improvement in dust collection efficiency due to the increase in the electric field strength cannot be obtained as expected. . In addition, in the method of increasing the area of the dust collecting electrode 2, in the case of FIG. 2, the collecting electrode needs to be extended to the downstream side of the air flow, and there is a disadvantage that the dust collecting portion becomes large.
However, in the case of the electric dust collecting method, the dust collecting portion often has a cleaning property due to its structure, and it can be reused and the running cost tends to be relatively low.

As an attempt to overcome various problems in the filter system and the electric dust collection system, there is an electret filter in which a filter material itself is charged in advance, and Japanese Patent Application Laid-Open No. 57-1454. Electret filters can reduce the pressure loss compared to filters with the same dust collection efficiency, but the problem of reduced power consumption over long periods of use and the improvement of dust collection efficiency are due to the mechanical dust collection of filters. There is a problem that a filter with high dust collection efficiency has a high pressure loss due to a strong dependence on force. In addition, since the filter is difficult to regenerate by washing due to its structure, it is necessary to replace the filter after trapping predetermined dust, and the running cost is not sufficiently reduced. Japanese Patent Application Laid-Open No. 57-1454 discloses that a charging unit is provided on the upstream side of a gas flow to charge dust particles passing therethrough, and a direction perpendicular to the gas flow direction of the dust-containing gas flow is provided on the downstream side. And arrange the filter media to meander,
A conductive spacer through which dust-containing gas can pass between adjacent portions is sandwiched from the upstream and downstream sides of the gas flow, and a high voltage is applied between the upstream and downstream spacers. The improvement of the dust efficiency and the reduction of the running cost by extending the life of the filter medium are realized. However,
Reuse of the filter medium by washing is difficult due to its structure, and after trapping predetermined dust, the filter medium needs to be replaced, and the running cost is not sufficiently reduced.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention is an improvement of the above-mentioned prior art, which realizes high dust collection efficiency, miniaturization and low pressure loss, which are the propositions of a dust collection system, and can be reused by washing. It is an object of the present invention to provide an air purifier having a low running cost.

[0006]

In order to solve the above-mentioned problems, the present invention provides a charging section on the upstream side of a gas flow and insulates a conductive or conductive substance as a collecting section on the downstream side. Permeable plate-like material coated with
The side surface of the plate-like material is continuously bent in a U-shape, and is formed in a pleated shape so that the angle between both sides forming the U-shape is 90 ° or less (hereinafter, this is referred to as a pleated electrode). This is disposed so as to be orthogonal to the gas flow, and the pleat electrode is coated with an insulator from at least one of the upstream side and the downstream side of the gas flow to the concave portion of the pleat electrode. If not, an electrode (hereinafter referred to as a collecting electrode) extending in parallel to the flow direction of the gas flow obtained by coating the conductive material with an insulator is coated on the pleated electrode with the insulator. If it is, insert a conductive material or a collector electrode coated with an insulator on the conductive material, and capture so that the polarity of the collector electrode is opposite to the polarity of the charged electrode on the particles by the upstream charged part of the gas flow. High voltage between the electrodes and the pleated electrodes is obtained so as to apply the.

Further, in the above-mentioned collecting part, when the collecting electrode is inserted into the pleated electrode only from one of the upstream and downstream sides of the gas flow, a ventilation hole is formed at the tip of the pleated electrode where the collecting electrode is not inserted. No or closed vents.

[0008]

According to the above means, when the collecting electrode is arranged on the upstream side of the gas flow of the pleated electrode, when the charged dust particles reach the collecting portion, the pleated electrode and the upstream collecting electrode are connected to each other. Under the electric field effect. In this case, the direction of the force applied to the charged particles from the electric field is a vector directed toward the collection electrode having a different polarity. On the other hand, considering the flow of the gas flow, the gas flow flows so as to concentrate on a portion having a low airflow resistance due to the nature of the fluid, that is, a portion between the convex portion and the concave portion of the pleated electrode. Therefore, the flow velocity near the convex portion and the concave portion of the pleated electrode is extremely low. Here, the motion of the charged particles passing through the collection unit is converted into a vector flowing from the upstream side to the downstream side of the gas flow dominated by the gas flow velocity and the collection electrode by the electric field formed by the collection electrode and the pleated electrode. As a result, the charged particles gradually enter the collection part and approach the collection electrode at the same time, and when approaching the collection electrode, the vector given by the gas flow is reduced by the mechanism described above. As is well known, the force that the charged particles receive from the electric field increases in proportion to the square of the distance, so that the attractive force that the charged particles receive from the collection electrode exerts a further effect. By the mechanism described above, when the collecting electrode is provided on the upstream side of the pleated electrode, the charged particles are efficiently trapped by the collecting electrode.

Focusing on the case where a collecting electrode is disposed downstream of the gas flow of the pleated electrode, when the gas flow passes through the pleated electrode, a part of the gas flow is refracted in the direction of the collecting electrode. The vector of the gas flow itself tilts in the direction toward the collection electrode. Also, due to the electric field effect between the collecting electrode and the pleated electrode, the charged particle has a direction vector toward the collecting electrode having a different polarity from itself. The motion of the charged particles passing through the collecting part is a combination of the vector inclined to the collecting electrode given by the gas flow and the vector directed to the collecting electrode by the electric field formed by the collecting electrode and the pleated electrode, and the pleated electrode When a collecting electrode is disposed downstream of the device, the charged particles are efficiently trapped by the collecting electrode.

When the collecting electrode is inserted into the pleat electrode only from one of the upstream and downstream sides of the gas flow, when the gas flow passes through the tip of the pleat electrode in which the collecting electrode is not inserted, the collecting electrode is turned off. If it is on the upstream side of the pleated electrode, the action of the electric field between the collecting electrode and the pleated electrode cannot be given to the charged particles passing through this part, so that the dust collecting efficiency is reduced. Further, when the collecting electrode is located downstream of the pleated electrode, the action of the electric field between the collecting electrode and the pleated electrode cannot be given to the charged particles passing through this portion, and furthermore, this portion cannot be provided. Since the gas flow passing through the collector electrode flows in parallel with the collector electrode without tilting in the direction of the collector electrode, the dust collection efficiency decreases. The above disadvantage can be improved by not forming a ventilation hole at the tip of the pleated electrode or closing the formed ventilation hole.

In the present invention, all of the upstream collecting electrode, the downstream collecting electrode and the pleated electrode can be constituted by a metal, a conductive polymer or a material obtained by coating them with an insulating material, and can be washed and regenerated. And running costs can be reduced.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic diagram of a first embodiment of the present invention. In the first embodiment, a linear discharge electrode 1 and a counter electrode 8 facing the discharge electrode 1 are provided on the upstream side of the gas flow as the charging unit 6, and the discharge electrode 1 is connected to a negative pole of a charging power supply 4a. 8 is connected to the positive pole of the charging power supply 4a and to the ground 5; In the charging section 6, a DC high voltage is applied between the linear discharge electrode 1 and the counter electrode 8 by the charging power supply 4a to generate a negative corona discharge, and dust contained in the gas flow entering the space. Is negatively charged. Here, it is not always necessary to use the linear discharge electrode 1 for the charging unit 6, and any material can be used as long as it can negatively charge the entering dust particles.

A collecting section 7 according to the present invention is provided downstream of the gas flow of the charging section 6. In the first embodiment, the collecting electrode 9 is inserted from the upstream and downstream sides of the pleated electrode 11, and the collecting electrode 9 is connected to the positive pole of the power supply 4b for collecting. It is connected to the negative pole side of the collecting power supply 4b and to the ground 5. Here, the trapping section 7 will be described in detail. The pleated electrode 11 is made of stainless steel punching metal having a thickness of 0.6 mm and a hole diameter of about 2 mm. The angle between the sides forming the U-shape is about 60 °, the radius of curvature at the tip is 1 mm, and the folding height, that is, the distance from the top of the mountain to the valley. It was processed to 7 mm. The collecting electrode 9 is formed by processing a stainless steel plate having a thickness of 0.3 mm into a strip shape, insulatingly coating it with silicon rubber, and contacting the concave portion of the pleated electrode 11 with a radius of curvature of 1 mm for the purpose of being in close contact with the concave portion. It was processed in the same way.

When the particles charged by the charging unit 6 enter the collection unit 7, first, as described in the section of the operation, the particles are first subjected to an electric field effect formed by the pleated electrode 11 and the upstream collection electrode 9a. In this case, the charged particles have a negative polarity, and the force received from the electric field is a vector directed to the positive collecting electrode 9a.

On the other hand, considering the flow of the gas flow, the gas flow flows so as to concentrate on a portion having a low airflow resistance due to the nature of the fluid, that is, a portion between the convex portion and the concave portion of the pleated electrode 11.
Therefore, the flow velocity near the convex portion and the concave portion of the pleated electrode 11 is extremely low. Here, the motion of the charged particles passing near the upstream collecting electrode 9a is formed by a vector from the upstream side to the downstream side of the gas flow, which is governed by the gas flow rate, and the vector formed by the upstream collecting electrode 9a and the pleated electrode 11. As a result, the charged particles enter the region and gradually approach the upstream collection electrode 9a at the same time as approaching the upstream collection electrode 9a. The vector given by the gas flow is reduced by the mechanism described above. Also, as is well known, the force that a charged particle receives from an electric field is two distances away.
Since it increases in proportion to the power, the suction force received by the charged particles from the upstream collection electrode 9a exerts a further effect, and most of the charged particles are trapped by the upstream collection electrode 9a in this space.

The charged particles that have passed through the region where the upstream collecting electrode 9a operates pass through the pleated electrode 11. At this time, a part of the gas flow is refracted toward the downstream collecting electrode 9b, Is inclined in the direction toward the downstream collection electrode 9b. This is because the ridge line of the pleated electrode 11 has an angle of 30 ° with respect to the downstream collecting electrode 9b, and the opening surface of the pleated electrode 11 is oriented in the direction of the downstream collecting electrode 9b with respect to the gas flow. It is because it is inclined to.

Further, due to the electric field effect between the downstream collecting electrode 9b and the pleated electrode 11, the charged particle has a direction vector toward the positive collecting downstream electrode 9b having a polarity different from that of the charged particle. The motion of the charged particles passing near the downstream collecting electrode 9b is caused by the vector inclined by the gas flow toward the downstream collecting electrode 9b and the electric field formed by the downstream collecting electrode 9b and the pleated electrode 11. The vectors are combined toward the collection electrode 9b, and the charged particles are efficiently trapped by the downstream collection electrode 9b.

In the first embodiment, when the voltage of the charging power source 4a is 5.5 KV and the voltage of the collecting power source 4b is 2 KV, the passing gas flow rate is 0.8 μm / s, and the number is 0.3 μm by the number counting method. The partial dust collection efficiency of the air dust was 90% or more, and the pressure loss was about 4 mmAq. When the voltage of the collection power supply 4b for applying a voltage to the collection electrode 9 of the present invention is set to 0 KV, the partial dust collection efficiency under the same measurement conditions is about 60%. It has been clarified that the collecting section 7 has an extremely high effect. In the first embodiment, the collecting section 7 can be reused by washing and regenerating.

FIG. 3 is a perspective view of a second embodiment of the present invention, and FIG.
FIG. 7 is a schematic diagram of the configuration of the second embodiment. In the second embodiment, a charging unit serving also as a first-stage dust collection unit and a first-stage dust collection unit 15 serving as a first-stage dust collection unit is provided upstream of the gas flow of the collection unit 7 of the present invention.
Is arranged. This part comprises a needle-shaped discharge electrode 1 made of stainless steel and a first dust collecting electrode 12 orthogonal to the gas flow of the stainless steel punching metal.
From the upstream side of the gas flow to the first dust collecting electrode 12 and connected to the minus side of the charging power source 4a.
Is connected to the positive side of the charging power supply 4a and also connected to the ground 5 to generate a negative corona discharge by applying a high voltage between the needle-shaped discharge electrode 1 and the first dust collection electrode 12, A negative charge is applied to the dust particles passing through this space, and an electric field generated between the discharge electrode 1 and the first dust collection electrode 12, particularly the needle end 3 of the needle-shaped discharge electrode 1 and the first dust collection electrode 12 The first-stage dust collection is performed by a strong electric field acting between the two.

Here, in the present invention, the charging section does not necessarily have to have the first-stage dust collecting function, but may have any configuration that can charge particles. The charged particles that have passed through the charging unit and the first-stage dust collection unit 15 are guided to the collection unit 7 according to the flow of the gas flow.

In the second embodiment of the present invention, the pleated electrode 1
1 is a stainless steel punching metal having a thickness of 0.6 mm and a hole diameter of about 2 mm. The intersection on the extension line of the folding angle is about 60 °, the radius of curvature at the tip is 1 mm, and the folding height, that is, from the top of the mountain to the valley. Was processed so that the distance to the portion was 7 mm. The downstream collection electrode 9b has a thickness of 0.1 mm.
A 3 mm stainless steel plate was insulatively coated with silicone rubber, and was worked so that the contact portion had a radius of curvature of 1 mm for the purpose of closely contacting the concave portion of the pleated electrode 11. The pleated electrode 11 was connected to the negative side of the collecting power supply 4b and to the ground 5, and the downstream collecting electrode 9b was connected to the positive side of the collecting power supply 4b.

The operation of the second embodiment is as described in the section of the operation and the first embodiment of the present embodiment. In the second embodiment, the voltage of the charging power supply 4a is set to 5.5K.
V, when the voltage of the collecting power supply 4b is 2 KV, the partial dust collection efficiency of 0.3 μm atmospheric dust by the number counting method at a passing gas flow rate of 0.8 m / s is 85% or more, and the pressure loss is about It was 2.5 mmAq. In addition, when the voltage of the collection power supply 4b applied to the downstream collection electrode 9b of the present invention is 0 KV, the partial dust collection efficiency under the same measurement conditions is about 60%.
%, And it is clear that the dust collecting portion of the present invention exerts a high effect. Further, the thickness 14 of the dust collecting section in the second embodiment is about 22 mm, which is significantly thinner than that of a normal electric dust collecting filter. Is possible.

As described above, two examples have been described as examples. However, the charged electrode property for dust particles is not necessarily negative, and when charged positively, the polarity of the collecting electrode 9 is set to a negative value different from the charged electrode property. do it. Also,
It is not always necessary to coat the collecting electrode 9 with an insulator, and it is sufficient if either the pleated electrode 11 or the collecting electrode 9 is insulated. Also, the insulating material does not need to be silicon rubber, and a polymer insulator such as Kapton or polypropylene may be used. Regarding the electrode material, it is not always necessary to use stainless steel. For example, the collector electrode 9 may be formed by laminating a material printed on one side of polypropylene with conductive ink.

[0024]

As described above, according to the present invention, it is possible to provide an air purifying apparatus which realizes high dust collection efficiency, miniaturization and low pressure loss, and which can be reused by washing and has a low running cost. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic view of a first embodiment of an air cleaning device of the present invention.

FIG. 2 is a schematic view showing a general example of a conventional air cleaning device.

FIG. 3 is a perspective view of a second embodiment of the present invention.

FIG. 4 is a schematic view of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge electrode 2 Dust collecting electrode 3 Needle end 4 Power supply 4a Charging power supply 4b Collection power supply 5 Grounding 6 Charging part 7 Collection part 8 Counter electrode 9 Collection electrode 9a Upstream collection electrode 9b Downstream collection electrode DESCRIPTION OF SYMBOLS 10 Insulator 11 Pleated electrode 12 1st dust collecting electrode 14 Thickness of dust collecting part 15 Charging part and 1st stage dust collecting part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Moriyama 2-3-1-1, Nishinomiya-shi, Yukuhashi-shi, Fukuoka Yasukawa Control Co., Ltd. Yukihashi Plant (72) Inventor Hideki Aso 2--13, Nishinomiya-shi, Yukuhashi-shi, Fukuoka No. 1 Inside Yukikawa Control Co., Ltd. Yukihashi Plant (72) Inventor Yoji Sakui 2-3-1-1, Nishinomiya City, Yukuhashi City, Fukuoka Prefecture Inside Yasukawa Control Co., Ltd. Yukihashi Plant (72) Inventor Satoru Kodama Yukihashi City, Fukuoka Prefecture 2-13-1 Nishinomiya City Yasukawa Control Co., Ltd. Yukihashi Plant Examiner Shigehiro Toyonaga (56) References JP-A-2-273561 (JP, A) JP-A-3-72965 (JP, A) 3-98657 (JP, A) JP-A-64-51158 (JP, A) JP-A-58-24362 (JP, A) JP-A-58-73359 (JP, U) (58) Fields investigated (Int. C l. ⁷ , DB name) B03C 3/00-3/88

Claims (2)

(57) [Claims] 1. An air purifying apparatus comprising: a charging unit provided on an upstream side of a gas flow and a collecting unit provided on a downstream side; and a conductive or conductive substance is coated with an insulating material as a collecting unit. A plate-like material having air permeability is formed into a pleated shape such that the side surface of the plate-like material is continuously bent in a U-shape, and the bending angle of both sides forming the U-shape is 90 ° or less. This is arranged so as to be orthogonal to the gas flow, and at least one of the upstream side and the downstream side of the gas flow, with respect to the concave portion of the pleated formation, the pleated formation is made of an insulating material. When the coating is not applied, an electrode that extends in parallel to the flow direction of the gas flow obtained by coating the conductive material with an insulator is used when the pleated formation is coated with an insulator. Is a conductive substance or conductive An electrode that extends in parallel to the flow direction of the gas flow, which is made by coating an insulating material on an insulating material, inserts the electrode that extends in parallel to the flow direction of the gas flow. An air cleaning apparatus characterized in that a high voltage is applied between an electrode extending in parallel to the flow direction of the gas flow and a pleated electrode so as to have a polarity opposite to that of the air flow. 2. An electrode which extends parallel to the gas flow direction only from one of the upstream and downstream sides of the gas flow is inserted into the pleated electrode. 2. The air purifying apparatus according to claim 1, wherein a ventilation hole is not formed or the ventilation hole is closed at a tip of the pleated electrode that is not inserted.