JPH0763650B2 - Corona blower and electric dust collector using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is an apparatus for blowing gas by ionic wind. Further, this apparatus is used for blowing gas and precharging particles suspended in the gas. This is an apparatus for collecting the fine particles by providing a dust collecting section on the upper and lower sides thereof.

[Conventional technology]

In the conventional device of this type, a corona discharger is installed on the upstream side in a duct through which gas flows through a corona blower, and a porous counter electrode such as a wire mesh is disposed on the downstream side so that they are mutually insulated. A method has been proposed in which a high voltage is applied between both electrodes to generate a corona discharge from the corona discharge electrode toward the opposite electrode, and the gas in the duct is blown from the upstream side to the downstream side using the accompanying ion wind as a wind force. ing.

In addition, a dust collector such as an electrostatic precipitator composed of positive and negative parallel plate electrode groups is provided on the downstream side of such a corona blower,
It has been proposed to construct a dust collector by utilizing the corona blower for blowing the gas and precharging particles suspended in the gas.

In order to increase the motive force of ionic wind with these devices, it is necessary to increase the applied high voltage, but with this, the amount of ozone produced by corona discharge also increases, which is harmful to the human body. As a means for preventing this, the inventor of the present application has proposed a method of electrically heating the above corona discharge electrode to thermally decompose ozone (Pr
oc.IEEE-IAS 1979 Annual Meeting, pp.61-65),
Other similar proposals have been made (for example, Japanese Patent Laid-Open No.
60-114363).

[Problems to be solved by the invention]

In the method of electrically heating the above corona discharge electrode to thermally decompose ozone, this electrode is exposed to airflow and receives its cooling effect, so a large heating current is required to reach the required heating temperature. If the avoiding discharge electrode is made thin, it becomes easy to break due to the acceleration of oxidation by heating, and in order to obtain an effective ozone decomposition effect, the discharge electrode surface should be 300-500.
Although it has to be heated up to ℃, there is a problem that flammable materials such as fluff caught on the discharge electrode may be ignited, which has hindered its practical use.

[Means for solving problems]

This invention, the corona discharge electrode current heating type corona blower,
Or, in a dust collector using the same, the corona generating part of the corona discharge electrode is provided in the electrode part facing the gas flow downstream side, and the pole part other than the corona generating part is covered with a heat resistant covering material. . This solves all the above problems.

That is, according to the present invention, a corona discharge electrode is provided on the upstream side of a box through which gas passes, and a counter electrode that allows free flow of gas is provided on the downstream side so as to be insulated from each other, and a voltage is applied between both electrodes. A corona at the place where air is blown from the corona discharge electrode side to the counter electrode side by the ionic wind resulting from the corona discharge, which is provided with a high-voltage power supply for generating a corona discharge from the corona discharge electrode toward the counter electrode. In a discharge electrode heating type corona blower for electrically heating the corona discharge electrode, a corona discharge electrode has a sharp pointed needle-like protrusion or a thin strip-shaped conductor that generates corona discharge in the corona discharge electrode. The corona generating part such as the peripheral part is provided with an electrode part facing the downstream side of the gas flow, and the corona generating part facing the downstream including the part facing the gas flow of the corona discharge electrode and the side part. Resistant to parts other than Wherein the coating by gender coating material. In this case, the corona generating part is exposed toward the downstream counter electrode, and the other part is a suitable wiping material made of glass, glass fiber, ceramic, heat resistant plastic (eg Kapton) having heat resistance and insulation properties. It is preferable to wipe off the whole body with this, and this has the advantage that the heating energy can be greatly reduced and that the heated portion can be completely prevented from being ignited by touching flammable suspended matter.

Moreover, as the dust collecting portion arranged downstream of such a corona blower, any appropriate one can be used,
Particles pre-charged in the corona blower by the electric field formed between the parallel electrodes by installing a number of parallel electrodes parallel to the gas flow like parallel capacitors and insulating them next to each other and applying a voltage between them. The parallel condenser type dust collecting part for electrically collecting the parallel electrodes on the parallel electrodes is particularly preferable in that the pressure loss is small and the collection efficiency is high. The counter electrode can be replaced.

In addition, as the parallel condenser type collecting unit, the present inventor has another invention called "electrostatic precipitator" (Japanese Patent Application No. 53-14534).
Nos. 53-17413 and 53-61426), a positive and negative conductive layer is formed on both sides of the band-shaped insulating film and then wound into a spiral shape. Or, as the present inventor proposes in another invention, "electrostatic precipitator" (Japanese Patent Application No. 53-61472), it has an electrically conductive electrode plate and an insulating property and gas passage. The spacers are alternately arranged and a high voltage is applied between the adjacent electrode plates, or another invention of the inventor, the "electrostatic precipitator" (Japanese Patent Application No. 53-87319 and Japanese Patent Application No. 53-87319). Sho 53
-91560), a conductive layer is provided so that the conductive layer is exposed only on the central part of one surface of the insulating strip-shaped film, and non-conductive parts are formed on both sides of the conductive layer. When a group is used in which the conductive layers are laminated so that the conductive layers do not face each other through a spacer that allows gas to pass through, or a spirally wound coil is used to apply a voltage between the conductive layers of adjacent electrode elements, the electrode gap is reduced. It is especially suitable because it can improve the dust collection efficiency and can be made smaller and lighter.

[Work]

Corona discharge is made from the corona generating part provided on the downstream side of the electrically heated corona discharge electrode to the counter electrode at the downstream side, and the gas is passed through the box by the wind force of the ionic wind, which causes the corona discharge. The air is blown from the electrode toward the counter electrode. In this case, the corona discharge electrode is heated and the generation of ozone is suppressed. In addition, the corona discharge electrode other than the above corona generating part is wiped with a heat-resistant cloth to prevent heat from being dissipated into the gas flow and flammable substances such as flying fluff come into direct contact with the heated discharge electrode for ignition. Prevent from doing.

〔Example〕

The features of the present invention will be described with reference to Examples and the drawings. FIG. 1 is a longitudinal sectional view showing an example of a corona-type blower according to the present invention, and FIG. 2 is a perspective view of the corona discharge electrode part. In these figures, 1 is a duct through which gas flows, 2 is a gas inlet at its upstream end, and 3 is a gas outlet at its downstream end.
4 is a corona discharge electrode portion provided on the upstream side in the duct, and 5 is a metal supported by a collar-shaped insulator 6 on the downstream side thereof, which is insulated so as to interrupt the gas flow and allows free passage of gas. The reticulated counter electrode, 7 is an ion catcher provided downstream of the ion catcher for removing leaked ions and simultaneously removes suspended particles in the gas. Reference numerals 8 and 9 are protective wire meshes provided near the gas inlet 2 and the gas outlet 3 in the duct so as to block the gas flow and allow free flow of the gas. The corona discharge electrode portion 4 has a thin T having a protrusion 10 protruding downstream.
Heat-resistant insulator 11 in the shape of a letter 11, and two L-shaped foil-shaped or thin-film current-carrying conductors 1 embedded in the inside as shown in the figure
2, 13 and 12, 13 consists of heating wires 16 connected to tips 14 and 15 located in the protrusion 10, and 16 is bent as shown in the figure, and only the tip 17 of the heating wire 16 of the insulator protrusion 10 is formed. A corona generating portion is formed so as to be exposed from the downstream end edge portion 18 so as to face the counter electrode 5, and the portion of the heating element 16 other than 17 is embedded inside 10. The T-shaped heat-resistant insulator 11 may be made of glass or ceramic, but in this example, it is composed of two plastic films (for example, Kapton) 19 and 20 having thermal fusion property at high temperature, and between them. It is formed by inserting 12,13,16 into and then hot pressing 19 and 20. The terminals 21 and 22 at the upper and lower ends of the L-shaped current-carrying conductors 12 and 13 are connected to the DC or AC heating power source 25, which is grounded at one end, through the conductors 23 and 24, respectively, whereby the thin wire heating element 16 is electrically heated. The corona generating part 17 at the tip is kept at the required temperature. Further, a high voltage power supply is provided between the corona generating part 17 and the counter electrode 5 through the conductive wires 26, 27 and the insulating porcelain tube 28.
A high voltage is applied from 29, and a strong corona discharge is generated from the heated grounded corona generating part 17 toward the counter electrode 5 at a high potential, a large ion current flows, and a strong ion wind is generated. The generated wind force sucks the gas from the gas inlet 2, sends the gas in the duct 1 in the direction of the arrow 30, and discharges it from the gas outlet 3 to the outside. In this case, the high-voltage power supply 29 may be a DC power supply or an AC power supply, but when using a DC high-voltage power supply in which 17 is positive and 5 is negative, the amount of ozone generated in 17 can be suppressed to the lowest level. The ion catcher 7 has two sets of parallel plate electrode groups 31, 32, ...
, And 31 ', 32' ..., 31 ', 32', ... are grounded via the common conductor 33, 32, 32, ... are grounded once via the common conductor 34 and insulating porcelain tube 35 Is connected to the other end of the high voltage power supply 36.

Thus adjacent electrodes 31-31 ', 31'-32, 32-32', ...
A high voltage is applied between the electrodes, and the ions that have passed through the wire mesh counter electrode 5 are collected and removed on the electrodes by the electric field between the electrodes, and the ions are emitted from the gas outlet 3 to the outside to induce various electrostatic disturbances. Prevent from doing. In this case, the suspended particles in the gas are charged by the collision of the ion current flowing from the corona generating part 17 toward the counter electrode 5, pass through 5, and enter the ion catcher 7, and the coulomb is generated by the electric field between the electrodes. It receives force and is collected on the electrode. In this case, an AC power supply may be used as the high-voltage power supply 36, but when a DC power supply is used, it is preferable because the above-mentioned suspended particles as well as ions can be collected with extremely high efficiency.

Next, FIG. 3 is a horizontal sectional view of an example of a two-stage type electrostatic precipitator using a corona blower according to the present invention for blowing air and charging suspended particles in gas, and FIG. 4 is a vertical sectional view thereof. , Fifth
FIG. 6 is a perspective view of the corona discharge electrode portion 4 ', and FIG. 6 is a partial perspective view showing a more detailed structure of the corona generating portion 17. In the figure, the names and functions of the elements numbered 1 to 35 are the same as those of the elements of the same number in FIG. 37 is a dust collecting part having the same structure as the ion catcher 7 in FIG. 1, and 38 is a DC high-voltage power supply, which applies a DC high voltage between the parallel electrode groups 31, 32, ... A strong DC electric field is formed between the electrodes. However, in this case, the grounded electrode groups 31 ′, 32 ′, ...
Is also used as a counter electrode for the corona discharge electrode portion 4 to which a positive high voltage is applied to the ground by the DC high voltage power supply 39. In this example, the corona discharge electrode portion 4'is the sixth
As shown in the figure, a thin strip-shaped metal tape 42 is sandwiched between two tape-shaped films 40 and 41 of heat-resistant and heat-fusible plastic (eg Kapton), and as shown in the figure. Since one peripheral edge 43 of the metal tape 42 is on the same line as the peripheral edges 44, 45 of the tape-shaped heat-resistant plastic film 40, 41, without being covered by the films 40, 41, from between the peripheral edges 44, 45. It is exposed to the outside to form a corona generating part 17 in the shape of a sharp knife edge, and another peripheral edge 46 of the metal tape 42 is positioned so as to be retracted sufficiently inward from the other peripheral edges 47, 48 of the membranes 40, 41. In this manner, the films 40 and 41 are completely integrated with each other except for the peripheral edge 43 of the metal tape 42 by press-bonding the films 40 and 41 to each other at high temperature and heat-sealing them.
The other peripheral edge 46 of the insert 42 is not exposed to the outside. The long tape-shaped discharge electrode portion 4'constructed in this way has a knife blade-shaped corona generating portion as shown in FIG.
The zigzag-shaped windings are wound around the insulating holders 49, 49 ', ... made of upper and lower insulators so that 17 goes downstream, and fixed at both ends, and the surface of the adjacent discharge electrode portion 4'is the third. As shown in the figure, they are arranged on the cross section of the upstream portion of the duct 1 so as to be equidistant from each other and parallel to each other and parallel to the gas flow. And both ends 50, 51 of the metal tape 42 of the tape-shaped corona discharge electrode portion 4 '
Is connected to the secondary side of the insulating transformer 55 via the conductors 52, 53 and the insulator tube 54, and is heated by being supplied with an AC heating current from a primary side AC power supply 56. Moreover, the metal tape 42 is applied with a positive DC high voltage with respect to the ground by the DC high voltage power supply 39 through the conductors 57 and 53, and the long knife edge corona generating part 17 to the dust collecting part 37 is grounded. Electrode group 31 ', 32',
A strong positive corona discharge is made toward the upstream edges 31 ″, 32 ″ of ……, and a large amount of positive ions are supplied, and the gas is supplied by the arrow 30.
At the same time as the air is blown in the direction of, the particles suspended in the gas are strongly charged positively. These positive ions and positively charged fine particles enter between the electrode groups of the dust collecting part 37, and then the negative electrode groups 31 ′, 3
2 ', ... caught on. The gas that has been cleaned and capable of removing positive ions is released to the outside from the gas outlet 3. Since the tape-shaped corona discharge electrode portion 4'of this example is a long and flexible tape-shaped member, it is extremely easy to stretch it and the metal tape 42
However, since the parts other than the peripheral exposed part 17, which is the corona generating part, are embedded in the heat-resistant plastic film that can be heat-sealed with heat, it is sufficiently thermally insulated against the gas flow and can be heated sufficiently with a small amount of power consumption. It has the major feature that it is possible and, in addition, it is extremely safe.

FIG. 7 shows a horizontal sectional view of another example of an electrostatic precipitator using the corona blower according to the present invention for blowing air and charging suspended particles in gas. In this example, the tape-shaped corona discharge electrode portion 4'shown in FIGS. 3 to 6 is used as the corona discharge electrode portion.
The heating power source 25 is supplied with a heating current through the wires 52, 53 and the porcelain insulator 54.
The metal tape 42 and the corona generating part 17 are heated, but these are grounded via the conductor wire 53. The names and functions of the elements numbered from 1 to 51 in the figure are the same as those of the elements of the same number in the figures of FIGS. 1 to 6. Particularly in this example, the counter electrode 5'is composed of a group of metal rods perpendicular to the paper surface in order to reduce ventilation resistance.
It is supported by the collar-shaped insulator 6 and insulated so as to block the gas flow, and a negative high DC voltage is applied to the ground from the high voltage power supply 39 through the conductor 27 and the porcelain insulator 28, thereby grounding the tape. A strong positive corona is generated from the corona generating part 17 of the corona discharge electrode part 4'to the counter electrode 4 ', and the arrow 30
Direction, a strong ion wind is generated to blow the gas inside the duct 1, and the fine particles introduced with the gas flow into the duct 1 from the gas inlet 2 are strongly positively charged by the collision of positive ions. . Reference numeral 37 denotes a dust collecting portion, which is another invention of the present inventor already mentioned in this example, "electric dust collector" (Japanese Patent Application No.
53-87319 and Japanese Patent Application No. 53-91560) are used. That is, 58,58 ', 59,59',
…… is a plastic sheet that can be stacked with a small gap, and the conductive layers 58a, 58′a, 58a, 58'a,
59a, 59'a, ... are formed, and these conductive layers are formed so as to be slightly inward of both edges 60, 61 of each sheet so as to prevent corona generation at the edges. The conductive layers 58a are formed by connecting 33, 34, which are connected by the conductors 33, 34 every other adjacent line, to the DC high-voltage power supply 38 through the insulator 35.
Since a DC voltage is applied between −59a −... and 58′a−59′a−, a DC electric field is formed in the gas passage between the sheets 58, 58 ′, 59, 59 ′. , The charged fine particles that enter the inside with the gas flow from the left are immediately removed and deposited on the sheet by the Coulomb force. In this case, since the adjacent conductive layers do not come into contact with each other, a high voltage can be stably applied between the conductive layers even if the sheet interval is extremely small, and the dust collection performance can be greatly improved.

In addition, even if charged fine particles are deposited on one side of the plastic sheet without the conductive layer, the charge leaks to the conductive layer on the back side of the sheet due to the slight surface conductivity caused by the moisture adsorption layer which naturally occurs on the plastic surface. The phenomenon that the electric charge in the dust collection space between the sheets weakens with time and the dust collection performance deteriorates with time does not occur, because the electric charge is accumulated on the non-conductive side surface. The clean gas after the fine particles are removed is discharged from the gas outlet to the outside.

〔The invention's effect〕

According to the present invention, the configuration as described above significantly improves the air flow rate, substantially completely prevents the generation of ozone due to corona discharge, and significantly reduces the electric power for heating the corona discharge electrode. In addition, even if flammable airborne substances come in, it is possible to prevent their ignition completely.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of an embodiment of the present invention, and FIG. 2 is a perspective view of the corona discharge electrode part thereof. 3 is a horizontal sectional view of another embodiment of the present invention, FIG. 4 is its sectional view, FIG. 5 is a perspective view of the tape-shaped corona discharge electrode portion, and FIG. 6 is its tape-shaped corona discharge. It is a perspective view which shows the internal detail of an electrode. FIG. 7 is a horizontal sectional view of another embodiment of the present invention. 1 ... Duct 2 ... Gas inlet 3 ... Gas outlet 4 ... Corona discharge electrode 4 '... Tape-shaped corona discharge electrode 5,5' ... Counter electrode 7 ... Ion catcher 8, 9 ...... Wire mesh 12, 12 …… Conducting conductor 16 …… Fine wire heating element 17 …… Corona generating part 19, 20 …… Plastic film 25 …… Heating power supply 29,36 …… High voltage power supply 31,31 ', 32, 32'… … Parallel plate electrode group 37 …… Dust collector 38,39 …… High-voltage DC power supply 40,41 …… Heat-resistant plastic tape 42 …… Metal tape 58,58 ′, 59,59 ′ …… Plastic sheet 58a, 58 'A, 59a, 59'a ... Conductive layer

Claims (7)

[Claims] 1. A corona discharge electrode is provided on the upstream side of a box through which gas passes, and a counter electrode which allows free flow of gas is provided on the downstream side so as to be insulated from each other, and a voltage is applied between both electrodes. A high-voltage power supply for generating corona discharge from the corona discharge electrode toward the counter electrode is provided, and gas is blown from the corona discharge electrode side to the counter electrode side by ion wind accompanying the resulting corona discharge. A corona blower at a certain place, in a discharge electrode heating type corona blower provided with means for electrically heating the corona discharge electrode, the corona discharge part of the corona discharge electrode facing the downstream side of the gas flow. It is provided in the discharge electrode part, and the electrode parts other than the corona generating part, including the part facing the gas flow of the corona discharge electrode and the side part, are covered with a heat resistant covering material. Corona type Wind instrument. 2. The heat-resistant cloth material is two heat-resistant plastic tapes, the corona discharge electrode is a thin metal tape, and only the downstream peripheral edge thereof is exposed toward the counter electrode. The corona blower according to claim 1, characterized in that it is sandwiched between the two heat-resistant plastic tapes so as to form a corona generating portion, heat-sealed, and embedded between them. . 3. An ion removing section comprising parallel plate electrode groups arranged adjacent to each other in parallel with the upper gas flow, and provided in the downstream box of the counter electrode, and the adjacent electrode groups. The corona blower according to claim 1 or 2, further comprising a high-voltage power supply for applying a voltage therebetween. 4. A corona discharge electrode is provided on the upstream side of a box through which gas passes, and a counter electrode which allows free flow of gas is provided on the downstream side so as to be insulated from each other, and a voltage is applied between both electrodes. Then, a high-voltage power supply is provided to generate corona discharge from the corona discharge electrode toward the counter electrode, and the resulting ionic wind associated with the corona discharge blows gas from the corona discharge electrode side toward the counter electrode side. And a means for electrically heating the corona discharge electrode is provided, and the corona generating part is provided in the corona discharge electrode part facing the downstream side, and the part and the side surface facing the gas flow of the corona discharge electrode are provided. Including the parts, the electrode parts other than the corona generating part are covered with a heat-resistant cloth material in a corona-type blower, in the downstream box, parallel to the upper insulating gas flow adjacent to each other. From the parallel plate electrode group that can be arranged That electrostatic dust portion is provided, and an electrostatic precipitator, characterized in that a high-voltage power supply for applying a voltage between its Aitonaru electrode groups. 5. A parallel plate electrode group is insulated from each other adjacent to each other,
The electrostatic precipitator according to claim 4, comprising a group of metal plate electrodes arranged in parallel. 6. A parallel plate electrode group is an electrode group formed by laminating a plastic sheet having a conductive layer formed on one surface thereof with a distance therebetween so that the conductive layers do not face each other. The electric dust collector according to claim 4. 7. The electrostatic precipitator according to any one of claims 4 to 6, wherein the parallel plate electrode group also serves as the counter electrode at the upstream side edge portion. ..