JPS5960871A - Particle charger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corona charging device for imparting a strong charge to fine particles within a short period of time.

Conventionally, a corona discharge electrode in the form of a wire or a nailed rod is insulated and arranged inside a grounded cylindrical electrode along its central axis, and a high DC voltage is applied between the two to cause the corona discharge electrode to reach the inner wall of the cylindrical electrode. A direct current corona discharge was generated towards the target.

A concentric cylindrical corona charging device in which dust-containing gas is passed through this cylinder and ions generated by corona discharge collide with dust particles in the gas to charge them is well known and widely used. There is.

However, in this device, the applied voltage is increased to increase the average electric field strength Ef in the charged space between the two electrodes. E=5~6
If the value is increased above about 1.5 kV, sparks will be generated, so if this value is increased beyond this value, it will not be possible to obtain a spark. 5 mA/rn”
However, it was impossible to impart a strong charge to dust particles in a short period of time. This is because the saturation value of the amount of charge given to the particle is proportional to E, and the charging time constant is inversely proportional to J.

On the other hand, as a discharge electrode, as shown in FIG. In the center of the throat part 6 of the ground electrode 5 having
A column 7 is arranged coaxially with this, and a high DC voltage is applied between the two by a high voltage DC power source 8 to a discharge electrode 3. This device allows dust-containing gas to pass through the charged space between the circumference 2 and the throat portion 6 at a high speed of usually about 30 (m/s). 6 than 2
The dust particles are charged by the corona discharge toward the In this case, E>10(
KV/m), J = 20 (mA/rn"), which were able to stably form extremely high B and J values, making it possible to strongly charge dust particles in a short time. .

However, the dust particles to be collected by this device are extremely fine. When the mass average particle diameter becomes about 1 [μm] or less, dust is deposited on the upstream and downstream sides of the circumference 2 of the disc-shaped discharge electrode 3 where corona discharge should occur, and the dust is deposited on the circumference 2.
is buried in this deposited layer, and as a result, the generation of corona discharge is significantly suppressed, resulting in a major drawback in that the charging performance is greatly reduced. This tendency is associated with fine particles that have a strong tendency to resist adhesion. For example, this is particularly noticeable in the case of fine carbon particles in diesel engine exhaust, and therefore it is impossible to use the above-mentioned "high-intensity ionizer" to charge such ultra-fine particles. Ta.

The present invention solves this difficulty and makes it possible to impart a strong electric charge to any type of ultrafine particles within a short time while preventing the corona discharge from decreasing due to particle adhesion to the discharge electrode. The purpose of the present invention is to provide a novel corona charging device with improved performance. Therefore, the present invention achieves this objective by disposing a group of relatively short needle-like electrodes at equal intervals on the upper adjustment electrode.

This is achieved by using it as a corona discharge electrode.

That is, in this case, the inventor of the present application believes that (1) the extremely strong negative corona discharge that occurs at the tip of the needle electrode is due to the large Ronca effect caused by its own strong charging action and electric field concentration; (2) Particularly when the particulates are combustible particles such as carbon particles in diesel engine exhaust, the above-mentioned extremely strong negative electrode tip Active o3 caused by corona.
o English, 0. As a result of being oxidized to CO or CO2 by the oxidizing action of chemical species such as OH, the tip is always kept clean, and if this needle electrode group is replaced with the disk electrode,
They found that the effects of (1) and (2) above are significantly reduced, and particles are prevented from adhering to the corona discharge electrode, resulting in enlargement and a decrease in corona current.

That is, in the novel corona charging device according to the present invention, a cylindrical electric field adjustment electrode is disposed on an insulating support approximately at the central axis of a small-shaped non-corona counter electrode, and the electric field adjustment electrode A large number of relatively short needle-shaped corona discharge electrodes are radially projected from approximately the center of the electrode toward the inner surface of the non-corona facing electrode, and a negative DC high voltage is applied to the electric field adjustment electrode and the oblique corona discharge electrode. A strong negative corona discharge is generated from the tip of the needle-like corona discharge electrode toward the inner surface of the non-corona counter electrode, and the negative ions generated by this are caused to collide with fine particles that are introduced together with the gas flow between the two electrodes. It is characterized by being strongly charged within a short period of time, and by the action of a strong negative corona generated at the tip of the needle-like corona electrode, the tip is always kept clean.

However, the outer diameter d1 of the cylindrical electric field adjustment electrode is preferably set within a range of % to % of the inner diameter d2 of the grounded non-corona electrode of the rotationally irregular shape, and particularly preferably around %. Further, the length L of the cylindrical electric field adjustment electrode is preferably at least twice the outer diameter d1. In addition, the protrusion length h of the above-mentioned relatively short needle-like corona discharge electrode is 1. The outer diameter d of the cylindrical electric field adjustment electrode is
It is best to set it to 1% to %, especially around %.

The features of the present invention will now be explained in more detail with reference to examples and drawings. Figure 2 is a longitudinal sectional view of one embodiment of the present invention.

FIG. 3 shows a front view from the inlet end. In the figure, 9 is a grounded cylindrical counter electrode, 10 is a gas inlet, and 11 is a gas outlet. Reference numeral 12 denotes a cylindrical electric field adjustment electrode disposed concentrically along the central axis inside the cylindrical counter electrode, the upstream end 13 of which has a hemispherical shape, and approximately the center of which is arranged outwardly at equal intervals. A large number of relatively short needle-like corona discharge electrode groups 14 that can protrude radially are planted.

The electric field adjusting electrode 12 is fixedly supported at the upstream end of a ceramic insulating cylinder 15 which is also arranged along the central axis.

Further, the ceramic insulating cylinder 15 is gripped and fixed at its downstream end 16 by a cylindrical holding fitting 21 which is fixed to the inner wall of the cylindrical counter electrode 9 by means of four pillars 17, 18, 19, 20. The ceramic insulating cylinder 15 has a conductive film n formed by applying a conductive paint on its inner surface, and has an array of insulating insulating tubes integrated with this at its base n, and 24 is a cylindrical counter electrode. It penetrates through the wall of 9 and protrudes to the outside, and has a conductive wire 6 inside thereof connected to the conductive film n. Now, a DC high-voltage power source 8 is used to connect the electric field adjusting electrode 12 to the needle-like corona discharge electrode group 14 and the cylindrical counter electrode 9 via a conductor wire n, a terminal, a conductor wire, a conductive film n, and a ground conductor array.

When a high DC voltage is applied so that the former becomes negative, a strong negative corona discharge is generated from the tip of the needle-like corona discharge electrode group 14 toward the inner surface 4 of the cylindrical counter electrode 9 facing thereto,
Provides a large amount of negative ion current. In this case, as already mentioned, a significantly high electric field strength E of 10 (KVA-IrL) or more can be stably formed and maintained in the electric space concavity of the electric field adjustment electrode 12 (7p action and the corona discharge electrode sieve 2). The flowing negative ion current density J can also achieve an extremely large value of 20 (mA/rr?) or more.

When ions are supplied, the particles passing between 14 and 19 are bombarded with negative ions and are strongly negatively charged, as indicated by the arrow 32.
The gas flows in the direction shown in FIG. 1 and is supplied to the target device through the gas outlet 11. In this case, the outlet 11 is the inlet, and the inlet 10 is the inlet.
It goes without saying that the gas flow direction may be reversed with the outlet as the outlet. Now, to give an example of numerical values in this embodiment, the inner diameter d2 of the cylindrical counter electrode 9 is 47 (mm).
.

The outer diameter of the electric field adjustment electrode 12 and the ceramic insulating cylinder 15.

dl = 18 (mm) I Total length L of electric field adjustment electrode n
= 55 (mm).

The effective length of the ceramic insulating cylinder 15 is 160 (mm), the protrusion length h of the acicular corona discharge electrode 14 is 3 (mm), and the exhaust gas containing fine carbon particles from a diesel engine is introduced from the inlet 10 at a gas temperature of 40°C. time, average gas velocity v = 8 (m/s), spark voltage Vs = 18 (KV) (
E=12.4KVA-rrL) Lever l1ff current I
s=2(mA) (J=68mA/Tr?), and v=
A high charged space electric field strength and charged space current density of 32 (rr)/s) (J = 119 mA/m") were obtained, and the carbon particles passing through this had a theoretical A high charge equal to the saturation charge that can be reached is given.However, even during long-term continuous operation with diesel engine exhaust flowing through it, the adhesion-resistant thickness of the carbon particle layer on the surface of the ceramic insulating cylinder was t2 = 0.5 ( mm
), and the value of the leakage current at that time is Vs=18(
KV) when I/=0.3 (mA).

When Vs = 22 (KV), Ir = only 0.4 (mA), and the current was kept clean at all times, and no decrease in corona current due to carbon particle adhesion occurred.

The novel particle charging device according to the present invention includes an electrostatic precipitator, an electrostatic aggregation device for fine particles, an overflow dust collector that uses a bag filter-9 electrostatic field, an electrostatic powder coating device, and an electrostatic type It can be installed in front of or inside a pesticide spraying device or any processing device that requires charging fine particles, and can be used to charge fine particles.

Figure 4 shows a novel particle charging device 33 according to the present invention connected to a negative DC high voltage power source 35 arranged parallel to the gas flow inside the casing, and an insulated corona discharge electrode group. 2 is a vertical cross-sectional view of an embodiment used as a pre-charging device between an electrostatic precipitator consisting of a group of dust collecting electrodes 37 connected to a grounded dust collecting electrode group 37.

In the figure, dust particles entering along with the gas in the direction of arrow 31 are strongly negatively precharged by passing through the particle charging device 33, and are then precharged at the inlet 39 between the electrostatic precipitators.
Since more dust enters the dust collection space 40, the collection efficiency is significantly improved.

FIG. 5 shows a perspective view of an embodiment in which the novel particle charging device 33 according to the present invention is utilized as a pre-charging device for an electrostatic aggregation device 41 for fine particles. The dust particles entering together with the gas in the direction of the arrow 31 are strongly charged while passing through the particle charging device 33, and are introduced into the casing 43 at 41 from the inlet 42 into the flat plate electrode group 46 to which a positive DC high voltage is applied. are arranged facing each other, and a DC electric field is formed in the space between them. Therefore, the negatively charged fine particles introduced here are immediately collected by the Coulomb force on the grounded plate electrode group 44 of positive polarity to form a deposited layer. Now, when these electrode group materials 46 are mechanically hammered, the particulate layer is peeled off, and the large agglomerated and grown particles are supplied from the outlet 47 to the next stage of equipment, such as an electrostatic precipitator or a bag filter. This will greatly improve its performance.

FIG. 6 shows an embodiment in which the new particle charging device according to the present invention is used as it is as an electrostatic powder coating gun, in which a cylindrical counter electrode 49 is provided on the inner wall of the pointed end of the insulating cylinder 48 of the gun body. , an electric field adjustment electrode 50 and a needle-shaped corona discharge electrode group 5 are arranged on the central axis opposite to the guide shown in FIGS. 2 and 3.
1 is supported and disposed on an insulating cylinder 52.

i is a negative DC high voltage power supply, and from the output terminal 53, 1, for example -
A voltage of 50 KV is supplied between the cables and the insulating cylinder 52 between the electric field adjustment electrodes and to the acicular corona discharge electrode group 51, and from the output terminal 55 through the cables towards 9, for example -. A strong negative corona discharge is generated, and a charged space 57 is formed in the annular space between them. Now, when the paint powder is fed into the inlet 61 of the gun body 48 through the flexible vibrator ω by the air that can be forced by the blower 59 from between the storage tanks, the paint powder advances in the direction of the arrow 62. When passing through the charged space 57, the particles 9 are strongly negatively charged and ejected into the gun front area 63. In front of the gun is a grounded object to be painted, and a DC electric field is formed between the electrodes 49, 50 and the surface of the object, and the slightly charged paint powder is carried to the object and applied to its surface. However, the electrodes 49 and 50 have a structure that allows them to slide freely, and when they are retracted to the left, the front area 63 of the gun
The electric field weakens, and the charged paint powder is driven mainly by the space charge electric field formed by itself and sticks to it.

Figure 7 shows an electrostatic powder pesticide sprayer that uses the electrostatic powder coating gun shown in Figure 6 to spray powdered pesticides.

A novel particle charging device according to the present invention is installed coaxially at the tip of the long vibro 5. However, in this embodiment, one cylindrical counter electrode 49 is grounded by a conducting wire θ, as in the examples shown in FIGS. 2 and 3. Now, the powdered agricultural chemicals are stored in the storage tank 58 and transported by air to the base 6 of the long cylindrical vibro 5.
When the inside of 65 is transported in the direction of the arrow, 1
The grain escape rate is greatly reduced. In this case, instead of the sesame straight cylindrical vibro 5 shown in Fig. 6, a flexible small-diameter pipe similar to the mark is used, and the powder pesticide is supplied to the base 67 of <33 as shown in Fig. 6. Needless to say, it's a good thing.

FIG. 8 shows outlet 1 of a novel particle charging device 33 according to the present invention.
1 consists of an insulating flexible hose or straight cylindrical pipe that can be gripped and pulled at both ends, and has a number of ejection lowers 1, 71', 71'', . . . at regular intervals on its downward side.
This is a pesticide spraying machine formed by installing a spraying head 72 equipped with... Powdered agricultural chemicals are supplied from the storage tank to the base part 67 of the particle charging device 330 through the flexible vibro 0 by the air forced by the blower 59, where they are strongly charged and sent into the spraying head 72 in the direction of the arrow 73. entered,
Gushing lower 1. , 7]', 71", . . . are ejected downward. At this time, a part of the negative charge of the charged powder pesticide is given to the insulating spray head 72 itself, which is driven by the Ronka. 76 is an annular collar for rounding provided at the outlet of the particle charging device, which relaxes the electric field at the outlet 1 and removes the spraying head 72 which is at a high potential from 11. This prevents creeping corona discharge from occurring on the inner and outer surfaces of the capacitor and lowering its potential.

Reference numeral 77 is attached to the other end of the spraying head 72 to prevent electric shock from occurring, as well as to prevent creeping corona discharge from occurring toward the surface thereof. 8o is a single push.

A common DC high-voltage power supply 52 is used for the electric field adjustment electrode and the needle-like corona discharge electrode group of each particle charging device.
High voltage cable 82 to be connected to branch cable 83.8
3'.

83", . . . . A negative DC high voltage is supplied through the storage tank μs and the powdered pesticide is supplied by the air compressed by the blower 59 to the branching device via the flexible vibro 0. from which branch pipes 85.85', 85
“, . . . through each particle charging device 33, 33'
, 33",... are fed tangentially to the base of.

The needle-like corona discharge electrode group descends while swirling violently, and the negative ions hit by the negative corona discharge generate strong chaos 7.
The powdered pesticide spraying device shown in the figure is suitable for spraying on fruit trees, and those shown in Figures 8 and 9 are for soybeans and rice.

Suitable for spraying on wheat, etc.

[Brief explanation of drawings]

Figure 1 shows a longitudinal cross-sectional view of a conventional high inch city ionizer particle charging device. FIG. 2 is a longitudinal sectional view of one embodiment of the present invention, and FIG. 3 is a front view thereof. Fig. 4 is a longitudinal sectional view of an electrostatic precipitator using the present invention as a pre-charging device, and Fig. 5 is a perspective view showing the inside of a particulate electrostatic coagulation device using the present invention as a pre-charging device. Fig. 6 is a longitudinal cross-sectional view of a handgun for electrostatic powder coating to which the present invention can be applied, and Figs. FIG. The important elements in each diagram are as follows. l112・Seki・・・・・・・・・Cylindrical electric field adjustment electrode 3・・・・・・・・・・・・・・・・・・・・・
...... Disc-shaped corona discharge electrode 5 ......
・・・・・・・・・・・・・・・・・・・・・ Benchley type grounded counter electrode 8・A・45・・・・ High voltage DC power supply I4・51・・・・・・・・・・・・・・・・・・
...Acicular corona discharge electrode group 9,49...
・・・・・・・・・・・・ Cylindrical counter electrode 15
．． 57-・・・・・・・・・・・・・・・・・・
... Ceramic insulation cylinder 21 ...
・・・・・・・・・・・・・・・・・・・・・ Support metal fittings not included ・・・・・・・・・・・・・・・・・・・・・
・・・ Ceramic insulator tube n ・・・・・・・・・・・・
・・・・・・・・・・・・・・・Conductive film 33...
・・・・・・・・・・・・・・・・・・・・・・・・
Particle charging device■, 46・・・・・・・・・・・・・
・・・・・・Positive/negative plate electrode 54.56.82・・
・・・・・・・・・ High voltage cable ・・・・・・
・・・・・・・・・・・・・・・・・・・・・Powder storage tank 59 ・・・・・・・・・・・・・・・・・・・・・
・・・・・・Blower-60・・・・・・・・・・・・
・・・・・・・・・・・・・・・ Flexible pipe 72
・・・・・・・・・・・・・・・・・・・・・・・・
...Spraying head 85, 85', 85"...
・・・・・・Branch pipe 81 ・・・・・・・・・・・・
・・・・・・・・・・・・・・・ Support beam 78.
80・・・・・・・・・・・・・・・Gripper 76.77・・・・・・・・・・・・・・・・・・
・・ Boxwood 69.74・・・・・・・・・・・・・・・
...Target plant t. 70.75・・・・・・・・・・・・・・・・・・
・ Branches and above

Claims (1)

[Scope of Claims] 1. A grounded non-corona opposing electrode with a rotating pair of fine shapes, a cylindrical electric field adjustment electrode that is insulated and supported on the central axis of the electrode and concentrically opposed to the electrode, and the electric field adjustment A plurality of relatively short needle-shaped corona discharge electrodes are arranged on the circumference of the electrode at approximately the center thereof and are arranged at regular intervals so as to project radially toward the counter electrode. A strong DC electric field is formed between the corona opposing electrode, the electric field adjustment electrode, and the opposing electrodes located between the needle-like corona discharge electrode group, and a strong and stable electric field is generated from the needle-like corona discharge electrode group toward the opposing non-corona electrode. generating a negative corona discharge, causing a charged particulate matter to pass through the annular charged space between the negative corona discharges, and quickly and strongly charging the charged particulate matter negatively by the bombardment of negative ions supplied from the negative corona; A particle charging device characterized in that it is supplied externally. An integrally constructed insulator tube extends over the central axis of the counter electrode, is supported and fixed to the non-corona counter electrode at its base, and projects outward from the base in an L-shape through the non-corona counter electrode. A patented charging device characterized in that it uses an insulating cylinder having a section and a conductor for connecting a high voltage supply cable and an electric field adjustment electrode inside the insulating tube section. 3. The particle charging device according to claim 2, wherein the insulating cylinder is made of a ceramic insulating material. 4. The outer diameter d1 of the cylindrical electric field adjustment electrode is in the range of (3A) to (%) of the inner diameter d2 of the non-corona opposing electrode, and its length L is at least twice the outer diameter d1, and 3. A particle charging device according to claims 1 to 3, characterized in that the protrusion length h of the needle-like corona electrode is in the range of (%) to (%) of dl. 5. An electrostatic precipitator characterized in that the particle charging device according to claims 1, 2, and 3.4 is used as a precharging device. 6. The particle charging device according to claim 1, 2.3.4 is used as a pre-charging device, and a DC high voltage is applied between the positive and negative parallel plate electrode groups and the two electrodes. An electrostatic condensation device consisting of an applied power source. 7. A powder storage tank, a blower for pumping powder, and a transport pipe for pumping powder, characterized in that the particle charging device according to claims 1, 2, and 3.4 is used as a powder coating gun. Electrostatic powder coating equipment consisting of: 8. A patent characterized in that the non-corona opposing electrode has a DC high-voltage power source that provides a negative DC high voltage lower than that of the electric field adjustment electrode and the needle-like corona electrode. The electrostatic powder described in Box 7. Painting equipment. 9. A storage tank for powdered agricultural chemicals and a blower for pressure-feeding powdered agricultural chemicals, characterized in that the particle charging device according to claims 1.2 and 3.4 is used as a charging section for powdered agricultural chemicals. −. An electrostatic powder pesticide spraying device that has a transport pipe for pressure feeding. 10. The electrostatic powder according to claim 9, characterized in that a part of the most downstream part of the transportation pipe for force-feeding powdered agricultural chemicals is a holding part, and the particle charging device is installed at the tip of the holding part. Physical pesticide spraying device. 11. An electrostatic powder spraying head according to claim 9, characterized in that an elongated cylindrical spraying head having a plurality of spouting ports for powdery pesticide is attached to the outlet side of the particle charging device. 12. The electrostatic powder pesticide spraying device according to claim 11, wherein the cylindrical spraying head comprises an insulating flexible hose. 13. The electrostatic powder pesticide spraying device according to claim 11, wherein the cylindrical spraying head is comprised of an insulating straight cylindrical pipe. 14. The electrostatic powder pesticide spraying device according to claim 9, characterized in that a plurality of the particle charging devices are mounted in parallel on a support beam at regular intervals.