JP5909629B2 - Electric dust collector - Google Patents

Description

  The present invention relates to an electrostatic precipitator used to collect particulate matter floating in the air, such as dust / dust, oil or water mist.

  Conventionally, this type of electrostatic precipitator is known as follows, and will be described with reference to FIG. 4 (see, for example, Patent Document 1).

  As shown in FIG. 4, a planar ground electrode plate 101 is provided in parallel with the air flow, and a discharge electrode 104 including a support 102 and a plurality of needle electrodes 103 is provided in parallel therewith. By supplying a high voltage to the discharge electrode 104, a corona discharge is generated between the ground electrode plate 101 and the discharge electrode 104, and airborne particulate matter is charged and collected.

  The ground electrode plate 101 is made of metal such as steel, stainless steel, or aluminum. In general, the needle-shaped electrode 103 is made of steel or stainless steel. However, in consideration of corrosion and corrosion resistance, metals such as titanium, iridium, platinum, rhodium, and tungsten, and alloys thereof may be used.

  At this time, the distance between the needle electrode 103 and the discharge electrode 104 on the ground electrode plate 30 is 30 mm, and the voltage applied to the needle electrode 103 is 18 kV.

JP 59-59258 A

  Such a conventional electrostatic precipitator has a problem that if the distance between the ground electrode plate and the discharge electrode is too narrow, spark discharge occurs frequently and the original dust collecting performance of the electrostatic precipitator cannot be obtained. Therefore, if the distance between the electrodes is increased (or the voltage applied to the discharge electrode is reduced), the problem can be solved, but the apparatus has to be enlarged in order to ensure the dust collection performance.

  The present invention solves such a conventional problem, and an object of the present invention is to provide an electric dust collector that does not generate a spark discharge and that can obtain a dust collection performance in a small size.

In order to achieve this object, the present invention provides a discharge electrode to which a high voltage is applied by a high-voltage power supply, and a plurality of ground electrodes alternately arranged at a certain distance facing the discharge electrode. The ground electrode is provided with a resistor on the surface of the insulating base so that the surface resistivity is 10 ⁶ Ω / □ to 10 ¹⁰ Ω / □, and the conductive member is in contact with a part of the resistor. Is an electrostatic precipitator equipped with a current monitoring means that is electrically connected to the ground, and generates a corona discharge between the discharge electrode and the ground electrode, and monitors the current flowing therewith. The application of a high voltage is controlled according to the current value detected in step 1, thereby achieving the initial purpose.

According to the present invention, a plurality of discharge electrodes to which a high voltage is applied by a high-voltage power supply and a plurality of ground electrodes that are arranged at a fixed distance so as to face the discharge electrodes are alternately arranged. A resistor is provided on the surface of the material so as to have a surface resistivity of 10 ⁶ Ω / □ to 10 ¹⁰ Ω / □, and the conductive member in contact with a part of the resistor is electrically connected to ground. An electrostatic precipitator equipped with a current monitoring means for monitoring a current flowing along with a corona discharge generated between the discharge electrode and the ground electrode, and a high current value detected by the current monitoring means. By controlling the application of voltage, even if the discharge electrode is brought close to the resistor of the ground electrode, no spark discharge occurs due to the resistance of the resistor. Further, since the resistor of the ground electrode plate and the discharge electrode can be brought close to each other, the size can be reduced, and high dust collection performance can be ensured.

  Furthermore, in the unlikely event that the distance between the resistor of the grounding electrode plate and the discharge electrode is closer or closer, the current monitoring means detects that the current has increased, and the application of a high voltage is detected. By controlling, the current flowing through the resistor can be suppressed and heat generation due to Joule heat in the resistor can be prevented, so that a safer electric dust collector can be provided.

1 is a system configuration diagram of an electric dust collector according to Embodiment 1 of the present invention. Perspective view showing the same charging unit Cross section of grounding electrode plate of the same charging unit The figure which shows the structure of the conventional electric dust collector

In the electrostatic precipitator according to claim 1 of the present invention, a plurality of discharge electrodes to which a high voltage is applied by a high-voltage power supply and a plurality of ground electrodes that are arranged at a fixed distance facing the discharge electrodes are alternately arranged. The ground electrode is provided with a resistor so as to have a surface resistivity of 10 ⁶ Ω / □ to 10 ¹⁰ Ω / □ on the surface of the insulative base, and is in contact with a part of the resistor. The member is an electric dust collector that is electrically connected to ground and generates a corona discharge between the discharge electrode and the ground electrode, wherein the resistor is tetraoxide in a binder containing silicon dioxide and aluminum oxide. Three irons are dispersed, provided with current monitoring means for monitoring the current flowing with corona discharge, and the application of high voltage is controlled by the amount of change in the current value detected by the current monitoring means It is. As a result, in a state in which the discharge electrode and the ground electrode resistors are arranged at a certain distance, corona discharge occurs, and the suspended particulate matter can be charged and collected, and the ground electrode resistor Spark discharge does not occur even if the discharge electrode is in close contact with the discharge electrode. Therefore, even if the distance between the discharge electrode and the resistor of the ground electrode is shortened or the voltage applied to the discharge electrode is increased, the spark discharge does not occur. It does not occur and dust collection performance can be improved.

  Further, the application of a high voltage may be controlled by the amount of change in current value per unit time. As a result, it is possible to distinguish between a case where the current changes gently and a case where the current changes suddenly, and it is possible to control the application of a high voltage according to the speed at which the current value changes.

Further, the resistor provided on the surface of the insulating base made of ceramics may include at least triiron tetroxide. As a result, the surface resistivity can be 10 ⁶ to 10 ¹⁰ Ω / □, corona discharge can be generated between the discharge electrode and the resistor, and the distance between the discharge electrode and the resistor can be reduced. Spark discharge does not occur, and it can be safely collected even in the case of collecting a combustible substance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
As shown in FIG. 1, the present embodiment includes an electric dust collector 3 including a charging unit 1 and a dust collecting unit 2, a high voltage power source 4 for applying a high voltage thereto, and current monitoring means. It comprises a certain ammeter 5, a control unit 6 for reading the value of the ammeter and controlling the high voltage power supply 4, and a lamp 7 which is a notification means capable of notifying the control unit 6 to the outside.

  As shown in FIG. 2, the charging unit 1 includes a discharge electrode 10 in which a plurality of needles 9 are fixed to a metal support member 8, a metal discharge electrode fixing member 11 that supports the discharge electrode 10, a metal frame 12, and the like. It is composed of a ceramic or resin insulator 13 for fixing the discharge electrode fixing member 11 while being electrically insulated, and a ground electrode 14 connected to the frame 12.

  In the present embodiment, the interval between the discharge electrode 10 and the ground electrode 14 is 20 mm, and the voltage applied to the discharge electrode 10 from the high-voltage power supply 4 is DC-7 to -11 kV. The ground electrode 14 is connected to the frame 12 via the conductive member 15, and the frame 12 is connected to the ground. When a high voltage is applied to the discharge electrode 10, the electric field concentrates on the tip of the needle 9 of the discharge electrode 10, and air near the tip of the needle 9 causes dielectric breakdown, generating corona discharge. Thereby, the particulate matter contained in the processing air can be charged. Note that the polarity of the applied voltage may be positive or negative.

  Although not shown in the drawings, the dust collector 2 is configured such that a load electrode plate to which a high voltage is applied and a ground electrode plate connected to the ground are alternately arranged at a distance (6 mm in this embodiment). It is. In the present embodiment, the voltage applied to the load electrode plate is the same as the voltage applied to the discharge electrode 10 of the charging unit 1, but may be a different voltage.

  The particulate matter charged by the charging unit 1 flies to the dust collecting unit 2 and is collected by the Coulomb force acting on the charged particles by the electric field between the load electrode plate and the ground electrode plate.

Here, the ground electrode 14 of the charging unit 1 will be described in detail. As shown in FIG. 3, the ground electrode 14 has a surface resistivity of 10 ⁶ to 10 ¹⁰ Ω / □, more preferably 10 ⁷ to 10 ⁹ Ω / □, on the surface of an insulating substrate 16 made of ceramics. The resistor 17 is provided so as to be. The resistor 17 has a configuration in which a resistor 17 is formed by applying and firing a slurry in which triiron tetroxide is mixed in a binder containing at least silicon dioxide and aluminum oxide.

By appropriately dispersing triiron tetroxide in the binder containing silicon dioxide and aluminum oxide, the surface resistivity of the resistor 17 can be in the range of 10 ⁶ to 10 ¹⁰ Ω / □. In order to obtain this surface resistivity, the resistor 17 is preferably mixed in a proportion of 40 to 60 wt% of triiron tetroxide with respect to the binder.

  Specifically, the resistor 17 is formed as follows. First, triiron tetroxide is added to a binder containing at least silicon dioxide and aluminum oxide and pulverized and mixed to prepare a slurry. The weight ratio between the binder and the triiron tetroxide is 40-60 wt% of the triiron tetroxide with respect to the binder. Next, the produced slurry is applied to the surface of the insulating substrate 16 by spraying. Thereafter, the insulating substrate 16 is fired at 1100 to 1200 ° C., and the resistor 17 is formed by melting the binder component. As a result, the ground electrode 14 is obtained in which the resistor 17 is firmly bonded to the surface of the insulating base 16.

  The insulating base 16 needs to withstand high temperatures in order to form the above-described resistor 17 on the surface thereof, and in this embodiment, ceramics used in ceramics, for example, tableware are used. Since the resistor 17 is also a ceramic formed by firing, the entire ground electrode 14 becomes an electrode made of ceramic, has high durability against current generated by corona discharge, ozone, and the like, and the quality is hardly deteriorated.

The reason why the surface resistivity of the resistor 17 is 10 ⁶ to 10 ¹⁰ Ω / □ is to prevent the occurrence of spark discharge at the same time as the generation of corona discharge. When the surface resistivity is lower than 10 ⁶ Ω / □, spark discharge occurs when the distance between the discharge electrode 10 and the ground electrode 14 is narrowed or when the voltage applied to the discharge electrode 10 is increased. Further, when the surface resistivity is higher than 10 ¹⁰ Ω / □, spark discharge does not occur, but corona discharge also does not occur, so that the particulate matter in the treated air cannot be charged. This will reduce the collection performance.

The ferric tetroxide contained in the resistor 17 has a characteristic that the volume resistivity decreases as the temperature rises. Therefore, when a large current flows, for example, when the discharge electrode 10 contacts the ground electrode 14, the surface resistivity of the ground electrode 14 decreases due to the generation of heat due to Joule heat, and the current increases. It has the feature that the current increases with time. In addition, Ti ₂ O ₃ , Ti ₄ O _7, etc. may be used as the substance whose resistivity decreases as the temperature rises.

  The results of experiments related to this are shown below.

As the ground electrode, a ceramic used for tableware or the like as an insulating base material is used, and a binder containing 45 wt% of triiron tetroxide is sintered on its surface to be 1.3 × 10 ⁸ Ω / □. A resistor was obtained.

  An aluminum tape using a conductive adhesive was affixed to one end of the ground electrode and connected to the ground. The aluminum tape and the aluminum tape up to a position of 10 mm were covered with an insulating film. Then, the tip of the acicular discharge electrode was brought into contact with a position 10 mm away from the aluminum tape, and a high voltage of −8 kV was applied.

  The results are shown in Table 1. Although it is 0.3 mA immediately after application, it can be seen that the current increases with time. After 5 seconds, it exceeded 2 mA, and the surface temperature near the discharge electrode contact at this time exceeded 250 ° C. That is, it can be said that the resistivity decreases with increasing temperature.

  This current increase is large with respect to the current (0.2 to 0.3 mA in the present embodiment) of the electrostatic precipitator that flows normally, and thus can be easily detected. In the present embodiment, the control unit 6 constantly monitors the value of the ammeter 5, and when the set value (for example, 1 mA) is exceeded, the high-voltage power supply 4 is stopped and control is performed so that application of a high voltage to the discharge electrode 10 is stopped. doing.

  As a result, even if the discharge electrode 10 and the ground electrode 14 are short-circuited or close to each other, the current rises and the ground electrode 14 continues to generate heat, the heat generation due to the current rise can be prevented in advance. For this reason, even if the material to be collected is flammable, it can be collected safely.

  Further, when the control for stopping the high-voltage power supply 4 is activated exceeding the set value, the lamp 7 as the notification means is turned on or flashes, and the control of the user of the electrostatic precipitator 3 is performed. I can inform you. As a result, it is possible to take an early response.

  Also, the current is constantly monitored by the ammeter 5, and the current value increases when the discharge electrode 10 is close to or in contact with the ground electrode 14, but the amount of change in the current value per unit time is determined and When exceeding, you may make it stop the application of the high voltage from the high voltage power supply 4 to the discharge electrode 10. FIG.

  As an example of the set value of the change amount of the current value, it can be stopped when the rising speed is 0.4 mA or more in 1 second. Thereby, the heat_generation | fever by the Joule heat of the ground electrode 14 surface can be prevented in advance.

  Next, in this Embodiment, the effect | action which can ensure high dust collection performance is demonstrated, making the electrostatic dust collector 3 small.

  In the charging unit 1, corona discharge is generated by the discharge electrode 10 and the resistor 17. Since the resistor 17 is configured as described above, the resistance value is sufficiently high, and the current that flows during discharge is limited, so that a large current that causes spark discharge does not flow. Therefore, the occurrence of spark discharge can be prevented.

  Since the spark discharge does not occur even when the discharge electrode 10 is brought close to the resistor 17, the distance between the discharge electrode 10 and the resistor 17 can be reduced (for example, the conventional 30 mm is made 15 to 20 mm). As a result, corona discharge becomes strong, and the size of the electrostatic precipitator 3 can be reduced without deteriorating the dust collection performance.

  In this embodiment, the application of the high voltage is stopped. However, the applied voltage may be decreased, and the current is also decreased as the voltage is decreased, so that an increase in heat generation can be suppressed.

  The electrostatic precipitator according to the present invention does not generate a spark discharge even when the discharge electrode and the ground electrode are brought close to each other, so that it is possible to ensure a small and high dust collection performance and to prevent heat generation at the ground electrode. Therefore, it is effective as an air cleaning method especially when a flammable substance is contained in the air, and is useful as an air cleaning device for a kitchen.

DESCRIPTION OF SYMBOLS 1 Charging part 2 Dust collection part 3 Electric dust collector 4 High voltage power supply 5 Ammeter 6 Control part 7 Lamp 8 Support member 9 Needle 10 Discharge electrode 11 Discharge electrode fixing member 12 Frame 13 Insulator 14 Ground electrode 15 Conductive member 16 Insulation Base material 17 Resistor 101 Ground electrode plate 102 Support body 103 Needle-shaped electrode 104 Discharge electrode

Claims (1)

A plurality of discharge electrodes to which a high voltage is applied by a high-voltage power supply and a plurality of ground electrodes arranged at a fixed distance so as to face the discharge electrodes are alternately arranged, and the ground electrodes are arranged on the surface of the insulating substrate. ^A resistor is provided so as to have a surface resistivity of ⁶ Ω / □ to 10 ¹⁰ Ω / □, and the conductive member in contact with a part of the resistor is electrically connected to ground, An electrostatic precipitator in which corona discharge is generated between the ground electrode and the resistor , wherein the resistor is obtained by dispersing triiron tetroxide in a binder containing silicon dioxide and aluminum oxide. current comprising a monitoring means, said current by the change amount of the current value detected by the monitoring means, electrical precipitator that controls the application of high voltage to monitor the current flowing.

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