JP2010221175A - Electric dust collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim a large capacity of an electric dust collector by combining a plurality of small-sized high-tension circuits as a high-tension circuit of the electric dust collector for large facilities and making each dust collecting electrode independently insulated in order to prevent the interference in outputs of the high-tension circuits. <P>SOLUTION: In the electric dust collector, a diode 4 is inserted into each output of a plurality of high-tension circuits 1, and each output is one-point connected and connected to the dust collector, by which the interference in the outputs of the high-tension circuits is prevented to enable a parallel use of the plurality of high-tension circuits without insulation and independence. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric dust collector that collects atmospheric dust, indoor dust, dust and the like in air conditioning and industrial fields.

  2. Description of the Related Art Conventionally, an electrostatic precipitator that collects particles is composed of two electrodes that are a pair of a discharge electrode and a counter electrode, and a positive or negative high voltage is applied to the discharge electrode to ground the counter electrode. When a high voltage is applied between the discharge electrode and the counter electrode, the gas insulation between the electrodes is broken and a current flows. This is called corona discharge. When floating particles pass through the region where the corona discharge current flows, the particles and the electrons moving in the corona discharge region collide with each other, and the floating particles are charged. Charged suspended particles receive the force of an electric field formed by a high voltage applied between the discharge electrode and the counter electrode, and are attracted and adhered to the counter electrode, and the suspended particles are removed.

  It is generally known that the dust collection performance of an electric dust collector largely depends on the amount of corona discharge current for charging electrons to suspended particles. Therefore, the larger the electrostatic precipitator, the more corona discharge current is required. The larger the required amount of corona discharge current, the greater the capacity required for the high voltage circuit for generating a high voltage.

  In a large-scale electric dust collector for industrial equipment, various dust collection performances are required depending on the situation of the installation site. In some cases, the range of high-voltage output is specified according to the specifications and standards specific to the installation site. Therefore, the high-voltage power supply required for the electrostatic precipitator for large facilities is often a custom product that is manufactured at each design in order to meet the requirements of various installation sites. Will give.

  Also, between the discharge electrode and the counter electrode of the electrostatic precipitator, the insulation distance between the electrode plates is shortened due to distortion between the electrode plates, the accumulation of adhering dust, and the inclusion of conductive foreign matter. Sparks are generated by destruction or short circuit. Since the spark current flowing between the discharge electrode and the counter electrode plate when the spark is generated is proportional to the capacity of the high voltage power supply circuit, the value of the spark current increases as the power supply circuit capacity increases. During sparking, excessive current flows also in the high-voltage circuit, and it also applies electrical stress to the high-voltage circuit such as the high-voltage transformer and high-voltage components and the primary-side components of the high-voltage transformer. In view of this, it is considered that the smaller the high-voltage power supply circuit capacity is, the more desirable in order to reduce the spark current.

  Therefore, in order to solve the above-mentioned problems, in order to avoid the production of a custom high-voltage power supply for an electric dust collector for large facilities, it is necessary to use a combination of multiple small-sized high-voltage circuits that are available on the market. Therefore, the capacity of the high-voltage power supply is increased while eliminating the need for custom design and manufacturing, reducing the cost of the large-sized high-voltage power supply, shortening the delivery time, reducing the spark current, and reducing the electrical stress of circuit components due to the spark current. How to do is being studied.

  Conventionally, as such a high-voltage power supply for a large electrostatic precipitator, as a method of using a plurality of small general-purpose high-voltage circuits, there is an electrostatic precipitator as shown in FIG.

  The electrostatic precipitator shown in FIG. 4 applies an insulating means 102 that insulates and separates a plurality of sets of electrode plates 101 arranged in parallel in the electrostatic precipitator, and applies a high voltage to each of the independent electrode plates. High-voltage circuit dispersing means 103.

By making each electrode plate set 101 insulated and independent from other electrode plate sets, a high voltage can be applied without the output of each high-voltage circuit dispersing means 103 interfering with the output of the other high-voltage circuit distributing means. If a discharge due to spark or contact occurs in this state, a transient current flows between the plates where the spark occurred, but the other high-voltage circuits are smaller because the capacity of the high-voltage circuit itself is small and each electrode is insulated and independent. Therefore, the transient current value can be suppressed to a very low level. Therefore, while satisfying the requirements of the layer current required for the dust collector, it is possible to avoid the high cost and long delivery time of the high voltage circuit by customization, and further reduce the stress to the high voltage circuit at the time of spark occurrence (for example, Patent Document 1).
JP 2006-272127 A

  In such a method of using a combination of conventional high-voltage power supply circuits in a distributed manner, the combination of one discharge electrode and the counter electrode is isolated from the combination of the other electrodes in order to avoid interference between outputs of the high-voltage power supply circuits. There is a problem that dust collection performance may be reduced by creating a space that does not contribute to dust collection inside the dust collector when performing the insulation treatment.

  Therefore, there is a demand for an electrostatic precipitator that does not require insulation treatment of each electrode combination even when a plurality of high-voltage circuits are used in parallel.

  Also, when connecting the output of multiple high voltage circuits to the discharge electrode, if the connection is made as it is, the applied voltage is reduced by the flow of current (hereinafter circulating current) flowing from one high voltage circuit to another due to variations in the output impedance of the high voltage circuit. This causes a problem that the rated voltage cannot be applied to the load and power is wasted due to the circulating current.

  Therefore, by arranging the semiconductor in the previous stage connected to one point, it is possible to limit the direction of current flow, prevent the generation of circulating current due to the difference in output impedance, and prevent wasteful power consumption while maintaining the output voltage.

  For semiconductors, either a diode that considers the rated voltage in consideration of the applied voltage (hereinafter referred to as a high voltage diode), or a diode that guarantees a withstand voltage by another method without considering the rated voltage (hereinafter referred to as low voltage diode) By limiting the direction of current flow to the output direction only, it is possible to prevent wasteful power consumption while maintaining the output voltage.

  When using a diode, place the diode in an insulation case and insert it between the high-voltage output cables, and ensure insulation between the diode element and the ground, so that the low-voltage diode is inserted in series with the high-voltage output. Can do.

  When a spark occurs between the discharge electrode and the counter electrode, a transient large current flows due to resonance of the capacitance and inductance components existing between the discharge electrode and the counter electrode. This transient resonance current often vibrates at a frequency of 1 kHz or more, and there is a problem that the transient current may flow back to the high voltage circuit depending on the frequency characteristics of the diode.

  Therefore, by selecting a diode having a frequency characteristic of 1 kHz or more, it is possible to prevent a backflow of a transient current during sparking to the high voltage circuit and to prevent electrical stress to the high voltage circuit.

  In addition, by inserting a constant voltage diode in parallel with the discharge electrode and the counter electrode after the inserted diode, and using the constant voltage diode as a bypass route for passing a transient current due to spark, the transient current flowing to the inserted diode can be reduced. This can reduce the stress on the diode itself.

  In addition, by inserting a current limiting resistor between the subsequent stage of the inserted diode and the discharge electrode, it is possible to prevent high voltage from being applied to the inserted diode when the discharge electrode and the counter electrode are completely short-circuited. .

  The present invention solves such a conventional problem, and in a conventional method of dispersing a high-voltage power supply circuit, a dust collection load is changed from a combination of one discharge electrode and a counter electrode to another electrode combination. An object of the present invention is to provide an electrostatic precipitator that can be made independent of insulation.

  In addition, by placing a semiconductor in the previous stage that connects each high-voltage output to a single point, it limits the direction of current flow, prevents the generation of circulating current due to the difference in output impedance, and prevents wasteful power consumption while maintaining the output voltage. The purpose is that.

  For semiconductors, either a diode that takes into account the applied voltage or the rated voltage is considered, or a diode that guarantees the withstand voltage without taking into account the rated voltage, and the current flows only in the output direction. The purpose of this is to prevent wasteful power consumption while maintaining the output voltage.

  Also, when using a diode, it is possible to insert a diode in an insulation case and insert it between high-voltage output cables to ensure insulation between the diode element and the ground, and use a low-voltage diode in series with the high-voltage output. it can.

  In addition, by selecting a diode with a frequency characteristic of 1 kHz or more against the spark transient current generated between the discharge electrode and the counter electrode, the backflow of the transient current to the high voltage circuit during sparking can be prevented and The purpose is to prevent electrical stress.

  In addition, by inserting a constant voltage diode in parallel with the discharge electrode and the counter electrode after the inserted diode, and using the constant voltage diode as a bypass route for passing a transient current due to spark, a transient current flowing to the inserted diode The purpose is to reduce the stress and prevent stress on the diode itself.

  Also, by inserting a current limiting resistor between the subsequent stage of the inserted diode and the discharge electrode, it is possible to prevent high voltage from being applied to the inserted diode when the discharge electrode and the counter electrode are completely short-circuited. It is aimed.

  In order to achieve the above object, the electric dust collector of the present invention comprises a plurality of high voltage applying means and a dust collecting means constituted by a discharge electrode and a counter electrode, and the high voltage output of the plurality of high voltage applying means is provided. One point of connection is connected to the discharge electrode.

  According to the present invention, it is possible to eliminate the need to insulate the dust collection load from the combination of one discharge electrode and the counter electrode from the combination of the other electrodes by a conventional method of dispersing high-voltage power supply circuits. A dust collector is obtained.

  Further, in all the outputs of the plurality of high voltage applying means, a semiconductor is inserted before the high voltage output is connected at one point.

  According to the present invention, by arranging the semiconductor in the previous stage that connects each high-voltage output to a single point, the direction of current flow is limited, the generation of circulating current due to the difference in output impedance is prevented, and the output voltage is maintained while being wasted. It is possible to obtain an electric dust collector capable of preventing a large amount of power consumption.

  The semiconductor is a diode having a high or low breakdown voltage.

  According to the present invention, by using a diode and restricting the direction of current flow only to the output side direction, it is possible to obtain an electrostatic precipitator that can prevent wasteful power consumption while maintaining the output voltage.

  Further, when an element having a withstand voltage lower than the high-voltage output rated voltage is used for the semiconductor, the semiconductor is housed in an insulating case, and the insulating case is inserted between output high-voltage cables.

  According to the present invention, when a diode is used, the low voltage diode is inserted in series with the high voltage output by placing the diode in an insulation case and inserting it between the high voltage output cables to ensure insulation between the diode element and the ground. Thus, an electric dust collector can be obtained.

  The diode to be used is an element having a frequency characteristic of 1 kHz or more.

  According to the present invention, by selecting a diode having a frequency characteristic of 1 kHz or more with respect to the spark transient current generated between the discharge electrode and the counter electrode, the reverse current of the transient current to the high-voltage circuit during sparking is selected. Thus, an electric dust collector capable of preventing electrical stress on the high-voltage circuit can be obtained.

  Further, a constant voltage diode is arranged in parallel with the discharge electrode and the counter electrode in the subsequent stage of the installed diode.

  According to the present invention, a constant voltage diode is inserted in parallel with the discharge electrode and the counter electrode after the inserted diode, and the constant voltage diode is used as a bypass route for passing a transient current due to sparks. Thus, an electrostatic precipitator can be obtained that can reduce the transient current flowing through and prevent stress on the diode itself.

  Further, a current limiting resistor is arranged between the high voltage applied output one point connection point and the discharge electrode.

  According to the present invention, by inserting a current limiting resistor between the subsequent stage of the inserted diode and the discharge electrode, a high voltage full voltage is applied to the inserted diode when the discharge electrode and the counter electrode are completely short-circuited. An electric dust collector capable of preventing the occurrence of the problem is obtained.

  According to the present invention, by inserting a diode into each output of a plurality of high-voltage circuits, interference between outputs of each high-voltage circuit can be prevented, and each discharge electrode and the counter electrode can be made independent of the other electrodes. A dust device can be provided.

  In order to achieve the above object, the invention according to claim 1 of the present invention includes a plurality of high voltage applying means, and a dust collecting means constituted by a discharge electrode and a counter electrode. The high-voltage output is connected to the discharge electrode at a single point, and the conventional high-voltage power supply circuit is distributed, and the dust collection load is combined with one discharge electrode and the counter electrode. It has the effect that it is not necessary to make the insulation independent from the combination of the electrodes.

  The invention described in claim 2 of the present invention is characterized in that, in order to achieve the above object, a semiconductor is inserted in a stage before one point connection of a high voltage output in all outputs of a plurality of high voltage applying means. Yes, by placing a semiconductor in the previous stage that connects each high-voltage output to a single point, it limits the direction of current flow, prevents the generation of circulating current due to the difference in output impedance, and consumes unnecessary power while maintaining the output voltage. It has the effect that it can be prevented.

  In order to achieve the above object, the invention according to claims 3, 4 and 5 is characterized in that the semiconductor is a high breakdown voltage or low breakdown voltage diode. By restricting the flowing direction only to the output side direction, there is an effect that wasteful power consumption can be prevented while maintaining the output voltage.

  According to a sixth aspect of the present invention, in order to achieve the above object, when an element having a withstand voltage less than the high voltage output rated voltage is used for the semiconductor, the semiconductor is accommodated in an insulating case, and the insulating case is placed between the output high voltage cables. When using a diode, place the diode in an insulation case and insert it between the high-voltage output cables to ensure insulation between the diode element and the ground. It has the effect that it can be used by being inserted in series with the output.

  The invention according to claim 7 of the present invention is characterized in that an element having a frequency characteristic of 1 kHz or more is used as a diode to be used in order to achieve the above object, and between the discharge electrode and the counter electrode. By selecting a diode with a frequency characteristic of 1 kHz or higher for the spark transient current generated in the process, it is possible to prevent the transient current from flowing back to the high-voltage circuit and prevent electrical stress to the high-voltage circuit. Has the effect of being able to.

  In order to achieve the above object, the invention according to claim 8 is characterized in that a constant voltage diode is arranged in parallel with the discharge electrode and the counter electrode in the subsequent stage of the installed diode. By inserting a constant voltage diode in parallel with the discharge electrode and the counter electrode at the subsequent stage of the diode, and using the constant voltage diode as a bypass route for flowing transient current due to spark, the transient current flowing to the inserted diode is reduced, It has the effect that stress on the diode itself can be prevented.

  According to a ninth aspect of the present invention, in order to achieve the above object, a current limiting resistor is arranged between the high voltage applied output single point connection point and the discharge electrode, and the inserted diode By inserting a current limiting resistor between the subsequent stage and the discharge electrode, it is possible to prevent a high-voltage full voltage from being applied to the inserted diode when the discharge electrode and the counter electrode are completely short-circuited. .

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

(Embodiment 1)
FIG. 1 shows the configuration of an electrostatic precipitator according to Embodiment 1 of the present invention. As shown in FIG. 1, a plurality of high voltage circuits 1 as high voltage applying means, a discharge electrode 2 and a counter electrode 3 as dust collecting means, and a diode 4 as a semiconductor.

  The diodes 4 are inserted into the output stages of the plurality of high voltage circuits 1, respectively. The output of the high voltage applying means is connected at one point in the subsequent stage (cathode) of these diodes 4 and connected to the discharge electrode 2.

  The high-voltage circuit 1 has an output impedance difference. When the diode 4 is not provided, a potential difference is generated between the outputs of the high voltage circuit due to the impedance difference, and current flows from the higher output impedance to the lower output impedance. When this circulating current flows, the high-voltage output voltage after one point connection is lowered.

  In addition, it is said that the larger the discharge current flowing between the discharge electrode 2 and the counter electrode 3 is, the higher the dust collection performance is. However, since this circulating current flows in a different route regardless of the discharge current, the dust collection performance. It will only be consumed without contributing. The greater the impedance difference, the lower the applied voltage and the greater the circulating current.

  Therefore, the diode 4 is inserted into the output stage of the high-voltage circuit 1 before the one-point connection. Due to the action of the diode 4, current does not flow backward from the discharge electrode 2 to the high voltage circuit side, and generation of circulating current can be prevented, thereby preventing wasteful power consumption while preventing a decrease in applied voltage.

  When a high voltage diode is used for the diode 4, it is not necessary to consider special insulation even if it is arranged on the high voltage side because the diode itself has a withstand voltage, but high voltage products are expensive and available due to their special characteristics. There is an aspect that is not good. Therefore, we will consider using low-voltage diodes that are inexpensive and widely available.

  A low-voltage diode is placed in an insulation case to ensure insulation from the ground, and is inserted in the middle of a high-voltage cable connecting each output of the high-voltage circuit 1 and the discharge electrode 2. The insertion position is inserted between each output point of the high voltage circuit 1 and one point connection.

  As for the discharge current flowing between the discharge electrode 2 and the counter electrode 3, even if it is a large electrostatic precipitator, the current value required from the height of the applied voltage is almost a current value on the order of mA. Therefore, if insulation from the ground can be secured, a general-purpose low-voltage diode can be used because the forward current is low. Here, a method of putting the diode 4 in an insulating case and sandwiching it between high-voltage cables is presented. However, if there is a method that can ensure insulation between the diode 4 and the ground even on the high-voltage circuit board, the method can be implemented. no problem.

  When a spark is generated between the discharge electrode 2 and the counter electrode 3, a transient large current flows for a short time. This transient current is a resonance current composed of an electrostatic capacitance existing between the discharge electrode 2 and the counter electrode 3, and an inductance component in the cable connecting the high voltage circuit 1, the discharge electrode 2, and the counter electrode 3. The peak current value is several tens of times the rated current. This transient current has a property of damped oscillation within a time of the order of μsec. Since this transient current is an oscillating current, the current flows alternately from the load side to the high voltage circuit side, so that the peak value is high, so the high voltage circuit and the primary side low voltage circuit via the high voltage transformer are also electrically connected. Stress. By selecting an element having a high frequency characteristic as the diode 4 used this time and selecting a frequency characteristic having a frequency of 1 kHz or more, it is possible to cope with the oscillation cycle of the transient current. Since the diode 4 corresponds to the oscillation period of the transient current, it is possible to prevent the spark transient current from flowing backward to the load side, and to reduce stress on the high-voltage circuit and the primary-side low-voltage circuit.

(Embodiment 2)
FIG. 2 shows the configuration of an electrostatic precipitator according to Embodiment 2 of the present invention. As shown in FIG. 2, the high voltage application means is composed of a plurality of high voltage circuits 1, a discharge electrode 2 and a counter electrode 3 as dust collection means, a diode 4 as a semiconductor, and a constant voltage diode 6.

  The constant voltage diode 6 is inserted in parallel with the discharge electrode 2 and the counter electrode 3 between the one-point connection point of each output of the high-voltage circuit 1 and the discharge electrode 2.

  By inserting the constant voltage diode 6, the transient current generated at the time of sparking flows the current flowing in the diode 4 to the constant voltage diode 6 to be consumed. As a result, the transient current flowing through the diode 4 can be alleviated, the electrical stress on the diode 4 can be reduced, and the electrical load on the diode 4 can be reduced, thereby further improving the backflow prevention effect of the transient current expected for the diode 4. Can be increased.

  Although the use of a constant voltage diode is presented here, any semiconductor can be used as long as it has a similar function. Further, depending on the voltage value applied between the discharge electrode 2 and the counter electrode 3, it may be difficult to realize with one constant voltage diode. In this case, it is possible to cope with a high applied voltage by connecting a plurality of constant voltage diodes in series.

(Embodiment 3)
FIG. 3 shows the configuration of an electrostatic precipitator according to Embodiment 3 of the present invention. As shown in FIG. 3, it is composed of a plurality of high voltage circuits 1 as high voltage applying means, a discharge electrode 2 and a counter electrode 3 as dust collecting means, a diode 4 as a semiconductor, a constant voltage diode 6, and a current limiting resistor 7. Yes.

  As shown in FIG. 3, a current limiting resistor 7 is inserted between the output connection point of each output of the high voltage circuit 1 and the discharge electrode 2. When the discharge electrode 2 and the counter electrode 3 are completely short-circuited due to the inclusion of conductive foreign matter or the like, the applied voltage may be applied to the diode 4 if there is no resistance component in the high-voltage circuit output. Therefore, if the current limiting resistor 7 is inserted, the applied voltage is shared by the current limiting resistor 7 even when the discharge electrode 2 and the counter electrode 3 are completely short-circuited, so that it is possible to prevent the applied voltage from being applied to the diode 4. it can. Note that it is necessary to select the specifications of the current limiting resistor 7 in consideration of the fact that all voltages are applied to both ends.

  The current limiting resistor 7 may be arranged at any part of the high voltage circuit for the purpose of preventing the application of the full voltage to the diode 4 when the discharge electrode 2 and the counter electrode 3 are short-circuited. The current limiting resistor 7 consumes a transient current at the time of sparking, and the burden on the diode 4 is reduced. Therefore, the diode 4 and the high-voltage circuit are more stress-reduced by arranging them at the subsequent stage of the diode 4. High effect.

  The present invention can be applied to a large electrostatic precipitator that collects suspended particles.

1 is a configuration diagram of an electric dust collector according to an embodiment of the present invention. 1 is a configuration diagram of an electric dust collector according to an embodiment of the present invention. 1 is a configuration diagram of an electric dust collector according to an embodiment of the present invention. Configuration diagram of conventional electric dust collector

DESCRIPTION OF SYMBOLS 1 High voltage circuit 2 Discharge electrode 3 Counter electrode 4 Diode 5 Insulation case 6 Constant voltage diode 7 Current limiting resistance

Claims (9)

An electric dust collector comprising: a plurality of high voltage applying means; and a dust collecting means composed of a discharge electrode and a counter electrode, wherein the high voltage outputs of the plurality of high voltage applying means are connected at one point and connected to the discharge electrode. apparatus. 2. The electrostatic precipitator according to claim 1, wherein a semiconductor is inserted in a stage before connection of one point of the high voltage output in all the outputs of the plurality of high voltage applying means. The electrostatic precipitator according to claim 1, wherein the semiconductor is a diode. The electrostatic precipitator according to any one of claims 1 to 3, wherein an element having a breakdown voltage equal to or higher than a high-voltage rated output voltage is used for the semiconductor. The electrostatic precipitator according to any one of claims 1 to 3, wherein an element having a withstand voltage lower than a high-voltage output rated voltage is used for the semiconductor. 6. When using an element having a withstand voltage lower than a high-voltage output rated voltage for a semiconductor, the semiconductor is housed in an insulating case, and the insulating case is inserted between output high-voltage cables. The electric dust collector as described. The electrostatic precipitator according to any one of claims 1 to 6, wherein an element having a frequency characteristic of 1 kHz or more is used as a diode to be used.  The electrostatic precipitator according to any one of claims 1 to 7, wherein a constant voltage diode is arranged in parallel with the discharge electrode and the counter electrode in a subsequent stage of the installed diode. 9. The electrostatic precipitator according to any one of claims 1 to 8, wherein a current limiting resistor is disposed between the high voltage applied output single point connection point and the discharge electrode.

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