JPH0731901A - Collector power source - Google Patents

Abstract

PURPOSE:To maintain high dot collecting efficiency by providing a means for keeping the output voltage at a constant value until the output current increasing with an increase in the amt. of dust collected by a collector is increased to a specified value in the output stage. CONSTITUTION:An ionizer power source terminal 2 to impress a corona discharge generating voltage on an ionizer is led out from a DC high-voltage power source 1, voltage dividing resistances R1 and R2 are connected in series between an output line to the terminal 2 and a grounding line 5, and a collector power source terminal 3 is connected to a voltage dividing point D. A constant- voltage circuit 4, in which Zener diodes 4a, 4b and 4c are connected in series, is connected between the terminal 3 and grounding wire 5 as a constant-voltage means. A leak is started due to the dust attracted to the collector by the operation of an electrostatic precipitator to increase the output current, however the output voltage is kept at a constant value by the partial constant output characteristic to a point A where the output current is increased to a specified value. The Zener effect of the circuit 4 is lost beyond the point A, and the output voltage is linearly attenuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collector power source for an electrostatic precipitator, which is capable of maintaining high dust collecting efficiency.

[0002]

2. Description of the Related Art In an electrostatic precipitator, as its main function part, corona discharge is generated between a discharge electrode and a discharge counter electrode (earth electrode), and the corona discharge charges (ionizes) dust in the air. An ionizer (charging unit) and a collector (dust collecting electrode) that collects dust by electrostatically attracting the charged dust are provided. In order to improve the discharge performance, a needle electrode, a metal thin wire (ionization wire), or the like is used for the discharge electrode of the ionizer, and the collector has at least 1
A pair of positive and negative electrodes are used.

Here, a high voltage power supply having required output characteristics is used for the ionizer and the collector. Among these, as the collector power supply, what is conventionally called a "resistance limiting system" is basically used. FIG. 3 shows the output characteristic of the collector power supply of this system. The output voltage linearly attenuates as the output current increases. This is because when the electric dust collector is operated and dust is collected in the collector and dust with low insulation is collected in the dust, the insulation resistance value of the dust decreases and a current (leakage current) flows out. The output voltage decreases due to the internal impedance of the power supply as the current increases.

The dust collecting efficiency of the electrostatic precipitator depends on the ionizer current for ionization in the ionizer and the voltage applied to the collector. For the collector, the dust collecting efficiency is almost proportional to the collector voltage. . That is, if the collector voltage decreases, the dust collection efficiency also decreases.

[0005]

In the conventional collector power supply, dust adsorbed on the collector causes leakage, and when the output current increases, the output voltage linearly decays accordingly. Therefore, the electric dust collector cannot maintain the initial dust collection efficiency, and there is a problem that the dust collection efficiency decreases as the output current increases.

Therefore, an object of the present invention is to provide a collector power supply which can maintain high dust collection efficiency.

[0007]

In order to solve the above-mentioned problems, the present invention firstly requires that an ionizer generates corona discharge to charge dust in the air, and the charged dust in the air is discharged. A collector power supply for applying a required electric potential to the collector in an electrostatic precipitator that electrostatically collects dust on the collector to which a required electric potential is applied, and an output that increases with an increase in the amount of collected dust to the collector. The gist is that constant voltage means for holding the output voltage at a constant voltage is provided in the output stage until the current reaches a constant value.

Secondly, the gist of the first structure is that the constant voltage means is formed by connecting a plurality of zener diodes in series.

Thirdly, it is a summary that the collector power source of the first configuration is integrally formed with an ionizer power source for applying a voltage for generating a corona discharge to the ionizer.

[0010]

In the above structure, firstly, the dust collection efficiency of the electrostatic precipitator depends on the output voltage of the collector power supply, and the dust collection efficiency and the output voltage are substantially proportional to each other. Even if the output current increases with an increase in the amount of collected dust, the output voltage is kept at a constant voltage until it reaches a constant value, so that high dust collection efficiency in the initial stage is maintained.

Secondly, the constant voltage means is constituted by connecting a plurality of Zener diodes in series, so that as the output current increases, the output voltage of the output voltage is increased by the internal impedance of the DC high voltage power source in the preceding stage of the constant voltage means. It is possible to appropriately realize the output characteristic that the output voltage is held at a constant voltage until the output current increases to a constant value even if the tendency of decrease occurs.

Thirdly, by integrating the collector power supply and the ionizer power supply, it is possible to realize the downsizing and cost reduction of the power supply of the electrostatic precipitator.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The collector power supply of this embodiment is configured as a power supply integrated with the ionizer power supply. Figure 1
The configuration of the collector power supply will be described with reference to FIG. 1. Reference numeral 1 denotes a DC high-voltage power supply unit. It has been derived. Voltage dividing resistors R ₁ and R ₂ are connected in series between the output line to the ionizer power supply terminal 2 and the ground line 5, and the voltage dividing point D
The collector power supply terminal 3 is connected to. Then, between the collector power supply terminal 3 and the ground wire 5, three high voltage Zener diodes 4a, 4b, 4c are provided as constant voltage means.
The constant voltage circuit 4 is connected in series. When a constant voltage (collector voltage) of, for example, 2.4 kV is required, each high-voltage zener diode 4a, 4b, 4c has a zener voltage of 0.8 kV.
The voltage dividing point D is the constant voltage of 2.4 kV in the initial state.
The voltage is set to the above voltage point, the output current increases, and the voltage at the voltage dividing point D falls below 2.4 kV due to the internal impedance of the voltage dividing resistor R ₁ and the DC high-voltage power supply unit 1, and three high voltages are generated. The output voltage from the collector power supply terminal 3 is kept at a constant voltage until the Zener effect by the voltage Zener diodes 4a, 4b, 4c is lost. That is, the collector power supply of this embodiment is of the "partial constant voltage system".

Next, the operation of the collector power supply configured as described above will be described with reference to FIG. 2 shows the output characteristics of the partial constant voltage system of this embodiment, and shows the output characteristics of the resistance limiting system shown in FIG. 3 for comparison. In the initial state, a constant voltage is applied to the collector, for example, 2.
4kV is given. Leakage starts due to dust adsorbed on the collector due to the operation of the electrostatic precipitator, and the output current increases, but until point A where the output current becomes a constant value, the output voltage (collector voltage) remains constant due to the partial constant voltage output characteristic. Hold on to voltage. After the point A, the zener effect of the constant voltage circuit 4 is lost and the output voltage is linearly attenuated, and at the point B, it intersects with the resistance limiting type output characteristic. The elapsed time from the start of operation until the output voltage reaches the point B is about 1 month, and it is 2 to 3 weeks in a place with bad environmental conditions. The time to reach point B almost coincides with the maintenance time for cleaning the collector and the like. In this way, the collector voltage can be kept higher than in the conventional example until the maintenance time is almost reached, and as a result, the dust collection efficiency can be kept high. The improvement of the dust collection efficiency up to the point B is about 17% higher than that of the conventional example. Here, as a result of the increased dust collection efficiency, there is a concern that the timing of generation of the leakage current will be earlier and the maintenance time will be earlier than that of the conventional example. However, the result of actual operation was that the maintenance cycle was almost the same as the conventional example.

Although the constant voltage circuit is composed of three high voltage Zener diodes in the above-mentioned embodiment, for example, a high breakdown voltage transistor is connected in series to the output line to the collector power supply terminal and the base of the high breakdown voltage transistor is connected. It is also possible to apply a constant voltage circuit having another configuration in which a Zener diode is connected between the ground line and the ground line to keep the base voltage constant.

[0016]

As described above, according to the present invention,
First, since the output stage is provided with constant voltage means for holding the output voltage at a constant voltage until the output current, which increases with an increase in the amount of dust collected in the collector, reaches a constant value, the dust collection efficiency of the electrostatic precipitator. Has a collector voltage dependency, and since the dust collection efficiency and the collector voltage are substantially proportional to each other, it is possible to maintain a high dust collection efficiency until the maintenance period.

Secondly, since the constant voltage means is constituted by connecting a plurality of zener diodes in series, the output voltage is increased by the internal impedance of the direct current high voltage power supply section in the preceding stage of the constant voltage means as the output current increases. It is possible to appropriately realize the output characteristic that the output voltage is held at a constant voltage until the output current becomes a constant value even if the decrease tendency occurs.

Thirdly, since the collector power source is constructed integrally with the ionizer power source, the power source of the electrostatic precipitator can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a collector power supply according to the present invention.

FIG. 2 is a characteristic diagram showing the output characteristics of the above-described embodiment together with a comparative example.

FIG. 3 is a characteristic diagram showing an output characteristic of a conventional collector power supply.

[Explanation of symbols]

 2 Ionizer power supply terminal 3 Collector power supply terminal 4 Constant voltage circuit (constant voltage means) 4a, 4b, 4c High voltage Zener diode

Claims (3)

[Claims] 1. An electrostatic precipitator in which an ionizer generates corona discharge to charge dust in the air and electrostatically collects the charged dust in the air to a collector to which a required electric potential is applied. A collector power supply for applying a required potential to the collector, a constant voltage means for holding the output voltage at a constant voltage until the output current that increases with an increase in the amount of dust collected on the collector reaches a constant value. A collector power supply characterized by being provided in the output stage. 2. The collector power supply according to claim 1, wherein the constant voltage means is configured by connecting a plurality of zener diodes in series. 3. The collector power supply according to claim 1, wherein the collector power supply is integrally formed with an ionizer power supply that applies a voltage for generating a corona discharge to the ionizer.