JPS61242653A - Electrical dust precipitator - Google Patents

Abstract

PURPOSE:To increase the mean impression voltage during the impression time and to improve the dust collecting performance by connecting a capacitor parallel to an electric discharge part consisting of an electric discharge electrode and a dust collection electrode. CONSTITUTION:In relation to an electrical dust precipitator for collecting the dust and soot high in the specific resistance, a protective resistance 11 and a capacitor 12 are connected mutually in series parallel for a protective resistance 6, an electric discharge electrode 7 and a dust collection electrode 8. Thereby in case of impressing intermittently the DC high voltage to the electric discharge part, the mean impression voltage during the impression time is risen and the amount of the corona discharge is increased and also the such unnecessary current that the reverse ionization phenomenon is caused is suppressed and thereafter an electrical dust precipitator which has the extremely simple cinstitution and is high in the dust collecting performance even for the dust and soot high in the specific resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic precipitator for collecting soot and dust having a high specific resistance.

[Conventional technology]

Conventionally known electrostatic precipitators have a high specific resistance (10”
For soot and dust (exceeding ~1011 Ω·cm), a reverse ionization phenomenon occurs between the electrodes, resulting in a significant drop in dust collection performance. Therefore, in order to prevent the occurrence of reverse ionization and improve dust collection performance for dust with high specific resistance, a method is used in which a voltage is applied intermittently between the discharge electrode and the dust collection electrode. has been adopted in recent years. For example, as shown in FIG. 4, this system uses AC type thyristors [1° thyristor 2. Reactor 3. Transformer 4. Rectifier 5゜Protection resistor 6. A discharge electrode 7, a dust collecting electrode 8 disposed opposite to the discharge electrode 7, a thyristor control device 9 connected to the gates 1 to 1 of the thyristor 2, and an intermittent charge control device 10 connected to the thyristor control device 9. The voltage from the AC type tA1 is intermittently applied between the discharge electrode 7 and the dust collection electrode 8 by controlling the thyristor 2 by the intermittent charge control device 10 via the thyrisk control device 9. It is applied.

[Problem that the invention seeks to solve]

It is generally known that when a voltage is intermittently applied between the discharge electrode and the dust collection electrode of an electric precipitator as described above, the higher the voltage applied to the electric precipitator, the higher the dust collection performance. In this case, the voltage GJ applied between the electrodes is as shown in Figure 5,
The voltage application time '1 and rest time T2 are repeated in several cycles to several tens of cycles, and within one application time T1 there are several to several dozen (two in the illustrated case) voltage peaks, and These peak values are not necessarily constant.

In this case, if the spark discharge voltage between the electrodes is 2, it is limited by the applied voltage VF. Furthermore, if the corona discharge starting voltage is v3, corona discharge occurs in the shaded area in FIG. Since the amount of discharge also decreases, there is a problem in that the dust collection performance cannot be improved as much as expected.

The present invention improves dust collection performance by increasing the average applied voltage during the application time in an electrostatic precipitator in which voltage is applied intermittently between electrodes. The purpose is to provide electrostatic precipitators.

[Means and actions for solving the problem] This purpose is to
According to the present invention, it has a discharge electrode and a dust collection electrode disposed opposite to the discharge electrode, and by intermittently applying a voltage between the discharge electrode and the dust collection electrode, The problem is solved by an electrostatic precipitator that collects dust, which is characterized in that a capacitor is connected in parallel to a discharge section made up of a discharge electrode and a dust collection electrode.

According to this configuration, due to the action of the capacitor connected in parallel to the discharge section, the peak value of the voltage applied between the electrodes remains constant at 5, which increases the average applied voltage and increases the amount of corona discharge. Dust collection performance is improved.

〔Example〕

The present invention will be described below based on an embodiment shown in the drawings. In FIG. 1, 11.12 is a protective resistor 6. A protective resistor and a capacitor are connected in parallel to the discharge electrode 7 and the dust collection electrode 8 and in series with each other.
This is the same as the conventional example shown in the figure. Fig. 2 is an equivalent circuit diagram of the embodiment shown in Fig. 1, where Si is a rectifier, R,, R2 are resistors for taking out the voltage signal on the DC side, Ro is a protective resistor, Rc is a protective resistor for a capacitor, and C is a capacitor. , C5 is the load side capacitance, and Ca and Ra are the equivalent capacitance and resistance of the dust layer attached to the dust collecting electrode.

Since the embodiment of the present invention is configured as follows, the voltage from the AC power supply is intermittently interrupted by controlling the thyristor 2 by the intermittent charge control device 10 via the thyristor control device N9. and further reactor 3.
It is converted into an intermittent DC high voltage by a transformer 4 and a rectifier 5, and is applied between a discharge electrode 7 and a dust collection electrode 8 via a protective resistor 6. In this case, the conventional example shown in FIG. Unlike protection resistance 6. Since the protective resistor 11 and the capacitor 12 are connected in parallel to the discharge electrode 7 and the dust collection electrode 8, the voltage V and current applied between the discharge electrode 7 and the dust collection electrode 8 due to charging of the capacitor 12 ■ is the third
As shown in the figure, the average applied voltage increases, and thus corona discharge occurs in the shaded areas in FIG. 3, so the amount of corona discharge increases and the dust collection efficiency increases.

Incidentally, in the case of this embodiment, as shown in FIG. 3, a voltage due to charging of the capacitor 12 is applied between the electrodes even during the rest time T2, but no corona discharge occurs between the electrodes, and therefore the specific resistance is The charging voltage Va (see FIG. 2) of the dust layer of the dust collecting electrode 8, which is the cause of the reverse ionization phenomenon that occurs in the case of a high level of dust, is the capacitance Cd of this dust layer itself.

The resistor Rd causes the current to discharge and fall as shown by the current id,
Therefore, during the rest time 'r2, the voltage caused by charging the capacitor 12 does not have an adverse effect on the reverse ionization phenomenon. If there is such an adverse effect, that is, promotion of the reverse ionization phenomenon during the pause time T2, the current I will rise as shown by the dotted line in FIG.
By appropriately selecting the pause time T2 and the capacitance of the capacitor 12, the above-mentioned adverse effects can be eliminated. still,
The protective resistor 11 is for protecting the capacitor 12 by blocking an overcurrent to the capacitor 12.

〔Effect of the invention〕

As described above, according to the present invention, since the capacitor is connected in parallel with the discharge section constituted by the discharge electrode and the dust collection electrode, when a DC high voltage is intermittently applied to the discharge section, the applied The average applied voltage during the time increases, the amount of corona discharge increases, and unnecessary current that causes reverse ionization phenomenon is suppressed, so the extremely simple structure can also collect soot and dust with high resistivity. An electrostatic precipitator with high dust performance can be provided. Furthermore, since a voltage is applied between the electrodes due to the charging of the capacitor even during the rest time, the uncollected dust 1~, which is ionized when the voltage is applied, is attracted to the dust collection electrode by Coulomb force, improving the dust collection performance. There is also the advantage of further improvement.

[Brief explanation of the drawing]

Fig. 1 is a schematic circuit diagram of an embodiment of an electrostatic precipitator according to the present invention, Fig. 2 is an equivalent circuit diagram of the embodiment of Fig. 1, and Fig. 3 is a voltage and current between electrodes of the embodiment of Fig. 1. FIG. 4 is a schematic circuit diagram of an example of a conventional electrostatic precipitator, and FIG. 5 is a graph showing the voltage and current between the electrodes of the conventional example of FIG. 1... AC power supply, 2... Zyristor, 3...
・Reactor, 4...Transformer, 5...Rectifier, 6
...protective resistor, 7...discharge electrode, 8...dust collection electrode, 9...cyrisk control device, 10...
Intermittent charge control device, 11...protective resistor, 12...
・Capacitor. Figure 3 Figure 5

Claims (1)

[Scope of Claims] It has a discharge electrode and a dust collection electrode disposed opposite to the discharge electrode, and by intermittently applying a voltage between the discharge electrode and the dust collection electrode, An electrostatic precipitator that collects dust, characterized in that a capacitor is connected in parallel to a discharge section composed of a discharge current and a dust collection electrode.