JPH05136660A - Electric dust collector - Google Patents

Abstract

PURPOSE:To improve the dust collection efficiency by providing thyristors having reversed parallel connection between a power capacitor and a pulse transformer and controlling the thyristors against the electric resistance of dust so as to vary the pulse width. CONSTITUTION:The output of an electric resistivity measuring unit 5 installed in an electric dust collector 10 is supplied to a thyristor control circuit 4 as a signal representing an electric resistivity. When a thyristor 2 is conducted in the circuit 4, a current flows from the power capacitor 1 to a booster transformer 6. Thus, a steep voltage is response to the circuit constant appears in a secondary coil 8, its peak makes the thyristor nonconductive, and the voltage charged in the dust collector 10 is gradually dropped while the energy is consumed by corona discharge. Then after the lapse of a time interval set by the circuit 4, when a thyristor 3 is triggered, the charge stored in the precipitator 10 is fed back to the capacitor 1 and the voltage of a discharging electrode 11 is rapidly dropped. Thus, the pulse width is properly controlled corresponding to the electric resisitivity of dust measured by the measuring unit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic precipitator, and more particularly to an electrostatic precipitator provided with a pulse power source for generating a rectangular wave pulse voltage in the electrostatic precipitator.

[0002]

2. Description of the Related Art In order to efficiently collect dust having a high electric resistivity with an electrostatic precipitator, a pulse charging method in which a high voltage pulse of several pulses / second or more is superimposed on a DC voltage is adopted.
Here, the dust generated from a dust source such as a boiler varies in electrical resistivity, particle size, etc., depending on the combustion state and the physical properties of the fuel. Along with this, it is necessary to change the pulse waveform of the pulse voltage applied to the electrostatic precipitator.

For example, when the electric resistivity of dust is low, the pulse width is widened and the pulse power applied to the electric dust collector is increased to improve the dust collecting performance. On the contrary, when the electric resistivity of dust becomes high, it is necessary to narrow the pulse width and reduce the discharge current.

[0004]

Particularly in the case of a high electric resistivity, in order to make the discharge current in the electrostatic precipitator uniform, a pulse with a fast rise and a reverse ionization on the precipitator are suppressed. Narrow the pulse width so as not to increase the discharge current,
A high peak voltage is required to maintain the electric field strength in the dust collection space.

Under such circumstances, there is a method of generating a pulse voltage by controlling the primary side of the step-up transformer with a switching element. However, the pulse width is fixed by a circuit constant,
There was a problem that a steep rise could not be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention is an improvement over the above-mentioned conventional technique, in which the pulse width is appropriately controlled by a high voltage of a rectangular wave pulse in accordance with the electric resistivity of the collected dust and is supplied to an electric dust collector. The pulse width to be changed is variable so that the operation under optimal conditions can be continued.

[0007]

[Operation] The present invention is provided with an electric resistivity measuring device for adjusting the width of the pulse voltage applied to the electric dust collector in response to the change in the electric resistivity of the dust collected in the electric dust collector. ， I tried to take this signal into the control part of the power supply.

[0008]

[Example] Fig. 1 shows the configuration and operation of the pulse power supply of the present invention.
Use to explain.

The AC voltage is rectified and the power supply capacitor 1 is charged. The output of the power supply capacitor is connected to the step-up transformer 6 via the thyristor 2 and the thyristor 2 and the switching elements whose conduction directions are antiparallel. The secondary coil of the step-up transformer 6 passes through the coupling capacitor 9 and is connected to the discharge electrode 11 of the electrostatic precipitator 10. A DC voltage is separately supplied to the discharge electrode from a DC power supply 13, and the coupling capacitor functions to separate the pulse circuit from the DC power supply and to superimpose the pulse voltage on the DC voltage.

The thyristor control circuit is supplied with the output of the electrical resistivity measuring device 5 installed in the electrostatic precipitator as a signal of electrical resistivity. In such a structure, the pulse voltage is generated as follows. When the thyristor 2 is turned on by the thyristor control circuit, a current flows from the power supply capacitor to the step-up transformer, a steep voltage appears according to the circuit constant in the secondary coil, and when the peak value is reached, the thyristor 2 is turned off. Change. After that, the voltage charged in the electrostatic precipitator gradually decreases while consuming energy due to corona discharge.

Next, the thyristor 3 is triggered after a lapse of a time interval set by the thyristor control circuit. This thyristor is connected so that it conducts in the opposite direction to the thyristor 2, and the charge accumulated in the electrostatic precipitator is returned to the power supply capacitor, and the discharge electrode voltage drops sharply.

By the above operation, the voltage as shown in FIG. 2 is applied to the discharge electrode of the electrostatic precipitator. Here, the pulse width τ can be appropriately controlled according to the electric resistivity of dust measured by the electric resistivity measuring device 5.

[0013]

According to the present invention, the pulse width of the pulse voltage to be supplied can be optimally controlled according to the electric resistivity of dust, and the performance of the electrostatic precipitator can be improved.

[Brief description of drawings]

FIG. 1 is an embodiment of a pulse power supply circuit of an electrostatic precipitator according to the present invention.

2 is a waveform of a voltage applied to a discharge electrode in the embodiment of FIG.

Claims (1)

[Claims] 1. A pulse power supply for applying a rectangular wave pulse high voltage to an electrostatic precipitator, wherein the control circuit of the switching means has an arbitrary pulse width corresponding to the electrical resistivity of the dust collected by the electrostatic precipitator. An electrostatic precipitator having a pulsed power supply, which is characterized in that: