JPS6190757A - Charge control device for electrostatic precipitator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a charge control device for an electrostatic precipitator, and more particularly to an electrostatic precipitator equipped with a device for detecting the amount of dust attached to a discharge electrode. The present invention relates to a charge control device for an electrostatic precipitator that prevents a decrease in dust collection efficiency during operation.

[Background of the invention]

The general configuration of an electrostatic precipitator includes a discharge electrode to which a high DC voltage is applied, and a dust collection electrode formed in a flat plate shape and arranged to face the discharge electrode and held at ground potential. It is installed inside a dust collection chamber equipped with a gas flow path.

Ions are generated by corona discharge between the discharge electrode and the dust collection electrode, the dust in the dust-containing gas passing between the electrodes is charged, and the dust is removed by the action of the electric field formed between the charged dust and the dust collection electrode. Dust collection is performed by moving the dust to the dust collection electrode. Dust accumulates on the dust collection electrode as the dust collection time passes. If this is left unattended, the dust collection efficiency will decrease, so a method is used in which the dust collection pole is hammered with a hammering device at appropriate time intervals to peel off the dust from the dust collection pole surface. The dust that falls due to hammering is collected in a hopper provided at the bottom of the dust collection chamber.

On the other hand, around the discharge electrode, which is the ion supply side,
When the dust caught up in the turbulence of the gas flow collides with the discharge electrode, the dust adheres to its surface. The thinner the discharge electrode, the more actively corona discharge occurs, and the greater the amount of dust attached. When the apparent diameter increases, the amount of ions generated by the discharge electrode decreases, and the dust in the gas becomes insufficiently charged. For this reason, a hammering device is provided not only on the dust collecting electrode but also on the discharge electrode.

The interval at which this discharge electrode is hammered should be determined depending on the dust adhesion situation, but it is usually determined empirically based on the dust concentration of the dust collector inlet gas and the dust particle size at the beginning of operation. It has been set to , and will rarely be changed thereafter.

However, in reality, the characteristics of dust fluctuate due to changes in the operating conditions of the equipment on the side of the dust source, changes in fuel, and the like. Therefore, during long-term operation, various types of dust will fly, and in the case of highly adhesive dust, the diameter of the discharge electrode will have to be increased. With such highly adhesive dust, it is necessary to catch the signs that the discharge electrode is becoming enlarged, increase the number of hammer strikes, improve the dust removal, and prevent the enlargement of the discharge electrode at an early stage. be. Dust that has been attached to the discharge electrode for a long period of time becomes stuck, and in order to peel it off, it is necessary to increase the number of hammer strikes as well as the strength.

For this purpose, it is necessary to continuously monitor the amount of dust attached to the discharge electrode. In response, the inventors focused on the fact that the corona onset voltage depends on the diameter of the inner diameter due to dust adhesion on the discharge electrode and the gas temperature, and previously proposed a method for estimating the amount of dust adhering to the discharge electrode. .

That is, if the diameter of the discharge electrode is φ and the relative density of the gas is δ, then To P.

δ=-X-・・・・・・・・・・・・・・・＋11TP
' (T,, po are the absolute temperature and pressure of the reference gas, and T and P are the absolute temperature and pressure of the actual gas.) Then, the corona starting voltage ■, can be approximated by the following equation. It is possible (however, al tag '+ al is a constant determined by experiment).

Vc = (at (fiδ122 Ji)X (a
l −#fi φ＞・・・・・・・・・・・・・・・(
2) As is clear from equation (2), the corona starting voltage Vc
The enlarged diameter φ of the discharge electrode can be determined by actually measuring the gas temperature T and calculating the equation (2). The hammering time interval can be set based on the enlarged diameter φ obtained by this calculation, and the hammering time interval can be optimized. However, in order to detect the corona start voltage Vc, the discharge current must be set to zero once
Then, the discharge voltage is gradually increased, and in the process, the discharge voltage at the point when the discharge current starts to flow is measured.However, there is an inconvenience that the dust collection efficiency decreases during the period in which the discharge voltage is lowered than normal.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a charge control device for an electrostatic precipitator that prevents a decrease in dust collection efficiency during detection of the amount of dust attached to a discharge electrode.

[Summary of the invention]

In order to achieve the above object, the present invention complicates the charging divisions in the dust collection chamber, and when the discharge voltage of the division (①) is lowered, the charging voltage of the other divisions is made higher than normal, and the dust collection chamber number □The dust collection performance of the body is maintained at the planned value. □ [Example] □ Hereinafter, preferred embodiments of the charge control device for an electrostatic precipitator according to the present invention will be described in detail with reference to the accompanying drawings.Next, an example of the device according to the present invention will be described in detail.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The dust collection chamber 10 is divided into a first section and a second section, and a first medical power source 12 and a second medical power source 14 are connected to discharge electrodes (not shown) provided in each section. A first section power control panel 16 and a second section power control panel 18 are connected to each of the power supplies 12 and 14, and change the voltage applied to the discharge electrode from zero to a predetermined voltage.

Inside the dust collection chamber 10, there is a first section discharge electrode hammering device 20, which is configured by a combination of a hammer and a motor, and which hammers the discharge electrode in the first section, and a second section discharge electrode, which hammers the discharge electrode in the second section. An electrode hammering device 22 is provided.

Furthermore, gas temperature detectors 24 and 26 are provided near each of the hammering devices 20 and 22 to detect the gas temperature in the atmosphere. A driving motor (not shown) for each of the hammering devices 20 and 22 is connected to a hammering device control panel 28 .

A control unit 30 using a microcomputer is connected to each of the power supply control panels 16 and 18 and the hammering device control panel 28, and power supply voltage control and hammering intervals are controlled according to a preset program. The control unit 30 is applied with detection voltages Vcl and Vc2 of the discharge electrodes as well as detection signals of the gas temperature detectors 24 and 26.

The operation of the configuration described above will be explained based on FIG. 2. The control unit 30 operates the first section power control panel 16 and the second section power control @18 alternately at regular intervals. Time t. The discharge current of the discharge electrode of the first district is reduced to zero by the first district power supply control panel 16, and from this point on, while gradually increasing the discharge electrode voltage Vcl of the first district power supply control panel 16, the discharge current of the first district power supply control panel 16 is reduced to zero. The voltage Vcl that starts flowing is detected and recorded in the memory within the control unit 30. In this period of small discharge pressure reduction, the dust collection performance of Section 1 temporarily decreases, but the electrostatic precipitator takes into account fluctuations in gas amount and changes in dust properties and sets the worst-case conditions. Since the capacity of the power supply is selected according to In other words, when the 1st section is decreasing, the 2nd section is set so that the discharge pressure increases from time to [2], thereby keeping the overall dust collection performance of the 1st and 2nd sections at the planned value. I can do it. Similarly, when detecting the voltage Vc2 at the beginning of the flow of the discharge current of the discharge electrode of the second section, the discharge pressure of the first section is increased from time t2 to t4.

From the corona start voltage obtained in this manner and the equation (2), the control unit 30 back-calculates the equation (2) to calculate the enlarged diameter φ. From this enlarged diameter φ, hammer bag N20 or
The timing for operating the hammer 22 is determined, and the hammering device control panel 28 is driven.

In addition, in the above structure, although the example which divided a dust collection chamber into two was shown, this invention can be similarly applied even if it divides into three or more.

〔Effect of the invention〕

As explained above, according to the charge control device for the electrostatic precipitator according to the present invention, when detecting the amount of dust adhering to the discharge electrode in the first category, the charging voltage in the other categories is increased, so that the charge control device for the electrostatic precipitator as a whole The dust collection efficiency can be maintained at the planned value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an operation time chart of the embodiment of FIG. 10... Dust collection room, 12... Power supply for 1 area, 14
...Power supply for 2nd district, 16...1st district power control panel, 1
8...2nd section power control panel, 20...1st section discharge hammering device, 22...2nd section discharge hammering device, 24.26.
... Gas temperature detector, 28 ... Hammering device control panel,
30...control unit.

Claims (1)

[Claims] A dust collection electrode and a discharge electrode are arranged facing each other in the dust collection chamber, and are divided into multiple charging sections, each of which is connected to a power source, and the target discharge electrode is charged when measuring the amount of dust attached to the discharge electrode. In a charge control device that performs charge control that gradually increases the voltage from near the zero level, the charging voltage for a charging section in which a discharge electrode that is not subject to measurement of the amount of attached dust is installed is set higher than normal by a predetermined value. A charge control device for an electrostatic precipitator, comprising a control means.