JPH0222707B2 - - Google Patents

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,
In particular, the present invention relates to a charge control device for an electrostatic precipitator that prevents a drop in dust collection efficiency during operation of the detection device in an electrostatic precipitator equipped with a device for detecting the amount of dust adhering to a discharge electrode.

[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 collecting electrode, and the dust in the dust-containing gas passing between the electrodes is charged, and by the action of the electric field formed between the charged dust and the dust collecting electrode. , dust collection is performed by moving the dust to the dust collection pole. As the dust collection time passes, dust accumulates on the dust collection electrode. 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 separate 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, also around the discharge electrode, which is the ion supply side, dust caught in the turbulence of the gas flow collides with the discharge electrode, so that dust adheres to the surface of the discharge electrode. 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 device at the dust source, changes in fuel, and the like. Therefore, when driving for a long time,
Various types of dust fly in the air, and in the case of highly adhesive dust, the diameter of the discharge electrode will be increased. In the case of highly adhesive dust like this, 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 time will become stuck,
In order to peel this off, it is necessary to increase not only the number of hammerings but also the strength.

For this purpose, it is necessary to continuously monitor the amount of dust attached to the discharge electrode. In contrast, the inventors have previously proposed a method for estimating the amount of dust adhering to a discharge electrode, paying attention to the fact that the corona starting voltage depends on the enlarged diameter of the discharge electrode due to dust adhesion and the gas temperature.

That is, if the diameter of the discharge electrode is φ and the relative density of the gas is δ, then δ=T ₀ /T×P ₀ /P...(1) (T ₀ and P ₀ are the absolute temperature and pressure of the gas as a reference. (where T and P are the actual absolute temperature and pressure of the gas), the corona starting voltage V _c can be approximated by the following equation (however, a ₁ , a ₂ , and a ₃ are determined experimentally. constant).

V _c = (a ₁ φδ + a ₂ √) × (a ₃ −l _o 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 is first set to zero, then the discharge voltage is gradually increased, and in the process, the discharge voltage at the point when the discharge current starts flowing is measured. There is an inconvenience that the dust collection efficiency decreases during a period in which the discharge voltage is lower 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 one division is lowered, the charging voltage of the other divisions is made higher than normal, and the entire dust collection chamber is The dust collection performance is maintained at the planned value.

〔Example〕

Hereinafter, preferred embodiments of a 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 apparatus 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 discharge electrode (not shown) provided in each section is connected to a power source 12 for the first section and a power source 14 for the second section. Each of the power supplies 12 and 14 has a 1-area power supply control panel 1.
Each of the 6th and 2nd ward power control panels 18 is connected,
The voltage applied to the discharge electrode is changed from zero to a predetermined voltage.

Inside the dust collection chamber 10, there is a device 1 which is configured by a combination of a hammer and a motor and which hammers the discharge electrode in the first section.
A district discharge electrode hammering device 20 and a second district discharge electrode hammering device 22 for hammering the second district discharge electrode are provided.
Furthermore, a gas temperature detector 2 for detecting the gas temperature in the atmosphere is installed near each of the hammering devices 20 and 22.
4 and 26 are provided. A driving motor (not shown) for each of the hammering devices 20 and 22 is connected to a hammering device control panel 28 .

Power control panels 16 and 18 and hammering device control panel 28
Each of these is connected to a control unit 30 using a microcomputer, and power supply voltage control and hammering intervals are controlled according to a preset program. The control unit 30 has detection voltages Vc1 and Vc2 of the discharge electrodes.
In addition, detection signals from gas temperature detectors 24 and 26 are applied.

The operation of the above configuration will be explained based on FIG. 2. The control unit 30 includes the 1st section power control panel 1
6 and the 2nd section power control panel 18 are operated alternately at regular intervals. 1 by the 1st section power control panel 16 at time t _0.
The discharge current of the discharge electrode of the ward is reduced to zero, and from this point the discharge electrode voltage Vc1 of the first district power control panel 16 is gradually increased, and the voltage Vc1 at which the discharge current starts flowing at time t1 is detected and controlled. The information is recorded in the memory within the unit 30. During this discharge pressure reduction section, the dust collection performance in Section 1 temporarily decreases, but the electrostatic precipitator takes into account fluctuations in gas volume and changes in dust properties and sets the worst-case conditions. Since the capacity of the power supply is selected, it is normally operated with sufficient margin. In other words, when the 1st ward is decreasing, the 2nd ward is decreasing from time to.
By setting the discharge pressure to be high at t2, the overall dust collection performance of the 1st and 2nd sections can be maintained at the planned value. 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 equation (2), the control unit 30 back-calculates equation (2) to calculate the enlarged diameter φ. The timing at which the hammering device 20 or 22 should be operated is determined from this enlarged diameter φ, 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 drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is an operation time chart of the embodiment shown in FIG. 10...Dust collection room, 12...Power supply for 1 section, 14...
...Power supply for 2nd district, 16...1st district power control panel, 18...
...2nd section power control panel, 20...1st section discharge electrode hammer device, 22...2nd section discharge electrode hammer device, 24, 26...
... Gas temperature detector, 28 ... Hammering device control panel, 3
0...Control unit.

Claims (1)

[Claims] 1 A dust collection electrode and a discharge electrode are arranged facing each other in the dust collection chamber, and the device is divided into multiple charged sections and a power supply is connected to each of them. In a charge control device that performs charge control that gradually increases the charge voltage from near the zero level, the charge voltage for the charge section in which the discharge electrode that is not subject to the measurement of the amount of attached dust is installed is set to a predetermined value higher than normal. 1. A charge control device for an electrostatic precipitator, characterized by comprising a control means for controlling the charge.