JPS6353858B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a control device for a hammering device for a discharge electrode,
In particular, the present invention relates to a control device for a hammering device for a discharge electrode in which the time interval for hammering the discharge electrode of a dust collector can be varied in accordance with the amount of dust attached.

[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. 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 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 thereof. 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, 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 hammerings, improve the peeling off of the dust, 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 hammer strikes but also the strength.

However, in the past, there was no method to continuously monitor the amount of dust adhering to the discharge electrode, so it was not possible to perform controls such as accelerating the hammering interval of the discharge electrode.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to propose a control device for a hammering device for a discharge electrode, which allows the hammering time interval to be controlled according to the amount of dust attached to the discharge electrode. It is said that

[Summary of the invention]

In order to achieve the above object, the present invention detects the amount of dust attached to the discharge electrode at regular time intervals, compares the detected value with a reference value, and changes the hammering time according to the deviation. This is what I did.

〔Example〕

Hereinafter, preferred embodiments of a control device for a discharge electrode hammering device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. A discharge electrode and a dust collection electrode (both not shown) are installed in the dust collection chamber 10, and a power source 12 that applies a DC high voltage is connected to the discharge electrode.
A hammering device 14 (consisting of a hammer, a motor for driving the hammer, etc.) is provided nearby. The power supply 12 is provided with a power supply control panel 16,
The voltage applied to the discharge electrode is changed from zero to a predetermined voltage. The hammering device 14 is controlled by a hammering device control panel 18, which includes the control panel 18 and a power supply control panel 16.
A control unit 20 configured using a microcomputer or the like is provided to control each of the above. A gas temperature detector 22 is connected to the control unit 20 and is provided in the dust collection chamber 10 to detect the gas temperature in the zero surrounding air. Further, the voltage applied to the discharge electrode (voltage divided by a resistor) is given to the control unit 20 as input information.

Here, a method for detecting the amount of dust attached to the discharge electrode will be explained.

As a result of experiments, the inventors confirmed that the corona starting voltage depends on the enlarged diameter of the discharge electrode due to dust adhesion and the gas temperature. By utilizing this, the amount of dust attached to the discharge electrode can be estimated.

The diameter of the discharge electrode is φ, and the relative density of the gas is δ=T ₀ /T×P ₀ /P...(1) (T ₀ and P ₀ are the absolute temperature and pressure of the gas based on the reference, and T, (P is the actual absolute temperature and pressure of the gas). Then, the corona starting voltage V _c can be approximated by the following equation (where a ₁ , a ₂ , and a ₃ are constants determined by experiment).

V _c = (a ₁ φδ + a ₂ √) × (a ₃ −l _o φ) ...(2) As is clear from equation (2), the corona starting voltage V _c
The enlarged diameter φ of the discharge electrode can be determined by actually measuring the gas temperature T and calculating the equation (2). Note that the corona start voltage V _c is determined by gradually increasing the discharge current of the discharge electrode from the zero level to the set value level at regular intervals, and detecting the discharge electrode voltage when the discharge current starts flowing during this operation. It can be determined by

In the above configuration, as shown in FIG. 2, the voltage applied to the discharge electrode is reduced to zero at time _t0 , and the discharge current is reduced to zero, and from this point on, the discharge electrode voltage _Vc of the power control panel 16 is gradually increased. The control unit 2 detects the voltage V _c at which the discharge current I starts flowing at time t ₁ while
Record in memory within 0.

From the corona start voltage obtained in this manner and equation (2), the control unit 20 back-calculates equation (2) to calculate the enlarged diameter φ. The timing at which the hammering device 14 should be operated is determined from this enlarged diameter φ, and the hammering device control panel 18 is driven. The control unit 20 calculates the amount of attached dust φ ₀ (conventional empirical value set based on the dust concentration of the inlet gas of the dust collector, the particle size of dust, etc.) which is stored in advance as a reference value. Compare with φ. If φ>φ ₀ at this time, a control command is output to the hammering device control panel 18 so that the hammering time interval becomes shorter than the time corresponding to φ ₀ until the next corona start voltage measurement. FIG. 3 is a flowchart showing an example of the processing by the control unit 20 described above.

Note that if there are no fluctuations in the pressure and temperature (gas density) in the dust collection chamber 10, the gas temperature detector 22 is not necessary, but by providing it, the accuracy of calculating the amount of attached dust can be improved. be able to.

〔Effect of the invention〕

As explained above, according to the control device for the hammering device for a discharge electrode according to the present invention, the amount of dust attached to the discharge electrode is detected and the hammering time interval is varied based on this detected amount. The hammering time interval of the electrode can be optimized depending on the amount of attached dust. Therefore, there is no possibility of the attached dust sticking to the discharge electrode as in the conventional case.

[Brief explanation of the drawing]

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.
FIG. 3 is a flowchart showing the process of the present invention. DESCRIPTION OF SYMBOLS 10... Dust collection chamber, 12... Power source, 14... Hammering device, 16... Power control panel, 18... Hammering device control panel, 20... Control unit, 22... Gas temperature detector.

Claims (1)

[Claims] 1. Hammering for discharge electrodes, in which dust adhering to a discharge electrode, which is disposed in a pair with a dust collection electrode, is hammered and peeled off in a dust collection chamber through which dust-containing dust passes from one opening to the other. In the device, a power supply control means for once reducing the discharge current of the discharge electrode to zero and then gradually increasing the discharge voltage, and a discharge electrode voltage based on the discharge current at the time when the discharge current starts flowing when the discharge voltage is increased by the means. A discharge electrode hammering device characterized in that it is provided with a calculation means for calculating the amount of dust attached to the discharge electrode by the means, and a control means for shortening the hammering time interval when the amount of dust attached by the means exceeds a set value. Control device.