JPH0334981B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a discharge line disconnection detection device for an electrostatic precipitator, and in particular to an automatic spark control mechanism that automatically controls operating voltage and current when a spark occurs, and an electrostatic precipitator. The present invention relates to a discharge line disconnection detection device for an electrostatic precipitator equipped with a power supply device having a device protection device.

[Conventional technology]

It is generally advantageous in terms of performance to operate an electrostatic precipitator at a higher charging voltage, and for this reason, it is usually equipped with a control device that uses constant current control or a combination of constant current control and constant voltage control, and is not equipped with a control device that uses constant current control or a combination of constant current control and constant voltage control. When a spark occurs, each control is operated at the output upper limit value (In, Vn shown in Figure 2) set by the setting device. In addition, when sparks occur, spark generation control is generally called "spark tracking control,""spark frequency system," or "spark integral control" for the purpose of preventing the transition from the corona discharge region to the arc or glow discharge region due to continuous spark generation. The electrostatic precipitator is operated within the range of the constant current or constant voltage set value by automatic time control, and the charging voltage and discharging current of the electrostatic precipitator are controlled depending on the spark generation situation.

The causes of this spark include changes in the inlet gas and dust conditions of the electrostatic precipitator, and changes in the structural conditions within the electrostatic precipitator.

One of the structural conditions is a disconnection due to deterioration of the discharge line, and the conventional method for detecting this disconnection is to detect the charging voltage on the high voltage (output) side and the voltage on the low voltage (input) side of the power supply, and use "low voltage detection". There is something called a "device" or "short circuit detection device", which is configured to operate and stop charging if the charging voltage remains below a certain value Vu for a certain period of time due to the automatic repeated spark control described above. was.

In such a configuration, the operating voltage Vu is generally set below the corona discharge starting voltage Vc, but Vc changes depending on the gas and dust conditions at the inlet of the electrostatic precipitator, so Vu is much higher than Vc. The lower part was fixedly set.

The following three cases can be considered as discharge line disconnection.

(a) Due to the disconnection of the discharge wire, a complete short circuit occurs between the discharge wire and the dust collection electrode.

(b) Even if the discharge wire is disconnected, the gap with the dust collection electrode will hardly change.

(c) The discharge wire breaks and the gap between it and the dust collection electrode becomes narrow.

In the operating state of an actual machine consisting of multiple discharge electrodes and dust collecting electrodes, in the case of (a), the charged state will be at point D in Figure 2, and the above-mentioned "low voltage detection device" or "short circuit detection device" will be activated. ” is sufficient for detection.

In the case of (b), the frequency of spark occurrence increases at the charging point before the disconnection or at a charging point below it, as at point A in FIG. However, over time, due to the effects of hammering, etc., it is possible that the state will shift to state (c).

In case (c), sparks occur frequently, and the charging voltage and current are changed from point A to B in Figure 2 by the automatic spark control described above.
After passing through the points, you will eventually reach point C. When the charging voltage at point C falls below Vc, corona discharge continues in the narrow gap between the collecting electrode and the broken end of the discharge wire, and the device no longer functions effectively as an electrostatic precipitator. Operation will continue under these conditions.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge line breakage detection device for an electrostatic precipitator that can eliminate the drawbacks of the prior art, particularly the condition (c), and can detect a breakage of a discharge line in a short time.

[Means for solving problems]

This invention is configured so that low voltage detection devices are set in two stages as a means of confirming the charging state of an electrostatic precipitator when the discharge wire is broken through actual operation and reliably detecting the breakage of the discharge wire. be.

〔Example〕

FIG. 1 is a circuit diagram of a discharge line breakage detection device for an electrostatic precipitator according to the present invention, and FIG. 2 is a charging characteristic diagram of the electrostatic precipitator.

The AC power supply 10 is phase-controlled by a power control element 11, boosted by a transformer 12, and connected to a rectifier 1.
3, the direct current is rectified and applied to the discharge electrode 21 of the electrostatic precipitator 20, and corona discharge is started between the discharge electrode 21 and the dust collecting electrode 22, and the electric precipitator 20 is operated.

The charging voltage is monitored by the output of a charging voltage detection device 30 using a resistive voltage divider. The discharge current is monitored by the output of a discharge current detection device 40 using a shunt resistor. The output of the charging voltage detection signal 30 is taken out and inputted to the low voltage detection devices x31 and y32, respectively, and the low voltage detection device x31 sets the operating value Vu at a voltage extremely lower than the corona starting voltage Vc, that is, a value near zero, as before. The electrostatic precipitator short-circuit signal 50 is sent out to stop charging if the voltage is below Vu for a certain period of time or more.

The low voltage detection device y32 detects the corona starting voltage Vc
The operating value Vu' is set to an approximate value of
is set to the operating value Iu, the power supply rated output current value/the number of discharge wires <Iu, and if the charging voltage is below Vu' and the discharge current is below Iu for a certain period of time, the electrical collection will be disabled. It is configured to be able to send out a dust device abnormality alarm signal 51.

In FIG. 2, when a discharge wire breakage occurs as shown in (c) above, the corona starting voltage changes from Vc to Vc', and according to this embodiment, sufficient detection is possible when the charging point is C. Discharge wire breaks could be identified at an early stage, and the period during which the electrostatic precipitator's functionality would deteriorate due to removal of the broken wires could be significantly shortened.

〔Effect of the invention〕

Since this invention has two stages of low voltage detection in the electrostatic precipitator, disconnection of the discharge line can be reliably detected.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a discharge line breakage detection device for an electrostatic precipitator according to the present invention, and FIG. 2 is a charging characteristic diagram of the electrostatic precipitator. 20... Electrostatic precipitator, 21... Discharge electrode, 22
...Particle collecting electrode, 30...Charging voltage detection device, 31...
...Low voltage detection device x, 32...Low voltage detection device y, 40...Discharge current detection device, 41...Minimum current detection device, 50...Short circuit detection signal, 51...Abnormality detection signal.

Claims (1)

[Claims] 1. A charging voltage and a discharge current are supplied to a dust collection electrode and a discharge electrode placed opposite to the dust collection electrode, and automatic spark control function and protection of the electrostatic precipitator when a spark occurs. A discharge line disconnection detection device for an electrostatic precipitator comprising a power supply device having the following functions: a charged voltage detection device; and when a first low voltage near zero is detected based on the output of the charged voltage detection device, a first low voltage detection device that outputs a short circuit detection signal; and a second low voltage detection device that detects a second low voltage near the corona discharge starting voltage based on the output of the charging voltage detection device.
a low voltage detection device; a discharge current detection device; a minute current detection device that detects a minute current based on the output of the discharge current detection device; the second low voltage is detected and the minute current is detected; A discharge line breakage detection device for an electrostatic precipitator, comprising: an AND circuit that outputs an abnormality detection signal when