JPS63130151A - Method for detecting abnormality of discharge wire of electrostatic precipitator - Google Patents

Abstract

PURPOSE:To perform rapid response by detecting the disconnection or loosening of a discharge wire during operation, by judging that the discharge wire is abnormal when the charge voltage in a spark generating state becomes lower than that at the time of usual operation and the spark generating state is cyclic. CONSTITUTION:Charge voltage is monitored on the basis of the output of a charge voltage detector 30 during the operation of an electric precipitator 20 and a discharge current is monitored on the basis of the output of a discharge current detector 40. Now, when spark discharge is generated between a discharge electrode 21 and a dust collection electrode 22, the output signals of both detectors 30, 40 are inputted to a spark detector 50 and a spark generating signal and charge voltage are inputted to a microcomputer 50 from the spark detector 50. The microcomputer 52 regards that a discharge wire is shaken by the disconnection or loosening thereof when it is judged that charge voltage is lower than that at the time of usual operation and a spark discharge state is generated cyclically to generate an alarm.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for detecting an abnormality in a discharge wire of an electrostatic precipitator, and particularly for detecting discharge wire abnormalities such as disconnection of the discharge wire or slackness of the discharge wire between supporting points of the discharge wire. The present invention relates to a method for detecting an abnormality in a discharge line of an electrostatic precipitator for detecting an abnormality in the line.

[Background of the invention]

It is generally advantageous in terms of performance to operate an electrostatic precipitator at a higher charging voltage, so it is usually equipped with a control device that uses constant current control or a combination of constant current control and constant voltage control method, and is not equipped with a control device that uses constant current control or a combination of constant current control and constant voltage control method. In the event of a spark, the motor is operated at the output upper limit value (In, Vn shown in FIG. 2) set by the setting device of each control.

In addition, in order to prevent the transition from the corona discharge area to the arc and glow discharge area due to continuous spark generation when sparks occur,
"Spark tracking control", "Spark frequency control", "Spark integral control"
The electric precipitator is operated within the set value of the constant current or constant voltage by automatic spark generation control, which is generally referred to as spark generation, and the charging voltage and discharge current of the electrostatic precipitator are controlled depending on the spark generation situation.

The cause of this spark is the inlet gas of the electrostatic precipitator.
Examples include changes in dust conditions, etc., and changes in structural conditions within the electrostatic precipitator.

One of the structural conditions is disconnection due to deterioration of the discharge wire and abnormal phenomena such as loosening of the discharge wire, and conventional methods for detecting internal disconnections under these two conditions have been based on the charged voltage on the high voltage (output) side of the power supply There is a device called a "low voltage detection device" or "short circuit detection device" that outputs low voltage (input) side mold pressure, and uses the above-mentioned automatic repetitive spark control to detect when the charging voltage remains below a certain value Vu for a certain period of time. The device was constructed so that it would operate and stop charging if it continued for more than 10 minutes.

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

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

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

(b) When the discharge wire is broken, the discharge wire swings between the broken part and the support part, and the gap with the dust collecting electrode becomes wider or narrower.

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

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

In the case of (b), the frequency of spark occurrence increases at the charging point before disconnection or at a charging point below it, as at point A in FIG. However, over time, due to the effects of hammer blows, etc., it is possible that the condition may shift to state (c), but early diagnosis has not been possible in the past.

In case (c), sparks occur frequently, and the charging voltage and current change from point A to point B in Figure 2 due to the automatic spark control described above.
Since the zero point is eventually reached, it is possible to detect the driving state to a certain extent.

Furthermore, if slack occurs between the supporting points of the radiator 4vA, a situation similar to (b) will occur, and the conventional situation (b) cannot be detected or diagnosed during operation.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is particularly capable of detecting the condition (b) above, and detecting abnormal conditions such as disconnection or loosening of discharge wires in a short time while the electrostatic precipitator is in operation. An object of the present invention is to provide a method for detecting discharge line abnormalities in an electrostatic precipitator.

[Summary of the invention]

In order to achieve the above object, the present invention provides a discharge line abnormality detection method for an electrostatic precipitator in which a DC high voltage is applied between a discharge electrode and a precipitate electrode to collect dust in a flue. Detects the charging voltage and discharge current between the electrode and the dust collection electrode, stores the charging voltage during normal operation, and detects the charging voltage in a spark generation state based on the detected values of the charging voltage and discharge current. The present invention is characterized in that the discharge line is determined to be abnormal when it becomes lower than the stored charging voltage during normal operation and the spark generation state is periodic.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the method for detecting discharge line abnormality in an electrostatic precipitator according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, an AC power supply 10 is phase-controlled by a power control element 11, boosted by a transformer 12, DC-rectified by a rectifier 13, and discharged by a discharge electrode 2 of an electrostatic precipitator 20.
1 is applied to start corona discharge between the discharge electrode 21 and the dust collecting electrode 22, and the operation is started.

The charging voltage is detected by a charging voltage detection device 30 using a resistive voltage divider.
monitored by the output of The discharge current is monitored by the output of a discharge current detection device 40 using a shunt resistor.

When a spark discharge occurs within the electrostatic precipitator 20, that is, between the discharge electrode 21 and the dust collection electrode 22, the discharge current increases rapidly,
Due to the characteristic that the charging voltage drops, the charging voltage detection device 30,
The spark detection device 5 is activated by the output signal of the discharge current detection device 40.
0 is configured, and the output signal of the spark detection device 50 is input to the phase control device 53 for the power control element 11, and the power control element 11 is instantaneously configured to
An automatic spark control circuit is configured to gate off (stop charging) and slowly restore (recover) the charged state again. On the other hand, if the discharge electrode (wire) 21 is short-circuited to the dust collecting electrode 22 due to a break in the discharge electrode (wire) 21, etc., the above-mentioned automatic spark control circuit operates and the charging voltage gradually decreases to a state below the corona starting voltage Vc (Vu ) continues for a certain period of time or more, the low voltage detection device 51 activates the power control element 1.
Gate off 1 or turn off AC power supply 10
The protective device is configured to prevent

Now, in the present invention, a signal indicating the presence or absence of spark generation from the spark detection device 50 and a charging voltage are inputted to the microcomputer 52 via the spark detection device 50. Then, the microcomputer 52 detects an abnormality in the discharge electrode (line) 21 by executing the process shown in FIG.

In other words, the present invention provides that, when the discharge wire is oscillating due to disconnection or slack in the discharge wire, a spark discharge state occurs synchronously and the charging voltage at the time of spark generation is equal to the charging voltage during normal operation. By focusing on the fact that the discharge line is lower than the current value and detecting these conditions, abnormalities in the discharge line are detected.

In FIG. 3, first, the charging voltage Vn during normal operation is stored (step 100). Next, it is determined whether or not a spark has occurred (step 102), and if a spark has occurred, the spark generation voltage Vs is input (step 1).
04). Then, this spark generation voltage Vs is compared with the stored charging voltage Vn during normal operation, and the spark generation voltage Vs is
When s is lower than the charging voltage Vn during normal operation, the process proceeds to step 108, where spark generation synchronization is measured.

That is, in step 108, each time the condition is satisfied in step 106, the time until the next condition is satisfied is measured, and the measured time is stored.

Step 110 determines whether or not there is periodicity in the spark generation state from the measurement time stored in step 108, and if there is periodicity, it is determined that the discharge wire is oscillating due to disconnection or slack in the discharge wire. Otherwise, the process proceeds to step 112 on the assumption that an abnormality has occurred in the discharge line, where an alarm is generated.

Note that FIGS. 4(a) and 4(b) respectively show an example of the waveforms of the charging voltage and discharge current when the discharge line is abnormal. Here, the measurement time T, , T, may be T,=T2. Further, T5 and T2 are in the range of approximately 0°5 to 5 seconds.

〔Effect of the invention〕

As explained above, according to the method for detecting an abnormality in a discharge line of an electrostatic precipitator according to the present invention, an abnormality in the discharge line is detected based on the periodicity of the spark generation state, etc. It is possible to detect an abnormal state in which the discharge wire is loosened and swinging, and it is also possible to detect an abnormality in the discharge wire during operation of the electrostatic precipitator. Furthermore, by removing the abnormal part (separating it from operation), it is possible to prevent a significant decline in the electrostatic precipitator and significantly shorten the period of functional decline.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of the discharge line abnormality detection method of an electrostatic precipitator according to the present invention, FIG. 2 is a charging characteristic diagram of the electrostatic precipitator, and FIG. 3 is a microcomputer shown in FIG. 1. Flowchart showing an example of processing contents, FIG. 4(a)
) and (b) are waveform diagrams of charging voltage and discharge current, respectively, when the discharge line is abnormal. 10... AC power supply, 11... Power control element (Sirisk), 12... Transformer, 13... Rectifier, 20... Electrostatic precipitator, 21... Discharge electrode (discharge wire) , 22... Dust collection electrode, 30... Charge voltage detection device, 40... Discharge current detection device, 50... Spark detection device, 51... Low voltage detection device, 52...
- Microcomputer, 53... Phase control device. Applicant Hitachi Plant Construction Co., Ltd. Figure 2 Figure 3

Claims (1)

[Claims] In a discharge line abnormality detection method for an electrostatic precipitator that applies a DC high voltage between a discharge electrode and a dust collection electrode to collect dust in a flue, the charged voltage between the discharge electrode and the dust collection electrode is and detecting the discharge current, and storing the charging voltage during normal operation, so that the charging voltage in the spark generation state detected based on the detected values of the charging voltage and the discharge current is higher than the stored charging voltage during normal operation. becomes lower,
A method for detecting an abnormality in a discharge line of an electrostatic precipitator, characterized in that the discharge line is determined to be abnormal when the spark generation state is periodic.