JPS6231985B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic precipitator, and more particularly to an electrostatic precipitator equipped with a circuit that continuously detects an applied voltage waveform.

The voltage applied to the discharge electrode of an electrostatic precipitator is usually a high voltage obtained by transforming power from a commercial AC power supply, and then rectified into DC voltage by a rectifier, so its waveform is similar to that of a commercial AC power supply. The waveform has peaks and valleys that repeat continuously in response to the power supply cycle. Therefore, the value at the peak of this applied voltage waveform is usually called the peak value, the value at the trough is called the bottom value, and the average value is called the average value.

In conventional electrostatic precipitators, the average value of the voltage applied to the discharge electrode is measured, and this measured value is used to control the power control element in the power supply section, and the voltage is applied to the spark generation state that will result in the highest dust collection rate. Adjusting the voltage. Furthermore, in order to optimally control the applied voltage during discharge, a method has been adopted in which the peak value of the applied voltage is detected and the waveform of the applied voltage is continuously determined from this and the average value.

In recent years, electrostatic precipitators for collecting high-resistance dust, which tend to cause back ionization when a certain amount of high-resistance dust adheres, have been introduced to detect the occurrence of back ionization from ripples in the voltage waveform in addition to the above-mentioned control. is proposed. What is important in this ripple detection is to detect the bottom value of the voltage waveform, but there has been no detection circuit that can continuously detect this bottom value.

That is, it has been difficult to construct a circuit that continuously detects the bottom value because it includes a voltage drop factor when a spark occurs inside the electrostatic precipitator.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the prior art, to prevent the influence of voltage drop when sparks occur, and to provide an electrostatic precipitator that can accurately detect the bottom value of applied voltage.

The present invention detects the degree of voltage drop (dv/dt) of the applied voltage when spark discharge occurs inside the electrostatic precipitator using a spark waveform removal circuit, and detects the degree of voltage drop (dv/dt) of the applied voltage when spark discharge occurs inside the electrostatic precipitator, and uses this circuit to detect the voltage drop depending on the time required to remove the spark waveform. A constant level voltage is output and this signal is added to the input signal applied to the bottom value detection circuit.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

Power from the commercial AC power source 10 is supplied to the transformer 14 via a power control element 12 whose amount of current is controlled by phase control. A high-voltage rectifier 16 is connected to the secondary output terminal that generates high voltage, and on the output side of the rectifier 16 is a dust collection section 22 in which discharge electrodes 18 and dust collection electrodes 20 are arranged alternately at a constant interval. At the same time, a series circuit of a high voltage resistor 24 and a detection resistor 26 is connected in parallel to the dust collecting section 22 . The voltage between the connection point of both resistors and ground (i.e., the voltage between the sense resistor 2
6) is amplified to a required voltage level by an amplifier 28, and then a peak value detection circuit 30 detects the peak value of the applied voltage as an applied voltage signal a;
Average value detection circuit 32 that detects the average value of applied voltage
and a spark waveform removal circuit 34 that detects the voltage drop degree (for example, dv/dt) of the applied voltage due to sparks.
is applied to each of the Further, the output signal of the amplifier 28 is applied to an adder 36, a signal outputted at a predetermined time from the spark waveform removal circuit 34 is applied to the adder 36, and the added signal is a bottom value for detecting the bottom value of the applied voltage. It is output to the value detection circuit 38.

peak value detection circuit 30, average value detection circuit 32,
Spark waveform removal circuit 34 and bottom value detection circuit 3
8 and a phase control signal of a phase control circuit 42 for controlling the phase of the power control element 12 are applied to a monitoring circuit 40 to monitor the occurrence of a reverse ionization phenomenon.

In the above configuration, the power control element 12 is controlled so that the power supply corresponding to the applied voltage required by the dust collector 22 is supplied to the transformer 14, and the voltage boost generated at the secondary terminal of the voltage generator 14 is controlled. After the high voltage is double-wave rectified by the high voltage rectifier 16, it is applied to the discharge electrode 18 and the dust collection electrode 20 of the dust collection section 22, corona discharge is performed, and the gas to be processed flowing between the two electrodes is Dust and the like are collected on the dust collecting electrode 20. on the other hand,
The applied voltage divided by the high-voltage resistor 24 and the detection resistor 26 is amplified by the amplifier 28, and then applied to each of the peak value detection circuit 30, average value detection circuit 32, spark waveform removal circuit 34, and adder 36. be done.
Each output signal of the peak value detection circuit 30, average value detection circuit 32, and bottom value detection circuit 38 is sent to the monitoring circuit 4.
The monitoring circuit 40 determines the occurrence of a reverse ionization phenomenon based on a decrease in the average value of the charge voltage, an increase in the waveform peak value of the discharge current, and a decrease in the bottom value.

On the other hand, when a spark discharge occurs within the dust collecting section 22, the power control element 12 is controlled by the phase control circuit 42.
Generally, the applied voltage is rapidly reduced to extinguish the spark discharge.
Therefore, the degree of voltage drop in the applied voltage during spark extinguishing control is detected by calculating dv/dt, and as shown in Figure 2, the signal b at a constant level is maintained at the same time as the spark discharge occurs (position P in the figure). The signal b is output from the spark waveform removal circuit 34 for the time period, and this signal b is sent to the adder 36.
and the output signal c added to the applied voltage signal a.
is sent to the bottom value detection circuit 38. The width of the signal b output from the spark waveform removal circuit 34 is as follows:
As shown in FIG. 2, the sum of the spark extinguishing time Ta and the charge recovery transient time Tb is selected so that Ta+Tb=Th.

Since the output signal c has a voltage value higher than the level detected during normal corona discharge within the time Th, when detecting the bottom value, even when a spark occurs, the bottom detected value is as shown in Fig. 2. It is not affected in any way. In the bottom value detection circuit 38, the detection time width is synchronized with that of the commercial battery, for example, about 5 cycles, and this is continuously sampled. The bottom detection value is taken out from the output terminal 44 via the monitoring circuit 40 and used for judgments such as humidity adjustment.

The inventors observed using a synchroscope and confirmed that the configuration shown in FIG. 1 allows data to be obtained with an accuracy of within 2.5%.

In the above explanation, an example has been shown in which the device is incorporated into a dust collector, but it is also possible to configure a dedicated reverse ionization detection device independently.

As is clear from the above, according to the present invention, the bottom value detection result of the applied voltage is not affected by spark discharge, and the applied voltage waveform (bottom value) is accurate.
can be detected.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram showing the operation of each part of the embodiment of FIG. 10...Commercial AC power supply, 12...Power control element, 14...Transformer, 16...High voltage rectifier, 22
... Dust collection section, 24 ... High voltage resistor, 26 ... Detection resistor, 28 ... Amplifier, 30 ... Peak value detection circuit, 32 ... Average value detection circuit, 34 ... Spark waveform removal circuit, 36 ... Adder, 38 ... Bottom value detection circuit, 40 ... Monitoring circuit, 42 ... Phase control circuit.

Claims (1)

[Claims] 1. In an electrostatic precipitator equipped with a spark control circuit that extinguishes spark discharge when it occurs and a bottom value detection circuit that detects the occurrence of reverse ionization from the bottom value of the applied voltage, the voltage drop in the applied voltage due to spark discharge a spark waveform removal circuit that detects the degree of the spark discharge and generates a signal at a constant level from the start of the spark discharge to the return of charge, and an added value of the signal output from the circuit and the applied voltage signal corresponding to the applied voltage. An electrostatic precipitator comprising: an addition section that sends the bottom value detection circuit to the bottom value detection circuit.