JPS5855062A - Automatic voltage controlling device for electric dust collector - Google Patents

Abstract

PURPOSE:To increase dust collecting efficiency by detecting generation of reverse ionization, and lowering applied voltage until reverse ionization, is disappeared, and recharging after substantial extinction of residual charge of the dust layer. CONSTITUTION:Generation and magnitude of reverse ionization are detected by a reverse ionization detecting circuit 13 basing on values of secondary voltage 2 and secondary current 12. Reverse ionization detection signal 16 is given by the detecting circuit 13 and low output instruction 17 is given by an output change timing circuit 15 without delay. A low output setting circuit 18 compares the set value with actual secondary current to render the value predetermined low current value, and controls output 19 so that no difference generates between the two. Output 10 of an automatic voltage controlling device 21 is controlled by the output 19, and secondary current of an electric dust collector EP becomes a previously set value. Reverse ionization disappears at this time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic voltage control device for applying an appropriate discharge voltage to a discharge electrode of an electric industrial machine.

In order to increase the dust collection efficiency of electrical industrial dust equipment, it is necessary to apply as high a voltage as possible to the discharge electrode, but the voltage that can be applied is limited by the occurrence of spark discharge and reverse ionization phenomenon.

For this reason, various attempts have been made to apply as high a voltage as possible without causing sparks or reverse ionization.
), instead of applying a continuous DC voltage, a divided DC voltage whose interruption time interval can be adjusted (for example, Japanese Patent Publication No. 43
7110), ``In order to deal with the accumulation of high-resistance dust, the current between the electrodes is limited (Japanese Patent Publication No. 45-4600), and charging is periodically suspended (Japanese Patent Publications No. 52-598, No. 56 of the Sho.
-70859), and other known examples.

However, no attempt has yet been made to detect the occurrence of a reverse ionization phenomenon and automatically control the applied voltage in response to this, thereby increasing the dust collection efficiency.

The present invention detects the occurrence of a reverse ionization phenomenon and controls it by feeding back the detection signal, thereby reducing the voltage applied to the discharge electrode in immediate response to the occurrence of the reverse ionization phenomenon, thereby eliminating the reverse ionization phenomenon. By waiting for the battery to recharge before recharging, it is possible to increase dust collection efficiency and reduce power consumption.

First, a conventionally known method of detecting spark discharge and controlling voltage as shown in FIG. 1 will be briefly described. (For details, please refer to Japanese Patent Application Laid-Open No. 52-39868.

) Based on the current signal 1 and the voltage signal 2, the first detection circuit 3 generates a spark signal 4 according to the frequency of sparks, and causes the memory circuit 5 to store and output the spark voltage 6. Spark signal 4 activates spark integration circuit 7, which outputs spark magnitude 8. The spark signal 4 controls the output 10 at once to extinguish the spark.

Arithmetic circuit 9 receives spark frequency signal 4I spark voltage 6.
A clearance calculation is also performed for the spark size 8, and the speed of voltage recovery after the spark disappears and the voltage value after recovery are determined to control the output 10.

This operation allows the highest voltage to be applied without causing excessive sparking.

This control method has already been implemented and has achieved good results, but when the object of collection is high-resistance dust, it has the disadvantage of not being able to obtain a sufficient voltage if reverse ionization occurs.
That is, when a reverse ionization phenomenon occurs, even if the control circuit voltage is increased, the secondary voltage hardly increases and the secondary current only increases. This is because the characteristics of the secondary voltage V and secondary current (2) of reverse ionization are as shown in 12.13 in FIG. 2, which is significantly different from the characteristic 14 in the normal case. Figure 3 shows the changes in the secondary voltage ■ and the secondary current I obtained by controlling with the apparatus shown in Figure 1. When reverse ionization occurs, the ionization increases and the voltage decreases greatly, and as the voltage decreases, Dust collection performance will be significantly reduced.

Therefore, we improved the dust collection efficiency by detecting the occurrence of reverse ionization, lowering the applied voltage until the reverse ionization disappears, and recharging the dust layer after the residual charge has virtually disappeared. is the present invention. The details will be specifically explained below.

As mentioned above, the reverse ionization phenomenon significantly reduces the dust collection performance, but this reverse ionization phenomenon occurs due to excessive accumulation of electric charge in the dust layer, and the period until the excessive accumulation of electric charge is The period for normal charging is - charge - 夷鼠艙夜p extra charge amount, charging current.

Dust resistivity5. Determined by the dielectric breakdown voltage of the dust and the dielectric constant of the dust.

Dielectric breakdown voltage of dust $110Kv/C11 - Since the dielectric constant of dust is on the order of I x 1G"""F711, the allowable value of accumulated charge for normal charges is given by the product of both, and I per 111" of dust collection electrode. It is on the order of X 1G-'coulombs.

The time it takes for the charge to accumulate to this value is
Per 0. According to one calculation, when approximately 511A is flowed, the value is as follows.

When the resistance of dust is lXl013Ω・1, it is several tens of I. Taking advantage of the fact that normal charging is possible during the allowable charge accumulation period, a sufficiently high voltage necessary for dust collection is applied during this period. As a result, when reverse ionization occurs, the first purpose of the present invention is to detect the occurrence and immediately reduce the voltage below the voltage at which it disappears, thereby eliminating the reverse ionization. When ionization is detected and the voltage is lowered ~ the reverse ionization disappears quickly, but there is still a large amount of charge remaining in the dust layer, and as soon as the high voltage is recharged, reverse ionization will occur.

A second object of the present invention is to perform high-voltage recharging only after this residual charge has substantially disappeared.

The period required for this recharging is approximately 1 to 3 times the product of the permittivity of the dust and the resistance of the dust, and the resistance of the dust I
For X 10”Ω, a few seconds, 1×1012Ωse1m
Several hundred msa:, lXl011Ω5ell several tens of m5ec
There is no harm in thinking that.

Therefore, to determine this period, - it is necessary to know the resistance value of the dust - b! However, the inventors discovered that the intensity of back ionization depends on the resistance value of the dust, and if the intensity of back ionization is detected, the necessary charging pause (or lowering the voltage) can be performed. It was discovered that the period can be determined.

Therefore, there is a detection circuit that detects the occurrence of back ionization and its intensity, an arithmetic circuit that calculates the required low charging time from the intensity of the detected back ionization, and a An output switching timing circuit that operates to instantly switch from high voltage charging to low voltage charging in response to a reverse ionization generation signal and then switch to high voltage charging again after the required low charging time calculated by the above calculation circuit has elapsed is as shown in Figure 1. The structure of the present invention is added to a conventional automatic voltage control device.

A specific example of the present invention is shown in FIG.

A reverse ionization detection circuit 13 detects the occurrence of reverse ionization and the magnitude of the reverse ionization from the values of the secondary voltage 2 and secondary current 12.
Although this reverse ionization detection circuit was invented by Petter, filed on the same day, it is of course possible to use another method having a similar function (for example, see Japanese Patent Laid-Open No. 49-76167).

This detection circuit issues a reverse ionization detection signal 16, and the output switching timing circuit 15 issues a low output command 17 without time delay. In response to this command 17, the low output setting circuit 18 compares this set value with the actual secondary current so that the current value is a preset low current value, and controls the output 19 so that there is no difference between the two.

The output 10 of the automatic voltage control device 21 is controlled by the output 19, and the secondary current of the electrostatic precipitator EP becomes the preset current value.

At this time, the dust collector voltage becomes equal to or lower than the reverse ionization extinction voltage, so that reverse ionization disappears.

On the other hand, the low charging time calculation circuit 14 is connected to the reverse ionization detection circuit 13.
Calculate the low charging time from the magnitude of the output 16 of
0, the timing circuit 15 interrupts the low power command 17, thereby causing the low power signal 19 to
is switched to the high charge signal 19', and the output 10 of the automatic control circuit 21 returns to the highest possible voltage.

As a result, the voltage of the dust collector increases, resulting in sufficient corona discharge.

If reverse ionization occurs again, repeat the above operation,
It is automatically controlled to maintain the highest dust collection efficiency at all times.

Here is an example of how the secondary voltage ■ and secondary current change according to the present invention! ffe is shown in FIG. FIG. 7 is an enlarged view of the time shown in FIG.

FIG. 5 shows the case where the resistance of the dust is I x 10''Ω·c+m.

Although reverse ionization rarely occurs, reverse ionization is detected at the time indicated by BC and the charge shifts to low. Since the dust resistance value is relatively low, reverse ionization is short and the charging time is only several tens of hours. 1 when highly charged. As in the past, control is performed to prevent excessive sparks from occurring.

Figures 6 and 7 show that the resistance of the dust is 1 x 1012 to lX.
This is the case on the order of 1013 Ω·cm. An intense pack corona occurs in a few tens of seconds after the start of high charging, and a low charging time of several hundreds of times is required. However, these times are not constant and change every moment depending on the state of the deposited dust, the state of floating dust, vibration of the discharge line, etc., and the voltage and current become an irregular pulse train. (Pulse width.

Both cycles are irregular. ) According to the present invention, it is possible to optimally charge even dust of 5×10 Ω·1 or more, which would undergo severe reverse ionization under conventional control. Since excessive reverse ionization is prevented from occurring and a high voltage is temporarily applied, dust collection performance is greatly improved.

According to experiments, this method increases the dust collection movement speed by 30 to 40
Are you sure it will improve your attack? ! It was.

Further, according to this method, it is possible to almost eliminate the current that does not contribute to the dust collection effect when reverse ionization occurs, and the power consumption is reduced to several times that of the conventional control method.

Roughly speaking, even if the resistance of dust changes, the device of the present invention automatically adopts the optimal charging method at that time.

[Brief explanation of drawings]

Figure 1 is a diagram of a conventionally known spark detection control system. Figure 2 is a voltage-current characteristic diagram, and Figure 3 is a diagram of the current before and after the occurrence of back ionization.
Voltage change diagram, Figure 4 is a control circuit diagram of the present invention, 5th Wi
is a change diagram of secondary voltage V and secondary current l when the resistance of dust is on the order of I
Figure 7 is an enlarged view of Figure 6, which is a diagram of changes in the case of IX 1G'' to IX 1013Ω/saliva order.

Claims (1)

[Claims] Equipped with a reverse ionization detection circuit, a low charging time calculation circuit, an output switching timing circuit, and a low output setting circuit, the voltage applied to the discharge electrode of the industrial dust machine is reduced at the same time as reverse ionization is detected, and after a predetermined period of time, the An automatic voltage control device for an electric industrial dust machine, characterized in that the applied voltage is restored.