JPS594460A - Electric dust collector - Google Patents

Abstract

PURPOSE:To improve dust collecting capability for dust having high resistance and save power consumption, by providing plural charging chambers, and making respective applied current different by using changeover switches. CONSTITUTION:Changeover switches SW0, SW1, SW2 are so made that secondary current of full-wave rectification waveform, half-wave of front half or half- wave of rear half of half-wave rectification waveforms flow to each dust collecting electrode by their on/off operation. Secondary side changeover switches SW0, SW1, SW2 and primary side reactor ACL and slide rheostat SD are controlled for plural charging chambers according to a dust monitor DM that monitors the quantity of dust at the outlet of the dust collecting chamber to operate the dust chamber always at around the maximum dust collecting efficiency.

Description

[Detailed description of the invention] The present invention relates to an electrostatic precipitator.

Conventionally, as this type of dust collector, those using the si-risk control method have become common, but in such devices,
Soot dust with electrical specific resistance in the range of 1011 to 1013Ω-sub
(hereinafter referred to as dust), the dust collection performance is significantly degraded due to the occurrence of phenomena such as frequent sparks and reverse ionization.

The present invention was proposed in view of these circumstances, and aims to provide an electrostatic precipitator that improves dust collection performance against high-resistance dust, reduces the number of power supplies, and reduces power consumption. - In a device in which the commercial frequency power supply on the secondary side is converted to a secondary DC high voltage through a current control element such as a transformer, and this is applied to the dust collecting electrode in the charging chamber to collect dust. , a plurality of charging chambers, and selectively extracting the first half wave, second half half wave, and/or full wave of the secondary side DC high voltage and selectively applying them to the dust collection electrodes of the plurality of charging chambers, respectively. The invention is characterized in that it includes a changeover switch circuit.

An embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a circuit diagram thereof, FIG. 2 is a waveform diagram showing secondary currents in each part of FIG. 1, and FIG. 3 is a control flowchart of FIG. 1. figure,
Figure 4 is a diagram showing the amount of dust at the outlet of the dust collection chamber in Figure 1, Figure 5 is a voltage-current diagram of the dust collection electrode, and Figure 6 is a diagram showing the relationship between dust collection performance and control according to Figure 1. The diagram shown in FIG. 7 is a diagram showing the relationship between the specific resistance of dust and the optimum charging method in FIG. 1.

First, in Figure 1, SD is a SLIDAC that transforms AC220V, SCR is a thyristor inserted in the output circuit of SLIDAC SD and controlled by the thyristor control circuit 5CRC, ACL is a reactor inserted in the output circuit of the thyristor SCR, and MT is a transformer, REC is a rectifier % SW6 *SWt * SWl is a changeover switch inserted in the output circuit of the rectifier REC, EPk and EPB are a dust collection chamber with dust collection electrodes A and B, respectively, and DM is a dust collection chamber A dust monitor such as a light scattering type, a light transmission type, or a β-ray type is attached to the EPA to monitor the amount of dust, and the V/10 is attached to the dust collection chamber EPB to detect the voltage-current characteristics of the dust collection electrode. Detector, AND is connected to dust monitor DM, dust collection chamber EPA, EPB%v7e detector V/detector top/ID input terminal, selector switch S W6 a S Wl # S W @
This is an AND circuit in which the a reactor ACL and the slider SD are connected to output terminals, respectively.

In such a device, a changeover switch SW.

When SWl + SW2 are each on, a secondary current with a full-wave rectified waveform flows through each dust collection pole A and H, as shown in FIG. 2 (4), and the switch SW.

is on % When SW1 or SW is on, the secondary current of full-wave rectification in the figure (in the figure) flows only in the dust collection electrode A or B, respectively, the changeover switch SWo is off, and SWi and 8W=
When each is on, a waveform secondary current flows.

Here, the conduction angle β of the secondary current is 90° in the same figure, but if the stain source is 60 cycles due to slideac SD, reactor ACL, thyristor SCR, etc., it will be 0 to 8 ms.
It can be controlled within the range of .

■ First, when the dust collection efficiency of the dust collection chamber decreases and the amount of dust coming out of the dust collection So increases, the output signal of the dust monitor DM becomes Ks8om□ as shown in Figure 4.
Therefore, as shown in FIG. 3, the following charging enhancement operation is started by the action of each control device.

(1) Increase the number of charging chambers to reduce the amount of dust so MAN
If it is below, keep it under control. At that time, only one or two chambers on the rear chamber side are controlled, and if there is sufficient performance margin, charging to some chambers may be turned off.

(2) If the amount of dust exceeds so MAX, as described later, if the output signal of the V/I detector is output, switch from full-wave charging to half-wave charging by turning off the changeover switch SWo. However, if the output signal of the V/I detector does not appear,
This switching is not performed. Dust amount So is so WAX
If the condition is below, the condition will be maintained. The following controls are effective when reverse ionization is occurring. Here, each dust collection room EPA, F! In the PR V/I detector, the change in current I when the voltage V of the precipitate electrode is gradually increased from O is determined by microcomputer control at regular time intervals as shown in Figure 5. When the value exceeds 5), it is assumed that reverse ionization has occurred and an output signal is output.

(3) When the dust amount SO is more than so MAW, gradually reduce the reactor ACL (see FIG. 6). Here, the reactor ACL is variable in about 3 stages')
, S6MAX or below, it is maintained in that state.

(4) The amount of dust is so MA! In the above case, the negative voltage is boosted. Here, the negative voltage is 100 to 220v
is variable in five steps, and the dust amount detection and primary voltage boost are repeated. At this time, the thyristor SCR is subjected to constant current control or spark control regardless of the above control.

Combining the above, the standard state of the control device is control (1):
All-room charging control (2): Full-wave charging (switch 8Wo remains on)
Control (3): Reactor ACL is large control (4) Secondary voltage is 100 ■ When operating under control (1), control (2)
Thereafter, when the vehicle is operating under control (2), control (4) is set to the standard state when the vehicle is operating under control (3).

■ When the dust collection efficiency of the dust collection chamber increases and the amount of dust coming out So falls far below the guaranteed value, the way the dust is coming out from the dust monitor ~ DM will change.
If the value falls below the value corresponding to , the number of charging chambers is reduced and energy saving operation B is started.

That is, the number of charging chambers is first reduced by one, and if the amount of dust is still less than So old N, the number of charging chambers is further reduced.

1[I To describe the control from V/I characteristics, the product of the peak value V of the dust collecting electrode voltage and its average value v0 VpX v□
As shown in Figure 6, there is a correlation with dust collection performance, and the peaks of both occur in correspondence with each other, so vpxVrn
Adjust each switch SW on the secondary side so that the value of
l a S Wl # Controls the S Wl, the primary side reactor ACL, and the slideac SD.

At that time, the control is based on the signals of the dust monitor DM and the V/I detector V/ID.As shown in the figure, 1 is full wave charging, 2 is half wave charging, and 3 to 5 are reactor kCL. , 6~
10 is performed by charging the voltage waveform on the secondary side of the Slidac 8DK to make it sharper. Among these controls, 1 is effective for dust that collects well, and 10 is effective for dust that is expected to collect well.

At this time, the V, If Vpx V, , in control 2 is larger than that in control IK, proceed further to hunt roll 3, and if v, xvrrl value in control 3 is smaller than that in control 2, conversely, control 2 By returning to Control 2 and proceeding to Control 1 or 3 in the same manner, the dust collection chamber is always operated near the maximum dust collection efficiency vpx VrnMAX.

Control points 1 described above. When n and m are combined, the result is as shown in FIG.

In short, according to the present invention, the commercial frequency power supply on the negative side is converted to a secondary DC high voltage through a current control element such as a transformer or thyristor, and this is applied to the dust collecting electrode in the charging chamber to collect the secondary side. In a device configured to collect dust, a plurality of charging chambers are used, and the helmsman's cow wave, rear driver's half wave, and/or full wave of the secondary side DC high voltage are selectively taken out and collected in the plurality of charging chambers. The present invention is industrially extremely useful because it provides a highly efficient electrostatic precipitator equipped with a switch circuit that selectively applies voltage to each electrode.

[Brief Description of the Drawings] Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
Figure 3 is a waveform diagram showing the secondary current in the circulating section, Figure 3 is a diagram showing the control flowchart of Figure 1, Figure 4 is a diagram showing the amount of dust at the outlet of the dust collection chamber in Figure 1, and Figure 5 is a diagram showing the amount of dust at the outlet of the dust collection chamber in Figure 1. The voltage-current diagram of the dust collection electrode. Figure 6 is a diagram showing the relationship between dust collection performance and control according to Figure 1. Figure 7 is a diagram showing the relationship between the specific resistance of dust and the optimal charging method in Figure 1. FIG. A, B... Dust collection electrode, ACL... Reactor, AND
.... AND circuit, DM...Dust monitor, EPA, EP
B...dust collection chamber, MT...transformer, REC...rectifier, SCR thyrisk, 5CRC...thyristor control circuit, SD...Slyduc s S We a
S Wl + S Ws...Choice switch, V/
ID...V/Z detector.

Claims (1)

[Claims] In a device in which the primary side commercial frequency power source is converted to a secondary side DC high voltage through a current control element such as a transformer or thyristor, and this is applied to the dust collection electrode in the charging chamber to collect dust, Selectively extracting the first half wave, second half half wave and/or full wave of the plurality of charging chambers and the secondary side DC high voltage and selectively applying them to the dust collecting electrodes of the plurality of charging chambers. An electrostatic precipitator characterized by comprising a changeover switch circuit.