JPH08224500A - Electrostatic precipitator - Google Patents

Abstract

PURPOSE: To make it possible to surely execute cleaning with a small quantity of injected air by providing electrostatic precipitation units laminated and arranged in plural stages vertically via partition plates with captured dust- dislodging air blow pipes by which pressurized air is supplied to every electrostatic precipitation unit. CONSTITUTION: The cleaning of the other electrostatic precipitation units 10b to 10d is executed by successively changing over the open stages of rear part shutters 20a to 20d and the ejection stages of the air blow pipes 31a to 31d when the cleaning of the electrostatic precipitation unit 10a of the uppermost stage is completed. The dislodgment of the dust of the respective electrostatic precipitation units 10b to 10d is executed by changing over the air ejection for cleaning of the air blow pipes 31a to 31d in such a manner. The smaller quantity of the air to be ejected for the purpose of cleaning and quantity of the air to be sucked to a dust recovering device 6 section than for simultaneous cleaning of the entire electrostatic precipitation unit is, therefore, required. Then, smaller sizes and capacities are required for a compressor 22, exhaust fan 4 of a dust recovering device 6, bag filter 5, discharge pipe 8, damper 7, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic precipitator for removing dust in dust-containing air.

[0002]

2. Description of the Related Art Generally, as a method for purifying dust-laden air in a tunnel for an automobile road, the dust-laden air is fed into a flow passage provided as a detour on the side of the tunnel or the like, and is introduced into the flow passage. A purification method in which a dust collector is installed to collect dust and the air after dust removal is circulated back into the tunnel is widely adopted. Since the dust removal target is a large amount of air in which fine particles are suspended, an electric dust collector is often used as the dust collector.

In this electrostatic precipitator, the dust that has passed through the charging portion and is charged is collected and accumulated on the dust collecting electrode plate of the dust collecting portion, so that the dust accumulated on the dust collecting electrode plate. It is necessary to periodically separate and collect the dust.To this end, air is generally sprayed between the dust collector plates to scavenge dust, and the dust-containing air is sucked in and collected by a bag filter or the like. The dust collector is cleaned and regenerated (hereinafter simply referred to as "cleaning") by dusting.

[0004]

However, at the time of cleaning the above dust collecting electrode plate, for many dust collecting electrode plates arranged in parallel at a small interval in the dust-containing air flow passage having a large cross-sectional area, A large-capacity compressed air supply device is required to inject air for dust removal all at once, and the exhaust fan and the filter dust collection device for filtering dust of the removed dust are also of high capacity and power. In addition, the suction and exhaust passage has a large cross-sectional area, and the equipment cost and the installation space are large.

Further, the dust that has been removed during the conventional removal of dust reattaches to the cleaned electrode plates and frames,
There is also a problem that the dust is scattered on the outflow side of the dust collecting part when restarted after cleaning.

The present invention solves the above-mentioned problems of the prior art, in which dust can be blown off by a small amount of air blown, the facility cost is low, and the installation space is small. The purpose is to provide a device.

Another object of the present invention is to provide an electrostatic precipitator which does not cause reattachment of dust to other cleaned electrode plates, frames and the like during cleaning.

[0008]

In the electrostatic precipitator of the first invention of this application, an electrostatic precipitator unit having a charging section and a precipitating section is vertically arranged in a casing via a partition plate. A plurality of stacked layers are arranged, and a rear shutter that is controlled to be opened / closed for each electrostatic dust collection unit is provided at the outlet of the casing, and a dust-containing air flow is blocked at the inlet of the casing. An inlet shutter of the electric dust collecting unit is provided with a space between the dust collecting unit and the dust collecting unit, and an air outlet facing the dust collecting unit is provided on the outflow side of the dust collecting unit. ) Is provided with an air blower pipe for sweeping away collected dust, and a dust discharge duct for discharging an air flow containing the dust that is discharged is opened at the bottom of the space. Dust-containing air flows through the electric dust collector Multiple Motonami was set into the passage, the dust discharge duct, is characterized in that connected to the dust collecting apparatus having an exhaust fan and dust separation filter.

In the electrostatic precipitator according to the second aspect of the present application, the electrostatic precipitator unit having a charging section and a precipitating section is arranged in a plurality of layers vertically in the casing via a partition plate. A front shutter is provided on the inflow side of the electrostatic precipitator unit for controlling the opening and closing of each of the electrostatic precipitator units, and an inlet shutter for blocking the dust-containing air flow is provided at the inlet of the casing. Is provided with a space between it and the front shutter, and has an air outlet facing the dust collecting section on the outflow side of the dust collecting section for pressurizing each of the electrostatic dust collecting units. An electrostatic precipitator which is provided with an air blower tube for blowing away the collected dust to which air is supplied, and which has a dust discharge duct for discharging an air flow containing the dust which is blown off at the bottom of the space. In the flow passage through which dust-containing air flows. And Motonami設, the dust discharge duct, is characterized in that connected to the dust collecting apparatus having an exhaust fan and dust separation filter.

Further, in the electrostatic precipitator of the third invention of this application, the electrostatic precipitator unit having the charging section and the precipitating section is arranged in a plurality of layers vertically in the casing through a partition plate. An outlet shutter is provided at an outlet of the casing with a space between the dust collecting unit and the electric dust collecting unit, and a fumarole facing the dust collecting portion on the inflow side of the charging portion via the charging portion. An air blower pipe for removing the collected dust, which is provided with pressurized air and is provided for each of the electric dust collecting units, has a dust discharge for discharging an air flow containing the dust. A plurality of electric dust collectors each having a duct opened at the bottom of the space are arranged side by side in a flow passage through which dust-containing gas flows, and the dust discharge duct is provided with an exhaust fan and a dust separation filter. Characterized by being connected to a dust recovery device To.

In the electrostatic precipitator according to the third aspect of the invention, a rear shutter is provided on the outflow side of the electrostatic precipitator of the electrostatic precipitator unit, and the opening / closing control is performed for each of the electrostatic precipitator units. When a space is formed between the outlet shutter and the outlet shutter, the rear shutter of the electrostatic precipitator unit other than the cleaning target is closed, so that the air flow including the dust removed during cleaning of the dust collecting electrode plate is cleaned from the flow passage portion. It is preferable because it can prevent backflow into the electrostatic precipitator unit other than the target.

[0012]

In the electric dust collector of the present invention, the air blown out from the air blower port of the air blower is blown between the dust collecting electrode plates of the dust collecting portion to remove dust accumulated on the dust collecting electrode plates. The dust that has been blown off flows as a downward flow in the space portion and is sucked and collected from the dust discharge duct portion to the dust collecting device portion.

Air can be ejected from each of the above-mentioned air outlets for each electrostatic precipitator unit, and the pressurized air blown into the electrostatic precipitator unit is vertically adjoined to another electrostatic precipitator unit. Since the partition plate blocks the inflow, it is possible to reliably clean the inside of the electrostatic precipitator unit to be blown with a small amount of blowing air, and a large amount of dust that has been brushed off in the other cleaned electrostatic precipitator units. There is no possibility that it will flow into the chamber and cause pollution such as electrode plates and frames.

In the electrostatic precipitator of the first and second aspects of the invention, since the entrance shutter is closed to clean the dust collecting electrode plate, another electric precipitator arranged in parallel with the electric precipitator to be cleaned is provided. The dust collector can perform electrostatic collection of dust-containing air flowing in the flow passage in parallel with the above cleaning.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the first invention will be described below with reference to FIGS. In the figure, reference numeral 1 denotes a flow passage through which dust-containing air flows, which is provided on a side of a tunnel for an automobile road in a bypass shape with respect to the tunnel, and an air blower (not shown) is provided on the upstream side. A plurality of the flow passages 1 are provided in parallel, and an electric dust collector described below is installed in each flow passage. Reference numeral 2 denotes an electrostatic precipitator, which is a dust collecting apparatus having a plurality of electric precipitators 3A and 3B (two in this embodiment) arranged side by side in the flow passage 1 and having an exhaust fan 4 and a bag filter 5. 6 is connected to a dust discharge duct 29 (described later) of each of the electric dust collectors 3A and 3B by an exhaust pipe 8 via dampers 7A and 7B. This dust recovery device 6
Is installed in the auxiliary equipment room together with compressors 22 and 35 described later.

The electrostatic precipitators 3A and 3B have the same structure except that the connection ports of the pipes and the positions of the driving ends of the shutters are symmetrical positions, and the same parts are designated by the same reference numerals. It is shown. 10a to 10d are charging parts 11
An electric dust collecting unit having a dust collecting portion 12 and a charging portion 11 in which the charging portion 11 is a positive discharge electrode and a negative electrode plate facing the discharge electrode, and the dust collecting portion 1
Reference numeral 2 has a known structure including a positive electrode plate and a plurality of dust collecting electrode plates facing the positive electrode plate. It is connected. And dust collection unit 10
The layers a to 10d are vertically stacked in four layers in the casing 15 with a partition plate 16 interposed therebetween.

When the bottom surface or the top surface of the housing of the electrostatic precipitator unit 10 (a generic name for the electrostatic precipitator units 10a to 10d. The other parts are also generically referred to hereinafter) is covered with a bottom plate or a ceiling plate. The bottom plate or the ceiling plate may be used as a partition plate, and the separate partition plate 16 may be omitted.

Numerals 20a to 20d are rear shutters provided at the outlet of the casing 15, each of which is provided with an air cylinder type opening / closing machine 23 connected to a compressor 22 through an electromagnetic opening / closing valve 21. It is opened and closed for each unit 10. Reference numeral 24 denotes an inlet shutter provided at the inlet of the casing 15, which is connected to the pipe 2 via an electromagnetic opening / closing valve 25.
6 is opened and closed all at once by an air cylinder type opening / closing operation device 27 connected to the compressor 22. A space 28 is formed between the entrance shutter 24 and the electrostatic precipitator unit 10, and an opening 29a at one end of a dust discharge duct 29 provided at the bottom of the casing 15 is provided at the bottom of the space 28. It has been opened.

Further, 31a to 31d are air blow pipes provided on the outflow side of the dust collecting portion 12, each having an air ejecting port 32 facing the dust collecting portion 12, and an air blow pipe by a pressure pipe 34 via an electromagnetic opening / closing valve 33. It is connected to a compressor 35 for air-conditioning, and pressurized air for air blow is supplied to each of the electrostatic precipitator units 10.

In the electrostatic precipitator 2 having the above structure, when the dust-containing air G flowing in the flow passage 1 is collected, as shown in FIGS. 1 and 2, two electric precipitators 3A, The 3B inlet shutter-24 and all rear shutters 20 are opened, and the total electrostatic precipitator unit 10 is opened.
Dust in the circulating dust-containing air is electrostatically collected.

Next, when dust is accumulated on the surface of the dust collecting electrode plate of the dust collecting portion 12 of the electric dust collector 3A due to long-term dust collecting, in order to clean it, as shown in FIGS. 3 and 4. First, the inlet shutter 24 of the electric dust collector 3A to be cleaned is closed, only the rear shutter 20a of the uppermost electric dust collector unit 10a is opened, and the other rear shutters 20b to 20d are closed and the damper 7A is closed. The dust collecting device 6 is operated by opening the electric dust collecting unit 10.
Pressurized air is ejected from the air outlet 32 of the air blow pipe 31a of the portion a.

The jet air is used as the electrostatic precipitator unit 10a.
3 is blown at high speed between the dust collecting electrode plates to scavenge the dust accumulated on the dust collecting electrode plate, and this dust is the space inside the closed entrance shutter 24 as indicated by the arrow P in FIG. It flows as a downward flow in 28, flows in the dust discharge duct 29 from the opening 29a, is sucked by the dust recovery device 6 and is collected.

At this time, by setting the exhaust amount of the exhaust fan 4 to be larger than the flow rate of the air blow of the air blow pipe 31a, the air in the flow passage 1 flows in from the opened rear shutter 20a, and this inflow air is also blown off. It acts as a dust-carrying air stream and prevents blown-off dust from polluting the surrounding area.

When the cleaning of the uppermost dust collecting unit 10a is completed, the opening stage of the rear shutter 20 and the jetting stage of the air blow pipe 31 are sequentially switched to clean the other dust collecting units 10b to 10d. Good.

As described above, since the cleaning air jets of the air blow tubes 31a to 31d are switched to blow off the dust of each electrostatic precipitator unit 10, the cleaning air jet amount and the dust collecting device 6 parts. The suction air volume to
Much smaller than cleaning all the electrostatic precipitator units at the same time (about 1/8 in this embodiment, but if the number of stacked layers of the electrostatic precipitator units and the number of the installed electrostatic precipitators in parallel are large, the amount is even smaller. It will be). Therefore, the exhaust fan 4, the bag filter 5, the exhaust pipe 8, the damper 7, etc. of the compressor 22 and the dust recovery device 6 may all be small and have a small capacity, and the installation space for these devices can be small.

Next, FIGS. 5 to 8 show an embodiment of the second invention. In the drawings, the same parts as those of the above-mentioned embodiment are designated by the same reference numerals and the detailed description thereof will be omitted. The electrostatic precipitators 41A and 41B of the electrostatic precipitator 40 eliminate the rear shutter 20 in the above-mentioned embodiment, and instead, replace the front shutter 42a with the same structure as the rear shutter 20.
.About.42d are provided on the inflow side of each of the electric dust collecting units 10a to 10d. The front shutter 42 is opened / closed for each electrostatic precipitator unit by an air cylinder type opening / closing machine 23 connected to a compressor 22 via an electromagnetic opening / closing valve 21, respectively. A space 28 is formed between the front shutter 42 and the entrance shutter 24, and the other structure is the same as that of the above-described embodiment.

When the dust-containing air G is collected by the electrostatic precipitator 40, as shown in FIGS. 5 and 6, the entrance shutters 24 and all front portions of the two electrostatic precipitators 41A and 41B are collected. The shutter 42 is opened, and the dust in the circulating dust-containing air is electrostatically collected by the all-electric collection unit 10.

Next, in order to clean the dust collecting electrode plate of the dust collecting portion 12, the electric dust collecting unit to be cleaned, for example, the electric dust collecting unit 10a of the electric dust collector 41A as shown in FIGS. 7 and 8. In the same manner as in the above-described embodiment, only the front shutter 42a of the above is opened and the inlet shutter 24 is closed, and pressurized air is ejected from the air blow pipe 31a of the electrostatic precipitator unit 10a to wipe off the accumulated dust. You can do it.

Electric dust collecting unit 10b other than the cleaning target
Since the front shutters 42b to 42d of 10d to 10d are closed, the airflow containing the dust that has flown into the space 28 does not flow back into the electrostatic precipitator units 10b to 10d to cause pollution. The flow passage 1 flows in the portion 28 as a downward flow, and also by the suction pressure of the exhaust fan 4.
The air inside does not flow in the electrostatic precipitating unit 10 other than the cleaning target as illustrated by an arrow Q, and flows exclusively in the cleaning target electrostatic precipitating unit 10a and is used for transporting dust.

Next, FIGS. 9 and 10 show an embodiment of the third invention (provided with a rear shutter according to claim 4), in which the same or corresponding parts as those of the above embodiment are the same. Reference numerals are given and detailed description thereof is omitted. The electrostatic precipitators 51A and 51B of the electrostatic precipitator 50 of this embodiment
Is the entrance shutter-2 in the embodiment of the first invention.
4 is removed and the air blow tube 31 is replaced with the electrostatic precipitator unit 1
0 to the inflow side, the fumarole 32 is opposed to the dust collecting portion 12 via the charging portion 11, the rear shutter 20 is arranged close to the electric dust collecting unit 10, and the casing 15 is provided.
A vertical outlet shutter 52 is provided at the outlet of the, and the closed outlet shutter 52 and the rear shutter shown by the solid line are shown.
The space 28 is formed between the space 20 and the space 20. The dust discharge duct 29 has an opening 29a that opens below the space 28.

The outlet shutter 52 supports the bases of two vertically long blades 53a and 53b, whose front ends are bent, on the casing 15 so as to be rotatable about a vertical axis, and an opening / closing drive not shown. Thus, the forward / reverse rotation drive is performed from the closed (flow path closed) position shown by the solid line to the open (flow path open) position shown by the chain line 54. At the lower end of the blade 53,
Horizontally extending fin plate-shaped end plates 55a and 55b, which face the upper surface of the bottom plate 15a of the single 15 at a small interval, are connected in series, and the blades whose tip portions abut each other at the open position indicated by the chain line 54. The opening 29a of the dust discharge duct 29 is closed by the 53a and 53b and the end plates 55a and 55b.

Numeral 57 is an air ejection nozzle provided downward on the top of the casing 15 for ejecting pressurized air into the space 28 and flowing out from the electrostatic precipitator unit 10 to be cleaned into the space 28. When an air flow containing dust is driven downward to surely form a downward flow in the space 28, when the suction pressure by the exhaust fan 4 of the dust recovery device 6 (see FIG. 1) is large. May be omitted.

In the electric dust collector 50, the dust collecting electrode plate of the dust collecting portion 12 is cleaned by stopping the operation of the blower upstream (or downstream) of the flow passage 1 so that the dust-containing air G does not flow. Then, do it. The point that the rear shutter 20 is opened for each electrostatic precipitator unit 10 to be cleaned and the accumulated dust is removed by the air blown from the air blow tube 31 is the same as in the above-described embodiment (the figure shows the electrostatic precipitator 51).
(A shows the cleaning state of the electric dust collecting unit 10a), and the dust that has been blown down descends in the space 28 and is sucked and collected by the dust collecting device 6 (see FIG. 1) through the dust discharge duct 29.

FIG. 11 shows an electrostatic precipitator 60 in which the vertical outlet shutter 52 shown in FIG. 9 is a horizontal batch open / close type similar to the inlet shutter 24 shown in FIG. This is the same as the electrostatic precipitator 50 of No. 9.

Next, the electrostatic precipitator 70 shown in FIG.
The rear shutter 20 in FIG. 9 is omitted, and the outlet shutter 52 is arranged close to the electrostatic precipitator unit 10. In other structures as well, the circulation of the dust-containing air G in the flow passage 1 is stopped to collect. The point of cleaning the dust collector plate is also the same as that of the electrostatic precipitator 50 in FIG. 9.

In this embodiment, the electrostatic precipitator unit 10 to be cleaned (in the figure, the electrostatic precipitator unit 1 is shown).
When the pressurized air is blown out by the air blower pipe 31 of the part 0a), the suction pressure of the dust recovery device 6 (see FIG. 1) also directs the electric dust collecting unit 10 other than the cleaning target toward the space 28 side. An air flow indicated by the arrow Q is generated, which prevents the air flow containing the dust particles falling in the space 28 from flowing into the electrostatic precipitator unit 10 other than the cleaning target.

The present invention is not limited to the above embodiments, and for example, the number of stacked stages of the electrostatic precipitator unit,
The number of electric dust collectors arranged in parallel may be other than the above, and the air blower tube may be one that swings around the horizontal axis or one that reciprocates in the horizontal axis direction.

Further, in the above-mentioned embodiment, the cleaning is performed for each electrostatic precipitating unit, but a small number (for example, two in the above-mentioned embodiment) of the electric precipitating units are stacked with respect to the number of stacked layers or the total number of units. For the dust collection unit,
Cleaning may be performed at the same time, in which case the total cleaning time is short.

[0039]

As described above, according to the present invention,
For the electrostatic precipitating units arranged in a plurality of layers vertically above and below via the partition plate, an air blower pipe for removing the collected dust, to which pressurized air is supplied for each electrostatic precipitating unit, is provided. Or, by sequentially ejecting air from the air blower tube to a small number of electric dust collecting units, it is possible to surely perform cleaning with a small amount of air blown,
The compressed air supply device for the blast air, the dust collection device for sucking and removing the dust that has been blown off, and the suction and exhaust passages thereof may be of small size and small capacity, and the installation space for these devices is also small. Complete. In addition, since the partition plate is provided, dust that has been removed during cleaning does not flow into another electrostatic precipitator unit and reattach to the cleaned electrode plate or frame.

Further, in the first and second aspects of the invention, since the entrance shutter for blocking the dust-containing air flow is provided at the entrance of the casing, by closing the entrance shutter, the dust in the flow passage is impregnated. The dust collecting electrode plate part can be cleaned without stopping the air flow.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view including an equipment connection system of an electrostatic precipitator showing an embodiment of a first invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a vertical cross-sectional view showing a state where a dust collecting electrode plate of the electric dust collecting apparatus of FIG. 1 is cleaned.

4 is a sectional view taken along line BB of FIG.

FIG. 5 is a vertical sectional view including an equipment connection system of the electrostatic precipitator showing an embodiment of the second invention.

6 is a cross-sectional view taken along the line CC of FIG.

FIG. 7 is a vertical cross-sectional view showing a dust collecting electrode plate cleaning state of the electric dust collecting apparatus of FIG.

FIG. 8 is a sectional view taken along line DD of FIG. 7;

FIG. 9 is a vertical cross-sectional view of the electrostatic precipitator during cleaning of the dust-collecting electrode plate according to the third embodiment of the present invention.

10 is a cross-sectional view taken along the line EE of FIG.

11 is a vertical cross-sectional view (equivalent to FIG. 9) of the electrostatic precipitator showing another embodiment of the outlet shutter in FIG. 9.

FIG. 12 is a vertical cross-sectional view of an electrostatic precipitator during cleaning of a dust collector plate showing another embodiment of the third invention.

[Explanation of symbols]

1 ... Flow path, 2 ... Electrostatic precipitator, 3A ... Electrostatic precipitator, 3B ... Electrostatic precipitator, 4 ... Exhaust fan, 5 ... Bag filter, 6 ... Dust recovery device, 10a-10d ... Electrostatic precipitator unit , 11 ... charged part, 12 ... dust collecting part, 15 ...
Casing, 20a to 20d ... Rear shutter, 23 ...
Opening / closing operation device, 24 ... entrance shutter, 28 ... space part, 2
9 ... Dust discharge duct, 29a ... Opening, 31a to 31
d ... air blow pipe, 32 ... fumarole, 40 ... electrostatic precipitator, 41A ... electrostatic precipitator, 41B ... electrostatic precipitator, 4
2a to 42d ... Front shutter, 50 ... Electrostatic precipitator, 51A ... Electrostatic precipitator, 51B ... Electrostatic precipitator, 5
2 ... Exit shutter, 60 ... Electrostatic precipitator, 70 ... Electrostatic precipitator, G ... Dust-containing air.

Claims (4)

[Claims] 1. An electrostatic precipitating unit having a charging section and a dust collecting section is vertically stacked in layers in a casing with a partition plate interposed therebetween, and each of the electrostatic precipitators is provided at an outlet of the casing. A rear shutter that is controlled to be opened and closed for each dust unit is provided, and an inlet shutter for blocking the dust-containing air flow is provided at the inlet of the casing with a space between the dust collecting unit and the dust collecting unit. An air blower tube is provided on the outflow side of the dust collecting portion for blowing away the collected dust, which has a gas outlet facing the dust collecting portion and is supplied with pressurized air for each of the electric dust collecting units. A plurality of electric dust collectors, each of which has a dust discharge duct for discharging an air flow containing dust removed and which is opened at the bottom of the space, are arranged in parallel in a flow passage through which dust-containing air flows, and the dust Connect the exhaust duct to the exhaust fan and dust. An electrostatic precipitator characterized by being connected to a dust recovery device equipped with a separation filter. 2. An electric dust collecting unit having a charging portion and a dust collecting portion is vertically stacked in a casing in a plurality of layers via partition plates, and each of the electric dust collecting units is provided on an inflow side of the electric dust collecting unit. A front shutter that is controlled to open and close for each dust collecting unit is provided, and an entrance shutter for blocking the dust-containing air flow is provided at the entrance of the casing.
A space is provided between the dust collecting portion and the dust collecting portion, which has an air outlet facing the dust collecting portion on the outflow side and is supplied with pressurized air for each of the electrostatic dust collecting units. A flow through which dust-containing air circulates in an electric dust collector that is provided with an air blower pipe for dropping and has a dust discharge duct for discharging an air flow containing dust that has been blown off at the bottom of the space. An electrostatic precipitator in which a plurality of dust collecting ducts are arranged in parallel in a passage and the dust discharging duct is connected to a dust collecting device having an exhaust fan and a dust separating filter. 3. An electrostatic precipitating unit having a charging section and a dust collecting section is vertically stacked in a plurality of layers in a casing via partition plates, and the electrostatic precipitator is provided at an outlet section of the casing. An outlet shutter is provided with a space between it and the unit, and an inflow side of the charging section has a fumarole facing the dust collecting section through the charging section and pressurizing for each of the electrostatic dust collecting units. An electrostatic precipitator which is provided with an air blower tube for blowing away the collected dust to which air is supplied, and which has a dust discharge duct for discharging an air flow containing the dust which is blown off at the bottom of the space. A plurality of the above are installed side by side in a flow passage through which dust-containing gas flows, and the dust discharge duct is connected to a dust recovery device having an exhaust fan and a dust separation filter. 4. A rear shutter, which is controlled to open and close for each of the dust collecting units, is provided on the outflow side of the dust collecting unit of the dust collecting unit, and a space is formed between the rear shutter and the outlet shutter. The electrostatic precipitator according to claim 3.