JPS6352540B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for collecting dust in an electrostatic precipitator applied to cleaning ventilation equipment for air inside a tunnel, for example, where the air inside an automobile road tunnel is used as the gas to be treated. Regarding the cleaning method.

[Prior art and its problems]

The air inside the tunnels of the abovementioned motorways is contaminated with many submicron-sized suspended particles such as smoke emitted from automobiles, dust generated by the wear of tires and road asphalt generated as automobiles run. As a method to clean and ventilate the contaminated air inside the tunnel, ventilation equipment using an electrostatic precipitator is installed in the detour tunnel in the tunnel leading to the roadway, and the contaminated air extracted from the roadway is passed through the electrostatic precipitator. A system has been developed that cleans the air and sends it back to the roadway.

Next, an overview of this dust collection equipment equipped with an electrostatic precipitator will be described with reference to FIG. In the figure, 1 is the detour tunnel that leads to the road inside the tunnel mentioned above.
An electrostatic precipitator 2 and a blower 3 are installed in the tunnel on the downstream side thereof. The electrostatic precipitator 2 is equipped with opening/closing dampers 5 and 6 on the inlet and outlet sides of the casing 4, respectively, and a charging unit 8 and a dust collection unit 9 that receive power from a high-voltage power supply 7 are housed inside the casing. . As a result, during operation, the contaminated air A is sucked into the electrostatic precipitator 2 from the upstream side by the blower 3, and as it passes through the inside of the machine, suspended particles contained in the contaminated air A collect as dust. Air collected and purified on the dust collecting electrode of the dust unit 9
A' is sent downstream through the blower 3.
In order to separate and recover the dust collected on the dust collection electrode, an air blow nozzle 10 is installed behind the dust collection unit 9 as a dust cleaning mechanism for blowing off dust toward the interlayer gap of the dust collection electrode.
are arranged in multiple stages, and this air blow nozzle 1
Air blow line 1 including compressor 11 at 0
2 is connected and piped. On the other hand, there is a dust discharge plenum 13 at the bottom of the dust collector casing.
A dust collection line 16 including a dust separation and collection device 14 such as a bag filter or a cyclone and a suction fan 15 is connected to this plenum 13 . In addition, the reference numeral 17 in the figure is an opening/closing drive unit for the dampers 5 and 6, 18 is the main valve of the air blow line 12, and 19 is an opening/closing damper provided on the outlet side of the dust discharge plenum 13.

Next, the conventional dust removal and dust collection operations with the above configuration will be explained with reference to FIGS. 2 and 3. First, during dust collection operation, the compressor 11 of the air blow line 12 and the suction fan 15 of the dust collection line 16 are both stopped as shown in FIG. 2, and in this state, the electrostatic precipitator 2 opens the dampers 5 and 6. Further, it receives power from the power supply device 7 to collect dust from the gas to be treated. When this dust collection operation continues for a certain period and a considerable amount of dust is collected and accumulated on the dust collection electrode, the next step is to remove the dust attached to the dust collection electrode based on the dust cleaning command. It will be brushed off and collected outside the aircraft. Such dust cleaning is carried out under the condition that the power supply to the blower 3 and the high-voltage power supply 7 shown in FIG. 1 is stopped, and the compressor 1 is
1 and suction fan 15, and dampers 5 and 6 on the inlet and outlet sides of the dust collector casing.
is closed, and the main valve 18 of the air blow line and the opening/closing damper 19 of the dust discharge plenum are opened to perform air blow and suction to the dust collection line at the same time, thereby starting the dust blowing and collection operation. That is, in this state, air blow nozzle 1
From 0, gas is supplied under pressure through the air blow line 12 and is ejected at a wind speed close to the speed of sound toward the gap between the layers of the dust collection electrodes that make up the dust collection unit 9, removing the dust that has adhered to the electrodes. brush off. Here, the dust collected on the dust collection electrode is aggregated and coarsened, and the coarse particle dust brushed off from the electrode is ejected into the casing from the air blow nozzle 10 and sent to the dust collection line by the suction fan 15. The airflow sucked toward the dust is dispersed into the transport airflow B as a transport airflow, and is carried out through the dust discharge plenum 13 to the dust recovery line 16 outside the machine. Furthermore, the dust riding on the carrier airflow enters the dust separation and recovery device 14, where it is separated from the carrier airflow, and only the airflow is exhausted to the upstream side of the electrostatic precipitator 2 through the suction fan 15, for example. On the other hand, the dust separated and collected from the conveying airflow is appropriately repacked into bags, etc., and then transported to a processing plant where it is disposed of.

When performing such dust cleaning, care must be taken to prevent the collected dust that has been blown off from the dust collection unit 9 by the start of air blowing from blowing out through the gap between the opening and closing dampers 5 and 6 of the casing and being scattered again. It is desired that the dust be smoothly sucked and carried out to the dust recovery line 16. However, in this case, in the conventional method of simultaneously starting the air blow operation and starting the suction fan 15 of the dust collection line based on the dust cleaning command as described above, since the internal volume of the casing 1 is large, the suction fan 15 is started. Immediately after, it takes some time for the dust transporting airflow B to be sufficiently generated and established to be sucked from inside the casing 1 through the discharge plenum 13 to the dust collection line 16, and during this time, the dust is blown off from the dust collection unit by the air blow. The dust may be scattered inside the casing, and the dynamic pressure of the air blow stream may be added to this, causing the dust to be blown out of the casing 1 through the gap between the opening/closing dampers 5 and 6.

[Purpose of the invention]

This invention was made in consideration of the above points, and when performing air blow type dust cleaning,
To provide a dust cleaning method which can smoothly suction and carry out dust brushed off from a dust collection unit immediately after starting air blowing to a dust collection line without blowing it out and scattering it outside a casing.

[Key points of the invention]

In order to achieve the above object, the present invention first cuts off the power supply to the dust collecting section during dust cleaning, then closes the opening/closing dampers on the inlet and outlet sides of the electrostatic precipitator, and starts the suction fan in the dust collection line. By starting air blowing to the dust collecting section after generating and establishing a suction conveying airflow from inside the casing toward the dust collection line, the dust that has been blown away from the dust collection section can easily ride on the suction conveying airflow and be collected. This allows for smooth suction and conveyance to the line.

[Embodiments of the invention]

Next, embodiments of this invention will be described. In FIG. 2, reference numeral 20 denotes an operation control device, which outputs control signals to various parts as indicated by dotted lines in response to an operation mode command 21 given here. In other words, if the operation mode command is dust collection operation, the power supply circuit of the high voltage power supply 7 is turned on and the opening/closing dampers 5 and 6 are turned on as shown in the figure.
is opened, the compressor 11 and the suction fan 15 are turned off, and the dust collection process for the gas A to be processed is performed. When a predetermined period of time elapses from this state, for example, by integrating the dust collection operation time, the command 21 switches from the dust collection operation to dust cleaning, and the dust cleaning is performed according to the following procedure. In other words, this switching operation is shown in a time chart as shown in Figure 4, and when a dust cleaning command is given, the high voltage power supply 7 is first
The power supply is cut off, and at the same time, the air blow compressor 11 and suction fan 15 are started. Note that at this point, the main valve 18 of the air blow line 12 and the suction damper 19 communicating with the dust collection line 16 are closed, and substantially no air blowing or suction operation is performed. Next, when the opening/closing dampers 5 and 6 of the casing 1 are closed, the suction damper 19
opens and starts suctioning the air inside the casing toward the dust collection line 16. After that, a predetermined time t
After a delay, the main valve 18 of the air blow line 12 is opened to start air blowing. By delaying the start of the air blow from the start of the suction operation of the dust recovery line, a suction conveyance airflow flowing from inside the casing toward the dust recovery line 16 is sufficiently generated and established during this delay time. Therefore, when the dust collected in the dust collection unit 9 is blown off by the start of air blowing, this dust is immediately dispersed into the conveying airflow B described in Fig. 3, which has already been generated inside the casing. , the dust collection line 16 smoothly passes through the discharge plenum 13.
It began to be transported to In this way, dust is prevented from blowing out from the casing 1 through the gap between the opening and closing dampers 5 and 6. On the other hand, the air blow ends in a relatively short time, and the suction fan 15
is continuously operated to suction and carry out the residual dust in the casing, and when a predetermined period of time has elapsed, the dust cleaning mode is switched again to the regular dust collection operation mode. As shown in Figure 4, by starting the high-voltage power supply before restarting the dust collection operation,
Effectively helps prevent dust from scattering again within the dust collection unit.

In addition, in the operation order of the above-mentioned embodiment, the order of closing the opening/closing dampers 5 and 6 and starting suction of air inside the casing may be changed, and then air blowing may be started. However, the opening/closing damper 5,
When considering the closing operation of dampers 5 and 6, it is advantageous to close the dampers 5 and 6 in a state where no airflow is flowing because there is less resistance associated with the closing operation and less operating power is required.

〔Effect of the invention〕

As described above, according to the present invention, when cleaning dust, the power supply to the electrostatic precipitator is cut off, the opening/closing dampers on the inlet and outlet sides of the casing are closed, and the suction fan of the dust collection line is started to collect dust into the casing. By controlling the operation to start air blowing to the dust collection section through the dust cleaning mechanism after generating and establishing the suction conveying airflow toward the line, the collected dust that is blown off from the dust collection section by the air blow is immediately removed from the dust collection section. The dust is dispersed in the suction conveying airflow toward the collection line and smoothly transported to the dust collection line, and the phenomenon in which the dust that is brushed off immediately after the start of air blowing is blown outward from the gap in the casing can be effectively prevented.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the entire electrostatic precipitator to which this invention is applied, Figs. 2 and 3 are explanatory diagrams of the operation of the precipitator showing the dust collection operation and dust cleaning state, respectively. 3 is a time chart showing operation control according to an embodiment of the present invention. 2: Electrostatic precipitator, 4: Casing, 5, 6:
Opening/closing damper, 7: High voltage power supply, 8: Charging unit, 10: Air blow nozzle of air blow type dust cleaning mechanism, 12: Air blow line, 14: Dust separation and recovery device, 15: Suction fan, 16: Dust collection line, 20: Operation control device.

Claims (1)

[Claims] 1. An electrostatic precipitator is equipped with opening/closing dampers on the inlet and outlet sides of the casing, and is equipped with an air blow type dust cleaning mechanism for blowing off the collected dust opposite the dust collection section inside the machine, and the dust cleaning mechanism is equipped with An air blow line including an air pressure feeding means is connected to the casing, and a dust collection line including a dust separation and recovery device and a suction fan is connected to the casing, and the dust collection line including a dust separation and recovery device is connected to the internal space of the casing, and when cleaning dust, first cut off the power supply to the dust collection section. In addition, close the opening/closing dampers on the casing inlet and outlet sides, start the suction fan in the dust collection line to generate and establish a suction conveying airflow inside the casing, and then start blowing air from the air blow line to the dust collection section through the dust cleaning mechanism. A collected dust cleaning method for an electrostatic precipitator is characterized in that the collected dust in the dust collecting section is blown off by air blowing, dispersed in a suction conveying air stream, and then transported to a dust collection line and collected.