JPH10202143A - Electric dust collector for tunnel - Google Patents

Abstract

(57) [Summary] A plurality of dust collection units receiving power in parallel from a high-voltage generation power supply device are provided. The current supply circuit is improved so that the discharge current flowing from the unit is limited, and the deterioration of the discharge wire and the re-scattering of the collected dust due to the spark can be effectively suppressed. A plurality of sets of dust collecting units each including a charging unit and a dust collecting unit arranged in a row in front and rear are arranged in a main body frame, and power is supplied between a high-voltage generating power supply device and each set of dust collecting units. In a tunnel electric precipitator that feeds power by wiring feeders 9, 10 and branch lines 9a, 10a, a resistor 1 is connected to a branch line of the feeder for each unit.
1 to limit the discharge current (discharge current of the electric charge stored in the floating capacitance of the unit) that flows from another unit through the branch line when a spark discharge occurs in some units. Prevention of adverse effects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric dust collector for a tunnel which is installed in a side tunnel of a roadway tunnel to purify air in the tunnel.

[0002]

2. Description of the Related Art In a road tunnel with a long tunnel distance,
The air pollution caused by automobile exhaust gas, soot, airborne dust, etc. reduces the visibility (line of sight) inside the tunnel. To improve this, electric dust collection equipment is installed in the ventilation side shaft provided in the tunnel. After cleaning the contaminated air taken in from the tunnel road (main shaft) through an electric precipitator, the clean air is blown back into the roadway space by a blower to improve the visibility inside the tunnel. ing.

FIG. 2 is a schematic diagram showing the configuration of such an electric dust collector for a tunnel. In the figure, reference numeral 1 denotes a side tunnel for ventilation of a tunnel, and 2 denotes an electric precipitator installed in the side tunnel. A plurality of dust collecting units 6 each including a charging unit 4 and a dust collecting unit 5 (in consideration of handling in a tunnel, a small dust collecting unit usually divided into 4 to 12 units is arranged vertically and horizontally. And the water washing nozzle 7 and the like are housed. Reference numeral 8 denotes a high-voltage power supply unit separately provided from the main body of the dust collector. As shown in FIG. 3, power supply feeders (cables) 9, 10 on the output side drawn from the power supply unit 8 and branched from each feeder. DC high voltage is applied to the charging unit 4 and the dust collecting unit 5 of each unit (denoted by I to IV) via the branch lines 9a and 10a. As is well known, the high-voltage generating power supply 8 for the electric precipitator basically has a configuration in which a thyristor for output voltage control, a step-up transformer, and a rectifier circuit are combined to convert an AC input into a high-voltage DC. It converts and outputs the power. When spark discharge or arc discharge occurs on the dust collection unit side and a sparkover occurs, a control means for lowering the power supply voltage or stopping the power supply so as to suppress the sparkover is provided. .

FIG. 4 schematically shows the structure of a charging unit 4 and a dust collecting unit 5 of a dust collecting unit 6 (for one unit) employed in an electric dust collector for tunnels. That is, the charging section 4 is formed by alternately arranging discharge wires (thin steel wires of 0.26 mmφ) 4a and ground electrode plates 4b at intervals of about 5 to 6 mm, and about 300 discharge wires 4a per unit are provided. It is stretched. The dust collecting portion 5 has a configuration in which a plate-like high voltage electrode plate 5a and a ground electrode plate 5b made of a thin steel plate having a thickness of about 0.5 mm are alternately arranged at intervals of about 5 to 6 mm.

In the charging section 4, a positive high voltage (11 kV DC) is applied to the discharge line 4a to generate a positive corona around the discharge line, and in the dust collecting section 5, a positive high voltage (DC) is applied to the high voltage electrode plate 5a. DC 5.5 kV) is applied to form an electric field having a high electric field intensity between the electrode plates 5a and 5b, and suspended particles such as soot and dust contained in the air to be treated introduced into the electric precipitator 2 are removed from the pre-stage. Is charged positively by the charging section 4, and the suspended particles are collected on the ground electrode plate 5b by electrostatic coulomb force in the dust collecting section 5 at the subsequent stage.
The dust collected in the dust collecting section 5 is temporarily stopped temporarily in a dust collecting operation, and is washed out from the dust collecting electrode plate by spraying washing water to be removed.

[0006] The current standard specification of the electric precipitator for a roadway tunnel (Japan Highway Public Corporation) has a processing wind speed of 7 m / se.
c, The processing air volume per unit is specified to be 3.75 m ³ / sec, and the dust collection efficiency is specified to be 80% or more.

[0007]

The nature of the air to be treated by the above-mentioned electric precipitator for tunnels depends on the humidity in the tunnel,
It fluctuates every day depending on smoke and dust concentration. Also,
In the dust collection section, the amount of collected dust gradually increases with the elapse of time in the dust collection operation. For this reason, the spark discharge starting voltage between the electrodes of the charging unit and the dust collecting unit also changes, and spark discharge and arc discharge occur during the dust collecting operation, resulting in spark over. In order to increase the dust collection efficiency, the electric dust collector is operated at a high voltage within a range that allows a certain amount of spark discharge. In this case, in order to prevent the spark discharge from shifting to arc discharge, the high-voltage generating power supply detects the occurrence of arc discharge by current and voltage, and temporarily reduces the output voltage by thyristor control to reduce arc discharge. , And control means for restoring the voltage to a normal voltage thereafter. Further, a high-frequency reactor for preventing a surge voltage caused by the occurrence of spark discharge from entering the power supply side, and a current limiting resistor for suppressing a discharge current at the time of ozone spark over are also connected to an output terminal side of the power supply device.

By the way, according to the knowledge obtained from the long-term actual operation results of the electric precipitator for tunnels, in the conventional power supply system shown in FIG. 3, the protection function of the high-voltage generating power supply device at the time of sparkover occurs. Despite normal operation, an unexpectedly large discharge current flows through the dust collection unit where sparkover has occurred. In the dust area, the dust collected on the electrode plate re-scatters in the vicinity of the spark discharge together with the explosive impact noise, which blows out of the electric dust collector and contaminates the downstream tunnel wall, It has been observed that the dust concentration of the air returning to the main tunnel of the tunnel may temporarily increase.

The inventors of the present invention have investigated the causes of the above phenomena and found that the causes are as follows. That is, the charging portion and the dust collecting portion of the electric dust collector function as a capacitor, and the floating capacitance of the dust collecting portion having a large electrode plate area is particularly large. In the dust collection unit of the standard specification described above, the electrostatic capacity of the charging unit is 0.002μ.
F, the electrostatic capacitance of the dust collection part is 0.3 μF. Moreover, FIG.
In the conventional power supply system shown in (1), the charging unit 4 and the dust collecting unit 5 of each unit are directly conductively connected to each other via branch lines 9a and 10a branched from the power supply feeders 9 and 10.

On the other hand, during a normal dust collection operation, the charging unit 4 and the dust collection unit 5 of each dust collection unit are charged with a high voltage, and electric charges are stored between the electrodes. For this reason, when a short-circuit occurs due to a sparkover occurring in a charging portion or a dust collecting portion (for example, the dust collecting portion 5 of the unit IV in FIG. 3) in a part of the dust collecting unit, the control operation of the high voltage generating power supply 8 is performed. Although the power supply voltage to the dust collecting unit is reduced by the above operation, the electric charge stored between the electrodes of the other dust collecting units is used as the discharge current i as branch currents 9a and 10b.
The liquid flows around the unit where the spark over has occurred through a and flows intensively to the location where the spark discharge occurs, and impulsive discharge energy is applied to the portion.

In addition, the current flowing from another dust collecting unit to the dust collecting unit in which the spark over has occurred via the branch lines 9a and 10a is limited as long as it is built in the output end side of the high voltage power supply 8 as described above. Since the current resistance cannot be limited by the current resistance and the wiring resistance of the branch lines 9a and 10a themselves is extremely small, the time constant (CR) of the discharge circuit is also small, so that an excessive current flows sharply. As a result, in the charging section 4 where the spark over has occurred, the temperature of the spark-discharged discharge wire 4a sharply rises, and the thermal stress causes the service life to be shortened and a disconnection accident to occur. Further, in the dust collecting portion 5, due to the impact caused by the spark discharge, the dust collected on the electrode plates 5a and 5b re-scatters together with a large explosion sound and radio noise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to solve the above-mentioned problems. When a sparkover occurs,
A power supply circuit for a tunnel with an improved power supply circuit so as to limit the discharge current intensively diverted from another unit to the unit and effectively suppress the reduction in the life of the discharge line due to sparkover and the re-scattering of collected dust. To provide a dust machine.

[0013]

According to the present invention, in order to achieve the above object, a resistor is individually connected to a branch line of the power supply feeder for each dust collecting unit, and some of the units are connected. When a sparkover occurs, a discharge current flowing from another unit via a branch line is limited.

That is, by inserting a resistor in the branch line of the power supply feeder connected to the charging unit and the dust collecting unit for each dust collecting unit, if a spark over occurs in some units, The resistor limits the current flowing from the other unit side (discharge current of the charge accumulated in the floating capacitance of the unit), and the current energy is converted into heat by the resistor and consumed. Further, the transient time constant (CR) of the circuit is increased by the connection of the resistor, so that the steepness of the current (the energy of the accumulated charge) flowing from another unit is reduced. As a result, deterioration due to a rapid rise in the temperature of the discharge wire is suppressed in the charging section, and adverse effects due to spark over, such as re-scattering of collected dust due to the impact of spark discharge, can be effectively prevented in the dust collection section. .

In addition, from the viewpoint of suppressing the power loss during the steady operation, the resistor has a resistance of 2 to 2 in practice.
It is good to set it to 5kΩ, and to protect the resistor from the surrounding environment, the one in which the resistance element is housed in a highly insulating ceramic outer cylinder is used, and when cleaning the dust collector with water,
At the same time, dust adhering to the surface of the ceramic outer cylinder is preferably cleaned.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the drawings of the embodiment, the same members corresponding to FIG. 3 are denoted by the same reference numerals. That is, in the illustrated embodiment, a resistor is provided for each of the branch line lines 9a and 10a of the feeder feeders 9 and 10 for applying a voltage from the high voltage generation power supply device 8 to the charging unit 4 and the dust collection unit 5 of each set of dust collection units. 11 are connected. Here, the resistor 11 employs a resistor element (ceramic resistor) housed in a ceramic outer cylinder such as an insulator, and has a resistance value of a dust collecting unit (standard) having a processing air volume of 3.75 m ³ / sec. (Specifications) is set to 2 to 5 kΩ.

With such a configuration, during the dust collection operation of the electric dust collector, the charging units 4 and 4 of some of the plurality of dust collection units are set.
Or, when spark discharge occurs transiently in the dust collecting section 5, the current intensively flowing from another dust collecting unit to the unit that has sparked over through the branch lines 9a and 10a of the power feeder is limited by the resistor 11, and , The transient time constant (C
Since R) increases, the steepness of the current (energy of accumulated charge) flowing from another unit to the unit where spark discharge occurs is reduced. By setting the resistance value of the resistor 11 to several kilohms as described above, the power loss consumed by the resistor during steady operation can be almost ignored at 1% or less of the supplied power. Further, the heat generated by the resistor 11 is dissipated to the surroundings through the ceramic outer cylinder having high heat conductivity.

As a result, problems such as deterioration of the discharge wire, disconnection accident, impulsive discharge impact noise, and re-scattering of collected dust due to an instantaneous rise in temperature due to the flow of a steep spark discharge current. Effectively suppressed. Note that resistor 1
1 is contaminated with dust (e.g., carbon black) during the dust collection operation. Therefore, when the collected dust of the dust collector body is washed with water, the water injection nozzle 7 is also used. (See FIG. 2).

[0019]

As described above, according to the present invention, the dust collector body composed of a plurality of dust collection units is wired between each dust collection unit and the high voltage generation power supply unit. Connect a resistor to the branch line of the feeder,
When a sparkover occurs in some units, the discharge current (discharge current of the charge stored in the floating capacitance of the unit) that flows from another unit via the branch line is limited. In the charging section, the deterioration caused by the rapid rise in the temperature of the discharge wire is suppressed, and in the dust collection section, adverse effects such as re-scattering of trapped dust due to the impact of spark discharge are effectively prevented, and the electricity collection for tunnels is prevented. The performance and reliability of the dust machine can be improved.

[Brief description of the drawings]

FIG. 1 is a power supply circuit diagram of an electric precipitator for a tunnel according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of the entire structure of an electric dust collector for a tunnel.

FIG. 3 is a power supply circuit diagram of a conventional electric precipitator for a tunnel.

FIG. 4 is a diagram schematically showing the internal structure of the dust collection unit in FIG.

[Explanation of symbols]

 Reference Signs List 4 Charging unit 5 Dust collecting unit 8 High voltage generating power supply 9,10 Feeding feeder 9a, 10a Branch line 11 Resistor

Claims (3)

[Claims] 1. An electric dust collector for a tunnel which is installed in a tunnel and purifies air taken in from the main road space, and includes a plurality of sets of a dust collecting unit including a charging unit and a dust collecting unit arranged in a row in front and rear. Are arranged side by side in the body frame, and between the high-voltage generating power supply and the charging unit and dust collection unit of each set of dust collection units, the power supply feeder drawn from the power supply unit is connected to the discharge wire of the charging unit and the dust collection unit. In the branch connection to the electrode plate, for each dust collection unit, a resistor is individually connected to the branch line of the power supply feeder, and when a spark over occurs in some units, the branch line from another unit is disconnected. An electric precipitator for a tunnel, wherein a discharge current flowing around via a current is limited. 2. The electric dust collector according to claim 1, wherein the resistance value of the resistor is set to 2 to 5 kΩ. 3. An electric dust collector for a tunnel according to claim 1, wherein the resistor has a resistance element housed in a ceramic outer cylinder.