JPH08108093A - Electrostatic precipitator controller and method for operating and starting the precipitator - Google Patents

Abstract

PURPOSE: To start an electrostatic precipitator at the time of collecting dust in gas by increasing the voltage between electrodes to a high voltage suitable to dust collection in a short time without generating a spark discharge. CONSTITUTION: In starting an electrostatic precipitator, etc., a changeover switch 73 is turned to a discrete contact 75 by a control circuit 74 in response to the external command, e.g. 'ON', to increase the voltage impressed between electrodes from a second voltage Vh as the previously impressed low voltage to a first voltage Vb as the high voltage suitable to dust collection, and the precipitator is ready to dust collection. Further, when the precipitator is suspended or the like, the changeover switch 73 is turned to a discrete contact 76 in response to the external command, e.g. 'OFF', to impress the second voltage Vh between the electrodes, hence the Joule heat due to the leakage current is generated in the electrode to dry the dust depositing on the surface, and the electrode surface is dehumidified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electrostatic precipitator which is preferably implemented for collecting and removing dust in the air in a tunnel and a method for starting and operating the electrostatic precipitator.

[0002]

2. Description of the Related Art In order to wash an electrostatic precipitator used for collecting and removing dust contained in air in a tunnel, a pressurized water is sprayed, whereby electrodes and electrodes of the electrostatic precipitator are sprayed. The dust collected on the insulators and the like held is removed, and thus the tunnel dust is continuously collected. If the electrodes are not sufficiently dried after washing with water, or if dust existing on the surface of the insulator and electrodes is absorbed while the electrostatic precipitator is stopped at night, remove the dust collector. When a high voltage is applied between the electrodes for activation, spark discharge occurs, which causes a short circuit, which may prevent activation. Therefore, in the prior art, as shown in FIG. 14, a low voltage of less than 11 kV, which is a voltage during steady operation of the electrostatic precipitator, is applied to the electrodes for a predetermined time, and the dust adhering to the electrodes and the insulators leaks from the electrodes. After being dried by Joule heat due to electric current to increase the insulation resistance, the voltage is increased stepwise and a high voltage for steady operation is applied.

In such a prior art, the state of the insulator and the electrode at the time of starting the electrostatic precipitator is different each time, and the state of air such as temperature, humidity and dust concentration is changed, and accordingly, the state is changed. The time when the low voltage for drying the dust must be applied so that the hygroscopic state and the adhering state of the dust change, and thus the above-mentioned short circuit does not occur, is different each time. Nevertheless, in the prior art, the time for applying the low voltage is set to a constant time, which can prevent a short circuit or the like even when the dust adhering to the insulator and electrodes is in a poor moisture absorption state. ing. Therefore, in the prior art, there is a problem that the time for applying the low voltage between the electrodes is unnecessarily long, and therefore it takes time to return to the steady operation. On the contrary, if the time is shortened and the normal operation is quickly restored, the dust may not be completely dried and the short circuit may occur. Japanese Patent Publication No. 2-106 is mentioned as a prior art which applies a low voltage at the time of starting.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to increase the voltage between electrodes at the time of start-up to a high voltage during steady operation in as short a time as possible without causing a short circuit due to spark discharge or the like. A control device for an electrostatic precipitator and a method for starting operation of the electrostatic precipitator are provided.

[0005]

SUMMARY OF THE INVENTION The present invention is a controller for an electrostatic precipitator in which a gas containing dust is passed between electrodes to which a voltage is applied from a voltage generating means. A first voltage is generated, and a predetermined second voltage that is less than the first voltage during the dust collection stop operation and that can be dehumidified by heat generated by the leakage current of the electrode is generated by the voltage generating means. A control device for an electrostatic precipitator, which is provided with a voltage switching means. Further, the present invention is a method for starting up the operation of an electrostatic precipitator in which a gas containing dust is passed between electrodes to which a voltage is applied from a voltage generating means, in a dust collection pause operation, at a voltage lower than the applied voltage during the dust collection operation. And a second voltage that can be dehumidified by the heat generated by the leakage current of the electrodes is kept applied between the electrodes, and the voltage for dust collection rises with the passage of time during the dust collection operation. Is a method for starting the operation of the electrostatic precipitator.

[0006]

In the electrostatic precipitator, a voltage is applied between the electrodes through which a gas containing dust, such as air, causes a corona discharge to charge the dust particles, and the charged dust particles are moved to the electrodes by electrostatic force. Dust collection is performed. The dust collection efficiency is generally better as the corona discharge current is larger. The corona discharge current becomes larger as the applied voltage between the electrodes becomes higher, and when it becomes higher, it shifts to the form of spark discharge. The corona discharge current increases as the temperature of the gas flowing between the electrodes increases, even if the voltage applied between the electrodes is the same.

The control device for the electrostatic precipitator generates a predetermined first voltage by the voltage generating means during the dust collecting operation, and is less than the first voltage during the dust collecting pause operation.
Further, there is provided voltage switching means for causing the voltage generating means to generate a predetermined second voltage capable of dehumidifying the electrodes by heat generation due to the leakage current of the electrodes.

According to the invention, the operation start-up method of the electrostatic precipitator is such that the second voltage is kept applied between the electrodes during the dust-collection pause operation, and the dust collection operation is performed during the dust-collection operation. This is a method of increasing the first voltage with time. As a result, Joule heat is generated by constantly applying a low voltage to the electrodes, and the dust adhering to the electrodes is always dried to dehumidify the electrode surface.

[0009]

1 is a block diagram showing a part of the configuration of a control device for an electrostatic precipitator according to an embodiment of the present invention. This electrostatic precipitator is arranged as shown by reference numeral 3 in an electrostatic precipitator tunnel 2 communicating with the side wall of the roadway tunnel 1 as shown in FIG. A blower 17 and a control device 10 are provided in the dust collector tunnel 2.
As a result, polluted air containing dust in the roadway tunnel 1 is bypassed to the tunnel 2 to form a longitudinal flow ventilation system. Thus, the purified air from which dust in the air is removed is blown into the space of the road tunnel 1. This can improve the line-of-sight distance in the road tunnel 1.

As shown in the plan view of FIG. 3, the electrostatic precipitator 3 includes a charging section 4 and a dust collecting section 5. FIG. 4 is a front view of the charging unit 4. A plurality of electrodes 7, which are discharge lines, are arranged between a plurality of flat plate-shaped electrodes 6 arranged at intervals. The plate-shaped electrode 6 is grounded via the line 8.
The electrode 7, which is a discharge line, is connected to the line 9, and a positive voltage is applied and supplied from the control device 10. The discharge current flowing between the electrodes 6 and 7 is detected by the ammeter 11, and the voltage between the electrodes 6 and 7 is detected by the voltmeter 12.

A dust collecting section 5 is arranged downstream of the charging section 4. As shown in FIG. 5, the front surface of the dust collecting portion 5 is arranged alternately with the plurality of flat plate-shaped electrodes 13 and 14 facing each other. One electrode 13 is grounded via a line 15. The other electrode 14 is connected to the control device 10 via a line 16 and is given a positive voltage. In this way, the dust-containing air flows between the electrodes 6 and 7 of the charging unit 4, and the dust is charged by corona discharge, and the charged dust is electrostatically applied to the electrodes 13 and 14 of the dust collecting unit 5. It is attached and collected. The electrodes 6, 7; 13 and 14 are washed with water by jetting pressurized water at regular intervals to collect dust and remove it.

The leak current flowing between the electrodes 13 and 14 is detected by the ammeter 19, and the voltage between the electrodes 13 and 14 is detected by the voltmeter 20. The temperature of the air flowing through the dust collector tunnel 2 is detected by the temperature detecting means 21.

FIG. 6 is a block diagram showing the overall configuration of the control device 10 for the electrostatic precipitator 3. For the charging unit 4 of the electrostatic precipitator 3, the charging unit control circuit 22 and the spark control circuit 2
3 and a DC voltage generating circuit 24 are provided. Similarly, for the dust collecting portion 5, a dust collecting portion control circuit 22a, a spark control circuit 23a, and a DC voltage generating circuit 24a are provided. The output of the temperature detecting means 21 is given to the charging section control circuit 22. The output of the ammeter 11 of the charging unit 4 is supplied to the charging unit control circuit 22 and the spark control circuit 23 via the line 25. The output of the voltmeter 12 of the charging unit 4 is given to the charging unit control circuit 22. Similarly, the output of the ammeter 19 in the dust collecting unit 5 is given to the dust collecting unit control circuit 22a and the spark control circuit 23a via the line 25a. Voltmeter 20 of dust collector 5
Is supplied to the dust collector control circuit 22a. The respective constituent elements 23 a and 24 a related to the dust collecting section 5 have the same configurations as the respective constituent elements 23 and 24 for the charging section 4.

Referring again to FIG. 1, in the charging section control circuit 22 for the charging section 4 of the electrostatic precipitator 3, the calculating means 27 has a signal representing the temperature Tp of the air detected by the temperature detecting means 21. From the voltage Vp between the electrodes 6 and 7 detected by the voltmeter 12 and the filter 28
The output through is given. The filter 28 is a voltmeter 1
2 serves to eliminate undesired fluctuations in output. The calculating means 27 is provided with the characteristics of the applied voltage between the electrodes 6 and 7 and the maximum allowable discharge current I1 shown in FIG. 7 with the detected temperature Tp of air as a parameter, as a memory table. The maximum allowable discharge current I1 increases as the applied voltage increases, and the discharge current I1 increases as the air temperature Tp increases even if the applied voltage is constant. Compared to the characteristic of the line 29 in FIG. 7, the characteristic of the line 30 is that the air temperature T
This is the characteristic when p is high. The maximum allowable discharge current I1 is
Corona discharge is generated between the electrodes 6 and 7 of the charging unit 4, and is the maximum current at which spark discharge does not occur.

The output of the calculation means 27 is given to the subtraction circuit 31. In the subtraction circuit 31, the discharge current Ip between the electrodes 6 and 7 detected by the ammeter 11 is filtered by the filter 32.
The undesired fluctuation is eliminated by and is given to the subtraction circuit 31. The subtraction circuit 31 subtracts the detection current Ip detected by the ammeter 11 from the maximum allowable discharge current I1 obtained by the calculation means 27 to obtain the difference Eg.

Eg = I1−Ip (1) The determination circuit 33 responds to the output Eg of the subtraction circuit 31, and if Eg> 0 (2), applies it between the electrodes 6 and 7 at the time of startup. A signal representing a predetermined time change rate Kg of the power voltage V is output.

[0017]

[Equation 1]

If Eg ≤ 0 (4), the time change rate of the voltage V to be applied between the electrodes 6 and 7 at the time of starting is set to zero as shown in the equation (5), and the applied voltage V is Hold.

[0019]

[Equation 2]

Thus, when the maximum permissible discharge current I1 exceeds the detection current Ip, that is, when the detection current Ip is less than the maximum permissible discharge current I1, a signal representing the applied voltage that rises at the time rate of change Kg is derived, and is also permissible. When the maximum discharge current I1 is less than or equal to the detection current Ip, that is, the detection current I
When p is greater than or equal to the maximum allowable discharge current I1, the applied voltage is maintained as it is. The time change rate Kg can be manually adjusted and set by the time change rate measuring means 34.

The subtraction circuit 31 may have only the function of comparing and detecting the magnitude relationship between the currents I1 and Ip.

The output of the judgment circuit 33 is given to the starting voltage control signal generating means 35, and a voltage control signal representing the applied voltage Vs applied between the electrodes 6 and 7 is led to the line 78. FIG. 8 is a diagram showing a time course of the applied voltage Vs represented by the voltage control signal derived from the starting voltage control signal generation means 35. From the second voltage Vh applied between the electrodes 6 and 7 in advance from the dust collection pause operation, the applied voltage is increased at the time change rate represented by the above formula (3), and then the time change rate is calculated by the formula ( It is set to zero as shown in 5). By such an operation, the applied voltage between the electrodes 6 and 7 rises with time. The time change rate Kg is, for example, 200 V / se.
It may be c.

One individual contact 75 of the changeover switch 73
The common contact 74 is configured to be operated by the switching control circuit 77 on the other individual contact 76. A signal representing the applied voltage Vs applied between the electrodes 6 and 7 from the starting voltage control signal generating means 35 is applied to the individual contact 75, and the second voltage Vh from the second voltage setting means 72 is applied to the individual contact 76. A signal to represent is given. The second voltage Vh is lower than a first voltage Vb described later, and is a voltage that does not cause corona discharge. In addition, the second voltage V
h can be manually adjusted and set. The changeover control circuit 77 changes over the changeover switch 73 in response to a command from the outside. The switching control circuit 77 sets the common contact 74 to the individual contact 75 when the external command is, for example, “ON”.
And the signal from the starting voltage control signal generating means 35 is conducted. Conversely, when the external command is "OFF",
The common contact 74 is switched to the individual contact 76, and the control signal representing the second voltage Vh is conducted. By the above operation,
During the dust collection pause operation, the second voltage Vh is applied between the electrodes 6 and 7.
By applying, the Joule heat due to the leakage current is generated in the electrode, and the dust and the like adhering to the electrode surface can be dried to dehumidify the electrode surface.

The applied voltage during the steady operation of the charging unit 4 of the dust collector 3 is determined as follows. Changeover switch 38
The one individual contact 39 and the other individual contact 40 are configured so that the common contact 41 is switched and operated manually, for example. The one individual contact 39 has the reference from the reference temperature setting means 42. A signal representing the temperature Tb, for example 25 ° C., is provided via line 43. The other individual contact 40 has a temperature T detected by the temperature detecting means 21.
A signal representative of p is provided for voltage control. A signal given from the reference temperature setting means 42 to the one individual contact 39 via the line 43 is used for constant current control. The output of the common contact 41 of the changeover switch 38 is given to the arithmetic means 44. A signal representing the set voltage Vb at the time of steady operation, for example, 11 kV from the voltage setting means 45 is also supplied to the calculating means 44 via a line 46.

The calculating means 44, as shown in FIG.
The table of the memory has the characteristics of the applied voltage Vb and the discharge current I2 in the charging unit 4 with the temperature of the air represented by the signal through the common contact 41 of the changeover switch 38 as a parameter. During constant current control in which the common contact 41 and the individual contact 39 of the changeover switch 38 are electrically connected to each other, the discharge current I2 set in the charging unit 4 is represented from the set reference temperature Tb and the set voltage Vb. The signal is derived and given to the subtraction circuit 48. Line 4 in Figure 9
Compared to the characteristic of 9, the characteristic of the line 50 is a characteristic when the temperature of the air containing dust in the charging unit 4 is high. Each of the characteristics of the lines 49 and 50 is less than the maximum allowable discharge current described with reference to FIG. 7 and has an approximate value. As a result, the corona discharge current can be increased to increase the amount of released ions, the dust contained in the air can be efficiently charged, and the dust collection efficiency is improved.

The subtraction circuit 48 includes an ammeter 11 for the charging section 4.
The signal representing the detection current Ip of the filter 3 is
Given through 2. The subtraction circuit 48 is the calculation means 44.
Discharge current I2 and detection current I during steady operation output from
It is obtained by subtracting the difference Eb of p.

Eb = I2-Ip (6) The correction value calculation circuit 52 calculates the product Mb of the output Eb of the subtraction circuit 48 and the coefficient Kb set by the coefficient setting circuit 53.

Mb = Kb.Eb (7) The coefficient Kb set by the coefficient setting circuit 53 is 0 to
It may be a value between 1 and a value greater than 1 and is a positive value. This coefficient Kb can be adjusted by manual operation. The output of the correction value calculation circuit 52 is given to the addition circuit 54 and added together with the set voltage Vb from the voltage setting means 45 via the line 46,
A voltage control signal representing the corrected applied voltage Vb1 in the steady operation is derived on the line 55. In this way, the correction value calculation circuit 52 and the addition circuit 54 constitute means for correcting the set applied voltage Vb and generating a voltage control signal for steady operation.

A steady running voltage control that represents a signal representing the applied voltage Vs at the time of starting from the starting voltage control signal generating means 35 via the line 78, the changeover switch 73 and the line 36 and the applied voltage Vb1 at the steady state from the adding circuit 54. The signal is given to the adding circuit 60 via the switches 58 and 59 of the switching circuit 57, and the output of the adding circuit 60 is
The voltage control signal representing the applied voltage V0 is given to the spark control circuit 23 via the line 61. Switching circuit 57
Responds to the outputs of the lines 36 and 55, and if Vs <Vb1 ... (8), the switch 58 is turned on and the switch 59 is cut off, and when Vs ≧ Vb1 ... (9), the switch 58 is turned on. Shut off and switch 59
Is conducted. Thus, until the applied voltage Vs at the time of startup reaches the applied voltage Vb1 at the time of steady operation, the voltage control signal representing the applied voltage Vs via the line 36 is given to the spark control circuit 23 via the line 61. Further, the applied voltage Vs at the time of startup reaches the applied voltage Vb1 at the time of steady operation,
When the start-up is completed, the switches 58 and 59 are switched, and a voltage control signal representing the applied voltage Vb1 during the steady operation is applied to the spark control circuit 23 via the line 61. Once the applied voltage Vb1 at the time of steady operation is switched, Vb1 is given to the spark control circuit 23 until it is stopped. The switching circuit 57 and the switches 58 and 59 constitute switching means.

The applied voltage Vb1 during the steady operation increases the temperature of the air flowing through the electrostatic precipitator 3, and as a result, the current Ip detected by the ammeter 11 increases and corresponds to the reference temperature Tb. Discharge current I derived from the calculation means 44
When it exceeds 2, the output Eb of the subtraction circuit 48 becomes a negative value,
Therefore, the result is that the applied voltage Vb1 for steady operation is reduced. If the air temperature decreases, the reverse operation is performed. In this way, in the state where the common contact 41 of the changeover switch 38 is conducted to the individual contact 39, the applied voltage Vb1 is controlled during the steady operation to reduce the fluctuation of the discharge current Ip of the charging unit 4, and as described above. Constant current control is achieved.

Further, during steady operation, it is possible to manually switch between the three states of dust collection operation, dust collection pause operation and dust collection stop operation. During nighttime when the traffic volume is low and the dust concentration is low, the dust collection operation is switched to the dust collection pause operation to dehumidify the electrode surface. When the dust concentration exceeds a predetermined constant concentration, the dust collection operation is automatically switched to increase the voltage applied between the electrodes. At this time, since the electrode surface is always dehumidified and dried, it is possible to raise the voltage to the first voltage Vb in a short time without causing spark discharge. When cleaning the electrodes or inspecting the equipment, switch to dust collection stop operation and set the applied voltage between electrodes 6 and 7 to 0.
V.

FIG. 10 is a block diagram showing the electrical construction of the dust collector control circuit 22a for the dust collector 5 of the electric dust collector 3. As shown in FIG. Control circuit 22 for charging section and control circuit 22 for dust collecting section
a has a similar configuration.

The voltage Vp between the electrodes 13 and 14 detected by the voltmeter 20 is applied to the filter 28 in the calculating means 27a.
Unwanted variations are eliminated and given by a. The computing means 27a stores the characteristics of the applied voltage between the electrodes 13 and 14 and the maximum allowable leakage current I1 such that the maximum allowable leakage current I1 increases as the applied voltage increases, as indicated by 29a in FIG. It is equipped as a table. Further, unlike the calculating means 27, the characteristics of the applied voltage and the maximum allowable leakage current I1 included in the calculating means 27a are not affected by the air temperature.

The output of the calculation means 27a is the subtraction circuit 31a.
Given to. Leakage current Ip between the electrodes 13 and 14 detected by the ammeter 11 is applied to the subtraction circuit 31a after the filter 32a eliminates undesired fluctuations. The subtraction circuit 31a subtracts the detected current Ip detected by the ammeter 19 from the maximum allowable leakage current I1 calculated by the calculating means 27a as in the above-mentioned equation (1), and calculates the difference Eg.

The determination circuit 33a responds to the output Eg of the subtraction circuit 31a, and if Eg> 0 as shown in the above equation (2), the electrode 13 at the time of start-up shown in the above equation (3),
Predetermined rate of change Kg of voltage V to be applied between 14
Output a signal that represents. Further, as shown in the above formula (4), if Eg ≦ 0, the electrodes 13 and 14 are activated at the time of startup.
The rate of change with time of the voltage V to be applied during the period is set to zero as shown in the above-mentioned equation (5), and the applied voltage V is held. The time change rate Kg can be manually adjusted and set by the time change rate measuring means 34a.

The subtraction circuit 31a may have only the function of comparing and detecting the magnitude relation between the currents I1 and Ip.

The output of the judgment circuit 33a is given to the starting voltage control signal generating means 35a, and the voltage control signal representing the voltage Vs applied between the electrodes 13 and 14 is led to the line 78a. FIG. 12 is a view showing a time course of the applied voltage Vs represented by the voltage control signal derived from the starting voltage control signal generating means 35a, and is similar to FIG.

One individual contact 7 of the changeover switch 73a
5a is applied voltage Vs from the starting voltage generating means 35a.
Of the second voltage Vh from the second voltage setting means 72a is applied to the other individual contact 76a. The changeover switch 73a is operated by the changeover control means 77a. The switching control means 77a switches the changeover switch 73a in response to a command from the outside.

In the switching circuit 57a, the set voltage Vb is applied from the applied voltage setting means 45a through the line 46a, and the line 78 is applied from the starting voltage control signal generating means 35a.
A signal representing the applied voltage Vs is given through a, the changeover switch 73a, and the line 36a. Switching circuit 57a
Responds to the outputs of the applied voltage setting means 45a and the activation voltage control signal generating means 35a. If Vs <Vb (10), the switch 58a is turned on and the switch 59a is turned off. When Vs ≥ Vb (11), the switch 58a is cut off and the switch 5
9a is conducted. As a result, the applied voltage Vs at startup is
Until the voltage reaches the set voltage Vb, a voltage control signal representing the applied voltage Vs via the line 36a is given to the spark control circuit 23a via the line 61a, and when the applied voltage Vs reaches the set voltage Vb, the switches 58a and 59a are turned on. A voltage control signal which is switched and represents the applied voltage Vb during the steady operation is applied to the spark control circuit 23a via the line 61a. As a result, at the time of startup, the output from the startup voltage control signal generating means 35a is input to the spark control circuit 23a,
When the activation is completed, the output from the applied voltage setting means 45a is input to the spark control circuit 23a. Also spark control circuit 2
3a and the DC voltage generating means 24a perform the same operations as the spark control circuit 23 and the DC voltage generating means 24 in FIG.
The application electrode between the electrodes 13 and 14 of the dust collector 5 is controlled. As a result, the dust collecting unit can be controlled by using a circuit having a simpler configuration than the charging unit control circuit 22. Therefore, the product cost can be reduced.

In the spark control circuit 23, a signal representing the discharge current Ip of the ammeter 11 is given through the line 25, and if the current Ip increases by this, it can be detected that a spark discharge has occurred. The number of spark discharges for each predetermined time is counted by the counter 63. The setting circuit 64 presets the number of spark discharges during the preset time, and the comparison circuit 65 transfers between the electrodes 6 and 7 when the count value of the counter 63 becomes equal to or larger than the preset value set by the setting circuit 64. A signal representing the applied voltage V0a for stopping the supply of the voltage of V.sub.2 or for temporarily lowering the supply voltage and raising it again is applied to the high voltage generation circuit 24 through the line 66.
The high voltage generation circuit 24 applies the applied voltage V via the line 66.
A high voltage is generated so that 0a is applied between the electrodes 6 and 7 of the charging unit 4.

FIG. 13 is a waveform diagram for explaining the operation of the spark control circuit 23. Applied voltage V0 represented by the voltage control signal applied to the spark control circuit 23 via the line 61
13 is indicated by a virtual line in FIG. 13 and is the applied voltage V0a represented by the voltage control signal output via the line 66.
Is shown by the solid line in FIG. Each operation at times t1 and t2 in FIG. 13 is as described with reference to FIG. 8 described above, and the applied voltage Vs rises with the lapse of time at the time of startup. At time t12, after the applied voltage Vs for start-up increases and the start-up operation ends as indicated by the above-mentioned equation (9), the switching means 57 functions to perform the steady operation indicating the applied voltage Vb1. Voltage control signal is applied to the spark control circuit 23 via the line 61.

When a spark is generated between the electrodes 6 and 7 of the charging section 4 at time t4, the detected current Ip of the ammeter 11 increases, whereby the spark generation is detected and the applied voltage V
The supply of the applied voltage is stopped so that 0a instantly becomes zero. Further, as shown at times t5 to t6, when the number of sparks generated exceeds a predetermined value within a predetermined time, the voltage applied between the electrodes 6 and 7 is changed to ΔV1, for example, 200
It decreases by V, and then the applied voltage increases with the lapse of time. The value set by the setting circuit 64 may be, for example, 10 spark discharges in 30 seconds.

As shown at time t7 to t8, for example, when the spark discharge is continuously generated for about 1 minute, the applied voltage V0a decreases with the passage of time, and the applied voltage becomes 0 at the subsequent time t8. And the applied voltage V
The time for zeroing 0a is set to a predetermined time, for example, 1 minute. After that, at time t9, the applied voltage rises with time. At time t10, a short circuit between the electrodes 6 and 7 is detected by the output of the voltmeter 12, and the time is detected at time t10.
When it continues for about 2.5 seconds until a, for example, the applied voltage V0a for one minute thereafter until time t11.
Pause. The applied voltage V0a is increased again from time t11. After time t12, when it is detected that the amount of dust attached to the electrodes and the insulator is large and the short circuit continues to occur, it becomes impossible to continue the operation of the electrostatic precipitator 3, so that, for example, from time t12, At time t13 when 5 to 10 minutes have passed, the electrodes 6, 7; 13, 4 of the electrostatic precipitator 3
At time t13, the spark control circuit 23 derives a signal instructing that the pressure water should be jetted to perform water cleaning, and the water cleaning means performs water cleaning. After this water cleaning, the electrode surface is dried, and then the starting operation for dust collection after time t1 is repeated again. Further, once the dust that has once absorbed moisture is heated and dried, it becomes difficult to remove it, but in the present invention, since the dust is always kept in a dry state, the dust that has adhered to the electrode does not solidify, so it is removed. It becomes easier and the time required for cleaning can be shortened.

When the common contact 41 of the changeover switch 38 is switched to the individual contact 40 for conduction, the calculation means 44 is a signal representing the discharge current I2 during steady operation corresponding to the set voltage Vb with the detected temperature Tp of air as a parameter. This discharge current I2 changes in conjunction with the change in the air temperature Tp, so that the fluctuation of the applied voltage Vb1 becomes small. Thus, constant voltage control is performed.

As another embodiment of the present invention, the correction value calculation means 52 is omitted and the output of the subtraction circuit 48 is the addition circuit 54.
May be given directly to. Control device 10
May be realized by a microcomputer or the like.

Electrodes 6 and 7 of the charging section 4 during steady operation
The voltage applied between 10 and 12 kV DC may be, for example, 11 kV as described above, and in the dust collecting unit 5, the applied voltage during steady operation between the electrodes 13 and 14 is, for example, DC. It is selected to be 5 to 6 kV.

Further, according to the present invention, in both the charging section 4 and the dust collecting section 5, switching control is performed by the changeover switch 73 and the changeover control circuit 77, and when the dust collecting suspension operation is performed, the first and second electrodes 6 and 7; Although the voltage Vh of 2 is applied, the second voltage setting means 7 is applied only to the dust collector control circuit 22a.
2a, changeover switch 73a and changeover control circuit 77
a is installed, and in the control circuit 22 for the charging section, the line 78 and the line 36 are connected to perform switching control only by the dust collecting section 5 so that the second voltage is applied between the electrodes 13 and 14. Good.

Although the present invention may be implemented in connection with a ventilation system for reusing the air in the tunnel as described above, it is not limited to tunnel ventilation, but for example, to remove dust in the inlet gas of a denitration device. The present invention may be practiced in a wide variety of other technical fields.

[0049]

As described above, according to the present invention, the voltage generating means during the dust collecting operation is provided in the control device of the dust collector in which the gas containing dust is passed between the electrodes to which the voltage is applied from the voltage generating means. Generates a first voltage predetermined by the voltage generation means, and generates a second voltage which is less than the first voltage during the dust collection stop operation and can perform dehumidification by heat generation due to the leakage current of the electrode. And a voltage switching means for generating the voltage.

Further, according to the invention, in the method for starting the operation of the electrostatic precipitator, the second voltage is kept applied between the electrodes during the dust collection stop operation, and the first voltage for dust collection is maintained during the dust collection operation. In this method, the voltage of 1 rises with the passage of time. By applying a low voltage to the electrodes and generating Joule heat in this way, it is possible to keep the dust always dry and dehumidify the electrode surface. Therefore, the voltage can be raised from the second voltage to the first voltage without causing spark discharge in a short time, and the electric dust collector can be shifted to the dust collecting operation state.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration for activating a charging unit of a control device for an electrostatic precipitator according to an embodiment of the present invention.

FIG. 2 is a horizontal cross-sectional view showing a simplified configuration of a ventilation system for reusing the air in a tunnel, which is implemented in association with a control device for an electrostatic precipitator according to an embodiment of the present invention.

FIG. 3 is a plan view showing a simplified configuration of a charging unit 4 and a dust collecting unit 5 of the electrostatic precipitator 3.

FIG. 4 is a front view showing a simplified configuration of a charging unit 4 of the electrostatic precipitator 3.

5 is a front view showing a simplified configuration of a dust collecting portion 5 of the electric dust collector 3. FIG.

FIG. 6 is a block diagram showing an overall configuration of a control device 10 of the electrostatic precipitator 3.

7 is a graph showing the relationship between the applied voltage Vb and the discharge current I1 for explaining the operation of the calculating means 27 shown in FIG.

FIG. 8 is a diagram showing a time course of an applied voltage Vs when the charging unit 4 is started.

9 is a graph showing the relationship between the applied voltage Vb and the discharge current I2 for explaining the operation of the calculating means 44 for steady operation in FIG.

FIG. 10 is a block diagram showing a configuration for starting a dust collecting portion of the control device for the electrostatic precipitator according to the embodiment of the present invention.

11 is a graph showing the relationship between the applied voltage Vb and the leakage current I1 for explaining the operation of the calculating means 27a shown in FIG.

FIG. 12 is a diagram showing a time course of an applied voltage Vs at the time of startup in the dust collecting unit 5.

13 is a diagram showing applied voltages V0 and V0a for explaining the operation of the spark control circuit 23. FIG.

FIG. 14 is a diagram showing a time course of an applied voltage Vs at the time of starting the charging unit 4 in the related art.

[Explanation of symbols]

 1 Roadway tunnel 2 Electrostatic precipitator tunnel 3 Electrostatic precipitator 4 Charging part 5 Dust collecting part 6, 7; 13, 14 Electrode 10 Control device 11, 19 Ammeter 12, 20 Voltmeter 21 Temperature detecting means 22 Charging part control circuit 22a Dust collector control circuit 23, 23a Spark control circuit 24, 24a DC voltage generating means 27, 44; 27a Computing means 31, 48; 31a Subtraction circuit 33, 33a Judging means 35, 35a Starting voltage control signal generating means 38, 73; 73a changeover switch 42 reference temperature setting means 45, 45a applied voltage setting means 52 correction value calculation means 54, 60; 60a adding circuit 57, 57a switching circuit 72, 72a second voltage setting means 77, 77a switching control circuit

Claims (2)

[Claims] 1. A control device for an electrostatic precipitator in which a gas containing dust is passed between electrodes to which a voltage is applied from a voltage generating means, in a dust collecting operation, a first voltage determined in advance by the voltage generating means is generated, It is provided with a voltage switching unit that causes the voltage generating unit to generate a predetermined second voltage that is less than the first voltage during the dust collection pause operation and that can be dehumidified by the heat generated by the leakage current of the electrode. Control device for the electrostatic precipitator. 2. A method for starting operation of an electrostatic precipitator in which a gas containing dust is passed between electrodes to which a voltage is applied from a voltage generating means, wherein a voltage lower than an applied voltage during the dust collecting operation is used during a dust collecting pause operation. A second voltage that can be dehumidified by the heat generated by the leakage current of the electrodes is applied between the electrodes, and the voltage for dust collection rises with time during the dust collection operation. A method for starting operation of an electric dust collector, which is characterized by: