JP3112384B2 - Electric dust collector control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device of an electric precipitator which can be suitably implemented, for example, to collect and remove air dust in a tunnel.

[0002]

2. Description of the Related Art Pressurized water is sprayed to clean an electric precipitator used for removing dust contained in air in a tunnel, thereby using an insulator and an electrode of the electric precipitator. The dust collected on the ground is removed, and the continuous collection of tunnel dust is performed. In such a state that the electrodes and the like after water washing of the electrodes are not sufficiently dried, or in a state where dust existing on the surface of the insulator and the electrodes has absorbed moisture while the electric precipitator is stopped at night, between the electrodes. When a high voltage is applied, a short circuit may occur and the motor may not be able to start. Therefore, in the prior art, a high voltage for steady operation is applied after applying a low voltage of less than 11 kV for a predetermined time during steady operation of the electrostatic precipitator.

[0003] In such prior art, the state of the insulator, the electrodes, and the like at the start of the electric precipitator is different each time, and the state of air (for example, temperature, pressure, humidity, dust concentration, etc.) changes. Therefore, the form of the spark discharge changes accordingly, and the time during which a low voltage has to be applied so that the above-mentioned short circuit does not occur is different each time. Nevertheless, in the prior art, the time during which a low voltage is applied is set to a relatively long fixed time, so that a short circuit or the like does not occur even when the insulator and the electrodes are in a poor moisture absorption state. ing. Therefore, in the prior art, there is a problem that the time for applying a low voltage between the electrodes for startup is unnecessarily long, and it takes time to return to the steady operation.

In the prior art, when the electrostatic precipitator is operated in a steady state, the voltage applied between the electrodes is controlled by the number of spark discharges, that is, a predetermined number of times, for example, a predetermined number of times within 30 seconds, for example, 30 times or more. When it is detected that a spark discharge has occurred, the applied voltage is instantaneously stopped, and a constant voltage such as 10
A voltage reduced by 0 to 200 V is applied, and thereafter, the voltage gradually rises to a high voltage at the time of steady operation with time. When a spark discharge occurs between the electrodes, the dust contained in the air is no longer charged, and the dust adhering and collecting on the electrodes is re-scattered, thereby lowering the dust collection efficiency.

[0005] In such prior art, the state of air containing dust flowing between the electrodes of the electrostatic precipitator during steady operation is constantly changing, and the form of spark discharge changes depending on the state of the air. Cannot be reliably detected. Therefore, as in this prior art,
In a configuration in which the applied voltage is controlled only by the number of spark discharges, it is not possible to apply an optimum voltage between the electrodes while suppressing spark discharge and improving dust collection efficiency. In an electric precipitator, at a high voltage immediately before spark discharge occurs between the electrodes, the corona discharge current between the electrodes is maximized, and the amount of ion emission is maximized, whereby dust is charged and dust collection efficiency is improved. In the prior art, such an optimal dust collection state cannot be maintained. As a prior art relating to spark discharge, there is Japanese Patent Application Laid-Open No. 61-465.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the voltage between the electrodes at the time of starting up to the high voltage at the time of steady operation.
An object of the present invention is to provide a control device for an electric precipitator which can be raised in a time as short as possible and without spark discharge.

Another object of the present invention is to provide a control device for an electric precipitator capable of reducing the number of spark discharges and improving dust collection efficiency during a steady operation.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a control device for an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, comprising: a temperature detecting means for detecting a temperature Tp of the gas; A voltage meter for detecting the applied voltage Vp, a current meter for detecting the current Ip flowing through the electrode, a temperature detecting means and a calculating means for determining an allowable maximum discharge current I1 in response to the output of the voltmeter. Subtraction means for calculating the difference between the output I1 and the detection current Ip of the ammeter; and a time change in response to the output of the subtraction means, when the allowable maximum discharge current I1 exceeds the detection current Ip, the voltage applied between the electrodes is predetermined. Voltage control signal generating means for deriving a voltage control signal that rises at a rate, and deriving a voltage control signal that holds a voltage applied between the electrodes when the allowable maximum discharge current I1 is equal to or less than the detection current Ip;
And a voltage generating means for generating a voltage in response to a voltage control signal and supplying the voltage between the electrodes. The present invention also provides a control device for an electric precipitator in which a gas containing dust flows between electrodes to which a voltage is applied, wherein a reference temperature setting means for setting a predetermined reference temperature Tb of the gas; An application voltage setting means for setting a predetermined application voltage Vb, an arithmetic means for obtaining a discharge current I2 during steady operation in response to outputs of the reference temperature setting means and the application voltage setting means, and a current Ip flowing through the electrode. An ammeter to be detected, subtraction means for obtaining a difference between the output I2 of the arithmetic means and the detected current Ip of the ammeter, and the set applied voltage Vb corrected by the output of the subtraction means, and the voltage of the corrected voltage A control device for an electrostatic precipitator, comprising: a voltage control signal generating means for deriving a control signal; and a voltage generating means for generating a voltage in response to the voltage control signal and supplying the voltage between electrodes. The present invention also provides
In a control device of an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, a temperature detecting means for detecting a temperature Tp of the gas and a predetermined applied voltage Vb between the electrodes during a steady operation are set. Calculating means for determining a discharge current I2 during steady operation in response to outputs of the applied voltage setting means, the temperature detecting means and the applied voltage setting means; an ammeter for detecting a current Ip flowing through the electrode; Subtracting means for obtaining a difference between I2 and the detection current Ip of the ammeter; and correcting the set applied voltage Vb by an output of the subtracting means.
A voltage control signal generating means for deriving a voltage control signal of the corrected voltage; and a voltage generating means for generating a voltage in response to the voltage control signal and supplying the voltage between the electrodes. It is a control device. The present invention also provides a control device of an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, a reference temperature setting means for setting a predetermined reference temperature Tb of the gas, and a temperature T of the gas.
temperature detection means for detecting p, switching means for switching and outputting the output of the reference temperature setting means or the temperature detection means,
An applied voltage setting means for setting a predetermined applied voltage Vb between the electrodes during a steady operation; and a discharge current I in a steady operation in response to an output from the switching means and an output from the applied voltage setting means.
2, an ammeter for detecting the current Ip flowing through the electrode, the output I2 of the arithmetic means and the detected current I of the ammeter.
a voltage control signal generating means for correcting the set applied voltage Vb by an output of the subtraction means to derive a voltage control signal of the corrected voltage; And a voltage generating means for generating a voltage and supplying the voltage between the electrodes. The present invention also provides a control device for an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, a temperature detecting means for detecting a temperature Tp of the gas, and a voltage for detecting an applied voltage Vp between the electrodes. Meter, an ammeter for detecting a current Ip flowing through the electrode, first calculating means for determining an allowable maximum discharge current in response to outputs of the temperature detecting means and the voltmeter, and an output I1 of the first calculating means and an ammeter. A first subtraction means for obtaining a difference from the detected current Ip, and an allowable maximum discharge current I1 is detected in response to an output of the first subtraction means.
When the allowable maximum discharge current I1 is equal to or less than the detection current Ip, a voltage control signal for deriving a voltage control signal that raises the voltage applied between the electrodes at a predetermined time rate of change when exceeding First voltage control signal generating means for deriving a signal, reference temperature setting means for setting a predetermined reference temperature Tb of the gas, and first switching means for switching and outputting the outputs of the temperature detecting means and the reference temperature setting means When,
An applied voltage setting means for setting a predetermined applied voltage Vb between the electrodes during the steady operation, and a discharge current I2 for the steady operation in response to the output from the first switching means and the output from the applied voltage setting means. 2 operation means and the output I of the second operation means
A second subtraction means for obtaining a difference between the second voltage and the detection current Ip of the ammeter, and a second control means for correcting the set applied voltage Vb by an output of the second subtraction means to derive a voltage control signal of the corrected voltage. Two voltage control signal generating means, first and second
In response to the voltage control signal of (a), when the voltage Vs by the first voltage control signal is lower than the voltage Vb1 by the second voltage control signal, the first voltage control signal is derived, and the voltage Vs by the first voltage control signal becomes the second voltage control signal. When the voltage is equal to or higher than the voltage Vb1 by the voltage control signal, the second switching means for deriving the second voltage control signal, and generating the voltage in response to the first or second voltage control signal from the second switching means. And a voltage generating means for supplying a voltage between the electrodes.

[0009]

In an electric precipitator, a voltage is applied between electrodes through which a gas containing dust, for example, air flows, to generate corona discharge, charge the dust particles, and move the charged dust particles to the electrodes by electrostatic force. To collect dust. In general, dust collection efficiency is better as the corona discharge current is larger. The corona discharge current increases as the applied voltage between the electrodes increases, and when the voltage is further increased, the state 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 applied voltage between the electrodes is the same.

According to the present invention, the temperature Tp of the gas containing dust, for example, air, is detected by the temperature detecting means, and the voltage Vp applied between the electrodes is detected by the voltmeter. Calculation means 27 according to voltage Vp
Then, for example, an allowable maximum discharge current I1 between the electrodes with respect to the applied voltage Vp using the gas temperature Tp as a parameter is obtained from a table of a memory or the like. The magnitude relationship between the detected current Ip between the electrodes and the detected current Ip is compared and detected by a subtraction means. If the allowable maximum discharge current I1 exceeds the detected current Ip, the voltage applied between the electrodes at a predetermined time rate of change. And the applied voltage is increased so that the discharge current Ip between the electrodes does not exceed the allowable value I1. Current Ip at which maximum allowable discharge current I1 is detected
If it is below, the applied voltage is maintained, that is, the voltage between the electrodes is kept constant without lowering. Thus, the applied voltage can be increased to a high voltage for steady operation in the shortest time without causing spark discharge between the electrodes. Thus, based on the gas temperature and the discharge current, the rise pattern or rise rate of the applied voltage is determined,
The electric dust collector is started smoothly.

Further, according to the present invention, at the time of steady operation, the constant current operation is performed such that the discharge current I2 for generating corona discharge between the electrodes becomes substantially constant. That is, the predetermined reference temperature Tb of the gas containing dust, for example, 25 ° C. is set by the reference temperature setting means, and the voltage Vb applied between the electrodes during the steady operation is set to, for example, 11 kV by the applied voltage setting means. Based on the reference temperature Tb and the predetermined applied voltage Vb, the calculating means 44 stores the discharge current characteristic with respect to the applied voltage Vb having the gas temperature Tb as a parameter, for example, as a memory table. Calculate the discharge current I2 during operation,
The subtraction means 48 subtracts the difference Eb between the discharge current I2 output from the calculation means 44 and the discharge current Ip detected by the ammeter for corona discharge between the electrodes.
8, the applied voltage Vb set by the applied voltage setting means is corrected by the output of the subtracting means 48. If the discharge current I2 exceeds the detection current Ip, for example, the set applied voltage is increased. And discharge current I2
Is less than the detection current Ip, the set applied voltage is reduced,
Thus, the steady operation is performed so that the current between the electrodes becomes substantially constant. As a result, the number of spark discharges during the steady operation can be significantly reduced, and the dust collection efficiency can be improved.

In particular, in the present invention, even when the temperature of the gas containing dust increases, the discharge current value between the electrodes is kept at the discharge current I2 determined by the calculating means 44. When the applied voltage between the electrodes is constant, the discharge current between the electrodes increases due to the rise in temperature, and thus the discharge current I2 is less than the current Ip flowing through the electrodes, and Difference (= I2-
Ip) becomes large, and thus the set applied voltage Vb is corrected to be low. In summary, when the gas temperature increases, the discharge current value remains constant and the applied voltage decreases. Therefore, the number of spark discharges can be significantly reduced.

According to the present invention, the temperature of the gas containing dust is detected by the temperature detecting means during the steady operation of the electric precipitator, and the temperature is detected by the detected temperature and the predetermined applied voltage set by the applied voltage setting means. The discharge current I2 at the time of steady operation is obtained, and the set applied voltage is corrected based on the magnitude relationship or difference between the discharge current I2 and the current Ip detected by the ammeter. As a result, the discharge current I2 changes in conjunction with the change in the gas temperature Tp, so that the change in the voltage applied between the electrodes is reduced, and constant voltage control is performed. That is, the set applied voltage Vb in the steady state is constant, and the discharge current I2 obtained by the calculation means changes as the gas temperature changes, and the discharge current I2 obtained by this calculation means becomes the actual value, That is, if they match the detection current Ip, the difference Eb (= I2-I
p) is zero or a constant value, whereby the voltage applied between the electrodes is maintained at the set applied voltage Vb or a fixed value corresponding to the set applied voltage Vb. Thus, the constant voltage control is performed as described above.

Further, according to the present invention, until the voltage Vs applied between the electrodes for start-up becomes equal to or higher than the voltage Vb1 applied between the electrodes for steady operation, the voltage Vs for start-up is maintained between the electrodes. The operation can be smoothly shifted from the start to the steady operation by the operation of the second switching means.

[0015]

FIG. 1 is a block diagram showing a configuration of a part of a control device of an electric precipitator according to an embodiment of the present invention. The electric precipitator is disposed as shown by reference numeral 3 in an electric precipitator tunnel 2 communicating with a side wall of a 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, contaminated air containing dust in the roadway tunnel 1 is bypassed to the tunnel 2 to form a longitudinal ventilation system. As a result, the purified air from which dust in the air has been removed is blown into the space of the roadway tunnel 2. As a result, the line-of-sight distance in the roadway tunnel 2 can be improved.

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

A dust collecting section 5 is arranged downstream of the charging section 4. As shown in FIG. 5, the dust collecting section 5 has a plurality of flat electrodes 13 and 14 arranged alternately so as to face each other. One electrode 13 is grounded via line 15. The other electrode 14 is connected to the controller 10 via a line 16 and is provided with a positive voltage. In this way, the air containing the dust flows between the electrodes 6 and 7 of the charging unit 4, so that the dust is charged by corona discharge, and the charged dust is applied to the electrodes 13 and 14 of the dust collection unit 5 by electrostatic force. Adhered and collected. The electrodes 6, 7; 13, 14 are sprayed with water and washed with water at regular intervals to collect dust and to be washed off.

The discharge current flowing between the electrodes 13 and 14 is detected by an ammeter 19, and the voltage between the electrodes 13 and 14 is detected by a 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 of the electric precipitator 3. For the charging unit 4 of the electrostatic precipitator 3, a charging unit control circuit 22 and a spark control circuit 2
3 and a DC voltage generating circuit 24. Similarly, for the dust collecting section 5, a dust collecting section control circuit 22a, a spark control circuit 23a, and a DC high voltage generating circuit 24a are provided.
The output of the temperature detecting means 21 is supplied to a control circuit 22 for the charging unit and a control circuit 22a for the dust collection unit. The output of the ammeter 11 of the charging unit 4 is supplied to a control circuit 22 for the charging unit and to a spark control circuit 23 via a line 25. The output of the voltmeter 12 of the charging unit 4 is provided to the control unit 22 for the charging unit. Similarly, the output of the ammeter 19 in the dust collecting section 5 is supplied to the dust collecting section control circuit 22a and also to the spark control circuit 23a via the line 25a. The output of the voltmeter 20 of the dust collecting section 5 is given to the dust collecting section control circuit 22a. Such a dust collecting part 5
Each of the components 22a, 23a, and 24a has the same configuration as the components 22, 23, and 24 for the charging unit 4.

Referring again to FIG. 1, in the charging section control circuit 22 for the charging section 4 of the electrostatic precipitator 3, a signal representing the temperature Tp of the air detected by the temperature detecting section 21 is sent to the calculating section 27. From the voltage Vp between the electrodes 6 and 7 detected by the voltmeter 12
Output is provided. The filter 28 is a voltmeter 1
2 serves to eliminate undesired fluctuations of the output. The calculating means 27 calculates the applied voltage between the electrodes 6 and 7 and the allowable discharge current I1 using the detected air temperature Tp as a parameter.
Are provided as a memory table.
As the applied voltage increases, the allowable maximum discharge current I1 increases, and as the air temperature Tp increases, the discharge current I1 increases even if the applied voltage is constant. Compared to the line 29 in FIG. 7, the characteristics of the line 30 are characteristics when the air temperature Tp is high. Allowable maximum discharge current I1
Indicates a maximum current in which a corona discharge occurs between the electrodes 6 and 7 of the charging unit 4 and no spark discharge occurs.

The output of the operation means 27 is given to a subtraction circuit 31. The discharge current Ip between the electrodes 6 and 7 detected by the ammeter 11 is applied to the filter 32
Thus, the undesired fluctuation is eliminated and the result is given to the subtraction circuit 31. The subtraction circuit 31 subtracts the detection current Ip detected by the ammeter 11 from the allowable maximum discharge current I1 obtained by the calculation means 27, and obtains 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 the voltage 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.

[0023]

(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 startup is set to zero as shown in Expression 5, and the applied voltage V is held. .

[0025]

(Equation 2)

When the allowable maximum discharge current I1 exceeds the detection current Ip, that is, when the detection current Ip is lower than the allowable maximum discharge current I1, a signal representing an applied voltage that increases at a time rate of change Kg is derived. When the maximum discharge current I1 is equal to or smaller than the detection current Ip,
When p is equal to or more than the allowable maximum discharge current I1, the applied voltage is maintained as it is. This 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 relation between the currents I1 and Ip.

The output of the judgment circuit 33 is supplied to a starting voltage control signal generating means 35, and the voltage V applied between the electrodes 6 and 7
A voltage control signal representing s is derived on line 36. FIG.
FIG. 5 is a diagram showing a time lapse of an applied voltage Vs represented by a voltage control signal derived from a starting voltage control signal generating means 35. From time t1, the applied voltage is increased at the time rate of change represented by the above-mentioned equation 3, and thereafter, the time rate of change is set to zero as shown by the equation 5, and similarly, at time t2 and t3, the applied voltage is increased at the time rate of change Kg. The voltage is increased, and then the time rate of change is made zero. By repeating such an operation, the voltage applied between the electrodes 6 and 7 increases with time. Time change rate Kg may be, for example, 200 V / sec.

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

The calculating means 44, as shown in FIG.
The characteristics of the applied voltage Vb and the discharge current I2 in the charging unit 4 using the temperature of the air represented by the signal via the common contact 41 of the changeover switch 38 as a parameter are stored as a memory table. At the time of constant current control in which the common contact 41 and the individual contact 39 of the changeover switch 38 are conductively connected, the set discharge current I2 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 FIG.
Compared with the characteristic of No. 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 characteristic of the lines 49 and 50 has an approximate value that is less than the maximum allowable discharge current described in connection with FIG. As a result, the corona discharge current can be increased to increase the amount of emitted ions, the dust contained in the air can be charged efficiently, and the dust collection efficiency can be increased.

The subtracting circuit 48 includes the ammeter 11 of the charging unit 4.
Is detected by the filter 3 as described above.
2 is given. The subtraction circuit 48 includes
Current I2 and detection current I during steady operation output from
It is obtained by subtracting the difference Eb of p.

Eb = I 2 −Ip (6) The correction value calculation circuit 52 calculates and 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
The value may be a value between 1 and more 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 supplied to an addition circuit 54, and is 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 at the time of steady operation is derived to a line 55. Thus, 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 switching circuit 57 converts a signal representing the applied voltage Vs at the time of starting from the starting voltage control signal generating means 35 via the line 36 and a steady operation voltage control signal representing the applied voltage Vb1 during the steady state from the adding circuit 54. , And an output of the addition circuit 60 is supplied to the spark control circuit 23 via a line 61 as a voltage control signal representing the applied voltage V0. The switching circuit 57 responds to the output of the lines 36 and 55. If Vs <Vb1 (9), the switch 58 is turned on, the switch 59 is turned off, and if Vs ≧ Vb1 (10), Switch 58 is turned off and switch 59 is turned off.
Is conducted. In this way, until the applied voltage Vs at the time of starting reaches the applied voltage Vb1 at the time of the steady operation, a voltage control signal indicating the applied voltage Vs via the line 36 is given to the spark control circuit 23 via the line 61. When the applied voltage Vs at the time reaches the applied voltage Vb1 during the steady operation, the switches 58 and 59 are switched, and a voltage control signal representing the applied voltage Vb1 during the steady operation is sent to the spark control circuit 23 via the line 61. Given. Once the voltage is switched to the applied voltage Vb1 during the steady operation, Vb1 is supplied to the spark control circuit 23 until it stops. The switching circuit 57 and the switches 58 and 59 constitute switching means.

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

In the spark control circuit 23, a signal representing the discharge current Ip of the ammeter 11 is given via the line 25, and if the current Ip increases, it can be detected that a spark discharge has occurred. The number of spark discharges at predetermined time intervals is counted by the counter 63. The setting circuit 64 sets the number of spark discharges during the predetermined time in advance, and the comparison circuit 65 sets the number of spark discharges between the electrodes 6 and 7 when the count value of the counter 63 exceeds the predetermined value set in the setting circuit 64. Is supplied to the high voltage generation circuit 24 via a line 66 to suspend the supply of the voltage or to reduce the supply voltage once and to increase the supply voltage again.
The high voltage generation circuit 24 applies the applied voltage V
A high voltage is generated so that 0a is applied between the electrodes 6 and 7 of the charging unit 4.

FIG. 10 is a waveform diagram for explaining the operation of the spark generation circuit 23. The applied voltage V0 represented by the voltage control signal applied to the spark generation circuit 23 via the line 61
Is an applied voltage V0a indicated by a virtual line in FIG. 10 and represented by a voltage control signal output via a line 66.
Is indicated by a solid line in FIG. The operations at times t1, t2, and t3 in FIG. 10 are as described with reference to FIG. 8 described above, and the applied voltage Vs increases with time at the time of startup. At time t3a, after the applied voltage Vs for start-up is increased and the start-up operation is completed as shown in the above-described equation 10, the voltage for the steady operation representing the applied voltage Vb1 is displayed by the operation of the switching means 57. A control signal is provided to the spark control circuit 23 via line 61.

When a spark is generated between the electrodes 6 and 7 of the charging unit 4 at time t4, the detection current Ip of the ammeter 11 increases, whereby the occurrence of the spark is detected and the applied voltage V
The supply of the applied voltage is stopped so that 0a becomes zero instantaneously. Further, as shown at times t5 to t6, when the number of spark occurrences becomes equal to or greater than a predetermined value within a predetermined time, the voltage applied between the electrodes 6 and 7 is changed to ΔV1, for example, 200V.
V, and thereafter, the applied voltage increases with time. The value set by the setting circuit 64 may be, for example, 10 spark discharges per 30 seconds.

As shown from time t7 to time t8, when a spark discharge is generated continuously for, for example, about one minute, the applied voltage V0a decreases with time. The time when the voltage is set to 0 and the applied voltage V0a is set to zero is set to a predetermined time, for example, 1 minute. Thereafter, at time t9, the applied voltage increases with time. At time t10, the electrodes 6,
When the short circuit of No. 7 is detected by the output of the voltmeter 12 and the time continues for, for example, about 2.5 seconds until time t10a, the applied voltage V0a is suspended for, for example, one minute until time t11. From time t11, the applied voltage V0a is increased again. When it is detected that the short circuit continues to occur after time t12, at time t13 when, for example, approximately 5 to 10 minutes have elapsed from time t12, pressurized water is applied to the electrodes 6, 7, 13 and 14 of the electrostatic precipitator 3. At time t13, the spark control circuit 23 derives a signal for instructing that water cleaning should be performed by spraying, and the water cleaning means performs water cleaning. After the water washing, the starting operation for collecting dust after the time t1 is repeated again.

When the common contact 41 of the changeover switch 38 is switched to the individual contact 40 and turned on, the calculating means 44 outputs a signal representing the discharge current I2 at the time of steady operation corresponding to the set voltage Vb with the detected temperature Tp of air as a parameter. Since the discharge current I2 changes in conjunction with the change in the air temperature Tp, the fluctuation of the applied voltage Vb1 is reduced. Thus, the 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
May be provided directly to the user. Control device 10
May be realized by a microcomputer or the like.

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

Although the present invention may be practiced in connection with a ventilation system that recycles air in a tunnel as described above, it is not limited to tunnel ventilation and may be, for example, to remove dust from the inlet gas of a denitration device. The present invention may be practiced in other various technical fields.

[0044]

As described above, according to the present invention, when the electric precipitator is started, the applied voltage Vp having the gas temperature as a parameter is determined by the temperature Tp of the gas containing dust and the applied voltage Vp between the electrodes. The corresponding allowable maximum discharge current I1
Is calculated by the calculating means 27, and the allowable maximum discharge current I
1 and the detected current Ip of the ammeter, if the allowable maximum discharge current I1 exceeds the detected current Ip, the voltage applied between the electrodes increases at a predetermined time rate of change. The applied voltage is maintained, and thus the applied voltage Vs between the electrodes can be increased so that the discharge current between the electrodes at the time of starting does not exceed the allowable maximum discharge current I1, which is an allowable value. The applied voltage can be raised to the high voltage in the steady operation in the shortest time without causing discharge.

Further, according to the present invention, at the time of steady operation, the discharge is performed in accordance with the discharge current characteristic of the calculating means based on the predetermined reference temperature Tb of the gas containing dust and the predetermined applied voltage Vb between the electrodes during the steady operation. The set applied voltage Vb is set so that the actual discharge current during the steady operation between the electrodes does not exceed the discharge current I2 obtained from the calculating means 44.
Is corrected, whereby the number of spark discharges during the steady operation can be greatly reduced, and the dust collection efficiency can be improved. In particular, when the gas temperature increases, the applied voltage can be reduced as compared with the above-described prior art while maintaining the discharge current value, and the number of times of spark discharge can be greatly reduced. Becomes possible.

Further, according to the present invention, during the steady operation, the temperature Tp of the gas containing dust is detected by the temperature detecting means, and the discharge is performed based on the detected temperature Tp and the predetermined applied voltage Vb during the steady operation. The discharge current I2 is calculated by the calculating means 44 according to the current characteristic, and the discharge current I2 determined by the calculating means 44 and the detection current Ip of the ammeter are calculated.
The constant voltage operation can be performed by correcting the set application voltage Vb according to the magnitude relation of.

Further, according to the present invention, the applied voltage Vs between the electrodes is determined at the time of startup using the first calculating means 27, and the applied voltage Vb 1 during the steady operation is determined by the detection gas selected by the first switching means 38. Temperature Tp or reference temperature Tb
And the set application voltage Vb during the steady operation, the set application voltage Vb is corrected by the discharge current I2 determined by the second calculating means 44, and the constant current control or the constant voltage control during the steady operation is switched and performed. To be able to
Further, the applied voltage Vs at the start determined by the first voltage control signal generating means 33, 35 at the start is changed to the applied voltage Vb1 determined by the second voltage control signal generating means 52, 53, 54 for the steady operation. When it has reached, the operation of the second switching means 57, 58, 59 enables a smooth transition from the starting state to the steady operation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration for starting a charging unit of a control device of an electric dust collector according to an embodiment of the present invention.

FIG. 2 is a simplified horizontal cross-sectional view showing a configuration of a ventilation system for reusing air in a tunnel implemented in connection with a control device for an electric dust collector according to an embodiment of the present invention.

FIG. 3 is a simplified plan view showing a configuration of a charging unit 4 and a dust collecting unit 5 of the electric dust collector 3;

FIG. 4 is a simplified front view showing a configuration of a charging unit 4 of the electric dust collector 3;

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

FIG. 6 is a block diagram showing an overall configuration of a control device 10 of the electric dust collector 3;

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

FIG. 8 is a diagram illustrating a lapse of time of an applied voltage Vs at the time of activation in the charging unit 4.

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

FIG. 10 is a diagram showing applied voltages V0 and V0a for explaining the operation of the spark control circuit 23.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tunnel for roadway 2 Tunnel for electric precipitator 3 Electric 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 Control circuit for charging part 22a Dust collection part control circuit 23, 23a Spark control circuit 24, 24a DC voltage generation means 27, 44 Operation means 31, 48 Subtraction circuit 33 Judgment means 35 Start-up voltage control signal generation means 38 Changeover switch 42 Reference temperature setting means 45 Application Voltage setting means 52 Correction value calculation means 54, 60 Addition circuit 57 Switching circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B03C 3/00-3/88

Claims (5)

(57) [Claims] 1. A control device of an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, a temperature detecting means for detecting a temperature Tp of the gas, and a voltage for detecting an applied voltage Vp between the electrodes. An ammeter for detecting a current Ip flowing through the electrode; an arithmetic means for determining an allowable maximum discharge current I1 in response to outputs of the temperature detecting means and the voltmeter; an output I1 of the arithmetic means and a detected current of the ammeter And a voltage control signal responsive to an output of the subtraction means for increasing a voltage applied between the electrodes at a predetermined time change rate when the allowable maximum discharge current I1 exceeds the detection current Ip. A voltage control signal generating means for deriving a voltage control signal for holding a voltage applied between the electrodes when the allowable maximum discharge current I1 is equal to or less than the detection current Ip, and generating a voltage in response to the voltage control signal. An electrostatic precipitator control system, characterized in that it comprises a voltage generating means for supplying to the electrodes. 2. A control device for an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, comprising: a reference temperature setting means for setting a predetermined reference temperature Tb of the gas; An application voltage setting means for setting a predetermined application voltage Vb, a calculation means for obtaining a discharge current I2 in a steady operation in response to outputs of the reference temperature setting means and the application voltage setting means, and a current Ip flowing through the electrode. An ammeter to be detected; a subtraction means for calculating a difference between an output I2 of the arithmetic means and a detection current Ip of the ammeter; and a correction of the set applied voltage Vb by an output of the subtraction means, and a voltage of the corrected voltage. A control device for an electrostatic precipitator, comprising: voltage control signal generating means for deriving a control signal; and voltage generating means for generating a voltage in response to the voltage control signal and supplying the voltage between electrodes. 3. A control device for an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, comprising: a temperature detecting means for detecting a temperature Tp of the gas; An applied voltage setting means for setting the voltage Vb; an arithmetic means for responding to outputs of the temperature detecting means and the applied voltage setting means for obtaining a discharge current I2 during steady operation; and an ammeter for detecting a current Ip flowing through the electrode. Subtracting means for calculating the difference between the output I2 of the calculating means and the detection current Ip of the ammeter; and correcting the set applied voltage Vb by the output of the subtracting means to derive a voltage control signal of the corrected voltage. A control device for an electrostatic precipitator, comprising: a voltage control signal generating means; and a voltage generating means for generating a voltage in response to the voltage control signal and supplying the voltage between the electrodes. 4. A control device of an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, wherein a reference temperature setting means for setting a predetermined reference temperature Tb of the gas; A temperature detecting means for detecting, a switching means for switching and outputting the output of the reference temperature setting means or the temperature detecting means, an applied voltage setting means for setting a predetermined applied voltage Vb between the electrodes during a steady operation, and a switching means. Calculating means for determining a discharge current I2 during steady operation in response to the output of the power supply and the output of the applied voltage setting means; an ammeter for detecting a current Ip flowing through the electrode; an output I2 of the calculating means and a detected current of the ammeter. Subtraction means for calculating a difference from Ip; and a voltage control signal generation means for correcting the set applied voltage Vb by an output of the subtraction means and deriving a voltage control signal of the corrected voltage. Stage and, in response to the voltage control signal, the control device of the electrostatic precipitator, which comprises a voltage generating means for supplying to the electrodes to generate a voltage. 5. A control device of an electric precipitator for flowing a gas containing dust between electrodes to which a voltage is applied, a temperature detecting means for detecting a temperature Tp of the gas, and a voltage for detecting an applied voltage Vp between the electrodes. A current meter for detecting a current Ip flowing through the electrode; a first calculating means for determining an allowable maximum discharge current in response to outputs of the temperature detecting means and the voltmeter; an output I1 of the first calculating means and an ammeter A first subtraction means for calculating a difference from the detected current Ip, and a time change rate in response to an output of the first subtraction means, wherein a voltage applied between the electrodes is predetermined when an allowable maximum discharge current I1 exceeds the detection current Ip. Derive the voltage control signal that rises with
First voltage control signal generating means for deriving a voltage control signal for maintaining a voltage applied between the electrodes when the allowable maximum discharge current I1 is equal to or less than the detection current Ip; and a reference temperature for setting a predetermined reference temperature Tb of the gas. Setting means; first switching means for switching and outputting the outputs of the temperature detecting means and the reference temperature setting means; applied voltage setting means for setting a predetermined applied voltage Vb between the electrodes during steady operation; A second calculating means for determining a discharge current I2 during a steady operation in response to an output from the means and an output from the applied voltage setting means; and calculating a difference between the output I2 of the second calculating means and the detection current Ip of the ammeter. A second subtraction unit, a second voltage control signal generation unit that corrects the set applied voltage Vb by an output of the second subtraction unit, and derives a voltage control signal of the corrected voltage; In response to the voltage control signal, the voltage Vs based on the first voltage control signal is changed to the voltage Vb based on the second voltage control signal.
A second switching means for deriving a first voltage control signal when the value is less than 1, and deriving a second voltage control signal when a voltage Vs based on the first voltage control signal is equal to or higher than a voltage Vb1 based on the second voltage control signal; And a voltage generation means for generating a voltage in response to the first or second voltage control signal from the second switching means and supplying the voltage between the electrodes.