JP2709030B2 - Method and apparatus for detecting cleaning time of electric dust collector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting the cleaning time of an electric dust collector, which are preferably implemented to collect and remove air dust in a tunnel in which an automobile runs, for example.

[0002]

2. Description of the Related Art An electric dust collector for ventilation in a tunnel in which an automobile or the like travels is divided into a charging part and a dust collecting part.
A step type electric dust collector is adopted. In the electrostatic precipitator, a corona discharge is generated by applying a high voltage between the charging unit electrodes, and a gas containing dust (hereinafter, referred to as a gas to be treated);
For example, air is passed through to charge the dust particles in the gas to be treated. The charged dust particles are deposited on the dust collecting portion electrode by an electrostatic action to perform dust collection. Generally, dust collection efficiency is better as the corona discharge current is larger. When the amount of dust accumulated for the dust collecting portion electrode exceeds a certain amount, spark discharge frequently occurs, or the dust re-scatters, thereby causing a reduction in dust collection efficiency,
It is necessary to stop the electric precipitator every certain time and wash the electrode with water or the like to remove dust adhering to the electrode.

[0003] In one prior art, the electrode is cleaned at predetermined intervals. In the above-mentioned electric precipitator, when the amount of adhering dust increases, spark discharge frequently occurs between the electrodes. In particular, if spark discharge occurs at the time of starting operation, the electric precipitator may not be able to be started. In this prior art, in order to prevent this, the cleaning time of the electrode is set shorter than the period in which the amount of the attached dust increases as the amount of spark discharge increases. For this reason, the amount of the attached dust is not so large as to cause many spark discharges, and the dust collector may be unnecessarily stopped and the electrode may be washed at an early stage when the electrode need not be washed.

In another prior art, the number of occurrences of spark discharges generated in a dust collecting portion electrode is measured, and when the number of occurrences exceeds a set number, the dust collector is stopped to clean the electrodes. I have. However, if spark discharge occurs frequently, the dust adhering to the dust collecting portion electrode may be scattered again to lower the dust collecting efficiency.

[0005] Still another prior art is disclosed in
8-10148. This prior art measures the electrostatic capacitance between the dust collecting unit electrodes corresponding to the attached dust thickness,
This is a method of detecting the cleaning time from the change in the capacitance. In such a method, an AC power supply and an electrode for detecting the capacitance are required, and therefore, there is a problem that a power supply device and an electrode structure of the dust collecting section are complicated.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent unnecessary cleaning of the dust collecting portion electrode, prevent dust from re-scattering, maintain good dust collecting efficiency, and An object of the present invention is to provide a method and an apparatus for detecting a cleaning time of an electric dust collector, which can simplify the configuration of the apparatus.

[0007]

According to the present invention, there is provided a method for detecting a cleaning time of an electric precipitator in which a gas to be treated, which is a gas containing dust, flows between electrodes to which a voltage is applied from a voltage generating means. The leak current, the temperature and humidity of the gas to be processed are detected, and the thickness of the dust attached to the electrode is calculated from the leak current, the temperature, and the humidity, and the thickness is equal to or greater than a predetermined value. It is a method for detecting the cleaning time of an electric dust collector, wherein it is determined that the cleaning time has come.

The present invention also relates to an apparatus for detecting a cleaning time of an electric precipitator in which a gas to be treated, which is a gas containing dust, flows between electrodes to which a voltage from a voltage generating means is applied. Leakage current detecting means, temperature detecting means for detecting the temperature of the gas to be treated, humidity detecting means for detecting the humidity of the gas to be treated, the leak current detecting means, the temperature detecting means, and the humidity A thickness calculating means responsive to each output of the detecting means for calculating the thickness of the dust adhering on the electrode; and a value obtained by calculating the thickness of the dust responsive to the output from the thickness calculating means. And a level discriminating means for discriminating a level as to whether or not the above is the case.

The thickness calculating means of the present invention includes a first calculating means for calculating a humidity characteristic coefficient h0 of the resistivity ρ0 of the gas to be processed corresponding to an output Hp from the humidity detecting means, and the humidity detecting means. Second calculating means for calculating the humidity characteristic coefficient h1 of the resistivity ρ1 of the dust corresponding to the output Hp from the temperature sensor, and the temperature characteristic coefficient of the resistivity ρ0 of the gas to be processed corresponding to the output Tp from the temperature detecting means. third calculating means for calculating t0, fourth calculating means for calculating a temperature characteristic coefficient t1 of the resistivity ρ1 of the dust corresponding to the output Tp from the temperature detecting means, a predetermined reference temperature and a predetermined reference humidity Resistivity ρ0c of the gas to be treated at
Gas resistivity output means for outputting a signal representing the following: a dust resistivity output means for outputting a signal representing the resistivity ρ1c of the dust at the reference temperature and the reference humidity;
T0, t1, outputs of the calculation means h0, h1, t0, t1, the resistivity ρ0c of the gas to be treated at the reference temperature and the reference humidity, the resistivity ρ1c of the dust at the reference temperature and the reference humidity, and Predetermined area S
A thickness d1 of dust adhering to the electrodes, based on a voltage V from the voltage generation unit, a leakage current i detected by the leakage current detection unit, and a predetermined interval d0 between the electrodes.

[0010]

(Equation 2)

And a calculating means for calculating

[0012]

According to the present invention, a method for detecting the cleaning time of an electric precipitator in which a gas to be treated, which is a gas containing dust, flows between electrodes to which a voltage from a voltage generating means is applied is provided. Detecting the temperature and humidity of the gas to be processed, calculating the thickness of the dust adhering to the electrode from the leakage current, the temperature and the humidity, and determining the cleaning time when the thickness becomes a predetermined value or more. This is a method in which it is determined that the cleaning has occurred, and cleaning is performed. Further, an apparatus therefor, a leakage current detecting means for detecting a leakage current between the electrodes, a temperature detecting means for detecting the temperature of the gas to be treated, a humidity detecting means for detecting the humidity of the gas to be treated, Responding to each output of the leakage current detecting means, the temperature detecting means, and the humidity detecting means, a thickness calculating means for calculating the thickness of dust adhering on the electrode, and responding to an output from the thickness calculating means, Level discriminating means for discriminating whether the thickness of the dust obtained by the calculation is equal to or greater than a predetermined value.

Preferably, the thickness calculating means calculates a humidity characteristic coefficient h0 of the resistivity ρ0 of the gas to be treated and a humidity characteristic coefficient h1 of the resistivity ρ1 of the dust corresponding to the output Hp from the humidity detecting means. First and second to operate
Calculating means, and third and fourth calculating means for calculating a temperature characteristic coefficient t0 of the resistivity ρ0 of the gas to be treated and a temperature characteristic coefficient t1 of the resistivity ρ1 of the dust corresponding to the output Tp from the temperature detecting means. Gas resistivity output means for outputting a signal representing the resistivity of the gas to be treated at a predetermined reference temperature and a predetermined reference humidity; and outputting a signal representing the resistivity of the dust at the reference temperature and the reference humidity. And a calculating means. The calculating means comprises: a voltage Vp and a current Ip of the dust collecting portion electrode; and a resistivity ρ0 of the gas to be treated and a resistivity ρ of the dust calculated by the first to fourth calculating means.
1, the temperature characteristic coefficients t0 and t1 of the resistivity ρ0 of the gas to be treated and the resistivity ρ1 of the dust, and the resistivity of the gas to be treated at the reference temperature and the reference humidity. ρ0c and the resistivity ρ1c of the dust at the reference temperature and the reference humidity.
A predetermined area S of the electrode, a voltage V from the voltage generating means, a leakage current i detected by the leakage current detecting means, and a predetermined interval d0 between the currents. Thickness d1 of dust adhering to

[0014]

(Equation 3)

Is calculated. Thereby, the resistivity ρ0 of the gas to be treated and the resistivity ρ1 of the dust adhering to the electrode, which change depending on the temperature and humidity of the gas to be treated, are calculated, and the two resistivity ρ0, ρ1 and the voltage V between the electrodes are calculated. From the change in the leakage current i, the thickness d1 of the dust adhering to the dust collecting portion electrode can be detected.

[0016]

FIG. 1 is a block diagram showing the entire electric configuration of a cleaning time detecting means of an electric dust collector according to one embodiment of the present invention. The cleaning time detecting means is provided in the control device of the electric precipitator shown in FIG. 2, detects a cleaning time at which dust adhering to a dust collecting section electrode (see FIG. 4) described later is removed with water or the like, and performs cleaning. It is for requesting.

As shown in FIG. 3, the electric precipitator is disposed in the electric precipitator tunnel 2 communicating with the side wall of the roadway tunnel 1 as indicated by reference numeral 3.
A blower 17 and a control device 10 are provided in the dust collector tunnel 2, whereby the gas to be treated in the roadway tunnel 1 is bypassed to the tunnel 2, thereby forming a vertical flow ventilation system. Thereby, the purified gas from which dust in the air has been removed can be blown out into the space of the roadway tunnel 1. This also allows the roadway tunnel 1
The line of sight within can be improved. A temperature detecting means 21 and a humidity detecting means 72 are provided upstream of the electric dust collector 3 in the roadway tunnel 1 or the dust collector tunnel 2.

The electric precipitator 3 comprises a charging section 4 and a precipitating section 5, as shown in the plan view of FIG. FIG. 5 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, which is a discharge line, is connected to the line 9, and the control device 1
A positive voltage from 0 is applied and supplied. 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 disposed downstream of the charging section 4. As shown in FIG. 6, the dust collecting portion 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. Thus,
When the air containing the dust flows between the electrodes 6 and 7 of the charging unit 4, the dust is charged by corona discharge,
The charged dust adheres to the electrodes 13 and 14 of the dust collecting unit 5 by electrostatic force and is collected.

The leakage 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 and humidity of the air flowing through the dust collector tunnel 2 are detected by the temperature detecting means 21 and the humidity detecting means 72.

FIG. 7 is a cross-sectional view showing a simplified configuration of the dust collecting section 5 viewed from a horizontal plane. The gas to be treated is
The amount of the gas flowing through the dust collector 3 is adjusted by the flow rate control damper 91, and the amount of the dust is passed through the dust collector 3. The gas to be treated is
The dust contained in the gas to be treated is charged by the charging unit 3, and the charged particles are collected by the dust collection unit 5, and are discharged as a clean gas. Dust adheres to the electrodes 13 and 14 by electrostatic force. When cleaning of the electrode is requested by the cleaning request unit 73, pressurized water is sprayed from a water cleaning unit 79 automatically realized by a nozzle or the like by, for example, an electromagnetic valve or the like, and the electrode is washed with water. Collected and removed. Wastewater containing dust is collected at the bottom of the dust collector and discharged.

Referring back to FIG. FIG. 2 is a block diagram showing the overall electrical configuration of the control device 10 of the electric dust collector 3. For the charging unit 4 of the electrostatic precipitator 3, a charging unit control circuit 22, a spark control circuit 23, and a DC voltage generation circuit 24 are provided. Similarly, for the dust collecting section 5, a dust collecting section control circuit 22a and a spark control circuit 23a
, DC voltage generating circuit 24a, and cleaning time detecting means 71
And are provided. The output of the temperature detecting means 21 is given to the control circuit 22 for the charging section and the cleaning timing detecting means 71, respectively. The output of the humidity detecting means 72 is given to the cleaning timing detecting means 71. The output of the ammeter 11 of the charging section 4 is supplied to the charging section control circuit 22 and to 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 ammeter 1 in the dust collecting section 5
The output of 9 is supplied to the dust collector control circuit 22a and to the spark control circuit 23a via the line 25. The output of the voltmeter 20 of the dust collecting section 5 is provided to the dust collecting section control circuit 22a. Each of the components 23a and 24a related to the dust collecting unit 5 has the same configuration as each of the components 23 and 24 for the charging unit 4. The output of the cleaning timing detecting means 71 is provided to the cleaning device 73.

FIG. 8 is an equivalent circuit diagram of the dust collecting portion electrode.
Although the dust collecting portion electrodes 13 and 14 are composed of a large number of parallel flat plates, it is equivalently considered to be a pair of such parallel flat plates. The leakage current i flowing when a DC voltage V is applied to the electrodes 13 and 14 in a state where the dust 93 adheres to the electrode 14 which is one of the parallel plate electrodes is expressed by the following equation from Ohm's law. Is done.

[0024]

(Equation 4)

At this time, S is the electrode area, d0 is the electrode interval, d1 is the thickness of the dust adhered to the electrode 14, ρ0 is the resistivity of the gas to be treated, and ρ1 is the resistivity of the adhered dust.

From the above formula, the thickness d of the dust adhering to the electrode 14
It can be seen that 1 is obtained by the following equation.

[0027]

(Equation 5)

The electrode area S and the electrode interval d0 are constants determined in advance by the shape and size of the electrode. The resistivity ρ0 of the gas to be treated and the resistivity ρ1 of the adhering dust have characteristics as shown by reference numerals 94 and 95 in FIG. 9 that increase as the temperature rises. Further, the resistivity ρ0 of the gas to be treated and the resistivity ρ1 of the attached dust have characteristics as shown by reference numerals 96 and 97 in FIG. 10, which decrease in inverse proportion to the humidity. Furthermore, the characteristic of the resistivity ρ0 of the gas to be processed changes depending on the composition of the gas to be processed.
By these characteristics, the resistivity ρ0 of the gas to be treated and the resistivity ρ1 of the attached dust can be expressed by the following equations.

Ρ0 = h0 · t0 · ρ0c (3) ρ1 = h1 · t1 · ρ1c (4) At this time, h0 is a coefficient obtained from the humidity characteristic of the gas to be treated, and as shown in FIG. Has a characteristic that h0 decreases in inverse proportion to the rise of the pressure, and h0 = 1 at the reference humidity. h1 is a coefficient obtained from the humidity characteristics of the attached dust. As shown in FIG. 12, h1 has a characteristic that when the humidity increases, h1 decreases in inverse proportion. When the humidity is the reference humidity, h1 = 1. Further, t0 is a coefficient obtained from the temperature characteristic of the gas to be treated, and as shown in FIG.
It has a characteristic that t0 increases in proportion to the rise in temperature, and t0 = 1 at the reference temperature. Furthermore,
t1 is a coefficient obtained from the temperature characteristics of the attached dust,
As shown in FIG. 4, t1 increases in proportion to the rise in temperature, and t1 = 1 at the reference temperature. Further, ρ0c is the resistance value of the gas to be treated at the reference temperature and the reference humidity, and ρ1c is the resistivity of the dust at the reference temperature and the reference humidity. Therefore, the thickness d1 of the dust adhering to the electrode depends on the temperature, humidity,
It can be seen that it corresponds to the voltage and current between 3 and 14.

Referring again to FIG. In the cleaning time detecting means 71 of the electric dust collector 3, the humidity Hp of the air detected by the humidity detecting means 72 is calculated by the first calculating means 74,
The second operation means 75 is provided. Further, the temperature Tp of the air detected by the temperature detecting means 21 is given to the third calculating means 76 and the fourth calculating means 77. The first calculation means 74 and the second calculation means 75 have the characteristics of the humidity and the humidity characteristic coefficient of the resistivity of gas or dust as shown in FIG. 11 or FIG. 12, respectively, as a memory table. Third operation means 76 or fourth operation means 7
Reference numeral 7 includes, as a table of a memory, characteristics of temperature and temperature characteristic coefficient of gas or dust resistivity as shown in FIG. 13 or FIG. 14, respectively. First calculation means 7
The humidity characteristic coefficient h0 of the gas resistivity output from the fourth, the third
The gas resistivity temperature characteristic coefficient t0 output from the calculating means 76 and the gas resistivity ρ0c output from the gas resistivity output means 80 are input to the gas resistivity calculating means 78. Similarly, the humidity characteristic coefficient h1 of the dust resistivity outputted from the second computing means 75, the temperature characteristic coefficient t1 of the dust resistivity outputted from the fourth computing means 77, and the dust outputted from the dust resistivity output means 81 The resistivity ρ1c is input to the dust resistivity calculation means 79. Gas resistivity output means 80
Alternatively, the dust resistivity output means 81 outputs the humidity 40
% And the resistivity ρ0c, ρ1c of the gas or dust in the reference state at a temperature of 20 ° C. are output to the gas resistivity calculating means 78 or the dust resistivity calculating means 79. The resistivity ρ0c, ρ1c of the gas to be processed or dust in the reference state may be set manually, or may be provided with a resistivity measuring means and set by measurement.

The gas resistivity calculation means 78 calculates the humidity characteristic coefficient h0 of the gas resistivity as shown in the above-mentioned equation (3).
Then, the resistivity ρ0 of the gas to be treated, which is the product of the temperature characteristic coefficient t0 of the gas resistivity and the gas resistivity ρ0c in the reference state, is obtained. Further, the dust resistivity calculating means 79 calculates the humidity characteristic coefficient h1 of the dust resistivity as shown in the above equation (4).
Then, the resistivity ρ1 of the adhered dust, which is the product of the temperature characteristic coefficient t1 of the dust resistivity and the dust resistivity ρ1 in the reference state, is obtained. The resistivity ρ0 of the gas to be processed, which is the output from the gas resistivity computing means 78, and the resistivity ρ1 of the attached dust, which is the output from the dust resistivity computing means 79, are given to the computing means. The calculating means 82 includes an electrode area setting means 83
, The electrode area S, the electrode interval d0 from the electrode interval setting means 84, and the voltage Vp and the current Ip between the electrodes of the dust collector via the lines 85 and 86 from the dust collector control circuit 22a. Electrode area S and electrode spacing d0
Can be manually set in the electrode area setting means 83 and the electrode interval setting means 84, respectively.

The calculating means 82 calculates the resistivity ρ of the gas to be treated.
0, attached dust resistivity ρ1, electrode area S, electrode interval d0,
Using the voltage Vp between the dust collecting portion electrodes and the current Ip, the calculation according to the above equation (2) is performed to obtain the thickness d1 of the attached dust. The level discriminating means 87 responds to the thickness d1 of the adhering dust which is the output of the calculating means 82, compares the thickness d1 of the adhering dust with the maximum allowable adhering dust thickness dmax, and obtains d1 ≧ dmax (5) If there is, a signal is output to the cleaning device 73 to perform cleaning. The allowable maximum adhering dust thickness dmax can be manually set by the allowable maximum adhering dust thickness setting means 88.

FIG. 15 is a block diagram showing an electrical configuration of the charging section control circuit 22 of FIG. In the charging section control circuit 22, a signal representing the temperature Tp of the air detected by the temperature detecting means 21 is given to the calculating means 27,
Further, an output via the filter 28 is given from the voltage Vp between the electrodes 6 and 7 detected by the voltmeter 12. Filter 28 serves to eliminate unwanted fluctuations in the output of voltmeter 12. The calculating means 27 has, as a memory table, the characteristics shown in FIG. 16 of the applied voltage between the electrodes 6 and 7 and the allowable maximum discharge current I1 using the detected temperature Tp of air as a parameter. 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. The line 30 is compared with the line 29 of the characteristic of FIG.
Are characteristics when the air temperature Tp is high. The allowable maximum discharge current I1 is a maximum current at which 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 provided 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 (6) The determination circuit 33 responds to the output Eg of the subtraction circuit 31, and if Eg> 0 (7), the voltage is applied 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.

[0036]

(Equation 6)

If Eg ≦ 0 (9), 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 (10), and the applied voltage V is Hold.

[0038]

(Equation 7)

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 relationship between the currents I1 and Ip.

The output of the judging circuit 33 is supplied to the starting voltage control signal generating means 35, and the voltage V applied between the electrodes 6 and 7 is
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 equation 8, and thereafter, the time rate of change is set to zero as shown by equation (10). Similarly, from time t2 and t3, the time rate of change Kg , The applied 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 section 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.

As shown in FIG. 18, the calculating means 44 controls the charging unit 4 using the temperature of air represented by a signal via the common contact 41 of the changeover switch 38 as a parameter.
Have the characteristics of the applied voltage Vb and the discharge current I2 as a table of the memory. At the time of 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 set reference temperature Tb and the set voltage V
b, a signal representing the set discharge current I2 in the charging unit 4 is derived and supplied to the subtraction circuit 48. Compared with the characteristic of the line 49 in FIG. 18, 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 is less than the allowable maximum discharge current described in connection with FIG. 16 and has an approximate value. 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 subtraction 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 (11) 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 (12) 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.

The 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 at 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 (13), the switch 58 is turned on, the switch 59 is turned off, and if Vs ≧ Vb1 (14), 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 increases, and as a result, the current Ip detected by the ammeter 11 increases, and the voltage Ib corresponding to the reference temperature Tb increases. 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.

FIG. 19 is a block diagram showing an electrical configuration of the dust collecting section control circuit 22a for the dust collecting section 5 of the electric dust collector 3. As shown in FIG. The control circuit 22 for the charging unit and the control circuit 22a for the dust collection unit have a similar configuration.

The calculating means 27a supplies the filter 2 based on the voltage Vp between the electrodes 13 and 14 detected by the voltmeter 20.
8a provides an output without unwanted fluctuations. The calculating means 27a determines that the allowable maximum leak current I1 increases with an increase in the applied voltage between the electrodes 13 and 14 and the allowable maximum leak current I1 indicated by the line indicated by the reference numeral 29a in FIG. The characteristics are provided as a memory table. Also, unlike the calculating means 27, the characteristics of the applied voltage and the allowable maximum leakage current I1 of the calculating means 27a are not affected by the air temperature.

The output of the operation means 27a is supplied to a subtraction circuit 31a
Given to. The leak current Ip between the electrodes 13 and 14 detected by the ammeter 11 is supplied to the subtraction circuit 31a without any undesired fluctuation by the filter 32a. The subtraction circuit 31a subtracts the detection current Ip detected by the ammeter 19 from the maximum permissible leakage current I1 calculated by the calculating means 27a as in the above-described equation (6), and obtains the difference Eg. Also,
The output Vp from the dust collector voltmeter 20 and the dust collector ammeter 19
Output from the filter 28a, 32a
And the cleaning timing detecting means 71 via the lines 85 and 86
Given to.

The decision circuit 33a responds to the output Eg of the subtraction circuit 31a and, as shown in the above equation (7), Eg> 0.
, The electrode 1 at the start-up shown by the above equation (8)
A signal representing a predetermined time rate of change Kg of the voltage V to be applied between 3 and 14 is output. Further, as shown in the above equation (9), if Eg ≦ 0, the electrodes 13 and
The time change rate of the voltage V to be applied during the period 14 is calculated by the above equation (1).
0) as shown by 0), and the applied voltage V is maintained. This time change rate Kg is calculated by the time change rate setting means 34a.
Can be manually adjusted and set. Also,
The subtraction circuit 31a may have only a function of comparing and detecting the magnitude relation between the currents I1 and Ip.

The output of the judging circuit 33a is supplied to a starting voltage control signal generating means 35a, and a voltage control signal representing a voltage Vs applied between the electrodes 13 and 14 is derived on a line 36a.

FIG. 21 shows the starting voltage control signal generating means 35.
FIG. 7 is a diagram showing a time lapse of an applied voltage Vs represented by a voltage control signal derived from FIG. From time t1, the applied voltage is increased at the time rate of change represented by the above equation (8), and thereafter, the time rate of change is set to 0 as shown by the equation (10). By such an operation, the applied voltage between the electrodes 13 and 14 increases with time.

The switching circuit 57a is supplied with a set voltage Vb from the applied voltage setting means 45a via a line 46a and a signal representing the applied voltage Vs from a starting voltage control signal generating means 35a via a line 36a. The switching circuit 57a responds to the output of the applied voltage setting means 45a and the output of the starting voltage control signal generating means 35a. If Vs <Vb (15), the switch 58a is turned on and the switch 59a is turned off. When Vs ≧ Vb (16), the switch 58a is turned off, and the switch 59 is turned off.
a is conducted. As a result, until the applied voltage Vs at the time of starting 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 the applied voltage Vs is set. When the voltage reaches the voltage Vb, the switches 58a and 59a are switched, and a voltage control signal representing the applied voltage Vb during the steady operation is supplied to the spark control circuit 23a via the line 64a. Thereby, at the time of starting, the output from the starting voltage control signal generating means 35a is input to the spark control circuit 23a, and when the starting is completed, the applied voltage setting means 45a
Is input to the spark control circuit 23a. Also,
The spark control circuit 23a and the DC voltage generator 24a
The spark control circuit 23 and the DC voltage generator 24 shown in FIG.
The same operation as described above is performed to control the voltage applied between the electrodes 13 and 14 of the dust collecting section 5.

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. 22 is a waveform chart for explaining the operation of the spark control circuit 23. The applied voltage V0 represented by the voltage control signal applied to the spark control circuit 23 via the line 61
Is an applied voltage V0a represented by a virtual line in FIG. 22 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. 22 are as described with reference to FIG. 17 described above, and the applied voltage Vs increases with time at startup. At time t3a, the applied voltage Vs for start-up
Switch means 57 after the start-up operation is completed by
The voltage control signal for the steady operation representing the applied voltage Vb1 is transmitted via the line 61 to the spark control circuit 23
Given to.

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 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 the time t12, the charging unit 3 sets the time t1 at about 5 to 10 minutes after the time t12.
In 3, at time t13, the spark control circuit 23 derives a signal instructing that water cleaning should be performed by injecting pressurized water to the electrodes 6, 7 of the electrostatic precipitator 3, and the water cleaning means performs water cleaning. Do. After this water washing or after the water washing requested by the above-mentioned washing requesting means 71, the starting operation for dust collection after the above-mentioned time t1 is repeated again.

In the charging section 3, the changeover switch 38
When the common contact 41 is switched to the individual contact 40 and turned on,
The calculation means 44 derives 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, and this discharge current I2 is calculated based on the air temperature Tp
, The variation of the applied voltage Vb1 is reduced. Thus, the constant voltage control is performed.

The electrodes 6 and 7 of the charging unit 4 during the 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 5-6 kV is selected.

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. The control device 10 may be realized by a microcomputer or the like.

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 used, for example, to remove dust from the inlet gas of a denitration device. The present invention may be practiced in other various technical fields.

[0064]

As described above, according to the present invention, there is provided a method for detecting a cleaning time of an electric precipitator in which a gas to be treated, which is a gas containing dust, flows between electrodes to which a voltage V from a voltage generating means is applied. A leak current i between the electrodes, a temperature Tp and a humidity Hp of the gas to be processed are detected, and a thickness d1 of dust adhering to the electrodes is calculated from the leak current i, the temperature Tp, and the humidity Hp. When the thickness d1 exceeds a predetermined value, it is determined that the cleaning time has come. In addition, a device for this purpose is provided with a leakage current i between the electrodes.
Current detection means for detecting the temperature Tp of the gas to be processed, humidity detection means for detecting the humidity Hp of the gas to be processed, the leak current detection means and the temperature detection means Responding to each output of the humidity detecting means, a thickness calculating means for calculating a thickness d1 of dust adhering on the electrode, and responding to an output from the thickness calculating means,
Level discriminating means for discriminating whether or not the thickness d1 of the dust obtained by the calculation is equal to or greater than a predetermined value. Also preferably, the thickness calculating means in the apparatus comprises a humidity characteristic coefficient h0 of the resistivity ρ0 of the gas to be treated and a humidity characteristic coefficient h1 of the resistivity ρ1 of the dust corresponding to the output Hp from the humidity detecting means. And a temperature characteristic coefficient t0 of the resistivity ρ0 of the gas to be processed and a temperature characteristic coefficient t1 of the resistivity ρ1 of the dust corresponding to the output Tp from the temperature detecting means. Third and fourth calculating means, and a gas resistivity output means for outputting a signal representing the resistivity ρ0c of the gas to be treated at a predetermined reference temperature and a predetermined reference humidity; and It includes a dust resistivity output unit that outputs a signal representing the dust resistivity ρ1c, and an arithmetic unit. The calculating means includes a voltage Vp of the dust collecting portion electrode, a current Ip, outputs h0, h1; t0, t1 of the first to fourth calculating means, and a resistivity ρ0c of the gas to be treated at the reference temperature and the reference humidity. And the resistivity ρ of the dust at the reference temperature and the reference humidity
1c, a predetermined area S of the electrode, a voltage V from the voltage generating means, a leak current i detected by the leak current detecting means, and a predetermined distance d between the currents.
Based on 0, the thickness d1 of the dust adhering to the electrode is calculated. Thus, the resistivity ρ0, ρ1 of the gas to be processed and dust adhering to the electrode, which change depending on the temperature and humidity of the gas to be processed, are calculated, and the two resistivity ρ
The thickness d1 of the dust adhering to the dust collecting portion electrode can be calculated from 0, ρ1, the change in the voltage V between the electrodes and the change in the leakage current i. Therefore, since the cleaning time can be accurately detected, the cleaning time is too early to stop the apparatus wastefully, or the cleaning time is too late to cause the attached dust to re-spread, thereby lowering the dust collection efficiency. Can be prevented. Further, since the present device does not require a dedicated power supply device and an electrode for detecting the cleaning time, the configurations of the cleaning time detecting device and the dust collecting unit can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall electrical configuration of a cleaning time detecting means of an electric dust collector according to one embodiment of the present invention.

FIG. 2 is a block diagram showing an overall electric configuration of the control device 10 of the electric dust collector.

FIG. 3 is a simplified horizontal cross-sectional view showing a configuration of a ventilation system for reusing air in a tunnel implemented in connection with the control device 10 of FIG. 2;

FIG. 4 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. 5 is a simplified front view showing a configuration of a charging unit 4 of the electrostatic precipitator 3;

FIG. 6 is a simplified front view showing a configuration of a dust collecting section 5 of the electric dust collector 3;

FIG. 7 is a simplified cross-sectional view showing a specific configuration of a dust collecting section 5 of the electric dust collector 3 as viewed from a horizontal plane.

FIG. 8 is an equivalent circuit diagram of the dust collecting portion electrodes 13 and 14 of the electric dust collector 3;

FIG. 9 is a graph showing the temperature characteristics of the resistivity of the gas to be treated and the attached dust.

FIG. 10 is a graph showing the humidity characteristics of the resistivity of the gas to be treated and the attached dust.

FIG. 11 is a graph showing humidity characteristics of a humidity characteristic coefficient h0 of gas resistivity.

FIG. 12 is a graph showing a humidity characteristic of a humidity characteristic coefficient h1 of the dust resistivity.

FIG. 13 is a graph showing a temperature characteristic of a temperature characteristic coefficient t0 of gas resistivity.

FIG. 14 is a graph showing a temperature characteristic of a temperature characteristic coefficient t1 of the dust resistivity.

15 is a block diagram showing an electrical configuration of a charging unit control circuit 22, a spark control circuit 23, and a DC voltage generation unit 24 of FIG.

FIG. 16 is a graph showing a relationship between an applied voltage Vp and a discharge current I1 for explaining the operation of the calculating means 27 shown in FIG.

FIG. 17 is a diagram showing a lapse of time of an applied voltage Vs at the time of activation in the charging unit 4.

FIG. 18 shows a calculating means 4 for steady operation in FIG.
4 and the discharge current I
2 is a graph showing the relationship of FIG.

FIG. 19 is a block diagram showing an electrical configuration of a dust collector control circuit 22a, a spark control circuit 23a, and a DC voltage generation unit 24a of FIG.

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

FIG. 21 is a diagram showing a lapse of time of an applied voltage Vs at the time of startup in the dust collecting section 5.

FIG. 22 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, 27a; 44; 82 Calculation means 31, 31a; 48 Subtraction calculation circuit 33, 33a Judgment means 35, 35a Start-up voltage control signal generation Means 38 Changeover switch 42 Reference temperature setting means 45, 45a Applied voltage setting means 52 Correction value calculation means 54, 60, 60a Addition circuit 57, 57a Switching circuit 71 Cleaning timing detection means 72 Humidity detection means 73 Cleaning device 74 First calculation means 75 second calculating means 76 third calculating means 77 fourth calculating means 78 gas resistivity calculating means 79 dust resistivity calculating means 80 gas resistivity output unit 81 dust resistivity output unit 83 the electrode area setting means 84 electrode spacing means 87 level discriminating means 88 the maximum permissible adhering dust thickness setting means

Claims (3)

(57) [Claims] 1. A method for detecting a cleaning time of an electrostatic precipitator in which a gas to be treated, which is a gas containing dust, flows between electrodes to which a voltage from a voltage generating means is applied. Detecting the temperature and humidity of the gas, calculating the thickness of the dust adhering to the electrode from the leakage current and the temperature and the humidity, and when the thickness becomes a predetermined value or more, the cleaning time has come. A method for detecting a cleaning time of an electric precipitator, characterized by making a judgment. 2. A cleaning time detecting device for an electrostatic precipitator in which a gas to be treated, which is a gas containing dust, flows between electrodes to which a voltage from a voltage generating means is applied, wherein a leakage current between the electrodes is detected. Detecting means, temperature detecting means for detecting the temperature of the gas to be processed, humidity detecting means for detecting the humidity of the gas to be processed, leak current detecting means, the temperature detecting means, and the humidity detecting means Thickness calculating means for calculating the thickness of the dust adhering on the electrode in response to each output; and wherein the thickness of the dust calculated and obtained in response to the output from the thickness calculating means is equal to or greater than a predetermined value. And a level discriminating means for discriminating whether or not the cleaning is performed. 3. The first calculating means for calculating a humidity characteristic coefficient h0 of the resistivity ρ0 of the gas to be processed corresponding to the output Hp from the humidity detecting means, A second calculating means for calculating a humidity characteristic coefficient h1 of the resistivity ρ1 of the dust corresponding to the output Hp; and a temperature characteristic coefficient t0 of the resistivity ρ0 of the gas to be processed corresponding to the output Tp from the temperature detecting means. A third calculating means for calculating; a fourth calculating means for calculating a temperature characteristic coefficient t1 of the resistivity ρ1 of the dust corresponding to the output Tp from the temperature detecting means; Gas resistivity output means for outputting a signal representing the resistivity ρ0c of the gas to be processed; and dust resistivity for outputting a signal representing the resistivity ρ1c of the dust at the reference temperature and the reference humidity. Output means; outputs h0, h1 of the first to fourth calculation means; t0, t1,
The resistivity ρ0c of the gas to be treated at the reference temperature and the reference humidity, the resistivity ρ1c of the dust at the reference temperature and the reference humidity, a predetermined area S of the electrode, and a voltage from the voltage generating means. V, a leakage current i detected by the leakage current detection means, and a predetermined distance d0 between the electrodes, and a thickness d1 of dust attached to the electrodes, 3. A calculation means for calculating
The cleaning time detecting device for an electric dust collector according to the above.