JPH0221298B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse charging type electrostatic precipitator.

A "pulse charging method" in which a periodic pulsed high voltage is applied instead of a direct current high voltage to the discharge electrode of an electrostatic precipitator, thereby improving its dust collection performance, is known per se. However, in all conventional methods, a pulsed high voltage is further superimposed and applied to the discharge electrode at a high DC potential, so a pulse transformer, a coupling capacitor, or both are connected between the output side of the high-voltage pulse power supply and the discharge electrode. In order to avoid direct connection between the high-voltage pulse power source and the discharge electrode by providing some kind of coupling interface that blocks the two in terms of direct current and allows the pulse voltage to freely transfer, the high-voltage pulse It was customary to prevent the high DC voltage from the discharge electrode from being applied to the output side of the power supply. However, as electrostatic precipitators become larger, the capacity of the coupling interface becomes extremely large, which not only significantly increases the cost, but also causes excessive power loss in that part. As a result, it has become extremely difficult to put the pulse charging method into practical use.

The present invention aims to solve this difficulty and to realize and supply an extremely inexpensive and highly efficient pulse charging type electrostatic precipitator.

Therefore, the present invention aims to increase the output pulse peak voltage of the high-voltage pulse power source to a large value corresponding to the maximum required peak voltage during pulse charging between the discharge electrode and the dust collecting electrode of the electrostatic precipitator to be pulse charged. This is achieved by directly connecting the output terminal of the high-voltage pulse power source to the discharge electrode and the dust collection electrode without using any coupling interface. However, the high-voltage pulse power supply generally consists of a capacitor for shaping the pulse voltage, its charging power source, and a high-voltage switch element for instantly connecting the charging voltage to the load, but as described above, the output terminal is connected to the discharge electrode and the When connecting between the dust collection electrodes, the charging power source is connected to the discharge electrode and the dust collection electrode after the high voltage switch element is turned on, and after applying a pulse high voltage due to instantaneous discharge of the capacitor, the charging A follow-on current from the power supply is supplied between the two electrodes, so that the voltage between the two electrodes is always subject to the DC charging voltage, and the pulse charging action is lost. In order to solve this problem, the present invention (1) uses an on-off type high voltage switch element that can immediately return to the OFF state after turning on as the high voltage switch element, and (2) uses the high voltage switch element as the high voltage switch element. After the ON operation, the output current from the charging power source is blocked during the conduction period until the OFF state is restored, and during that period, the charging of the pulse voltage shaping capacitor and the supply of follow-on current to both electrodes are prohibited. The charging power source is provided with a current blocking mechanism for blocking the output charging current and for restoring the supply of the output charging current during the non-conducting period after the high voltage switch element returns to the OFF state.
In this case, it is economical to make the capacitance Co of the pulse voltage forming capacitor as small as possible, but if it is too small, a sufficient output pulse peak voltage cannot be obtained. It is desirable that the capacitance Cd be approximately the same as the capacitance Cd between the dust collecting electrodes. The pulse charging operation obtained by constructing the high voltage pulse power supply as described above is as follows. First, the high-voltage switch element is turned on at a certain time point _t1 during which the current blocking function of the current blocking mechanism is operating. At that moment, the charging voltage Vo of the pulse voltage shaping capacitor is applied between the discharge electrode and the dust collection electrode, and the total inductance L consisting of the inductance and resistance of the connecting conductor and the inductance and resistance of the high voltage switch element itself, and the total Applied through resistor R. As a result, first of all,
A high-frequency transient vibration occurs in the Co-L-R-Cd series circuit, and the first peak voltage causes Fig. 1b.
As shown in the figure, a very short peak pulse high voltage Vp is instantaneously applied between the discharge electrode and the dust collection electrode, producing a uniform pulsed corona discharge over the entire discharge electrode,
A plasma containing significantly abundant positive and negative ions is formed. In the figure, the vertical axis υ _d represents the voltage between the two electrodes, and the horizontal axis t represents time. The peak voltage value Vp due to this transient oscillation is maximum when Co≫Cd and peaking occurs and becomes Vp = 2Vo - Vb, but decreases as Co approaches Cd and decreases when Co = Cd.
Become VpVo. This transient decays within a relatively short time, after which υ _d changes the initial voltage to V ₁ = Vo/(Co
+Cd), and CR slowly decays due to corona discharge. In other words, due to the DC electric field formed between the two electrodes, unipolar ions are extracted from the plasma in the recombination process and flow as an ion current to the collecting electrode, and along with this, the charges stored in Co and Cd are removed. It is consumed and the voltage υ _d between both electrodes decreases.
At a certain time point _t2 of this decay, the high-voltage switch element is turned off and Co is disconnected, and the decay of υ _d is caused only by the charge consumption of Cd, and its decay rate changes. At this time, as the voltage υ _d decreases, the ion current itself also decreases, and the subsequent decay rate has this effect. On the other hand, the voltage υ _c of the pulse voltage shaping capacitor maintains the value υ _d at time t ₂ until the next charging time t ₃ as shown in FIG. 1a. υ _d
If the attenuation continues until the next pulse voltage is applied, or if the plasma disappears at a point before that,
As υ _d decreases to a value below the DC corona starting voltage value, the ionic current disappears, which causes υ _d to
There may be cases where the attenuation of the signal stops. In any case, the value of υ _d reaches its lowest value Vb just before pulse charging.
The pulse voltage shaping capacitor releases the current blocking function of the current blocking mechanism at time _t3 after the high voltage switch element returns to OFF.
After being charged again to Vo, and then restoring the current blocking function of the current blocking mechanism at time _t4 prior to time _t1 , the high voltage switch element is turned on again at time _t1 to apply a pulsed high voltage to both electrodes. Then, repeat this operation.

Such initial high frequency transient vibration and subsequent
As a result of applying a periodic pulse high voltage as shown in Fig. 1b consisting of the CR damping section between the two electrodes, an average DC voltage Vdc as shown in the figure is applied between the two electrodes on average, and the above-mentioned The dust particles entering between the two electrodes are charged by the impact of the unipolar ion flow generated by the pulsed corona discharge, and the above Vdc
is driven to the collecting electrode by the average DC electric field of
Moreover, it is removed.

In this case, the higher the peak value of the pulse high voltage and the faster its rise, the more uniform and strong the pulse corona generated over the entire discharge electrode becomes. On the other hand, if the rise becomes excessive, the high voltage switch element may be damaged. Therefore, the above-mentioned initial high frequency vibration has an extremely important meaning for this pulse charging method.
In order to adjust its value and period, an appropriate value of inductance can be inserted in series with the high voltage switch element as required. In this case, an ideal current distribution is obtained when the rise time is several hundred ns or less, and in order to maintain uniformity of the current distribution, it is desirable that the rise time be 2 μs or less at the longest. In addition, when selecting an element such as a thyristor as the high-voltage switch element, which is turned off by applying a reverse voltage, the reverse voltage caused by the above-mentioned transient vibration automatically turns it on and then turns it off as required. Moreover, the initial peak voltage between the two electrodes can be made much larger than the charging voltage Vo of the pulse shaping capacitor.

That is, the novel pulse charging type electrostatic precipitator according to the present invention includes a main body casing, a dust-containing gas inlet, a clean gas outlet, and a dust outlet connected to the main body casing, and a grounding device arranged in the gas passage in the casing. A dust collecting electrode and a discharge electrode insulated opposite the dust collecting electrode are provided, and a high voltage power source is provided for applying a high voltage between the discharge electrode and the dust collecting electrode to cause the discharge electrode to cause corona discharge. In the electrostatic precipitator that the company owns, a capacitor for forming a pulse voltage with one end grounded as the high-voltage power supply, a high-voltage charging power supply connected to both ends of the capacitor to charge the capacitor, and a capacitor between the ungrounded terminal of the capacitor and the discharge electrode. A high-speed on/off method that connects the discharge electrode and the dust collecting electrode to periodically make them conductive for short periods of time, applies the charging voltage as a pulsed high voltage between the discharge electrode and the dust collection electrode, and immediately returns to the non-conductive state. A high-voltage pulse power supply consisting of a discharge high-voltage switch element having a function is used, and the high voltage is connected to the discharge electrode side terminal of the discharge high-voltage switch element and the ground side terminal of the pulse voltage shaping capacitor, respectively. The output terminals of the pulse power source are directly connected to the discharge electrode and the dust collection electrode without any coupling interface, and after the discharge high-voltage switch element is turned on, at least its off function is turned off. During the switch conduction period until recovery, the output current from the charging power source is blocked to prevent the charging current to the pulse voltage shaping capacitor and the generation of follow-on current to the discharge electrode, and to prevent the discharge from occurring. The charging power source is equipped with a current blocking mechanism that cancels the output current blocking function to enable charging of the pulse voltage shaping capacitor during the non-conducting period of the high voltage switch element. While operating the current blocking function of the current blocking mechanism, the discharge high voltage switch element is turned on and off to apply a pulsed high voltage between the discharge electrode and the dust collection electrode, and then the current blocking function of the current blocking mechanism is activated. is released to charge the pulse shaping capacitor, and thereafter the above operation is repeated periodically to periodically generate a pulsed corona discharge in the discharge electrode, thereby causing the supplied ions to charge the dust-containing gas. The dust particles that enter between the two electrodes along with the gas flow from the inlet are charged,
The present invention is characterized in that the dust is collected on the dust collecting pole by electric force and then peeled off and dropped downward to be discharged to the outside from the dust discharge port, and the clean gas is discharged to the outside from the clean gas outlet.

As a result of these features, the novel pulse charging type electrostatic precipitator according to the present invention can perform pulse charging without using an expensive and high power loss coupling interface between the pulse power source and the discharge electrode. This makes it possible to achieve the remarkable effect of making extremely inexpensive and highly efficient pulse charging possible.

The current blocking mechanism, which is the basis for realizing the above-mentioned features of the present invention, prevents the charging current from charging the capacitor and from subsequent current to the discharge electrode, at least during the conduction period of the high voltage switch element. In addition, any mechanism or element may be used as long as it enables sufficient charging of the capacitor from the charging power source during the non-conducting period, and a mechanism consisting of an appropriate circuit element, mechanical element, or a combination thereof. can be used. Also,
The high voltage switch elements for discharge to be used in the present invention include thyristors, power transistors, other solid state switch elements, thyratrons, hydrogen thyratrons, other discharge tube switch elements, spark gaps, spark gaps with trigger electrodes, and laser trigger type sparks. Mechanical switching elements such as gaps, rotary spark gaps, or any other suitable device may be used. Further, as the pulse forming capacitor to be used in the present invention, any type of capacitor such as an oil-immersed paper capacitor, a ceramic capacitor, a cable, etc. may be used, but a ceramic capacitor with low internal inductance is particularly suitable. Further, the charging power source to be used in the present invention may be of any type with a constant or variable output voltage, and methods for generating a variable voltage include adjusting the value of the input AC voltage using an induction voltage regulator, a saturable reactor, Alternatively, any method may be used, such as a method in which the voltage or current of the input AC is controlled by phase control using thyristors connected in antiparallel. In addition, the configuration of the charging power source is the secondary side (high voltage side) of the high voltage transformer.
There are those with a half-wave rectifier attached, those with a double-wave rectifier, those with a capacitor added to this, and those with an appropriate inductance inserted in series with the rectifier to change the charging voltage by resonant charging to the secondary voltage of the transformer. It is possible to use a system in which the charging voltage is raised higher than the peak value of , or a system in which the charging voltage is increased by a voltage doubler rectifier circuit or a several voltage doubler rectifier circuit. It goes without saying that the AC power source to be connected to the primary side of the transformer may be a commercial frequency power source, a non-commercial frequency power source configured by an inverter circuit, or a variable frequency power source.

Hereinafter, features of the present invention will be explained in more detail with reference to examples and drawings.

FIG. 2 shows an embodiment of the present invention, in which the above-mentioned current blocking mechanism was proposed by the present inventor in a separate application entitled "High Voltage Ultra-short Pulse Power Supply" (Japanese Patent Application No. 172797-1982).
FIG. 4 is a diagram showing an example of what can be realized by a combination of a rectifier and a synchronous rotating spark switch that rotates in synchronization with the alternating current frequency of the charging current. In the figure, 1 is an electrostatic precipitator, which includes a casing 2, a dust-containing gas inlet 3, a clean gas outlet 4, a dust hopper 5, a dust outlet 6, and a large number of grounding points vertically arranged in parallel at equal intervals in the gas flow direction. It has a dust collection electrode group 7, and a discharge electrode group 9 which is insulated and stretched over a metal frame 8 between them. Metal vertical columns 10 and 10' support the frame 8 via horizontal arms 11, are supported by insulator tubes 12 and 12' at their upper portions, and penetrate through the ceiling of the casing 2. 13 is a high voltage pulse power source which is a feature of the present invention, and its output terminals 14,
14' is directly connected to the upper end of the pillar 10 and the grounded dust collection electrode 11 via conductors 15 and 15', respectively;
The output pulse high voltage is applied to the discharge electrode 9 and the dust collection electrode 7.
It is designed to be applied directly between the two. 16 is a capacitor for high voltage pulse shaping, 17 is a high voltage transformer for charging, 18 is this primary winding (low voltage side), 19 is its secondary winding (high voltage side), and input terminal 2 of the primary winding.
0 and 20' are connected to any suitable AC power source, such as a commercial frequency AC power source or a non-commercial frequency or variable frequency AC power source such as an inverter. and output terminals 21, 2 of the secondary winding 19
1' is connected to the high voltage terminal 23 of the capacitor 16 via a rectifier 22, and 21' is connected to the ground terminal 23' of the capacitor 16. It is connected to the output terminals 14, 14' via 24'. however,
A synchronous rotating spark switch 30 consisting of fixed electrodes 25, 26 intervening in the conductor 24 and rotating electrodes 28, 29 which are driven by a synchronous motor 27 and are electrically connected to each other.
is provided, and the synchronous motor has a phase adjuster 3.
1 and conducting wires 32 and 32' to an AC power source on the primary winding side, and is configured to rotate at a rotation speed per second that is 1/2 of the frequency of the AC power source. Figure 3 shows the operation of the present high voltage pulse power supply. In the figure, the horizontal axis t indicates time;
The curve υ _c is the terminal voltage of capacitor 16, and the curve υ _a
indicates the secondary output voltage of the high voltage transformer, and the third
υ _d in figure b indicates the discharge electrode voltage. The voltage in each figure has negative polarity at the top. Now, when the secondary output voltage _{υ a} of the high voltage transformer 17 is in the rising period of negative polarity, the rectifier 2
2, the capacitor 16 is charged, and its voltage υ _c reaches the negative peak value Vo of υ _a , after which υ _c is maintained at Vo by the current blocking action of the rectifier 22. Then, at a suitable time t ₁ in the half cycle when the polarity of υ _a is positively reversed, the rotating electrodes 28 and 29 of the synchronous rotary spark switch 30 switch to the fixed electrodes 25 and 26.
By adjusting the phase adjuster 31 so as to generate a spark close to the output terminals 14, 14',
A voltage is instantaneously applied between the discharge electrode 9 and the dust collecting electrode 7 via the conducting wires 15, 15'. As a result, due to the mechanism described in detail, there is a gap between the two electrodes as shown in Figures 1 and 3b.
As shown in υ _d , a voltage with a peak value Vp appears, which is the superimposition of the pulse voltage on the DC average voltage Vdc. However, in this case, the blocking action of the rectifier 22 completely blocks the follow-on current from the charging power source. Immediately after the spark is generated, the rotating electrodes 28, 29 of the synchronous rotating spark switch 30 are replaced with the fixed electrodes 25, 26 to 26, 2.
5, the discharge between them disappears, and the switch 30 returns to its off state at time _t2 . That is, in this way, the blocking action of the rectifier 22 is combined with the synchronization and phase selectivity of the switching action of the synchronous rotary spark switch and the mechanical switch-off function to ensure that the capacitor is charged during the polarity reversal half cycle of the AC voltage. The feature of this embodiment is that the switch is selectively operated to prevent the occurrence of follow-on current. A current blocking mechanism is realized. After time t ₂ , υ _c keeps a constant value, and the polarity of the charging AC voltage reverses to negative again, and from time t ₃ , when this constant value is exceeded, the capacitor 16 is charged again, and the voltage υ _c reaches Vo. but,
The discharge electrode voltage υ _d continues to attenuate during this period, and at the next time t ₁
Then, the synchronous rotary spark switch rotates half a turn again to generate a pulse voltage due to spark generation, and this operation is repeated thereafter. As a result, the discharge electrode 9 performs a pulsed corona discharge, and the dust entering from the gas inlet 3 is charged and collected by the dust collection electrode 7 by the mechanism already detailed, and the clean gas is stacked from the gas outlet 4. is discharged to. Further, by mechanically hammering the dust collecting electrode 7, the accumulated dust on the collecting electrode 7 is peeled off, falls to the hopper 5 below, is collected, and is discharged to the outside from the dust outlet 6. In this case, it is generally economical to make the capacitance Co of the capacitor 16 approximately equal to the interelectrode capacitance Cd. In addition, by inserting an inductance or resistance of an appropriate low value in the middle of the circuit from the capacitor 16 to both electrodes, it is possible to prevent surges from entering the pulse power supply when sparks are closed between the two electrodes, and to prevent transient vibrations at the initial stage of the pulse voltage. The period can be adjusted, but generally if it is set to 2 microseconds or less, a uniform pulse corona is generated over the entire discharge electrode, and the ion current density on the dust collection electrode becomes uniform. Also, when the capacitor charging voltage Vo is increased, the instantaneous peak voltage Vp applied to the discharge electrode 9
increases, but as a result, the plasma density of the pulsed corona increases, the corona current increases, the decay rate of υ _d increases, and the value of the average DC voltage Vdc of the discharge electrode tends to decrease. Therefore, when the electrical resistance of dust is extremely high and there is a risk of generating a severe reverse corona, the capacitor charging voltage should be adjusted.
It is better to lower Vo to suppress the corona current value and increase the Vdc value. Furthermore, when the dust electrical resistance is not very high and the reverse corona is mild, it is better to set Vo relatively high to increase the corona current and increase the dust charging speed. Vo is adjusted by changing the voltage of the AC power supply on the primary side of the high-voltage transformer 17, but any suitable known means such as an induced voltage regulator or control of the primary current using a thyristor may be used for this purpose. I can do it. In addition, the degree of reverse ionization can be detected using an appropriate sensor or method such as a positive ion sensor, antenna, frequency of spark generation, voltage-current characteristics, etc., and thereby the primary AC voltage can be automatically controlled appropriately. .
In some cases, the primary AC power source may be configured with an inverter or the like to set a frequency different from the commercial frequency, or may be made variable, so that the frequency of the pulse power source may be set to a value other than the commercial frequency or may be made variable. I can do it. Therefore, control of the ion current can also be achieved by automatically or manually controlling this frequency. Further, the rotating electrodes of the rotary spark switch 30 do not necessarily have to be two poles, but may be four poles, six poles, eight poles, etc. (generally an even number of poles) depending on the case.
7 rotation speed can be reduced to 1/2, 1/3, 1/4, etc. Also, even in the case of two poles, the synchronous motor 2
By lowering the rotation speed of 7 to 1/2, 1/3, 1/4, ..., the frequency of the output pulse voltage can be changed to 1/2, 1/3, 1/4, etc.
It is possible to switch to...

FIG. 4 shows a thyristor switch 3 in place of the synchronous rotary spark switch 30 in the embodiment of FIG.
3, which also utilizes the method proposed by the present inventor in the above-mentioned separate invention. The names and functions of the elements numbered from 1 to 24 and 24' in the figure are the same as those of the elements with the same numbers in Figure 2, and 34 is an arbitrary voltage for adjusting the magnitude of the primary AC voltage. The adjustment device is shown. The thyristor switch 33 includes a turn-on circuit 37 for supplying a control current to the thyristor element 35 and its gate 36, and a turn-on circuit 37 for supplying a reverse voltage to the thyristor element 35 to make its current zero and turn off its conduction. It consists of a turn-off circuit 38.

The operation of this pulse power supply is exactly the same as that of the embodiment shown in FIG.
After charging to the peak value Vo of the negative charging AC voltage via the AC voltage, a control current is supplied from the turn-on circuit 37 to the gate 36 at an appropriate time _t1 during the half cycle when the polarity of the AC voltage is reversed to positive. The thyristor element 35 is turned on, and the voltage of the capacitor 16 is applied between the discharge electrode 9 and the dust collection electrode 7 to apply a pulse voltage, and then the turn-off circuit is activated at time _t2 , and the thyristor element 35 is turned on. The element 35 is turned off and the conduction between the capacitor 16 and the discharge electrode 9 is interrupted. The following operations are the same as in the embodiment shown in FIG. 2, and the waveforms of υ _c , υ _a , and υ _d are also as shown in FIG. 3. However, in this case, in order to limit the rise of the current and protect the thyristor element 35, a small inductance 39 and a resistor 40 are used.
is inserted in series in the circuit. Also, the switching speed is relatively slow, on the order of several microseconds, compared to the spark switch, which is on the order of several nanoseconds. In this case, as already mentioned, the initial L.
Since a reverse voltage is applied to the thyristor element 35 immediately after turn-on due to the C transient vibration, the turn-off circuit can be omitted when the duration thereof is longer than the turn-off time. Further, the thyristor element 35 may be controlled to turn on every two or several cycles of the AC charging voltage, thereby reducing the frequency of the pulse voltage to 1/2 or a fraction of the AC voltage frequency. , corona current can be reduced.

Figure 5 shows a system that utilizes the charging power source of a double-wave rectifier circuit, which is conventionally widely used as a power source for electrostatic precipitators, and also inserts an antiparallel-connected thyristor element on the primary side of a high-voltage transformer as a current blocking mechanism. An example of how the present invention can be implemented is shown below. The names and functions of the elements numbered 1 through 40 in the figure are the same as those of the elements numbered the same in the embodiment of FIG. However, in this example, the single wave rectifier 22 in FIG.
A bridge type double-wave rectifier 41 is connected instead of
The capacitor 16 is charged through this. Further, 42 and 43 are anti-parallel connected thyristor elements as a current blocking mechanism inserted in the circuit on the primary side of the high voltage transformer, and by supplying a control current from the control circuit 46 to the respective gates 44 and 45, 42 and 43 are turned on. Further, when a reverse voltage is applied to each element 42, 43 and the element current becomes zero, each element is turned off. Therefore, the thyristor element 4
A control current is sequentially supplied to the gates 2 and 43 at phase points t ₄ and t ₄ ' in the forward half wave of the primary AC voltage, and the phase at those points t ₄ and t ₄ ' (see Fig. 6A) is By changing , the peak value of the secondary voltage of the transformer 17, and therefore the charging voltage Vo of the pulse shaping capacitor 16, can be freely changed.
Unless the control current is applied to the gates 43 and 44, the primary current of the high voltage transformer is blocked, the secondary voltage does not appear, the capacitor 16 is not charged, and a follow-on current to the discharge electrode occurs. do not have. The operation of this embodiment is now shown in FIG. The dotted line υ _a ′ in the figure
is the virtual output voltage that should appear on the secondary side of the high voltage transformer 17 when the thyristor elements 42 and 43 are always in a conductive state. The positive aspect of exchange now
In the negative half cycles (1) and (2), 42 and 43 are sequentially turned on at times t ₄ and t ₄ ', which are delayed by a certain phase from the zero voltage point. At this time, due to the action of the double-wave rectifier 41, a negative voltage is applied to the capacitor 16 regardless of whether the AC secondary voltage is positive or negative, and the applied electromotive force becomes like a curve υ _r . Therefore, the capacitor 16 is charged by this electromotive force, and its terminal voltage becomes like the curve υ _c , and is first held at the peak value voltage Vo by the blocking action of the double-wave rectifier 41. Then, gate 4 is used for the next positive/negative half cycle of AC.
Unless the supply of control current to the capacitors 4 and 45 is stopped and the thyristor elements 42 and 43 are turned on, charging to the capacitor 16 is cut off during this rest cycle. Therefore, at an appropriate point during this pause cycle,
At time t ₁ , the thyristor switch element 35 is turned on to apply a pulse voltage to the discharge electrode 9 , and immediately thereafter at time t ₂ , the thyristor switch element 35 is turned off to break its conduction. During this time, a voltage as shown by the curve υ _d in Fig. 6 is applied to the discharge electrode, and the capacitor 16
Charging is started again at time _t4 , and this operation is repeated thereafter. In this manner, a pulse voltage having a frequency of 1/2 of the AC power frequency is applied to the discharge electrode 9, and pulse charging is performed.

FIG. 7 shows another example in which the present invention can be carried out by utilizing the existing double-wave rectification power source of the electrostatic precipitator as the charging power source. The names and functions of the elements numbered 1 to 46 in the figure are are the same as those of the elements with the same numbers in FIGS. 4 and 5. In the figure, there is a sufficiently larger capacitance between the double-wave rectifier 41 and the pulse voltage shaping capacitor 16.
A tank capacitor 48 having Ct is inserted in parallel with 16, and a thyristor element 50 as a current blocking mechanism of the present invention is interposed between the high voltage terminals 23 and 49 of both capacitors, and its gate is for discharging. A separate control current is supplied from a control circuit 37 that controls the thyristor element 35 as a high voltage switch element. The operation of this embodiment is now shown in FIG. The tank capacitor 48 is charged to a negative DC voltage Vo' by the charging power source, and its value can be freely changed by controlling the gates of the anti-parallel thyristor elements 42 and 43 on the primary side. Next, first, when the thyristor element 50 is turned on at time _t5 , the voltage of the capacitor 48 is applied to the pulse shaping capacitor 16 via the resonant inductance 52 and the thyristor element 50, and the terminal voltage υ _c of 16 is Due to transient oscillation between the capacitance Co and the inductance 52 and the capacitance Ct of the tank capacitor 48, it is charged to a negative voltage value Vo close to twice Vo',
Immediately after that, the reverse voltage is applied to the thyristor element 50 and it is turned off, so that υ _c is held at Vo. Next, at time _t1 , when the thyristor element 35 as a high-voltage switch element for discharging is turned on, a pulse voltage as shown by the curve _υd in FIG. 8 is applied to the discharge electrode, and pulse charging is performed. At this time, the thyristor element 5 as a current blocking mechanism
Since 0 has already been turned off, the generation of follow-on current is completely prevented. Immediately thereafter, at time _t2 , the discharge high-voltage thyristor element 35 is turned off by the operation of the turn-off circuit 38, and the conduction between the capacitor 16 and the discharge electrode 7 is cut off. Then, at the next time point _t5 , charging of the capacitor 16 starts again, and this operation is repeated thereafter.
In this embodiment, one cycle of t ₅ - _{t 1} - t ₂ - _{t 5} can be freely selected regardless of the frequency of the AC power supply, so the frequency of the output pulse voltage can be freely controlled, and the peak voltage can be controlled by the thyristor. It can be freely adjusted by controlling the phase of gate signals 42 and 43. Figure 5
3 is a voltage divider inserted between the pulse power output terminals 14 and 14', and a sensor 54 connected to the voltage divider detects the voltage drop caused by the transition from a spark to an arc in the dust collecting electrode of the discharge electrode 9, and outputs the signal. is input to the control circuit 37 of the thyristor element to stop turning on the discharge thyristor element 35 to extinguish the arc, and then resume normal operation.

FIG. 9 shows the embodiment of FIG. 7, in which the capacitor 16 is charged by using rotary spark switches 30, 55, in which the rotating electrodes are connected so as to be orthogonal to each other, instead of the thyristor elements 35, 50. No cutting from, capacitor 16
By connecting to the discharge electrode 9 and disconnecting from this, the same operation as the embodiment shown in Fig. 7 is performed.The names and functions of the numbers 1 to 52 in the figure It is exactly the same as that of the elements with the same numbers in FIG. 7 and FIG. In this example, the rotary spark switch 55 serves as a current blocking mechanism; 56 and 57 are fixed electrodes of the rotary spark switch 55; 58 and 59 are rotating electrodes; This is a coupling device for synchronous rotation while maintaining the positional relationship as shown in FIG. In this case, the frequency of the output pulse voltage can be controlled by controlling the rotation speed of the variable speed motor 61 for driving the rotating electrode. Since the operation of this embodiment is self-evident, the explanation will be omitted. This method also allows the existing power supply for electrostatic precipitators to be used as is. In this example, the rotary spark switches 30 and 55 are coaxial,
It goes without saying that the respective rotating electrodes may be mounted on the same shaft at an electrical angle of 90°. Furthermore, when the load on the electrostatic precipitator is large, the tank capacitor 48 and the rotary spark switch 55 can be shared, and multiple combinations of pulse forming capacitors 16 and rotary spark switches can be connected to this for split charging. .

FIG. 10 shows an embodiment in which an inductance element 62 is used as the current blocking mechanism of the present invention in place of the rotary spark switch 55 in the embodiment of FIG.
This can also utilize the power source of an existing electrostatic precipitator. In this case, the rotary spark switch 30 driven by the variable speed motor 61 is turned on, and the charging voltage of the capacitor 16 is applied to the discharge electrode 9.
Even if both become electrically conductive due to a spark, charging of the capacitor 16 and generation of follow-on current are suppressed by the action of the inductance 62, and during this time, the fixed electrodes 25, 26 and the rotating electrodes 28, 29 of the rotary spark switch 30 are connected.
are separated, and the conduction between the capacitor 16 and the discharge electrode 9 is cut off. Then, until the spark switch 30 is turned on, the capacitor 16 is connected to the tank capacitor 48 via the inductance 61.
Once fully charged, repeat the above steps.
In this case, when an arc short circuit occurs between the discharge electrode and the dust collection electrode, a voltage drop signal due to this is transmitted to the voltage divider 53,
Control circuit 4 for anti-parallel thyristor elements 42 and 43 on the primary side of high voltage transformer 17 via sensor 54
6 and immediately blocks the primary current to extinguish the arc. Then, after the arc is extinguished, 42 and 43 resume conduction. Even in this embodiment, the value of the output pulse voltage is determined by the thyristor element 42,
The frequency can be controlled by controlling the phase of the gate 43 and the rotation speed of the electric motor 61.

FIG. 11 shows that instead of using one half-wave rectifier in the embodiments of FIGS. 2 and 4, a bridge-type double-wave rectifier is used in a divided form, and thereby This prevents biased magnetism from appearing in the iron core due to the flow of DC component current, and the names and functions of elements 1 to 46 in the figure are the same as the elements with the same numbers in Figures 2 to 5. It is. However, as shown in the figure, the bridge-connected double-wave rectifier 41' connected to the secondary side of the high-voltage transformer 17 is
One end 62 of the side not connected to the secondary winding 19 is grounded, and the other end is open and divided into 63, 63' to connect the two pulse voltage shaping capacitors 16,
16', and connected to high voltage side terminals 23, 23'' of the discharging high voltage switch elements 64, 64', each consisting of a synchronous rotating spark switch 30 or a thyristor element 35, etc., which have already been described in detail.
are connected to the output terminals 14, 14'' through the discharge electrodes 9, 14'' of the two electrostatic precipitator dust collection chambers 1, 1'.
9'. In addition, the ground terminals 23', 23'' of the pulse shaping capacitors 16, 16'
are connected to the dust collecting electrodes 7, 7' of the respective dust collecting chambers 1, 1' via output terminals 14', 14. By dividing and connecting the rectifier 41' as described above, the pulse voltage forming capacitor 1
6 and 16' are high voltage side terminals 23, 23'' is ground terminal 2
3', 23 are alternately charged negatively every negative half period of the output voltage of the high voltage transformer 17, and the charging voltage is applied to the anti-parallel thyristor elements 42, 4 on the primary side.
It can be freely adjusted by phase control of 3. Well, 1
6 is negatively charged, when turning on and off the high voltage switch element 64 in the next AC half cycle, only the dust collection chamber 1 is pulse charged, but the following current is generated by the rectifier 41'. This is prevented by the current blocking effect of the rectifying element connected in series with 16, and during this AC half cycle, high voltage switch element 64' is kept off and 16' is negatively charged. In the next AC half cycle, 16 is charged, but 64 is not turned on, and 1
Under the current blocking state of the rectifying element connected in series with 6', 64' is turned on and off, and only the dust collection chamber 1' is pulse-charged. In this way, 1 and 1' with the frequency of the AC voltage are pulse-charged alternately every half cycle of the AC voltage, but the primary winding 1 of the high voltage transformer 17 is
An alternating current flows through the iron core 8 to prevent eccentric magnetization of the iron core.

[Brief explanation of drawings]

FIG. 1 shows the working principle of pulse charging according to the invention. FIG. 2 shows an embodiment of the present invention, and FIG. 3 shows its operation. FIG. 4 shows another embodiment of the invention. FIG. 5 shows another embodiment of the invention, and FIG. 6 shows its operation. FIG. 7 shows another embodiment of the invention, and FIG. 8 shows its operation. 9, 10 and 11 each show another embodiment of the present invention. The names of the main elements in the diagram are as follows. 1, 1'... Electrostatic precipitator, 2... Upper casing, 3... Dust-containing gas inlet, 4... Clean gas outlet, 5... Hopper, 6... Dust outlet, 7,
7'... Dust collection electrode, 9,9'... Discharge electrode, 12,1
2'...Insulator tube, 13...High voltage pulse power supply, 14,
14', 14'', 14...upper output terminal, 15,
15', 24, 24', 32, 32'... Conductor, 1
6, 16'... Pulse shaping capacitor, 17
...high voltage transformer, 20, 20'... the upper primary side input terminal, 21, 21'... the upper secondary side output terminal,
22... Single wave rectifier, 25, 26, 56, 57...
... Fixed spark electrode, 27 ... Synchronous motor, 28,2
9,58,59...Rotating spark electrode, 30,55...
...Rotary spark switch, 31...Phase adjuster, 34
... Voltage regulator, 35, 42, 43, 50 ... Thyristor, 37, 46 ... Thyristor control circuit, 38 ... Thyristor turn-off circuit,
39,52,62...Inductance, 41,4
1'...Double wave rectifier, 48...tank capacitor, 53...voltage divider, 54...arc detector, 6
1...Electric motor, 64, 64'...High voltage switch element for discharge.

Claims (1)

[Scope of Claims] 1. A main body casing, a dust-containing gas inlet, a clean gas outlet, and a dust discharge port connected to the main body casing, a grounded dust collection electrode disposed in a gas passage in the casing, and a dust collection electrode facing thereto. It has an insulated discharge electrode,
In an electrostatic precipitator equipped with a high voltage power source for applying a high voltage between the discharge electrode and the dust collecting electrode to cause corona discharge to the discharge electrode, the high voltage power source is used for forming a pulse voltage with one end grounded. condenser,
In order to charge this, a high-voltage charging power supply is connected to both ends of the capacitor, and an intervening connection is made between the non-grounded terminal of the capacitor and the discharge electrode to periodically conduct short periods of time between the two, and the charging voltage is converted into a pulsed high voltage and then applied. A high-voltage pulse power source consisting of a high-voltage switch element for discharging, which is equipped with a high-speed on/off function to immediately return to a non-conducting state after being applied between the discharge electrode and the precipitate electrode, is used, and the discharge Connect the output terminals of the high voltage pulse power supply connected to the discharge electrode side terminal of the high voltage switch element and the ground side terminal of the pulse voltage forming capacitor, respectively, and connect some kind of coupling interface to the discharge electrode and the dust collection electrode, respectively. After the discharging high-voltage switch element is turned on, the output current from the charging power source is blocked during the switch conduction period until the off function is recovered, thereby forming a pulse voltage. In addition to preventing the generation of charging current to the pulse voltage shaping capacitor and subsequent current to the discharge electrode, the output current blocking function is canceled during the non-conducting period of the discharge high voltage switch element to prevent the pulse voltage shaping capacitor from flowing. The charging power source is equipped with a current blocking mechanism that enables charging, and while the current blocking function of the current blocking mechanism is activated, the high voltage switch element for discharging is turned on and off during the operation. A pulsed high voltage is applied between the discharge electrode and the dust collecting electrode, and then the current blocking function of the current blocking mechanism is released to charge the pulse forming capacitor, and the above operation is repeated periodically to collect the dust. A pulsed corona discharge is periodically generated at the discharge electrode, and the supplied ions charge the dust particles that enter between the two electrodes along with the gas flow from the dust-containing gas inlet, and the dust particles are collected by the electric force. A pulse charging type electrostatic precipitator characterized in that the dust is collected at the highest level, then separated and dropped downward to be discharged to the outside from the dust outlet, and clean gas is discharged to the outside from the clean gas outlet. 2. The charging power source is composed of a high voltage transformer that connects the primary side (low voltage side) to the AC power source and the rectifier on the secondary side (high voltage side), and the high voltage switch element for discharging is connected to the fixed electrode and the AC power source. A synchronous rotating spark switch is constructed of a rotating electrode that rotates in synchronization with the frequency of the fixed electrode. The distance between the rotating electrode and the rotating electrode is sufficient to prevent sparks from occurring between the two, and during the AC half-cycle section where the polarity is opposite to this, the distance between the two electrodes is sufficiently close to prevent a spark from occurring between the two. 2. The pulse charging type electrostatic precipitator according to claim 1, wherein the current blocking mechanism is realized by setting the rotational phase of the rotating electrode relative to the fixed electrode so as to generate . 3. The charging power source consists of a high-voltage transformer that connects the primary side (low-voltage side) to the AC power source and the rectifier on the secondary side (high-voltage side), and the high-voltage switch element for discharging consists of a thyristor switch element. , the thyristor switch element is kept in the OFF state without being turned on during an AC half-cycle period in which the polarity of the secondary voltage of the high voltage transformer is in the forward direction of the rectifier, and the polarity of the secondary voltage of the high voltage transformer is maintained in the OFF state without being turned on; According to claim 1, the current blocking mechanism is realized by controlling the supply phase of the signal supplied to the gate of the thyristor element so as to turn on the thyristor element during the AC half-cycle period. Pulse charging type electrostatic precipitator. 4. The charging power source consists of a high voltage transformer whose primary side (low voltage side) is connected to the AC power source via a thyristor element and a rectifier is connected to the secondary side (high voltage side), and the discharge high voltage switch element consists of a thyristor switch element, which is kept in the OFF state, during which time the primary thyristor element is turned on, the pulse voltage forming capacitor is charged, and then the primary thyristor element is turned OFF. Claim 1, characterized in that the current blocking mechanism is realized by controlling the gate signal supplied to each thyristor element so as to turn on the thyristor switch element during this period. The pulse charging type electrostatic precipitator described in . 5 The charging power source consists of a high voltage transformer whose primary side (low voltage side) is connected to the AC power source and where a tank capacitor is connected between the secondary side (high voltage side) terminals via a rectifier. One end is directly connected to the grounding end of the pulse voltage forming capacitor, and the other end of the tank capacitor is connected to the high voltage end of the pulse forming capacitor via a charging switch element as the current blocking mechanism, While keeping the high-voltage switch element in the OFF state, the charging switch element is turned ON to charge the pulse voltage forming capacitor, and then the charging switch element is turned OFF to maintain the OFF state. 2. The pulse charging type electrostatic precipitator according to claim 1, wherein the current blocking mechanism is realized using the charging switch element by turning on the discharging switch element. 6. Claims characterized in that both the discharging high-voltage switch element and the charging switch element are rotary spark switch elements having a fixed electrode and rotating electrodes that rotate in synchronization with each other. 5
The pulse charging type electrostatic precipitator described in . 7. The pulse charging type electrostatic precipitator according to claim 5, wherein both rotating electrode shafts of the rotating spark switch element are mechanically connected to each other. 8. The pulse charging type electrostatic precipitator according to claim 5, wherein both rotating electrodes of the rotary spark switch are mounted on a common rotating shaft. 9. The pulse charging type electrostatic precipitator according to claim 5, wherein both the high voltage switch element for discharging and the switch element for charging are thyristor elements. 10. The pulse charging type electrostatic precipitator according to claim 1, wherein the current blocking mechanism is an inductance element. 11 The rectifier is a bridge-connected double-wave rectifier, and the bridge connection is divided into two by opening the end that is not connected to the secondary side of the high-voltage transformer at one end;
connected to the high voltage terminals of separate pulse voltage forming capacitors, and the diagonal ends of the ends of the bridge-connected double-wave rectifier are connected to the ground terminals of each of the capacitors; The discharge electrodes of the dust collecting chamber of the electrostatic precipitator are connected to the discharge electrodes of the dust collecting chamber of the separate electrostatic precipitator via high-voltage switch elements for discharge, such that the terminals are turned on and off alternately every half cycle of the alternating voltage, and when the commutator strips connected thereto are turned on and off. The pulse charging type electrostatic precipitator according to claim 1, characterized in that the pulse charging type electrostatic precipitator is connected to.