SU1618448A1 - Apparatus for automatic regulation of alternate voltage of electric precipitator - Google Patents

Abstract

The invention relates to electrical engineering, namely to power sources of electrostatic precipitators that trap high-resistance dust, and allows an increase in the degree of gas cleaning. The device for automatic control of alternating voltage of the electrostatic precipitator 1 contains a high-voltage source b with a thyristor regulator 9, two counter-parallel circuits consisting of valves 2, 3 connected in series and switches 4.5, current sensors 8 and voltage 20, a selector 19 spark gaps, a transient mode unit 13, a continuous mode control signal generator 12, an amplitude-Phase converter 11, a thyristor control generator 10, a block 14. overvoltage suppressors, the control unit 15, the output drivers 16, 17, and the switching control unit 18 of the driver 12, 3 or so on. k / ic

Description

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FIG. one

The invention relates to electrical engineering, namely to power sources of electrostatic precipitators (ESPs) that trap high impedance dust,

The purpose of the invention is to increase the degree of gas cleaning.

FIG. 1 shows a block diagram of a device for automatically controlling an alternating voltage of an electrostatic precipitator; in fig. 2 is a block diagram of a switching control unit of a driver and a driver of long-term control signals; in fig. 3 shows comparable in time diagrams of the operation of the switching unit of the imager.

The electrostatic precipitator 1 (Fig. 1) is connected through a chain of diodes 2 and 3 and switches 4 and 5 to a high voltage source 6 of alternating voltage. The high-voltage source 6 contains a step-up transformer 7, one output of the high-voltage winding of which is connected to the common point of diodes 2 and 3, and the other through the current sensor 8 to the common point of the circuit. The low-voltage winding of the transformer 7 is connected via a thyristor regulator 9 to the network inputs of the source 6. The control inputs of the thyristor controller 9 are connected via an impulse control driver of the thyristors 10 to the amplitude-phase converter 11, the first input of which is connected to the output of the control driver 12 signals of the continuous mode, the second input - with the output of the block 13 of the transient mode and with the output of the block 14 of the overvoltage limiting. The first and second inputs of the unit 14 are connected to the network input of the high-voltage source 6, the third and fourth inputs are connected to the first and second outputs of the control unit 15, respectively. The first and second outputs of control unit 15 are also connected via output drivers 16 and 17 of control pulses to the control inputs of switches 4 and 5, and the second output is also connected to the first input of the driver control switching unit 18 and the second driver input 12 of control signals long mode. The second input of the generator 18 switching control unit 18 is connected to the second output of the continuous mode control signal generator 12, the third input of which is connected to the output of the driver switching control unit, and the first input to the output of the selector switch 19, which is also connected to the input of the transition unit 13 mode. The first input of the selector 19 spark bits is connected to the output

voltage sensor 20 on the electrostatic precipitator; the second with the output of current sensor 8.

A continuous mode control signal generator 12 (FIG. 2) comprises

driver capacitors 21 and 22, one of the plates of each of which is connected to the common point of the circuit, and the others through the first 23 switching contact of the relay 24 to the common point of the series-connected

0 charge 25 and discharge 26 circuits with a lining of an additional capacitor 27 and the second input of the driver control switching unit 18. Through the second 28 switching contact of the relay 24 of the condensers 5, 22, is connected to the output of the control unit 18. The winding of the relay 24 is included in the collector circuit of the transistor switch 29, the base of which is connected to the second output of the block through a resistor divider 30

0 15 of the control (Fig. 1) and the first input of the control unit 18 by switching the former. The input of the charge circuit 25 of the capacitors 21, 22, 27 is connected to the first input of the driver 12 and means to the output of the selector 19 (Fig. 2) of the spark discharges, and the output of their discharge circuit 26 to the first output of the driver 12 and therefore to the first input amplitude-phase converter 11 (Fig. 2). First entry

0 of the driver control switching unit 18 (Fig. 2) is connected via the switch signal generator 31 to the clock inputs of D-flip-flops 32 and 33. The output of trigger 33 is connected via a resistor divider 34 to the base of the transistor switch 35, in whose collector circuit a winding of relay 36 is connected A switching contact 37 of which connects the output of control unit 18 to a common point of either resistors 38 and 39, or resistors 39 and 40 of a divider connected between a common point of the circuit and a device power source. The common point of the resistors 39 and 40 is also connected via a diode 41 to the transistor5 collector. key 42 and a resistor 43. The base of the transistor switch 42 through a resistor divider 44 is connected to the output of the trigger 32. The second input of the switching control control unit 18 is connected via

0 voltage follower 45 with inverted inputs of comparators 46 and 47 voltages, to the direct inputs of which constant voltages UonU U0n2 are applied. The outputs of the comparators 46 and 47 are connected to the inputs

5 inverter circuits 48 and 49, the output of the inverter circuit 48 is connected to the information input of the trigger 32, and the output of the circuit 49 to the information input of the trigger 33.

The device works as follows

The control unit 15 generates control pulses of the switches 4 and 5 operating in antiphase. Block 15 generates voltage pulses with the following parameters: the frequency of the f = 0.01-10 Hz, the duty cycle Q 2-5. Thus, the control unit 15 sets the alternating voltage switching mode on the electrostatic precipitator. The frequency and duty cycle of the pulses are set manually, based on the physicochemical properties of the dust and the technological parameters of the filter. The output pulses from the control unit 15 are fed to the formers 16 and 17 of the control pulses of the switches 4 and 5, providing the supply to the control inputs of the switches of rectangular voltage pulses of a given value. When switched on by the control unit 15 of the switch 4, as a result of the charge of the electrostatic condenser through the supply source 6 circuit - diode 2 - switch 4, a positive polarity is formed on the electrostatic precipitator. When the switch 5 is turned on via the power supply source 6 - diode 3 - the switch 5 on the electrostatic precipitator, a negative polarity voltage is formed. The high voltage source 6 of an alternating voltage maintains a pre-breakdown voltage on the electrostatic precipitator during a positive or negative half-wave of alternating voltage. For example, when operating an automatic voltage regulator similar to the regulator of the type of PRT, this is done as follows.

When voltage is applied to the electrostatic precipitator 1, spark discharges systematically occur in its active zone, accompanied by abrupt voltage drops on the filter electrodes and pulse current increases, which triggers the trigger of the 19 spark discharger. At the output of the selector 19 of the spark discharges, a voltage pulse appears, the shape of which repeats the shape of the abrupt voltage changes on the electrostatic precipitator. The output signals of the selector 19 of the spark bits affect the transient mode unit 13 and the continuous mode control signal generator 12. Shaper 12 sets the output signal, which is the dynamic voltage level, which determines the switching on angle of the thyristors of the controller 9 and, therefore, the average voltage level at the filter electrodes. In addition, in the driver 12, according to the signal from the output of the control unit 15, the alternating signal is switched by the switching capacitors 21 and 22 (Fig. 2), each of which is connected to a charge of 5 alternating 25 and one bit in one half-period of the alternating signal 26 chains and determines the unlocking angle of the thyristor of the regulator 9, and in the other it stores the level found in its working half-period, which determines the pre-breakdown voltage on the electric filter. The transient mode unit 13 acts on the amplitude-phase converter 11 in such a way that leads to the closure of the thyristor of the regulator 9, i.e. to relieve the voltage from the primary winding of the transformer 7 at each spark or arc breakdown in the electrostatic precipitator. The inputs of the overvoltage control unit 14 receive the network voltage and signals from the outputs of the control unit 15, and

0 output, a signal is generated which acts on the amplitude-phase converter 11 in such a way that it closes one of the thyristors of the regulator 9, i.e. to relieve primary tension

5 windings of the transformer 7 for the time of the negative half-wave of the mains voltage when a positive polarity is formed on the electrostatic precipitator and for the time of the positive half-wave when the negative polarity is formed. The amplitude-phase pro, the detector 11 determines in a dependent way, and on the amplitude of the signals from blocks 12-14, the moment when the control pulses are applied to the thyristors of the regulator 9 relative to the phase of the supply voltage.

The determination of the DC voltage level, to which it is necessary to connect the alternating voltage setting capacitor, which is not working in this half-period, and connecting the latter to this level, is carried out as follows.

Let us assume that at the instant on the electric filter a negative polarity of the operating voltage Uf (Fig. 3) is formed, while the output of the control unit 15 (Fig. 1) receives a pulse 112 (Fig. 3) to the second input of the control signal generator 1.2

0 continuous mode and to the first input of the switching control unit 18. This signal opens the transistor switch 29, a current flows through the winding of the relay 24. At the same time, the contact 23 of the relay 24 connects the driving capacitor 21 to the charge 25 and the discharge 26 circuits, and the contact 28 of the relay 24 connects the driving capacitor 22 to the benefit of the driver switching control unit 18. The voltage on the drive capacitor connected to

The charge 25 and the discharge circuit determines the unlocking angle of the thyristors of the regulator 9, therefore, the voltage across the electrostatic precipitator. Thus, in the considered half-period of alternating voltage on the electrostatic precipitator, the voltage on the master capacitor 21 determines the magnitude of the negative polarity voltage on the electrostatic precipitator and in this half-period changes, regulating the voltage on the electrostatic precipitator, and the voltage on the master capacitor 21 (Fig 3) in this half-period remains constant and is maintained by a signal from the output of the generator control unit 18, the voltage level maintained on the capacitor 22 corresponds to the voltage reached bent on an electrostatic precipitator during the formation of a positive polarity in the previous period of alternating voltage,

The device can memorize three levels Ui, i; Ui, 2, Ui, 3 of the voltage Ui on the electrostatic precipitator (Fig. 3), which correspond to the levels Us.i; U3.2; Because of the voltages U3, U4 (Fig. 3) on the drive capacitors 21 and 22, the Values Ui, 2, Ui, 3 are the most characteristic values of the levels of the pre-breakdown voltages on the electric filter npw for this gas and depend on the physicochemical the composition of the gas to be purified and the technological parameters of the filter, -Ui.i, correspond to the voltage level of the initial corona formation. The voltage 1) W, W is supplied from the common point of the resistors 38 and 39, Oz, 2 - from the common point of the resistors 39 and 40 with the open transistor 42, Pz.h - the common point of the resistors 39 and 40 with the closed transistor 42. The current of the first considered half-cycle of alternating voltage on the electrostatic precipitator is the voltage W (Fig. 3), on the reference capacitor 22 has a voltage level 113, 1. This means that in the previous half period, the voltage Ui on the electrostatic precipitator did not reach the value Ui, 2 (Fig. 3). At the same time, the contact 37 of the relay 36 connects the output of the control unit switching unit 1B to the common point of resistors 39 and 40 when the transistor 42 is closed, in this case the resistor 43 is connected via diode 41 parallel to the resistor 40. Let this position of the contact 37 of relay 36 correspond to the case when the relay coil 36 flows current, i.e. the open state of the transistor 35 or when a voltage pulse Ui has fallen on its base (Fig. 3).

To the second input of the switching control unit 18 of the shaper 12, the input voltage 1) 5 (Fig. 3) is sent from the additional capacitor 27 of the shaper 12 control signals of the continuous mode corresponding to the current value

operating voltage on the electrostatic precipitator. The signal U5 through the voltage follower 45 is fed to the inputs of the comparators 46 and 47, where it is compared: in one with the level Uoni proportional to the value 1) s, 2 and

0 therefore, the value of Ui, 2, and in the other - with the level of Uon2 proportional to 1) s, s and respectively Ui, 3. The signals U6, U7 (fig. 3) from the outputs of the comparators 46 and 47 (fig. 3) are converted in the circuits into signals 1) 8 and U9

5, respectively, and then go to the informational D-inputs of triggers 32 and 33. When the clock pulses U10 (Fig. 3) arrive from the output of the switching signal generator 31, the triggers 32 and 33 are set to the states corresponding to the signals at the D-inputs. The signals U8, U9 carry information about the range in which (.s; Ui ,, 3; UKUu) the current value of the voltage on the electric filter is located. The clock pulses U10 (Fig. 3) are short (fxy µs) pulses corresponding to the moments of switching the polarity of the alternating voltage. Since time is switch-

0 contact 23 of the relay 24 has a finite value greater than ph10 μs, then when the pulses U2 (Fig. 3) arrive from the control unit 15, the polarity switching over the duration of the pulses Uusigne5, U8, U9 carries information about the voltage on the electrostatic precipitator moment before switching alternating voltage. In so doing, the triggers 32 and 33 are set to the state U11, U12 {fig. 3) determining the output of the switching control unit 18 of the driver: the voltage levels to be fixed. The proposed device remembers the voltage level or equal,

5 or less than the current value of the voltage on the electrostatic precipitator. When this type of electrostatic precipitator is used to clean a certain gas, the level of operating voltages varies within 10–20%; therefore, it is sufficient to have two levels of memory.

Thus, the device allows the alternating power supply of the electrostatic precipitator to be carried out in any frequency and voltage control range. It

5 makes it possible to increase the degree of gas cleaning by increasing the average value of the voltage on the electrostatic precipitator when switching the alternating voltage of the alternating voltage, using a simple and reliable scheme for constructing the device.

Claims (1)

Invention Formula A device for automatic control of the alternating voltage of an electrostatic precipitator containing a high-voltage source with a thyristor regulator in the primary circuit connected to the electrostatic precipitator through two parallel-connected circuits, each of which consists of series-connected, respectively, first valve and first switch, the second valve and the second switch, the current sensor and the voltage sensor connected to the electrostatic precipitator, connected through a spark selector switch to the transient unit the mode and the first input of a continuous mode control signal generator containing the first and second master capacitors, one plate of which is connected to the common point of the circuit, and the other plate through the first switching contact-relay with the plate of the additional capacitor and common point of the series-connected charge and discharge circuits, while the outputs of the transient mode unit and the shaper mode control signal generator are connected via an amplitude-phase converter and a pulse shaper control The yields to laziness thyristors a thyristor controller, an overvoltage limiting unit, the first and second inputs of which are connected to the network inputs of the high-voltage source, and the output to the second input of the amplitude-phase converter, the control unit, whose outputs are connected via output control drivers to the control inputs, respectively, the first and second switches and directly the first output - with the third, and the second output - with the fourth input of the overvoltage suppressor unit and the second input of the control signal generator Long-term operation, characterized in that, in order to increase the degree of gas cleaning by increasing the average value of the operating voltage on the electrostatic precipitator when switching polarity, a device for controlling the switching of the former, the first and second inputs of which are connected respectively to the second output of the control unit and the second output of the shaper mode control signal generator, and the output through the second control switch input of the control signal shaper relay, th mode - with the first and second predetermined capacitors. ± n ti s 6 0 Ul 0 UB 0 U9 0 %one Un ° 0 tin 0 2f g -3