SU1382493A1 - Apparatus for feeding electric precipitator with alternate voltage - Google Patents

Abstract

The invention is intended to power an electrostatic precipitator by alternating voltage and improves the gas cleaning efficiency by increasing the average voltage applied to the electrostatic electrodes. The device for supplying the electrostatic precipitator with alternating voltage contains two adjustable constant-voltage sources 3 and 5 connected via high-voltage switches 2 and 4 with electrodes of the electrostatic precipitator 1, voltage divider 15 connected to constant-voltage sources 3, 5 voltage and control unit 16, the outputs of which are connected to adjustable sources 3, 5 of constant voltage, and through output shapers 18, 19 pulses - are connected to control input high-voltage KONtMyTaTopoB, 4. 4 Il. S (l

Description

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The invention relates to electrical engineering, namely to power supplies of electrostatic precipitators that trap high-resistance dust.

The purpose of the invention is to increase the efficiency of gas cleaning by increasing the average voltage applied to the electro-filter electrodes.

FIG. 1 is a block diagram of a device for feeding an electrostatic precipitator by alternating voltage; in fig. 2 - time diagrams of the device; in fig. 3 is a block diagram of a voltage level sensor; in fig. 4- time diagrams of the voltage level sensor operation.

The electrostatic precipitator 1 through the switch 2 is connected to the positive pole of the high-wave adjustable source

3 constant voltage, and through the switch 4 - with the negative pole of the high voltage adjustable source 5 constant voltage. High-voltage adjustable constant voltage sources 3 and 5 containing high voltage step-up transformers 6 and 7, respectively. The high-voltage winding of the transformer 6 is connected to the bridge rectifier 8, the positive pole of which is connected to the anode of switch 2, and the negative through current sensor 9 is connected to the common point of the circuit. The high-voltage winding of the transformer 7 is connected to the bridge rectifier 10, the negative pole of which is connected to the cathode of the switch 4, and the positive one is connected via the current sensor 11 to the common point of the circuit. The low-voltage windings of transformers 6 and 7 are connected via thyristor controllers 12 and 13, respectively, to the network input of the source. The control inputs of the thyristor controller 12 are connected to the driver outputs

14 control pulses, the first input of which is connected to the output of the sensor

9 current, the second - with the sensor output

15, which is connected between the collecting and corona electrodes of the electrostatic precipitator 1, the third with the first output of the control unit 16. The control inputs of the thyristor controller 13 are connected to the outputs of the generator 17 of control pulses, the inputs of which are connected: the first to the output of current sensor 11, the second to the output of voltage divider 15, and

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the third is connected to the second output of control unit 16, the third output of which is connected via the output driver 18 of pulses to the control input of switch 2, the fourth through the output driver of 19 pulses to the control input of switch 4, and the fifth and sixth outputs to the third and the fourth inputs of the voltage level sensor.

The control unit 16 consists of a master oscillator 20, the output of which is connected to the counting input of the first trigger 21, the first output of which is connected to the first inputs of the first AND 22 circuit, first, the EXCLUSIVE OR 23 circuit, and through a differentiating device 24 to the first input of the second trigger 25. The second output of the trigger 21 is connected to the first inputs of the second circuit AND 26, the second circuit EXCLUSIVE OR 27 and through a differentiating device 28 to the first input of the third trigger 29, the output of which is connected to the fourth input of the voltage level sensor 30 and to the second and the inputs of EXCLUSIVE OR circuits 23 and 27, the third inputs of which are connected to the output of the second trigger 25 and to the third input of the voltage level sensor 30.

The first output of the control unit 16 is the output of the AND 22 circuit, the second is the output of the AND 26 circuit, the third is the output of the EXCLUSIVE OR circuit 23, which is connected to the first input of the AND 22 circuit, the fourth is the output of the EXCLUSIVE OR circuit 27, which is connected to the first input of the circuit And 26, fifth and sixth are the outputs of the 25 m 29 flip-flops, respectively.

The input of the control unit 16 is connected to the output of the voltage level sensor 30, the first input of which is connected to the voltage divider 15, the second to the source 31 of the reference voltage.

The voltage level sensor 30 (Fig. 3) consists of the OR circuit 32, the first input of which is connected to the fifth output of the control unit 16, and the second input to the output 6 of the control unit 16. The output of the OR circuit 32 is connected to the first input of the circuit AND 33, the second input of which is connected to the output of the comparison circuit 34, the first input of which is connected to the output of the voltage divider 15, and the second to the source 31 of the reference voltage. Output circuit 33

connected to the input of the control unit 16.

The device works as follows.

High voltage sources 3 and 5 maintain on the electrostatic precipitator 1 a pre-breakdown voltage during a positive or negative half-wave alternating voltage. The control unit 16 generates control pulses of switches 2 and 4 and power sources 3 and 5 so that when the device is turned on, unlocking signals are supplied, for example, to switch 2 and source 3. A positive voltage is generated on the electrostatic precipitator, and switch 4 and source 5 are locked. When switching the polarity of the voltage to the electro-filters, the source 3 is switched off first, and the switch 2, which connects it to the electrostatic precipitator, remains switched on for some time. When the voltage of the previous polarity on the electrostatic precipitator decreases to a certain minimum value, the signal from the voltage level sensor 30 switches off the operating switch 2, and switch 4 and the source 5 are turned on. A negative polarity voltage is formed on the electrostatic precipitator. Then everything happens as described.

The formation of control pulses is carried out as follows.

The counting input of the trigger 21 receives a signal and, (FIG. 2) from the output of the master oscillator 20 and sets the switching mode of alternating voltage on the electrostatic precipitator 1. The frequency and duty cycle of the switching are based on the physicochemical properties of dust and the technological parameters of the electrostatic precipitator 1. From the outputs the trigger 21 is removed by two antiphase signals and 2, U (Fig. 2), which are fed to the input of differentiating devices 24 and 28 and converted into 1/4 short pulses, and 5, which flip triggers 25 and 29 into the opposite state. At this point in time, corresponding to the moment of arrival of the signal from master oscillator 20, the power supply of the current polarity is turned off. The second inputs of the triggers 25 and 29 receive a signal and, corresponding to the moment of voltage decrease on the electrostatic precipitator to not

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which is the minimum level that is specified by the voltage of the setpoint LF o. The signal Uf, flips triggers 25 and 29 to the initial state. At this moment, the switch is turned off, which connected the source of the voltage of the previous polarity to the electrostatic precipitator, and the source of the voltage of the subsequent polarity turns on and connects its switch.

Thus, pulses U, are removed from the outputs of the flip-flops 25 and 29. U,, duration that determines the time ahead of the moment the power source is turned off relative to the moment the switch that connects it to the electrode is turned off. Next, the output pulses of the flip-flops 25 and 29 are fed to the inputs of circuits 23 and 27, performing the function EXCLUSIVE OR, the first inputs of which receive signals from the corresponding outputs of the trigger 21. From the output of the circuit 23, the signal Ug (Fig. 2) is turned on to turn on switch 2. This signal also arrives at the input of the AND circuit 22, to the other input of which the signal U is fed from the output of the trigger 21. At the same time, the output of the AND 22 circuit produces a signal U, j, to turn on the source 3 of positive polarity. Similarly, from the output of circuit 27, the signal U ,, is removed (Fig. 2) to turn on switch 4, from the output of circuit 26, to signal to turn on source 5 of negative polarity. In this case, rigidly synchronized control signals for switches and power sources are generated. The output pulses from the control unit 16 are fed to the formers 18 and 19 of the control pulses of the switches 2 and 4, ensuring that rectangular voltage pulses of a given magnitude are applied to the accelerating electrodes of the switches. For example, for a switch on an ELV 1/150 type valve, the pulse voltage amplitude is 2-4 kV at a current up to 30 mA. At the output of the source 3 of positive polarity, a voltage U ,, is formed at the output of the source 5 of negative polarity - U,, on the electrostatic precipitator - U,.

A voltage level sensor 30 (Fig. 1) captures a point in time when, after turning off any source (positive or negative polarity), the voltage on the electrostatic precipitator decreases to some degree

th minimum value. Since the electrostatic precipitator operates in the mode of constant electrical breakdowns and the voltage is controlled by the frequency of spark breakdowns, the voltage on the electrostatic precipitator during any half-period alternating sign voltage abruptly (with a front of ten milliseconds) drops almost to zero, and then after a pause of 2-3 half periods, the network voltage rises again to the breakdown value. In this case, it is necessary to distinguish between the decrease in voltage caused by the breakdown in the electrostatic precipitator and the decrease in voltage caused by the disconnection of the power source. The voltage level sensor 30 operates as follows.

Voltage. (Fig. 4), proportional to the voltage on the filter, is removed from the voltage divider 15, which is an ohmic divider, and is fed to the input of the comparison circuit. A signal appears at the output of the FOR circuit.

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(Fig. 4) at the time of voltage reduction on the electrostatic precipitator to a certain value, specified by applying to the second input of the voltage circuit 34

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OR 32 adds the signals u, t (Fig. 4) from the outputs of the flip-flops 25 and 29, the leading edge of which corresponds to the moment when the polarity of the voltage on the electrostatic collector begins the moment of switching off the high voltage regulated constant voltage source. The result of the addition of the signals U, enters the input of the AND 33 circuit. At the output

Circuits 33 appears pulses Ug, co-circuits EXCLUSIVE OR, respectively.

corresponding to the moment of voltage drop on the electrostatic precipitator to a certain value, which occurred when switching the polarity of alternating voltage,

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and the second inputs - with the first inputs of the first and the second circuits EXCLUSIVE OR, respectively, with the antiphase outputs of the first trigger and the inputs of the first and second differentiating devices, and the first inputs of the second and third triggers are connected to the outputs of the first and second differentiating devices, respectively.

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Claims (1)

Formula images A device for feeding an electrostatic precipitator by alternating voltage. ten about- , P 20 3824936 containing two adjustable high-voltage sources of different polarity, connected via high-voltage switches to electrodes of the electrostatic precipitator, voltage divider on the electrostatic precipitator connected to the second inputs of high-voltage sources, the first and second output formers of the pulses, the outputs of which are connected to the control inputs of the corresponding high-voltage switches, and a control unit comprising a master oscillator, the output of which is connected to the counting input of the first trigger, characterized in that To increase the gas cleaning efficiency by increasing the average voltage applied to the electrostatic precipitator electrodes, it additionally contains a voltage level sensor, a reference voltage source and two differentiating devices introduced into the control unit, the second and third triggers, the first and second circuits EXCLUDING OR and The first and second circuits AND, the first input of the voltage sensor being connected to the voltage divider on the electrostatic precipitator, the second input to the voltage source, and the third and fourth inputs corresponding to venno - to the outputs of the second and third flip-flops, the second inputs of which are connected to the sensor output voltage and, respectively, second, and third inputs of the first and second XOR circuits. OR, the outputs of the first and second circuits AND are connected to the inputs of the respective high-voltage voltage sources, the first inputs are connected to the inputs of the first and second output shapers, respectively, and to the outputs of the first and second 25 thirty 35 40 0 and the second inputs - with the first inputs of the first and the second circuits EXCLUSIVE OR, respectively, with the antiphase outputs of the first trigger and the inputs of the first and second differentiating devices, and the first inputs of the second and third triggers are connected to the outputs of the first and second differentiating devices, respectively. lL Jl P P rm Ji IL t I r rLj P ri t P P about ppp Y ( / I I I P n cftuz.3 Phie.