SU1271572A2 - Apparatus for automatic control of static precipitator voltage - Google Patents

Abstract

The invention relates to devices for automatic control of the flow rate of an electrostatic precipitator, can be used in the chemical industry and allows an increase in the degree of purification of flue gases by expanding the range of control and increasing the reliability of the operation of an electrostatic precipitator. The device contains a transformer 1 connected to a voltage divider 3 via a HiCie Hiibie series high voltage rectifier 2, resistance 5 and a selector 6. The thyristor 9 of a transformer 1 G10.1 is connected to the driver AND the control signal of the continuous mode through serially connected driver 8 control pulses and amplitude. phase-to-phase converter 7. The latter is connected to a switch 23 of operation mode (manual and "automatic) connected via a cut-off diode 21 to a variable resistor 20 connected to the unit of the transient mode 12. The latter contains an oscillating circuit (capacitor 16, choke 17, thyristor 18), divisors (welding 191 and RC circuit; resistor 13 cl and capacitor 14. 1 ill. sp o ho ho

Description

The invention relates to the field of electrical power supply of industrial electrostatic precipitators, in particular, to automatic voltage control devices on an electrostatic precipitator, and is an improvement of the device described in the ed. St. No. 355606.

The aim of the invention is to increase the degree of purification of waste gases by electrostatic precipitators by expanding the range of control and increasing the reliability of the electrostatic precipitator.

The drawing shows the functional diagram of the device.

The device contains a high-voltage transformer 1, a high-voltage rectifier 2, a voltage divider 3, from whose lower arm a signal proportional to the voltage on the electrodes of the electrostatic precipitator 4 is removed, a resistance 5 from which a signal proportional to the current consumed by the electrostatic filter 4, the selector 6 is removed. bits intended to separate the transient components of the voltage on the electrostatic precipitator and the current flowing through the electrostatic precipitator corresponding to the spark discharge. The amplitude-phase converter 7 and the control pulse shaper 8 implement the well-known vertical principle of phase-pulse control of the thyristors 9 of the power regulator. The vertical control is based on a comparison of a reference sawtooth voltage, synchronized with the frequency of the mains supply, and the adjustable value of the constant voltage (control signal) on the capacitor 10.

The durable mode control signal generator 11 is intended to change (increase) the level of the control signal on the capacitor 10 when a spark breakdown occurs in the electrostatic precipitator 4 and with an increase in the current consumed by the electrostatic precipitator 4 above the specified one. The transient mode unit 12 is designed for a short-term, equal to several half-periods of the supply voltage, a change in the level of the control signal (the time of this change is determined by the parameters of the parallel RC chain: resistor 13 and capacitor 14), as well as for a relatively long change in the level of the control signal. The duration, and accordingly, the magnitude of the change in the signal level, is controlled by the resistor 15 and the frequency of occurrence of spark discharges in the electrostatic precipitator is determined. The capacitor 16, the choke 17, the thyristor 18 form an oscillating circuit. The coupling diode 19 is designed to eliminate the effect of the resistor 13 on the discharge time of the capacitor 10 (i.e., on the rise time of the voltage on the electrostatic precipitator 4 after the breakdown). The variable resistor 20 is designed to manually adjust the voltage level on the electrostatic precipitator 4. The cut-off diode 21 is designed to eliminate the effect of the resistor 20 on the rise time of the voltage on the electrostatic precipitator 4 after the breakdown. The switch 22 is designed to start the device, and the switch 23 is for selecting the operation mode (“manual,“ automatic).

The device works as follows. In the initial state, the supply voltage was applied to all units of the device. Through the closed switch 22, the voltage on the capacitor 10 in the initial state

5 is equal to the supply voltage and exceeds the reference sawtooth voltage of the converter 7, therefore the control pulses do not enter the power thyristors 9 and the voltage on the electrostatic precipitator 4 is maximum. When you turn off the switch 22

 the capacitor 10 begins to discharge, the discharge time is determined by the input resistance of the amplitude-phase converter 7. The moment of equality of the control voltage on the capacitor 10 with the sawtooth reference voltage of the amplitude phase converter 7 determines: the pulse duration at the output of the converter 7, the phase shift relative to the half-cycle of the mains voltage of the control pulse at the output of the driver 8

0 and the turn-on angle of the power thyristors 9. With a decrease in the voltage on the capacitor 10, the turn-on angle of the power thyristors and the voltage level on the electrostatic precipitator increases 4. In the event of spark discharges, the electrostatic precipitator 4 at the output of the spark selector 6 appears voltage pulse, including thyristor 18 of transient mode block 12. Oscillating charge of capacitor 10 occurs along the circuit

0 16, 17, 18, 19, 10, 16. After the end of the first half-wave of the current, the thyristor 18 will be automatically locked and the voltage on the capacitor 10 will increase by 2 (Uj6-Uio), the turn-on angle of the power thyristors 9 will decrease, the voltage on the elec filter 4, and in the following half-periods of the supply voltage, spark breakdowns no longer occur. Next, the capacitor 10 is discharged, the turn-on angle of the thyristors 9 increases, the voltage on the Q filter 4 increases to the next spark breakdown, etc. Depending on the position of the slider of the resistor 15, the depth of the test (the magnitude of the decrease in voltage on the electrostatic precipitator 4 after the spark breakdown) can be adjusted so that

5 depending on the specific operating conditions of the electrostatic precipitator 4, to ensure reliable operation of the unit and electrostatic precipitator 4. The voltage surge on the resistor 13 and the capacitor 14 when the thyristor 18 is turned on provides a short-term (1-2 half-periods of the supply voltage) blocking of the switching angle of the thyristors 9.

If it is necessary to minimize the probability of occurrence of spark discharges in the electrostatic precipitator 4, for example, when cleaning an explosive dust-gas mixture or when a polymer coating of the collecting electrodes of the electrostatic precipitator 4 is present, the switch 23 closes and the resistor 20 sets the level of the control voltage on the capacitor 10. When after switching on the device (switch 22), the voltage on the capacitor 10 decreases to a value equal to the voltage level given by the resistor 20, an additional diode 21 opens and the voltage across The condenser 10 remains fixed. Accordingly, the voltage on the electrostatic precipitator 4 remains fixed.

If for some reason a spark breakdown occurs in the electrostatic precipitator 4, the device operates as follows: the capacitor 10 is recharged, reduced by the value given by the resistor 15, the voltage on the electrostatic precipitator 4 and the delayed spark breakdown does not occur on the subsequent half-periods of the supply voltage . Then, the voltage on the capacitor 10 decreases with a speed determined by the input resistance.m of the converter 7, since the resistor 20 is actually disconnected from the capacitor 10 by the locked diode 21. When the voltages on the capacitor 10 and the resistor 20 are equal, the diode 21 opens and the voltage on the capacitor 10, respectively, and on the electrostatic precipitator 4, remains fixed. Thus, if, before approaching a fixed voltage level on the electrostatic precipitator 4, a spark breakdown occurs in it, the operation of the device in the manual control mode is similar to the operation of the device in the automatic control mode, prolonged spark breakdowns, emergency shutdowns of the device and burnings of the electrodes do not occur.

The presence of the proposed device in the block transitional additional

elements: a variable resistor, a capacitor, a decoupling diode ensures reliable operation of the device in the automatic regulation mode, i.e., maintaining the highest possible voltages and, accordingly, the maximum possible degree of purification for all changes in the parameters of the dust-gas mixture being cleaned electrostatic precipitator electrodes (overgrowing, de-centering) over the entire range of currents consumed by the electrostatic precipitator. At the same time, the possibility of a spark discharge in an electrostatic precipitator in the mode of uniform sparks, switching off the device by the protection system, and therefore just an electrostatic precipitator and increasing emissions to the atmosphere, is excluded. The likelihood of burnout of corona electrodes decreases, which leads to a decrease in unplanned downtime of the electrostatic precipitators and ultimately results in a decrease in air emissions.

Connecting the manual adjustment resistor slider to the capacitor at the output of the continuous mode driver through a cut-off diode ensures reliable operation of the device and an electrostatic filter, if necessary, to minimize the probability of spark breakdowns in the electrostatic precipitator, for example, when cleaning explosive gases and using polymer coated precipitating electrodes .

Claims (1)

Invention Formula Device for automatic regulation of the electrostatic precipitator voltage St. No. 355606, characterized in that, in order to increase the degree of gas purification by electrostatic precipitators, expanding the control range and increase the reliability of the electrostatic precipitator, a variable resistor and a capacitor are additionally introduced into the transient mode unit, the output of the unit is connected via a diode to a capacitor at the output of the long-term signal conditioner connected through an additional cut-off diode with a manual resistor slider.