EP0317634A1 - Device for power supply to gas-cleaning electrofilters - Google Patents

Abstract

Power supply device for gas cleaning electrostatic precipitators contains two direct voltage sources (1,2) whose poles (5,6) of the same name are grounded. Between the other poles of the same name of each of the DC voltage sources (1, 2) and a spray electrode (16) of the electrostatic filter (17) are two high-voltage switches, which are designed in the form of electron beam valves (7, 8) of the triode type with hollow anodes (11). Modulators (18, 19) of an alternating voltage are connected to the cathodes (9) and the control electrodes (10) of the electron beam valves (7, 8) and are connected to the control unit (40) via isolating transformers (38, 39), which are connected to Sensors (49, 50, 51, 52) electrical and physical quantities is coupled. In each electrical circuit, which consists of a series connection of the direct voltage source (1,2), the electron beam valve (7,8) and the spray electrode (16) of the electrostatic filter (17), there is a respective storage element (13, 15) in series.

Description

Technical field

The invention relates to energy converters and relates in particular to power supply devices for gas cleaning electrostatic precipitators.

Current state of the art

Devices for the unipolar power supply of electrostatic filters are currently the most widespread, in which the main peculiarity of the work is a reduction in the effectiveness of dust trapping and gas cleaning with increasing volume resistance of a deposited dust layer if this resistance exceeds a value of 10 ⁹ Ω · cm. In this case the deposited layer of dust does not come to discharge and the process of charging the same continues until the layer of dust has broken through and the process of back-spray discharge has started. As a result, the breakdown voltage of the discharge space of the electrostatic precipitator drops, as does the efficiency of gas cleaning. In addition, the devices for unipolar power supply constructed in single-phase transformer rectifier circuits have a low utilization factor for an installed power.

Spark and arc discharges occur during the operation of the electrostatic precipitator, which reduce the reliability of the power supply devices of a gas cleaning electrostatic precipitator. In order to limit the resulting short-circuit currents, current limiting choke coils or magnetic amplifiers with a high reactance are installed, the power of which is up to 1/3 of the useful power of the power supply device and the useful function of which is only briefly realized during the spark and arc discharges. The achievement of a high reactance by switching on the current limiting choke coils or magnetic amplifiers in the power circuit leads to an increase in the installed power of the device and to a doubling of the output voltage when the device is operating in idle mode.

A power supply device for gas cleaning electrostatic precipitators is widely known, which ensures a unipolar power supply and contains a mains current limiting choke coil and a series circuit comprising a thyristor regulator, a high-voltage single-phase transformer and a bridge rectifier, one pole of which is grounded and the second pole of which is connected to a blocking choke Spray electrode of the electrostatic precipitator (GMA Aliev "Agregaty pitaniya elektrofiltrov" ("Food groups for electrostatic precipitators"), 1981, publisher "Energoizdat, (Moscow), p. 5, Fig. 29). The electrostatic precipitator is equipped with a system for mechanical vibration of Precipitation electrodes provided, which is actuated at certain time intervals by a working mechanism.

The effectiveness of the gas purification in the electrostatic precipitator, the _h lagselektrode by the rate of sedimentation of the charged dust particles on the Rainfall is determined of the electric filter, depends on the shape of the supplied operating voltage of the electric filter by the Gleicnrichterschaltung, the control method for this voltage, the level of Output parameters of the device and the external current-voltage characteristic of the device is conditioned. The strongly pulsating form of the working voltage leads to a reduction in the arc discharges that occur in the discharge space of the electrostatic filter, to a reduction in the efficiency and other energy parameters of the device, such as the utilization factor for an installed power.

When cleaning gases containing dust with a high resistance, the degree of gas cleaning increases with an increase in voltage and current only to a certain critical value of the output parameters at which the process of reverse spray discharge begins. As a result, the effectiveness of the power supply device is lowered.

In the device described, the voltage across the electrostatic filter is broken down by the average number of sparks breaks in the discharge space of the electrostatic precipitator. This results in instability in the work of the facility, an increase in energy consumption and a decrease in the effectiveness of the technological process of gas cleaning, because the optimal number of spark breakthroughs. Discharge space is determined by the parameters of the gas stream to be cleaned - moisture, chemical composition, dispersity of the dust particles.

The voltage at the electrostatic precipitator is kept at the maximum level, which is why the operating mode with the spark breakdowns in the discharge space of the electrostatic precipitator becomes regular. An electromagnetic incompatibility of the operating mode for the power supply occurs through the device with the electrophysical processes in the load, which causes instability in the work of setting up and failure of individual components of the device - most often the thyristor regulator and the high-voltage cable between the rectifier pole and the Spray electrode - causes.

A power supply device for gas cleaning electrostatic precipitators is well known, which ensures a unipolar power supply and contains a main high-voltage source consisting of a series connection of a transformer and a rectifier (US, A, 4183736). The output of the main high-DC voltage source is connected to an auxiliary pulse current source, the output of which is coupled to the spray electrode of the electrostatic filter. The value of the pulse voltage of the auxiliary source is approximately 10% of the voltage value of the main source.

During the work of the device, the pulse voltage of the auxiliary source is superimposed on the DC voltage of the main source and regulated according to the pulse amplitude frequency and duration. This allows the current density of the spray discharge to be flexibly controlled and the intensity of the process of the back spray discharge in the xlectrofilter to be reduced. The device described is characterized by a low utilization factor for an installed capacity and by an instability of the operating mode for cleaning characterized by gases containing high-resistance dust. In the known device there is no compatibility between the electromagnetic processes in the feed source and the electrophysical processes in the load and, as a result, no effective protection of the device against spark discharges and arcing of the discharge space of the electrostatic filter is guaranteed. The supply of an electrical multiple filter from a common source is adversely difficult, in terms of energy, because of the impossibility of regulating the electrical parameters of the stages of the electrostatic filter (the current of the spray discharge) separately.

A power supply device for gas cleaning electrostatic precipitators is also widely known, which has a direct current source, the output of which is connected to a series of capacitors connected in parallel via a plurality of diodes connected in parallel. The capacitors are periodically discharged via thyristors onto the primary windings of an step-up transformer connected in parallel, the secondary winding of which is connected to the spring electrode of the electrostatic filter (US, A, 3641740). The use of the pulse voltage of the microsecond range for the power supply of the electrostatic precipitator makes it possible to increase the maximum working voltage between the spray and the low-position electrodes of the electrostatic precipitator and to intensify the process of charging the dust particles. The effectiveness of the main technological process of gas cleaning, which is due to the sedimentation rate and the neutralization of the dust particles, does not increase because of this, that the dust particles charge too often when the capacitors are quickly discharged.

The utilization factor for an installed power in the present power supply device, like the efficiency of this device, does not exceed a value of 0.5.

It is also a gas power supply Cleaning electrostatic precipitator is well known, which secures an alternating power supply and contains two controllable high - DC voltage sources, the poles of the same name are each grounded (SU, A, 904786). Two high-voltage switches are in each case connected between the other poles of the same name of each of the sources and the spray electrode. The device also has a control unit, the inputs of which are connected to transmitters of electrical and physical quantities and the outputs of which are connected to the high-voltage switches.

In response to a signal from the control unit, the high-voltage switches in the form of electromechanical switches periodically switch the spray electrodes of the electrostatic precipitator on and off from one DC voltage source, which forms an alternating voltage on the electrodes of the electrostatic precipitator and ensures a cyclic recharge of the intrinsic capacity of the electrostatic precipitator.

The use of an alternating voltage of rectangular shape and a long duration (τ ≈ 1 s) ensures an optimal operating mode for the recharging of the dust particles in the electrostatic precipitator and eliminates the causes of the occurrence of the process of a back-spray discharge in the layer of dust deposited on the precipitation electrode. When switching, the electrostatic precipitator remains charged to the high voltage of the previous polarity when the polarity is reversed. As a result, the likelihood of an uncontrolled electrical discharge build-up increases in the high-voltage switches and the reliability of the work of the power part of the power supply device decreases. For an electrical discharge during the switching intervals, the known device is provided with an additional controlled discharge element which is connected in parallel to the spray electrode and is connected to the control unit. The cyclical triggering of the controlled discharge element is accompanied by transition processes in the power circuit and the control unit, which reduces the effectiveness of the gas cleaning and the operational reliability of the device. The functioning of the egg _h - direction is also made more difficult due to the need to periodically ground the spray electrode to ground. When spark and arc discharges occur in the electrostatic precipitator, the current limitation is achieved by a large increase in the reactive resistance in the power circuit, which reduces the efficiency and the utilization factor for an installed power of the device. When the device is operating in idle mode, the generation of overvoltages in the supply power circuit is inevitable, which are dangerous for the insulation of the device.

The design of the known device with a high reactance for protection against arcing in the load not only leads to an increase in the installed power, but also limits the range of effective operating modes for cleaning gases containing high resistance dust and for supplying power to electrical multiple filters. Since the current-voltage characteristic of the electrostatic filter depends on the dust concentration, a dependence of the current and voltage of the subsequent cell on the electrical parameters of the preceding cell is observed in the multi-stage devices. The effective operation of the electrostatic filter is only possible when each cell is powered by its autonomous voltage source, which limits the functional possibilities and the energy parameters of the power supply device.

Disclosure of the invention

The invention has for its object to provide a power supply device for gas cleaning electrostatic precipitators with such high-voltage switches, the circuit design allows to limit voltages and currents during transitions in the device, to increase the operational reliability of the device and the degree of gas cleaning.

This is achieved in that in the power supply device for gas cleaning electrostatic precipitators, the two direct voltage sources, their poles of the same name are grounded are two high-voltage switches, which lie between the other poles of the same name of each of the DC voltage sources and a spray electrode of the electrostatic filter, and a control unit, the inputs of which are connected to sensors of electrical and physical quantities and the outputs of which are connected to the high-voltage switches, according to the invention contains the high-voltage switches in Triode-type electron beam valves are designed with hollow anodes and the device additionally has modulators of an alternating voltage according to the number of electron beam valves, the inputs of which are each coupled via their own isolating transformers to the control unit and the first and second outputs of which are each coupled to the cathodes and control electrodes of the electron beam valves, as well as inductive storage elements, each of which lies in an electrical circuit which consists of a series connection of the DC voltage source, the electron beam valve, and the spray electrode of the electrof ilters exists.

In order to increase the effectiveness of the energy recovery during fast transition processes in the device, it is expedient to design the anode of the electron beam valves in the form of a Faraday cylinder.

To further increase the reliability of the device, it is expedient to accommodate the modulators of an alternating voltage in a closed conductive screen, the outer surface of which is galvanically coupled to the control electrodes of the electron beam valves, the first outputs of the modulators isolating an alternating voltage from the screen and the second Outputs are connected to the inner surface of the conductive shield.

It is also expedient that in order to increase the efficiency of the device and the power utilization factor in the power supply of electrical multiple filters, each pair of the electron beam valves, the number of which is equal to that of the stages of the electrostatic filter, is shunted between the poles of the same name of the two direct voltage sources and that inductive storage elements in In the form of pulse transformers, the primary windings of which are connected to at least two additional modulators connected to the control unit, and the secondary windings of which are connected in series between the electron beam valves and the spray electrode of the electrostatic filter.

The application of the present invention makes it possible to effectively limit voltages and currents during transient processes in the device, which arise when the polarity of the power supply to the gas purification electrostatic filter is reversed, to increase the reliability of the device and the degree of gas purification.

Brief description of the drawings

• Fig. 1 ein Blockschaltbild einer erfindungsgemäßen Stromveraorgungseinrichtung für Einfach-Gasreinigungs-Elektrofilter;
• Fig. 2 ein Schaltbild einer erfindungsgemäßen Stromversorgungseinrichtung für Mehrfach-Gasreinigungs-Elektrofilter;
• Fig. 3 eine elektrische Schaltung eines erfindungsgemäßen zusätzlichen Modulators;
• Fig. 4 ein Blockschaltbild einer anderen Ausführungsform der erfindungsgemäßen Stromversorgungseinrichtung für Mehrfach-Gasreinigungs-Elektrofilter;
• Fig. 5 eine grafische Darstellung der Abhängigkeit der Spannung an der Sprühelektrode des Elektrofilters und des Stroms in einem induktiven Element von der Zeit für die Einrichtung gemäß der Erfindung nach Fig. l;
• Fig. 6 grafische Darstellungen der Abhängigkeiten der Ströme an der Anode und Steuerelektrode von der Spannung an der Anode von Elektronenstrahlventilen gemäß der Erfindung;
• Fig. 7 a, b grafische Darstellungen der Abhängigkeit der Spannungen an den Katoden und Anoden der an die Pole von Hochspannungsquellen gelegten Elektronenstrahlventile von der Zeit für die Einrichtung gemäß der Erfindung nach Fig. 2;
• Fig. 7 c,d grafische Darstellungen der Abhängigkeit der Spannung am Ausgang der zusätzlichen Modulatoren einer alternierenden Spannung gemäß der Erfindung von der Zeit;
• Fig. 7 e, f grafische Darstellungen der Abhängigkeit der Spannung an den Sprühelektroden der Elektrofilter gemäß der Erfindung von der Zeit;
• Fig. 8 grafische Darstellungen der Abhängigkeit des elektrischen Stroms der erfindungsgemäßen Stromversorgungseinrichtung und des Stroms des Elektrofilters von der Spannung.

The invention is to be explained in more detail by the following description of specific embodiments of the power supply device for gas cleaning electrostatic precipitators with reference to the drawings. It shows:

• Figure 1 is a block diagram of a power supply device for single gas cleaning electrostatic precipitators according to the invention.
• 2 shows a circuit diagram of a power supply device according to the invention for multiple gas cleaning electrostatic precipitators;
• 3 shows an electrical circuit of an additional modulator according to the invention;
• 4 shows a block diagram of another embodiment of the power supply device for multiple gas cleaning electrostatic precipitators;
• 5 is a graphical representation of the dependence of the voltage at the spray electrode of the electrostatic filter and the current in an inductive element on the time for the device according to the invention according to FIG. 1;
• 6 shows graphical representations of the dependencies of the currents at the anode and control electrode on the voltage at the anode of electron beam valves according to the invention;
• Fig. 7 a, b graphical representations of the dependence of the voltages on the cathodes and anodes on the poles electron beam valves placed by high voltage sources from the time for the device according to the invention of Fig. 2;
• 7 c, d are graphical representations of the dependence of the voltage at the output of the additional modulators of an alternating voltage according to the invention on time;
• 7 e, f are graphical representations of the dependence of the voltage on the spray electrodes of the electrostatic filters according to the invention on time;
• 8 shows graphical representations of the dependency of the electrical current of the power supply device according to the invention and the current of the electrostatic filter on the voltage.

Preferred embodiment of the invention

The power supply device for gas cleaning electrostatic precipitators contains two controllable high Gleioh voltage sources 1, 2 (FIG. 1), each of which has a series connection of a mains-connected contactor 3 and a rectifier transformer 4. The positive pole 5 of the source 1 and the negative pole 6 of the direct voltage source 2 are grounded.

The contactor 3 of the high-DC voltage sources 1, 2 is in a well-known method (SV Shapiro, AS Serebryakov, VI Panteleev "Tiristornye i magnitno - tiristornye agregaty pitaniya elektrofiltrov ochistki gaza" ("Thyristor and Magnetothyristor Power Supply Devices for Gas Cleaning Electrofilters" ), 1978, publisher "Energiya", Moscow, p. 31, picture 2 to 3).

The device contains two high-voltage switches, which are designed in the form of electron beam valves 7, 8 of the triode type with a cathode 9, a control electrode 10 and a hollow anode 11.

The hollow anode 11 of the electron beam valves 7, 8 can also be designed in the form of a Faraday cylinder.

The cathode 9 of the electron beam valve 7 is connected to the negative pole 12 of the DC voltage source 1 via an inductive storage element 13. To the positive pole 14 the anode 11 of the electron beam valve 8 is connected to the direct voltage source 2 via an inductive storage element 15. The anode 11 of the electron beam valve 7 and the cathode 9 of the electron beam valve 8 are placed on a spray electrode 16 of the gas cleaning electrostatic filter 17.

The electron beam valves 7, 8 are connected to modulators 18, 19 of an alternating voltage. The modulators 18, 19 of an alternating voltage contain electron tubes 20, 21 which are in opposite phase and have a cathode 22, control electrodes 23, 24 and an anode 25. The cathode 22 of the tube 20 and the anode 25 of the tube 21 are in the circuit of the control electrode 10 of the electron beam valves 7, 8 and form an output 26 of the modulators 18, 19. The control electrodes 23, 24 of the electron tubes 20, 21 are connected to respective pulse shapers 27, 28. The cathode 22 of the electron tube 21 and the anode 25 of the electron tube 20 are connected to modulation rectifiers 29 and 30, respectively, which are connected in series. The modulation rectifier 29 is coupled to the pulse shaper 28.

The modulation rectifier 30 is connected to the pulse shaper 27.

Each of the modulators 18, 19 of an alternating voltage is arranged in a conductive screen 31.

The cathode 22 of the electron tube 20 and the anode 25 of the electron tube 21 are connected to one another and to the conductive screen 31, the outer surface of which is galvanically connected to the control electrode 10 via a contact 32. The connection point 33 of the poles of the modulation rectifiers 29, 30 is connected to a conductor 34, which forms an isolated output 35 of the modulators 18, 19 of an alternating voltage, which is connected to the cathode 9 of the electron beam valves 7, 8.

The inputs of the pulse shapers 27, 28, which form the control inputs 36, 37 of the modulators 18, 19 of an alternating voltage, are connected to the outputs of the control unit 40 via signal isolating transformers 38, 39. The the inputs 41, 42 of the modulators 18, 19 of an alternating voltage-forming inputs of the modulation rectifiers 29, 30 are connected to an electrical network 45 via power isolating capacitors 43 arranged in an insulating shield housing 44.

The signal isolating transformers 38, 39 and the force isolating transformers 43 are accommodated in the insulating shield housing 44, on which the shield 31 and the valve 7 are arranged.

The windings of the isolating transformers 38, 39 have shields 46 with a high electrostatic potential and grounded shields 47, which are connected by means of a connection 48 to the conductive shield 31 of the modulators 18, 19 of an alternating voltage.

The device is also provided with sensors 49, 50 of the current of the direct voltage sources, which are connected to the grounded poles 5, 6 of the direct voltage sources 1, 2, with a sensor 51, connected to the spray electrode 16 of the electrostatic filter 17, of the voltage at the spray electrode of the electrostatic filter, provided with a sensor 52 of the back-spray discharge connected to a precipitation electrode 53 of the electrostatic filter 17. The outputs 54, 55 of the sensors 49, 50 of the current of the DC voltage sources, the output 56 of the sensor 51 of the voltage at the spray electrode of the electrostatic filter, the output 57 of the sensor 52 of the reverse spray discharge are led to the inputs of the control unit 40.

The outputs 58, 59 of the control unit 40 are coupled to the contactors 3 of the DC voltage sources 1 and 2 and the outputs 60, 41 to the signal isolating transformers 38, 39.

The circuit design of the control unit 40 is well known ("Elektrotekhnicheskaya promyshlennost"("Electrical engineering industry"), consequence "Apparaty vysokogo napryanzheniya, transformatory, silovye kondensatory"("High-voltage devices, transformers, power capacitors"), H. 9 / 122,1981 , Moscow, VI Perevodchikov ea "Elektronnye kommutatory dlya istochnikov pitaniya elektrofiltrov "(" Electron switch for feeding sources of the electrostatic precipitators ", S, 16 to 18).

The power supply device for multiple gas cleaning electrostatic precipitators, namely for an electrostatic precipitator 17 consisting of three stages 62, 63, 64 (FIG. 2), in which each pair of electron beam valves 7, 8, the number of which is equal to that of stages 62, 63, 64 of the electrostatic filter 17 is placed between the poles 12, 14 of the same name of the two direct voltage sources 1, 2 in the shunt. The inductive storage elements are designed in the form of pulse transformers 65, 66. The primary winding 67 of each pulse transformer 65, 66 is coupled with its connection 68 to an additional modulator 69. The secondary winding 70 of each pulse transformer 65, 66 is connected in series between the electron beam valve 7 or 8 and the spray electrode 16 of each stage 62, 63, 64 of the electrical multiple filter. The outputs 71, 72 of the additional modulators 69 are connected to the control unit 40. The electron beam valves 7, 8 located between the two DC voltage sources 1, 2 with the secondary windings 70 of the pulse transformers 65, 66 form arms 73, 74, 75, 76, 77, 78 of a multi-arm commutation bridge, in the galvanically split diagonal of which the spray electrodes 16 of each stage 62 , 63, 64 of the electrostatic filter 17 are connected.

In the present embodiment of the power supply device for electrostatic precipitators, the DC voltage sources 1, 2 contain a contactor 3 and a rectifier transformer 4, which consists of an step-up transformer 79, the secondary winding of which is connected to a rectifier bridge 80.

The additional modulator 69 contains a series connection of a thyristor controller 81 (FIG. 3) connected to an electrical network 82 (FIG. 3), a charging source 83, a charging inductor 84, a diode 85 and a switching thyristor 86 connected in parallel to a forming chain 87 Pulse transformer 65.66 connected with its output 68. The shaft thyristor 86 lies between the ground terminal 88 of the primary winding 67 each pulse transformer 65, 66 and the input 89 of the formation chain 87. The outputs of the thyristor controller 81 and the switching thyristor 86 form the outputs 71, 72 of the additional modulators 69 connected to the control unit 40.

Another embodiment of the power supply device for an electrical multiple filter, as shown in FIG. 4, is possible. The gas cleaning electrostatic filter 17 has two stages 90, 91. The arms 92, 93, 94, 95 of a four-arm commutation bridge are formed by the series-connected electron beam valves 7, 8 and the secondary windings 70 of the pulse transformers 65, 66, the primary windings 67 of which are coupled to the two additional modulators 69. RC attenuators 96, 97 are applied to the poles 12, 14 of the same name of the high-voltage sources 1, 2.

LC attenuators can be used.

The diagonals of the commutation bridge are connected to the spray electrodes 16 of each stage 90.91 of the electrostatic filter 17 by means of high-voltage cables 98.99.

The power supply device for gas cleaning electrostatic precipitators works as follows.

In the initial state, the electron tubes 21 (FIG. 1) of the modulators 18, 19 of an alternating voltage are conductive; negative reverse voltages are applied to the control electrodes 10 of the electron beam valves 7, 8 by the rectifiers 29 of the modulators 18, 19. The device is continuously set to idle operation by means of the contactor 3 of the DC voltage sources 1, 2. When the target level of the output voltage of the DC voltage sources 1, 2 is reached, a signal from the transmitter 51 of the voltage at the spray electrode 16 of the electrostatic filter 17 reaches the input of the control unit 40, which signal arrives from the outputs 60, 61 of the control unit 40 via the isolating transformers 38, 39 signals arriving at the inputs 36, 37 of the modulators 18, 19 of an alternating voltage. Under the effect of these signals coming from the control unit 40, an opening and take place alternately blocking of the electron beam valves 7, 8 by changing the electrostatic potential of the outer surface of the conductive screen 31, which is regulated by the modulator 18, 19 of an alternating voltage and is applied to the control electrode 10 of the electron beam valve 7 and 8.

The blocking state of one of the electron beam valves 7, 8 is fixed at the control electrode 10 at a negative potential. The corresponding voltage of negative polarity is formed by the modulation rectifier 29 and the electron tube 21 of the modulators 18, 19 of an alternating voltage.

The conductive state of one of the electron beam valves 7, 8 is fixed to the control electrode 10 at a positive potential. The corresponding voltage of positive polarity is generated by the rectifier 30, the electron tube 20 and the pulse shaper 27 of the modulators 18, 19 of an alternating voltage.

Depending on the current level of the electrostatic filter 17, the voltage of the control electrode 10 of the electron beam valves 7, 8, the current at the output of the modulators 18, 19 of an alternating voltage, the electron beam valves 7, 8 operate in switch operation with a small voltage drop at the anode 11 of less than 1 kV and in resistance mode, where the value of the voltage drop at the anode 11 increases to the breakdown voltage at the spray electrode 16 of the electrostatic filter 17.

In the embodiment of the device where the anode 11 of the electron beam valve 7, 8 in the form of a Faraday cylinder with a large surface area and with intensive liquid cooling in the time intervals τ _i , * τ _o , (FIG. 5) of the commutation of the valves is executed, the edges of the pulses of positive and negative polarity are formed by converting the kinetic energy of an electron beam of the electron beam valve 7,8 (Fig.l) into the thermal energy.

At time t ₌ 0 (FIG. 5), the charge cycle of the self-capacitance of the electrostatic filter 17 (FIG. 2) begins at Opening of the electron beam valve 7. The steepness of the leading edge τ _i (FIG. 5) of the pulse is determined by the parameters R, L, C of the charging circuit: the intrinsic capacity of the electrostatic filter 17 and the inductors 13, 15 and by the braking operation of the electron beam in the electron beam valve 7 , 8 (Fig. 1).

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ist. Der Verlauf dieser grafischen Darstellungen ermöglicht die Steuerung des Zeitintervalls τ₁ (Fig. 5) der Flanken der Impulse einer alternierenden Spannung und eine Begrenzung des Stroms des Elektrofilters 17 (Fig. 1) zu den Zeitpunkten des Aufbaus der Funken- oder Lichtbogenentladungen des Elektrofilters 17 in Abhängigkeit von den Signalen der Geber 49,50 des Stroms der Gleiehspannungsquellen, des Gebers 51 der Spannung an der Sprühelektrode, des Gebers 52 der Rück-Sprühentladung. Hierbei erfolgt eine nachgiebige und adaptive Steuerung der Betriebsart des Elektrofilters 17, die von Übergangsvorgängen begleitet wird, was bei der Reinigung von Gasen besonders wichtig ist, die einen hochohmigen Staub mit einem spezifischen elektrischen Widerstand von über 2.10 ⁸ Ω.m enthalten.. The time intervals τ _i , τ _o (FIG. 5) of the pulse edge, which characterize the possibility of power control and modulation in the electrostatic filter 17 (FIG. 1), depend on the value of the load current, the voltage of the control electrode 10 of the electron beam valve 7, 8, the value of their interference capacitance and the insertion parameters of the power circuit - the intrinsic capacitance of the electrostatic filter 17 and the inductive elements 13, 15 in the circuit of the rectifier transformer 4 of the DC voltage source 1. The control and stabilization functions of the electron beam valves 7, 8 are defined by a graphic representation (FIG. 6) of the dependency of the current of the anode 11 and the control electrode 10 on the voltage at the electron beam valve 7, 8. The voltage U of the control electrode 10 is approximately constant, wherein

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is. The course of these graphical representations enables the control of the time interval τ ₁ (FIG. 5) of the edges of the pulses of an alternating voltage and a limitation of the current of the electrostatic precipitator 17 (FIG. 1) at the times when the spark or arc discharges of the electrostatic precipitator 17 are built up as a function of the signals from the sensors 49, 50 of the current of the track voltage sources, the sensor 51 of the voltage at the spray electrode, and the sensor 52 of the back-spray discharge. This gives a flexible and adaptive control of the operating mode of the electrostatic precipitator 17, which is accompanied by transition processes, which is particularly important when cleaning gases which contain a high-resistance dust with a specific electrical resistance of over 2.10 ⁸ Ω.m.

In the operation of the gas cleaning electrostatic precipitator 17, radio discharges occur, the frequency of which depends on the parameters of the dust-gas flow Geometry of the discharge space of the electrostatic precipitator 17 moves in the range from 50 to 150 per minute and increases with increasing specific electrical resistance of the dust particles.

The spark discharges in the electrostatic filter 17 are built up in the moments t ₂ and t ₄ (FIG. 5). The process of voltage recovery in the electrostatic filter 17 is caused by the properties of the electron beam valve 7, 8, by its current-voltage characteristics (FIG. 6). The electron beam valves 7, 8 (FIG. 1) limit the current of the spark and arc discharge of the electrostatic filter 17, the value of which does not exceed one and a half times. The dielectric strength of the electrode space of the electrostatic filter 17 is quickly restored for a time interval τ _o (FIG. 5).

The shield housing 44 (FIG. 1) of the modulator 18, 19 of an alternating voltage decouples the control circuits in the event of rapid fluctuations in the operating mode.

In practice, the electrical discharge in the electrostatic precipitator 17 does not transition to an arc stage, and the spark stage of the discharge proceeds in such a way that erosion of the spray and precipitation electrodes 16 and 53 of the electrostatic precipitator 17 and an interruption in its power supply are minimal.

The time interval τ _r (FIG. 5) of the pulse roof is selected by the selection of the blocking time of the electron beam valve 7 or 8 (FIG. 1). After completion of the predetermined time interval τ _r (FIG. 5) of the roof of the positive polarity pulse, the control unit 40 (FIG. 1) delivers a signal for blocking the electron beam valve 7 and for opening the electron beam valve 8 at time t ₆ Circuit: valve 7, inductive element 13, rectifier transformer 4 of DC voltage source 1, grounded pole 5 of source 1, in which the self-capacitance of the electrostatic filter 17 discharges. The limitation and stabilization of the discharge current via the inductive element 13 is effected by the action of the electron beam valve 7 (FIG. 6) in a pre- g _a weighted U _{St. of} the voltage at its control electrode 10 reached.

The current change i _L = f (t) (FIG. 5) in the inductive element 13 is determined by a non-linear behavior of the discharge circuit, in which the electromagnetic energy is recovered, which is stored in the self-capacitance of the electrostatic filter 17 with a positive polarity of the working voltage .

At the moment t _e , the energy stored in the magnetic field of the inductive element 13 (FIG. 1) is used for the recharging of the intrinsic capacity of the electrode space of the electrostatic filter 17. At time t ₉ (FIG. 5), the self-capacitance of the electrostatic filter 17 (FIG. 1) has completely reloaded.

Then the electron beam valve 8 generates a negative half-wave (FIG. 5) of the working voltage. In this way, the electron beam valves 7, 8 fully controlled by means of the modulators 18, 19 (FIG. 1) of an alternating voltage ensure recovery of the electromagnetic energy when the working voltage of the electrostatic filter 17 is reversed and recovery of the energy from rapid electrophysical transition processes during the spark discharges in the electrostatic filter 17.

The duration and amplitude of the pulses of positive and negative polarity can be regulated independently by the control unit 40, at the inputs of which signals the transmitter 49, 50 of the current of the DC voltage sources, the transmitter 51 of the voltage at the spray electrode, and the transmitter 52 of the back-spray discharge are applied will.

Here, the effect of the back-spray discharge is eliminated or reduced, and the choice of the steepness of the current impulses of the electrostatic precipitator 17 achieves self-shaking of the precipitation electrodes 53 of the electrostatic precipitator 17 for dedusting as a result of an electromechanical effect which arises in the event of a sudden strong change in voltage on the self-capacitance .

When the electrostatic precipitator 17 (FIG. 2) is designed as a multiple filter with stages 62, 63, 64, the Ven begins to conduct tile 7 and 8 of arms 73, 75 and arms 74, 76 of the commutation bridge in pairs at the same time. In accordance with the signals from the transmitters 49, 50 of the current aer direct voltage sources, the transmitter 51 of the voltage at the spray electrode, the transmitter 52 of the back-spray discharge, the control unit 40 detects the time interval τ ₁ and τ ₂ (FIG. 7 a, b) of the roof the pulse of an alternating voltage. At the time instant t ₁ , the formation of the flanks of the alternating voltage comes to an end, and at the time instant t ₂ , signals arrive from the outputs 60, 61 (FIG. 2) of the control unit 40, whereupon the valves 7, 8 of the arms 73 and 74, respectively lock and open valves 7, 8 of arms 75 and 76, respectively. The time intervals τ _{k 1} and τ _{k 2nd} (FIGS. 2a, b) represent a switching interval when there is a linear decrease in the current of the electron beam valve 7 (FIG. 2) of the arm 73 and an increase in the current of the electron beam valve 7 of the arm 75. The in the time intervals τ _{k 1} , τ _{k 2nd} (FIG. 7 a, b) the average current drawn from the pole 12 (FIG. 1) of the high DC voltage source 1 has a constant value. At the instant t ₃ (FIG. 7) the switching interval of the corresponding pair of valves 7, 8 (FIG. 2) ends and the roof of the voltage pulse is formed until time t ₄ (FIG. 7), where the next cycle of the Switching of the current between the electron beam valves 7,8 of the same polarity begins.

In the additional modulators 69 (FIG. 3), which in the specific embodiment contain the formation chains 87 constructed from the LC links, the capacitors of the formation chains 87 are charged with the aid of the charging source 83. After the switching thyristor 86 has been ignited, the formation chain 87 discharges with a signal arriving at the input 72 of the additional modulator 69 from the control unit 40. The discharge current flows through the primary winding 67 of the pulse transformer 65. The output voltage of a predetermined duration is shaped by the secondary winding 70 of the pulse transformer 65, 66. The level of the pulse voltage is controlled by the thyristor controller 81 regulated, the control output 71 is connected to the control unit 40. The pulse frequency changes as a function of the ignition timing of the switching thyristor 86. The pulse transformer 65 performs separation functions, and its insulation is dimensioned for a full operating voltage of the electrostatic filter 17. For each polarity of the output voltage of the device, the own additional modulator 69 is used, which has a series of pulses of positive or negative polarity (according to FIG. 7 c, d) with the parameters: duration τ _{M 1} τ _{M 2nd} ; Period T _{M 1} , T _{M 2nd} ; Amplitude U _{M 1} , U _{M 2nd} formed.

The windings of the pulse transformers 65, which have a relatively small inductance and are designed for the formation of short pulses of a few tens of microseconds, fulfill the functions of blocking reactors by additionally limiting the pulse overcurrents which are caused by the discharge of the self-capacitance of the electrostatic filter 17.

The series connection of the additional pulse transformers 65, 66 in all arms of the commutation bridge and the use of the independent modulators 18, 19 enable separate control of the charging and the drift speed of the dust particles in each stage of the electrostatic filter 17.

The arms 73, 74, 75, 76, 77, 78 of the commutation bridge generate an alternating voltage U _Σ , U _{r of a} complicated shape (FIGS. 7 e, f), the parameters of which are determined by the work of the modulators 69, the DC voltage sources 1 and 2 and the electron beam valves 7 and 8 can be determined. The process of returning the energy stored in the self-capacitance of each stage 62, 63, 64 of the electrostatic filter 17 is accompanied by the transfer of the excess energy of the self-capacitance of the electrostatic filter 17 into leakage inductances of the pulse transformers 65 and 66, which corresponds to the time interval -t ₂ to t ₃ , where the current in the inductance of the transformers 65, 66 has the shape of the pulse of the current i _L. Here there is an electroless break (Time interval τ _n ) formed in the electron beam valves 7,8, which the switching operation in the power supply. direction relieved.

The superimposition of the alternating voltage of large duration by short modulation pulses of the amplitude U _{M 1} and U _{M 2nd} with the aid of the modulators 69 (FIG. 2) and the isolating pulse transformers 65, 66 ensures an additional increase in the effectiveness of the gas cleaning process by separately intensifying and controlling the rate at which the dust particles are charged and deposited on the electrode 53.

The supply of the alternating total voltage U _{Σ 1} , U _{Σ 2nd} (Fig. 7 e, f) complicated staircase shape allows, by changing the parameters of the superimposed pulses with the amplitude UM, the charge obtained by the dust particles in the field of the spray discharge and the drifting speed of the dust particles in the direction of the precipitation electrode 53 (Fig. 2) increase. With a relatively low power consumption P _M for the modulation of the alternating main voltage, the effectiveness of the gas cleaning is maintained while maintaining the operating modes of the recovery of the electromagnetic energy in the time intervals τ _{k 1} , τ _{k 2nd} (Fig. 7) the commutation of the valves additionally increased.

In the formation of the alternating voltage, which eliminates the back-spray discharge and ensures the effect of self-shaking of the electrodes, an uninterrupted current draw is realized from the high-DC voltage sources 1, 2 of different polarities, which can be constructed in a three-phase bridge circuit. This makes it possible to work in the operating mode with a utilization factor for an installed power of the sources 1, 2 close to 1.

If the number of pairs of the electron beam valves 7,8 is odd, as shown in FIG. 2, the valves 7,8 of the arms 77, 78 start with a delay at the time.

Furthermore, the operating mode of the arms 77 and 78 similar to the work of the electron beam valves 7, 8 of the arms 73, 74 of the commutation bridge.

The work of the other embodiment of the power supply device for gas cleaning electrostatic precipitators is analogous to that described above. In this case, the additional modulators 69, the outputs 68 of which are parallel to the primary windings 67 of the pulse transformers 65, 66, generate unipolar pulses which are fed into the arms 92, 94 or 93, 95 of the commutation bridge. The modulators 18 and 19 and the isolating transformers 44 are connected together to control the valves 7 (positive polarity) or valves 8 (negative polarity) of all arms 92, 93, 94, 95. The RC attenuators 96, 97 connected to the poles 12 and 14 of the DC voltage sources 1 and 2 provide additional protection against overvoltages that occur during the switching intervals.

• U_o die Spannung am Ausgang 99,
• I_o der Strom am Ausgang eines Armes der Einrichtung,
• I_a der Aufnahmestrom des Elektrofilters,
• U _a die Spannung an der Sprühelektrode des Elektrofilters.

The external characteristics of the power supply device for gas cleaning electrostatic precipitators shown in FIG. 8 are recorded separately on the anode of the valve 7 or the cathode of the valve 8, on the power cables 98 and 99 (FIG. 2). The characteristics of the arms 74, 76, 78 of the commutation bridge (with positive polarity) are shown. In the graphical representation of the dependency I ₌ f (U), designations are assumed:

• U _o the voltage at output 99,
• I _o the current at the output of an arm of the device,
• I _a the absorption current of the electrostatic filter,
• U _a the voltage at the spray electrode of the electrostatic precipitator.

The diagrams I _o = f (U _o ) are recorded for different values of nominal powers (in a range of lA <I _o <2A). The diagrams I _a = f (U _a ) characterize various parameter values of the dust-gas flow (speed, humidity, concentration of the dust particles). The power supply device has useful properties of a voltage source (in nominal operation) and a current source (in transition operations).

The use of the electron beam valves in the device ensures electromagnetic compatibility between the main elements of the power circuit with one another and the control units, which increases the operational reliability of the device. The ability to transition the device from the voltage source mode to the current source mode during pulse intervals eliminates the need to use a powerful current limiting inductor, the presence of which results in an abrupt decrease in the utilization factor for an installed electromagnetic power. When cleaning the gases containing a non-resistive dust, the optimal change range of the carrier frequency of the alternating voltage is 0.01 to 10 Hz, the duration of the modulation pulses 10 to 100 µs, the ratio UM / U _{l of} the voltage amplitudes 0.1 to 0.3. The edge duration of the main pulse can be varied within a range of 5 to 20.0 ms, the current value up to 2.5 A and the voltage + 50 kV.

The device can be used to supply power to multiple electrostatic filters (n = 2 to 8) with an output of a few hundred kW and above. Here, the operating mode for an asymmetrical power supply of the electrostatic precipitators can be easily implemented by means of pulses of different amplitudes and durations, which makes it possible to additionally promote the gas cleaning process.

Industrial applicability

The invention can be used for electrical cleaning of flue gases, in thermal power plants, in the metallurgy and cement industry.

Claims (4)

1. Power supply device for gas cleaning electrostatic precipitators, the two direct voltage sources (1,2), the opposite poles (5,6) of which are grounded, two high voltage switches, which are connected between the other opposite poles (5,6) of each of the direct voltage sources (1,2 ) and a spray electrode (16) of the electrostatic filter (17), and contains a control unit (40), the inputs of which are connected to sensors (49, 50, 51, 52) of electrical and physical quantities and the outputs of which are connected to the high-voltage switches gekennzeichn et that the high-voltage switch in the form of electron beam valves (7,8) of the triode type with hollow anodes (11) and the device additional modulators (18,19) of an alternating voltage according to the number of electron beam valves (7,8), their inputs (36, 37) each have their own isolating transformers (38, 39) with the control unit (40) and their first and second outputs (35, 26) with the cathodes (9) and control electrodes (10) of the elec Tronenstrahlventile (7,8) are coupled, and inductive storage elements (13,15), each of which is in an electrical circuit, which consists of a series connection of the DC voltage source (1,2), the electron beam valve (7,8), the spray electrode (16) of the electrostatic filter (17). 2. Device according to claim 1, characterized g e-markneet that the anode (11) of the electron beam valves (7,8) is in the form of a Faraday cylinder. 3. Device according to claim 1,2, characterized in that the modulators (18, 19) of an alternating voltage are accommodated in a closed conductive screen (31), the outer surface of which is galvanically connected to the control electrodes (10) of the electron beam valves (7, 8) is coupled, the first outputs (35) of the modulators (18, 19) isolating an alternating voltage from the conductive screen (31) and the second outputs (26) of which are connected to the inner surface of the conductive screen (31) are connected. 4. Power supply device for multiple gas cleaning electrostatic precipitators according to claims 1,2,3, d a-characterized in that each pair of the electron beam valves (7,8), the number of which is equal to that of the steps (62,63,64) of the electrostatic precipitator (17) is shunted between the poles (5,6) of the same name of the two direct voltage sources (1,2) and the inductive storage elements (13,15) are in the form of pulse transformers (65,66), whose primary windings (67) on at least two additional modulators (69) connected to the control unit (40) and the secondary windings (70) of which are connected in series between the electron beam valves (7, 8) and the spray electrode (16) of the electrostatic filter (17).

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