EP0209714A1 - Procédé pour mettre en oeuvre un filtre électrostatique - Google Patents

Procédé pour mettre en oeuvre un filtre électrostatique Download PDF

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Publication number
EP0209714A1
EP0209714A1 EP86108070A EP86108070A EP0209714A1 EP 0209714 A1 EP0209714 A1 EP 0209714A1 EP 86108070 A EP86108070 A EP 86108070A EP 86108070 A EP86108070 A EP 86108070A EP 0209714 A1 EP0209714 A1 EP 0209714A1
Authority
EP
European Patent Office
Prior art keywords
voltage
filter
current
alternating current
converter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP86108070A
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German (de)
English (en)
Other versions
EP0209714B1 (fr
Inventor
Hermann Dipl.-Ing. Mickal
Franz Dipl.-Ing. Neulinger
Walter Dipl.-Ing. Schmidt
Helmut Dipl.-Ing. Schummer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GEA Group AG
Siemens AG
Siemens Corp
Original Assignee
Metallgesellschaft AG
Siemens AG
Siemens Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metallgesellschaft AG, Siemens AG, Siemens Corp filed Critical Metallgesellschaft AG
Publication of EP0209714A1 publication Critical patent/EP0209714A1/fr
Application granted granted Critical
Publication of EP0209714B1 publication Critical patent/EP0209714B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/66—Applications of electricity supply techniques
    • B03C3/68—Control systems therefor

Definitions

  • the invention relates to a method for operating an electrostatic filter with the features of the preamble of claim 1 (DE-AS 19 23 952).
  • electrostatic filters are often used, the plates and spray wires of which are supplied with such a high DC voltage that in the medium passed between the plates and spray wires ionization of the foreign substances contained and their separation on the plates occurs.
  • the DC voltage (supply voltage) of the plates and spray wires is chosen to be as high as possible.
  • ionization processes also take place in the gas itself, which lead to a permanent discharge of the filter up to a corona discharge on the spray wires.
  • the filter discharges via short breakdowns or even voltage breakdowns up to a stationary arc if the direct current supplied by the voltage supply is not interrupted. No significant foreign matter separation is then possible until the subsequent reconstruction of a high DC voltage. In addition, these processes cause wear on the filter, in particular its spray wires, and short downtimes of the entire device.
  • the ionization processes and thus the mentioned limit value of the supply voltage depend on the distribution of the electric field strength between the plates of the electrostatic filter. Insulating layers of foreign substances deposited on the plates must be knocked off, collected and removed at certain intervals - if necessary with the supply voltage switched off for as short a time as possible. In addition, ionization creates space charges with strong distortions in the potential profile between the plates, and the voltage gradient and the spray direction can even be reversed between plates and space charges.
  • the limit value mentioned is therefore not constant during operation.
  • the supply voltage of the filter should be kept as close as possible to this practically uncontrollably changing limit value.
  • Electrostatic precipitators contain a voltage supply that is connected to two phases of a three-phase network and takes an alternating current from the network via an electronic actuator.
  • the output voltage of the actuator is controlled by the firing angle and supplies a line-frequency alternating current which is phase-shifted with respect to the input voltage and which then feeds the electrostatic filter as a pulsating continuous current after step-up and rectification.
  • DE-AS 19 23 952 to ramp up the voltage on the electrostatic filter after a certain ramp-up function via the gate control in the actuator until the limit value corresponding to the current state of the filter is reached and there is a voltage breakdown or a similar sudden discharge of the filter occurs.
  • the AC power controller must first be blocked after a breakdown in order to avoid an arc and to wait for the deionization of the plasma formed.
  • the currentless minimum pause is determined by the frequency of the actuator, i.e. the mains frequency.
  • the result of this is that the filter is fed by a direct current which flows practically without gap with a ripple corresponding to the mains frequency and is interrupted after a breakdown. For the filter voltage fed by this current, there is an undulating course which rises until it breaks down.
  • Electrostatic precipitators have also been proposed in which the filter is not supplied with such a practically seamless direct current which is taken from the supply network by a mains-frequency alternating current regulator, is highly transformed and rectified. Rather, the filter is charged by a sequence of individual voltage or direct current pulses. In order to supply the charge that flowed across the medium during the pulse pauses, the frequency and / or duration of the individual pulses are specified such that the mean current intensity of these isolated direct current pulses assumes a filter current setpoint value that is adapted to the respective filter state. This creates a filter voltage that is rippled in accordance with the pulse repetition frequency, the value of which is as far as possible below the breakdown limit.
  • a combination is currently striven for as an optimal method in which the filter is initially biased via a rectifier with an already relatively high, practically constant basic DC voltage, which is then superimposed on an AC voltage or isolated individual voltage pulses in order to generate a wavy filter voltage.
  • the height of the filter is said to be considerably above the breakdown voltage of the filter, but a very short pulse duration means that no arc is formed when the filter is discharged.
  • the duration, shape and pulse repetition frequency of these isolated individual pulses are adapted to the respective load condition of the filter.
  • isolated current pulses are fed to the filter biased to the constant basic DC voltage, the maximum amplitude of which is controlled in accordance with a setpoint value for the filter current in such a way that the filter is thereby pulsed to a maximum voltage below the breakdown voltage.
  • These current pulses are taken from an intermediate circuit fed by a rectifier by means of a resonant circuit converter dimensioned to the desired pulse width or a frequency-controlled converter with forced quenching and are transformed up.
  • the ripple of the filter voltage is also ensured in that a diode suppresses one polarity of the highly transformed current pulse.
  • DE-OS 27 13 675 proposes a simple power supply in which the basic voltage is supplied by a gate-controlled AC power controller connected to two phases of a three-phase network with a transformer and rectifier connected downstream.
  • the electrodes supplied with the basic direct voltage are connected to the secondary winding of a high-voltage transformer via a coupling capacitor, the primary winding of which is fed by a controllable rectifier device via an inverter in the center point circuit.
  • the invention now provides a method which can be adapted as optimally as possible to the changing operating conditions and which responds quickly, particularly in the event of rollovers.
  • the alternating current is generated with an inverter frequency of a few kilohertz, in particular about 2 kHz or more.
  • a frequency converter is only used in the prior art if a basic DC voltage for generating a ripple aimed for in the deposition process is an AC voltage with the converter frequency without rectification or a sequence of isolated individual pulses which result from the converter-frequency AC voltage by means of a diode by suppressing the negative voltage half-waves are formed, is superimposed, the high-frequency alternating current is used according to the invention in order to initially generate an initially low harmonic DC voltage via the bridge rectifier by means of a practically continuous direct current.
  • a DC link converter is used as the frequency converter, in which the converter connected to the three-phase supply network (e.g. a controllable three-phase rectifier or in particular a three-phase rectifier with a downstream DC converter for controlling the DC link direct current) supplies a direct current which to form the alternating current in time with the converter frequency, a high-frequency inverter with alternating sign is used to switch to the alternating current outputs of the converter.
  • the inverter only needs to be blocked in order to switch off the filter current and the direct current is to be routed past the alternating current outputs of the inverter by means of an idle path using suitable means (e.g. a cross-thyristor between the direct current inputs of the inverter or suitable ignition pulses for series-connected inverter valves).
  • the intermediate circuit current is impressed by the actuator. Its amplitude is practically unchangeable within a period of the converter cycle, so that even in the event of a breakdown there is no significant increase in current at the transformer and therefore no significant recharging of the filter. This prevents arcing and limits the duration of discharge phenomena, which leads to reduced wear on the spray wires and increased service life of the filter.
  • the converter cycle only needs to be blocked for just as many cycle periods as is necessary to deionize the gas.
  • the entire intermediate circuit current is then available again for alternating and recharging the filter, the separating ability of which is therefore quickly restored, thereby the filter efficiency is increased.
  • the high alternating current frequency only a smaller transformer is required, which results in lower construction costs and power losses and more favorable transient behavior in the event of rapid changes in operation.
  • the curve shape of the filter supply voltage which is very different for the respective application, can be adapted via the amplitude control within the DC packets mentioned.
  • An adjustable ripple dU / dt e.g. the basic voltage U of the filter, e.g. depending on the residual content in the medium.
  • the medium is already largely free of foreign substances and very is high impedance.
  • the medium is only able to conduct a low current with a constant filter voltage and thus only absorb a low power.
  • the energy consumption of the filter can be increased by a higher ripple in the supply voltage. It may also be necessary to control the average level of the filter voltage as a function of the residual impurity content; With a higher filter voltage, a separation of residual foreign matter can also be achieved in the outflowing, already largely cleaned gas.
  • the optimal operating point for feeding the filter can be specified in an iterative search process via the control.
  • the filter voltage can be increased automatically by increasing the supplying direct current, as long as the frequency of the breakdowns occurring is not significantly increased.
  • a dependency of the filter voltage on the foreign matter content of the inflowing gas is automatically taken into account, but it can also be carried out by a predetermined function for controlling the alternating current amplitude, e.g. depending on the recorded breakdown frequency.
  • the periodicity of the entire voltage curve can also be controlled via the converter frequency and changed depending on the load condition or the foreign substance content of the inflowing gas.
  • F denotes the electrostatic filter, between the electrodes (plates and spray wires) of which the medium represented by an arrow M (for example flue gas or another exhaust gas) is passed and which has a voltage U, which is detected by a measuring element MU, to be supplied from a supply network N.
  • the input of the filter is connected via a high-voltage rectifier GRH to the secondary winding WS of a transformer, the primary winding WP of which is at the output of the high-frequency clocked frequency converter HF.
  • the high-voltage rectifier GRH is designed as a full-wave rectifier, in particular as an uncontrolled rectifier bridge.
  • An intermediate circuit converter is preferably used as the high-frequency frequency converter HF used.
  • a switch Q indicates a switchable freewheeling path via which inductive currents which occur when the converter is blocked, for example the impressed intermediate circuit current when a current intermediate circuit is used in the converter, can continue to flow.
  • the amplitude of the high-frequency alternating current (ia) can usually be controlled via a corresponding control input of the alternating current controller HF.
  • NF indicates that the amplitude control can also be adjusted via a controllable mains frequency AC power controller.
  • PR summarizes the control and regulation of the high-frequency alternating current in FIG. 1, which, in addition to the actual value U of the filter supply voltage, also contains suitable actual and target values depending on the application.
  • the amplitude, frequency and the "cross firings" of the freewheeling path Q can be used to control the interruptions in the current ia at the output of the AC power controller HF via the output signals.
  • the foreign substance raw gas content (content of the inflowing medium of foreign substances) and / or foreign substance pure gas content (foreign substance content of the outflowing medium) can be used as input signals.
  • the supply voltage and / or supply current of the filter can be optimized, in particular they can be controlled according to a predefined voltage / current characteristic. This characteristic can depending on the foreign substance raw gas content, ie the load state of the filter.
  • the control can react very quickly to any voltage drop and to the start and end of a knocking process, and the ripple of the voltage, ie the fluctuation of the voltage between an upper and lower limit value, can be specified and optimized.
  • controllable rectifier arrangement is shown schematically as a controllable three-phase rectifier bridge DR, which already contains the necessary means to change the intermediate circuit current I (measuring element MI) of an intermediate circuit converter and thus the amplitude of the high-frequency actuator output current with a certain control behavior regulate.
  • the intermediate circuit contains an intermediate circuit choke ZI, which is designed for the structure of the intermediate circuit current and is optionally supplemented by an intermediate circuit capacitor.
  • the downstream inverter AR generates the high-frequency alternating current.
  • the suitable inverter shown in FIG. 2 is known as an inverter with "phase sequence deletion".
  • a two-phase bridge is sufficient, although in principle three-phase and multi-phase bridges can also be possible and possibly also advantageous in order to obtain a direct current that is as complete as possible after step-up transformation and rectification.
  • valves TH1 and TH4 and the valves TH2 and TH3 each ignite simultaneously and delete the previously ignited valves by reloading the commutation capacitors K1 and K2.
  • the transverse thyristor TQ is provided as a means for cross-ignition.
  • the specified intermediate circuit current continues to flow through the choke ZI, but is conducted via the freewheeling path TQ past the primary winding WP, which therefore quickly de-energizes in every phase position of the inverter and, after blocking any number of converter clock pulses, is excited again with the full intermediate circuit current can be. After a breakdown, the required separation voltage can be quickly built up again.
  • cross-firings can also be carried out by firing valves in series. They can also be provided in order to shorten the current carrying time of the valves fired in the normal clock sequence compared to a half period of the inverter output current. The impressed intermediate circuit current itself is practically not affected by these switching operations.
  • the operating point of the power supply is determined in that a setpoint generator SS specifies a setpoint I * for the intermediate circuit current or the amplitude of the output alternating current, the control deviation of which controls the control rate SDR for the controlling means of the controllable rectifier arrangement via a current controller SR .
  • the setpoint I * can in particular be determined on the basis of a current / voltage characteristic stored in the setpoint generator SS, to which the value for the optimum voltage U * is specified by a current control program part PS.
  • U * can be changed periodically, for example as a function of the residual substance content measured on a flue gas probe RG, in order to generate the aforementioned ripple in the filter supply voltage.
  • the optimal basic level for U * can be determined by a flue gas probe EG depending on the foreign substance raw gas content or can be changed in an iterative search procedure so that on the one hand a high degree of separation, on the other hand, a low frequency of breakdowns and voltage drops at the measuring element MU occur.
  • limiting the voltage to the predetermined value U * is advantageous.
  • the setpoint / actual value difference of the supply voltage U is applied to a limit controller BR, which operates on a limit circuit BG that limits the current setpoint.
  • a ramp generator HG is provided at the setpoint input of the limit controller PR, the final value (e.g. depending on the frequency of the voltage breakdowns detected on the voltage measuring element MU) can be changed by a pulse program part PI.
  • the voltage limiting regulator BR enables stable operation of the power supply up to the vicinity of the breakdown point, as a result of which the breakdown frequency is reduced and the filter service life is increased.
  • the pulse program part PI also has the task of specifying the AC output frequency and thus the high frequency of the inverter AR by means of a corresponding, operationally dependent control signal for the inverter tax rate WSt. It also generates the switching signal for the freewheeling path (valve TQ) and the temporary stopping and restarting of the inverter after one Punch.
  • the DC current drawn from the high-voltage rectifier GRH can be interrupted by periodic blocking ("packet formation") and thus a voltage ripple on the filter can also be forced.
  • the coupling capacitor KK shown in FIG. 2 also facilitates the additional connection of such pulses which can be applied to the corresponding input terminals HFI of the filter.
  • a DC chopper with a control valve ST and a freewheeling diode FD is used to control the impressed direct current I, the size of the choke FD being reduced by an actuator frequency in the kHz range (e.g. 5 kHz).
  • the intermediate circuit decouples the network N from reactions of the inverter AD.
  • the input voltage of the direct current controller is advantageously supplied by an uncontrolled three-phase rectifier bridge, which thus represents a symmetrical, practically no reactive current load for the network N.

Landscapes

  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Rectifiers (AREA)
  • Electrostatic Separation (AREA)
  • Ac-Ac Conversion (AREA)
EP86108070A 1985-06-24 1986-06-12 Procédé pour mettre en oeuvre un filtre électrostatique Expired - Lifetime EP0209714B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3522568 1985-06-24
DE19853522568 DE3522568A1 (de) 1985-06-24 1985-06-24 Verfahren zum betrieb eines elektrofilters

Publications (2)

Publication Number Publication Date
EP0209714A1 true EP0209714A1 (fr) 1987-01-28
EP0209714B1 EP0209714B1 (fr) 1990-03-28

Family

ID=6274044

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86108070A Expired - Lifetime EP0209714B1 (fr) 1985-06-24 1986-06-12 Procédé pour mettre en oeuvre un filtre électrostatique

Country Status (5)

Country Link
EP (1) EP0209714B1 (fr)
JP (1) JPS621465A (fr)
AU (1) AU583132B2 (fr)
DE (2) DE3522568A1 (fr)
ZA (1) ZA864662B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999065608A1 (fr) * 1998-06-18 1999-12-23 Kraftelektronik Ab Procede et dispositif de generation de pics de tension dans un precipitateur electrostatique
EP3156132A1 (fr) * 2015-10-15 2017-04-19 RWE Power AG Procédé et dispositif de filtration des poussières de charbon provenant de la vapeur d'échappement du séchage de charbon

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE463353B (sv) * 1989-03-28 1990-11-12 Flaekt Ab Saett att reglera stroempulsmatning till en elektrostatisk stoftavskiljare
SE500810E (sv) * 1993-01-29 2003-04-29 Flaekt Ab Sätt att vid ¦verslag reglera str¦mtillf¦rseln till en elektrostatisk stoftavskiljare
AU700107B2 (en) * 1994-11-08 1998-12-24 Sansha Electric Manufacturing Company, Limited Power supply apparatus
TW283274B (fr) * 1994-11-08 1996-08-11 Sansha Denki Seisakusho Co Ltd
SE518282C2 (sv) 2000-04-12 2002-09-17 Alstom Switzerland Ltd Sätt att skydda strömgenerator för likström mot överspänning vid lastbortfall
CN112362989B (zh) * 2020-10-30 2021-11-02 湖北工业大学 高压静电除尘器火花放电模拟装置及试验方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1923952A1 (de) * 1969-05-10 1970-11-19 Licentia Gmbh Regelverfahren beim elektrostatischen Abscheiden von Aerosol mit einem Elektrofilter,insbesondere fuer Abgasentstaubung
US3641740A (en) * 1969-07-09 1972-02-15 Belco Pollution Control Corp Pulse-operated electrostatic precipitator
FR2191342A1 (fr) * 1972-07-06 1974-02-01 Clemessy Sa Ets
US3984215A (en) * 1975-01-08 1976-10-05 Hudson Pulp & Paper Corporation Electrostatic precipitator and method
FR2385442A1 (fr) * 1977-03-28 1978-10-27 Siemens Ag Dispositif d'alimentation en courant pour depoussiereur electrostatique
EP0034075A2 (fr) * 1980-01-24 1981-08-19 Merlin Gerin Dispositif d'alimentation statique d'un électrofiltre de dépoussiérage électrostatique
US4390831A (en) * 1979-09-17 1983-06-28 Research-Cottrell, Inc. Electrostatic precipitator control
EP0146853A2 (fr) * 1983-12-22 1985-07-03 General Electric Company Circuit de commande de convertisseur pour générateur de rayons X

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD62115A (fr) *
GB1031947A (en) * 1964-09-14 1966-06-02 Hitachi Ltd An electrostatic precipitator
DE2825708B2 (de) * 1978-06-12 1980-06-26 Siemens Ag, 1000 Berlin Und 8000 Muenchen Schaltungsanordnung zum Verringern von Oberwellen im Netzwechselstrom bei Gleichstromverbrauchern, die aus dem Wechselstromnetz gespeist werden
DE2929601A1 (de) * 1979-07-03 1981-01-22 Bbc Brown Boveri & Cie Anspeisungsvorrichtung fuer einen ozonerzeuger
DE3522569A1 (de) * 1985-06-24 1987-01-02 Metallgesellschaft Ag Stromversorgung fuer ein elektrofilter

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1923952A1 (de) * 1969-05-10 1970-11-19 Licentia Gmbh Regelverfahren beim elektrostatischen Abscheiden von Aerosol mit einem Elektrofilter,insbesondere fuer Abgasentstaubung
US3641740A (en) * 1969-07-09 1972-02-15 Belco Pollution Control Corp Pulse-operated electrostatic precipitator
FR2191342A1 (fr) * 1972-07-06 1974-02-01 Clemessy Sa Ets
US3984215A (en) * 1975-01-08 1976-10-05 Hudson Pulp & Paper Corporation Electrostatic precipitator and method
FR2385442A1 (fr) * 1977-03-28 1978-10-27 Siemens Ag Dispositif d'alimentation en courant pour depoussiereur electrostatique
US4390831A (en) * 1979-09-17 1983-06-28 Research-Cottrell, Inc. Electrostatic precipitator control
EP0034075A2 (fr) * 1980-01-24 1981-08-19 Merlin Gerin Dispositif d'alimentation statique d'un électrofiltre de dépoussiérage électrostatique
EP0146853A2 (fr) * 1983-12-22 1985-07-03 General Electric Company Circuit de commande de convertisseur pour générateur de rayons X

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999065608A1 (fr) * 1998-06-18 1999-12-23 Kraftelektronik Ab Procede et dispositif de generation de pics de tension dans un precipitateur electrostatique
GB2357198A (en) * 1998-06-18 2001-06-13 Krafteletronik Ab Method and device for generating voltage peaks in an electrostatic preciptator
US6373723B1 (en) 1998-06-18 2002-04-16 Kraftelektronik Ab Method and device for generating voltage peaks in an electrostatic precipitator
GB2357198B (en) * 1998-06-18 2002-12-04 Krafteletronik Ab Method and device for generating voltage peaks in an electrostatic preciptator
EP3156132A1 (fr) * 2015-10-15 2017-04-19 RWE Power AG Procédé et dispositif de filtration des poussières de charbon provenant de la vapeur d'échappement du séchage de charbon

Also Published As

Publication number Publication date
DE3522568A1 (de) 1987-01-02
DE3669966D1 (de) 1990-05-03
EP0209714B1 (fr) 1990-03-28
AU583132B2 (en) 1989-04-20
AU5920086A (en) 1987-01-08
JPS621465A (ja) 1987-01-07
ZA864662B (en) 1987-02-25

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