EP0031056A1 - Method of determining the filter current limit of an electrostatic filter - Google Patents

Method of determining the filter current limit of an electrostatic filter Download PDF

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Publication number
EP0031056A1
EP0031056A1 EP80107568A EP80107568A EP0031056A1 EP 0031056 A1 EP0031056 A1 EP 0031056A1 EP 80107568 A EP80107568 A EP 80107568A EP 80107568 A EP80107568 A EP 80107568A EP 0031056 A1 EP0031056 A1 EP 0031056A1
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Prior art keywords
filter
voltage
current
change
control voltage
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German (de)
French (fr)
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EP0031056B1 (en
Inventor
Helmut Dipl.-Ing. Herklotz
Günter Mehler
Franz Dipl.-Ing. Neulinger
Helmut Dipl.-Ing. Schummer
Horst Dr. Dipl.-Ing. Daar
Walter Dipl.-Ing. Schmidt
Heinrich Winkler
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GEA Group AG
Siemens AG
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Metallgesellschaft AG
Siemens AG
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    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S323/00—Electricity: power supply or regulation systems
    • Y10S323/903—Precipitators

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  • the invention relates to a method for determining the filter current limit of an electrostatic filter, which e.g. is fed from an AC network via a thyristor actuator and in which the control voltage of the actuator depends on filter operating values up to. can be changed to a predetermined filter current limit.
  • This generic term refers to a control method, as described in more detail, for example, in Siemens magazine 1971, pp. 567-572.
  • filter current limitation In addition to this nominal current limitation, another type of filter current limitation is of interest. Under certain operating conditions of the electrostatic filter, e.g. In sintering plants or in bypass operation in the cement plant, either a filter voltage maximum or a filter voltage saturation can occur.
  • the goal of the "current limitation" function is to determine the maximum or saturation in order to prevent unnecessarily high filter currents.
  • the object of the present invention is the filter depending on the operating state of the filter. Determine current limit so that there is an optimal ratio of separator performance to energy consumption.
  • This object is achieved in that during the filter operation in predetermined time intervals which the control voltage is automatically changed in predetermined steps to a minimum value and from here back to the original value, that the ratios of changing the filter voltage to changing the control voltage and changing the filter voltage to change the filter current are continuously calculated and that the value falls below predefined limit values of these ratios or in the event of a change in the sign of two successive ratio values, the associated filter current determines the filter current limit.
  • the filter current limit from which a further increase in the filter performance is prevented is advantageously selected such that it is 3 to 15% above the filter current at which the criteria mentioned above are present.
  • the values of filter current and filter voltage associated with each step are also advantageously stored and the filter characteristic that can be determined from them is displayed. On the one hand, this gives the operating personnel information about the operating behavior of the filter and, on the other hand, it can be of interest for higher-level optimization strategies of several filters.
  • the filter characteristic is recorded the ratio of the change in the filter voltage and the change in the filter current to the change in the control voltage is also advantageously calculated. If it is found that the relative change in the filter voltage when the control voltage changes is greater than the change in the filter current, a defined voltage drop is carried out when the filter breaks down. If the reverse occurs, a defined current reduction is carried out in the event of breakdowns. In this way it can be decided whether the current or the voltage should be lowered by a predetermined amount in response to a breakthrough so that, for example, one stays within the predetermined breakdown frequency.
  • the times for the recording of the filter characteristic are selected such that in each case only. the control voltage is varied for a filter. E.g. Assuming that the filter characteristic is recorded every 15 minutes and the recording takes one second each, it should be understood that the separating operation is practically unaffected by this.
  • the elec trofilter 1 via high-voltage rectifier 2, high-voltage transformer 3 and a thyristor actuator 4 consisting of antiparallel-connected thyristors, fed from an AC voltage network 6.
  • the control voltage U St for the thyristor actuator 4 is determined by a controller 5 so that optimum filter operating values result.
  • a control of this type is described, for example, in the article mentioned at the beginning.
  • this controller 5 is designed today as a digital controller, ie essentially consists of a microcomputer system.
  • filters 7 and 8 are indicated.
  • the digital controllers 5 of the individual filters run via a data bus 92 with a superordinate control computer 9, to which a display 91 is assigned.
  • the individual operating parameters and setting values can be specified from the host computer 9 and optimization strategies for the filters can be calculated if necessary.
  • the filter current function as a function of the peak voltage or the arithmetic mean or the RMS value of the filter voltage is referred to below as the filter characteristic. It is among others dependent on the current operating conditions of the electrostatic filter and must therefore be cyclical, e.g. at intervals of 15 minutes, at a time when the breakthrough limit is not being scanned.
  • the current control voltage U St is stored and this value is output again to the thyristor controller 4 after completion of the filter characteristic recording.
  • the assigned values of filter voltage and filter current are saved.
  • the control voltage is reduced by a constant increment ⁇ U St until a minimum value of, for example, 1 volt is reached, which is given by the lower possible control voltage.
  • the control voltage U St is then raised from this minimum value with the same increment back to the current value at the start of the recording.
  • the values of the filter voltage U Fi , F i + 1 etc. and the filter current I F assigned to each control voltage U St are stored during the lowering phase and arithmetically averaged with the corresponding values of the start-up phase. The characteristic calculated from this can then be displayed on the display 91.
  • a filter voltage maximum exists when the sign of a filter voltage increment is not the same as the sign of the next filter voltage increment when the control voltage changes (cf. curve a), ie, therefore, a sign or where i denotes the sampling points of the filter characteristic.
  • the maximum filter current and the filter and control voltage values assigned to it are stored. You limit e.g. the setting range of a flue gas density control or the scanning of the breakdown limit.
  • the stop point can be determined from the recording of the filter characteristic, i.e. the point from which a defined voltage or current drop should advantageously be made in the event of a breakdown.
  • the changeover point assumed as a criterion for this choice is determined by calculating the ratio of the change in filter voltage to changing the control voltage and the ratio of changing the filter current to changing the control voltage, and by comparing these two ratio values. If there is a relatively greater reaction of the filter current than the filter voltage when the control voltage changes, then breakdowns with a defined current reduction are used, since this is then more favorable in terms of process technology. The reverse applies if the relative voltage change is greater than the relative current change when the control voltage changes.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Electrostatic Separation (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
  • Networks Using Active Elements (AREA)

Abstract

The automatic recording of the current-voltage characteristic of an electrostatic filter in which the characteristic obtained upon stepwise variation of the control is displayed to the operating personnel and at the same time saturation phenomena and voltage maxima are picked up.

Description

Die Erfindung bezieht sich auf ein Verfahren zum Ermitteln der Filterstromgrenze eines Elektrofilters, das z.B. über ein Thyristorstellglied aus einem Wechselstromnetz gespeist ist und bei dem die Steuerspannung des Stellgliedes abhängig von Filterbetriebswerten bis. zu einer vorgegebenen Filterstromgrenze änderbar ist.The invention relates to a method for determining the filter current limit of an electrostatic filter, which e.g. is fed from an AC network via a thyristor actuator and in which the control voltage of the actuator depends on filter operating values up to. can be changed to a predetermined filter current limit.

Mit diesem Oberbegriff wird auf ein Steuerverfahren Bezug genommen, wie es beispielsweise in der Siemens-Zeitschrift 1971, S. 567 - 572 näher beschrieben ist.This generic term refers to a control method, as described in more detail, for example, in Siemens magazine 1971, pp. 567-572.

Da die Wirksamkeit eines Elektrofilters etwa mit dem Quadrat der anliegenden Spannung steigt, muß man bestrebt sein, die Filterspannung so hoch wie möglich einzustellen. Die Durchbruchsfestigkeit des Gases begrenzt allerdings diese Spannung nach oben. Da es außer dem Durchbruch selbst kein Kriterium für die maximal mögliche Spannung gibt, müssen in bestimmten Zeitabständen Durchbrüche herbeigeführt werden, um diese Grenze abzutasten. Da sich die Durchbruchsgrenze sehr schnell ändern kann, muß relativ häufig abgetastet werden.Since the effectiveness of an electrostatic filter increases approximately with the square of the applied voltage, efforts must be made to set the filter voltage as high as possible. The breakdown strength of the gas be however, this tension limits upwards. Since there is no criterion for the maximum possible voltage apart from the breakdown itself, breakdowns must be made at certain time intervals in order to sense this limit. Since the breakthrough limit can change very quickly, sampling must be done relatively frequently.

Bei einer derartigen durchschlagabhängigen Regelung muß dafür gesorgt werden, daß die Strombelastbärkeit der Anlage nicht überschritten wird. Bei der bekannten Anordnung wird durch eine einstellbare Strombegrenzung bei Erreichen des eingestellten Wertes ein weiteres Ansteigen der Steuerspannung verhindert. Steigt der Strom wegen einer Verkleinerung des Staubwiderstandes an, dann bewirkt die Strombegrenzung ein langsames Absenken der Steuerspannung, bis der Strom auf seinen eingestellten Wert abgesunken ist.With such a breakdown-dependent control, it must be ensured that the current carrying capacity of the system is not exceeded. In the known arrangement, a further increase in the control voltage is prevented by an adjustable current limitation when the set value is reached. If the current increases due to a reduction in the dust resistance, the current limitation causes the control voltage to slowly decrease until the current has dropped to its set value.

Neben dieser Nennstrombegrenzung ist noch eine andere Art der Filterstrombegrenzung von Interesse. Unter bestimmten Betriebsbedingungen des Elektrofilters, z.B. in Sinteranlagen oder im Bypassbetrieb im Zementwerk kann entweder ein Filterspannungsmaximum oder auch eine Filterspannungssättigung eintreten. Hier 'ist das Ziel der Funktion "Strombegrenzung" das Maximum bzw. die Sättigung festzustellen, um unnötig hohe Filterströme zu verhindern.In addition to this nominal current limitation, another type of filter current limitation is of interest. Under certain operating conditions of the electrostatic filter, e.g. In sintering plants or in bypass operation in the cement plant, either a filter voltage maximum or a filter voltage saturation can occur. Here, the goal of the "current limitation" function is to determine the maximum or saturation in order to prevent unnecessarily high filter currents.

Die Aufgabe der vorliegenden Erfindung besteht darin, die vom Betriebszustand des Filters abhängige Filter- . stromgrenze so zu bestimmen, daß sich ein optimales Verhältnis von Abscheiderleistung zum Energieaufwand ergibt.The object of the present invention is the filter depending on the operating state of the filter. Determine current limit so that there is an optimal ratio of separator performance to energy consumption.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß während des Filterbetriebes in vorgegebenen Zeitabständen die Steuerspannung selbsttätig in vorgegebenen Schritten bis zu einem Minimalwert und von hier aus wieder bis zum ursprünglichen Wert geändert wird, daß dabei fortlaufend die Verhältnisse von Änderung der Filterspannung zu Änderung der Steuerspannung und Änderung der Filterspannung zur Änderung des Filterstromes berechnet werden und daß beim Unterschreiten vorgegebener Grenzwerte dieser Verhältnisse oder bei einer Vorzeichenänderung zweier aufeinanderfolgender Verhältniswerte der jeweils zugehörige Filterstrom die Filterstromgrenze bestimmt.This object is achieved in that during the filter operation in predetermined time intervals which the control voltage is automatically changed in predetermined steps to a minimum value and from here back to the original value, that the ratios of changing the filter voltage to changing the control voltage and changing the filter voltage to change the filter current are continuously calculated and that the value falls below predefined limit values of these ratios or in the event of a change in the sign of two successive ratio values, the associated filter current determines the filter current limit.

Auf diese Weise lassen sich Sättigungserscheinungen bzw. Maximalwerte der Filterspannung erkennen, ab denen eine weitere Steigerung der Energiezufuhr zum Filter, d.h. Stromerhöhung, keine wesentliche Erhöhung der Abscheiderleistung mehr ergibt.In this way, saturation phenomena or maximum values of the filter voltage can be recognized, from which a further increase in the energy supply to the filter, i.e. Current increase, no significant increase in separator performance results.

Das Erkennen derartiger Grenzwerte ist im Hinblick auf einen wirtschaftlichen Betrieb des Elektrofilters von großem Interesse.The detection of such limit values is of great interest with regard to the economical operation of the electrostatic filter.

Vorteilhafterweise wird die Filterstromgrenze, ab der eine weitere Steigerung der Filterleistung verhindert wird, etwa so gewählt, daß sie 3 bis 15% über dem Filterstrom liegt, an dem die vorstehend erwähnten Kriterien vorliegen.The filter current limit from which a further increase in the filter performance is prevented is advantageously selected such that it is 3 to 15% above the filter current at which the criteria mentioned above are present.

Vorteilhafterweise werden ferner die zu jedem Schritt gehörigen Werte von Filterstrom und Filterspannung gespeichert und die daraus bestimmbare Filtercharakteristik angezeigt. Dies gibt zum einen dem Bedienungspersonal einen Aufschluß über das Betriebsverhalten des Filters und kann andererseits von Interesse für übergeordnete Optimierungsstrategien mehrerer Filter sein. Bei der Aufnahme der Filtercharakteristik wird ferner vorteilhafterweise das Verhältnis von Änderung der Filterspannung und Änderung des Filterstromes zur Änderung der Steuerspannung berechnet. Ergibt sich, daß die relative Änderung der Filterspannung bei einer Änderung der Steuerspannung größer ist als die Änderung des Filterstromes, so wird bei Durchschlägen des Filters eine definierte Spannungsabsenkung vorgenommen. Ergibt sich der umgekehrte Fall, so wird bei Durchschlägen eine definierte Stromabsenkung vorgenommen. Auf diese Weise kann entschieden werden, ob als Reaktion auf einen Durchbruch zweckmäßigerweise der Strom oder die Spannung um einen vorgegebenen Betrag abzusenken ist, damit man z.B. im Rahmen der vorgegebenen Durchschlagshäufigkeit bleibt.The values of filter current and filter voltage associated with each step are also advantageously stored and the filter characteristic that can be determined from them is displayed. On the one hand, this gives the operating personnel information about the operating behavior of the filter and, on the other hand, it can be of interest for higher-level optimization strategies of several filters. When the filter characteristic is recorded the ratio of the change in the filter voltage and the change in the filter current to the change in the control voltage is also advantageously calculated. If it is found that the relative change in the filter voltage when the control voltage changes is greater than the change in the filter current, a defined voltage drop is carried out when the filter breaks down. If the reverse occurs, a defined current reduction is carried out in the event of breakdowns. In this way it can be decided whether the current or the voltage should be lowered by a predetermined amount in response to a breakthrough so that, for example, one stays within the predetermined breakdown frequency.

Vorteilhafterweise werden ferner bei Vorhandensein mehrerer hintereinander oder parallelgeschalteter Filter die Zeitpunkte für die Aufnahme der Filtercharakteristik so gewählt, daß jeweils nur. bei einem Filter die Steuerspannung variiert wird. Sei z.B. angenommen, daß die Filtercharakteristik alle 15 Minuten aufgenommen wird und die Aufnahme jeweils eine Sekunde dauert, ist einzus hen, daß hierdurch der Abscheidebetrieb praktisch nicht berührt wird.Advantageously, if there are a plurality of filters connected in series or in parallel, the times for the recording of the filter characteristic are selected such that in each case only. the control voltage is varied for a filter. E.g. Assuming that the filter characteristic is recorded every 15 minutes and the recording takes one second each, it should be understood that the separating operation is practically unaffected by this.

Anhand eines in der Zeichnung dargestellten Ausführungsbeispieles sei die Erfindung näher erläutert; es zeigen:

  • Figur 1 das elektrische Schaltungsschema einer Filteranlage mit Steuerung,
  • Figur 2 zwei Filtercharakteristiken, d.h. Abhängigkeit von Filterspannung und Filterstrom und
  • Figur 3 den Verlauf der Filterspannung in Abhängigkeit von der Steuerspannung am Stellglied.
The invention will be explained in more detail with reference to an embodiment shown in the drawing; show it:
  • 1 shows the electrical circuit diagram of a filter system with control,
  • Figure 2 two filter characteristics, ie dependence on filter voltage and filter current and
  • Figure 3 shows the course of the filter voltage depending on the control voltage on the actuator.

Bei der in Figur 1 gezeigten Anordnung wird das Elektrofilter 1 über Hochspannungsgleichrichter 2, Hochspannungstransformator 3 und ein aus antiparallelgeschalteten Thyristoren bestehendes Thyristorstellglied 4 aus einem Wechselspannungsnetz 6 gespeist. In Abhängigkeit von Filterbetriebswerten, wie z.B. Primärstrom und Primärspannung, Sekundärspannung, Sekundärstrom und Zahl der Durchschläge im Filter, wird durch einen Regler 5 die Steuerspannung USt für das Thyristorstellglied 4 so bestimmt, daß sich optimale Filterbetriebswerte ergeben. Eine Steuerung dieser Art ist beispielsweise in dem eingangs genannten Aufsatz beschrieben. Im Zuge der heutigen Digitalisierung der Technik ist es von Vorteil, wenn dieser Regler 5 heute als digitaler Regler ausgebildet wird, d.h. im wesentlichen aus einem Mikrocomputersystem besteht.In the arrangement shown in Figure 1, the elec trofilter 1 via high-voltage rectifier 2, high-voltage transformer 3 and a thyristor actuator 4 consisting of antiparallel-connected thyristors, fed from an AC voltage network 6. Depending on the filter operating values, such as primary current and primary voltage, secondary voltage, secondary current and number of breakdowns in the filter, the control voltage U St for the thyristor actuator 4 is determined by a controller 5 so that optimum filter operating values result. A control of this type is described, for example, in the article mentioned at the beginning. In the course of today's digitalization of technology, it is advantageous if this controller 5 is designed today as a digital controller, ie essentially consists of a microcomputer system.

Zusätzlich zu dem gerade beschriebenen Filter sind noch weitere Filter 7 und 8 angedeutet. Die Digitalregler 5 der einzelnen Filter verkehren über einen Datenbus 92 mit einem übergeordneten Leitrechner 9, dem eine Anzeige 91 zugeordnet ist. Vom Leitrechner 9 her können die einzelnen Betriebsparameter und Einstellwerte vorgegeben werden und gegebenenfalls Optimierungsstrategien für die Filter berechnet werden.In addition to the filter just described, further filters 7 and 8 are indicated. The digital controllers 5 of the individual filters run via a data bus 92 with a superordinate control computer 9, to which a display 91 is assigned. The individual operating parameters and setting values can be specified from the host computer 9 and optimization strategies for the filters can be calculated if necessary.

Die Funktion Filterstrom 'als Funktion der Scheitelspannung bzw. des arithmetischen Mittelwertes oder des Effektivwertes der Filterspannung sei nachfolgend als Filtercharakteristik bezeichnet. Sie ist u.a. von dem momentanen Betriebsverhältnissen des Elektrofilters abhängig und muß daher zyklisch, z.B. im Abstand von 15 Minuten ermittelt werden, und zwar zu einem Zeitpunkt, an dem nicht gerade die Durchschlagsgrenze abgetastet wird.The filter current function as a function of the peak voltage or the arithmetic mean or the RMS value of the filter voltage is referred to below as the filter characteristic. It is among others dependent on the current operating conditions of the electrostatic filter and must therefore be cyclical, e.g. at intervals of 15 minutes, at a time when the breakthrough limit is not being scanned.

Bei der Aufnahme der Filtercharakteristik wird zunächst die aktuelle Steuerspannung USt gespeichert und dieser Wert nach Abschluß der Filtercharakteristikaufnahme erneut an den Thyristorsteller 4 ausgegeben. Gleichzeitig werden die zugeordneten Werte von Filterspannung und Filterstrom gespeichert. Anschließend wird zu Beginn jeder Halbwelle der Primärspannung die Steuerspannung um ein konstantes Inkrement ΔUSt vermindert bis zum Erreichen eines Minimalwertes von z.B. 1 Volt, der durch die untere mögliche Steuerspannung gegeben ist. Anschließend wird die Steuerspannung USt von diesem Minimalwert mit dem gleichen Inkrement wieder bis zum aktuellen Wert am Beginn der Aufnahme hochgefahren. Sei z. B. angenommen, daß die gesamte Filtercharakteristik in 32 Stützpunkte unterteilt sei, was für die normalen Betriebsverhältnisse völlig ausreicht, so ist dabei mit einer Maximaldauer von etwa 0,5 bis 1 Sekunde für die Aufnahme der Filtercharakteristik zu rechnen.When recording the filter characteristic is first the current control voltage U St is stored and this value is output again to the thyristor controller 4 after completion of the filter characteristic recording. At the same time, the assigned values of filter voltage and filter current are saved. Then, at the beginning of each half-wave of the primary voltage, the control voltage is reduced by a constant increment ΔU St until a minimum value of, for example, 1 volt is reached, which is given by the lower possible control voltage. The control voltage U St is then raised from this minimum value with the same increment back to the current value at the start of the recording. Be z. B. assuming that the entire filter characteristic is divided into 32 bases, which is completely sufficient for normal operating conditions, a maximum duration of about 0.5 to 1 second is to be expected for the recording of the filter characteristic.

Die jeder Steuerspannung USt zugeordneten Werte der Filterspannung UFi , Fi+1 usw. und des Filterstromes IF werden während der Absenkphase gespeichert und mit den entsprechenden Werten der Hochlaufphase arithmetisch gemittelt. Die hieraus berechnete Charakteristik kann dann in der Anzeige 91 angezeigt werden.The values of the filter voltage U Fi , F i + 1 etc. and the filter current I F assigned to each control voltage U St are stored during the lowering phase and arithmetically averaged with the corresponding values of the start-up phase. The characteristic calculated from this can then be displayed on the display 91.

Nach Erreichen des Anfangswertes der Steuerspannung wird geprüft, ob die Filterstrombegrenzung verändert werden muß und der aktuelle Umschaltpunkt zwischen Strom- und Spannungsabsenkung bei Durchschlägen berechnet. In diesem Zusammenhang sei noch bemerkt, daß beim Auftreten eines Durchschlages während der Aufnahme der Filtercharakteristik die normale Spannungs- bzw. Stromabsenkungsroutine eingreift und die Aufnahme der Charakteristik abgebrochen wird, da während des eigentlichen Durchschlages keine brauchbaren Verhältniswerte berechenbar sind.After reaching the initial value of the control voltage, it is checked whether the filter current limitation has to be changed and the current switchover point between current and voltage reduction in the event of breakdowns is calculated. In this context, it should also be noted that if a breakdown occurs during the recording of the filter characteristic, the normal voltage or current reduction routine intervenes and the recording of the characteristic is interrupted, since no usable ratio values can be calculated during the actual breakdown.

In Figur 2 sind zwei Filtercharakteristiken, d.h. Filterstrom IF in Abhängigkeit von der Filterspannung UF aufgetragen, und zwar zeigt die Kurve a eine Filtercharakteristik mit einem Spannungsmaximum und die Kurve b eine Filtercharakteristik mit Sättigungserscheinungen. Eine Filterspannungssättigung liegt vor, wenn,

Figure imgb0001
oder - vgl. Figur 3 -
Figure imgb0002
ist Wobei Δ UFi, Δ IFi und Δ USti normierte Inkremente von Filterspannung, Filterstrom und Steuerspannung im Meßpunkt i sind, mit Δ ≤ i ≤ 32Two filter characteristics, ie filter current I F as a function of the filter voltage U F, are plotted in FIG. 2, namely curve a shows a filter characteristic with a voltage maximum and curve b shows a filter characteristic with saturation phenomena. Filter voltage saturation exists if,
Figure imgb0001
 or - cf. Figure 3 -
Figure imgb0002
 where Δ U Fi , Δ I Fi and Δ U Sti are standardized increments of filter voltage, filter current and control voltage at measuring point i, with Δ ≤ i ≤ 32

Als Schwellwert sei z.B.ε= 0,005 vereinbart. Wird also während der Aufnahme der Filtercharakteristik dieser Wert ε unterschritten, so wird in diesem Fall der maximale Filtergrenzstrom auf den Wert TFmax = X . I'F begrenzt, wobei I'F derjenige Wert ist, an dem; das betreffende Kriterium festgestellt wurde und x zwischen 103% und 115% gewählt ist.For example, a threshold value of = 0.005 was agreed. If this value falls below ε during the recording of the filter characteristic, the maximum filter limit current in this case becomes the value T Fmax = X. I ' F limited, where I' F is the value at which; the relevant criterion has been determined and x is selected between 103% and 115%.

Ein Filterspannungsmaximum liegt vor, wenn das Vorzeichen eines Filterspannungsinkrementes ungleich dem Vorzeichen des nächsten Filterspannungsinkrementes bei veränderter Steuerspannung ist (vgl. Kurve a), d.h. also Vorzeichen

Figure imgb0003
Figure imgb0004
oder
Figure imgb0005
wobei mit i die Abtastpunkte der Filtercharakteristik bezeichnet sind. Auch in diesem Fall wird dermaximale Filterstrom auf den Wert begrenzt: IFmax = X . I'F A filter voltage maximum exists when the sign of a filter voltage increment is not the same as the sign of the next filter voltage increment when the control voltage changes (cf. curve a), ie, therefore, a sign
Figure imgb0003
Figure imgb0004
 or
Figure imgb0005
 where i denotes the sampling points of the filter characteristic. In this case too, the maximum filter current is limited to the value: I Fmax = X. I ' F

Der maximale Filterstrom sowie die ihm zugeordneten Werte der Filter-und der Steuerspannung werden gespeichert. Sie begrenzen z.B. den Stellbereich einer Rauchgasdichteregelung oder das Abtasten der Durchschlagsgrenze.The maximum filter current and the filter and control voltage values assigned to it are stored. You limit e.g. the setting range of a flue gas density control or the scanning of the breakdown limit.

Zusätzlich kann noch aus der Aufnahme der Filtercharakteristik der Ums-haltpunkt festgelegt werden, d.h. der Punkt, ab dem bei einem Durchschlag vorteilhafterweise eine definierte Spannungs- oder Stromabsenkung vorgenommen werden soll. Der als Kriterium für diese Wahl angenommene Umschaltpunkt wird dadurch ermittelt, daß das Verhältnis von Änderung der Filterspannung zur Änderung der Steuerspannung und das Verhältnis von Änderung des Filterstromes zur Änderung der Steuerspannung berechnet wird und daß diese beiden Verhältniswerte miteinander verglichen werden. Ergibt sich eine relativ größere Reaktion des Filterstromes als der Filterspannung bei Änderung der Steuerspannung, so wird bei Durchschlägen mit definierter Stromabsenkung gearbeitet, da dies dann verfahrenstechnisch günstiger ist. Das umgekehrte gilt, falls die relative Spannungsänderung höher als die relative Stromänderung bei Änderung der Steuerspannung ist.In addition, the stop point can be determined from the recording of the filter characteristic, i.e. the point from which a defined voltage or current drop should advantageously be made in the event of a breakdown. The changeover point assumed as a criterion for this choice is determined by calculating the ratio of the change in filter voltage to changing the control voltage and the ratio of changing the filter current to changing the control voltage, and by comparing these two ratio values. If there is a relatively greater reaction of the filter current than the filter voltage when the control voltage changes, then breakdowns with a defined current reduction are used, since this is then more favorable in terms of process technology. The reverse applies if the relative voltage change is greater than the relative current change when the control voltage changes.

Claims (5)

1. Verfahren zum Ermitteln der Filterstromgrenze eines Elektrofilters, das über ein Stellglied aus einem Wechselstromnetz gespeist ist und bei dem die Steuerspannung des Stellgliedes abhängig von Filterbetriebswerten bis zu einer vorgegebenen Filterstromgrenze änderbar ist, dadurch gekennzeichnet, daß während des Filterbetriebes in vorgegebenen Zeitabständen die Steuerspannung (ÜSt) in vorgegebenen Schritten ( Δ USt) bis zu einem Minimalwert und von hier aus wieder bis zum ursprünglichen Wert geändert wird, daß da-bei fortlaufend die Verhältnisse von Änderung der Filterspannung (UF) zur Änderung der Steuerspannung und Änderung der Filterspannung zur Änderung des Filterstromes (IF) berechnet werden und daß bei Unterschreiten vorgegebener Grenzwerte (ε) dieser Verhältnisse oder bei einer Vorzeichenänderung zweier aufeinanderfolgender Verhältniswerte der jeweils zugehörige Filterstrom (I'F) die Filterstromgrenze (IFmax) bestimmt.1.Method for determining the filter current limit of an electrostatic filter, which is fed via an actuator from an AC network and in which the control voltage of the actuator can be changed up to a predetermined filter current limit depending on filter operating values, characterized in that during control operation the control voltage ( ÜSt) is changed in predetermined steps (Δ U St ) to a minimum value and from here back to the original value, so that the ratios of changing the filter voltage (UF) to change the control voltage and changing the filter voltage to change continuously of the filter current (I F ) are calculated and that if the specified limit values (ε) fall below these ratios or if the sign of two successive ratio values changes, the associated filter current (I ' F ) determines the filter current limit (IF max ). 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Filterstromgrenze (IFmax) zu etwa 3 bis 15% über demjenigen Filterstrom (I'F) liegt, bei dem eines der Kriterien erfüllt ist.2. The method according to claim 1, characterized in that the filter current limit (I Fmax ) is about 3 to 15% above that filter current (I ' F ) at which one of the criteria is met. 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die zu jedem Schritt gehörigen Werte von Filterstrom (IF) und Filterspannung (UF) gespeichert werden und die resultierende Filtercharakteristik angezeigt wird.3. The method according to claim 1, characterized in that the values of filter current (I F ) and filter voltage (U F ) associated with each step are stored and the resulting filter characteristic is displayed. 4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß bei Vorhandensein mehrerer hintereinander oder parallelgeschalteter Filter (1, 7, 8) die Zeitpunkte für die Aufnahme der Filtercharakteristik so gewählt sind, daß jeweils nur bei einem Filter die Steuerspannung (USt) variiert wird.4. The method according to claim 1, characterized in that in the presence of several filters connected in series or in parallel (1, 7, 8), the times for the recording of the filter characteristic are selected are that the control voltage (U St ) is only varied in one filter. 5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Verhältnis von Änderung der Filterspannung (UF) und Änderung des Filterstromes (IF) zur Änderung der Steuerspannung (USt) berechnet wird und durch den jeweils größeren relativen Wert festgelegt ist,. ob als Reaktion auf die Durchschläge des Filters eine definierte Spannungs- oder Stromänderung durchgeführt wird.5. The method according to claim 1, characterized in that the ratio of the change in the filter voltage (U F ) and the change in the filter current (I F ) to the change in the control voltage (U St ) is calculated and determined by the larger relative value, respectively. whether a defined voltage or current change is carried out in response to the breakdowns of the filter.
EP80107568A 1979-12-11 1980-12-03 Method of determining the filter current limit of an electrostatic filter Expired EP0031056B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80107568T ATE4676T1 (en) 1979-12-11 1980-12-03 PROCEDURE FOR DETERMINING THE FILTER CURRENT LIMIT OF AN ELECTRICAL FILTER.

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DE2949786 1979-12-11
DE19792949786 DE2949786A1 (en) 1979-12-11 1979-12-11 METHOD FOR DETERMINING THE FILTER CURRENT LIMIT OF AN ELECTROFILTER

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EP0031056A1 true EP0031056A1 (en) 1981-07-01
EP0031056B1 EP0031056B1 (en) 1983-09-21

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US (1) US4354860A (en)
EP (1) EP0031056B1 (en)
JP (1) JPS56124462A (en)
AT (1) ATE4676T1 (en)
AU (1) AU535224B2 (en)
DE (2) DE2949786A1 (en)
ZA (1) ZA807729B (en)

Cited By (4)

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EP0039817A1 (en) * 1980-05-08 1981-11-18 Metallgesellschaft Ag Method of regulating the voltage of an electrical precipitator in a plant
EP0039816A1 (en) * 1980-05-09 1981-11-18 Metallgesellschaft Ag Process for the continuous optimisation of the electrical work point in a wet electrostatic filter
US4486704A (en) * 1981-07-28 1984-12-04 Flakt Aktiebolag Control device for an electrostatic dust separator
DE3910123C1 (en) * 1989-03-29 1990-05-23 Walther & Cie Ag, 5000 Koeln, De Method for optimising the energy consumption when operating an electrostatic precipitator

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DE3169116D1 (en) * 1980-12-17 1985-03-28 Smidth & Co As F L Method of controlling operation of an electrostatic precipitator
EP0097161B1 (en) * 1981-07-24 1987-03-18 TRUCE, Rodney John Detecting, measuring and applying back corona parameters on an electrostatic precipitator
SE430472B (en) * 1982-03-25 1983-11-21 Flaekt Ab DEVICE FOR IN AN ELECTROFILTER SYSTEM WITH MULTIPLE ELECTRODE GROUPS MAKE A REGULATION OF THE POWER AND / OR VOLTAGE WIRES CONNECTED TO RESP ELECTRODROUP GROUP SAY THAT TOTAL ENERGY REQUIREMENT CAN BE MINIMIZED.
US4522635A (en) * 1982-10-19 1985-06-11 Flakt Aktiebolag Method and device for varying a d.c. voltage connected to an electrostatic dust separator
DE3301772A1 (en) * 1983-01-20 1984-07-26 Walther & Cie AG, 5000 Köln METHOD AND DEVICE FOR AUTOMATIC VOLTAGE REGULATION OF AN ELECTROSTATIC FILTER
GB8431293D0 (en) * 1984-12-12 1985-01-23 Smidth & Co As F L Controlling pulse frequency of electrostatic precipitator
DE3526754A1 (en) * 1985-07-26 1987-01-29 Metallgesellschaft Ag CONTROL METHOD FOR AN ELECTRIC FILTER
US5378978A (en) * 1993-04-02 1995-01-03 Belco Technologies Corp. System for controlling an electrostatic precipitator using digital signal processing
DE19511604C2 (en) * 1995-03-30 1999-08-12 Babcock Prozessautomation Gmbh Method for continuously optimizing the operating state of an electrostatic filter
US7081152B2 (en) * 2004-02-18 2006-07-25 Electric Power Research Institute Incorporated ESP performance optimization control
DE102004036210B4 (en) * 2004-07-26 2006-08-31 Siemens Ag Control device and control method for electrostatic precipitators with a configurable number of parallel and serial filter zones

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GB1424346A (en) * 1972-11-16 1976-02-11 Lodge Cottrell Ltd Automatic voltage controller
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0039817A1 (en) * 1980-05-08 1981-11-18 Metallgesellschaft Ag Method of regulating the voltage of an electrical precipitator in a plant
EP0039816A1 (en) * 1980-05-09 1981-11-18 Metallgesellschaft Ag Process for the continuous optimisation of the electrical work point in a wet electrostatic filter
US4486704A (en) * 1981-07-28 1984-12-04 Flakt Aktiebolag Control device for an electrostatic dust separator
DE3910123C1 (en) * 1989-03-29 1990-05-23 Walther & Cie Ag, 5000 Koeln, De Method for optimising the energy consumption when operating an electrostatic precipitator

Also Published As

Publication number Publication date
US4354860A (en) 1982-10-19
JPS618746B2 (en) 1986-03-17
JPS56124462A (en) 1981-09-30
ZA807729B (en) 1981-12-30
AU535224B2 (en) 1984-03-08
DE3064980D1 (en) 1983-10-27
AU6522680A (en) 1981-06-18
EP0031056B1 (en) 1983-09-21
ATE4676T1 (en) 1983-10-15
DE2949786A1 (en) 1981-06-19

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