EP0341152A1 - Verfahren und Vorrichtung zur Kontrolle der Elektrostatikfiltersverschmutzung - Google Patents

Verfahren und Vorrichtung zur Kontrolle der Elektrostatikfiltersverschmutzung Download PDF

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Publication number
EP0341152A1
EP0341152A1 EP89401246A EP89401246A EP0341152A1 EP 0341152 A1 EP0341152 A1 EP 0341152A1 EP 89401246 A EP89401246 A EP 89401246A EP 89401246 A EP89401246 A EP 89401246A EP 0341152 A1 EP0341152 A1 EP 0341152A1
Authority
EP
European Patent Office
Prior art keywords
voltage
fouling
scale
return
indicating device
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
EP89401246A
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English (en)
French (fr)
Other versions
EP0341152B1 (de
Inventor
Alain Brunet De La Charie
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.)
AAF France SAS
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AAF France SAS
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Filing date
Publication date
Application filed by AAF France SAS filed Critical AAF France SAS
Priority to AT89401246T priority Critical patent/ATE99192T1/de
Publication of EP0341152A1 publication Critical patent/EP0341152A1/de
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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

Definitions

  • the present invention relates to a method and an electronic indicating device for continuously monitoring the level of fouling of electrostatic filters.
  • Electrostatic filters such as those described in French patent application No. 87 16 026 filed by the applicant, have a very high filtering efficiency as long as their filter elements are not excessively charged with pollutants.
  • the operating principle of electro filters static consists of ionizing polluting particles carried in a gas flow through a high density electrostatic field. The ionized particles are then deposited on the surface of the metal collecting elements under the action of the electrostatic field. The gas leaving the filters is thus purified.
  • a high voltage transformer supplied with electric current from the sector of a commercial line (110 V or 220 V alternating for example), provides a nominal rectified voltage for example of 12 kV to supply the ionization element and 6 kV to supply the collector of an electrostatic filter.
  • An electronic assembly inside the transformer, takes part of the rectified current from the high voltage output, at a height of around 110 V.
  • This voltage known as "return voltage”
  • return voltage is used to protect the transformer. Its absence means a malfunction of the transformer, a leak or a short circuit of this voltage to ground.
  • the presence of the return voltage at too low a level implies an abnormal operation of the transformer resulting for example in excessive leaks, since the power is constant.
  • the current monitoring technique consists of supplying, with this return voltage, a neon lamp whose ignition threshold is around 70 V.
  • a photosensitive cell in the presence of this lit lamp supplies, through an amplifier circuit, a device power relay.
  • the neon lamp and photosensitive cell system has been replaced by many manufacturers by a transistor having a reaction threshold at an equivalent level.
  • the present invention therefore relates to a control method and an electronic indicating device for indicating with precision the level of fouling, and therefore the efficiency, of the electrostatic filters.
  • the invention is based, for a given electrostatic filter, on the unexpected and surprising observation in itself that the return voltage of the high voltage transformer is directly linked to the level of fouling of the filter elements thereof:
  • the high voltage transformer supplies the filter elements (collector and more particularly ionization element) in the clean state.
  • a current leak occurs because electrons intended to ionize polluting particles circulate between the ionization element for example in the form of tungsten wires at 12 kV and metal plates connected to ground. This slight leak results in a variation of the high voltage, and therefore of the return voltage.
  • a high voltage transformer giving an empty ionization voltage of 11.5 kV and a return voltage corresponding to 118.3 V, will give a return voltage of 10.2 V with the filtration elements energized (10, 7 kV).
  • a fouling by conductive pollution can occur (dust humidified with water in particular). In this case, the opposite phenomenon occurs and the intensity increases while the voltage decreases.
  • the control method according to the invention allows permanent monitoring of the level of fouling of an electrostatic filter supplied by a high voltage transformer, part of the rectified current is taken from the high voltage output as a return voltage. The variations in the return voltage between a high threshold voltage and a low threshold voltage are detected and the fouling level of the electrostatic filter is deduced therefrom.
  • control method allows the detection of a return voltage greater than the high threshold voltage in order to deduce therefrom the level of fouling by increasing a layer of insulating particles on the filter elements and detecting a return voltage smaller than the low threshold voltage to deduce the level of fouling by increasing a layer of conductive particles on the filter elements.
  • the control method according to the invention also makes it possible to trigger an alarm with time delay when the return voltage is greater than the high threshold voltage or less than the low threshold voltage for a predetermined duration.
  • the return voltage can be visualized using an indicator scale such as a light scale consisting of a series of light-emitting diodes having different ignition thresholds. The evolution of the lighting of the diodes of different positions then visually indicates the progression of the level of fouling of the electrostatic filter over time.
  • the electronic indicating device comprises means for adjusting the high threshold and low threshold voltage; a voltage comparator for comparing the return voltage with respect to the threshold voltages; a voltage subtractor, connected to the adjustment means, supplying an inter-threshold voltage; an adjustable gain amplifier connected to the comparator and the subtractor; an indicator scale connected to the amplifier.
  • the device further comprises a timer, the delay time of which is adjustable; an alarm; a first flip-flop bringing the comparator into contact with either the amplifier or the timer; a second flip-flop bringing the timer into contact with either the amplifier or the alarm.
  • the timer is only triggered when the return voltage is greater than or equal to the high threshold, or less than or equal to the low threshold.
  • the alarm is only triggered when the fault duration of the return voltage, compared to the threshold voltages, is greater than or equal to the predetermined time delay.
  • the indicator scale the extent of which is defined by the threshold voltage, visually indicates a signal voltage, which is the difference between the return voltage and the low threshold voltage delivered by the comparator, for permanent control of the return voltage in a voltage range between the low threshold and high threshold voltages.
  • the indicator scale is preferably at least two-color. To optimize the visibility of the scale, it can be chosen to be bright, for example by means of a plurality of light-emitting diodes (LEDs) having different ignition thresholds.
  • the diodes are arranged in a sequence according to the increasing or decreasing value of the ignition thresholds, so that one can visualize the progress of the fouling of the electrostatic filter by the successive lighting of the light-emitting diodes on the indicator scale.
  • the indicator scale comprises at least one light-emitting diode which lights up only when the alarm is triggered.
  • the alarm can then be replaced by this diode.
  • the means for adjusting the high threshold or low threshold voltages each consist of a potentiometer, and the timer consists of a capacity and a potentiometer.
  • a high voltage transformer (THT) 4 connected to a commercial line 5 supplies by connection 6 an electrostatic filter (FE) 7.
  • the return voltage S taken by the connection 8 on the high voltage output of the transformer 4, is sent to a comparator (C) 9.
  • Two adjustment means (H) 10 and (B) 11 make it possible to adjust respectively a high threshold voltage SH and a voltage low threshold SB.
  • the threshold voltages SH and SB are sent by the connections 12 and 13 to the comparator 9 which is connected by the connection 14 to a first flip-flop 15.
  • flip-flop 15 establishes the connection via connections 14, 16 and 17 between an amplifier (A) 18 and comparator 9 which delivers a signal voltage S-SB; if the voltage S is not between the voltages SB and SH, that is to say that if the voltage S exceeds the permitted threshold voltages, the flip-flop 15 establishes a connection by the connections 14 and 19 between the comparator 9 and a timer (T) 20 whose delay time T o is adjustable.
  • the timer 20 is connected by the connection 21 to a second flip-flop 22.
  • the flip-flop 22 establishes a connection by the connections 21, 23 and 17 between the timer 20 and the amplifier 18, a signal voltage S-SB delivered by the comparator 9 then successively crosses connection 14, flip-flop 15, connection 19, timer 20, connection 21, flip-flop 22, connections 23 and 17 and arrives at amplifier 18. If the fault duration t of the voltage S is greater than or equal to the time delay T o , the flip-flop 22 then triggers via connection 24 an alarm (AL) 25 light or sound and simultaneously causes the supply of the electrostatic filter 7 to be stopped by means not shown.
  • AL alarm
  • a three-color light scale 30 consists of a row of light-emitting diodes.
  • the light scale is made up of ten green diodes 3, four yellow diodes 2 and two red diodes 1.
  • the row of diodes is symmetrical with respect to the middle, in other words in the following order: a red diode 1, two yellow diodes 2, ten green diodes 3, two yellow diodes 2 and a red diode 1.
  • the gain of the amplifier 18 is adjusted to amplify the inter-threshold voltage SH-SB which thus gives a "maximum” reference signal via the connection 31 to calibrate the 'light scale 30 using the mass which constitutes the reference "mini".
  • the maximum usable extent of the light scale 30, that is to say between the two red end diodes 1, is determined by the choice of the gain of the amplifier 18.
  • the signal voltage S-SB after amplification is then in the range defined between the "mini" reference and the "maxi" reference. Each diode has its operating threshold. The signal voltage is indicated by one or two lit diodes.
  • the high threshold SH and low threshold SB voltages, the delay time T0 and the gain of the amplifier 18 are preset to determine the operating limits of the filter and put the amplified signal voltage S-SB in zone 3 of the green diodes 3.
  • the return voltage S tends towards one of the threshold voltages SH or SB, and we see on the light scale 30 a displacement of the lighting of the diodes towards one of the ends.
  • the fouling of the filter elements reaches a significant level and cleaning of these elements is necessary.
  • the flip-flop 22 triggers the alarm 25 and causes by means not shown to immediately stop supplying the electrostatic filter 7 It is also possible to envisage operating the alarm 25 as soon as the ignition goes from a green diode 3 to a yellow diode 2 in order to warn the user in time of the need to clean the dirty filter elements.
  • the indicating device described in the illustrated example may not include the part relating to the alarm, that is to say, the alarm 25, the timer 20 and the two flip-flops 15 and 22.
  • the output 14 of the comparator 9 is directly connected to the amplifier 18. The exceeding of the threshold voltages SH or SB by the return voltage S is then indicated by one of the red diodes 1.
  • the electronic indicating device can be mounted on all devices using a return voltage for the protection of the high voltage transformer. It can replace the electronic mounting of simple conventional protection, inside the control box, with the indicator scale arranged in a suitable location, for example on the door of the box.

Landscapes

  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Filtering Materials (AREA)
EP89401246A 1988-05-06 1989-05-03 Verfahren und Vorrichtung zur Kontrolle der Elektrostatikfiltersverschmutzung Expired - Lifetime EP0341152B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89401246T ATE99192T1 (de) 1988-05-06 1989-05-03 Verfahren und vorrichtung zur kontrolle der elektrostatikfiltersverschmutzung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8806092A FR2630929B1 (fr) 1988-05-06 1988-05-06 Procede et dispositif de controle de l'encrassement de filtres electrostatiques
FR8806092 1988-05-06

Publications (2)

Publication Number Publication Date
EP0341152A1 true EP0341152A1 (de) 1989-11-08
EP0341152B1 EP0341152B1 (de) 1993-12-29

Family

ID=9366060

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89401246A Expired - Lifetime EP0341152B1 (de) 1988-05-06 1989-05-03 Verfahren und Vorrichtung zur Kontrolle der Elektrostatikfiltersverschmutzung

Country Status (4)

Country Link
EP (1) EP0341152B1 (de)
AT (1) ATE99192T1 (de)
DE (1) DE68911743D1 (de)
FR (1) FR2630929B1 (de)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4318152A (en) * 1979-10-05 1982-03-02 United Air Specialists, Inc. Digital high voltage monitor and display for electrostatic precipitators
US4335414A (en) * 1980-10-30 1982-06-15 United Air Specialists, Inc. Automatic reset current cut-off for an electrostatic precipitator power supply

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4318152A (en) * 1979-10-05 1982-03-02 United Air Specialists, Inc. Digital high voltage monitor and display for electrostatic precipitators
US4335414A (en) * 1980-10-30 1982-06-15 United Air Specialists, Inc. Automatic reset current cut-off for an electrostatic precipitator power supply

Also Published As

Publication number Publication date
ATE99192T1 (de) 1994-01-15
FR2630929B1 (fr) 1991-11-29
FR2630929A1 (fr) 1989-11-10
DE68911743D1 (de) 1994-02-10
EP0341152B1 (de) 1993-12-29

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