EP0135516B1 - Verfahren und vorrichtung zur steuerung einer einschlagvorrichtung - Google Patents

Verfahren und vorrichtung zur steuerung einer einschlagvorrichtung Download PDF

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Publication number
EP0135516B1
EP0135516B1 EP84900604A EP84900604A EP0135516B1 EP 0135516 B1 EP0135516 B1 EP 0135516B1 EP 84900604 A EP84900604 A EP 84900604A EP 84900604 A EP84900604 A EP 84900604A EP 0135516 B1 EP0135516 B1 EP 0135516B1
Authority
EP
European Patent Office
Prior art keywords
chisel
molten electrolyte
measuring circuit
impedance
cell
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.)
Expired
Application number
EP84900604A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0135516A1 (de
Inventor
Ulrich Heinzmann
Werner Braun
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.)
Alcan Holdings Switzerland AG
Original Assignee
Schweizerische Aluminium AG
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 Schweizerische Aluminium AG filed Critical Schweizerische Aluminium AG
Priority to AT84900604T priority Critical patent/ATE22938T1/de
Publication of EP0135516A1 publication Critical patent/EP0135516A1/de
Application granted granted Critical
Publication of EP0135516B1 publication Critical patent/EP0135516B1/de
Expired legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/14—Devices for feeding or crust breaking

Definitions

  • the present invention relates to a method for controlling an impact device with an up / down movable chisel for the crust forming on the molten electrolyte of a melt flow electrolytic cell, by detection of the chisel / molten electrolyte contact.
  • a device for controlling an impact device with an up / down movable chisel for the crust that forms on the molten electrolyte of a melt flow electrolysis cell by detecting the chisel / molten electrolyte contact with an electrical measuring circuit, comprising the chisel as a sensor on which the chisel / molten electrolyte path appears as a contact-significant impedance element.
  • the aluminum oxide or the alumina in the electrolyte is consumed.
  • alumina concentration must be increased by adding new aluminum oxide.
  • maximum restraint of the process gases is guaranteed if the operation is carried out automatically at short intervals.
  • the non-continuous alumina feed can also be used over the entire longitudinal or transverse cell axis.
  • the known storage bunkers or alumina silos arranged on the electrolysis cells are generally designed in the form of funnels or containers with a funnel-shaped or conically tapering lower part.
  • the content of the silos arranged on the cell usually covers one to two times the daily requirement, which is why they are also called day silos.
  • the day silos are mostly fed in a closed pipe system, preferably by means of dense current from the central alumina supply.
  • the supply of alumina from the day silo to a breakthrough in the crust covering the molten electrolyte takes place in known devices usually by opening at least one flap which is pivoted for charging, or according to other systems with metering screws, metering cylinders or metering volumes.
  • day silos on the electrolytic cells are dispensed with, the metering devices are located outside the area of the electrolytic cell.
  • alumina charging and impact device for breaking the crust are always combined locally and functionally.
  • An electronic process control initially triggers the lowering and lifting of the chisel of the impact device, followed immediately by the charging of alumina.
  • the lowering movement of the chisel is stopped by a mechanically or pneumatically actuated limit switch and its return to the rest position is triggered.
  • the chisel remains immersed in the molten electrolyte for some time, has to be corroded relatively quickly and has to be replaced prematurely.
  • crust material remains stuck to the strongly heated chisel and must be stripped off.
  • the compressed air consumption is relatively high.
  • the chisel is used as a sensor in an electrical measuring circuit, which leads from the chisel to the cathode of the cell via a recording device. If the chisel is immersed in the molten electrolyte, the DC voltage generated by the direct electrolysis between the molten electrolyte and the cell cathode appears on the recording device as an indication that the chisel has contacted the molten electrolyte and as a control criterion.
  • the object of the present invention is the method. to design the device of the type mentioned in such a way that the above-mentioned disadvantages are eliminated.
  • the impedance between the chisel and the molten electrolyte is detected by means of an active impedance measuring circuit.
  • the measuring circuit is provided with an active signal source, a current or voltage source, and the impedance between the chisel and molten electrolyte is recorded by registering the resulting current or voltage signal on the measuring circuit, which results, at least primarily, from the closing of the measuring circuit by immersing the chisel in the molten electrolyte.
  • the impact device is preferably controlled such that when the impedance measured by the active impedance measuring circuit reaches a predetermined minimum value, the chisel is raised.
  • the impacting device in order to keep the energy to be used for the impacting devices at the individual electrolysis cells of an overall system to a minimum, the impacting device is to be operated with as little energy as possible, which in the normal case is just sufficient to break through the crust, it is proposed that the chisel be used with a predetermined Lowered force, monitors whether the minimum value is reached within a specified period of time, otherwise the lowering force increases.
  • the operating energy for the impact device is increased by raising the lowering force in order to force the breakthrough.
  • the operational safety of such a wrapping device is increased by detecting the time span of reaching or falling below the minimum value and generating an indication when a predetermined maximum time span is exceeded.
  • the device of the type mentioned at the outset is designed according to the invention in such a way that the measuring circuit with an active source and measuring device belonging to the circuit is an impedance measuring circuit.
  • the measuring circuit from the chisel must be connected via an active source and measuring device to a connection which preferably contacts the molten electrolyte with low resistance. Where this connector is located is of secondary importance. It is therefore possible to arrange this connection point directly at the area where the chisel is immersed in the molten electrolyte. If this connection point is practically at the same potential with regard to the operating parameters of the cell as the area in which the chisel is immersed in the molten electrolyte, then when it is immersed in cell operation, there appears practically a zero potential difference between the connection point and the chisel. In such a case, the measuring circuit remains unaffected by the operating parameters of the cell, in particular by the anode / cathode voltage, and a direct current impedance measurement can be carried out.
  • the source be an alternating signal source and thus an alternating signal impedance is measured.
  • the detected impedance is largely independent of the cell operating variables mentioned and interfering variables, if the measuring circuit is closed on the one hand via the chisel and on the other hand via a connection with low-resistance connection to the molten electrolyte.
  • connection point for the molten electrolyte isolated from the cell i.e. Arranging the entire measuring circuit in relation to the cell on the fly simplifies the implementation in that the connection for the molten electrolyte is a connection point of the cell itself. This can be on the anode or cathode side, for example. If an AC impedance is measured with an AC signal source, it is further proposed to provide DC decoupling capacitors in the circuit which decouple DC operating cell values from the circuit with a high impedance, but which act as low-resistance elements on the measuring circuit drive frequency used.
  • a steel trough 10 is lined with an insulation and carbon layer, which is not shown individually for reasons of clarity, the carbon base containing the cathode bars running in the transverse direction of the cell.
  • Carbon anodes 16 are immersed in the molten electrolyte 14 and are suspended from the cross members 20 via anode rods 18.
  • the cell encapsulation comprises a horizontal cover 22 and mobile oblique cover plates 24, which are electrically insulated from the board of the steel tub 10.
  • the impact device 28 is fastened in an electrically insulating manner with at least 5 kOhm.
  • This impacting device pneumatically actuates a chisel 30 which can be moved vertically up and down and which is shown in the rest position above the carbon anodes 16.
  • the lowermost working position of the chisel is drawn in with dashed lines, which plunges into the molten electrolyte, closes the electrical measuring circuit, in FIG. 1 an AC circuit, and is raised to the rest position in the next moment.
  • the electronic relay 34 measures the resulting alternating current signal as a function of the circuit impedance and sends a corresponding signal to the electronic process control 36.
  • Two decoupling capacitors 40 in the alternating current circuit cause the DC potential separation between the electrolytic cell and the electronic process control, respectively. the relay 34.
  • one connection 42 of the measuring circuit generally designated 44 is connected to the chisel 30, the other connection 46 to one of the anode trees 18.
  • the measuring circuit 44 generally comprises an active signal source 48, a signal generator for DC or preferably AC Signals and a measuring device 50, a current or voltage measuring device for impedance measurement.
  • the impact device is preferably controlled in accordance with the impedance measurement signal, preferably via a process control.
  • Fig. 2 it is now shown with function blocks, how the essential functions of the control can be realized, in a specially created structure, whereby in most cases, as mentioned, the use of an already provided process control will be indicated.
  • output A 50 of measuring device 50 acts on one input of a comparator unit 52, at the second input of which a reference signal source 54, preferably adjustable, is connected.
  • the comparator unit 52 only emits a signal with a high level if the output signal of the measuring device 50 falls below the switching value set with the source 54. If the output signal of the measuring device 50 is proportional to the circular impedance, that is to say the impedance between the chisel 30 and the anode tree 18, then a signal with a high level only appears at the output of the comparator unit 52 if the minimal impedance that is significant for contacting the chisel and molten electrolyte is registered .
  • a bistable unit such as a FLIP-FLOP 56
  • the striking device 28 is controlled pneumatically by a control unit 58 with control inputs d and u, corresponding to the control of the lowering movement and lifting movement.
  • a start switch 5 1 is closed and a control voltage U B is applied to the lowering input d of the control unit 58, via a changeover switch S 2 which is then in the position shown.
  • the chisel is lowered and finally contacts the molten electrolyte.
  • the changeover switch S 2 is switched to the position shown in broken lines, which triggers the return of the chisel 30 via the control unit 58.
  • the rising signal edge at the output of the bistable element 56 triggers a time delay circuit, for example a monostable multivibrator 59 with an adjustable pulse length TI , at the end of the pulse appearing at output A 59 a pulse is generated via a monostable multivibrator 60 generated which is fed to an AND gate 62.
  • the second input of the AND gate 62 is connected to the output of the comparator unit 52.
  • this pulse appears at the output of the AND gate 62, it means that the contact between the chisel and the electrolyte has been maintained during the set time period ⁇ j , so long, a bistable circuit, such as a FLIP-FLOP 64, is set, which leads to a display on the display device 66.
  • the FLIP-FLOP 64 is reset on a falling edge at the output A 52 of the comparator unit 52, which indicates that the contact between the chisel and the electrolyte has been interrupted again by the chisel being returned.
  • a second time delay circuit 68 such as a monostable multivibrator with an adjustable output pulse length T2 is triggered.
  • a pulse is generated by a monostable multivibrator 70.
  • This pulse is fed to the AND gate 72.
  • the pulse at the output of the monostable multivibrator 70 only appears at the output of the AND gate 72 when the second input of said gate is at logic '1'. which, with the inverter 75, is only the case when the output signal of the FLIP-FLOP 56 indicates that the contact between the chisel and the electrolyte has not been established.
  • the pulse at the exit of gate 72 thus indicates that after triggering the lowering movement of the chisel, waiting for the time period t 2 , contact between the chisel and the electrolyte has still not taken place. This means that the crust has not been broken. Therefore, with the pulse then appearing at the output of the gate 72, a bistable circuit, the FLIP-FLOP 74, is set, the output of which acts on the control input E 76 of a force control device 76, with the aid of which the pressure force or. the pressure P with which the chisel 30 is driven down is then increased. If the crust is broken, the FLIP-FLOP 74 is reset by the rising switching edge at the output of the FLIP-FLOP 56: The crust is broken.
  • the FLIP-FLOP 56 is reset after passing through the return path of the chisel 30 by a limit switch S E , which is only shown schematically, the impact cycle is ended. It goes without saying that when the pressure is increased, the chisel is preferably only, at least partially, retrieved in order to attempt a new breakthrough. The control to be provided for this is not shown in FIG. 2.
  • a further time delay unit for example a monostable multivibrator 78 with an adjustable pulse length T3, is triggered, at the end of which a pulse is generated again via a monostable multivibrator 80.
  • the output pulse of the monostable multivibrator 80 only appears at the AND gate 82 if the FLIP-FLOP 74 is still set at the same time, ie if the chiseling force is still being used. This means that the chisel was unable to penetrate the molten electrolyte even under increased pressure.
  • This state is also indicated on display 66 via an OR gate 84.
  • the lowering of the chisel is thus triggered by the control system, which is also referred to as electronic process control.
  • This can be determined in a time-fixed interval by closing S 1 in FIG. 2, for example every 1 to 2 minutes, according to instrumental analysis results of the alumina concentration in the melt flow or according to other automated parameters.
  • the preferably used AC voltage source of FIG. 1 can output an adjustable voltage, which is preferably between 20 and 40 V, in particular between 20 and 25 V.
  • the entire resistance of the AC circuit closed via the molten electrolyte is designed here in such a way that the AC voltage source emits a current of a few milli-amperes at the set voltage.
  • the electronic relay (converter) built into the AC circuit sends the signal to the central electronic unit, which is usually located outside the electrolysis hall Process control further.
  • a capacitor is installed in the alternating current circuit, as shown in FIG. 1. These capacitors separate the potential between the electrolytic cell, any stray currents that may occur and the electronic process control.
  • All elements of the measuring circuit are in the area of the electrolysis cell, but outside the hot one. corrosive zone.
  • the electronic process control causes the chisel to drop into the working position with a signal and - after contact with the electrolyte is established - e.g. via the electronic relay, the chisel is immediately raised in the rest position or - if the measuring circuit is not within the specified period ⁇ 2 after the chisel has been lowered - that the pneumatic or hydraulic pressure P on the chisel is increased.
  • the chisel In the rest position, the chisel is outside the area of the anode body, on the one hand because of mechanical effects when changing the anode, and on the other hand because of the increasing temperature and corrosion effects in the direction of the crust breakthrough.
  • the measuring circuit is closed and the electronic process control initiates the immediate termination of the lowering phase and the immediately subsequent lifting of the chisel into the rest position.
  • a chisel that is already somewhat worn or corroded in the lowest area does not have a disadvantageous effect on the method according to the invention.
  • the measuring circuit is not closed.
  • the electronic process control triggers an increase in pressure.
  • a reduced line pressure of, for example, 3-4 bar. If the chisel does not apply enough force with this reduced line pressure, the electronic process control causes the system to switch to the normal line pressure of, for example, 7-8 bar.
  • the electronic process control will trigger an optical and / or acoustic signal.
  • the cell operator can then correct the problem.
  • the same signal is triggered if the AC circuit remains closed for a time T 1 exceeding the normal operating cycle of the impact device, for example because the chisel is jammed.
  • the voltage source of FIG. 1 preferably outputs a voltage between 20 and 40 V, in particular 20 and 25 V, an alternating current of a few milliamps flowing when contact is made between the chisel and the electrolyte.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
EP84900604A 1983-02-10 1984-02-09 Verfahren und vorrichtung zur steuerung einer einschlagvorrichtung Expired EP0135516B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84900604T ATE22938T1 (de) 1983-02-10 1984-02-09 Verfahren und vorrichtung zur steuerung einer einschlagvorrichtung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH73983 1983-02-10
CH739/83 1983-02-10

Publications (2)

Publication Number Publication Date
EP0135516A1 EP0135516A1 (de) 1985-04-03
EP0135516B1 true EP0135516B1 (de) 1986-10-15

Family

ID=4194080

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84900604A Expired EP0135516B1 (de) 1983-02-10 1984-02-09 Verfahren und vorrichtung zur steuerung einer einschlagvorrichtung

Country Status (6)

Country Link
US (1) US4563255A (it)
EP (1) EP0135516B1 (it)
AU (1) AU567029B2 (it)
DE (2) DE3305236C2 (it)
IT (1) IT1175323B (it)
WO (1) WO1984003108A1 (it)

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4702324A (en) * 1984-05-14 1987-10-27 Aluminum Company Of America Control system for positioning and operating a pneumatic percussion tool
IT1196487B (it) * 1986-07-15 1988-11-16 Techmo Car Spa Procedimento per depurare i gas emessi dai forni di elettrolisi per la produzione di alluminio e relativa apparecchiatura
JPH05504513A (ja) * 1990-10-15 1993-07-15 トレスキー、ミロスラフ 回路から欠陥部品を除去する装置
CA2126181A1 (en) * 1992-07-14 1994-01-20 James P. Kissane Alumina supply apparatus for electrolytic smelter
WO1996002764A1 (en) * 1994-07-15 1996-02-01 Terry Fluid Controls Pty. Ltd. Actuator
FR2727985B1 (fr) * 1994-12-09 1997-01-24 Pechiney Aluminium Procede et dispositif de mesure de la temperature et du niveau du bain d'electrolyse fondu dans les cuves de production d'aluminium
DE29910803U1 (de) 1999-06-21 1999-09-16 VAW Aluminium-Technologie GmbH, 53117 Bonn Schaltungsanordnung zum Steuern eines Krustenbrechers
US6436270B1 (en) 1999-07-19 2002-08-20 Ab Rexroth Mecman Method and device for controlling the movement of a feeding and breaking chisel in an aluminum production cell
US6649035B2 (en) * 2001-05-04 2003-11-18 Ross Operating Valve Company Low energy and non-heat transferring crust breaking system
US6732761B2 (en) * 2001-08-03 2004-05-11 Ross Operating Valve Company Solenoid valve for reduced energy consumption
DE102004033964B3 (de) * 2004-07-14 2006-03-30 Bosch Rexroth Ag Einrichtung und Verfahren zum Betrieb einer Krustenbrechvorrichtung für Metallschmelzen
DE102007059962B3 (de) * 2007-12-11 2008-12-11 Robert Bosch Gmbh Vorrichtung zum Messen des Metallniveaus in einem Reduktionsbecken
CN101275245B (zh) * 2008-01-14 2010-10-13 贵州莱利斯机械设计制造有限责任公司 一种双阳极碳块残极自动压脱方法及装置
DE102008010175B4 (de) * 2008-02-20 2011-08-25 Robert Bosch GmbH, 70469 System für reduzierten Druckluftverbrauch in metallurgischer Industrie
US7915550B2 (en) * 2008-06-17 2011-03-29 Mac Valves, Inc. Pneumatic system electrical contact device
US8367953B2 (en) * 2008-06-17 2013-02-05 Mac Valves, Inc. Pneumatic system electrical contact device
DE102009052776A1 (de) * 2009-11-11 2011-05-12 Robert Bosch Gmbh Verfahren und Einrichtung zum Betrieb einer Krustenbrechvorrichtung für Metallschmelzen
NO336059B1 (no) * 2012-12-27 2015-05-04 Sinvent As Fremgangsmåte og apparat for rensing av karbonanoder
CN107287621B (zh) * 2017-07-07 2023-08-18 新乡宏达冶金振动设备有限公司 一种电解质清理机
CN107497793B (zh) * 2017-09-30 2024-03-12 中冶赛迪技术研究中心有限公司 一种铝槽打壳锤头超声振动清洗装置及方法
CN109594103B (zh) * 2019-02-20 2020-01-10 长江师范学院 铝电解槽阳极效应预警方法

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
DE1064628B (de) * 1958-07-22 1959-09-03 Vaw Ver Aluminium Werke Ag Anordnung zur ununterbrochenen UEberwachung des Ohmschen Widerstandes von aktiven Zweipolen
FR1376385A (fr) * 1962-12-07 1964-10-23 Vmw Ranshofen Berndorf Ag Procédé et dispositif pour l'addition automatique d'alumine dans les fours d'électrolyse pour la production d'aluminium
IT949765B (it) * 1972-03-01 1973-06-11 Cronzio De Nora Impianti Elett Metodo e relativo dispositivo per proteggere gli anodi contro il pericolo di cortocircuiti in celle a catodo di mercurio
FR2483965A1 (fr) * 1980-06-06 1981-12-11 Aluminium Grece Procede et appareillage de controle de l'alimentation en alumine d'une cellule pour la production d'aluminium par electrolyse
FR2487386A1 (fr) * 1980-07-23 1982-01-29 Pechiney Aluminium Procede et appareillage pour reguler de facon precise la cadence d'introduction et la teneur en alumine d'une cuve d'electrolyse ignee, et application a la production d'aluminium

Also Published As

Publication number Publication date
AU567029B2 (en) 1987-11-05
IT8419515A0 (it) 1984-02-09
DE3305236C2 (de) 1985-11-21
EP0135516A1 (de) 1985-04-03
IT1175323B (it) 1987-07-01
AU2437384A (en) 1984-08-30
WO1984003108A1 (en) 1984-08-16
DE3460987D1 (en) 1986-11-27
US4563255A (en) 1986-01-07
DE3305236A1 (de) 1984-09-20

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