US3345273A - Method of and apparatus for indicating anode positions - Google Patents

Method of and apparatus for indicating anode positions Download PDF

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Publication number
US3345273A
US3345273A US342505A US34250564A US3345273A US 3345273 A US3345273 A US 3345273A US 342505 A US342505 A US 342505A US 34250564 A US34250564 A US 34250564A US 3345273 A US3345273 A US 3345273A
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Prior art keywords
carbon
voltage
cell
anode
low
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US342505A
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English (en)
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Robert V Brown
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Reynolds Metals Co
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Reynolds Metals Co
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Application filed by Reynolds Metals Co filed Critical Reynolds Metals Co
Priority to US342505A priority Critical patent/US3345273A/en
Priority to GB4342/65A priority patent/GB1092992A/en
Priority to CH149865A priority patent/CH431105A/de
Priority to DER39816A priority patent/DE1242884B/de
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Publication of US3345273A publication Critical patent/US3345273A/en
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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
    • C25C3/20—Automatic control or regulation of cells

Definitions

  • This invention relates to a method of and apparatus for indicating the anode condition of an electrolytic reduction cell and more particularly to a method of and apparatus for detecting and indicating one or more low or overloaded, carbons or anodes in a multiple anode alumina reduction cell.
  • carbon from the anode of a reduction cell is converted into carbon dioxide gas during the electro-chemical reduction process, so that the carbon blocksor anodes must be replaced periodically.
  • a carbon block replacement schedule is followed so that the average age of the carbon blocks in each section of the cell is maintained substantially constant.
  • a pot line includes a large number of multiple anode cells, for instance one hundred and forty lcells each having twenty-four carbons, anode positioning and replacement is a constant costly process that permits much error and inefficient cell operation.
  • the additional current will tend to heat the carbon and the steel stub. As the stub becomes red it will become visible to the operator and may be noticed, in which case the operator will raise said carbon by a small amount. If the operator fails to detect the heated stubs of the low carbon, the heating process will continue until the iron lstub actually melts and the carbon is disconnected from the anode rod. Once this has occurred the operator may not notice the condition until the carbon is due for a changeout or he has occasion to raise the set of carbons in the cell. The heating of the stub to its melting point generally occurs at a much faster rate than can be matched by the inherent tendency to self-adjustment.
  • a second phenomenon may be experienced under low carbon conditions.
  • the one low carbon drawing its large amount of current appears at times to create a disturbance in the liquid aluminum layer such that a number of neighboring carbons are periodically subjected to extreme overloads of current as though waves were flowing in the liquid aluminum layer.
  • a number of adjacent carbons may show over-heating and redness of the stubs, making it difficult for an operator to determine which carbon should. be raised in order to cure the trouble.
  • the production rate of the cell is reduced during the period of the upset.
  • the voltage wave form across a multiple-block-anode alumina reduction cell comprises a substantial direct current wave and a random low frequency alternating current wave of a fluctuating amplitude superimposed thereon that varies as a function of the degree of overloading of one or more carbons in the cell.
  • the amplitude variations of the superimposed alternating current (AC) are of sufficient magnitude to be detected and'indicated on a suitable meter.
  • AC superimposed alternating current
  • This variation in amplitude of the AC signal may be used to accurately indicate when the individual carbon blocks of a cell should be adjusted, with the result that cell upsets due to low carbon blocks are prevented. As a result the cell requires less attention by the operator and operatesrnore ly.
  • the magnitude of the AC component may be sensed by various means and interpreted by the operator and/ or utilized to actuate alarm means.
  • an AC voltage component in a frequency range downwardly of about 20 cycles per second may be generated by a highly upset cell condition and cause a DC Voltmeter to oscilate over a range of 0.2 volt -or more, with the amplitude of the oscillations decreasing as the carbon adjustment is improved.
  • the amplitude of the oscillations may be observed by an operator on an expandedscale voltmeter, or an on-line digital computer may be used'to calculate the amplitude from a set of consecutive voltage readings and issue pre-selected instructions to an operator.
  • an object of this invention to provide a method of and apparatus for indicating a low, or overloaded, carbon condition in a reduction cell utilizing an AC signal superimposed on the cell DC voltage wave form to actuate suitable indicator means.
  • a further object of this invention is to provide a method of and apparatus for detecting low carbon anodes in a multipleanode-reduction cell by sensing a variation in the amplitude of an AC signal superimposed upon the DC voltage wave form of the cell, and utilizing said AC signal amplitude variations to indicate a low carbon condition.
  • a method of detecing low carbon anodes in a multiple anode reduction cell in accordance with this invention may include the steps of detecting the variations in amplitude of any AC voltage superimposed on said DC voltage; land relating said amplitude variations of said AC voltage to a low carbon anode condition in said cell.
  • the amplitude variations of said AC voltage caused by a low carbon anode may be directly observed on a suitable meter.
  • the AC voltage superimposed on the cell DC voltage may be amplified, integrated, and the resulting output utilized to actuate suitable loW carbon indicator means.
  • the frequency spectrum ⁇ of the cell voltage utilized is l-20 cycles, the remainder of the voltage signal being eliminated by standard low pass filters, with about 20 cycle cutoff which is of course variable and determined by the characteristics of the detection means.
  • Any variation in amplitude of the AC voltage of l-20 cycles per second superimposed on the cell DC voltage is amplified and converted into a milliampere current proportional to the AC voltage component in the frequency range of 1-20 cycles.
  • a broader or narrower frequency spectrum may be utilized if desired.
  • apparatus for accomplishing this and many other objects may include means for measuring variations in the voltage of a reduction cell; means for amplifying and converting said variations in said voltage (within a frequency range of approximately 1 20 cycles per second) into a varying current proportional to said voltage variations; and utilizing said variations in current for indicating a low carbon ⁇ anode condition.
  • FIGURE 1 is a schematic illustrating a low carbon indicator arranged for use with a multiple-anode reduction cell.
  • FIGURE 2 is a wave diagram illustrating the reduction cell voltage Wave form and having an AC voltage component caused by a low carbon impressed thereon.
  • VFIGURE 3 is a wave diagram illustrating variations in an output current proportional to variations in the voltage wave of FIGURE 2.
  • FIG- URE 1 An important type of alumina reduction cell is shown schematically in FIG- URE 1.
  • This type of cell known in the industry by various n-ames such as prebaked, Niagara, etc., is particularly distinguished from other types of reduction cells by virtue of the anode.
  • the anode in this type of cell cornprise a plurality of carbon blocks 11 each of which are individually connected to the positive side of a source of direct current electricity, represented in FIGURE 1 as an anode bus 12 and the negative side of said source by a cathode bus 13.
  • Each carbon block 11 is individually adjustable with respect lto a carbon cathode 14, and the set of carbon blocks that comprises the anode is vertically adjustable with respect to the cathode 14 in such a manner that the position of each block relative to the other blocks of the set is unchanged.
  • Each carbon block 11 is connected through an iron stub 16 cast in the block to a copper anode rod 17 which in turn is clamped to anode bus 12 by a hand operated clamp 18.
  • ⁇ Anode bus 12 is supported at each end by a Ibridge jack 19 attached to :cell frame 21 whereby the anode bus 12 is raised or lowered with respect to the carbon cathode 14 and a layer of molten aluminum 22 which overlies the cathode 14, eifecting a uniform increase or decrease respectively in the thickness of a layer of molten cryolite 23 disposed between the neighorbing surfaces of the carbon blocks 11 and the molten aluminum.
  • Individual carbon blocks 11 may be raised or lowered by an operator with respect to the anode bus 12 and cathode 14 after loosening the appropriate clamp 13 with a conventional hand jack (generally used by the industry) that operates between clamp 18 and rod 17.
  • the electrical circuit through the cell consists in sequence of the anode bus 12, the anode rod 17, the stub 16, carbon iblock 11, the molten cryolite layer 23, molten aluminum layer 22, carbon cathode 14, current collection means 24 and cathode bus 13.
  • the anode bus 12 and cathode bus 13 are connected respectively through a rectifier or other suitable source of D.C. power (not shown).
  • the major resistance to electrical current ow resides in the molten cryolite layer 23 and the total cell current distributes itself among the plurality of parallel-connected carbon blocks 11 in inverse relation to the thickness of the molten cryolite layer 23 between each of said blocks andthe molten aluminum layer 22.
  • a D.C. voltmeter 26 having an expanded scale, is connected across the anode bus 12 and cathode bus 13 by means of conductors 27 and 28 respectively and measures the reduction cell voltage which during periods of good adjustment (as shown in FIGURE 2) remains substantially constant.
  • the cell voltage begins to fluctuate with increasing magnitudes that may reach several hundred millivolts and continue until the proper adjustment of the carbon is made.
  • An anode effect lamp 29 connected in parallel with the meter 26 indicates this condition.
  • the cell voltage is approximately 4.5 volts.
  • the expanded scale meter is provided to permit simultaneously the measurement of the cell voltage and visual observation of the magnitude of any fluctuations in cell voltage particularly any voltage variations of a low frequency which have been found to be significant because directly ⁇ attributable to one or Imore low caribons in a cell.
  • the low carbon condition leads to a current overload and t-hus cell voltage variations.
  • a conventional amplifier-integrating circuit designated as a low-carbon indicator 31 is connected in parallel with the lmeter 26 and measures the amplitude variations in the A C. voltage superimposed on the cell D.C. voltage Waveforms.
  • Ithe A.C. voltage may vary from a few millivolts under good anode adjustment to several hundred millivolts under cell -upset conditions resulting from one or more low carbons.
  • a signal may be provided to adjust the carbon while the eifect of the carbon maladjustment is still small and thus avoid an upset altogether. Further, an operator can readily determine from the strength of the signal at any time whether the cell carbon adjustment is excellent, good, or just satisfactory. Additionally, the signal is made more easily readable and interpretable by inclusion of integrating .means in the detector circuit to reduce pulsations arising from the low frequency portions of the voltage wave.
  • a very satisfactory signal can be obtained from a portion of the frequency spectrum of the cell voltage wave up to about cycles per second.
  • a voltage wave of this frequency range is easily amplified and integrated to provide a highly responsive, substantially pulsation free, indicator signal.
  • a conventional low-pass filter 30 is used to select the desired signal since a sharply dened frequency cut-off is not needed to insure elimnation of su-bstantially all of the 60 cycle and higher components of the voltage wave.
  • the indicator 31 may also convert the ce'll voltage wave in the desired frequency range of up to 20 cycles per second into an output current in milliamps proportional to the amplitude of the A.C. component in said frequency range.
  • This wave form is shown in FIGURE 3 and may be recorded on a strip chart.
  • This output current is measured by an expanded scale ammeter 32 that also turns on a low carbon light 33 connected in series with a suitable voltage source when the output current exceeds a determined value. Referring to FIGURE 3, the output current remains substantially constant during periods of good carbon adjustment fbut rises rapidly during poor carbon adjustment or when the cell goes into an anode effect. It is ⁇ to be noted that both lamps 29 and 33 are turned on during an anode effect while only lamp 33 is turned on during periods of low carbon upset and that lamp 33 goes out after the low carbon is properly adjusted.
  • detection means to be connected electrically across s-aid anode and cathode elements and sensitive to low frequency voltage variations in the neighborhood of 1 to 20 cycles per second superimposed on the applied DC voltage;
  • a display device responsive to said detection means to indicate the occurrence of voltage variations caused by a low anode condition.
  • said detection means includes:
  • detection means to be connected electrically across the anodes and cathode and sensitive to low frequency voltage variations in the neighborhood of l to 20 cycles per second superimposed on the applied DC voltage
  • said detection means including a low-pass filter and means for amplifying and converting the voltage variations at the output of said filter into a varying current proportional to the variations of the filter output,
  • a ldisplay device responsive to the varying current to provide an output indicative of a low carbon condition.
  • detection means to be connected electrically across said anode and cathode elements, said detection means being sensitive to voltage variations in the neighborhood of 1 to 20 cycles per second superimposed on the applied DC voltage;
  • a display device responsive to said detection means to indicate the occurrence of said voltage variations

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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)
US342505A 1964-02-04 1964-02-04 Method of and apparatus for indicating anode positions Expired - Lifetime US3345273A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US342505A US3345273A (en) 1964-02-04 1964-02-04 Method of and apparatus for indicating anode positions
GB4342/65A GB1092992A (en) 1964-02-04 1965-02-01 Method and apparatus for indicating anode positions
CH149865A CH431105A (de) 1964-02-04 1965-02-03 Verfahren zur Auffindung und Anzeige von einer oder mehreren zu tief hängenden oder überlasteten Kohleelektroden in einer Reduktionszelle; Vorrichtung zur Durchführung des Verfahrens und Anwendung des Verfahrens
DER39816A DE1242884B (de) 1964-02-04 1965-02-04 Verfahren und Vorrichtung zum Feststellen einer zu tief eingestellten Elektrode fuer eine elektrolytische Zelle mit mehreren Elektroden

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US342505A US3345273A (en) 1964-02-04 1964-02-04 Method of and apparatus for indicating anode positions

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CH (1) CH431105A (de)
DE (1) DE1242884B (de)
GB (1) GB1092992A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3410786A (en) * 1965-04-09 1968-11-12 Pechiney Prod Chimiques Sa Superstructure for electrolytic cells
US3491002A (en) * 1964-09-21 1970-01-20 Reynolds Metals Co Adjusting anode blocks in an electrolytic cell
US3539456A (en) * 1968-06-25 1970-11-10 Aluminum Co Of America Electrolytic cell solute determining apparatus and method
US3661748A (en) * 1970-04-07 1972-05-09 Instrumentation Labor Inc Fault sensing instrumentation
US3871984A (en) * 1973-09-17 1975-03-18 Reynolds Metals Co Transmission of pot line control signals
US3875030A (en) * 1973-09-17 1975-04-01 Reynolds Metals Co Detection of grounded anodes

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ZA74950B (en) * 1973-02-21 1975-01-29 Nat Southwire Aluminum Method and apparatus for producing metal
DE102013213982A1 (de) * 2013-07-17 2015-03-12 Bayer Materialscience Ag Verfahren und System zur Überwachung der Funktionsfähigkeit von Elektrolysezellen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2904490A (en) * 1955-09-09 1959-09-15 Ardal Og Sunndal Verk Method and arrangement for regulating the electrical effect to electrolysis furnaces coupled in series, particularly for the production of aluminium
US2930746A (en) * 1957-01-10 1960-03-29 Robert J Cooper Control of reduction pot lines
US2933440A (en) * 1956-10-09 1960-04-19 Kaiser Aluminium Chem Corp Method and apparatus for detection of anode effect

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2904490A (en) * 1955-09-09 1959-09-15 Ardal Og Sunndal Verk Method and arrangement for regulating the electrical effect to electrolysis furnaces coupled in series, particularly for the production of aluminium
US2933440A (en) * 1956-10-09 1960-04-19 Kaiser Aluminium Chem Corp Method and apparatus for detection of anode effect
US2930746A (en) * 1957-01-10 1960-03-29 Robert J Cooper Control of reduction pot lines

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3491002A (en) * 1964-09-21 1970-01-20 Reynolds Metals Co Adjusting anode blocks in an electrolytic cell
US3410786A (en) * 1965-04-09 1968-11-12 Pechiney Prod Chimiques Sa Superstructure for electrolytic cells
US3539456A (en) * 1968-06-25 1970-11-10 Aluminum Co Of America Electrolytic cell solute determining apparatus and method
US3661748A (en) * 1970-04-07 1972-05-09 Instrumentation Labor Inc Fault sensing instrumentation
US3871984A (en) * 1973-09-17 1975-03-18 Reynolds Metals Co Transmission of pot line control signals
US3875030A (en) * 1973-09-17 1975-04-01 Reynolds Metals Co Detection of grounded anodes

Also Published As

Publication number Publication date
CH431105A (de) 1967-02-28
DE1242884B (de) 1967-06-22
GB1092992A (en) 1967-11-29

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