US3052618A

US3052618A - Apparatus for automatic regulation, during working, of the distance between the electrodes of electrolytic cells having a movable mercury cathode

Info

Publication number: US3052618A
Application number: US713940A
Authority: US
Inventors: Deprez Charles; Bulte Rene; Crabbe Rene
Original assignee: Solvay SA
Current assignee: Solvay SA
Priority date: 1957-02-09
Filing date: 1958-02-07
Publication date: 1962-09-04
Anticipated expiration: 1979-09-04
Also published as: US3361654A; DE1065819B; FR1202149A; BE554895A; GB853360A; CH357058A

Description

p 4, 1962 c. DEPREZ EIAL ,05 13 APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING. OF THE DISTANCE BETWEEN THE ELECTRODES 0F ELECTROLYTIC CELLS HAVING A MOVABLE MERCURY CATHODE Filed Feb. 7, 1958 5 Sheets-Sheet l Sept. 4, 1962 c. DEPREZ ETAL 3,052,618

APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING, OF THE DISTANCE BETWEEN THE ELECTRODES 0F ELECTROLYTIC CELLS HAVING A MOVABLE MERCURY CATHODE 5 Sheets-Sheet 2 Filed Feb. 7, 1958 CLLII'.

CLLI

ch I INVENTORS CHARLES DEPREZ,

RENE BULTE a BY RENE CRABB ATTORNEY? Sept; 4, 19 c. DEPREZ EI'AL 3,052,618

APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING, OF THE DISTANCE BETWEEN THE ELECTRODES 0F ELECTROLYTIC CELLS HAVING A MOVABLE MERCURY CATHODE Filed Feb. 7, 1958 5 Sheets-Sheet 3 CLLI 3,052,618 RKING, 0F ECTROLYTIC ABLE MERCURY CATHODE S pt- 4, 1962 c. DEPREZ ETAI.

APPARATUS FOR AUTOMATIC REGULATION, DURING W0 THE DISTANCE BETWEEN THE ELECTRODES OF EL CELLS HAVING A MOV 5 Sheets-Sheet 4 Filed Feb. 7, 1958 Sept. 4, 1962 c. DEPREZ ETAL 3,052,618

APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING, OF THE DISTANCE BETWEEN THE ELECTRODES OF ELECTROLYTIC CELLS HAVING A MOVABLE MERCURY CATHODE Filed Feb. 7, 1958 Sheets-Sheet 5 Motor 5 Motor- 34 T 3 I 1%: -& 102,) 220 [lec/mma gn at .9 Motor /2 102/2) #50) 0 1) 5in r- L 213 'lectramaynet 3 270(2) #56) flotarl 12 my 1% 1 il- United States Patent 3,052,618 APPARATUS FOR AUTOMATIC REGULATION,

DURING WORKING, 0F TIE DISTANCE BE- TWEEN THE ELECTRODES OF ELECTROLYTIC ggIELS HAVING A MOVABLE MERCURY CATH- Charles Deprez, Uccle-Brussels, Ren Bult, Forest-Brussels, and Ren Crabbe, Boitsfort-Brusseis, Beigium, assignors to Solvay & Cie., Brussels, Belgium, a Belgian company Filed Feb. 7, 1958, Ser. No. 713,940 Claims priority, application Belgium Feb. 9, 1 .957 12 Claims. (6!. 204-225) In cells for the electrolysis of aqueous solutions having a moving mercury cathode of the horizontal type, it is necessary to regulate periodically the distance between the electrodes, in order to compensate for the wear of the graphite anodes.

Various devices have already been proposed enabling this regulation to be effected without interrupting the operation of the cell. W. C. Gardiner, for example, describes in Chemical Engineering, volume 54 of November 1947, pages 108 to 112, supporting rods for the lead-in of the current to the anode plates which are ar ranged in the lid of the electrolytic cell in such a manner that the rotation of the said rods causes the anode plates to descend towards the moving cathode. The first regulation is eiiected in the state of rest when the anodes are renewed, and during operation the wear of the anodes is periodically compensated for by the rotation of the supporting rods which causes the anodes to descend a distance controlled by the voltage, read from a voltmeter, existing between the anodes and the moving cathode.

It has also been proposed in Belgian Patent No. 451,- 762 to regulate the distance between the anodes and the moving mercury cathode during the operation of the cell by displacing the plates supporting the anodes and serving as a lid for the electrolytic cell. For this purpose, the lateral sides of the cells are fitted with fixed supports with which threaded rods engage, these rods being fixed to the plates which are thus suspended from the fixed supports and maintained in position by nuts screwed on the threaded rods and tightened on the fixed supports. By loosening the nuts, the plates are caused to descend thus enabling the wear of the anodes to be compensated for during operation.

In these two devices the regulation depends on the estimation of the operator and is thus not safeguarded against errors. For this reason there have been proposed, for example in British Patent No. 627,349, devices comprising, on the bottom of the cell which constitutes the support for the moving mercury cathode, supports on which the freely suspended graphite anodes rest. When and as the graphite disappears, the anodes descend towards the cathode and the distance between the electrode is thus theoretically kept constant and determined by the dimensions of the supports. These devices have two disadvantages; on the one hand, the supports constitute a permanent obstacle to the uniform circulation of the mercury and may constitute barriers opposing the carrying away by the mercury of impurities or solid residues which may form permanent local short-circuits detrimental to the good operating of the cell; on the other hand, the wear is less rapid at the point of contact between the supports and the anode than elsewhere and the distance between the electrodes is diflicult to estimate. To obviate these disadvantages, it has been proposed in Belgian Patent No. 522,772 and US. Patent No. 2,784,157 to provide cavities in the support of the moving mercury cathode wherein retractable calipers may move which emerge from the support surfiace to ice a predetermined height and on which the anodes may rest during the regulation.

Hitherto all devices for carrying out processes of regulation have been operated by hand.

The invention relates to a process for regulating during operation the distance between the electrodes of electrolytic cells having a moving mercury cathode and to an automatic device enabling all of the anodes to be regulated within a minimum of time thus obtaining a precise regulation independent of any human factor of estimation.

We have found the surprising fact that it is possible without major disadvantages to tolerate for a limited time a contact between an anode and the moving mercury cathode of an electrolytic cell. The process accordingly consists in successively gripping each anode by its support rod and current lead which projects through the lid of the cell, causing it to approach the cathode, until the amperage attains a given value as a function of the voltage existing in the cell or undergoes a rapid increase, particularly by the contact between the electrodes, and in subsequently displacing the anode in the opposite direction to a distance substantially corresponding to the optimum yield of the electrolytic cell.

The device for automatically carrying out the process according to the invention comprises a combination of two carriages the first of which runs on a runway parallel to the longitudinal axis of the cell, the second running at right angles to the first. The second carriage is fitted with pincers having several catches arranged concentrically to the support of the anode to be displaced which is movable in a vertical direction, the movements of the carriage and of the pincers being electrically controlled according to a pre-established plan from a control station situated at any point of the electrolytic plant or at one end of the cell or .even on one of the two carriages.

FIG. 1 of the accompanying drawings illustrates a de vice for carrying out the process according to the invention;

FIG. 1a is a similar view of the device seen in FIG. 1 but showing only the lower half of FIG. 1 and illustrating the cells and anodes with which the device can be associated;

FIG. 2 shows a detail of the fastening system of the device to the lid of the electrolytic cell;

FIG. 3 diagrammatically illustrates the various connections existing between the various members ensuring the automatic operation of the device;

FIG. 4 diagrammatically illustrates the supply circuits of all the operating members of the device;

FIG. 5 diagrammatically illustrates an electrolytic plant in plan view, the arrows indicating the direction in which the regulation is effected; and

FIG. 6 shows a modification of the contact plug in the form of a contactor.

It is to be understood that the invention is in no way limited to the examples given in these figures.

The device according to the invention is fitted with a series of relays and contactors ensuring its automatic operation. It is known that a contactor may simultaneously ensure the opening and the closing of difieren-t circuits thus permitting several simultaneous possibilities. In order to indicate these circuits and thus the various possibilities, there are used in FIGURES 3 and 4 of the accompanying drawings numbers which are placed in brackets after the reference number of the contactor in question. Moreover, some contactors are open in the state of rest, while others are closed. In order to indicate this difference, the symbols 0 and c are used to indicate open and closed, respectively. Thus, the contactor 111(1)c denotes that the contactor 111, circuit 1, is closed in the position of rest, that is to say open when it is mechanically actuated, whereas the contactor 111(2)o denotes the contactor 111, circuit 2, is open in the position of rest, that is to say closed when it is mechanically actuated. Thus, when the contactor 111 is actuated, the circuit 1 is interrupted whereas the circuit dis closed. a

The device shown in FIG. 1 comprises in outline a large carriage C allowing the longitudinal displacement of the device, a small carriage R moving transversely and carrying the pincers, the system for fastening the pincers to the tubular piece P fixed on the lid of the electrolytic cell and the system for opening and closing the pincers on the rod supporting the anode. Finally, the assembly of the device is fitted with various control and regula tion systems.

The large carriage is composed of a chassis C supported by two axles (not shown) on which two rollers (not shown) are arranged. One axle is driven by the motor 1 fitted with a speed reducer. The starting of the motor 1 is controlled by means of the contactor 1010. The lateral traverses of the chassis comprise fingers 2 actuated by electromagnets 3; these fingers fix the cartriage in a predetermined position by engaging with stopping notches 4. The fingers 2 are raised by the feeding of the electro-magnets 3 which is determined by means of the contactors 102(2)0, 103(1)0, 104(1)0, 105(2)c, 106(3))0, 107(1)c, 107(2)c, the relays 201 and 220(2), the latter being timed to one second delay, viz. ensuring contact for one second after removal of actuating voltage. One of the traverses carries shoes '50 and 51 whose purpose will be explained below. On the other hand, the motor 5 is fixed on one of the traverses, fitted with a speed reducer and actuating the double contact plug 6 which engages with the double current supply 70 each of whose sockets is connected at a dilferent point with the current path, that is to say connected with a difierent point of the copper bar CU serving for the circulation of the current from the sole of the electrolytic cell to the anodes of the immediately adjacent cell. This contact plug verifies the amperage existing in the cell when the anode An contacts the cathode Hg, above which is formed the electrolyte Sa and below which is the sole So of the cell. The contact plug 6 is subject to corrosion. A contactor is therefore preferably used as shown in FIG. 6. This contactor is completely enclosed in a sealed casing 400; instead of the contact plug 6, the axle controlled by the motor 5 is fitted with a finger 401 which engages the movable piece 402 of the contactor. This movable piece, when descending, ensures the closing of the

circuits

403 and 404 connected with different points of the copper bar 406 which ensures the circulation of the current from the sole S of the electrolytic cell CLLII to the anodes An of the adjacent cell CLLI. The movable piece 402 is fitted with a return spring 405. The motor is actuated by means of the contactors 106(4)0, 108(1)0, 108(2)0, 109(4)0, (timed to one second), 110(2)0, 110(3)o, 110(4)c, the

relays

202, 203, 204, 205 (timed to one second) and the push button 301(1)0 (timed to one second).

The small carriage R also comprises two axles E fitted with rollers G. One of these axles is driven by the motor 7 fitted with a speed reducer and actuated by means of the contactors- 106(2)0, 111(2)o, 116(1)o, 116(2)c, 116(3)c and the

relays

206 and 218. The device for fastening the small carriage to the large carriage comprises the finger 8 actuated by the electromagnet 9 and permits the immobilization of the small carriage due to the stopping notches 10 provided on the transverse side members A. Voltage is applied to and cut off from the electromagnet 9 by means of the contactors 102(2)0, 103(1)o, 105(1)c, 106(1)c, 106(5)0, 111(1)c, 117e, the relays 207, 208, 220(1) (timed to one second), and the push button 301(2)0. The small carriage is fitted with a chassis C comprising four elastic supports 11 to which the pincers and the various systems of regulation and control are fastened; the assembly supported by the elastic supports 11 is thus rendered independent of the carriages during the control operations.

The pincers consist of several parts which may be operated simultaneously or separately by any automatic or non-automatic electric device. This entire assembly is enclosed in the casings C and 0.; which are tight and resistant to corrosive liquids.

The system of fastening the device to the tubular piece P surrounding the supporting rod of the anode and fastened to the lid of the electrolytic cell comprises the motor 12; fitted with a speed reducer and a frictional coupling F The motor 12 is actuated by means of the contactors 103(2)o, 103(3)0, 109(1)0 (timed to one second), 110(1)0, 112(1)c, 112(2)c, 113(2)0, 113(3)c and the relays 209, 210(2) (timed to one second), 211 and 212. The motor 12 actuates by means of a pinion 13, having teeth inclined at 45, and a rack 14 having the form of a bracket, the fastening tube 15 fitted with bayonet notches 1'6 fastening it to the projection 17 of the tubular piece P which is fastened on the lid of the electrolytic cell around the rod supporting the anode An. FIG. 2 is a fragmentary view of the rack 14: it is made of two branches arranged at right angles. The pinion 13 to which a guide roller is fixed (not shown) engages in the first instance the rack arranged on the Vertical branch which results in the descent of the fastening tube 15. At the end of its course, the pinion 13 engages the rack disposed on the horizontal branch thus causing the securing tube to turn and fastening it, by means of the bayonet notches 16, to the projection of the tubular piece P. It should be noted that the rod supporting the anode should be arranged in the lid of the electrolytic cell in such a manner that the cell will be perfectly tight. To this effect, an adequate device will be used such as has been described, for example, in Belgian Patent No. 457,712.

The pincers proper comprise the catches 18 joined to the integral axles 19 of the support 2 0. The lower end of each catch is intended to engage the groove 21 cut into the rod supporting the anode An. The upper part of each catch is fitted with a head 22 engaged by the female cone 23 and the male cone 214. When the catches are open, the

cones

23 and 24 are hooked to a projection 26 by means of a small hooked rod 25. The small rod 25 is fitted with a spring (not shown) which tends to hold it fast to the support 20 and is movable around the axle 42. A notch is provided in the support 20 for passing the hook of the small rod 25 When the catches are closed, the push button carried by the piece 43 which is capable of sliding in the support 20' and fitted with a return spring 44, is in contact with the rod supporting the anode. The piece 43 carries a lever 25' arranged in a groove of the support 20 and fitted with a spring 45 which tends to keep it against the wall of the'support 20; this lever is displaced upwards as soon as the push button is put in contact with the rod supporting the anode and it engages the heel of the small rod 25 which is then freed from the projection 26. The cone 24 engages the springs 29*, the relaxation of which causes the cones 23 and 2.4 to descend thus causing the catches to be closed.

The operating mechanism of the pincers comprises the motor 34 controlled by means of the contactors 102(2) 0, 109(5)0 (timed to one second), 110-(1)0, 115(1):), the relays 210(1) (timed to one second), 216, 217 and 219. The motor 34 ensures the descent and the ascent of the pincers by means of trains of reduction gears 36 and 37, the friction coupling 38 and the endless screw 35 at which the support 20 is suspended. The verification of the rising distance of the pincers is effected by the synchro circuit interrupter 4 1 having a controllable course which is set in motion by means of an endless screw 40 which engages the endless screw 35. The controllable interrupter synchro 41 completes one rotation of 360 for a vertical movement of the pincers of 100 millimetres. A safety device reversing the rotation of the motor 34 is provided by the two generator dynamos 39 actuated by means of the

gear trains

36 and 37 and by the gear wheels D.

The restitution mechanism of the cones 2 3 and 24 comprises the motor 36 fitted with a friction coupling F which actuates a tubular gear Wheel 31 the lower end of which is threaded and fitted with a nut 32, with which the rods 33 engage, to raise the cones 23 and 2d. The motor 30 is actuated by means of the contactors 109(2) 0, 109(3)0 (both timed to one second), 114(1)0, 114(2)0, the

relays

213, 214, 215' and the controllable interrupter synchro 41.

It should be mentioned that all the motors are fitted with a mechanical brake whose jaws are actuated by an electromagnet arranged in series or in parallel with the motor. Stopping of the supply to the motor gives rise to the stoppage of the supply to the electromagnet which determines the braking of the movement of the motor by locking its axle by the jaws of the brake. As a matter of course, the motors, contactors and relays are protected from shock and covered by a jacket which is resistant to corrosive fluids.

The various contactors are actuated by the following pieces:

Large carriage C 105 (1)c and (2)0; 1tl7(1)c and Small carriage R: 106(1)c, (2) 0, (3 0, (4)0, (5) 0, 111(1)c and (2)0, 1170;

Finger 2: 113 1.10'(1)0, (2)0, (3)0 and (4)0;

finger 8: 113(1)0, (2)0'and (3)0; 116(1)0, (2)0 and Contact plug 6: Hid-(1)0, (2)0and (3)0; 108(1)0 and Fastening tube 103 1 2 0 and 3 0; 112 1 and (2) 0;

The end 18 of the catches actuates a contactor (not shown) which has the effect of diminishing the speed of rotation of the motor 34- which rotates fairly slowly when the catches are closed over the rod supporting the anode;

The not 32: the contactor, timed to one second, 109(1)0, (2)0, (3)0, (4)0 and (5)0 and the contactor 114(1)0 and (2)0;

All of the pincers: 102(1)0 and (2)0;

The contactor 115'(1)0 and (2)0 is actuated by mechanisms described below.

FIG. 5 shows a diagrammatic plan view of an electrolytic plant. According to this diagram, the device has just effected the control of the cell CLL 1 and is in the position of end of contro indicated by PR that is to say the small carriage R has started from a starting point PD and has consecutively stopped level with the anodes a a a a 032, and has then moved up to the point end of control FR The device is then displaced according to the dotted arrow PR by a rolling bridge and is now situated in the axis of the first series of anodes b b b and 0 of the cell CLLII. The large carriage is connected to an alternative current source of 110-115 volts and fastened by means of the fingers 2 which engage with the notches 4 shown in FIG. 1. FIG. 3 summarises the position of all of the contactors at this instant: the pincers are in the upper position and actuate the contactor 1020 (both circuits being closed). The contactor 1150 is not actuated (both circuits being open). The large carriage being bolted, the fingers 2 are in the notches 4 and no longer actuate 1010 (open circuit), but actuate the contactor 110 (circuits (1), (2) and (3) closed-circuit (4) open). In the locked position the large carriage cannot actuate the contactor 105 (both circuits closed); on the other hand, it actuates the contactor 1070 (both circuits open). The nut 32 is in the low position on the threaded part of the tubular gear wheel 31 and actuates the contactor 1140 (both circuits closed), whereas the contactor 10% is free (the five circuits being open). The fastening tube 15 in the high position actuates the contactor 1030 (the three circuits being closed). The

finger 8 which has fallen back actuates the contactors 113 (circuits (1) and (2) closed, circuit (3) open) and 116 (circuit (1) open, circuits (2) and (3) closed). The small carriage in the position PR actuates the contactor 106 (circuit (1) open, circuits (2), (3), (4) and (5) closed), does not actuate 111 (circuit (1) closed and circuit (2) open) and actuates the contactor 117' (circuit open). The contact plug 6 being in the high position, the contactor 11140 is actuated (the three circuits being closed), while the contactor 1080 is in the position of rest (both circuits open).

The small carriage R being in FR the push button 301 of the control post is pressed thus starting the following series of operations:

(1) The small carriage moves towards the other end of the large carriage C while the contact plug 6 descends and plugs itself into the current supply 70. These operations analyze as follows:

(0) Motor 5: By the closing of 301(1), timed to one second, the motor 5 is put under voltage and rotates in the direction corresponding to the descent of the contact plug 6 thus causing the opening of the contactor 11140; the circuits (2) and (3) of this contactor being open, voltage is applied to the relay 204 thus enabling the motor 5 to be continuously supplied when 30 1(1) is re-opened. When the contact plug arrives at the end of the course, it actuates the contactor 11180 which closes; the closing of the circuit (1) of this contactor leads to the end of the supply of the motor 5, since the relay 2% is disconnected, whereas the closing of the circuit (2) causes the application of voltage to the relays 202 and 2413, the latter preparing the re-ascending movement of the contact plug 6 by reversing the direction of rotation of the motor 5.

(b) Electromagnet 9 and motor 7: The closing of the push-button 3tl1(2) timed to one second, determines the application of voltage to the electromagnet 9 and the relays 2117 and 268; the finger 8 is lifted and actuates the contactor 116 whose circuit (1) closes, while the circuits (2) and (3) open: the motor 7 is placed under tension, the small carriage R moves and thereby no longer actuates the contactor 117a which closes; the electromagnet 9 remains under voltage when 301(2) is re-opened on account of the fact that 207 remains under voltage. Due to its displacement, the small carriage no longer actuates the contactor 1116 (circuit (1) closed, circuits (2), (3), (4) and (5) open). After a certain course of the small carriage, the shoe 50 fixed at the end of the transverse side member A raises the contactor 111 (circuit (1) open and circuit (2) closed). In parallel with the contactor 111 the contactor 117 is actuated and opens. The electromagnet 9 is thus no longer fed, the finger 8 falls back and ceases to actuate 116: the circuit (11) is thus open, the motor 7 is no longer fed, whereas the circuits (2) and (3) of the contactor 116 are closed (applying the voltage to the relays 206 and 218), the latter preparing the reversal of the direction of rotation of the motor 7. The small carriage continues its course and the finger 8 is blocked in the notch 19 whereby the contactor 113 (circuits (1) and (2) closed and circuit (3) open) is actuated.

(2) The action on the contactor 113 gives rise to the application of voltage to the

motors

12 and 34 which respectively ensure the fastening of the device to the cell and the descent of the pincers.

(0) Motor 12: Before the finger 8 actuates the contactor 113, the circuit (3) of the contactor is closed and the relay 210 is under tension. This relay is timed to one second, the action on the contactor 113 (closing of the circuits (2) and (3)) causes the application of voltage to the motor 12. The fastening tube 15 descends and frees the contactor 1630 (the three circuits being open). Due to the opening of the circuit (1) of this contactor, no voltage can be applied to the

electromagnets

3 and 9, whereas the opening of the circuits (2) and (3) determines the application of voltage to the relay 211 thus enabling the motor 12 to be continuously fed when the relay 210(2) is re-opened. It should be kept in mind at this point that the pincers and the casings C and C are independent of the small carriage R on account of the elastic supports 11 thus permitting freeing movements of the pincers and the casings. Due to the rack 14 having the shape of a cross-piece, the projections of the tubular pincers P engage with the bayonet notches 16 when the tube 15 descends, then by rotation of the tube 15 (horizontal branch Y of the rack 14-) the whole is fastened to the tubular piece P. At this instant the tube 15 actuates the contactor 1120. The closing of the circuit (1) of this contactor interrupts the supply of the relay 211 and thus that of the motor 12; the closing of the circuit (2) of the same contactor causes the application of voltage to the

relays

209 and 212, the latter preparing the reascent of the tube 15 by reversing the direction of rotation of the motor 12.

(b) Motor 34: 210(1) being timed to one second, the closing of the contactor 1 13 (circuit (1)) determines the application of voltage to the motor 34 and to the relay 220. The pincers start their rapid descent, the rotation of the screw 35 causing the support 20 to descend, and thus the contactor 1020 is freed which results in the application of voltage to the relay 217 thus ensuring the continuous supply of the motor 34 when the relay 210(1) is re-opened. Since the pincers continue to descend, the push button 27 comes in contact with the rod supporting the anode; the piece 43 has from now on an ascending movement with regard to the support 20 thus displacing the lever 28 upwards. The lever 28, by leaning on the hook of the small rod 25, lifts it and frees it from the projection 26. The cones 23 and 24- are then immediately driven out by the relaxation of the springs 29; the cone 24 separates the heads 22 and the catches 18 close over the groove 21 cut in the supporting rod of the anode. The descending movement of the

cones

23 and 24 and the closing movement of the catches causes the closing of a contactor (not shown) and this has the effect of reducing the rotation speed of the motor 34 from 3000 rpm. to 1000 r.p.m., the anode thus slowly descending towards the moving cathode. On account of the drawback spring of the small rod 25 and of the lever 28, the heel of the small rod now strikes the lateral part of the lever 28.

(3) The anode to be controlled approaches the moving mercury cathode and the re-ascending movement of the pincers, in order to carry out the process according to the invention, is efiected by reversing the direction of rotation of the motor 34. The reversal of the direction of rotation of the motor 34 is carried out by closing the contactor 1150 which is actuated indifiterently by one of the three following mechanisms If the amperage verified by the contact plug 6 reaches a given value as a function of the voltage existing in the cell;

If this amperage undergoes a rapid increase;

If the friction coupling 38 slips. The latter system is a safety device. If for any reason the two preceding mechanisms have not worked, the pincers continue to descend and the anode rests on the sole of the cell which represents a certain mechanical effort. The friction coupling 38 is set in such a manner as to slide, beyond a certain tolerated effort. Below this tolerated effort it does not slide and the two generating dynamos 39 which rotate at the same speed as the motor 34 supply the same amount of current, and the difierence of potential between the two generators arranged opposite one another is nil. Beyond the tolerated effort, the coupling slides and the two generators no longer rotate at the same speed; there is thus a difierence of potential taken up by a relay (not shown) which actuates the contactor 1150. The closing of this contactor by any of the three mechanisms leads to the application of voltage to the relays 21 6 and 219,

8 the latter causing the reversal of the direction of rota-. tion of the motor 34 and thus the re-ascent of the pincers.

(4) The reversal of the direction of rotation of the motor 34 causes the opening of the contactor 1150, but since the

relays

216 and 219 remain under voltage, the direction of rotation of the motor 34 corresponding to the ascent of the pincers is maintained. Similarly, the relays 217 still under voltage permit the continuous supply of the motor 34. The reversal of the direction of rotation of the motor 3 determines moreover the extent of the displacement of the re-aseent of the pincers and thus of the anode, by the controllable interruptor 41 which operates by means of the endless screw 40 only during the ascending movement of the pincers. After a controllable distance of ascent comprised between 0 and 30 millimetres, the controllable interrupter synchro 41 closes, the relay 217 is no longer supplied and, thus, the motor 34 is no longer supplied and stops.

(5) The stopping of the motor 34 (closing 41(1)) causes the application of voltage to the motor 30 which actuates the tubular gear wheel 31. The nut 32 arranged in the low position on the threaded part of the tubular gear wheel, ascends and lifts the

cones

23 and 24 by means of the rods 33 whose heads are fitted with an enlargement having the purpose of rigidly fixing them to the nut 32 from a predetermined position; the small rod 25 hooks to the projection 26 and the catches 18 of the pincers spread open: this has the effect of freeing the contactor which determines the slow speed of the motor 34. As the nut 32 rises to the high position on the threaded part of the tubular gear wheel, it frees the contactor 114 which results in the application of voltage to the relay 213 thus permitting a continuous supply to the motor 30. The nut 32, now arriving at the high position, actuates the contact 1090 timed to one second, that is to say the five circuits close during one second. The closing of the contactor 1090 has the effect:

(0) Of rearming the mechanism for the closing of the catches 18. Actually, the circuit (3) being closed, the relays 214 and 215, the latter of which causes the reversal of the direction of rotation of the motor 30, are under voltage. The controllable interruptor synchro 41 is re-opened and the nut 32 re-descends to the low position on the tubular gear wheel thus compressing the springs 29 between the cone 24' and the nut 32. At the same time, the contactor 1090 is freed, the motor 30 still being supplied because the relays 213 are under voltage, and it rotates in the direction corresponding to the descent of the nut 32, the relays 214 and 215 being under voltage. Having arrived at the low position, the nut 32 actuates the contactor 1140 thus closing the circuits (1) and (2): the relays 213, 214- and 215 are no longer under voltage, the supply of the motor 30 is interrupted and, at the same time the direction of rotation is reversed, since 215 is no longer under voltage.

(b) The closing of 109(1) causes the application of voltage to the motor 12: the fastening tube 15 rotates, is freed from the projections 17 and the tubular piece P and re-ascends: as a result, the contactor 1120 is freed, the continuous supply of the motor 12 being ensured on account of the fact that voltage is applied to the relay 211, since 109(1) is re-opened within a second. Having arrived at the high position, the tube 15 actuates the contactor 1030, the three circuits are closed causing the supply of the relay 211 to be terminated and thus the stopping of the motor 12 and at the same time the reversal of the direction of its rotation with a view to subsequent operation, the

relays

209 and 212 being no longer under voltage.

(0) The closing of 109(5) causes the application of voltage to the motor 34: the pincers re-ascend, the controllable interrupter synchro 41 is opened. Having arrived at the high position, the pincers actuate the contactor 1020, thus excluding the

relays

216, 217' and 219 from the circuit: the motor 34 is no longer supplied and 9 p the reversal of the direction of rotation is prepared (219 out of circuit).

(6) Thus, there is again achieved the initial situation 1-b. It should be mentioned here that when the motor 34 is under voltage, the relay 220 is under voltage. Now, this relay is timed to one second and when the the closing of the contactor 102 causes the stopping of the motor 34., 220 remains closed for another second and this determines the application of voltage to the electromagnet 9, the finger 8 which is lifted acts on the contactor 116 whose circuit (1)0 closes, the motor 7 is placed under voltage and the small carriage moves towards the following anode and no longer acts on the contactors 111 (circuit (1) closed, circuit (2) open) and 117 (closed) thus permitting the supply of the electromagnet 9 when the relay 220(1) opens. After a certain course of the small carriage, a shoe 51 situated on one of the side member lifts 1170 which opens at the same time as 111(1); the electromagnet 9 is no longer supplied, the finger 8 falls back and no longer actuates 116, the circuit (1) of this contactor opens, the motor 7 is interrupted while the direction of rotation remains the same because the

relays

206 and 218 are still under voltage. The small carriage continues on its course, until the finger 8 engages with one of the stopping notches 10 thus actuating the contactor 113 which controls the

motors

12 and 34, and the operation starts again as under (2).

(7) After the control of the last anode of the series (for example 12 the small carriage actuates the contactor 106 (circuit (1) open, circuits (2), (3), (4) and (5) closed); the nut 32 being in the high position (raised by the cones 23 and 24), 1090 is closed. Simultaneously with the re-ascent of the pincers after the control of the last anode of the series and with the re-ascent of the fastening tube, the closing of the circuit (4) of the contactor 106 and of the circuit (4) of the contactor 109 (timed to one second), places the motor 5 under voltage: the contact plug 6 re-ascends, freeing the contactor 1080, the

relays

202 and 203 which are under voltage enable the motor 5 to rotate in the direction corresponding to the ascent of the contact plug 6; the relay 204 is placed under voltage and thus allows the continuous supply of the motor 5 once the contactor 109(4) is re-opened. Having arrived at the high position, the contact plug 6 actuates the contactor 1040: the circuits (2) and (3) being closed, the

relays

202, 203 and 204 are no longer supplied and the motor 5 stops while the reversal of the direction of rotation is prepared (203 out of circuit).

(8) As soon as the contact plug 6 has re-ascended, the ire-ascending movement of the pincers, which is the longest movement, is terminated, and the pincers in the high position actuate the contactor 1020. The relay 220 which remains closed for one second after the termination of the supply of the motor 34, applies voltage to the

electromagnets

3 and 9 and, as a result, the

motors

1 and 7 are fed. The small carriage R returns to its starting position while the large carriage moves towards the following series of anodes (b [2 where it stops, locks itself and the contact plug 6 descends to the current supply 70. These operations analyze as follows:

(a) Electromagnet 3: the relay 220(2) being closed, the closing of the contactor 102(2) permits the supply of the electromagnet 3, since the contactor 106 is still actuated by the small carriage R (see (7)). At the same time the relay 201 is placed under voltage thus ensuring the continuous supply of the electromagnet 9 when the relay 220(2) is opened and the contactor 106 is no longer actuated by the small carriage R which moves simultaneously with the large carriage. The finger 2 is lifted and actuates the contactor 1010, thus applying voltage to the motor 1: the large carriage moves and the contactor 107 thus no longer being actuated, is reclosed and ensures the continuous supply to the electromagnet 9 when 220(2) is re-opened. Having arrived in the vicinity of the following series of anodes, the finger 2 approaches the stopping notch 4 having the shape of a shoe. This part of the notch is such as momentarily to actuate the contactor 10 7c. It is re-opened and thus interrupts the supply of the electromagnet 3. The finger 2 falls back and ceases to actuate 1010, the motor stops. As soon as the finger 2 has engaged with the notch 4, the large carriage is locked. The contactor is actuated (circuits (1), (2) and (3) closedcircuit (4) open) as soon as the finger 2 engages with the notch 4.

(b) Electromagnet 9 and motor 7. The relay 220(1) being closed, the closing of the contactor 1020 causes the application of voltage to the electromagnet'9 and the relays 207 and 208. The finger 8 being lifted, the contactor 116 is actuated, the closing of the circuit (1) giving rise to the application of voltage to the motor 7. As the small carriage moves, the contactor 106 is no longer actuated, nor are the contactors 111, circuit (1) closed, circuit (2) (open) and 117 (closed). After a certain course the smail carriage stops, the

contactor

117 and 111 being simultaneously actuated by the shoe 50: the electromagnet is no longer under voltage, the finger 8 falls back and ceases to actuate the contactor 116 (circuit (1) open, circuits (2) and (3) closed): the motor 7 stops and the reversal of the direction of its rotation is prepared by the application of voltage to the

relays

206 and 218.

(c) Motor 5: As soon as the contactor 110 is actuated by the finger 2, the motor 5 is placed under voltage (the relay 205 being timed to one second) and the contact plug 6 descends into the connector 70. The operation then continues as under (1(a) (9) The operations then continue as under (2) etc.

(10) Having arrived in front of the last series of anodes, the large carriage C actuates the contactor 1056 which opens. The opening of the contactor causes the complete stopping of the apparatus, when, after having controlled the last anode, the small carriage R moves to the position end of control FR Various safety devices are thus provided: the motor 1 (large carriage) cannot be set in motion (by means of the electromagnet 3) if the contact plug 6 and the fastening tube 15 are not raised. The motor 7 (small carriage) can operate only if the tube 15 is in the high position. On the other hand, the motor 5 can be supplied only if the fingers 2 are engaged with the notches 4 ensuring the locking of the large carriage. The

motors

34, 12 and 30 can lbe supplied only if the large carriage is locked (fingers 2 in the notches 4-) and also the small carriage (finger 8 in notch 10). It has been seen that the

motors

1 and 7 ensuring the displacement of the large carriage and the small carriage respectively can be put under voltage only if the fingers 2 and 8 are lifted. In order to provide this safety device, it is possible to use for example a magnetic coupling for connecting the rollers to the axles, the electromagnet being placed under voltage when the fingers 2 and 8 are lifted.

Other safety devices are also provided: they have the efiect of insuring that the re-ascent of the anode cannot be interrupted unless the current has regained a normal value. On the other hand, if the current circulating through the copper bars already exceeds the control value which is made evident by a visible signal and an audible signal, the apparatus raises the anodes until the current falls to a normal value. At this instant, the apparatus stops and can be started again only by a manual operation which stops the visible and audible signals.

The device is not limited to the control operations described above. It may also, by using suitable contactors and appropriate relays, effect for example the following operations- Lift and lower all anodes a similar amount without previously placing the electrodes in contact;

Control the anode a then lower the following anodes 11 a a a 11 the same amount as a ycontrol in, then b b b 12 and so forth.

In the case of control operations such as descri above, the dew'ce permits one to estimate the wear f the graphite anodes: it is suflicient to arrange a secure mark on the pincers, which passes before a scale during the vertical movement of the pincers, the distances of descent of the pincers during the consecutive controls giving the extent of the wear of the anodes.

It must be clearly understood that the device described above which comprises an assembly of mechanical pieces and systems of control, regulation and safety, is capable of numerous modifications which do not depart from the scope of the invention, the examples given are in no way limiting the range of the invention.

We claim:

1. Apparatus for the automatic controlled regulation of the distance between the graphite anodes and the mobile mercury cathode of an electrolytic cell for the electrolysis of aqueous solutions, said anodes having supporting rods and said cell having a sole supporting said mercury cathode with said sole being connected in series with the anodes of an adjacent cell by a copper bar to provide fiow of current between the sole of said cell and the anodes of the adjacent cell, said apparatus comprising first rails disposed on each side of said cell in parallel relationship with the longitudinal axis of the cell, a first carriage adapted to move along said rails above said supporting rods and comprising a chassis made of crosspieces defining second rails, and a second carriage received by said second rails, said second carriage being provided with pincers having a plurality of catches, said pincers being movable in the vertical direction and being adapted to seize said rods supporting the anodes, the movements of the first and second carriages and of the pincers being controlled by motors provided with brakes and actuated from a control post by means of con-taotors and relays according to a predetermined program, the indication essential for the regulation being obtained by means of a contact plug connected to two different points of said copper bar, said plug permitting measurement of the intensity of the current passing through the anode when the latter is placed in contact with the moving cathode.

2. Apparatus as defined in claim 1, wherein said first carriage is provided with locking fingers and each first rail is provided with notches to receive said locking fingers of the first carriage.

3. Apparatus as defined in claim 2, wherein said second carriage is provided with looking fingers, said bar is provided with a connector in which is received said contact plug, and said firstcarriage comprises a chassis made of two cross-pieces supported on axles which carry rollers, the axles being controlled by a motor, said cross-pieces having notches to receive said locking fingers of said second carriage, and a reversible motor for controlling the descent and reascent of said contact plug respectively into and out of said connector on the copper bar to ensure the circulation of the current between the sole of said cell and the anodes of said adjacent cell.

4. Apparatus as defined in claim 3, wherein said rollers are connected to said axles by means of a magnetic clutch, said rollers being connected when the fastening fingers of the first carriage are lifted.

5. :Apparatus as defined in claim 1, wherein said second carriage comprises a chassis supporting said pincers for seizing the supporting rods of the anodes and said chassis further supporting means for controlling the gripping and releasing movement of said pincers, the assembly of pincers and of said control means being contained in casings.

6. Apparatus as defined in claim 5, wherein said chassis of said second carriage is fitted with two second axles carrying second rollers, said second axles being controlled by a second reversible motor, and said chassis carrying said locking fingers of the second carriage.

7. Apparatus as defined in claim 6, wherein said second rollers are connected to said second axles by means of an electromagnetic clutch, said second rollers being connected when the locking fingers of said second carriage are lifted.

8. Apparatus as defined in claim 5, wherein the motor which actuates said pincers is a reversible motor, and wherein said pincers comprise an endless screw on which a support is suspended, catches being pivoted on said support and a roller disposed on the upper part of each of said catches, said roller being engaged by two conical cams actuated by springs.

9. Apparatus as defined in claim 8, wherein the screw of the pincers is mechanically connected with two generating dynamos by means of two gear trains and a friction coupling set for a tolerated mechanical efiort, whereby when said tolerated efiort is exceeded the coupling slides and the reascent of the anode is brought about by the difference of potential developed by said two dynamos.

10. Apparatus as defined in claim 8, wherein said screw of the pincers is mechanically connected by means of an endless screw to the axle of an interruptor of variable course which verifies the distance of the reascent of the anode to be controlled.

11. Apparatus as defined in claim 5, wherein each anode rod is surrounded by a tubular member provided with projections and wherein said chassis of the second carriage is fitted with a fastening tube actuated by means of a rack having the shape of a cross-piece, said fastening tube being provided with bayonet notches adapted to engage said projections in the tubular member.

12. Apparatus as defined in claim 5, wherein a system for opening and re-arming the catches is attached to said pincers, said system comprising a hollow tubular gear wheel having a threaded lower part, a nut arranged on said threaded part, and rods which engage with the nut and are connected with a conical cam, and a reversible motor to actuate said tubular gear wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,396,919 Brace Nov. 15, 1921 2,098,813 Rosseau -i Nov. 9, 1937 2,203,062 Schueler June 4, 1940 2,316,685 Gardiner Apr. 13, 1943 2,347,608 Owen Apr. 25, 1944 2,421,209 Lindner et a1. r May 27, 1947 2,542,523 Hirsh 1 Feb. 20, 1951 2,784,157 Deprez. Mar. 5, 1957 2,786,023 Deprez Mar. 19, 1957 2,816,861 Castex Dec. 17, 1957 2,819,802 Hart Jan. 14, 1958 FOREIGN PATENTS 470,517 Germany Dec. 27, 1928 1,070,329 France July 22, 1954

Claims

1. APPARATUS FOR THE AUTOMATIC CONTROLLED REGULATION OF THE DISTANCE BETWEEN THE GRAPHITE ANODES AND THE MOBILE MERCURY CATHODE OF AN ELECTROLYTIC CELL FOR THE ELECTROLYSIS OF AQUEOUS SOLUTIONS, SAID ANODES HAVING SUPPORTING RODS AND SAID CELL HAVING A SOLE SUPPORTING SAID MERCURY CATHODE WITH SAID SOLE BEING CONNECTED IN SERIES WITH THE ANODES OF AN ADJACENT CELL BY A COPPER BAR TO PROVIDE FLOW OF CURRENT BETWEEN TH E SOLE OF SAID CELL AND THE ANODES OF AN ADJACENT CELL, SAID APPARATUS COMPRISING FIRST RAILS DISPOSED ON EACH SIDE OF SAID CELL IN PARALLEL RELATIONSHIP WITH THE LONGITUDINAL AXIS OF THE CELL, A FIRST CARRIAGE ADAPTED TO MOVE ALONG SAID RAILS ABOVE SAID SUPPORTING RODS AND COMPRISING A CHASSIS MADE OF CROSSPIECES DEFINING SECOND RAILS, AND SECOND CARRIAGE RECEIVED BY SAID SECON RAILS, SAID SECOND CARRIAGE BEING PROVIDED WITH PINCERS HAVING A PLURALITY OF CATCHES, SAID PINCERS BEING MOVABLE IN THE VERTICAL DIRECTION AND BEING ADAPTED TO SEIZE SAID RODS SUPPORTING THE ANODES, THE MOVEMENTS OF THE FIRST AND SECOND CARRIAGES AND OF THE PINCERS BEING CONTROLLED BY MOTORS PROVIDED WITH BRAKES AND ACTUATED FROM A CONTROL POST BY MEANS OF CONTACTORS AND RELAYS ACCORDING TO A PREDETERMINED PROGRAM, THE INDICATION ESSENTIAL FOR THE REGULATION BEING OBTAINED BY MEANS OF A CONTACT PLUG CONNECTED TO TWO DIFFERENT POINTS OF SAID COPPER BAR, SAID PLUG PERMITTING MEASUREMENT OF THE INTENSITY OF THE CURRENT PASSING THROUGH THE ANODE WHEN THE LATTER IS PLACED IN CONTACT WITH THE MOVING CATHODE.