US2617762A - Anode device - Google Patents

Description

Nov. 11, 1952 A. BASILEWSKY ANODE DEVICES Filed July 25. 1949 2 SHEETS-SHEET 1 iF z In 8 INVENTOR. i; w l i l ALEXIS EIAEILEWEKY Nov. 11, 1952 Filed July 25 A. BASILEWSKY ANODE DEVICES 2 SHEETS-SHEET 2 J .5 las: 20/: 02 2aa INVENTOR. ALEXIS EASILEWSKY BY /"A Z W S Patented Nov. ii, 195.?

ANODE DEVICE Alexis Basilewsky, New York, N. Y., assignor to Solvay & Cie, Ixelles-Brussels, Belgium Application July 25, 1949, Serial No. 106,723 In Belgium October 23, 1944 1 Claim. 1

My invention consists in a new and useful improvement comprising means for mounting a stem for the anode of an electrolytic cell in which gas is generated, a method of and means for initially assembling the stem and its supporting ring, and means for adjusting the stem. The invention is concerned particularly with the control of the space between the electrodes in an electrolytic cell of the mercury type in which the anode is a horizontally disposed graphite plate and the cathode is 'a layer of mercury on the bottom of the cell.

This application is a continuation in part of my two co-pending applications, now abandoned, Serial Number 620,009, filed on October 3, 1945, and Serial Number 728,307, filed on February 13, 1947.

' In electrolytic decomposition of alkali halides, for example, sodium chloride, an aqueous solution thereof is introduced into a cell, overlying a mercury layer which serves as a cathode. An anode plate of graphite or the like is disposed in a pool of the solution. Passage of direct current between the anode and the cathode brings about decomposition of the metal halide with resulting evolution of chlorine gas which rises to the top of the cell in a vapor space overlying the electrolyte. Alkali metal, for example, sodium, goes to the mercury cathode and amalgamates therewith. For a normally well-designed cell, the amount of alkali metal decomposed per hour depends on the amount of current which goes through the electrolyte. The drop that occurs between anode and cathode depends on different factors which are:

1. The theoretical voltage of the electrolytic decomposition of the alkali metal halide;

'2. The contact resistance between the several electric conductors bringing the current to the electrodes;

3. The electric resistance of the solution (electrolyte) to the passage of the current.

As the consumption of electric power, per unit of the product manufactured, will be the result of the multiplication of the current by the total voltage, both of these factors should be reduced to a minimum in a practical way. The present invention provides means to minimize the drop of voltage between the electrodes, and more particularly the resistance opposed by the electrolyte to passage of the current. This resistance depends on the current density, the conductivity of the electrolyte and the space between anode and cathode. Although the current density and the conductivity of the electrolyte will depend 'on the general conditions of the process, the space between the electrodes should be as small as possible. During the operation of the process,

evolution of chlorine on the graphite anode causes consumption of this material which increases the space between the electrodes, and requires, after a certain time, adjustment of the anode to prevent excessive drop of voltage which would result in undue consumption of electric power per unit ton of the product manufactured. This necessity for adjusting the anode to determine the space between anode and cathode has been a problem for all designers of electrolytic cells, and has been dealt with in difierent ways, depending on the possibilities of the available technique.

The materials of the cells must resist the tendency to corrosion caused by wet chlorine, one of the most active chemicals. Moreover, the chlorine produced must be as concentrated as possible, and all leakage of chlorine into the atmosphere must be avoided because chlorine is a toxic gas even in smallest concentrations in the air and it causes corrosion of metallic parts of the apparatus. In the beginning, cells were made of concrete, and the anode stems were sealed by means of cement to the top of the cell and the current was led to the anode by means of a copper conductor fixed on a graphite anode stem. To control the space between anode and cathode, one had to remove the cover of the cell and allow the anode to descend by changing spacers. Gastightness was secured by means of suitable mastic, and to avoid any leakage of chlorine into the atmosphere, the cell was maintained under reduced ressure. This form was the most usual and themost widely used by users of electrolytic cells. It is obvious that to control the space between anode and cathode the cell had to be rendered inactive, opened, the stem adjusted, and the cell closed, all of which required a considerable amount of time and consequently reduced the working time of the cell. Such a method could be used with cells working with low current densities, as for instance amperes per sq. it, when the loss of electric energy was proportionately not so important. Actually when the current densities are increased, this problem becomes more acute because the loss of electric energy becomes more serious and the consumption of the graphite is increased more and more quickly as the current densitygrows. Many inventors tried to develop devices for quicker and more efiicient control of the space between the electrodes without having to render the cell inactive, and with a minimum of working power. The. fact that modern cells generally use ebonite-lined steel, permits inventors to use more versatile equipment. In Germany, the anodes. were suspended from a cover of ebonite-lined steel through a packing gland providing practically gas-tightness of the joint and the current was supplied to the graphite stems through a copper bar attached by bolts. This device allows control of the anode-cathode distance without opening the cell, but it necessitates relatively expensive glands which, must be ebonite-lined to prevent corrosion by chlorine, and specially impregnated packings which are attacked by chlorine after a certain time. Moreover, the control of the space requires a rather long operation of unscrewing. the gland and the attached copper bar and rescrewing it after the spacev has been corrected.

To avoid such difficulties and to provide, av device which is cheap and easily handled, applicant,

has found as a result of his experience that; av simple graphite ring in Which a graphite stem is pressed can assure the desired gas-tightness, a.

satisfactory transmission of current and a simple;

way to control the space betweenthe electrodes,

without interfering withtheoperation of the cell. In the improved device, hereinafter fully de scribed, a graphite rod to serve as the anode stem is pressed through a graphite ring under conditions which will be fully described. The graphite ring is mounted on the cell with a gasket of rubber or other material resistant to chlorine which assures a seal to prevent escape of gas from the cell. The electric current is brought to the anode by aconductor mounted on the ring and the assembled ring and conductor are removably clamped by a plate and bolts. Electrical insulationof the graphite ring from the cover of the cell is secured by a device fully explained below, and between the, plate, and the conductor there is also an insulation gasket, and the bolts areinsulated in any convenient and well-known way. The current passesfrom the conductor to the, graphite ring and then to the graphite rod and th anode, with the smallest loss of voltage possible, and it isobvious from the foregoing description that the device will cost, less than all of the other proposed devices.

Contrary to the usual opinion, I have found by experience that graphite is sufiiciently elastic to permitit, without rupture, to stand considerable pressureof the rod against the ring. The internal diameter of the, graphite ring is less than the external diameter ofthe rod. A chart in which the differences. of the two diameters are the ab scissas and the force required to press the rod through, the ring, are the ordinates shows a straightline indicating the amounts of force suitable for the purposedesired. I have found that to obtain, good resultsv this force should be between 400 and 1200 pounds depending on the diameter differences which gives satisfactory mounting, avoids too delicate machining of the graphite parts, and allows an easily controlled assembly of rod and ring by measuring the force required to pass the graphite rod into the graphite ring. Since graphite is porous, it is necessary, to avoid any diffusion of chlorine through the pores, to impregnate the graphite ring and the graphite rod with a suitable impregnating mediumwhich will not harm the graphite, prevent movement of the rod through the ring, or provide a high electrical contact resistance. Such product can be chlorinated naphthalene or melted parafiin wax.

In the drawings:

Rig. 1 is a vertical section of the cell, the cathode, the anode, the stem for the anode, and the mechanism for adjustably mounting the stem.

Fig. 2 isa side elevation of a tool applied to the stern for adjustment thereof.

Fig. 3', isa riz ntal section on the lined-37 of Fig. 2, in the direction of the arrows, a portion being broken away.

Fig. 4 is a horizontal section on the line 4-4 of Fig. 2, in the direction of the arrows.

Fig. 5' is a fragmentary, top plan of a cell provided with a plurality of cathodes and. anodes, portions of the casing of the cell being removed to disclose a number of the anode stems and the mechanism for their adjustable mounting.

Fig; 6 is a diagrammatic, vertical section of a mechanism for the initial assembly of the anode stem and its graphite ring.

Fig. 7 is a pressure chart indicating, in inches and pounds, the proper degrees of pressure for the initial assembly of anode stems and rings of given dimensions.

As illustrated in the drawings, the cell I (Fig. 1) has a cover 2 removably clamped thereon, and a gasket 3 on the upper edge of the cell I to provide a gas-tight seal. The cover 2 has a circular orifice Z-a, and a lining ll of suitable electric insulating material, such asebonite or glass, which passes through the orifice 2-11 and has an annular portion Q-a overlying the cover 2 peripherally of the orifice 2-a. Imposed on this portion 4-a is.

the graphite ring 5 with a suitable electric insulating gasket 6, such as impregnated asbestos, disposed between portion t-a and ring 5, the orifice 2-11 and the ring 5 being co-axial. A suit,- able electrical conductor ring "I is mounted on the ring 5 co-axially therewith and has a suitable electric lead 1-11. A suitable plate 8 serves to, clamp the rings 5 and 1 on the cover 2 by means of bolts 9 with nuts 9-0: suitably insulated and an insulating gasket. It? is interposed between the ring I and the plate 8. The plate 8 has an orifice li-a oo-axial with rings 5 and I. If desired, the plate 8 being metallic may be mounted directly on the ring 5, ring I and gasket I0 be ing omitted, and the lead (-11 being connected to plate 6, the plate 8 beingsuitably insulated from bolts 9.

Suitably mounted on the cover 2 of the cell I there is a suitable framing II supporting aremovable casing I2.

Overlying the bottom of the cell I there is, a mercury layer l3 operating as the cathode, with a suitable electric lead I3-a passing out of the cell portion Ill-a of the stem l5 being, received in a,

drive-fit in a socket I l-b in the anode I4. The stem I5, passing loosely through the orifice 2-11 of thecover 2, is engaged in a gas-tight fit by thev graphite ring 5, and extends loosely through the ring I and the orifice B-a of the plate 8, projecting upwardly of the plate 8, its slightly tapered upper end I5-b being disposed slightly below the casing I2.

The tool 'I for adjusting the stem I5 and anode I4 (Figs. 2, 3 and 4) has a frame It comprising a horizontal beam IT fromthe ends of which depend legs I8 having on their lower ends lugs I9, respectively, which co-act with latches 2i] fixed on the plate 8, by which the tool I can be removably mounted on the plate 8. Suitably threaded in the beam I'Ithere is a rod 2| having on its upper end an operating handle 22. The rod 2| has on its lower end a head 23. Loosely carried on the rod 2|, above the head 23, there is a collar 24having depending fingers 25 carrying a resilient clamping ring 26 having lugs 27 and 28 (Fig, 4). A fork 29 is, mountedon lug 2'! and loosely embraceslug 28. Journaled in the legs of thefork 29 (Fig. 2) there is a shaft 30 extending upwardly through and journaled in the beam I1, and provided on its upper end with an operating handle 3I adjacent the operating handle 22 of the rod 2I. The shaft 30 has fixed thereon, between the legs of the fork 29, a cam 32 co-acting with lug28 (Fig. 4) to operate the clamping ring 26. As shown in Fig. 5, a cell I can be provided with a considerable number of cathodes and anodes with anode stems having my improved adjusting-mechanism. The cell I00 has a casing comprising individually removable portions IOI so that a plurality of anode stems are accessible byremoval of certain portions IOI. There is illustrated in Fig. 5 means whereby four electric leads 'I-a to four anodes, respectively, can be provided with a single electric switch. As illustrated, the leads'I-a have contacts I-b co-acting with a manual knife switch I02 suitably pivoted on cell I00 and having attached thereto a. suitable electric lead (not shown). I

I Fig. 6 illustrates diagrammatically a device for the initial assembly of the graphite ring 5 and the graphite stem I5. The device comprises a presshaving a bed 200 with a seat 20I to receive the ring 5 therein and a bore 202 co-axial with seat 20L The bottom 202-a of the bore 202 is disposedbelow thebottom 20I-a of the seat 20I at a precise distance for a purpose presently to be explained. The press has a reciprocatable head 203 comprising a slidably. mountedcasing 204 charged with a suitablefiuid, such as oil, forming a liquid mass 205 upon which impinges a piston 200 reciprocated by any suitable means such as manual lever (not shown). "A manometer 201 is provided to indicate in pounds the pressure exerted by the head 203 on the stem I5 to press it into assembly with the ring 5. The manometer 201 has marks 201-11 and 207-1) to indicate the minimum and, maximum degrees of desirable pressure. s

I will now describe the novel method of initially assembling the supporting ring 5 and the anode f stem I5, which can be practiced by the use of the novel means illustrated in Fig. 6. The ring 5 is placed in the seat 20! of the bed 200. The stem I5 is positioned co-axially of ring 5 and bore 202 of the bed 200, its tapered end I5-b, being introduced into the ring 5. The head 203 of the press is lowered by its actuating lever, pressing the stem I5 through the ring 5. It is obvious that thestem I5 is pressed downwardly by the casing 204fwhich is moved downwardly by the pressure exerted by the piston 205 reciprocated by the lever (not shown) and transmitted by the mass of liquid 205, the manometer 201 indicating the degree of pressure exerted. The depression of the stem continues until the tapered end I5b of the stem I5 passing from the ring 5 a precise distance, through bore 202 is brought into contact with the bottom 202-a of the bore 202 in the bed 200. This contact is indicated by the manometer 201 due to excessive pressure on mass 205 when the stem I5 has been seated in bore 202. The above-described steps, of my improved method of initially assembling the ring 5 and the stem I5, assure a precisely determined disposition of the stem I5 in the ring 5 for a purpose presently to be explained.

As previously mentioned, to effect the desired relation of the ring 5 and the stem I5, the internal diameter of the ring 5 must be less than the external diameter of the stem I5.- It is obvious that the degree of variation'of these diametersdetermines the degree of pressure required to effect movement of the stem I5 relative to the ring 5. I have found that good results are obtained when this degree of pressure is be-' tween 400 and 1200 pounds and experience has shown that a graphite ring 1.8 in. thick and having an outside diameter of 5.3 in. should have an inside diameter of 2.95 in. and that outside diameter of the graphite stem should be 2.95 plus in., the excess of the external diameter of the stem over the internal diameter of the ring varying from .0018 in. to .0081 in. I haveshown in the chart (Fig. 7) the several degrees of pressure required to press the stem I5 through th ring, dependent upon said excess.

Calling D the external diameter of the stem I5 and D the internal diameter of the ring 5, then DD' 0.00001D and DD'0.01D

Minimum D-DE0.00001 2.95

that is r 042 00000295 inch Maximum D-D' 0.01 2.95

that is DD' 0.0295 inch It is obvious that 0.0018 inch and are between the limits. w

A amounting to 5.3 inches has approximatelythe proper'dimension, since 1.791) or 1.'19 2.95=5.2s inches 'Also H amounting to 1.8 inches'has'approximately the proper dimension, sin'ce 0.6D or 0.6 2.95=1.77 inches When the ring 5 and the stem. I5 have been initially assembled, as above described, the parts are assembled in the cell I as shown in Fig. -1. It is obvious that, since the total length of the stem I5 and the thickness of the anode I l, before use, are known, and the anode I 4 is mounted on the end I5-a of the stem I5, and the ring 5 is disposed on the stem I5 at a precise position determined by the length of the bore 202, when the ring 5 is seated upon the cover 2 of the'cell I the space between the cathode I3 and the anode I I is precisely determined as desired. Since this precise determination of this space is essential to the proper functioning of the cell, the value of my novel method of initially assembling the ring 5 and the stem I5 is obvious.

I will now describe the use of my improved tool T for adjusting the stem I5 relative to thering 5 in order to redetermine the space between the cathode I3 and the anode I4 when consumption of the anode I4 in use has increased the space betweenthecathode; l 3 and the anode [4. When the casingizihasbeen removedv and the electric circuit to: the. anode [4 has. been opened, the tool. '1: ismounted in operative position by cone necting, lugs. l9 and; latches 20; (Fig. 2); the rod 2!. isscreweddown to dispose the ring. 26 about the upper; end, 15-h of the stem. 15; the ring. 26. isthen clampedon thestem [5 by functioningof the cam. 32; further depression of the rod, 2! brings the head 23 into contact with the stem: l5; depression of"head 23 by rod 21 presses the stem through thering, 5 and eventually carriesv the anodiltdownwardly to contact thebottom of the 111. The movement of rod 2| is then reversed to. raise the. head: 23, into contact with the collar 24. Further upward movement of the rod 2| causes; raising; of the stem I 5 and, movement upwardly f. theanode M. It is obvious that. the rod 2| can be calibrated so that a determined rotation thereof will precisely determine the space between the cathode I3 and the anode I4.

It is to be particularly noted that to utilizemy improved tool T only the latches 29 have to be provided for each of the considerable number of anode stems in a cell, which constitutes an important saving in capital cost of the cell. Experience has proved that a cell of 112 anode stems can be properly serviced to provide an anode-cathode space of one quarter of an inch, by one operator using my improved tool in less than-one hours time.

The particularly valuable improvement of my invention consists in the fact that this adjustment may be done while the cell remains in operation. As above explained, a cell contains a considerable-number of anodes, for instance 112. As illustrated in Fig. 5, four anodes can be connected to the switch I92; so that when this switch is open only four anodes out of the hundred or more are not operating and the slight increase in current of about 4% which occurs in all of the other anodes which are still in operation will not cause any change in the functioning of the cell which will continue to produce during all of the time of the adjustment of the anode-cathode gaps of the four anodes. When these four anodes have been. adjusted, they are again switched into the circuit and then four other anodes can be adjusted, and, so on for. all of those in the cell.

Contrary towhat might be expected, movements of the graphite rod throughthe graphite ring do not produce any noticeable wear of the ring, and the same rod and ring can be used after several anodes have been consumed.

My improved, means for mounting the rod does not introduce any supplementary voltage losses in the electric contacts but in fact it definitely reduces them. The close, contact between the electric conductor I and the graphite ring which is easily effected (as anyone skilled in the art will understand) is then better than. effected by the conventional method of leading the current. to the graphite rod by means of a collar.

Moreoven. experience: has shown that. the electrical. contact betweenthe graphite. rod i5. and; the graphite ring 5 has; a. very smallelectric resistance. If the. graphite rod [5 be mounted; in: the graphite ring 5 withzthe. correct pressure, the contactv resistance. R, representing. the ratio between the drop of voltage E; (in volts): and, the current density through. the contact D (amp. per sq. in.), will be less than 0.001 ohm per sq; in. It should be particularly emphasized that this resistance does not increasev with use, viz. repeated adjustment. of the rod in thering, but remains constant. Thisis anextremelyvaluable feature of. my improved means for mounting the anode stem iortadj ustment.

It. is. obvious that: my improved means for mounting the stem is. adapted for use; in cells in which the, cathodeand. anode" are vertically disposed.

Having described: my; invention, what I claim 1s:

Ina devicefor adjustably mounting an anode in a gas generating electrolytic cell. having a sealing cover; with an orifice therein, the combination; of a. graphite. rod of uniform circular cross-section passed loosely through said. orifice and having an anode mounted on the end of the rodin the cell; a graphite collar having a circular orifice of uniform. cross-section and encompassing said rod exteriorly of the cell; and means for mounting said collar on the cover of the cell in a. gas-tight joint, the dimensions of the rod and the collar having the relations expressed in the following formulae:

0.0.o00lD D-D' 0101'D DD Ais approximately 1.79D H isapproximately 0.6D

in. which. D is the outside diameter of the rod, D is the inside diameter of the collar, A is the diameter of the largest circle inscribed on the collar, and H is the distance between the faces of thecollar.

ALEXIS BASILEWSKY.

REFERENCES: CITED:

The following references are of record, in the file of this patent:

UNITED STATES. PATENTS Number. Name Date 680,440 Rhodin Aug. 13, 1901 680,441. Rhodin Aug. 13, 1901 693,678 Wilson Feb. 18, 1902 867,319 Stubbs Oct. 1, 1907 1,231,254 Hancock June 26, 1917 1,279,192 Wheeler Sept..17, 1918 1,467,217 Williams Sept. 4, 1923 1,941,387 Camescasse .Dec. 26, 1933 2,008,772 Robertson July 23, 1935 2,218,904 Burd Oct. 22, 1940 2,247,780 Hurm'anns May 2, 1944 2,374,861 Graham May 1, 1945

Claims (1)

1. 0.00001D$D-D'' 0.01D$D-D''

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