US2987463A - High amperage diaphragm cell for the electrolysis of brine - Google Patents

Description

June 6, 1961 J. c. BAKER ETAL 2,987,463 HIGH AMPERAGE DIAPHRAGM CELL FOR THE ELEcTRoLYsIs oF BRINE Filed June e, 1958 4 Sheets-Sheet l 'T l ff Q v l* 1 W ///n /.n/ '/w ////f/////m E w//my/Ar//Au/ ,av/A1 v C- BYatumZJr/v 0.004.

ATTORNEYS June 6, 1961 J. c. BAKER ETAL 2,987,453

HIGH AMPERAGE DIAPHRAGM CELL FOR THE ELECTROLYSIS OF BRINE Filed une 6 1958 4 Sheets-Sheet 2 JOSE C. BAKER CHRISTOPHER C. SILSBY, JR. JOHN E. VENABLE HENRY R. WIESNER Wmv., f

ATTORNEYS June 6, 1961 .1. c. BAKER ErAL 2,987,463

HIGH MPERAGE DIAPHRAGM CELL FOR THE ELECTROLYSIS OF BRINE Filed June 6, 1958 4 Sheets-Sheet 3 INVENTORS JOSE C. BAKER CHRISTOPHER C. SILSBY, JR. JOHN E. VENABLE HENRY R. WIESNER ATTORNEYS June 6, 1961 J. c. BAKER ET AL 2,987,463

HIGH AMPERAGE DIAPHRAGM CELL FOR THE ELECTROLYSIS OF BRINE Filed June 6, 1958 4 Sheets-Sheet 4 INVENTORS JOSE C. BAKER CHRISTOPHER C. SILSBY, JR. JOHN E. VENABLE HENRY R. WIESNER ATTORNEYS United States Patent O 1 2,987,463 HIGH AMIERAGE DIAPHRAGM CELL FOR THE ELECTROLYSIS F BRINE Jos C. Baker, Pasadena, Tex., and Christopher C. Silsby, Jr., Euclid, John E. Venable, Madison, and Henry R. Wiesner, South Euclid, Ohio, assignors to Diamond Alkali Company, Cleveland, Ohio, a corporation of Delaware Filed June 6, 1958, Ser. No. 740,293 5 Claims. (Cl. 204-266) This invention relates to a high amperage electrolytic diaphragm-type cell for the electrolysis of alkali metal chloride brine and more particularly to a cell capable of operation at a capacity of 30,000 amperes and higher.

Diaphragm-type cells for the electrolysis of aqueous alkali metal halide brine generally employ a foraminous or perforated metallic cathode and a duid-permeable diaphragm overlaying the cathode permitting percolation of electrolyte from the anode chamber through the diaphragm and cathode into a cathode chamber. Such cells rst made their appearance in the early part of the twentieth century. 'Ihe fluid permeable diaphragm, by separating the anode and cathode chambers, avoids the disturbing edects of convection currents and gas evolution, and generally inhibits migration of hydroxyl ions towards the anode. Those diaphragm-type cells most widely used today are of the circulating electrolyte type, wherein the diaphragms and cathodes may be arranged either horizontally or vertically, but in most instances, at least in the United States, the arrangement is vertical. These cells may be subdivided into two groups, those in which the diaphragms and cathodes are completely submerged, so that all sides of the cathode are submerged in electrolyte, and those in which the electrolyte comes in contact with one face only of an incompletely submerged diaphragm. When a completely submerged cathode is used, it is possible to a large degree to keep the anolyte separated from the catholyte by maintaining an anolyte liquor level in the anode compartment which is higher than the liquor level in the cathode compartment, so that a Huid flow is set up from the anode chamber to the cathode chamber. However, in such a cell migration of hydroxyl ion as well as osmosis of the cathode products can occur through the diaphragm and into the anode compartment. In a cell having an incompletely submerged diaphragm there is no large body of solution of alkali metal chloride and hydroxide present inthe cathode compartment because the cathode liquor is withdrawn as fast as it is formed. In this way osmotic action and hydroxyl ion migration are reduced 'to a For the most part diaphragm-type electrolytic cells have heretofore been designed for operation at relatively low capacities of the order of 10,000 amperes and less. One such cell, the so-called Hooker type S-3, however, has reached a capacity of approximately 20,000 amperes. This cell is cubical in design and employs a multiplicity of completely submerged cathodes upon which diaphragms are deposited, in situ. The Hooker-type cell is described by Stuart, Lyster and Murray, Chemical and Metallurgical Engineering 45, 354 (1938). The anodes are parallel, vertically disposed at blades of graphite, with their lower ends embedded in a lead slab resting on the cell bottom, from which they project upwardly, and the cathodes are in the form of parallel hollow ingers projecting horizontally from two opposite sides of the cell, the cathodes being adapted to alternate with the anodes, leaving an open channel or aisle in the center of the cell. The diaphragm is deposited upon the perforated or wire mesh cathode surface by the now conventional technique described, for example, in U.S. Patent No. 1,862,244 to K. E. Stuart, issued June 7, 1932. Performance data on the Hooker S-3 cell is given at page 2,987,463 Patented June 6, 1961 ICC 434, Table 63, of Mantells Industrial Electrochemistry, Third Edition (McGraw-Hill Book Co, Inc., 1950).

It is, of course, axiomatic that the greater the amperage imposed, the greater production capacity. As cell capacity is increased, however, the problem of driving a large current through the cell becomes formidable, because the resistance oered to passage of the current also increases with capacity. The electrical energy used to overcome excessively high resistance in the cell is, of course, converted to heat energy and, therefore, in part wasted. Since, conductivity is related to temperature, some increase in conductivity is realized with increase in temperature but with the increased capacity, the operating temperature of the cell increases and may even drive the temperature of the circulating electrolyte to the boiling point. Generally speaking, the art has avoided these diiculties by using a multiplicity of cells having relatively low operating amperages, although the need to tum to higher capacity cells is recognized in order to hold capital investment and operating costs at a In accordance with the instant invention, an electrolytic cell of the diaphragm type is provided that is capable of operating at high amperages, above 30,000 amperes, and yet because of its design readily permits improved production eiciency and operating conditions. These advantageous results are obtainable due tothe following features, taken singly or in combinations of two or three:

(l) A base having associated therewith a plurality of electrically-conductive metallic grid members delining a spaced series of slots on the base, in which slots 4there is tixed a multiplicity of vertically disposed anodes of halogen-resistant electrically-conductive material.

(2) A multiplicity of tubular, foraminous, electricallyconductive metal cathodes interposed between the anodes, the cathodes being arranged to form a series of tubes horizontally disposed in the cell, spaced from the base, extending completely across the cell to a peripheral chamber formed by inner and outer side walls, said tubes extending at least from inner side wall to innerY side wall and defining a corresponding series of catholyte compartments therewithin, and ixed to the inner side Walls in openings connecting the catholyte compartments with the peripheral chamber, and electrically connected at least to one of said side walls.

(3) A multiplicity of vertically-disposed electrically conductive cathode end sheets forming said inner side walls and connected with the cathodes at their ends adjacent said inner side walls, but spaced from the side walls, and with the cathodes forming a series of vertically disposed tubes adjacent the anodes on their vertical surfaces, and thus defining anolyte compartments therewithin completely separated from the catholyte compartments by the diaphragm-covered metal cathodes.

A subsidiary feature is the provision of an electricallyinsulating liquid-impervious material overlaying the metal bonding layer and other areas of the inner walls exposed to anolyte.

The invention will be more fully understood by reference to the attached drawings, in which:

FIGURE 1 is a top plan view of an electrolytic diaphragm type cell for the electrolysis of alkali metal chloride brine, partially cut away to show the arrangement of anodes and cathodes therein and to show the metallic grid members superimposed upon the base;

FIGURE 2 is a partial vertical section of the electrolytic cell of FIGURE l, partially cut awayto show the arrangement of anodes md cathodes and the mode of aixing the anodes to the base;

FIGURE 3 is an end view of the electrolytic cell of FIGURE 1, partiallycut away to show the arrangement of anodes and cathodes therein; 1

FIGURE 4 is an end view of another cell showing a desirable type of electrical connection which can be made with the end of the cell as shown in FIGURE 3;

FIGURE 5 is a fragmentary detail of the structure of FIGURE l, enlarged for clarity; and

FIGURE 6 is a fragmentmy detail of the structure of FIGURE 2, enlarged for clarity.

The cell structure shown in these drawings comprises the cell can 1, having outer walls 2 and inner Walls 3 of electrically-conductive material. The outer side Walls 2 with inner wall 3 form the peripheral chamber 5 for the collection of catholyte solution and cathode gas evolved in cathode tubes 6 and half-cathodes 7. The side walls are of electrically-conductive material so as to facilitate supplying an electric current to the cathodes. Side walls 3 are protected where necessary by halogenresistant material. Metal sheets of the same metal as the cathode tubes, such as steel sheets, are quite satisfactory, since the openings 8 and 9 are easily made, and welds can be used to join them electrically to the cathode tubes. Theouter and inner side walls in the cell illustrated are of steel and are both connected to a source of electricity at the buss 13. The catholyte solution and cathode gas enter the chamber -5 from the catholyte chamber by way of the slots 8 (best shown in FIGURE 5) and other openings 9 in the inner walls 3.

The anodes 10, each unit of which as shown is composed of ve sections of halogen-resistant electricallyconductive material, such as graphite or magnetite, are

Y mounted on the base member 4 by way of the slots 11,

exaggerated for clarity, between the grid members 12, also of electrically-conductive material. The grid members and the anodes are electrically connected to each other and aiixed to the base-member by the electricallyconductive bonding layer 14, suitably of lead (best shown in FIGURE 6). The bonding layer is not essential; the `anodes can be sweated into the slots in a tight electrical connection with the grid members. The grid members 12 are attached to a source of electricity by the anode lug 41. The grid members are formed preferably of electrolytic grade copper, for example, approximately 99.8% copper, resistivity not to exceed 1.72 microohms per cubic centimeter at 20@` C. according to A.S.T.M. specification B5-43. The grid gives improved electrical conductivity in the base, cuts 12R loss to Va minimum, and

Vthus permits operation of the cell at a lower temperature.

The lead bonding layer and a portion of the sides of the anode are coated With a chemically inert liquid-impermeable nonconducting coating 15 such as bitumen, petroleum residuum, gilsonite or asphalt, and this is overlaid with a base slab of concrete 16 having a reinforcing bar 17 at its upper edge. The edges of the concretev base are overlaid with a layer of putty 18 sealing a rubber gasket 19. Thus, leakage and electrolysis at the base of the cell and corrosion of the base by anoly-te are prevented. Y

'I'he cathode tubes 6 extend from inner sidewall to inner side wall of the 'cell chamber, in the slots S to which their ends are electrically connected by Welding. The tubes can extend beyond the side Walls, if desired. The slots 8 communicate with the peripheral cham-ber 5. The cathode tubes are readily constructed fromV metal'sheets by forming into a tube and welding the seam. Any electrically conductive material that is resistant to caustic canV be used, but stee'L is preferred. vPerforated steel sheets and steel wire cloth are suitable. The method Y of ttingthem to the inner side walls 3 makes it possible the two ends of the cathode assembly are the half-cath- Yodes 7, enclosing half-compartments which YValso communicate with the chamber 5. The cathode tubes are horizontally disposed across the cell and are spaced above the base member 4 to permit circulation of the cell liquor therebeneath. Adjacent cathode tubes are interconnected by end members 21 (best shown in FIGURE 5), which end members 21 are overlaid with fluid permeable diaphragm material 25 and complete the enclosure of the sides of the anodes by cathode material and form anolyte compartments 22, the end spaces 23 of Which are relatively open. The member 21 is spaced from the side walls of the chamber 5 by brackets 24 so as to permit hydrogen and cell liquor to escape behind them into the peripheral chamber through the openings 9, and also assist circulation of cell liquor at the ends of the inner chamber. The end members thus increase the eiiiciency of the cell. A well placed multiplicity of electricallyconductive metal straps 25 furnish needed support and stability to the cathode tube assembly. These can be Welded to the tubes for a better electrical connection.

The cathode tubes 6 and half-cathodes 7 advantageously are connected electrically to the electrically-conductive side walls 3 at both their ends. This can be done by welding; if both tubes and side Walls are of steel, Welding is facilitated. It then is poss-ible to supply a current at each end of the tubes by connecting the side walls 3 to a source of electricity. It also is desirable to make electrical connections, also by welding, between the-supporting straps 25 and the tubes 6. The result is a considerably improved operation, since there can be no great voltage drop along the cathodes as the distance from the source of the current increases. Y Areas of side Walls 3 adjacent the diaphragm-covered cathode surfaces are protected -by chlorineand anolyte-resistant material such as concrete.

The diaphragm 26 which completely separates the cathode from the anodes is huid-permeable and of halogen-resistant material, in this case asbestos, deposited in situ upon the outer surface of the cathode material facing the anode. However, other types of diaphragms can be used, and such are well known to those skilled in this art. The cell structure is adapted to permit use of sheet diaphragms, such as asbestos paper, which can be wrapped around or attached to the outer face of the cathode.

Cell cover 30, provided at its edges with reinforcing rings 31 and 32' and at its corners with lifting eyes 33, rests upon the upper sealing member 44 resting on the can 1, and encloses a collection space for chlorine gas. Its interior, if desired, also can be provided with a coating of suitable inert sealing material to ensure protection Afrom the corrosive chlorine atmosphere.

crete, such as Lumnite (calcium aluminate) cement or of concrete mixed with a Vinsol resin (a hard, brittle, darkcolored, thermoplastic resin derived from pine wood, and containing phenol, aldehyde, and ether groups, which resin is supplied in lump, flake, and pulverized forms, and as a stable emulsion. Sp. gr. 1,218;^M.P. 234-239 F.; ash Vpoint 455 F.; acid No. 93; largely insoluble in petroleum solvents; soluble in alcohols, ketones, and esters; partly soluble in aromatic hydrocarbons; compatible with ethyl cellulose, nitrocellulose, chlorinated rubber, proteins (such as casein and zein) and polyolen Vresins (such as Vista'nex).v This results in a concrete having a much lower porosity, and a much more uniform density, thus resisting penetration and resultant attack by chlorine gas upon the concrete, and aking-otf of large portions thereof with damage Vto the electrodes. This type of concrete also can be used to line the walls and baseof'the cell, as at 16. Y

Alternatively, the cell walls can be extended upwardly beyond Vthe height of the anodes and cathodes and 'a fiat cover of halogen-resistant material fitted thereto, such as a steel sheet protected on the inside Yby a halogen-resistant rubber coating.

Provision is madefor introduction of brine through the cell cover by one brine inlet or, as shown, by two brine inlets at 34 and 35, by way of tubes 36 and 37 (best shown in FIGURE 3) which extend to about one inch hom the bottom of the anolyte compartment 22 through the open ends 23 of anolyte compartments adjacent to the end screens. These inlets are best placed about one-third the distance from each end for optimum circulation of chloride ion throughout the cell. Brine also can be dispersed according to any conventional procedure, provided it does not impinge upon the diaphragm, such as by spraying in droplet form.

Chlorine is withdrawn through the vent 38. Hydrogen and traces of other gases are withdrawn from the peripheral chamber through the vent 39, and the catholyte liquor, i.e., alkali metal hydroxide containing unelectrolyzed salt, is withdrawn at 40.

Electrical connection with other cells in series can be provided as shown in FIGURE 4. Connection is made to the anode lug 41 by the buss bar 42 which is attached to the recessed cathode lug 43 of an adjacent cell. The recess reduces the length of the electrical buss connection and saves cell room space without affecting operation.

In the operation of the cell an alkali metal chloride, for example, sodium chloride, brine stream of desired concentration is fed to the cell through openings 34 and 35 in the roof 30. The brine level is brought to a point somewhat above the upper surface of the anodes, suitably more than one inch and preferably about one to four inches above the anodes, and an electric current passed through the cell by means of the electric connections, some of Which are not shown. It has been found that the anolyte level is preferably maintained well above the tops of the anode elements of the cell to aid in ensuring uniform chloride ion distribution in the anolyte compartments.

Although the precise manner in which uniform chloride ion concentration is obtained is not completely understood, there is evidence that the feed brine entering through the inlets 34 and 35 and through the tubes 36 and 37 downwardly to the bottom of the cell is dispersed, upon impact with the base of the cell, assisted by natural circulation within the anode compartment, uniformly in the region of the lower portions of the anodes and cathodes. The hottest part of the cell of the present invention is at the center, unlike cells having an open center aisle, where there are no anodes. The brine is heated in the central portion of the cell, during electrolysis. Chlorine gas forms at the surfaces of the anodes 10, rises along the anodes and is exhausted from the cell through the vent 38. The rising chlorine as well as the heat generated during electrolysis, particularly at and near the center of the cell, causes upward movement of the anolyte in the electrolytically active central regions of the anolyte compartments 22, and this is accompanied by a compensating circulation of the anolyte downwardly at the edges of the cell in the more open end spaces 23 of these compartments. The result of the placement of brine introduction and this natural convection-and chlorine liftaided circulation is to give substantially uniform chloride ion concentration throughout the anolyte compartments. This circulation is greatly assisted by theplacement of the cathode tubes above the base of the cell.

Concurrently with the evolution of chlorine from the anodes, anolyte percolates through the porous cathode diaphragm and the metallic cathode members 6` and 7, as well as the end members 21 of the cathodes, where it forms alkali metal hydroxide and hydrogen, into the catholyte compartments 20. The alkali metal hydroxide solution and hydrogen escape from the catholyte compartments 20 into the peripheral chamber 5 by way of the slots 8 and other openings 9. The catholyte solution ultimately leaves the peripheral chamber 5 of the cell through the take-oi conduit 40, here shown at the side of the cell. However, the catholyte take-01T conduit may conveniently be located otherwise than as shown, without detrimental elect. Hydrogen and traces of other gases present in the peripheral chamber 5 may be suitably removed as through the hydrogen outlet 39. Manometer connection 45 may be provided for conveniently determining anolyte level with the anode compartment.

The above-described design offers considerable advantages over prior cells. The most important is the elicient operation at a large current, of the order of 30,000 amperes and higher, which permits a considerably greater production. The cathode design permits an exceedingly low hydrogen content in the chlorine cell gas. The improved copper grid superimposed upon the base member gives a much better electrical connection in the proximity of the anode, reducing to a minimum the distance current must travel through lead in order to reach the anode. 'I'he anode and cathode arrangement allows cell repair and assembly to be accomplished readily and eiciently outside the cell room, because each of these components is readily removed. It also is possible to achieve a con siderable stability of operation under varying load conditions simply by adjusting the feed of brine to the cell and withdrawal of cell liquor from the cell to tit the need.

The following data is typical of performance of the cell of the invention at amperages of 27,000, 30,000, and 33,000 with a sodium chloride brine, and is compared with a typical 20,000 ampere cell of more conventional design:

TABLE I Performance data 30,000 Ampere Typical Diaphragm Cell 20,000 Cell Amperes Ampere Dia- 27,000 30,000 33,000 phragm Cell Current Ecieney 96. 5 96.5 96. 5 95. 5 Avg. Cell Voltage (Inc. Bus 1 3. 68 1 3. 82 1 3. 94 l 3. 78 PoWer-KWHDC/Ton Cl; 2, 630 2, 720 2, 800 2, 690 Graphite-lbs/Ton C12. 7, 7. 5 7. 5 7. 5 Avg. Anode Life-Days 255 230 210 230 Avg, Diaphragm Life-Days 115 110 115 Cell Liquor Temp- F 193 106 199 195 Percent NaOH in Cell Liquor 1 10. 5 1 10.5 1 10.5 l 10A 5 NaC1O3/1,000 NaOH in C.L 0. 54 0. 54 0. '541 0. 54 Chlorine Production-Tons/D 0 91 1.01 1.11 0. 675 NaOH Produetion-Tons/Day l 02 1.14 1 25 0. 760 Anolyte Temp. F 200 203 20 1 The cell can be operated so as to produce cell liquor with an 11.217a NaOH content. Ihls results in a cell voltage increase of 0.02 volt.

Brine cell feed specification The above data shows that the 30,000 ampere diaphragm cell of the invention does not require an appreciably higher cell voltage than the 20,000 ampere cell. In fact, at 27,000 amperes the cell voltage needed is markedly less than that needed by the 20,000 ampere cell. At 30,000 amperes the voltages are comparable, and so also are the average lives of the anodes and of the diaphragms. A higher cell liquor temperature is not necessary. The percentage of sodium hydroxide in the cell liquor is the same, and the chlorine and sodium hydrox- V7 ide production are increased. As would be expected from this, the current eiciencies are substantially the same.

The purity of the chlorine obtainable from the cell The cell structure of the invention is readily adapted for use at any available amperages to suit the available electrical equipment, merely by adjusting the number of electrode pairs. It can be used at amperages well below 30,000 amperes, when so modified, although of course it is most economically operated at 30,000 amperes and above. Amperages of 35,000 to 40,000 arnperes are not excessive.

The cell is useful for the electrolysis of alkali metal chlorides in general, including not only sodium chloride, as indicated above, but also potassium chloride, lithium chloride, rubidium chloride, and caesium chloride. These collectively are encompassed by the term brine as used in the specication and claims.

What is claimed is:

1. An electrolytic cell for the electrolysis of alkali metal chloride solution comprising a basermember having associated therewith a plurality of electrically-con.- ductive metallic grid members defining a series of spaced slots therebetween and positioned upon said base member, electrically conductive outer side walls and inner side walls mounted on the base, the outer and inner side Walls with the base defining therebetween a peripheral liquid-containing chamber, the inner side walls with the base defining an inner-liquid containing chamber, a plurality of anodes fixed in the slots between said grid members upon the base member and vertically disposed within the inner chamber, a plurality of hollow, tubular, foraminous electrically-conductive metal cathodes interposed between the anodes, said tubular cathodes being horizontally disposed in the inner chamber and extending Vcompletely across the chamber at least fromV inner side wall to inner side wall, the tubes of said cathodes dening catholyte compartments therewithin, and being fixed in openings in said inner walls connecting the catholyte compartments with the peripheral chamber so as to `form an electrical connection to at least one of Vthe cell side walls, the side walls of adjacenttubular cathodes being interconnected electrically by conductive metal cathode material spaced from the inner side walls and forming with the tubes vertical cathodic surfaces adjacent the ends of said anodes thus enclosing the anodes on their vertical surfaces and thereby dening anolyte compartf ments, a fluid-permeable diaphragm associated with the surface of said cathode tubes and completely separating the cathode surface from the anode compartments, means for introducing brine into an anolyte compartment, means for withdrawing chlorine from the cell, means for withdrawing catholyte liquor and hydrogen gas kfrom the peripheral chamber, and means for passing a direct current from said grid members through the cell.

V2. An electrolytic cell forv the electrolysis of sodium chloride brine comprising a base member, having associated therewith a plurality of electrically-conductive metallic grid members defming a series of spaced slots therebetween and positioned upon said base member, said grid members being an integral part of means extending outside said cell for electrical connection with a source of direct current, electrically conductive outer side walls and inner side Walls mounted on the base, the outer and inner side walls with the base defining therebetween a peripheral liquid-containing chamber, the inner side walls with the base defining an inner liquid-containing chamber, a plurality of anodes fixed within t-he slots between said grid members upon the base member and vertically disposed within the inner chamber, a plurality tubular, foraminous, electrically-conductive metal cathodes interposed between the anodes, said tubular cathodes being horizontally disposed in the inner chamber spaced above the base member and extending completely across the inner chamber at least vfrom inner side wall to inner side wall and defining catholyte compartments therewithin, the tubes of said cathodes being electrically connected to at least one of said side walls and being fixed in openings in said inner side walls connecting the catholyte compartments with the peripheral chamber, adjacent cathode tubes being interconnected near their ends by electrically conductive foraminous metal cathode material spaced from said inner side walls and lforming with adjacent tubes additional vertically disposed cathode surfaces adjacent vertical surfaces of the anodes in said slots, and delining anolyte compartments therebetween separated from the catholyte compartments by foraminous metal cathode material, ak fluid-permeable diaphragm associated with the surface of said cathode tubes and said |vertically disposed additional cathode sur-faces spaced from said inner side walls, and completely separating the cathodic surfaces from the anode compartments, openings in the inner side walls connecting the catholyte com- Ipartment and the spaces between said vertically disposed additional cathode surfaces and the inner side wall with the peripheral chamber, the areasV of said inner side walls adjacent diaphragm-covered cathode surfaces being protected by anolyteand chlorine-resistant material, means for introducing sodium chloride brine into an anolyte compartment, means -for withdrawing chlorine from the cell, means for withdrawing catholyte liquor and hydrogen ygas from the peripheral chamber, and means `for supplying a direct current to said means extending outside said cell -for electrical connection and thereby through said cell.

' 3. An electrolytic cell in'accordance with claim 2 in which the grid members are arranged in units having a plurality of tine; members per unit.

4. Anrelectrolytic cell in accordance'with claim 2 in which there Vis a layer of fusible electrically-conductive material bonding the anodes and grid members to the base member. Y

5. An electrolytic cell in accordance with claim 4 in which there is an electrically-insulating liquid-impervious material' overlaying the bondingV layer. Y

Rockwell Apr. 17,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,2,987,463 June 6, 1961 I i Jos C. Baker et a1. i

It is hereby certified that error appears in the above numbered patent requiring correction and 'that 'the said Letters Patent should read as -Lorreo'lsed below.

Column 2, line 4, after "greater" insert, the '--g Column 4, 1in-e 57, for "1,218" read 1,218 mg column 6, line 58, above the last column of the table, strike out, "Percent"; column 8, line 13, after "plurality" insert Signed and sealed this 28th day of November 1961.

(SEAL) Attest:

ERNEST W. rSWIDER I DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC

Claims (1)

1. AN ELECTROLYTIC CELL FOR THE ELECTROLYSIS OF ALKALI METAL CHLORIDE SOLUTION COMPRISING A BASE MEMBER HAVING ASSOCIATED THEREWITH A PLURALITY OF ELECTRICALLY-CONDUCTIVE METALLIC GRID MEMBERS DEFINING A SERIES OF SPACED SLOTS THEREBETWEEN AND POSITIONED UPON SAID BASE MEMBER, ELECTRICALLY CONDUCTIVE OUTER SIDE WALLS AND INNER SIDE WALLS MOUNTED ON THE BASE, THE OUTER AND INNER SIDE WALLS WITH THE BASE DEFINING THEREBETWEEN A PERIPHERAL LIQUID-CONTAINING CHAMBER, THE INNER SIDE WALLS WITH THE BASE DEFINING AN INNER-LIQUID CONTAINING CHAMBER, A PLURALITY OF ANODES FIXED IN THE SLOTS BETWEEN SAID GRID MEMBERS UPON THE BASE MEMBER AND VERTICALLY DISPOSED WITHIN THE INNER CHAMBER, A PLURALITY OF HOLLOW, TUBULAR, FORAMINOUS ELECTRICALLY-CONDUCTIVE METAL CATHODES INTERPOSED BETWEEN THE ANODES, SAID TUBULAR CATHODES BEING HORIZONTALLY DISPOSED IN THE INNER CHAMBER AND EXTENDING COMPLETELY ACROSS THE CHAMBER AT LEAST FROM INNER SIDE WALL TO INNER SIDE WALL, THE TUBES OF SAID CATHODES DEFINING CATHOLYTE COMPARTMENTS THEREWITHIN, AND BEING FIXED

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