US2475157A - Electrolytic apparatus - Google Patents

Description

y 1949- J. c. SCHUMAC-HER 2,475,157

ELECTROLYT I G APPARATUS Filed Oct. 51, 1945 2 Sheets-Sheet 1 N a 8 w. D

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I I I 1 l2 F 92 I i l a I i 8 t i :5 *2 N lNYENTOR EG- JOSEPH vc. SCHUMACHER ATTORNEY July 5, 1949. J. c. SCHUMACHER ELECTROLYTIC APPARATUS 2 Sheets-Sheet 2 Filed Oct. 51, 1945" 'IOOOOO 0OQOO E W I INVENTOR JOSEPH SCHUMACHER ATTORNEY Patented July 5, 1 949 NITED STATES ATENT FFICE ELEGTBOLYTIC APPARATUS Application (lctobcr 31, 1945, Serial No. 625,859

3 Claims.

This invention relates to an improved electrolytic cell and in particular to an electrochem ical cell for use in making perchlorates.

One object of the invention is to provide an electrolytic cell of the non-diaphragm type for the electrolysis of aqueous solutions. Another object is to provide an improved electrolytic cell in which the operating conditions for an electrochemical reaction may be adequately controlled. Still another object is to provide an anode structure for an electrolytic cell utilizing thin sheets of platinum metal. These and other objects are attained by my invention which will be understood from the following description, reference being made to the accompanying drawings in which:

Fig. 1 is a top elevational view of a. preferred form of my electrolytic cell;

Fig. 2 is a side elevational view of the same with. parts broken away to show the interior arrangement;

Fig. 3 is an end elevational view of the same;

Fig. t is a cross-sectional view taken on the line t-t of Fig. 2;

Fig. 5 is a cross-sectional view taken on the line 5-5 of Fig. 2; and

Fig. 6 is a cross-sectional view taken on the line 6-5 of Fig.2.

My improved electrolytic cell is particularly adapted for use in the electrochemical oxidation of sodium chlorate to sodium perchlorate in aqueous solution and the following description will be made with particular reference to a preferred form for use in carrying out this reaction, although it will be understood that the inventlon may be employed in other electrochemical reactions lnVOlVilflg other chemical transformations.

In general my electrolytic cell consists of an elongated trough-like steel tank having an electrically insulating cover through which extend thin platinum sheet electrodes supported by suitable holding members, with cooling coils dis-- posed between electrodes, and cooling jackets provided on the outer side Walls of the tank, the steel tank and attached steel parts insie the cell constituting the cathode.

Referring to the drawings, my electrolytic cell consists of an elongated steel tank l l with an open top and outwardly extending flanges 52 around the upper edge. Channels for cooling liquid are provided by longitudinally placed steel jackets welded to the two side walls 5 ill of the tank ll, these being subdivided by horizon tal partitions iii to distribute thechfiulatiag;

cooling liquid. Further control of the temperature in the cell is attained by the use of a tier of steel tubes l5 extending centrally through theelectrolyte compartment of the cell between theanodes H, the ends of these tubes being connected to manifolds It on the two ends of the tank ll so that the coolin liquid may be circulated not only through the side wall jackets IE but also through these tubes disposed between the platinum cathodes 6'! within the electrolyte compartment of the cell. The cooling water enters through the pipe 2i. and is withdrawn through the pipe 22. The cell cover plates 18 consist of sheets of chemically resistant artificial stone material, for example, sheets made of com pressed mixtures of Portland cement and ashes-- me, which sheets are attached by bolting to the flange I2 around the upper edge of the. tank. Slit openings 49 fittin the platinum electrode sheets 2d are provided in this artificial stone cover I8 for the insertion of the anodes. The steel surfaces of the tank H and the water-cooling tubes id in contact with the electrolyte serve as the cathode for the cell. v

The electrolyte is introduced through the influent pipe ZIA and is withdrawn through the overflow or efiluent pipe 22A tube. The cell isespecially adapted for use in a process requiring the circulation or recirculation of the electrolyte in and out of the cell but it may also be used in a discontinuous process or in a batch or intermittent process in which the cell is filled with electrolyte which remains in it until the elec trochemical reaction is completed to the desired stage.

In most electrochemical processes of the type to which this cell is adapted, there is evolved a mixture of gases often in explosive proportions. In the case of the electrochemical oxidation of sodium chlorate to sodium perchlorate for example, varying amounts and proportions of hy drogen, oxygen, and chlorine gases are evolved, and it necessary, in order to avoid explosions. to remove this or dilute it with-another gas to a mixture which is no longer explosive. Provision is made in my cell for their itroduction of aswceping out gas through the influcnt pipe 2'3 and the removal of theniixture of gases from the efiiuent pipe 2t.

In electrochemical reactions requiring the use of platinum anodes, it is important, because of the high unit cost of platinum to use as small a quantity of the metal as possible. My platinum electrodes ll consist of a thin sheet 233 of plati, im ut .0. i hribi h aoiehdeidettsfi.

with numerous holes in order to provide ready circulation of the electrolyte through and around all portions of the platinum surface. The thin sheet of platinum is inserted through the cover plate l8 through an opening I9 provided therein. Above the cover plate, the upper end of the thin platinum sheet is pressed between relatively heavy sheetsof'icopper 25, and the sandwich thus formed is bolted together between the vertical portions of L shaped bars 25 by bolts 29, which in turn are bolted along the horizontal Sides to the cover plates l8 by means of threadedstuds 21 of headed machine screws set in holes in the artificial stone cover plates l8. Inorder tov prevent twisting and buckling of'the extremely-thin electrode sheet within the cell, it is positioned in substantially aligned position between depending glass bars 28 which are suspended from and rigidly held adjacent the platinum sheets 26 in countersunk holes 39 in; the cover plates is, the glassibazrsz being provided with flanges ii to fit in: countersunk"holes,vbeing cemented in place by; suitable: chemically; resistant material. The glass-bars. 28 are disposed at intervals along the lengthoftherelectrode and extend as far as the depthof theplatinum sheet.

The; cathode ofzthe cellzconsists of the surfaces of; the'lsteelitankl and the steel tubes used for w-aterscooling which: are. in contact with the electrolyte-.. An'lupright bar: member welded to a thaflange-aonnonelside.at the top edge of the tank.

presides; a'i. convenient electrical connection for.

. the-cathode; to: the bus. bars of the electrical System;

. My improvedielectrolytic; cell. is particularly" adapted;iorrelectrochen'iical. oxidation reactions which; may? utilize; thehigh over+voltage of a platinumtsurf aceaon the; anode. Myanode struc ture'permittlng-themse ofthe very thin platinum materialiallowsthe' commercial use of this metal for anodes. whereas: heavier self-aligning sheets offplatinum arexprohibitive in price, and platinum clad composite sheets with base metals such as copper have been foundto disintegrate rapidly becauseofi undetectedilpinliolesv in the thin plati- .numcovering:sheets.v By using anodes'of plati nun hmetaLonly; evenit'hough extremely thin, the pirirlioles. (sometimeszpotential' or undetectable prior/to. actual anode use) which are characteristieof tliin platinum sheets, do not cause any trouble because of the absence ofthe base metal contact in the electrolyte zone. In my anode structure; allcontact'of" the platinum with other metals is outside and protected from electro chemical action.

By using theplatinuinanode, I am able to employ-highercurrent-densities perunit area, and higher voltages, which result in greater efiiciency, andita l'so in-more=heating of the electrolyte, and more danger of local overheating from nonuniform" conductivityor for other causes. In order -to maintain uniform and optimum conditions "Of'0perfllt10n of the'cells, it is necessary to provide large capacity cooling means, which in= chides the ,pipecoils. between the electrodes, and thesout'side-icoolingjackets; Uniformity of tern perature: and concentration within the electrolyte is-also -providedby=the means for circulating the electrolyte in and out of the cell, and over the electrode surfaces to'remove the generated gas thereon.

These charactristics of my improved electrochemicalilcell are advantageously employed in the process;-v oi electrochemically oxidizing sodium ttiwrateabsusmm ps'rohloraterwhich is filllyde 4 scribed in my copending patent application Serial No. 625,857.

I claim:

1. An electrolytic cell comprising an elongated steel tank adapted to contain an aqueous electrolyte and to serve as cathode; and electrically insulating cover for said tank having openings for nonsrigid' platinum sheet anodes, vertically disposed anode-holding" insulating rods rigidly supported by said cover along the perimeters of said openings and adapted to laterally position said sheet anodes to keep them in alignment; an anode member for said cell including rows of anode assemblies disposed lengthwise of said cell, each assembly consisting of a thin non-rigid sheet of platinum sandwiched between co-extensive sheets of another metal in the portion above said cover plate with metallic clamping bar members for said sandwich having attaching means to hold said assembly on the cover above the anode openingtherein; means for maintaining temperature uniformity; inxthezelectrolyte' include ing steel pipe coils for" cooling medium disposed between the rows of platinum sheets and serving as cathode surfaces; and means for circulating the electrolyte-inthe cellaround the anodes and from one end oi the cell..to-v the": other'includmg baifies; inlet pipes. and' overflow discharge openings.

2. An electrolytic-cell comprising anelongat'ed steel tank'adapted tolcontainian aqueous'electrolyte and to serve ascathode; jackets for circulation of cooling-,liquid. on thewalls of said tank; an electrically" insulating cover for said tank. having openings for non-rigid platinum sheet anodes; vertically disposed anode-holding insulating rods rigidly supported by said cover along the perimeters of said openings and adapted to laterally" position said sheetanodes to keep them in alignment'yan anode member-for. said cell including rows of anode assemblies disposed lengthwise" of 'saidcell, each assembly-consisting of a thinnon-rigidhheetofplatinum sandwiched between co-extensive sheets of another metal in the portion above said cover-plate with metallic clamping bar members for said sandwich having attachingmeans to hold said assembly-on the cover above the anode opening therein; means for maintainingtemperature-uniformity in the electrolyte includingsteel pipe coils for cooling medium disposedbetween therows-of platinumsheets and interconnected to'saidjackets on'saicl' tank for common flow of cooling medium; said coils serving also-as cathode surfaces and means for circulating the (electrolyte i'n the cell around the anodes-and.':f1'om-One-endOfthe cell to the other including battles, inlet pipes and'overflow discharge openings.

3. An electrolytic cell comprising an elongated steel tank'adapted to contain an aqueous electrolyte and to serve as cathode; jackets for circulation of cooling liquid on the walls of said tank; an electrically'insulating coverfor said tank having openings fornon-rigid platinum sheet anodes; vertically'disposed anode-holding insulating'rods rigidly supported by said cover along the perimeters of said openings and adapted to laterally position said sheet anodes to lace them in alignment; an anode member for said cell including rows of anode assemblies disposed clamping Barmemliers'for? said sandwich having attaching means to hold said assembly on the cover above the anode opening therein; means for maintaining temperature uniformity in the Number electrolyte including steel pipe coils for cooling 0 medium disposed between the rows of platinum 5 665,426 sheets and interconnected to said jackets on said 706, tank for common flow of cooling medium; said 314,155 coils serving also as cathode surfaces; and means 331,343 for circulating the electrolyte in the cell around 893,472

the anodes and from one end of the cell to the 10 a 930,902

other including baflles, inlet pipes and overflow 1,085,742

discharge openings; and means for introducing 1,609,771

inert cooling gas between the cell cover and the 2,222,195

upper level of the contained electrolyte and for withdrawing the inert gas along with the gener- 15 ated gas mixture from said cell whereby to cool Number the non-immersed portions of said anodes within 1731028 said cell. 431-252 JOSEPH c. SCHUMACHER. 4881984 REFERENCES CITED The following references are of record in the file of this patent:

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