US2361974A - Electrolytic cell - Google Patents

Description

NOV- 7, 1944 J. N. SMITH 2,351,974

BLECTROLYTIC CELL Filed Feb. 7, 1940i 2 sheets-sheet 1 nNvsN-ron MM/man .Sm/1% E I ATTORNEY Nov. 7, 1944. J. N. SMITH BLECTROLYTIC CELL Filed Feb. 7, 1940 2 sheets-snm 2 m W i ATTCRNEY Patented Nov. 7, 1944 ELEczraoLr'rrc cm1.

James Norman Smith, Montreal, Quebec, Canada, asslgnor, by direct and mesne assignments, of one-fourth to John A. Rietmann, Norwalk, Conn., and one-fourth to George F. Hndel,

New York, N. Y.

' Application February 7, 1940, Serial No. 317,682

7 claims. tcl. ani-26o) My invention relates to electrolytic cells and more particularly to cells adapted to be used for the electrolytic decompositioxt of aqueous saline solutions, such brine, to produce chlorine, sodium hydroxide and hydrogen.

One of the objects of my invention is to provide an improved cell in which the internal resistance is reduced to a high degree.

Another object of my invention is to provide an improved cell of the character described which shall be simple and economical to manufacture and assemlble, rugged in construction, and which shall have a high eillciency of operation.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the fea- .tures of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter described, and of which the scope of application will be indicated in the claims.

In the accompanying drawings, in which are shown various possible embodiments of this invention,

Fig. 1 is an elevational sectional view of an electrolytic cell embodying my invention;

Fig. 2 is a sectional view taken along the line 2 2 of Fig. 1 and showing the elements of the cell in partial detail;

Fig. 3 is an enlarged sectional view taken along the line 3-3 of Fig. 1;

Fig. 4 is a plan view of a diaphragm forming member with the formed diaphragm in position thereon;

Fig. 5 is an enlarged sectional view taken along the line 5-5 of Fig. 4;

Fig. 6 is an enlarged view taken along the line 6-6 of Fig. 4;

Fig. 'I is an enlarged sectional view taken along the line 'I-'I of Fig. 4;

Fig. 8 is an enlarged sectional view taken along the line 8--8 of Fig. 5;

Fig. 9 is a view similar to Fig. 3 showing a modified form of my invention; and

Fig. 10 is a View similar to Fig. 3 showing another modiiied form of my invention. 4

Referring now in detail to the drawings and more particularly to Figs. 1 through 3, there is disclosed an electrolytic cell constructed in accordance with my invention and 'comprising a cell tank Ill which may be fabricated from sheet steel. 'I'he tank I0, which may be of circular cross-section (as shown in Fig. 2) or any other cross-sectional coniiguration deemed economical, includes a side wall II and a bottom plate I2.

' lying the angle iron ring I5. A sealing Joint between the ii'ange I9 and supporting ring I5 is provided in any suitable manner, such as by use of a layer 20 of a mastic substance. Lugs 2 I, having holes 22 therein, may also be provided at spaced points around the ange I 9 to provide means for conveniently lifting the removable cell cover I6 from the electrolytic cell.

Projecting inwardly from the upper portion of the barrel I8 are a pair of flanges 23 adapted to support a slab 24 of concrete or other suitable insulating material having a central aperture 25 through which a positive electrode or anode depends. Another aperture 26 is provided for the removal of chlorine. While in the embodiment of my invention herein described, the slab 24 ls formed by pouring concrete into the top I1 while keeping an auxiliary mold in position to define the bottom and central aperture 25 of the slab, it is to be understood that the method and means for forming the slalb is no part of my invention and the slab 24 may be assembled in any other manner well known in the art. At the lower edge of the barrel I8, there may be formed an inwardly extending flange 21 having a downwardly depending lip 28 on which a diaphragm is supported in a manner hereinafter described.

Means may also be associated with the top Il to support a negative electrode or cathode. Said means may comprise a plurality of tubes 29 equidistantly spaced around the inside of the barrel I8 and formed integrally therewith.

'I'he anode may comprise a graphite core 30 which passes freely through the central aperture 25 in the concrete slab and is clamped at its upper end by a copper terminal 3i having an internal ridge 32 adapted to engage a circumferentiallower end with a closure pan electrolytic cell. For this purpose, I may employ an asbestos cloth treated with any suitable inert insulating composition commonly known to the art. The composition known as Nitrose may be used for this purpose. This composition may be purchased from the Nitrose Company, of Peoria, Illinois. The portion of the anode 30 projecting beneath the collector top I1, may be formed with a plurality of long vertical slots 35,v

each adapted to snugly receive and frictionally retain a graphite strip 36, In the embodiment of my invention herein disclosed, I have shown fifty-six strips having their free ends arranged in substantially circular outline. It will be apparent, however, that a greater or lesser number of strips may be used and that the free ends :of these strips may be arranged in other than a circular outline without departing from the spirit of my invention.

Brine is fed into my electrolytic cell through a central bore 31 running vertically through the anode 30. Inclined recirculating bores 38 run from the brine feed 31 to the outer surface of the anode 30 above the upper ends of the graphite strips 35, thus preventing any abnormal rise in the anolytic liquid level and consequent flooding of the gas collector. s.

A vertically pleated asbestos diaphragm 39 surrounds the anode 30, being secured at its upper end to the collector |1 and being provided at its 40 having a drain plug 4|.

I prefer to formand mount my diaphragm in the following manner: I lay the diaphragm over a diaphragm former (see Figs. 4 to 7) having a width slightly less than the width of the diaphragm and force the diaphragm into thegrooves |0|, thus forming a series of folds or pleats in the diaphragm.

After the folds are formed, the bottom of each end of the fold extending beyond the former |00 is brought back between the walls of the folded pleat to a point slightly above the surface of the former, as shown in Fig. 5, to make a, formed end |02. A U-shaped temporary spring clip |03 is then placed over each end of the fold, thus holding the diaphragm in pleated shape ready for assembly in the electrolytie cell. Finally, the diaphragm is removed from the former |00 and placed over the anode 30, each fold lying between two anode strips 36. I'he two vertical ends of the diaphragm are then brought together and held by a suitable clamp 44 and the clip |03 removed.

Each formed upper end |02 is placed in a slot 45 in the collector lip 28 and each formed lower end is placed in a corresponding slot 46 in the closure pan 40. To make certain that no chlorine or brine will pass through any point of contact of the diaphragm with the collector or closure pan, a strip of asbestos webbing 411s wound around the diaphragm and beyond the ends thereof. Bands 48 may be employed to clamp the diaphragm and webbing to the collector I1 and closure pan 40.

The above method and means for forming and mounting the pleated diaphragm have been found to give highly satisfactory and consistent results, Other methods and means for forming and mounting the pleated diaphragm may, however, be employed, without departing from the spirit of my invention.

The cathode comprises a set of eight rods 49 freely slidable in the collector tubes 29 and held against vertical displacement by a terminal clamp 50 and gasket 5| of asbestos cloth treated with a suitable inert insulating composition such as that employed to treat the anode gasket 34. If desired, the portion of the rods 48 located within the tubes 29 may be covered with a thin mica sheet held in place by asbestos cord and a few coats of a suitable inert insulating composition brushed over the mica and asbestos.

Adjustably mounted on each rod 40 are a pair of abutting metallic cathode sectors 52 preferably made of iron or steel, each comprising a bearing 53 carrying an arcuate plate 54 from which, in this particular embodiment of my invention, seven cathode fingers 55 project toward and in alignment with the graphite anode strips 36. Bands 55' clamped around the upper and lower ends of each plate 54 carrying the cathode fingers 55 force the inner face of the fingers into contact with the diaphragm 39 and the diaphragm in turn into contact with the outer face of the graphite anode strips 36, as clearly shown in Fig. 3, thus clamping the diaphragm between the anode and cathode and urging the strips 36 against the anode 30.

One or both of the opposed faces of the graphite strip 36 and fingers 55 which contact the diaphragm are covered with a layer of insulating material since otherwise the chlorine and hydrogen formed on their faces would polarize the electrode, as neither the catholyte nor anolyte could circulate between the faces to remove the accumulated clinging gas bubbles. Any well known inert insulating materials or compositions may be used for the insulating layers 56 and 51 on the strips 38 and fingers 55. For example. I have found Nitrose to be suitable for the layers 56 on the graphite strips and sheet mica, rubber or porcelain enamel satisfactory for the layers 51 on the fingers.

Since the most effective portions of the electrode surface are the side walls of the strips 36 and fingers 55, these members preferably project from the core 30 and plate 54, respectively, a distance greater than the width of the strips or fingers, as the width of these members 36 and 55 determines the amount of inactive surface of the electrode or diaphragm due to the insulating layers 56 and 51,. Also preferably these members project from the core 30 and plate 54 a distance greater than the space between them as the body portions of the anode and cathode from which the strips and fingers project are the furthest from the diaphragm, and therefore, the most ineffective portions of the electrodes. If desired, the aligned strips 36 and fingers 55 may be made broader at their base and tapered toward the diaphragm, as shown in Fig. 9, to reduce the width of the faces insulated with the layers 56 and 51 and also reduce the spacing between the bases of the strips and fingers.

'I'he anolyte level is maintained above the recirculating bores 38, substantially as indicated by the dot-dash line on Fig. 1. lThe catholyte level is maintained slightly lower than the anolyte level. I may coat all the inactive interior portions of my cell with inert insulating materials.

During the operation of my improved cell, an extremely rapid circulation of the anolyte is obtained due to the restricted area of vertical ow, the feed of brine at the bottom of the anode and the provision of recirculating means for the anolyte. This rapid circulation continually Washes the exposed faces of the graphite strips.

removing the chlorine bubbles as soon as they begin to form and thus maintain a maximum area of active anode surfacea condition under which the maximum current will flow for a given voltage and the internal resistance of the cell will be at a minimum.

The very small distance between the anode and cathode surfaces, resulting from my improved electrode and diaphragm construction, will reduce the length of current path and will, therefore, further reduce the internal resistance of the cell.

Tests conducted at various temperatures and ampere ratings on cells constructed in accordance with my invention have shown that a lower operating voltage is obtained in my improved cell than has been hitherto possible in saline electrolytic cells and that corespondingly less power is therefore dissipated by the internal resistance of the cell.

In the modied form of my invention shown in Fig. 10, the cell tank, anode and cathode are constructed and assembled in the same manner as those described in reference to Figs. 1 through 3. In this form, however, the diaphragm 10, instead of being pleated, is smooth and may be drawn somewhat tightly over the graphite strips. I have found that this manner of diaphragm assembly gives satisfactory results and at the same time is easier toarrange and assemble than the form of diaphragm shown in Figs. 1 through 3.

It will thus be seen that there is provided a device in which the several objects of this invention are achieved, and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes -might be made in the embodiments above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. In an electrolytic cell of the character described, a central electrode having a plurality of substantially vertical channels and immersed in electrolyte, a diaphragm surrounding and contacting said electrode between said channels, a gas collector associated with said central electrode and said diaphragm, and means to prevent flooding said gas collector, said means comprising passageways within said electrode to permit the now of electrolyte from above said channels to below said electrode. e

2. In an electrolytic cell of the character described wherein a-tubular foraminous diaphragm of insulating material is disposed between a cathode and an anode, an electrode 'assembly comprising a central anode immersed in an electrolyte, said anode having a plurality oi electrically conductive projecting portions so arranged that adjacent projecting portions form a series of unbroken vertical channels, means to prevent flooding a gas collector in said cell. said means comprising passageways within said anode for circulating said electrolyte from adjacent the tops of said channels through the interior of said snode to adjacent the bottom of said channels, and a cathode disposed around said anode, said cathode having a plurality of electrically conductive projecting portions so arranged that adjacent projecting portions form a second series of unbroken vertical channels, the projecting portions on the cathode and anode being in substantial linear alignment and of substantially the same width, the vertical side faces of the projecting portions on the cathode and anode being in substantial planar alignment, and the tips of each of said projecting portions having a layer of insulating material secured to its face and in contact with 4said diaphragm,

3. In an electrolytic cell of the character described, wherein a foraminous diaphragm of insulating material is disposed between a cathode and an anode, an electrode assembly including an anode comprising an electrically conductive member having a plurality of electrically conductive projecting portions so arranged that adjacent projecting portions form a series of unbroken vertical channels, and a cathode comprising an electrically conductive member having a plurality of electrically conductive projecting portions so arranged that adjacent projecting portions form a second series of unbroken vertical channels, the projecting portions on the cathode and anode being directly opposed in substantial linear alignment and of substantially the same width, the vertical side faces of the projecting aligned portions on the cathode and anode being in substantial planar alignment, and the tips of each of said projecting portions having a layer o1 insulating material secured to its face and in contact with said diaphragm whereby a very small distance between the anode and cathode surfaces is maintained.

4. An electrolytic cell as set forth in claim 3, wherein the anode is centrally disposed and immersed in an electrolyte, wherein the cathode is disposed around the anode, and wherein the diaphragm is tubular.

5. An electrolytic cell as set forth in claim 3, wherein the anode is centrally disposed and immersed in an electrolyte, wherein the cathode is disposed around the anode, wherein the diaphragm is tubular, and wherein said projecting portions taper from their bases toward their tips.

6. An electrolytic cell' as set forth in claim 3, wherein the anode is centrally disposed and immersed in an electrolyte. wherein the cathode is disposed around the anode, wherein the diaphragm is tubular, and wherein said projecting portions extend away from said members a distance greater than the width o! said projecting portions.

7. An electrolytic cell as set forth wherein the anode is centrally' disposed and4 immersed in an electrolyte, wherein the cathode is disposed around the anode, wherein the diaphragm is tubular, and wherein said projecting portions extend away from said members a distancegreater than the width ot said projectingportions and greater than the distance between such portions.

JAMIE NORMAN SMITH.

inclaimS.

Images