US2786811A - Electrolytic cell for producing gases - Google Patents

Description

March 26, 1957 R. B. sw oPE ELECTROLYTIC CELL FOR PRODUCING GASES Filed Dec. 1, 1955.

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v Fl 6. 8. l7 IE5 n INVENTOR. ROBERT BSwoPE' Y Y Y 1 m Vi 26 HIS flTTO/QNiYS March 26, 1957 R. B- SWOPE ELECTROLYTIC CELL FOR PRODUCING GASES 2 Sheets-Sheet 2 Filed Deo. 1,- '1955 -IN VEN TOR.

ROBERT B. SWOPE LL/M w M w 23 T H q B 6 l 6 |u||L| G iw z 1 I H F H MWZO I 6 m l 6 H I l I!Vl 2,786,811 ELECTROLYTIC CELL FOR PRODUCING GASES Robert B. Swope, Washington, D. (3.

Application December 1, 1955, Serial No. 550,350

4 Claims. (Cl. 204-256) My invention relates to electrolytic cells for the production of gases by electrolysis, particularly hydrogen and oxygen, and aims to increase the output and enhance the quality of such gases by improvements in the construction of the cells whereby they may be assembled in multiple cell units and operated in a battery of several such units, resulting in a saving in space and electric current as well as in a uniformly good product. V

For many years electrolytic cells have been constructed as single cell units arranged in line and connected in series in order to produce gases of sufficient purity to satlsfy the requirements for industrial and therapeutical purposes, but such arrangements have many disadvantages, as they occupy large floor space, are costly to build, and the electrical connections between the cathode of one cell and the anode of the next cell are not only heavy but cause loss of power because of the large amperage of the operating current.

The filter press type of multiple cell unit as heretofore constructed has not been found satisfactory for various reasons, as it was difficult to maintain a high standard of purity of the product, and the repairing or replacement of a single defective cell required dismantling the assembled group of cells with loss of the entire output of the unit pending its restoration to service.

I have overcome these disadvantages by a new form of cell unit made up of individual sections involving a saving both in manufacturing and in operating costs, as hereinafter described in connection with the preferred form of the invention illustrated in the accompanying drawings, the characteristic features of which are set forth in the appended claims.

In the drawings, in which like reference numerals designate the same or like parts in the several views:

Figure 1 is a front elevation of a unitary assembly comprising six electrolytic cells connected in series for operation on a direct current power line at about fifteen volts potential;

Figure 2 is a top plan view;

Figure 3 is a side elevation of the same, Figs. 1, 2 and 3 being drawn to the same scale;

Figure 4 is a plan view of the mid portion of the cell assembly showing the arrangement of the inlet and outlet connections for circulating the liquid electrolyte, and the outlet connections for the gaseous products;

Figures 5 and 6 are vertical cross-sections on the line 5-4; in Figure 4, Fig. 5 showing an upper corner and Fig. 6 showing a lower corner of one of the cell frames, Figs. 4, 5 and 6 being drawn to the same scale larger than that of Figs. 1, 2 and 3;

Figure 7 is an enlarged cross-section of a portion of the frames of several cells on the line 7-7 of Fig. 4; and

Figure 8 is a general plan view of six sectional cell units assembled in a battery, showing the. electrical connections diagrammatically. The number of cells in each unit and the number of such units in the battery may be varied.

Referring to Figs. 1 through 4, my improved cell unit atct Patented Mar. 26, 1957 is composed of twelve frames 10 forming six similar sections between the plate electrodes 11, each section being divided into two gas- tight chambers 12, 13, by gas-tight diaphragms 14 (shown best in Fig. 7) which may be slightly permeable to liquids but are insulated from the frames 10 by suitable gaskets 15. The sections are separated from each other by the plates 11, which are preferably made of sheet iron or steel. The anode side of each plate is covered with a nickel coating 16 to protect it from oxidation. The cathode side of each plate 11 is bare iron or steel.

The endmost plates 17, 18 are heavier guage than the intermediate plates, and the entire assembly of frames, separator diaphragms and plates is securely clamped together by suitable means such as corner clamps 19 and through bolts 20, which are electrically insulated from the adjacent plates by strips of neoprene, Bakelite, fibreboard or other insulating material. Intermediate clamps 21 of C-type engage the edges of the frames between the corners and assist in securing them together, these clamps also being spaced from the frames by strips of insulation. Lugs welded'to the respective end plates and connected by through bolts insulated therefrom may be substituted for the 'o-clamps.

The frames are disposed vertically with their edges at 45 to the horizontal and are supported at opposite corners by lugs 22 welded thereto which rest upon suitable angle brackets 23 carried by pedestals 24, being insulated therefrom by rubber pads 25 or other suitable means. Each unit is supported on its own pair of pedestals 24 which are arranged in parallel rows lengthwise of the battery, with the negative end plate 18 of each unit connected to the positive end plate 17 of the adjacent unit by heavy conductors 26 as shown in Fig. 8, these conductors being bolted or otherwise secured to convenient 'C-clamps 21.

The nickel coated end plate 17 at one end of the battery is connected by a cable 27 to the positive pole of a suitable source of direct current, such as a rectifier or rotary converter (not shown) furnishing a current of sufficient amperage and voltage to operate the entire battery, which may contain eight six cell units where -120 volt D. C. current is available. The bare iron end plate 18 at the opposite end of the battery is connected to the negative pole of the source of direct current by a similar cable 23. Short cables 29. may be used to connect the cables 27, 28, respectively, to adjacent C-clarnps or lugs which make good electrical contact with the end plate 17 at one end of the battery of cell units and with the end plate 1.8 at the opposite end of the battery. Like cables 25* may be used for connecting pairs of 'C-clamps or lugs securing the intermediate sections together, all of these C-clamps or lugs being in electrical contact with the end plates at their ends to which the cables are connected.

The cell frames 16 are made of square steel tubes welded together at the corners to form a continuous conduit extending around the entire periphery of the plate to which they are welded on both sides. At the upper corner one tube butts against the adjacent tube, as shown in Fig. 5, the two tubes being in communication through a hole 39 in the latter tube, the end of which extends beyond the corner far enough to permit a tubular outlet piece 31 to be welded on for receiving a rubber hose connection. A series of holes 32 is drilled in the inner wall of each tubular frame member 1!) oneach side of and close to its upper corner to permit gas forming on the plates in the chambers 12, 13 to escape through the outlets 31. The frames welded on the bare iron sides of the plates are all oriented with the outlet 31 extendin upwards and to the left and the frames welded on the nickel sides of the plates are all oriented with the outlets 1 xt n ng uswar s an t t e h for co n n in connecting these outlets to the hydrogen collector or take olf main and to the oxygen collector or take off main, respectively, when in operation producing these gases. Rubber tube connections 33, 34 are provided for connecting these outlets to the oxygen collecting and hydrogen collecting means, respectively.

; The electrolyte, which may be a solution of sodium hydroxide (NaOH) or potassium hydroxide (KOH) of a strength below that likely to cause either the nickel or the iron to dissolve, is supplied to each cell individually from a series of receptacles 35 supported on a bracket 36 attached to a convenient part of each unit, such as one of the upper C-clamps 21, for example, as shown in Fig.

1. These receptacles 35 are insulated from each other v and from the bracket 36 by means of suitable strips 37 of rubber, neoprene or other insulating alkali proof material, and' are connected to the respective frames to surrounding the chambers 12 by means of neoprene conwelded on the outside of the adjacent frames 1% and into which they discharge. Openingsfii) in the inner Walls of extending through the intervening diaphragms 14 and gaskets 15, permit the; electrolyte to flow freely between the chambers 12 and 13 to equalize the level therein, which below the gas outlet openings 32 during the operation of Y the unit.

The level of the circulating electrolyte is controlled by means of individual weir boxes 45 positioned at a some- ,what lower level than the supply receptacles 35 in order to provide a hydrostatic head for causing slow circulation of the electrolyte through the chambers 12, 13. The electrolyte is withdrawn from these chambers through the encircling frames 16 by means of pipes 46 and Y-connections '47 emptying into the Weir boxes 45 from which the elec- -trolyte discharges over individual spillways 43 into a trough 49 from which it is withdrawn through a pipe 50 by a suitable pump and returned to a storage tank from which it is supplied to the receptacles 35 by individual feed pipes 51.

The pressure of the oxygen and hydrogen gas in their respective gas holders determines the level at which the "electrolyte stands in the chambers 13 and i2, and this pressure is maintained substantially constant except for occasional surges caused by fluctuations in the operating conditions and in the amounts of gas withdrawn from time to time from the gas holders.

An important feature in the construction of the cell units is the nature and dimensions of the rubber-like gaskets which are cemented to the frames 10 and diaphragms 14 by a plastic compound consisting of neoprene dissolved in any one of the solvents customarily used for this purpose. This plastic compound also penetrates the interstices in the asbestos fabric of which the diaphragms are preferably made and prevents passage of liquid or gas through the portions of the diaphragms so protected.

. 1e gaskets 14 are cut somewhat wider than the frames 1!) so as to project outwardly therefrom around the entire outer periphery thereof sufficiently to prevent electric current from bridging the space between one frame and the next at the joints with the diaphragms, and so as to project inwardly into the chambers 12, 13 by a distance about one and one-half times greater than the shortest line between the adjacent plates or frames and the edge of the plate to -'-prevent electric current from leaking across the edges of the frames. 1

At the upper corners of the frames the gaskets are wide enough to dip into the electrolyte, and the entire corner area 52 of each gasket is so firmly cemented to the dia- -phragm 14 as to prevent any gas from seeping between the 5 gasket and diaphragm, the plastic'neoprene composition which permeates-the diaphragm beneath the corner area nector's 38whi'cl1 slip over the open ends of steel tubes 39 is maintained above the upper liquid flow openings 46 and 52 of the gasket serving to prevent seepage of electrolyte and gas into and through the diaphragm at this point where fluctuations in the pressure of the gas on opposite sides of the diaphragm might otherwise cause some comingling of the two gases which fill the upper corners of the chambers 12, 13 at all times during operation of the battery at pressures which are determined by the conditions momentarily prevailing in the respective collector mains and gas holders.

Although I prefer to use gaskets of sensible thickness between the diaphragms 14 and frames 10, thin plastic coatings of rubber, neoprene or polymerized organic materials such as polyethylene, dissolved in a suitable solvent, may be utilized to impregnate the diaphragm at the places where it is desired to prevent passage of any gas in lieu of the gaskets. By making this impregnated strip of a width one and one-half times the length of the normal path of the current flowing in the electrolyte between the anode and the cathode, the tendency of the current flow to concentrate around the edges of the cell is largely overcome and thereby the likelihood of local action on the edges of the frames such as to produce a mixture of gases is forestalled.

Other advantages of my invention stem from the provision of square tubing for the frames 10, permitting circulation of the electrolyte through these hollow members with little chance for comingling of the gas produced in one chamber with gas produced in the other chamber, as the circulation of the electrolyte from one chamber to the other can only take place through the lower pair of circulating holes 40 and the equalizing interchange openings 41. Furthermore, the circulation of the electrolyte through the hollow frames 10 tends to cool these parts of the cells as well as the plates 11.

The voltage drop in a six cell unit as illustrated herein is too low to be dangerous to operating personnel and no safeguards are required beyond the rubber insulating pads and rubber tube connections for circulating the electrolyte to prevent leakage of current at these points, the resistance of the electrolyte being sufficient to prevent short circuiting adjacent cells through the electrolyte in the pump and supply system.

Furthermore, the removal of one or two sectional units for repair or cleaning can be readily effected without taking the entire battery out of service as it is only necessary to close the electrolyte supply and gas takeoff lines to the units to be withdrawn, remove the rubber, connecting tubes, break the electrical connections and connect the adjacent units by a suitable conductor, whereupon the disconnected unit can be lifted out of its place and removed.

The invention is not restricted to the form of apparatus illustrated, but I claim the following:

1. An electrolytic cell unit comprising a plurality of cells formed by a series of square plates arranged in metal as the adjacent plates to whichthey are secured with liquid and gas tight joints, one side of each plate and the adjacent face of the frame secured thereto being 1 coated with a protectivemetal facing and thesuccessive plates being arranged with the coated side of one plate facing the uncoated side of the next plate in said unit to form a single cell thereof, gas-tight. liquid I. permeable diaphragms of approximately thesame size. as the plates having liquid and gas tight insulating margins squeezed between the frames of successive plates in each unit, said diaphragms dividing the successive cell spaces each into two chambers, means for clamping the plates, frames and diaphragms together and for supporting'the unit thus formed with the. several cells electrically insulated from each other, said frames having gas outlet openings :in their inner wallsyat their upper corners into said chambers,

two gas collectors and individual ducts for connecting one to the upper corner of every alternate frame and the other to the upper corner of each intervening frame in said unit, and means for supplying and maintaining a liquid electrolyte in said chambers at a level below said gas outlet openings.

2. An electrolytic cell unit as set forth in claim 1 wherein the frames have liquid circulating openings in their inner walls and liquid inlet openings and outlet openings in their outer walls positioned below said gas outlet openings Within the liquid as maintained by said liquid supplying and maintaining means.

3 An electrolytic cell as set forth in claim 2 wherein the frames having liquid inlet openings from the source of electrolyte supply are arranged in alternation with the frames having liquid outlet openings, and an interchange References Cited in the file of this patent UNITED STATES PATENTS 1,239,530 Shriver Sept. 11, 1917 2,522,661 Bowen Sept. 19, 1950 2,717,872 Zdansky Sept. 13, 1955

Claims (1)

1. AN ELECTRROLYTIC CELL UNIT COMPRISING A PLURALITY OF CELLS FORMED BY A SERIES OF SQUARE PLATES ARRANGED PARALLEL VERTICAL PLANES WITH THEIR OPPOSITE DIAGONAL CORNERS IN ALINEMENT HORIZONTALLY AND VERTICALLY, SQUARE FRAMES SECURED ONE ON EACH FACE OF EACH PLATE AROUND THE MARGIN THEREOF, SAID FRAMES BEING FORMED OF HOLLOW TUBING SQUARE IN CROSS-SECTION AND MADE OF THE SAME METAL AS THE ADJACENT PLATES TO WHICH THEY ARE SECURED WITH LIQUID AND GAS TIGHT JOINTS, ONE SIDE OF EACH PLATE AND THE ADJACENT FACE OFF THE FRAME SECURED THERETO BEING COATED WITH A PROTECTIVE METAL FACING AND THE SUCCESSIVE PLATES BEING ARRANGED WITH THE COATED SIDE OF ONE PLATE FACING THE UNCOATED SIDE OF THE NEXT PLATE IN SAID UNIT TO FORM A SINGLE CELL THEREOF, GAS-TIGHT LIQUID PERMEABLE DIAPHRAGMS OF APPROXIMATELY THE SAME SIZE AS THE PLATES HAVING LIQUID AND GAS TIGHT INSULATING MARGINS SQUEEZED BETWEEN THE FRAMES OF SUCCESSIVE PLATES IN EACH UNIT, SAID DIAPHRAGMS DIVIDING THE SUCCESSIVE CELL SPACES EACH INTO TWO CHAMBERS, MEANS FOR CLAMPING THE PLATES, FRAMES AND DIAPHRAGMS TOGETHER AND FOR SUPPORTING THE UNIT THUS FORMED WITH THE SEVERAL CELLS ELECTRICALLY INSULATED FROM EACH OTHER, SAID FRAMES HAVING GAS OUTLET OPENINGS IN THEIR INNER WALLS AT THEIR UPPER CORNERS INTO SAID CHAMBERS, TWO GAS COLLECTORS AND INDIVIDUAL DUCTS FOR CONNECTING ONE TO THE UPPER CORNER OF EVERY ALTERNATE FRAME AND THE OTHER TO THE UPPER CORNER OF EACH INTERVENING FRAME IN SAID UNIT, AND MEANS FOR SUPPLYING SAID MAINTAINING A LIQUID ELECTROLYTE IN SAID CHAMBERS AT A LEVEL BELOW SAID GAS OUTLET OPENINGS.

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