US2447547A

US2447547A - Electrolytic alkali chlorine cell

Info

Publication number: US2447547A
Application number: US597259A
Authority: US
Inventors: Kenneth E Stuart
Original assignee: Hooker Electrochemical Co
Current assignee: Occidental Chemical Corp
Priority date: 1945-06-02
Filing date: 1945-06-02
Publication date: 1948-08-24
Anticipated expiration: 1965-08-24

Description

Aug. 24, 1948. STUART 2,447,547

ELECTROLYTIC ALKALI CHLORINE CELLS Filed June 2, 1 945 5 Sheets-Sheet 1 IN VEN TOR K. E. STUART ELECTROLYTIC ALKALI CHLORINE 'GELLS Aug. 24, 1948.

,5 Sheets-Sheet 2 Filed June 2, 1945 IN VEN TOR Aug. 24, 1948. I K. E. STUART 2,447,547

ELECTROLYTIC ALKALI CHLORINE CELLS 5 Sheets-Sheet 3 Filed June 2, 1945 IN VENT OH Aug. 24, 19 48. K. E. STUART ELECTROLYTIC ALKALI -CHLIORINE CELLS Filed June 2, 1945 5 Sheets-Sheet 4 Aug. 24, 1948. STUART 2,447,547

ELECTROLYTIC ALKALI CHLORINE CELLS Filed June 2, 1945 5 Sheets-Sheet 5 INVENTOR.

Patented Aug. 24, 1948 ELECTROLYTICi ALKALI CHLORINE CELL Kenneth E. Stuart, Niagara Falls, N. Y., assignor to Hooker Electrochemical Company, Niagara Falls, N. Y., a corporation of New York Application June 2, 1945, Serial No. 597,259

5 Claims. 1

This application is a continuation-in-part of application Serial No. 444,771, filed May 28, 1942, now abandoned.

My invention relates more particularly to an improvement upon the cell described in Patent No. 1,866,065, granted to me July 5, 1932. One object of my invention is to increase the electrode surface of the cell per unit of floor space occupied, Another object of my invention is to simplify the construction of the cathode assembly. Another object of my invention is to provide improved means for forming a liquid-tight joint between the liquid-retaining enclosing wall of the cathode assembly and the liquid-retaining bottom closure member of the cell. Another object of my invention is to protect the bottom closure member against electrolysis which would otherwise be liable to result from accidental minor leaks through said joint, when the bottom closure member is of metal. Still another object of my invention is to provide an improved means for forming a liquid-tight joint between the liquid-retaining enclosing wall of the cathode assembly and the non-conducting cover member of the cell. A further object of my invention is to eliminate certain imperforate cathodic metal surfaces which are liable to become exposed to electrolytic action within the cell and thus cause formation of chlorates, withloss of current efiiciency.

Referring to the drawings:

Fig. 1 is a plan view of the cell, with the gas collecting cover member removed, and partly in section along line a-a of Fig. 3, showing the cathodic and anodic electrodes, and their spacing. with respect to each other.

Fig, 2 is an end elevation of the cell, in section along line bb of Fig. 1.

Fig. 3 is a side elevation of the cell, partly in section along line -0 of Fig. 1.

Fig. 4 is an elevation of a portion of the cell, in section along line 12-19 of Fig. l, but to an enlarged scale.

Fig. 5 is a sectional elevation through one of the cathodic electrodes, to the scale of Fig. 4.

Fig. 6 is an elevation of a portion of the cell, corresponding to Fig. 4, but showing the bottom closure member as constructed of non-conducting material, such as concrete.

Referring to Figures 1, 2 and 3, I is the anode assembly, including a bottom closure plate 2, which in this case is rectangular in plan and constructed of metal, and preferably of steel, and adapted to carry the cell current. Plate 2 is stifiened by

ribs

3, 3 which rest upon non-conducting members 4, ll, and supports the anodic electrodes, comprising rows of upright, elongated, chlorine-

resistant anodes

5, 5. Anodes 5 are of graphite in the form of flat-sided blades, and have their lower ends conductively aiiixed to plate 2, preferably by embedding these ends in a slab B, of low melting metal, such as lead, which is anchored to plate 2. The ends of the anodes are embedded in slab 5 by supporting the anodes above the plate, preferably with a slight clearance between, and pouring molten lead around the ends of the anodes. Lead slab 5 may be anchored to plate 2 by solder, or by means of fins l, or both. Fins l are preferably welded to plate 2 and extend between the rows of anodes. Holes 8 B are drilled through the ends of anodic electrodes. 5, below the level to which the lead is to be poured,

Holes

9, 9 are similarly drilled through fins l. The molten lead flowing through holes 8 and 9

anchor anodi electrodes

5, 5 to plate '2 firmly and conductively. This method of aflixing the anodic electrodes to the metal closing plate is disclosed and claimed in co-pending application Serial No. 389,033, filed April 17', 1941, now Patent No. 2,370,087.

Plate 2 is provided with a rim l0, which may serve as a retaining wall for the molten lead when it is poured in for the purpose of anchoring the anodic electrodes. Rim I0 is preferably of angle section, one leg being welded to plate 2, perpendicularly with respect thereto, and the other leg forming flange ll, upon which cathode assembly [2 is supported.

Cathode assembly I2 comprises a foraminous structure enclosed in upright liquid-retaining wall i3. Wall l3 is constructed of metal plate and its upper and lower rims lie in normally horizontal boundary planes. In horizontal or plan view wall 13. conforms in shape with flange I'i, so that it is adapted to rest thereon and form a liquid-tight closure therewith. The foraminou's structure comprises a series of thin hollow, upright, flat-sided, elongated, parallel, horizontally aligned cathodic electrodes I4, arranged in two banks, projecting inwardly from opposite sides of wall l3, and alternating with anodic electrodes 5, as clearly illustrated in Fig. l. Cathodic electrodes I l are supported and reinforced by structure to be described in detail later. A crosssection of one of the cathodic electrodes is illustrated in Fig. 5, in which 43 is the wall, of wovenwire screen, which constitutes the active electrode surface, and 3d a corrugated inner plate. Wire screen 48 is covered by permeable, chlorine resistant diaphragm 15. This diaphragm is pref- Unlike the cell of Patent No. 1,866,065, above referred to, the enclosing frame of which is of channel section, enclosing walls l3 are flangeless. This is an important feature of the present invention, as the space between the flanges of the earlier cell, which in that construction is outside the cell, may by omission of the flanges be made available for housing of electrodes, without any increase in floor space occupied. In the cell of the patent, the anode assembly includes a bottom member of concrete, and the joint between flange of the cathode enclosing frame and concrete bottom member is rendered liquid-tight by means of rope type gasket of circular crosssection, in accordance with Patent No. 2,208,778, granted to me July 23, 1940. This in theory gives line contact between the flange and gasket, which however, under the weight of the superposed structure, becomes surface contact, the surface being about one quarter of an inch wide. In the present invention I obtain substantially the same effect by cementing gasket ll, of resilient, nonconducting sheet material, upon the surface of flange -l l. The edge of enclosing wall i3 is then caused to rest directly upon gasket 11, and since the thickness of this wall is about one quarter of an inch, the intensity of pressure is the same as before, and the joint equally effective.

The metal parts of the cathodic assembly, if ofiron, are unaffected by electrolysis, but the metalof bottom plate 2 and rimlfl are anodic. There is no knownmetal but platinum that will withstandL wet nascent chlorine, and electrolyte leaking past gasket I! would, if allowed to flow down over rim [0, cut th metal away almost as if the the electrolyte were a strong acid. As no gasket joint is at all times absolutely perfect, it is very important to guard against contact between flange H and any electrolyte that may accidentally lea-k past gasket H. For this .pur-

pose, I extend gasket I! outwardly a short distance beyond the edge of flange II. The overhanging part of gasket i1 is then caused to sag and forms a natural drip rim, causing any leaking' electrolyte to drip directly to the floor instead of flowing downward over the surface of flange H and rim l0.

It is of course also necessary to protect lead slab 6 and the inner surface of rim l0 against electrolysis. This is accomplished by carrying rim l0 above the level of the lead slab and filling in all the space enclosed by rim in above the lead and between anodic electrodes 5 with a layer of impervious, non-conducting, chlorine-resistant material, such as bitumemas indicated at 18. Layer [8 is applied in a fluid condition, either while molten or in a solvent. The fluid bitumen may be poured in until it fills the space within rim [0 level full. Gasket ll preferably extends beyond flange ll inwardly as well as outwardly. The inwardly overhanging part of gasket I! may then be pressed downward into the fluid bitumen until the latter flows over its upper surface. The edge of the gasket is thus embedded in the bitumen and an excellent seal secured. Gasket l1 may be of rubber or of any good, resilient, nonconducting rubber substitute. If the solvent for the bitumen is also a solvent or softening agent for the material of the gasket, a perfect bond is secured. If desired, the bitumen may be poured in While in a molten condition to a level just below gasket I1, and another layer of bitumen in a solvent may then be poured in, making a bond with both the first layer of bitumen and the gasket. If the gasket is of a material incapable of withstanding the temperature of molten bitumen, it is thus protected against inury.

The joint between enclosing wall 13 and cover It; may be made in a similar manner by cementing gasket ill to the under surface of the rim of cover I6.

It should be noted that, although flange ll projects beyond walls I 3, it projects much less far than the flange of a standard channel of a height equal to that of enclosing wall l3. Hence the floor space occupied by the cell is more effectively utilized when the enclosing wall of the cathode assembly is flangeless, as in my present cell.

By reference to Figs. 1 and 2, it will be seen that the use of a steel bottom plate 2 lends itself to a very simple bus bar connection to the anode assembly, consisting of four fiat bus bars 20, extending longitudinally of the cell in a direction generally parallel to the rows of anodic electrodes, and bolted and soldered to the outer surface of plate 2, opposite the ends of these electrodes. Bus bars 20 preferably extend from end to end of the cell. At one end they are overlapped by bus bars 2|, which are bolted and soldered to bus bars 20, curve upward beyond the cell preferably in a sweep of large radius and are bolted to plate 22, upon the vertical face of the cathode enclosing wall I3 of the next cell of the series, by means of bolts 23. Bus bars 2! should be of soft annealed copper or laminated, for flexibility. Bus bars 24 carry the current around the side walls l3 and are riveted and soldered thereto. Lugs 25 are affixed to the bottom of plate 2, by bolts 26, Lug 25 serve for connection of jumper switches (not shown), by means of which any particular cell of the series may be short-circuited when necessary for diaphragm or anode renewal. This type of bus bar connection between cells is very economical of floor space.

By reference to Fig. 1, it will also be seen that, while, as before, the electrodes are divided into two banks with a clearance between. which is a important for circulation of electrolyte, the corresponding electrodes are opposite each other, instead of being staggered, as in the original cell. While the staggered arrangement is advantageous under most circumstances, when economy of floor space is a prime consideration it may be dispensed with. In this way longitudinal space equal to half the distance between corresponding electrodes is gained.

By the use of the type of bus bar connection between cells just described and the saving in flange space and that due to dispensing with the staggered arrangement of the two banks of electrodes, I am able to gain sufficient space to increase the number of electrodesin each bank from fifteen to eighteen, or one fifth, upon the same center to center distance between cells.

Similarly, by the saving in flange space at each side of the cell I am able to increase the total Width of the graphite anode blades by one sixth. It should also be noted that by dispensing with the outward flanges. ofenclosing wall la, the cell design is freed from the limitations of standard channel sections. This makesit possible to utilize one sixth more of the height of the standard, graphite anode blades.

The combined eiTect of th increa e in. number, width and height of electrodes is anincrease eij more than sixty per cent in total electrode surface, without any increase in f oor space 0. cupie'd; a very important result, especially when it is realized that this is by comparison with a cell which is itself extremely economical of floorspace,

When the walls of the enclosing frame areof flangeless plate, as inthe present case, it may. be desirable to provide means for stiffenin -these,

walls. This object is accomplished by means of membersv 27. These extend horizontally around walls iii. In order that members 21' may have amaxirnum sectional moment of inertia, they are, preferably of angle section, With the edge of one leg welded to the adjacent wall I 3 and the other leg inside and parallel to this Wall. The space within the legs of the upper angl 21 is thus left open, to form passage 28 for flow of hydrogen to exit 29 similarly, the space within the l gs of lower angle 2'! formspassage 30 for flow of the liquid product of electrolysis to effiuent pipe 3|, whence it falls by gravity into, funnel 32 to be carried away by header pip 33. Members E lare provided, for reinforcing cathodic electrodes i4 against collapsingpressure.

Effluent pipe 31 is, connected to passage 30 through a threaded opening at and swings upon the thread. From this opening it projects outwardly, then bends upwardly to vertical leg 3,6. At the top of leg 33 it bends horizontally and describes an arc about opening 35, finally ending in spout 31, which is adapted to deliver into funnel: 32. The liquid product of electrolysis w fills passage 3fiinside wall; it to a level just short of passage 28 and must not be allowed to encroach upon passage 28. for otherwise the hydrogen exit would be obstructed. The radius of the arc described by effluent pipe 3i about opening 35 is therefore made such that in any position of the pipe passage 28 cannot be obstructed,

Lugs 38 are provided for lifting the cathode assembly as for diaphragm renewal.

Brine is supplied to the cell preferably at a constant rate through flow controlling restriction 39, in accordance with U. S. Patent No. 2,183,- 299,,granted to me Dec. 12, 1939. The brine is supplied preferably at a temperature of to 90 C; and saturated at that temperature in accordance with the process of U. S. PatentNo. 2,173,986, granted to me Sept, 26, 1939. Chlorine is discharged from cover I 6 through pipe Ml. The electrolyte level within the cell is shown by the liquid column in manometer 4|, with reference to the lower end of vertical pipe 49, to the upper end of which the manometer is connected, the manometer reading corresponding to the pressure built up in pipe 49 by chlorine evolved upon anodes 5 and trapped in th pipe under the hydrostatic head corresponding to the depth ofsubmergence of the open lower end of the pipe.

An important advantage of the fiangeless construction of walls is about which nothing has heretofore been said is as follows: when the walls are of flanged channel section, the foraminous border of the cathodic electrode structure is Welded to the edges formed by the fiat surfaces of the flanges with the web of the channel. Since the gasket could not make a liquid-tight joint with. the; ioraminous border, and: since, there. is: some variation in the forming of the channel frame, the gasket is n cessarily caused to, bear upon the surface of the flange at a. short distance from the edge, wheretheioraminous border, and hence the diaphragm, begins. Between the. edge and the bearing area there therefore exists. a.- narrow strip of surface extending around the. cell which is imperforate and not covered by the; diaphragm. It is necessary to protect. this sure lace against electrolysis by the use of putty, as. caustic soda would, otherwise, be formed upon it. anclthis would come into contact with chlorine and be converted to sodium chlorate, an undesired; current wasting icy-product. But putty is not a, reliable protection for this surface. It sometimes fails, and when this occurs there results a COD: tamination of the product and loss. of current; eiiiciency in the cell. By the use of the flangeless. construction of the present invention, however, the foraminous cathode border is carried to the edge of wall i3 where this edge rests upon. the. gasket, and no marginal surfaces are left to=becovered by putty where chlorate might. otherwise be formed and, current wasted.

While I have described the, novel cathode struc.. ture of my cell in connection with a novel type of metal bottom closure, I do not wish'to be limited to this combination, as my cathode may be used inzcornbination with the concrete bottom closure member of Patent No. 1,866,065; This is, illustrated in Fig. 6, in which the cathode: is that; described above, and'the reference figures likewise the same, insofar as they apply to the cathode. In this case, however, the bottomv clo,-' sure member 43 is adapted to be constructedof: concrete or other non-conducting, material. 45, is a slab of low melting metal, corresponding, to slab 5 and M a layer of bituminous materialcorresponding to layer it. Bottom closuremember 43 being massive, its rim requires no flange, since it is itself broad enough to provide a gasket seat; The same is true of the rim of cover Iii. Gaskets; M, which are of the flat sheet type, are therefore; cemented directly to the rims of the top and: bottomclosure members. Since concreteis non.- conducting, gaskets t? do not need to project outwardly of the bottom closure rim to form" a. drip rim. Current is supplied to slab 5.5 through bus bar 46, embedded therein.

When my improved cathode is used in combinae tionwith a, concrete bottom closure there is still" a substantial increase in electrode area per unit, of floor space, and the other advantages enumerated above are the same as when it is used in combination with a metal bottom closure.

I claim as my invention:

1. In an electrolytic alkali chlorine cell'comprising a cathode assembly including a foraminous metal structure and cathodic electrodes housed in an upright, liquid-retaining metal wall; an anode assembly co-opera-tive therewith, including upright anodic electrodes having their lower ends embedded.- in a slab of low melting;

said bottom closure upturned border and making a sealing bond therewith: the improvement which consists in that said retaining wall is of thin plate; that the lower edge of said retaining wall platelies in a, flat boundary plane; that the lower border of the foraminous structure is continuous and conductivel joined to the inner face of the retaining wall plate, flush with the lower edge thereof, leaving said edge exposed to form a gasket bearing surface of a width limited by the thickness of said retaining wall plate; that the flat face of the bottom closure upturned border conforms with the lower rim of the retaining wall in plan view and extends inwardly and outwardly thereof; and that said face is provided with a flat gasket of impervious, resilient material, the lower edge of said retaining wall plate resting upon said gasket and making a norm-ally liquid-tight closure therewith under the weight of the superstructure.

2. In an electrolytic alkali chlorine cell as described in claim 1, the further improvement which consists in that the upper edge of said retaining wall plate likewise lies in a flat boundary plane; that the upper border of the foraminous structure is likewise continuous and conductively joined to the inner face of the retaining wall plate, flush with the upper edge thereof, leaving said edge exposed to form a. gasket bearing surface of a width limited by the thickness of said retaining wall plate; that said top closure member is provided beneath with a flat normally horizontal gasket bearing surface conforming in plan view with the upper rim of said retaining wall and extending inwardly and outwardly thereof; and that said top closure gasket bearing surface is provided with a fiat gasket of impervious, resilient material, afiixed thereto and resting upon the upper edge of said retaining wall plate.

3. In an electrolytic alkali chlorine cell as described in claim 1, the further improvement which consists in that theupper edge of said retaining wall likewise lies in a flat boundary plane; that the upper border of the foraminous structure is likewise continuous; that the borders of the foraminous structure are spread vertically; that the upper border of the foraminous structure is likewise conductively joined to the inner surface of the retaining wa11 plate, flush with the upper edge thereof, leaving said edge exposed to form a gasket bearing surface of a width limited by the thickness of said retaining wall plate; that said top closure member is provided beneath with a flat normally horizontal gasket bearing surface conforming in plan view with the upper rim of said retaining wall and extending inwardly and outwardly thereof; and that said top closure gasket bearing surface is provided with a fiat gasket of impervious, resilient material aflixed thereto, resting upon the upper edge of said retaining wall plate.

4. In an electrolytic alkali chlorine cell comprising a cathode assembly including a'foraminous metal structure and. cathodic electrodes housed in an upright liquid retaining metal wall; an anode assembly co-operative therewith including upright anodic electrodes having their lower ends embedded in a slab of low melting metal; a top closure member for said retaining wall, and a bottom closure member for said retaining wall and support for said cathode and anode assemblies comprising a flat metal plate beneath said retaining wall extending completely across from side to side thereof and having its upper surface aifixed to said slab, said bottom plate being also provided with an upturned border and s'aidupturned border being provided with an outwardly extending fiat flange around its upper rim; the improvement which consists in that said retaining wall is of thin plate; that the lower edge of said retaining wall plate lies in a fiat boundary plane; that the lower border of the foraminous structure is continuous and conductively joined to the inner surface of the retaining wall plate, flush with the lower edge thereof, leaving said edge exposed to form a gasket bearing surface of a width limited by the thickness of said retaining wall plate; that the flange of the bottom closure member conforms with the lower rim of the retaining wall in plan View and extends inwardly and outwardly thereof; that the flange is provided with a flat gasket of impervious, resilient, electrically non-conducting material; and that the edge of the retaining wall plate resting upon said gasket makes a normally liquid-tight closure therewith under the weight of the superstructure; said slab, bottom plate and upturned border being protected against anodic electrolysis by a layer of impervious, electrically non-conducting pressure plastic material extending around and between the lower ends of said anodic electrodes to said gasket and making a sealing bond therewith.

' 5. In an electrolytic alkali chlorine cell as described in claim 4, the improvement as claimed therein, in which said gasket extends inwardly of said flange and is embedded in said layer.

' KENNETH E. STUART.

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

UNITED STATES PATENTS Number Name Date 180,104 Balmore July 25, 1876 310,744 Swain Jan. 13, 1885 1,378,829 Riiber May 17, 1921 1,665,208 Huff Apr. 10, 1923 1,793,711 Mitscherling Feb. 24, 1931 1,865,152 Stuart June 28, 1932 1,866,065 Stuart July 5, 1932 1,924,827 Anderson Aug. 29, 1933 2,208,778 Stuart July 23, 1940 2,368,861 Means Feb. 6, 1945 2,370,086 Stuart Feb. 20, 1945 2,370,087 Stuart Feb. 20, 1945 2,392,868 Stuart Jan. 15, 1946 FOREIGN PATENTS Number Name Date 11,620 Great Britain 1891 5,645 Sweden July 4, 1894