US3113918A

US3113918A - Electrolytic apparatus

Info

Publication number: US3113918A
Application number: US68019A
Authority: US
Inventors: Evans David Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-06-03
Filing date: 1960-11-08
Publication date: 1963-12-10
Anticipated expiration: 1980-12-10

Description

Dec. 10, 1963 1:..1. EVANS 3,113,918

ELECTROLYTIC APPARATUS Filed Nov. 8. 1960 3 Sheets-Sheet 1 WVE/YTOE 0A wd Evans wwhm ArmeA/Exr Dec. 10, 1963 D. J. EVANS 3,113,918

ELECTROLYTIC APPARATUS Filed Nov. 8. 1960 3 Sheets-Sheet 2 @W Mhmm Dec. 10, 1963 D. J. EVANS 3,113,918

ELECTROLYTIC APPARATUS Fiied Nov. 8. 1960 s Shgets-Sheet s M/viwoz Dav/Id Eva/1s (EMA/NM 3,113,918 ELECTRQLYTTQ APPARATUS David Johnson Evans, 215422 High Holhorn, London, England Filed Nov. 8, 1.969, ger. No. 68,019 9 Claims. (Cl. 264-268) This invention relates to electrolytic apparatus including relatively small-scale apparatus for production of chlorine or hypochlorite for sterilising purposes and largescale apparatus such as electrolysers for production of chlorine or hypochlorite directly in large volumes of sea-Water, for example condenser cooling water.

The electrodes usually employed in such apparatus are made of graphite which is liable to erosion in normal use, eventually resulting in irregular action and even destruction of the electrodes.

It is known that platinum is far more resistant to chemical action than graphite, and that titanium is very resistant to such action. By coating thin sheets of titanium with platinum, it is therefore possible to produce composite metallic electrodes of substantial thickness, sutiiciently rigid for practical purposes, without the high cost of platinum electrodes.

The present invention has for its main object to provide improved electrolytic apparatus employing electrodes consisting of th n sheets of titanium coated with platinum, and having far higher efiiciency than apparatus emplo ing graphite electrodes, which would have to be made of much larger size to give equal output.

The invention thus has the further objects of enabling relatively small apparatus to be employed and of facilitating provision for cooling by liquid circulation, which is readily applicable when required.

A specific object of the invention is to ensure rapid discharge of the electrolyte and the electrolytic products by arranging the thin sheets of titanium, coated with platinum on one face, to form a stack with the electrodes inclined at an angle and suitably spaced apart, their platinum-coated faces being uppermost, and with the electrolyte and the electrolytic products from the uppermost faces passing upwards to discharge.

Other objects and advantages of the invention will hereinafter appear from the'following description of two embodiments given with reference to the accompanying drawings, in which:

FIG. 1 is an elevation, partly in section, of a first embodiment having electrodes of flat rectangular shape.

FIG. 2 is a half-section on the line 22 of FIG. 1.

FIG. 3 is a sectional elevation of a second embodiment having eelctrodes of dished shape.

FIG. 4 is a section at right angles to FIG. 3.

In the embodiment shown in FIGS. 1 and 2, the electrodes consist of fiat sheets 19 of rectangular shape, composed of titanium with a coating of platinum, these sheets being mounted between two former plates 11 having parallel and vertical inner faces formed with grooves 12, inclined at an angle of about 45 degrees. The electrodes have their opposite edges fitted into the grooves so as to form a sloping stack with gaps of about 2 mm. between their faces, and preferably having edge-sealing by the use of suitable insulating material. Each of the two end electrodes has a backing disc 13 secured centrally thereto by countersunk-headed screws 14, and is also secured by screws to a bevel-faced block 15 through which there passes alead-in or conductor rod 16 fixed to the backing disc 13.

The assembly of electrodes 19, former plates 11 and bevel-faced blocks 15 is slidably fitted into a tubular housing 17, the areuate outer faces of the former plates 11 being curved to the same radius as the interior of the housing, and the two blocks 15 with their conductor rods United States Patent 0 16 being maintained above the axis of the housing by ledges or millings 18 on the inner faces of the former plates 11, the grooves 12 in the latter stopping short at this same level. The tubular housing 17, which may be made of polyvinyl chloride or like plastic, has two rings 19 surrounding its ends; these rings, which act like jointing flanges, may be either screwed on the exterior of the housing as at Ell or fixed thereto by other means. Between the ends rings 19, the housing is surrounded by a metallic casing 21 made in two semi-cylindrical halves, which are held together by bolted joints at lugs or flanges 22 formed at their longitudinal edges. Circular cover plates 23, also preferably made of plastic material, are secured to the end rings by bolts or the like, a metal clamping plate 24 being arranged on the outside of each cover plate for engagement by the bolts or the like. The metal clamping plate also facilitates the attachment of end connections, such as an inlet 25 for electrolyte at one end of the housing; leading to the space below the electrodes 12, an outlet 26 at the other end of the housing, leading from the space above the electrodes 12, and junction-boxes 27 inside which the conductor rods are connected to the external leads. Brackets 28 or the like may be welded or otherwise secured to the casing 21 outside the housing, or to an outer jacket surrounding the casing, if cooling is required. Internal cooling may also be provided by forming passages in the interior of the electrodes 12, for example by Welding two platinised sheets together at their edges to form an electrode, the coolant flowing through the internal passages.

In another embodiment of the invention, as shown in FIGS. 3 and 4, the titanium electrodes consist of dished or frusto-conical discs 30 slipped upon a central tube 31 and separated from one another by spacing washers 32 of insulating material. The central tube is arranged to be substantially vertical, and the discs 3%, which are platinised on the upper face only, are mounted with their apertured centers above their outer edges, advantage being taken of this position and of the shape of the cathodic surface for the discharge of hydrates when the polarity of the cell is temporarily reversed from time to time, the hydrates then dropping from the outer edges of the cathodic surfaces and falling from the peripheries of the underlying discs. The stack of discs 30 is supported by a sleeve 33 resting upon a base 34, and a second sleeve 35 is fitted on top of the stack, both sleeves being made of a suitable plastic.

The whole assembly is enclosed in a housing 36 of suitable insulating material, to which a top cap 37 and the bottom cap or base 34 are secured, for example by means of clamping plates 38 and bolts 38-.

The shape of the discs 39 lends itself to insulation of the edges by dipping in a suitable plastic. The uppermost electrode 30 may be completely covered with this plastic insulating material on its anodic face, the lead-in conductor rod 39 attached to this electrode being also covered with the insulating material, and its extremity being carried through the cap 37 at the top of the cell by way of a hole 49 which may be provided with a suitable gland. The bottom electrode of the stack may also have its attached conductor rod 41 covered with insulated material and it may extend through a gland in the bottom cap or base 34.

The central tube 31 is preferably arranged for circulation of coolants, being made of silica glass or other hear-resistant material; if cooling is not required, the tube may be of any suitable plastic material, and it may be perforated to serve as the outlet for the hydrogen and electrolytic product, the top sleeve 35 being similarly perforated to register with the tube perforations.

The tube 31 preferably leaves an annular space between it and the edge of the central aperture in each electrode, to allow for the exit of hydrogen and the circulation of the electrolyte, or it may be ribbed externally to leave spaces inside the washers 32 separating the electrodes from one another, so that the hydrogen and elec trolyte may pass out beneath the sleeve 35. The electrolyte then flows out through a pipe 42, which preferably projects below the top cap 37, while the hydrogen collects above the inner end of this pipe and escapes through a separate pipe 43, the inner end of which is flush with the top cap.

In some cases the bottom cap or base 34 may be hollowed out to provide a space of conical shape to receive hydrates when thrown off the electrodes, a suitable vent being positioned near the bottom to allow these deposits to be blown down from time to time. Operation of the valve controlling blow-down may be automatically sequenced with the reversal of polarity. Preferably, however, the inlet 44 for electrolyte projects through the bottom cap or base 34 for a suflicient distance to ensure that the hydrates are trapped without falling back into the inlet, and a drain pipe 45 for removal of the hydrates is provided, the inner end of this pipe being flush with the base 34.

It will be seen that this embodiment allows for variation of the number of electrodes in a very simple way, the tube 36 being readily replaceable by one of a diiferent length, and that the cell may be assembled from standard parts to suit different requirements of voltage and output.

Automatic venting of hydrogen may be arranged for by the use of a normal liquid outlet in the top cap 37, with the central tube 31, on which the electrodes 30 are mounted, extending upwards for a relatively great length; the bottom of this tube will be sealed below the base 34, its upper portion and the sleeve 35 being perforated above the electrodes to allow entrance of the hydrogen, which can thus escape at the top end of the tube 31. This arrangement will be particularly suitable for treating sea-water, which normally needs no cooling, but can be allowed to flow out through the central tube together with the hydrogen and the electrolytic product.

The invention is not limited to the embodiments described by way of examples; thus the second embodiment described may be modified by reversing the relative position of the frusto-conical electrodes.

What I claim is:

1. Electrolytic apparatus comprising a container, said container having opposite end portions, said container defining a closed cavity therewithin, a liquid inlet at one end of said container in communication with said cavity, a liquid outlet at the opposite end of said container in communication with said cavity, said liquid outlet being disposed a substantial distance vertically above said liquid inlet when said container is in its operative position, a stack of electrically conductive bipolar electrodes disposed within said cavity and positioned vertically between said inlet and said outlet, said electrodes being insulated from one another and closely spaced from one another in substantially parallel relationship, all of said electrodes being inclined at a substantial angle to the vertical, each of said electrodes comprising a thin sheet of titanium coated with platinum on only one face thereof, the platinum coated face of each electrode being the upwardly directed face of the inclined electrode, and means for impressing an electrical potential between the electrodes at opposite ends of said stack of electrodes.

2. Apparatus as defined in claim 1, wherein said electrodes are flat sheets, supporting means within said container, said supporting means defining a plurality of parallel grooves, edge portions of the fiat sheet electrodes being mounted in said grooves.

3. Apparatus as defined in claim 2, wherein the supporting means comprises two former plates mounted parallel to one another, said former plates each having a substantially vertical inner face having grooves formed therein and inclined at an angle of substantially 45 to the vertical.

4. Apparatus as defined in claim 3, wherein the former plates have arcuate outer surfaces, the container having a circular internal cross-sectional configuration, the assembly of electrodes and former plates being slidably mounted within said container.

5. Apparatus as defined in claim 4, wherein said container includes two end plates, the liquid inlet being disposed in one of said end plates and the liquid outlet being disposed in the other of said end plates, the means for impressing an electrical potential between the electrodes at opposite ends of the stack of electrodes comprising a pair of blocks of electrically insulating material having flat end faces disposed at an angle of substantially 45 to the vertical and defining apertures therethrough, each of said blocks having an end face, the blocks being so positioned within the container that the end faces of the blocks contact an adjacent electrode of the stack over substantially the whole area of the respective end faces, the end electrodes at opposite ends of the stack of electrodes being mechanically attached to the adjacent blocks, and a rod of electrically conducting material attached to the end face of each of said blocks and passing through the aperture in the associated block and extending to the exterior of said container.

6. Apparatus as defined in claim 1, wherein each of said electrodes is of dished substantially frusto-conical configuration and has a central aperture formed therethrough, support means mounted within said container and comprising a tube engaging the edges of the central apertures in the electrodes and extending therethrough, and spacing Washers disposed between adjacent electrodes.

7. Apparatus as defined in claim 6, wherein said tube is vertically mounted within the container, the container being provided with top and bottom caps, said tube being mounted between said caps, electrical current lead means extending from the outside of the container to the uppermost and lowermost electrodes within the container, the liquid inlet being disposed in the bottom cap and the liquid outlet being disposed in the top cap.

8. Apparatus as defined in claim 7, wherein the substantially frusto-conical electrodes are positioned with the apices of the cones uppermost, the mounting tube and the central apertures in said electrodes being arranged such that spaces are defined between the tube and the edges of said apertures.

9. Apparatus as defined in claim 8, wherein the liquid inlet projects above the bottom cap and into the container at a point within the orthogonal projection of the electrodes onto the bottom cap, the bottom cap being provided with a drain outlet to the exterior whose inner end is flush with the inner surface of the bottom cap.

References Cited in the file of this patent UNITED STATES PATENTS 728,440 Boucher May 19, 1903 1,062,058 Threlfall May 20, 1913 2,636,856 Suggs Apr. 28, 1953 2,955,999 Tirrell Oct. 11, 1960 FOREIGN PATENTS 514,171 Germany Dec. 10, 1930 1,220,408 France Jan. 4, 1960 132,953 Australia May 31, 1949 604,415 Canada Aug. 30, 1960 13,723 Great Britain 'of 1893

Claims

1. ELECTROLYTIC APPARATUS COMPRISING A CONTAINER, SAID CONTAINER HAVING OPPOSITE END PORTIONS, SAID CONTAINER DEFINING A CLOSED CAVITY THEREWITHIN, A LIQUID INLET AT ONE END OF SAID CONTAINER IN COMMUNICATION WITH SAID CAVITY, A LIQUID OUTLET AT THE OPPOSITE END OF SAID CONTAINER IN COMMUNICATION WITH SAID CAVITY, SAID LIQUID OUTLET BEING DISPOSED A SUBSTANTIAL DISTANCE VERTICALLY ABOVE SAID LIQUID INLET WHEN SAID CONTAINER IS IN ITS OPERATIVE POSITION, A STACK OF ELECTRICALLY CONDUCTIVE BIPOLAR ELECTRODES DISPOSED WITHIN SAID CAVITY AND POSITIONED VERTICALLY BETWEEN SAID INLET AND SAID OUTLET, SAID ELECTRODES BEING INSULATED FROM ONE ANOTHER AND CLOSELY SPACED FROM ONE ANOTHER IN SUBSTANTIALLY PARALLEL RELATIONSHIP, ALL OF SAID