US2727788A - Electrolytic cell cleaning apparatus - Google Patents

Description

Dec. 20, 19.55

J. c. BAKER 2,72 7,788

ELECTROLYTIC CELL CLEANING APPARATUS Filed July 3, 1951 FIG. 2

INVENTOR. JOSE C. BAKER United States Patent ELECTROLYTIC CELL CLEANING APPARATUS Jose Charlton Baker, Pasadena, Tex assignor to Diamond Alkali (Iompany, Cleveland, Ohio, a corporation of Delaware Application July 3, 1951, Serial No. 235,059

2 Claims. (Cl. 299-141) This invention relates to electrolytic cells particularly for the electrolysis of sodium chloride brine to obtain chlorine and caustic soda therefrom and has a special relation to such cells of the diaphragm-cathode type, though, as will be clear to those skilled in the art, is has application in other similar apparatus. It more particularly relates to the maintenance and rebuilding of cathodes of such electrolytic cells. An especially useful application of the invention is in application to diaphragm-type electrolytic cells of the general type of those illustrated in K. E. Stuart Patent No. 1,866,065.

Cells of the type of the Stuart patent mentioned above are characterized by having alternate anodes and cathodes mounted as closely as possible within a minimum cell area. Economy of space and avoidance of great solution distances for electrolysis are both considerations in close arrangement of anodes and cathodes. The anodes of such cells are customarily of solid carbon and, as in the cell referred to in the aforesaid patent, may be mounted in the base of the cell upon which a liquid-tight, cathode-supporting frame is mounted.

The cathodes of such a cell, on the other hand, comprise foraminous screens over which are laid materials providing a filter surface which permits the passage of ions therethrough but inhibits the passage of liquid from the anolyte to the catholyte chamber. A common method of forming such cathodes is to spread asbestos paper sheet over the entire cathode surface. Another common and extremely commercially successful method is to deposit such asbestos diaphragm upon the foraminous cathode screens. This depositing technique is also the development of K. E. Stuart, as is described in his Patent Nos. 1,855,497, 1,862,244, and 1,865,152. Upon completion of the depositing technique, a screen of asbestos fibers is deposited upon the foraminous cathode screen over the entire surface thereof, and the cathode frame is then ready to be assembled with the anodes already mounted in the base of the cell to complete the entire electrolytic cell.

Such an electrolytic cell for treating saturated brine to obtain therefrom chlorine and caustic soda may last in use for a period from a few weeks to many, many months. At the conclusion of that time, either due to erosion of anodes or much more likely due to packing of the filter media whereby the desired flow through the cathode is impeded, some rebuilding and repairing will be necessary in order to restore the cell to its original efliciency. It has been found, of course, that it is not desirable to discard the entire cathode screen merely because the asbestos portion thereof has become too tightly matted to permit passage of the desired liquids therethrough at an efiicient rate. 0n the other hand, the asbestos itself apparently is not susceptible to any reasonable treatment for renewal thereof but, on the contrary, must he completely removed from the metallic screen cathode and either the cathode rewrapped with asbestos paper or the deposition procedure, as described in the aforesaid Stuart patents, carried out again on a clean screen.

It has been found, and the problem is a serious one where a large number of cells is being operated in a single operation, that the removal of asbestos paper which has been wrapped upon such foraminous screening or the removal of asbestos deposited upon such surfaces many months before represents a very substantial technical problem, especially after the cell has been on the line for a period of many months. When one considers that new anodes are seldom over 1% inches thick, that the space between cell elements is kept as low as possible, say /2 inch, but that such cell elements may be several feet long and a foot or so high, it will be appreciated that the problem of mechanically attaching each individual cathode screen over its entire area to remove therefrom all old asbestos (since any old asbestos left on the structure contributes to initial and continued inefiiciency in the newly rebuilt cell) is a substantial one. Heretofore, the only known means for removing such asbestos from the forraminous cathode screens was to scrape the same therefrom by hand or with the assistance of water injected between the cathodes themselves, which gave some assistance in the removal problem. In any case, however, the removal problem was one of very heavy labor costs, Whereby the cell rebuilding job was made considerably more expensive than it should have been merely for the purpose of renewing the diaphragm on the cathode screens.

The present invention contemplates a device for removing asbestos, either sheet or deposited, from such screen material of cathodes of electrolytic cells, which device may be used for general filter cleaning purposes in similar circumstances as that encountered in cells of the type described in Patent No. 1,866,065. In addition, the present invention is directed to a method of removing old asbestos from used cathode structures, which method results in substantial labor savings over previous methods practiced in the art and, therefore, results in putting the cells back on the line, producing chlorine and caustic soda or other materials, as the case may be, much sooner than has been the case in the past.

It is an object of the present invention to provide a device for the removal of old filter material from foraminous screens and other filter support structures.

It is a further object of the invention to provide a device particularly adapted for the removal of diaphragms from cathode structures of cells, especially those cells adapted for the production of chlorine and caustic soda, and particularly cells wherein alternate cathodes and anodes are set up in relatively close association, as in Patent No. 1,866,065.

A. further object of the invention is to provide an improved method for use in the rebuilding of electrolytic cells for the production of chlorine and caustic soda, which method represents very substantial savings over and above the methods practiced in the prior art for rebuilding such cells.

Other and further objects of the present invention will become apparent as the description of a preferred embodiment thereof proceeds. Such preferred embodiment is described in the following portion of the specification and includes the drawing in which Fig. 1 is an elevation of a structure embodying the present invention, and

Pig. 2 is an end section of the structure of Fig. 1 taken on the line 22 of Fig. 1 but showing the structure in position between a pair of cathodes to be treated.

Referring to the drawings, Fig. 1 shows the device including handle 12, which may suitably have threads 14 for attachment of a source of water (not shown) at high pressure. Depending upon the size of the electrolytic cell involved, handle 12 may be of considerable length, such as, as much as 36 or 48 inches. Handle 12 has extension 16 which is suitably provided with narrow slots 18 and otherwise is water-tight. As may be seen particul'arlyfrom Fig.2, slot 18 permits the ejection of water therethrough directly against the sides of the cathodes 20 from which'it is desired to remove the old cathode diaphragm material. I A particular advantage of the present structure is to benoted in the relatively rectangular shape of the actual spray portion of the device shown as extension 16 and particularly clearly illustrated in Fig. 2. Thus, water coming out of slot 18 at high pressure impinges directly against the asbestos layer 22 on the forarninous screen 24 and, in washing away the asbestos, has but relatively constricted space between the walls of the cathode and the walls of the extension 16, whereby relatively high pressure is maintained at that point to force the asbestos or other filter material away from the screen 24.

Itwill be appreciated that with this device, it is necessary only to insert the same between a pair of cathodes in order to remove therefrom all of the old asbestos material or other filter material deposited thereupon, whereby no hand work in cleaning the foraminous screens or other filter surfaces is necessary. Moreover, in one form of the invention, wherein the diagonal of the extension 16 is longer than the distance between two screens 24, it is a preferred step in practicing the method of the invention to turn the extension 16 until its corners contact the screen, whereby the high pressure water from slots 18 hits the cathodes tangentially and thus the removal of asbestos 22 is facilitated.

It has been found in actual practice that this apparatus and method provide a very substantial saving in rebuilding of cells, so that at the present time, employing the device of the present invention and the method hereof, a multiple cathode structure which heretofore required many hours to clean by hand, can quite simply, with high pressure water and the present invention, be completely cleaned in a matter of a few minutes.

While there have been described various embodiments of the invention, the apparatus described is not intended to be understood as limiting the scope of the invention as it is realized that changes therewithin are possible and it is further intended that each element recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner, it being intended to cover the invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. A device for removing used diaphragms from foraminous cathodes of electrolytic cells, including a handle, a closed-end, tubular member of substantially rectangular cross-section secured to and extending from said handle, said tubular member having narrow slots in oppositely disposed walls thereof, said rectangular cross-section having a diagonal greater than the distance between said foraminous cathodes, said slots extending longitudinally substantially parallel to the longitudinal axis of said tubular member, and means connected to said tubular member for introducing fluid under pressure thereinto.

2. A cleaning device for removing filter material simultaneously from two spaced planar foraminous surfaces, said device comprising a handle, a hollow, substantially rectangular member secured to said handle at one end and closed at the other, said hollow member having oppositely disposed substantially planar sides, only two of said sides each having a slot therethrough extending linearly in a direction substantially parallel to the longitudinal axis of said handle, said sides defining a construction small enough to pass freely between said foraminous surfaces while the distance between opposite corners of said cross-section is greater than the distance between said foraminous surfaces, thereby to permit oscillatory movement of said hollow member about the longitudinal axis of said handle between two foraminous surfaces to facilitate cleaning thereof, but not rotary motion about said longitudinal axis between said foraminous surfaces, and means for introducing fluid under pressure into said hollow member.

References Cited in the file of this patent UNITED STATES PATENTS 1,186,226 Parker June 6, 1916 1,521,390 Reynolds Dec. 30, 1924 1,635,115 Deutsch July 5, 1927 1,644,226 Bedard Oct. 4, 1927 1,743,953 Beatty Jan. 14, 1930 1,768,314 Folta June 24, 1930 1,783,237 Greer Dec. 2, 1930 1,923,828 Janota Aug. 22, 1933 2,064,072 McArdle Dec. 15, 1936 2,081,168 Mering May 25, 1937 2,345,808 Green Apr. 4, 1944 2,581,781 Ahlfors Jan. 8, 1952 FOREIGN PATENTS 28,415 Austria May 10, 1907

Claims (1)

1. A DEVICE FOR REMOVING USED DIAPHRAGMS FROM FORAMINOUS CATHODES OF ELECTROLYTIC CELLS, INCLUDING A HANDLE A CLOSED-END, TUBULAR MEMBER OF SUBSTANTIALLY RECTANGULAR CROSS-SECTION SECURED TO AND EXTENDING FROM SAID HANDLE, SAID TUBULAR MEMBER HAVING NARROW SLOTS IN OPPOSITELY DISPOSED WALLS THEREOF, SAID RECTANGULAR CROSS-SECTION HAVING A DIAGONAL GREATER THAN THE DISTANCE BETWEEN SAID FORAMINOUS CATHODES, SAID SLOTS EXTENDING LONGITUDINALLY SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF SAID TUBULAR MEMBER, AND MEANS CONNECTED TO SAID TUBULAR MEMBER FOR INTRODUCING FLUID UNDER PRESSURE THEREINTO.

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