US779383A - Electrolytic apparatus. - Google Patents

Description

PATBNTBD JAN. s, 14905.

o. P. TowNsBND. BLBGTROLYTIG APPARATUS."

APPLICATION FILED HAY 10, 1904 WWW v yam.

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UNITED STATES Patented January 3, 1905.

PATENT OFFICE.

ELECTROLYTIC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 779,383, dated January 3, 1905.

Original application filed April 12, 1902, Serial No. 102,582. Divided and this application filed May 10, 1901i. Serial No. 207,227.

To all whom it may concern:

Be it known that I, CLIN'roN PAUL TowN- SEND, a citizen of the United States, residing at Tashington, in the District of Columbia, have invented certain new and useful Improvements in Electrolytic Apparatus, of which the following is a specification.

This apparatus is intended for the electrolysis of solutions, especially aqueous solutions of alkali-metal salts, and is designed for the recovery of a cathode product of electrolysis. The construction is such that a product or products of the electrolysis, whether primary or secondary, is liberated in the presence of a liquid which is substantially immiscible with and inert toward said product or 'products and which serves several important functions hereinafter specified.

As a specific example of the use of the apparatus I will describe the electrolysis of an aqueous solution Vof sodium chlorid to produce caustic soda and chlorin, referring to the accompanying drawing, wherein the figure is a transverse vertical section of one type of cell.

The cell shown comprises a central compartment l, containing an anode or anodes 2 and one or more lateral or cathode compartments 3, shown as two in number, said lateral compartments being separated from the central compartment by cathodes 4 and diaphragms 5. The anodes 2, shown as two in number, may be lplates of Acheson graphite carried by a conductor-bar 2', also of graphite, or they'may be of any other suitable construction and material. The diaphragms 5 are of asbestos or other suitable pervious material, supported between the perforated sheet-metal or wire-gauze cathodes 4 and the plate 6, which have numerous small perforations, except at their upper portions. The plates 6, which may be of hard rubber, earthenware, hardened asbestos, or other suitable non-conducting material, serve to support the diaphragm and may be omitted if the .diaphragm is of self-supporting material. The cathodes are shown as inclined slightly from the vertical; but such inclination is not essential.

7 7 represent plates, preferably of iron, adjacent and approximately parallel to the cathodes. These plates terminate a slight distance above the bottom of the cathode-compartments and below the top for a purpose hereinafter described. The position of the plates 7 is such as to provide a relatively narrow space between said plates and the cathodes and a relatively wide space between said plates and the outer wall of the cathode-compartments.

8 8 are coils suitably connected and employed for heating or cooling the liquid in the cell to maintain the temperature of the electrolyte at any desired point. Considerable economy of current can be eifected by maintaining the electrolyte at a suitable temperature above normal.

As illustrated, the cathode-compartments 3 3 are somewhat deeper than the central or anode compartment l and are provided with valve-regulated drain-pipes 9 9, communicating with the main conduit 10.

In operation the central compartment is filled with sodium-chlorid solution, and a continuous fiow is preferably maintained through this compartment from below upward, the inlet ll and outlet 12 being provided for this purpose. The lateral com partments are filled to or above the top of the plate 7 with a liquid which is substantially immiscible with and inert toward the cathode product, which product in the present instance'is sodium hydrate. It is important that the liquid used in the lateral compartments should be of such character as to separate readily from the caustic and that it should be so inert with respect to the caustic that it will not undergo any rapid injurious change or modification in use. Qf such liquid the non-saponifying oils may be taken as an example. Upon the passage of the current chlorin is liberated at the anode and sodium at the cathode. The chlorin escapes from the cell and may be collected and used as desired. The sodium is set free at the cathode in the presence of the inert immiscible liquid and is in part or entirely oxidized by the solution in the diaphragm or percolating through the diaphragm. The caustic solution so formed under' the oil detaches itself freely from the cathode and is withdrawn from the cell through the pipes. 9. The hydrogen which results fron tle reaction escapes upward through the narrow space between the cathodes and the plates 7 thereby inducing a strong circulation of the oil, which furtherI aids in detaching the globules of caustic solution, thereby removing them quickly from the field of the electrolytic action.

The use of an inert liquid immiscible with the cathode product for the purpose of collecting such product effects many important advantages, as follows:

First. The product is formed and collected under a seal of said immisoible liquid and is thereby protected from all effects due to the contact of atmospheric gases. In the case of caustic soda, for instance, the sealing liquid prevents the production of sodium carbonate. It also prevents the production of carbonates of such metals as calcium and magnesiun, which may be present in an unpurified brine and which Would act to obstruct the diaphragm and gradually to reduce its porosity. It also prevents evaporation of the liquid which carries the product in solution, and consequent deposition therefrom in the diaphragm or on the cathode of the less-soluble constituents.

Second. It effects the positive removal of the product from the electrode, an effect probably due, in part, at least to the difference in the adhesive power of the two liquidsas, for instance, the caustic solution and the mineral oilfifor the material of the electrode. For instance, oil adheres closely to such surfaces, and it follows that the caustic solution being unable to displace the oil assumes at once the form of a globule and freely detaches itself from the surface. Since the amount of diffusion of one liquid into another is dependent upon the time during Which they remain in contact, this rapid removal of the caustic through the agency of the oil is most effective in preventing diffusion 'of the caustic into the liquid in the anode-compartment.

Third. This removal of the caustic from the cathode is further aided by the fact that the hydrogen, which is a product of the reaction between the sodium and the water of the brine and Which is set free concurrentl y with the production of the caustic, is liberated under the hydrostatic pressure of the oil instead of merely expandinginto an atmosphere. The hydrogen is compressed into bubbles, which acquire a positive energy and direction of movement and greatly assist in detaching globules of caustic.

Fourth. The hydrogen moving rapidly upward between the cathode and the plate 7, as before mentioned, imparts a rapid movement of circulation to the-oil, Which causes the oil to effectively and positively strip from the cathode the particles or globules of caustic solution. This rapid and useful movementof circulation is effected automatically and without extraneous assistance by the escaping hydrogen. The immiscibleliquid, therefore, operatingthrough its own adhesion to the cathode surface through the direction which it gives to the bubbles of hydrogen and through its rapid movement of circulation effects a practically instantaneous removal of the caustic from the surface of the cathode and from the field of electrolysis.

Fifth. The removal of the caustic from the cathode being effected in part by the hydrogen bubbles escaping under the oil and in part by the stripping action of the circulating oil thereby induced, as above described, it follows that an increase of current density by which both of these favorable effects are increased will operate advantageously within certain limits. In practice I find that I am enabled to utilize current densities equal to or exceeding one ampere per square inch of cathode area with a high degree of efficiency, thus giving to the apparatus a very large capacity.

Sixth. During the relatively slow downward movement of the oil in the large compartment between the plate 7 and the cell- Wall the caustic carried by the oil is permitted to separate therefroin and is deposited in the lower portion of the cell and in the drainage system, whence it is withdrawn as desired. The caustic is thus automatically deposited as formed outof the circulating-path of the oil and out of the field of electrolytic action and is positively insulated from the electrolytic field.

Seventh. The oil further acts in a marked degree to protect the diaphragm from the products of the electrolysis. I find that a fibrous material of vegetable or animal origin may be employed and that the film of oil which covers or coats the fiber serves to a largeextent to prevent contact therewith of the products of electrolysis, and hence to prevent their corrosive action.V

Eighth. The oil affords a convenient means for regulating the rate of flow of the electrolyte through the diaphragm, and hence the concentration of caustic solutions produced at any particular current density. By raising or lowering the oil-level the amount of percolating liquid may be decreased or increased at Will, and this effect may be supplemented by a variation in the level of the liquid in the anode-compartment. If the rate of flow through the diaphragm be greatly diminished, the caustic is seen to be detached from the cathode in the form of fiakes or liocculent masses or particles.

Ninth. The oil serves to positively support the diaphragm, and particularly those portions of the same which lie between the meshes of the cathode and which therefore do not derive support therefrom. The tendency of the diaphragm to yield to the pressure of the liquid in the anode-compartment and to become perforated is thereby obviated.

Tenth. The hydrostatic pressure of the an- IOO IIO

ode liquor varies from top to bottom of the diaphragm, and hence the percolation through portions of the diaphragm at different levels would vary through wide limits in the absence of a balancinghydrostatic pressure. The effectI of the balancing or partially-balancing hydrostatic pressure of the oil is to compensate in part for such differences and to equalize the fiow through different portions of the diaphragm.

Eleventh. The heating or cooling means for varying' the temperature of the oil, and hence of the electrolyte, afford a convenient means for control in this respect.

It is to be understood that the foregoing statement of advantages is merely7 illustrative and is not to be construed as in any way limiting the scope of my process as defined in the claims.

In operating the ,cell I have noted a very marked storage effect, the yield at first being low, but rising rapidly to figures closely approximating those required by theory. On ceasing to pass current through the cell a strong secondary current appears, apparently due to the oxidation of sodium which had been deposited upon the cathode and protected from oxidation. This secondary current persists for a long period and caustic-soda solution is delivered from the cell during the whole of such period. In case it is desired to interrupt the passage of current through the cell the electrical connections may be so changed as to cause this secondary current from two or more cells to pass through other cells, whereby such current is employed to produce a useful effect. Such procedure should not be permitted to continue too long, however, as some oxidation or solution of the cathode may occur. v

The process herein described is claimed in my copending application, Serial No. 207,490, filed May 11, 19011.

This application is a division of my application Serial No. 102,582, filed April 12, 1902.

I claim- 1. An electrolytic cell, comprisinga vessel having two compartments, a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, and a body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, in the other compartment, as set forth.

2. An electrolytic cell, comprising a vessel having two compartments, a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, and a body of a non-saponifying oil in the other compartment, as set forth.

3. An electrolytic cell, comprising a vessel having two compartments, a diaphragm and a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, and a body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, in the other compartment, as set forth.

11. An electrolytic cell, comprising a vessel having two compartments, a diaphragm and a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, and a body of a non-saponifying oil in the other compartment, as set forth.

5. An electrolytic cell, comprising a vessel having two compartments, a diaphragm which will permit limited percolation of the electrolyte and a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, and a body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, in the other compartment, as set forth.

6. An electrolytic cell, comprising a vessel having two compartments, a diaphragm which will permit limited percolation of the electrolyte and a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, and a body of a non-saponifying oil in the other compartment, as set forth.

7 An electrolytic cell, comprising a vessel having two compartments, a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, a body of a liquid which is substantially immis; cible with and inert toward a cathode product of the electrolysis, in the other compartment, and a partition in the cathode-compartment, having passages at or near its upper and lower ends, as set forth.

8. An electrolytic cell, comprising a vessel having two compartments, a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, a body of a non-saponifyingoil in the other compartment, and a partition in the cathode-compartment, having passages at or near its upper and lower ends, as set forth.

9. An electrolytic cell, comprising a vessel having two compartments, a pervious cathode between said compartments, an anode and a` body of electrolyte in one compartment, a body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, in the other compartment, and a partition in the cathode-compartment and relatively near the cathode, said partition having' passages at or near its upper and lower ends, as set forth.

10. An electrolytic cell, comprising a vessel having two compartments, a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, a body of anon-saponifying oil in the other compartment, and a partition in the cathode-compartment and relatively near the cathode, said partition having passages at or near its upper and lower end, as set forth.

ll. An electrolytic cell, comprising a vessel IIO having two compartments, a pervious cathode between said compartments. an anodc and a body of electrolyte in one compartment, a body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, in the other compartment, and means for regulating the temperature of said liquid, as set forth.

12. An electrolytic cell, comprising a vessel having` two compartmen ts, a pervious cathode between said compartments, an anode and a body of electrolyte in one compartment, a body of anon-saponifying oil in the other compartnent, and means foi regulating the temperature of said oil, as set forth.

13. An electrolytic cell, comprisingavessel, two diaphragms subdividing said vessel into three compartments, an anode in the intermediate compartment, a pervious cathode in each side compartment and overlyingI one of said diaphragms, a body of the elcctrolyte in the CLINTON PAUL TOVVN SEND.

Vitnesses:

RoBT. E. J, CoRooRAN, ELoN H. HooKER.

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