Improvements in Apparatus for the Electrolysis of Salt.
Year: 1893

page_text: Date of Application, 9th May, 1893-Accepted, 19th Aug., 1893
COMPLETE SPECIFICATION.
Improvements in Apparatus for the Electrolysis of Salt.
I, THOMAS CRANEY, of 624 Harrison Street, Bay City, County of Bay State
of Michigan, United States of America, Manufacturer, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
This invention relates to new and useful improvements in apparatus for the
manufacture of caustic soda by electrolytic decomposition of chloride of sodium or
common salt, and the invention consists in the arrangement and combination of
different parts, whereby the apparatus is adapted for commercial use.
The main object of my invention is to adapt the apparatus for continuous work
to facilitate the collection of the products and to control its operation, all as more
fully hereinafter described, and shown.
In the drawings,
Fig. 1 is a vertical, central cross-section, shown in diagram.
Fig. 2 is a plan view of my apparatus.
Fig. 3 is a detail showing the construction of the support for the anode.
Fig. 4 is a detail showing the construction of one of the sections of the cup.
A is a tank or vat containing the electrolyte in solution. This tank is preferably
made of iron in a substantial form and provided with a conical bottom B and a
talse bottom C, which is grated or perforated, and of suitable strength to support
the weight of the cells, and their enclosed anodes. The tank preferably forms the
cathode and is connected to the proper pole of the generator and insulated in any
suitable manner. The tank may be supported in any manner, preferably by
suspending it from overhead beams.
Within the tank or vat and supported upon the perforated bottom C thereof, are
a series of cups D which enclose the anodes E and serve as a dividing diaphragm
between the anodes and cathodes, and as receptacles for a solid product at the
anodes, and to this end these cups are constructed, in the following manner.
That portion of the cups which is immersed within the solution of the tank
is built of superimposed sections a, or stoneware or other indestructible material
as shown in Fig. 3, and affording between the joints (which are preferably
interlocking) communication between the interior of the cups and the tank for
efficient electrolytic action; the upper portion of the cups are made gas tight in
one or more sections, preferably of an apertured ring section F and a dome shaped
top cover G sealed upon a ring section and provided with a fill aperture H, and a
central aperture I, through which the upper end of the anode protrudes and is
sealed therein.
J is a body of salt, preferably of the granulated form in which it is usually
manufactured, and filled in the space around the anode up to or near the height of
the solution in the tank.
The anode is preferably made of a body of carbon enclosed within and supported
by superimposed sections as shown in Fig. 4 of stoneware which form large
interstices between to expose the carbon for electrolytic action upon the
electrolyte.
The cups communicate with each other at or near the surface of the solution in
the tank through pipes K sealed in the apertures, provided for in the ring sections
of the cups, and leading to a discharge pipe L for carrying off the chlorine or
other gaseous product of decomposition arising within the cups and also as an
overflow for the solution from the tank itself, whereby some of the waste products
incidently formed are also carried off and may be separately collected.
From a collector M having valves N N', a pipe O leads up to or near the level

page_text: of the surface of the solution in the tank, and is connected by a flexible portion P
to a receptacle Q, which is swung from a scale beam adjusted to hold the out-flow-
opening of the overflow pipe R at a corresponding level with the solution in the
tank, provided the receptacle is filled with a solution of caustic soda of proper
strength, such as will be furnished by the proper and effective operation of the
apparatus in its working condition.
The overflow pipe R discharges into a tank T, in which the product from the
apparatus is collected for further operation. It will be seen that with this arrange-
ment the greater specific gravity of the solution of caustic soda, compared with
that of the solution undecomposed in the tank is made use of to separate and
collect it and at the same time control and determine such separation by the
weighing process, as the receptacle Q when the solution is not strong enough
becomes lighter and thereby rises up and carries the flexible portion of the pipe P
with it thereby diminishing the overflow until the electrolytic action has again
reached its proper limit.
The apparatus is further provided with a supply tank V for supplying fresh
liquid to the tank A through a pipe W, which passes into the top of the said
tank A and through which the hydrogen may escape. In lieu of other means
fresh salt may be added from day to day into the cups through the fill apparatus H.
A discharge pipe U and suitable valves N, N', are also provided for drawing off
or emptying the contents of the tank when required, as for instance, should the
contents become foul or saturated with accumulated waste products, which may
thus be saved for other purposes if desired.
I lay particular stress upon the facile separation provided in my tank for the
escape of the caustic alkali which can freely follow its specific gravity, and
naturally gravitate to the lowest point, and from there into the collector M, and
finally into the tank T.
I do not intend to confine myself to carrying on the operation exactly in the
manner described, as circumstances may arise where it is preferable to draw off
the caustic alkali at intervals and the direct discharge or overflow provided at
intervals directly from the bottom of the tank or from the receiver.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1. The combination with an electrolytic cell, of a receiver connected to the
bottom of the cell by a valve controlled connection and means for discharging the
liquid from the receiver.
2. The combination in an electrolytic cell, of the tank containing the electrolyte,
the receiver connected to the bottom thereof, the overflow pipe from the receiver,
a weighing receptacle flexibly connected to said overflow, and an overflow from said
receptacle.
3. The combination in an elect.olytic cell, of a tank containing the electrolyte,
the perforated false bottom or grating, the receiver connected to the bottom thereof,
the overflow pipe from the receiver extending up to the height of the electrolyte
in the tank, the weighing receptacle flexibly connected to said overflow pipe and
the overflow from the receptacle.
4. The combination with an electrolytic cell of an overflow pipe, through which
the liquid is discharged from the bottom of the cell, and a weighing receptacle
flexibly connected thereto and into which said overflow pipe discharges.
Dated 15th
5th day of March 1902
THOMAS CRANEY.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.