Improvements in the Electrolytical Decomposition of Alkaline- chlorides for the Production of Chlorine and Alkalies, and. in Apparatus therefor.
Year: 1892

page_text: Date of Application, 10th Sept., 1892
Complete Specification Left, 13th Oct., 1892-Accepted, 3rd Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Electrolytical Decomposition of Alkaline-
chlorides for the Production of Chlorine and Alkalies, and. in
Apparatus therefor.
I, CAMILLE ALPHONSE FAURE, of 15 Rue des Halles, Paris, in the Republic
of France, Engineer, do hereby declare the nature of this invention to be as
follows:-
"
This invention relates to improvements in the electrolytical decomposition of
alkaline chlorides for the production of chlorine and alkali, and has for its chief.
object to avoid the production of a large quantity of hypochloric acid instead of
chlorine as frequently happens in electrolytical apparatus as heretofore constructed,
and to enable the chlorine and alkali to be obtained in a pure or practically pure
condition.
In order that the nature of my invention may be fully understood I will proceed
to explain the same by reference to the annexed illustrative drawing which
is a vertical cross section of apparatus by means of which the desired result is
effected.
This apparatus comprises any suitable number of electrolytic vessels formed by
walls A of porous brick surmounted by a cap piece a of non-porous brick;
diaphragms B composed of slabs of porous material and arranged parallel to and
at a convenient distance from the walls A; and partitions C formed of a mixture
of suitable substances such as clay, carbon and bitumen, kneaded, agglomerated and
baked in an oven so as to constitute non-porous conducting electrodes.
The electrolytic vessels thus constructed are placed on an impervious foundation
of material that is a non-conductor of electricity such as bricks of sand-stone and
slates connected by a bituminous luting.
The several walls, diaphragms and partitions are firmly stayed apart by blocks
arranged to allow of a free circulation in each compartment.
The compartments formed between the slabs C are fluid tight and insulated; they
are closed at the sides by walls of sand-stone and bitumen.
Each of the compartments formed between the electrodes Cand the diaphragmns B,
and between the electrodes C and the walls A is charged with very dense coke c
and crespectively which from an electrolytical point of view forms a single
electrode with the partitions C next which it is placed and which serves to protect
these partitions against the destructive action of the nascent products, oxygen and
soda, liberated by the electrolytical decomposition of sodic chloride. The oxygen
which will be liberated simultaneously with the chlorine, will be converted in great
part into carbonic acid by combination with the carbon of the coke which can
be easily renewed from time to time. The nascent soda also acts upon the coke
instead of the partitions. In some cases it is even advisable to protect the
partitions C against the destructive action of the soda by means of cast iron
plates which are kept in direct contact with the partitions by means of rammed or
stamped pulverized coke.
The solution of sea-salt, or sodic chloride to be decomposed is supplied to the
compartments e e by pipes D above. This solution, by reason of the walls A and
diaphragms B being composed of porous material, passes into the compartments I
containing the coke c¹ and also into the compartments containing the coke c.
The electric current passes through the battery in the direction of the arrows in
such a manner that the chlorine will be liberated on the positive side F + of the
electrodes C whilst on the negative side F
soda will be liberated. The gases
produced at F are collected in inverted gutters 9 which rest at one side in
-
1

page_text: grooves a¹ formed in the cap pieces a and on the other side on cross walls. In
order to prevent the gas from escaping between these gutters and the surfaces of
the partitions C, the space that remains free is covered in by small slabs m.
The grooves a' in the cap pieces a contain some of the solution as shown which
forms a hermetic seal which is the more efficient because the level of the liquid in
the compartments is inaintained at a level slightly above the upper ridge or
crest a of the said groove.
With the apparatus thus arranged and using simply a solution of sodic chloride
then upon the passage of an electric current more hypochlorous acid would be
obtained on the positive surfaces than chlorine. This drawback however is
obviated by first sending into all the compartments neutral or acid sulphate of soda,
and continuing to send in a small proportion of such salt mixed with the solution of
sodic chloride subsequently used.
After a time, the sulphuric acid ceases to be given off in the gaseous state,
and remains in the liquid state. It then becomes applied to the positive surfaces of
the electrodes, whilst the soda passes to the compartiments between A and C. The
free sulphuric acid thus obtained reacts on the solution of sea-salt (sodic chloride)
which is then supplied in a continuous manner. Acid sulphate of soda and hydro-
chloric acid are thereby formed, the latter reacting upon the hypochlorous acid and
liberating the whole of the chlorine, which passes off through the coke and is
collected under the gutters g. The various solutions thus separated by the partitions
are maintained strictly at the same density by the addition to them of water supplied
by pipes K.
The solution of soda which passes through the partitions A into the compart-
ments I, tends to increase in density, but the water admitted by the pipes exactly
counterbalances this tendency. The solution of sodic chloride which is being
constantly renewed in the compartments e, keeps the acid and the alkaline portions
of the solutions well apart and overcomes their tendency to mingle and combine
notwithstanding their equal density.
a
The solution of sodic chloride and the alkaline solution are continuous along
vertical surface situated, according to the rate of discharge of the soda, at about
the middle of the porous walls A, A, but they do not mingle to any appreciable
extent.
The level of the solution in the compartment I is maintained lower than the
level of the solution in the adjacent compartments, by allowing it to discharge
through an overflow pipe p located at the said level and situated at one end of
the compartments. This discharge is regulated in such a manner as to cause the
liquid to pass from e into I at the same rate as the soda is being produced which
can be readily ascertained by a rough and ready analysis.
The solution of sea-salt or sodic chloride is heated to about 20° or 30° before it is
admitted to the compartments. This heat together with that produced. by the
passage through it of the electric current causes the mean and uniform temperature
of the battery to be about 60° which is very favourable to the exit of the chlorine
and to the electrical conductivity of the solutions.
To enable the solution to be thus heated, there is combined with the electrolytical
apparatus a boiler or ordinary re-heater into which the solution of salt or sodic
chloride is passed before entering the apparatus.
The gaseous products of the electrolytical process consist principally of chlorine,
oxygen, and carbonic acid; they are caused to pass into a purifier and then over
hydrate of lime, whereby chloride of lime is produced. It is however advantageous
to first pass these gases through a column of incandescent coke which couverts the
oxygen into neutral carbon monoxide.
2
1003

page_text: Improvements in the Electrolytical Decomposition of Alkaline-
chlorides for the Production of Chlorine and Alkalies, and in
Apparatus therefor.
1, CAMILLE ALPHONSE FAURE, of 15 Rue des Halles. Paris, in the Republic
of France, Engineer, 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 improvements in the electrolytical decomposition of
alkaline chlorides for the production of chlorine and alkali, and has for its chief
object to avoid the production of a large quantity of hypochlorous acid instead of
chlorine as frequently happens in electrolytical apparatus as heretofore constructed,
and to enable the chlorine and alkali to be obtained in a pure or practically pure
condition.
In order that the nature of my invention may be fully understood I will proceed
to explain the same by reference to the drawing filed with my Provisional Specifi-
cation which is a vertical cross section of apparatus by means of which the desired
result can be effected.
This apparatus comprises any suitable number of electrolytic vessels formed by
walls A. of porous brick each surmounted by a cap piece a of non-porous material;
diaphragms B composed of slabs of porous material arranged parallel to and at a
convenient distance from the walls A.; and partitions C formed of a mixture of
suitable substances such as clay, carbon and bitummen, kneaded, agglomerated and
baked in an oven so as to form non-porous conducting electrodes.
The electrolytic vessels thus constructed are placed on an impervious foundation
of material that is a non-conductor of electricity, such for example as bricks of
sand-stone and slates connected by a bituminous cement.
The several walls, diaphragms, and partitions are firmly stayed apart by blocks
or distance pieces arranged to allow of a free circulation in each compartment.
The compartments formed between the slabs C are fluid tight they are closed at
the sides by walls of sand-stone cemented in place by bitumen.
Each of the compartments formed between the electrodes C and the diaphragms B,
and between the electrode C and the walls A is charged with very dense coke e
and respectively, which from an electrolytical point of view forms a single
electrode with the partitions C next which it is placed, and which serves to protect
these partitions against the destructive action of the nascent products, oxygen and
soda, liberated by the electrolytical decomposition of sodic chloride. The oxygen
which will be liberated simultaneously with the chlorine, will be converted in great
part into carbonic acid by combination with the carbon of the coke which can be
easily renewed from time to time. The nascent soda also acts upon the coke or
electrodes. In some cases it is even advisable to protect the electrodes C against
the destructive action of the soda by means of cast iron plates each fixed at a
distance of say one inch from the negative side of the corresponding electrode,
powdered carbon or coke being ramined in between the two to ensure a larger and
effective contact throughout.
The solution of sea-salt or sodic chloride, to be decomposed is supplied to the
compartments e e, by pipes D above. This solution by reason of the walls A and
diaphragms B being composed of porous material, passes into the compartments I
containing the coke c' and also into the compartments containing the coke c.
The electric current is passed through the battery in the direction of the arrows
so that the chlorine will be liberated on the positive side F + of the electrodes C,

page_text: -
whilst soda will be liberated on the negative side F thereof. The gases produced
at the positive side + are collected in inverted gutters which rest at one side in
grooves a formed in the cap pieces a and on the other side on cross walls. In order
to prevent the gas from escaping between these gutters and the surfaces of the
partitions C, the space between these parts is covered in by small slabs m.
The grooves a' in the cap pieces a contain some of the solution as shown which
forms a hermetic seal which is the more efficient because the level of the liquid in
the compartments is maintained at a level slightly above the upper ridge or crest a²
of the said groove.
With the apparatus thus arranged, and using simply a solution of sodic chloride,
then, upon the passage of an electric current, more hypochlorous acid would be
obtained on the positive surfaces than chlorine. This drawback however is
obviated by first introducing into all the compartments neutral or acid sulphate of
soda preferably in solution and mixed say with an equal weight of a solution of
sodic chloride and continuing to introduce a small proportion of say about 2%
of such salt mixed with the solution of sodic chloride subsequently used.
After a time sulphuric not being given off in the gaseous state, accumulates. It
then becomes applied to the positive surfaces of the electrodes whilst the soda
passes to the compartments between A and C. The free sulphuric acid thus
obtained reacts on the solution of sea-salt (sodic chloride) which is then supplied in
a continuous manner. Acid sulphate of soda and hydrochloric acid are thereby
formed, the latter reacting upon the hypochlorous acid and liberating the whole of
the chlorine, which passes off through the coke and is collected under the gutters g.
The various solutions thus separated by the partitions are maintained strictly at
the same density by the addition to then of water supplied by pipes K.
The solution of soda which passes through the partitions A into the
compartments I, tends to increase in density, but the water admitted by the pipes K
exactly counterbalances this tendency. The solution of sodic chloride which is
being constantly renewed in the compartments e, keeps the acid and the alkaline
portions of the solutions well apart and overcomes their tendency to mingle and
combine which they would otherwise do notwithstanding their practically equal
density.
The solution of sodic chloride and the alkaline solution are in contact with each
other along a vertical surface situated, according to the rate of discharge of the
soda, at about the middle of the porous walls A A, but they do not mingle to any
appreciable extent.
The level of the solution in the compartment 1 is maintained lower than the
level of the solution in the adjacent compartments, by allowing it to discharge
through an overflow pipe p located at the said level and situated at one end of the
compartment. This discharge is regulated in such a manner as to cause the liquid
to pass from e into I at the same rate as the soda is being produced, which can be
readily ascertained by a rough and ready analysis.
The solution of sea-salt or sodic chloride is heated to about 20° or 30° C. before
it is admitted to the compartments. This heat, together with that produced by the
passage through it of the electric current, causes the mean and uniform temperature
of the battery to be about 60° C. which is very favourable to the exit of the chlorine
and to the electrical conductivity of the solutions.
To enable the solution to be heated as mentioned, there is used in conjunction
with the electrolytical apparatus, a boiler or ordinary re-heater into which the
solution of salt or sodic chloride is passed before entering the apparatus through the
pipes D.
The gaseous products of the electrolytical process consist principally of chlorine,
oxygen, and carbonic acid; they are caused to pass into a purifier and then over
hydrate of lime, whereby chloride of lime is produced. It is however advantageous
to first pass these gases through a column of incandescent coke which converts the
oxygen and carbonic acid into neutral carbon monoxide.

page_text: Having now particularly described and ascertained the nature of the said inven--
tion and in what manner the same is to be performed I declare that what I
claim is :-
-
1. The herein described improvement in the electrolytical decomposition of an.
alkaline chloride for the production therefrom of chlorine and alkali according to.
which the electrolytical vessel at the commencement of the process, is charged with.
an alkaline sulphate and a small proportion of such salt is mixed with the solution.
of alkaline chloride subsequently used, as herein set forth for the purpose specified..
2. In the electrolytical decomposition of an alkaline chloride for the production:
therefrom of chlorine and alkali, passing the gases evolved at the positive electrode.
through a mass of incandescent carbonaceous fuel in order to convert the oxygen.
present in such gases into neutral carbon monoxide before utilizing the chlorine for
the manufacture of chloride of lime, as set forth.
3. Apparatus for the electrolytical decomposition of alkaline chlorides for the...
production of chlorine and alkalies, comprising vessels formed of walls such as A of
porous material surmounted by cap pieces of non-porous material, diaphragms such,
as B of porous material, electrodes such as D formed of agglomerated carbon, the...
spaces or compartments formed by and between the said electrodes and the walls..
and diaphragms being charged with coke ce, and gutters such as arranged to
receive the gases evolved at the positive side of the electrodes substantially as
described and shown.
с
4. Apparatus of the kind referred to in the preceding claim constructed with..
supply pipes such as D and K, for the purpose of introducing fresh solution of
alkaline chloride and water respectively for the purpose of maintaining the density
of the liquids in the several compartments of the apparatus practically constant as-
set forth.
Dated this 12th das of Ontabar 1900
C. A. FAURE.
By L. W., per F. B..