Improvements in or connected with Diaphragms for Electrolytic Purposes.
Year: 1894

page_text: Date of Application, 10th Aug., 1894-Accepted, 15th Sept., 1894
COMPLETE SPECIFICATION.
Improvements in or connected with Diaphragms for Electrolytic
Purposes.
"
We, MARTIN KILIANI, of Neuhausen, Switzerland, Doctor of Philosophy, and
WALTHER RATHENAU, of 22, Schiffsbauerdam, Berlin, Germany, Doctor of
Philosophy, and CARL SUTER, of Neuhausen, Switzerland, Engineer, and the
Corporation "ELEKTROCHEMISCHE WERKE of 22 Schiffsbauerdam, Berlin,
Germany, 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 :-
The construction of a serviceable diaphragm for electrolysing salts, especially
when the operation is to be carried out on a large scale, has hitherto been
attended with many difficulties, the material used having proved either hard to
work, or being wanting in durability. Very frequently these diaphragms have to
be constructed in the form of vessels surrounding one of the electrodes and
containing the electrolyte surrounding the said electrode, the other electrode
being arranged externally with respect to this closed system. Where firm and
hard porous substances, such as clay, permeable porcelain and the like are used
for the construction of the diaphragms, such construction does not certainly
involve any serious impediments or difficulties in itself; but it is generally found,
that, in addition to other drawbacks, the aforesaid substances have the objectionable
feature of offering a very great resistance to the electrical current. Where, on
the other hand, thin sheets of soft flexible material or membranes offering little
or no resistance to mechanical strains and capable of being easily rent or torn,
such as parchment, asbestos fabric and the like are employed, special arrange-
ments are requisite in order to impart sufficient firmness to the walls of the
diaphragm to enable them to withstand safely any differences of pressure that
may arise during the electrolytic process while avoiding the necessity for unduly
thick walls or immoderate overlapping of the membrane of porous material both
of which augment the resistance of the diaphragm and at the same time reduce
its useful or available area.
When it is desired to construct large diaphragms in the form of vessels of such
non-resistant diaphragm-material, it is necessary to impart sufficient firmness to
the walls of the same. Now it has to be taken into account that, on the one
hand, the structural parts employed for this purpose, have to be made of substances
which are proof against the action of acids and alkalies and are therefore, for
the most part, rather difficult to work into shape, and that on the other hand
it is desirable to avoid so far as practicable, the subdivision of such structural
parts into sections, and the necessity, consequent thereon, of providing packing
or means for tightly closing the joints.
The improved construction of a diaphragm according to this invention, as
hereinafter described and illustrated by the accompanying drawings, affords a
practical and convenient nieans for meeting the requirements hereinbefore stated.
According to this invention the diaphragm material is enclosed within two frames
combined therewith, in a peculiar manner, which, in addition to rendering the
whole arrangement extremely simple and easily controllable has the advantage
of facilitating the firm and reliable locking or securing in position of the walls
of the diaphragm. Another advantage of the improved construction is, that it
requires but few simple moulded pieces and consequently presents but few joints

page_text: requiring to be packed, the said pieces permitting of being readily manufactured
in great quantities.
On the annexed sheet of drawings,
Figs. 1 to 4 show several modes of supporting the diaphragm.
Fig. 1 is a section through and a view from below of a portion of a diaphragm-
vessel, the diaphragm being supported as indicated in Fig. 1.
Fig. 2 is a similar section and view of a portion of a
diaphragm being held and steadied as shown in Fig. 2.
diaphragm vessel, the
Fig. 3 is a similar section and view of a portion of a diaphragm vessel, the
diaphragm being maintained as represented in Fig. 3.
Fig. 4 is a similar section and view of a portion of a diaphragm vessel, the
diaphragm being steadied as indicated in Fig. 4.
Fig. 5 is a perspective view of a complete diaphragm vessel, placed vertically.
Fig. 6 is a similar view of a compound diaphragm-vessel.
Fig. 7 is an isometrical view of a diaphragm-vessel placed horizontally and open
at the top, whilst the side on which it is placed, is made solid.
The diaphragm e consisting of a permeable membrane (parchment, glass-wool,
asbestos card or the like) is steadied by being compressed between two series of
parallel laths bars or rods, a, b, of acid proof material such as glass, porcelain or
the like, which laths bars or rods may be arranged opposite each other in such a
manner as to either coincide on the same lines respectively (as shown in Figure 1);
or so as to break joint with each other, each lath bar or rod on one side being
placed about half way between a pair of laths bars or rods on the other side (as
illustrated in Figure 2); or they may be arranged all in the sanie plane, in which
case the material of the diaphragm will have, as it were, to undulate through them
(as shown in Figure 3); or again, the laths bars or rods may be at right angles to
each other (as shown in Figure 4). By combining a number of sheets of
diaphragm material thus enclosed between laths bars or rods a box or receptacle
may be constructed, the shape or disposition of the parts of which will of course,
depend on requirements and the material used in its construction. Considering the
little power of resistance of such diaphragms, the safety and reliability of the
operation almost entirely depend upon the secure position of the lattice-work or
framework which, once put in place and properly adjusted, should remain firmly in
position. To attain this result the laths, bars or rods are all jointly secured to
two end- or edge-frames d, d' (Figure 5), one of which is to form the upper edge
of the diaphragm or receptacle, whilst the other surrounds its bottom, or itself
constitutes the bottom plate. The upper edge frame may be constructed so as to
constitute a lid or cover, if desired.
One of the main peculiarities of this improved arrangement is that it does not
require a special frame for each side of the vessel, the said frame lying in the plane
of the side, but that the whole of the laths bars or rods being retained in position
by one pair of frames d d which, for this purpose, are arranged at right angles to
the said laths bars or rods. These frames, therefore, do not, properly speaking,
enclose the lattices, but rather constitute a directrix for the arrangement of the
said laths bars or rods. With this mode of construction, the shape of the diaphragm
or receptacle is determined by the form of the frames d d¹, or, in other words,
the frames d d have to conform to the shape to be given to the diaphragm or
receptacle for instance for diaphragms in the form of rectangular vessels,
rectangular frames dd, and for diaphragmns in the form of oval or round vessels,
oval or round frames d d are to be used.
For the purpose of enabling the laths bars or rods to be properly secured to
the frames dd, the said frames are provided at their edges with series of indenta-
tions or notches e (Figures 14, 24, 34, 44). Into these indentations or notches
the inner laths bars or rods are fitted, so that a species of cage is formed.
The permeable or porous material c is tightly stretched around this cage and
then is surrounded by another outer casing of similar lattice work formed of, laths
bars or rods a retained in position by india rubber rings for by wire wound round

page_text: them or by any other suitable means to tightly press the said laths bars or rods
against the diaphragm c (Fig. 5). In Fig. 4 the ends of the outer rods a enter
notches in the frames d d¹.
In order to still further increase the stability of the structure, the upper frame d
may be connected by a number of supports with the lower frame or the bottom
plate.
For extensive plant diaphragm vessels are frequently required of such a size
that one single membrane or diaphragm is not sufficient to form the walls, or
that the exceptional length of the laths bars or rods forming the supports or
lattice work would not be sufficiently secure. In these cases the novel structural
arrangement offers the additional advantage of enabling a number or series or
system of frames to be combined together by means of an intermediate frame or
intermediate frames such as d2 d³ of a similar nature to those above and below
(Figure 6).
The diaphragms or receptacles may be arranged either vertically or horizontally,
as desired. Moreover, according to the purpose for which they are intended, one
side or more sides may be left open i.e. have no diaphragm wall in them, or such
side or sides may be closed by a wall of solid material.
and
Figure 7 represents a diaphragm of this description arranged for use in the
horizontal position. One side thereof (the top side) is open as shown at
serves the same purpose as the upper opening or orifice of the vertical arrange-
ment, while the side opposite to this opening having to bear the pressure of the
liquid which the diaphragm contains, is made solid and forms the bottom or base
plate . In cases where a number of such diaphragms are to be arranged in
juxtaposition the adjacent sides may be left open or they may be closed either by
a solid wall or by a pervious wall.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. For electrolytic purposes an acid proof and alkali-proof diaphragm constructed
in the form of a vessel consisting of a permeable membrane held between frames
of lattice work composed of parallel laths, bars or rods, such as a b, of a material
proof against both acids and alkalies, and the whole system of such laths, bars or
rods secured to end-frames such as d d', the shape of which frames determines the
outline of the shape in plan or horizontal section of the diaphragm.
2. A diaphragm in the form of a vessel such as is claimed in the preceding
claiming clause and having the laths bars or rods constituting the inner frame or
lattice fitted in indentations or notches provided for their reception in the frames d d¹
whilst the laths bars or rods constituting the outer frame or lattice are securely
fastened to, and pressed against the frames and the membrane interposed between
them, by means of devices such as india rubber rings bands or wires such as
(Figs. 14, 24, 34).
f
3. In a diaphragm in the form of a vessel such as is claimed under the preceding
first claiming clause the arrangement of intermediate frames such as d for the
purpose of increasing the stability of the diaphragm.
4. A diaphragm in the form of a vessel such as is claimed under the preceding
first claiming clause but with a side or with sides left open or closed by a solid
wall for the purpose of enabling the system to be arranged horizontally and
steadying it, substantially as hereinbefore described and illustrated by Figure 7 of
the accompanying drawings.
Dated this 10th day of August 1894.