Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
10~i0380
Background of the Invention
This invention relates to novel cathode fingers for electro-
lytic cells suited for the electrolysis of aqueous solutions. More
particularly, this invention relates to novel cathode fingers for elec-
trolytic cells suited for the electrolysis of aqueous alkali metal
chloride solutions.
Electrolytic cells have been used extensively for many years
for the production of chlorine, chlorates, chlorites, hydrochloric acid,
caustic, hydrogen and other related chemicals. Over the years, such cells
have been developed to a degree whereby high operating efficiencies have
been obtained, based on the electricity expended. Operating efficiencies
include current, decomposition, energy, power and voltage efficiencies.
The most recent developments in electrolytic cells haYe been in making
improvements for increasing the production capacities of the individual
cells while maintaining high operating efficiencies. This has been done
to a large extent by modifying or redesigning the individual cells and
increasing the current capacities at which the individual cells operate.
The increased production capacities of the individual cells operating at
higher current capacities provide higher production rates for given cell
2~ room floor areas and reduce capital investment and operating costs.
In general, the most recent developments in electrolytic cells
have been towards larger cells which have high production capacities and
which are designed to operate at high current capacities while maintaining
high operating efficiencies. Within certain operating parameters, the
higher the current capacity at which a cell is designed to operate, the
higher is the production capacity of the cell. As the designed current
capacity of a cell is increased, however, it is important that high
operating efficiencies be maintained. Mere enlargement of the component
parts of a cell designed to operate at low current capacity will not
provide a cell which can be operated at high current capacity and still
maintain high operating efficiencies. Numerous design improvements must
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be incorporated into a high current capacity cell so that high operating
efficiencies can be maintained and high production capacity can be
provided.
Because the present invention may be used in many different
electrolytic cells of which chlor-alkali cells are of primary importance,
the present invention will be described more particularly with respect to
chlor-alkali cells and most particularly with respect to chlor-alkali
diaphragm cells. However, such descriptions are not to be understood as
limiting the usefulness of the present invention with respect to other
electrolytic cells.
In the early prior art, chlor-alkali diaphragm cells were
designed to operate at relatively low current capacities of about 10,000
amperes or less and had correspondingly low production capacities. Typical
of such cells is the Hooker Type S Cell, developed by the Hooker Chemical
Corporation, Niagara Falls, New York, U.S.A., which was a major break-
through in the electrochemical art at its time of development and initial
use. The Hooker Type S Cell was subsequently improved by Hooker in a
series of Type S cells such as the Type S-3, S-3A, S-3B, S-3C, S-3D and
S-4, whereby the improved cells were designed to operate at progressively
higher current capacities of about 15,000, 20,000, 25,000, 30,000, 40,000
and upward to about 55,000 amperes with correspondingly higher production
capacities. The design and performance of these Hooker Type S cells are
discussed in Shreve, Chemical Process Industries, Third Edition. Pg. 233
(1967), McGraw-Hill; Mantell, Industrial Electrochemistry, Third Edition,
Pg. 434 (1950), McGraw-Hill; and Sconce, Chlorine, Its Manufacture,
Properties and Uses, A.C.S. Monograph, Pp. 94-97 (1962), Reinhold. U.S.
Patent 2,987,463 by Baker et al. issued June 6, 1961 to Diamond Alkali
discloses a chlor-alkali diaphragm cell designed to operate at a current
capacity of about 30,000 amperes which is somewhat different than the
Hooker Type S series cells. U.S. Patents 3,464,912 by Emery et al. issued
Sept. 2, 1969 to Hooker and 3,493,487 by Currey et al. issued Nov. 2, 1971
1()~03l~0
to Hooker disclose chlor-alkali diaphragm cells designed to operate
at a current capacity of about 60,000 amperes.
The above description of the prior art shows the development
of chlor-alkali diaphragm cell design to provide cells which operate
at higher current capacities with correspondingly higher production
capacities. Chlor-alkali diaphragm cells have now been developed
which operate at high current capacities of about 150,000 amperes and
upward to about 200,000 amperes with correspondingly higher production
capacities while maintaining high operating efficiencies.
Summary of the Invention
In according with the present invention, there are provided
novel cathode fingers for an electrolytic cell. The novel cathode
fingers have a novel cathode finger structure.
The novel cathode finger structure comprises a conductive
metal cathode finger reinforcing means, lengths of highly conductive
metal positioned in the cathode finger structure and foraminous con-
ductive metal means attached to the cathode finger reinforcing means
thereby forming the exterior of the cathode finger structure and gas
compartment space inside the cathode finger structure. The cathode
finger reinforcing means can be provided with a suitable number of
pegs, pins or protrusions. The foraminous conductive metal means can
be attached to these protrusions and thereby provide additional
compartment space for gas, formed at the cathode during electrolysis,
to be channeled to a collection chamber.
The highly conductive metal is preferably positioned on the
cathode finger reinforcing means in the cathode finger structure and
means is provided for attaching the highly conductive metal to the
cathode finger reinforcing means. The highly conductive metal is
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positioned in the cathode finger structure in such a configuration
whereby the lengths of highly conductive metal are adapted to carry
an electric current and to maintain a substantially uniform current
density through the cathode finger structure without any significant
voltage drop across the cathode finger structure and with the most
economical power consumption in the cathode finger structure.
The novel cathode finger structure provides novel cathode
fingers. The cathode walled enclosure contains a plurality of cathode
fingers which extend substantially across the interior of the cathode
walled enclosure and the cathode fingers are attached in electrical
contact to at least one interior sidewall of the cathode walled
enclosure. The cathode busbar structure is attached in electrical
contact to the exterior sidewall of the cathode walled enclosure
adjacent to the attached cathode fingers.
Means are provided for positioning the opposite ends of the
cathode fingers adjacent to the interior sidewall of the cathode walled
enclosure which is opposite to the interior sidewall where the cathode
fingers are attached.
An electrolytic cell provided with the novel cathode fingers
of the present invention may be used in many different electrolytic
processes. The electrolysis of aqueous alkali metal chloride solutions
is of primary importance and the electrolytic cell of the present in-
vention will be described more particularly with respect to this type
of process. However, such description is not intended to be understood
as limiting the usefulness of the cathode fingers of the present invention
or any of the claims covering the cathode fingers of the present invention.
DESCRIPTION OF THE DRAWINGS
The present invention will be more fully described by reference
to the drawings in which:
106(~380
FIGURE 1 is an elevation view of an electrolytic cell and
shows a cathode busbar structure;
FIGURE 2 is an enlarged partial sectional side elevatlon
view of the cell of FIGURE 1 along plane 2-2 and shows another view
of the cathode busbar structure;
FIGURE 3 is an enlarged partial plan view of the cathode
walled enclosure of the cell of FIGURE 1 and shows the relatlve position
of the cathode fingers;
FIGURE 4 is an enlarged partial sectional and elevation view
of the cathode fingers and the cathode walled enclosure of the cell
of FIGURE 3 along plane 4-4 and shows the relative position of the cathode
fingers and anode blades as positioned at the end of the cathode walled
enclosure;
FIGURE 5 is an enlarged sectional side elevation view of a
cathode finger and the cathode walled enclosure of the cell of FIGURE 3
along plane 5-5 and shows the configuration of the highly conductive
metal positioned on the cathode finger reinforcing means;
FIGURE 6 is a side elevation view of the opposlte side of the
cathode finger reinforcing means of FIGURE 5 and shows the visible
configuration of the highly conductive metal positioned thereon;
FIGURE 7 is a side elevation view of another embodiment of
a cathode finger reinforcing means and shows the configuration of the
highly conductive metal positioned thereon;
FIGURE 8 is an end elevational view of the cat'node finger
reinforcing means of FIGURE 7 along plane 8-8 and shows the configuration
of the highly conductive metal positioned thereon and the peg or pin
means;
FIGURES 3, 4, 5, 6, 7 and 8, when viewed together~ show
typical embodiments of cathode finger structures;
l(~WO
Two different types of metals are used to fabricate most
of the various components or parts which comprise the novel cathode
fingers of the present invention. One of these types of metals is
a highly conductive metal. The other type of metal is a conductive
metal which has good strength and structural properties.
The term highly conductive metal is herein defined as a
metal which has a low resistance to the flow of electric current
and which is an excellent conductor of electric current. Suitable
highly conductive metals include copper, aluminum, silver and the
like and alloys thereof. The preferred highly conductive metal is
copper or any of its highly conductive alloys and any mentlon of
copper in this application is to be interpreted to mean that any other
suitable highly conductive metal can be used in the place of copper
or any of its highly conductive alloys where it is feasible or
practical.
The term conductive metal is herein defined as a metal which
has a moderate resistance to the flow of electric current but which
is still a reasonably good conductor of electric current. The con-
ductive metal, in addition, has good strength and structural properties.
Suitable conductive metals include iron, steel, nickel and the like
and alloys thereof such as stainless steel and other chromium steels,
nickel steels and the like. The preferred conductive metal is a
relatively inexpensive low-carbon steel, hereinafter referred to
simply as steel, and any mention of steel in this application is to
be interpreted to mean that any other suitable conductive metal can be
used in the place of steel where it is feasible or practical.
The highly conductive metal and the conductive metal should
have adequate resistance or have adequate protection from corrosion
during operation of the electrolytic cell.
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Referring now to FIGURE 1, electrolytic cell 11 comprises
corrosion resistant plastic top 12, cathode walled enclosure 13 and
cell base 14. Top 12 is positioned on cathode walled enclosure 13 and
is secured to cathode walled enclosure 13 by fastening means (not shown).
A seal is maintained between top 12 and cathode walled enclosure 13 by
means of a sealing gasket. Cathode walled enclosure 13 is positioned
on cell base 14 and is secured to cell base 14 by fastening means (not
shown). A seal is maintained between cathode walled enclosure 13 and
cell base 14 by means of an elastomeric sealing pad. Electrolytic cell
0 11 is positioned on legs 15 which are used as support means for the cell.
Cathode busbar structure 16 is attached in any suitable
manner, as by welding, to steel sidewall 17 of steel cathode walled
enclosure 13. Cathode busbar structure 16 comprises copper lead-in
busbar 18 and a plurality of copper busbar strips 19, 21 and 22 which
have different relative dimensions and are positioned in such a con-
figuration wherein lead-in busbar 18 and busbar strips 19, 21 and 22
are adapted to carry an electric current and to maintain a substantially
uniform current density through cathode busbar structure 16 to electrical
contact points on sidewall 17 of cathode walled enclosure 13.
Cathode busbar structure 1~ can be provided with cooling
means 23 which comprises steel plates 24, 25, 26 and 30 and steel
entrance and exit ports 27 and 28 fabricated in any suitable manner, as
by welding, to form the said cooling means. Cooling means 23 is attached
in any suitable manner, as by welding, to lead-in busbar 18 and busbar
strip 19. Coolant, preferably water, is circulated through cooling means
23 by passage through entrance and exit ports 27 and 28. Cooling means
23 is provided primarily for use when an electrolytic cell adjacent to
electrolytic cell 11 is jumpered and is removed from the electrical
circuit. The use of cooling means 23 permits considerably less copper
to be used in cathode busbar structure 16 which results in a substantial
reduction in capital investment costs for cathode copper. While cooling
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means 23 is provided primarily for use when an electrolytic cell adjacent
to electrolytic cell 11 is jumpered, cooling means 23 can be used during
routine cell operation either to cool cathode busbar structure 16 during
any periodic electric current overloads or to continuously cool cathode
busbar structure 16, thereby permitting further reductions in the use
of copper in cathode busbar structure 16 with an accompanying reduction
in capital investment costs for cathode copper~
Lead-in busbar 18 can be provided with steel contact plates
29 and 31 which ser~e as contact means. Steel contact plates 29 and
31 are attached to lead-in busbar 18 in any suitable manner, as by means
of screws 32. Lead-in busbar 18 and steel contact plates 29 and 31 can
be provided with holes 33 which can serve as means for attaching inter-
cell connectors carrying electricity from an adjacent cell or leads
carrying electricity from another source to lead-in busbar 18. Lead-in
busbar 18 and busbar strip 19 can be used as a cathode jumper busbar
when provided with holes 34 which can serve as means for attaching
cathode jumper connectors when an adjacent electrolytic cell is jumpered
and is removed from the electrical circuit~ It is during this jumpering
operation that cooling means 23 can provide its greatest utility by pre-
venting the temperatures in cathode busbar structure 16 from rising to
levels whereby damage to cathode busbar structure 16 or other components
of electrolytic cell 11 occurs.
Referring now to FIGURE 2, cathode busbar structure 16 is shown
in another view and the description of this figure further describes
cathode busbar structure 16 including the configuration and the different
relative dimensions of the components or parts comprising cathode busbar
structure 16 which were described in FIGURE 1.
Cathode busbar structure 16 comprises copper lead-in busbar
18 and a plurality of copper busbar strips 19, 21 and 22. Busbar strips
19, 21 and 22 are attached to steel sidewall 17 of steel cathode walled
enclosure 13 in any suitable manner, as by means of copper to steel welds
380
35, 37, 38 and 41, and to one another in any suitable manner, as by means
of copper to copper welds 36 and 39. The weld metal is preferably of the
same metal as the busbar strips, that is, copper. This means of attaching
the busbar strips to sidewall 17 greatly decreases the required weld area
and forms a lower electrical contact resistance to sidewall 17 or the
cathode steel. Lead-in busbar 18 is attached to busbar strip 19 in any
suitable manner, as by means of copper to copper weld 42, and lead-in
busbar 18 is attached to sidewall 17 in any suitable manner, as by means
of steel blocks 43. Lead-in busbar 18 is attached to steel blocks 43
in any suitable manner, as by a combination of screws (not shown), and
steel blocks 43 are attached to sidewall 17 of cathode walled enclosure
13 in any suitable manner, as by means of steel to steel welds 40. Steel
contact plates 29 and 31 are attached to lead-in busbar 18 in any suit-
able manner, as by means of screws 32.
The above means of attachment provides a cathode busbar struc-
ture wherein lead-in busbar 18 and the plurality of busbar strips 19, 21
and 22 are attached and electrically interconnected by means of welds
36, 37, 38, 39 and 42 and cathode busbar structure 16 is attached in
electrical contact to sidewall 17 of cathode walled enclosure 13 by means
of welds 35, 37, 38, 40 and 41.
Cathode fingers 44 are attached in electrical contact to side-
wall 17 in any suitable manner, as by welding cathode finger reinforcing
means 45 to sidewall 17. A typical cathode finger 44 is partially shown.
Cathode finger 44 comprises steel cathode finger reinforcing means 45
and perforated steel plates 46 which are attached in any suitable manner,
as by welding. Perforated steel plates 47 are attached in any suitable
manner, as by welding, to perforated steel plates 46 and sidewall 17,
thereby forming peripheral chamber 48.
The height of the plurality of the busbar strips at their points
of attachment to sidewall 17 is usually substantially equal to the height
of cathode finger reinforcing means 45 at their points of attachment to
sidewall 17. This height can be further defined as being of more than
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about one-half of the height of cathode walled enclosure 13. The
thickness of busbar strips 21 and 22 are preferably less than those of
lead-in busbar 18 and busbar strip 19.
The cathode finger reinforcing means are preferably corrugated
structures fabricated from steel sheet, however, other suitable rein-
forcing means such as conductive metal bars, plates, reinforced sheets
and the like can also be used. The cathode finger reinforcing means
serve the dual functions of first, supporting and reinforcing the per-
forated steel plates, and second, carrying electric current to all
sections of the perforated steel plates with a minimum electrical resis-
tance through the cathode finger reinforcing means.
The foraminous conductive metal means used to form the cathode
fingers and the peripheral chamber are preferably perforated steel plates
but can be steel screens. Other suitable foraminous conductive metal
means which can be used to form the cathode fingers and the peripheral
chamber include conductive metal grids, meshes, screens, wire clothes or
the like.
Cathode walled enclosure 13 is positioned on cell base 14 and
is secured to cell base 14 by fastening means (not shown). Cell base 14
comprises elastomeric sealing pad 49 and conductive anode base 51, and,
if needed, structural support means 52. A seal is maintained between
cathode walled enclosure 13 and cell base 14 by means of elastomeric
sealing pad 49.
In a typical circuit of electrolytic cells, electric current
is carried through intercell connectors (not shown) to lead-in busbar
1~ of cathode busbar structure 16. Electric current is then carried and
a substantially uniform current density is maintained through cathode
busbar structure 16 without any significant voltage drop across cathode
busbar structure 16 and with the most economical power consumption in
cathode busbar structure 16. Electric current is carried and a substan-
tially uniform current density is maintained through cathode busbar
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structure 16 by means of the configuration and the different re1ative
dimensions of lead-in busbar 18 and busbar strips 19, 21 and 22. Electric
current is thus carried through cathode busbar structure 16 to electrical
contact points on sidewall 17 of cathode walled enclosure 13 where it is
distributed to cathode fingers 44 and, under these conditions, the electric
current is readily carried to all sections of perforated steel plates 46
with a minimum electrical resistance through cathode finger reinforcing
means 45.
The cathode busbar structure makes the most economic use of in-
~ested capital, namely, the amount of copper or other suitable highly
conductive metal used in the cathode busbar structure. The configuration
and different relative dimensions of the lead-in busbar or busbars and
the plurality of busbar strips significantly reduce the amount of copper
or other suitable highly conductive metal required in the cathode busbar
structure as compared to the prior art. The lead-in busbar or busbars
and the plurality of busbar strips by means of their configuration and
different relative dimensions are also adapted to carry an electric
current and to maintain a substantially unifDrm current density through
the cathode busbar structure.
The configuration and dimensions of the lead-in busbar or bus-
bars and the plurality of busbar strips can vary depending on the designed
current capacity of the electrolytic cell and also can vary depending on
a number of factors such as the current density, the conductivity of the
metal used, the amount of weld area, the fabrication costs and the like.
The cathode busbar structure provides improved electrical con-
ductivity to the immediate area of the cathode fingers, thereby providing
a minimum or no significant voltage drop across the cathode busbar struc-
ture with a substantial reduction in copper or other suitably highly con-
ductive metal expenditures as compared to the prior art.
The cathode busbar structure can enable an electrolytic cell to
be designed to operate as a chlor-alkali diaphragm cell at high current
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1(~03~0
capacities of about 150,000 amperes and upward to about 200,000 amperes
while maintaining high operating efficiencies. These high current
capacities provide for high production capacities which result in high
production rates for given cell room floor areas and reduce capital
investment and operating costs. In addition to being capable of oper-
ation at high amperages, an electrolytic cell can also efficiently
operate at lower amperages, such as about 55,000 amperes using the
cathode busbar structure.
Referring now to FIGURE 3, cathode fingers 44 are enclosed by
steel sidewalls 17, 54, 55 and 56 of steel cathode walled enclasure 13.
The plurality of cathode fingers 44 can be any number from about 10 to
about 50 or more, preferably the number is about 15 to about 40 and more
preferably the number is about 20 to about 30. The anode blades (not
shown) are positioned between cathode fingers 44. Perforated steel
plates 46 are attached in any suitable manner, as by welding, to steel
cathode finger reinforcing means 45. Steel plates 53 are also attached
in any suitable manner, as by welding, to cathode finger reinforcing
means 45. Cathode fingers 44 are attached to steel sidewall 17 in any
suitable manner, as by welding steel plates 53 and cathode finger rein-
forcing means 45 to sidewall 17. Perforated steel plates 47 are attached
to sidewalls 17, 54, 55 and 56 and to perforated steel plates 46 in any
suitable manner, as by welding. Perforated steel plates 47 surround the
inner sidewalls of cathode walled enclosure 13 and form peripheral
chamber 48 which serves as a collection chamber for hydrogen gas formed
at the cathode during electrolysis. Hydrogen gas formed at the cathode
during electrolysis is channeled across cathode fingers 44 to peripheral
chamber 48 from whence it proceeds to gas withdrawal means 57.
Referring now to FIGURE 4, perforated steel plates 46 are
attached in any suitable manner, as by welding, to steel cathode finger
3~ reinforcing means 45. Steel plates 53 are attached in any suitable
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manner, as by welding, to cathode finger reinforcing means 45 Steel
support means 58 are attached in any suitable manner, as by welding,
to cathode finger reinforcing means 45 and to sidewall 56 of steel
cathode walled enclosure 13. Perforated steel plates 47 are attached in
any suitable manner, as by welding, to perforated steel plates 46 and to
sidewalls 17 and 56 thereby forming peripheral chamber 48. Because of
the larger dimensions of this figure, peripheral chamber 48 is more
clearly shown. Cathode finger reinforcing means 45 can be provided with
protrusions 59 and perforated steel plates 46 can be attached in any
suitable manner, as by welding, to protrusions 59 thereby providing
additional compartment space for hydrogen gas, formed at the cathode
during electrolysis, to be channeled to peripheral chamber 48.
Steel tips 61 and steel plates 53 are attached in any suitable
manner, as by welding, to copper rods 62. Steel tips 61 and steel plates
53 are attached in any suitable manner, as by welding, to cathode finger
reinforcing means 45 thereby positioning copper rods 62 on cathode finger
reinforcing means 45.
Cathode finger reinforcing means 45 are preferably corrugated
structures fabricated from sheet steel, however, other suitable rein-
forcing means such as bars, plates, reinforced sheets and the like canalso be used. Cathode finger reinforcing means 45 serve the dual
functions of first, supporting and reinforcing perforated steel plates
46, and second, carrying electric current to all sections of perforated
steel plates 46 with a minimum electrical resistance through cathode
finger reinforcing means 45.
Referring now to FIGURES 2 and 4, cathode walled enclosure 13
is positioned on cell base 14 and is secured to cell base 14 by fastening
means (not shown)~ Cell base 14 comprises conductive anode base 51 and,
if needed, suitable structural support means 52. A seal is maintained
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between cathode walled enclosure 13 and cell base 14 by means of
elastomeric sealing pad 49.
Anode blades 72 are preferably metallic anode blades and are
attached in electrical contact to conductive anode base 51 in any suitable
manner, as by means of nuts and/or bolts, secured projections, studs,
welding or the like. Cathode fingers 44 are spaced adjacent to each other
at such a distance whereby anode blades 72 are centered between adjacent
cathode fingers 44 and the desired alignment distance between anode blades
72 and cathode fingers 44 is provided.
Referring now to FIGURES 2, 3 and 4, electrolytic cell 11 is par-
ticularly useful for the electrolysis of alkali metal chloride solutions
in general, including not only sodium chloride, but also potassium chloride,
lithium chloride, rubidium chloride and cesium chloride. When electrolytic
cell 11 is used to electrolyze such solutions, electrolytic cell 11 is
provided with diaphragm 71 which serves to form separate anolyte and
catholyte compartments so that chlorine is formed at the anode and caustic
and hydrogen are formed at the cathode. Diaphragm 71 comprises a fluid-
permeable and halogen-resistant material which covers steel plates 46
forming cathode fingers 44 and perforated steel plates 47 forming peri-
pheral chamber 48. Preferably, diaphragm 71 is asbestos fiber deposited
in place on the outer surfaces of perforated steel plates 46 and 47. Elec-
trolytic cell 11 is adapted to permit the use of many types of diaphragms,
including asbestos fabric, asbestos paper, asbestos sheet and other suit-
able materials known to those skilled in the art.
Perforated steel plates 46 forming cathode fingers 44 and per-
forated steel plates 47 forming peripheral chamber 48 are foraminous con-
ductive metal means. Other suitable foraminous conductive metal means
which can be used to form the cathode fingers and the peripheral chamber
include conductive metal grids, meshes, screens, wire cloths or the like.
Referring now to FIGURES 3 and 5, some of the details described
in the foregoing figures are more clearly shown in these figures. Cathode
busbar structure 16 is attached to outer sidewall 17 of cathode walled
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enclosure 13 and the ends of cathode fingers 44 adjacent thereto are
attached to inner sidewall 17 of cathode walled enclosure 13 in the manner
or manners described in the foregoing figures.
The other ends of cathode fingers 44 are preferably positioned
as follows: Posterior ends 63 of steel cathode finger reinforcing means
45 are positioned adjacent to steel sidewall 55 of steel cathode walled
enclosure 13 by means of steel support members 64, 65, 66 and 67. Support
members 64 and 65 are attached in any suitable manner, as by welding, to
cathode finger reinforcing means 45 and rest upon support members 66 and
67 which are attached in any suitable manner, as by welding, to sidewall
55. Support members 64 and 65 can be attached or fastened to support
members 66 and 67, respectiYèly, however, it is preferred that support
members 64 and 65 not be attached or fastened so that both linear and
horizontal thermal expansion and/or contraction can be provided for cathode
fingers 44.
Perforated steel plates 47 are attached in any suitable manner,
as by welding, to sidewalls 17, 54, 55 and 56, respectively, and to
adjacent perforated steel plates 46 thereby forming peripheral chamber 48.
Copper rods 62 are preferably of different lengths and are
preferably positioned on cathode finger reinforcing means 45 as shown in
FIGURE 5~ Steel tips 61 are attached in any suitable manner, as by weld-
ing, to ends 68 of copper rods 62 and steel ~late 53 ~s attached in any
suitable manner, as by welding, to linear ends 73 of copper rods 62 there-
by forming cathode copper assembly 69~ Cathode copper assembly 69 is
attached to cathode finger reinforcing means 45 in any suitable manner,
as by welding steel tips 61 and steel plate 53 to steel cathode finger
reinforcing means 45~ Copper rods 62 can thus be positioned on cathode
finger reinforcing r~eans 45~ Copper rods 62 are of sufficient length and
preferably are of different lengths to maintain substantially uniform
current density through cathode finger 44. Copper rods 62 do not neces-
sarily have to be round or uniform in cross-section and can be square,
rectangular, hexagonal, octagonal or the like in cross-section and can
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38~)
vary ;n cross-section along their lengths. It is important, however,
that copper rods 62 be of sufficient length and cross-section to carry an
electric current and to maintain a substantially uniform current density
through cathode fingers 44 without any significant voltage drop across
cathode fingers 44 and with the most economlcal power consumption in
cathode fingers 44.
The use of a suitably highly conductive metal, such as copper,
in cathode fingers 44 as shown in FIGURES 4, 5, 6, 7 and 8 is considered
to be a novel use of a suitable highly conductive metal in the cathode
fingers. The use of copper in the cathode fingers is disclosed in U.S.
Patents 3,464,912 by Emery et al. issued Sept. 2, 1969 to Hooker and
3,493,487 by Ruthel et al. issued Feb. 3, 1970 to Hooker, however, these
disclosed uses of copper in the cathode fingers do not disclose, much
less teach, the use of copper in the cathode fingers of an electrolytic
cell in the manner as taught herein.
The preferred method of positioning copper rods 62 on cathode
finger reinforcing means 45 and in cathode fingers 44 is also novel. Steel
tips 61 are welded to ends 68 of copper rods 62 and steel plate 53 is
welded to linear ends 73 of copper rods 62 thereby forming cathode copper
assembly 69. Any warpage from the welding of steel tips 61 and steel
plate 53 to copper rods 62 is corrected or compensated for before cathode
copper assembly 69 is attached to cathode finger reinforcing means 45.
Cathode copper assembly 69 is attached to cathode finger reinforcing
means 45 by welding steel tips 61 and steel plate 53 to steel cathode
finger reinforcing means 45. Copper rods 62 are thus positioned on
cathode finger reinforcing means 45 and in cathode fingers 44. In this
manner, all the copper to steel welds are made prior to the welding of
cathode copper assembly 69 to cathode finger reinforcing means 45 and any
metal warpage from welding is substantially eliminated.
The novel cathode fingers can enable an electrolytic cell to be
designed to operate as a chlor-alkali diaphragm cell at high current
capacities of about 150,000 amperes and upward to about 200,000 amperes
while maintaining high operating efficiencies. These high current capa-
cities provide for high production capacities which result in high pro-
duction rates for given cell room floor areas and reduce capital invest-
ment and operating costs. In addition to being capable of operatlon athigh amperages, an electrolytic cell can also efflciently operate at
lower amperages, such as about 55,000 amperes using the novel cathode
fingers.
Referring now to FIGURE 6, the opposite side of cathode finger
reinforcing means 45 shown in FIGURE 5 is shown and the visible configura-
tion of copper rods 62 positioned thereon is also shown. Cathode copper
assembly 69 which comprises copper rods 62, steel plate 53 and steel tips
61 is shown positioned on cathode finger reinforcing means 45. Cathode
finger reinforcing means 45 can be provided with protrusions 59 and per-
forated steel plates 46 can be attached in any suitable manner, as by
welding, to protrusions 59 thereby providing additional compartment space
for hydrogen gas, formed at the cathode during electrolysis, to be
channeled to peripheral chamber 48. Protrusions 59 are positioned at
spaced intervals on cathode finger reinforcing means 45 and only a repre-
sentative portion are shown in this figure.
Referring now to FIGURES 7 and 8, another embodiment of a
cathode finger reinforcing means is shown and a configuration of copper
rods positioned thereon is also shown. In this embodiment, cathode finger
reinforcing means 111 comprises steel plate 112 having steel peg or pin
means 113 extending therefrom. Cathode copper assembly 69 which comprises
copper rods 62, steel plate 53 and steel tips 61 is shown positioned on
steel plate 112 of cathode finger reinforcing means 111 with a portion of
steel plate 112 removed to accommodate steel plate 53. Cathode copper
assembly 69 is attached to cathode finger reinforcing means 111 in any
suitable manner, as by welding steel plate 53 and steel tips 61 to steel
plate 112. Perforated steel plates 46 can be attached in any suitable
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manner, as by welding, to steel peg means 113 thereby providing compart
ment space for hydrogen gas, formed at the cathode during electrolysis,
to be channeled to peripheral chamber 48.
Preferred Embodiments
The following Example illustrates the practice of the present
invention and a mode of utilizing the present invention.
EXAMPLE
The following data is typical of the performance of an electro-
lytic cell provided with the novel cathode fingers of the present invention
operating at a current capacity of 150,000 amperes. The performance is com-
pared with the performance of a smaller electrolytic cell of the prior art,
also equipped with metal anode blades, operating at a current capacity of
84,000 amperes. Both electrolytic cells are chlor-alkali diaphragm cells.
150,000 Ampere Cell
84,000 Ampere CellProvided with the Novel
of the Prior ArtCathode Fingers of the
Present Invention
Current Efficiency 96.4 96.4
Average Cell Voltage
(including busbars) 3.84 3.83
Power - KWHDCtTon C12 2735 2725
Cell Liquor Temperature -C. 100.5 100.7
Anolyte Temperature - C 94.5 94.7
Percent NaOH in Cell Liquor 11.5* 11.5*
Chlorine Production - Tons/Day 2.83 5.06
NaOH Production - Tons/Day 3.20 5.71
Brine Feed - ~rams/Liter 325 325
Current Density-Amperes/sq. in. 1.5 1.5
* The cells can be operated at lower caustic content in the cell
30liquor. This will result in greater current efficiencies.
The above data show that the electrolytic cell provided with the
novel cathode fingers of the present invention operates at essentially the
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lQ~U380
same current efficiency, voltage and operating conditions as the smaller
electrolytic cell of the prior art at the same anode current density.
The electrolytic cell provided with the novel cathode fingers of the
present invention has a higher production rate for a given cell room
floor area, uses less operating labor and also has a lower capital in-
vestment per ton of chlorine produced.
This example shows that an electrolytic cell can be designed to
operate at a high current capacity to provide a high production capacity
and a high production rate while maintaining high operating efficiencies.
An electrolytic cell provided with the novel cathode fingers of
the present invention can have many other uses. For example, alkali
metal chlorates can be produced using the electrolytic cell by further
reacting the formed caustic and chlorine outside of the cell. In this
instance, solutions containing both alkali metal chlorate and alkali
metal chloride can be recirculated to the electrolytic cell for further
electrolysis. The electrolytic cell can be utilized for the electrolysis
of hydrochloric acid by electrolyzing hydrochloric acid alone or in
combination with an alkali metal chloride. Thus, the electrolytic cell
is highly useful in these and many ot'ner aqueous processes.
While there have been described various embodiments of the
present invention, the apparatus described is not intended to be under-
stood as limiting the scope of the present invention. It is realized
that changes therein are possible. It is further intended that each
component recited in any of the following claims is to be understood as
referring to all equivalent components for accomplishing the same results
in substantially the same or an equivalent manner. The following claims
are intended to cover the present invention broadly in whatever form the
principles thereof may be utilized.
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