CA2316930A1

CA2316930A1 - Low current density electrolytic cell and method of manufacturing same

Info

Publication number: CA2316930A1
Application number: CA002316930A
Authority: CA
Inventors: Richard L. Romine
Original assignee: Individual
Current assignee: Eltech Systems Corp
Priority date: 1998-11-05
Filing date: 1999-11-04
Publication date: 2000-05-25
Also published as: PL343901A1; EP1048093A1; ZA200003243B; BR9906750A; NO20003456L; WO2000030187A2; NO20003456D0; WO2000030187A3

Abstract

An electrolytic cell (1) and method for decreasing the power consumption of an electrolytic cell (1) having a fixed designed current capacity in one aspect comprises refitting an electrolytic cell (1) with additional cathodes and anodes to lower the overall current density of the cell. In order to accommodate the additional anodes, the cathode-to-cathode spacing (CS) can be reduced and the cathodes can also be reconfigured to provide a narrower cathode tube structure (11). This can be accomplished by decreasing the spacing between opposed cathode plates (12). This modification permits operation of the cell (1) at the original designed current capacity at a significantly reduced power consumption. New cell manufacture is also contemplated.

Description

AND METHOD OF MANUFACTURING SAME

BACKGROUND OF THE INVENTION

1. Field of Invention The present invention relates to an electrolytic cell of decreased current density which allows for lower power consumption, and a method 20 for reconfiguring an electrolytic cell to allow for lower power consumption while maintaining the designed current capacity of the cell.

2. Description of the Related Art 25 Electrolytic cells are used extensively on an industrial scale for the production of metals and chemicals, e.g., for the electrowinning of aluminum, copper, nickel and zinc and the production of chlorine, chlorides, sodium hydroxide, sodium chlorate, hydrogen and oxygen. Of primary importance in this invention are the chlor-alkali cells, and particularly chlor-30 alkali diaphragm cells.
Chior-alkali diaphragm cells were originally designed to operate at relatively low current capacities of about 10,000 amperes. These cells had relatively low production capacities by modern standards. Typical cells of this type are the Hooker Type S cells which were developed by the Hooker Chemical Corporation. This particular cell was subsequently improved upon by increasing its designed current capacity to about 50,000 amperes with 5 corresponding increases in production capacity.
Subsequent cell designs have bean directed at increasing the operating efficiency based on the electrical energy consumed, and to increasing the production capacity of the cell to obtain a higher production 10 rate for a given cell room area. This has been achieved to a large extent by modifying or redesigning the cell to increase the designed current capacity.
This, in turn, directly increases the production capacity of the cell. As the designed current capacity of the cell is increased, however, it is necessary to maintain high operating efficiencies to maintain production economics.
15 Mere enlargement of the component parts of a cell initially designed to operate at a relatively low current capacity for operation at a higher current capacity will not achieve high operating efficiencies. Consequently, modifications in the cell design as well as in the design of individual cell components is often required to achieve this result. These design 20 improvements include the use of expandable anodes and cathode structures of improved strength, current distribution and hydrogen gas release.
Modern electrolytic cells of this type are capable of operating at current capacities of 165,000 amperes or more with production capacities 25 of 5 tons per day or more of chlorine or sodium hydroxide, and current efficiencies exceeding 95%. In U.S. Patent 3,899,408, there is taught an electrolytic cell designed for operation at such high current capacities. The cell is provided with cathode structures comprised of cathode "fingers" in the form of a rectangular box formed from foraminous conductive metal plates. A corrugated conductive metal reinforcing member is enclosed within the cathode finger and extends the length of the cathode. This corrugated member is in electrical and physical contact with the cathode finger, and serves to provide structural support for the cathode finger, to 5 maintain a uniform current distribution, and to provide a space for release of hydrogen gas.
It would still be desirable, however, to provide an electrolytic cell design capable of operating at high current capacities and production rates, 10 yet provide decreased power consumption. It would also be desirable to provide such an electrolytic cell and in doing so to modify only the internal components of the cell and thereby utilize the existing cell structure and its support equipment to maximum advantage.

In accordance with the present invention, a method for substantially decreasing the power consumption of an electrolytic cell while maintaining the designed current capacity is achieved by increasing the number of 20 cathodes and anodes within the cell body. This can be accomplished in part by decreasing the lateral dimensions of the individual cathode tubes.
This modification helps to allow the use of substantially more cathodes and anodes within the cell. It can be used with a reduction in the existing spacing between anodes and cathodes. Moreover, sufficient space is 25 maintained within cathode tubes to allow for improved release of hydrogen gas from the cathode. Subsequent assembly of a new cell in accordance with the present invention, or reassembly of a cell on refurbishing of an existing cell, results in a cell having a substantial reduction in power consumption and a lower operating current density. In this manner, in one aspect of the invention, the number of anodes within the cell can be 5 increased from 42 up to as many as 50 elements, while the number of cathodes can be increased from 20 up to as many as 24 elements.
In addition to the foregoing advantages, the new electrolytic cell has the following additional advantage of improved anodic efficiency as a result 10 of lower current density producing smaller chlorine gas bubbles at the anode which are more easily removed from the anode surface. Similarly, the hydrogen disengagement of the cathode is also improved, resulting in less hydrogen in the chlorine which is a significant product improvement.
In addition, the lower current density also results in a lower cell liquor 15 temperature which reduces the corrosion of metal parts and extends the life of the plastic cell top and rubber anode blanket.
In one aspect, the invention is directed to an electrolytic cell having a walled enclosure of a size containing from about 42 to about 46 anodes 20 and from about 20 to about 22 cathodes, the cathodes comprising spaced apart conductive metal cathode tube members of foraminous conductive metal plates forming the exterior of a cathode tube structure, the improvement in the cell comprising an increased number of up to about 25 cathode tube members of reduced cathode-to-cathode spacing and an 25 increased number of up to about 52 anodes, of reduced anode-to-anode spacing, the cell having a cathode area increase of up to about 20 percent and an anode area increase of up to about 20 percent.

WQ 00/3018? PCT/US99/2610?
In a related aspect, the invention is directed in a manner related to the foregoing, but for a cell having three times the number of anodes than cathodes, plus three additional anodes, wherein there is provided an increased number of anodes from about 87 to about 102, and increased 5 number of cathodes from about 28 to about 33.
In another aspect, the invention is directed to a method of decreasing the power consumption of an electrolytic cell, the cell having a walled enclosure of a size containing from about 42 to about 46 anodes and from about 20 to about 22 cathodes, with there being a proportion of two times the number of anodes than cathodes, plus two additional anodes, each cathode comprising spaced apart foraminous conductive metal plates forming the exterior of a cathode tube structure, wherein a cell top is removed from the electrolytic cell and the walled enclosure of a size is separated from a cell base, the method comprising the steps of:
(a) removing the cathode tube structures from the cell;
(b) replacing the cathode tube structures within the cell with an increased number of up to about 24 cathode tube structure members of reduced cathode-to-cathode spacing;
20 (c) providing an increased number of up to about 52 anodes to the cell to correspond in the aforesaid proportion with the increased number of cathode tube structure members, with the cathode tube structure members being positioned between anodes;
(d) reattaching the cathode walled enclosure of a size to the cell base, whereby the cell size is maintained while the anodes and cathodes are increased; and (e) replacing the cell top.

Wa00/30187 PCT/US99/26107 In a related aspect, the above method is directed in a related manner to a cell having about 87 anodes and about 28 cathodes, where there is provided an increase to about 102 anodes as well as to about 33 cathodes.
5 In yet another aspect, the invention is directed to a method for providing an electrolytic cell of reduced power consumption, said cell having a walled enclosure sized for containing from about 42 to about 46 anodes and from about 20 to about 22 cathodes, with there being a proportion of two times the number of anodes than cathodes, plus two 10 additional anodes, each cathode comprising spaced apart conductive foraminous metal plates forming the exterior of a cathode tube structure, wherein the cell comprises a cell top, the walled enclosure, and a cell base, the method comprising the steps of:
la) inserting in the cell an increased number from greater than 15 about 20 up to about 25 cathode tube structure members of. reduced cathode-to-cathode spacing;
(b) providing an increased number of up to about 52 anodes to the cell to correspond in the aforesaid proportion with the increased number of cathode tube structure members, with the cathode tube structure 20 members being positioned between anodes;
(c) attaching the cathode walled enclosure of the size to the cell base; and (d) attaching the cell top.
25 Again in a related manner, the foregoing method can be directed to a cell having about 87 anodes and about 28 cathodes, where there is provided an increase to about 102 anodes and about 33 cathodes.

W(3 OOI30187 PCT/US99/26107 In a still further aspect, the invention is directed to a cathode tube structure member comprising spaced apart foraminous conductive metal plates having a tube width of about 1 5/64 inches and a tube length of about 50 inches.

In another aspect, the invention is directed to a method of operating an electrolytic cell having from greater than 20 up to about 24 cathodes and from greater than 42 up to about 50 anodes, which method comprises:
(a) carrying out the electrolytic cell operation at a current density 10 below 1.5 amps/inchz;
(b) operating the electrolytic cell at a current capacity within the range of from about 50,000 amperes to about 100,000 amperes; and (c) conducting the electrolytic cell operation at a cell voltage below about 3.4.

BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading 20 the following specification with reference to the accompanying drawings, in which:
Fig. 1 is a perspective view of the exterior of an electrolytic cell used for employing the present invention.
Fig. 1 A is a side elevation, in section of a type of cathode sidewall 25 utilized for the electrolytic cell of Fig. 1.
Fig. 2 is an enlarged partial sectional and elevation view depicting internal components including cathode tube structures, as well as a portion of the walled enclosure of the electrolytic cell of Fig. 1.
Fig. 2A is a magnified view of a portion of the cathode tube structures and anodes of Fig. 2 highlighting the cathode-to-cathode spacing (CS) and the cathode tube width (TW).

Electrolytic cells employing the present invention can typically be useful for the electrolysis of a dissolved species contained in a bath, such as in electrolyzers employed in a chlor-alkali cell to produce chlorine and 10 caustic soda, or in an electrolysis process producing chlorate.
The cathode and cathode assembly elements can be made of any electrically conductive metal resistant to attack by the catholyte in the cell.
Steel and stainless steel can be advantageously used, as well as nickel and 15 valve metals such as titanium may be utilized. The cathodes can be any of those as are conventionally used in a cell including activated cathodes.
Referring then, to Fig. 1, there is shown an electrolytic cell 1 which can be adapted in accordance with the present invention. Principal 20 elements of the cell 1 include the cell top 2, which can be formed from a corrosion-resistant plastic material, the cathode walled enclosure or "cell can" 3, and cell base 5 (Fig. 2). Part of the cathode walled enclosure 3 is positioned behind a sidewall busbar 4 (Fig. 1 A), as will be more particularly described hereinbelow. The cell top 2 is fastened to the cathode walled 25 enclosure 3 which is, in turn, fastened to a cell base 5. The fastening means allow ease of removal of the cell top 2, cathode walled enclosure 3 and cell base 5.

Referring then to Fig. 1 A, there is depicted the interface bonded structure of walled enclosure 3 and sidewall busbar 4. This bonded structure extends the full length from an edge of the cell top 2 downwardly to a cell base 5. The sidewall busbar 4 can be a unitary, monolithic and 5 planar busbar 4 that, for the particular cell of the figure, is as high as the cathode walled enclosure 3 and can be longer than the walled enclosure 3 to which it is bonded. The busbar 4 may thus be actually larger than the walled enclosure 3. The extra length of the sidewall busbar 4 and its adjacent walled enclosure 3 together form one wall of the cell 1. In 10 assembly, the cathode busbar 4, being typically a copper busbar 4, can be interface bonded to the cathode walled enclosure 3 such as by explosion bonding, brazing or roll bonding. A cathode busbar 4 of this type is described in U.S. Patent 5,137,612, the disclosure of which is incorporated herein by reference.

It is contemplated that for purposes of the present invention, however, the cathode busbar structure 4 may comprise other configurations, e.g., a plurality of copper busbar strips of varying dimensions. These busbar strips can be attached to the cathode walled 20 enclosure 3 by any suitable manner, as by welding. A cathode busbar structure of this type is described in U.S. Patent 3,904,504, the disclosure of which is incorporated herein by reference.
In Fig. 2 there is then illustrated, for a representative cell, the 25 cathode walled enclosure 3 and the individual cathode tube structure members 11 . These representative cathode tube structure members 11 are formed from pairs of adjacent parallel conductive metal screens or perforated plates 12. These two plates 12, with their top 12A and bottom 12B, collectively form a cathode tube. The plates 12 of an individual tube 11 for the representative cell of the figure to be refurbished are usually spaced apart approximately 1 3/16 inches. The cathode tube structure members 11 further include cathode tube reinforcing means 15. Disposed at each end of the electrolytic cell 1 and within the walled enclosure 3 are 5 cathode end tube structures 17. These end tube structures 17 are somewhat identical to the cathode tubes 11, however, the end tube structures have only one conductive metal screen or perforated plate 12 forming the end of the cathode tube structure.
10 In Fig. 2A, there is then shown an expanded view of the bottom portion of Fig. 2, in which the cathode tube structure member width, usually referred to herein just as the "tube width" (TW) is illustrated. This tube width is the distance measured between the outside surfaces of the two plates 12 of a cathode tube. The cathode-to-cathode spacing (CS), 15 then, is the distance measured between cathodes. This can be the spacing between adjacent cathodes or, as depicted in the figure, the spacing between a cathode end tube structure 17 and the next adjacent cathode tube structure member 11. In the representative old cell 1 to be refurbished, the spacing (CS) will generally be 2 1 /4 inches.

In operation, the cell 1 is filled with an electrolytic medium, preferably a brine solution, and current is supplied to the cell 1 through external connections. The products of the cell 1 are removed through outlets situated on the side of the cell 1. These products for a chlor-alkali 25 cell include sodium hydroxide, chlorine and hydrogen gas.
In refurbishing an electrolytic cell 1 in accordance with the present invention, the initial step is to drain the cell 1 of electrolytic solution and disconnect the external electrical connections to the cell 1. The cell top 2 is then removed from the cell by disconnecting it from the cathode walled enclosure 3. After removal of the cell top 2, the cathode walled enclosure 3 is disconnected and removed from the cell base 5. The cathode walled enclosure 3 can be removed from the cell base 5 using any convenient 5 means, such as by a crane or hoist.
After detachment and removal of the cathode walled enclosure 3 from the cell base 5, the cathode tube structure members 1 1, usually 20 in number for this representative cell, are removed from the cathode walled 10 enclosure 3. This is accomplished by cutting the cathode rim screen 16 (Fig. 2) around the internal periphery of the cathode walled enclosure 3 and then cutting any connection points of the cathode tube structure members 11 to the cathode walled enclosure 3. The existing cathode tube structure members 1 1 are then removed from the enclosure 3.

New cathode tube structure members 11 similar in appearance and which can be at least generally similar in their elements of construction to the original cathode tube structure members 11 are then installed into the cathode walled enclosure 3. The new cathode tube structure members 11, 20 however, for the representative cell of the figures, have a narrower lateral dimension or "tube width" (TW) of approximately 1 5/64 inches, again as measured between the outside surfaces of adjacent plates 12 in the same structure 11. This width permits the accommodation of up to 24 cathode tube structures 11 in the refurbished cathode walled enclosure, providing a 25 cathode area increase of up to approximately 20 percent. Generally, such cathode area increase of from about 15 to about 20 percent can be realized for the type of cell as represented by the cell of the figutes. In order to accommodate this narrower structure, any corrugated conductive metal reinforcing means 15 which may be used will also be narrower, i.e., have a narrower width, than the original reinforcing means. For length, the new cathode tube structure members 11 can, by way of example, have a tube length of about 50 inches.
5 Additionally, it is contemplated that conductive rods (not shown) may be placed between the corrugations of the reinforcing means 15 and form a part of the cathode tube structure members 11. These rods can be metal rods consisting of copper, brass, or bronze and can serve to conduct electrical current more efficiently along the cathode tubes. The space 10 between the reinforcing means 15 and the perforated plates 12 is approximately the same as provided in the original design. This space defines a hydrogen gas channel within the cathode tube structure member 11. While the tube width is decreased for the cell of the figures, this helps allow for an increased number of tubes, thereby providing adequate space 15 for release of the hydrogen gas from the cathode tube structure member 11. The same number of electrical contact points is also more than adequate in the new member since the reconfigured cell has a somewhat lower current density than the original cell. For instance, the refurbished cell of the figures may have a current density of as low as approximately 20 1.2 amperes per square inch. This compares to a current density of 1.5 amperes per square inch for the conventional cell. Both of these current densities are based on equivalent design current capacity of 84,000 amperes. Design current capacity for commercial cells will often be within the range from about 50,000 amperes to about '100,000 amperes.

The new cathode tube structure members 1 1 are then reinstalled in the cathode walled enclosure 3 in a similar manner as the original cathode tube structure members 11. A new cathode rim screen 16 is also installed around these members 11 and the sidewall of the cathode walled enclosure 3. By reduction of the cathode-to-cathode spacing ICS) from a conventional 2 1 /4 inches to 1 7/8 inches, additional anodes 20 can be inserted in the new configuration, boosting the total from 42 anodes to a total of up to 50 anodes, in the refurbished representative cell of the 5 figures. This represents an anode area increase of up to approximately twenty percent. It will, hence, be understood that the type of cell as represented by the cell of the figures has a proportion of anodes to cathodes that is two times the number of anodes than cathodes, plus two additional anodes. With the improved cells of this type there can generally 10 be obtained an anode area increase of from about 15 to about 20 percent.
The anodes 20 (Fig. 2) are positioned between adjacent cathode tube structure members 11. All cathodes, including additional cathodes, are attached to the cell base 5 in any suitable manner, such as by bolting or welding. Also, in a cell refurbishing, the anode-to-anode spacing can be 15 reduced from 3 5/8 inches to 3 1 /8 inches. As for the cathodes, this anode spacing is the width within the cell 1 between adjacent anodes 20.
While the representative invention cell of the figures has herein been described as containing 24 cathodes and 50 anodes, it is also contemplated 20 that the cell could contain from 21 to 23 cathodes. In this regard, there would then be from 44 to 48 anodes, there being two times as many anodes as cathodes in the cell, plus two additional anodes.
If the invention cell is an improved MDC-55, such cell can have three 25 times the number of anodes than cathodes, plus three additional anodes.
Thus, an original cell of 28 cathodes and 87 anodes may have, as an improved cell, 33 cathodes and 102 anodes. For this type of cell the anode area increase, as well as the cathode area increase, can also be on the order of about 20 percent. For this cell the anode-to-anode spacing may be reduced by about 0.8 inch. Moreover, where the invention cell could be an improved MDC cell of the type MDC-29 that has twice the number of anodes than cathodes, plus two additional anodes, the cell could contain 25 cathodes, as opposed to 22 for the original cell, and as an improved cell 5 have 52 anodes, as opposed to 46 for the original cell. These original MDC
types of cells ace in commercial use and have been depicted in Kirk-Othmer, 4'" edition, Volume No. 1 at page 967.
The cathode walled enclosure 3 can then be reattached to the cell 10 base 5. The cell top 2 is then reinstalled and attached to the cathode walled enclosure 3. Following connection of the electrical contacts, the cell 1 can be placed into service.
The outer surfaces of the individual cathode plates 12 are covered by 15 a separator. The separator for the cell will be a diaphragm, e.g., an asbestos diaphragm, which may sometimes be referred to herein as a "diaphragm porous separator". For the diaphragm in the electrolytic cell 1, a synthetic, electrolyte permeable diaphragm can also be utilized. The synthetic diaphragms generally rely on a synthetic polymeric material, such 20 as polytetrafluoroethylene fiber as disclosed in U.S. Patent 5,606,805 or expanded polytetrafluoroethylene as disclosed in U.S. Patent 5,183,545.
Such synthetic diaphragms can contain a water insoluble inorganic particulate, e.g., silicon carbide, or zirconia, as disclosed in U.S. Patent 4,606,805. Of particular interest for the diaphragm is the generally non-25 asbestos fiber diaphragm containing inorganic particulates as disclosed in U.S. Patent 4,853,101. The teachings of this patent are incorporated herein by reference.

Broadly, this diaphragm of particular interest comprises a non-isotropic fibrous mat wherein the fibers of the mat comprise 5-70 weight percent organic halocarbon polymer fiber in adherent combination with about 30-95 weight percent of finely divided inorganic particulates 5 impacted into the fiber during formation. The diaphragm has a weight per unit surface area of between about 3 to about 12 kilograms per square meter. Preferably, the diaphragm has a weight in the range of about 3-7 kilograms per square meter. A particularly preferred particulate is zirconia.
Other metal oxides, i.e., titanic, can be used, as well as silicate, aluminates, 10 ceramics, cermets, carbon, and mixtures thereof. Especially for this diaphragm of particular interest, the diaphragm may be compressed, e.g., at a compression of from about one to about 6 tons per square inch.
It is contemplated that the anodes 20 will be coated with an 15 electrochemically active coating. As representative of the electrochemically active coatings for the foraminous metal anode are those provided from platinum or other platinum group metals or they can be represented by active oxide coatings such as platinum group metals, magnetite, ferrite, cobalt spinal or mixed metal oxide coatings. Such coatings have typically 20 been developed for use as anode coatings in the industrial electrochemical industry. They may be water based or solvent based, e.g., using alcohol solvent. Suitable coatings of this type have been generally described in one or more of the U.S. Patent Nos. 3,265,526, 3,632,498, 3,711,385 and 4,528,084. The mixed metal oxide coatings can often include at least one 25 oxide of a valve metal with an oxide of a platinum group metal including platinum, palladium, rhodium, iridium, and ruthenium or mixtures of themselves and with other metals. Further coatings include tin nxidR
manganese dioxide, lead dioxide, cobalt oxide, ferric oxide, platinate coatings such as MxPT304 where M is an alkali metal and x is typically targeted at approximately 0.5, nickel-nickel oxide and a mixture of nickel and lanthanum oxides, such an lanthanum nickelate.
it has been observed that a loss of current efficiency occurs in the 5 present invention. This decrease in current efficiency results from the reduction in power consumption and identical feed brine temperature and ambient conditions of a conventional cell. To counter effect the hss ir, current efficiency, it is contemplated that the operating temperature of the present invention can be increased by either raising the feed brine 10 temperature or by insulating the electrolytic cell. This is typically done by wrapping the cathode with an insulation blanket.
While the foregoing discussion has been directed to refurbishing of a conventional electrolytic cell, it is also contemplated that the present 7 5 invention can be directed to the construction of a new electrolytic cell.
Results of the cell operation presented in the following table illustrate the improved performance of the representative new cell of the figures as compared to the conventional, or comparative cell. Both cells operate at an 20 equivalent design current capacity of 84,000 amperes and also produce the same amount of cell product. However, the new cell has a significantly reduced power consumption as well as a reduced current density and operates at a cell voltage below 3.4.

Comparative Cell Invention Cell Current efficiency 95.6 95.3 Average Cell Voltage 3.48 3.30 Power (KWHDC/metric ton CI2) 2751 2617 Cell Liquor Temperature 96.5 93.4 Anolyte Temperature 92.5 90 Cell Liquor Strength (g/I NaOH) 145 ~ .
145'"

Brine Feed (g/I NaCI) 325 325 Current Density (amperes/in2) 1.5 1.26 15 "The cells can be operated at lower caustic content in the cell liquor.
This will result in greater current efficiencies.

Claims

18

1. In an electrolytic cell having a walled enclosure of a size containing from about 42 to about 46 anodes and from about 20 to about 22 cathodes, said cathodes comprising spaced apart conductive metal cathode tube members of foraminous conductive metal plates forming the exterior of a cathode tube structure, the improvement in said cell comprising an increased number of up to about 25 cathode tube members of reduced cathode-to-cathode spacing and an increased number of up to about 52 anodes, of reduced anode-to-anode spacing, said cell having a cathode area increase of up to about 20 percent and an anode area increase of up to about 20 percent.

2. The electrolytic cell of claim 1 wherein said cathode-to-cathode spacing is reduced from about 2 1/4 inches to about 1 7/8 inches and said cathode tube members also have a reduced width that is reduced from about 1 3/16 inches to about 1 5/64 inches.

3. The electrolytic cell of claim 1 wherein said cathodes of reduced width are cathode tube structures containing support means and said support means comprise corrugated conductive reinforcing means alternately attached and in electrical contact with said cathode tube members.

4. The electrolytic cell of claim 3 wherein said corrugated conductive reinforcing means include conductive rods between said reinforcing means, said conductive rods are metal rods and said metal is a metal selected from the group consisting of copper, brass, and bronze.

5. The electrolytic cell of claim 1 wherein said cell has a current capacity within the range from about 50,000 amperes to about 100,000 amperes and the anode current density of said cell is within the range from about 1.2 amps/inch2 to about 1.5 amps/inch2.

6. The electrolytic cell of claim 1 wherein said anode-to-anode spacing is reduced from about 3 5/8 inches to about 3 1/8 inches.

7. The electrolytic cell of claim 1 wherein said cell contains a separator between said cathode and said anode.

8. The electrolytic cell of claim 7 wherein said separator comprises a diaphragm and said cell produces one or more of chlorine, caustic soda, or potassium hydroxide.

9. The electrolytic cell of claim 8 wherein said diaphragm is a synthetic diaphragm comprising organic polymer fibers in adherent combination with inorganic particulates, which diaphragm further comprises a non-isotropic fibrous mat comprising 5-70 weight percent of halocarbon polymer fiber in adherent combination with about 30-95 percent of finely divided inorganic particulate.

10. The electrolytic cell of claim 1 wherein said cell further comprises means for insulating said cathode tube structure members as well as further comprising a cathode busbar structure external to said cell, which structure has a unitary, at least substantially rectangular-shaped and wall-sized, sidewall busbar comprised of a busbar section and an extension section.

11. The electrolytic cell of claim 10 wherein said unitary sidewall busbar is a planar busbar which is interface bonded to said cathode sidewall by explosion bonding, brazing, or roll bonding.

12. The electrolytic cell of claim 1 wherein said cell further comprises a cathode busbar structure, said structure optionally comprises a plurality of copper busbar strips of different relative dimensions and said cathode busbar structure is attached to said cathode sidewall as by welding.

13. The electrolytic cell of claim 1 wherein said cell comprises from 21 to 24 cathodes of reduced width and from 44 to 50 anodes, with there being two times the number of anodes than cathodes, plus two additional anodes.

14. The electrolytic cell of claim 1 wherein said cell further comprises a cathode end tube structure at each cell end, which end tube structure has one foraminous conductive metal plate forming the end of said cathode tube structure and said end tube structures are disposed on ends of said electrolytic cell within said walled enclosure.

15. In an electrolytic cell having a walled enclosure of a size containing about 87 anodes and about 28 cathodes, with there being three times the number of anodes than cathodes, plus three additional anodes, said cathodes comprising spaced apart conductive metal plates forming the exterior of a cathode tube structure, the improvement in said cell comprising an increased number of up to about 33 cathode tube members of reduced tube width and an increased number of up to about 102 anodes of reduced anode-to-anode spacing, said cell having a cathode and anode area increase of up to about 20 percent.

16. The electrolytic cell of claim 15 wherein said cathode tube member width is reduced from about 1 3/16 inches to about 1 5/64 inches.

17. The electrolytic cell of claim 15 wherein said anode-to-anode spacing is reduced by about 0.8 inch.

18. The electrolytic cell of claim 15 wherein said cell contains a separator between said cathode and said anode.

19. The electrolytic cell of claim 18 wherein said separator comprises a diaphragm and said cell produces one or more of chlorine, caustic soda, or potassium hydroxide.

20. The electrolytic cell of claim 19 wherein said diaphragm is a synthetic diaphragm comprising organic polymer fibers in adherent combination with inorganic particulates, which diaphragm further comprises a non-isotropic fibrous mat comprising 5-70 weight percent of halocarbon polymer fiber in adherent combination with about 30-95 percent of finely divided inorganic particulate.

21. The electrolytic cell of claim 15 wherein said cell further comprises a cathode busbar structure external to said cell, which structure has a unitary, at least substantially rectangular-shaped and wall-sized, sidewall busbar comprised of a busbar section and an extension section.

22. The electrolytic cell of claim 21 wherein said unitary sidewall busbar is a planar busbar which is interface bonded to said cathode sidewall by explosion bonding, brazing, or roll bonding.

23. The electrolytic cell of claim 15 wherein said cell further comprises a cathode busbar structure, said structure optionally comprises a plurality of copper busbar strips of different relative dimensions, and said cathode busbar structure is attached to said cathode sidewall as by welding.

24. In a method for decreasing the power consumption of an electrolytic cell, said cell having a walled enclosure of a size containing from about 42 to about 46 anodes and from about 20 to about 22 cathodes, with there being a proportion of two times the number of anodes than cathodes, plus two additional anodes, each cathode comprising spaced apart foraminous conductive metal plates forming the exterior of a cathode tube structure, wherein a cell top is removed from said electrolytic cell and said walled enclosure of said size is separated from a cell base, said method comprising the steps of:
(a) removing said cathode tube structures from said cell;
(b) replacing said cathode tube structures within said cell with an increased number of up to about 25 cathode tube structure members of reduced cathode-to cathode spacing;
(c) providing an increased number of up to about 52 anodes to said cell to correspond in said proportion with said increased number of cathode tube structure members, with said cathode tube structure members being positioned between anodes;
(d) reattaching said cathode walled enclosure of said size to said cell base, whereby said cell size is maintained while said anodes and cathodes are increased; and (e) replacing said cell top.

25. The method of claim 24 wherein said increased number of cathode tube structure members have a decreased cathode-to-cathode spacing between adjacent cathode tube structure members and said decreased spacing between said adjacent cathode tube structure members is decreased from about 2 1/4 inches to about 1 7/8 inches.

26. The method of claim 24 wherein said cathode tube structure members have a reduced width, said width is reduced from about 1 3/16 inches to about 1 5/64 inches said increased number of anodes is provided at least in part by reduced anode-to-anode spacing and said anode-to-anode spacing is reduced from about 3 5/8 inches to about 3 1/8 inches.

27. The method of claim 24 wherein said cell has a cathode area increase of up to about 20 percent and an anode area increase of up to about 20 percent, said cell has a current capacity within the range of from about 50,000 amperes to about 100,000 amperes, and said cell has an anode current density within the range of from about 1.2 amps/inch2 to about 1.5 amps/inch2.

28. The method of claim 24 wherein said foraminous conductive metal plates are perforated metal plates or screens and said increased number of cathode tube structures contain corrugated reinforcing means.

29. The method of claim 24 wherein said method is directed to refurbishing an electrolytic cell.

30. A refurbished electrolytic cell made by the method of claim 29.

31. In a method for decreasing the power consumption of an electrolytic cell, said cell having a walled enclosure of a size containing about 87 anodes and about 28 cathodes, with there being a proportion of three times the number of anodes than cathodes, plus three additional anodes, each cathode comprising spaced apart foraminous conductive metal plates forming the exterior of a cathode tube structure, wherein a cell top is removed from said electrolytic cell and said walled enclosure of said size is separated from a cell base, said method comprising the steps of:
(a) removing said cathode tube structures from said cell;
(b) replacing said cathode tube structures within said cell with an increased number of up to about 33 cathode tube structure members of reduced cathode tube structure width;
(c) providing an increased number of up to about 102 anodes to said cell to correspond in said proportion with said increased number of cathode tube structure members, with said cathode tube structure members being positioned between anodes;
(d) reattaching said cathode walled enclosure of said size to said cell base, whereby said cell size is maintained while said anodes and cathodes are increased; and (e) replacing said cell top.

32. The method of claim 31 wherein said cathode tube structure is decreased in width from about 1 3/16 inches to about 1 5/64 inches.

33. The method of claim 31 wherein said increased number of anodes is provided at least in part by reduced anode-to-anode spacing.

34. The method of claim 33 wherein said anode-to-anode spacing is reduced by about 0.8 inch.

35. The method of claim 31 wherein said cell has a cathode area increase of up to about 20 percent and an anode area increase of up to about 20 percent.

36. The method of claim 31 wherein said foraminous conductive metal plates are perforated metal plates or screens.

37. The method of claim 31 wherein said method is directed to refurbishing an electrolytic cell.

38. A refurbished electrolytic cell made by the method of claim 37.

39. A method for providing an electrolytic cell of reduced power consumption, said cell having a walled enclosure seized for containing from about 42 anodes to about 46 anodes and from about 20 to about 22 cathodes, with there being a proportion of two times the number of anodes than cathodes, plus two additional anodes, each cathode comprising spaced apart conductive foraminous metal plates forming the exterior of a cathode tube structure, wherein said cell comprises a cell top, said walled enclosure, and a cell base, said method comprising the steps of:
(a) inserting in said cell an increased number of from greater than about 20 up to about 25 cathode tube structure members of reduced cathode-to-cathode spacing;
(b) providing an increased number of up to about 52 anodes to said cell to correspond in said proportion with said increased number of cathode tube structure members, with said cathode tube structure members being positioned between anodes;
(c) attaching said cathode walled enclosure of said size to said cell base; and (d) attaching said cell top.

40. The method of claim 39 wherein said increased number of cathode tube structure members have a decreased cathode-to-cathode spacing and said decreased spacing is about 1 7/8 inches.

41. The method of claim 39 wherein said cathode tube structure members have a reduced width and said width is reduced from about 1 3/16 inches to about 1 5/64 inches.

42. The method of claim 39 wherein said increased number of anodes is provided at least in part by reduced cathode-to-cathode spacing and anode-to-anode spacing and said anode-to-anode spacing is about 3 1/8 inches.

43. The method of claim 39 wherein said electrolytic cell has a current capacity within the range of from about 50,000 amperes to about 100,000 amperes and an anode current density within the range of from about 1.2 amps/inch2 to about 1.5 amps/inch2.

44. An electrolytic cell made by the method of claim 39.

45. A method for providing an electrolytic cell of reduced power consumption, said cell having a walled enclosure sized for containing about 87 anodes and about 28 cathodes, with there being a proportion of three times the number of anodes than cathodes, plus three additional anodes, each cathode comprising spaced apart conductive foraminous metal plates forming the exterior of a cathode tube structure, wherein said cell comprises a cell top, said walled enclosure, and a cell base, said method comprising the steps of:
(a) inserting in said cell an increased number of up to about 33 cathode tube structure members of reduced cathode tube structure width;
(b) providing an increased number of up to about 102 anodes to said cell to correspond in said proportion with said increased number of cathode tube structure members, with said cathode tube structure members being positioned between anodes;
(c) attaching said cathode walled enclosure of said size to said cell base; and (d) attaching said cell top.

46. The method of claim 45 wherein said cathode tube structure width is reduced from about 1 3/16 inches to about 1 5/64 inches.

47. The method of claim 45 wherein said increased number of anodes is provided at least in part by reduced anode-to-anode spacing.

48. The method of claim 47 wherein said anode-to-anode spacing is reduced about 0.8 inch.

49. An electrolytic cell made by the method of claim 45.

50. The method of operating an electrolytic cell having from greater than 20 up to about 24 cathodes and from greater than 42 up to about 50 anodes, which method comprises:

(a) carrying out said electrolytic cell operation at a current density below 1.5 amps/inch2.
(b) operating said electrolytic cell at a current capacity within the range of from about 50,000 amperes to about 100,000 amperes; and (c) conducting said electrolytic cell operation at a cell voltage below about 3.4.

51. A cathode tube structure member comprising spaced apart foraminous conductive metal plates having a tube width of about 1 5/64 inches and a tube length of about 50 inches.