US3705842A

US3705842A - Float measuring device for mercury cells

Info

Publication number: US3705842A
Application number: US89643A
Authority: US
Inventors: Alexander L Barbato
Original assignee: Diamond Shamrock Corp
Current assignee: Diamond Shamrock Chemicals Co; Eltech Systems Corp; Diamond Shamrock Corp
Priority date: 1970-11-16
Filing date: 1970-11-16
Publication date: 1972-12-12
Anticipated expiration: 1989-12-12

Abstract

D R A W I N G
METHOD FOR DETERMINING THE DISTANCE BETWEEN THE WORKING FACE OF AN ANODE AND A RESERVOIR OF MERCURY BENEATH THE ANODE IN A SUBSTANTIALLY ENCLOSED ELECTROLYTIC CELL HAS A VALUE ESTABLISHED FOR THE POSITION OF THE WORKING FACE OF THE ANODE IN THE CELL ON AN EXTERNAL SCALE MEANS AND ANOTHER VALUE ESTABLISHED FOR THE SURFACE OF THE MERCURY RESERVOIR IN THE CELL ON THE EXTERNAL SCALE MEANS. THE DEPTH OF THE MERCURY RESERVOIR CAN ALSO BE DETERMINED. A MEASURING DEVICE IN AN ELECTROLYTIC CELL HAS A TUBE ATTACHED TO A CAGE ON AN ANODE NEAR AN OPENING IN THE ANODE. THE CAGE FORMS A CHAMBER ABOVE THE OPENING IN THE ANODE AND THE OTHER END OF THE TUBE IS CONNECTED WITH AN OPENING IN THE COVER OF THE ELECTROLYTIC CELL. A FLOAT IS MOVABLY DISPOSED BETWEEN THE CHAMBER AND THE MERCURY RESERVOIR. THE FLOAT FITS INTO THE CHAMBER AND PREFERABLY HAS A HEIGHT EQUAL TO THE HEIGHT OF THE CHAMBER ABOVE THE WORKING FACE OF THE ANODE. THE FLOAT HAS A ROD ATTACHED WHICH EXTENDS THROUGH THE TUBE TO GIVE READINGS ON A SCALE MEANS LOCATED OUTSIDE THE ELECTROLYTIC CELL.

Description

Dec. 12,1972 A. L. BARBATO 3,705,842

FLOAT MEASURING DEVICE FOR MERCURY CELLS FiledNov. 16, 1970 INVENTOR ALEXANDER L. BARBATO, Deceased by PATRICIA J. BARBATO, Execufrix ATTORNEY United States Patent Othce 3,705,842 Patented Dec. 12, 1972 3,705,842 FLOAT MEASURING DEVICE FOR MERCURY CELLS Alexander L. Barbato, deceased, by Patricia J. Barbato,

executrix, Perry, Ohio, assignor to Diamond Shamrock Corporation, Cleveland, Ohio Filed Nov. 16, 1970, Ser. No. 89,643 Int. Cl. C01d 1/08; C22d N04 US. Cl. 204-99 17 Claims ABSTRACT OF THE DISCLOSURE Method for determining the distance between the working face of an anode and a reservoir of mercury beneath the anode in a substantially enclosed electrolytic cell has a value established for the position of the working face of the anode in the cell on an external scale means and another value established for the surface of the mercury reservoir in the cell on the external scale means. The depth of the mercury reservoir can also be determined. A measuring device in an electrolytic cell has a tube attached to a cage on an anode near an opening in the anode. The cage forms a chamber above the opening in the anode and the other end of the tube is connected with an opening in the cover of the electrolytic cell. A float is movably disposed between the chamber and the mercury reservoir. The float fits into the chamber and preferably has a height equal to the height of the chamber above the working face of the anode. The float has a rod attached which extends through the tube to give readings on a scale means located outside the electrolytic cell.

FIELD OF THE INVENTION This invention relates to devices and methods for performing measurements in operating electrolytic cells by an operator outside the cells. In greater detail this invention concerns instruments capable of being used to measure the distance from a working face of an anode to a mercury reservoir in an electrolytic cell and the depth of the mercury reservoir in the electrolytic cell.

DESCRIPTION OF THE PRIOR ART A recent development in the chlorine-caustic industry is the use of dimensionally stable anodes. The anodes, as their name implies, have the advantageous property of conducting current at relatively low chlorine overvoltages while themselves exhibiting great resistance to the corrosive environment present in the chlorine-caustic cells. The properties of these anodes afford significant advantages enabling their utilization in mercury-type cells.

in a mercury-type cell using dimensionally stable anodes in the electrolysis of solutions for the production of chlorine and the like, one of the more important variables is the distance between the working face of the anode and the surface of the mercury in the cell (hereinafter sometimes referred to as the operating distance). The operating distance is important because if the distance is too small, severe short circuits in the system can develop, and if the distance is too large, there is an increased voltage drop dissipating power in the electrolytic process.

No methods or devices are currently known for determination by an electrolytic cell operator of the distance between the surface of a mercury reservoir and the working face of a dimensionally stable anode in an electrolytic cell or the depth of the mercury reservoir in the electrolytic cell. The electrolytic cell involved in this invention comprises a lower electrode having a substantially horizontal upper surface (a mercury layer), an upper electrode having a substantially horizontal lower surface, an electrode vessel having a lid above said upper electrode, means for adjustably suspending the upper electrode in said cell and means for operating the suspending means for vertically moving said upper electrode. Currently, when mercury-type cells are assembled for electrolysis, the working face of the anode is placed on the cell bottom and then removed from the cell bottom a given distance. The flow of mercury through the cell is started so as to form a reservoir of mercury continuously present in the cell with relative vertical adjustment of the working face of the anode for optimum operating conditions. As can be expected the adjustment is only as effective as the skill of the operator since the operator has no precise parameters for the operating distance. It is desirable to be able to measure the operating distance between the working face of an anode and the surface of a mercury reservoir for a given anode setting in an electrolytic cell so the operating distance is a known number and can be checked by subsequent measurement. 'It is further desirable to know the operating distance for a given anode setting as changes in the distance between the surface of the mercury in the cell and the working face of the anode can occur independently of changes in the anode setting due to changes in conditions in the mercury-type cells. One of the possible changes in an operating cell is the development of mercury butter, a mixture of mercury, sodium and iron. The mercury butter can accumulate in the cell raising the mercury level in the cell and changing the operating conditions of the cell. Unexpected developments and emergencies, such as mercury butter build-ups causing short circuits, can result in the operator making quick movement in the vertical position of the anode and losing the relative vertical position of the anode in the cell. The foregoing are representative of the many developments during the operation of mercury-type cells which make it desirable to be able to measure the operating distance between the surface of the mercury and the working face of the anode and the depth of the mercury reservoir in the electrolytic cell.

SUMMARY OF THE INVENTION It is the principal object of this invention to provide measuring means for mercury-type electrolytic cells enabling a determination of the operating distance between the working face of an anode and the surface of a body of mercury in the electrolytic cell and the depth of the mercury reservoir in the electrolytic cell without any interruption or any interference with the operation of the cell. These determinations may be made by an operator through the use of the measuring devices disclosed in this invention.

It is a further object of this invention to provide float means sensitive to a change in the level of a body of mercury in an electrolytic cell due to changing conditions during operation of the electrolytic cell.

Other objects and advantages of the invention herein disclosed will be apparent to those skilled in the art from a reading of the following specification, the appended claims and by reference to the attached drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a partially cutaway section through a mercury-type electrolytic cell having a dimensionally stable anode which has connected therewith a measuring device having a cage attached to the anode and a tube which extends outside the cell connected to the cage and a float with an attached rod partially held within the tube and the rod actuating a scale means positioned outside of the electrolytic cell.

FIG. 2 shows an alternative scale and pointer combination which can be employed with the measuring device of the present invention.

FIG. 3A shows a partially cutway top view and FIG. 3B shows a partially cutaway section along line B-B in FIG. 3A of another embodiment of the invention in which the chamber above the anode structure has a different configuration and FIG. 3C shows an isometric view of this component.

FIG. 4- shows another embodiment of a float capable of being used in this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention presents a method and associated apparatus for determining the distance between the working face of an anode having an opening therein and a reservoir of mercury beneath the anode and the depth of the mercury reservoir in a substantially enclosed electrolytic cell where a tube or sleeve runs between an opening in the cover of the cell and is connected to the anode at a point near the opening in the anode defining a path in the cell with the portion of the tube adjacent the anode forming a chamber over the opening in the anode. The tube can also run between the opening in the cover of the cell and a cage positioned over the opening in the anode with the cage forming a chamber over the opening in the anode. Between the chamber and the mercury reservoir is movably positioned a float capable of fitting into the chamber and the float preferably being of height equal to the height of the chamber above the working face of the anode. The float has a rod attached thereto which extends through the tube and outside the cell to give readings on a scale means mounted on the cover of the cell. The distance between the Working face of an anode and a reservoir of mercury in the electrolytic cell beneath the anode is determined by positioning the float so it is in contact with the top of the cage or the top of the portion of the tube forming the chamber giving a reading on the scale means and then allowing the float to ride upon the mercury reservoir in the cell giving another reading on the scale means. The depth of the mercury reservoir in the electrolytic cell can be determined by manually depressing the float-rod combination until it rests upon the mercury cathode support (cell bottom 13), giving another reading on the scale means.

Referring now to FIG. 1 there is shown a partially cutaway section through a mercury-type electrolytic cell having a dimensionally stable anode 10 shown partially cut away with working face 11 receiving power input from a source (not shown) through appropriate lead-ins (not shown) and conductor bars (also not shown). The electrolytic cell has cell bottom 13, cell cover 12 and walls (not shown) forming a substantially enclosed cell except for opening 15. A mercury reservoir 14 of a given height is in the bottom of the cell forming the cathode of the cell. The mesh anode 10 has a circular opening located at, and of diameter equal to, the distance between the two mesh strands labeled 16. Fastened onto anode 10 is a hollow, cylindrical coupling 17 shown partially cut away which in turn is capped by a plug or bushing 18 also shown partially cut away which is threadably connected to coupling 17 with opening 32 receiving rod 23 therethrough. Hollow cylindrical tube or sleeve 19 is connected on top of plug 18 and is sealed by seal 20 to cover 12. Plug 18, coupling 17 and anode 10 enclose a chamber 22 of height preferably equal to the height of float 21. If the height of chamber 22 differs from the height of float 21 then the differences must be considered in the determination of the operating distance between the working face 11 of anode 10 and the mercury reservoir 14. Float 21 is constructed so it rides on mercury reservoir 14 and has attached thereto rod 23. The float-rod combination is capable of being movably positioned between the chamber 22 adjacent plug 18 and the surface of the mercury reservoir 14. Rod 23 extends through chamber 22, the opening 32 in plug 18, hollow tube or sleeve 19 and outside the cell cover 12 at opening 15 coming in contact with marker 24 which is pivoted on pivot 25 on scale 26. The float-rod combination can be manually raised from its position shown in FIG. 1 riding on the mercury reservoir 14 which changes the position of pointer 24 on scale 26. Scale 26 is fastened to tube 19 by connectors 28.

When rod 23 is manually raised so float 21 is in contact with the bottom of plug 18 in chamber 22, the marker is so positioned that it indicates a zero or known calibration mark. At this position the bottom of float 21 is preferably at the same level as the working face 11 of anode 10 since the height of float 21 is preferably equal to the height of cavity 22 which is also the distance between the bottom of plug 18 and working face 11 of anode 10. While this is a preferred embodiment it is to be emphasized that so long as the height of the float 21 and the height of chamber 22 are known values so that the difference between these heights can be used in a calculation, the operating distance between the working face 11 of anode 10 and mercury reservoir 14 can be determined in a simple calculation. When rod 23 is released it moves down tube 19 as float 21 moves down from cavity 22 into contact with mercury reservoir 14. This results in pointer, 24 following rod 23 to a new reading on scale 26 giving the distance between the working face 11 of anode 10 and the surface of mercury reservoir 14. Where this distance varies from the desired distance between the working face 11 of anode 10 and mercury reservoir 14, the distance is changed by moving anode 10 to a new setting giving the.

desired operating distance.

This device allows an operator to take rapid measurements of the operating distance during electrolytic operations by initially determining a reference point when the float 21 is in contact with plug 18 to be used as a reference for subsequent readings when the float is riding on the mercury reservoir or establishing a zero point by withdrawing rod 23 so the top of float 21 is in contact with plug 18. Then the operator allows float 21 to return to riding on mercury reservoir 14. Where the distance measured varies from that desired, the operator makes an adjustment of the position of anode 10 in the electrolytic cell. Such adjustment requires the operator to establish a now reference point for taking subsequent readings when the float 21 is in contact with plug 18.

Tube 19 is so arranged that there is a minimum exposure of personnel to the electrolytic reaction. It is preferable that tube 19, coupling 17 and plug 18 be made of a valve metal such as titanium and tantalum or an alloy of a valve metal, although various metals and alloys can be used if properly coated for corrosion resistance. The cell cover can be rubber or steel with a mbber lining on the side exposed to electrolytic reaction, or any commercially available corrosion resistant cell cover, and the construction of the scale is not critical and can be stamped out of steel. The float can be a hollow plastic container or a hollow metal container with a polymeric coating covering the metal to give corrosion resistance, with fluoro' carbon and acrylic polymers being preferred. Especially preferred polymers are polytetrafluoroethylene and methyl methacrylate trade products sold under the names Teflon and Lucite. The float and the rod are made so that their weight is greater than the weight of an equal volume of brine but less than the weight of an equal volume of mercury. This can be adjusted by adding or removing suitable weights such as lead balls to the float container. In this way the float willride on top of a mercury reservoir but will sink in an aqueous medium. This feature is important in mercury-type electrolytic cells as a brine layer is present on top of the flowing mercury cathode and the float must sink in the aqueous brine layer but float on the mercury layer in order to give an accurate reading of the distance between the working face of the anode and the mercury layer. The bottom surface of the float 21 riding on the mercury reservoir 14 is preferably large in size compared to the size of the upper surface of the float so that no depression of the float in the mercury occurs. FIG. 4 shows another configuration for the float 21 in which the bottom has a large surface area with the sides sloping toward the rod 23, and grooves 29 on the bottom of the float to prevent formation of a vacuum under the float due to the flowing mercury. Also the grooves prevent the float from sticking to the cell bottom when it is submerged by manual force in the mercury layer. The rod is constructed of rigid material (preferably a valve metal such as titanium or tantalum) so that accurate readings are given on scale 26 of the position of the float. While the embodiment of the dimensionally stable anode shown in the drawings is of mesh configuration, any other type of anode such as perforated corrugated or solid sheets, or rods may be used provided at least one suitable opening is provided to permit passage of the float through the anode into the chamber located above the anode. The dimensionally stable anode comprises an electrically conductive surface supported by a noble or valve metal. The conductive surface coating may be any material which is chemically inert to the electrolyte as well as resistant to the corrosive conditions of the cell such as platinum group metals, alloys of platinum group metals, platinum group oxides, mixtures of paltinum group oxides, mixtures of paltinum group oxides and alloys which are mixtures of platinum group metal oxides with platinum group metals. Valve metal includes filmforming metals such as titanium, tantalum, zirconium, niobium and the like.

One further manipulation of float 21 is manual depression of the float into the mercury layer until the float rests on the mercury cathode support (cell bottom 13) which gives another reading on scale 26 for the depth of the mercury layer in the electrolytic cell.

FIG. 2 shows another arrangement of the scale 26' which is mounted on cover 12 adjacent opening 15 in cover 12. Marker 24 on rod 23 poins to values on scale 26.

FIGS. 3A and 3B show another embodiment of the instant invention in which a cage 27 is used to define a chamber 22 above an opening in anode 10. FIG. 3B is a partial side view of the electrolytic cell cut away along line B-B in FIG. 3A which is a partial top view of the cell. Again the dimensionally stable anode shown partially cut away with working face 11 receives power input from a source (not shown) through appropriate lead-ins (not shown) and conductors bars (also not shown). The electrolytic cell has cell bottom 13, cell cover (not shown) and walls (not shown) forming a substantially enclosed cell except for an opening in the cell cover enabling tube 19 to open outside the cell. A mercury reservoir 14 of given depth is supported on the mercury cathode support 13, forming the cathode of the cell. The anode 10 has a circular opening located at, and of diameter equal to, the distance between the two mesh strands labeled 16. A portion 27' of the cage is horizontal and forms the top of the cage which with four strands 27" form a chamber extending from the top of cage 27' to the working face 11 of anode 10 where the strands 27" are joined with the anode 10. The strands 27" of the cage are fastened to anode 10 either by mechanical means or by welding. Hollow cylindrical tube 19 is connected to the top 27' of the cage 27 and is sealed by seal 20 to the cover (as shown in FIG. 1). The top 27 and strands 27" of the cage enclose a chamber 22 of height preferably equal to the height of float 21. Float 21 is constructed so it can ride on mercury reservoir 14 and has attached rod 23 which extends through the chamber 22, through an opening in the top 27' of the cage 27, and through tube 19 to give a reading on scale means outside the cell mounted on the cover. The float-rod combination is capable of being movably positioned between the chamber 22 and the surface of mercury reservoir 14. The float rod combination can be manually raised from its position shown in FIG. 3B riding on the mercury reservoir 14 which changes the position of a pointer on the scale means on the cover.

When rod 23 is manually raised so float 21 is in contact with the top 27' of the cage 27 in chamber 22, the marker is so positioned that it indicates a zero or known calibration mark. At this position the bottom of float 21 is in a known position relative to the working face 11 of anode 10 since the height of float 21 and the height of cavity 22 are known values. Preferably the height of float 21 and the height of cavity 22 are equal to each other so the bottom of float 21 will be even with the work ing face 11 of anode 10 when float 21 is raised into chamber 22. When rod 23 is released it moves down channel 19 as float 21 moves down from chamber 22 into contact with mercury reservoir 14. This results in rod 23 moving a marker on a scale located outside the electrolytic cell to a new reading given the distance between the working face 11 of anode 10 (the initial or zero reading on the scale) and the surface of the mercury reservoir 14. Where this distance varies from the desired distance between the working face 11 of anode 10 and mercury reservoir 14, the distance is changed by moving anode 10 to a new setting giving the desired operating distance.

While preferred embodiments of this invention have been disclosed herein, those skilled in the art will appreciate that changes and modifications may be made therein Without departing from the spirit and scope of this invention as defined in the appended claims.

What is claimed is:

1. A method of determining the distance between the working face of an anode having an opening therein and a reservoir of mercury on a mercury cathode support beneath the anode in a substantially enclosed electrolytic cell, where a tube in the electrolytic cell has one end attached to the anode in the region of the opening in the anode with the portion of the tube adjacent the anode being formed into a chamber of known height over the opening in the anode and the other end of the tube opens outside the cover of the cell, a float of known height being movably disposed in the cell between the chamber and the mercury reservoir, the float having a rod attached thereto which extends through the chamber and the tube to give a reading on a scale positioned outside the cell, said method having the steps of (a) positioning the float so it is in contact with the chamber portion of the tube which gives a reading I on the scale, and

(b) releasing the float so it rides on the mercury reservoir in the cell which gives another reading on the scale.

2. The method of claim 1 where the anode is adjustably positioned in the cell and there is practiced the subsequent step of adjusting the position of the anode.

3. The method of claim 1 where the movement of the float is performed with a float of height equal to the height of the chamber above the working face of the anode.

4. The method of claim 1 where the movement of the float is performed in a cell where the tube is welded to a structure forming a chamber of known height above the working face of the anode.

5. The method of claim 1 in which is practiced the additional step of depressing the float so it rests upon the mercury cathode support which gives another reading on. the scale.

6. A method for determining the distance between the Working face of an anode with an opening therein and a reservoir of mercury beneath the anode in a substantially enclosed electrolytic cell, comprising the steps of (a) positioning a tube in the electrolytic cell with one end of the tube attached to the anode in the region of the opening in the anode with the portion of the tube adjacent the anode forming a chamber of known height over the opening in the anode and the other end of the tube opening outside the cover of the cell, '(b) movably positioning a float in the cell beneath the opening in the anode, the float having a known height, and the float having a connected stem extending through the chamber and the tube to give readings on a scale positioned outside the cell,

(c) withdrawing the float so it is in contact with the chamber portion of the tube which gives a reading on the scale, and

(d) releasing the float so it rides on the mercury reservoir in the cell which gives another reading on the scale.

7. The method of claim 6 in which is practiced the additional step of depressing the float so it rests upon the mercury cathode support which gives another reading on the scale.

8. The method of claim 6 where the anode is adjustably positioned in the cell and there is practiced the subsequent step of adjusting the position of the anode.

9. The method of claim 6 where the movement of the float is performed with a float of height equal to the height of the chamber above the working face of the anode.

10. In an electrolytic cell having an opening in the cover, an anode with at least one opening in the working face positioned in the cell and a mercury cathode reservoir resting on a mercury cathode support, the improvement enabling determination of the distance between the working face of the anode and the mercury reservoir and the depth of the mercury reservoir comprising (a) a tube connected to the opening in the cover of the cell and attached to the anode in the region of the opening in the anode with the portion of the tube adjacent the anode forming a chamber over the opening in the anode of known height above the working face of the anode,

(b) a float of known height having a rod attached thereto, the float being movably disposed between the mercury reservoir and the chamber over the opening in the anode with the rod extending through the tube and outside the cover of the cell, and

(c) scale means located on the cover outside the cell so that the relative vertical position of the float-rod combination in the cell is indicated on the scale means.

11. The electrolytic cell of claim 10 where the scale means is mounted on the cover and the rod is in contact with a pivoted pointer means registering a reading on the scale means.

12. The electrolytic cell of claim 10 where the scale means is mounted adjacent the opening in the cover and the rod has a pointer thereon which points to a reading on the scale.

13. The electrolytic cell of claim 10 where the anode is capable of vertical displacement in the cell.

14. The electrolytic cell of claim .10 where the height of the float is equal to the height of the chamber above the working face of the anode.

15. The electrolytic cell of claim 10 in which the tube is welded to a structure forming a chamber over the opening in the anode of known height above the working face of the anode and the structure is welded to the anode.

16. The electrolytic cell of claim 15 wherein the structure comprises a cylindrical plug with a hole centered in the plug and the plug is threaded around its circumference to fit into a hollow, cylindrical coupling threaded inside to receive the plug.

17. The electrolytic cell of claim 15 where the structure comprises a cage having a flat top with strands leading from the top to the anode to generally define a chamber over the anode.

References Cited UNITED STATES PATENTS 3,480,526 11/1969 Duclaux 204-225 X 3,567,615 3/1971 Nicolaisen 204-219 FOREIGN PATENTS 297,826 4/ 1954 Switzerland 204-250 JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant 'Examiner U.S. Cl. X.R. 204219, 225, 250'