US4138295A
Expired / Lapsed
US
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Process and apparatus for downward recycling of the electrolyte in diaphragm cells
Assignee: Diamond Shamrock Technologies SA
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Filing: 1978-02-17
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Granted: 1979-02-06
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Expires: 1998-02-17
Abstract
Abstract An alkali chlorine diaphragm cell such as is constructed in a conventional manner whereby evolved gaseous chlorine rises in the pool of alkali metal chloride solution is provided with recycling means to recycle the solution from an upper level of the solution to a predetermined lower level of the solution adjacent the cell bottom, a plurality of spaced conduits are preferably provided for this purpose. The downward recirculation of the electrolyte through these conduits is induced by the upward movement of the electrolyte caused by the gaseous chlorine rising in the electrolyte outside the conduits. These conduits advantageously are located at or near anode surfaces and prevent or restrain lateral movement of recycled electrolyte until the recycled electrolyte reaches such lower level usually adjacent the bottom of the anolyte chamber. The circulation is preferably conducted as a plurality of spaced downward streams, each stream being between a pair of cathode elements and discharging into the space between an anode element and at least one of the cathode elements of the pair. This invention is concerned with an improved electrolytic cell for electrolysis of aqueous alkali metal halide solutions to produce the corresponding halogen and an improved method for operating cells used in such electrolysis. Alkaline compounds, notably sodium hydroxide, are produced in conjunction with chlorine production.
Inventors
- 👤 Vittorio DeNora
- 👤 Oronzio De Nora
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:59
CPC Classifications
C; C25; C25B; C25B11/00; C25B11/02; C25B9/00; C25B9/13; C25B9/17; C25B9/19
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
115 words
In the process of producing chlorine by electrolyzing aqueous alkali metal chloride solution in an electrolytic cell between a hollow anode located between a pair of cathode surfaces and open at its top and lower ends, the improvement which comprises generating between said cathode surfaces and said anode, during said electrolysis, upward circulation of solution toward the top of the solution in both the hollow interior of the anode and in the spaces between the exterior of the anode and the adjacent cathode surfaces, and downward movement of the solution from an upper level of said solution to a lower level thereof through electrically non-conducting passages substantially free of gaseous halogen within said hollow anode.
Claim 2
Dependent Claim
115 words
In the process of producing chlorine by electrolyzing aqueous alkali metal chloride solution in an electrolytic cell between a hollow anode located between a pair of cathode surfaces and open at its top and lower ends, the improvement which comprises generating between said cathode surfaces and said anode, during said electrolysis, upward circulation of solution toward the top of the solution in both the hollow interior of the anode and in the spaces between the exterior of the anode and the adjacent cathode surfaces, and downward movement of the solution from an upper level of said solution to a lower level thereof through electrically non-conducting passages substantially free of gaseous halogen within said hollow anode.
Claim 3
Dependent Claim
34 words
The process of claim 1 wherein the downward flow is in a passage between said pair of anode surfaces which are not involved with the upward flow of chlorine bubbles generated at the anode.
Claim 4
Dependent Claim
149 words
A process of electrolyzing a pool of an aqueous solution of alkali metal halide in an electrolytic cell to liberate gaseous halogen within said cell and form alkali metal hydroxide and hydrogen, which comprises conducting said electrolysis between a plurality of hollow anodes, open at their tops and lower ends, which have conductive surfaces facing a plurality of cathode surfaces, immersed in said pool and separated by a diaphragm, whereby to evolve gaseous halogen which rises in the solution in the interelectrodic gap between the anodes and cathodes and in the hollow interior of said anodes creating upward movement of the solution toward the top of said pool, flowing solution downward within said cell through electrically non-conducting passages substantially free of gaseous halogens in the interior of the anodes from an upper level to a lower level of said pool, and returning the downward flowing solution to said pool.
Claim 5
Dependent Claim
149 words
A process of electrolyzing a pool of an aqueous solution of alkali metal halide in an electrolytic cell to liberate gaseous halogen within said cell and form alkali metal hydroxide and hydrogen, which comprises conducting said electrolysis between a plurality of hollow anodes, open at their tops and lower ends, which have conductive surfaces facing a plurality of cathode surfaces, immersed in said pool and separated by a diaphragm, whereby to evolve gaseous halogen which rises in the solution in the interelectrodic gap between the anodes and cathodes and in the hollow interior of said anodes creating upward movement of the solution toward the top of said pool, flowing solution downward within said cell through electrically non-conducting passages substantially free of gaseous halogens in the interior of the anodes from an upper level to a lower level of said pool, and returning the downward flowing solution to said pool.
Claim 6
Dependent Claim
31 words
The process of claim 3 wherein the halide is a chloride and the downward flow is conducted in a plurality of spaced passages, each passage being inside a different anode surface.
Claim 7
Dependent Claim
32 words
The process of claim 4 wherein the downward flow is directly to a depth in the solution at least 50 percent of the depth of immersion of the anode in said solution.
Claim 8
Dependent Claim
36 words
The process of claim 4 wherein the chloride permeability of the diaphragm is low enough to hold alkali metal chloride concentration in the alkali metal hydroxide formed below one percent by weight on the anhydrous basis.
Claim 9
Dependent Claim
26 words
The process of claim 3 wherein the electrolyte is caused to flow downwardly through a passage bonded by at least a pair of impervious non-conducting surfaces.
Claim 10
Dependent Claim
15 words
The process of claim 7 wherein lateral flow of the downward flowing solution is restrained.
Claim 11
Dependent Claim
13 words
The process of claim 3 wherein the diaphragm includes a cation exchange material.
Claim 12
Dependent Claim
21 words
The process of claim 3 wherein there are a plurality of spaced downwardly flowing passages in the interior of said anodes.
Claim 13
Dependent Claim
121 words
An electrolytic alkali halogen cell which comprises a plurality of spaced hollow anode elements extending in parallel relationship from a common anodic conductor, a plurality of foraminous cathode elements interleaved between anode elements, a diaphragm between cathode and anode, means to impose an electric potential between anode and cathode, means to maintain a pool of aqueous alkali metal chloride brine in the cell whereby upon electrolysis of the brine, chlorine gas is evolved at the anode and rises in the brine between pairs of cathode elements and causes upward brine movement toward the top of the pool, and means inside said hollow anodes for positively recycling brine downward from an upper level of the pool directly to a lower level thereof.
Claim 14
Dependent Claim
121 words
An electrolytic alkali halogen cell which comprises a plurality of spaced hollow anode elements extending in parallel relationship from a common anodic conductor, a plurality of foraminous cathode elements interleaved between anode elements, a diaphragm between cathode and anode, means to impose an electric potential between anode and cathode, means to maintain a pool of aqueous alkali metal chloride brine in the cell whereby upon electrolysis of the brine, chlorine gas is evolved at the anode and rises in the brine between pairs of cathode elements and causes upward brine movement toward the top of the pool, and means inside said hollow anodes for positively recycling brine downward from an upper level of the pool directly to a lower level thereof.
Claim 15
Dependent Claim
51 words
The cell of claim 11 wherein the recycling means are vertical tubular elements open at the top and bottom and extending from a level close to the top of the pool of aqueous alkali metal chloride solution to a level close to the bottom of said pool inside said hollow anodes.
Claim 16
Dependent Claim
29 words
The cell of claim 12 wherein the recycling means extends vertically for a depth which is not less than 50 percent of the depth of immersion of the anodes.
Claim 17
Dependent Claim
43 words
The cell of claim 12 wherein the total cross section area of the recycling means is comprised between the range of 20% to 60% of the total cross section area of the pool of aqueous alkali metal chloride solution contained in the cell.
Claim 18
Dependent Claim
57 words
The cell of claim 11 wherein the recycling means is at least one vertical chamber defined by at least two parallel vertical substantially impervious baffles extending vertically from a level close to the top of the pool of aqueous alkali metal chloride solution to a level close to the bottom of said pool inside said hollow anodes.
Claim 19
Dependent Claim
22 words
The cell of claim 15 having a plurality of said anode surfaces each of which is associated with an individual recycling means.
Claim 20
Dependent Claim
26 words
The cell of claim 11 wherein there are a plurality of spaced recycling means disposed between a pair of cathode surfaces and inside said hollow anodes.
Claim 21
Dependent Claim
28 words
The cell of claim 11 wherein there are a plurality of spaced recycling means, each being disposed between a pair of anode elements and inside said hollow anodes.
Claim 22
Dependent Claim
102 words
An electrolytic alkali chlorine cell which comprises an anolyte chamber separated from a catholyte chamber by a diaphragm, said anolyte chamber being adapted to contain a pool of aqueous alkali metal chloride solution, hollow anode elements disposed below the top of the pool and opposite cathodic surfaces whereby as gaseous chlorine is evolved upon electrolysis at a surface of said anode elements, the chlorine rises and tends to cause upward movement of the solution, and recycling means inside said hollow anodes having a surface which is less electroconductive than said anode surface to convey solution downward toward the bottom of said pool.
Claim 23
Dependent Claim
102 words
An electrolytic alkali chlorine cell which comprises an anolyte chamber separated from a catholyte chamber by a diaphragm, said anolyte chamber being adapted to contain a pool of aqueous alkali metal chloride solution, hollow anode elements disposed below the top of the pool and opposite cathodic surfaces whereby as gaseous chlorine is evolved upon electrolysis at a surface of said anode elements, the chlorine rises and tends to cause upward movement of the solution, and recycling means inside said hollow anodes having a surface which is less electroconductive than said anode surface to convey solution downward toward the bottom of said pool.
Claim 24
Dependent Claim
135 words
An electrolytic alkali chlorine cell which comprises a cell having anolyte and catholyte chambers, hollow anode elements in substantially vertical spaced relation in the anolyte chamber, foraminous cathode elements bounding the catholyte chamber and a diaphragm separating said chambers, means for feeding aqueous alkali metal chloride electrolyte into the anolyte chamber, means to impose an electric potential between cathode and anode elements whereby upon electrolysis of the aqueous chloride, gaseous chlorine is evolved on surfaces of the anode elements and rises along the hollow anode elements in the electrolyte tending to cause upward electrolyte movement toward the top of the anode surface, and recycling means inside said hollow anode elements restraining lateral movement of the recycle electrolyte adjacent the anode surfaces to recycle electrolyte from an upper level thereof downward to a lower level thereof.
Claim 25
Dependent Claim
135 words
An electrolytic alkali chlorine cell which comprises a cell having anolyte and catholyte chambers, hollow anode elements in substantially vertical spaced relation in the anolyte chamber, foraminous cathode elements bounding the catholyte chamber and a diaphragm separating said chambers, means for feeding aqueous alkali metal chloride electrolyte into the anolyte chamber, means to impose an electric potential between cathode and anode elements whereby upon electrolysis of the aqueous chloride, gaseous chlorine is evolved on surfaces of the anode elements and rises along the hollow anode elements in the electrolyte tending to cause upward electrolyte movement toward the top of the anode surface, and recycling means inside said hollow anode elements restraining lateral movement of the recycle electrolyte adjacent the anode surfaces to recycle electrolyte from an upper level thereof downward to a lower level thereof.
Claim 26
Dependent Claim
13 words
The cell of claim 20 wherein the recycling means is a substantial non-conductor.
Claim 27
Dependent Claim
31 words
The cell of claim 20 wherein said recycling means conveys electrolyte from a level adjacent the upper portion of said anode surfaces to a level adjacent the bottom of said surfaces.
Claim 28
Dependent Claim
54 words
The cell of claim 20 wherein the anode surfaces are horizontally aligned between the cathode elements and the recycling means is a conduit inside said hollow anode elements for recycling electrolyte which extends downward from an upper level of the electrolyte to at least a level adjacent the lower portion of the anode surfaces.
Claim 29
Dependent Claim
16 words
The cell of claim 20 wherein the recycling means is between a pair of anode surfaces.
Claim 30
Dependent Claim
24 words
The cell of claim 20 wherein said cell is provided with a plurality of individual recycling means each being inside separate individual anode elements.
Claim 31
Dependent Claim
27 words
The cell of claim 20 wherein said cell is provided with pluralities of pairs of said anode elements with recycling means between said pairs of anode elements.
Claim 32
Dependent Claim
111 words
An alkali chlorine cell comprising a plurality of cathode fingers, a plurality of spaced hollow anode elements between said fingers, a diaphragm between cathode fingers and the anode elements dividing the cell into an anolyte chamber containing the anode elements and catholyte chambers behind the cathode fingers whereby when an electric potential is applied between the anode elements and the cathode fingers with an aqueous alkali metal chloride electrolyte in the anolyte chamber, chlorine gas is formed and rises along the anodes in the electrolyte creating upward movement of electrolyte, and means inside said hollow anode elements and between said fingers to direct downward flow of electrolyte in the anolyte chamber.
Claim 33
Dependent Claim
111 words
An alkali chlorine cell comprising a plurality of cathode fingers, a plurality of spaced hollow anode elements between said fingers, a diaphragm between cathode fingers and the anode elements dividing the cell into an anolyte chamber containing the anode elements and catholyte chambers behind the cathode fingers whereby when an electric potential is applied between the anode elements and the cathode fingers with an aqueous alkali metal chloride electrolyte in the anolyte chamber, chlorine gas is formed and rises along the anodes in the electrolyte creating upward movement of electrolyte, and means inside said hollow anode elements and between said fingers to direct downward flow of electrolyte in the anolyte chamber.
Claim 34
Dependent Claim
20 words
The cell of claim 27 wherein said means has a substantially non-conductive external surface exposed to the alkali metal chlorine.
Claim 35
Dependent Claim
21 words
The cell of claim 27 wherein the diaphragm is low enough in permeability so that flow of anolyte therethrough is impeded.
Claim 36
Dependent Claim
29 words
The cell of claim 27 wherein the diaphragm is sufficiently impermeable to ensure production of sodium hydroxide containing less than 0.5 percent chloride by weight on an anhydrous basis.
Claim 37
Dependent Claim
110 words
An alkali chlorine cell having a foraminous cathode and a hollow anode, a diaphragm between the anode and cathode dividing the cell into an anolyte chamber and a catholyte chamber whereby when an electric potential is imposed between anode and cathode with aqueous alkali metal chlorine electrolyte in the anolyte chamber, gaseous chlorine is evolved at the anode surface and rises in electrolyte toward the top of the cell creating upward flow of electrolyte, and means inside the hollow anode to convey electrolyte from an upper level of the cell downward to a lower level in said cell, said means restraining lateral flow of said electrolyte during said downward flow.
Claim 38
Dependent Claim
110 words
An alkali chlorine cell having a foraminous cathode and a hollow anode, a diaphragm between the anode and cathode dividing the cell into an anolyte chamber and a catholyte chamber whereby when an electric potential is imposed between anode and cathode with aqueous alkali metal chlorine electrolyte in the anolyte chamber, gaseous chlorine is evolved at the anode surface and rises in electrolyte toward the top of the cell creating upward flow of electrolyte, and means inside the hollow anode to convey electrolyte from an upper level of the cell downward to a lower level in said cell, said means restraining lateral flow of said electrolyte during said downward flow.
Claim 39
Dependent Claim
31 words
The cell of claim 31 wherein the means is adapted to convey electrolyte downward to a depth at least 50 percent of the total depth of anode immersion in the electrolyte.
Claim 40
Dependent Claim
21 words
The cell of claim 31 wherein the surface exposed to electrolyte of the means to convey electrolyte downward is a non-conductor.
Claim 41
Dependent Claim
104 words
An electrolytic alkali chlorine cell which comprises an anode disposed between a pair of cathode surfaces, said anode presenting a pair of spaced perforated surfaces opposite said pair of cathode surfaces with an interior space therebetween so that electrolyte between the anode and cathode has access to the interior of the anode between said spaced anode surfaces, said perforate anode surfaces being adapted to divert evolved chlorine to said interior space and at least a conduit between said pair of cathode surfaces capable of conveying electrolyte from an upper level to a lower level thereof and of restraining lateral electrolyte flow during said conveyance.
Claim 42
Dependent Claim
104 words
An electrolytic alkali chlorine cell which comprises an anode disposed between a pair of cathode surfaces, said anode presenting a pair of spaced perforated surfaces opposite said pair of cathode surfaces with an interior space therebetween so that electrolyte between the anode and cathode has access to the interior of the anode between said spaced anode surfaces, said perforate anode surfaces being adapted to divert evolved chlorine to said interior space and at least a conduit between said pair of cathode surfaces capable of conveying electrolyte from an upper level to a lower level thereof and of restraining lateral electrolyte flow during said conveyance.
Claim 43
Dependent Claim
176 words
An alkali chlorine cell comprising: a plurality of spaced upright cathode fingers, spaced pairs of upright perforate anode surfaces, extending upward along but spaced from the cathode fingers each said spaced pair of anode and surfaces being between a pair of cathode fingers and providing an interior space between the spaced pair of anode surfaces, means to cause evolved chlorine to rise in the interior spaces whereby to generate upward electrolyte movement, means to maintain the level of electrolyte in the cell above the level of the fingers, the space between the fingers being open to the body of electrolyte above said fingers and chlorine rising in said interior spaces is open to rise through said body, and electrolyte conduits between each pair of adjacent cathode fingers providing a downward path unobstructed by rising chlorine and extending from an upper to a lower level of the cell, said conduits being open to electrolyte flow to both said upper and lower levels of the cell the lower outlet thereof being adjacent the lower end of said finers.
Claim 44
Dependent Claim
176 words
An alkali chlorine cell comprising: a plurality of spaced upright cathode fingers, spaced pairs of upright perforate anode surfaces, extending upward along but spaced from the cathode fingers each said spaced pair of anode and surfaces being between a pair of cathode fingers and providing an interior space between the spaced pair of anode surfaces, means to cause evolved chlorine to rise in the interior spaces whereby to generate upward electrolyte movement, means to maintain the level of electrolyte in the cell above the level of the fingers, the space between the fingers being open to the body of electrolyte above said fingers and chlorine rising in said interior spaces is open to rise through said body, and electrolyte conduits between each pair of adjacent cathode fingers providing a downward path unobstructed by rising chlorine and extending from an upper to a lower level of the cell, said conduits being open to electrolyte flow to both said upper and lower levels of the cell the lower outlet thereof being adjacent the lower end of said finers.
Claim 45
Dependent Claim
25 words
The cell of claim 35 wherein the conduits extend down a distance at least 50 percent of the dept of anode immersion in the electrolyte.
Claim 46
Dependent Claim
37 words
The cell of claim 35 wherein the anode surfaces are provided with means to divert evolved chlorine to said interior spaces causing evolved chlorine to rise in the interior spaces between the spaced pairs of anode surfaces.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-05 | 1982-08-07 | 1983-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-05 | 1986-08-07 | 1987-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-05 | 1990-08-07 | 1991-02-06 | $7700.00 | Window Closed / Lapsed |