JPS582275B2 - Denkaihouhou Oyobi Denkaisou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Many industrial manufacturing processes are based on the electrolysis of aqueous salt solutions.

One important application is the electrolysis of sodium chloride brine to produce sodium hydroxide and chlorine.

In this electrolysis, as in other processes involving the electrolysis of aqueous salt solutions, one method is to use a porous separator to separate the anolyte and catholyte compartments of the cell.

The term ``diaphragm'' is used below for porous separators that allow the passage of electrolyte without significant changes in composition.

In this method, hydrogen and caustic soda are produced at the cathode located in the catholyte compartment of the electrolytic cell, while chlorine is produced at the anode located in the anolyte compartment.

Salt water passes through the diaphragm from the anolyte compartment to the catholyte compartment.

The cathode usually consists of iron mesh, while the anode consists of graphite or platinum coated titanium.

The septum is usually asbestos.

The diaphragm cell requires sufficient solution flow to prevent and ensure that back-diffusion of sodium hydroxide into the anolyte is minimized.

This is necessary to avoid chlorate in the anolyte and a reduction in current efficiency.

If minimal brine flow in the membrane is used to avoid chlorate formation, only about half of the sodium chloride will be converted.

The weakened anolyte must then be evaporated to concentrate the caustic soda and crystallize the salt.

Finally, the salt is filtered or centrifuged from the caustic soda solution.

It is common practice to purify the brine feed to the process to reduce the content of impurities that can clog the diaphragm.
It is also common to renew the diaphragm at regular intervals.

Attempts have been made to produce diaphragm electrolytic cells using permselective membranes instead of diaphragms.

This does not provide a solution to the main problem.

All membranes that provide reasonably high conductivity and chemical resistance undergo significant back-diffusion and electromigration of hydroxyl ions;
The rate increases with catholyte concentration and temperature.

The second type of electrolyzer for chlorine and caustic soda is
A mercury electrolyser, in which the electrolysis of salt water provides the production of sodium amalgam at the cathode and chlorine at the anode.

The amalgam reacts with water to give a salt-free solution of caustic soda and hydrogen.

This method does not require a diaphragm because the caustic soda solution is produced in a separate section or section of the apparatus from the aqueous salt solution and chlorine.

In one embodiment of a mercury electrolyzer, purified sodium chloride water is fed into a slightly inclined horizontal cell at the bottom of which cathodic mercury flows cocurrently with the brine.

Above the mercury and in the brine is a horizontal anode made of graphite or platinum, or titanium coated with a platinum group metal.

These anodes are suspended from the airtight cover of the cell.

Current is supplied to the anodes by rods suspended from and sealed in holes in these covers.

The salt water is localized within the cell by a mercury siphon at the end of the cell.

Typically, the concentration in the electrolytic cell is between 3 1 5 g/l and 2
7.5 g/l and the brine leaves the cell by overflow.

Typically, brine is supplied to the cell by a valve and rotameter.

After leaving the electrolyzer, the brine is dechlorinated and resaturated by the addition of HCI and a combination of vacuum and air stripping before returning to the electrolyzer to bring its pH to about 7.0.

Electricity is supplied to the mercury by a busbar connection to the bottom of the steel cell.

An anode rod, which projects above the cover and is usually vertically adjustable, is connected to the main busbar by a pigtail, clamp, soldered rod or similar metal device.

To stop the operation of each cell, a short circuit switch is usually provided to connect the anode busbar to the cathode busbar.

The cover, side walls, end box, seal, and sometimes most of the bottom of the cell are covered with a corrosion-resistant material, usually hard rubber.

Their life span before needing repair or replacement rarely exceeds five years, and is often much shorter.

This assembly of components is commonly referred to as a primary electrolytic cell.

The mercury flowing out of the primary electrolyzer, in addition to sodium,
It contains impurities such as calcium, magnesium and iron that were not completely removed during the pre-purification of the brine.

The mercury is washed with distilled water to remove the sodium as caustic soda.

This operation is carried out in contact with graphite and results in the production of a caustic soda solution, hydrogen gas and relatively sodium-free mercury which is pumped back into the in-resoto box of the primary electrolyzer.

Equipment for this purpose is usually called a secondary electrolytic cell or a dehydration cell.

In the practice of the invention, this is a horizontal tank with a graphite grid or a short column collapse with graphite packing.

If it is a cell, place it either next to or below the primary electrolytic cell.

If it is a column, it is usually placed at the discharge end of the primary electrolyzer, with a pump underneath the column and a long pipe for returning the mercury below the primary cell.

To understand the function of the mercury cathode in a mercury, chlorine-caustic electrolyzer, consider the electrolysis of a sodium chloride solution between a steel cathode and a graphite anode.

Chlorine is generated at the anode and hydrogen is generated at the cathode.
Meanwhile, in the latter simultaneously caustic soda is formed according to the following reaction: 2NaCl + 2H2 C) - 2NaOH + C 1
2 + H2 If the anolyte and catholyte are not separated, the following secondary reaction occurs: 2NaOH + C 12 = NaOC l + Na C
l +H2 03NaOCl=NaCl03+2NaC
IC (graphite) + 2NaOCl = 2NaCl + CO2Cl
2+H22HCl (explosion) Such an electrolytic cell is clearly useless for the purpose of producing caustic soda and chlorine.

On the other hand, in a mercury electrolyzer and using a mercury cathode, when the mercury is relatively pure, hydrogen will not be generated at the cathode in preference to the release of sodium, and the mercury will be released according to the equation below. Sodium amalgam results: 2NaCl-+2Na(Hg)+Cl2 The reason is that the hydrogen overpotential at the mercury surface is higher than the voltage required to precipitate sodium into such a surface.

Overvoltage is a voltage on the electrode that is higher than theoretically necessary to release gas onto the surface of the electrode.

If the mercury contains more than a few tenths of a percent of sodium or traces of magnesium, nickel or similarly low hydrogen overpotential metals, more or less hydrogen and caustic soda will form, rather than a sodium amalgam.

In such a case, current efficiency decreases, graphite consumption increases, and chlorine gas in the tank, i.e., chlorine in the uncondensed gas remaining after most of the chlorine is liquefied, will combine with hydrogen. Becomes explosive when mixed.

The opposite effect is desirable when producing caustic and hydrogen from amalgam.

When clean sodium amalgam is placed in a beaker and water or caustic is poured over it, little or no reaction occurs because the hydrogen does not readily escape from the mercury surface.

When a piece of graphite is partially immersed in mercury, hydrogen bubbles can be seen rising from the graphite very close to the mercury surface, the water or caustic becomes more alkaline and the amalgam is stripped of its sodium.

Thus, under operating conditions, the water splitting tank becomes a short-circuited cell with amalgam as the anode and graphite as the cathode.

This process typically provides about 50% pure concentrated caustic, compared to about 11% concentration with diaphragm cells.

However, mercury cycling, exposure of mercury surfaces to salt water,
and other problems inherent in this technology invariably force the design of large, expensive, complex equipment that occupies large buildings and leads to unavoidable mercury contamination from skimming operations and the like.

Moreover, mercury electrolysers are extremely sensitive to impurities in the sodium chloride solution, which can increase the deicing of the amalgam that occurs during electrolysis, resulting in a high and often explosive hydrogen content in the chlorine. Become.

The problem of mercury circulation is avoided by making the mercury in such a form that it is used as a membrane, one surface of which is the cathode in the chlorine undergoing electrolysis, and the other surface being in contact with the caustic soda solution. be able to.

In this way, the deposition of sodium in the amalgam occurs simultaneously with the deicing on the opposite side.

Attempts to accomplish this have always required designs in which the mercury is supported in a siphon-like, overlying groove, or on a porous or woven material, essentially a diaphragm.

When mercury is supported in a siphon, the long path that metallic sodium must travel through the mercury results in an excessive concentration of sodium at the cathode surface and the consequent evolution of hydrogen on the cathode surface and into the chlorine. ,
And whenever mercury is supported on a diaphragm, the net result is that air bubbles become trapped in the pores, thereby increasing the resistance.

Moreover, the deposition of metallic impurities, such as iron, in the pores leads to wetting of these impurities by mercury, with concomitant leakage and loss of mercury through the diaphragm.

U.S. patent for modification in mercury cathode electrolyzer No. 2,749,301.

A mercury cathode is supported on a porous membrane made of woven plastic or asbestos cloth.

Salt water flows over the anode surface and below the cathode.

In order to avoid clogging of the diaphragm with air bubbles, extremely large quantities of saline water must be pumped into the space between the anode and the diaphragm, which is thus uneconomical.

However, even at high flow rates, chlorine as well as hydrogen bubbles from the mercury layer on the diaphragm gradually become entangled into the diaphragm, reducing the efficiency of the process.

It is an object of the present invention to provide a new method and device for the electrolysis of alkali metal salt solutions.

It is also an object of the present invention to overcome some of the drawbacks existing in currently used electrolytic cells and methods.

These and other objects will become more fully apparent in the detailed description below.

The present invention relates to a method and apparatus for the electrolysis of aqueous solutions containing alkali metal ions, such as the electrolysis of sodium chloride solutions to produce chlorine, sodium hydroxide and hydrogen.

The alkali metal ions are present in solution together with the anions of mineral acids and/or hydroxyl ions and/or the anions of organic acids.

Examples of such aqueous solutions are sodium and potassium chlorides, bromides, salts, sulphites, phosphates, acetates and hydroxides.

In one embodiment of the invention, a composite membrane is used to separate the cathode product from the electrolyte.

This composite membrane is characterized by a membrane facing the anode, which is a solid polymer or resin, and a layer of metal permeable to alkali metals in intimate contact with the membrane.

The term membrane is used for materials that exhibit high ionic permeability and relatively low permeability to the anolyte.

In another aspect of the invention, the presence of a gas phase in the electrolyte adjacent to the composite membrane is provided at temperatures above atmospheric pressure under conditions in which normally occurring gaseous products liquefy or dissolve in the electrolyte. in the electrolyte in contact with the composite membrane by operating under pressure or with an anode covered by an electrolyte-permeable diaphragm or an anion-permeable membrane and with removal of the anodic product through the anode. Avoid the presence of gas phase.

In yet another aspect of the invention, electrolyzer modules consisting of an electrolysis chamber and a deicing chamber separated by a composite membrane are stacked to provide a distributed series flow of current from cell to cell while being electrically insulated. Conductive grooves, tubes or pipes allow liquid to flow from module to module in the electrolyzer.

A feature of this composite membrane is that in applications for electrolysis of aqueous alkaline salt solutions, alkali metal ions migrate from the aqueous solution into the metal layer through the membrane and then exit from the metal layer.

For the most advantageous use of the present invention, the electrical resistance to electrical migration of alkali metal ions within the membrane must be low, and the maximum unit capacity and minimum electrical energy requirements for composite membranes. It is clear that the transport capacity of the metal layer for the alkali metal must be high in order to provide the alkali metal.

Furthermore, in order to be able to release the alkali metal ions, which are to be conducted in the metal layer as alkali metal atoms or alkali metal ions with free electrons, directly from the polymer membrane into the metal layer, The composite membrane must be designed to provide direct interfacial contact between the polymeric membrane and the metal layer.

A preferred metal layer is liquid mercury which forms a liquid amalgam with alkali metals.

This property is, of course, known in the prior art, where mercury electrolysers are widely used for the production of electrolytic chlorine and caustic soda.

In the following description, mercury will be used as the metal layer of the composite membrane of the present invention.

In another embodiment of the invention, the interface between the polymeric membrane and the mercury layer is increased over a planar interface by corrugating the membrane, i.e., by indenting it into the mercury layer. be able to.

It is also convenient to enlarge this interface by first depositing mercury within the polymer membrane structure, for example by electrolyzing a mercury salt solution or by other methods.

Resistance is achieved by using a swelling agent, usually a polar solvent such as ethanol or glycol, alone or in conjunction with mercury impregnation.
It has also been found that the reduction can be achieved by application to polymeric membranes.

The polymeric portion in the composite membrane must have the properties of low electrical resistivity and high resistance to chlorine and salt water under the operating conditions used.

The polymeric portion of the composite membrane can consist of a solid perfluorocarbon polymer having pendant sulfonic acid or sulfonate groups, or sulfonic acid and sulfonate groups.

(The expression ``sulfonic acid group'' is used generally to refer to sulfonic acid and/or sulfonate groups.

) The fluorocarbon polymer has pendant groups either directly attached to the polymer backbone or attached to perfluorocarbon side chains attached to the backbone.

Either or both of the polymer main chain and any side chains can have oxygen atom bonds (ie, ether bonds).

The perfluorocarbon polymer used for the preparation of the polymer portion of the composite membrane of the present invention is such that the pendant groups and the perfluorocarbon polymer have mixed substituents of chlorine and fluorine (provided that the number of chlorine atoms is chlorine and fluorine). Also included are perfluorocarbon copolymers having no more than about 25% of the total atoms of fluorine) with the pendant groups.

The polymeric portion may optionally be reinforced, for example, by using a suitable metal mesh or polytetrafluoroethylene cloth or other reinforcing metal, as described in co-pending U.S. Pat. No. 196,772. can do.

Perfluorocarbon polymers used for the polymer membrane portion of composite membranes are described in U.S. Pat.
It can be prepared as described in No. 3.

A suitable perfluorocarbon polymer is 2FSO2C
F2 CF2 0CF (CF3) CF2 0CF
After copolymerizing vinyl ether with =CF2 and tetrafluoroethylene, the -SO2F group is converted into -SO3
prepared by changing H or a sulfonate (eg, an alkali metal sulfonate) or both.

Suitable copolymers have equivalent weights ranging from 950 to 1350, where equivalent weight is defined as the average molecular weight per sulfonyl group.

The preferred thickness of the membrane portion is 0.00 liters to 0.010 inches.

Thus, the electrolytic cell of the present invention has an anode and a composite membrane, the composite membrane comprising a polymer portion consisting of a perfluorocarbon polymer having pendant sulfonic acid and/or sulfonate groups and in close contact with the polymer portion. It consists of a cathode layer of an alkali metal permeable metal in contact with the alkali metal.

Although the metal layer in the composite membrane is described as mercury,
Other metals can be used instead.

The type of metal selected is determined by the cations in the electrolyte, the permeability of the metal layer to the cations, and the interaction between the metal layer and the cations.

For example, thin films of silver and/or lead or a combination of these metals and mercury can be considered for this purpose.

Since the electrolytic cell of the present invention can be operated at high pressures and elevated temperatures, normally solid metals and alloys can be used in their molten state.

Very thin layers of solid metal exhibiting sodium diffusion properties enable the use of solid metal components in composite membranes.

This method can also be used in conjunction with liquid metals.

These and other embodiments facilitate configurations using composite membranes in positions other than horizontal.

The anode of the electrolytic cell may consist of any material suitable for the intended electrolytic process, such as, for example, platinum group metals and their oxides alone or as a coating on titanium or tantalum.

The anode may be in any suitable form, such as a sheet, expanded or perforated metal, smaller sections of such form, or any other form that does not lead to damming or uptake of the anode product. be able to.

The shorting electrode in the deicing chamber is made of graphite or similar material with a relatively low hydrogen overvoltage.

These electrodes are distributed in a pattern on the surface of the mercury in the thawing chamber and partially immersed in the mercury.

Hydrogen bubbles are generated at the graphite surface, while hydroxide ions are generated when sodium ions enter the aqueous solution from the mercury layer.

Although a shorted graphite electrode can serve to carry the cathodic current to the mercury, it is preferable to use a metal conductor from the anode of the electrolyzer immediately above.

Graphite cloth entwined between and around these metal conductors has been found to be effective in producing rapid and complete deicing of the amalgam while allowing close spacing of each metal conductor.

The invention will now be described in further detail in conjunction with the accompanying drawings.

It is understood that the means for carrying out the invention shown in the drawings are not restrictive and that various changes in construction and operational details may be made by those skilled in the art. Should.

Figures L2, 3 and 4 are partial sectional views of single elements of electrolyzers for stacking, in which the individual elements occupy an essentially annular space, which annular space extends from the outside of the annulus. The cylindrical core at the center of the ring is used as an insulated conduit for the weakened electrolyte.

Other geometric forms can also be used, for example rectangular elements.

In the following descriptions of figures 1, 2 and 3, reference is made to the upper part of the electrolytic cell, which is identical to the upper part of the next adjacent electrolytic cell below.

Referring to FIG. 1, 1 is the outer anolyte ring, 2 is the outer deicing chamber shell, 3 is the water supply pipe, 4 is the anolyte, and 5 is the outer anolyte busle ( bustle)
, 6 is an anolyte regulator, 7 is an anolyte supply pipe, 8 is an anode, 9 is a hydrogen space, 10 is a caustic space, 11 is a graphite cloth tape, 12 is the electrical conductor, 13 is the inner anolyte ring, 14 is the inner deicing chamber shell, 15 is the caustic and hydrogen discharge pipe, 16 is the inner anolyte busle, and 17 is the inner 18 is the anolyte overflow tube, and 19 is the outer membrane ring.

Layers A and B together form a composite membrane: in which A is a polymer membrane layer and B is a metal layer, ie mercury.

The electrolytic elements include an anode 8, an outer anode ring 1, and an inner anode ring 13.
, the outer ice-breaker shell 2, the inner ice-breaker shell 14 and the bottom of the next anode 8'.

Inside each element is a composite membrane AB, a graphite tape 11 and a conductor 1.
There are 2.

The anode 8 is a plate made of steel or nickel with a thin layer of titanium bonded in intimate electrical contact to its upper surface.

The upper surface of the titanium layer, on the other hand, is coated with a member of the platinum group metals or one of their oxides, for example ruthenium oxide.

A conductor 12 is connected to the lower side of the anode.

This connection must still be in close electrical contact.

For example, conductor 12 may be a nickel wire attached to the anode plate by electron beam welding.

These conductors need not be straight wires, but hairpin loops, or tend to carry current between the mercury and the anode above it and disturb the space between the mercury surfaces or the interface between mercury B and membrane A. It may be any other suitable form that provides good electrical contact between the mercury and the anode above it.

A person skilled in the art will, of course, be able to calculate the electrical conductivity of these elements.

A very good distribution of the current in the mercury is required.

Whether this is achieved by a large number of thin conductors or by relatively few thick conductors with relatively thin distribution conductors in the mercury, for example a mesh,
It doesn't matter as long as the above requirements are met.

Elements in contact with anolyte and chlorine, anodic rings 1 and 13
and the diaphragm rings 2 and 14, membrane rings 17 and 19, and any required gaskets, not shown in the diagram for simplicity, must be of material and construction to withstand the corrosive environment encountered. Must be.

Moreover, the construction and bolting must be such that even if the protective material is torn, it will not result in a short circuit.

It is therefore preferred that all these elements be constructed from non-conductive materials rather than from coated metals.

In the case of fluoropolymers, high-density polyethylene, certain polyesters, and materials that only face the ice-breaking chamber,
Epoxies are suitable materials.

The inner edges of the conductors 12, 2 and the outer edges of the conductors 14 are
It must be metallic and amalgam-wettable, preferably iron or nickel.

This is desirable to prevent leaching of the solution around the mercury in the case of the icebreaker ring and poor electrical contact in the case of the conductor 12.

Graphite cloth tape 11 serves as a very efficient ice-breaking element, but graphite tubes around conductor 12 or other shapes of graphite placed between these conduits are also suitable.

However, stratification and poor deicing can be avoided by using graphite cloth wrapped around the conductor 12 in such a way as to form a flow path, thereby facilitating the flow and mixing of water and caustic fluid. It is preferable.

The water supply pipe 3 and the caustic and hydrogen pipes 15 are simply conventional pipes or tubes made of suitable insulating material or with suitable insulating fittings.

The brine supply pipe 7 has a flow regulator 6 to ensure that the proper amount of electrolyte reaches each element.

This anolyte regulator 6 may simply be a control valve with an appropriately sized orifice or flow sensing means.

When a stack of these elements is fed from a common header, by the use of a flow control device designed to supply an appropriate proportion of the total flow to a number of vertically arranged vessels. Preferably, the flow rate is adjusted and, if necessary, measured.

The flow rate of the individual electrolytic units must be uniform regardless of the different hydrostatic heads present on the stack of electrolytic cells.

This can be accomplished by various dispensing means, such as individual feed pots that feed at certain times of the day, along with flow control orifices.

A preferred method for maintaining a controlled and substantially equal flow rate of brine in each brine stream despite differences in hydrostatic pressure is to direct each brine stream vertically upward in a tube with progressively narrower holes. It is to send it.

Within this tube is a rotor, or float, suspended in a moving salt water stream.

At this time, the gravitational force (less than the buoyant force) on the rotor is
Balance the equal and opposite force exerted on the rotor by the moving brine stream.

This force is independent of the flow rate of the brine stream and is equal to the pressure difference times the maximum cross-sectional area of the rotor.

Therefore, the pressure difference is also independent of flow rate.

The float is an axially symmetrical body, either a sphere or preferably a solid with its center of gravity substantially below the cross section at its maximum area.

It is designed to be self-centripetal in the moving flow and can be described as a weight-like configuration.

Its vertical position within the tapered tube can vary with flow rate.

When this position is measured on a linear scale as a measure of flow velocity, this device is known as a rotameter.

Each parameter of this device has the following relationship: However: △P is pressure difference; Sf is the maximum cross-sectional area of the float; vf is the volume of the float; df is the density of the float; d is the density of the fluid; C is orifice constant; g is the gravitational constant; S is the relationship between the float and the pipe wall at the maximum cross section. Area of the annular space between; q is the volumetric flow rate.

These equations show that the pressure difference △P imposed on the brine flow depends on the choice of the float parameters, vf(df-d)/Sf, i.e., the float geometry and the apparent density (which together determine the specific weight can be controlled by appropriate selection of

The invention is utilized for the purpose of maintaining equal flow rates in several liquid streams in the following manner.

Each brine stream is designated by a number 1, 2, 3,...n, and the hydrostatic pressure is p1 t p2 t p3
It is expressed as y...pn, where the number under the bottom indicates the number of the salt water flow.

The float parameters as mentioned above in the float of each flow are pressure differences Δpl, Δp2, Δm,...
Adjust so that △pn satisfies the following condition: H +△p 1 = p2 + △P2°p3 + △P3°゛゜゛゜゜”pn + ∆Pn By adjusting the float parameters as described above, the flow rate distribution can be adjusted to It remains the same regardless of the salt water flow rate.

In the above description of this aspect of the invention, the flow rate of brine in each stream is equal and the flow in each tube is upward to oppose the downward force in the float, which is heavier than the fluid.

However, through the use of appropriately balanced and weighted floats, it is possible to apply the invention to balance the flow rates in unequal brine streams.

Means for adjusting the flow rate ratio between each stream, such as a valve in each stream, can be used in combination with the float control means, such that the flow rate ratio between each stream (i.e., ) can be maintained regardless of the total flow rate from the main pipe.

It is also within the scope of this invention to use floats that are lighter than the liquid at average specific gravity.

For this case, the flow of liquid in the tapered tube is downward; the taper in the tube extends downward and the center of gravity of the float is above the cross section at maximum area.

In this flow control system, the vertical position of the float is related to the annular area S and the volumetric flow rate q, assuming all of the parameters on the right side of equation (2) remain constant.

By varying the upstream pressure P1 in the common manifold, it is possible to obtain a proportional change in the flow rate of the liquid flow to each electrolyzer while maintaining the hydrostatic pressure difference.

The ability to proportionally control solution flow to the individual vessels by control means in a common manifold is of great benefit in chlorine-caustic production.

This is because flexibility in production is essential in order to meet fluctuations in demand without requiring extremely large storage facilities.

Optionally, these flow balancing devices may be combined with capacitive or inductive position sensing means.
It can be used as a sensor for flow rate information.

This flow control system is also valuable in systems other than the chlorine electrolyzer described here.

This type of flow control is useful for any system consisting of multiple feed streams from a common header when it is desired to maintain equal or proportional flow rates between the multiple feed streams despite different upstream pressures. It also has general applicability to systems.

The anolyte overflow tube 18 is designed so that the hydrostatic head created by the height compensates for the weight of the mercury, membrane and caustic and keeps the membrane A firmly up against the bottom of the conductor 12. must be high enough to provide the necessary force.

Film A is shown as a flat film in the figure, but film A
It is preferred to have an extended surface with folds or depressions extending into the mercury to widen the interface between the mercury and the mercury.

This lowers the electrical resistance of the interface and the membrane itself and reduces the amount of mercury in the system.

The hydrostatic head to be provided by
Preferably, the inch is high.

Preferably, the anolyte tube is also designed to be electrically insulating.

Of course, some or all of the pipes connecting to the tank can be replaced by passageways within the tank structure.

Referring to FIG. 2, 20 is the housing of the electrolytic cell, 21 is the anode, and 22 and 23 are gaskets.

All other elements of the vessel shown in FIG. 2 have the function of similar elements in FIG.

Anode 21, along with the conductor, fulfills the same function as anode 8 and conductor 12 of FIG. 1, but facilitates the outflow of liquid chlorine.

Two alternative anode structures are shown in FIG.

On the left hand side the upper part of the conductor 21' is enlarged to form a button.

This results in an anode consisting of a number of small parts with intervening channels for the outflow of liquid chlorine.

In this way, more than one conductor can be connected to a single button, and rather than the button passing through the top of the trough housing, the conductor is connected to the top of the trough housing and through the trough housing. It is also clear that buttons placed all over the top can be made to run through.

This configuration adapts the configuration to forming techniques and to wire and threaded metal working techniques and eliminates the use of brittle anode materials that cannot be easily processed to cover large surfaces as thin parts. It has the advantage of being possible.

This method allows a choice of materials and the conductor and button can be of one material or two completely different materials.

The anode design shown on the right-hand side, in which the anode consists of a perforated sheet 21'', is adapted to different fabrication methods.

Perforated sheets, wire mesh or spread metal can be used to connect conductors by passing each conductor through the top of the tank housing or by connecting several conductors to each other in the deicing chamber and forming bundles of such conductors. Electrical connections can be made by pulling only one connecting wire from the anode sheet to the anode sheet.

Space can be provided for liquid chlorine by positioning the anode sheet somewhat above the top of the tank housing.

The top surface of either the button or the anode sheet must have a shape such that liquid chlorine does not disturb it but tends to flow to the top of the cell housing.

For corrosion resistance, the top of the cell housing can be protected by a layer of fluoroplastic held by shoulders or buttons on the conductors.

Gaskets 22 and 23 seal the polymer membrane to the vessel housing and adjacent housings to each other.

If a perfluorosulfonic acid polymer is used as the membrane, this material should be sealed against other fluoropolymers or its edges should be left in the sulfonyl fluoride form and the gasket structure assembled in this way. Is possible.

Similarly, this material, or its sulfonyl fluoride form, can be used neat or attached to the fluoropolymer lining of other tank components, thereby providing various means of attachment and corrosion protection.

The puzzle structure of FIG. 2 is somewhat different from that of FIG.

This is because the vessel in Figure 1 is intended to produce dissolved chlorine under pressure, whereas the vessel in Figure 2 is produced through a hole or hole in the anode along the top edge of the vessel housing and inside. It is designed to produce liquid chlorine which is freely discharged into the bustle structure.

Referring to FIG. 3, 24 is a diaphragm, 25 is an anode network, 26 is an anode pan, and 27 is an anolyte and anode gas outlet.

The cell of FIG. 3 has a fundamentally different anode structure.
It is essentially similar to the cell in the figure.

Using the electrolysis of sodium hydroxide solution to produce caustic soda, boric acid, hydrogen and oxygen as an example, the anode gas oxygen cannot be dissolved or liquefied in the tank under any practical conditions. It is clear that it cannot be done.

Therefore, to carry out such electrolysis, a high anolyte flow rate is required to drive the bubbles out of the cell, yet still suffers the disadvantage of air bubbles in the anolyte resulting in relatively high cell resistance. It is necessary to either be able to accept this, or to be able to operate a cell with a composite membrane at the cathode and a drained anode protected by a diaphragm, leaving an intervening electrolyte substantially free of air bubbles. .

The electrolyte can either completely penetrate through the anode diaphragm or can be partially circulated through the cell, allowing some of the electrolyte to flow through the diaphragm.

This can be adjusted by selecting a membrane with appropriate resistance to flow and controlling the pressure difference between the main chamber flow and the gas phase in the anode pan by means known in the art. can.

The diaphragm can also be replaced by an anion-permeable membrane or a cation-permeable membrane, so that in the case of sodium sulfate electrolysis, the anolyte is not a mixture of sulfuric acid and sodium sulfate at the anode. It consists mostly of sulfuric acid with a minimal amount of sodium sulfate leaking out.

The sodium sulfate recycle stream thus allows for the separation of sodium sulfate from the sulfuric acid without the need for an external crystallization step.
Just let it resaturate.

Since one of the major applications of sodium sulfate electrolysis is in the recovery of rayon spinning baths, such crystallization can be accomplished by recycling the solution from the electrolytic cell into the spinning bath recovery.

This type of electrolytic cell can also be used for the electrolysis of sodium chloride by choosing suitable membranes and anode materials, in which case the cell can be operated at almost normal pressure.

Although FIG. 3 shows a wire mesh anode, other drainage forms of anode can be used as well, thus allowing the use of materials such as lead-silver alloys, magnetite, and the like.

Referring to FIG. 4, 1 is a pressure-resistant enclosure, 2 is a caustic liquid or water distributor, 3 is a caustic liquid or water supply, 4 is a flexible cathode busbar, 5 is a caustic liquid or water supply pipe, and 6 is an insulated pressurized fluid,
7 is a cathode end cap, 8 is an anolyte supply main tube, 9 is an anolyte regulator, 10 is an anolyte release core, 11 is an electrolytic cell element, 12 is an anolyte overflow pipe, 13 is an insulating ring, and 14 is an anode Liquid feed, 15 is the anode end cap, 16 is the caustic and hydrogen outlet, 17 is the anolyte and chlorine outlet, 18 is the cathode rectifier bus connection, and 19 is the anode rectifier bus connection.

This figure shows a conceptual cross-section of a stack of electrolyzer elements providing chlorine as a liquid or dissolved gas.

The bottom of the stack is the terminal anode, which also has most, if not all, of the plumbing connections, since it is also possible to lead the water and caustic connections 3 into the foundation. .

This foundation is also connected to the positive side of the rectifier.

The pressure envelope 1 is mounted on the stack and connected in a gas-tight manner to the foundation, and the space between the pressure envelope and the stack of electrolytic cells is filled with an insulating pressure fluid 6.

At the top of the tank stack is a cathode end cap 7.

This end cap is connected by flexible busbars to the shell 1, which acts as a vertical bus bar conducting the negative current from a rectifier whose bottom is connected to the top of the tank stack.

At the top of the tank stack is a water or caustic distributor that feeds each element's deicing chamber.

The volume of liquid in each deicing chamber is relatively large so that discontinuous feeds can be accommodated, provided the average feed volume is accurate.

Therefore, measurement of the total feed 3 to the stack with precise distribution by devices such as rotary valves, multi-shaft plunger pumps, etc. is appropriate.

The distribution device must be at the top of the stack so that the individual supply pipes drain and empty into the deicing chamber, in order to prevent leakage of current through the series of supply pipes 5.

When the insulating fluid 6 provides complete insulation, the pressure-resistant shell can be bare metal, except for the insulating ring 13.

However, the risk of leakage from the cell stack is always present, regardless of the pressure balance control between the cell stack and the fluid 6, and large short circuits can occur.

The inner surface of the pressure envelope 1 is therefore preferably lined with a suitable insulating material, which may be rubber or other plastic material compatible with the fluid 6 and operating temperatures.

In addition, the bottom of the shell and the top of the anode end cap are connected to ring 13 since the entire stack voltage difference exists at that point.
should be protected by leak-free coupling.

The above enclosure configuration assumes that the main output from the rectifier or other DC power source is at or near ground level.

If this is not the case, the insulated connections in the shell can be somewhere along the height of the shell and the current connections are then placed on either side of the insulated connections.

Referring to FIG. 5, 1 is a cooler or a heat recovery device;
is a stack of electrolytic cells, 3 is an anolyte circulation pump, 4 is a weakened anolyte cooler, 5 is a resaturator, 6 is a chlorine decanter, 7 is a dechlorination system, 8 is a chlorine drying system, 9 is a slurry tank , 10
1 is a slurry pump, 11 is a salt charge, 12 is a chlorine product, 13 is an anolyte lead stream, and 14 is a purified anolyte lead return stream.

FIG. 5 is a conceptual flow diagram for a brine and chlorine system surrounding one or several cell stacks producing liquid chlorine directly in an electrolytic cell.

The operation of the process shown in this flow diagram will be obvious to those skilled in the art from this diagram.

Simply put, this consists of the following:

The weakened anolyte is passed from tank 2 into heat exchanger 4 where it undergoes a reduction in temperature.

The cooled anolyte is then sent to a resaturator 5 where the chlorine content is increased.

The anolyte is then passed into the chlorine decanter 6, from where most of the anolyte is recycled into the tank 2 by the pump 3.

A portion of the anolyte from the chlorine decanter 6 passes into the dechlorinator γ, from where it is discharged as stream 13.

Purified anolyte, stream 14 and salt 11 are charged into slurry tank 9 and sent by slurry pump 10 to resaturator 5.

Chlorine removed from chlorine decanter 6 and dechlorinator 7 is discharged as stream 12 through chlorine dryer 8 .

The heat transfer fluid from the tank 2 passes through the heat exchanger 1 and the attenuated anolyte cooler 4 and is then returned from the latter to the tank stack 2.

The theoretical decomposition voltage for sodium chloride is about 2.3 volts, but cell stacks are industrially operated at about 2 volts per element above this theoretical voltage.

This excess voltage is expressed as heat and corresponds to a rate of about 60 kW per day per ton of chlorine produced.

Most of this heat is expressed as an increase in the temperature of the circulating electrolyte and the produced caustic solution, and a portion results in an increase in the temperature of the insulating fluid 6 of FIG.

This heat must be removed.

This can be achieved by simple heat exchange, with heat being rejected to air or water.

However, operating temperatures and heat sinks
(ink), a significant amount of the electrical energy beyond what is theoretically required is recovered for power generation, process heat, water desalination, etc. be able to.

For the generation of power, it is convenient to use a liquid such as Freon, which has boiling properties at temperatures and pressures close to the conditions of the vessel stack.

This thus turns the stack of coolers and tanks into a boiler.

The boiling insulating liquid can be used to drive the turbine and then condensed back into the cooler.

Otherwise, distilled water is very suitable as an insulating liquid.

Liquid chlorine has an extremely large coefficient of thermal expansion.

At room temperature, liquid chlorine is much heavier than the anolyte, but at higher temperatures the specific gravity of chlorine approaches or is lower than that of the anolyte.

Therefore, chlorine must be separated from the anolyte by either decanting below the anolyte or removing it above the anolyte.

The temperature conditions in the decanter must be controlled as necessary to ensure that a suitable specific gravity difference exists for separation.

Additionally, the unique properties of chlorine are such that when chlorine is lighter than the electrolyte, there is no chlorine interference with the membrane, and when chlorine is heavier than the electrolyte, chlorine does not flood the anode. Instruct the tank to be configured and operated in such a way that it is possible to do so.

The dechlorination system 7 shown in FIG. This is a system that allows for the outflow of

The anolyte circulation rate can be about 5 to 10 gallons per minute per ton of chlorine per day, while the effluent flow is about 0.3 to 0.5 gallons per minute.

Dechlorination under pressure is accomplished by heating the bleed stream and recovering heat by suitable heat exchange means.

If a minor use is available for gaseous chlorine, such as the production of hypochlorite or hydrochloric acid, dechlorination simply discharges the bleed stream to atmospheric pressure and then blows air in the usual manner. This can be achieved by dechlorination by injection or vacuum.

Referring to FIG. 6, 1 is a cooler or heat recovery device, 2
is a stack of electrolyzers, 3 is an expansion engine, 6 is a chlorine flash separator, 7 is an anolyte circulation pump, 8 is a dechlorination system,
9 is the chlorine condenser, 10 is the chlorine drying system, 11 is the slurry pump, 12 is the slurry tank, 13 is the salt supply, 14 is the purified anolyte bleed return stream, 15 is the chlorine product, and 16 is the anolyte bleed. It is a flow.

A brief summary of the operation of this arrangement is as follows.

The weakened anolyte is passed into the resaturator 4 and then into the expansion engine 5.
The latter is driven by the anolyte as it flows into the chlorine flash separator 6.

The bulk of the anolyte passes from the separator 6 to the anolyte recirculation pump 7, which pumps the anolyte back into the anolyte cooler 3 and then into the tank stack 2.

A small portion of the separated anolyte enters the dechlorination system 8 from where it is discharged from the system as a liquid stream 16.

Chlorine from flash separator 6 and from dechlorination system 8 exits as product stream 15 via chlorine condenser 9 and chlorine drying system 10 .

The purified anolyte 14 and salt 13 are stored in a slurry tank 13.
and is directed to the resaturator 4 by the slurry pump 11.

Electrically insulating heat transfer medium is transferred to heat exchanger 1 through stacking of tanks.
from there through the anolyte cooler and back into the tank stack.

This flow diagram is therefore similar to that of FIG. 5, except that operating means for the electrolytic cell are provided such that all chlorine products exit the electrolytic cell as dissolved gas.

To obtain the chlorine product, the pressure of the weakened anolyte is reduced below the operating pressure of the electrolyzer, resulting in a relatively direct relationship between the operating pressure and the pressure maintained in the chlorine flash separator 6. The release of gaseous chlorine occurs at

Since the chlorine separated at 6 is hot and moist and under some pressure, it can be condensed by cooling.

Flushing at pressures greater than 100 psi is preferred in order to be able to utilize commonly available cooling water.

Since very large quantities of anolyte have to be brought up from the flash pressure to the operating pressure, resulting in a considerable use of energy, by flashing the weakened anolyte and the chlorine produced in a kind of expansion engine 5, Preferably, a large proportion of this energy is recovered.

The flow diagrams of Figures 5 and 6 illustrate the production of wet, liquid chlorine.

If necessary, this liquid chlorine can be dried after washing away adhering salts.

In common industrial practice, chlorine has a water content of 6
Drying in equilibrium with about 95% sulfuric acid at 0 is absolutely necessary, otherwise the steel equipment in which liquid chlorine is routinely transported and stored will corrode.

The salt feed to the system is usually purified and prepared in situ.

The salt feed is preferably relatively fine to ensure rapid dissolution, otherwise salt crystals may enter the cell and corrode the membrane.

Referring to Figure 7, 1 is a stack of electrolyzers, 2 is a caustic liquid cooling system, possibly combined with a heat recovery system (not shown), 3 is a caustic liquid separator, and 4 is a caustic liquid circulation pump. , 5
is a caustic liquid separator flash tank, 6 is a hydrogen cooler, and 7 is a caustic liquid separator flash tank.
is a mercury removal system, 8 is a caustic liquid vacuum deaerator, 9 is a vacuum pump, 10 is a hydrogen flow, 11 is a recovered mercury flow, 12 is a caustic liquid flow,
And 13 is a water stream.

Hydrogen and caustic liquid are removed together from the tank stack and separated in 3.

Since hydrogen is only slightly dissolved in the caustic liquid, most of the hydrogen separates out as a hot gas under pressure.

After cooling this hot gas in 6, the mercury content in the cold gas, which was already very low due to the hydrogen being under pressure, is further reduced and the condensed mercury can be recovered.

Very trace amounts of mercury vapor present in the cold hydrogen under pressure can be further removed in 7 by known methods such as chlorine water washing, adsorption, etc.

Unlike conventional mercury electrolysers, this system operates in a completely confined apparatus, and the mercury content in the hydrogen is inversely proportional to the pressure at which the hydrogen is generated, resulting in less mercury contamination. Or the mercury contamination that must be treated will be at a minimum level of one-tenth or less.

The hydrogen released at 10 is thus no longer of socio-ecological significance due to the efficient removal of mercury.

It should be noted that chlorine is produced without the presence of non-condensable gases and therefore there are no bad breath gases to vent or treat.

After separation in 3, the majority of the caustic liquid is recycled for cooling in 2.

This cooling system, along with the cooling systems shown in FIGS. 5 and 6, can be operated in a variety of ways depending on the desired result.

This can serve simply to cool the caustic, i.e. to remove the heat content of the caustic stream, or the caustic stream is at a higher temperature than the brine stream, thus unlike simple cooling. Heat removal from the caustic liquid can be managed to increase the potential for heat recovery.

The net increase in caustic in the system, ie, the net product of caustic, can flow from 3 to 5 where it is expanded to near atmospheric pressure.

Dissolved hydrogen and few hydrogen bubbles leave the caustic at this point.

Depending on the configuration of the system, the hydrogen exiting in step 5 may not contain mercury, in which case no treatment other than removing the caustic droplets is required, but if the hydrogen contains some mercury contamination, If so, it can be processed in parallel with the main hydrogen stream exiting from 3.

Hydrogen has a tendency to remain suspended in the caustic as very small bubbles when its pressure is reduced, and it is therefore desirable to flush residual hydrogen bubbles from the caustic with a vacuum in 8.

The small amount of hydrogen released from the caustic at this point can be combined with the hydrogen stream from 5 and treated as required.

The caustic liquid coming out of 8 can thus be sent directly to a storage location without the risk of hydrogen explosion in the storage tank.

The system can be operated over a wide range of temperatures and pressures to provide liquid or dissolved chlorine, depending on the physical properties of the chlorine.

The selection of specific pressures and temperatures within operable conditions is determined by balancing economic factors through known optimization techniques.

Examples of temperature and pressure ranges for the production of liquid chlorine are about 100 to 1000 psi at about 60 to 270 psi.
300 to 65 under a1 or 150 to 225
It is 0 psia.

In accordance with economic considerations, this method operates at temperatures higher than the temperatures of commonly available heat sinks.

In normal industrial practice, this is 80'F.

This means that the electrolytic tank that produces liquid chlorine has a power of 100 ps.
In the case of systems operating at pressures higher than This means that it shall not be lower than 100 psi.

The pressure/temperature upper limit is again essentially an economic issue.

Of course, the upper limit for liquid chlorine is its critical temperature.

At very high pressures, the equipment becomes significantly more expensive and therefore the process does not normally operate at pressures higher than 1000 psi.

Possible operating temperatures within such pressure ranges can be determined from known data.

The potential for heat recovery from the system can be increased by operating at higher temperatures such that there is a temperature difference between the respective temperatures of the brine and caustic liquid and the heat sink temperature.

In the production of liquid chlorine directly during electrolysis, the main consideration is the boiling point curve for liquid chlorine.

In the case of the production of dissolved chlorine in electrolytic cells, the solubility of chlorine decreases with increasing salt concentration and temperature and increases with increasing pressure.

Thus, the greater the pressure difference between the electrolyzer and the flash separator, the more chlorine is produced per pass per unit of brine flow.

The higher the salt concentration, the lower the chlorine production per batch of brine.

The higher the operating temperature of the vessel, the less chlorine will be dissolved in the brine, but the more heat can be recovered from the brine.

Standard optimization techniques can be used with known data regarding chlorine boiling point and solubility to determine operating conditions for a particular case.

All conventional chlorine electrolysers cannot practically be operated outdoors and must be housed indoors.

The electrolyzer of the invention can be operated outdoors in almost any climate and requires no building costs.

The cell design of the present invention requires neither element-to-element busbars nor distribution busbars at each element, resulting in the absence of any copper or aluminum busbars around the cell.

This not only saves capital costs, but also eliminates one of the main maintenance costs of a conventional chlorine plant.

The above description of the invention has all been for the electrolysis of sodium chloride and sodium sulfate to give caustic soda and hydrogen.

However, it is not limited to these aspects.

Solutions containing other ions, in particular corresponding potassium ion solutions, can also be electrolyzed in a similar manner.

The invention described herein is generally applicable to compounds that can be electrolyzed in a conventional mercury cathode cell.

The present invention is also useful for performing other known electrolytic processes in solutions containing alkali metal ions.

Of course, anolyte fluids (or impurities or interfering ions therein) and deicing media that are known to interfere with the proper functioning of the electrolytic process should be avoided.

Furthermore, for the production of sodium sulfide by using sodium polysulfide as a deicing medium, for the production of sodium hyposulfite by using sulfur dioxide solution as a deicing medium, for the production of alcoholates. for various organic reductions, dimerizations and similar reactions.
In some cases, deicers can be used without deicing graphite.

Also, by careful control of the current efficiency ratio to avoid oxidation of the metal component in the composite membrane, it is possible to use this metal component as a bipolar electrode, thus making it possible to connect the final electrode in the deicing chamber to the composite membrane. Between the anode side of the bipolar metal component,
Further reaction steps can be carried out.

An example of such a reaction is the production of sodium.

Furthermore, although the mercury layer was described as always stationary, this does not exclude the possibility of mercury circulation from the composite membrane.

EXAMPLES The following examples were carried out in an electrolytic cell containing a platinum coated titanium anode facing a composite membrane and having substantially saturated salt water flowing between the anode and the composite membrane.

The produced chlorine was removed from the electrolyzer along with the brine stream.

The composite membrane is made of tetrafluoroethylene and the formula FSO2CF.
After copolymerization with a vinyl ether having 2CF20CF(CF3)CF20CF=CF2 by conventional thermoplastic resin techniques, the sulfonyl fluoride dangling from the resulting copolymer having an equivalent weight in the range of 950 to 1350 produced by changing the group to an acid,
Perfluorosulfonic acid membrane “Nafiion”
on) (manufactured by E.I. DuPont de Nimors & Co.) and a layer of mercury thereon.

The amount of mercury was sufficient to completely cover the polymer film, but care was taken to ensure that all folds or depressions in the polymer film were also covered.

The mercury in the composite membrane was in contact with the graphite element and water was passed over the mercury to form a caustic solution and hydrogen on the composite membrane.

In all examples, the surface of the membrane was expanded into the mercury because the pressure of the brine was greater than the weight of the silver and caustic on the membrane, either by the use of a solvent or by swelling the membrane with an electrolyte.

, the total surface of the electrolytic cell is approximately 1 square tesimeter (approximately 2//
X 8// ).

The flow rate of water through the icebreaker is from less than 10% to 50%
Although various concentrations of caustic alkali were varied to give concentrations exceeding 100%, no effect was observed on the operation of the electrolytic cell.

Example 1 An electrolytic cell substantially similar to that of FIG. 1, except that the horizontal cross-section was rectangular rather than annular, was constructed using a polymeric membrane having a nominal thickness of 2 mils and an equivalent weight of 1200.

The active polymer membrane area inside the flange holding the membrane was 2 inches by 8 inches (1.03 di), and the anode area and mercury layer area were each 1.03 dm.

The thickness of the mercury layer is 4 mm, and the area of the deicing material is 271 cm.
m, and the spacing between the anode and the composite membrane was 0.055 inch.

The electrolyzer was operated at atmospheric pressure with a pH of 3 in the anolyte brine and a concentration of the spent brine of approximately 275 g/l.

The brine supply was 1 cc/amp minute and was recirculated through the electrolyte chamber at a brine flow rate of approximately 4.2 gallons/minute.

The amount of water supplied to the ice-melting section was 0.23 ml/ampere-minute.

The cell voltage was 4.9 volts at 50 amps and 6.6 volts at 80 amps.

The brine flow rate was increased to 6.4 gallons per minute to improve gas blowing out of the electrolyzer, and the voltage was decreased to 6.0 volts at 80 amps.

The temperature of the electrolyte compartment and deicing compartment were both about 190 below at low current density and about 205'F at high current density.

A caustic solution with a concentration of 9-10% by weight was made with a current efficiency of about 95%.

Example 2 The same tank was operated with a membrane that was first soaked in hydrochloric acid and then in a saturated aqueous solution of mercuric chloride at 100° C. for 24 hours.

The mercury in the membrane was then reduced to metallic mercury in situ by the use of hydroxylamine, and the vessel was operated under the same conditions as Example 1 using a brine flow rate of 6.4 gallons/minute.

The cell voltage was 5.6 volts at 80 amps and 4.6 volts at 50 amps.

Other results were substantially the same as in Example 1.

Example 3 The same vessel was operated under the same conditions, except that the membrane was swollen with glycol prior to mercury impregnation as described in Example 2.

The cell voltage was 0.2 to 0.3 volts lower at 80 amps than without the glycol treated membrane.

Other results were substantially the same as in Example 2.

Example 4 An electrolytic cell identical to that used in Example 1 was constructed using a polymeric membrane with a nominal thickness of 3.5 mils and an equivalent weight of 1200, at a pressure of 450 psi and a brine flow of 50 m2/min. I drove.

The electrolyte brine has a pH of 3, and the concentration of the used brine is approximately 2.
It was 75 g/l.

The temperature of the electrolyte chamber and the ice melting section were both below 75°C.

Grooves were carved into the anode to allow liquid chlorine to flow out.

The element on the mercury consisted of 1 inch diameter nickel pins on 1 inch centers and graphite cloth around and between them.

Graphite and nickel were in contact with mercury.

The area of the deicing material is 271cm, and the thickness of the mercury layer is 4M.
Met.

Initially, at a cell voltage of approximately 10 amps and 3.64 volts, dissolved chlorine in the brine was seen in the viewing glass at the outlet of the cell.

As the current is increased to 50 amperes, the bath voltage increases and then decreases as liquid chlorine appears, leaving the bath voltage at 50 amps.
．． Stable at 1 volt.

Liquid chlorine appeared as a separate phase in the viewing glass with the brine containing dissolved chlorine.

Liquid chlorine appeared because as the current was increased the formation of chlorine exceeded its solubility in salt water.

Relatively low cell voltages could be obtained at higher temperatures and with thinner polymer membranes.

The viewing glass was positioned so that the saline and liquid chlorine entered through the dip tube at the top.

The observation glass also had an overflow port on the bottom edge of the dip tube.

This arrangement, at these operating temperatures, resulted in precipitation of liquid chlorine at the bottom of the viewing glass and overflow of salt water from the top of the viewing glass.

The observation glass thus functioned as a decanter.

From the overflow, brine containing dissolved chlorine flowed into the receiver.

The pressure in the receiver was then reduced to vaporize the dissolved chlorine from the brine.

The amount of water supplied to the ice-thawing chamber was 0.23 ml/amp minute.

A caustic solution with a concentration of 9-10% by weight was made with a current efficiency of about 90%.

The hydrogen and caustic from the tank were flowed into a separator to separate the hydrogen and caustic.

The entire system was initially purged with nitrogen and then the hydrogen was removed along with the nitrogen charge.

The invention has been described in terms of specific embodiments described in detail.

Additional embodiments will be apparent to those skilled in the art upon consideration of this description.

Therefore, such modifications should be considered within the scope of this invention.

The main embodiments of the present invention are as follows.

1. A method for electrolyzing an aqueous solution containing sodium and/or potassium ions together with mineral acid and/or organic acid anions and/or hydroxide ions in the solution, comprising: an anode, a polymer membrane facing the anode, and the anode. passing an electric current through the solution present between a composite membrane consisting of a layer of a metal permeable to alkali metals, which is in close contact with the surface of the polymer membrane remote from the membrane; how to.

2. In the method of 1 above, in which the electrolysis is usually to provide a gaseous anode product in the solution at normal pressure, the anode product is in a substantially liquefied state or dissolved in the solution. an improved method consisting of carrying out the process at a pressure higher than normal pressure under conditions giving

3. 2. The electrolysis is conducted at a pressure of about 100 to 1000 psi and a temperature of about 60 to 270 degrees Fahrenheit. the method of.

4. The method of 1 above, wherein the metal is mercury.

5. 1. The polymer membrane is a perfluorocarbon polymer having pendant sulfonic acid groups. the method of.

6. 5. The metal is mercury. the method of.

7. The method of item 6 above, wherein the electrolysis is conducted at a pressure of about 100 to 1000 psi and a temperature of about 60 to 270''F.

8. Electrolyzing an aqueous solution containing sodium and/or potassium ions together with mineral and/or organic acid anions and/or hydroxide ions in solution to give an anode product from the solution, which is usually gaseous at normal pressure. An improved process characterized in that the electrolysis is carried out at a pressure higher than normal pressure under conditions in which the anodic product of the electrolysis is in the liquid phase.

9. The electrolysis is carried out by passing an electric current through the solution present between an anode and a composite membrane having a polymer membrane in intimate contact with a cathode layer of a metal permeable to alkali metals. Above 8. the method of.

10. 9. The polymer membrane is a perfluorocarbon polymer having pendant sulfonic acid groups. the method of.

11. 8. The electrolysis is carried out at a pressure of about 100 to 1000 psi. the method of.

12. 11 above, wherein the aqueous solution is a sodium chloride aqueous solution.
．． the method of.

13. An electrolytic cell characterized in that it has a composite membrane consisting of an anode and a polymer membrane and a cathode layer of a metal permeable to alkali metal ions in intimate contact with the polymer membrane.

14. 13. The polymer membrane is a perfluorocarbon polymer having pendant sulfonic acid groups. electrolytic cell.

15. 14. The metal is mercury. electrolytic cell.

16. 14. The polymer contains mercury deposited therein. electrolytic cell.

17. 14 above, wherein the polymer is treated with a swelling agent. electrolytic cell.

18. 13. having a plurality of conductive cathode elements in contact with the metal; electrolytic cell.

19. 18 above, wherein said polymer membrane is deformed to project upwardly into the area between said cathode elements. electrolytic cell.

20. 18 above, wherein said cathode element has adjacent graphite elements at least in the area in contact with said metal. electrolytic cell.

21. The polymer membrane is FSO2CF2CF2QC and CF3
) A copolymer of OCF-CF2 and F2C=CF2 -8
13 above, which has been treated to convert the 02F group into a sulfonic acid group. electrolytic cell.

22. 18., respectively, wherein the anode of said electrolytic cell is in electrical contact with the cathode element of an adjacent lower electrolytic cell. A series of stacked electrolyzers having an electrolyzer configuration of .

23. a brine supply head conduit positioned substantially vertically along the cell elements of the cell stack; a brine supply conduit connected to each cell element and the feed head conduit; flow control in each brine supply conduit; means, and float means in each flow control means, provided that the specific weight of each float means and the sum of the respective hydrostatic heads in said feed head conduit at the level of the corresponding electrolyser element are the same, so that each 22. A stacked series of electrolyzers as in claim 22, wherein said electrolyzer cell stacks have substantially the same flow rate of brine to the electrolyzer elements.

24. 13. The shape of the anode is adapted to provide a liquid outflow space. electrolytic cell.

25. 24 above, wherein the anode consists of a wire mesh or a number of separate discrete elements protruding from the surface. electrolytic cell.

26. 14. The electrolytic cell of item 13 above, wherein the anode is a porous anode, and includes a diaphragm or membrane between the composite membrane and the anode.

27. a composite membrane consisting of a porous anode, a polymer membrane and a cathode layer of a metal permeable to alkali metal ions in intimate contact with the polymer membrane, and a membrane or diaphragm between the anode and the composite membrane; A method of electrolyzing an aqueous solution containing sodium and/or potassium ions together with mineral acid and/or organic acid anions and/or hydroxide ions in an electrolytic cell consisting of an anode and a cathode. A method characterized in that passing an electric current through the solution and removing the anodic product through the anode.

28. 27. The aqueous solution is sodium sulfate. the method of.

29. A method of electrolyzing salt water in an electrolytic cell consisting of an anode, a cathode, and an anolyte chamber therebetween, comprising pressurizing the cell to about 100 to 1000 psi and passing the salt water into the anolyte chamber. , reducing the salt content of the brine by passing an electric current between the anode and the cathode and causing chlorine and depleted brine to be in liquid phase in the anolyte compartment; and removing the brine from the bath. The method is characterized in that chlorine, caustic liquid and hydrogen are removed.

30. The cathode is a metal layer in a composite membrane that is substantially parallel and coextensive in surface area with the anode, and the composite membrane includes a polymer membrane facing the anode and a polymer membrane on the side remote from the anode. 29. above, having a layer of metal permeable to alkali metal ions in intimate contact with the surface of the coalesced membrane; the method of.

31. 30 above, wherein the metal is mercury. the method of.
32. 29. Adding purified salt to the removed brine to form a brine stream that feeds the anolyte chamber. the method of.

33. The depleted brine contains dissolved chlorine therein and the pressure above the brine is reduced to liberate chlorine gas, as described in 29. method, 34. The depleted brine contains the chlorine in a liquefied state, and the brine and chlorine are separated by gravity separation.
9. the method of.

35. 2 above, in which the caustic liquid and hydrogen are taken out together and separated in stages, first under electrolytic pressure and then by lowering the pressure above the caustic liquid;
9. the method of.

36. 31 above, wherein the caustic liquid and hydrogen are removed together and separated stepwise, ie, first under electrolytic pressure and then by reducing the pressure above the caustic liquid. the method of.

37. 36 above, wherein the hydrogen from at least the first stage of said separation is cooled and purified and then purified to remove mercury. the method of.

38. 29 above, wherein the brine and caustic liquid are removed at a temperature higher than the available heat sink temperature and energy is recovered from the brine and caustic liquid. the method of.

39. 30 above, comprising removing a caustic liquid and recovering energy from the caustic liquid at a temperature above the temperature of the brine. the method of.

40. It consists of a series of electrolytic cells, each electrolytic cell having an anode, a cathode which is a metal layer in a composite membrane, a polymeric membrane facing the anode, and a polymeric membrane on the side remote from the anode. an anolyte chamber between the anode and the cathode, with a layer of metal permeable to alkali metals in intimate contact with it at the surface of the electrolytic cells in the series an electrolyzer, characterized in that the space between the anode of the first cell and the cathode of the next downwardly adjacent cell forms a chamber.

41. The series of electrolytic cells is surrounded by an outer shell forming a space between the series of electrolytic cells and the outer surface of the series of cells.
, device.

42. Said 41, which contains an insulating fluid in said space.
．． equipment.

43. 41. The surface of the outer shell facing the electrolytic cell is insulated. equipment.

44. 41. wherein at least a portion of said shell is a conductor of current to said series of electrolytic cells. equipment.

45. 44 above, wherein the shell is supported on a base member adjacent to the anode of the lowermost electrolytic cell, and an insulating member separates the shell from the base member. equipment.

46. A fluid distribution thread consisting of at least one main tube and at least two branch tubes having branch points, including flow control means in each branch tube and float means in each flow control means, wherein each float An improved yarn characterized in that the specific weight of the means and the sum of the respective pressures in each branch pipe are the same.

47. 46 above, including means for adjusting the ratio of the flow rates in each branch pipe to provide a substantially constant ratio between the flow rates in each branch pipe regardless of the total flow rate in the main pipe. thread.

48. In a method of electrolyzing an aqueous solution of sodium chloride, an electric current is passed through the solution, and the solution is applied to an anode, a perfluorocarbon polymer membrane having pendant sulfonic acid groups, and a surface of the polymer membrane on the side remote from the anode. a composite membrane consisting of a layer of mercury in intimate contact therewith.

49. 48 above, wherein said electrolysis is carried out at a pressure higher than normal pressure under conditions which provide chlorine in a substantially liquefied state or dissolved in said solution. the method of.

50. 49 above, wherein the electrolysis is conducted at a pressure of about 100 to 1000 psia and a temperature of about 60 to 270'F. the method of.

51. 49. The method of claim 49, wherein the electrolysis is conducted at a pressure of about 300 to 650 psia and a temperature of about 150 to 225 psia.

52. The perfluorocarbon polymer has been treated to convert -SO2F groups into sulfonic acid groups.
O2 CF2 CF2 0CF (CF3) CF2
48. where 0CF=CF2 and F2C-CF2 copolymer. the method of.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a single element of an electrolytic cell using a composite membrane, a sheet anode and a graphite cloth in a deicer for producing chlorine as a dissolved gas under pressure. FIG. 2 shows an electrolytic cell using a composite membrane, an anode (shown in alternative forms of a perforated anode and a button anode) and a graphite cloth in the deicing for producing liquid chlorine under pressure. A partial cross-section of a single element. FIG. 3 is a partial cross-section of a single element of an electrolytic cell for the electrolysis of sodium sulfate, using a drained anode chamber with a composite membrane and a gold-steel anode, and a graphite cloth in a deicer. FIG. 4 shows a cross-section of a stack of electrolyzer elements inside a pressure-bearing envelope for producing chlorine under pressure. FIG. 5 shows a brine and chlorine system flow diagram for an electrolytic cell stack consisting of electrolytic cells using composite membranes for producing liquid chlorine under pressure. FIG. 6 is a flow diagram of the brine and chlorine system for a cell stack consisting of electrolytic cells using composite membranes for producing chlorine dissolved in brine under pressure. FIG. 7 shows the water, lye and hydrogen system flow diagram for a stack of electrolyzers with the lye cooled by recirculation.

Claims (1)

[Scope of Claims] 1. A method for electrolyzing an aqueous solution containing sodium and/or potassium ions together with chlorine and/or bromide ions, comprising: an anode and a parter having a sulfonic acid group or a metal sulfonate group facing the anode; a fluorocarbon polymer membrane and a mercury cathode layer in intimate contact therewith at the surface of the polymer membrane remote from the anode; the mercury cathode layer includes at least one
A method characterized in that an electrical current is passed through the solution between a composite membrane consisting of two graphite deicing elements in contact with each other. 2 anode, a composite membrane consisting of a perfluorocarbon polymer membrane having sulfonic acid or metal sulfonate groups and a mercury cathode layer in intimate contact with the polymer membrane, and at least one membrane in contact with the mercury cathode layer; An electrolytic cell characterized in that it has a graphite deicing element.