FR2475066A1 - Expanded spacer used between two parallel surfaces - esp. expanded polymer foil used between electrodes in electrolyser mfg. hydrogen in high yield - Google Patents

Expanded spacer used between two parallel surfaces - esp. expanded polymer foil used between electrodes in electrolyser mfg. hydrogen in high yield Download PDF

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Publication number
FR2475066A1
FR2475066A1 FR8002553A FR8002553A FR2475066A1 FR 2475066 A1 FR2475066 A1 FR 2475066A1 FR 8002553 A FR8002553 A FR 8002553A FR 8002553 A FR8002553 A FR 8002553A FR 2475066 A1 FR2475066 A1 FR 2475066A1
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France
Prior art keywords
sheet
distance
characterized
2d
spacing device
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
FR8002553A
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French (fr)
Inventor
Siebo Kunstreich
Bernard Girard
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CEM CIE ELECTRO MECANIQUE
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CEM CIE ELECTRO MECANIQUE
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Priority to FR8002553A priority Critical patent/FR2475066A1/en
Publication of FR2475066A1 publication Critical patent/FR2475066A1/en
Application status is Withdrawn legal-status Critical

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/18Separators; Membranes; Diaphragms; Spacing elements characterised by the shape
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00Diaphragms; Spacing elements
    • C25B13/02Diaphragms; Spacing elements characterised by form or shape

Abstract

The spacer permits the flow of a fluid between the parallel surfaces, which are esp. electrodes; and is made from a flat foil (1) with thickness (e). In foil (1) are parallel rows of slots(2) with initial length (L), sepd. from each other in the same row by a space(n); and a distance(d) exists between adjacent rows. The slots in adjacent rows are staggered by the dimension (L+n)2. After expansion, foil(1) has joints(3) with a transverse cross-section of length(2d) and thickness(e); and each joint (3) is tilted at an angle w.r.t. a plane(Z) parallel with the thickness of foil(1). Foil (1) is pref. made of PTFE, in which case the tilt angle is pref. zero. Used esp. between pairs of electrodes in electrolyser contg. KOH electrolyte for mfg. H2.

Description

 The present invention generally relates to a spacing device for azure a predetermined minimum spacing between two parallel surfaces at spaced points arranged along the nodes of a mesh network, while allowing the flow of a fluid between the two surfaces parallel to them. In particular, the present invention relates to a spacing device of the aforementioned type, which is used to ensure the spacing between the porous diaphragm and one or the other of the two electrodes of a cell of a high efficiency electrolyser , as well as the method of manufacturing such a spacing device.

 It is known that, in electrolysers which are intended for the production of hydrogen and which use a potash solution as electrolyte, obtaining a high overall yield requires an increase in the temperature of the potassium hydroxide solution and that, in In particular, operation at around 2000 is economically attractive. Under these conditions, conventional porous asbestos diaphragms placed between the electrodes of the elementary cells of the electrolyser can no longer be used because of corrosion. A known solution consists in replacing the porous asbestos diaphragms with thin porous sintered metal diaphragms, in particular sintered nickel. However, in this case, it is necessary to prevent the metal diaphragm from short-circuiting the cell by contact with the two electrodes. trodes deforming in particular as a result of even slight pressure difference between the anode and cathode compartments of the cell. It is therefore necessary to provide in each of the anode and cathode compartments of the cell a spacing device capable of ensuring the separation between the diaphragm and the adjacent electrode, while allowing the flow of the electrolyte between the diaphragm and the adjacent electrode. Various spacers have already been proposed to solve this problem. However, the known spacers are complicated to set up in the electrolysers or significantly reduce the active surface of the electrodes and diaphragms.

 The present invention therefore aims to provide a spacing device whose manufacture is simple, fast and inexpensive and which, in the case where it is used in an electrolyser, can be quickly set up in the electrolyser and reduces little active surface of the electrodes.

For this purpose, the spacing device according to the present invention is characterized in that it consists of a grating having a deployed structure known per se, obtained from a flat sheet of thickness e having sections of length 1 disposed along lines which are parallel to a first direction y of the planar sheet and spaced apart by a distance d, the sections on the same line being spaced from each other by a distance n and being offset by a distance (1 + n) / 2 in the first direction y with respect to the cuts on the adjacent line, said expanded structure grating forming a network whose nodes have a rectangular cross-section of length 2d and width e, and in that the rectangular cross section of said nodes has an orientation that satisfies the relationship

Figure img00020001

where a is the angle between the length side 2d of said rectangular section and the perpendicular to the plane d 2d of the plane sheet, and e is defined by tge = e
In the case where the spacing device is intended to be used in an electrolyser, the expanded structure roasting is made of an insulating plastic material chemically resistant to electrolytes and the operating temperature of the electrolyser. Preferably, the unfolded structure screen is made of polytetrafluoroethylene and the aforementioned angle a is equal to zero.

An embodiment of the spacing device according to the invention will now be described with reference to the appended drawings in which:
Figure 1 is a plan view showing a portion of a sheet used for the manufacture of the spacing device according to the invention.

 FIG. 2 is a plan view, on an enlarged scale, showing the shape of the meshes for different tensile values, when pulling in the x direction on the opposite sides of the sheet shown in FIG.

 Figure 3 is a sectional view along the line 111-111 of Figure 2.

 Figures 4a to 4d show various orientations of the rectangular section # of nodes of the meshes shown in Figure 2.

 Figure 5 is a perspective view showing a portion of a jig used for the manufacture of the spacing device according to the invention.

 FIG. 6 is a perspective view, on an enlarged scale, showing a detail of the template shown in FIG. 5.

 Figure 7 is a schematic vertical sectional view of an electrolysis cell.

 FIG. 8 is a schematic view in horizontal section of the electrolysis cell shown in FIG. 7, in one of the two anode and cathode compartments from which is placed a spacer device according to the invention.

 The spacing device according to the invention is in the form of a grid having an expanded structure.

To make an expanded structure grating, a flat sheet 1 (FIG. 1) of thickness e is used, in which sections 2 of length 1 are made. The sections 2 are made along lines which are parallel to a direction y of the flat sheet 1 and which are spaced apart by a distance d. The sections 2 situated on the same line are spaced from each other by a distance n and are separated by a distance (+ n) / 2 in the y direction with respect to the sections 2 situated on the line adjacent.

 If two opposite contractions in the x direction are then exerted on the two opposite sides of the plane sheet 1, a mesh network is obtained whose meshes have substantially the shape of lozenges. The greater the traction exerted in the direction x is important, the more the meshes are open as shown on FIG. 2. The nodes 3 of the mesh network have a rectangular cross-sectional section of length 2d and width e. As shown in FIG. during the deployment of the sheet 1, the nodes 3 leave the xy plane of the sheet 1 and "stand", that is to say that the angle between the length side 2d of the rectangular section of the nodes 3 and the x axis increases, but remains always less than 900 (see also Figures 4a to 4d). In the case where the sheet 1 used is a plastic sheet, if traction ceases, the mesh network or mesh returns to its original position, that is to say that the sheet 1 takes the form shown on the Figure 1. If it is desired that the mesh retains the desired shape, it must be stabilized by a shaping treatment which will be described later.

 As can be seen in FIG. 3, if the mesh is placed between two parallel surfaces 1 and 5, there remain free spaces 6 which allow the circulation of a fluid between the surfaces 4 and 5 parallel to these and perpendicularly to the plane of Figure 3, that is to say parallel to the Z direction of the sheet 1. However, if either of the surfaces 4 and 5 is subjected to a pressure in the z direction tending to bring it closer to the other surface, the nodes 3 may have a tendency to lie down, that is to say that the angle f can become zero and that the spaces 6 can close and thus prevent any flow of fluid.

To avoid this, it is necessary that the rectangular section of the nodes 3 has a well-defined orientation. In FIG. 4b, the angle α between the side of length 2d of the rectangular section of node 3 and the direction z is greater than 2, e being defined by tg = 2d. In this case,
2 sees that if a pressure P is applied to the node 3, the surface 4 being assumed fixed, the node 3 will tend to fold (<p becomes zero). In Figure 4c, the angle a is equal to 2 ~ e. This orientation of the rectangular section
2 of the node 3 corresponds to an unstable equilibrium position.

In Figure 4d, the angle a is less than 2 -e. In that case,
2 if the node 3 is subjected to a pressure P, the surface 4 being assumed fixed, the node 3 will stand completely (<p = 900 or a = O). From the foregoing, it can be seen that if it is desired to prevent the knots 3 of the lattice from lying down under the action of a pressure P and the spaces 6 (FIG. 3) to close again, the orientation of the rectangular section of the nodes 3 must be such that the angle has satisfies the relation

Figure img00050001

It can also be seen that if the surfaces 4 and 5 must be spaced apart by a distance E + #, where E is the distance tolerance on the distance E, the following relation must be satisfied.

Figure img00050002

 The two relations (1) and (2) above make it possible to define the quantities d and e of the sheet 1 as a function of the spacing E which must be ensured between the surfaces 4 and 5 for a given application. The length 1 of the sections 2 is chosen according to the size of the meshes that it is desired to obtain.

The aforementioned shaping and stabilizing treatment makes it possible to give the angle a the desired value,
and maintain it at this value when the roasting is
subject to any external solicitation.

 In the case where the spacing device according to the invention is intended to be used as a spacer between the porous diaphragm and the electrode in a high efficiency electrolyzer with an electrolyte consisting for example of a potash solution at 25 - 45% by weight at at a temperature of up to 200 ° C., a sheet 1 made of an insulating plastic material capable of resisting chemical corrosion by the electrolyte at the operating temperature is used. In this case, the sheet 1 is preferably made of polytetrafluoroethylene. In addition, the angle a is preferably chosen to be zero so that the short sides e of the rectangular section of the knots 3 of the mesh are parallel to the surfaces 4. and the porous diaphragm and the electrode and that there is no edge likely to damage the diaphragm which is very thin (0.25 to 0.35 mm). In this case, the length 2d of the long sides of the rectangular section of the nodes 3 is chosen equal to the desired spacing E between the diaphragm and the electrode, and the thickness e of the sheet 1 is chosen so that the relation (2 ) above mentioned is satisfied and also such that the nodes 3 have a good mechanical strength while reducing as little as possible the active surface of the diaphragm and the electrode.

Shaping and stabilizing treatment
insulating plastic mesh having the structure
deployed described above can be achieved using
the jig 7 shown in FIG. 5. The jig 7 is essen
made up of a rigid plate 8 provided with
parallel ribs 9 of thickness a and presenting
notches 10 having a width b and a depth c. The
notches 10 are distributed as the nodes 3 of the mesh network
formed by the mesh and they are dimensioned so as to
can each receive a knot 3. In other words, 11 thickness
has ribs 9 is less than or equal to n and the width
b notches 10 is greater than or equal to e.The depth
c notches 10 can be chosen as large as it is
sire and she is preferably equal to a multiple of 2d so
that several screens can be stacked on the jig 7 and stabilized simultaneously. In addition, the notches 10 make a
~ angle 2 - a with the longitudinal axis of the ribs 9, &alpha; being the desired angle for the orientation of the rectangular section of the nodes 3 of the grid. In the case where the angle desired is equal to zero, the notches 10 make an angle of 900 with the longitudinal axis of the ribs 9 as shown in FIGS. 5 and 6.

 For the shaping and stabilizing treatment, each RxAllage 1 is placed in a deployed structure, while subjected to opposite tensile forces in the x direction, on the jig 7 by engaging the knots 3 in the slots 10 After placing the mesh 1 on the jig 7, the tensile forces can be suppressed. Several screens 1 can thus be set up on the template 7.

Then, the template 7 is placed in an oven. When the screens 7 are polytetrafluoroethylene, the oven temperature is raised to about 200-2200C and the temperature is maintained at this value for a few hours, for example 3 hours. Then, the temperature of the oven is lowered to room temperature, the template is taken out of the oven and the fences 1 are removed from the template 7. The dimensions of the fences i are then stabilized
Figure 7 shows schematically, in vertical section, an electrolysis cell of a high efficiency electrolyser.

A thin porous diaphragm 11, for example made of sintered nickel, is mounted equidistantly (E + #) from the cathode 12 and the anode 13 and separates two respectively cathodic and anodic compartments in which the electrolyte, for example a solution of potash, circulates in the direction indicated by the arrows. Since the porous metal diaphragm 11 is very thin (0.25 to 0.35 mm) and can have a large surface area (several square bends) and because, in practice, the pressure differences of bending 160 millibars can occur between the two cathode and anode compartments of the electrolysis cell, an insulation material spacing device must be arranged in each of the two cathode and anode compartments of the cell in order to prevent the diaphragm porous metal 11, by deforming under the action of a pressure difference, does not come into contact with one or the other of the two electrodes 12 and 13. The mesh 1 according to the invention made of polytetrafluoroethylene of unfolded structure is suitable particularly blen-like spacing device for a high efficiency electrolyser of the type described above.

 FIG. 8 shows schematically, in horizontal section, the electrolysis cell of FIG. 7, in one of the two compartments of which a grid 1 according to the invention is installed. Of course, although not shown in FIG. 8, a similar screen is also located in the other compartment of the electrolysis cell. As can be seen in FIG. 8, the long sides of length 2d of the nodes 3 are perpendicular to the surfaces 4 and 5 of the diaphragm 11 and of the anode 13, while the short sides of length e of the nodes 3 are in contact with the surfaces 4 and 5. It is also seen that the grid 1 leaves free passages 6 in the direction for the circulation of the electrolyte and the gases produced by the electrolysis. We also see that the grid 1 according to the invention covers a minimum surface on the diaphragm 11 and on the electrode 13, thus allowing ion exchange during electrolysis. Finally, it provides sufficient mechanical strength to withstand pressure differences of 160 millibars between the two compartments of the cell.

 For example, in the case where the grid according to the invention is intended to be used as spacing device in a high efficiency electrolyser, e can be between 0.8 and 1 mm, n can be about equal to at 4 mm, d may be between 0.8 and 1 mm and 1 may be about 35 mm.

 Although the present invention has been described above with particular reference to a grid having an expanded structure of polytetrafluoroethylene, usable as a spacer in a high efficiency electrolyser, it goes without saying that the grid according to The invention can be used as a spacing device in other fields of the art. In general, the spacing device according to the present invention can be used in all cases where it is necessary to ensure a predetermined minimum spacing between two parallel, flat or curved surfaces, while permitting the flow of a fluid between the two surfaces parallel thereto. In addition, if it is not necessary to ensure at the same time an electrical isolation between the two suxXaceg spacing device according to the invention can be made of metal by the well known technique of the metal deployed in the latter In this case, the stabilization treatment described above is not usually necessary.

 It is of course understood that the embodiment of the invention which has been described above has been given by way of purely indicative and non-limiting example, and that many modifications can be made by the man of the invention. art without departing from the scope of the present invention.

Claims (9)

REVENDICATJONS
 1.- spacing device for ensuring a predetermined minimum spacing between two parallel surfaces at spaced points arranged along the nodes of a mesh network, while permitting the flow of a fluid between the two surfaces in parallel at. these, characterized in that it consists of a mesh having a deployed structure known per se, obtained from a flat sheet (1) of thickness e having sections (2) of length i disposed according to lines which are parallel to a first direction y of the flat sheet (1) and spaced apart by a distance d, the sections (2) situated on the same line being spaced from each other by a distance n and being shifted by a distance (1 + n) / 2 in the first direction-2 from the sections (2) on the adjacent line, said expanded structure grating forming a network whose nodes (3) have a rectangular cross-section of length 2d and width e, and in that the rectangular cross-section of said nodes (3) has an orientation which satisfies the relationship
Figure img00100001
 where a is the angle between the length side 2d of said rectangular section and the perpendicular z to plane 2d of the plane sheet (1), and e is defined by tg6 = e
 2.- spacing device according to claim 1, characterized in that the grid (1) in expanded structure is an insulating plastic material chemically resistant to electrolytes and the operating temperature of an electrolyser.
 3.- spacing device according to claim 2, characterized in that a is equal to zero.
 4.- spacing device according to claim 2 or 3, characterized in that the grid (1) in expanded structure is polytetrafluoroethylene.
 5. A method of manufacturing a spacing device, characterized in that it consists in: a) forming, in a manner known per se, an in-structure grid deployed from a flat sheet of insulating plastic material of thickness e, by making cuts of length 1 in said flat sheet so that the sections are arranged along lines parallel to a first direction y of the sheet and spaced apart by a distance d, and that the sections located on the same line are spaced from each other by a distance n and offset by a distance (1 + n) / 2 in the first direction y from sections on the adjacent line, and exert two opposing tensile forces on two opposite sides of the sheet in a direction x perpendicular to the first direction y, so as to obtain a mesh network whose nodes have a cross section rec tangulalre of length 2d and width 2e, and b) to submit the sheet It is subjected to a stabilization treatment in such a way that, after removal of the tensile forces, the rectangular cross-section of the knots of the mesh network formed by the expanded structure grating maintain an orientation which satisfies the relationship
Figure img00110001
 in &alpha; is the angle between the side of length 2d of said rectangular section t the perpendicular z to the plane plane plane, and e is defined by tge = 2d
 e
 6. A process according to claim 5, characterized in that the stabilizing treatment consists of placing the sheet, as it is smoother at said tensile forces, on a jig consisting of a rigid plagie provided with several parallel ribs. of thickness having notches having a width b to the outside equal to and a depth c equal to a multiple of 2dt the notches forming an angle 2 a> with the longitudinal axis of the ribs, each node of the network formed by the grating being placed in a notch, to suppress the tensile forces and to subject the sheet thus placed on the jig to a heat treatment in a furnace.
 7. A process according to claim 6, characterized in that, in the case where the sheet is poytytetrafluoroethylene, the heat treatment is to raise the temperature of the oven to about 200-2200C, to maintain this temperature for a few hours and to go down the oven temperature at room temperature.
 8. A process according to claim 6 or 7, characterized in that the angle a is equal to zero.
 9.- Application of the spacing device according to any one of claims 2 to 4, to an electrolyzer comprising, in each anode-cathode range, a thin porous diaphragm (11) of metal mounted at a distance E + # of each electrode (12, 13), characterized in that the thickness e of the insulating plastic sheet (1) and the distance d between the cutting lines satisfy the relation
Figure img00120001
FR8002553A 1980-02-06 1980-02-06 Expanded spacer used between two parallel surfaces - esp. expanded polymer foil used between electrodes in electrolyser mfg. hydrogen in high yield Withdrawn FR2475066A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR8002553A FR2475066A1 (en) 1980-02-06 1980-02-06 Expanded spacer used between two parallel surfaces - esp. expanded polymer foil used between electrodes in electrolyser mfg. hydrogen in high yield

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR8002553A FR2475066A1 (en) 1980-02-06 1980-02-06 Expanded spacer used between two parallel surfaces - esp. expanded polymer foil used between electrodes in electrolyser mfg. hydrogen in high yield

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206032A1 (en) * 1985-06-12 1986-12-30 Forschungszentrum Jülich Gmbh Electrolyser with a diaphragm electrode sandwich assembly, and assembling apparatus suited therefor

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL259158A (en) * 1959-12-17
DE274353C (en) *
US1364493A (en) * 1918-02-28 1921-01-04 Ford Bruce Method of making storage-battery separators
US1972433A (en) * 1930-12-22 1934-09-04 Expanded Metal Separator for accumulators
FR1057349A (en) * 1952-05-24 1954-03-08 Electrical accumulator for separator
FR1067287A (en) * 1952-11-29 1954-06-14 A battery separator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE274353C (en) *
US1364493A (en) * 1918-02-28 1921-01-04 Ford Bruce Method of making storage-battery separators
US1972433A (en) * 1930-12-22 1934-09-04 Expanded Metal Separator for accumulators
FR1057349A (en) * 1952-05-24 1954-03-08 Electrical accumulator for separator
FR1067287A (en) * 1952-11-29 1954-06-14 A battery separator
NL259158A (en) * 1959-12-17

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206032A1 (en) * 1985-06-12 1986-12-30 Forschungszentrum Jülich Gmbh Electrolyser with a diaphragm electrode sandwich assembly, and assembling apparatus suited therefor

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