Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
  • C25B9/70—Assemblies comprising two or more cells
  • C25B9/73—Assemblies comprising two or more cells of the filter-press type
  • C25B9/75—Assemblies comprising two or more cells of the filter-press type having bipolar electrodes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
  • C25B11/036—Bipolar electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

• the present invention relates to a new bipolar assembly for filter press electrolyser.
• Hydrochloric acid in the following description, is an important by-product generated in a large amount by a number of industrial processes, among which particularly important are the synthesis of vinyl chloride by dichloroethane pyrolisis, followed by polymerisation to polyvinylchloride (PVC), and of several isocyanates which reacted with glycoles permit to obtain the family of polyurethanes, increasingly employed for the production of paints and of expanded cell materials prized for thermal insulation systems, such as insulation for refrigerators and walls of buildings.
• PVC polyvinylchloride
• Such electrolysis can be carried out according to two technologies respectively based on the utilisation of gaseous hydrochloric acid (this being the physical state in which HCI is formed by dichloroethane pyrolisis and isocyanate synthesis) or of an aqueous solution of HCI obtained by sending the gaseous HCI to a water-fed absorption column.
• gaseous hydrochloric acid this being the physical state in which HCI is formed by dichloroethane pyrolisis and isocyanate synthesis
• aqueous solution of HCI obtained by sending the gaseous HCI to a water-fed absorption column.
• Such column is an equipment normally present in the plants that generate HCI as a by-product, since the aqueous solution practically represents the only way through which commercialisation can be effected.
• the two walls of the cathodic and anodic compartment of two adjacent cells can be put in mechanical and electrical contact either by means of a suitable compression (a concept known to the experts of the field as "single cell") or through a connection by suitable clamping elements, such as nuts and bolts or welds (bipolar assemblies).
• a suitable compression a concept known to the experts of the field as "single cell”
• suitable clamping elements such as nuts and bolts or welds
• peripheral flanges are in fact obtained either by press-shaping or by folding of the sheets that constitute the compartment walls: such operation gives in general satisfying results with low percentages of rejects for insufficient planarity or mechanical defects since each wall is worked to form only its own flange, cathodic or anodic respectively.
• the wall must be subjected, operating with the known procedures, to a double forming since both flanges, cathodic and anodic, are necessarily parts of the same wall.
• the present invention describes a design of bipolar assemblies comprising a single separating sheet with the dual function of anodic wall and cathodic wall made of corrosion resistant metal or metal alloy, and provided with an anodic perimetral flange and a cathodic perimetral flange; at least one of said perimetral flanges is made by a pre-formed element, and is not made out of press- shaping or folding the separating wall.
• the cathodic and the anodic perimetral flange are obtained by combining the folding of the peripheral portion of the sheet with a frame made out of a rod or a tube, both having a quadrangular section, made of a material of equivalent type as that of said sheet.
• one of the flanges is obtained by folding the peripheral portion of the sheet, and the other is a pre-formed flange welded to the sheet itself: a reinforcing element is preferably interposed between the two flanges.
• the anodic perimetral flange and the cathodic one constitute a generally U-shaped pre-formed integral element, welded to said separating sheet; preferably, a reinforcing element is interposed between the anodic and the cathodic peripheral flange.
• the pre-formed integral element is obtained by folding of a second sheet, or by welding of two pre-formed flanges.
• the invention is directed to a method of catalytic activation of a bipolar assembly comprising at least one electrode, and preferably a couple of electrodes, fixed to the two anodic and cathodic faces of the sheet.
• said bipolar assembly subjected to catalytic activation is a newly manufactured assembly.
• said bipolar assembly is a previously catalysed assembly already, operated in an electrolyser, whose, catalytic activation, exhausted, is restored by reactivation.
• the invention is directed to. an electrolyser comprising a multiplicity, of bipolar assemblies according to one of the above described embodiments.
• Fig. 1 represents a cross-section of a bipolar assembly in which the two walls, anodic and cathodic, are separated and mutually fixed and the perimetral flanges are realised by folding of each wall as disclosed in the prior art.
• Fig. 2 outlines the cross-section of a bipolar assembly whose anodic and cathodic walls are made of a single sheet and the two perimetral flanges are realised following the procedures of the prior art.
• Fig. 1 represents a cross-section of a bipolar assembly in which the two walls, anodic and cathodic, are separated and mutually fixed and the perimetral flanges are realised by folding of each wall as disclosed in the prior art.
• Fig. 2 outlines the cross-section of a bipolar assembly whose anodic and cathodic walls are made of a single sheet and the two perimetral flanges are realised following the procedures of the prior art.
• Fig. 1 represents a cross-section of a bi
• FIG. 3 shows the cross-section of a bipolar assembly whose anodic and cathodic walls are made of a single sheet and the two perimetral flanges are manufactured, according to a first embodiment of the invention, respectively by the folding of the peripheral portion of the sheet and with a rod or tube, both having quadrangular section, worked in such a way as to form a frame and made of a material of equivalent type as the one of the single sheet.
• Fig. 4 reports the cross-section of a bipolar assembly whose walls are made of a single sheet and the two perimetral flanges are manufactured, according to a second embodiment of the invention, respectively by folding of the peripheral portion of the sheet and by welding of a pre-formed flange of a material equivalent to the one of the sheet.
• Fig. 5 illustrates a further embodiment of the invention in which the sheet, having the dual role of anodic and cathodic wall, is not folded in its peripheral portion and is welded to a single pre-formed frame with U-shaped section of a material equivalent to the one of the sheet.
• Fig. 6 shows a variant of the embodiment of fig. 5 in which the pre-formed frame is made of two shells welded together so as to form a piece with U-shaped section provided with an inner edge whereto the sheet is welded in its turn.
• Fig. 7 outlines the assembly of fig. 3 completed with supports and electrodes in form of punched or expanded sheets or meshes.
• Figs. 8A and 8B reproduce a three-dimensional image of the assembly of fig. 7 according to the views from the two sides.
• Fig. 1 and fig. 2 show two cross-sections of a bipolar assembly corresponding to the design according to the prior art in case the anodic and cathodic walls are two distinct sheets and a single sheet respectively.
• the essential constructive elements of the assembly are indicated, wherein 1 and 2 are the separate anodic and cathodic wall, 3 the welds providing to ensure the mechanical stability and the electrical continuity needed to allow the passage of the electric current, 4 the surface of the anodic flange, 5 the surface of the cathodic flange, 6 a perimetral reinforcing element made of a metal or plastic material rod suitable to guarantee that the flanges may be compressed without deformations or deflections taking place, 7 the gaskets, respectively anodic (at the left) and cathodic (at the Tight), which seal the perimetral surface of both flanges under compression hindering the leakage of the fluids contained in he anodic and in the cathodic compartments;
• an embodiment according to the prior art is outlined in case the two walls of the adjacent anodic and cathodic. compartments are constituted by a single v sheet. Based on this kind of construction the peripheral portion of the single, sheet is subjected to a sequence of folds, at least five or preferably six as shown in the figure, around the perimetral reinforcing element to form the two flange surfaces, anodic and cathodic.
• 1 is the single sheet covering at the same time the roles of walls 1 and 2 in fig. 1
• 4 is the anodic flange surface
• 5 is the cathodic flange surface
• 6 is the perimetral reinforcing element with the same functions of the one of fig.
• Fig. 3 shows a first embodiment according to the invention of the assembly wherein the walls of the two adjacent anodic and cathodic compartments consist of a single sheet 1 and the peripheral portion of said single sheet 1 is folded so as to form the surface 4. only of the anodic flange (as preferred in the .
• frame 14 is made of a rod, or preferably of a tube with polygonal section, preferably quadrangular, to decrease the, amount of material resistant to corrosion, and thus expensive, and moreover the weld 9 can optionally be a double weld as shown in the figure to ensure a higher reliability towards the possible leakage of the fluid contained in the cathodic compartment to the external environment.
• This first constructive alternative according to the invention allows to maintain the mechanical folding stresses within very low levels, certainly not able to generate defects in the material of the sheet.
• the quality of the weld or welds 9 and suitable speeds and production costs are guaranteed by adequate clamping equipment for the various pieces and by the modern automated welding techniques, in particular the laser technique. Examining fig.
• the folded sheet - frame assembly creates a crevice 15 in which the process liquid could infiltrate and stagnate: this situation does not cause in general any particular inconvenience, with the exception of the specific case in which such liquid contains chlorides and in particular it is acidic and at a temperature higher than ambient, as effectively happens in the case of hydrochloric acid solution electrolysis, In this situation a corrosive attack confined within the crevice zone may in fact develop.
• the protection against this type of attack is effected either selecting a material characterised by higher resistance, for instance in the mentioned case of hydrochloric acid solution electrolysis the use of titanium - 0.2% palladium alloy instead of titanium, or applying a thin protective film to the crevice zone.
• These films well known in the electrochemical technology, generally contain small amounts of noble metals, such as platinum, ruthenium or iridium, or oxides thereof.
• Fig. 4 shows a variation of the embodiment of fig. 3 having the purpose of avoiding the use of the frame 14. made of a rod or tube with quadrangular section made with corrosion resistant material.
• the assembly always as a cross-section, comprises again the single sheet 1 with the peripheral portion folded to form only the anodic flange 4 as already seen in fig. 3, with the difference that the frame 14 of corrosion resistant material is replaced by a further pre-formed flange 5 which acts as cathodic flange and is welded to the sheet 1 through weld 10, performed with an automated procedure, preferably with the laser technology.
• the weld 10 can be realised as a double weld (not shown in the figure).
• the perimetral reinforcing element does not come in contact with any corrosive fluid and is therefore manufactured with a low cost material, e.g. carbon steel.
• a low cost material e.g. carbon steel.
• the embodiment of fig. 4 allows a saving of expensive material, being on the other hand more delicate as regards the final planarity of the piece, important to facilitate the assemblage of the electrolysers.
• FIG. 5 A further constructive alternative of the assembly of fig. 4 is given in fig. 5 where the single sheet 1 is not folded in its peripheral portion and the two surfaces of the anodic 4 and cathodic 5 flanges are obtained by means of a pre-formed perimetral element with U-shaped section that is welded to the single sheet with the weld 11.
• the construction material of the reinforcing 10 element 6 is not critical: carbon steel is totally suitable.
• fig. 6 outlines an embodiment of the invention as a cross-section wherein the perimetral piece with U-shaped section discussed in the context of fig. 5 is pre- manufactured by welding two shells obtained from two metal strips with only two foldings: the assembling weld 12 of the two shells can be single or it can be double in 30 case one wants to ensure a high reliability against infiltrations.
• the so pre- manufactured element is worked for instance in a press to obtain a high planarity.
• the piece presents a free edge protruding respect to the weld 12: this edge, whose requirements are to be straight and free of defects such as cutting barbs, is welded head-to-head (weld 13) to the edge of the sheet 1.
• This type of embodiment is less advantageous compared to the one described in fig. 5 essentially for the additional steps represented by the execution of the weld 12 and the pressing to restore the piece planarity required after the deformations induced by the welding procedure: on the other hand the press working ensures an adequate planarity also after effecting the weld 13.
• This last weld which is inevitably single as weld 11 of the assembly of fig. 5, is however easier to effect (the two edges to be joined are in a head-to-head position, while in the assembly of fig. 5 the surface of the perimetral piece with U-shaped section and the edge of the sheet are positioned at 90°).
• This ease of execution guarantees a high probability of absence of defects, which on the other hand as above said are at least in part tolerable.
• the welding be of automated type, preferably with laser technology.
• the assemblies outlined in figs. 3, 4, 5 and 6 must be completed with the' relative anodes and cathodes: these are normally constituted by punched or expanded sheets or meshes of corrosion resistant metal or metal alloy, preferably provided with a thin superficial film of electrocatalytic material.
• Fig. 7 reproduces a cross-section of the assembly in fig. 3 wherein the anode 17 and the cathode 18 have been installed by fixing, e.g. welding, on adequate supports 16 in their turn connected to the wall 1 preferably by welding.
• fixing e.g. welding
• the assembly of fig. 7 is reproduced in a three-dimensional representation in figs. 8A (view from the anode side) and 8B (view from the cathode side).
• the fixing by welding of the sheets or meshes previously provided with the electrocatalytic film results rather critical as in the welding zones the electrocatalytic film material is embedded in the molten zone with possible contamination and consequent generation of defects such as porosity and/or brittleness.
• the assembly of fig. 3 is characterised by being made of parts having the same thermal expansion coefficient and thus the assembly may be exposed to high temperatures without risks of distortion.
• the important consequence of this characteristic is that the new assemblies may be equipped with sheets or meshes free of electrocatalytic films (with a substantial simplification of the welds to the supports 16): in a subsequent phase the whole assemblies are subjected to the procedure of application of the electrocatalytic films to the sheets or meshes with the relative high temperatures.
• exhausted assemblies are treated to eliminate the remnants of the old electrocatalytic films, e.g. by means of sandblasting or chemical washing, then subjected to the application of new films according to a procedure that matches exactly the one utilised for new assemblies.
• a further advantage of the application of the electrocatalytic films to the assemblies including the punched or expanded sheets or meshes is given by the absence of damages to the films necessarily induced by the fixing welds on the sheets or meshes previously provided with the film according to the prior art.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Electrodes For Compound Or Non-Metal Manufacture (AREA)
• Filtration Of Liquid (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

Priority Applications (11)

Applications Claiming Priority (2)

Publications (2)

Family

ID=11447040

Family Applications (1)

Country Status (16)

Cited By (1)

Families Citing this family (5)

Family Cites Families (14)

• 2001
  • 2001-02-28 IT IT2001MI000401A patent/ITMI20010401A1/it unknown
• 2002
  • 2002-02-28 DE DE60201510T patent/DE60201510T2/de not_active Expired - Lifetime
  • 2002-02-28 BR BRPI0207728-0A patent/BR0207728B1/pt not_active IP Right Cessation
  • 2002-02-28 EP EP02729944A patent/EP1366212B1/en not_active Expired - Lifetime
  • 2002-02-28 KR KR1020037011342A patent/KR100845727B1/ko not_active Expired - Fee Related
  • 2002-02-28 PL PL363678A patent/PL205527B1/pl unknown
  • 2002-02-28 RU RU2003128979/15A patent/RU2280104C2/ru active
  • 2002-02-28 US US10/466,782 patent/US6998030B2/en not_active Expired - Lifetime
  • 2002-02-28 CA CA002438028A patent/CA2438028C/en not_active Expired - Fee Related
  • 2002-02-28 AT AT02729944T patent/ATE278821T1/de active
  • 2002-02-28 CN CNB02805461XA patent/CN1257316C/zh not_active Expired - Lifetime
  • 2002-02-28 ES ES02729944T patent/ES2229144T3/es not_active Expired - Lifetime
  • 2002-02-28 MX MXPA03007711A patent/MXPA03007711A/es active IP Right Grant
  • 2002-02-28 WO PCT/EP2002/002204 patent/WO2002068718A2/en not_active Ceased
  • 2002-02-28 JP JP2002568808A patent/JP4088527B2/ja not_active Expired - Lifetime
  • 2002-02-28 AU AU2002302375A patent/AU2002302375A1/en not_active Abandoned

Also Published As

Similar Documents

Legal Events