FILTERPRESSTYPE ELECTROLYTIC-CELL BLOCK FOR WATER ELECTROLYSIS

Abstract: The filterpresstype electrolytic-cells of the present in­ vention differentiate themselves from that presently available in the art by a modular structure and thus in that they are more simple and easy to be assembled. The mechanical elements (4) (5) (6) constituting the elec­ trolytic cells (CE) are mechanically identical to constituting the condenser chambers (C) which are intended for conden­ sating the steam present in the oxygen and the hydrogen there produced by electrolysis. The cooling, e.g. by air, of both the electrolytic cells (CE) and the condenser cells (C) is realised by using suitable pas­ sageways (5) provided within the electrodes elements (4) folded in U-form; said electrodes elements (4) ensuring a separating function and providing the cooling function in the condenser cells. The channels for the distribution of the electrolyte and for the withdrawal of the produced gases are formed by the compression to which are submitted cylindrical rings (6/1C, 6/2C) showing slits, provided in the structure of suitable spac­ ing frames (6/1, 6/2) which allow the building up of the cells.

Description: The present invention refers to filterpresstype electrolytic-cells intended for producing either hydrogen and oxygen separately or both gases mixed together according to precise stoichiometric proportions and incorporating means for cooling said cells and for condensating the steam present in the produced gases. More particularly it is an object of the present invention to provide a filterpresstype electrolytic-cells made by interchangeable elements of standard type. A further object of the present invention is a compact mobile plant of reduced power for providing limited quantities of said gases to be employed e.g. in oxy-hydrogen welding, in oxygen cutting, for producing therapeutic oxygen, for producing hydrogen and any way every time it is necessary to provide, for direct utilisation, either oxygen and hydrogen or their mixture in stoichiometric proportions. It is known that the electrolytic cells for H₂O electrolysis are of two basic types: a) cells having monopolar electrodes which may be further distinguished in bell-cells, diaphragm-cells and bell-diaphragm cells; b) cells having bipolar electrodes which may be further distinguished in tank-cells and filterpresstype-cells. It is also known that the cells having bipolar electrodes show, against the cells having monopolar electrodes, the following advantages: 1) for the same production capability and energy consumption, they need less floor space; 2) they allow an higher current density which make them highly qualified for the production of deuterium; 3) they may work under a pressure higher than the atmospheric avoiding consequently any auxiliary pump; 4) they avoid the parallel connection which is on the contrary required by the cells having monopolar electrodes. From the European Patent Application No. 0045583 it appears that a device already exists for electrolysis in which the electrolyte runs from one cell to the other in a circular form, and in which the cooling of the gases produced is carried out only in one group of cells which are interchangeable with electrolytic cells, but not connected to an electrical current. The temperature of the electrolytic cells increases in linear form as shown in the diagram in figure 1a attached to the said Patent Application, and the temperature of the electrolytic cells is different from one to the other; the cooling of the electrolytic cells is not equal for all the cells, but is carried out by groups of cells. It is hence the main object of the present invention to provide filterpresstype electrolytic-cells which make it possible to achieve a larger production of oxygen and hydrogen while requesting the same energy consumption and the same manufacturing expenses as the cells presently produced and proposed by the market. A further object of the present invention is to provide a interchangeable standard structure for said filterpresstype electrolytic-cells in order to reduce the manufacturing expenses of said filterpresstype electrolytic-cells, while simplifying the withdrawal of the gases produced by the electrolysis. In order to achieve the hereabove objects, the filterpresstype cells according to the present invention defined in Claim 1 solve the following problems: 1) the same modular mechanical elements are used for assembling both the electrolytic cells self and the condenser chambers intended for condensating the steam present in the produced gases; 2) the cooling by air of said cells is ensured by passageways realised in the electrodes themselves; 3) the cooling by air of the condenser is ensured by using the same passageways in the electrodes as already mentioned in preceding point 2, which electrodes in this case ensure the function of separating elements between the successive condensation chambers; 4) the gases at the output from the condenser cells, are in a state that the steam has been condensed in the meantime. 5) any suitable number of cells can be assembled in series. 6) special spacers of an extremely low price are placed between the electrodes to allow the construction of the half-cells, of the condensation chambers, of the channels for distributing the electrolyte and of the channels for collecting the gases by the electrolysis; 7) the body constituting the condenser is assembled and connected to one end of the body constituting the electrolytic cells in such a way as to form a unique body; 8) the same cells are used for producing either oxygen and hydrogen separately or their mixture according to stoichiometric proportions. By way of non-exhaustive example, some of the preferred embodiments of the present invention will now be described with reference to the accompanying drawings whereby: fig. 1 shows a group of electrolytic cells having an asbestos diaphragm and intended for producing oxygen and hydrogen separately; fig. 2 shows a group of electrolytic cells intended for producing said gases mixed together according to stoichiometric proportions; fig. 3 shows a group of condenser cells forming a condenser; fig. 4 shows an example whereby the electrolytic cells and the condenser cells are assembled together in serial relationship; fig. 5 shows two embodiments of spacing frames used in assembling the half-cells; fig. 6 shows the functionning of the two frames of fig. 5 and, fig. 7 is an overall sight of a single body plant comprising both the electrolytic cells and the condenser cells. As shown in Fig. 1, the basic electrolytic cell for producing oxygen and hydrogen separately comprises the following modular elements disposed according to the following assembling sequence: a) a first aluminium end-plate 1 which cooperates with a second identical aluminium plate at the other end for compressing and firmly maitaining the plurality of cells in between (tie-rods, not shown, are provided to exerce said compression); b) a plastic frame 2 having four input-output pipes made in MOPLEN® or any other suitable plastic material; c) a plastic plate 3 having tighting functions, bored likewise the aluminium end-plates 1 and made e.g. in MOPLEN®; d) an electrode 4 represented by a metal plate fold in U-form and intended to be connected either to the positive or to the negative output of a DC power supply; e) a spacer 5 to be inserted inside the electrode 4 fold in U-form; the frame of said spacer 5 is so shaped as to form a plurality of openings which constitute the passageways for the cooling fluid e.g. air; f) a first spacing frame 6/1 to form the input-output channels of the first half-cell; g) an asbestos diaphragm 7 providing for the separation of the hydrogen from the oxygen; h) a second spacing frame 6/2, substantially symmetric of the first spacing frame 6/1, to form the second half-cell and the relative input-output channels for the circulation of the electrolyte and the withdrawal of the produced gases; i) a second electrode i.e. a metal plate 4 fold in U-form, identical to that one described in point d) and then the structure reproduces itself periodically. Some peculiar details of the separating frames 6/1 and 6/2 are shown in Fig. 5. Each one of said frames is provided with four cylindrical rings 6/1a, 6/2a in form of a cylindrical collar and with two toggle loops 6/1b, 6/2b to allow the passage of tie rods (not shown) which are intended to exerce a pression on a plurality of cells when said plurality of cells is mounted after each other in serial relationship so as to form a complete plant. In each of said frames 6/1, 6/2 respectively two diagonally opposed of said cylindrical rings 6/1a, 6/2a show respectively slits 6/1c, 6/2c whose function is to provide a top and a bottom input-output channel respectively. The channel located at the top serves to the transport of one of the gases produced by the electrolysis while the channel located at the bottom serves to introduce the electrolyte in the half-cell. Each of the four cylindrical rings 6/1a, 6/2a of each frame is further provided with bushes 6/1d, 6/2d acting as washers in order to provide a better tighting of the four input-output channels builded up by the slits in each of said four cylindrical rings of each frame when pressed against the corresponding cylindrical rings of the next following frame. The slits 6/1c in the cylindrical rings 6/1a of the frame 6/1 are provided on the same side of said frame where also the bushes 6/1d are; while in the cylindrical rings 6/2a of the frame 6/2 the slits 6/2c are provided on the opposite side to that where the bushes 6/2d are pojecting therefrom. The reasons for this peculiar form is to be found in that frame 6/1 is resting against the surface of the adjacent electrode 4 with that surface where the bushes 6/1d are projecting therefrom; while the frame 6/2 is resting on the surface of the next adjacent electrode 4 with its surface opposite to that where the bushes 6/2d are projecting therefrom. Hence the presence of the asbestos diaphragm 7 would provide an occlusion of the input-output channels provide by slits 6/1c, 6/2c if the frames would have had to rest against the surface of said asbestos diaphragm 7 on the same side where said slits 6/1c, 6/2c are provided. The input-output channels build up by slits 6/1c, 6/2c allow the distribution and the circulation of the electrolyte inside the electrolytic cells and provide the ways for withdrawing the oxygen and the hydrogen produced alternatively, i.e.: in one half-cell the electrolyte is introduced through the channel located at the left-hand corner; while in the next following half-cell this happen through the channel located at the right-hand corner, both said channels being located at the bottom of said frames and of the compound structure when assembled, (fig. 7). Similarly in one half-cell oxygen is withdrawn while in the next following half-cell hydrogen is withdrawn through the respective input-output channels, both these later channel being on the top of said frames and of the compound structure when assembled, (fig. 7). A group of condenser-cells (shown in fig. 3) is build up by an assembly of cells mechanically identical to the hereabove described cells for electrolysis purposes. These condenser-cells differentiate themselves from the cells for effective electrolysis purposes only in that the respective electrodes 4 are not connected to whatever polarity of whatever DC power supply. Said electrodes, in the condenser-cells, are not connected to DC; they have only function of hydraulic separating, tighting element and simultaneously the function of cooling surfaces, i.e. no electrical function. Moreover the asbestos diaphragm 7 may be and is normally omitted; it has to be maintained where the two gases are intended to be produced separately. Hence the basic element for condenser-cells comprises: an element exactly alike to electrode 4 i.e. a first metal sheet 4 fold in U-form with the spacing frame 5 inside which allows the cooling air to circulate inside said tighting and cooling means 4, a first plastic frame 6/1 to build up the first condensing half-cell, a second metal sheet fold in U-form exactly alike to electrode 4, with its spacing frame 5 inside, or, in an alternative embodiment, a simple metal sheet 4a (as shown in fig. 2), a second plastic frame 6/2 to build up the second condensing half-cell which is followed by a third metal sheet fold in U-form 4 and so on. The condenser body is terminated with a tighting plastic end-plate 3, a frame 2 with four output pipes made e.g. in MOPLEN® and an aluminium end-plate 1 to allow the compression of the whole by means of tie rods (not shown). In the condenser chambers the gases to be condensed travel through a zig-zag diagonal path in order to increase the time said gases will remain in contact with the cooled metal surfaces of metal sheets 4. The gas to be condensed enters one of the input-output channels and, after the steam has been condensed, travels to the diagonally opposite channel from which it is withdrawn to be introduced in a device for recuperating the condensed steam. The production of oxygen and hydrogen mixed in stoichiometric proportions takes place in electrolytic cells as shown in Fig. 2. Said cells differentiate themselves from that wherein oxygen and hydrogen are produced separately only in that the asbestos diaphragm 7 is omitted and in that, if the cooling is per se sufficient, a simple metal sheet 4a may be used as electrode 4 instead of the normal electrode represented by a metal sheet fold in U-form and having inside the spacer 5 constituting passageways for the cooling fluid. The hydrogen and oxygen so produced in each half-cell may be indifferently withdrawn either through the channel on the left-hand side or through the channel located on the right-hand side. Fig. 4 shows an example of assembly whereby the group of electrolytic cells and the group of condenser cells are mounted after each other in serial relationship. The group of condenser cells C shows: the aluminium compression plate 1; the plastic frame 2 with its four output pipes; the plastic tighting plate 3 made e.g. in MOPLEN®; the first separating element represented by the electrode 4 fold in U-form and having inside the spacer 5 which provides the passageways for the cooling fluid; the plastic frame 6/1 to provide the input-output channels for the gases submitted to condensation; the second separating and cooling element i.e.: the metal sheet 4 fold in U-form with its spacer 5 inside; said second separating and cooling element 4 completes the first condenser half-cell. Then the structure repeates itself periodically untill a suitable number of condenser cells is so assembled. The group of electrolytic cells CE shows: the plastic tighting plate 3 which ensures the tighting between the block of condenser-cells C and the block of electrolytic-cells CE; the first electrode 4, represented by a metal sheet fold in U-form and connected to one of the polarities of the DC power supply; said electrode 4 has inside the spacer 5 to build up the passageways for the cooling fluid; the first plastic frame 6/1 to form the first half-cell and the relative input-output channels for the circulation of the electrolyte and the withdrawal of the there produced gas; the asbestos diaphragm 7 having the separating function for the two gases; the plastic frame 6/2 to form the second half-cell and the respective channels for the electrolyte and the gases; the second electrode 4 fold in U-form, connected to the other polarity of the DC power supply and having its spacer 5 inside to provide the cooling function; the second plastic frame 6/1 to form the third half-cell and then the structure repeates itself periodically. In Fig. 7 is schematically shown an assembly containing a group of electrolytic-cells CE and a group of condenser-cells C, whereby it is to be appreciated that the condenser block C is mounted in serial relationship with the electrolytic cells block CE so as to form a single body plant of homogeneous design and showing a substantially parallelepiped form. The electrolyte is introduced in the channels on the bottom of one end of said single body plant. The produced gases travel toward the other end of the electrolytic cells block CE and, after having been introduced in the block of condenser cells C, each in a different half-cell, they are withdrawn through the channels on the bottom at the end of the condenser block C; the steam present in the produced gases having been condensed in the meantime. The paths travelled by the hydrogen and the oxygen in each grow up of half-cells are shown in detail in Fig. 6, whereby it is to be appreciated that the hydrogen enters each cell through the channel formed on the top by the cylindrical rings shown on the right-hand side in Fig. 5, while the oxygen enters each cell through the channel formed by the cylindrical rings shown on the left-hand side in said Fig. 5. Similarly happens for the electrolyte which enters each cell alternatively through the channels provided on the bottom and diagonally opposed to the channels through which the gases enter each cell. While the forms of the mechanical elements constituting the modular structure, object of the present invention, herein described constitute some preferred embodiments of the present invention, it is to be understood that the invention is not limited to these precise forms of said mechanical elements and that many changes may be made therein e.g.: in the form and to the location of the slits 6/1c, 6/2c; in the form of the plastic plates 2 and 3, and finally in the form and structure of the spacer 5 inside the electrodes 4 (provided that this later, in cooperation with the electrodes 4, allows a good ventilation for the cooling function) without departing from the scope of the invention which is defined in the appended claims.

Claims: "A filterpresstype electrolytic cell block for water electrolysis", assembled together with a block of condenser cells so as to form a single homogeneous body showing nearly parallelepiped form, the electrolytic cells being interchangeable with the condenser cells, the electrolytic cells being connected in series and working at a pressure higher than that of the atmosphere, each cell including: A- a) an electrode (4) formed by a U shaped metal plate; b) a spacing frame (5) to introduce within the plate described in point a), the spacing frame being constructed in such a way as to form a multiplicity of channels for the passage of the cooling fluid, for example air; c) a first elastic frame (6/1) to form the input channel of the electrolyte in the bottom of the cell, and on the top, an output channel diametrically opposite for one of the gases; d) an asbestos diaphragm (7) to separate the hydrogen from the oxygen when the obtaining of the H₂ and O₂ mixture is not wanted; wherein the space confined between the oppositely disposed plates of two neighbouring U-shaped electrodes (4) is utilized for carrying out the electrolysis of water and is separated by the U-shaped electrode plates from the space confined between the plate-pair constituting said U-shaped electrode (4); e) a second spacing frame (6/2) to form the second half-cell and the relative input and output channel for the entry of the electrolyte and the discharge of the other gas produced by electrolysis; B- a group of condenser cells formed with part of the same elements which, in repeating series, constitute the electrolytic cells but without electric connections, that is the U-form plate (4), the spacing frame (5), the plastic frames (6/1) and (6/2); the cooling of the electrolytic and condenser cells being carried out simultaneously for all the above-mentioned cells, by means of air or another fluid forced through the spaces of each metal plate (4), acting both as an electrode or, alternatively, as a separating element, the above-mentioned metal plates (4) being U shaped for that reason around a spacing frame (5) in order to form the spaces through which the cooling fluid passes. "A filterpresstype electrolytic cell block" according to claim 1, in which the electrolytic cells are interchangeable with condenser cells and in which the electrolyte is static, that is, it does not run from one cell to the other, characterized by the fact that the electrolytic cells are cooled simultaneously, and also by the fact that in condenser cells the gases are cooled to a temperature lower than that of the electrolytic cells. A filterpressstype electrolytic cell block according to Claim 1 whereby the mechanical elements which are common to the structure of both the electrolytic and the condenser cells are: a) the metal plates (4) used alternatively as electrodes or as separating means but in both cases as cooling means; b) two different types of plastic spacing frames (6/1, 6/2) substantially symmetric to be inserted between electrodes (4) of different electrical polarity in the blocks of electrolytic cells or alternatively between the separating elements (4) in the condenser cells; c) aluminium end-plates (1) intended to press together the individual electrolytic and condenser cells by means of tie rods; d) the plastic frame (2) provide with four pipes to build up the input-output channels for the gases and the electrolyte; e) tighting plates (3) of a suitable plastic material to ensure tighting at the end of each block of cells; said tighting plates (3) showing four holes and two toggle loops to allow the passage of the tie rods which press the blocks of cells together. A filterpresstype electrolytic cell block according to any preceding claim whereby the channels through which travel separately the hydrogen and the oxygen produced by the electrolysis, and the channels through which the electrolyte is supplied are formed by the cooperation of cylindrical rings (6/1a, 6/2a) of the spacing frames (6/1, 6/2) which form the half-cells and the similar cylindrical rings in the structure of the spacer (5), as a result of the compression exerced on the block of cells by end-plates (1); said channels being accessible through passageways formed by slits (6/1c, 6/2c), in the surface of said cylindrical rings (6/1a, 6/2a), and the surfaces of said metal plates (4) constituting the electrodes of the electrolyticcells or alternatively the separating elements of the condenser cells; said half-cells being provided with an asbestos diaphragm (7) to ensure the separation of the oxygen from the hydrogen thereby produced. A filterpresstype electrolytic cell block according to claim 4 whereby each of said spacing frames (6/1, 6/2) comprises a rectangular frame (6/1e, 6/2e), four cylindrical rings (6/1a, 6/2a) each provided with a bush (6/1d, 6/2d), two toggle loops (6/1b, 6/2b); said spacing frames (6/1, 6/2) being substantially symmetric and differentiating from each other only in the relative position of the slits (6/1c, 6/2c), intended to form the channels allowing the incoming of the electrolyte and the incoming-outcoming of the gases; the first one of said frames (6/1), looked at from that side where the bushes (6/1d) project outside, being provided with a first slit (6/1c) in the body of the cylindrical ring (6/1a) located at the upper right corner and with a second slit (6/1c) in the body of the cylindrical ring (6/1a) located at the lower left corner of said spacing frame (6/1); both said slits (6/1c) being located on the same side frame (6/1) where said bushes (6/1d) project therefrom, to form the channels respectively for the passage of the gases and of the electrolyte when said frame (6/1) is pressed against the surface of the metal plate (4) or alternatively of a simple metal plate (4a); the second of said frames (6/2), looked at from that side where the bushes (6/2d) project outside, being provided with a first slit (6/2c) in the body of the cylindrical ring (6/2a) located at the upper left corner and with a second slit (6/2c) in the body of the cylindrical ring (6/2a) located at the lower right corner of said spacing frame (6/2); both said slits (6/2c) being located on that side of said frame (6/2) opposite to that where said bushes (6/2d) project therefrom, to form the channel respectively for the passage of the gases and of the electrolyte when said frame (6/2) is pressed against the surface of the metal plate (4) or alternatively of a simple metal plate (4a). A filterpresstype electrolytic cell block according to claim 5 whereby the accessway to said inputoutput channels formed by said cylindrical rings (6/1a, 6/2a) located at the top of each of said spacing frames (6/1, 6/2) is not provided from each half-cell; said accessway is rather provided to the left-hand channell or to the right-hand channel according to the fact that in the considered cell, the cylindrical ring provided with a slit is that one located at the left-hand side or at the righthand side, the incoming or outcoming of the channels formed by the cylindrical rings located at the bottom of said frames (6/1, 6/2) also happening according to the position of the related slit, similarly to what happens with the channels located at the top of said frames (6/1, 6/2).

Inventors: BELLIA, NICOLO' GIUSEPPE, DOTT. ING.
Applicants: VISCOBELL S.P.A.
Application year: 1984
Main classification: C25B9
IPC codes: C25B9