MXPA01003830A - High pressure electrolyser module - Google Patents

Abstract

A high pressure electrolyser as represented in the figure, having a number of electrolysis chambers being held in frame (1), being separated by membrane (2) to which the electrodes (3) are pressed. The electrodes are electrically connected to the bipolar plate (4) with a metal woven sheet (5). The frame has the larger conduit openings (7) on the top side and (8) on the bottom side. Conduit openings (7) evacuate the gas that is generated and openings (8) form a supply channel of electrolyte. Opening (7) is connected tothe electrolyser module's inner space with the small connecting conduit (9) and similarly opening (8) is connected to the inner space via small connecting conduit (10). A ring shaped frame having conduit openings for the supply of electrolyte and the removal of the gasses that are generated and further having a connecting surface with concentric elevations and depressions.

Description

HIGH PRESSURE ELECTROLYZER MODULE DESCRIPTIVE MEMORY The present invention relates to a high pressure electrolyzer module of the filter press type for the electrolytic production of gases and also relates to an electrolyser comprising said module. The electrolysers of the filter press type comprise a so-called electrolyser module and a number of peripheral elements such as degassing chamber, a water supply unit and possibly a transformer / rectifier and the pipeline necessary to connect the different parts of the electrolyser. An electrolyser module comprises a series of stacked, alternately cathodic and anodic electrolysis chambers. Each camera supports either one or more anodes or cathodes. The electrolysis chambers are separated from each other by membranes or selectively permeable diaphragms. A combination of a cathodic camera and an anodic camera form an electrolysis cell. In each chamber, the electrodes are mounted vertically, preferably in close contact with the membranes. This can be achieved, for example, by pressing the membrane between the electrodes. Membranes that are particularly suitable for this purpose have been described in EP-A-0 232 923. The electrolysis chambers are supported together by a frame which forms the outer wall of the electrolyser and can have a variety of shapes, polygonal, example square, rectangular or circular. Ultimately, the frame is in fact shaped like a ring or cylinder. The separation membrane is fixed to the frame together with the electrodes. The frames are made of a material that is inert to the electrolyte and can be made, for example, of metal, covered by a suitable non-conductive layer, or they can be made of a suitable inert non-conductive material such as synthetic material. A frame made of metal covered by a flexible vulcanizable material is known from WO-97/00979. In each electrolysis chamber, the electrodes have to be linked by a suitable conductor. In a particular embodiment, this can be done by contacting the electrode with a metal woven sheet, which in turn makes contact with a metal plate that is mounted on the frame; said plate being referred to in the art as a bipolar plate. The gas that is generated is conducted to a degassing chamber, normally placed on the electrolyzer unit, where the gas is collected and separated from the electrolyte transported with the gas. The degassed electrolyte is recycled back to the electrolysis chambers and the gas that is collected can be pressurized and stored in suitable pressure vessels. The electrolysis chambers can be connected to external tubes leading to or coming from the degassing chamber for the circulation of the generated gases or the electrolyte, respectively. Or the frames of the electrolysis chamber may have suitable conduits on its upper side and on its lower side. The upper duct aims to evacuate the gas-electrolyte mixture that is generated during electrolysis and the lower duct allows the electrolyte to enter. The gas-electrolyte mixture that is generated is pumped through the upper conduit to a tube leading to the degassing unit from which the degassed electrolyte is pumped back to the lower conduit in the frame from which enter the electrolysis chambers. Filter press electrolysers have been described in EP-A-137,836 and EP-A-56,759. E.U.A. 5,139,635, for example, discloses gas electrolysers of the filter press type comprising a vertical stack of electrolysis chamber connected to a degassing chamber. Accordingly, gas electrolysers known in the art of the filter press type are complex arrangements involving different peripheral elements such as pumps, tanks and tubing, and therefore, comprise a multitude of moving parts, which require supervision, verification and maintenance. Thus, a more simplified arrangement with no or few moving parts would be a desirable goal to achieve since it would not require maintenance or limited maintenance. The high pressure electrolysers according to the present invention have the objective of avoiding moving parts and at the same time allowing the elimination of peripheral equipment that results in a more simplified disposition of the electrolyser, requiring less supervision and maintenance. The present invention relates to an electrolyser which operates under high pressure, thereby producing gases which are under increased pressure and which can be stored directly, without the additional compression step. In a further aspect, the electrolysers according to the present invention allow the circulation of the electrolyte in the electrolyser and the degassing chamber by spontaneous convection, that is, without pumping. In a further aspect, a supply system is provided to replace the water that is consumed during the course of electrolysis with minimal moving parts that use the pressure of the gas that is released in the electrolyser module as a driving force. In addition to the aforementioned advantages, the high pressure electrolysers of the invention can be allowed to cool to room temperature when they are not in operation. Typically, electrolysers known in the art operate at elevated temperatures, for example at 70 ° C, and show leakage when allowed to cool. Consequently, even when they are out of operation, they have to be kept at this elevated temperature. Thus, in one aspect, the present invention relates to a high-pressure electrolyser module comprising a series of stacked electrolysis chambers and each chamber being supported within two ring-shaped support frames, said frames having openings that form conduits. for the supply of electrolyte and the removal of the gas that is generated, wherein (1) the connecting surface of the ring-shaped frame has one or more elevations and / or one or more depressions in such a way that an elevation of a ring fits in a depression of a nearby ring; (2) a package is placed between said elevation in a particular ring and said depression of a nearby ring; (3) the distance between the edge of said conduit and the external wall of the opening forming the gas or electrolyte conduit, and the outer wall of the ring-shaped frame, is such that the material can withstand a pressure gradient of at least 200 bars. In a further aspect, the invention relates to an electrolyser comprising an electrolyzer module as described herein. The gases that are generated in the electrolyzer module contain electrolyte and typically a gas / electrolyte mixture is generated in the module normally forming a foam mixture. This mixture is conducted to a degassing chamber where the gas and electrolyte are separated. As used herein, the term gas that is generated and similar terms, when used in relation to gas that is generated in the electrolyser module until it is separated in the degassing chambers, attempts to comprise the aforementioned gas mixture. electrolyte. The electrolysis chambers in the high-pressure electrolysis modules according to the invention contain one or more, preferably two electrodes placed vertically in the chamber. The electrodes are made of materials known in the art that are inert to the electrolyte. The chambers are separated by a membrane or semi-permeable diaphragm and when two electrodes are used per chamber, the electrodes are preferably pressed against the membrane or diaphragm and connected through a suitable conductor. In a preferred arrangement, a bipolar plate is placed between the two electrodes and electrical contact is made by placing two woven metal sheets between each electrode. The different parts of each electrolysis chamber are supported in a ring-shaped frame that forms the external wall of the electrolysis chamber. The shape and dimensions of this frame are essential characteristics to ensure, on the one hand, high pressure electrolysis and, on the other hand, spontaneous electrolyte convection. In a particular embodiment, the electrolysis chambers are placed between two flanges, preferably made of metal, mounted on each side of the electrolysis chamber stack. The flanges are supported together with different connecting rods placed on the outside of the electrolyser module and link the flanges fitted with bolts to tighten in order to press the electrolysis chambers. In a further aspect, the present invention provides a ring-shaped frame wherein the connecting surface of said ring has one or more elevations and / or one or more depressions, such that an elevation of a ring is adjusted in a depression of a near ring and the ring has at least two openings in a cylindrical shape, at least one on the lower side and at least one on the upper side, the distance between the edge of said duct and the outer wall of the opening that It forms the gas or electrolyte conduit, and the outer wall of the ring-shaped frame is such that the material can withstand a pressure gradient of at least 200 bars, in particular said distance being at least 1.5 cm. The term "connecting surface" as used herein, refers to the flat surface of the ring, which has one or more elevations as described hereinafter, whereby a particular ring-shaped frame makes contact with a nearby ring . The ring-shaped frame has a thickness (i.e., distance between the two connecting surfaces of the ring) in a range of 0.2 to 1.5 cm, in particular 0.4 to 1.0 cm, preferably approximately 5 to approximately 6 mm. The internal diameter of the ring may vary depending on the desired volume of the electrolysis chamber and therefore on the scale of the electrolysis process. In a standard electrolyzer module for industrial application, the internal diameter can vary between 10 and 100 cm, preferably between 20 and 40 cm. A typical internal diameter for example is 30 cm. The internal size of the ring is often expressed in terms of surface, that is, the surface circumscribed by the inner circle of the ring. Expressed in this way, the particular internal sizes can vary between 300 and 5000 cm2, more particularly between 1000 and 3000 cm2. or between 1000 and 2500 cm2, for example, approximately 2000 or approximately 3000 cm2. The distance between the outer and inner edge of the ring-shaped frame, ie the outer diameter minus the internal diameter, can vary, and should be at least about 5 cm, more particularly at least about 7 cm, example approximately 10 cm. The external diameter of the ring depends on the aforementioned dimensions of the internal diameter and the size and positioning of the ring openings. The connecting surface of the ring-shaped frames of the invention may have an elevation or many of said elevations, preferably placed in a concentric manner, while a close ring may contain one or more depressions of equal size and shape that an elevation fits into a depression of a nearby ring. Or a particular ring may have on one connection surface one or more elevations and on the other surface, one or more depressions. In another embodiment, a connection surface may contain one or more elevations as well as depressions. The elevations and depressions can have different shapes, for example in the form of a block (ie, square or rectangular) or triangular. The last form is preferred. In a particularly preferred embodiment, the connecting surface of the ring-shaped frame has a series of small elevations and depressions that give the surface a milled appearance, the elevations and depressions having a triangular shape, whereby a cross section of the Surface has a jagged look. The distance between each elevation (and therefore between each depression) may vary, but in the above-mentioned particularly preferred embodiment, it is in the range of 0.5 to 3 mm, for example about 1 mm and the distance between the top of a Elevation and the lower part of a depression is in the range of 0.5 to 3 mm.

Preferably, the elevations / depressions cover almost the entire surface of the ring, except for a small section on the outer and inner edges of the ring, in particular terminating at least 2 or 3 mm from the edge of the ring. In a particularly preferred embodiment, a series of elevations / depressions is arranged concentrically around the conduit openings. This modality allows an even more effective closure of the rings. The distance of the outer circle circumscribing the surface covered by these concentric elevations / depressions, and the outer edge of the conduit opening is almost half the diameter of the conduit opening. The ring-shaped frames are made of a suitable polymeric material which is inert to the electrolyte, and preferably is a thermoplastic material such as polyphenylene sulfide, polyphenylene oxide and the like and in particular polysulfone. These rings are manufactured through conventional molding techniques. In order to ensure a better contact, an adequate packaging is used. The latter may be a ring of flat type or ring type 0 and is made of a suitable material, inert to the electrolyte used. In particular, the package is a flat ring made of synthetic material and is pressed between the milled surfaces of two nearby frames. Preferably, said flat ring-shaped package is made of a suitable inert and elastic polymeric material, such as polytetrafluoroethylene and has a uniform thickness in the range of 0.2 to 1 mm, preferably about 0.5 mm. Preferably, it has the same size or is slightly smaller than the flat surface of the ring-shaped frame. At last stay, the outer side of the package is within a short distance from the outer side of the frame, for example 2 mm. Preferably, the flat packing covers the surface formed by the elevations / depressions in the ring. The distance between the outer wall of the ring frame and the edge of the openings forming the gas or electrolyte passages is critical and must be such that the section of the ring covered by said distance can withstand the pressure gradient between the internal space of the ring. electrolyzer module and the atmospheric pressure outside the electrolyser module. In particular, said distance is at least 1.5 cm, particularly at least 2 cm or at least 3 cm. In the case in which the electrolyser operates at approximately 200 bars, a distance of approximately 2 cm has been verified as effective. The ring-shaped frame has at least three openings, two at the upper end to remove the gases that are generated and at least one, but preferably two, on the lower side which serves as an electrolyte supply conduit. Preferably, there are four openings, two on the upper side and two on the lower side, the center of each opening being located in an imaginary concentric circle towards the inner and outer edge of the ring, and the openings being placed symmetrically. The duct openings are of circular shape having a diameter in the range of 1.0 cm to 3.0 cm, particularly in the range of 1.5 cm to 2.5 cm, for example approximately 2.0 cm.

In a particular embodiment, each ring-shaped frame has two upper openings and two lower openings. The upper openings serve as conduits for removing the gases that are released in the cathode or the anode, for example, in the case of electrolysis of water, hydrogen and oxygen. The lower openings serve as a conduit for the supply of electrolyte, either fresh or degassed coming from the degassing chamber. The ring-shaped frames are stacked in such a way that all the openings fit precisely one into the other, thereby forming a channel which passes through the entire electrolyser module. In each ring, an upper opening and a lower opening is connected to the electrolysis chamber through a small connecting duct in cylindrical form. Said piaference connection conduits, should have a small diameter, for example in the range of 0.5 to 5 mm, particularly of 0.5 to 3 mm, for example 1 or 2 mm. In particular, the diameter of the connection conduit for electrolyte must be greater than that of the connection conduit for gas removal. In a particular embodiment, the diameter of said conduits is approximately 1 mm for the gas conduits and approximately 2 mm for the electrolyte conduits. The length of said connection conduits may be in the range of 1 cm to 4 cm, in particular 2 cm to 3 cm, for example 2.5 cm. In a particular embodiment, a ring-shaped frame has two upper openings of which one is connected to the inner edge of the ring and two lower openings of which one is connected to the inner edge of the ring, the openings being symmetrically placed in the ring. the ring and where the openings having the small conduit connection are placed in the same half of the ring. This particular mode of the ring allows stacking only with this type of ring. When the openings in the ring frame are configured and placed in the manner described above, it has been unexpectedly discovered that the electrolyte-gas mixture circulates in the electrolyser module and the degassing unit by spontaneous convection, that is, without the aid of a pumping system. The high pressure electrolysis modules according to the present invention can withstand pressures as high as 200 Bars, even 'up to 300 Bars. Normally, the pressures used to compress gases such as hydrogen or oxygen, for example, 200 Bars, are very feasible. This allows electrolysis under increased pressure, so the gases that are produced do not need to be compressed. This allows a simpler arrangement, since one can omit, on the one hand, a gas compressor and on the other hand, a pump, necessary to circulate the electrolyte. In a further aspect, there is provided a high pressure electrolyser according to the invention, having a water supply system, placed on a degassing chamber, comprising a vessel having a water inlet and an inlet for pressurized gas which derives from one of the degassing units, and an outlet for water carried at high pressure towards a pipe that is connected to one of the degassing chambers. The water supply system has minimal moving parts and is placed on the electrolyser module, in particular on the degassing units. It comprises a container, preferably made of metal and capable of withstanding the pressure in which the electrolyser operates, having an inlet for water and an inlet for pressurized gas which is derived from one of the degassing units. Water is allowed to enter said container, for example, by means of a suitable outlet, and subsequently the pressurized gas enters. In this way, the water is brought to high pressure and then this water is allowed to leave the container, for example, through a tap, towards a tube that is connected to one of the degassers, the water flowing in the degasser by gravity. The current theme is simple, without requiring additional pumps, thus avoiding moving parts. The shots can be controlled manually or their operation can be automated. In a preferred embodiment, in the case of water electrolysis, use is made of the pressurized oxygen that is separated in the oxygen degassing unit and the water supply system is connected to the oxygen separation chamber. The electrolysers of the present can be used in the production of different gases, for example, chlorine by the electrolysis of brine or oxygen and hydrogen in the case of water electrolysis. The following is a detailed description of the drawings intended to illustrate the invention and not limit it to them.

Figure 1 shows a cross section of a high pressure electrolyser module according to the present invention. Figure 2 is a front view of a ring-shaped frame according to the present invention. Figure 3 shows a cross section of the ring-shaped frame. Figure 4 shows a schematic representation of an electrolyser with two degassing chambers and a water supply system. Figure 1 shows a cross section of a number of electrolysis chambers that are supported in the moroc 1, being separated by the membrane 2 towards which the electrodes 3 are pressed. The electrodes are electrically connected to the bipolar plate 4 with a foil woven metal 5. The frame has the largest openings in duct 7 on the upper side and 8 on the lower side. The conduit openings 7 evacuate the gas that is generated and the openings 8 form an electrolyte supply channel. The opening 7 is connected to the internal space of the electrolyser module with the small connecting duct 9 and similarly, the opening 8 is connected to the internal space through the small connecting duct 10. In figure 2 a front view of the ring-shaped frame according to the present invention, with the connecting surface 11, the inner edge 12 and the outer edge 13, the milled surface 14 and the upper conduit openings 15 and 16; and the lower conduit openings 17 and 18. In this embodiment, only the upper opening 16 is connected to the internal opening of the ring-shaped frame and thus to the electrolysis chamber via the connection conduit 19, and Similarly, the opening 18 is connected to the electrolysis chamber via the connection conduit 20. The centers of the four ring openings are placed in a concentric circle 23. The axis 21 crosses the center of the ring-shaped frame, said center it is also located at the intersection of the intersecting axes 22. The milled surface concentric to the ring openings 15, 16, 17 and 18 is represented by 24, the surface of the last milled surface depends on the distance between the outer edge 26 of the opening and the outer edge 25 of the concentric milled surface 24. Figure 3 shows an & amp; cross section of the external section of a number of frames in the form of rings 34 with the milled surface 14 and the elevations 33 and depressions 32 that give the cross section of the ring a toothed appearance. 13 is the outer edge of the ring and 31 is the packing. Figure 4 shows a schematic representation of most of a high pressure electrolyser according to the invention, wherein 41 represents the electrolyser module with the degassing chambers placed at the top 43 and 44 and the water supply system placed even higher 44. The gas / electrolyte mixture that is generated in the electrolyzer module 41 is led to the degassing chambers 43 and 44. One of said degassing chambers, in particular the oxygen degassing chamber in the case of electrolysis of water, is connected to a water supply system 44, wherein the water is pressurized with the oxygen gas coming from the chamber 43. The pressurized water of 44 is conducted to the chamber 43 by gravity, and therefore not additional pumping is required to supply fresh water.

Claims (9)

NOVELTY OF THE INVENTION CLAIMS

1. - A high pressure electrolyser module comprising a series of stacked electrolysis chambers and each chamber being supported within two ring-shaped support frames, said frames having circular openings forming conduits for electrolyte delivery and removal of the gas that is generated, wherein (1) the connecting surface of the ring-shaped frame has one or more elevations and / or one or more depressions, such that an elevation of a ring is adjusted in a depression of a close ring; (2) a flat package is placed between the connection surfaces of the ring-shaped frames; (3) the distance between the outer wall of the ring frame and the edge of the openings forming the gas or electrolyte conduits is at least 1.5 cm; (4) the diameter of said conduits is in the range of 1 cm to 3 cm.

2. The electrolyser module according to claim 1, further characterized in that the distance between the outer wall of the ring frame and the edge of the openings forming the gas or electrolyte conduits is at least 2 cm.

3. The electrolyser module according to claim 1, further characterized in that the diameter of said conduit is in the range of 1.5 cm to 2.5 cm.

4. - The electrolyser module according to any of the preceding claims having a cylindrical connection conduit between the inner edge of the ring-shaped frame and the opening conduit, said connection conduit in cylindrical form having a diameter in the range from 0.5 mm to 3 mm and a length in the range of 1 cm to 4 cm.

5. The electrolyser module according to any of the preceding claims, further characterized in that the flat package has a thickness in the range of 0.2 mm to 1 mm and is made of polytetrafluoroethylene.

6. A ring-shaped support frame for a high-pressure electrolyser, wherein (1) the connecting surface of said ring has one or more elevations and / or one or more depressions, such that an elevation of a ring fits in a depression of a nearby ring and (2) the ring has at least two openings of cylindrical shape, at least one on the underside and at least one on the upper side; (3) the distance between the outer wall of the ring frame and the edge of the openings forming the gas or electrolyte conduits is at least 1.5 cm; (4) the diameter of said conduits is in the range of 1 cm to 3 cm.

7. The ring-shaped frame according to claim 6, further characterized in that the distance between the edge of said conduit and the external wall of the opening forming the gas or electrolyte conduit, and the external wall of the frame in Ring shape is at least 1.5 cm.

8. - An electrolyser comprising an electrolyser module according to claim 1 and further having a water supply system, placed on a degassing chamber, comprising a container having an inlet for water and an inlet for pressurized gas that is derives from one of the degassing units, and an outlet for water carried at high pressure to a pipe that is connected to one of the degassing chambers.

9. The electrolyser according to claim 8, further characterized in that the water supply system is placed on the oxygen degassing chamber and the pressurized gas is derived from the oxygen degassing chamber.