Electrode arrangement for electrochemically treating liquids

Abstract

The invention relates to an electrode arrangement (100) for electrochemically treating liquids, comprising at least two cathode plates (10, 11) between which at least one anode plate (12) is arranged, wherein a fluid chamber (13) is formed between each cathode plate (10, 11) and the or each anode plate (12). In order to provide a simple design of the electrode arrangement (100) that takes up minimal space, it is proposed that two cathode plates (10, 11) each form at least an areal portion of the housing of the electrode arrangement (100) and have connection means (14) in order to be connected to a voltage source.

Description

[0001] ELECTRODE ARRANGEMENT FOR ELECTROCHEMICAL TREATMENT OF LIQUIDS

[0002] The invention relates to an electrode arrangement for an electrochemical treatment of liquids, in particular waste water, comprising at least two cathode plates, between which at least one anode plate is arranged, wherein a fluid space is formed between each cathode plate and the or each anode plate.

[0003] STATE OF THE ART

[0004] Wastewater is often contaminated with persistent organic pollutants, which contain chemicals that are characterized by their longevity, can accumulate in organisms and thus in the food chain, and have harmful effects on humans and animals. Such chemicals in wastewater therefore pose a persistent threat to human health and the ecosystem. A recently developed technology for electrochemical water treatment enables the neutralization of organic chemicals in wastewater by means of electrochemical oxidation, so that they essentially lose their harmful effects. To carry out electrochemical water treatment, so-called wastewater reactors are known. These comprise electrode arrangements and have at least one cathode and at least one anode, between which a fluid chamber is formed, through which the wastewater is passed.A voltage is applied between the electrodes, and a special surface coating on the anode allows the applied voltage to trigger chemical reactions that render the organic chemicals harmless.

[0005] For example, DE 10 2018 128 228 A1 discloses a method for operating an electrode assembly for the electrochemical treatment of liquids. It is stated that, for example, a boron-doped diamond can be used as the anode and a stainless steel as the cathode. The boron-doped diamond is applied as a coating to an anode plate, and the cathode plate itself can comprise the stainless steel material for liquid contact.

[0006] Various electrode arrangements stacked on top of one another in the form of so-called stacks are also known from the prior art. For example, DE 10 2016 113 727 A1 discloses an electrode arrangement for the electrochemical treatment of liquids, comprising two cathode plates and an anode plate arranged between them, wherein the cathode plates have channels through which the liquid flows perpendicular to their planar extension. In order to build such a wastewater reactor with a corresponding electrode arrangement, so that ultimately only an inlet and an outlet for the liquid to be electrochemically treated and a power connection are present, a housing is required that must enclose the electrode arrangements known from the prior art.

[0007] DISCLOSURE OF THE INVENTION

[0008] The object of the invention is to improve an electrode arrangement for an electrochemical treatment of liquids with at least two cathode plates and at least one anode plate, wherein the electrode arrangement as a whole should have a simple and space-minimal structure, wherein in particular further structural components for the construction of a wastewater reactor with a corresponding electrode arrangement should, if possible, require no further structural measures.

[0009] This object is achieved by an electrode arrangement according to the preamble of claim 1 with the characterizing features. Advantageous developments of the invention are specified in the dependent claims.

[0010] The invention includes the technical teaching that two cathode plates each form at least a flat part of a housing of the electrode arrangement that is sealed against the liquids and have connection means for being connected to a voltage source.

[0011] The core concept of the invention is a very compact design of the electrode arrangement for forming a liquid reactor, in which the outer cathode plates simultaneously form the fluid-tight housing of the electrode arrangement. Thus, the electrode arrangement, as an individually manageable system, can only be provided with fluid connections to create an inlet or outlet for the liquid for electrochemical treatment into and out of the fluid spaces. A further housing to accommodate the electrode arrangement and, in particular, for further fluidic sealing is not required. This also results in the advantage that a large number of such electrode arrangements can be fluidically and electrically interconnected as individual cells to form a battery, which are fluidically and electrically connected to one another.The housings of the electrode assemblies formed by the cathode plates can be connected to a common negative pole, which in particular also forms a ground point, so that the electrical potential of the housing of the electrode assemblies with the cathode plates has no voltage potential relative to the installation environment. Within the meaning of the invention, the electrode assembly not only comprises cathode plates and anode plates, but can also include other components, such as sealing elements, screw connections, connecting means for contacting an electrical voltage connection, and the like.

[0012] The simplest form of the electrode arrangement according to the invention comprises an anode plate between two cathode plates, wherein the plate-shaped electrodes are spaced apart to form a fluid space therebetween. The fluid forming the electrolyte flows through the fluid space between the electrode plates and forms an electrolyte, so that the chemical processes can take place, in particular, on the surface of the anode plate when a voltage is applied between the electrode plates. The electrode arrangement according to the invention preferably has several anode plates, between each of which a cathode plate is arranged. The outer electrode plates are each formed by cathode plates, and all electrode plates are connected to a voltage source.

[0013] The cathode plates can be made of stainless steel, while the anode plates can have a titanium substrate coated on both sides with boron-doped diamond (BDD). The actual chemical reaction for purifying the liquid takes place on the surface of the anode plate, so that pollutants such as pharmaceuticals, perfluorinated or chlorinated organic substances, landfill leachate, phenolic compounds, or other chemical substances are rendered harmless through oxidation. Since coating the anode plates with boron-doped diamond is cost-intensive, all anode plates are housed internally in the electrode assembly. The inventive design of the electrode assembly allows maximum utilization of the anode plate surface for carrying out the electrochemical processes on the anode plate surface.For this purpose, they are coated on both sides and incorporated into the structure of the electrode arrangement in a particularly advantageous manner. Thus, in particular, several cathode plates and several anode plates are arranged alternately one after the other and plane-parallel to one another, so that they form a "stack," i.e., a stacked arrangement.

[0014] To ensure a compact design of the electrode arrangement, the cathode plates and the at least one anode plate are held in their stacked arrangement relative to one another by means of a pressing device and are pressed together, in particular, using electrically insulating intermediate layers. The pressing device can also be referred to as a connecting device, and according to one possible embodiment, this comprises a number of screw elements that are guided through openings that are provided at least in the cathode plates. As an alternative to a large number of screw elements, it would also be conceivable to attach, for example, terminal strips to the outside of the outer cathode plates forming the housing, which are clamped against one another using a significantly reduced number of screw elements.

[0015] It is particularly advantageous for cost reasons if the anode plates are surrounded as completely as possible by the liquid in terms of their dimensions. A further aspect of the advantageous design of the electrode arrangement is that the at least one or in particular the plurality of anode plates have a format in their plate-shaped extension plane that is smaller than the format of the cathode plates. In order to nevertheless enable the stacking of the cathode plates in alternating arrangement with the anode plates, electrically insulating frame elements are provided which compensate for the undersize of the anode plates relative to the cathode plates. The frame elements can enclose the anode plates so that the anode plates can lie in the frame elements, and together with the frame elements have a format that corresponds to the format of the cathode plates.

[0016] The frame elements can be approximately the same thickness as the anode plates, so that the frame elements extend in a common plane with the respective anode plate. The frame elements can also have holes through which the screw elements are guided, so that the screw elements successively penetrate the cathode plates, the frame elements, and the sealing elements, while the anode plates are held within the frame elements.

[0017] Sealing elements are provided alternately with the frame elements and the cathode plates, which are pulled together with the frame elements and the cathode plates by means of the pressure device in order to form a stable “stack”.

[0018] A further idea improving the invention is a special receptacle for the anode plates in the assembly of the electrode arrangement. For this purpose, the sealing elements project beyond the at least one or more frame elements with an inward overhang, i.e., pointing into the fluid space. This creates an internally circumferential groove in which the anode plates are held in their planar plane. The groove is thus defined in the planar plane of the anode plates by means of the frame elements and laterally by the sealing elements overlapping the edge of the anode plates. The overhang can, for example, have an overhang dimension that corresponds to 1 to 50 times and / or 1 to 10 times and / or 1 to 5 times and / or 1 to 3 times the thickness of the anode plate. The overhang dimension can, for example, be 1 mm.

[0019] The at least one anode plate and / or the cathode plates that do not form the flat part of the housing of the electrode assembly have fluid openings by means of which the multiple fluid spaces between the electrode plates are fluidically connected to one another in various ways. The fluid openings can be arranged alternately at opposite edges of the cathode plates and anode plates, so that a meandering flow of the liquid to be electrochemically treated occurs through the electrode assembly. The liquid then sequentially passes through the entire length of the successively meandering fluid spaces, so that the flow rate per unit time is lower.

[0020] Alternatively, the multiple fluid spaces between the electrode plates can also be flowed through in parallel or turbulent parallel through fluid openings arranged at least on both sides, so that the electrode arrangement enables a higher total flow and the flow per time is higher.

[0021] The cathode plates, which form the flat part of the housing of the electrode assembly and thus represent the outer electrodes of the electrode assembly, have fluid connections to provide an inlet or outlet for the liquid for electrochemical treatment into and out of the fluid spaces. If two opposing outer cathode plates are provided to form the electrode assembly, a first cathode plate can have a first fluid connection on a first side of the electrode assembly for the inlet of the liquid, and an opposite second cathode plate can have a fluid connection on an opposite side for the outlet of the liquid.The inflow and outflow of the liquid occurs, for example, perpendicular to the planar extension of the cathode plates, whereby the fluid connections are arranged in such a way that the distance between the fluid connections and the nearest fluid openings in the anode plates is as large as possible, and so that the entire surface of the anode plate is flowed around by the liquid.

[0022] The at least one anode plate and the cathode plates have contact tabs that form the connection means for connecting a voltage / current supply and on which electrical contacts are arranged, located outside the fluid space. In the areas where the anode plates have the contact tabs, no frame elements are arranged or the frame element is interrupted at that point, so that the at least one anode plate is formed in one piece, of the same material, and continuously from the inside to the contact tabs, defining the fluid space.

[0023] The electrode arrangement can be cuboid-shaped, for example, with a length of 400 mm, a width of 90 mm, and a stack thickness of 21 mm, for example, with a dimensional deviation of up to 20% or up to 10%. The fluid connections can protrude from the cathode plates in the thickness direction of the electrode arrangement, and the contact tabs with the electrical contacts are located, for example, in extension of the longitudinal axis, whereby the 400 mm of the main dimension of the electrode arrangement can be further increased by the length of the contact tabs. The contact tabs of the cathode plates and the anode plates can be mounted on opposite sides of the main axis, although any other alternative arrangement is also conceivable.Advantageously, however, the contact tabs are provided in extension of the longitudinal axis of the electrode arrangement, so that a battery with a large number of electrode arrangements of the design presented here enables an arrangement that is as space-saving as possible.

[0024] At the core of the invention, it is achieved that the cathode plates with the sealing elements and with the frame elements as a whole form a coherent housing, wherein the electrical contacts are mounted outside the fluid space and no other materials are in contact with the fluid to be treated.

[0025] PREFERRED EMBODIMENT OF THE INVENTION

[0026] Further measures improving the invention are described in more detail below, together with the description of a preferred embodiment of the invention, with reference to the figures. It shows:

[0027] Figure 1 is a perspective view of the entire electrode arrangement with the features of the invention,

[0028] Figure 2 is a cross-sectional view through the electrode arrangement,

[0029] Figure 3 is a perspective view of the electrode assembly with an upper cathode plate removed and

[0030] Figure 4 is a flying view of the components of the electrode assembly according to the invention. Figure 1 shows the electrode assembly 100 according to the invention, which can also be referred to as a liquid reactor. The electrode assembly 100 serves for the electrochemical treatment of liquids that are fed to the electrode assembly 100 and then discharged therefrom. The exemplary embodiment shows the electrode assembly 100 with a cuboid shape in an elongated extension, and the special feature of the electrode assembly 100 according to the invention are the external cathode plates 10, 11, which form a top and bottom housing closure of the electrode assembly 100. In this respect, the cathode plates 10, 11 form an essential part of the housing of the electrode assembly 100 and seal an internal fluid space across the entire surface.An essential feature of the outer cathode plates 10, 11 is their liquid-tight construction, so that these two electrode plates are the only electrode plates of the multitude of electrode plates that do not have any further passages, except for the fluid connections 27 for supplying and removing the liquid to be electrochemically cleaned.

[0031] According to this exemplary embodiment, the electrode assembly 100 comprises three anode plates 12, 17, and 18, with further inner cathode plates 15, 16 being provided in addition to the outer cathode plates 10, 11. All cathode plates 10, 11, 15, 16 are alternately stacked on top of each other as a "stack" with the anode plates 12, 17, and 18, with the fluid spaces formed between the respective plates.

[0032] The basic idea of ​​the invention is that the outer cathode plates 10, 11 simultaneously form the housing of the

[0033] Electrode assembly 100. The electrode assembly 100 thus formed forms a individually handleable unit, allowing it to be fluidically connected via the fluid connections 27. A blind flange 27a is also shown, allowing the flow direction of the electrode assembly 100 to be changed when these are exchanged for fluid connections 27. Thus, depending on the liquid reactor type, different configurations of the fluid connections 27 and the blind flanges 27a can be provided.

[0034] Furthermore, contact bolts 30, 31 are shown, which electrically connect the cathode plates 10, 11, 15, 16 and the anode plates 12, 15 and 16 to one another and which, in a manner not shown in detail, form the contact means 14 for connection to a current and / or voltage source.

[0035] To enable electrical contact between all electrode plates, the cathode plates 10, 11, 15, 16 and the anode plates 12, 17, and 18 have contact tabs 28, each connected to contact pins 30, 31. A direct voltage of, for example, 30 volts can be applied to the contact pins 30, 31, whereby, depending on the conductivity of the liquid to be cleaned, a current of, for example, 30 amperes can flow. The electrical contact on the contact pin 30 for contacting the cathode plates 10, 11, 15, 16 can simultaneously form a ground point, so that the housing has no electrical potential with respect to the installation environment.

[0036] Figure 2 shows a cross-sectional view of the arrangement of the cathode plates 10, 11, 15, 16 and the arrangement of the anode plates 12, 17, and 18 of the electrode assembly 100. It is clear that the cathode plates 10, 11 form outer electrode plates to form the housing, and the anode plates 12, 17, and 18 are arranged internally, alternating with further, internal cathode plates 15 and 16. Fluid spaces 13 are formed between the cathode plates 10, 11, 15, 16 and the anode plates 12, 17, and 18, through which the liquid to be treated can flow. For sealing purposes, sealing elements 23 are provided which seal the cathode plates 10, 11, 15 and 16 as well as the anode plates 11, 17 and 18 at a distance from one another.

[0037] Furthermore, the anode plates 12, 17, and 18 are designed with a smaller surface area, making them smaller than the cathode plates 10, 11, 15, and 16. This dimensional difference is compensated for by frame elements 22, which are enclosed between the sealing elements 23. The cathode plates 10, 11, 15, and 16, the frame elements 22, and the sealing elements 23 are screwed together via screw elements 20, with the screw elements 20 forming the pressing device 19.

[0038] When examining the arrangement of the screw elements 20, it becomes clear that they only penetrate the cathode plates 10, 11, 15, 16 as well as the frame elements 22 and the sealing elements 23, but not the anode plates 12, 17 and 18. These are enclosed on the outside by the frame elements 22, which are positioned between two sealing elements 23. The sealing elements 23 have an overhang 25 that encloses the anode plates 12, 17 and 18 inwards. This allows maximum utilization of the surfaces of the anode plates 12, 17, 18 provided with the expensive boron-doped diamond coating without large parts of the anode plates 12, 17, 18 being covered by sealing elements 23. The inward-facing overhang 25 can have a size of one millimeter, for example.

[0039] Fluid connections 27 and blind flanges 27a are provided on the outer sides of the upper and lower outer cathode plates 10, 11 to allow the inflow and outflow of the liquid to be electrochemically cleaned. Figure 3 shows the electrode assembly 100 with the cathode plates 11, 15, and 16, with the upper cathode plate 10 removed according to Figure 2. The other anode plates 12, 17, and 18 are shown alternating with the cathode plates 11, 15, and 16, as already described in connection with Figure 1.

[0040] Removing the upper cathode plate 10 reveals the first inner anode plate 12, which has a fluid opening 26 at its edge to allow the fluid to flow between the multiple fluid chambers 13. The design of the electrical contacts by means of the contact pins 30, 31 on the contact tabs 28, 29 has already been described in connection with Figure 1.

[0041] Figure 4 shows a flying view of the components of the electrode assembly 100, with the structure from top to bottom depicting the cathode plates 10, 15, 16, and 11 as the lowest cathode plate. The anode plates 12, 17, and 18 are arranged alternately between them. The anode plates 12, 17, and 18 are enclosed at the edges by frame elements 22, in which the openings 24 are provided. The openings 21 are provided in the cathode plates 10, 11, 15, and 16, and the screw elements 20 for forming the pressing device 19 are passed through the openings 21 and 24, while further openings 33 are provided in the sealing elements 23, through which the screw elements 20 are passed.

[0042] This view clearly shows that the contact tabs 28, 29 for connecting the contact pins 30, 31 are formed in one piece and of the same material as the actual cathode plates and anode plates. Screw nuts 32 are provided to connect the contact pins 30, 31 to the electrode plates. The invention is not limited in its embodiments to the preferred embodiment specified above. Rather, a number of variants are conceivable, which make use of the solution presented even in fundamentally different designs. All features and / or advantages apparent from the claims, the description, or the drawings, including design details or spatial arrangements, can be essential to the invention both individually and in a wide variety of combinations.

[0043] List of reference symbols:

[0044] 10 Cathode plate

[0045] 11 Cathode plate

[0046] 12 Anode plate

[0047] 13 Fluid space

[0048] 14 Connection devices

[0049] 15 Cathode plate

[0050] 16 Cathode plate

[0051] 17 Anode plate

[0052] 18 Anode plate

[0053] 19 Pressure device

[0054] 20 screw element

[0055] 21 Opening

[0056] 22 frame element

[0057] 23 Sealing element

[0058] 24 Opening

[0059] 25 overhang

[0060] 26 Fluid opening

[0061] 27 Fluid connection

[0062] 27a Blind flange

[0063] 28 Contact tab

[0064] 29 Contact tab

[0065] 30 contact bolts

[0066] 31 contact bolts

[0067] 32 screw nut

[0068] 33 Opening

[0069] 100 electrode arrangement

Claims

Claims:

1. Electrode arrangement (100) for an electrochemical treatment of liquids, comprising at least two cathode plates (10, 11), between which at least one anode plate (12) is arranged, wherein a fluid space (13) is formed between each cathode plate (10, 11) and the or each anode plate (12), characterized in that two cathode plates (10, 11) each form at least a flat part of a housing of the electrode arrangement (100) which seals off the liquids and has connection means (14) for being connected to a voltage source.

2. Electrode arrangement (100) according to claim 1, characterized in that a plurality of cathode plates (10, 11, 15, 16) and a plurality of anode plates (12, 17, 18) are arranged alternately one after the other and plane-parallel to one another.

3. Electrode arrangement (100) according to claim 1 or 2, characterized in that the cathode plates (10, 11, 15, 16) and the at least one anode plate (12, 17, 18) are held in their stacked arrangement relative to one another by means of a pressing device (19).

4. Electrode arrangement (100) according to claim 3, characterized in that the pressing device (19) comprises a number of screw elements (20) which are guided through openings (21) which are made at least in the cathode plates (10, 11, 15, 16).

5. Electrode arrangement (100) according to one of the preceding claims, characterized in that the at least one or more anode plates (12, 17, 18) have a format in their plate-shaped extension plane which is smaller than the format of the cathode plates (10, 11, 15, 16).

6. Electrode arrangement (100) according to one of the preceding claims, characterized in that at least one or more frame elements (22) are provided which enclose the at least one anode plate (12) or the plurality of anode plates (12).

7. Electrode arrangement (100) according to one of the preceding claims, characterized in that sealing elements (23) are provided which are arranged between the cathode plates (10, 11, 15, 16) and the at least one or more anode plates (12, 17, 18) with the frame elements (22).

8. Electrode arrangement (100) according to one of the preceding claims, characterized in that the frame elements (22) have openings (24) through which the screw elements (20) are guided, so that the screw elements (20) successively penetrate the cathode plates (10, 11, 15, 16), the frame elements (22) and the sealing elements (23), while the anode plates (12, 17, 18) within the Frame elements (22) are held and designed free of openings for screw elements.

9. Electrode arrangement (100) according to one of the preceding claims, characterized in that the sealing elements (23) project beyond the at least one or more frame elements (22) with overhangs (25) into the fluid space (13) and enclose the anode plates (12, 17, 18) at the edges.

10. Electrode arrangement (100) according to one of the preceding claims, characterized in that the at least one anode plate (12) is held in its position between the cathode plates (10, 11) at the edge by means of the overhangs (25) and the frame elements (22).

11. Electrode arrangement (100) according to claim 9 or 10, characterized in that the overhangs (25) have an overhang dimension which is 1 to 15 times and / or 1 to 10 times and / or 1 to 5 times and / or 1 to 3 times the thickness of the anode plate (12) and / or the overhangs (25) are 1 mm.

12. Electrode arrangement (100) according to one of the preceding claims, characterized in that the at least one anode plate (12, 17, 18) and / or the at least one cathode plate (15, 16), which do not form the planar part of the housing of the electrode arrangement (100), have fluid openings (26) by means of which the plurality of fluid spaces (13) between the at least one anode plate (12, 17, 18) and the cathode plate (15, 16) are fluidically connected.

13. Electrode arrangement (100) according to one of the preceding claims, characterized in that at least one of the cathode plates (10, 11) forming the flat part of the housing of the electrode arrangement (100) has fluid connections (27) in order to create an inflow and outflow of the liquid for the electrochemical treatment into and out of the fluid spaces (13).

14. Electrode arrangement (100) according to one of the preceding claims, characterized in that the electrical electrode connection of the cathode plates (10, 11) and / or the at least one anode plate (12) is formed outside the fluid space (13).

15. Electrode arrangement (100) according to one of the preceding claims, characterized in that the anode plates (12, 17, 18) and the cathode plates (10, 11, 15, 16) have contact tabs (28, 29) which form the connection means (14) for connecting a direct current or voltage source.

16. Electrode arrangement (100) according to one of the preceding claims, characterized in that only surfaces of the cathode plates (10, 11, 15, 16), the anode plates (12, 17, 18) and the sealing elements (23) are in contact with the liquid in the fluid spaces (13) when it is filled.

Images