filter

Abstract

The present invention relates to a filter for treating a process fluid, for example a process fluid occurring in particular during hydrogen electrolysis, preferably for separating hydrogen and / or oxygen from process water, said filter comprising a first filter element 10 and a second filter element 12 surrounding the first filter element 10 at a predeterminable radial distance to form a flow chamber 14, each filter element 10, 12 having a filter medium 16, 18 through which the process fluid can flow in a flow direction 24 from the outside to the inside or preferably from the inside to the outside, said filter medium 16 forming, as viewed in said flow direction 24, a first degassing stage which serves to remove gas bubbles from the process fluid by expanding them through coalescence and separation caused by buoyancy forces, and a subsequent further filter medium 18 forming a second degassing stage which serves to remove finely distributed gas bubbles remaining in the process fluid by re-coalescence, said separation of the gas bubbles being caused by rising caused by buoyancy forces.

Description

[Technical Field]

[0001] The present invention relates to a filter for treating process fluids, for example in particular for treating process fluids produced during hydrogen electrolysis, preferably for separating hydrogen and / or oxygen from process water. [Background technology]

[0002] DE 102021001631 A1 discloses a method for treating a process fluid arising during the decomposition of a process liquid which is produced when it is decomposed into different process gases in at least one fluid circuit with the aid of an electric current in an electrolysis cell, in which at least one of several process gases is contained in the form of a process liquid to form the process fluid, and in which at least one fluid storage tank is present as part of the fluid circuit, in which at least one filter device is housed, by means of which the process fluid is cleaned from any particulate contamination and at the same time the contained process gas is separated from the process fluid while retaining the process liquid.

[0003] The filter device used here and known in this respect preferably has a replaceable filter element through which the fluid can flow from the inside to the outside, is surrounded by a housing wall and is designed as an outlet pipe with several passage points, some of which are located below a respective variable fluid level in the fluid storage tank and others are located above this fluid level, forming fluid chambers while maintaining a predeterminable radial distance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Patent Application Publication No. 102021001631 Summary of the Invention [Problem to be solved by the invention]

[0005] Based on this prior art, the present invention is based on the objective of further improving the known solution while retaining its advantages, in particular of achieving an even higher efficiency of separation of gas from the process fluid. [Means for solving the problem]

[0006] This problem is solved by a filter having in its entirety the features of claim 1.

[0007] The filter according to the invention comprises a first filter element and a second filter element surrounding the first filter element at a predeterminable radial distance to form a flow chamber, each filter element comprising a filter medium, in which the process fluid can flow through the filter medium from outside to inside or preferably from inside to outside, in a flow direction in which one filter medium forms a first degassing stage which serves to expand the gas bubbles by coalescence and remove them from the process fluid by separation caused by buoyancy, and thereafter a further filter medium forms a second degassing stage which serves to separate the gas bubbles again by rising due to buoyancy so as to remove the finely distributed gas bubbles remaining in the process fluid by coalescence.

[0008] In this way, a two-stage degassing filter is created in one assembly, which significantly improves fluid and gas separation compared to known solutions. In the field of hydrogen electrolysis, as mentioned above, oxygen and hydrogen are released from process water as the process fluid during the process. For both hydrogen and oxygen, two separate fluid circuits exist for the process: one circuit with water and free hydrogen bubbles, and another circuit with water and free oxygen bubbles. For each of these circuits, a separate separator is used, whose role is to separate the corresponding gas from the liquid. The gas content that can occur in the process is between 30 and 95% by volume. Due to its improved degassing speed, the degassing filter of the present invention allows for a significant reduction in the size or volume of each separator. This savings in installation volume allows the filter of the present invention to be increasingly used for various practical applications. Preferably, the filter media used in the first and second elements are different from each other depending on the degassing task to be achieved.

[0009] In a preferred embodiment of the filter according to the invention, the leading filter medium in the flow direction consists of a depth filter cartridge designed as a hollow cylindrical filter casing to increase the filter volume. This results in a coaxial arrangement of two filter stages used to degas the process fluid, whereby the first filter stage causes a first coalescence of gas bubbles, which then rise upwards due to buoyancy, increasing their volume accordingly and thus being separated from the process fluid. The gas bubbles that have not yet been separated are then retained by the second degassing stage and fed back into the coalescence process, whereby they are also finely dispersed in the fluid, increase in volume, rise due to buoyancy, and are then separated from the process fluid, usually in the form of process water.

[0010] It is particularly preferred that the filter be formed using meltblown fibers to form a depth filter cartridge, which is preferably sprayed onto a fluid-permeable support on which the filter casing is supported along its inner periphery. The depth filter cartridge used is designed to be significantly larger in volume compared to pleated element materials, resulting in improved gas release behavior. In this respect, the meltblown depth filter cartridge forms a hollow cylindrical solid filter casing block with a predeterminable porosity.

[0011] Instead of constructing the depth filter cartridge from meltblown fibers, it is also possible to construct it from sintered materials either in the form of a sintered metal filter or in the form of a ceramic filter, each having a predeterminable filter permeability.

[0012] For a reliable degassing process with a high separation rate, it has proven advantageous to select a filter fineness of the depth filter cartridge between 10 μm and 200 μm. When meltblown fibers are used primarily or exclusively in depth filter cartridges, the fiber diameter is preferably between 0.1 μm and 2000 μm, and the mean flow pore diameter (MFP / mean flow pore size) is preferably between 1 μm and 2000 μm.

[0013] For a homogeneous structure of the filter, all essential components are preferably made of the same plastic material, and if metals such as stainless steel or titanium are used as filter media for the filter, it is preferred that all filter media consist of the same metal material.

[0014] Particularly preferably, it can be provided that the filter medium following one filter medium in the flow direction has a mat structure of at least two layers, preferably three layers, which allows further improved particle cleaning from the fluid flow.

[0015] The present invention also relates to an apparatus comprising a container for accommodating at least one of the above-mentioned filters, the container having at least one inlet for a gas-containing process fluid, an outlet for the gas separated in the container, and a further outlet for the gas-free process fluid, the flow through each filter starting from the inlet of the container from the inside to the outside, transferring the separated gas above the fluid level in the container to one outlet in the container, and the process fluid accumulated in the container below this fluid level being discharged from the container via the further outlet. Preferably, the parallel flow to each filter in the container runs from below through a plurality of openings in a separator plate in the container extending parallel to the fluid level established during operation, parallel to the fluid level adjusted during operation, and suction connections are provided between the individual filters, which open above the adapter plate and below the fluid level in the container and are connected to the further outlet for the process fluid.

[0016] In the following, the filter according to the invention will be explained in more detail using various embodiments and in relation to the installation of the container according to the drawings, which are shown diagrammatically and not to scale. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view of the filter. [Figure 2] FIG. 2 shows the filter in one of two different embodiments in longitudinal section through FIG. [Figure 3] FIG. 3 shows the filter in one of two different embodiments in longitudinal section through FIG. [Figure 4] FIG. 4 shows an enlarged view of the head of the filter according to FIG. 2 and the filter according to FIG. [Figure 5] FIG. 5 is an enlarged view of the bottom end of the filter according to FIG. 2 and the filter according to FIG. [Figure 6] FIG. 6 shows an enlarged view of the head of the filter according to FIG. 2 and the filter according to FIG. [Figure 7]FIG. 7 is an enlarged view of the bottom end of the filter according to FIG. 2 and the filter according to FIG. [Figure 8] FIG. 8 is a side view showing the installation of the filter according to FIGS. 1 to 3 in a container. [Figure 9] FIG. 9 is a plan view showing the installation of the filter according to FIGS. 1 to 3 in a container. DETAILED DESCRIPTION OF THE INVENTION

[0018] 2, 4 and 5 relate to a first embodiment of a filter according to the invention. The filter is used to treat process fluids, in particular those produced during hydrogen electrolysis, preferably to separate hydrogen and / or oxygen from process water. The filter comprises, in an assembly, a first filter element 10 and a second filter element 12 surrounding the first filter element 10 and defining a flow chamber 14 at a predeterminable radial distance.

[0019] Furthermore, the first filter element 10 includes a first filter medium 16, and the second filter element 12 includes a second filter medium 18. The first filter medium 16 is supported at its inner periphery by a fluid-permeable support 20 in the form of a support grid. The second filter medium 18 is surrounded at its outer periphery by an additional fluid-permeable support 22, also configured in the form of a support grid. These additional fluid-permeable supports, not shown, can be disposed on the outer periphery of the first filter medium 16 and on the inner periphery of the second filter medium 18, as needed. In this case, flow through the filter occurs from the inside to the outside, as indicated by arrow 24 in FIG. 2 .

[0020] The first filter media 16, together with its inner support 20, is housed between an upper end cap 26 and a lower end cap 28. The second filter media 18, with its additional support 22, has the same axial length and is housed between the same end caps 26, 28. At this point, the respective end faces of the first filter media 16 and second filter media 18 and the two supports 20, 22 are rigidly or fluid-tightly connected to the end caps 26, 28, preferably using a miller welding process. Further details of the end caps 26, 28 will be described in more detail below. Looking again in the flow direction 24, the first filter media 16 forms a first degassing stage, which serves to expand gas bubbles by coalescence and remove them from the process fluid by buoyancy separation. The subsequent additional filter media 18 forms a second degassing stage, which serves to remove any remaining finely distributed gas bubbles in the process fluid by coalescence again and separate the bubbles by rising due to buoyancy. Thus, the first degassing stage formed by the first filter element 10 acts as a whole to expand existing gas bubbles, which then rise in the process fluid and thus separate to the surface of the process fluid. The second filter element 12, forming the second degassing stage, is used to coalesce any remaining finely distributed gas bubbles in the process fluid into larger bubbles and separate the bubbles by rising due to buoyancy.

[0021] In one embodiment of the filter according to the present invention, the inner filter stage in the form of a filter element 10 is a volumetric meltblown depth filter cartridge made of polypropylene. The filter fineness of the depth filter cartridge is preferably between 10 μm and 200 μm. Alternatively, a sintered filter (details not shown) with the same filter fineness can be used. To manufacture a depth filter cartridge from meltblown fibers, the meltblown fibers are preferably sprayed onto the inner support 20. The outer filter stage, which includes the second filter media 18, is a three-layer pleated structure made of woven polypropylene. Preferably, in this case, the mesh size of the two outer layers facing the support 22 is approximately 200 μm to 1000 μm, which is relatively coarse. In contrast, the mesh size of the inner layer is 0.1 μm to 500 μm, which can be described as relatively fine. The pleated filter mat forming the second filter media 18 has a fold density of 0.1 to 6 folds per centimeter.

[0022] In addition to the polypropylene material mentioned above, other plastic materials that can be used in the manufacture include polyamide and polyester. When the same plastic material is used for the filter media 16, 18, the supports 20, 22, and the end caps 26, 28, a homogeneous structure is achieved, which helps facilitate recycling of the entire filter. Twill or satin weaves, as well as so-called plain weaves, can be used as the weave for the second filter media 18. Other weave types are also possible. In addition to the three-layer structure described above, there are also options for structures with two to five layers, with the mesh size preferably ranging from coarse to fine as viewed in the flow direction 24.

[0023] In the previously mentioned mirror welding process, two identically designed centering rings 30 with through holes 32 are inserted into the flow chamber 14 in the region of the upper end cap 26 and the region of the lower end cap 28. The upper centering ring 30, as viewed in FIG. 2, is fixed to the upper end cap 26 by mirror welding at its upper free end face. The through holes 32 in the centering ring 30 allow the passage of gas bubbles rising from the flow chamber 14 between the two filter media 16, 18. Similarly, the lower centering ring 30, as viewed in FIG. 2, is mirror-welded to the lower end cap 28 at its lower free end face. For this purpose, each centering ring 30 has an annular fixing rod 34 on its inner periphery and an annular fixing rod 36 on its outer periphery. The rods 34, 36 approximately center the bottom 38 of the respective centering ring 30, which is provided with several through holes 32. The several through-holes 32 extend at discrete distances from one another along a bottom 38 that extends parallel to the orientation of the end caps 26, 28. Outwardly, each of the fixing rods 34, 36 is supported by an upper portion of the outer periphery of the first filter medium 16 and an inner periphery of the second filter medium 18. For simplicity, the two centering rings 30 are identically designed, although the lower centering ring 30, as viewed from the perspective of FIG. 2, does not necessarily have through-holes 32 for removing air bubbles. In any case, the upper and lower free end faces of the two fixing rods 34, 36 of each centering ring 30 are also mirror-welded to the associated end cap 26 or 28. Instead of the mirror welding mentioned, other welding processes can also be used, such as a transmission welding process using laser light, as shown by way of example in the applicant's German Patent Applications DE 102007013178 A1 and DE 102010005541 A1. Ultrasonic welding methods can also be used and the production of adhesive bonds is also conceivable.The two rods 34, 36 each have pairs of protruding centering rods 39 pointing outward toward the filter media 16, 18, which may penetrate at least partially into the flexible filter media 16, 18 to facilitate or enable positioning of the rods 34 for the welding process within the filter. The centering rods 39 are annular, integral parts of the respective retainer rods 34, 36.

[0024] The lower end cap 28 has a downwardly projecting hollow cylindrical annular connector 40 with an O-ring-shaped sealing device 42 received in a peripheral groove of the annular connector 40. In this way, the filter as a whole can be fixed in a vessel housing 43 in an environmentally sealed manner, as shown in FIGS. 8 and 9, and the gas-containing process fluid can be supplied via the hollow passage of the annular connector 40 to the central inside 44 of the filter, which is designed as an inlet space and is surrounded closest to the support 20 together with the first filter medium 16. However, the O-ring-equipped sealing device 42 can also be omitted to maintain a homogeneous structure and be replaced by a clamp connection (not shown). From this inside 44, the process fluid passes through the first filter element 10, then along the flow direction 24, to the flow chamber 14, from where it passes through the second filter element 12 with its subsequent further support 22, and to the outside 45 of the filter. This corresponds to the interior of the vessel housing 43 as part of the vessel mounting for the respective filter, which will be explained in more detail with reference to FIGS. 8 and 9.

[0025] The upper end cap 26 has outlet openings 46 coaxial with the orientation of the upper through-holes 32 of the centering ring 30. As shown in FIG. 4 , one free end opens into the flow chamber 14 above the centering ring 30, and the other free end opens into an annular gap 48, which opens from the inside of the thus closed upper end cap 26 onto the outside 45 of the filter. To form the circumferential annular gap 48 (not shown), an upper cap region 50 is separated from a lower end cap region 52 of the upper end cap 26, forming a shoulder projecting radially outward. However, instead of a common annular gap 48 for all outlet openings 46 in the cover region of the end cap 26, each outlet opening 46 is preferably connected to the outside 45 of the filter via its own flow passage 49, as shown in FIG. 1 . Furthermore, it has proven advantageous to make each flow passage 49 relatively narrow and to select the free diameter of the outlet opening 46 to be smaller than the free diameter of the through-holes 32 of the centering ring 30. In either case, bubbles rising within the flow chamber 14 pass through the through holes 32 in the upper centering ring 30, through the outlet openings 46, and into the individual passages 49 in the upper end cap 26, allowing them to be expelled from the process fluid and out of the filter into the environment in the form of the outside 45 of the filter.

[0026] In a coaxial arrangement of two filter stages with flow from the inside out and flow from below via an annular connector 40, a homogeneous construction of filter media 16, 18 made of a metallic material, in particular stainless steel or titanium, can be used instead of the previous media structure.

[0027] In this embodiment, the inner filter stage, in the form of the first filter media 16, is a three-ply pleated structure made of stainless steel. This structure replaces the volumetric meltblown structure of the polypropylene variant shown above. The mesh size of the two outer layers in the direction of the flow chamber 14 is again relatively coarse, with values ​​between 200 μm and 1000 μm. In contrast, the mesh size of the subsequent inner layers is relatively fine, with values ​​between 0.1 μm and 500 μm. In addition to stainless steel, titanium is also readily available. The pleat density of the pleated filter material is 4 to 8 pleats per square centimeter, and the woven fabrics used include twill, satin, and plain weave. Two to five-ply structures, with mesh sizes that progress from coarse to fine in the direction of flow 24, are also conceivable. Alternatively, sintered filters with similar degassing properties can be used.

[0028] The outer filter stage, in the form of the second filter media 18, also consists of a three-ply pleated structure made of stainless steel with equivalent mesh dimensions on the outside and inside, as described above. Preferably, the pleat density is 0.1 to 6 pleats per centimeter, and the weave type described above is also used. Coating the entire filter or only the individual woven fabrics 16, 18 can further improve the degassing properties, especially if the coating is made with a material that promotes coalescence. In this way, the material used for the filter media 16, 18 can also be passivated to prevent the release of electrons and iron ions. As far as the operating principle of a two-stage degassing filter with a homogeneous metal structure is concerned, this corresponds to the solution described above. Instead of the proposed welding process, the metallic filter media 16, 18 can also be glued to the corresponding end caps 26, 28 or crimped together using metal joining techniques (not shown). For an improved degassing process, it has proven advantageous to select a correspondingly high pleat density for the first filter media 16 and a correspondingly low pleat density for the outer filter media 18.

[0029] The second embodiment according to Figures 3, 6, and 7 will be described below only insofar as it differs significantly from the previously described embodiment. In particular, the same reference numerals as those shown above are used for the same components, and the explanations given therein also apply to this further second embodiment. Instead of the centering ring 30 described above, a single circumferential positioning ring 54 is used for the second embodiment, which is supported on the inner circumferential side of the second filter medium 18 toward its free end region, in each case with a predeterminable axial extent. Each positioning ring 54 has several pairs of centering rods 39 on its outer circumferential side, which at least partially engage in the second filter medium 18 on its inner circumferential side to ensure positioning of the positioning ring 54 at each end region of the second filter medium 18. In this way, the mirror welding process can be effectively supported by two positioning rings 54.

[0030] As shown in particular in FIG. 7 , the second filter element 12, with its outer support 22 and the second filter medium 18 and lower positioning ring 54, is connected, particularly by welding, to a separate annular cap 56, which, in the installed position shown in FIG. 7 , is supported at its bottom end on a flange-like protrusion 58 of the lower end cap 28. In this way, the annular cap 56 rests on a portion of the lower end cap 28 without protruding beyond it. For sealing purposes, in the region of the stepped transition between the protrusion 58 and the other lower end cap 28, a further sealing device 62 is inserted into its radially outwardly opening annular groove 60, thereby sealing the interior of the filter against the environment in the form of the filter exterior 45. Similar to the first sealing device 42 on the annular connector 40, the further sealing device 62 can also be omitted if clamp connections (not shown) are to be used at the respective connection points, which can additionally be secured by welded or adhesive connections.

[0031] Thus, the outer support 22 and second filter media 18, together with the lower locating ring 54, are welded, particularly by mirror welding, to the upper side of the bottom annular cap 56. Furthermore, the inner support tube 20, together with the lower side of the associated filter media 16, is welded, particularly by mirror welding, to the upper side of the actual lower end cap 28. Thus, the upper end of the outer support 22, together with the associated second filter media 18 and upper locating ring 54, is welded to the lower flat end face of the upper end cap 26. In this embodiment, too, the outlet opening 46 of the upper end cap 26 opens into the flow chamber 14.

[0032] However, unlike the previously described embodiments, the first filter element 10 has its own end cap 64, designed as a flat annular disk, which opens a gap-shaped passage space 66 formed by the upper side of the end cap 64 and the adjacent lower side of the upper end cap 26. In this way, the hollow cylindrical flow chamber 14 is connected at its upper end via the passage space 66 for medium communication. This also allows for tolerance compensation between the two filter elements 16, 18. The overall construction of the filter according to the second embodiment uses the same materials as described above. The connection of the individual filter components to each other to obtain the entire filter can be carried out particularly cost-effectively using the aforementioned miller welding process, as well as the aforementioned materials. Furthermore, given the strong welded connections, the filter as a whole can be designed as a disposable product that is easily recyclable. An external view of the filter shown in Figures 2 and 3 is shown in Figure 1.

[0033] As shown in Figures 8 and 9, a total of six filters, each with a cover part 68 that can be removed from the housing 43 for the purpose of removing used filters and replacing them with new elements, are inserted into the vessel housing 43 as described above. The cover part 68 is provided with a retaining device 70 for holding the individual filters, consisting of the first filter element 10 and the second filter element 12, in place. For this purpose, when the cover part 68 is closed, the retaining device 70 presses the individual filters downwards, via their respective annular connectors 40, against a separator or adapter plate 72 having a correspondingly designed annular recess 74. The vessel housing 43 or vessel further has an inlet 76 at its bottom end for gas-containing process fluid, an outlet 78 for gas separated in the vessel 43, and a further outlet 80 for gas-free process fluid; the flow through each filter is from the inside to the outside, starting from the inlet 76 of the vessel 43. The separated gas is passed to one of the outlets 78 in the vessel 43 above a fluid level 82 in the vessel 43. However, process fluid that accumulates within the vessel 43 below this fluid level 82 exits the vessel 43 via a further outlet 80 .

[0034] As shown in FIG. 8, parallel flows pass through each filter from below via openings in the form of annular recesses 74 in the adapter or separator plate 72 in the vessel 43, aligned vertically. In particular, each filter is guided above the fluid level 82 and extends between the separator or adapter plate 72 and the holding device 70. To improve the drainage of the process fluid or process water, suction connections 84 are provided between the individual filters. These suction connections 84 open laterally above the separator or adapter plate 72 and below the fluid level 82 in the vessel 43, and are thus connected to a further outlet 80 for the process fluid. In this way, 3 to 30 degassing filters can easily be accommodated in a tank in the form of the vessel 43. The number of filters used can be selected depending on the volumetric flow rate to be treated. The parallel flows pass through the degassing filters from below via the separator or adapter plate 72. The vessel 43 or vessel housing is preferably made of stainless steel and has an internal coating for passivation and corrosion protection.

[0035] The gas bubbles separated by the first and second filter media 16, 18 due to coalescence and buoyancy separation pass through the flow chamber 14 from the process fluid side to the gas side, located above the fluid level 82 in the vessel 43. The accumulated gas in the flow chamber 14 then reaches the gas discharge side of the vessel 43, equipped with the gas connection 78, via the flow guides in the upper end cap 26, located above the fluid level 82, as already described. The gas-containing process fluid flows continuously through two filter stages, in the form of the first and second filter elements 10, 12, with their associated filter media 16, 18. The first filter stage, in the form of the first filter element 10, then causes a first coalescence or pre-separation of the gas bubbles (air / hydrogen / oxygen). After flowing through the filter stages 10, 12 and into the annular gap between the first and second filter stages 10, 12, formed by the flow chamber 14, the retained gas bubbles coalesce and rise upward, just like the enlarged gas bubbles. After passing through the illustrated venting openings in the upper end cap 26, the gas bubbles pass onto the fluid surface, i.e., onto a fluid level region 82 of varying height according to FIG. 8. Any gas bubbles not yet separated are retained by an outer second venting stage in the form of the second filter element 12, coalesce at this point, and then also rise upwards by buoyancy, rising above the fluid level 82. The filter arrangements mentioned using the corresponding vessel shapes can be used for any venting process for process fluids and are not limited to process water such as that produced during hydrogen electrolysis.

Claims

1. A filter for treating a process fluid, for example a process fluid occurring in particular during hydrogen electrolysis, preferably for separating hydrogen and / or oxygen from process water, said filter comprising a first filter element (10) and a second filter element (12) surrounding said first filter element (10) at a predeterminable radial distance to form a flow chamber (14), each filter element (10, 12) having a filter medium (16, 18) through which the process fluid flows from the outside A filter capable of flowing in an inward or preferably from the inside to the outside flow direction (24), in which, viewed in said flow direction (24), one filter medium (16) forms a first degassing stage which serves to remove gas bubbles from the process fluid by expanding them through coalescence and separation caused by buoyancy forces, followed by a further filter medium (18) which forms a second degassing stage which serves to remove finely distributed gas bubbles remaining in the process fluid by again coalescence, the separation of which occurs by rising caused by buoyancy forces.

2. 2. The filter of claim 1, wherein the preceding filter media (16) in the flow direction (24) comprises a depth filter cartridge designed as a hollow cylindrical filter casing to increase the filter volume.

3. 3. The filter of claim 2, wherein meltblown fibers are used to form the depth filter cartridge, the meltblown fibers preferably being sprayed onto a fluid-permeable support (20) on which the filter casing is supported along its inner periphery.

4. 4. The filter of claim 3, wherein said depth filter cartridge is made of a sintered material.

5. 5. The filter of claim 2, wherein the depth filter cartridge is made of meltblown fibers and has a filter fineness between 10 μm and 200 μm, a fiber diameter between 0.1 μm and 2000 μm, and a mean flow pore diameter between 1 μm and 2000 μm.

6. 6. A filter according to any one of claims 1 to 5, characterized in that, for a homogeneous structure, all components of the filter, such as the filter media (16, 18), end caps (26, 28) and supports (20, 22), consist of the same plastic material, preferably polypropylene.

7. 7. The filter according to claim 1, wherein the filter medium (18) following one of the filter media (16) in the flow direction has a mat structure of at least two layers, preferably three layers.

8. 2. The filter according to claim 1, characterized in that, due to the homogeneous structure, each filter medium is configured to form a two-stage degassing filter from a metal such as stainless steel or titanium, and each filter medium (16, 18) of at least one filter element (10, 12) preferably has a pleated mat structure of at least two, preferably three layers made from metal threads or fibers, and preferably is constructed entirely from stainless steel material.

9. 9. Apparatus comprising a container (43) for housing at least one filter according to any one of claims 1 to 8, the container (43) having at least one inlet (76) for a gas-containing process fluid, an outlet (78) for gas separated in the container (43), and a further outlet (80) for gas-free process fluid, the flow through each filter starting from the inlet (76) of the container (43) and flowing from the inside to the outside, transferring separated gas above a fluid level (82) in the container (43) to one of the outlets (78) in the container (43), and discharging the process fluid accumulated in the container (43) below the fluid level (82) from the container (43) via the further outlet (80).

10. 10. A vessel according to claim 9, characterized in that the parallel flow to each filter runs from below, parallel to the fluid level (82), through a plurality of openings (74) in a separating plate (72) in the vessel (43), and suction connections (84) are provided between the individual filters, which suction connections (84) open above the separating plate (72) and below the fluid level (82) in the vessel (43) and are connected to the further outlet (80) for process fluid.

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