Seamless seal of filter element

Abstract

A filter element (1) or filter element (1) system for wet filtration, comprising a sealing edge (6) and at least one sealing material (16) in a sealing area (12) within the sealing edge, which filter element (1) or filter element (1) system is intended to be cleaned with lower frequency, faster speed and, most importantly, higher efficiency while complying with the required hygiene regulations. To this end, the sealing material (16) is embedded in or applied to the sealing area (12) such that the sealing material (16) is at least partially thermally and / or chemically bonded to the substrate.

Description

Background Technology

[0001] This invention relates to a method for manufacturing a filter element for wet filtration, the filter element comprising a filter frame made of a substrate and at least one groove in the filter frame. Furthermore, this invention relates to a filter plate, a system comprising at least two filter plates, and a filter press.

[0002] Wet filtration is a method for separating solids from liquids. In this method, a suspension is passed through a filter medium that traps the solids (also called the filter cake) while allowing the purified liquid (also called the filtrate) to pass through. In wet filtration using a filter press, filter elements are used to further compress the filter cake by applying pressure to reduce the residual moisture in the cake. The filter element has a drain surface for collecting the filtrate and a filtrate discharge area for discharging the filtrate or for introducing a liquid or gaseous medium into the filter chamber for further processing of the filter cake. In such filter presses, multiple filter elements are arranged in series.

[0003] Filter elements typically consist of a frame-like sealing edge and a centrally located filter surface surrounded by sealing edges on all four sides. Filter elements, or particularly combinations of two filter elements arranged front to back, can be configured in various ways.

[0004] A filter plate and filter frame combination refers to two filter elements arranged one behind the other, where the filter plate does not have a cavity recess; that is, the surface of the drainage protrusion or groove of the filtration area is flush with the sealing edge surrounding the filtration area. To form a filtration cavity, the filter plate and filter frame are paired, the filter frame consisting essentially only of the sealing edge, with an open area in the center to form the filtration cavity. The filtration cavity is then formed by another filter plate on the opposite side of the filter frame. This combination is the simplest system for industrial solid-liquid separation.

[0005] The filter element can also be designed as a cavity filter plate, in which the filter cavity is integrated into the filter element. This filter cavity is formed by the recessed arrangement of filter areas, drainage bosses, or grooves relative to the sealing edge. When two cavity filter plates are placed abutting against each other, a filter cavity is formed between them due to the recessed filter areas on both sides. Typically, a so-called sealing edge bevel is arranged between the filter areas and the sealing edge, making it easier for the formed filter cake to fall from the filter cavity when the filter press is opened.

[0006] Filter elements can also be designed as diaphragm chamber filter plates. Diaphragm chamber filter plates are an improvement on chamber filter plates, designed to further dewater the filter cake by applying pressure to it through a diaphragm, thereby shortening the filtration time. Otherwise, relying solely on the pressure of the feed pump would prolong the filtration time. Diaphragm chamber filter plates typically also integrate the filter chamber into the design.

[0007] Diaphragm combination filter plates can also be used as filter elements. These diaphragm combination filter plates are simply cavity filter plates, but the boundary surfaces of their filter cavities are adapted to the contours of the diaphragm.

[0008] All these constructions of the filter element are the subject of this application.

[0009] In some applications of wet filtration using filter presses, seals are required between filter elements, preferably on relatively flat surfaces of the sealing edges. Various sealing profiles (such as round ropes or O-rings) are used for this purpose, installed within corresponding grooves in the sealing surfaces. This is primarily done at openings or recesses in the flat sealing surfaces that interrupt the filter elements. These are typically orifices or filter chambers.

[0010] In particular, installing the sealing profile is both labor-intensive and difficult. As a result, it is not always possible to ensure that the seal is uniform throughout the entire area. Cleaning the filter element in the sealing area is also very time-consuming, especially when additional hygiene regulations are important. Bacterial growth can easily occur, especially in the area between the tank and the seal, which increases the frequency of cleaning cycles. For optimal cleaning results, the sealing profile must be removed and reinstalled after each cleaning.

[0011] Therefore, cleaning filter plates (especially those in sealing areas and those in filtration processes where special hygiene regulations apply due to the nature of the filtrate) is both time-consuming and labor-intensive. Summary of the Invention

[0012] Therefore, the object of the present invention is particularly to provide a filter element that can be cleaned at a lower frequency, a faster speed, and, most importantly, a higher efficiency, while meeting the required hygiene regulations.

[0013] According to the present invention, this problem is addressed by the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0014] This invention is based on the consideration that, in particular, gaps between the seal and the filter element groove promote bacterial growth, leading to a shortened cleaning cycle. It is precisely because of bacterial growth in these gaps that the entire seal must be removed, cleaned, or replaced and reinstalled. Therefore, based on the derivation of this invention, the following conclusion is drawn: the external seal inserted into the groove should be omitted. Instead, the sealing material should be applied directly to the sealing area of ​​the sealing edge or to the surface of the sealing area of ​​the sealing edge, and this should be done as part of the seal manufacturing process, specifically by thermally and / or chemically bonding the sealing material to the substrate of the sealing edge or sealing area. This material bonding prevents the formation of gaps between the seal and the sealing area that promote bacterial growth.

[0015] Methods for applying or embedding sealing material onto or into a sealing edge can now also apply the seal to a flat surface of the sealing edge. However, in a preferred embodiment, the sealing area is constructed as a groove. This irreversible embedding of the seal into the sealing edge or groove of the filter element can be achieved by welding or other additive manufacturing processes.

[0016] In a preferred embodiment, the groove is completely filled with sealing material, so that no gaps are left even in edge areas that might promote bacterial growth. In additional or alternative embodiments, the sealing material may also protrude from the groove, such that it extends beyond the surface of the filter element or sealing edge in cross-section.

[0017] After the sealing material is inserted or applied, in a preferred embodiment, the seal may be post-processed using mechanical and / or thermal processes to obtain the desired seal shape. In particular, it is conceivable to grind the seal flat to be flush with the surface of the sealing edge, thereby forming a flat surface; however, this flat surface exhibits varying elasticity in the sealing area. Alternatively, the seal may also protrude from the surface of the sealing edge and be machined to achieve the desired profile or cross-sectional profile.

[0018] The seals are preferably made of elastomers or thermoplastic elastomers, especially in the sealing edge area, where their Shore hardness is lower than that of the filter plate substrate. Furthermore, a hardness range of 20 Shore A to 50 Shore D has proven advantageous for the seals according to DIN ISO 815-1. The sealing material also possesses resilience, preferably with a compression set of less than 50%.

[0019] In a filter press, multiple filter elements are arranged in series such that the base surface of the sealing edge of one filter element corresponds to the base surface of the sealing edge of an adjacent filter element. During operation, these base surfaces of the adjacent sealing edges abut each other substantially flat. In a particularly preferred embodiment, at least one base surface of the sealing edge has a material rib that is adapted in position and design to the seal of the adjacent filter element. When the filter elements are used, i.e., when the two filter elements are arranged directly above or adjacent to each other, the material rib engages with the seal of the adjacent filter element, thereby ensuring that the space between the filter elements is sealed. In such a scenario, the material rib and the seal can be designed such that the material rib is pressed into and deformed by the seal.

[0020] In a preferred embodiment, the material protrusions are made of the same substrate as the filter frame and thus protrude therefrom in the form of a molded feature.

[0021] In a preferred embodiment, the material protrusions are formed as one or more sealing ribs. If multiple sealing ribs are present, they may extend substantially parallel to each other. The material of the sealing ribs should be chosen to have a harderness than the corresponding sealing material of the mating and opposing filter plate. The geometry of the ribs can vary, and where they are pressed into the sealing material, they can be dome-shaped, flat, or even pointed. The geometry can be specifically adapted to the required internal pressure that the seal needs to withstand and the corresponding hardness of the sealing material.

[0022] The advantages of this invention are particularly evident in the robust bond between the seal and the filter element, which eliminates the need for maintenance in this area; specifically, it eliminates the need to replace the seal. Furthermore, the manufacturing process avoids gaps between the groove and the seal, thus meeting the highest hygiene standards and requirements. The uniformity of the seal and the possibility of post-processing allow for a particularly uniform pressure distribution in the sealing profile. Attached Figure Description

[0023] The invention is further described with reference to the embodiments shown in the accompanying drawings. The drawings show: Figure 1 Two filter elements arranged one in front of the other are shown, with circumferential seals. Figure 2 A system consisting of two adjacent filter elements with a seal is shown, and Figure 3 A system comprising two adjacent filter elements with material protrusions is shown. Figure 4 A system comprising two adjacent filter elements and two rounded sealing ribs is shown. Figure 5 A system comprising two adjacent filter elements and two flat sealing ribs is shown.

[0024] The illustrations in the accompanying drawings are simplified and schematic. Different views of components may be drawn to different scales. Components that are identical or have the same structure use the same reference numerals. Detailed Implementation

[0025] Figure 1 The illustrated implementation shows one embodiment of two filter elements 1 arranged sequentially front to back. Figure 1 The diagram illustrates a system consisting of a filter plate 2 and a filter frame 4 arranged in front of it. As described in the background section, the invention, and the illustrations in all the accompanying drawings, are not limited to the combination of filter plate 2 and filter frame 4, but are applicable to all conceivable filtration elements, particularly chamber filter plates, diaphragm chamber filter plates, and diaphragm combination filter plates. Figure 1The filter element 1 visible from the front is designed as a filter frame 4. Behind the filter frame 4, a second filter element 1, serving as a filter plate 2, is visible. This filter plate 2 includes sealing edges 6 and a centrally located filtration area 8, which is surrounded by sealing edges 6 on all four sides. Filtrate discharge channels 10 are provided in all corners of the sealing edges 6 of the filter frame 4 and the filter plate 2, through which filtrate can be discharged. However, filtrate discharge channels 10 can also be provided only in some corners. For this purpose, corresponding holes 11 are provided in the filter frame, connecting the filtrate chamber to the filtrate discharge channel 10, through which filtrate can be discharged.

[0026] Figure 1 The filter frame shown has a sealing region 12 surrounding the sealing edge 6, which takes the form of a groove 14 filled with sealing material 16. Furthermore, a groove 14 filled with sealing material 16 is also provided around each filtrate discharge channel 10. As a result, each filtrate discharge channel 10 is individually sealed, and the filtration region 8 and the filtration chamber are also sealed and isolated from the outside.

[0027] Figure 2 and Figure 3 The illustrated embodiment shows two adjacent filter elements 1 at section A, which, as an example, take the form of a filter plate 2 and a filter frame 4. Figure 2 and Figure 3 Not Figure 1 Instead of showing the precise cross-section, it illustrates alternative constructions that differ, particularly in the location and design of the seals.

[0028] Although the filter elements 1 are shown spaced apart for clarity, in use, the base surfaces 18 of the sealing edges 6 are substantially directly overlapped, so that the seal 16 is in direct contact with the adjacent filter element 1. Figure 2 and Figure 3 The illustrated embodiments show only one filter element 1 with seals 16 on both sides, but it is also possible to have another filter element 1 with seals 16, or to have each filter element 1 with seals 16 on only one or both sides. This also applies to the material protrusions 20 described later.

[0029] exist Figure 2In the illustrated embodiment, the filter plate 2 has two grooves 14 in the sealing edge 6, both of which are completely filled with sealing material 16, causing the seal 16 to protrude beyond the base surface 18 of the sealing edge 6. In this embodiment, adjacent filter frames 4 have neither grooves nor seals, but instead have flat base surfaces 18 of the sealing edge 6. When using two filter elements 1, the two base surfaces 18 of the sealing edge 6 (as shown) are directly stacked on top of each other, causing the protruding seal 16 of the filter plate 2 to press against the flat base surface 18 of the filter frame 4 and seal the gap between the two filter elements 1. The restoring force of the sealing material 16 ensures that this process is repeatable, meaning that the filter elements 1 can be separated and reassembled without compromising the sealing effect.

[0030] exist Figure 3 In the illustrated embodiment, the seal 16 is designed slightly differently. Figure 2 Unlike other filter plates, the seal 16 does not protrude but is flush with the base surface 18 of the sealing edge 6 of the filter plate 2. Alternatively, the seal 16 may also be designed to be slightly recessed relative to the base surface 18. For this purpose, the filter frame 4 includes a material rib 20 in the sealing edge, such that when the filter elements 1 are closed together, the material rib 20 engages with the seal 16 of the adjacent filter plate 2 or the material rib 20 is pressed into the seal 16 of the adjacent filter plate 2. This achieves a sealing effect not only through compression when the filter elements 1 are pressed together but also through a form-fit seal.

[0031] and Figure 3 Similar systems to the one shown are in Figure 4 and Figure 5 The implementation scheme shown is illustrated. The difference lies in the source... Figure 3 The material protrusion 20 is now formed as two parallel sealing ribs 22, and has adjacent displacement regions 24. Figure 4 In the embodiment shown, the sealing rib 22 is rounded, while... Figure 5 In the illustrated implementation, they are flat. Theoretically, conical sealing ribs 22, as well as combinations of different constructions within a single filter plate, are also conceivable.

[0032] The rigid, protruding sealing ribs 22 are pressed into the soft, flat sealing material 16 located on opposite sides, thereby forming a form fit through the displacement of the sealing material between the sealing ribs 22. This is achieved by the closing force of the filter press, i.e., by pressing the filter elements together. Specifically, the sealing material 16 is pressed into the displacement zone 24, which is arranged laterally to adjacent sealing ribs 22. Figure 4 and Figure 5 In the illustrated embodiment, the displacement zone 24 extends even into the base surface 18, thus forming a recess. The restoring force of the sealing material 16 allows the seal between the filter elements 1 to be repeated multiple times.

[0033] List of reference numerals in the attached diagram: 1: Filter element; 2: Filter plate; 4: Filter frame; 6: Sealing edge; 8: Filtering area; 10: Filtrate discharge channel; 12: Sealed area; 14: Trough; 16: Seals / Sealing Materials; 18: Base plane; 20: Material protrusions; 22: Sealing rib; 24: Displacement zone.

Claims

1. A method for manufacturing a filter element (1) for wet filtration, said filter element (1) comprising a sealing edge (6) made of a substrate and at least one sealing region (12) of said sealing edge (6), wherein, The sealing material (16) is embedded in or coated onto the sealing region (12) such that the sealing material (16) is at least partially thermally and / or chemically bonded to the substrate.

2. The method for manufacturing the filter element (1) according to claim 1, characterized in that, The sealing area (12) is constructed as a groove (14).

3. The method for manufacturing the filter element (1) according to claim 2, characterized in that, The sealing material (16) substantially completely fills the groove (14) and / or the sealing material (16) protrudes from the base surface (18) of the sealing edge (6).

4. A method for manufacturing the filter element (1) according to any one of claims 1 to 3, characterized in that, The sealing material (16) is then post-processed by mechanical manufacturing processes and / or thermal manufacturing processes.

5. A filter element (1) for wet filtration, the filter element (1) comprising a sealing edge (6) and at least one seal (16) in a sealing region (12) located within the sealing edge (6), the filter element (1) being manufactured by the manufacturing method according to any one of claims 1 to 4.

6. The filter element (1) for wet filtration according to claim 5, characterized in that, The sealing material (16) is an elastomer or a thermoplastic elastomer.

7. The filter element (1) for wet filtration according to claim 5 or 6, characterized in that, According to DIN ISO 815-1, the hardness of the sealing material (16) is between 20 Shore A and 45 Shore A.

8. A system comprising at least two filter elements (1) for wet filtration in a filter press, said system comprising at least one filter element (1) according to any one of claims 5 to 7, wherein, At least one filter element (1) has a material protrusion (20) in the sealing edge (6) region, the material protrusion being adapted in position and construction to the sealing material (16) of the adjacent filter element (1) such that when the filter element (1) is in use, the material protrusion (20) engages with the sealing material (16) of the adjacent filter element (1).

9. The system comprising at least two filter elements (1) according to claim 8, characterized in that, The material protrusion (20) is formed from the substrate of the sealing edge (6).

10. A filter press for wet filtration, the filter press comprising a plurality of filter elements (1) according to any one of claims 5 to 7, and / or the filter press comprising a system of filter elements (1) according to any one of claims 8 to 9.

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