Filter panel and cartridge filter equipped with such a panel

Abstract

The invention relates to a filter panel (12) intended to be installed in a cartridge filter (10), the filter panel (12) comprising a peripheral frame (32) to which a filter cloth (34) is fixed, the frame (32) being formed by two side members (36, 38) connected at each end by end transverse members (40, 42), characterized in that the filter panel (12) comprises an array (R1) of crossbars (44) connecting the inner edges (46, 48, 50, 52) of the frame (32) to each other, the array (R1) of crossbars (44) forming at least one first closed pattern (54) in the center of the frame (32) and comprising at least four diagonal lines (64, 66, 68, 70, 72, 74, 76, 78) which are inclined with respect to the side members (36, 38) and which extend from the first closed pattern (54) to the inner edges (46, 48, 50, 52) of the frame (32).

Description

Technical Field

[0001] The present invention relates to a filter panel of the type intended to be mounted in a cartridge filter and to an associated cartridge filter.

[0002] The invention more particularly relates to a filter panel comprising a peripheral frame and a filter cloth attached to the frame. Technical Background

[0003] Cartridge filters are known for use in water treatment, for example upstream of industrial plants, in particular for the treatment of large liquid flows. Cartridge filters of this type comprise a filter cartridge which is rotatably mounted in a tank and partially immersed in the liquid flow to be filtered.

[0004] The cartridge has multiple filter panels arranged in one or more rows around its perimeter. Each filter panel comprises a frame covered with filter cloth. Each filter panel is bent and then secured to the cartridge to conform to the curvature of the cartridge around its axis of rotation.

[0005] Liquid entering the tank enters the interior of the cartridge and then flows radially from the inside to the outside through the filter panels by gravity before flowing out of the tank. As a result, debris and other impurities are deposited on the inside of the filter panels on the filter cloth.

[0006] To clean the filter surface while filtration continues, the filter is mounted to rotate about the drum axis. To clean a portion of the filter surface, the drum is rotated about its axis to remove that portion of the filter surface from the liquid. The filter surface can then be cleaned by spraying liquid through spray bars arranged around the drum's periphery.

[0007] The filter panels are typically made of fabric stretched over a frame.One of the difficulties in manufacturing the filter panels is that the filter panels must bear the weight of the sludge that accumulates in the cartridge and the continuous cycle of filtering and cleaning.

[0008] Wire cloth has the advantage of being very strong, but it is relatively expensive. Alternatively, known filter cloths can be made from plastic materials such as polypropylene. While the manufacturing costs are much lower than those of wire cloth, this type of filter cloth is more susceptible to damage. It deteriorates very quickly during use, particularly due to the difficulty in ensuring sufficient tension on the frame forming the filter panel.

[0009] Panels as disclosed in US Pat. No. 6,484,885 B1 are also known.

[0010] The present invention specifically aims to solve the above-mentioned problems by providing a filter panel that is stronger and more economical to manufacture and that guarantees optimal filtration. Summary of the Invention

[0011] A filter panel for installation in a cartridge filter, the filter panel having a peripheral frame to which a filter cloth is fastened, the frame being formed by two longitudinal members connected at each end by an end cross member, characterised in that the filter panel has a grid of cross members connecting the inner edges of the frame to one another, the grid of cross members forming at least one first closed pattern in the centre of the frame and having at least four diagonals which are inclined relative to the longitudinal members and extend from the first closed pattern to the inner edges of the frame, and characterised in that the grid of cross members has at least two intermediate cross members which are parallel to the end cross members and are arranged on either side of the first closed pattern, respectively.

[0012] The present invention achieves an optimal compromise between filter cloth rigidity and flexibility for installation in cartridge filters. Specifically, in use, it has been shown that, after the filter cloth has been attached to the frame, full tensioning of the filter cloth is achieved, even though the filter cloth has not yet been fully tensioned on the frame. This tensioning of the filter cloth allows for excellent filtration performance while ensuring a longer service life for the filter panel.

[0013] According to other features of the present invention:

[0014] - at least four diagonal lines each extending from the first closed pattern to a corner of the frame;

[0015] - at least four diagonal lines each extending from the first closed pattern to an end of the intermediate cross member;

[0016] - Each intermediate cross member crosses at least two diagonals;

[0017] - the grid of crosspieces forms a second closed pattern concentric with the first closed pattern;

[0018] - the grid of crosspieces comprises inclined crosspieces which cross the diagonal lines and are inclined relative to the longitudinal members;

[0019] - the grid of crosspieces has a transverse plane of symmetry intersecting the first closed pattern at its center;

[0020] - the grid of crosspieces comprises two transverse crosspieces, each of which extends transversely from the longitudinal member to at least the first closed pattern;

[0021] - the grid of crosspieces comprises two longitudinal crosspieces, each of which extends longitudinally from an end crosspiece to an intermediate crosspiece;

[0022] - the first closed pattern is a polygon having at least four sides, preferably six sides;

[0023] - at least four diagonal lines connect to the first closed pattern at the corners of the polygon;

[0024] - the cross section of the crosspieces forming the grid of crosspieces has a trapezoidal profile, the vertices of which are oriented on the side edges of the filter cloth;

[0025] - the grid of rungs comprises at least two intermediate rungs, the trapezoidal profiles of which define an area at least 20% larger than the area defined by the trapezoidal profiles of the diagonals;

[0026] - the first closed pattern is repeated at least once on each side of the closed pattern located in the center of the frame;

[0027] - the frame and the grid of the crosspieces are made in one piece from molded plastic;

[0028] The filter cloth is made of plastic and is welded to one side of the frame, comprising the corresponding side of the grid of crosspieces.

[0029] The present invention also provides a cartridge filter for filtering liquid, comprising a cartridge rotatably mounted in a container, characterized in that the cartridge filter comprises a filter panel according to any one of the preceding features, the filter panel being attached to the cartridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features and advantages of the present invention will become apparent from the following detailed description, for which reference is made to the accompanying drawings, in which:

[0031] Figure 1 is a perspective view illustrating a cartridge filter having a filter panel in accordance with the teachings of the present invention;

[0032] Figure 2 It shows that Figure 1 A schematic side view of a cartridge filter is shown with two filter panels mounted on the cartridge;

[0033] Figure 3 The figure shows the Figure 1 an exploded perspective view of a filter panel of a cartridge filter and a filter cloth of the filter panel before securing the filter cloth to a frame of the filter panel;

[0034] Figure 4 is shown with its filter cloth attached to the top Figure 3 A side view of the filter panel;

[0035] Figure 5 The filter cloth is partially damaged. Figure 3 A top view of the filter panel with damage;

[0036] Figure 6 yes Figure 3 A cross-sectional view AA of a cross section of the filter panel;

[0037] Figure 7 It shows Figure 3 sectional view BB of a cross section of a secondary intermediate cross member of the filter panel;

[0038] Figure 8 is similar to Figure 5 A pulled-out top view showing an alternative design for a filter panel with a grid having a repeating closed pattern. DETAILED DESCRIPTION

[0039] In the following description, the same, similar or like elements will be referred to by the same reference numerals.

[0040] Figure 1 A cartridge filter 10 having a filter panel 12 in accordance with the teachings of the present invention is shown.

[0041] The cartridge filter 10 has a container 14 with an inlet 16 for the liquid to be filtered and an outlet 18. The flow direction of the liquid inside the cartridge filter 10 is indicated by arrows F1 and F2.

[0042] Inside the tank 14, a cartridge 20 is mounted for rotation about a horizontal axis A1. The cartridge 20 has a cylindrical structure on which the filter panel 12 is mounted.

[0043] According to the embodiment shown, the cartridge 20 includes six filter panels 12, more specifically three series of two filter panels 12. According to the configuration shown, and as shown Figure 2 As shown in the figure, two filter panels 12 are used to form a complete circumference of the barrel 20. Therefore, there are two filter panels 12 in each group, which are mounted on the barrel 20 in a curved manner and then fixed to the barrel 20, for example, by fixing plates 23, 25, so as to form a part of a cylinder. Therefore, in this embodiment, each filter panel 12 has a generally semicircular profile when mounted on the barrel 20.

[0044] According to alternative embodiments (not shown), the cartridge 20 may include a greater or lesser number of groups of filter panels 12, and each group may include a greater number of filter panels 12. For example, when a larger diameter cartridge 20 is desired without changing the size of the filter panels 12, four filter panels 12 may be used to achieve the cartridge circumference.

[0045] The cylindrical filter 10 also has a spray bar 24 with a plurality of spray nozzles 26. The spray bar 24 here extends parallel to the axis of rotation Al outside the cylinder 20 so that the filter panels 12 can be unblocked. In addition, an upper portion of a channel 28 is arranged inside the cylinder 20 in order to recover residues resulting from the unblocking of the filter panels 12 and in order to discharge these residues via a discharge aperture 30 to the outside of the cylindrical filter 10.

[0046] Before being installed in the cylindrical filter 10, each filter panel 12 is in the form of a relatively flat plate, as Figures 3 to 5 shown. The filter panels 12 here extend in a horizontal plane PI.

[0047] For the description of the invention and the understanding of the claims, when the filter panels 12 are in the state of plates, i.e. before being assembled on the cylinder 20, the vertical orientation, the longitudinal orientation and the transverse orientation of the references V, L, T indicated according to Figures 3 to 7 will be used by way of non-limiting and non-restricting reference to the Earth's gravity, the longitudinal L and transverse T axes of these orientations extending in a horizontal plane. According to Figure 5 the longitudinal orientation along the L axis from the rear to the front corresponding to the orientation from the bottom to the top, and according to Figure 5 the transverse orientation along the T axis from the left to the right corresponding to the orientation from the left to the right will be used as non-limiting examples.

[0048] The filter panel 12 comprises a peripheral frame 32 to which a filter cloth 34 is attached. The frame 32 is formed from two longitudinal members 36, 38 connected at each end by end transverse members 40, 42.

[0049] The mesh R1 of crosspieces 44 connects the inner edges 46, 48, 50, 52 of the frame 32 to one another. The mesh R1 of crosspieces 44 here refers to the mesh of crosspieces or bars in the plane PI of the filter panel 12 which help to ensure that the frame 32 has a certain rigidity while allowing the filter panel 12 to bend about the transverse axis along the longitudinal members 36, 38 to allow the filter panel 12 to be installed on the cylinder 20 in the position of the circular arc formed as Figure 2 shown.

[0050] Advantageously, the mesh R1 of crosspieces 44 forms a first closed pattern 54 in the centre of the frame 32. The closed pattern here refers to the shape drawn by a set of consecutive crosspieces 44. The first closed pattern 54 is here a hexagon and is here empty, i.e. the first closed pattern is not crossed by any crosspiece 44.

[0051] In an alternative embodiment (not shown), the first closed pattern may be another type of polygon, such as a square, an octagon. Alternatively, the first closed pattern may be a circle or an ellipse.

[0052] According to the embodiment shown, the hexagon has two opposing first sides 56, 58 that are parallel to, and therefore transverse to, the end rails 40, 42. When the first closed pattern 54 is centered in the frame 32, the hexagon has two opposing first vertices 60, 62 that are located midway between the two end rails 40, 42.

[0053] Advantageously, the grid R1 of the crosspiece 44 comprises at least four, in this case eight, diagonals 64 , 66 , 68 , 70 , 72 , 74 , 76 , 78 , which are inclined relative to the longitudinal members 36 , 38 and extend from the first closed pattern 54 to the inner edges 46 , 48 of the frame 32 .

[0054] According to the illustrated embodiment, the four major diagonals 64, 66, 68, 70 each extend from the middle of the sides 80, 82, 84, 86 of the hexagon that slope to the end rails 40, 42 to the inner edges 46, 48 of the opposing side rails 36, 38. The four minor diagonals 72, 74, 76, 78 each extend from the end of one of the first sides 56, 58 of the hexagon to a corner 88, 90, 92, 94 of the frame 32.

[0055] Advantageously, the grid R1 of the crosspieces 44 comprises intermediate crosspieces 96, 98, 100, 102 which are parallel to the end crosspieces 40, 42 and are arranged respectively on both sides of the first closed pattern 54. Here, two main intermediate crosspieces 96, 98 on both sides of the first closed pattern 54 each connect two longitudinal members 36, 38 at the level of the end of one of the main diagonals 64, 66, 68, 70.

[0056] Here, four secondary intermediate cross members 100 , 102 arranged on both sides of the first closed pattern 54 each connect two longitudinal members 36 , 38 .

[0057] In the embodiment shown, the secondary intermediate cross members 100 , 102 pass through the secondary diagonals 72 , 74 , 76 , 78 .

[0058] Advantageously, the mesh R1 of the crosspieces 44 forms a second closed pattern 104 concentric with the first closed pattern 54. The second closed pattern 104 is here a hexagon, the sides of which, parallel to the end crosspieces 40, 42, are formed by the central portions 106, 108 of the main intermediate crosspieces 96, 98, and the other sides of which are formed by the inclined crosspieces 110, 112, 114, 116 which pass through the main diagonals 64, 66, 68, 70 and are inclined relative to the longitudinal members 36, 38.

[0059] Advantageously, the grid R1 of crosspieces 44 comprises two transverse crosspieces 118 , 120 each of which extends transversely from the first closed pattern 54 , here from the first two vertices 60 , 62 of the hexagon, to the opposite longitudinal members 36 , 38 .

[0060] According to one embodiment, the two transverse rails 118 , 120 may extend to the center of the first closed pattern 54 and thus form a continuous crossbar from one edge of the frame 32 to the other.

[0061] Advantageously, the grid R1 of crosspieces 44 comprises two longitudinal crosspieces 122, 124 each extending longitudinally from an end crossmember 40, 42 (here from the middle of each end crossmember 40, 42) to an intermediate crossmember 96, 98, 100, 102 (here to each main intermediate crossmember 96, 98).

[0062] According to the embodiment shown, the grid R1 of the crosspiece 44 has a transverse plane of symmetry P2 that intersects the first closed pattern 54 at its center and passes through the transverse crosspieces 118 , 120 .

[0063] like Figure 6 and Figure 7 As shown, the crosspiece 44 preferably has a generally triangular or trapezoidal cross-section with its apex oriented toward the filter cloth 34 . Figure 6 A cross section of most of the crosspiece 44 is shown, particularly including the diagonals 64 , 66 , 68 , 70 , 72 , 74 , 76 , 78 , the main intermediate cross members 96 , 98 , and the angled crosspieces 110 , 112 , 114 , 116 .

[0064] Figure 7 The cross section of the secondary intermediate cross members 100, 102 is shown. Due to the rigidity function of the secondary intermediate cross members 100, 102, this cross section is larger than the cross section of the other cross members 44. For example, the trapezoidal profile here defines an area that is 20% to 40% larger than the area defined by the trapezoidal profile of the other cross members 44.

[0065] Advantageously, the frame 32 and the mesh R1 of the crosspiece 44 are made in one piece by injecting a plastic material (e.g. polyethylene (HDPE) or polypropylene (PP), or polyamide (PA) such as nylon) into a mold. The frame 32 can be made of the same plastic material as the filter cloth 34.

[0066] Advantageously, the filter cloth 34 is welded to the top surface 126 of the frame 32, including the top surface of the mesh R1 of the crosspiece 44. Figure 6 and Figure 7 As shown, the top of each spacer 44 is welded to the filter cloth 34. Different welding methods can be used, the purpose of which is to Figure 1 and Figure 2 That bending ensures full tension in the filter cloth 34 to achieve a secure connection between the filter cloth 34 and the frame 32 and bracket 44 .

[0067] Note that the filter panel 12 is intended to be installed in the cartridge filter 10 so that the filter cloth 34 is on the outside of the cylinder.

[0068] Due to the structure of the mesh R1 of the crosspieces 44 described above, good rigidity of the filter panel 12 is obtained, while allowing good flexibility in the longitudinal direction, namely by supporting the longitudinal members 36 , 38 .

[0069] The structure of the first closed pattern 54 associated with the diagonals 64, 66, 68, 70, 72, 74, 76, 78 enables the filter panel 12 to withstand bending stresses applied more specifically along the transverse plane of symmetry P2. It can be seen that the central portion of the mesh R1 of the crosspiece 44 forms a spider web that enables the filter panel 12 to withstand very high stresses even when it is installed in the cartridge filter 10 and supports high loads, in particular large amounts of liquid to be filtered and sludge collected on the walls of the filter cloth 34.

[0070] Another advantage of the filter panel 12 is that it does not require a grid with overly tightly spaced rungs 44 to withstand stress. This allows the formation of windows 128 that are large enough to maximize the area of ​​contact between the filter cloth 34 and the liquid to be filtered while minimizing the amount of water drawn in by the walls of the rungs 44 when the drum 20 is rotated to clean the filter panel 12 using the water spray nozzles 26.

[0071] In the absence of excessive water addition by the walls of the crosspieces 44, in particular due to the secondary intermediate crosspieces 100, 102, it is possible to optimally add debris and other solid matter contained in the liquid to be filtered and allow them to drain through the channels 28. Thus, the choice of a larger cross section for the secondary intermediate crosspieces 100, 102 compared to the other crosspieces 44 makes it possible to minimize the amount of water added by the majority of the crosspieces 44, while at the same time providing sufficient surface area for the addition of debris and solid matter to the secondary intermediate crosspieces 100, 102.

[0072] according to Figure 8 In the alternative embodiment shown, the filter panel 12 is Figures 3 to 7 The filter panel of is different in that the grid R1 of the crosspiece 44 includes the center pattern three times, ie the first closed pattern 54 and the second closed pattern 104 are repeated once on each side of the closed pattern set 54 , 104 located in the center of the frame 32 .

[0073] according to Figure 8 In the embodiment shown, it is noted that the transverse crosspieces 118, 120 extend to the center of each first closed pattern 54, which here forms three crosspieces on the frame 32. Figure 8 The illustrated embodiment may also have transverse rails 118 , 120 as in the previous embodiments, wherein the transverse rails 118 , 120 terminate at the apex of each first closed pattern 54 .

Claims

1. A cartridge filter comprising a filter panel (12), wherein the filter panel (12) comprises: a peripheral frame (32) formed from two longitudinal members (36, 38) connected at each end by an end cross member (40, 42), a grid (R1) of crosspieces (44), said grid of crosspieces connecting the inner edges (46, 48, 50, 52) of the peripheral frame (32) to one another, said grid (R1) of crosspieces (44) forming at least one first closed pattern (54) in the center of the peripheral frame (32) and having at least four diagonal lines, said at least four diagonal lines being inclined relative to the longitudinal members (36, 38) and extending from the first closed pattern (54) to the inner edges (46, 48, 50, 52) of the peripheral frame (32), and said grid (R1) of crosspieces (44) having at least two intermediate crosspieces, said at least two intermediate crosspieces being parallel to the end crosspieces (40, 42) and being arranged on two sides of the first closed pattern (54), respectively, A filter cloth (34) is fastened to the peripheral frame (32).

2. The cartridge filter according to claim 1, wherein The at least four diagonal lines each extend from the first closed pattern (54) to a corner (88, 90, 92, 94) of the peripheral frame (32).

3. The cartridge filter according to claim 1 or 2, characterized in that: At least four diagonal lines each extend from the first closed pattern (54) to an end of the intermediate cross member.

4. The cartridge filter according to claim 1 or 2, characterized in that: Each intermediate cross member crosses at least two diagonals.

5. The cartridge filter according to claim 1 or 2, characterized in that: The grid (R1) of the crosspiece (44) forms a second closed pattern (104) concentric with the first closed pattern (54).

6. The cartridge filter according to claim 1 or 2, characterized in that: The grid (R1) of the crosspieces (44) includes inclined crosspieces (110, 112, 114, 116) that cross a diagonal line and are inclined relative to the longitudinal members (36, 38).

7. The cartridge filter according to claim 1 or 2, characterized in that: The grid (R1) of the crosspiece (44) has a transverse plane of symmetry (P2) that intersects the first closed pattern (54) at its center.

8. The cartridge filter according to claim 1 or 2, characterized in that: The grid (R1) of the crosspiece (44) includes two transverse crosspieces (118, 120) each extending transversely from a longitudinal member (36, 38) to at least the first closed pattern (54).

9. The cartridge filter according to claim 1 or 2, characterized in that: The grid (R1) of the crosspiece (44) includes two longitudinal crosspieces (122, 124) each extending longitudinally from an end crossmember (40, 42) to an intermediate crossmember.

10. The cartridge filter according to claim 1 or 2, characterized in that: The first closed pattern (54) is a polygon having at least four sides.

11. The cartridge filter according to claim 10, characterized in that At least four diagonal lines connect to the first closed pattern (54) at the corners of the polygon.

12. The cartridge filter according to claim 1 or 2, characterized in that: The cross section of the crosspiece (44) has a trapezoidal profile, the apex of which is oriented on the side of the filter cloth (34).

13. The cartridge filter according to claim 12, wherein: The grid (R1) of the crosspiece (44) comprises at least two intermediate cross members, the trapezoidal profile of which defines an area that is at least 20% larger than the area defined by the trapezoidal profile of the diagonals.

14. The cartridge filter according to claim 1 or 2, characterized in that: The grid (R1) of the crosspiece (44) includes three first closed patterns (54).

15. The cartridge filter according to claim 1 or 2, characterized in that: The peripheral frame (32) and the grid (R1) of the crosspiece (44) are made in one piece by molding of plastic.

16. The cartridge filter according to claim 15, wherein The filter cloth (34) is made of plastic and is welded to one side of the peripheral frame (32), including the corresponding side of the grid (R1) of the crosspiece (44).

17. The cartridge filter according to claim 1 or 2, characterized in that: The cartridge filter includes a cartridge (20) rotatably mounted in a container (14), the cartridge filter including a filter panel (12) attached to the cartridge (20).

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