Sleeve for filtration unit with backwashing

Abstract

The sleeve (70) is configured to be coaxially mounted inside a stack of annular filtration elements and is provided with holes (72), each hole having an inner orifice (73) and an outer orifice (74). The outer orifice (74) of each hole (72) is configured to face and communicate with the inner passage of the filtration element, and the holes (72) are configured as several circumferential rows, each circumferential row extending over the entire circumference of the sleeve (70), and at least some of the holes (72) have elongated outer orifices (74) in the circumferential direction.

Description

Technical Field

[0001] The present disclosure relates to a sleeve for a filtration unit with backwashing, a filtration assembly, and a filtration unit with backwashing. More particularly, the present disclosure relates to improving the backwashing efficiency of such filtration units.

Background Art

[0002] Patent Document 1 describes a filtration unit including at least two filtration elements, each filtration element having an inner surface, an outer surface, a filtration mesh, two concentric edges, an inner edge and an outer edge through which the filtration mesh extends, respectively, and radial ribs provided at least on the inner surface, the radial ribs extending between the concentric edges and being circumferentially distributed so as to form different sectors on the inner surface. The filtration elements are configured to be assembled with each other such that their respective inner surfaces face each other so as to define a space therebetween, and the radial ribs that divide the sectors form circumferential partitions within the space. At least one of the inner edge and the outer edge has a passage communicating with the corresponding sector. The filtration elements are stacked axially between an upper cover and a lower cover.

[0003] By stacking a selected number of pairs of filtration elements, a desired filter area is obtained for the intended application. Generally, the fluid to be filtered passes through the stack through the inner passage of the inner edge, passes through the filtration mesh, and after being purified, flows out through the outer passage defined within the outer edge. Of course, the flow of fluid through the filtration mesh can be reversed or adjusted in some other way.

[0004] The filter described in the document further comprises a flow divider arranged coaxially with the filtration element, each of which has different distribution columns and a rotating backwash distributor provided in the first cover. The rotating backwash distributor has a shutter with a discharge opening, which rotates, thereby periodically and selectively communicating the discharge opening with each distribution column, thereby periodically and selectively establishing communication between each distribution column and its respective inner passage.

[0005] In this way, the fluid flow is periodically reversed in sectors corresponding to the inner passages that communicate with the discharge opening, allowing backwashing to occur in these sectors due to the pressure gradient across the filter mesh, i.e., the pressure gradient between the outer and inner sides. The fluid used for backwashing is then discharged through the discharge opening.

[0006] In some applications, generally those with high contamination rates, the pressure gradient may not be sufficient to ensure a sufficiently high backflush flow, and therefore complete backwashing of the filter mesh. An increase in the overall backflush flow is undesirable as it represents a loss of purified flow. This loss can be compensated for by increasing the inflow flow, but this means that upstream devices such as pumps, heat exchangers, and other auxiliary equipment will become oversized.

[0007] The inventors propose a first solution to this problem in Patent Document 2. In fact, this application describes another backwashing system comprising a sleeve, around which filtration elements are stacked; and a rotary distributor extending along the entire height of the sleeve and configured to selectively isolate the holes of the sleeve, such that the holes are opposite the inner passages of the filtration elements, enabling backwashing in the corresponding sectors. To optimize the pressure gradient to minimize the number of sectors backwashed simultaneously and thus increase backwashing efficiency, the filtration elements, along with the holes of the sleeve, are circumferentially offset along the axial direction of the stack to increase the number of passage columns that can be individually isolated by the distributor.

[0008] This document describes the unique offset of half-sectors. Of course, it is desirable to increase the number of different offsets in order to increase the number of passage columns that can be isolated by the distributor. However, in practice, it is virtually impossible to provide additional offsets with the configuration disclosed in this document. In fact, firstly, due to the size of each inner passage, the circumferential gap between two holes in the sleeve is not large enough to accommodate two or more offset holes without overlapping at least some passage columns. Secondly, arranging the holes in a staggered manner reduces the mechanical strength of the sleeve, and such a reduction in mechanical strength becomes all the more significant when considering the increase in the number of offset holes. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2012 / 028824 Brochure [Patent Document 2] European Patent Application No. 21305621.1 Specification [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, there is a need to further improve the efficiency of backwashing. Thus, a new type of filtration unit, or part of a new type of filtration unit, is required. [Means for solving the problem]

[0011] This disclosure relates to a sleeve for a filtration unit with backwashing, wherein the sleeve is configured to be coaxially mounted inside a stack of annular filtration elements, and is provided with holes, each having an inner orifice and an outer orifice, the outer orifice of each hole facing the inner passage of the filtration element and communicating with the inner passage. The holes are arranged as several circumferential transverse rows, each circumferential transverse row extending across the entire circumference of the sleeve. The present invention relates to a sleeve in which at least some of the holes have elongated outer orifices in the circumferential direction.

[0012] With a configuration in which the outer orifice of the pore is elongated in the circumferential direction, that is, in the same direction as the inner passage of the filtration element, a smooth flow is ensured at the interface with the filtration element without any substantial pressure drop.

[0013] At least some of the holes have an axially elongated inner orifice. In such a sleeve, the inner orifice of the hole is elongated in the axial direction. This particular orientation allows the inner orifice to be better directed toward the inflow of the fluid to be filtered, and the fluid actually flows axially along the main direction of the sleeve. As a result, the pressure drop at the inlet of the inner orifice is reduced. Nevertheless, since the outer orifice of the hole is elongated in the circumferential direction, smooth flow is ensured at the interface with the filtering element without substantial pressure drop.

[0014] In fact, since the inner orifice is provided axially and the outer orifice is provided circumferentially, the directional transition of the filtered fluid flow from axial flow within the sleeve to radial flow within the filtration element is facilitated.

[0015] Furthermore, this special orientation makes it possible to substantially reduce the circumferential width of the inner orifice without substantially reducing the total water passage cross-section of the inner orifice, and thus without substantially increasing the pressure drop at the inlet of the hole. Therefore, it is possible to provide a greater number of tandem rows of inner orifices that can be selectively isolated without overlap by a rotary distributor, as desired. As a result, the number of sectors that are backwashed simultaneously can be reduced.

[0016] In particular, due to this special configuration of the holes and the resulting mechanism of the inner and outer orifices within the sleeve, it is possible to increase the number of longitudinal rows of holes as desired without substantially affecting the mechanical strength of the sleeve.

[0017] In some embodiments, most, preferably all, of the holes have an axially elongated inner orifice and a circumferentially elongated outer orifice.

[0018] In some embodiments, the holes are spaced at regular intervals in each circumferential row.

[0019] In some embodiments, each row comprises the same number of holes.

[0020] In some embodiments, each row comprises from 8 to 24 holes, preferably from 12 to 20 holes.

[0021] In some embodiments, the spacing between each circumferential row is constant.

[0022] In some embodiments, the sleeve comprises at least 10, preferably at least 20, circumferential rows.

[0023] In some embodiments, the holes are circumferentially offset along the axial direction of the sleeve. As described above, such an offset makes it possible to increase the number of columns that can be individually isolated by the distributor and thus to reduce the number of sectors being backwashed simultaneously.

[0024] In some embodiments, the outer orifices of the holes are configured as j sets, whereby in each set of outer orifices, any row of outer orifices is axially aligned with the outer orifices of other rows, and j is an integer greater than or equal to 2, preferably equal to 3 or 4. As described above, due to the special configuration of the holes, it is possible to provide three or more sets of holes with outer orifices offset relative to each other. Therefore, improved backwashing can be achieved.

[0025] In some embodiments, the circumferential offset θ(1) between outer orifices belonging to different sets of outer orifices is a multiple of the pitch θ0 = 360° / n.j, where n is the number of holes in each row and j is an integer greater than or equal to 2, preferably greater than or equal to 3, for example, equal to 3 or 4. Preferably, n is also equal to the number of sectors in each filter element. Preferably, j is the number of sets of the outer orifices described above. In other words, the pitch θ0 is equal to the sector width multiplied by 1 / j. Therefore, it should be noted that when a given hole is shifted j times, this hole is converted into an adjacent hole in its row. Therefore, due to the shift being due to a pitch that is not an integer multiple of the sector, the shift of the outer orifices is accurately and uniformly controlled.

[0026] In some embodiments, the rows of each set of outer orifices have an alternating arrangement along the axial direction of the sleeve. Therefore, the alternating arrangement between rows with different offsets is regular.

[0027] In some embodiments, the circumferential offset θ(1) between the outer orifices of any row and the outer orifices of the preceding row in the axial direction of the sleeve is equal to θ0 = 360° / n.j, where n is the number of holes in each row and j is an integer greater than or equal to 2, preferably greater than or equal to 3, for example, equal to 3 or 4. Therefore, each row is regularly offset by a pitch θ0 relative to the preceding row.

[0028] In some embodiments, the inner orifices of at least some holes are circumferentially offset relative to the centers of the outer orifices of those holes. This is preferably true for most, or possibly all, of the holes. This allows for decorrelation of the inner orifice positions from the outer orifice positions, thereby increasing the design flexibility of the sleeve. In particular, it is possible to optimize the position of the inner orifice for any given hole, regardless of the position of the outer orifice.

[0029] In some embodiments, the position of the inner orifice of a hole differs from the position of the outer orifice of the hole among multiple holes. This makes it possible to artificially increase the number of columns of inner orifices relative to the number of columns of outer orifices. As a result, it is possible to increase the number of columns that can be individually isolated by the distributor and, therefore, reduce the number of sectors that are backwashed simultaneously.

[0030] In some embodiments, the sleeve is provided with k types of holes, thereby the circumferential displacement of the inner orifice relative to the center of the outer orifice.

[0031]

number

[0032] k is equal for all holes of a given type, and k is an integer greater than or equal to 2.

[0033] In some embodiments, all holes in a given row are of the same type.

[0034] In some embodiments, k is equal to 2, where k is the circumferential displacement of the inner orifice of any hole relative to the center of the outer orifice of that hole.

[0035]

number

[0036] teeth,

[0037]

number

[0038] or

[0039]

number

[0040] Equivalent to,

[0041]

number

[0042] This is an angle value that is strictly greater than 0°, preferably greater than 1°. Preferably, this value

[0043]

number

[0044] This value is less than 3° or 2°. In particular, this value is preferably less than or equal to θ0 / 4.

[0045] In some embodiments, the rows of holes are grouped into groups of k consecutive rows, with the exception of the first bottom row and / or the last top row, and all holes in a given group are of the same type. Thus, the type of holes can be changed after a series of rows in each set consisting of holes of the same type. Thus, the sequence of rows is regular, and the rows of inner orifices are also regular. The first group at the bottom and / or the last group at the top may be incomplete, especially if the total number of rows is not a multiple of k.

[0046] In some embodiments, the inner orifices of the bore are configured as a row of N, so that in each row of inner orifices, any inner orifice in any row is aligned axially with the inner orifice in any other row, where N is an integer of 4 or more, preferably 6 or 8 or more. Thus, the number of columns that can be individually isolated by the distributor is increased, and the number of sectors that are backwashed at the same time is decreased, thereby improving backwashing efficiency.

[0047] In some embodiments, some holes have an internal funnel-shaped portion that opens in an internal orifice and narrows outward. This is preferably true for most, or possibly all, of the holes. This funnel-shaped portion helps to guide the flow from axial to radial, and thus reduces the pressure drop at the inlet of the hole.

[0048] In some embodiments, only the axial height of the inner funnel-shaped portion is reduced, while the circumferential width of the inner funnel-shaped portion remains substantially constant.

[0049] In some embodiments, some holes have an outer funnel-shaped portion that opens at the outer orifice and narrows inward. This is preferably true for most, or possibly all, of the holes. This funnel-shaped portion helps distribute the flow across the entire width of the inner passage of the filter element, and from there, the flow across the entire width of the sector of the filter element.

[0050] In some embodiments, only the circumferential width of the outer funnel-shaped portion is reduced, while the axial height of the outer funnel-shaped portion remains substantially constant.

[0051] In some embodiments, the inner funnel-shaped portion and the outer funnel-shaped portion intersect. This facilitates the integration of both the inner and outer funnel-shaped portions within the thickness of the sleeve. This also makes it possible to limit the reduction of the water passage cross-section at the joint between the inner and outer funnel-shaped portions.

[0052] In some embodiments, the minimum water-permeable cross-section of some holes is 50% or more, preferably 70% or more, and preferably 90% or more, of the water-permeable cross-section of the inner orifice of the hole. This preferably applies to most of the holes, or in some cases, all of them. This limits the pressure drop within the holes.

[0053] In some embodiments, the sleeve diameter includes 100 to 400 mm.

[0054] In some embodiments, the height of the sleeve is less than 3 meters, preferably less than 2 meters.

[0055] In some embodiments, the sleeve is manufactured by additive manufacturing.

[0056] In other embodiments, the sleeve is manufactured by lost-wax casting.

[0057] The disclosure also relates to a filtration assembly for a filtration unit with backwashing, comprising a sleeve according to any one of the embodiments described above and a plurality of filtration elements stacked on top of each other, wherein each filtration element has a filter medium and a plurality of internal passages for guiding a fluid to be filtered into the filter medium, the internal passages opening onto partitioned sectors.

[0058] In some embodiments, the filtration elements are key-fixed to a sleeve, thereby offsetting the inner passage of one of the filtration elements relative to the inner passage of an adjacent filtration element.

[0059] In some embodiments, each filtration element comprises an inner edge, an outer edge, and a filter medium extending between the inner and outer edges, the filtration element having an inner and outer surface on each side of the filter medium, with main ribs extending between the inner and outer edges circumferentially distributed on the inner surface to form sectors, the filtration elements being adapted to be assembled to a first identical filtration element, thereby defining a space circumferentially partitioned by the respective main ribs in contact with each other on the inner surface, and the inner edge having an inner passage communicating with each of the sectors on the inner surface.

[0060] The filter media may extend over part or all of the distance between the inner and outer edges. One side of the filter media defines the inner surface of the filtration element, while the opposite side defines the outer surface of the filtration element. The filtration element may be generally flat.

[0061] Ribs defined on the inner surface allow for the isolation of sectors for backwashing. Partitioning of the outer surface is not necessary. At least one outer passage may be provided on the outer surface of the outer edge for the purified fluid outlet and backflush inlet. Conversely, on the inner surface, there may be no passages on the outer edge, thereby requiring fluid entering a sector through a passage to cross the filtration element to exit that sector.

[0062] In some embodiments, the outer surface of a filtration element has a key for pairing the filtration element with a second identical filtration element at a predetermined position, the key being positioned such that the inner passage of the second identical filtration element is offset from the passage of the filtration element.

[0063] The key is an element that provides a key-fixed connection between the outer surface of a reference filter element and the outer surface of a second identical filter element. Thus, the key pre-determines, for example, the relative position of the second identical filter element with respect to the reference filter element, angularly. The key may include physical elements that enable physical cooperation.

[0064] The key may be located between the inner and outer edges to reduce the volume of the filtration element.

[0065] In particular, this key fixing system can be configured according to the teachings of Patent Document 2, the contents of which are incorporated herein by reference.

[0066] Note that filtration elements do not need to be keyed to each other, as long as they are keyed to a common element, in this case the sleeve. Hybrid solutions are also conceivable, where some filtration elements are keyed to each other and some are keyed to the sleeve.

[0067] In some embodiments, the filter media includes a mesh. In some embodiments, the mesh is sloped from one end of the inner edge to the opposite end of the outer edge, which helps to increase the filtration surface and reduce pressure drop.

[0068] In some embodiments, the filtration assembly further comprises a rotary backwash distributor configured to selectively isolate the inner orifice of the sleeve, thereby enabling backwashing within the corresponding sector.

[0069] In some embodiments, the rotary backwashing distributor has an opening which periodically and selectively communicates with at least one of the internal orifices of the sleeve.

[0070] This disclosure also relates to a filtration unit comprising a filtration assembly according to any one of the embodiments described above.

[0071] The features and advantages described above will become clear when you read the following detailed description of exemplary embodiments of the presented sleeve, filtration assembly, and filtration unit. This detailed description is accompanied by the drawings.

[0072] The present invention and its advantages will be better understood by reading the following detailed description of embodiments of the invention given as non-limiting examples. This description is accompanied by reference to the attached drawings. [Brief explanation of the drawing]

[0073] [Figure 1] This figure shows a cross-section of a filtration unit according to an example. [Figure 2] Figure 1 is a perspective view of the inner surface of the filtration element used in the filtration unit. [Figure 3] Figure 2 is a perspective view of the outer surface of the filtration element. [Figure 4] This is a perspective view of a filtration unit comprising two filtration elements stacked on top of each other. [Figure 5] This figure shows the backwashing system in a cross-section of the first radial plane. [Figure 6] This figure shows the backwashing system in a cross-section of the second radial plane. [Figure 7] Figure 1 is a perspective view of the sleeve of the filtration unit. [Figure 8] This is an axial cross-sectional view of the sleeve. [Figure 9] This is a radial cross-sectional view of the sleeve in the first radial plane. [Figure 10] This is a radial cross-sectional view of the sleeve in the second radial plane. [Figure 11] This is a close-up view of a part of the sleeve. [Figure 12] This is an enlarged view corresponding to frame XII in Figure 8. [Modes for carrying out the invention]

[0074] Figure 1 shows a cross-section of filter 1. Filter 1 comprises a cartridge 2 and a filtration assembly 90.

[0075] In this embodiment, the filter 1 comprises two inlet sections 3 and one outlet section 4, each section located within the cartridge 2. However, the filter 1 may comprise any number of inlet sections 3 and any number of outlet sections 4. The filter 1 also comprises a backwash motor 5 and a backwash outlet 6, as presented below.

[0076] The filtration assembly 90 comprises multiple filtration elements 10 stacked around the sleeve 70 and between the upper cover 50 and the lower cover 60 along the axial X of the filter 1. The filtration assembly 90 also comprises a backwash distributor 80.

[0077] Figures 2 and 3 show an exemplary filtration element 10. This filtration element 10 has an inner surface 20, an outer surface 21, a filtration mesh 22, and two concentric edges, an inner edge 24 and an outer edge 26, respectively, with the filtration mesh 22 extending between the inner edge 24 and the outer edge 26. The concentric edges 24 and 26 are circular about a central axis X, which will be used below to define the axial direction. The inner edge 24 extends mainly in a plane perpendicular to the axial direction X, i.e., in the radial plane. The outer edge 26 extends mainly in a plane perpendicular to the axial direction X, i.e., in the radial plane.

[0078] In this embodiment, the diameter of the outer edge 26 is approximately 300 mm. Of course, other diameters are possible, including, for example, diameters in the range of approximately 100 mm to approximately 600 mm.

[0079] The filtration element 10 includes main ribs 28 provided on at least the inner surface 20. In this embodiment, as shown in Figure 4, the main ribs 28 are also provided on the outer surface 21. Therefore, when three similar filtration elements 10 are stacked, both sides of the central filtration element of the stack face the respective inner surfaces of the other two filtration elements 10, and the main ribs provided on each of these surfaces interact to form compartments.

[0080] The main ribs 28 extend radially between the inner edge 24 and the outer edge 26. The main ribs 28 are regularly distributed circumferentially to form n sectors on the inner surface 20, as shown in Figure 3. In this embodiment, the radial ribs 28 also form n sectors on the outer surface 21, as shown in Figure 4. The main ribs 28 on the inner surface 20 and the outer surface 21 face each other on both sides of the filter mesh 22. In other words, the radial ribs 28 correspond axially on the inner surface 20 and the outer surface 21.

[0081] Each inner edge portion 24 has an inner passage 30 that communicates with a corresponding sector. The inner passage 30 is provided as a notch or cutout in the inner edge portion 24. The inner passage 30 is provided between continuous main ribs 28. The inner passage 30 is provided on the inner surface 20. Therefore, the inner passage 30 has an opening angle ε(0) and a height a2.

[0082] As shown in Figure 3, the outer edge 26 has an outer passage 32 that communicates with the corresponding sector. The outer passage 32 is provided as a notch or cutout in the outer edge 26. The outer passage 32 is provided between continuous main ribs 28. The outer passage 32 is provided on the outer surface 21.

[0083] Holes 34 for passing an assembly rod or assembly key are defined near the outer edge 26 of each filter element, and these holes are formed by molding the same material that defines the circular edges 24, 26 and the main rib 28. Male and female bushings 36 are positioned around these holes 34, for example, within the main rib 28, to position two filter elements 10 relative to each other.

[0084] In the non-limiting example shown, each filter element 10 is divided into 16 sectors (n=16). Filter elements can have fewer or more sectors, particularly depending on their diameter size. For example, a filter element with an outer diameter of 100-150 mm may have 8-12 sectors, while a filter element with an outer diameter of 500-600 mm may have 20-24 sectors.

[0085] The filtration element 10 can be manufactured by molding it around a filtration mesh 22. In other words, the filtration element can be manufactured by injection molding or the like, and the filtration mesh 22 forms an insert in the mold. The molded part can be made of metal (e.g., aluminum alloy) or plastic material, especially polymer. The main ribs 28 and the inner and outer edges 24 and 26 can be coated with elastomer to prevent leakage between the filtration elements 10.

[0086] Each sector comprises at least one reinforcing rib 40 connecting the main rib 28 to the outer edge 26. In this embodiment, each reinforcing rib 40 has a portion that is inclined with respect to the main rib 28 and the outer edge 26 when viewed in the radial plane over which the outer edge 26 extends. However, other configurations are also possible.

[0087] As shown in Figure 3, reinforcing ribs 40 are also provided on the outer surface 21. The reinforcing ribs 40 on the inner surface 20 and the outer surface 21 face each other on both sides of the filter mesh 22 to reduce pressure drop.

[0088] As shown in Figure 4, the filtration elements 10 are configured to be assembled with respect to each other, so that their respective inner surfaces 20 face each other, defining a space between them. This space is circumferentially defined by main ribs 28 on the inner surfaces that are in contact with each other. On the other hand, the main ribs 28 on the outer surfaces 21 do not need to be in contact with each other. The two filtration elements 10 assembled in this manner form a filtration section 11.

[0089] Next, when the filtration elements 10 are stacked to form the filtration assembly 90, a circumferential misalignment α is introduced between each continuous filtration section 11. As a result of introducing such a circumferential misalignment α, the main ribs 28 on the outer surfaces 21 of two continuous filtration elements 10 may not extend in correspondence with each other, and similarly, the outer passages 32 of these continuous filtration elements 10 may not extend in correspondence with each other. Such misalignment does not affect the function of the filter.

[0090] To ensure appropriate circumferential displacement is introduced between each filtration section 11, key locking mechanisms may be provided on some or all of the filtration elements 10. An exemplary key locking system is described, for example, in Patent Document 2.

[0091] The upper cover 50 leans against the casing 2 in the stacking direction of the filtration elements, in this case in the direction of the central axis X. Specifically, the upper cover 50 leans against the shoulder of the casing 2, which forms a stopper against axial and possibly radial movement of the upper cover 50.

[0092] The upper cover 50 may be a generally annular portion. The upper cover 50 may have a central opening for inserting the sleeve 70 shown in Figure 1. The first cover 50 may extend radially from the sleeve 70 and outward to at least the outer edge 26 of the filter element 10. The first cover 50 and the sleeve 70 may be in airtight contact with each other, for example, due to a small gap between the first cover 50 and the sleeve 70. A gasket may be provided if necessary.

[0093] Similarly, but independently, the lower cover 60 may be a generally annular portion. The lower cover 60 may have a central opening for inserting the sleeve 70 shown in Figure 1. The lower cover 60 may extend radially from the sleeve 70 and outward to at least the outer edge 26 of the filtration element 10. The lower cover 60 and the sleeve 70 may be in sealed contact with each other, for example, due to a small gap between the lower cover 60 and the sleeve 70. However, since both the sleeve 70 and the lower cover 60 are within the dirty zone 2a, sealing is not required.

[0094] Therefore, the sleeve 70 extends at least from the upper cover 50 to the lower cover 60.

[0095] As better shown in Figure 7, the sleeve 70 has holes 72 that are configured to face the inner passage 30 of the filtration element 10 and to be in fluid communication with the inner passage 30. Each hole 72 has an inner orifice 73 provided on the inner surface of the sleeve 70 and an outer orifice 74 provided on the outer surface of the sleeve 70. To properly align the outer orifice 74 of the hole 72 with the inner passage 30 of the filtration element 10, the sleeve 70 may have a key-fastened connection to at least one of the first cover 50 and the second cover 60.

[0096] In addition, at least one of the first cover 50 and the second cover 60 may be provided with a key for attaching one of the multiple filtration elements to a predetermined position relative to at least one of the first cover 50 and the second cover 60. Thus, the filter 1 provides a key-fixed connection between the sleeve 70 and the filtration element 10, here via at least one of the first cover 50 and the second cover 60.

[0097] In addition to being keyed to each other, or instead, the filter sections 11 can be keyed to the sleeve 70, so that one passage of the filter section 11 is offset from the inner passage 30 of the adjacent filter section 11. Any type of keyed connection, including the keyed connections described in detail above, is included.

[0098] As schematically shown by the arrows in Figure 2, the fluid to be filtered enters the filter through the inlet 3 of the casing 2, passes through the central conduit 71 formed by the sleeve 70, and flows into the holes 72 of the sleeve 70, which are not separated by the backwash distributor 80. After being filtered through the filtration section 11, the filtered fluid is supplied to the outside of the filtration section 11 and extracted at the outlet 4 of the casing 2.

[0099] Therefore, in casing 2, the lower cover 60 is also called the dirty zone. Zone 2a of the casing, adapted to receive the fluid to be filtered, is separated from zone 2b of the casing, also called the clean zone, which is adapted to receive the filtered fluid. Thus, the pressure drop of the fluid between the dirty zone 2a and the clean zone 2b causes the lower cover 60 to be biased toward the upper cover 50, and thus maintains the filtration elements 10 in sealed contact with each other.

[0100] In addition, the filtration assembly 90 further comprises a cover backing 61. The cover backing 61 is coupled to the lower cover 60 by a return system configured to return the cover backing 61 toward the upper cover 50. The cover backing 61 leans against the casing 2 in the stacking direction, for example, by a shoulder of the casing 2, which forms a restraint against axial and possibly radial movement of the cover backing 61. This shoulder may have a continuous annular shape or may be provided as a plurality of discrete supports.

[0101] The cover backing 61 may be a generally annular portion. The cover backing 61 may have a central opening for inserting the sleeve 70, as shown in Figure 1. The cover backing 61 may extend radially from the sleeve 70 and outward to at least the outer edge 26 of the filter element 10.

[0102] The cover backing 61 is perforated; that is, the cover backing 61 has through-holes that allow fluid to pass through, which helps to maximize the pressure difference across the second cover 60. These openings may be angularly distributed along the perimeter of the cover backing 61.

[0103] Figures 5 and 6 illustrate the principle of backwashing the filtration element 10. As described above, the sleeve 70 is positioned concentrically with the filtration element 10 and radially inward of the filtration element 10. The sleeve 70 has a sealed contact with the filtration element 10. As already described, the inner passage 30 of the filtration element 10 is circumferentially offset along the axial direction, and as a result, the outer orifice 74 of the hole 72 is circumferentially offset in correspondence with the inner passage 30. Furthermore, as will be described in more detail in this disclosure, the inner orifice 73 of each hole 72 is circumferentially offset relative to the outer orifice 74.

[0104] The distributor 80 is rotationally driven by a backwash motor 5 and is configured to selectively isolate the inner orifices 73 of the holes 72 in the sleeve 70 to isolate the corresponding sectors of the filtration element 10. For example, in this embodiment, the distributor 80 has a shutter 82 having two shutter portions 82a flanking a discharge opening 84, which is mounted, for example, to rotate around a central axis X, thereby allowing the discharge opening 84 to communicate with each inner orifice 73 periodically and selectively.

[0105] As best shown in Figure 1, the discharge opening 84 may extend axially across multiple filtration elements 10, whether continuous or not, thereby enabling all internal orifices 73 corresponding to the discharge opening 84 in the radial direction, for example, all internal orifices 73 aligned with the discharge opening 84, to communicate with the discharge opening 84 simultaneously. For example, the opening 84 may be linear. The opening 84 may extend parallel to the central axis X. The discharge opening 84 has an opening angle δ(1), while each shutter portion 82a has a shutter angle δ(2). Preferably, the opening angle δ(1) of the discharge opening 84 of the distributor 80 is the same as the opening angle of the internal orifices 73.

[0106]

number

[0107] It is practically equivalent to this.

[0108] Figures 5 and 6 show that the shutter angle δ(2) of the shutter portion 82a is large enough to ensure that the inner orifice 73 does not communicate with the discharge opening 84 and the central conduit 71 simultaneously.

[0109] The illustrated embodiment has a unique discharge opening 84, but multiple discharge openings 84 may be provided. The discharge openings 84 may be distributed circumferentially, thereby increasing the frequency of backwashing a given sector without increasing the speed of the backwash distributor 80. Multiple discharge openings 84 are such that when one sector is completely backwashed through one of the discharge openings 84, no other discharge openings 84 face any passage, otherwise the intrinsic backflash flow rate is reduced.

[0110] The displacement of the inner orifices 73 in adjacent filtration sections reduces the number of inner orifices 73 communicating with the discharge opening 84 simultaneously. Consequently, the backflush flow is divided among fewer sectors, increasing the specific backflush flow rate.

[0111] In fact, Figure 6, which is similar to Figure 5 but depicts a different filtration element 10, shows that the discharge opening 84 does not contact any of the inner orifices 73 in the plane of Figure 5, but communicates with the inner orifices 73 in the plane of Figure 6. As the backwash distributor 80 rotates, the shutter closes the inner orifice in Figure 6, while the discharge opening 84 contacts another column of inner orifices 73. This configuration results in a filter with continuous backwashing, i.e., at least one sector is backwashed at every position of the backwash distributor 80. Continuous backwashing can be achieved in other ways, for example, by using multiple discharge openings 84. Conversely, by appropriately sizing the discharge openings 84, the filter can perform discontinuous backwashing, i.e., there are positions of the backwash distributor 80 where no sectors are backwashed.

[0112] In either case, the backwash fluid is discharged at the top of the discharge opening 84 of the discharge chamber 6a, and the discharge chamber 6a leads to the backwash outlet 6. If desired, the backwash fluid itself may be purified through another similar filtration unit.

[0113] Figure 7 shows the sleeve 70 in more detail. As already described, the sleeve 70 is cylindrical and defines the central conduit 71. The sleeve 70 comprises a main portion 75, an upper rim 76, and a lower extension 77.

[0114] The main portion 75 extends over most of the sleeve 70 and includes the aforementioned hole 72.

[0115] The upper rim 76 is key-secured to the upper cover 50 by a flat portion 76a. As shown in Figure 2, the upper rim 76 is also configured to mount a ball bearing 85a which rotatably supports the upper end 85 of the backwash distributor 80. Thus, the upper end 85 of the backwash distributor tightly seals the upper end of the central conduit 71.

[0116] The lower extension 77 extends along the lower cover 60 and cover backing 61, protruding over the cover backing 61 and entering the dirty zone 2a. The lower extension 77 includes a lower rim 77a that rotatably supports the lower end 86 of the backwash distributor 80. The lower end 86 of the backwash distributor 80 is sealed so that the discharge opening 84 does not communicate with the dirty zone 2a. In addition to the lower end of the open sleeve 70, the lower extension 77 includes an opening 77b that allows the fluid to be filtered and flow into the central conduit 71.

[0117] Next, the mechanism of hole 72 will be explained with reference to Figures 7 to 12.

[0118] The sleeve 70 comprises a plurality of transverse rows 78 spaced at regular intervals of holes 72, each transverse row 78 extending circumferentially (i.e., in the radial plane) and comprising the same number of holes 72 spaced at regular intervals. In this embodiment, the sleeve 70 comprises 53 transverse rows, each transverse row comprising 16 holes 72.

[0119] As already explained, each hole 72 comprises an inner orifice 73 and an outer orifice 74. The outer orifice 74 is elongated in the circumferential direction. Every outer orifice 74 has the same opening angle as the inner passage 30, substantially equal (difference of 10% or less) to the opening angle ε(0).

[0120]

number

[0121] Each outer orifice 74 also has the same height f(2) as the height a2 of the inner passage 30 (a difference of 10% or less). Conversely, the inner orifice 73 is elongated in the axial direction. Each inner orifice 73 has the same size. To maintain the mechanical strength of the sleeve 70, it is preferable to make the height f(1) of the inner orifice 73 as high as possible while keeping it smaller than the thickness a1 of the element 10.

[0122] As can be seen more clearly in Figures 9 and 10, the position of the inner orifice 73 is not always the same as that of the outer orifice 74. In particular, in this embodiment, two types of holes are provided. In the first type 72-1 hole, when viewed from the outside, the inner orifice 73 of the hole is shifted to the left relative to the outer orifice 74 (Figure 9), while in the second type 72-2 hole, when viewed from the outside, the inner orifice 73 of the hole is shifted to the right relative to the outer orifice 74 (Figure 10). The type of hole 72 is always the same in a given row 78.

[0123] In more detail, in this embodiment, the circumferential displacement between the center of the outer orifice 74 and the center of the inner orifice 73 is

[0124]

number

[0125] This is equal to 1.875°.

[0126] Furthermore, as can be seen in Figures 9, 10, and 12, each hole 72, regardless of its type, comprises an inner funnel-shaped portion 73a that opens at the inner orifice 73 and narrows outward, and an outer funnel-shaped portion 74a that opens at the outer orifice 74 and narrows inward. In this embodiment, the depth of both the inner funnel-shaped portion 73a and the outer funnel-shaped portion 74a is greater than half the thickness of the sleeve wall 70, and therefore the inner funnel-shaped portion 73a and the outer funnel-shaped portion 74a intersect each other.

[0127] The outer orifices 74 of the holes 72 are configured as j sets of horizontal rows 78 on the outer surface of the sleeve 70. In this embodiment, j=3. In each set of horizontal rows 78-1, 78-2, and 78-3, the outer orifice 72 of any horizontal row 78 is aligned axially with the outer orifice of the other horizontal row 78 to form vertical rows 79-1, 79-2, and 79-3.

[0128] The three sets of horizontal rows 78-1, 78-2, and 78-3 are arranged in a regular alternating pattern along the entire length of the main portion 75 of the sleeve 70. Furthermore, the circumferential offset θ(1) between the outer orifices 74 of two consecutive horizontal rows 78 is the same along the entire length of the main portion 75 of the sleeve 70. In this embodiment, this circumferential offset θ(1) is equal to 7.5 degrees.

[0129] Furthermore, for the sake of regularity, hole 72 is always the same type of hole within a group of three consecutive rows, i.e., within a group containing only one row in each set 78-1, 78-2, and 78-3. In that case, for the next group of three rows 78-1, 78-2, and 78-3, the types of holes 72-1 and 72-2 will change.

[0130] As a result, when observing the inner orifice 73 of hole 72, the combination of three sets of transverse rows 78-1, 78-2, 78-3 and two types of holes 72-1, 72-2 forms six different transverse rows of inner orifices 88-11, 88-21, 88-31, 88-12, 88-22, 88-32 that are circumferentially offset from one another. These six transverse rows are regularly alternating along the length of the main portion 75 of sleeve 70. Consequently, when scanning the sleeve from one end to the other, there is a pitch N of six transverse rows before encountering the same transverse row again.

[0131] Therefore, this mechanism provides corresponding rows of 89-11, 89-21, 89-31, 89-12, 89-22, 89-32 with p=6, and each row is spaced circumferentially by a regular offset θ(2)=360° / nN, which is therefore equal to 3.75° here. Thus, in this embodiment, the opening angle of each inner orifice 73

[0132]

number

[0133] This is equal to a regular displacement θ(2), while the opening angle δ(1) of the discharge opening 84 of the distributor 80 is also equal to this value. As a result, in this embodiment, the sleeve 70 has 96 columns that can be individually isolated by the backwash distributor 80.

[0134] Nevertheless, the opening angle of the inner orifice 73

[0135]

number

[0136] The optimal value corresponds to the regular displacement θ(2) = 360° / nN, but the opening angle of the inner orifice 73

[0137]

number

[0138] In alternative embodiments, this can take on other values.

[0139] In particular, in the first alternative embodiment, the opening angle of the inner orifice 73

[0140]

number

[0141] This regular shift θ(2) = 360° / nN can be greater than this. Nevertheless, in such a case, there will inevitably be at least some inner orifices 73 in the row that overlap with the inner orifices 73 of another row. In such an alternative embodiment, the opening angle δ(1) of the discharge opening 84 of the distributor 80 is such that the opening angle of the inner orifices 73 reduces the period during which two adjacent sectors experience backflushing simultaneously.

[0142]

number

[0143] It is preferable that it be smaller than the following. In more detail, the opening angle δ(1) of the discharge opening 84 is such that each sector is ensured to have at least a moment in which it is effectively isolated from the adjacent sector.

[0144]

number

[0145] It is preferable to make it smaller than this. Therefore, such alternative configurations may be useful for smoothing the transition between backflashes of adjacent sectors.

[0146] In the second alternative embodiment, the opening angle of at least some of the inner orifices 73

[0147]

number

[0148] The regular deviation θ(2) = 360° / nN can be made smaller than this. In such cases, the pressure drop is artificially increased. Nevertheless, such an increase in the pressure drop can be useful in some cases, for example, the opening angle of the inner orifice 73.

[0149]

number

[0150] The value of can increase along the length of the sleeve 70 from the fluid inlet 3, which typically compensates for the pressure drop that increases with distance from the inlet 3, and thus equalizes the load along the sleeve 70.

[0151] While the present invention has been described by reference to certain exemplary embodiments, modifications to these embodiments may be made without departing from the general scope of the invention as defined by the claims. In particular, individual characteristics of different illustrated / described embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an exemplary rather than restrictive sense. [Explanation of Symbols]

[0152] 1 filter 2 Carter, Casing 2a Dirty Zone 2b Clean Zone 3 Inflow part, inlet 4 Outflow part, outlet 5. Backwash motor 6 Backwash outlet, backwash outlet 6a Discharge chamber 10 Filtration elements 11 Filtration section 20 Inner self 21 Exterior 22 filtration mesh 24 Inner edge 26 Outer edge 28 Main Ribs 30 Inner passage 32 Outside passage 34 holes 36 Male bushings and female bushings 40 Reinforcement Ribs 50 Top cover, first cover 60 Lower cover, second cover 61 Cover Backing 70 sleeves 71 Central conduit 72 holes 72-1 First type of hole 72-2 Type 2 with holes 73 Internal orifice 73a Inner funnel 74. External orifice 74a Outer funnel 75 Main parts 76 Upper rim 76a flat part 77 Lower extension 77a Lower rim 77b opening 78, 78-1, 78-2, 78-3: Horizontal row of outer orifices 79-1, 79-2, 79-3 Outer orifice Column 80 Backwash distributor 82 shutters 82a Shutter section 84 Discharge opening 85 Upper end 85a ball bearing 86 Lower end 88, 88-11, 88-21, 88-31, 88-12, 88-22, 88-32 Horizontal row of inner orifices 89-11, 89-21, 89-31, 89-12, 89-22, 89-32: Vertical rows of inner orifices 90 Filtration Assembly δ(1) Aperture angle δ(2) Shutter angle ε(0) Opening angle φ(1) Opening angle φ(2) Circumferential displacement φ(3) Opening angle θ Circumferential displacement θ0 pitch θ(1) Circumferential displacement θ(2) Regular shift f(1) height f(2) height

Claims

1. A sleeve for a filtration unit with backwashing, wherein the sleeve (70) is configured to be coaxially mounted inside a stack of annular filtration elements (10), The filtration element (10) is provided with holes (72), each hole having an inner orifice (73) and an outer orifice (74), and the outer orifice (74) of each hole (72) is configured to face the inner passage (30) of the filtration element (10) and to communicate with the inner passage (30). The holes (72) are configured as several circumferential rows (78), each circumferential row (78) extending over the entire circumference of the sleeve (70). A sleeve in which at least some of the holes (72) have elongated outer orifices (74) in the circumferential direction, and at least some of the holes (72) have elongated inner orifices (73) in the axial direction.

2. The sleeve according to claim 1, wherein the plurality of holes (72) are offset in the circumferential direction along the axial direction of the sleeve (70).

3. The sleeve according to claim 2, wherein the outer orifices (74) of the hole (72) are configured as j sets (78-1, 78-2, 78-3), so that in each set of outer orifices (74), the outer orifices (74) of any row (78) are aligned in the axial direction with the outer orifices (74) of other rows (78), and j is an integer of 2 or more, preferably 3 or more.

4. The circumferential displacement θ between the outer orifices (74) belonging to different sets of outer orifices (78-1, 78-2, 78-3) is equal to the pitch θ ０ The sleeve according to claim 3, wherein the number of holes (72) in each row (78) is 360° / n, which is a multiple of j, and n is the number of holes (72) in each row (78).

5. The sleeve according to any one of claims 1 to 4, wherein the inner orifices (73) of at least some of the holes (72) are circumferentially offset with respect to the center of the outer orifice (74) of the hole (72).

6. The sleeve according to any one of claims 1 to 5, wherein the position of the inner orifice (73) of the hole (72) relative to the position of the outer orifice (74) of the hole (72) differs among the multiple holes (72).

7. The sleeve (70) is provided with k types of holes (72-1, 72-2), and the circumferential displacement of the inner orifice (73) relative to the center of the outer orifice (74) [Math 1] The sleeve according to claim 6, wherein k is equal for all holes of a predetermined type (72-1, 72-2), and k is an integer of 2 or more, preferably equal to 2.

8. k is equal to 2, and the circumferential displacement of the inner orifice (73) of the hole (72) with respect to the center of the outer orifice (74) of any hole (72). [Math 2] teeth, [Math 3] or [Math 4] Equivalent to, [Math 5] The sleeve according to claim 7, wherein the angle is strictly greater than 0°, preferably greater than 1°.

9. The sleeve according to any one of claims 1 to 8, wherein the inner orifices (73) of the hole (72) are configured as a sequence of N (88-11, 88-21, 88-31, 88-12, 88-22, 88-32), so that in each sequence of inner orifices, the inner orifices (73) of any horizontal row (88) are aligned in the axial direction with the inner orifices (73) of other horizontal rows (88), and N is 4 or more, preferably 6 or 8 or more.

10. The sleeve according to any one of claims 1 to 9, wherein some of the holes (72) are provided with an inner funnel-shaped portion (73a) that opens in the inner orifice (73) and narrows outward.

11. The sleeve according to any one of claims 1 to 10, wherein some holes (72) open in the outer orifice (74) and have an outer funnel-shaped portion (74a) that narrows inward.

12. The sleeve according to claims 10 and 11, wherein the inner funnel-shaped portion (73a) and the outer funnel-shaped portion (74a) intersect.

13. A filtration assembly for a filtration unit with backwashing, comprising a sleeve (70) according to any one of claims 1 to 12 and a plurality of stacked filtration elements (10), each filtration element (10) having a filter medium (22) and a plurality of internal passages (30) for guiding the fluid to be filtered into the filter medium (22), the internal passages (30) opening onto partitioned sectors.

14. A filtration unit (1) comprising the filtration assembly (90) according to claim 13.

Images