Filter element having pleat height

Abstract

A filter element having pleats of different heights, with inwardly and outwardly facing pleats having different pleat heights, a filter including the filter element, and a filtering method using the filter element are disclosed.

Description

Background Art

[0001]

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 395,079, filed Aug. 4, 2022, which is hereby incorporated by reference in its entirety.

[0002]

[0002] In this technical field, there is a need for improved pleated filter elements.

[0003]

[0003] The present invention provides to improve at least some of the problems of the prior art. These and other advantages of the present invention will become apparent from the description set forth below.

Summary of the Invention

[0004]

[0004] One aspect of the present invention provides a cylindrical porous filter, the porous filter comprising an inner core and an outer cage, having an annular gap between the inner core and the outer cage, and having a cylindrical hollow porous filter element disposed within the annular gap between the inner core and the outer cage, the annular gap having a width, the cylindrical hollow porous pleated filter element having first and second end faces, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups being a first filter element subgroup comprising a first bridge with a plurality of longitudinal pleats having a longitudinal pleat height, the first filter element subgroup being alternated with a second filter element subgroup comprising a second bridge with at least one longitudinal counterpleat having a longitudinal counterpleat height, each of the first bridge and the second bridge having a height greater than the width of the annular gap, the plurality of longitudinal pleats in the first filter element subgroup having a first pleat having the greatest height and a second longitudinal pleat having the smallest height, the height of the first longitudinal pleat being in a range 25% to 35% less than the height of the first bridge, the height of the second longitudinal pleat being in a range 65% to 75% less than the height of the first bridge, at least one longitudinal counterpleat in the second filter element subgroup having a longitudinal counterpleat height in a range 25% to 35% less than the height of the second bridge, the first bridge, the longitudinal pleats, the second bridge, and the at least one longitudinal counterpleat being in a laid-over state.

[0005] In one aspect, each first bridge has a front first bridge surface and a rear first bridge surface, each of the longitudinal pleats has a pair of longitudinal pleat legs, each of the longitudinal pleat legs has a first longitudinal pleat leg surface and a second longitudinal pleat leg surface, each second bridge has a front second bridge surface and a rear second bridge surface, at least one longitudinal counter-pleat has a pair of longitudinal counter-pleat legs, each of the longitudinal counter-pleat legs has a first longitudinal counter-pleat leg surface and a second longitudinal counter-pleat leg surface, the first bridge, the longitudinal pleats, the second bridge and at least one longitudinal counter-pleat are in an overlapping state, and in this state, the longitudinal pleat leg surface of one longitudinal pleat is in close contact with at least one of the longitudinal pleat leg surfaces of the adjacent legs of that one longitudinal pleat, the longitudinal pleat leg surfaces of the adjacent longitudinal pleats, the rear first bridge surface and the front second bridge surface, and the longitudinal counter-pleat leg surface of at least one longitudinal counter-pleat is in close contact with at least one of the longitudinal counter-pleat leg surfaces of the adjacent legs of that one longitudinal counter-pleat, the front first bridge surface and the rear second bridge surface.

[0006] In another aspect, a method of filtering a fluid is provided, the method including the step of flowing a fluid through an embodiment of a cylindrical porous filter, the cylindrical porous filter comprising an inner core and an outer cage, having an annular gap between the inner core and the outer cage, having a cylindrical hollow porous filter element disposed within the annular gap between the inner core and the outer cage, the annular gap having a width, the cylindrical hollow porous pleated filter element having first and second end faces, the cylindrical hollow porous pleated filter element comprising a first filter element subgroup comprising a first bridge followed by a plurality of longitudinal pleats having a longitudinal pleat height, and a second filter element subgroup comprising a second bridge followed by at least one longitudinal counterpleat having a longitudinal counterpleat height, the first and second filter element subgroups being alternating, each of the first and second bridges having a height greater than the width of the annular gap, the plurality of longitudinal pleats in the first filter element subgroup having a first pleat having a greatest height and a second longitudinal pleat having a smallest height, the height of the first longitudinal pleat being in a range 25% to 35% less than the height of the first bridge, the height of the second longitudinal pleat being in a range 65% to 75% less than the height of the first bridge, the at least one longitudinal counterpleat in the second filter element subgroup having a longitudinal counterpleat height in a range 25% to 35% less than the height of the second bridge, the first bridge, the longitudinal pleats, the second bridge, and the at least one longitudinal counterpleat being in an overlapping state.

[0007] In another aspect, a filter element with cylindrical hollow porous pleats is provided. The filter element with cylindrical hollow porous pleats comprises a plurality of filter element groups, and each of the plurality of filter element groups is a first filter element subgroup comprising a first bridge followed by a plurality of longitudinal pleats having a longitudinal pleat height, and a first filter element subgroup alternating with a second filter element subgroup comprising a second bridge followed by at least one longitudinal counter-pleat having a longitudinal counter-pleat height. The plurality of longitudinal pleats in the first filter element subgroup have a first pleat having the largest height and a second longitudinal pleat having the smallest height. The height of the first longitudinal pleat is in the range of 25% to 35% smaller than the height of the first bridge, and the height of the second longitudinal pleat is in the range of 65% to 75% smaller than the height of the first bridge. At least one longitudinal counter-pleat in the second filter element subgroup has a longitudinal counter-pleat height in the range of 25% to 35% smaller than the height of the second bridge.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

[0009] FIG. is a photograph showing a filter element as shown in FIG. 1.

Figure 2B

Figure 2C

Figure 3

[0010] FIG. is a partial cutaway perspective view showing a filter including a filter element having a mixed pleat height as shown in FIG. 2B according to another aspect of the present invention (a filter element that is not fully compressed).

Best Mode for Carrying Out the Invention

[0009]

[0011] According to one aspect of the present invention, a cylindrical porous filter is provided. The porous filter includes an inner core and an outer cage, has an annular gap between the inner core and the outer cage, and has a cylindrical hollow porous filter element disposed in the annular gap between the inner core and the outer cage. The annular gap has a width. The cylindrical hollow porous pleated filter element has first and second end faces. The cylindrical hollow porous pleated filter element includes a plurality of filter element groups. Each of the plurality of filter element groups is a first filter element subgroup including a first bridge with a plurality of longitudinal pleats having a longitudinal pleat height, and is alternately arranged with a second filter element subgroup including a second bridge with at least one longitudinal counter-pleat having a longitudinal counter-pleat height. Each of the first bridge and the second bridge has a height greater than the width of the annular gap. The plurality of longitudinal pleats in the first filter element subgroup have a first pleat having the largest height and a second longitudinal pleat having the smallest height. The height of the first longitudinal pleat is within a range 25% to 35% smaller than the height of the first bridge. The height of the second longitudinal pleat is within a range 65% to 75% smaller than the height of the first bridge. At least one longitudinal counter-pleat in the second filter element subgroup has a longitudinal counter-pleat height within a range 25% to 35% smaller than the height of the second bridge. The first bridge, the longitudinal pleats, the second bridge, and at least one longitudinal counter-pleat are in an overlapped state.

[0010]

[0012] In another aspect, a filter element with cylindrical hollow porous pleats is provided. This filter element with cylindrical hollow porous pleats comprises a plurality of filter element groups. Each of the plurality of filter element groups is a first filter element subgroup comprising a first bridge with a plurality of longitudinal pleats having a longitudinal pleat height, and is alternately arranged with a second filter element subgroup comprising a second bridge with at least one longitudinal counter-pleat having a longitudinal counter-pleat height. The plurality of longitudinal pleats in the first filter element subgroup have a first pleat with the largest height and a second longitudinal pleat with the smallest height. The height of the first longitudinal pleat is in the range of 25% to 35% smaller than the height of the first bridge, and the height of the second longitudinal pleat is in the range of 65% to 75% smaller than the height of the first bridge. At least one longitudinal counter-pleat in the second filter element subgroup has a longitudinal counter-pleat height in the range of 25% to 35% smaller than the height of the second bridge.

[0011]

[0013] In another aspect, a method of filtering a fluid is provided, the method including the step of flowing a fluid through an aspect of a cylindrical porous filter, the cylindrical porous filter comprising an inner core and an outer cage, having an annular gap therebetween, and having a cylindrical hollow porous filter element disposed within the annular gap between the inner core and the outer cage, the annular gap having a width, the cylindrical hollow porous pleated filter element having first and second end faces, the cylindrical hollow porous pleated filter element comprising a first filter element subgroup comprising a first bridge followed by a plurality of longitudinal pleats having a longitudinal pleat height, and a second filter element subgroup comprising a second bridge followed by at least one longitudinal counterpleat having a longitudinal counterpleat height, the first and second filter element subgroups being alternating, each of the first and second bridges having a height greater than the width of the annular gap, the plurality of longitudinal pleats in the first filter element subgroup having a first pleat having a greatest height and a second longitudinal pleat having a smallest height, the height of the first longitudinal pleat being in a range of 25% to 35% less than the height of the first bridge, the height of the second longitudinal pleat being in a range of 65% to 75% less than the height of the first bridge, the at least one longitudinal counterpleat in the second filter element subgroup having a longitudinal counterpleat height in a range of 25% to 35% less than the height of the second bridge, the first bridge, the longitudinal pleats, the second bridge, and the at least one longitudinal counterpleat being in an overlapping state, preferably, the method including the step of obtaining a filtered fluid.

[0012]

[0014] Aspects of the method can include an outside-in flow in which the fluid to be filtered flows from the outer cage through the filter element into the inner core, or an inside-out flow in which the fluid flows from the inner core through the filter element into the outer cage.

[0013]

[0015] In a preferred embodiment, the first impermeable end cap is connected to the first end face of the filter element.

[0014]

[0016] In one embodiment, each first bridge has a first front bridge face and a first rear bridge face, each longitudinal pleat has a pair of longitudinal pleat legs, each longitudinal pleat leg has a first longitudinal pleat leg face and a second longitudinal pleat leg face, each second bridge has a second front bridge face and a second rear bridge face, at least one longitudinal counterpleat has a pair of longitudinal counterpleat legs, each longitudinal counterpleat leg has a first longitudinal counterpleat leg face and a second longitudinal counterpleat leg face, the first bridge, the longitudinal pleats, the second bridge and at least one longitudinal counterpleat are in an overlapping state, and in this state, the longitudinal pleat leg face of one longitudinal pleat is in close contact with at least one of the longitudinal pleat leg faces of the adjacent legs of that one longitudinal pleat, the longitudinal pleat leg faces of the adjacent longitudinal pleats, the first rear bridge face and the second front bridge face, and the longitudinal counterpleat leg face of at least one longitudinal counterpleat is in close contact with at least one of the longitudinal counterpleat leg faces of the adjacent legs of that one longitudinal counterpleat, the first front bridge face and the second rear bridge face.

[0015]

[0017] In some embodiments, the second (inner) longitudinal pleat leg surface of the longitudinal pleat leg of one longitudinal pleat is in close contact with the second (inner) longitudinal pleat leg surface of the adjacent leg of that one longitudinal pleat, and the first (outer) longitudinal pleat leg surface of the longitudinal pleat leg of one longitudinal pleat is in close contact with the rear first bridge surface, or the front second bridge surface, or the first (outer) longitudinal pleat leg surface of an adjacent longitudinal pleat, and / or the second (inner) longitudinal counter-pleat leg surface of the longitudinal counter-pleat leg of at least one longitudinal counter-pleat is in close contact with the second (inner) longitudinal counter-pleat leg surface of the adjacent leg of at least one longitudinal counter-pleat, and the first (outer) longitudinal counter-pleat leg surface of the longitudinal counter-pleat leg of at least one longitudinal counter-pleat may be in close contact with the second bridge surface at the rear or the first bridge surface at the front.

[0016]

[0018] In some embodiments, the first bridge has a height within a range that is 10% to 25% greater than the annular gap between the inner core and the outer cage, and / or the second bridge has a height within a range that is 10% to 25% greater than the annular gap between the inner core and the outer cage.

[0017]

[0019] Advantageously, a filter element, a filter including the filter element, and a filter device including the filter can have a lower packing density and a higher permeability while maintaining a desired pressure difference and a reduced membrane area, and at the same time, the edge flow resistance is reduced.

[0018]

[0020] An embodiment of a filter element according to an aspect of the present invention is in a substantially hollow cylindrical form and includes a pleated porous medium including a mixture of a plurality of pleat heights, where the plurality of longitudinal pleats face inward (the tips face the inner core; height (I) H1 - (I) H2), and at least one longitudinal counter-pleat faces outward (the tip faces the outer cage; counter-pleat: height (O) H1).

[0019]

[0021] Hereinafter, each component of the present invention will be described in more detail, and similar components have the same reference numerals.

[0020]

[0022] FIG. 1 schematically shows one embodiment of a pleated cylindrical hollow porous filter element 3000 (for ease of reference, the pleats are shown in an expanded state before being compressed to form the pleated porous filter element), and this filter element 3000 is disposed within an annular gap G between an inner core 800 provided with holes and an outer cage 900. The annular gap has a width W. The pleated cylindrical hollow porous filter element has a longitudinal axis (see FIG. 3) and first and second end faces. The cylindrical hollow porous pleated filter element comprises a plurality of filter element groups GRP.

[0021]

[0023] Each of the plurality of filter element groups GRP comprises a first filter element subgroup SG1 comprising a first bridge B1 (having a front first bridge face and a rear first bridge face) followed by a plurality of longitudinal pleats 100A, 200A having a longitudinal pleat height. Each of the first filter element subgroups SG1 alternates with a second filter element subgroup SG2 comprising a second bridge B2 (having a front second bridge face and a rear second bridge face) followed by at least one longitudinal counter-pleat 100B having a longitudinal pleat height.

[0022]

[0024] The first bridge B1 and the second bridge B2 each have respective heights B1H, B2H that are greater than the width of the annular gap.

[0023]

[0025] The plurality of longitudinal pleats in the first filter element subgroup SG1 has a first pleat having the largest height (I) H1 and a second longitudinal pleat having the smallest height (I) H2. The height (I) H1 of the first longitudinal pleat is in the range of 25% to 35% smaller than the height BH1 of the first bridge B1, and the height (I) H2 of the second longitudinal pleat is in the range of 65% to 75% smaller than the height BH1 of the first bridge B1.

[0024]

[0026] At least one longitudinal counterpleat in the second filter element subgroup SG2 has a longitudinal counterpleat height (O) H1 in the range of 25% to 35% smaller than the height BH2 of the second bridge B2.

[0025]

[0027] The first bridge, the longitudinal pleat, the second bridge and at least one longitudinal pleat are in an overlapping state (shown in FIGS. 2B and 3).

[0026]

[0028] According to this illustrated embodiment, the groups and subgroups in the filter element have different designs and height patterns (continuously repeated units and asymmetric orientations), that is, group = subgroup 1: B1, (I) H1, (I) H2, subgroup 2: B2, (O) H1, and group = subgroup 1: B1, (I) H1, (I) H2, subgroup 2: B2, (O) H1, and the filter element has any suitable number of repeating groups.

[0027]

[0029] Each pleat is provided with a pair of legs, each leg having an inner surface, an outer surface (thus, the legs have opposing inner surfaces and opposing outer surfaces), the length of the legs, and a coronal or tip portion where the legs intersect (adjacent). The pleat is folded. Each leg has a root portion that abuts against the core (for longitudinal counterpleats) or the cage (for longitudinal pleats), and the pleats extend axially from the core or the cage respectively.

[0028]

[0030] In the embodiment shown in FIG. 1, the lengths (I) H1 of the respective legs of the pleats are equal to each other, the lengths (I) H2 of the respective legs of the pleats are equal to each other, the lengths (0) H1 of the respective legs of the pleats are equal to each other, and the lengths (I) H2 and (O) H1 of the respective legs of a pair of pleats are equal to each other.

[0029]

[0031] As will be described in more detail below, for example, as shown in FIGS. 2B and 3, the formed filter element has overlapping pleats. Thus, the first bridge, the longitudinal pleats, the second bridge and at least one longitudinal counter-pleat are in an overlapping state, in which the longitudinal pleat leg surface of one longitudinal pleat is in close contact with at least one of the longitudinal pleat leg surfaces of the adjacent legs of that one longitudinal pleat, the longitudinal pleat leg surfaces of the adjacent longitudinal pleats, the rear first bridge surface and the front second bridge surface, and the longitudinal counter-pleat leg surface of at least one longitudinal counter-pleat is in close contact with at least one of the longitudinal counter-pleat leg surfaces of the adjacent legs of one longitudinal counter-pleat, the front first bridge surface and the rear second bridge surface.

[0030]

[0032] Typically, the second (inner) longitudinal counter-pleat leg surfaces of each one longitudinal counter-pleat are in close contact with the second (inner) longitudinal counter-pleat leg surfaces of the adjacent legs of that one longitudinal counter-pleat, and the first (outer) counter-pleat leg surface of one longitudinal counter-pleat may also be in close contact with the rear first bridge surface or the front second bridge surface, and / or the second (inner) longitudinal pleat leg surfaces of each one longitudinal pleat are in close contact with the second (inner) longitudinal pleat leg surfaces of the adjacent legs of that one longitudinal pleat, and the first (outer) pleat leg surface of one longitudinal pleat may also be in close contact with the first (outer) longitudinal pleat leg surfaces of the adjacent longitudinal pleats, the front first bridge surface or the rear second bridge surface.

[0031]

[0033] By way of example, using the embodiment shown in FIG. 1 for reference, in the superposed state, the rear first bridge surface is in close contact with the first (outer) longitudinal pleat leg surface of the first longitudinal pleat leg of the subsequent longitudinal pleat (100A), and the second (inner) longitudinal pleat leg surface of the first longitudinal pleat leg will be in close contact with the second (inner) longitudinal pleat leg surface of the adjacent second longitudinal pleat leg of the longitudinal pleat (100A). The first (outer) longitudinal pleat leg surface of the second longitudinal pleat leg of the longitudinal pleat (100A) is in close contact with the first (outer) longitudinal pleat leg surface of the first longitudinal pleat leg of the subsequent (adjacent) longitudinal pleat (200A). Referring to FIG. 1 and the like, for example, the front second bridge surface is in close contact with the first (outer) longitudinal pleat leg surface of the second longitudinal pleat leg surface of the subsequent (adjacent) longitudinal pleat (100A) of the longitudinal pleat (200A), and the rear second bridge surface will be in close contact with the first (outer) longitudinal counter pleat leg surface of the first longitudinal counter pleat leg of the subsequent (adjacent) longitudinal counter pleat (100B).

[0032]

[0034] Using FIGS. 1, 2B, 2C and 3 for reference (FIG. 2B shows a fully compressed filter element with superposed pleats), an inner core 800 provided with a cylindrical hole is coaxially arranged along the inner circumference of the pleated porous filter element 3000, a cylindrical cage 900 is arranged along the outer circumference of the filter element, an annular gap G exists between the inner core and the outer cage, the pleated porous filter element is arranged in the gap between the inner core and the outer cage, and this gap has a width W.

[0033]

[0035] The first bridge B1 and the second bridge B2 each have a height B1H, B2H that is greater than the width of the annular gap, and thus the bridges B1 and B2 each have an end portion that is bent so as to face the outer cage and the inner core as part of the overlapped state. In some embodiments, the first bridge has a height within a range that is 10% to 25% greater than the annular gap between the inner core and the outer cage, and / or the second bridge has a height within a range that is 10% to 25% greater than the width of the annular gap between the inner core and the outer cage.

[0034]

[0036] The heights of the longitudinal pleats and the longitudinal counter-pleats are each smaller than the width of the annular gap between the inner core and the outer cage.

[0035]

[0037] As shown in FIG. 2B, in the assembled filter element, the longitudinal pleats are bent in the vicinity of their tip portions (facing the inner core) as part of the overlapped pleats, and the longitudinal counter-pleats are bent in the vicinity of their tip portions (facing the outer cage).

[0036]

[0038] The opposing surfaces of the adjacent legs of the pleats do not necessarily have to be in close contact over the entire axial length of the filter element, but the greater the axial length of the region of close contact, the more effectively the space between the inner and outer circumferences of the filter element 3000 is used. Thus, the adjacent legs are in close contact over an entire continuous region that extends over at least about 50% of the axial length of the filter element 3000, and in some embodiments, at least about 75%, or about 95 - 100%.

[0037]

[0039] The type of the porous filter medium 500 (see FIG. 3) that can be used for the porous filter element of the present invention is not particularly limited and can be selected according to the fluid to be filtered and the desired filtration characteristics. Preferably, the porous filter medium / filter element includes a polymer medium. The filter element / filter can be used to filter fluids such as liquids, gases, or mixtures thereof used in various industries. For example, the filter element / filter can be used to filter process fluids in the microelectronics industry for wet etching cleaning (for example, a material removal process using a liquid chemical or an etchant to remove material from a wafer). For CMP (chemical mechanical planarization), for producing ultrapure water (UPW), and for lithography modules, the fluids can include, for example, SC1 (standard clean 1) fluid, SC2 (standard clean 2) fluid, isopropyl alcohol (IPA, including hot IPA), sulfuric acid (H2SO4, including hot H2SO4), tetramethylammonium hydroxide (TMAH, including hot TMAH), hydrogen peroxide (H2O2, including hot H2O2), ammonium hydroxide (NH4OH, including hot NH4OH), and hydrogen fluoride (HF, including hot HF), particularly those used independently of each other or in combination.

[0038]

[0040] Typically, the pleated porous filter element includes or is a membrane. The membrane can have any suitable pore structure, for example, pore size (for example, by bubble point, or as described in, for example, U.S. Patent No. 4,340,479 such as K LProven by, or characterized by capillary condensation flow porometry), average pore size, average flow pore (MFP) size (e.g., as characterized using a porometer, e.g., a porometer available under the trademarks of Porvair Porometer (Porvair plc, Norfolk, UK) or POROLUX (Porometer.com, Belgium)), pore evaluation, pore diameter (e.g., as characterized using a modified OSU F2 test as described in U.S. Patent No. 4,925,572), or can have a removal evaluation media. The pore structure used depends on the size of the particles utilized, the composition of the fluid being processed, and the desired outflow level of the processed fluid. In some embodiments, the membrane has an average pore size in the range of 10 nm to 150 nm (depending on the application).

[0039]

[0041] The porous membrane can have any desired critical wetting surface tension (e.g., CWST as defined in U.S. Patent No. 4,925,572). The CWST can be selected as further disclosed, for example, in U.S. Patent Nos. 5,152,905, 5,443,743, 5,472,621, and 6,074,869, as is known in the art. Typically, the membrane has a CWST in the range of 28 dynes / cm (28×10 -5 N / cm) to 34 dynes / cm (34×10 -5 N / cm).

[0040]

[0042] Exemplary membranes are disclosed in U.S. Patent Nos. 4,702,840 and 4,900,449. Other membranes may also be suitable, including those disclosed in U.S. Patent Nos. 4,906,374, 4,886,836, 4,964,989, 5,019,260, 4,340,479, 4,855,163, 4,744,132, 4,707,266, 4,203,848, 4,618,533, 6,039,872, 6,780,327, 6,783,937, and 7,189,322. Exemplary membranes include, but are not limited to, nylon membranes, polytetrafluoroethylene (PTFE) membranes, high-density polyethylene (HDPE) membranes, and highly asymmetric polyarylsulfone (HAPAS) membranes. Exemplary membranes may be used individually or in combination with any other exemplary membranes having the same or different properties.

[0041]

[0043] The filter can include additional elements, layers, or components that can have different structures and / or functions, such as at least one of any one or more of prefiltration, support, drainage, spacing, and interference.

[0042]

[0044] For example, in the embodiment of the filter 3100 shown in FIG. 3, in addition to a cylindrical inner core 800 provided with holes coaxially arranged along the inner circumference of the filter element, and a cylindrical outer cage 900 arranged along the outer circumference of the filter element 3000, the illustrated filter includes a first pleated mesh 501 in contact with the first (e.g., upstream) surface of the porous media 500 of the filter element, and a second pleated mesh 502 in contact with the second (e.g., downstream) surface of the porous media 500 of the filter element, providing a three-layer composite material. In these embodiments where the filter includes the first pleated mesh and / or the second pleated mesh, reference to contact between the surfaces of the pleats refers to contact between the meshes on the referenced surface of the filter element. For example, the second (inner) longitudinal counter-pleat leg surface of one longitudinal counter-pleat being in close contact with the second (inner) longitudinal counter-pleat leg surface of an adjacent leg of that one longitudinal counter-pleat means that the mesh on the second (inner) longitudinal counter-pleat leg surface of one longitudinal counter-pleat is in close contact with the mesh on the second (inner) longitudinal counter-pleat leg surface of an adjacent leg of that one longitudinal counter-pleat.

[0043]

[0045] The components (mesh, filter medium) forming the filter element can be formed into a composite material by conventional filter manufacturing techniques before or simultaneously with corrugation.

[0044]

[0046] The mesh (the term "mesh" also includes "screen") prevents the opposing surfaces of the filter medium from contacting each other when the pleats are superimposed, and allows fluid to flow uniformly to or from substantially all portions of the surface of the filter medium. Thus, substantially the entire surface area of the filter medium can be effectively used for filtration.

[0045]

[0047] A variety of meshes are suitable for use in aspects of the present invention. The mesh can be made from any material having suitable edgewise flow characteristics, i.e., any material having suitable resistance to fluid flow passing through the layer in a direction parallel to its surface. The edgewise flow resistance of the drainage mesh is preferably such that the pressure drop across the drainage layer is less than the pressure drop across the entire filter medium, and thus low enough to provide a uniform distribution of fluid along the surface of the filter medium.

[0046]

[0048] Typically, a filter 3100 according to one aspect of the present invention includes end caps 850 (only one of which is shown in FIG. 3) at one or both ends of the filter element 3000. The end caps 850 can be either blind (closed) end caps or open end caps, and the materials from which they are formed and their shapes can be selected according to the filtration conditions and the material of the member to which the end caps are joined. Preferably, the end caps 850 are attached to the filter element 3000, but they may also be attached to the inner core 800 or the outer cage 900. Conventional techniques can be used to attach the end caps to the filter element.

[0047]

[0049] Optionally, in some aspects, inserts in the form of strips of material having good affinity for the end cap material are formed in a wavy shape within the ends of the filter element 3000 to improve the sealing between the two ends of the filter element 3000 and the end caps 850. For example, if the end caps are made of a fluoropolymer, strips of another fluoropolymer such as fluorinated ethylene propylene (FEP) resin can be formed in a wavy shape within the ends of the filter element as inserts. The insert need only be wide enough to adhere the filter media to the end cap, and thus may extend only over a portion of the axial length of the filter element 3000. A typical width of the insert is about 0.5 inches.

[0048]

[0050] The filter device and filter configuration are suitable for an outside-in flow where the fluid to be filtered flows from the outer perimeter (e.g., outer cage) through the filter element into the hollow central portion (e.g., inner core), or can be used for an inside-out flow where the fluid flows from the hollow central portion (e.g., inner core) through the filter element to the outer perimeter (e.g., outer cage).

[0049]

[0051] The filter element 3000 shown in FIG. 3 can be manufactured by various techniques, such as those described in U.S. Patent No. 5,543,047, for example.

[0050]

[0052] In one technique, the filter composite is first corrugated to form a corrugated sheet, cut to an appropriate length or an appropriate number of pleats, and then formed into a cylindrical shape. The longitudinal edges of the corrugated sheet are then sealed to each other by conventional means to form a cylindrical filter element. The pleats of the filter element are then overlapped when the filter element 3000 is inserted into the cage 900. After the filter element is fitted into the cage 900, the core 800 is inserted into the hollow central portion of the filter element 10, and then end caps are attached to the ends of the filter element to form the completed filter.

[0051]

[0053] A filter comprising a filter element is disposed within a housing that includes at least one inlet and at least one outlet, defines at least one fluid flow path between the inlet and the outlet, and the filter constitutes the filter device across the fluid flow path. Preferably, the filter device is sterilizable. Any housing of an appropriate shape that provides at least one inlet and at least one outlet can be used.

[0052]

[0054] The housing can be manufactured from any suitable rigid impermeable material including any impermeable thermoplastic material compatible with the fluid being processed. For example, the housing can be manufactured from a metal such as stainless steel or from a polymer. In a preferred embodiment, the housing is a polymer and in some embodiments, a transparent or translucent polymer such as acrylic, polypropylene, polystyrene or polycarbonate resin.

[0053]

[0055] The following examples further illustrate the invention but should of course not be construed as limiting its scope.

Example

[0054]

[0056] This example demonstrates that the permeability of a test filter device including a filter element according to one aspect of the invention is improved as compared to a test filter device including a commercially available filter element having longitudinally superposed pleats (longitudinally superposed pleats as schematically described in U.S. Patent No. 5,543,047).

[0055]

[0057] The filter element (high density polyethylene (HDPE) membrane) is pleated using a Rabofsky PM600 corrugator such that the first and second bridge heights are 1 inch (the width of the gap is 0.85 inch) and (I) the height of H1 is 0.6 inch and (I) the height of H2 is 0.4 inch, (O) the height of H1 is 0.3 inch (see Figures 1, 2A and 2B) and has upstream and downstream meshes. The pore size is 15 nm.

[0056]

[0058] The commercially available filter element (HDPE membrane) has a longitudinal pleat height of 1 inch.

[0057]

[0059] The filter element according to one aspect of the present invention and a commercially available filter element have an inner core and an outer cage provided with the same holes, and have the same gap width of 85 inches. Each filter element has an open end cap at one end and a closed end cap at the other end, and is disposed within a test housing arranged for outside-in flow.

[0058]

[0060] A test device having a filter element according to one aspect of the present invention has the same pressure drop as a test device having a commercially available filter element, but has a smaller membrane area. Accordingly, the permeability (flow rate per unit area per unit pressure drop) of the filter element according to one aspect of the present invention shows an improvement of up to 20%.

[0059]

[0061] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference in their entirety to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0060]

[0062] The use of the terms "a", "an", "the", and "at least one" and similar referents in the context of describing the present invention (in particular, in the context of the following claims) should be construed to include both the singular and the plural unless otherwise indicated herein or clearly contradicted by the context. The use of the term "at least one" (e.g., "at least one of A and B") following a list of one or more items should be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B) unless otherwise indicated herein or clearly contradicted by the context. The terms "comprising", "having", "including", and "containing" should be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise stated. The recitation of a range of values herein is merely intended to serve as a convenient method of referring individually to each separate value falling within the range, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by the context. The use of any examples, or exemplary language (e.g., "such as") provided herein is merely intended to better illustrate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0061]

[0063] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect those skilled in the art to appropriately use such variations, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, the invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Further, unless otherwise indicated herein or clearly contradicted by context, any combination of any possible variations of the above-described elements is included in the invention.

Claims

1. A cylindrical porous filter, The cylindrical porous filter comprises an inner core and an outer cage, the cylindrical porous filter has an annular gap between the inner core and the outer cage, and the cylindrical porous filter has a cylindrical hollow porous pleated filter element disposed within the annular gap between the inner core and the outer cage, the annular gap has a width, The cylindrical hollow porous pleated filter element has a first end face and a second end face, and the cylindrical hollow porous pleated filter element comprises a plurality of filter element groups. The cylindrical hollow porous pleated filter element comprises a membrane having an average pore size in the range of 10 nm to 150 nm. Each of the plurality of filter element groups comprises a first filter element subgroup that alternates with a second filter element subgroup, the first filter element subgroup comprises a first bridge consisting of a plurality of longitudinal pleats having a plurality of longitudinal pleat heights, and the second filter element subgroup comprises a second bridge consisting of at least one longitudinal counterpleat having a longitudinal counterpleat height. Each of the first bridge and the second bridge has a height greater than the width of the annular gap. The plurality of longitudinal pleats in the first filter element subgroup comprises a first longitudinal pleat having the greatest height and a second longitudinal pleat having the smallest height, wherein the height of the first longitudinal pleat is within a range of 25% to 35% less than the height of the first bridge, and the height of the second longitudinal pleat is within a range of 65% to 75% less than the height of the first bridge. The longitudinal counterpleat height of at least one longitudinal counterpleat in the second filter element subgroup is within a range of 25% to 35% less than the height of the second bridge. A cylindrical porous filter in which the first bridge and the plurality of longitudinal pleats and the second bridge and the at least one longitudinal counter pleat are in an overlapping state.

2. The cylindrical porous filter according to claim 1, wherein a first impermeable end cap is connected to the first end face of the filter element.

3. Each first bridge has a front first bridge surface and a back first bridge surface, Each of the plurality of longitudinal pleats has a pair of longitudinal pleat legs, and each of the longitudinal pleat legs has a first longitudinal pleat leg surface and a second longitudinal pleat leg surface. Each second bridge has a front second bridge surface and a back second bridge surface. The at least one longitudinal counter pleat has a pair of longitudinal counter pleat legs, each of which has a first longitudinal counter pleat leg surface and a second longitudinal counter pleat leg surface. The first bridge and the plurality of longitudinal pleats and the second bridge and the at least one longitudinal counter pleat are in an overlapping state, and in the overlapping state, The longitudinal pleat leg surface of one longitudinal pleat is in close contact with at least one of the longitudinal pleat leg surfaces of adjacent legs of the same longitudinal pleat, the longitudinal pleat leg surface of the adjacent longitudinal pleat, the first bridge surface on the back side, and the second bridge surface on the front side. The cylindrical porous filter according to claim 1 or claim 2, wherein the longitudinal counterpleat leg surface of a longitudinal counterpleat is in close contact with at least one of the longitudinal counterpleat leg surfaces of adjacent legs of one longitudinal counterpleat, a first bridge surface on the front side, and a second bridge surface on the back side.

4. The cylindrical porous filter according to claim 1 or 2, wherein the first bridge has a height in the range of 10% to 25% greater than the annular gap between the inner core and the outer cage.

5. The cylindrical porous filter according to claim 1 or 2, wherein the second bridge has a height in the range of 10% to 25% greater than the annular gap between the inner core and the outer cage.

6. A method for processing a fluid, the method comprising circulating the fluid through a cylindrical porous filter according to claim 1 or claim 2.

7. The method according to claim 6, comprising circulating the fluid to be filtered through the outer cage, the cylindrical hollow porous pleated filter element, and the inner core.

8. A cylindrical hollow porous pleated filter element, The cylindrical hollow porous pleated filter element comprises a plurality of filter element groups, Each of the plurality of filter element groups comprises a first filter element subgroup that alternates with a second filter element subgroup, the first filter element subgroup comprises a first bridge consisting of a plurality of longitudinal pleats having a plurality of longitudinal pleat heights, and the second filter element subgroup comprises a second bridge consisting of at least one longitudinal counterpleat having a longitudinal counterpleat height. The plurality of longitudinal pleats in the first filter element subgroup comprises a first longitudinal pleat having the greatest height and a second longitudinal pleat having the smallest height. The height of the first longitudinal pleat is within a range of 25% to 35% less than the height of the first bridge, the height of the second longitudinal pleat is within a range of 65% to 75% less than the height of the first bridge, and the longitudinal counterpleat height of at least one longitudinal counterpleat in the second filter element subgroup is within a range of 25% to 35% less than the height of the second bridge. The cylindrical hollow porous pleated filter element comprises a membrane having an average pore size in the range of 10 nm to 150 nm.

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