Patent Application
20120211408
This invention generally relates to filters. More specifically, this invention relates to filter baskets having internal support elements suitable for high-pressure filtering operations.
Filter baskets are used in housings in a variety of applications, and in a large number of industries. Filter baskets may be employed in several configurations, including non-backwashing, backwashing, and pre-coat resin arrangements.
Housings with filter baskets have a long history of use in industrial markets. Applications where these types of filters are used has grown to include environments where the standard disposable non-woven polymer filter bags are not acceptable or cost-effective. Reusable metal filter baskets are used instead of disposable filter baskets for a variety of reasons such as temperature, characteristics of the fluid being filtered, economy, and ability to clean the filter basket in place through backwashing.
A standard metallic filter basket has similar dimensions to a nonwoven basket. Since a metal filter media typically does not hold as much contaminant as non-woven polymer filter bags, there have been attempts to compensate for the differences in dirt hold capacity between non-woven depth media and surface filter metallic media by increasing the area of metallic media in a given filter basket envelope. A typical method used for increasing the surface area of metallic media filter baskets is the use of tube bundles. Although utilizing tube bundles can increase the media surface area when compared to the standard single-tube metallic filter basket design, there are still applications where the metallic filter baskets need to be improved to reduce pressure drop, reduce flux rate across the filter media, and/or reduce system down time and reduce backwashing waste by increasing the time interval between filter basket change-out or backwashing.
Some filter baskets may be employed to filter fluids under high pressures, potentially resulting in a high pressure gradient across the filter media. In high-pressure filtering operations, filter baskets may be deformed out of their originally-manufactured configuration.
Additionally, there is a need to reduce the foot print or volume occupied by filter systems when large and/or multiple filter housings are necessary to meet a minimum filter area requirement, and a need for a filter basket that can hold more contaminants than currently available filter baskets.
The invention provides such a filter and method by providing more filter media area in the same filter element envelope as currently existing products. The filters of the present invention may be provided with internal support elements which provide increased resistance to deformation of filter media when the filter is used in high-pressure filtering operations. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
In one aspect, the invention provides a filter having sheets of metal filter media surrounding a longitudinal axis. The filter has inlet and outlet faces at opposite axial ends of the filter, and each filter media sheet extends between the filter inlet and outlet faces. Inlet passages are formed between the sheets of metal filter media, where each inlet passage is open to the inlet face and closed to the outlet face, and has a length extending generally in the direction of the longitudinal axis. Outlet passages are also formed between the sheets of metal filter media, where each outlet passage is open to the outlet face and closed to the inlet face, and has a length extending generally in the direction of the longitudinal axis. A support core is positioned within at least one outlet passage. A flow path from the inlet face to the outlet face passes through at least one of the sheets of filter media.
In another aspect, the invention provides an extended area filter. The extended area filter comprises a first tubular sheet of metal filter media surrounding a longitudinally extending axis between opposed first and second end faces of the filter, where the first and second end faces are at opposite axial ends of the filter with one of the faces being an inlet face and the other an outlet face. A second tubular sheet of metal filter media is telescopically interfit within the first tubular sheet of filter media, a third tubular sheet of metal filter media is telescopically interfit within the second tubular sheet of filter media, and a fourth tubular sheet of metal filter media is telescopically interfit within the third tubular sheet of filter media. A first annular closure is provided between ends of the first and second tubular sheet proximate the first end face; a second annular closure is provided between ends of the second and third tubular sheet proximate the second end face; and a third annular closure is provided between ends of third and fourth tubular sheet proximate the first end face. Support elements are positioned between the first and second tubular sheets, and between the third and fourth tubular sheets, such that the support elements prevent contact between the first and second tubular sheets and between the third and fourth tubular sheets. First annular flow passages extend generally in the direction of the longitudinal axis, and are formed between the first and second tubular sheets and between the third and fourth tubular sheets, such that the first annular flow passages are open to the second flow face and are closed to the first flow face. A second annular flow passage extends generally in the direction of the longitudinal axis, and is formed between the second and third tubular sheets, such that the second annular flow passage is open to the first flow face and closed to the second flow face. A flow path from the inlet face to the outlet face passes through at least one of the tubular sheets of metal filter media.
In yet another aspect, the invention provides a filter apparatus comprising a housing, with an interior volume divided into an inlet plenum and an outlet plenum. The housing also comprises a filter holder separating the inlet plenum and outlet plenum. A filter is mounted in the filter holder. The filter comprises a longitudinal axis, an inlet and outlet faces at opposite axial ends of the filter. The filter inlet face is in fluid communication with the inlet plenum, and the filter outlet face is in fluid communication with the outlet plenum. The filter further comprises filter media tubes concentrically arranged about the longitudinal axis such that each filter media tube extends between the inlet and outlet faces of the filter. The filter tubes are configured to form a plurality of inlet passages between the plurality of filter tubes, such that each inlet passage is open to fluid flow at the inlet face and closed to fluid flow at the outlet face, and has a length extending generally in the direction of the longitudinal axis. Each outlet passage is fitted with an internal supporting element. A fluid flow path from the housing inlet plenum to the housing outlet plenum passes through at least one of the sheets of filter media and through an internal supporting element.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
Referring to
As can be seen in the drawings, a plurality of filter tubes 116 are arranged to provide a lot of metal filter media within a compact volume area. In the embodiment shown, filter tubes 116 are generally cylindrical (including a cylinder shaped or tapered/cone shaped), and are concentrically disposed about the longitudinal axis 118 of filter 100. In other embodiments, filter tubes 116 may be other shapes, e.g., elliptical or polygonal with straight sides (“annular” and “tubular” as used herein are meant to be generic to include generally cylindrical and these other shape possibilities). In preferred embodiments, sheets of filter media 116 have a preferential flow direction for fluid filtration, and sheets of filter media are oriented such that filter fluids flow from a flow-in surface 120 of filter 100 to a flow-out surface 122 of filter 100. Concentric sheets of filter media 116, in conjunction with inlet spacer rings 142 and outlet spacer rings 144 that provide for annular closures, define alternating annular cylindrical volumes that provide inlet and outlet flow passages, shown as unfiltered fluid receiving volumes 130 or inlet flow volumes 130, and filtrate receiving volumes 132 or outlet flow volumes 132. Inlet flow volumes 130 are open at inlet flow face 124 and are sealingly closed at outlet face 126, and are in fluid communication with the flow-in surfaces 120 of filter tubes 116. Outlet flow volumes 132 are open at outlet flow face 126 and are sealingly closed at inlet face 124, and are in fluid communication with the flow-out surfaces 120 of filter tubes 116. It is understood that inlet and outlet flow volumes are reversible and depend upon how the filter is used in application (e.g., if flow is reversed, the inlet flow volumes become outlet flow volumes and vice versa).
To provide for mounting and/or sealing of the filter, a mounting ring that may take the form of a weld-compatible metal end ring 102 may be provided. End ring 102 of filter 100 includes a circumferential flange 104, a sealing surface 106 of flange 104, an annular wall 108, a screen mounting surface 112, and a filter media attachment flange 114. Filter media attachment flange 114 defines an end ring annulus 115 for receiving the outlet face 126 of filter 100. A chamfer 110 may be provided between cylindrical wall 108 of end ring 102 and screen mounting surface 112 of end ring 102. Alternatively, chamfer 110 of end ring 102 may be a rounded exterior corner or a sharp corner. In other embodiments, annular wall 108 may be a tapered, or frustoconical, wall which may be interpositioned between flange 104 of end ring 102 and screen mounting surface 112 of end ring 102. In still other embodiments, sheets of filter media may be joined directly to a annular wall 108 of end ring 108, without a separate filter media attachment flange 114. End ring 102 may optionally be provided with one or more support structures (rod, flat bar, perforated plate, etc.) configured to support the plurality of filter media tubes at the outlet face 126 of filter 100 or the inlet face 124 of filter 100, thereby constraining movement of the filter tubes 116 of filter 100 in both radial and axial directions.
In a typical embodiment, tubes of metal filter media 116 may include a longitudinal seam 128. In a preferred embodiment, longitudinal seam 128 is a welded seam providing additional structural support for tubes of filter media 116. In the embodiments shown, filter tubes 116 are formed and welded without the use of a safe edge material incorporated in longitudinal seam 128 and longitudinal weld 129. However, longitudinal seam 128 and longitudinal weld 129 may optionally include one or a pair of safe edges 140 (discussed in more detail with reference to
Referring to
In the exemplary embodiment shown in
A second filter media tube 116 is positioned as a second filter media tube 158, telescoped within first filter media tube 156 and substantially parallel to longitudinal axis 118. An appropriately sized inlet face spacer ring 142, shown as first inlet spacer ring 160, is interpositioned between first filter media tube 156 and the second filter media tube 158, adjacent to inlet face 124 of filter 100. The ends of the first filter media tube 156 and the second filter media tube 158 are sealing joined to first inlet spacer ring 160 at the ends of tubes 156, 158 adjacent to inlet face 124.
First and second filter tubes 156, 158 and first inlet spacer ring 160 thereby define a first flow-out volume 162, the first flow-out volume 162 being an annular cylinder closed to fluid flow at the end adjacent to inlet face 124 and open to fluid flow at the end adjacent to outlet face 126. First inlet spacer ring 160 thereby blocks the flow of the fluid being filtered from passing directly from the inlet face 124 and inlet volumes 130 to the outlet face 126 and the outlet volumes 132 without passing through a filter media.
A third filter media tube 116 is positioned as a third filter media tube 168, telescoped within second filter media tube 158 and substantially parallel to longitudinal axis 118. An appropriately sized outlet face spacer ring 144, shown as first outlet spacer ring 164, is interpositioned between second filter media tube 158 and the third filter media tube 168, adjacent to outlet face 126 of filter 100. The ends of the second and third filter media tubes 158, 168 adjacent to outlet face 126 are sealingly joined to first outlet spacer ring 164.
Second and third filter tubes 158, 168 and first outlet spacer ring 164 thereby define a first flow-in volume 166, the first flow-in volume 166 being an annular cylinder open to fluid flow at the end adjacent to inlet face 124 and closed to fluid flow at the end adjacent to outlet face 126. First outlet spacer ring 164 thereby blocks the flow of the fluid being filtered from passing directly from the inlet face 124 and inlet volumes 130 to the outlet face 126 and the outlet volumes 132 without passing through a filter media.
A fourth filter media tube 116 is positioned as a fourth filter media tube 170, telescoped within third filter media tube 168 and substantially parallel to longitudinal axis 118. An appropriately sized inlet face spacer ring 142, shown as second inlet spacer ring 172, is interpositioned between third filter media tube 168 and the fourth filter media tube 170, adjacent to inlet face 124 of filter 100. The ends of the third filter media tube 168 and the fourth filter media tube 170 are sealingly joined to second inlet spacer ring 172 at the ends of filter tubes 168, 170 adjacent to inlet face 124.
Third and fourth filter tubes 168, 170 and second inlet spacer ring 172 thereby define a second flow-out volume 174, the second filtrate volume 174 being an annular cylinder closed to fluid flow at the end adjacent to inlet face 124 and open to fluid flow at the end adjacent to outlet face 126. Second inlet spacer ring 172 thereby blocks the flow of the fluid being filtered from passing directly from the inlet face 124 and inlet volumes 130 to the outlet face 126 and the outlet volumes 132 without passing through a filter media. It should be noted that first, second, third and fourth are used for differentiation purposes only, rather than a specific location or arrangement.
Still referring to
In a preferred embodiment of an extended area filter, inlet spacer rings 142 and outlet spacer rings 144 are formed from a stainless steel material and are impermeable to fluid flow. In other embodiments, spacer rings 142, 144 may be formed from a permeable material, thereby adding additional filtration capacity to the extended area filter. Such closures can thereby either be permeable or provide sealed ends. In the embodiments shown, filter media tubes 116 are sealingly joined to spacer rings 142, 144 by welding, e.g., gas tungsten arc welding. In other embodiments, spacer rings 142, 144 may be another material, such as a plastic, epoxy, or elastomer, and may be joined to filter tubes 116 by thermal welding, an adhesive compound (epoxies, cements, self-setting agents, etc.), or mechanical fastening (rolled seam, fasteners, etc.). In yet other embodiments, filter media tubes 116 may be tapered or frustoconical with respect to radial distance from longitudinal axis 118, such that the alternating ends of the filter tubes may be directly joined (welded, adhered, potted, mechanically fastened, etc.) without interpositioned spacer rings 142, 144. All of the foregoing can effectively provide closures between edges of sheets.
As shown in
In other applications, configuration of a primary direction opposite to the described flow direction (i.e., a flow direction from axial flow face 126 to axial flow face 124, and in a direction opposite to flow directions 150, 152) may be desirable. In filters employing layered filter media, it may be advantageous to orient the sheets of filter media 116 such that the layers are oriented to provide optimal filtration when fluid is filtered in the primary flow direction.
Referring to
Referring to
In a preferred embodiment, a safe edge 140 is butt welded to layers 121 and 123 of a filter media 116, such that safe edge 140 extends in a longitudinal direction from the sheets of filter media of filter tubes 116, and such that weld joint 139 joins and seals safe edge 140 to both finer mesh layer 121 and coarser mesh layer 123. In the embodiments shown using a metal screen filter media, safe edge 140 is used at the ends of the tubes to facilitate joining of the sheets of filter media 116 to inlet spacer rings 142, outlet spacer rings 144, an end cap 146, and filter media attachment flange 114 of end ring 102.
Referring to
Safe edges 140 of second and third filter tubes 158, 168 are joined by welded seams 143 to an outlet spacer ring 144, shown as spacer ring 164. As shown in
Referring to
Referring to
In a preferred embodiment, the filter media is a five layer filter media including a guard mesh at flow-in surface 120, a fine filter mesh 121, and coarse support meshes 122 at flow-out surface 120. Exemplary five-layer filter material is commercially available from Purolator Facet, Inc. 8439 Triad Drive, Greensboro, N.C., and is sold under the trademark POROPLATE®. In such a multi-layer embodiment, the fine layer 121 of filter media 116 is positioned in fluid communication with flow-in surface 120 of filter 100, and the coarse layer 123 of filter media 116 is positioned in fluid communication with flow-out surface 122 of filter 100. In other embodiments employing two or more layers of filter media, a coarser layer 123 may be positioned in fluid communication with flow-in surface 120 of filter 100, and a finer layer 121 may be positioned in fluid communication with flow-out surface 122 of filter 100.
Other exemplary filter materials are sold under the trademarks POROMESH® and POROFELT®, which are also both commercially available from Purolator Facet, Inc. POROMESH® is a woven wire mesh similar to POROPLATE® media, that has not been diffusion bonded. POROFELT® media is a fiber-metal felt media typically having a pore size ranging from about 3 microns to about 80 microns. However, fiber-metal felt media may have a pore size less than 3 microns or greater than 80 microns.
Alternatively, sheets of filter media 116 may have a single layer, or may include three or more layers. Other embodiments of extended area filters may advantageously utilize any other porous medium, including but not limited to wire mesh (woven, welded or otherwise), fiber-metal felt (used with or without wire mesh), sintered powder, wire wrap, perforated sheet, wedge wire, sintered wire depth media (as disclosed in U.S. Pat. No. 7,497,257, which is hereby incorporated by reference in its entirety), and polymer (woven and non-woven) filter mediums.
A wire screen or woven wire mesh provides surface filtration, i.e., the screen or mesh prevents particles of the desired size and larger from passing through the screen and all filtered particles are trapped on or near the top surface of the screen. Wire screens for use with extended area filters include screens ranging from a standard mesh size 500 (25.0 microns) to a standard mesh size 4 (5,156 microns). Wire screen having a mesh size smaller than 25 microns or larger than 5,156 microns may also be employed with extended area filter baskets. In preferred embodiments, wire diameters of the filtration media range from about 0.0008 inches to about 0.035 inches. In other embodiments, filtration media may include smaller or larger wire diameters.
Wire wrap is also a common type of surface filtration. Wire wrap is a usually triangular-shaped wire that is wrapped around a supporting structure, with a given gap between wires to accomplish a particle filtration size. One difficulty with surface filtration is that as larger particles are captured on the filter layer, the open spaces become smaller and smaller, thus capturing smaller and smaller particles. Eventually the particles being captured are so fine that the filter becomes plugged, severely reducing or stopping flow of filtrate through the screen. Accordingly, extended area filters may be configured for backwashing to clear accumulated particulate matter from the sheets of filter 116 as necessary.
Other embodiments of extended area filters may employ perforated sheet media having a preferred pore size of between about 250 microns and 1000 microns. However, perforated sheet media may have a pore size smaller than 250 microns or larger than 1000 microns.
Still referring to
Referring to
As shown in
Although this invention can apply to any filter basket size and is not limited to any industry standard filter basket configuration, the example figures show the typical advantage and area improvement of this invention for a size 2 filter basket. In a standard configuration of a size #2 filter, i.e., a filter basket having a single cylinder of a filter media disposed about a longitudinal axis, and having a diameter of about 6.56 inches and a length of about 29.5 inches, the convention filter basket provides a filter media surface area of about 4.23 square feet. In the exemplary embodiment shown in
Referring to
In a preferred embodiment, filter tube 184 is formed from a planar sheet of filter media 116, such as a sheet of sintered laminate filter media. Strips of safe edge material 140 are added to the first and second ends of the filter media sheet to aid in welding the filter tube 184 to, for example, spacer rings 142, 144 and/or media attachment flange 114 during assembly. A flat strip (shown best as strip 141 in
Additional filter tubes of appropriate diameters are telescoped inside one another with appropriately sized spacer rings being inserted between the filter tubes 116. The ends of the tubes are then welded, or otherwise joined, to the spacer rings, forming a seal between the “flow-in” sides of the filter tubes and the “flow-out” sides of the filter tubes. Welding, or other joining method, is done on all tube ends and spacer rings, sealing the “flow-in” side of the filter tube assembly from the “flow-out” side. An end ring 102 is welded, or otherwise joined, to the filter tube assembly, completing the assembly of a filter basket, e.g., filter basket 100. Different styles of end ring 102 may be utilized depending on the size, configuration, and shape of the filter basket housing. Each end ring 102 is configured to mate with and form a seal between the flow-in surfaces 120 and flow-out surfaces 122 of the filter basket for a particular housing.
Referring to
One or more annular openings 318 are provided in basket holder 308 for receiving a filter basket, shown as an expanded area filter basket 100. Annular opening 318 is configured to receive annular wall of end ring 102 of filter 100 such that inlet face 124 of filter 100 is in fluid communication with inlet plenum 310, and outlet face 126 of filter 100 is in fluid communication with outlet plenum 312 of filtration vessel 302. When a filter 100 is installed in annular opening 318 of basket holder 308, flange 104 of filter 100 forms a fluid-impermeable seal between end ring 102 of filter 100 and basket holder 308, thereby preventing fluid communication between inlet plenum 310 of filtration vessel 302 and outlet plenum 312 of filtration vessel 302. Sealing surface 106 of end ring 102 may optionally be provided with an annular closure material (e.g., O-ring, fiber washer, gasket, etc.) providing a face seal between basket holder 308 of filtration vessel 302 and sealing surface 106 of end ring 102 of filter 100. Alternatively, an annular closure material may be provided on basket holder 308 circumferentially surrounding annular opening 318.
An exemplary schematic backwashing system suitable for filtration vessels of the present invention is also shown in
During filtering operation of filtration apparatus 300, valves 342, 344 are open and back-wash valves 330, 332 are closed. A contaminated fluid is flowed from inlet valve 342 through fluid intake 320 and fluid inlet 314 to inlet plenum 310, and filtered by passing through filters 100 to outlet plenum 312. The clean filtrate then flows out of the outlet plenum 312 through fluid outlet 316 and filtrate outflow 322 to filtrate outlet valve 344. To backwash filter baskets 100, fluid intake and outflow valves 342, 344 are closed and valves 330, 332 are opened. A backwash cleaning fluid is then flowed from backwash fluid reservoir 340 to outlet plenum 312, through filters 100 (in a reverse direction from normal flow) to inlet plenum 310, thereby removing trapped particulate matter from the flow-in surfaces 120 of filters 100. The resulting contaminated backwash fluid is then passed from inlet plenum 310 to backwash waste vessel 338 for appropriate disposal. Once backwashing is complete, valves 330, 332 are closed and valves 342, 344 are opened, allowing filtering from inlet plenum 310 to outlet plenum 312 through filters 100 to resume.
A filtration apparatus 300 configured for in-line filtration may also be provided with a backflow system for cleaning extended area filters installed therein, shown as a fluid intake pipe 320 provided in fluid communication with inlet plenum 310, a permeate supply valve 342, and a pipe 326 and a backwash waste valve 330, and additionally a filtrate outflow 322 provided in fluid communication with outlet plenum 312, a pipe 328 and backwash fluid supply valve 338, and a filtrate outlet valve 344. Backwash waste valve 330 is in fluid communication with a pipe 334 receiving backwash waste, and backwash fluid supply valve 332 is in fluid communication with a pipe 336 providing a backwash fluid supply.
Extended area filters may be provided with an internal support element, shown generally in
In a preferred embodiment, internal support elements 400 are formed from a metal material compatible with the material used to form the receiving extended area filter. Thus, in one preferred embodiment, internal support elements 400 are formed from a stainless steel material. In other embodiments, internal support elements 400 may be formed from another metal or other materials such as a plastic.
Referring to
As shown in
The wire count and size of the wires may be varied according to specific design and application. Wire diameter is generally chosen such that the height of the welded wire mesh is approximately equal to the thickness of the internal annulus defined by outlet flow volumes 132 of an extended area filter, for example a filter 100 or 200. In a preferred embodiment, the wire counts range from 2 to 4 wires per inch, and have a wire diameter of about 0.047 inch. In other embodiments, wire diameters may range from about 0.060 to 0.028 inches. In some other embodiments, a larger or smaller wire diameter may be used. As shown in
In another embodiment, circumferential wire round 406 of wire wrap core 402 may be formed from a single wire that is helically wrapped around a set of axial wire rods 404. In such an embodiment, the spacing between adjacent positions (that is, the points on one complete turn of the helix about longitudinal axis 118 of an extended area filter) on circumferential wire round 406 may be selected by varying the pitch of the helix. Alternatively, circumferential wire rounds 406 may also be formed as a double helix, triple helix, etc.
As shown in
As best shown in
By contactingly supporting the inner surfaces 122 of first filter media tube 156 and second filter media tube 158, the internal support element 400 places radially inward force 412 and radially outward force 414 in opposition, thereby preventing or reducing deformation of filter tubes 156 and 158 into outlet flow volume 132 during high-pressure filtering operations. During filtering, the open lattice areas 416 of internal support element 400 allow filtered fluid to flow through outlet flow volumes 132 of an extended area filter to outlet face 126, as shown by fluid flow paths 154.
Internal support elements 400 typically have a porosity at least greater the porosity of the filter media of filter media tubes 116, and more preferably at least twice as great, and in some embodiments at least 3 times as great, to provide adequate support while facilitating drainage and not impose much if any additional restriction to flow. For example, internal support elements 400 may have a porosity between about 40 percent and about 90 percent, and the metal filter media may have a porosity between about 30 percent and about 60 percent. In other examples, internal support elements 400 may have a porosity from about 50 percent to about 80 percent, and the metal filter media may have a porosity between about 35 percent and about 55 percent. The internal support element may be less restrictive to flow than the filter media. Alternatively, if relatively weak filter media material is used, then the core may be designed to be more restrictive to flow so that the pressure drop across the filter media may be effectively lowered.
In a preferred embodiment, a single internal support element 400 is received in each outlet flow volume 132 of an extended area filter. For some applications, it may be desirable for each internal support element 400 to occupy all or substantially all the longitudinal length of outlet flow volumes 132. In other embodiments, internal support structures 400 may occupy only a portion of each outlet flow volume. For example, a single internal support structure 400 may be sized to occupy 80 percent, 60 percent, 40 percent, 20 percent, or less than 20 percent of each outlet flow volume. In other embodiments, each outlet flow volume 132 may be provided with more than one internal support element 400.
Internal support elements 400 may be placed within outlet flow volumes 132 of an extended area filter during manufacture of the filter. In other embodiments, internal support 400 may be separately manufactured and dimensioned to be slideably received by the outlet flow volumes 132 of an extended area filter.
As shown in
The layers 432 and 434 of multi-layer welded wire core 430 may be welded or otherwise joined, or may not be joined together. As may be readily appreciated, multi-layer welded wire core 430 may also be formed from more than two layers placed in a mutually supporting concentric relation.
Axial rods 404 of rod cage core 440 may be held in place with one or two rings, shown as end rings 442. As shown, end rings 442 are formed of a strip of material having a height less than the diameter of axial rods 404, thereby allowing fluid flow past the end rings 442 when rod cage core 440 is positioned within an outlet flow volume 132 of an extended area filter. In another embodiment, rode cage core 440 may be provided with a single ring proximate to inlet face 124, thereby leaving an open flow path through outlet face 126. In still another embodiment, axial rods 404 are held in place with one or more flat rings positioned along the length of axial rods 404. The diameter of axial rods 404 of rod cage 440 are generally chosen such that the diameter is approximately equal to the thickness of the internal annulus defined by outlet flow volumes 132 of an extended area filter, for example a filter 100 or 200. In a preferred embodiment, axial rods 404 of rod cage core 440 have a diameter of 0.187 inches and a center to center spacing of 1 inch, resulting in a porosity of 85 percent.
The pleats of square pleated core 450 define individual channels 458 within the core 450. When square pleated core 450 is installed in an outlet flow volume 132 of an extended area filter, channels 458 are in fluid communication with flow-out surfaces 122 of the extended area filter. Channels 458 define an axial flow path within outlet flow volume 132, thereby directing flow of filtered fluids in the outlet flow volume 132 towards outlet face 126 of the filter.
In a preferred embodiment, square pleated core 450 is rolled from a flat perforated sheet having a thickness of about 0.094 inches and a 7 percent open perforated area, to an overall thickness (distance from the inner diameter to the outer diameter of square pleated core 450) of about 0.188 inches, resulting in an overall porosity of square pleated core 450 of about 42 percent. In another embodiment, square pleated core 450 may be formed by extrusion, and the material of square pleated core 450 subsequently perforated. In other embodiments, the material of square core 450 is not perforated. In still other embodiments, a sheet of another material such as a wire mesh may be pleated and rolled to form square pleated core 450.
The pleats of triangular pleated core 460 define individual channels 458 within the core 460. When triangular pleated core 460 is installed in an outlet flow volume 132 of the extended area filter, channels 458 are in fluid communication with flow-out surfaces 122 of an extended area filter. Channels 458 define an axial flow path 459 within outlet flow volume 132, thereby directing flow of filtered fluids in the outlet flow volume 132 towards outlet face 126 of the filter.
Triangular pleated core 460 may be formed from flat sheet of perforated metal into a pleated sheet and rolled or formed into a cylindrical configuration. In a preferred embodiment, triangular pleated core 460 is formed from a perforated sheet having a thickness of about 0.05 inches, to a pleat depth (distance from the inner diameter to the outer diameter of triangular pleated core 460) of about 0.409 inches, resulting in an overall porosity of triangular pleated core 460 of about 70 percent. In other embodiments, the material of triangular core 460 is not perforated. In other embodiments, a sheet of another material, such as a welded or woven wire mesh, may be pleated and rolled to form triangular pleated core 460. In still other embodiments, triangular pleated core 460 may be formed by extrusion.
In some embodiments of extended area filters having internal supports, it may be desirable to provide additional internal support elements 400 in inlet flow volumes 130. Where an extended area filter is provided with internal support elements in both the inlet flow volumes 130 and the outlet flow volumes 132, the filter may be used in high-pressure filtration applications in either a forward flow direction or a reverse flow direction. In some applications, it may be further desirable to reinforce the outermost filter tube 156, for example by bands placed around the external surface 120 of first filter tube 156, thereby preventing or reducing radially outward deformation of first filter tube 156 during high-pressure filtration in a reverse flow direction.
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference 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.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
This patent application is a continuation-in-part of U.S. patent application Ser. No. 13/031,342, filed Feb. 21, 2011, the entire teachings and disclosure of which are incorporated herein by reference thereto.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13031342 | Feb 2011 | US |
| Child | 13186016 | US |
