Patent Application
20080223797
1. Field of the Invention
This invention relates to compositions and shapes for solid profile filters or “filter blocks,” and methods of making or using the same. While the filter blocks and methods may have applications in many process flow schemes, the preferred embodiments of the invention are particularly beneficial in gravity flow or low pressure applications. The preferred filter blocks are adapted to exhibit improved flow distribution and pressure drop, and, therefore, improved flowrates and media utilization.
2. Related Art
Solid profile filters, or “filter blocks,” for water filtration have been commercially-available for many years. Typically, such filter blocks comprise granular activated carbon (GAC) and polymeric binder, with or without various additives such as lead sorbent, and, hence, are often also referred to as “carbon blocks.” The raw materials are extruded or compressed in molds to form hollow, cylindrical or “tubular” blocks. Examples of conventional carbon blocks are given in Heskett U.S. Pat. No. 3,538,020, Degen U.S. Pat. Nos. 4,664,683 and 4,665,050, “Amway” U.S. Pat. No. 4,753,728, and Koslow U.S. Pat. Nos. 5,019,311 and 5,147,722 and 5,189,092. See
The fluid-flow path through these tubular activated carbon blocks is generally radial. In an out-side-in flow scheme, housing structure and internals distribute water to the outer cylindrical surface of the block, and the water flows radially through the cylindrical wall to the hollow axial space at the center axis of the block. From the hollow axial space or perforated tube provided therein, the filtered water flows out of the block at or near either at the bottom end or the top end of the filter block, depending upon how the internals and ports have been designed.
These tubular filter blocks have a single outside diameter “OD” (the outer cylindrical wall) and a single inside diameter “ID” (the inner cylindrical wall), with the two diameters defining a wall thickness. The cylindrical volume, minus the hollow axial space volume, defines the volume of filtering media. These tubular shapes have end surfaces opposing each other axially. These end surfaces are typically sealed to end caps or other housing or internals structure to cause fluid to flow in a radial direction rather than around the end surfaces of the block. The ID, OD, and axial length define the surface areas, volume, and mass of the tubular-shaped activated carbon block. Activated carbon blocks can be varied in outside diameter, inside diameter, and length in order to achieve a specified volume and surface area of media.
The materials used to make radial-flow activated carbon blocks, as shown in the above-referenced patents and as discussed above, are typically carbon particles ranging from 12×30 US mesh to 80×325 US mesh (Koslow states 0.1 to 3,000 micrometers) and thermoplastic or thermo-set binders that are common to the art and disclosed in the referenced patents. Other materials can be blended with the carbon particles and binder particles such as lead- or other metals-reducing adsorbents.
Particle size, wall thickness, surface area, and compression may all be adjusted separately to achieve a desired pressure drop through a filter. Use of smaller carbon particles, increased compression, or thicker walls will generally increase pressure drop and increase contaminant removal. Use of larger carbon particles, less compression, or thinner walls will generally decrease pressure drop and decrease contaminant removal. Larger diameters (OD and ID) for cylindrical blocks will decrease pressure drop by increasing surface area available to the fluid flowing through the block. A large OD carbon block with a small ID will have more pressure drop than the same carbon block with a larger inside ID, as the length of the fluid path through the block is longer.
Clapham, in U.S. Pat. No. 3,721,072, produces a low-pressure air filter by providing a monolithic extended surface filter sheet, in the form of a wave pattern. Each wave of the extended surface consists of a peak and a trough extending along the entire length of the filter body to the outside boundary of the filter. ('072 FIG. 1). Clapham's wave forms are much smaller than the overall dimensions of the filter body, for example, thirteen waves in a single filter body. Also, Clapham's filter body is substantially wider and longer than it is thick, for example, more than 10 times as long (or at least more than 5 times as long) and also more than 10 times as wide (or at least more than 5 times as wide) as the thickness of the filter body. Therefore, the Clapham filter body may be considered a corrugated filter sheet or filter plate. Clapham's sheet-like or plate-like filter body may be placed in a frame, extending around the periphery of the filter body, made of “metal, glass, wood, plastic, paperboard, and the like . . . or bonded carbon integral to the filter.”
Chapman, in U.S. Pat. Nos. 6,322,615 and 6,056,809, discloses corrugated sheets for air filtration, wherein, as in Clapham, the peaks and troughs extend all the way to the outside boundary of the filter, the wave forms are much smaller than the overall dimensions of the filter body, and the filter body may be considered a corrugated sheet or plate. Methods of making this corrugated filter body comprise rolling the filter material between rollers with multiple V-shaped tools forming the peaks and troughs in the extended plate or sheet surface of the filter body.
Gelderland, et al., in U.S. Pat. No. 6,413,303, disclose activated carbon air filters made of layers of corrugated paper sheets coated in carbon and binder. Insley, et al., in U.S. Pat. No. 6,280,824, disclose polymeric film layers comprising filtration media and each having a corrugated shape. Gelderland, et al. and Insley, et al. each teach flow being through the open spaces defined by the corrugates (parallel to the corrugate troughs), rather than through the corrugated plates (ie parallel, rather than transverse, to the plane of each plate).
Granular activated carbon (GAC), without binder and with or without various additives such as lead sorbent, has been used for year in water filtration. The loose, granular activated carbon is typically loaded as a “filter bed” or “carbon bed” in a compartment inside a filter housing. The housing and internals are adapted to contain the otherwise-loose granules in place in the compartment, and to distribute water to the inlet of the bed and collect the water at the outlet of the bed. A bed of GAC, preferably with other granular media or additives such as ion exchange resin, is the conventional media of choice for low pressure or gravity flow applications, because of the relatively low pressure drop through the bed of granules; no binder is present in the carbon bed, and, hence, no binder fills the spaces between the carbon granules to interfere with fluid flow. The interstitial spaces between the granules allow water flow through the bed with good media contact and without the pressure drop that is expected in a compressed, binder-formed block.
One important application for such filter beds of granular activated carbon is the field of disposable filter cartridges used in gravity flow water pitchers, carafes, countertop tanks, and water coolers. These devices are used in many homes, offices, and business wherein batch purification of volumes of about 2-20 liters of water is desired for personal consumption and cooking. Typically, these devices that include filtration capability are filled with tap water from municipal supplies or rural wells, as the user wishes to remove chlorine or other contaminants, or to generally improve the taste and odor of the water. These devices continue to be very popular, especially in view of the emphasis on healthy drinking water and in view of the expense and inconvenience of purchasing bottled water.
These gravity-flow filtration devices typically feature relatively small, disposable and replaceable filters cartridges that are inserted into the device and used for several weeks of normal use. Examples of these devices and/or of filters that are designed for these devices are disclosed in Design U.S. Pat. No. 416,163, Design U.S. Pat. No. 398,184, U.S. Pat. No. 5,873,995, U.S. Pat. No. 6,638,426, and U.S. Pat. No. 6,290,646. The filter cartridges for these devices contain filtration media that entirely or substantially comprises beds of granular media.
Good flow distribution in the filter is of primary concern in gravity flow or low pressure systems, because flow distribution affects filtration effectiveness and the time at which “breakthrough” of contaminates occurs, and, hence, the time at which the filter should be changed out. As these filtration systems typically do not contain any means for monitoring filtration effectiveness or breakthrough, and, at most, have means for measuring total water that has passed through the filter, it is important that good flow distribution be maintained to maximize use of media, and, hence, to maximize the filtration effectiveness for a given volume of filtered water. If channeling occurs at any time during the filter life, the effectiveness of the filter and/or the effective filter capacity is reduced, and the filtered water quality may drop if the filter is not changed out.
Good water flow rate through the filter is also of primary concern in gravity flow or low pressure systems such as a water pitcher, carafe or countertop tank, because this effects how quickly filtered water from a freshly-water-filled device may be used. Typically, these devices are kept in the refrigerator or on a countertop, and so their total volume is designed to be an amount that is reasonable for such spaces and that is a reasonable weight to carry. Users of such devices typically do not want to wait a long time for the filtered water. Therefore, reasonable flow rate through the filter is important for customer satisfaction and to gain a competitive edge in the marketplace. As most of these water filtration devices typically utilize only gravity to force the water through the filters, achieving adequate flowrate of water through the filter is problematic, especially in view of the goal of effective contaminant removal and long filter life. The goal of low pressure drop for high flowrates would drive the design toward short (shallow) granular filter media beds, but the goal of effective contaminant removal and long life without breakthrough would drive the design to in the opposite direction, toward long (deep) granular filter media beds. Further, achieving adequate flowrate is also problematic because the carbon-based granular media that are used in the filters in question tend to be slightly hydrophobic. Therefore, while excellent water-media contact is needed for good flow distribution and good flow rates, the media actually tends to resist wetting by the water it is intended to filter.
Therefore, conventional filters for water pitcher devices have typically included granular media beds about 2-6 inches deep. Further, important procedures in the installation of a filter into one of these water pitcher devices are the pre-rinse and the pre-wet steps recommended by manufacturers of the devices and the filters. These procedures involve rinsing the filter and then soaking the fresh filter in water for several minutes prior to inserting the filter into the device. These procedures are explained by the manufacturers as steps that remove carbon fines that may reside in the fresh filter, and that wet the granular or particulate carbon media to achieve better flow distribution and flow rates after the filter cartridge is installed in the device.
The inventors believe that there is room for improvement in filters used for gravity flow water filtration devices, such as water pitchers, carafes, and countertop tanks, and in the filters that are used for low-pressure systems (such as 30 psi or less). The inventors believe that embodiments of the invented solid profile filters or “filter blocks” may be effective for said gravity flow or low-pressure systems, and/or for a wide variety of applications other than gravity-flow and low-pressure systems. Preferred embodiments of the invented apparatus and methods may satisfy the needs of many filtration applications and flow schemes by providing filters of improved flow distribution, flow rate, contaminant reduction/removal, performance consistency, and/or durability.
In a first group of embodiments, the invention comprises a solid profile filter block comprising multiple sub-blocks, each of said sub-blocks comprising filter media walls surrounding and defining a cavity for receiving fluid, and each of said sub-blocks being connected to at least one other of said sub-blocks by filter media of which the filter block is made. The invention may also comprise methods of making and/or using said solid profile filter block.
In a second group of embodiments, the invention comprises a solid profile filter block comprising multiple sub-blocks, each of said sub-blocks comprising filter media walls surrounding and defining a cavity for receiving fluid, and each of said sub-blocks being connected to at least one other of said sub-blocks by adhesive, polymeric binder, melting and re-solidification of binder already present in said sub-blocks, and/or other direct attachment of a given sub-block to another sub-block. Direct attachment in this second group of embodiments does not include clamping, engaging, or fastening a given sub-block to another sub-block by filter housing components, clamps, or fasteners.
In each of the first and second groups of embodiments described above, the multiple-sub-block filter block may comprise a main body of filter media with multiple cavities provided therein (whether or not the main body also comprises external indentations/gaps/spaces that are described later in this disclosure). The main body of the filter block, therefore, may be described also as a multi-core filter block, wherein the main body has been “cored” in multiple locations by removal of material or molding of the main body to have the cavities.
In each of the first and second groups of embodiments described above, the preferred filter blocks each comprise multiple sub-blocks may be formed by providing multiple internal cavities in a filter block and also at least one external indentation, wherein each of said internal cavities and said external indentation extends deep into the block. The cavities will be understood to be extremely large compared to interstitial voids of the media, and large compared to imperfections or other irregularities in the main body of the filter block. As described later in this disclosure, the indentation(s) for molded filter blocks are frequently in the bottom of the filter block for easier removal from the mold, but indentations (including gaps, spaced, or recesses) may also be in other portions/surfaces of the filter block.
Preferably, the indentation(s) extend(s) along at least ⅓ of the adjacent sub-block, and, more preferably, ⅓ up to ⅞ along adjacent sub-block. Thus, when considering a filter block wherein the sub-blocks extend along substantially the entire filter block, it is preferred that at least one indentation extend into the filter block to a depth equal to about ⅓-⅞ (and more preferably ½-⅞) of the relevant filter block dimension. For example, if the indentation extends axially into the filter block, it is preferred that the indentation depth be equal to ⅓-⅞ of the axial length of the filter block. For example, if the indentation extends radially into the filter block, it is preferred that the indentation depth be equal to ⅓-⅞ of the diameter of the filter block. By extending deep into the block, said cavities and indentation(s) may provide access deep in the block for fluids flowing into or out of the filter block. In an inside-out flow scheme, the multiple internal cavities allow inlet fluid to flow deep inside the filter block to access the media of the sub-blocks, and said at least one external indentation allows outlet fluid to be collected from the sub-blocks in region(s) between the sub-blocks. In an outside-in flow scheme, said at least one external indentation allows inlet water to reach each sub-block from region(s) between the sub-blocks, and the multiple internal cavities allow outlet fluid to be collected from the sub-blocks deep inside the filter block. The internal cavities may comprise D-shaped, circular, triangular, polygonal, or other shapes in cross-section or in end-view. Said at least one external indentation may comprise one or more slots, holes, cross-shaped slots, or other recesses, gaps, or spaces.
Said at least one external indentation is provided in the outer surface of the block to separate portions of the sub-blocks to provide a space between exterior surfaces of said portions of the sub-blocks (these particular exterior surfaces being those that “face” the exterior indentation) for fluid access out of or into said sub-blocks from regions at or near the central axis of the filter block or other regions of the sub-blocks not at the outer perimeter/circumference of the filter block. This way, all or substantially all of the filter media of each sub-block is accessible to fluid for filtration, rather than solely the media near the outer perimeter/circumference of the filter block.
Said first group of embodiments, including those which comprise both multiple internal cavities and at least one external indentation, are preferably made in a molding process or other process that forms multiple of the sub-blocks, or preferably all of the sub-blocks, at the same time. However, such molding or otherwise forming many of these preferred embodiments poses particular problems due to the preferred sub-block structure and the deep penetration of the cavities and indentation(s) into the filter block. Unless special adaptation is made in many embodiments, blemishes, holes, torn or destroyed sub-block walls, and/or other imperfections in the block may occur during separation of the filter block and the mold/tools. As a filter block with uniform flow distribution is an important object of these embodiments, such imperfections are usually not acceptable. Therefore, the inventors have provided adaptations in the block shape, to allow for proper removal of the block from the mold or other forming tools. The adaptations may include orientation of the sub-blocks to be “clustered” around a central axis, shape and diameter of the cavities and indentation(s) being adapted to minimize thin portions extending transverse to the direction in which the filter block is removed from the mold, and tapering/slanting of the surfaces of the block, including the outer perimeter surfaces, and/or the internal cavity surfaces, and/or the external indentation surfaces. These adaptations allow many embodiments of the filter blocks, including all of its sub-blocks, to be made in a single mold at one time. These adaptations allow various embodiments to achieve the objectives of a relatively large volume of media in a small “package” (small housing, and small “footprint” inside a water filtration pitcher or other device), with a low pressure drop, good flow distribution, coupled with durability and performance consistency.
In said second group of embodiments, including those which comprise both multiple internal cavities and at least one external indentation, some or all of the sub-blocks may be molded or formed in different molds, at different times, and/or by different processes, followed by direction attachment of the sub-blocks to one or more adjacent sub-blocks. By using direct attachment, rather than housing components, clamps, or fasteners, to attach sub-blocks to each other, there is little or no material between the sub-blocks (for example, only glue, adhesive, and/or binder). This direct attachment, because space between the sub-blocks is not being taken up by housing components, clamps, or fasteners, also allow various embodiments to achieve the objectives of a relatively large volume of media in a small “package” (small housing, and small “footprint” inside a water filtration pitcher or other device), with a low pressure drop, good flow distribution, coupled with durability and performance consistency.
The invented solid profile filter blocks may feature many different overall filter block sizes and shapes, and the multiple sub-blocks of the filter block may feature many different sub-block sizes and shapes. The preferred filter blocks may be considered three-dimensional rather than sheet-like, plate-like, or generally two-dimensional. Also, the preferred blocks are of dimensions such that they are not to be considered “pleated” or “corrugated” sheets or plates.
The filter blocks of the preferred embodiments comprise activated carbon particles/granules, binder particles, and optional additives, that are formed into said multiple sub-blocks. The preferred optional additives are metals removal additives, for example, lead sorbent/scavengers such as Alusil™ or ATS™, or arsenic removal additives. Some embodiments of the invented filters may be effective in removing both soluble and/or particulate lead from water. Optionally, instead of, or in addition to, carbon particles/granules, activated carbon fibers may be used with binder to form the solid profile. Also, other filtration or treatment media may be used, in place of or in addition to, activated carbon granules or fibers.
The opening of each internal cavity may be located at or near a common first axial end, and the sub-blocks preferably extend from that common end generally parallel to each other, and preferably clustered around, or arranged symmetrically around, the center axis of the block rather than on a single plane. In such embodiments, inlet or out fluid (depending on whether the application is an inside-out or an outside-in flow scheme) would enter or leave said multiple cavities at the same or about the same time at or near the time of entering or exiting the filter block. One or more external indentations may be located at or near said central axis of the block, at the opposite, second axial end, for separating the sub-blocks at or near said second axial end. Such configurations may be provided, for example, by molding or otherwise forming said sub-blocks in a single, unitary filter block, or by direct attachment of the sub-blocks into a single filter block.
Alternatively, other embodiments may include a single internal cavity that, farther along the axial length of the filter block, branches into multiple cavities. In such embodiments, an external indentation will typically be provided in the region of the filter block comprising the branching into multiple cavities. Such filter block embodiments may be described as comprising multiple sub-blocks in a portion of the filter block, rather than the filter block being formed entirely or substantially entirely of said sub-blocks. In such embodiments, inlet or outlet fluid (depending on whether the application is an inside-out or an outside-in flow scheme) would enter or leave said multiple cavities at a time different from the fluid entering or leaving the filter block, as the residence time in the filter block would comprise a period of the fluid residing in the single cavity region of the filter block.
While other sub-block and internal cavity arrangements may be included in the invention, it is preferred that there is some symmetry along the flow path so that fluid entering one of the sub-blocks will be filtered/treated the same or very similarly to fluid entering others of the sub-blocks. Therefore, it is preferred that the filter block comprise a plurality of sub-blocks that are symmetrically disposed relative to an inlet port or inlet distributor for parallel flow through the sub-blocks, and it is preferred that the sub-blocks comprise the same or similar amounts and types of media.
The above shapes and forms, and other shapes and forms still within the scope of the invention, will become apparent to the reader after review of this Description, the drawings, and the claims.
Objects of the preferred embodiments include maximizing the volume of a solid profile filtration media in a given cartridge, housing, or “package” total volume, while providing good contact between the fluid being filtered/treated and said solid profile media and providing low pressure drop, for high contaminant reduction and good flow rates. Embodiments of the invented multiple-sub-block solid profile filter blocks achieve some or all of these objects.
The preferred filter blocks may be considered three-dimensional filters, rather than being sheet or panel filters. Multiple internal cavities and preferably one or more external indentations allow water or other fluid to flow deep into/inside the three-dimensional filter block, to preferably access all or substantially all of the media of the each sub-block. The indentation(s), therefore, tend to extend into the filter block at or near a central region of the filter block, to provide fluid access space between the sub-blocks. The indentation(s) may take the form of slots, holes, recesses, or other spaces or gaps provided between the sub-blocks along a substantial portion of the sub-blocks. By providing these structures and adaptations, the preferred embodiments prevent there being significant unused zone(s) of media between the internal cavities, wherein such zone(s) of media would be “unused” because they would have no effective fluid inlet or outlet and would take up space within a filter cartridge without contributing significant filtration/treatment capability. This way, substantially all of the filter media of a sub-block is accessible to fluid for filtration/treatment, rather than just the media near the outer perimeter/circumference of the block.
Referring to the Figures, there are shown multiple, but not the only, embodiments of the invented solid profile filter blocks. Embodiments are portrayed wherein the opening of each cavity is located at a common first axial end, and the sub-blocks extend from that common end generally parallel to each other but preferably clustered around, or arranged symmetrically around, the center axis of the block rather than on a single plane. Also, embodiments are portrayed wherein a single cavity branches, farther along the axial length of the filter block, into multiple cavities. The opening of a single cavity may be located at a first axial end of the block, with the multiple cavities beginning at some point or points along the length of the block, and the closed ends (or capped ends) of the multiple cavities typically lie at or near the second axial end opposite the single cavity opening. One or more external indentations, gaps, or spaces, may be located, for example, at or near said central axis of the block at said second end, for separating the sub-blocks at or near said second end. In each of these types of multiple-sub-block configurations, it may be noted that the internal cavities comprise a closed/capped end, so that fluid flow may not flow through any of said cavities to exit the filter block without flowing through at least a portion of the filtration/treatment media, that is, without flowing through a wall of media. The closing or capping may comprise, for example, closing an end of a cavity with a media wall or with a portion of the filter cartridge housing or with filter internals such as a plate or other sealing member.
Alternatively, although not portrayed in the drawings, the inventors envision that embodiments of the invention filter blocks with a first set of multiple cavities at one end of the block, branching into different numbers or shapes of multiple cavities of a second set of said cavities generally midway along the length of the block. The openings of the first set of multiple cavities may be located at a first axial end of the filter and the closed or capped ends of the second set of cavities is typically at the opposite end of the filter block. Thus, embodiments of the invention may include significant branching of internal cavities, preferably with external indentations providing space/gaps between the sub-blocks at least at said second end of the filter block between the sub-blocks of the second set of cavities for separating the sub-blocks at or near the second end.
Thus, one may see from the above examples of internal cavities, that the multiple-sub-block form of the preferred embodiments may include, for example: a filter block that has multiple-sub-block filtration units extending all along the filter block length; a filter block with a first axial end region that comprises a single filtration unit (which itself may be considered a sub-block), transitioning to a middle or second axial end region comprising multiple sub-blocks; or a filter block with a first axial end region comprising multiple sub-blocks transitioning to middle or second axial end region comprising different multiple sub-blocks. The inventors envision that the preferred filters will have as few as two sub-blocks up to about 10 sub-blocks, but that it is more likely that filters of 2-5 sub-blocks will be effective in terms of quality control during manufacture and durability of the product. In each case, the preferred sub-blocks are integral with each other and/or directly attached to each other, so that neither housing nor casing components, nor internal filter cartridge components (such as are typically made of plastic or metal), nor clamps, are necessary to hold the sub-blocks together and, therefore, so that preferably none of these housing/casing/internals components/clamps are present between the sub-blocks. This way, preferably none of said housing/casing/internals components/clamps take up space inside the filter block.
The overall shape of the invented filter block may or may not be cylindrical (may or may not be round in cross-section and/or end-view) and, instead may be square, oval, triangular, or other shapes in cross-section and/or in end-view. The preferred filter blocks may be considered three-dimensional solid profiles, and may be described as having three dimensions that are on the same order of magnitude and/or may be described as being substantially non-planar or substantially non-sheet-like. For example, the preferred embodiments may be dimensioned to have an axial length within the range of ⅓-10 times the diameter of the filter block (more preferably ⅓-5 times the diameter, and most preferably 1-5 times the diameter). For these calculations, because many of the blocks are tapered in diameter, the largest diameter of the block, may be used. In non-cylindrical blocks, the axial length is preferably within the range of ⅓-10 times the width (more preferably ⅓-5 times the width, and most preferably, 1-5 times), and within the range of ⅓-10 times the depth (more preferably ⅓-5 times the depth, and most preferably, 1-5 times the depth).
Also, the shape of each of the filtration sub-blocks may be cylindrical, conical, or square, oval, triangular, or other shapes in cross-section and/or end-view. Each sub-block comprises a media wall that preferably surrounds at least four sides, and preferably five sides, of a cavity, which may also be called an internal hollow space in the filter block that may be placed in fluid communication with a fluid inlet to the filter cartridge or a fluid outlet from the filter cartridge. In other words, multiple media walls connect to or are integral with each other, so that each cavity is surrounded on four sides and, optionally, at one of its ends by the media wall. The media walls defining the sub-blocks preferably do not connect to each other all the way to the end of the block, but are, instead, preferably spaced apart along at least a portion of their lengths by the external indentation(s). Said indentation(s) may be provided by slots, holes, or other shapes of external indents, recesses, spaces or gaps between significant portions of the sub-blocks, including those purposely made in the molding process or other methods of making an integral filter block, and including those purposely left between the sub-blocks during direct attachment of sub-blocks to each other.
The preferred configurations include at least one end of each cavity being closed, preferably by a media wall that extends radially. This radial filter wall has a thickness sufficient to close, and, in effect, to “seal” each cavity, and/or to properly filter any fluid that passes through it. With the radial filter wall at least as thick as the axial filter walls, the fluid will tend to flow radially through the generally-axial filter walls, but, if the fluid does flow axially through the radial filter wall, the fluid will be appropriately filtered. In most embodiments, the cavity walls that create the inside surface areas do not protrude through the entire length of the block shape and so the radial filter wall, instead of a housing or internals plate, cap, or seal, serves to close one end of the cavities. In less-preferred embodiments wherein the cavities protrude through the entire length of the block shape, an additional sealing plate, cap, or other seal would be needed to maintain radial flow through the axial filter walls.
Referring specifically to Figures, there are shown several, but not the only, embodiments of the invented multiple-sub-block filter block, which may be compared to the prior art hollow, cylindrical filter block in
The filter block 10 in
A lip, depression, or other ring structure 26 preferably surrounds the top end of the block, as a recess for receiving adhesive (G) for sealing the top end of the filter to a cartridge housing component, thus, preventing water from bypassing around the top end of the filter. The block structure, combined with the adhesive or other seal, may eliminate the need to place a plastic plate at the top end of the filter that is separate from the cartridge housing. This way, water flow may be controlled, for example, in the case of inside-out flow, the water enters only at the cavities openings 16 and flows generally radially through preferably all the generally axial block walls (illustrated as 31, 32, 33, 34 in
The block in
The filter block 200 of
In cross-section, as viewed along line 2F-2F, one may see just two of the sub-blocks 202, 204 and just two of the cavities 212, 214. The block 200 comprises an opening/space between the sub-blocks (channel 220, an example of an external indentation) that allows water access between the sub-blocks, preferably either to reach the external surface of the sub-block portions “facing” each other for flow outside-in even in the area between the sub-blocks, or for water collection between the sub-blocks after inside-out flow out of the sub-blocks.
Block 200 in its preferred (but not the only) version and size has a major outside diameter of about 1.95″, a length of about 3″, a minimum wall thickness of about 0.260″, a volume of about 5.6 cubic inches, and a surface area substantially increased by the interior cavities 211, 212, 213, 214, and channel 220.
Block 300 in
Block 300 in its preferred (but not only) version and size has a major outside diameter of about 1.95″, a length of about 3″, and a minimum wall thickness of about 0.260″, a volume of about 6.31 cubic inches, and a surface area substantially increased by interior cavities 311, 312, 313, and exterior cavity 320 (slot portions 321, 322, 323).
Block 400 in
Block 400 in its preferred (but not only) version and size has a major outside diameter of 1.95″, a length of 3″, and a minimum wall thickness of 0.260″, and a volume of 6.42 cubic inches, and a surface area substantially increased by interior cavities 411, 412, 413, and 414, and exterior cavity 420 (slot arms 421, 422, 423, 424).
The preferred filter blocks of the invention, on the other hand, have additional cavities, cavity surfaces, and indentations/spaces/gaps that increase fluid-accessible surface area. The multiple-sub-block filter block shapes according to many embodiments of the invention will increase inlet or outlet surface area (and preferably both) for a given volume of activated carbon material and for a given filter cartridge volume, housing volume, or “package” volume. An important design feature, for a filter cartridge in a gravity-flow water pitcher or tank for example, is to minimize the total space that a cartridge or filter housing takes up (also called the filter “package” volume) inside the pitcher or tank. Therefore, embodiments of the invention that minimize the package volume, while providing excellent filtration performance and life and good flow-rates, will be beneficial for said pitcher or tank applications.
Many, but not all, embodiments of the multiple-sub-block sold profile filters use activated carbon and thermo-set binder, and the preferred proportions may range from about 5 up to about 70 weight percent binder, and 95 down to about 30 weight percent activated carbon plus additives. More preferably, many embodiments comprise 10-50 weight percent binder and 90 down to 50 weight percent activated carbon plus additives.
An especially preferred composition, for example, for gravity flow or low-pressure filter blocks according to embodiments of the inventions is: 30-50 wt-% binder(s), 28-52 wt-% powdered or granular activated carbon, and 18-22 wt-% lead removal media, wherein the total of the binder, activated carbon and lead removal media equals 100-%. Filter blocks, in the shape represented by
In order to form the media components into the solid profile, a mixture of the media components and binder(s) may be placed in a mold, and may be compressed with a piston or weight on the mixture, for example, and heated to make the binder tacky enough to stick to the media particles, thus, holding them together in a solid profile when cooled. Typically, heating in a 400-500 degree F. oven for about 30 minutes will effectively heat the mixture to reach the desired amount of binder tackiness. The preferred, but optional, compression may take place before heating, during heating, and/or after heating. Compression that reduces the volume of the mixture about 10-20 percent is preferred, but this may vary and may extend to a greater range (for example, 10-40 percent) or lesser range of compression. The mixing of components may be done by various methods, with the preferred result being that the binder is interspersed between the other components for effective connection of the components in a solid profile.
Many binders may be used, for example, thermoplastic binder, thermo-set binder, polyolefins, polyethylene, polyvinyl halides, polyvinyl esters, polyvinyl ethers, polyvinyl sulfates, polyvinyl phosphates, polyvinyl amines, polyamides, polyimides, polyoxidiazoles, polytriazols, polycarbodiimides, polysulfones, polycarbonates, polyethers, polyarylene oxides, polyesters, polyarylates, phenol-formaldehyde resins, melamine-formaldehyde resins, formaldehydeureas, ethyl-vinyl acetate copolymers, co-polymers and block interpolymers thereof, and derivatives and combinations thereof.
In order to minimize the amount of carbon or carbon plus additive surface area covered/blocked by binder, preferred binders exhibit less than a 5 g/min melt index, and more preferably less than a 1 g/min melt index by ASTM D1238 or DIN 53735 at 190 degrees C. and 15 kilograms. Particularly preferred binders have a melt index (ASTM D1238 or DIN 53735 as above) of less than or equal to 0.1 g/min. Binders from these ranges, and especially from the less than 1 g/min melt index group and the less than or equal to 0.1 g/min melt index group, may be selected that become tacky enough to bind the media particles together in a solid profile, but that maintain a high percentage of the media particle surface area uncovered/unblocked and available for effective filtration. Further, the selected binders preferably leave many interstitial spaces/passages open in the solid profile; in other words, it is desirable to have the binder not completely fill the gaps between media particles. A high amount of porosity is desirable, and, when combined with the high amount of “bulk” surface area for the block (bulk surface area meaning the exposed surfaces of the block, including the cavities and preferably the indentations described above), the preferred embodiments are effective in delivering fluid to the media of the block, effective in fluid flow through the porous block, and effective in fluid flow out of the media in the block.
Embodiments of the multiple-sub-block solid profile blocks may be used in liquid filtration applications and also in air or other gaseous material filtration applications. While the filter blocks in the drawings, and the terminology used herein, are shown or described in terms of “up” and “down,” the filters are not limited to the orientations drawn; various orientations, housings, internals, and flowschemes may be used, as will be understood by one of average skill after viewing this Description and the Drawings.
While preferred examples are given above, various other sizes and types of media components may be used, and the invention is not necessarily limited to filter blocks comprising activated carbon. Alternative media may be found that, because of its porosity and/or contamination removal attributes, may be used in the multiple-sub-block shapes of the invention, as a supplement or additive to, or instead of, activated carbon. Further, there may be filtration or treatment media that may be formed in some or all of the filter block shapes of the invention that do not require binder to connect granules or powder.
Although this invention has been described above with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to these disclosed particulars, but extends instead to all equivalents within the broad scope of the following claims.
This application claims priority of Provisional Application Ser. No. 60/846,162, filed Sep. 20, 2006, the entire disclosure of which is incorporated herein by this reference.
| Number | Date | Country | |
|---|---|---|---|
| 60846162 | Sep 2006 | US |
