Patent Description:
Hard water is a problem in many parts of the United States. Water is considered "hard" when it has a high concentration of dissolved minerals, specifically calcium and magnesium. While water is in the ground, it picks up soluble bits of whatever it passes through. While this can include contaminants that make the water unfit to drink, in many instances it simply means that the water contains minerals found in the earth. Of these, calcium and magnesium are of particular importance because they affect the water's ability to function in residential and commercial settings. These minerals make the water "hard.

Hard water is formed when water percolates through deposits of limestone and chalk which are largely made up of calcium and magnesium carbonates. Water hardness is determined by the concentration of multivalent cations in the water. Multivalent cations are positively charged metal complexes with a charge greater than <NUM>+. Usually, the cations have the charge of <NUM>+. Common cations found in hard water include Ca<NUM>+ and Mg<NUM>+. These ions enter a water supply by leaching from minerals, such as within an aquifer.

Typically, hard water classifications are shown using two common units: calcium in mg/l and grains per hardness. One grain of hardness equals <NUM>/l or ppm of hardness. Table I depicts water hardness classification as qualified by the Water Quality Association (WQA):.

Water containing calcium carbonate at concentrations below <NUM>/l is generally considered as soft or slightly hard; concentrations from <NUM>-<NUM>/l, moderately hard; concentrations from <NUM>-<NUM>/l, hard; and concentrations more than <NUM>/l, very hard.

Hard water used in appliances like washing machines, dishwashers, and the like, can significantly decrease their efficiency. For such appliances, water must be free from ions responsible for hardness. Ion-exchange water softeners have been implemented to remove hardness from water as a solution to this problem. Essentially, the ion-exchange water softeners work to remove the calcium and magnesium in the water.

The heart of a water softener is a mineral tank or water treatment vessel. It is typically filled with small polystyrene beads, also known as softener salts, resins, or zeolites. Generally, a large water treatment vessel containing softener salts is utilized for a water softener system. Water received in the household is filtered through the polystyrene beads, zeolite minerals, or the like, wherein calcium and magnesium ions are replaced with sodium ions. This is known as ion exchange. Ion exchange is the process through which ions in a solution are transformed to a solid which release ions of a different type but of the same polarity. This means that the ions in solutions are replaced by different ions originally present in the solid. This is a physical separation process in which the ions exchanged are not chemically altered.

Cation exchange water softeners remove the calcium and magnesium ions found in hard water by exchanging them with sodium (or potassium) ions. Once all the ions are fully exchanged, the water softener must then undergo a regeneration process to flush the system of excess ions and recharge with new sodium ions.

The polystyrene beads are designed to carry a negative charge. Calcium and magnesium in water both carry positive charges. When hard water is passed through the resin bed, the calcium and magnesium ions have a stronger positive charge than sodium ions. As a result, the calcium and magnesium have a stronger attraction to the negatively charged resin bed than the sodium. The sodium ion is then replaced on the resin bead with the calcium and magnesium taking its place. The sodium ion becomes unattached from the resin bed and moves to the solution taking the place of the calcium and magnesium ions. As a result, the less desirable calcium and magnesium ions are exchanged for more desirable sodium ions.

In this manner, calcium and magnesium ions in the water are transferred to the beads which in turn get saturated with the minerals. Once saturated, the beads will lose their ion-exchange capacity to remove magnesium or calcium ions. Thereupon, the resin beads must be regenerated to its sodium form with a salt or brine solution. During regeneration, the ion exchange resin is soaked with a strong solution of sodium chloride (brine) where the high concentration of the salt in the brine solution causes the calcium and magnesium ions in the resin beads to become dislodged. At the same time, the sodium in the brine solution again becomes affixed to the resin bead. After regeneration, the excess brine and hardness causing ions are rinsed to drain and the resin beads are once again ready to be used.

In operation, a water treatment vessel must accommodate this ion exchange interaction, and the ability to regenerate the resin bed. Generally, water treatment systems are designed to ensure that bed regeneration is effected prior to the point of exhaustion of the ion-exchange material.

In <CIT>, titled "WATER TREATMENT TANK," a water softening system is disclosed which is operative in a treatment mode to receive untreated water through an inlet port and pass treated water through an outlet port, and which is operative in a regenerative (backwash) mode. This treatment tank has a vessel with an interior cavity which is partitioned into a top headspace portion, a middle treatment bed space portion, and a bottom headspace portion, via the placement of a pair of distributor plates or filters mounted within the interior cavity to extend between the side walls thereof. The treatment bed space portion between the first and the second distributor filter is filled with an ion-exchange resin, and a portion of the top headspace portion is filled with a particulate filter medium supported by the first distributor filter. The distributor plates are mounted within the interior cavity of the tank, and spaced apart. The distributor plates are constructed of circular grating with spaced apart, concentrically circular wall portions. In this design, a mesh screen is required to extend through the circular grating in order to retain the ion-exchange resin within the treatment bed space. These screens are typically a polyester fabric. Thus, the distributor plates themselves are not designed to retain the ion-exchange material.

One consideration for a co-flow regeneration ion exchanger regardless of how the regeneration is established involves exhaustion of the resin bed. If the resin bed is permitted to become completely exhausted of its capability of exchanging ions, a single regeneration cycle will not be sufficient to establish the original capacity of the bed. Instead, several regeneration cycles often will be required.

Typically, a water softening system comprises an exchange medium in a water treatment tank which is in fluid communication with a brine storage tank for regeneration purposes. In this manner, the exchange medium may be subjected to backwashing with the brine. Document <CIT> discloses a distributor plate for a composite pressure vessel. The distributor plate includes a thermoplastic polymeric disk having a top side, a bottom side, a perimeter edge and a central opening. Radial slits are formed in the disk to define fluid flow passages through the disk between the central opening and the perimeter edge. The fluid flow passages through the disk are adapted to swirl fluid flowing through the disk from the bottom side to the top side around the central opening. Document <CIT> describes a distributor plate for a fluid tank such as a water softener pressure vessel. The distributor plate separates the resin bed from a lower end of the resin tank. The distributor plate includes a disk that is supported on an upwardly facing surface from below and that is restrained from upward motion by a weld bead located above an outer periphery of the disk. Document <CIT> discloses a distributor plate for a resin tank of a fluid treatment device such as a water softener. The distributor plate includes a central hub, an outer ring, a plurality of ribs extending between the hub and the ring and dividing the distributor plate into discrete segments, and a slotted plate connected therebetween.

In <CIT>, titled "COMPOSITE WATER TREATMENT VESSEL INCLUDING LIQUID DISTRIBUTOR PLATES," a water treatment vessel is taught having a thermoplastic liner, a reinforcing layer over the thermoplastic liner, and a distributor plate. Radial slits are formed in the distributor plate disc to define fluid flow passages through the disc between the central opening and the perimeter edge. Importantly, the fluid flow passages through the disc are adapted to swirl fluid flowing through the disc from the bottom side to the top side around the central opening. To achieve this swirling motion, each of the radial slits of the distributor plate is narrower in width at the top side of the disc than at the bottom side of the disc, with the fluid being bounded by a first longitudinal sidewall substantially perpendicular to the top side of the disc, and a second longitudinal sidewall having a concave profile in cross-section. In contrast, as discussed in detail below, the design of the distributor plate of the present invention does not desire nor promote a swirling fluid motion.

Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a water filter in which all the media resides above the lower distributor for effective utilization.

It is another object of the present invention to provide a uniform flow through the filter media in both flow directions to maximize media utilization.

A further object of the invention is to provide a means for up flow/counter flow regeneration which does not generate mixing or moving of the filter media to maximize media regeneration efficiency/utilization.

It is yet another object of the present invention to provide a method for producing a pressure vessel/device that incorporates the advantages of the present invention.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The above and other objects, which will be apparent to those skilled in the art, are achieved in the present invention which is directed to a fluid treatment vessel according to claim <NUM>.

The distributor plate top side includes a first plurality of chords traversing across the distributor plate in a first direction and a second plurality of chords traversing across the distributor plate in a second direction perpendicular to the first direction, the first and second plurality of chords forming the sidewalls of the cavities, and extending to the perimeter edge.

The perimeter edge forms the sidewalls of the cavities adjacent the perimeter edge.

The first plurality of chords has a cross-section of an isosceles trapezoid with a first chord base located below the distributor plate top side and internal to the distributor plate.

Each side of the isosceles trapezoid forming one of the sidewalls for the cavities, respectively.

The distributor plate bottom side includes a third plurality of chords traversing across the distributor plate in the first direction and a fourth plurality of chords traversing across the distributor plate in the second direction, the third and fourth plurality of chords extending to the perimeter edge.

The third plurality of chords each have a top side that forms the cavity base for the cavities.

The first and second plurality of chords may be integrally formed.

The third and fourth plurality of chords may be integrally formed.

The distributor plate includes a cylindrical sleeve extending from the central opening, the cylindrical sleeve in mechanical communication with the fluid transfer tube.

The third plurality of chords has a cross-section of an isosceles trapezoid with a base located below the distributor plate top side and internal to the distributor plate.

In a second aspect, the present invention is directed to a distributor plate according to claim <NUM>.

In a third aspect, the present invention is directed to a method of assembling a water treatment vessel according to claim <NUM>.

The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:.

In describing the preferred embodiment of the present invention, reference will be made herein to <FIG> of the drawings in which like numerals refer to like features of the invention.

In the present invention, a water filtration system provides for a housing having at least one type of filter media enclosed therein that internally supports at least one distributor plate. More specifically, the present invention is used in water softener applications. As depicted in <FIG>, a liner <NUM> of the water treatment housing or vessel forms (when assembled and combined with a structural overwrap layer) a composite pressure vessel that is preferably formed from two similar liner sections <NUM>, <NUM> attached at approximately the housing mid-section, and bonded or welded together so as to form a fluid-tight seal. The composite pressure vessel <NUM> is preferably comprised of a thermoplastic liner (tank) that is overwrapped with a reinforcing layer. The thermoplastic liner is typically formed of a polymer, such as a high density polymer (HDPE) liner. The liner halves are bonded together. The reinforcing layer is typically comprised of glass filaments and epoxy in a fiberglass mixture is then overwrapped on the liner. The composite pressure vessel <NUM> is depicted as a cylindrically shaped vessel formed from two symmetrical halves that are bonded at approximately the vessel's midpoint although other geometric configurations are possible, and bond points other than the vessel's midpoint are also possible, such that the present invention is not limited to a particular geometric configuration or a midpoint bond seal.

In the preferred embodiment, the tank top is dome-shaped and includes an insert, injection molded tank neck <NUM>. Similarly, the tank bottom is preferably also dome-shaped. In at least one embodiment, each domed-shaped portion is formed with a cylindrical shell portion that comprises the body of the tank top or tank bottom. The two halves are spin-welded together, and as shown in <FIG>, at an approximate mid-point of the vessel. Other means of attachment, such as laser welding, thermally bonding, and the like, can achieve a sufficient bond of the tank top and bottom.

The vessel is preferably constructed using a thermoplastic, polypropylene, or polyethylene liner, or other thermally formable/moldable plastic material, and may be extruded or injection molded. As depicted in <FIG>, the tank is a combination of two cylindrical bodies, each comprising the thermoplastic, polypropylene liner that when combined share the same central axis. In a preferred embodiment, the end portions of each cylindrical body are formed concurrently with the cylindrical bodies, that is, there are no separate end portions or end caps that would otherwise require additional welding.

In the present design, the bottom half of the injection molded tank has a distributor plate <NUM> inserted within it. Distributor plate <NUM> is situated on the bottom surface of the lower half <NUM> of vessel <NUM>. <FIG> depicts a cross-sectional view of vessel <NUM> depicting the placement of distributor plate <NUM>.

Distributor plate <NUM> has a diameter approximately equal to the inner diameter of the vessel <NUM> at a lower portion of vessel lower half <NUM>. A fluid transport tube <NUM> is held in place at a bottom end 20a by a center aperture or opening in distributor plate <NUM>, and extends at a top end 20b through tank neck <NUM>. Distributor plate <NUM> seats in a support structure <NUM>. Support structure <NUM> is preferably bowl- or domed-shaped on its bottom facing end to match correspondingly with the top inner surface of the domed-shaped bottom of the vessel lower half portion <NUM>.

<FIG> is a perspective, cross-sectional view of vessel <NUM> depicting the attachment of fluid transport tube <NUM> to the distributor plate / support structure combination (<NUM>, <NUM>). In the embodiment depicted by <FIG>, central aperture <NUM> includes a cylindrical sleeve <NUM> comprising a receiving tube segment for receiving fluid transport tube <NUM> at its bottom end 20a. Fluid transport tube bottom end 20a is slidably or threadably received by sleeve <NUM>, forming a fluid-tight seal. Support structure <NUM> may include posts <NUM> to provide structural bracing for distributor plate <NUM> at locations between its axial center and its edge.

<FIG> is a perspective, exploded view of vessel <NUM> depicting the assembly of the major components.

The distributor plate <NUM> for the composite pressure vessel <NUM> is preferably designed as a thermoplastic polymeric disc having a top side, a bottom side, a perimeter edge, and a central opening. Other materials may be used for the distributor plate provided the materials do not adversely interact with either the fluid or the filter media / resin bed material, and provide for a sufficiently robust structure to withstand the fluid and filter media / resin weight.

<FIG> depicts a partial, cross-sectional, perspective view of distributor plate <NUM>. The distributor plate is formed having a top plate portion I and a bottom plate portion II. These may be separate portions attached or placed together, or preferably integrally formed together. Top plate portion I and bottom plate portion II together form rows of upwardly facing wells for receiving and retaining filter media / resin on the topside of distributor plate <NUM>, and form narrow fluid passage slits or apertures <NUM> at the bottom edges of each upwardly facing well or cavity, slits <NUM> being situated at the interface of top plate portion I and bottom plate portion II. As discussed in further detail below, the base of well or cavity <NUM> is formed by a top surface of lower chord <NUM> of bottom plate portion II, that traverses the bottom plate portion II in a similar fashion, and direction, as upper chord <NUM> traverses the top plate portion I. The upper chord <NUM> and lower chord <NUM> are spaced apart in a direction outwards from the distributor plate center so that each lower chord <NUM> provides a floor or upwardly facing surface for the well formed by two adjacent upper chords <NUM>.

The upper surface of top plate portion I includes a plurality of chords <NUM> traversing across the circular distributor plate <NUM> in one direction, and a plurality of chords <NUM> traversing across the distributor plate <NUM> in a direction perpendicular to chords <NUM>, such that a lattice of upwardly facing wells or cavities <NUM> are formed. It is understood that the distributor plate, and thus the chords, may be formed from a mold, such as an injection molded construct, and as such the chords providing the lattice structure may be integrally formed with one another. Each set of adjacent chords <NUM> and adjacent chords <NUM> together form the sidewalls of upwardly facing wells or cavities <NUM> that are designed to receive and retain filter media / resin. In some instances, sidewalls of wells <NUM> at the outer periphery of the distributor plate are formed in part by edge <NUM>. Sidewalls formed by edge <NUM> are curved at approximately the radius of the distributor plate <NUM>.

As depicted in <FIG>, chords <NUM> have a cross-section of an isosceles trapezoid with base 30a at the bottom, and sides 30b,c that angle outwards, away from the respective chord's topmost edge, and downwards from the distributor plate top surface, such that each two adjacent chords <NUM> form an upwardly facing well or cavity <NUM> in the shape of an inverted isosceles trapezoid having its open-faced "base" or larger width portion at the top. In cross-section, each well or cavity <NUM> has a larger opening exposed to the top surface of distributor plate <NUM>, the width indicated by arrow A, and a smaller opening formed by the bottom (lower) angled ends of chords <NUM>, the width of the smaller opening indicated by arrow B.

Chords <NUM> form the end wall segments of cavity <NUM> except at the outermost reaches of the distributor plate, where a circumferential edge <NUM> forms an end wall segment or in some instances a curved sidewall segment for the wells lying on the outer periphery.

Chords <NUM> located in the bottom plate portion II have a similar cross-section as chords <NUM> of the top plate portion I, with the exception that the cross-section directional shape of chord <NUM> is inverted with respect to chord <NUM>, that is, the cross-section of chord <NUM> is an isosceles trapezoid with its base 40a facing upwards towards top plate portion I, and having sides 40b,c that angle inwards, from the respective chord's bottom most edge, and downwards from the distributor plate top surface, such that each two adjacent chords <NUM> form a downwardly facing well <NUM> in the shape of an isosceles trapezoid having its widest portion or "base" at the top. In cross-section, each well <NUM> has a larger opening exposed to the bottom surface of distributor plate <NUM>, and an opposing smaller opening formed by the top angled ends of chords <NUM>.

The base 40a of chord <NUM> has a width that is less than the width of the narrowest portion of well <NUM>, which is denoted by Arrow B, such that when the top portion of chord <NUM> (base 40a) is presented as the floor of well <NUM>, there remain narrow apertures or slits <NUM> between the bottom edge of each adjacent chord <NUM> (base 30a) and top edge of chord <NUM> (base 40a). Slits <NUM> are designed for fluid flow through distributor plate <NUM>, as denoted by directional arrows C.

<FIG> is a top perspective view of distributor plate <NUM> depicting rows of wells or cavities <NUM> exposed to the top surface of distributor plate <NUM>, the wells or cavities <NUM> presenting a rectangular aperture to the top surface, and forming inverted isosceles trapezoidal cavities separated by chords <NUM>. <FIG> is an exploded view of a portion of the distributor plate of <FIG>.

As noted above, chords <NUM> form the end wall segments of well <NUM> except at the outermost reaches of the distributor plate, where a circumferential edge <NUM> forms an end wall, segment or in some instances a curved sidewall segment, for the wells lying on the outer periphery.

<FIG> depicts a top view of distributor plate <NUM>. <FIG> depicts a bottom view of distributor plate <NUM>.

<FIG> is a sideview of the distributor plate support structure <NUM> with distributor plate <NUM> held therein. In this view, sleeve <NUM> can be seen above the rim of support structure <NUM>. Preferably, the bottom of support structure <NUM> is shaped to fit the inside bottom of vessel lower half <NUM>, both shown here as domed-shaped. Support structure <NUM> may simply be placed in vessel lower half <NUM> or secured thereto. <FIG> is a bottom perspective view of support structure <NUM>.

<FIG> depicts a top perspective view of the distributor plate <NUM> and support structure <NUM> assembly.

It is noted that the distributor plate may be molded as a single structure or formed from the attachment of top plate portion I to bottom plate portion II. Once the top and bottom disc portions are secured together, fluid flow passages or slits <NUM> are formed upon alignment of the alternating quadrilateral structures as shown in <FIG>.

Assembly of the vessel with the distributor plate and support structure is best described in reference to <FIG>. The distributor plate <NUM> is attached to support structure <NUM>. Support structure <NUM> includes a circumferential ledge extending radially inwards to seat a bottom portion of the outside edge <NUM> of distributor plate <NUM>. Fluid transport tube <NUM> is then inserted within sleeve <NUM> and the subassembly is placed within the vessel lower half <NUM>. Preferably there is no attachment of the subassembly to the vessel lower half <NUM>; however, a friction or snap fit attachment to the inner wall of the vessel may be performed, and is not precluded by the present invention. Vessel upper half <NUM> is then secured to vessel lower half <NUM> in a fluid-tight seal. Attachment may be performed by bonding or welding the halves together; however, the design is not limited solely to welding. Other airtight, watertight seals may be utilized. An outer covering is then applied to the assembled vessel, preferably a fiberglass covering <NUM>; however, the present invention is not limited to any specific protective outer covering.

<FIG> depicts a partial, cross-sectional view of the vessel upper half <NUM> with through-hole fitting <NUM> secured thereto without the epoxy/fiberglass outer wrap. In a first embodiment of the present invention, the top portion of the vessel includes through-hole fitting <NUM> presenting an aperture <NUM>. The through-hole fitting <NUM> is fitted and bonded to the vessel upper half <NUM>. The reinforced fiberglass layer need not be removed in order to form the aperture for insertion of the through-hole fitting <NUM>, and certainly not removed once the through-hole fitting <NUM> is secured in place. In this embodiment, the proposed design does not require the removal of the outer reinforced layer after the through-hole fitting <NUM> is attached.

The through-hole fitting <NUM> is preferably a glass-filled structure to match the liner material, such as HDPE/HDPE or polypropylene/polypropylene material (so that they melt and fuse together in the molding process), and which is subsequently wrapped within a high-density polyethylene (HPDE) liner <NUM>, wherein the HPDE liner encompasses a fiberglass wrapping.

Claim 1:
A distributor plate (<NUM>) for a water softener system comprising:
a top plate portion (I), a bottom plate portion (II), a perimeter edge (<NUM>), and a central opening (<NUM>),
said top plate portion (I) and bottom plate portion (II) together forming rows of upwardly facing wells or cavities (<NUM>) for receiving and retaining filter media on the topside of distributor plate (<NUM>) and forming narrow fluid passage slits (<NUM>) at the bottom edges of each upwardly facing well or cavity, the slits (<NUM>) being situated at the interface of top plate portion (I) and bottom plate portion (II),
said upward facing wells or cavities (<NUM>) are formed from a first plurality of chords (<NUM>) traversing across said distributor plate (<NUM>) in a first direction and a second plurality of chords (<NUM>) traversing across said distributor plate (<NUM>) in a second direction perpendicular to said first direction, such that said first and second plurality of chords (<NUM>,<NUM>) form sidewalls of said upward facing wells or cavities (<NUM>), and extend to a perimeter edge (<NUM>) of said distributor plate (<NUM>),
said bottom plate portion (II) including a plurality of downward facing wells or cavities (<NUM>) exposed thereon in a direction opposite said upward facing direction, said downward facing wells or cavities (<NUM>) are formed from a third plurality of chords (<NUM>) traversing across said bottom plate (II) in said first direction and a fourth plurality of chords traversing across said bottom plate (II) in said second direction, such that said third and fourth plurality of chords (<NUM>) form sidewalls of said downward facing wells or cavities (<NUM>), and extend to said perimeter edge (<NUM>), whereby each lower chord (<NUM>) provides a floor or upwardly facing surface for the well or cavity (<NUM>) formed by two adjacent upper chords (<NUM>),
said first plurality of chords (<NUM>) having a cross-section of an isosceles trapezoid (30a-c) with a first chord base (30a) located at a bottom and whereby sides (<NUM> b, c) angle outwards, such that each two adjacent chords (<NUM>) form an upwardly facing well or cavity (<NUM>) in the shape of an inverted trapezoid, said third plurality of chords (<NUM>) having a cross-section of an isosceles trapezoid (40a-c) being inverted with respect to chords (<NUM>), thereby with its base (40a) facing towards top plate portion (I) whereby two adjacent chords (<NUM>) form a downwardly facing well or cavity (<NUM>).