Patent Grant
12090573
The invention generally relates to fluid treatment tanks and, more particularly, to a tank that has a fluid-permeable distributor plate and that can be easily manufactured and assembled. The invention additionally relates to such a distributor plate and to a method of making a fluid treatment tank including such a distributor plate.
Fluid-permeable plates, generally known as “distributor plates,” are widely used in a variety of fluid treatment tanks. Typical of these tanks are known as “pressure vessels” in which the fluid being treated is pressurized, albeit usually at a low pressure such as residential water line pressure. One such tank is a pressure vessel known as a “resin tank” of a water treatment system. The typical resin tank is a hollow cylindrical structure the interior of which defines a resin bed configured to hold “resin” and water or another liquid therein. The resin may be provided in the form of a plurality of plastic, e.g., polystyrene, beads. The resin bed is separated from the bottom of the tank by a slotted, perforated, or otherwise fluid permeable distributor plate that permits bidirectional fluid flow therethrough, but which prevents resin from falling through the distributor plate. A riser tube may be centrally positioned within the tank. The typical riser tube extends from the distributor plate to an upper opening in the tank through which treated liquid exits the resin tank. The tank may include a blow-molded plastic tank liner reinforced by an outer layer of fiberglass wrap.
Some pressure vessels have distributor plates mounted well-above the bottom of the tank so as to permit a single tank to contain two or more diverse treatment media. Some of upper plates are located in the vicinity of the vertical center of the tank and thus as known as “mid-plate distributor plates” or simply “mid-plates.” Some tanks contain two more such plates located well-above the bottom of the tank in a vertically-spaced relationship. For the sake of conciseness, all such plates are referred to herein as “mid-plates”, it being understood that the plate need not be located at or near the center of the tank. These mid-plates usually include a cylindrical outer surface that is spin-welded to the interior of the tank's plastic liner. Such plates are described, for example, in U.S. Pat. Nos. 7,901,576 and 8,382,994 to Enpress.
Spin welding involves imparting relative rotation to the components to be welded to generate sufficient frictional heat to the parts at their interface to melt the mating surface of one or both components. Once rotation stops, the material cools and solidifies and fuses the components together, forming a welded assembly. Spin welding necessarily involves holding the two components in close concentric engagement while they are rotated relative to one another. In the case of a water treatment tank mid-plate, spin-welding typically uses a rotating mandrel or spindle that engages the mid plate while the tank liner is held stationary. Spin welding a distributor plate to the interior of a tank liner is difficult or impossible unless the tank liner is open near the plate so as to allow insertion of the mandrel axially into the tank. The Enpress patents discussed herein propose first forming the tank liner, then cutting the tank liner apart in sections to provide an open end near the mid plate, then spin-welding the mid plate to the inner surface of the tank liner, then rejoining the tank liner sections, presumably by thermally bonding them together. The resultant process is time-consuming and equipment intensive. It also risks loss of tank integrity where the cut tank liner sections are rejoined if the welds are imperfect. It also risks misalignment of the rejoined sections unless care is taken to maintain concentricity of those sections during the rejoining process, a condition that can be difficult to meet given the tendency of the liner to become out of round during handling.
The inventor has realized that the need to section tank liners theoretically could avoided by laser welding the tank liner and distributor plate together. Laser welding involves directing a laser beam though a first material that is relatively transparent to the beam to a second material, that is relatively absorbent, so as to heat the second material sufficiently to melt and fuse it to first material upon subsequent cooling. Since the weld energy is imparted through the transparent outer component, that component need not be open in the vicinity of the inner component to accommodate a rotating mandrel or spindle. However, laser welding is similar to spin welding to the extent that requires that the components being welded be held in close engagement with one another during the laser welding process. The inventor has recognized that, in the case of treatment tank mid plate or other distributor plate, incorporating any measures into a welding system that clamps the plate to the tank liner or otherwise holds the plate and the tank liner in engagement with one another would have operate from an open end of the tank liner—just as with a spin welder—negating a major potential benefit of laser welding over spin welding.
The need therefore has arisen to provide a mechanism and/or process for holding an outer peripheral surface of a mid-plate or other distributor plate closely adjacent an inner peripheral surface of a water treatment tank preparatory to and during a laser welding process.
The need additionally has arisen to provide a mechanism and/or a process for welding a distributor plate in a water treatment tank without having to leave an end of the tank adjacent the distributor plate open during the welding process.
The need additional has arisen to provide a water treatment tank with welded distributor plate and a seamless tank in the vicinity of the distributor plate.
In accordance with a first aspect of the invention, one or more of the above-identified needs is met by providing a fluid treatment tank comprising a tank at least one distributor plate that is configured to support a bed of a fluid treatment media. The thank has an at least generally cylindrical inner surface, and at least one distributor plate received in the tank and configured to separate the bed from a lower end of the tank. The distributor plate has an upper surface, a lower surface, and an outer peripheral surface. The upper surface forms a support surface for fluid treatment media. A plurality of fluid permeable openings are formed through the distributor plate from the upper surface to the lower surface for the passage of a liquid being treated by the treatment media. The outer peripheral surface of the distributor plate is laser-welded to the inner peripheral surface of the tank.
In order to facilitate welding of the distributor plate to the tank, the outer peripheral surface of the distributor plate may have a biasing mechanism that biases the outer peripheral surface of the distributor plate against the inner peripheral surface of the tank.
The distributor plate may be formed of two or more components including an inner fluid permeable disk and an outer ring that supports the disk in the tank. The biasing mechanism may include a plurality of peripherally-spaced resilient fingers extending axially and radially away from a circular base of the support ring into engagement with the inner peripheral surface of the tank liner, each of the fingers having a base connected to the base of the ring and having a free end. The fingers may be spaced from one another at the free ends thereof, in which case a peripheral seal may extend outwardly from the base of the ring and seal against the inner peripheral surface of the tank beneath the free ends of the fingers. Each of the fingers may be curved along at least a majority of a length thereof and have an apex between the base and the free end thereof, the apex engaging the inner peripheral surface of the tank.
The tank may be made of a first material that is relatively transparent to laser light of a designated frequency, and at least an outer peripheral portion of the distributor plate may be made of a second material that is relatively absorbent to laser light of the designated frequency.
In accordance with another aspect of the invention, a method of forming a fluid treatment tank that has a distributor plate constructed at least generally as discussed above is provided. The method includes engaging an outer surface of the distributor plate with an inner peripheral surface of a fluid treatment tank, the distributor plate being configured to separate a bed of treatment media from a lower end of the tank. The distributor plate has an upper surface, a lower surface, and an outer peripheral surface, the upper surface forming a support surface for the fluid treatment media, and a plurality of fluid permeable openings are formed through the distributor plate from the upper surface to the lower surface for the passage of a liquid being treated by the treatment media. The method additionally includes laser-welding the outer surface of the distributor plate to the inner wall of the tank.
The engaging may comprise deflecting a basing mechanism on the distributor plate against the inner peripheral wall of the tank. In this eventuality, the engaging may comprise deflecting a circumferentially-spaced resilient fingers against the inner peripheral wall of the tank, the fingers extending radially and axially away from a base of an outer ring of the distributor plate. The distributor plate may have two or more components including an inner disk and an outer support ring of different materials and that includes the fingers.
Various other features, embodiments and alternatives of the present invention will be made apparent from the following detailed description taken together with the drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration and not limitation. Many changes and modifications could be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and in which:
Distributor plates constructed in accordance with the invention could be used in a variety of fluid treatment tanks configured to treat a variety of fluids using any of a number of media. Hence, while preferred embodiments of the invention now will be described in conjunction with a resin tank of a water treatment system, it is to be understood that the invention is not so limited.
Referring now to the drawings and, initially,
The tank liner 12 is made of a thermoplastic material such as blow-molded high-density polyethylene (HDPE). Liner 12 includes a generally cylindrical hollow body or wall 14 and upper and lower generally semi-spherical top and bottom ends 16 and 18. A feature 19 is integrally molded to the bottom end 18 of the liner 12 to rotationally couple the liner 12 to a filament winding machine during the fiberglass winding process The body 14 may have an internal diameter of, for example, 0.2 m to 1.0 m and a height of 0.5 m to 2 m. The illustrated example has an internal diameter of about 0.25 m. At least one distributor plate is provided in the liner 12 to define a treatment media area thereabove. The illustrated embodiment includes two such plates 20, 22 located near the bottom of the tank 10 and near the center of the tank 10, respectively and defining respective treatment media storage areas 24, 26, thereabove. Each distributor plate 20, 22 has fluid permeable slots or other openings formed through them that are sized and shaped to permit the relatively free flow of the liquid being treated while inhibiting or preventing the ingress of resin beads or other treatment media particles. Each area 24, 26 is configured to receive a bed or layer of a resin or other water treatment media during use of the tank 10. The resin may be provided in the form of a plurality of plastic, e.g., polystyrene, beads. The same or different treatment media may be received in each area 24, 26. The plate 20 is located near the bottom of the tank 10 and can be thought of as a “bottom plate” distributor. The plate 22 is located above the bottom dome 18 and thus can be thought of as a “mid-plate” distributor plate. A riser tube 28 extends vertically through the center of the tank 10 from the beneath the bottom plate 20, extends through center openings in both plates 20 and 22, and extends to or through an upper center upper opening 30 of the tank 10. An annular opening 32 is formed between the outer peripheral surface of the riser tube 28 and the perimeter of the opening 30. An inlet tube 34, positioned beneath the lower end of the riser tube 28, extends downwardly through the bottom distributor plate 20 in communication with the lower end portion of the tank 10. During a water treatment operation, untreated water enters the tank 10 from above through the annular opening 32, flows through the media areas 26 and 24 and the openings in the associated distributor plates 22 and 20 in succession, enters the inlet tube 34, and rises out of the tank 10 through the riser tube 28. This flow may be reversed, for example, during a treatment media generation cycle.
Pursuant to an implementation of the invention, one or both of the distributor plates 20 and 22 is mounted in the tank liner 12 by laser welding. In the illustrated embodiment, the mid-plate 22 is mounted in the tank liner 12 by laser welding, it being understood that, in other implementation\s, the bottom plate 20 and/or still other plates could be mounted in the tank liner by laser welding instead of or in addition to the mid-plate 20.
With additional reference now to
The inner disk 42 of the mid-plate 22 of this embodiment is made from unfilled or glass-filled Noryl® (Noryl® is a registered trademark of Sabic Innovative Plastics IP B.V.), which is family of amorphous reinforced materials in the form of modified polypropylene ether (PPO) resins that are formed from amorphous blends of PPO resin and polystyrene. The characteristics of Noryl and other possible inner disk materials, as well as the design and construction of such disks, are described in great detail in U.S. Pat. No. 10,106,434, the subject matter of which is hereby incorporated by reference in its entirety.
Referring particularly to
Referring now to
Still referring to
Suitable ring materials are those that are fusible to the tank liner 12 and that are relatively absorbent to laser energy of a wavelength found in laser welders. In the illustrated embodiment in which the tank liner 12 is made of a blow-molded, high-density polyethylene (HDPE) that is relatively transparent to laser energy. One such material is available from Exon Mobile under the PAXON® line and, more specifically PAXON BA53-055. The ring 40 also is preferably made from a high-density polyethylene (HDPE). A suitable material is available from LyondellBasell under the Petrothene® line and, more specifically, Petrothene LT570401. The ring material is impregnated with a material, such as carbon black, that renders it absorbent to laser energy. The laser energy absorbent material may be mixed with the HDPE resin prior to the injection molding process in a percentage sufficient to achieve the desired degree of melting during the laser welding process.
Referring briefly to
Referring to
Referring especially to
Still referring to
As mentioned above, the ring 40 is constructed in segments 40A, 40B, 40C so as to permit it to be formed around the disk 42 so as to capture the tongue 58 of the disk 42 in the groove 60 of the ring 40. Each segment 40A, 40B, 40C extends about 120 degrees around the plate 22. Adjacent segments could be connected to one another in any desired manner. As seen in
To mount the mid-plate 22 in the tank liner 12, the mid-plate 22 is pre-assembled by connecting the ring segments 40A, 40B, 40C to one another with the tongue 58 on the disk 42 captured in the groove 70 in the ring 40. The plate is then inserted into the cylindrical tank liner body 14 from one of the ends to the desired position. During this process, the fingers 80 deflect to permit axial movement of the mid-plate 22 relative to the tank liner body 14, albeit with some resistance. When the mid-plate 22 is properly positioned in the tank liner body 14, the fingers 80 hold the mid-plate 22 in place, with at least the apices 86 of the fingers 80 firmly engaging the inner peripheral surface of the tank liner body 14. As mentioned above, finger deflection also can accommodate signifying out-out roundness and/or other surface irregularities formed in the inner peripheral surface of the tank liner body 14.
The ring 40 then is laser welded to the tank liner body 14 using a laser welder that transmits laser energy through the tank liner body 14 from the outside. A laser suitable for this process is commercially available from Leister under the NOVALS™ Basic AT name. This laser has a 200W laser line and operates at a wavelength of 975 nm. The laser energy passes through the tank liner body 14 without appreciably heating it and is absorbed in the ring 40, heating at least the outer portions of fingers 80 to above their melting point. When the laser is turned off, the melted material cools, fusing the fingers 80 to the inner peripheral surface of the tank liner body 14 in the vicinity of the apices 86, and possibly elsewhere. The mid-plate 22 now is retained in place with sufficient force to support a bed of treatment media and to withstand the pressures encountered during typical use of the tank 10.
Because laser welding does not require the insertion of a rotating mandrel or comparable structure into the tank liner body 14, the tank liner body 14 need not be cut in the vicinity of the mounting location prior to the welding and rejoined after the welding operation. The tank liner body 14 instead can be seamless between the end domes 16 and 18. Fabrication therefore is substantially simplified when compared to the fabrication of a tank having a mid-plate installed by spin-welding. Tank dimensional reliability and tank integrity also are enhanced due to the lack of any seam along the cylindrical portion of the tank liner body 14.
Referring again to
Although the best mode contemplated by the inventors of carrying out the present invention is disclosed above, practice of the present invention is not limited thereto. It will be manifest that various additions, modifications and rearrangements of the aspects and features of the present invention may be made in addition to those described above without deviating from the spirit and scope of the underlying inventive concept.
For example, distributor plates and tanks as described herein could be used to store fluid treatment media other than resin and could be used to treat fluids other than water.
In addition, it is conceivable that the entire distributor plate, including the fingers or other biasing mechanism, could be formed of a single component formed from a material that can be laser welded to the tank liner, in which case the disk and the attendant openings might not have the same degree of dimensional stability as discussed above.
The scope of some changes to the described embodiments is discussed above. The scope of other changes to the described embodiments that fall within the present invention but that are not specifically discussed above will become apparent from the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4235340 | Clack et al. | Nov 1980 | A |
| 6379630 | Wilfong et al. | Apr 2002 | B1 |
| 6589491 | Peddicord et al. | Jul 2003 | B1 |
| 7354495 | Carter et al. | Apr 2008 | B2 |
| 7810670 | Carter et al. | Oct 2010 | B2 |
| 7901576 | Stolarik et al. | Mar 2011 | B2 |
| 7963400 | Stolarik et al. | Jun 2011 | B2 |
| 8110103 | Mormino et al. | Feb 2012 | B2 |
| 8382994 | Stolarik et al. | Feb 2013 | B2 |
| 10087086 | Schmall | Oct 2018 | B1 |
| 10106434 | Vaughan | Oct 2018 | B2 |
| 20060142451 | Yushina | Jun 2006 | A1 |
| 20080264847 | Emerson et al. | Oct 2008 | A1 |
| 20160311694 | Vaughan | Oct 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 0452042 | Oct 1991 | EP |
| 2469429 | May 1981 | FR |
| 2049134 | Dec 1980 | GB |
| Number | Date | Country | |
|---|---|---|---|
| 20200353564 A1 | Nov 2020 | US |
