Patent Application
20130186824
1. Technical Field
This document relates to membrane filtration, specifically to a spiral cross flow membrane filtration device and process.
2. Background
Conventional configurations and schemes exist that try to improve cross flow velocity to reduce the propensity for fouling and scaling of membranes. However, these efforts are expensive, unreliable, and operationally problematic. Further, these efforts generally employ configurations not optimal to provide full cross flow coverage of the fouling prone membrane surfaces.
An example of such ineffective conventional configurations and schemes includes the application of turbulence generating feed water spacing media within the confines of spiral wound media. These efforts to try and improve fouling resistance of spiral wound membranes however have meet with little success simply because of the flow limitations inherent to the spiral wound membrane configuration. A further difficulty inherent to spiral wound membranes is the inability to effectively clean severely fouled membranes exasperated by the inability to expose the permanently rolled membrane material for physical cleaning.
These troublesome issues have lead to reconfiguration of membranes away from early spiral wound configurations.
For example, cassette packaging of linear, flat membranes has been introduced but has inefficiencies in flow distribution and associated inferior performance, as well as suffering from the required multiplicity of seals, and hence, severe problems associated with leakage.
As another example, circular flow patterns and associated circular membrane configurations have been presented. However, they suffer substantially from high pressure drop and, as a consequence of the geometrical configuration, ineffectively low cross flow velocity across the outer radii of the circular membranes. This is an especially inferior configuration since the outer radii encompasses the majority of the membrane surface area. This presentation accordingly has low velocity across the majority of the membranes resulting in high fouling problems.
As a further example, membrane surfaces have been mechanically spun. However, they encumber sealing problems inherent to rotating mechanisms within a pressured fluid environment. Further, these examples suffer from an inability to maintain an induced high cross flow relative velocity on the membranes due to induced swirl of the fluid surrounding the rotating membranes. The induced swirl substantially reduces cross flow and indeed, especially reduces the cross flow velocity to near zero at inward radii.
As still another example, multiple counter-rotating membrane disks have been presented. But they substantially complicated in design and are plagued with inherent sealing and mechanical failings.
As yet another example, other mechanically induced swirl cross flow manifestations have also been presented using spinning blades. These efforts suffer from complex, expensive and unreliable high load rotating seals. Also, the complexity of the mechanical design burdens this design with difficult and burdensome maintenance requirements. This design is further taxed by a high power requirement and accompanying high operating expense.
Finally, as still another example, configurations have been presented wherein a swirl is induced via entrained piping. This approach is burdened by the fluid dynamic burdens of the piping placement within the swirl pattern. Relative cross flow velocities and swirl path coverage are dramatically hindered by the presence of such piping as well. Furthermore, flow shadows on the membranes from the piping manifest as low cross flow velocity areas prone to unresolvable fouling presenting an inherent, serious flaw.
Thus, important and burdensome disadvantages of conventional membrane filtration processes are inefficiency, unreliability, operational difficulty, minimal durability, plugging, fouling and blinding associated with treating poor quality feed fluids with high solids content.
Aspects of this document generally relate to operational enhancement of membrane filtration processes, and specifically relate to a spiral cross flow membrane filtration device and process that reduces fouling and scaling by employing high velocity cross flow to minimize solids deposition upon the membrane surface. These aspects may include, and implementations may include, one or more or all of the components and steps set forth in the appended CLAIMS, which are hereby incorporated by reference.
In one particular aspect, a spiral cross flow membrane filtration device may include a large diameter hollow cylindrical vessel in the walls of which may be at least two tangentially oriented, but circumferentially opposing inlet slots or ports for feed fluid. Also suspended, longitudinally and central to the vessel, may be a compressed stack of alternating large diameter, two sided membrane covered plates and much small diameter spacers. The longitudinal center of the stack may contain multiple conduits to independently convey multiple fluids.
Particular forward osmosis implementations may include one or more or all of the following. A central conduit supplies a rich draw solution, another conduit removes a lean draw solution, and the third conduit provides reject drainage of a spent feed solution. The rich draw solution conduit conveys rich draw solution to flow basins underneath the membranes on the outer plate surfaces. Hollow interiors of the plates drain and convey permeate diluted lean draw solution from the membranes to the lean draw solution conduit for conveyance from the device and process. The reject conduit is open through the spacers to the gap between the membrane plates and conveys spent feed fluid from the process.
In another particular aspect, a process of spiral cross flow membrane filtration is disclosed. The process may include the steps of: conveying feed fluid at high velocity through one of the two tangentially oriented inlet slots or ports of the vessel, generating a large cyclonic swirl about the vessel and membrane plates; conveying the cyclonically motivated feed fluid radially into the spacers between the membrane plates, generating an inward spiraling high velocity flow across the membranes, inward flow providing angular acceleration and higher velocity across the membranes, high velocity across the membranes providing superior cleaning proficiency; conveying rich draw solution into the rich draw solution conduit, rich draw solution conveying from this conduit across the plates in contact with and under the membranes, osmotic pressure extracting permeate from the swirling feed fluid through the membranes, the rich draw solution diluting with the permeate; the diluted draw solution being internally conveyed in the plates, from the permeate dilution of the membranes to the lean draw solution conduit; the lean draw solution being discharged from the lean draw solution conduit; feed fluid lessened from permeate loss conveys through the spacers into the reject conduit, the reject conduit then discharging the permeate reduced feed fluid; the high velocity feed fluid to the vessel being periodically diverted between opposing inlet slots or ports, the cyclonic swirl about the vessel and membranes periodically reversing direction, flow reversal breaking loose streamlined detritus and other flow shaded debris, the membrane surface cleaning proficiency being enhanced.
The foregoing and other aspects and implementations of a spiral cross flow membrane filtration device and process may have one or more or all of the following advantages, as well as other benefits discussed elsewhere in this document.
The excellent attributes of a spiral cross flow membrane filtration device and process afford the trouble free application of all types of membrane filtration media and associated applications; coarse strainer, microfilter, ultrafilter, nanofilter, reverse osmosis and, especially, forward osmosis. The cleanliness and ease of service substantially advances the durability of membranes and minimizes the cleaning, flushing and associated maintenance burdens typical of conventional techniques.
Other advantages include: a) enhanced reliability, presenting minimal downtime for cleaning and service; b) minimizing chemical costs for cleaning and washing; c) maximizing membrane life and performance expectancy; d) enhanced flux rates and performance; e) lower pumping energy use requirements; f) elimination of pretreatment equipment capital and operating expense; g) the capability to treat fluids to higher levels of solids enabling increased product quantity and less waste; h) ease of membrane service, repair and replacement, especially in the field; i) higher membrane performance by maximizing membrane contact area subsequent to elimination of streamline and shadow solids deposition on membrane surfaces; j) superior membrane performance and durability solely through the employ of simple, membrane safe hydraulic flow cleansing processes; k) superior forward osmosis flux by employing full countercurrent flow regimes; l) continuous membrane filtration and heavy solids blowdown without the burdensome batch cleaning requirements of conventional membrane filtration processes; and m) true parallel contacting, minimizing the inefficiencies and losses associated with reduced gradient flux as burdens conventional series configurations.
The foregoing and other aspects, features, and advantages will be apparent to those of ordinary skill in the art from the DESCRIPTION and DRAWINGS, and from the CLAIMS.
Implementations will hereinafter be described in conjunction with the appended DRAWINGS (which are not necessarily to scale), where like designations denote like elements, and:
This document features a membrane filtration device and process that afford high efficiency solids removal, filtration and/or conditioning of liquids. The device and process purveys high quality, durable membrane treatment in liquid applications especially burdened by high suspended solids loading. The device and process conveys superior treatment for providing clean permeate liquid by means of pressured membrane filtration or liquid extraction by means of forward osmosis. Thus, there are many features of membrane filtration device and process implementations disclosed herein, of which one, a plurality, or all features or steps may be used in any particular implementation.
In the following description, reference is made to the accompanying DRAWINGS which form a part hereof, and which show by way of illustration possible implementations. It is to be understood that other implementations may be utilized, and structural, as well as procedural, changes may be made without departing from the scope of this document. As a matter of convenience, various components will be described using exemplary materials, sizes, shapes, dimensions, and the like. However, this document is not limited to the stated implementations and examples and other configurations are possible and within the teachings of the present disclosure.
A membrane filtration device and process will be described with respect to implementations in specific contexts, namely as a device and process for pressured membrane filtration and for forward osmosis treatment of highly solids laden fluids. Implementations of a membrane filtration device and process may also be applied, however, to other situations wherein sheet filtration or treatment is desirable. Furthermore, it should be appreciated by those skilled in the art that the conception and specific implementations disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure set forth in this document.
Membrane filtration device and process implementations employ the concept of cyclonic flow, conservation of angular momentum and geometrical influence to generate high cross-flow velocities upon the reject side of sheet membrane material. High cross-flow velocities scour solids and detritus deposits from the membranes, dramatically reducing operational maintenance, improving membrane performance and durability. The benefits provided are furthered by fashioning the device to impart periodic reversal of the cyclonic direction across the membranes; affording multidirectional cross-flow and the associated scouring enhancements, such as elimination of layering, stream line and shadow depositions.
There are a variety of membrane filtration device implementations.
In pressure filter implementations at least three fluid types partake in the device and process; feed fluid, permeate fluid, and reject fluid. Feed fluid is the fluid being treated often also referred to as the challenge fluid. Permeate is the fluid which passed through the membrane. In the case of coarse filtration permeate is also termed filtrate. Reject fluid is the residual fluid after permeate has been extracted from the feed fluid. These implementations accordingly have one fluid ingress as feed fluid and two fluid egresses as permeate fluid and reject fluid. Processing and handling of these three fluids are external to the present disclosure, subsequently not of significance herein.
In forward osmosis implementations at least four fluid types partake in the device and process; feed fluid, rich draw solution, lean draw solution, and reject fluid. Feed fluid is the fluid being treated. Rich draw solution provides the osmotic pressure across the membranes to draw permeate from the feed fluid to dilute the rich draw solution. Lean draw solution is rich draw solution diluted with permeate. Reject fluid is the residual feed fluid after permeate has been extracted. Such implementations may have two fluid ingresses, feed fluid and rich draw solution, and two fluid egresses, reject fluid and lean draw solution. Processes and handling of these four fluids are external to the present disclosure, subsequently not of significance herein.
Notwithstanding, turning to FIGS. 1 and 3-7 and for the exemplary purposes of this disclosure, a spiral cross flow membrane pressure filtration device is shown.
With reference to
Subsequent to pressured feed fluid, permeate flux penetrates the membrane surfaces of the plates 6 concurrent with the high velocity spiraling cross flow. The membrane plate assemblies 6 receive and convey the permeate from underneath the membranes toward one or more longitudinal permeate conduits 12 penetrating the stack core. Permeate conveys within the permeate conduits 12 to egress from the vessel 1.
Referencing
Referencing
Thus,
Low pressure in the central longitudinal reject conduit 10, communicated through the radial bridge ducts 214 of the spacers 8, educes centrally inward spiraling of the feed fluid across the membranes 124 covering the plates 116. Permeate issues from the feed fluid as it spirals past the membranes 124. The reject fluid radially conveys through the bridge ducts 214 of the spacer 8 passing into and through the longitudinal reject conduit 10 to egress vessel 1.
As
Turning to FIGS. 2 and 8-13 and for the exemplary purposes of this disclosure, a spiral cross flow membrane forward osmosis filtration device is shown.
With reference now to
One or more of the longitudinal conduit penetrations 11 within the stack ingresses rich draw solution which is conveyed underneath the forward osmosis membranes covering the sides of the plate assemblies 6. Osmotic potential extracts fluid from the adjacent swirling feed fluid as permeate through the membranes. The permeate dilutes and alters the rich draw solution passing underneath the membrane to a lean draw solution. The lean draw solution conveys from the plate assemblies 6 into one or more lean draw solution longitudinal conduit penetrations 13 within the stack and egresses from the vessel 1.
Referencing
Referencing
Thus,
Feed fluid spirals at high velocity radially inward between the plate assemblies in the region supported by the spacers 9 while imbuing pressured, shearing contact with the membranes 332 on the opposing faces of the coupled plate 316 assembly. Rich draw solution conveys through the rich draw solution conduit 11 of the spacers 9 entering the rich draw solution conduits 324 of the two opposing plates 316. The rich draw solution streams through the rich draw solution ducts 325 from the rich draw solution conduits 324 into the rich draw solution basins 321 underlying the membranes 332 on both sides of the coupled plate assembly. The rich draw solution spreads radially outward through the rich draw solution basins 321 exploiting osmotic pressure to extract permeate through the overlying membranes 332 from the adjacent spiraling feed fluid flow. The permeate dilutes the rich draw solution as it spreads radially outward in the rich draw solution basin 321 presenting a lean draw solution at the outer periphery of the basin 321. The dilute, now lean draw solution exits the rich draw solution basin through the lean draw solution return ports 328 at the outer periphery of the rich draw solution basin 321 passing into the lean draw solution return basin 331 hollow between the coupled plates 316. The lean draw solution converges radially inward through the lean draw solution basins 331, eventually passing through the lean draw solution ducts 329 in the plate hubs 318 entering the lean draw solution conduit penetrations 327. The lean draw solution conveys through the lean draw solution conduits 13 in the spacers 9 for egress from the vessel 1.
Low pressure in the central longitudinal reject conduit 10, communicated through the radial bridge ducts 414 of the spacers 9 educes centrally inward spiraling of the feed fluid across the membranes 332 covering the coupled plates 316. Permeate issues from the feed fluid as it spirals past the membranes 332. The reject fluid radially conveys through the bridge ducts 414 of the spacers 9 passing into and through the longitudinal reject conduit 10 to egress the vessel 1.
As
The implementations just described are not the only implementations possible Many additional implementations are possible.
For the exemplary purposes of this disclosure, another spiral cross flow membrane pressure filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane forward osmosis filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane pressure filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane forward osmosis filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane pressure filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane forward osmosis filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane pressure filtration device is depicted in
For the exemplary purposes of this disclosure, another spiral cross flow membrane forward osmosis filtration device is depicted in
For the exemplary purposes of this disclosure, in some implementations the debris and detritus egress does not come from the cyclonic swirl. For example, in some implementations the vessel axis could be vertical. Then, the detritus egress would be from detritus sedimentation from the cyclonic flow into a lower section of the vessel. The detritus may or may not be extracted from the cyclonic swirl. Thus, the solids egress port could come from a non-cylindrical end surface of the vessel and also due to the fact that the cyclonic flow will have degraded in this settlement area, in a vertical configuration.
For the exemplary purposes of this disclosure, in some implementations, instead of two membrane plates, a single membrane plate may be included in a small vessel. Centrally located ports in the single membrane vessel sidewalls may address the radial inward flow. This implementation also eliminates the need for reject fluid port in spacers.
For the exemplary purposes of this disclosure, in some implementations, a single membrane plate vessel can be used with at least one spacer for flow and reject holes may be in the two end walls of the vessel, radially just outside the spacer. That is, reject is ported from the vessel walls centrally on one or both sides of the membrane plate rather than through the membrane plate core or spacer core.
For the exemplary purposes of this disclosure, implementations employing various combinations of portions of the foregoing implementations are certainly conceivable. It is plausible that vessels could enclose multiple compartments to facilitate sequential membrane types, chemical additions or draw solution conditioning.
For the exemplary purposes of this disclosure, implementations employing various configurations of inlet feed such as spiral slots, vaned slots, multiplicity of types and numbers of inlets, adjustable slots and multiple focused ingress port are plausible configurations and variances as well.
For the exemplary purposes of this disclosure, implementations wherein both ingress generated cyclonic flow and mechanical rotation of the plates are plausible.
For the exemplary purposes of this disclosure, implementations wherein both ingress generated cyclonic flow and mechanical spinning vane induced cyclones are plausible.
For the exemplary purposes of this disclosure, implementations engaging additional beneficial appliances are also feasible. Example of such would be the employ of centrifugal separation devices such as centrifuges, hydro-cyclones or clarifiers to concentrate reject or waste blowdown for recycle. Filtration devices could also be so used.
For the exemplary purposes of this disclosure, it is reasonable to envision thermal processes being employed in certain implementations. An example would be heating of the vessels, draw solutions or feed fluids to enhance flux rates.
For the exemplary purposes of this disclosure, it is conceivable that multiple combinations of vessels could be readily employed to independently and sequentially treat the feed fluids for various extraction or treatment opportunities. Separate tanks could also rationally be engaged to facilitate quiescence to enhance solids separation for decant recycling.
Further implementations are within the CLAIMS.
It will be understood that implementations are not limited to the specific components disclosed herein, as virtually any components consistent with the intended operation of a spiral cross flow membrane filtration device implementation may be utilized. Accordingly, for example, although particular components and so forth, are disclosed, such components may comprise any shape, size, style, type, model, version, class, grade, measurement, concentration, material, weight, quantity, and/or the like consistent with the intended operation of a spiral cross flow membrane filtration device implementation. Implementations are not limited to uses of any specific components, provided that the components selected are consistent with the intended operation of a spiral cross flow membrane filtration device implementation.
Accordingly, the components defining any spiral cross flow membrane filtration device implementation may be formed of any of many different types of materials or combinations thereof that can readily be formed into shaped objects provided that the components selected are consistent with the intended operation of a spiral cross flow membrane filtration device implementation. For example, the components may be formed of: rubbers (synthetic and/or natural) and/or other like materials; glasses (such as fiberglass), carbon-fiber, aramid-fiber, any combination thereof, and/or other like materials; polymers such as thermoplastics (such as ABS, Acrylic, Fluoropolymers, Polyacetal, Polyamide; Polycarbonate, Polyethylene, Polysulfone, and/or the like), thermosets (such as Epoxy, Phenolic Resin, Polyimide, Polyurethane, Silicone, and/or the like), any combination thereof, and/or other like materials; composites and/or other like materials; metals and/or other like materials; alloys and/or other like materials; any other suitable material; and/or any combination thereof.
For the exemplary purposes of this disclosure, the membranes employed within this disclosure are not limited to any sheet type; examples of which may be pressure filters such coarse screen type, cloth type, paper type, micro-filter, ultra-filter, nanofilter and reverse osmosis or forward osmosis type membranes are all possible.
For the exemplary purposes of this disclosure, an FO membrane may be made from a thin film composite RO membrane. Such membrane composites include, for example, a cellulose ester membrane cast by an immersion precipitation process on a porous support fabric such as woven or nonwoven nylon, polyester or polypropylene, or preferably, a cellulose ester membrane cast on a hydrophilic support such as cotton or paper. The RO membrane may be rolled using a commercial thin film composite, sea water desalination membrane. The membranes used for the FO element (in any configuration) may be hydrophilic, membranes with salt rejections in the 80% to 95% range when tested as a reverse osmosis membrane (60 psi, 500 PPM NaCl, 10% recovery, 25.degree. C.). The nominal molecular weight cut-off of the membrane may be 100 daltons. The membranes may be made from a hydrophilic membrane material, for example, cellulose acetate, cellulose proprianate, cellulose butyrate, cellulose diacetate, blends of cellulosic materials, polyurethane, polyamides. The membranes may be asymmetric (that is, the membrane may have a thin rejection layer on the order of 10 microns thick and a porous sublayer up to 300 microns thick) and may be formed by an immersion precipitation process. The membranes may be either unbacked, or they may have a very open backing that does not impede water reaching the rejection layer, or they may be hydrophilic and easily wick water to the membrane. Thus, for mechanical strength they may be cast upon a hydrophobic porous sheet backing, wherein the porous sheet is either woven or non-woven but having at least about 30% open area. The woven backing sheet may be a polyester screen having a total thickness of about 65 microns (polyester screen) and total asymmetric membrane is 165 microns in thickness. The asymmetric membrane may be cast by an immersion precipitation process by casting a cellulose material onto a polyester screen. The polyester screen may be 65 microns thick, 55% open area.
Various spiral cross flow membrane filtration device implementations may be manufactured using conventional procedures as added to and improved upon through the procedures described here. Some components defining a spiral cross flow membrane filtration device implementation may be manufactured simultaneously and integrally joined with one another, while other components may be purchased pre-manufactured or manufactured separately and then assembled with the integral components.
Manufacture of these components separately or simultaneously may involve extrusion, pultrusion, vacuum forming, injection molding, blow molding, resin transfer molding, casting, forging, cold rolling, milling, drilling, reaming, turning, grinding, stamping, cutting, bending, welding, soldering, hardening, riveting, punching, plating, and/or the like. If any of the components are manufactured separately, they may then be coupled with one another in any manner, such as with adhesive, a weld, a fastener, wiring, any combination thereof, and/or the like for example, depending on, among other considerations, the particular material forming the components.
Implementations of a spiral cross flow membrane filtration device and process are particularly useful in forward osmosis/water treatment applications as previously explained. However, implementations are not limited to uses relating to forward osmosis applications. Rather, any description relating to forward osmosis applications is for the exemplary purposes of this disclosure, and implementations may also be used with similar results in a variety of other applications.
Thus, the excellent attributes of a spiral cross flow membrane filtration device afford the trouble free application of all types of membrane filtration media and associated applications; coarse strainer, microfilter, ultrafilter, nanofilter, and reverse osmosis as well. The cleanliness and ease of service substantially advances the durability of membranes and minimizes the cleaning, flushing and associated maintenance burdens typical of the prior art.
This disclosure provides a means to efficiently and robustly employ membrane based filtration and treatment processes in the presence of poor quality feed fluids as well as providing a uniquely easy means to service and replace individual membrane elements. The advantages over conventional techniques are substantial.
High solids content and poor quality feed fluids can be processed without plugging fouling or blinding. This results in enhanced operational reliability, less chemical costs for cleaning, longer membrane life, enhanced flux rates and throughput performance, less down time, and lower pumping energy use.
The ability to process high solids content and poorer quality fluids eliminates the need for expensive pretreatment technologies. Pre-filtration, screening, settling, coagulation, flocculation and other processes and technologies common and necessary with conventional techniques are not required, thereby eliminating high capital and operating expenses as well as inefficiencies associated with these pretreatment technologies.
The superior capacity to successfully process poor quality feed fluids provides the unique capability to process normal quality waters to a much higher level of solids concentration and poorer quality than conventional techniques. This substantial advantage affords the unique ability to generate more valuable product with less feed fluid and less wasted volume.
The unique membrane structure and support arrangement provides extreme ease of membrane servicing and replacement. In contrast to conventional techniques, the membrane surfaces are not configured as non-accessible spiraled cartridges or tiny tubular surfaces prone to plugging. Instead, the membrane surfaces are each individually and easily accessible, cleanable and replaceable.
Cleansing high velocity cross-flow employs no flow shadowing distribution bars or reception bars. Instead, shadow free, high velocity flow is provided, eliminating the blinding and plugging resulting from shadow effect solids build up and associated service requirements and performance degradation.
Additionally, the high velocity cleansing cross-flow is entirely hydraulic driven, eliminating mechanical stresses imposed upon membranes by swirling mechanical blades for example. Further since mechanical shearing, tearing or impaction issues are nonexistent, the induced swirl velocity limitations upon the membranes are lax, permitting much higher cross-flow velocities and the associated much higher membrane cleansing performance.
Forward osmosis implementations benefit from the fully countercurrent radially inward feed flow and radially outward rich draw solution flow providing superior forward osmosis flux rates.
The unique ability to reverse flow patterns provides much more efficient membrane surface scouring by eliminating the inevitable streamline and shadow deposition burdens common to conventional techniques.
The unique capacity to employ cyclonic centrifugal separation of solids and detritus for continuous or periodic blowdown is a tremendous advantage over conventional techniques. This feature affords the ability to employ poorer quality feed fluid, reduce waste, increase durability and reliability, reduce maintenance, and extend the membrane lifecycle.
Multiple coupled stacked plate and spacer assemblies with longitudinal feed fluid slots proffer parallel feed fluid contact to all the membranes in the vessel eliminating a troublesome propensity of conventional techniques of creating a solids content gradient upon sequentially contacted membranes. Accordingly, this parallel feed affords elimination of segregated fouling or blinding and purveys the maximum flux through the membranes as a whole. Additionally, in forward osmosis applications, the parallel feed bestows the highest osmotic pressure and maximum flux through the membranes.
In places where the description above refers to particular implementations, it should be readily apparent that a number of modifications may be made without departing from the spirit thereof and that these implementations may be alternatively applied. Other implementations presently existing or later to be developed, which perform substantially the same function or achieve substantially the same result as the corresponding implementations described herein, may be utilized. The accompanying CLAIMS are intended to cover such modifications as would fall within the true spirit and scope of the disclosure set forth in this document. The presently disclosed implementations are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the disclosure being indicated by the appended CLAIMS rather than the foregoing DESCRIPTION. All changes that come within the meaning of and range of equivalency of the CLAIMS are intended to be embraced therein.
