Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
  • B01D63/10—Spiral-wound membrane modules
  • B01D63/103—Details relating to membrane envelopes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
  • B01D63/10—Spiral-wound membrane modules
  • B01D63/106—Anti-Telescopic-Devices [ATD]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/04—Tubular membranes

Definitions

• the present invention is directed toward means and methods for applying a tape layer to the outer periphery of a spiral wound module.
• Spiral wound modules also referred to as spiral wound “elements” are well known for use in a variety of fluid separations including both gas and liquid phase separations. Due to their spiral configuration, a relatively large membrane surface area can be packed into an individual module.
• spiral wound modules can be used in a wide variety of applications including: reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF).
• RO reverse osmosis
• NF nanofiltration
• UF ultrafiltration
• MF microfiltration
• common liquid separations include the treatment of liquid feeds such as the concentration and/or salt removal in food, dairy and sweetener feeds; desalination of water, removal of divalent ionic species such as calcium and barium ions, and removal of larger constituents such as cysts, viruses, and pesticides.
• a typical module includes a permeate collection tube, at least one but often a plurality membrane envelopes and an outer cover or housing.
• Spiral wound modules are available in a variety of sizes; however, for home drinking water treatment units modules typically have a length of from about 15 to 45 cm and a diameter of from about 3.5 to 5 cm. For a typical 5 cm diameter module, one to three membrane envelops are wound around the permeate collection tube.
• Commercially available examples of such spiral wound modules include model TW30-1812 (24, 36, 50 and 75) from the FilmTec Corporation.
• Spiral wound modules commonly include an outer tape layer which maintains the membrane envelope(s) in a spiral wound configuration and which may further serve as an outer cover or housing for the module.
• Applicable tapes include pressure sensitive tapes applied from a roll.
• One known application technique involves helically winding a relatively narrow width of tape about the outer periphery of the module, as illustrated in Figure 2A. This technique is time intensive given the number of winds necessary to cover the outer periphery of the module.
• Another known technique illustrated in Figure 2B utilizes a relatively wide tape which covers the outer periphery of the spiral wound module in a single pass. That is, the width (W) of the tape coincides with the length (L) of the spiral wound module such that the tape covers the outer periphery in one rotation about the module.
• the present invention is directed toward means and methods for applying a tape layer to the outer periphery of a spiral wound module. Many embodiments are disclosed.
• Figure 1 is a perspective, partially cut-away view of a spiral wound module.
• Figure 2A is perspective idealized view showing a prior art technique of applying a tape layer about the periphery of a spiral wound module.
• Figure 2B is perspective idealized view showing another prior art method of applying a tape layer about the periphery of a spiral wound module.
• Figure 2C is perspective idealized view showing one embodiment of the subject method of applying a tape layer about the periphery of a spiral wound module.
• Figure 3A is a perspective view of an idealized set-up for practicing one embodiment of the invention showing the alignment of an unrolled length of tape with a spiral wound module.
• Figure 3B is a perspective view of the set-up of Figure 3A showing the application of an unrolled length of tape to the outer periphery of a spiral wound module.
• Figure 4 is a perspective view of an alternative idealized set-up for practicing on embodiment of the subject invention.
• Figure 5 is a perspective view of another alternative idealized set-up for practicing on embodiment of the subject invention.
• the present invention includes a method for applying a tape layer to the outer periphery of a spiral wound module.
• the tape layer is not particularly limited but is preferably applied from a roll.
• the width of the tape corresponds to the width of the roll; whereas the length of the tape corresponds to the amount of tape removed from the roll. That is, while the width of the tape is fixed by the width of the roll, the length of the tape is variable depending upon the portion of tape tangentially "dispensed" from the roll.
• tapes having thickness of from approximately 0.075 to 0.15 mm have been found acceptable for most embodiments.
• the tape layer may also provide support to the module during operation.
• tapes having relatively high tensile strengths may be preferred.
• bi-directional tapes are advantageous.
• Taps having tensile strengths above about 30 N/mm are acceptable.
• Applicable tapes include those which comprise a polymer backing (for example polypropylene, polyester, etc.) with an adhesive (for example acrylic, synthetic rubber resin, etc.) provided upon at least a portion of one side.
• Preferred tapes include pressure sensitive tapes having a non-adhesive front side and an adhesive covered back side. The adhesive need not be applied to the entire back side of the tape. Moreover, the type of adhesive need not be pressure sensitive.
• the spiral wound module is not particularly limited and includes modules such as those commonly used in home water treatment systems which typically have a diameter of approximately 3.5 to 5 cm.
• a spiral wound module suitable for use in the present invention is generally shown at 2 in Figure 1.
• the module (2) is formed by winding one or more membrane envelopes (4) and optional feed channel spacer sheet(s) ("feed spacers") (6) about a permeate collection tube (8).
• Each membrane envelope (4) preferably comprises two substantially rectangular membrane sheets (10) surrounding a permeate channel spacer sheet (“permeate spacer”) (12).
• the module (2) comprises a plurality of membrane envelops (4) separated by a plurality of feed spacers sheets (6).
• Membrane envelops (4) are commonly formed by joining the back side surfaces of adjacently positioned membrane leaf packets, wherein each leaf packet comprises a substantially rectangular membrane sheet (10) folded upon itself to define two membrane "leaves” wherein the front sides (34) of each leaf are facing each other and the fold is axially aligned with the fourth edge (22) of the membrane envelope (4), that is parallel with the permeate collection tube (8).
• a feed spacer sheet (6) is shown located between facing front sides (34) of the folded membrane sheet (10). The feed spacer sheet (6) facilitates flow of feed fluid in an axial direction (that is parallel with the permeate collection tube (8)) through the module (2).
• the membrane envelope (4) is formed by joining the back sides of two adjacently positioned membrane leaves.
• permeate spacer sheets (12) may be attached about the circumference of the permeate collection tube (8) with membrane leaf packets interleaved therebetween.
• the back sides of adjacently positioned membrane leaves are sealed about portions of their periphery (16, 18, 20) to enclose the permeate spacer sheet (12) to form a membrane envelope (4).
• the membrane envelope(s) (4) and feed spacer(s) (6) are wound or "rolled" about the permeate collection tube (8) to form two opposing scroll faces (30, 32) at opposing ends.
• the sealant (14) used for sealing the edges (16, 18, 20) of the membrane envelope (4) preferably permits relative movement of the various sheet materials during the winding process.
• the cure rate or period of time before which the sealant (14) becomes tacky is preferably longer than that required to assemble and wind the membrane envelopes (4) about the permeate collection tube (8).
• the length of the spiral wound module refers to the distance between the opposing ends of the module, that is the linear distance from one scroll face (30) to the other (32).
• Feed fluid enters the module (2) from an inlet scroll face (30) and flows across the front side(s) 34 of the membrane sheet(s) (10) and exits the module (2) at the opposing outlet scroll face (32).
• Permeate fluid flows along the permeate spacer sheet (12) in a direction approximately perpendicular to the feed flow as indicated by arrow (28). Actual fluid flow paths vary with details of construction and operating conditions.
• Suitable sealants for sealing membrane envelopes include urethanes, epoxies, silicones, acrylates, hot melt adhesives and UV curable adhesives. While less common, other sealing means may also be used such as application of heat, ultrasonic welding and tape.
• Permeate collection tubes are typically made from plastic materials such as acrylonitrile-butadiene-styrene, polyvinyl chloride, polysulfone, poly (phenylene oxide), polystyrene, polypropylene, polyethylene or the like. Tricot polyester materials are commonly used as permeate spacers. Representative feed spacers are described in more detail in US Patent 6,881,336 to Johnson.
• feed spacers include polyethylene, polyester, and polypropylene mesh materials such as those commercially available under the trade name VEXARTM from Conwed Plastics. Additional details regarding various components and construction of spiral wound modules are provided in the literature see for example: US Patent No. 5,538,642 to Solie which describes a technique for attaching the permeate spacer to the permeate collection tube, WO 2007/067751 to Jons et. al which describes trimming operations and the use of a UV adhesive for forming an insertion point seal.
• the type of membrane sheet is not particularly limited.
• the selection of membrane sheet is based on the specific application, feed source, solute, and foulants. While RO and NF flat sheet membranes have been formed from many different materials (for example cellulose acetate materials, polysulfone, poly ether sulfone), the most commercially successful membranes have been thin film composite membranes.
• One preferred composite membrane sheet is FilmTec Corporation's FT-30TM membrane.
• ⁇ film composite membranes typically comprises a bottom layer (back side) of a nonwoven polyester material web (for example PET scrim), a middle layer of a microporous polymer such as polysulfone having a thickness of about 25-125 microns, and top layer (front side) comprising a thin film polyamide layer having a thickness less than about 1 micron and more commonly from about 0.010 to 0.1 micron.
• a nonwoven polyester material web for example PET scrim
• a middle layer of a microporous polymer such as polysulfone having a thickness of about 25-125 microns
• top layer front side
• a thin film polyamide layer having a thickness less than about 1 micron and more commonly from about 0.010 to 0.1 micron.
• the polyamide layer is preferably created by an interfacial polycondensation reaction between a polyfunctional amine monomer and a polyfunctional acyl halide monomer upon the surface of the microporous polysulfone as described in US Patent Nos.: 4,277,344 and 5,658,460 to Cadotte et al; and US 6,878,278 to Mickols.
• Methods of modifying such polyamide membranes are described in US Patent No. 5,876,602 to Jons et. al.; US 5,755,964, US 6,280,853 and US 2009/0159527 to Mickols; US 4,888,116; US 4,765,897; US 4,964,998 to Cadotte et. al. and US 2007/0251883, US 2008/0185332 and US 2009/0194479 to Niu et al. RO and NF type membrane sheets are preferred for use in the present invention.
• the present invention includes a method for applying a tape layer (36) from a roll (38) to the outer periphery of the spiral wound module (2).
• the term "outer periphery” refers to the cylindrical outer surface area of the module (2) but does not include the scroll faces (30, 32).
• a length of tape from the roll (38) is applied to the outer periphery of the spiral wound module (2) in a manner such that the length of tape (36) coincides with the length of the spiral wound module (2).
• the term “coincides” means that the length direction of both the tape (36) and module (2) are approximately parallel to each other, and while not required, are also preferably of approximately the same length, for example the tape (36) is preferably the same or slightly longer (for example preferably less than 10 percent longer) than the length of the spiral wound module (2).
• the tape (36) preferably forms a layer about the majority, and more preferably the entire outer periphery of the spiral wound module (2).
• the width (W) of the tape (2) is preferably equal to or greater than the circumference of the spiral wound module (2) such that the tape (36) wraps about at least 90 percent (%) and more preferably 100% of the circumference of the outer periphery of the spiral wound module (2).
• the width (W) of the tape is at least 10% or even 25% greater than the circumference of the spiral wound module (2) such that the tape (36) may be overlap upon itself once applied about the outer periphery of the spiral wound module (2).
• the width of the tape (2) may be less than the circumference of the spiral wound module (2); in which case multiple parallel and adjacently aligned strips of tape may be applied along the length of the module in order that tape covers the majority and preferably entire circumference of the module.
• While tape may be applied to the module as it is unrolled from the roll (for example by contacting a free edge of the tape to one end of the module and simultaneous contacting the tape to the outer periphery of the module as the tape is unrolled along the length of the module), a length of tape is preferably unrolled from the roll prior to the step of applying the tape to the module.
• the length of unrolled tape corresponds to the length of the spiral wound module, that is within 10% of the length of the module but is preferable equal to or slightly longer than the module.
• the unrolled tape is preferable cut, torn, or otherwise separated from the roll prior to being applied to the outer periphery of the spiral wound module.
• the manner in which the unrolled tape is contacted with the module is not particularly limited. In one preferred embodiment, the unrolled tape is first aligned with the spiral wound module prior to being contacted with its outer periphery.
• a length of unrolled tape is cut from a roll and linearly aligned along an axis which is spaced from and parallel to the spiral wound module (that is parallel to the axis defined by the permeate collection tube) such that the length of the tape coincides with the length of the module.
• the unrolled tape is contacted with the outer periphery of the spiral wound module.
• Figures 3A and 3B depict an idealized set-up for practicing one embodiment of the subject method. As shown, tape (36) is unrolled from roll (38) and cut with movable blades (40, 40') to a length corresponding to the length of the spiral wound module (2).
• the unrolled length of tape (36) is then aligned with spiral wound module (2) by drawing the front side (42) of the tape (36) against a press (46) (as indicated by a curved arrow in Figure 3A), such as by way of drawing negative pressure (that is vacuum) through the press (46) (as indicated by an upward arrow), and locating the press (46) in a spaced apart and aligned position relative to the spiral wound module (2).
• the press (46) comprises a vacuum drum including a convex surface (48) for drawing the front side (42) of the tape (36).
• the back side (44) of the tape (36) is contacted to the outer periphery of the module (2) by moving one or both the press (46) and module (2) together, (as indicated by a bi-directional vertical arrow), into contact with each other with the unrolled tape (36) located therebetween.
• the unrolled tape (36) is subsequently applied to the outer periphery of the module (2) by counter rotating the press (46) and module (2) (as indicated by curved arrows in Figure 3B) while maintaining contact between the press (46) and module (2).
• FIGS 4 and 5 illustrate alternative set-ups for practicing embodiments of the invention.
• rollers (50, 52, 54) for applying an unrolled length of tape (36) to the outer periphery of a spiral wound module (2).
• a length of tape is unrolled and cut from the roll, linearly aligned, and then contacted with the outer periphery of a spiral wound module (2).
• a single rotating roller (50) is subsequently brought into contact with the module (2), with the tape (36) located between the roller (50) and module (2).
• the roller (50) and module (2) are then counter rotated about their respective axes while maintaining contact until the tape (36) forms a layer about the outer periphery of the module (2).
• roller (50) may be fixed about its axis.
• Figure 5 illustrates a similar set-up utilizing a pair of rollers (52, 54) which counter rotate about the outer circumference of the spiral wound module (as illustrated by curved arrows in Figure 5).
• rollers (52, 54) may be driven by rotation of the module (2) about its axis (defined by the permeate collection tube (8)).
• the rollers (52, 54) may be fixed about their axes.
• the present invention is well suited for applying a tape layer to spiral wound modules and particularly to modules having lengths beyond standard tape widths, for example modules longer than 25 cm, 50 cm, 100 cm, 150 cm and 225 cm.
• the length of tape applied to the module is the same or slightly longer in length than the module. Excess tape extending beyond the ends of the module can be trimmed as part of an optional finishing step.
• the spiral wound module preferably includes at least a permeate collection tube extending between two opposing ends and including a plurality of openings along its length, and at least one membrane envelope wound about the permeate collection tube and forming two opposing scroll faces, wherein the membrane envelope is in fluid communication (and preferably in sealing engagement) with the openings along the permeate collection tube.
• the membrane envelope is not particularly limited and may comprise a wide range of designs, compositions and structures.
• the membrane envelope comprises a structure which functions as an RO or NF membrane.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Adhesive Tapes (AREA)

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• 2010
  • 2010-10-13 US US12/903,245 patent/US8142588B2/en active Active
  • 2010-10-13 WO PCT/US2010/052414 patent/WO2011053452A1/en not_active Ceased
  • 2010-10-13 JP JP2012536848A patent/JP5763662B2/ja not_active Expired - Fee Related
  • 2010-10-13 CN CN201080047309.6A patent/CN102574063B/zh active Active
  • 2010-10-13 EP EP10771271.3A patent/EP2493598B1/en active Active
  • 2010-10-13 KR KR1020127013282A patent/KR101788534B1/ko active Active

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