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| United States Patent | 5096591 |
| Link to this page | http://www.wikipatents.com/5096591.html |
| Inventor(s) | Benn; James A. (29 Academy St., Arlington, MA 02174) |
| Abstract | A spirally wound ultrafiltration filter cartridge system and method which
comprises a membrane sheet material forming a closed loop having a one end
and an other end with first and second open spacer sheet materials, the
membrane sheet material and spacer sheet material wrapped about a
perforated center tube, the membrane sheet material sealed at either end
by solid resin headers, the filter cartridge forming spirally wound
permeate and concentrate flow channels and having a tangential, elongated
feed inlet on the exterior surface of the filter cartridge. A concentrate
stream is removed from the center tube and a permeate stream is removed
from the one end of the closed loop of the membrane sheet material. The
method of manufacture comprises spirally winding the closed end loop sheet
material and the spacer sheet material about a perforated center tube and
sealing either end of the membrane sheet material with a ptting resin. |
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Title Information  |
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Drawing from US Patent 5096591 |
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Spirally, wound filter cartridge, apparatus system and method of
manufacture and use |
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| Publication Date |
March 17, 1992 |
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| Filing Date |
September 11, 1990 |
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| Parent Case |
REFERENCE TO PRIOR APPLICATION
This application is a continuation-in-part patent application of U.S. Ser.
No. 07/518,811, filed May 4, 1990, LIQUID SEPARATION AND CLARIFICATION
SYSTEM. The parent application is directed to an ultrafiltration apparatus
and method particularly for the filtration of high solids-containing,
petroleum solvent and water waste effluent from cleaning ink printing
press blankets. |
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Title Information |
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Description |
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BACKGROUND OF THE INVENTION
In traditional filtration equipment, fluid to be filtered is recirculated
through a filter element containing filtration membranes where the fluid
is driven parallel to the membrane to permit the membrane to purify fluid
as it passes through the membrane, and to provide a scrubbing action on
the surface of the membrane to remove built-up solids that have been
filtered out of the fluid by the membrane. These filter elements typically
have one inlet where the raw fluid is introduced, and two outlets, one
where the raw recirculating fluid exits and another where the purified
fluid exits.
Many different configurations of ultrafiltration filter elements have been
developed which provide this crossflow cleaning action. One type of filter
element, called a "spiral" type of filter element, is made of flat sheets
of filter material that are made into pouches that are wound into a spiral
shape around a porous or perforated center tube. The feed fluid to be
filtered enters one end of the filter element and flows parallel to the
cylindrical axis of the filter to exit at the other end of the filter as a
concentrate stream. The filtered or permeate fluid collects in the pouches
and passes in a spiral manner to the center tube for collection. This type
of "spiral" design is used currently by many companies to construct both
ultrafiltration as well as reverse osmosis filter elements.
Major problems with this type of filter element are that they are expensive
to manufacture and cannot be easily mounted on or dismounted from a piece
of filtration equipment. In the typical well-known state-of-the-art
manufacturing process, individual flat sheets are positioned on a table
top, urethane or epoxy adhesive is applied around the perimeters of the
alternate sheets, and they are then manually rolled around a center tube
to create spiral-shaped pouches hydraulically connected to the center
tube. Upon drying of the adhesive, the ends of the rolled filter element
are trimmed to remove excess adhesive and open the spaces between the
individual pouches to allow the fluid to be filtered to enter the ends of
the filter element. Not only is this a slow manual manufacturing process,
but also often, when trimming the excess adhesive from the ends of the
filters, the pouches can be accidentally ruptured, rendering the filter
element useless. Therefore, usually extensive leak testing must be
performed on the filter elements before they are released to the customer.
In current, commercial practice, these filters are mounted on a filtration
system by being inserted into a filter housing, which is then screwed onto
a hydraulic fitting on the filtration system. Fluid to be filtered enters
the top of the filter element and flows axially through the filter element
to exit at the bottom of the filter. Fluid that has been filtered enters
the spirally wound pouches and flows spirally to the center tube for
collection.
When the filter element needs changing, the housing must be dismounted from
the filtration system and the filter element manually removed from the
housing. This results in considerable spillage and operator exposure to
the fluid being filtered, where this fluid may be hazardous to the
operator and equipment.
It is desirable therefore to provide a spiral wound filter apparatus and
method of manufacturing the filter apparatus, which filter apparatus is
easily and inexpensively manufactured and wherein the spiral wound filter
cartridge used in the filter apparatus can be easily mounted and
dismounted on conventional filter apparatuses by an unskilled operator and
with minimum contact with any potentially hazardous fluids being filtered.
It is desired to provide a method of filtration particularly for the
filtration of hazardous solvent or water waste solutions like ink printing
blanket waste solution comprising ink and other particles, petroleum
solvent and water.
SUMMARY OF THE INVENTION
The invention relates to a spiral wound filter apparatus and a method of
manufacturing and using the filter apparatus.
The invention relates to a filter apparatus comprising a container and a
filter cartridge within the container for the separation of a feed stream,
such as, but not limited to a printing ink blanket waste effluent stream,
into a permeate stream and a concentrate stream. The filter apparatus
comprises a perforated or porous center tube for the withdrawing of a
concentrate stream and membrane sheet material, particularly an
ultrafiltration membrane sheet material, for example, having membrane
pores of less than about 0.5 microns for the separation of the feed stream
into the concentrate stream and the permeate stream with the membrane
sheet material typically formed in a closed loop. The filter apparatus
also includes a porous spacer, screen-type sheet material within the loop
of the sheet membrane material to separate the sheet membrane material and
also on the outside of the sheet membrane material, to form spirally wound
feed concentrate flow path and permeate flow path about the center tube,
that is, to form a spiral permeate flow channel and a spiral concentrate
flow channel about the center perforated tube.
The filter apparatus includes a tangential, elongated feed inlet comprising
the open end of the spiral formed by the loop of the sheet material on the
exterior, cylindrical surface of the filter cartridge for the tangential
introduction of the feed stream into the concentrate flow path channel.
First and second end headers are employed at one and the other end of the
spirally wound spacer, typically of potted resin, to seal the spirally
wound peripheral edges of the filter cartridge. The filter apparatus
includes a permeate outlet means extending into the permeate flow channel,
typically through the first or second or both end headers, for the
withdrawal of a permeate stream from the filter cartridge. The filter
apparatus includes a center perforated tube having at least one open end
and extending through at least the one or second header end or both for
the withdrawal of a concentrate stream from the filter cartridge.
Optionally, as described, the woven screen material employed to form the
concentrate and permeate flow channels may be wound around the exterior
surface of the filter cartridge to form an exterior screen wraparound so
that the filter cartridge may be snugly fit into the cylindrical container
of the filter apparatus.
Traditional liquid filter apparatuses are designed to capture contaminants
and let the liquid of the feed stream pass through. Generally, the
quantity of solid contaminants in the feed stream are small and a small
amount of filter material can be used for filtering large fluid quantities
before saturation or plugging of the filter material or ultrafiltration
membrane surface occurs. However, some liquid feed stream requiring
filtration contain a high level of contaminants which very quickly
saturate or plug filter material in conventional filter apparatuses. The
present filter apparatus relates to a novel design of a new filter
apparatus which is spirally wound and contains a large amount of filter
membrane material in a small space and is inexpensively and easily
manufactured to enable economic filtration of particularly fluids with a
high level of contaminants, such as the filtration of aqueous, petroleum
solvent cleaning solutions for printing presses. The ink printing press
blanket wash waste solution typically is derived when the solvent is
applied to paper handling parts of the press. The solvent dissolves and
carries away dried ink and paper debris. The solvent can be cleaned for
reuse if the ink and paper debris are removed from the solvent. One method
of cleaning the solvent from such waste effluent streams is by
distillation.
The parent application describes the employment of a hollow fiber filter
membrane to effect cleaning by filtration of the waste effluent stream.
The present filter apparatus and cartridge is particularly adapted for the
use in filtration of the printing ink blanket wash waste effluent streams;
however, it is recognized that the present filter apparatus and cartridge
may be adopted and used for a wide variety for filtering operations and
which also require ultrafiltration. It is particularly useful where the
filtration fluid is hazardous, and the filter cartridge needs to be
changed periodically, quickly and preferably without contact of the waste
solution with the hands of the operator.
In the operation of the filter apparatus, fluid to be filtered enters the
filter cartridge, at the external, tangential, elongated feed opening of
the permeate flow channel on the external surface of the cylindrical
filter cartridge. The feed stream continues throughout a spiral,
concentrating flow path toward the center of the spiral and then is
removed through a concentrate perforated center tube. The feed fluid is
typically pressured, from example, from 5 psi to 30 psi or higher where
the cartridge is employed in ultrafiltration, and typically from 15 psi to
22 psi so that the concentrate passes across the filtration membrane on
either side of the flow channel where it enters the spirally wound
permeate flow path and proceeds to the permeate outlet tube generally
centrally disposed and adjacent the center tube where it is withdrawn. The
screen materials maintain the flow spaces between the spirally wound
filter material to create the spirally wound concentrate and permeate flow
paths about the center tube and permeate outlet tube.
The internal flow characteristics of the filter apparatus are different
from the typical, commercially available, spirally wound filter elements
in that the feed stream to be filtered enters the filter apparatus from
the external cylindrical surface by tangential entry along the entire
longitudianl surface, and then spirals around within the filter cartridge
for exit through the center tube at either one or the other end or both.
In the operation of an ultrafiltration apparatus, typically the inlet
pressure as stated may range from about 5 psi to 30 psi or more while the
outlet pressure is essentially 0 psi to 10 psi or more. A wide variety of
materials may be employed as the membrane sheet material to prepare the
filter, but more typically comprises an ultrafiltration or reverse osmosis
membrane sheet material having fine pores. One suitable ultrafiltration
material would comprise a porous, nylon 66-type material having a
thickness of from about 2 mils to 10 mils, but more particularly 5 mils to
6 mils, and having an average micron pore size of about 0.1 to 0.2 or
less. The spacer separating material employed on both sides of the filter
sheet material generally comprises a very open mesh-type, resilient,
screen-type material to form the spirally flow channels and typically may
be comprised of a non-corrosive-type material, such as a plastic material,
like an olefinic resin or polyethylene or polypropylene. The screen-type
material may very in size, but typically should be open enough to permit
the generally unimpeded flow of the permeate or concentrate stream, and
generally is molded or formed in a semi-rigid manner in an over-under
molded or woven-type arrangement. The screen-type material may range in
thickness from 5 mils to 30 mils, particularly 12 mils to 20 mils, which
amount substantially represents the size of the respective concentrate and
permeate flow channels.
In the use of the filter cartridge within the filter container of the
apparatus for the treatment of a printing press blanket waste effluent as
feed stream, i.e. containing 1% to 10% by weight of solid particles and
comprising a petroleum solvent, with an ultrafiltration surface membrane
of about 10 feet.sup.2, the recirculation flow rate is about 1.5 gallons
per minute, while the permeate flow rate is about 0.05 gallons per minute.
The feed pressure from the outside of the cylindrical filter cartridge
keeps the flow channels narrow so that there is a good membrane surface
scrubbing action by the fluid as the feed stream spirally winds through
the flow channels.
The filter cartridge and apparatus of the invention may be easily and
inexpensively manufactured. The filter cartridge is prepared by forming a
closed loop of the ultrafiltration sheet membrane material. Of course, if
desired, rather than having the entire loop made of ultrafiltration or
filtration sheet material one side of the material may be a non-porous
sheet material so that the loop would comprise adjacent, spaced apart
sheets, one of a filtration sheet material and the other of a non-porous
or different type filtration sheet material, with both ends connected and
sealed, such as by adhesive sealing of the edges or by a plug.
However, in one preferred embodiment, a sheet of ultrafiltration membrane
material is formed into a flattened loop, and a spacer screen-type
material is then placed within the loop to form the permeate channel. A
spacer screen optionally of the same or different type is then placed on
the outside surface of the flattened loop of the filtration sheet material
to form the concentrate flow channel. A permeate outlet tube is inserted
within the loop at one end, and then the screen and the membrane loop
material with the internal screen are merely rolled about the perforated
center tube into a spiral form and with the extending free end of the
screen material from within the concentrate channel wrapped around the
outside of the filter cartridge to provide for a snug fit within the
selected filter container. Each end of the spiral wound cartridge is then
dipped in a potting resin, such as a quick hardening epoxy or urethane
resin, to form a resin end header, and then the entire filter cartridge is
inserted into a cylindrical container to form the filter apparatus of the
invention.
The perforated permeate tube is merely potted in place with the potting
resin to extend adjacent the central tube, and thus desirably can be
inserted next to the central tube prior to rolling up the sheet material,
or in fact, the central tube may be cut away in a certain portion and the
concentrate discharge tube may be made a part of the central permeate
tube, but is within the end of the loop of the ultrafiltration sheet
material. When the ends of the wound spiral are formed, they are
sequentially dipped into the hardenable liquid urethane or epoxy resin to
form the end caps, the central tube and the permeate tube are temporarily
blocked to prevent them from filling with the resin. The formation of the
end caps creates passages for the feed stream to be filtered to enter the
outside cylindrical surface of the spiral within the filter container and
to exit by way of the permeate withdrawal tube. This method of manufacture
and assembly avoids the tedious and exacting manual job of applying
adhesive around the perimeter of individual sheet materials as in typical
spiral membrane modules, and also avoids the need to trim the ends of the
spiral subsequent to winding of the spiral elements.
The filter cartridge is easily incorporated into a disposable container to
form the filter apparatus, and that allows fast and safe mounting and
dismounting of the filter apparatus onto a standard ultrafiltration or
other filtration equipment. The filter apparatus thus resembles in shape
and use the familiar screw-type, spin-on filters used to filter oil in
automobile engines with the addition of a connection that is a permeate
discharge on the bottom of the filter element to remove the permeate feed
stream. The filter apparatus is desirable in that it can be mounted and
dismounted on a filtration system by an unskilled operator merely by
screwing on to the screw on-type or other mounting of standard filtration
systems where the operator can minimize contact with any potentially
hazardous fluids being filtered. In addition, the automatic low cost and
high reliability methods used currently to manufacture oil filters can be
easily modified to manufacture at very low cost the filter cartridge and
filter apparatus of the invention.
The invention will be described for the purposes of illustration only in
connection with certain embodiments; however, it is recognized that
various changes, modifications, additions and improvements may be made in
the illustrated embodiments by those persons skilled in the art, all
falling within the spirit and scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan, sectional view of the filter apparatus of the
invention;
FIG. 2 is a sectional view of the filter cartridge shown in FIG. 1; and
FIG. 3 is the filter system of the invention and showing in a sectional
view along lines 3--3 the use of the filter apparatus of FIGS. 1 and 2.
DESCRIPTION OF THE EMBODIMENTS
FIGS. 1 and 2 particularly show a filter cartridge 10 having a looped
ultrafiltration membrane nylon material 12 spirally wrapped around a
central concentrate outlet tube 14 having perforations 16 with screen
woven spacer material 18 to form a spirally wound concentrate channel 28
with a feed inlet 22 and a spirally wound permeate channel 30 with a
concentrate outlet in the center tube 14 with the outlet 24 and with a
tubular permeate outlet tube 26. As illustrated, the screen woven spacer
sheet material 18 is continually wrapped to form an external wrapping
around the outer ultrafiltration membrane sheet material 20 which forms
the outer cylindrical surface of the filter cartridge 10 so that the
filter cartridge may be snugly fit within a cylindrical container 42. As
illustrated, the permeate discharge tube 26 extends within one end of the
loop of the ultrafiltration membrane 12, while the other end forms the
elongated, tangential, exterior feed inlet 22 of the filter cartridge. The
spirally wound ultrafiltration membrane sheet material 12 and the spacers
18 are sealed by dipping into a potting resin to form end caps 34 and 36
with the permeate tube 26 extending through the end header 34 and the
outlet 24 of central tube 14 extending through end header 36.
FIG. 3 shows a filter system employing the filter cartridge 10 with the
external wrapping about of the screen spacer material 18 wrapped about the
exterior of the filter cartridge 10 to form a snug fit within the
cylindrical container 42 to form the filter apparatus, the filter
cartridge is snugly positioned within the container 42 and the end caps 34
and 36 sealed to the container by the employment of an adhesive. Container
42 has a lower permeate outlet 50 to withdraw the permeate discharge from
the permeate tube 26. The filter cartridge as shown is spun onto a
standard screw on-type filter holder head 44 used for mounting hydraulic
filters which head 44 has a concentrate outlet 46 so that concentrate
discharged from the center tube 14 may be removed and has a feed inlet 48
so that a feed stream may be introduced through the head 44 and into the
container 42 and hence, elongatedly and tangentially introduced into the
feed inlet flow path 22 to begin its spiral passage through the filter
cartridge 10. The container has a screw on-type header 45, and as
illustrated, the container 42 containing the filter cartridge 10 has been
screwed onto the standard filter holder head 44 with the threaded
connection sealing the outlet connection between header and filter, and
O-ring 38 sealing the inlet connection between the header and filter.
The filter cartridge apparatus and system and method of the invention thus
provide for an economically and easily manufactured filter cartridge and
apparatus which provides for an apparatus and cartridge which may be
easily and safely mounted and dismounted rapidly and to provide a rapid
and effective ultrafiltration apparatus particularly for hazardous fluids,
such as, but not limited to printing ink waste effluent streams.
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Description |
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