U.S. patent application number 15/387005 was filed with the patent office on 2017-04-13 for method of potting hollow fiber membranes and apparatus for filtering liquid with hollow fiber membranes.
The applicant listed for this patent is General Electric Company. Invention is credited to Zsolt BATOR.
Application Number | 20170100700 15/387005 |
Document ID | / |
Family ID | 48917692 |
Filed Date | 2017-04-13 |
United States Patent
Application |
20170100700 |
Kind Code |
A1 |
BATOR; Zsolt |
April 13, 2017 |
METHOD OF POTTING HOLLOW FIBER MEMBRANES AND APPARATUS FOR
FILTERING LIQUID WITH HOLLOW FIBER MEMBRANES
Abstract
A method for potting hollow fiber membranes comprises the steps
of forming a bundle of membranes with a layer of adhesive; covering
one end of the bundle with a permeate pan, the ends of the
membranes protruding upwards into the permeate pan; and flowing a
liquid potting material into the permeate pan. The bundle may be
tilted to more quickly distribute the liquid potting material. An
apparatus for filtering liquid with hollow fiber membranes
comprises a bundle of membranes, a layer of adhesive spaced from
the end of the bundle, a permeate pan covering the end of the
bundle, and a header formed with the membranes, the adhesive and
the pan.
Inventors: |
BATOR; Zsolt; (Oroszlany,
HU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
48917692 |
Appl. No.: |
15/387005 |
Filed: |
December 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13588611 |
Aug 17, 2012 |
9555375 |
|
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15387005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 63/021 20130101;
B01D 63/022 20130101; B01D 63/02 20130101; B01D 2313/025 20130101;
B01D 2313/21 20130101; B01D 2323/42 20130101; B01D 2313/10
20130101 |
International
Class: |
B01D 63/02 20060101
B01D063/02 |
Claims
1. An apparatus for filtering liquid with hollow fiber membranes,
the apparatus comprising a bundle of hollow fiber membranes; at
least a first layer of adhesive material substantially
perpendicular to the length of the membranes, the first layer of
adhesive spaced from an end of the bundle; a permeate pan covering
the end of the bundle to define a permeate collection space in
fluid communication with the lumens of the membranes; and a header
material extending from the first layer of adhesive to the pan,
wherein the header has meniscuses around the membranes or extends
to a second layer of adhesive material located between the end of
the bundle and the first layer of adhesive material.
2. The apparatus of claim 1 wherein the apparatus has the second
layer of adhesive material.
3. The apparatus of claim 1 wherein the pan further comprises a
hole to allow access to the permeate collection space.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 13/588,611, filed Aug. 17, 2012, which is hereby incorporated
by reference.
FIELD
[0002] The present invention relates to a method of potting hollow
fiber membranes and an apparatus for filtering with hollow fiber
membranes.
BACKGROUND
[0003] In order to filter a fluid with hollow fiber membranes, the
membranes are fixed to a header, alternatively called a potting
head or a tube sheet, such that their outer surfaces are sealed to
a first face of the header, but their lumens are open to a second
face of the header. In an immersed membrane module the header, with
the membranes, is then attached to a permeate pan to create a
permeate collection space between the second face of the header and
the pan. The permeate collection space is connected to a source of
suction to create a trans-membrane pressure across the walls of the
membranes and to carry the liquid from the ends of the membranes
through the permeate collection space.
[0004] In U.S. application Ser. No. 10/167,699, the ends of
membranes are potted in a liquid wax to create a fugitive lamina.
The wax is allowed to solidify around the ends of the membranes. A
thermosetting or thermoplastic synthetic resinous material is then
poured over the wax to create a fixing lamina. The wax prevents the
ends of the membranes from being plugged with the resinous
material. The resinous material is allowed to harden around the
membranes into a header. The wax is then removed by, for example,
heating or dissolving with a solvent, leaving the ends of the
membranes open to a space formerly occupied by the wax.
[0005] In U.S. Pat. No. 6,592,759, ends of membranes are potted in
a dense gel. A liquid, less dense than the gel, is poured over the
gel and around the membranes. The gel prevents the ends of the
membranes from being plugged with the liquid. The liquid is allowed
to harden into a header. Once the liquid has hardened, the gel is
removed by vibrating to a fluid state, flushing with a solvent, or
heating.
[0006] In U.S. Pat. No. 7,393,486, a bundle of hollow fiber
membranes are potted by injection molding a hot thermoplastic into
a cavity containing the membranes. The cavity is formed between a
mold and two spaced-apart layers of adhesive pre-applied to the
bundle of membranes. The hot thermoplastic is allowed to harden
into a header.
[0007] In U.S. application Ser. No. 12/381,097, ends of membranes
are inserted into a spacer and held with open ends protruding
upwards from the spacer. The spacer can be a plate with openings to
accommodate the membranes or the spacer can be flexible plastic
strips. In the case of flexible plastic strips, the strips can be
wound up in spiral shape, or segments of plastic strip can be
combined to form a multi-layer package. Once the membranes are
inserted in the spacer, a liquid is then poured around the
membranes and over the top of the spacer. The spacer is
non-permeable to the liquid thus preventing the liquid from flowing
down the membranes. The liquid is allowed to harden into a
header.
SUMMARY OF THE INVENTION
[0008] This specification describes a method of potting hollow
fiber membranes, and an apparatus for filtering liquid with hollow
fiber membranes.
[0009] The method for potting hollow fiber membranes comprises the
steps of forming a bundle of membranes with a layer of adhesive,
covering the end of the bundle with a permeate pan so that the end
of the bundle extends upwards into the pan, and flowing a liquid
potting material into the pan to fill the spaces between the
membranes and to cover the layer of adhesive.
[0010] Through this method, the steps of potting the ends of the
membrane in a fugitive lamina, and removing the fugitive lamina
once the header has formed, are avoided. This method also avoids
the need to rapidly inject hot thermoplastic into the potting area.
A thermosetting resin may solidify more slowly than melted
thermoplastic and does not need to be hot to be in liquid form.
Using the force of gravity, the liquid resin is allowed to spread
across the layer of adhesive without covering the ends of the
membranes. The permeate pan is bonded to the membranes as the resin
cures.
[0011] An apparatus for filtering liquid with hollow fiber
membranes comprises a bundle of membranes held together by a layer
of adhesive material; a permeate pan covering the end of the bundle
to create a permeate collection space which is in fluid
communication with the ends of the membranes; and a header
integrally formed with the membranes, the layer of adhesive, and
the permeate pan.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Examples of embodiments of the invention or inventions will
be described below with reference to the following figures.
[0013] FIG. 1 shows a plan view of two layers of adhesive on a
sheet of hollow fiber membranes.
[0014] FIG. 2 shows an isometric view of sheets of fibers of FIG. 1
assembled into a larger bundle of fibers having two layers of
adhesive.
[0015] FIG. 3A is an isometric view of a plate clamped
circumferentially around a bundle of fibers.
[0016] FIG. 3B is a cross-section view of FIG. 3A viewed along the
cut line A-A.
[0017] FIG. 4A is an isometric view of a plate and bundle abuted
against a permeate pan.
[0018] FIG. 4B is a cross-section view of FIG. 4A viewed along the
cut line B-B.
[0019] FIG. 5 is a cut-out cross-section view of FIG. 4A viewed
along cut line C-C, with a potting region filled with a liquid
resin.
[0020] FIGS. 6A, B and C are side views showing the use of gravity
to more quickly flow a liquid resin across a potting region.
[0021] FIG. 7 is a side view of a bundle fitted into a permeate
pan.
DETAILED DESCRIPTION
[0022] FIG. 1 shows a plan view of a sheet 1 of hollow membrane
fibers 5 with two layers of adhesive 2 and 3. Optionally, one layer
of adhesive can be used. The sheet of membranes 1 can be formed by
laying the membranes 5 on a supporting surface, such as a table, so
that the membranes 5 are generally parallel to each other but
spaced apart from each other, for example between 0.2 and 2 times
their diameter. Optionally, the sheet can be formed by any suitable
fabric forming method and have inert fibers running transversely
across the membranes to help maintain the membranes in position.
Further optionally, the sheet may be formed by winding the
membranes onto a drum, preferably though a guide that advances
across the face of the drum at a speed relative to the speed of
rotation of the drum which lays the fibers in a spiral around the
drum at a desired spacing. The membranes may have diameters, for
example, between 0.2 and 2.5 mm and there may be, for example,
between 10 and 500 membranes in a sheet. The width of the sheet may
be, for example, from 200 mm to 1200 mm and the length of the
sheet, and its membranes, may be, for example, between 200 mm and
3200 mm. In various Figures, the membranes are shown as cut to a
shorter lengths to allow other parts to be shown larger. To form
the sheet 1, a first layer of adhesive 2 is placed over the sheet 1
or forming surface so that it is spaced from one end 4 of the sheet
1. Optionally, a second layer of adhesive 3 can be placed over the
sheet 1. The second layer of adhesive 3 is at or spaced from the
end of the sheet 4. The second layer 3 optionally does not cover or
fill the ends of the membranes 5. The second layer 3 may be placed
close to the ends of the membranes 5, without closing the ends, to
reduce the length of the membranes 5 that will protrude into, and
interfere with flows of fluids in, the permeate cavity behind the
header. The layers of adhesive 2,3 hold the sheet together. The
layers of adhesive 2,3 also seal the entire outer circumference of
the membranes 5, although a perfect seal does not need to be
formed. The adhesive may be thermoplastic and applied by melting it
so that it flows over and around the membranes 5. The adhesive may
also be melted after applying it to the membranes 5 and molded or
shaped while it is molten to provide a layer of uniform shape or
more carefully controlled size. The adhesive may be of a type
normally referred to as hot melt glue, which may be a polyethylene
or a blend of ethylene vinyl acetate co-polymers. Alternately, the
adhesive may be a resin such as polyurethane or epoxy.
[0023] FIG. 2 shows a bundle 11 of membranes 5 made by stacking a
number of sheets 1, for example between 1 and 30 or between 10 and
20 sheets, together. Sheets 1 are stacked so that their adhesive
layers 2,3 lay on top of each other to generally form a
parallelepiped. Optionally, one or more sheets may be rolled up
together to generally form a cylinder or made into other shapes.
The sheets 1 may be glued, welded, melted or clamped together or
simply held together manually or by wrapping a string, wires, band
or other wrap around the bundle. A first layer of adhesive 12 is
at, or spaced from, one end 14 of the stack of membranes 5.
Optionally, a second layer of adhesive 13 is spaced from and
situated between the first layer of adhesive 12 and the end 14 of
the membranes 5, optionally so as to leave the ends of the bundle
of membranes 5 uncovered by adhesive.
[0024] FIGS. 3A and 3B shows a bundle 11 of membranes 5 clamped
circumferentially by a plate 101 about a first layer of adhesive
12. FIG. 3B is a cross section of FIG. 3A viewed along the cut line
A-A. The plate 101 is composed of four metal girder segments: two
length girders 102 and two end girders 103. The length girders 102
are clamped lengthwise along opposite sides of the bundle 11
against the first layer of adhesive 12. The length girders 102 are
preferably just slightly shorter than the length of the bundle 11.
The two length girders 102 are held together by one or more clamps
104 with jaws 105. The jaws 105 are brought together against the
two length girders 102 to compress the first layer of adhesive 12.
This creates a seal between the first adhesive layers 12 of the
sheets 1, as well as a seal between the length girders 102 and the
adjacent outermost first layer of adhesive 12 of the bundle 11.
Once the bundle 11 is clamped between the two length girders 102,
the exposed first layer of adhesive 12 at the sides of the bundle
11 are heated with a heat gun, or a similar heating device to glue
the sides of the sheets 1 together. Additional adhesive may be
added if necessary. The end girders 103 are preferably slightly
longer than the width of the bundle 11. The end girders 103 are
then abutted against the first layer of adhesive 12 of the bundle
11, perpendicular to the length girders 102 to create a rectangular
plate 101 . The end girders 103, like the length girders 102, are
sealed against the outermost first layer of adhesive 12 of the
bundle 11. Once in position, the end girders 103 can be bolted to
the length girders 102 with angle brackets 106 at each of the four
intersecting corners where the girders meet. The girders do not
need to be bolted together, however. The clamps 104 can be left in
place, and additional clamps 104 can be added to hold the end
girders 103 against the length girders 102 (not shown). If the
bundle 11 is cylindrical in shape (not shown), the plate may be a
collar.
[0025] FIGS. 4A and 4B are substantially the same as FIGS. 3A and
3B, respectively, the difference being that one end of a bundle 11
is covered with a permeate pan 208 to form a potting region 216.
The permeate pan 208 is an inverted bowl. The base of the pan is
open to receive the ends of the membranes 5 in a bundle 11. The
base of the permeate pan 208 seals against the top of a plate 101.
The potting region 216 is defined by a space between the plate 101,
a layer of adhesive 12 and the permeate pan 208. FIG. 4B is a cross
section of FIG. 4A viewed along the cut line B-B. Upon seating the
pan 208 on the plate 101, the pan 208 has a collection space 210 in
fluid communication with the ends of the membranes 5. The plate 101
may have rubber inserts 212 to improve the seal between the plate
101 and the base of the permeate pan 208. The permeate pan 208 is
pressed into the rubber inserts 212 of the plate 101 and held in
place with wires 214 wrapped circumferentially around both the
permeate pan 208 and the plate 101. Wires 214 are not required,
however: any sort of clamp or vice could apply pressure from the
top of the permeate pan 208 and the bottom of the plate 101. A hole
218, such as a spigot hole, may be present in the top of the
permeate pan 208. A pipe can be used in flowing a potting liquid
into the potting region 216. An end of a -up pipe 299, can be
inserted through the hole 218, down through a space between the
membranes 5, and into the potting region 216. Optionally, multiple
pipes 299 can be inserted through one or more holes 218 into the
potting region 216. Pipes 299 could also be inserted up through the
bottom of the first layer of adhesive 12 (preferably before
clamping) or through a hole made in the side of the permeate pan
208 (not shown). The pipes 299 could extend into the potting region
216 to any depth, but preferably a distance of 1/8th and 3/8ths of
the total length of the potting region 216, from both ends of the
potting region 216. Once filled with a liquid urethane (as
described below) or other resin and left to solidify into a header,
the header will be formed integrally with the membranes, the sides
of the permeate pan 208, and the top of the layer of adhesive 12.
The plate 101 and pipe(s) 299, are to be removed preferably before
the resin has completely solidified as they do not form part of the
header.
[0026] FIG. 5 shows a front cross-section view of a potting region
216 and surrounding area substantially as shown in FIGS. 4A, viewed
along cut lines C-C, filled with liquid resin 222. The potting
region 216 is the space defined by a first layer of adhesive 12, a
plate 101, and, a permeate pan 208. A liquid resin 222, is flowed
into the potting region 216 through a pipe 299, and around the
membranes 5. When a sufficient amount of liquid resin 222 is
present to form, when solidified, a header, the flow of liquid
resin 222 into the potting region 216 is stopped. The liquid resin
222 does not extend to the very ends of the membranes 5 and does
not cover or fill the ends of the membranes 5. As the liquid resin
222 is left to solidify, it forms meniscuses 226 around the
membranes. To avoid forming a meniscus, the resin may be filled to
the second layer of adhesive 13.
[0027] A protector cap 220 is optionally fit into a hole 218 to
redirect the pipe 299 downward towards the potting region 216. The
protector cap 220 is to help prevent covering or filling the ends
of the membranes 5 with a liquid resin 222 when it is being flowed
into the potting region 216.
[0028] FIGS. 6A, 6B, and 6C show side views of the process of
filling a potting region 216 with a liquid resin 222 through a pipe
299. The end of the pipe 299 is inserted through a hole 218 in a
permeate pan 208 down into the potting region 216. FIG. 7B shows
the tilting of the potting region 216 to flow the liquid resin 222
throughout the potting region 216 more quickly using the force of
gravity. The bundle 11 may be tilted in any direction to flow the
liquid resin 222 in that direction more quickly. The liquid resin
222 is not allowed to flow over the ends of the membranes 5 or
cover or fill the ends of the membranes 5. When the liquid resin
222 has reached a pre-defined level 224, which is below the ends of
the membranes 5, the bundle 11 is tilted back to a position to make
the liquid resin 222 level. The flow of liquid resin 222 from the
pipe 299 is then stopped.
[0029] FIG. 7 shows a side view of the bundle of membranes 11
fitted into the open base of a permeate pan 208. A first layer of
adhesive material 12 forms an interference fit with the walls of
the pan 208. A perfect seal is not required, however, a good fit
around the circumference of the first layer of material 12 will
limit the amount of liquid resin that may escape when the liquid
resin is flowed into the pan. Liquid resin is flowed into the
permeate pan in the same way as described in FIGS. 4 to 6. It may
be flowed in through a hole 218 in the pan 208. One or more pipes
299 and one or more protector caps 220 may be used assist with
flowing the liquid resin 222 into the pan 208. The liquid resin 222
is left to harden into a header. Once hardened, the header will be
integrally formed with the pan 208 and the bundle of membranes
11.
[0030] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *