Hollow fiber membrane contactor

【0001】

[Technical field to which the invention belongs]

The present invention relates to a hollow fiber membrane contactor.

【0002】

[Conventional technology]

Hollow fiber membrane contactors are known. For example, U.S. Pat. Nos. 3,288,877, 3,755,034, 4,220,535, 4,664,681, 4,940,617, 5,186,832, 5,264,171, 5,284,584, each of which is incorporated herein by reference. , And No. 5,449,457. Generally, such contactors utilize a thin wall membrane to separate gaseous, solid or liquid components from a solution or colloidal mixture by diffusion. Hollow fiber membrane diffusion contactor from Celgard Inc. (Charlotte, North Carolina) LIQUI-CEL^RAlso, from Dainippon Ink and Chemicals (DIC, Tokyo), "SEPAREL"^RIt is commercially available under the name of ". Such contactors have many uses, one of which is liquid degassing (degassing).

【0003】

"SEPAREL^RThe contactor features a shell that surrounds a hollow fiber cloth wrapped around a perforated core. "SEPAREL^RThe contactor uses a cloth made of polymethylpentene (PMP) hollow fibers and polyester yarn. Hollow fibers made from PMP exhibit peculiar diffusion performance as shown in Japanese Patent Application Laid-Open No. 2-102714 (published on April 16, 1990). In addition, "SEPAREL^RThe contactor operating parameters are limited to a maximum temperature of 50 ° C and a maximum supply water pressure of 0.4Mpa. For more information, please refer to the website of Dainippon Ink and Chemicals Co., Ltd. (domain name; www.dic.co.jp.), Hollow fiber film degassing module-SEPAREL.^R, Is posted.

【0004】

Commercially available PMP fabrics used in the manufacture of contactors utilize PMP hollow fibers as weft and polyester yarn as warp. This cloth tends to tear and break when wrapped under tension. Thus, the low strength is due to the use of polyester warp yarns in the production of this fabric. Polyester is a relatively rigid material that does not bend or bend sufficiently. When wrapping a PMP fabric around a mandrel, the warp absorbs most of the applied load and the fabric with polyester warp breaks and tears. It has been shown that a cloth similar to the cloth described in Japanese Patent Application Laid-Open No. 2-102714 breaks even at an essentially zero tension during winding. It is desirable to apply some wrapping tension in order to produce a well-formed fiber bundle that makes good contact within the shell of the contactor.

【0005】

Another reason for the low strength of such PMP fabrics is the inability to use sized warp threads with adequate spacing. For example, a cloth similar to the cloth (tear at the time of winding) described in aspect 3 of Japanese Patent Application Laid-Open No. 2-102714 shows a maximum number of warp threads of about 5 (threads) per inch.

【0006】

U.S. Pat. No. 4,911,846 discloses an artificial lung made of hollow fiber cord cloth. As shown in FIGS. 11 and 12 of this publication, the cord cloth contains polyolefin hollow fibers (including PMP hollow fibers) in weft and warp threads (polyester, polyamide, polyimide, polyacrylonitrile, polypropylene, polyacrylic acid ester, polyvinyl). Includes as (including alcohol etc.). The warp is a polyester or polyamide multifilament yarn having a yarn fineness of preferably 10 to 150 denier, more preferably 25 to 75 denier. However, no information is provided regarding the spacing of the warp threads or the composition of the non-polyester, non-polyamide warp threads, as shown in column 6, lines 3-14 of US Pat. No. 4,911,846.

【0007】

[Problems to be Solved by the Invention]

Therefore, there is a need for a contactor that uses a cloth that is resistant to breakage and can operate at higher temperatures and pressures than conventional PMP hollow fiber contactors.

【0008】

[Means for solving problems]

The contactor according to the present invention is for degassing (degassing) a liquid comprising a perforated core and a microporous membrane cloth wrapped around the core. This cloth contains polymethylpentene hollow fibers and polyolefin warp threads as weft threads. In a preferred embodiment, the fabric has a number of weft threads between 50 and 70 threads per inch and a number of warp threads between 3 and 12 threads per inch. The end of the wrapped cloth is fixed by the tube sheet, and the tube sheet and the wrapped cloth are put in the shell. The shell has at least one opening and an end cap that allows the liquid to flow through the shell.

【0009】

In a further aspect, the invention is a contactor for degassing a liquid, the contactor being adapted to withstand pressures greater than 0.4 MPa and temperatures greater than 50 ° C. The contactor according to this embodiment comprises a shell, polymethylpentene hollow fibers as weft threads, and warp threads, and is a microporous membrane cloth in which the number of fibers and threads driven is similar to that described above. Further included. The cloth is preferably wrapped around a perforated core and located inside the shell. The shell has at least one opening that allows the liquid to flow through the shell.

【0010】

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail with reference to the drawings. FIG. 1 shows a cross-sectional view of the contactor 10 of the hollow fiber membrane according to the present invention. The contactor 10 includes a core tube 12. The core tube 12 has a plurality of holes 14. The hollow fiber 16 surrounds the core tube 12. The shell 13 surrounds the fiber and the core tube 12. The tube sheet 26 fixes the side end of the hollow fiber 16 to the core tube 12. The side edges of the shell 13 are closed by the end cap 15.

【0011】

As shown in FIG. 1, the liquid 18 preferably enters the contactor 10 via the liquid inlet 20 of the core tube 12. The liquid 18 enters through the liquid inlet 20 of the core tube 12, and exits the core tube 12 via the hole 14 when the block 22 turns the liquid. The liquid 18 then moves over the outer surface of the hollow fibers 16. The liquid 18 re-enters the core tube 12 via the hole 14 on the other side of the block 22 and exits the core tube 12 via the liquid outlet 24. The hollow fiber 16 surrounds the core tube 12 and is held by the tube sheet 26 substantially parallel to the axis of the core tube 12. The hollow fiber 16 extends from the tube sheet 26 and has a headspace at any end of the contactor 10 such that the vacuum 30 drawn at ports 32 and 34 communicates with the lumen side of the hollow fiber 16 via the headspace 28. Communicate with 28. For example, port 34 may be used to introduce scavenging gas that facilitates removal of companion gas.

【0012】

The membrane contactor 10 is preferably an external flow, hollow fiber membrane module. The membrane contactor 10 has a lumen side and a shell side. The lumen side, also known as the internal side, is largely defined by the lumen of this hollow fiber. The shell side, also known as the external side, is partially defined by the outer surface of the hollow fibers. This liquid travels through the shell side (or outside), during which a vacuum (or vacuum and scavenging gas) is applied to the lumen side (or inside). As a result, the accompanying gas from the liquid passes from the shell side through the membrane to the lumen side by diffusion.

【0013】

Preferably, the hollow fiber 16 is a semi-permeable, gas-selective, heterogeneous, integrally asymmetric, and liquid-impermeable membrane. The membrane is preferably a monolayer membrane (eg, not a composite or multilayer membrane) and is made of a homopolymer of PMP. This film is preferably a film having a skin layer on its surface, and the skin is on the shell side. This film is 100 Barrer (10)^-8Standard cm³.cm / sec.cm²It has a permeability of less than .cm (Hg)). This is described, for example, in US Pat. No. 4,664,681, which is cited herein by reference. All membranes in the contactor are preferably 0.05 m²Larger, most preferably 0.1 m²From 350m²Has an active surface area between.

【0014】

Next, as shown in FIG. 2, the hollow fibers 16 are preferably made on a cloth 36 having weft threads 38 and warp threads 40. Preferably, the fabric is a weft-inserted knitted fabric in which the warp is a knitting yarn. The weft 38 is a hollow fiber 16. The cloth 36 preferably has a weft number of threads between 50 and 70 threads per inch, most preferably between 60 threads and 65 threads per inch.

【0015】

The warp 40 must be flexible, but strong and inactive against the liquid flowing through the contactor. The warp 40 is preferably a multifilament polyolefin yarn. Most preferably, the yarn is selected from the group consisting of polypropylene and polyethylene. The term "filament" is used in the same meaning as "cutting filament" which is also called "staple fiber". Further, in the present specification, the term "thread" includes "a thread made of a filament and a staple fiber". Preferably, the yarn is sufficiently resistant to tearing but has a fineness that is not large enough to create noticeable gaps between the fabric layers. Preferably, the warp is between 80 denier / 40 filaments (ie 80/40 yarns) and 20 denier / 10 filaments (20/10 yarns), most preferably approximately 40 denier / 20 filaments (40/20 yarns). Must. Further, the warp threads may be treated by a surface finish, for example a surface finish of silicon oil.

【0016】

The number of warp threads driven is also an important factor in the design of this fabric. If there are too few warp threads, the fabric is prone to tearing. On the other hand, too many warp threads reduce the efficiency of the contactor by blocking the surface area of the hollow fibers. In a preferred embodiment, the number of warp threads driven is between about 3 and 12 threads per inch of cloth, most preferably approximately 6 to 7 threads per inch.

【0017】

The cloth 36 and the core tube 12 are wound to form the hollow fiber unit 42. The unit 42 is preferably cylindrical. In use, the unit 42 has a diameter in the range between about 2 inches and 16 inches and a length in the range between about 8 inches and 72 inches, but with a size even larger than these diameters and lengths. It can be used. The aspect ratio of unit 42 is L / D²Is defined as. In this equation, L is the nominal length of the unit and D is the nominal diameter of the unit. Preferably, this aspect ratio is 0.1 to 6.0 inches.^-1The range between.

【0018】

Furthermore, the cloth 36 is preferably wound under tension to form a unit 42 having a filling fraction between about 35% and 45%. The filling fraction (PF) is the number of fibers (n) and the cross-sectional area (A) of each fiber._f), And the cross-sectional area of the fiber bundle (A)_{b b}It is defined as the value divided by). Here, the cross-sectional area of this fiber bundle excludes the area occupied by the core tube 12. Expressed as an expression, PF = n * A_f/ A_{b b}Will be.

【0019】

Also, PMP hollow fibers have a natural tendency to shrink with temperature. Therefore, in a preferred embodiment of the invention, the PMP cloth 36 is pre-shrinked prior to winding. A preferred method of pre-shrinking and stabilizing the fabric is to heat the fabric to an expected operating temperature of about 15 ° C. or higher for approximately 2 to 8 hours, preferably 4 hours. Heating this fabric between about 55 ° C and about 65 ° C for about 2-8 hours, preferably 4 hours, provides suitable fiber stabilization for the majority of expected applications. Pre-shrinking the fabric and wrapping it under tension helps to obtain a well-formed bundle produced by the present invention that contributes to high operating parameters (eg, temperature and pressure).

【0020】

The hollow fiber membrane unit 42 formed by the present invention may be combined with other structural elements to form a contactor. Such structural elements are well known in the art and generally consist of an outer shell, at least one opening in the shell that allows fluid to flow through the shell. Co-assigned US Patent Application No. 09 / 816,730, filed March 22, 2001, incorporated herein by reference discloses some possible structures of contactors. All of these are applicable to the present invention.

【0021】

As shown in FIG. 3, the contactor 10'is the same as the contactor 10 in FIG. 1 except that the flow diversion baffle 50 is located inside the shell and the port 34 is repositioned. .. A baffle 50 is added to facilitate the distribution of liquid on all outer surfaces of the hollow fibers 16. In this way, the position of port 34 can be changed.

【0022】

As shown in FIG. 4, the contactor 10 "is different from the contactors 10 and 10'in that the liquid outlet 24 is repositioned from the end of the core tube 12 to the shell side of the contactor 10". The vacuum 30 communicates with the headspace 28 and then with the lumen of the hollow fiber 16. The second headspace exemplified in the above embodiment has been removed. The liquid 18 enters the liquid inlet 20 of the core tube 12. The liquid 18 exits the core tube 12 via the hole 14, travels over the outer surface of the hollow fiber 16, and exits the shell side via the liquid outlet 24. The liquid outlet 24 may be placed elsewhere outside the contactor to maintain communication with the shell side.

【0023】

The present invention is not limited to the above-described embodiment, and various modifications and modifications can be made based on the technical idea of the present invention. That is, any of the methods known to those skilled in the art may be used to form the contactor described in the present invention. One such method is set forth in the co-assigned US Patent Application No. 09 / 851,242 filed May 8, 2001.

【0024】

The invention may be embodied in other particular forms without departing from the spirit or essential attributes of the invention, and thus as indicating the scope of the invention, rather than the specification above. The scope of the attached claims should be referred to.

[Simple explanation of drawings]

FIG. 1 is a cross-sectional view of a hollow fiber membrane contactor according to the present invention.

FIG. 2 is a perspective view of a hollow fiber membrane unit and a cloth used in the present invention.

FIG. 3 is a cross-sectional view showing a second aspect of the hollow fiber membrane contactor according to the present invention.

FIG. 4 is a cross-sectional view showing a third aspect of the hollow fiber membrane contactor according to the present invention.

[Explanation of symbols]

Ten Contactor 12 Core tube 16 Hollow fiber 20 Liquid inlet 22 Block 26 Tube sheet 28 Headspace 32,34 Port 36 Cloth 38 Weft 40 Warp 42 Hollow fiber unit