JP3641662B2 - Hollow fiber membrane type separation element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a hollow fiber membrane type separation element that can treat various liquids and gases in the electronics industry, food industry, pharmaceutical industry and the like.
[0002]
[Prior art]
The hollow fiber membrane separation element binds a large number of hollow fiber-like porous membranes (hereinafter simply referred to as hollow fiber membranes), fixes the ends thereof, and incorporates them into a casing to form a unit. as way of solid reduction, the until now polyurethane, but was to immobilized by an adhesive made of epoxy resin, this product has eluate adhesives, and heat resistance, poor chemical resistance Therefore, since its application is limited to water purifier relationship, recently so that integrated by filling a thermally fusible resin such as poly olefin resin between the adjacent hollow fiber membranes is known It was.
[0003]
However, in these cases, the hollow fiber membranes are crushed, the inner and outer diameters of the hollow fiber membranes are uneven, or there are insufficiently welded portions, resulting in poor sealing and bubbles remaining. In order to improve these points, the present applicant previously proposed the following hollow fiber membrane type separation element as Japanese Patent Application No. 7-73827 (Japanese Patent Laid-Open No. 8-266671).
[0004]
The outline is as shown in FIG. 8 to FIG. 10. A large number (about 400 to 600) of hollow fiber membranes made of synthetic resin such as polyolefin, polysulfone, polyvinylidene fluoride, polytetrafluoroethylene, etc. are shown in FIG. Each of the yarn membranes is bundled as shown in a) to form a hollow fiber membrane bundle 1, and this yarn membrane bundle 1 is bent into a U shape as shown in FIG. 5B, and the molten resin does not enter each yarn membrane. The tip is crushed and then inserted into the polyolefin resin cylindrical casing 2 from the side where the thread membrane bundle 1 is bundled as shown in FIG. (C), and this is provided at a predetermined position (about 10 to 40 mm) from the tip. The string is pulled up while being narrowed down by the annular protrusion 2 a and assembled into the casing 2.
[0005]
Thereafter, as shown in (d), the tube 5 for holding the shape is fitted to the outside of the casing 2, and this is held by the holder 6 from above as shown in (e) and set in the molten resin injecting machine 7. Molten resin (polyethylene) is uniformly injected from the inlet 7a between the hollow fiber membranes at the mating ends and between the inner walls of the casing 2, and the injection depth is reduced to a predetermined value (the tip) by narrowing the annular protrusion 2a. (F) is removed from the injector 7 and the holder 6 as shown in the figure, and is set in the centrifuge 8 as shown in (g) and 100 to 150 G The hollow fiber membranes and the casing 2 are joined to each other by cooling and solidifying while giving a centrifugal acceleration of a certain level and preventing the generation of voids that tend to occur when the molten resin is cooled and solidified.
[0006]
After that, the shape holding tube 5 is removed from the casing 2, and the tip part of the casing is cut about 5 to 10 mm together with the casing as shown in the figure (h), each hollow fiber membrane is opened, and (i) the figure is cut as shown in the figure. The first end plate 3 made of the same material as the casing 2 having the large diameter portion 3a and the central pipe portion 3b is welded and joined to the end side, and the dish-like second end plate 4 is welded and joined to the other end. The separated separation element E. FIG. 10 shows that the hollow fiber membrane bundle 1 is accommodated in the casing 2 without being bent, and both ends of the hollow fiber membrane bundle 1 are fixed to the inner surfaces of both ends of the casing 2 by fixing the yarn membranes one by one by the above-described manufacturing method. The end is sealed). The manufacturing process diagram of FIG. 8 illustrates an element that does not have a through hole in the peripheral surface of the casing and does not require a housing, but an exchangeable type that has a through hole and requires a housing is also included in the manufacturing process. There is no change.
[0007]
9 and 10, the exchangeable separation element E is provided with a large number of through holes 2b around it, and is housed in a steel plate housing H when used, and the pipe portion 3b of the first end plate 3 is used. A flexible seal ring 3c is attached to the center boss portion of the lid body Ha, and a coil spring S is disposed between the bottom portion of the housing H and the second end plate 4 to separate the separation element E. And the processing fluid is taken into the housing H through the inlet pipe Hb provided on the lid Ha, and the fluid enters the inside through many through holes 2b on the casing peripheral surface and is purified by crossing each hollow fiber membrane, The purified fluid is taken out from the outlet pipe Hc on the lid Ha. When each hollow fiber membrane is clogged with fine particles adhering to the surface over time, the lid Ha is removed and replaced with a new element E.
[0008]
[Problems to be solved by the invention]
Prior to the use of the separation element E, the sealing state of the fixing portion 1a of the hollow fiber membrane bundle 1 is confirmed (alcohol is introduced into the housing H from the inlet pipe Hb, and the hollow fiber membrane is wetted to After blocking the pores, compressed air with a constant pressure is fed into the housing H from the inlet pipe Hb, alcohol in the housing H is pushed out from the outlet pipe Hc, and then compressed air is fed in to generate bubbles from the outlet pipe Hc. The pressure ( bubble point value) state of the point is examined, that is, the pressure is high if there is no crack in the fixing portion 1a, and the pressure is low if there is a crack), but in this case, the polyolefin resin that forms the fixing portion 1a If there is a large difference in the melting temperature of the polyolefin resin forming the casing 2, the residual stress will occur during centrifugal cooling in the centrifuge 8. Because the crack was easily occurred in the fixed portion 1a, and a polyethylene of low density close to that of the melting point of the same system is currently in the resin forming the resin and the casing 2 to form a fixing portion 1a is. However, low-density polyethylene has low mechanical strength, and if the casing 2 has a normal outer diameter of 70 mm and a length of 250 mm or more, it may be twisted and may not be useful for holding the hollow fiber membrane bundle.
[0009]
Accordingly, an object of the present invention is not to make a crack in the fixing portion of the hollow fiber membrane bundle, and to maintain rigidity and prevent twisting even when the length of the casing is increased.
[0010]
[Means for Solving the Problems]
Based on the above problems, the present invention firstly accommodates a bundle of a plurality of hollow fiber membranes made of a polymer material inside a cylindrical casing by bending it into a U-shape, and its combined end portion has a low density. As a hollow fiber membrane type separation element that is fixed with polyethylene and fixed to the inner surface of one end of the casing, the short tube portion at one end of the casing for fixing the hollow fiber membrane bundle is formed of low density polyethylene and the short tube The main body part excluding the part is made of high-density polyethylene, a first end plate made of high-density polyethylene and having a central pipe part is attached to one end of the casing, and a second material made of the same material as the main body part of the casing is attached to the other end. An end plate is attached, and secondly, a plurality of elastic locking pieces and at least one axial groove are provided at the other end of the main body portion of the casing, and the second end plate is locked. One-stop The second end plate is detachably attached to the other end portion of the casing, and thirdly, a polymer is provided inside the cylindrical casing. The above casing for fixing a hollow fiber membrane bundle as a hollow fiber membrane type separation element that accommodates a bundle of hollow fiber membranes made of a material and fixes both ends thereof with low-density polyethylene and is fixed to the inner surfaces of both ends of the casing. A short cylinder part at both ends of the casing is formed of low density polyethylene, and a main body part excluding the short cylinder part is formed of high density polyethylene, and a first end having a central pipe portion made of high density polyethylene at one end of the casing. A plate is attached, and a second end plate made of the same material as that of the main body of the casing is attached to the other end.
[0011]
Embodiment
FIG. 1 shows an example of a casing of a separation element according to the present invention. A casing 12 has an outer diameter of about 60 to 70 mm, a thickness of about 2 to 3 mm, and a length of about 250 mm. ) To the position of about 20 to 40 mm, inward projections 12c for narrowing the hollow fiber membrane bundle are provided in an annular shape, and a number of through holes 12d are provided on the peripheral surface excluding both ends, and from one end The short cylindrical portion 12b up to the inward projection 12c is formed of low-density polyethylene (density 0.915 to 0.930 g / cm ³ , melting point 100 to 115 ° C.), and the main body portion 12a from the inward projection 12c to the other end is high. It is made of high density polyethylene (density 0.945 to 0.965 g / cm ³ melting point 125 to 135 ° C.).
[0012]
Thus, the casing 12, for example fitted in the lower mold D ₁ a short tube portion 12b of the low density polyethylene which has been preformed central as in FIG. 2, this mandrel-shaped upper mold D ₂ At the same time, the left and right split molds D ₃ are brought into contact with each other, and the molten high-density polyethylene is injected into the gap between the upper mold D ₂ and the left and right split molds D ₃ , whereby a high-density polyethylene main body 12 a And a short cylindrical portion 12b of low density polyethylene are molded as one body.
[0013]
Then, inside the casing 12, said as polio olefin, polysulfone, polyvinylidene fluoride, a large number of hollow fiber membranes made of a resin such as polytetrafluoroethylene are bundled, inserted bent in a U-shape A tube for holding the shape is fitted to the outside of one end portion of the casing 12, while the other end portion is held by a holder and set in a resin injecting machine, and melted from a low density polyethylene (density 0.919). g / cm ³ , melting point 101 ° C.) was injected between the hollow fiber membranes at the mating ends and between the inner surfaces of the short cylindrical portions 12b of the casing, and then removed from the injector and subjected to a centrifuge. Remove the rear tube, the molten resin is made a centrifugal cooled without bubbles or turbulence fixing portion 11a (FIG. 3), the fixing portion 11a is a casing 12 in company 5 Then, each hollow fiber membrane is opened by about 10 mm, and then, as shown in FIG. 3, the large-diameter portion made of the same high-density polyethylene as the main body portion 12a of the casing on one end portion of the casing 12, that is, the short cylinder portion 12b. 13a and a first end plate 13 having a central pipe portion 13b are heated and fitted by a die-shaped heater and welded, while the other end of the main body portion 12a has the same high-density polyethylene as the main body portion 12a. Similarly, the dish-shaped blind second end plate 14 is fitted and welded to form a replaceable hollow fiber membrane type separation element E.
[0014]
At the time of use, the separation element E is housed in a steel plate housing H, a seal ring 13c made of a flexible rubber material is attached to the peripheral surface of the central pipe portion 13b of the first end plate 13, and the lid Ha A coil spring S is disposed and held between the second end plate 14 and the bottom of the housing H, and the processing fluid taken in from the inlet pipe Hb of the lid Ha is much of the casing 12. The inside of the casing 12 passes through the through holes 12d and is purified by traversing the hollow fiber membranes, and the purified fluid passes through the hollow fiber membranes and exits from the fixing portion 11a into the lid Ha to exit pipe Hc. Through the outside. When each hollow fiber membrane is clogged with fine particles adhering to the surface over time, the lid Ha is removed and replaced with a new element E.
[0015]
In this case, since the short tube portion 12b of the fixing portion 11a and the casing 12 at one end of the hollow fiber membrane bundle is formed of a low density polyethylene having the same structure, without causing cracks in the fixed portion 11 a, sufficient airtightness It holds, and since the main body portion component 12a of the casing 12 is formed of high density polyethylene, to maintain a high mechanical strength.
[0016]
Figure 4 shows a modification of the casing 12, in the longitudinal direction of the inner wall thickness of a plurality (two in the figure) to the other end of the body portion 12a of the casing 12 made of high density polyethylene in this example The elastic locking pieces 12e thus formed are provided at intervals in the circumferential direction, and a plurality of axial grooves 12f (this may be one) are formed by shifting the positions thereof.
[0017]
FIG. 5 shows a modified example of the second end plate made of the same material, which is provided with a window hole 14a and a fluid through hole 14c for latching the locking piece 12e of the casing 12 on the peripheral surface. A protrusion 14b that engages with the axial groove 12f of the casing 12 is formed on the peripheral surface, and a circular protrusion 14d for receiving a spring and a central through hole 14e are provided on the end surface.
[0018]
The second end plate 14 has a method in which the protrusion 14b on the inner peripheral surface is fitted in the groove 12f of the casing and positioned at the other end while being positioned, and the locking piece 12e of the casing 12 is locked in the window hole 14a. Thus, it is detachably attached to the other end of the casing 12. When the second end plate 14 is used, the processing fluid enters the casing 12 also from the through hole 14c on the peripheral surface and the through hole 14e on the end surface. The reason for making the second end plate 14 in this way is that in the replaceable element using the U-shaped hollow fiber membrane bundle 11, the second end plate 14 is not necessarily blind and is fixed to the casing 12. This is because the length of the casing 12 can be changed.
[0019]
The whole is made of the same high-density polyethylene as that of the casing body, has a required length (same as casing 12 in the figure) as shown in FIG. Like the two end plate 14, it is provided with a window hole 15a and an axial protrusion 15b, and is formed to have a slightly larger diameter, and the other end is elastic to the peripheral surface like the other end of the casing 12. A splicing casing 15 provided with a locking piece 15e and an axial groove 15f is used, one end of which is detachably coupled to the other end of the casing 12, and a long U-shaped hollow fiber membrane bundle 11 inside. If the second end plate 14 is detachably attached to the other end, a separation element E having a large processing capacity can be obtained.
[0020]
In the above example, the hollow fiber membrane 11 is bent in a U-shape inside the casing 12 and its end portion is fixed to the inner surface of one end portion of the casing 12. Not limited to this, as shown in FIG. 7, the short cylinder portions 12b at both ends of the casing 12 are formed of low density polyethylene, and the main body portion 12a excluding those short cylinder portions 12b is formed of high density polyethylene, and the casing 12 is hollow. The yarn membrane bundle 11 is accommodated in a straight line without being bent, and the yarn membranes at both ends thereof are fixed with low-density polyethylene (in this case, one end cuts the fixing portion to open the hollow fiber membrane, but the other end And may be fixed to the inner surfaces of the short cylindrical portions at both ends of the casing 12. In this case, the fixing with the molten resin and the cooling of the molten resin are performed in accordance with the above-mentioned steps in order one by one on both ends of the casing. In the above example, the through hole 12d is provided on the peripheral surface of the casing 12 to be used in a replaceable manner, but the housing may not be provided without providing the through hole 12d. In this case, the other end fixing portion 11a is cut in the same manner as the one end fixing portion to open the hollow fiber membrane, and the second end plate 14 has a central pipe portion like the first end plate 13, Further, a filtrate outlet is provided in the middle of the casing 12.
[0021]
【The invention's effect】
As described above, the present invention accommodates a bundle of hollow fiber membranes made of a polymer material in a cylindrical casing by bending it into a U shape, fixing its mating end with low-density polyethylene, and one end of the casing. As a hollow fiber membrane type separation element that is fixed to the inner surface of the part, the sealed state is sufficiently maintained without causing cracks in the fixing part of the hollow fiber membrane bundle by being configured as in claims 1 and 3. In addition, the casing can have a high strength, can be long without fear of being twisted, and, if constructed as in claim 2, the length of the casing can be increased by using a member. Therefore, the processing capability of the separation element can be improved.
[Brief description of the drawings]
FIG. 1 is a half sectional side view of an example of a casing of a separation element according to the present invention.
FIG. 2 is an explanatory view of how to make a casing.
FIG. 3 is a half sectional side view showing a use state of a separation element according to the present invention.
FIG. 4 is a perspective view of a modified example of the casing.
FIG. 5 is a perspective view of a modified example of the second end plate.
FIG. 6 is a half sectional side view of an example in which the length is increased.
FIG. 7 is a half cross-sectional side view showing a use state of an example in which both ends are fixed.
FIG. 8 is a manufacturing process diagram of the prior art.
FIG. 9 is a half sectional side view showing a state of use of a prior art element having one end fixed.
FIG. 10 is a half cross-sectional side view showing the state of use of a prior art element with both ends fixed.
[Explanation of symbols]
11 Hollow fiber membrane bundle 11a Fixed portion 12 Casing 12a Main body portion 12b Short tube portion 12c Inward projection 13 First end plate 13b Central pipe portion 14 Second end plate 15 Additional casing E Separating element H Housing

Claims (3)

Inside the cylindrical casing, a bundle of a large number of hollow fiber membranes made of a polymer material is folded and stored in a U shape, and the matching end is fixed with low-density polyethylene and fixed to the inner surface of one end of the casing. In the hollow fiber membrane type separation element, the short cylinder part at one end of the casing for fixing the hollow fiber membrane bundle is formed of low density polyethylene and the main body part excluding the short cylinder part is formed of high density polyethylene, A hollow fiber membrane type characterized in that a first end plate made of high-density polyethylene and having a central pipe portion is attached to one end of the casing, and a second end plate made of the same material as the casing main body is attached to the other end. Separation element.   A plurality of elastic locking pieces and at least one axial groove are provided at the other end of the main body of the casing, and a window hole for locking the latching piece and a groove for fitting the groove are formed on the second end plate. The hollow fiber membrane type separation element according to claim 1, wherein the second end plate is detachably attached to the other end of the casing. In a hollow fiber membrane type separation element that accommodates a bundle of hollow fiber membranes made of a polymer material inside a cylindrical casing, and fixes both ends thereof with low-density polyethylene and fixes them to the inner surfaces of both ends of the casing, The short cylinder part at both ends of the casing for fixing the hollow fiber membrane bundle is formed of low density polyethylene and the main body part excluding the short cylinder part is formed of high density polyethylene, and one end of the casing is made of high density polyethylene. A hollow fiber membrane type separation element, wherein a first end plate having a central pipe portion is attached and a second end plate made of the same material as that of the main body of the casing is attached to the other end.

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