JP2012030194A - Hollow yarn membrane module, hollow yarn membrane module filter, and seawater desalting pretreatment filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow yarn membrane module that secures a sufficient flux to enable efficient filtering treatment, and a hollow yarn membrane module filter.SOLUTION: The hollow yarn membrane module to be used in the hollow yarn membrane module filter for filtering raw water from the outer surface of a hollow yarn membrane to the inner surface thereof, includes the hollow yarn membrane bundle wherein a plurality of hollow yarn membranes having opening ends are arranged with predetermined gaps and the sealing end member provided to one end of the hollow yarn membrane bundle to seal and fix the end parts on the side opposite to the opening ends of the hollow yarn membranes. Opening parts for supplying raw water to the gaps are provided in the sealing end member. In the hollow yarn membrane module filter with the hollow yarn membrane module housed in an outer cylinder, a raw water supply port is provided at one end of the outer cylinder, while a filtered water takeout port is provided at the other end of the outer cylinder, and the hollow yarn membrane module is arranged so that the sealing end member provided in the hollow yarn membrane module faces the raw water supply port.

Description

  TECHNICAL FIELD The present invention relates to a hollow fiber membrane module, a hollow fiber membrane module filtration device, and a seawater desalination pretreatment filtration device. The present invention relates to a membrane module filtration device and a seawater desalination pretreatment filtration device.

  In recent years, a hollow fiber membrane module filtration device that filters raw water such as seawater using a hollow fiber membrane module formed by concentrating a plurality of hollow fiber membranes in a wastewater treatment system or a seawater desalination system has been proposed. ing. And as the filtration method, compared with the method of filtering from the inner surface side of the hollow fiber membrane to the outer surface side (internal pressure method), the membrane area contributing to filtration per unit volume can be secured large, and the cost In general, a method of filtering from the outer surface side to the inner surface side of the hollow fiber membrane (external pressure type) is widely adopted (for example, Patent Documents 1 and 2).

JP-A-5-57154 JP-A-5-212254

  However, even with an external pressure type, it is difficult to say that the conventional hollow fiber membrane module filtration device has a sufficient flux (unit area, filtration amount per unit time), and more efficient filtration treatment. Was desired.

  Therefore, the present invention provides a hollow fiber membrane module, a hollow fiber membrane module filtration device, and a seawater desalination pretreatment filtration device that can secure a sufficient flux and perform a more efficient filtration treatment. Let it be an issue.

  As a result of diligent research, the present inventor has found that the above problems can be solved by the invention shown in the following claims, and has completed the present invention. Hereinafter, each bill will be described.

The invention described in claim 1
A hollow fiber membrane module used in a hollow fiber membrane module filtration device that filters raw water from the outer surface side to the inner surface side of the hollow fiber membrane,
A hollow fiber membrane bundle in which a plurality of hollow fiber membranes having open ends are arranged with a predetermined gap;
Provided with one end of the hollow fiber membrane bundle, and a sealing end member that seals and fixes an end opposite to the opening end of the hollow fiber membrane,
The hollow fiber membrane module is characterized in that an opening for supplying raw water to the gap is provided in the sealing end member.

  In order to solve the above-mentioned problems, the present inventor has analyzed and examined the conventional hollow fiber membrane module from various aspects such as its structure and filtration mechanism. As a result, in the conventional hollow fiber membrane module, since the raw water is not sufficiently supplied as much as the hollow fiber membrane closer to the center of the hollow fiber membrane bundle, the flow of the raw water in the hollow fiber membrane module is not uniform. It was found that it was difficult to obtain a sufficient flux as the entire hollow fiber membrane module.

  This will be described in detail with reference to FIG. FIG. 8 is a diagram schematically showing the configuration of a conventional hollow fiber membrane module filtration device, where (a) is a cross-sectional view of the entire device, and (b) is a plan view of a sealed end. As shown in FIG. 8 (a), in the conventional hollow fiber membrane module filtration device, the hollow fiber membrane module 51 forms a hollow fiber membrane bundle 53 by converging a number of hollow fiber membranes 52, and the hollow fiber membrane bundle A sealed end member 54 that seals and fixes one end of each hollow fiber membrane 52 is provided at one end of the bundle 53, and the sealed end member 54 faces the raw water supply port 58 of the outer cylinder 55. As shown in FIG. As the sealing end member 54, as shown in FIG. 8B, a disk-shaped flat plate having no opening is used. In addition, 60 and 61 are the raw | natural water drains used, for example at the time of the cleaning etc. in the outer cylinder 55, for example.

  The raw water taken in from the raw water supply port 58 of the outer cylinder 55 is changed in flowing direction by the sealing end member 54, and the gap 56 between the hollow fiber membrane bundle 53 and the outer cylinder 55, that is, the hollow fiber membrane bundle 53. Is further supplied to the gaps between the hollow fiber membranes 52 from the outer peripheral portion of the hollow fiber membrane bundle 53.

  The raw water reaching the outer surface of each hollow fiber membrane 52 is filtered from the outer surface side of the hollow fiber membrane 52 toward the inner surface side. The filtered filtered water is sent inside the hollow fiber membrane 52 toward the water collecting chamber 57 and is sent from the filtered water outlet 59 to a water storage container or the like separately provided outside.

  However, the supply of raw water to the gap between the hollow fiber membranes described above is not uniform between the outer periphery and the inside of the hollow fiber membrane bundle, and the hollow fiber membrane closer to the center of the hollow fiber membrane bundle has more raw water. It is hard to be supplied to. For this reason, sufficient flux cannot be obtained as the whole hollow fiber membrane module.

  On the other hand, in the invention of this claim, since the opening for supplying the raw water is provided in the sealing end member, the raw water taken in from the raw water supply port is sent to the outer peripheral portion of the hollow fiber membrane bundle. In addition, the raw water can be sufficiently supplied to the gap between the hollow fiber membranes that are directly supplied to the inside of the hollow fiber membrane bundle through the opening, and arranged inside the hollow fiber membrane bundle. For this reason, the flux of each hollow fiber membrane inside the hollow fiber membrane bundle is improved, and raw water can be uniformly supplied to the entire hollow fiber membrane bundle. Can be secured. As a result, sufficient filtration performance can be exhibited and efficient filtration treatment can be performed.

  The shape of the opening is not limited as long as raw water can be supplied to the gap between the hollow fiber membranes, but in terms of ease of processing for the sealed end member, a circular shape is preferable. It is determined appropriately depending on the diameter and number of hollow fiber membranes, the size of the hollow fiber membranes, and the like. Each hollow fiber membrane is arrange | positioned so that an opening part may be avoided.

The invention described in claim 2
2. The hollow fiber membrane module according to claim 1, wherein the opening is provided only in a central portion of the sealing end member.

  According to the inventor's experiment, the flow rate of the hollow fiber membrane module as a whole is greater when the openings are provided only at the center than when the openings are provided around the center of the sealing end member. Is big.

  This is because, when a plurality of openings are provided around the center of the sealed end member, raw water supplied from many openings collides with each other, but the center of the sealed end member of the hollow fiber membrane module When the openings are provided only in the openings, the raw water does not collide with each other and spreads efficiently and uniformly from the inner side to the outer side of the hollow fiber membrane bundle, so the flux in each hollow fiber membrane increases. It seems to have been.

The invention according to claim 3
The sealing end member is provided with a suppressing member that suppresses the flow of raw water to the outer peripheral portion of the hollow fiber membrane module on the outer peripheral portion of the surface opposite to the surface in contact with the hollow fiber membrane bundle. The hollow fiber membrane module according to claim 1 or 2.

  By providing a suppression member that suppresses the flow of the raw water to the outer peripheral portion of the hollow fiber membrane module on the outer peripheral portion of the surface opposite to the surface with which the hollow fiber membrane bundle of the sealing end member contacts, more raw water can be obtained. Then, it is guided to the opening of the sealed end member, and a large amount of raw water can be directly supplied into the hollow fiber membrane bundle.

  Examples of such a restraining member include a cylindrical member (skirt), a disk-shaped plate projecting outward from the sealing end member, and an O-ring provided on the outer periphery of the sealing end member. The shape is not limited as long as the flow of raw water to the outer peripheral portion of the hollow fiber membrane module can be suppressed. Among these suppressing members, a cylindrical member (skirt) is preferable because of its excellent suppressing effect.

The invention according to claim 4
The hollow fiber membrane module according to any one of claims 1 to 3, wherein the hollow fiber membrane module filtration device is housed in an outer cylinder,
A raw water supply port is provided at one end of the outer cylinder, and a filtered water outlet is provided at the other end,
The hollow fiber membrane module filtration device, wherein the hollow fiber membrane module is disposed so that a sealing end member provided in the hollow fiber membrane module faces the raw water supply port.

  The hollow fiber membrane module is accommodated in the outer cylinder by arranging a sealing end member provided with an opening for supplying raw water in the gap between the hollow fiber membranes so as to face the raw water supply port of the outer cylinder. Therefore, as described above, the raw water from the raw water supply port can be directly supplied to the inside of the hollow fiber membrane bundle from the opening, and the flow rate of the hollow fiber membrane inside the hollow fiber membrane bundle can be improved.

The invention described in claim 5
The hollow fiber membrane module filtration device according to claim 4, wherein a suppression member that suppresses inflow of raw water into a gap formed by the hollow fiber membrane module and the outer cylinder is provided. is there.

  By providing a restraining member that suppresses the inflow of raw water into the gap formed by the hollow fiber membrane module and the outer cylinder, more raw water is guided to the opening of the sealed end member, and the hollow fiber membrane bundle Since more raw water can be supplied to the inside of the hollow fiber membrane bundle, the flow rate of the hollow fiber membrane inside the hollow fiber membrane bundle can be further improved.

  As described above, the suppressing member may be provided on the sealed end member side of the hollow fiber membrane module, but may be provided on the outer cylinder side.

The invention described in claim 6
A seawater desalination pretreatment device equipped with two types of filtration devices,
At least one of the two types of filtration devices is constituted by the hollow fiber membrane module filtration device according to claim 4 or 5, and is a seawater desalination pretreatment filtration device.

  The hollow fiber membrane module of the present invention can be applied to direct filtration system filtration, but is provided at the front stage of the RO membrane in a seawater desalination system that performs desalination by desalting using a reverse osmosis membrane (RO membrane). It can be applied as a pretreatment device. By using in this way, it is because the seawater desalination processing system which can suppress effectively the clogging (fouling) of RO membrane and can maintain a high flux can be comprised. Furthermore, it was found that the effects of the present invention are remarkably exhibited when applied to, for example, two-stage filtration using membranes having different pore sizes.

  In particular, by applying to a two-stage filtration device using a filtration membrane (LF membrane) having a pore diameter exceeding 1 μm in the previous stage of a filtration membrane (MF membrane) having a pore diameter of 0.1 to 1 μm, Combined with the characteristics, it is possible to provide a seawater desalination pretreatment filtration device that exhibits extremely high filtration performance. The same effect can be obtained when an LF membrane or MF membrane is used at the front stage and an ultrafiltration membrane (UF membrane) is used at the rear stage.

  According to the present invention, the flux of the hollow fiber membrane module can be increased, and a more efficient filtration process can be performed.

(A) is sectional drawing which shows typically the longitudinal cross-section of the hollow fiber membrane module of the 1st Embodiment of this invention, (b) is a top view of a sealing edge part. It is sectional drawing which shows typically the cross section in the upper surface of the sealing end member of the hollow fiber membrane module of the 1st Embodiment of this invention, (a) is an example in which the radial flow path space is not provided. (B) shows an example in which the flow path space is provided. It is sectional drawing which shows typically the cross section in the upper surface of the sealing end member of the hollow fiber membrane module of the 2nd Embodiment of this invention, (a) is an example in which the radial flow path space is not provided. (B) shows an example in which the flow path space is provided. It is a flowchart which shows the process of the pre-processing at the time of desalinating seawater, The figure (a) is a flowchart of two-stage filtration, The figure (b) is a flowchart of direct filtration. It is sectional drawing which shows typically the cross section in the upper surface of the sealing end member of the hollow fiber membrane module of a comparative example. It is a graph which shows the filtration test result of the Example of this invention. It is a graph which shows the filtration test result of a comparative example. (A) is sectional drawing which shows the longitudinal cross-section of the conventional hollow fiber membrane module typically, (b) is a top view of a sealing edge part.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

(First embodiment)
FIG. 1A is a sectional view schematically showing a longitudinal section of the hollow fiber membrane module according to the first embodiment of the present invention, and FIG. 1B is a plan view of a sealed end portion. FIG. 2 is a cross-sectional view schematically showing a cross section of the top surface of the sealed end member of the hollow fiber membrane module according to the first embodiment of the present invention, and (a) is provided with a radial flow path space. (B) shows an example in which the flow path space is provided. In FIG. 1, the number of hollow fiber membranes is reduced in order to avoid complication of the drawing, and the dimensional relationship of each member is appropriately changed from the actual one and displayed.

  The hollow fiber membrane module 1 according to the present embodiment includes a plurality of hollow fiber membranes 2 constituting a hollow fiber membrane bundle 3 and a sealed end member 4 that closes and seals and fixes the lower ends of the hollow fiber membranes 2. Have. Further, the hollow fiber membrane module 1 has one opening 4 a in the center of the sealing end member 4 and a substantially cylindrical channel space 12 a in which the hollow fiber membrane 2 is not provided in the center of the hollow fiber membrane bundle 3. have. Further, a skirt 4 b for preventing the raw water supplied from the raw water supply port 8 from flowing outside the hollow fiber membrane bundle 3 is provided on the outer peripheral portion of the sealing end member 4 on the raw water supply port 8 side. . The upper end of the hollow fiber membrane 2 opens into the water collection chamber 7, and the filtered water filtered by the hollow fiber membrane 2 is collected in the water collection chamber 7 and discharged from the filtered water outlet 9. In addition, 13 is a support | pillar.

  The hollow fiber membrane module 1 configured as described above is housed in the outer cylinder 5 and used for filtration such as seawater desalination. The hollow fiber membrane bundle 3 may have a simple structure as shown in FIG. 2 (a), but may be necessary depending on the diameter of the hollow fiber membrane, the size of the gap between the hollow fiber membranes, the number of hollow fiber membranes, and the like. Accordingly, for example, as shown in FIG. 2B, the radial flow path space 12 may be provided so that the hollow fiber membrane bundle is divided into six at intervals of 60 degrees. Further, the outer shape of the hollow fiber membrane bundle 3 is not a close-packed hexagon as shown in FIGS. 2 (a) and 2 (b), but is rounded along the inner wall of the outer cylinder 5 so that a gap between the outer fiber 5 and the outer cylinder 5 is provided. It may be small.

  According to the hollow fiber membrane module 1 according to the present embodiment, since the opening 4a for supplying raw water is provided in the sealing end member 4, the raw water taken in from the raw water supply port 8 becomes a hollow fiber membrane bundle. 3 is also supplied directly to the inside of the hollow fiber membrane bundle 3 through the opening 4a, and the raw water is also sufficiently supplied to the gap between the hollow fiber membranes arranged inside the hollow fiber membrane bundle 3. Can be supplied. For this reason, the flow rate of each hollow fiber membrane 2 inside the hollow fiber membrane bundle 3 is improved, and the raw water can be uniformly supplied to the entire hollow fiber membrane bundle 3. A good flux can be secured.

(Second Embodiment)
FIG. 3 is a cross-sectional view schematically showing a cross section of the top surface of the sealed end member of the hollow fiber membrane module 1 according to the second embodiment of the present invention. The hollow fiber membrane module 1 according to the present embodiment is different from the hollow fiber membrane module according to the first embodiment in the cross section of the substantially cylindrical channel space in the opening 4a and the hollow fiber membrane bundle 3. The difference is that six are arranged at equal intervals on the outer periphery of the central portion.

  As in the first embodiment, the flow path space 12 does not have to be provided as shown in FIG. 3A if necessary, and the flow path space extends radially from the center as shown in FIG. 3B. 12 may be provided.

  Also in the hollow fiber membrane module according to the present embodiment, since the opening 4a is provided in the hollow fiber membrane bundle 3, compared with the conventional hollow fiber membrane module that supplies raw water from the outer periphery of the hollow fiber membrane module. Thus, the flux can be increased. Furthermore, since a plurality of openings 4a are provided, the difference in flux between the plurality of hollow fiber membranes can be reduced.

  Hereinafter, the present invention will be described in more detail with reference to an example in which the hollow fiber membrane module of the present invention is used for seawater desalination.

(Filtering process in seawater desalination)
First, the filtration process relating to the present embodiment will be briefly described. FIG. 4 is a flowchart showing a step of pretreatment (filtration before performing reverse osmosis) when desalinating seawater using, for example, a reverse osmosis method. FIG. 4 shows two methods as preprocessing. In the first method, after the first-stage filtration of seawater using a hydrophobic or hydrophilic filter membrane (LF membrane) having a pore diameter of more than 1 μm, for example, 2 μm, a fine pore size of 0.1 to 1 μm is obtained. The second method is a method of directly filtering seawater (only the MF membrane) using a filtration membrane (MF membrane). In the examples described below, seawater was filtered by these two methods, and the flux was examined. The hollow fiber membrane module of the present invention can be applied to any filtration using an LF membrane and an MF membrane, but the hollow fiber membrane module of this example is used in microfiltration (MF). . Although the hollow fiber membrane module of the present invention may be configured by an MF membrane as shown in FIG. 4 and the examples, the hollow fiber membrane module of the present invention is not limited to this and is configured by an LF membrane. Alternatively, it may be used as a front-stage module for two-stage filtration using a UF membrane in the rear stage.

(Examples and comparative examples)
Next, examples and comparative examples will be described. Examples 1 to 5 and Comparative Examples 1 and 2 were carried out by combining the following hollow fiber filtration membrane modules and filtration methods. In addition, the content of the combination of each Example and a comparative example is collectively described in Table 2 with an evaluation result.

1. Hollow fiber membrane module and filtration method First, a hollow fiber membrane module and a filtration method will be described.
(1) Hollow fiber membrane module As a hollow fiber membrane module, the material is polytetrafluoroethylene (PTFE), and a hollow fiber membrane having a total length of 1200 mm and an effective length of 1000 mm is used. Three types of hollow fiber membrane modules were prepared. The configuration of these hollow fiber membrane modules is shown in Table 1. The material of the hollow fiber membrane is preferably PTFE, but is not limited to this as long as the effect of the module structure of the present application can be obtained, and other hollow fiber membranes can be applied.

In addition, the diameter of a sealing end member is 80 mm, and the structure of the cross section of each type is as follows.
Type 1
Cross-sectional structure: Structure type 2 shown in FIG.
Cross-sectional structure: structure shown in FIG. 3B of the second embodiment Aperture number (number of holes): 6 holes Aperture diameter (hole diameter): 8 mm
Type 3
Cross-sectional structure: structure shown in FIG. 2A of the first embodiment Aperture number (hole number): 1 hole Aperture diameter (hole diameter): 10 mm

  As the outer cylinder, an outer cylinder having an outer diameter of 114 mm was used.

(2) Filtration method Filtration was performed by the following three methods (filtration methods).
Hydrophobic two-stage: the first-stage filtration using a hydrophobic LF membrane and the hollow fiber membrane module of the present embodiment
Two-stage filtration method combined with microfiltration using a slurry Hydrophilic two-stage: Combines the first stage filtration using a hydrophilic LF membrane and the same microfiltration as a hydrophobic second stage
Combined two-stage filtration method Direct filtration: Direct microfiltration of seawater

2. Filtration test Next, the filtration test will be described.
(1) Filtration test method Seawater is supplied at a substantially constant pressure of 0.05 MPa and subjected to total filtration (a method of filtering the entire amount of membrane feed water), and the amount of filtrate water is measured at each filtration elapsed time to obtain a flux (m / D).

(2) Filtration test results

  The filtration test results are summarized in Table 2. Moreover, the filtration test result of the total filtration of Examples 1-5 is shown in FIG. 6, and the filtration test result of the total filtration of Comparative Examples 1 and 2 is shown in FIG.

  From Table 2, FIG. 6, and FIG. 7, it was confirmed that the flux of the example was larger than that of the comparative example. The large flux in the example is that the sealing end member of the hollow fiber membrane module and the hollow fiber membrane bundle are each provided with an opening and a substantially cylindrical channel space, and further provided with a skirt. This is because the raw water can easily flow through the hollow fiber membrane bundle and spread more evenly throughout the hollow fiber membrane bundle. Further, from Table 2 and FIG. 6, it was found that a larger flux can be obtained by providing one opening in the central portion than providing six openings in the sealing end member.

  The flux after 60 minutes is larger in the two-stage filtration method than in the direct method, and the decrease in the flux is suppressed. This is because clogging of the MF membrane is suppressed by two-stage filtration.

  As mentioned above, according to this invention, since the flux at the time of filtering water can be enlarged, water treatment, such as desalination of seawater and wastewater treatment, can be performed more efficiently.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1,51 Hollow fiber membrane module 2,52 Hollow fiber membrane 3,53 Hollow fiber membrane bundle 4,54 Sealing end member 4a Opening 4b Suppression member (skirt)
5, 55 Outer cylinder 6, 56 Gap 7, 57 Catchment chamber 8, 58 Raw water supply port 9, 59 Filtrated water outlet 10, 11, 60, 61 Raw water drain port 12, 12a Channel space 13 Strut

Claims (6)

A hollow fiber membrane module used in a hollow fiber membrane module filtration device that filters raw water from the outer surface side to the inner surface side of the hollow fiber membrane,
A hollow fiber membrane bundle in which a plurality of hollow fiber membranes having open ends are arranged with a predetermined gap;
Provided with one end of the hollow fiber membrane bundle, and a sealing end member that seals and fixes an end opposite to the opening end of the hollow fiber membrane,
An opening for supplying raw water to the gap is provided in the sealed end member.   2. The hollow fiber membrane module according to claim 1, wherein the opening is provided only in a central portion of the sealing end member.   The sealing end member is provided with a suppressing member that suppresses the flow of raw water to the outer peripheral portion of the hollow fiber membrane module on the outer peripheral portion of the surface opposite to the surface in contact with the hollow fiber membrane bundle. The hollow fiber membrane module according to claim 1 or 2. The hollow fiber membrane module according to any one of claims 1 to 3, wherein the hollow fiber membrane module filtration device is housed in an outer cylinder,
A raw water supply port is provided at one end of the outer cylinder, and a filtered water outlet is provided at the other end,
The hollow fiber membrane module filtration device, wherein the hollow fiber membrane module is disposed so that a sealing end member provided in the hollow fiber membrane module faces the raw water supply port.   The hollow fiber membrane module filtration device according to claim 4, wherein a suppression member that suppresses inflow of raw water into a gap formed by the hollow fiber membrane module and the outer cylinder is provided. A seawater desalination pretreatment device equipped with two types of filtration devices,
6. A seawater desalination pretreatment filtration device, wherein at least one of the two types of filtration devices is constituted by the hollow fiber membrane module filtration device according to claim 4 or 5.

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