JP2008221108A - Liquid separation membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure which reduces the flow resistance of filtered water and a back washing solution, excellent in back-washability, and also excellent in productivity with respect to an inner pressure type liquid separation hollow fiber membrane module. <P>SOLUTION: The inner pressure type liquid separation hollow fiber membrane module is characterized in that the flow channel width coefficient R = (Le×Db<SP>2</SP>)/N/(Dc<SP>2</SP>-Db<SP>2</SP>)/Dc<SP>1/3</SP>satisfies 2 or higher and 10 or lower when Db is the outer diameter of a bundle of the separation hollow fiber membranes; Le is the efficient length of the hollow fiber membranes; and N is the number of the outlets of filtered water used simultaneously among the outlets of filtered water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal structure of an internal pressure type hollow fiber type liquid separation membrane module.

  In recent years, the spread of separation and purification technology using membrane separation technology has been highly appreciated due to its high-level separation function and energy saving features. Examples of its application fields are production of fresh water by desalination of seawater and brine, surface water and groundwater drinking water, production of pure water and ultrapure water used in the semiconductor industry and pharmaceutical industry, household wastewater and industrial wastewater, Sewerage treatment of municipal sewage and water recovery from wastewater, recovery of valuable materials from fermentation liquor and waste liquid, etc., liquid treatment field, oxygen enrichment and nitrogen enrichment from air, helium recovery from natural gas It is widely used in a wide range of fields, such as gas separation fields such as carbon dioxide separation in the third recovery of oil.

  A fluid separation membrane is a liquid separation membrane such as a reverse osmosis membrane, nanofiltration membrane, ultrafiltration membrane, microfiltration membrane, or oxygen-enriched membrane, nitrogen separation membrane, carbon dioxide gas separation based on the separation target and separation mechanism. It is classified as a gas separation membrane such as a membrane. On the other hand, when focusing on the form of the fluid separation membrane, it is classified into a hollow fiber membrane, a tubular membrane, a flat membrane, a spiral membrane and the like. In the present invention, among the liquid separation membranes, the invention is particularly concerned with the internal pressure type hollow fiber type liquid separation membrane. Hereinafter, in the present invention, unless otherwise specified, the membrane module refers to an internal pressure type hollow fiber type liquid separation membrane that is assembled in a usable state by connecting a pipe.

  In recent years, there has been a worldwide movement to utilize a membrane filtration method using an ultrafiltration membrane and a microfiltration membrane as a turbidity removal means in water purification treatment. One of the reasons is that it is highly evaluated for its high filtration accuracy compared to the sand filtration method that has been widely used for water purification treatment in the past, and high removability of pathogenic protozoa having resistance to chlorine such as Cryptosporidium. it is conceivable that. In order to further spread the membrane filtration method, it is required to reduce the equipment cost and the operation cost. In order to meet such a demand, various improvements are being made to the membrane module and the membrane filtration system. For example, in order to reduce the operating cost, increase the water permeability per operating pressure, improve the ratio of the production water volume to the supply water volume, that is, the recovery rate, reduce the frequency of chemical washing, extend the membrane life, Etc. are considered effective. Further, it is considered effective to reduce the facility cost by increasing the water permeation amount per membrane module volume, increasing the size of the membrane module, and the like.

  From such a background, conventionally, as an improvement of the membrane module, an increase in the size of the membrane module and an increase in the amount of permeated water per membrane area have been promoted. However, this increases the pressure loss related to the permeate flow in the membrane module and decreases the amount of water per operating pressure, and increases the pressure loss related to the backwash liquid flow in the membrane module to reduce the cleaning efficiency and compensate for it. For this reason, the amount of cleaning liquid is increased to compensate for the increase in the amount of cleaning liquid, the reduction in the recovery rate, the backwashing pressure of the part far from the backwashing liquid inlet at the time of backwashing is reduced, and the part is not washed sufficiently. Problems such as an increase and a decrease in recovery rate, a decrease in film life, or an increase in the frequency of drug washing have become apparent. The following techniques which are considered to be useful for solving these problems are disclosed in the patent literature.

Patent Document 1 discloses a technique of providing a discharge thin film made of a double wall having a wave shape or a hole over substantially the entire length in the longitudinal direction of a capillary filtration membrane. The discharge thin film is connected to a discharge conduit provided in the center of the case in the longitudinal direction of the case, and the permeated water is discharged to the outside of the module through the discharge conduit. On the other hand, the discharged thin film serves as a backwash liquid channel for introducing backwash liquid outside the module during backwashing. According to this configuration, it is possible to prevent damage to the hollow fiber membrane due to a strong flow of permeated water, and it is possible to increase the filling membrane area as compared with the case where a discharge pipe is provided, and to improve the filtration capacity of the module. Are listed. However, since the discharge thin film is connected to the discharge conduit, the number of members is large, the structure is complicated, and the productivity is poor. In addition, it is complicated to uniformly and densely fill the hollow fiber membrane in the gap of the discharge thin film with a cross-sectional fan shape, and the packing density of the membrane cannot be increased, so it is inferior in compactness and inferior in productivity. There is.
JP 2000-246063 A

In Patent Document 2, a cylindrical water collecting body having at least a part of a net-like portion is provided at the center of the case, and a module for backwashing liquid at the time of draining permeated water out of the module and backwashing through this is provided. A technique for introducing the information into the network is disclosed. When this technology is applied to a membrane module having a permeated water outlet on the outer peripheral surface of the case, a communication channel that connects the water collector and the permeated water outlet is necessary. For this reason, the internal structure of the module becomes complicated, resulting in a problem that the productivity is inferior. In addition, since the flow path connecting the water collector and the permeate outlet is formed, it is impossible to fill the portion with a hollow fiber membrane, which reduces the effective membrane area and lacks compactness. End up.
JP 2005-270944 A

Patent Document 3 describes a technique for installing a hollow core membrane bundle in a protective cylinder formed with a constricted portion. According to this invention, the flow outside the hollow fiber membrane is improved and a module can be manufactured at low cost. Has been. However, the operation of filling the hollow cylinder with the constricted protective cylinder is complicated and difficult, and not only the productivity is inferior, but also there is a problem that the hollow fiber membrane may be damaged in the production process. .
Japanese Patent Laid-Open No. 10-337449

  The present invention has been made against the background of such prior art problems. That is, the object of the present invention is, firstly, the pressure loss in the permeate chamber that becomes the flow path of the permeate during permeation is low, and the pressure loss in the permeate chamber that becomes the flow path of the backwash liquid during backwashing is low. It is another object of the present invention to provide an internal pressure type hollow fiber type liquid separation membrane module with high energy efficiency and long life, in which the entire membrane module is uniformly washed. Second, it is to provide an internal pressure type hollow fiber type liquid separation membrane module that is simple in structure and excellent in productivity while solving the first problem.

As a result of intensive studies, the present inventors have found that the above two problems can be solved simultaneously by the means described below, and have reached the present invention. That is, this invention consists of the following structures.
(1) A cylindrical case having one or more permeate outlets on the outer peripheral surface,
A hollow fiber membrane bundle is provided in the cylindrical case,
The hollow fiber membrane bundle is sealed between the hollow fiber type separation membranes and between the hollow fiber type separation membranes and the cylindrical case at both ends, and the hollow fiber membrane bundles are sealed in the hollow fiber type separation membranes at both ends of the cylindrical case. The cavity is open,
It comprises a substantially annular space in cross section that is a gap between the hollow fiber membrane bundle and the cylindrical case, and includes a permeate chamber that communicates with the permeate outlet,
The inner diameter of the tubular case at the outlet of the permeate chamber is Dc, the outer diameter of the bundle of hollow fiber separation membranes is Db, the effective length of the hollow fiber membrane is Le, and the permeate outlet used simultaneously among the permeate outlets. Where N is N, the following formula (1)
R = (Le × Db ² ) / N / (Dc ² −Db ² ) / Dc ^1/3 (1)
An internal pressure type hollow fiber type liquid separation membrane module characterized in that the flow path width coefficient R defined by
(2) The internal pressure type hollow fiber type liquid separation membrane module according to (1), wherein the flow path coefficient R is 3 or more and 9 or less.
(3) For the permeate chamber in the cross section that includes the center of the permeate outlet and is orthogonal to the long axis of the case, the width on the permeate outlet side is Lf, and the width on the opposite side of the permeate outlet is Lb. The internal pressure type hollow fiber type liquid separation membrane module according to (1) or (2), wherein Lf / Lb> 1.
(4) The internal pressure type hollow fiber type liquid separation membrane module according to any one of (1) to (3), wherein a width of the permeate chamber is Lf / Lb ≧ 1.5.

  According to the present invention, it is possible to reduce the operating pressure and the backwash pressure, and the energy efficiency is improved. In addition, since the entire membrane can be washed uniformly during backwashing, it is possible to reduce backwashing time, use backwashing liquid, extend backwashing interval, and extend membrane life, improve energy efficiency during operation, This has the effect of reducing costs. Furthermore, since the internal structure of the membrane module is simplified, the manufacturing cost of the membrane module is reduced.

  Here, the case where purified water is obtained from surface water or groundwater using an internal pressure type hollow fiber type liquid separation membrane module will be described as an example.

  FIG. 1 is a schematic view showing an entire internal pressure type hollow fiber type water purification membrane module as an example of an embodiment in the case where there is one permeated water outlet 110 in the vicinity of the end with respect to the axial direction of the case. The membrane module includes a cylindrical case 100 and a pair of caps 200 and 300 that close the end portions in the axial direction. The case 100 and the caps 200 and 300 are fastened by fastening means 700. Inside the case 100, a hollow fiber membrane bundle 400 having a circular outer cross-sectional outer diameter made up of a number of hollow fiber membranes 410 wrapped in a hollow fiber membrane protection cylinder 420 is arranged so as to extend in the axial direction of the case. ing. The outer peripheral surface of the hollow fiber membrane protection cylinder 420 has a net shape or a wall shape with a large number of holes through which water can be passed with a water flow resistance that is negligibly small compared to the transmembrane pressure difference. The raw water is filtered by the hollow fiber membrane 410 to purify the water. The upper end portion and the lower end portion of each hollow fiber membrane 410 are sealed and fixed to the case body 100 by a sealing resin 500. That is, the sealing resin 500 is filled in the gap between the hollow fiber membranes 410 and the gap between the hollow fiber membrane 410 and the inner wall surface of the case 100, thereby fixing the hollow fiber membranes 410 in a liquid-tight manner. In the hollow fiber membrane 410, the upper and lower ends thereof are opened, and only the upper end and the lower end are fixed with the sealing resin 500, and the other intermediate portion fulfills the water purification function. The permeate chamber 800 is a space having a substantially annular cross section that is a gap between the case 100 and the hollow fiber membrane bundle 400, and the upper and lower ends thereof are separated by the upper end portion and the lower end sealing resin 500. A permeate outlet 110 is formed near the upper end of the permeate chamber 800. On the other hand, the caps 200 and 300 are made of cap-shaped cap bodies 210 and 310, and openings 220 and 320 are formed, respectively. An air vent 120 (not shown) may be formed near the upper end of the permeate chamber. Further, a drain port 130 (not shown) may be formed near the lower end of the permeate chamber.

  The flow of water when membrane filtration is performed by crossflow and when backwashing is described with reference to FIGS. As shown in FIG. 3, the pressurized raw water is supplied to the inside of the hollow fiber membrane through the opening 220, and a part or all of the raw water passes through the hollow fiber membrane and passes through the permeate outlet 110 to the outside of the membrane module. This flows into the production water, and the remainder flows out of the membrane module through the opening 320 without being filtered. Since raw water contains various contaminants, when the membrane filtration is continued, the contaminants accumulate on the membrane surface and increase the membrane filtration resistance. In order to remove the contaminants and prevent the membrane filtration resistance from increasing, it is common to perform backwashing periodically at intervals of several tens of minutes to several hours. In that case, the permeated water outlet 110 functions as a backwash liquid inlet, and as shown in FIG. 4, clean water or oxidizer such as chlorine, acid, alkali, surfactant, or these agents can be removed from the permeated water outlet 110. Pressurize and supply clean water containing a suitable cleaning agent such as a mixture and exhaust through one or both of the openings 220, 320. The backwash flow rate is appropriately adjusted according to conditions such as the degree of increase in membrane filtration resistance, the amount and type of contaminants, backwash time, type of cleaning liquid, etc. Generally, it is about 1.5 to 5 times. Dispersed in the permeate outlet 110 so that a large force is applied to the hollow fiber membrane in the front portion of the permeate outlet 110 due to the direct hit of the cleaning liquid flowing in from the permeate outlet 110, and the hollow fiber membrane is not damaged. A plate 600 is installed. FIG. 2 shows a schematic perspective view of an example of a preferred embodiment of the dispersion plate 600. If it is not desirable that the cleaning agent contained in the backwash liquid is mixed into the production water, it is recommended that the cleaning agent be mixed into the production water by rinsing with clean water or discarding the initial filtered water. Can be prevented.

  The inventors of the present invention initially produced a prototype membrane module by contacting the outer periphery of the hollow fiber membrane protective cylinder 420 with the inner periphery of the case 100 in the membrane module having the same structure as in FIG. We experienced that the water permeability of the prototype membrane module was extremely inferior to that of the hollow fiber membrane. Comparative Example 1 described later is an example of such a situation. As a result of various studies on this phenomenon, it has been found that the pressure outside the hollow fiber membrane at a position far from the permeate outlet is so high that it is not significantly different from the supply pressure, and the effective transmembrane pressure is small. Since the hollow fiber membrane bundle is filled with the hollow fiber membrane at a high density, a large pressure loss occurs when the permeated water flows in the hollow fiber membrane bundle, and the outside of the hollow fiber membrane bundle is also in contact with the case. The gap was very narrow, and it was thought that a large pressure loss occurred with respect to the flow of permeate. Based on the above consideration, the present inventors have realized that it is advantageous to form a permeate chamber extending in the axial direction of the membrane module and secure a permeate flow path even if the amount of the filled membrane is reduced, As a result of further investigations, it became clear that an excellent membrane module can be obtained when the dimensions of the case and the hollow fiber membrane bundle are in a specific relationship. That is, when membrane modules having various dimensions were prototyped and the relationship between the operating pressure and the transmembrane pressure difference was studied, the membrane module in which the channel width coefficient R, which is a newly set parameter, is a value within a specific range. However, it has been found that the above-mentioned problems can be solved.

  If the hollow fiber membrane bundle outer diameter Db is excessively large with respect to the case inner diameter Dc, problems such as large flow resistance in the permeate chamber occur, which is inappropriate. At this time, the channel width coefficient R becomes large. On the other hand, if the hollow fiber membrane bundle outer diameter Db is too small with respect to the case inner diameter Dc, the flow resistance in the permeate chamber is small, but the effective membrane area is small and sufficient water permeability cannot be obtained. At this time, the channel width coefficient R becomes small. Further, when the effective length Le / N of the hollow fiber membrane per the number of permeate outlets is large, it is necessary to increase the flow path width of the permeate chamber accordingly, and conversely, when Le / N is small Accordingly, if the flow path width of the permeate chamber is not reduced, the production efficiency per module volume is deteriorated, but the flow path width coefficient R can be used as an index for setting the flow path width. The channel width coefficient R is preferably 2 or more and 10 or less, more preferably 3 or more and 9 or less.

Now, what the channel width coefficient R = (Le × Db ² ) / N / (Dc ² −Db ² ) / Dc ^1/3 means means in three parts. . First, (Le × Db ² ) / N is a value related to the amount of water per one permeate outlet. Le × Db ² is proportional to the volume of the portion effective for liquid separation of the hollow fiber membrane bundle. This is divided by the number N of permeate outlets used at the same time, and (Le × Db ² ) / N is the volume of the portion effective for liquid separation of the hollow fiber membrane bundle per permeate outlet. The effective membrane area in the hollow fiber membrane bundle is a function of the volume of the membrane bundle, the inner and outer diameters of the hollow fiber membrane, and the filling factor in the membrane bundle, and therefore (Le × Db ² ) / N is per permeate outlet. It can be seen that this is a function of the effective membrane area. Since it is widely used to set or analyze the permeation amount per effective membrane area in setting the operating conditions and operating behavior of the fluid separation membrane module, (Le × Db ² ) / N is permeated water. It can be understood that this is a value related to the amount of water per one outlet. Second, Dc ² -Db ² is a value proportional to the cross-sectional area of the permeate chamber if the hollow fiber membrane bundle outer shape is circular, and approximates the cross-sectional area of the permeate chamber even when the hollow fiber membrane bundle outer shape is not circular. Proportionally proportional value. Therefore, it can be understood that it is related to the flow resistance of the permeated water. Third, Dc ^1/3 is an adjustment coefficient for making the membrane module capable of solving the above-described problems within a common range of the channel width coefficient R even when the case inner diameter Dc is different, and is simply (Le × Db ² ) / N / (Dc ² −Db ² ), a suitable numerical range that shifts when the case inner diameter Dc is different is adjusted. The number N of permeate outlets used at the same time refers to the number of permeate outlets used as the permeate outlet during regular permeation operation for obtaining product water. exclude.

  The cross-sectional outer shape of the hollow fiber membrane bundle in the present invention is substantially circular. The substantially circular range in the present invention includes a circle, an ellipse, a regular polygon having 6 or more sides, and a rounded corner of the regular polygon. If the cross-sectional outer diameter of the hollow fiber membrane bundle is substantially circular, a useless space does not occur in the case, and the filling efficiency of the hollow fiber membrane can be increased, which is preferable. In addition, a hollow fiber membrane bundle is formed in advance in any shape of these cross-sectional outer diameters, and the flow path width of the permeate outlet side on the permeate outlet side is widened at the end adhesion part or permeate outlet facing part. When end bonding is performed while pushing the hollow fiber membrane bundle in this way, a part of the outer shape of the hollow fiber membrane bundle is distorted, and this is also cited as a preferred cross-sectional outer shape of the hollow fiber membrane bundle. It is particularly preferable that the hollow fiber membrane bundle has a circular shape, an elliptical shape, and a shape obtained by distorting a part thereof, from the viewpoint of simplifying the manufacturing process of the hollow fiber membrane bundle and providing high reproducibility.

The outer diameter Db of the hollow fiber membrane bundle is determined as follows. FIGS. 5A to 5C are cross-sectional views in a cross section that is perpendicular to the long axis of the cylindrical case and includes the center of a specific permeate outlet in an example of an embodiment of the present invention. On the left section,
1) Assume an auxiliary line 1001 connecting the center of the specific permeate outlet with the center of the case as the origin. The direction from the origin to the center of the specific permeate outlet is set to 0 °.
2) Let Db (1) be the diameter of the cross-sectional outline of the hollow fiber membrane bundle on the auxiliary line 1001.
3) The auxiliary line 1003 perpendicular to the auxiliary line 1001 is set at a position where the hollow fiber membrane bundle diameter becomes the maximum projected length Db (3).
4) Auxiliary lines are taken in the 45 ° and 135 ° directions clockwise from the 0 ° direction so as to pass through the intersection of the auxiliary line 1001 and the auxiliary line 1003 to be auxiliary lines 1002 and 1004, respectively. The diameters of the hollow fiber membrane bundles on the auxiliary lines 1002 and 1004 are Db (2) and Db (4), respectively.
5) Calculate Db by the following formula.
Db = {Db (1) + Db (2) + Db (3) + Db (4)} / 4 (2)
However, if the cross-sectional outer shape of the hollow fiber membrane bundle is circular, the diameter is Db. Further, the outer shape of the hollow fiber membrane bundle on the cross section perpendicular to the long axis of the cylindrical case and including the center of the specific permeate outlet is the same as the outer shape of the hollow fiber membrane bundle on the module end surface. In such a case, the same measurement as described above is performed on the module end face. In any case, when the hollow fiber membrane bundle is covered with a water-permeable material such as a net-like body, the hollow fiber membrane bundle diameters Db and Db (1) to Db (4) It is set as the value measured without including the thickness.

  The case inner diameter Dc is the case inner diameter on the auxiliary line 1001.

  When there are a plurality of permeate outlets 110 to be used simultaneously, R is calculated for each permeate outlet, and the average value is preferably 2 or more and 10 or less, and more preferably 3 or more and 9 or less.

  Here, the hollow fiber membrane bundle 400 may be composed of small bundles of a plurality of hollow fiber type separation membranes. The cross-sectional outer shape of the small bundle may be any shape such as a circle, an ellipse, a polygon, and a fan. Further, a gap (hereinafter referred to as a gap between the small bundles) may be formed between the small bundles. When the gaps between the small bundles are formed, the gaps between the small bundles also flow in the permeated water and backwash water in cooperation with the permeate chamber 800 which is the gap between the outer periphery of the hollow fiber membrane bundle and the inner surface of the case. It functions as a channel and has the effect of reducing the flow pressure loss in the hollow fiber membrane bundle. Providing the gap between the small bundles is effective when the outer diameter of the hollow fiber membrane bundle is large, and is particularly effective when the outer diameter of the hollow fiber membrane bundle is 100 mm or more. Between the small bundle gaps may be filled with a water permeable filler, and such an embodiment is suitable for the small bundle due to deformation of the small bundle even when there is a flow of permeated water and backwash water at a high flow rate. It is preferable because the clogging between the bundle gaps does not occur and the flow pressure loss effect is surely exhibited.

  When filling the water-permeable filler between the small bundle gaps, it is not always necessary to fill the entire gap between the small bundles. The filling body may not be filled in a portion where the flow rates of the permeated water and the backwash liquid are small, such as a portion far from the permeated water outlet. The left permeable filling body preferably has a maximum length in the case axial direction of 60% or more of the effective length of the hollow fiber membrane and not more than the case length, and communicates with the permeate chamber. Preferred examples of the left-hand filler include a laminate of mesh sheets and a three-dimensional mesh body having a high porosity and a large pore diameter. For example, a three-dimensional network having a structure in which a net-like sheet having a thickness of about 0.5 to 5 mm is laminated or a large number of bent filaments having a wire diameter of about 0.5 to 5 mm are bonded to each other at the contact portion. Is mentioned.

  The permeate chamber 800 may be partially or entirely filled with a water-permeable filler as long as the flow resistance of the permeate and the backwash water is not greatly increased. When the permeated liquid chamber 800 is filled with the water permeable filler, it is not always necessary to fill the entire permeated liquid chamber. It may be partially filled, and it may not be filled in a portion where the flow rate of the permeated liquid and the backwash liquid is small, such as a part far from the permeated liquid outlet 110. In addition, it is preferable that the portion near the permeate outlet 110 is not filled with a filler, or a filler with particularly low water permeability is used. This is because the flow rate per channel cross-sectional area in this part is particularly high compared to other parts in the membrane module, and thus reducing the flow resistance in this part is highly effective in reducing the flow pressure loss in the permeate chamber. It is preferable that the permeated liquid chamber permeable filler has a length of 60% to 100% of the distance from the end of the case to the permeated liquid outlet and communicates with the permeated liquid chamber. Preferred examples of the permeate chamber filling material include a laminate of mesh sheets and a three-dimensional mesh body having a high porosity and a large pore diameter. For example, a three-dimensional network having a structure in which a net-like sheet having a thickness of about 0.5 to 5 mm is laminated, or a large number of bent filaments having a wire diameter of about 0.5 to 5 mm are bonded to each other at the contact portion. Is mentioned. Moreover, when a thing with high rigidity is used for a permeate liquid filling body, there exists an effect which suppresses a deformation | transformation of a hollow fiber membrane bundle when operating a membrane module by a large flow rate, and it is preferable.

  Further, FIG. 1 shows the case where the permeate outlet 110 is located near the end of the case 100. However, as shown in the embodiment of FIGS. It may be near the center. 7 and 8, an air vent 120 is provided near the upper end of the permeate chamber 800, and a drain port 130 is provided near the lower end of the permeate chamber 800. When there is air in the permeate chamber 800 when starting up the operation of the membrane module, the air in the permeate chamber 800 is permeated by the permeated water when the air vent 120 is opened and the drain port 130 is closed and the supply of raw water is started. Then, the air vent 120 is closed and the membrane filtration operation is started. Further, when the liquid in the permeate chamber 800 is to be discharged, such as when the membrane module is detached from the membrane filtration device, when the air vent 120 is opened and the drain port 130 is opened, air is passed from the air vent 120 to the permeate chamber. It flows in and the liquid in the permeate chamber 800 is discharged.

  Considering the flow distribution of the permeated water in the case, the permeated water gathers on the permeated water outlet side where the outlet from the membrane module is located, and thus the flow rate in the vicinity thereof becomes maximum. Therefore, the cross-sectional area of the flow path near the permeate outlet can also be increased by decentering the center of the hollow fiber membrane bundle from the center of the case to the opposite side of the permeate outlet, or by changing the inner diameter of the case and increasing the vicinity of the permeate outlet. It is possible to expand and reduce the flow resistance, and it is preferable to use such measures together in the present invention. The embodiment of FIG. 8 is a schematic view when the center axis of the hollow fiber membrane bundle 400 is decentered from the center axis of the case 100 to the side opposite to the permeate outlet 110, and the embodiment of FIG. It is a schematic diagram at the time of changing and making the permeate outlet 110 vicinity thick.

In the present invention, the channel widths Lf and Lb of the permeate chamber 800 functioning as a permeate channel are defined as follows. FIG. 6 is a cross section at a portion corresponding to the AA cross section of FIG. 1 in an example of an embodiment in which the central axis of the hollow fiber membrane bundle 400 is decentered from the central axis of the case 100 to the side opposite to the permeate outlet. It is a schematic diagram of a surface. On the left section,
1) Assume an auxiliary line 1001 connecting the center of the case 100 and the center of the specific permeate outlet 110. The direction from the origin to the center of the specific permeate outlet is set to 0 °.
2) Of the gap width between the case 100 and the hollow fiber membrane bundle 400, the width in the 0 ° direction is Lf, and the width in the 180 ° direction is Lb.
However, the outer shape of the hollow fiber membrane bundle 400 on the cross section perpendicular to the major axis of the cylindrical case 100 and including the center of the specific permeate outlet 110 and the outer shape of the hollow fiber membrane bundle 400 on the module end surface are If they are the same, the same measurement as described above is performed on the module end face. In any case, when the hollow fiber membrane bundle is covered with a water-permeable material such as a mesh, the thickness of the water-permeable material is included in the width of the gap between the hollow fiber membrane bundle and the case. To do.

  If Lf / Lb slightly exceeds 1, an eccentric effect is produced, but to obtain a clear effect, Lf / Lb is preferably 1.5 or more, and if Lf / Lb is 2 or more, further preferable. On the other hand, since the hollow fiber membrane bundle on the opposite side of the permeate outlet 110 may be in contact with the inner periphery of the case, the upper limit of Lf / Lb is infinite. However, unnecessarily increasing Lf is not a good idea because it leads to a reduction in the amount of hollow fiber membranes that can be filled in the membrane module. In consideration of this point, Lf is preferably 20% or less of the case inner diameter Dc. More preferably, it is 10% or less.

  The case 100 in the present invention is a substantially cylindrical container filled with a liquid separation membrane, and has at least one permeate outlet 110 on the outer peripheral surface thereof. The permeated water outlet 110 on the left functions as a fluid inlet / outlet port. In the usage state of the liquid separation membrane, both ends of the case are coupled to the cap, or a bottom portion integral with the case is formed. An opening may be formed in the bottom integral with the left cap or case. The material of the case and cap is not particularly limited, but engineering plastics such as vinyl chloride resin and polysulfone resin, various reinforced resins such as glass fiber reinforced resin, and corrosion-resistant metal materials such as stainless steel are suitable. The glass fiber reinforced resin is particularly lightweight as a case material because it is lightweight and excellent in corrosion resistance and has good adhesion to the liquid separation membrane sealing resin. Stainless steel is particularly preferable as a cap material because it is excellent in strength and corrosion resistance and can be easily connected to external piping. The case and cap may be uneven or colored according to functional or design requirements.

  Moreover, it is preferable that the caps 200 and 300 in the present invention include an end plate as a constituent element. There are various types of end plates, such as a dish shape, a regular semi-ellipsoidal shape, an approximate semi-elliptical shape, a hemispherical shape, and a flat mirror shape, and any shape may be used. By providing the end plate as a constituent element, the thickness can be reduced compared with a simple bottomed cylindrical type, and the weight can be reduced and the cost can be reduced.

  The fastening method of case 100 and caps 200 and 300 in the present invention is not limited to a specific method. It may be screwed, or a flange provided on the case and the cap may be fastened by a bolt and nut or a swing bolt and nut. Moreover, it is also possible to connect by various pipe joints, and V band coupling, a victic joint, and a strub coupling (registered trademark) are examples of suitable fastening methods.

  The material of the hollow fiber type separation membrane in the present invention is not particularly limited. Preferable examples of the membrane material include organic polymer compounds such as polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, polyamide, and cellulose acetate, and copolymers, mixtures, and modified products containing these. Also, a ceramic film may be used. Further, the separation mode of the hollow fiber type separation membrane is not particularly limited. Any separation mode such as reverse osmosis membrane, nanofiltration membrane, ultrafiltration membrane, microfiltration membrane, etc. may be used.

  As mentioned above, although the example of the embodiment of this invention was demonstrated, this invention is not limited to these, A various change is possible unless it deviates from the meaning.

  In addition, the liquid separation membrane module is a water purification membrane module made of an internal pressure type hollow fiber membrane, and the above explanation has been given by taking the case of operating by a cross flow filtration method as an example. The present invention can be similarly applied. Further, the use thereof is not limited to the water purification treatment, and it can be similarly applied to those having different uses of the liquid separation membrane such as waste water treatment and pretreatment of seawater desalination reverse osmosis membrane.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

(Method for producing hollow fiber membrane and method for measuring water permeability of hollow fiber membrane)
Polyethersulfone (manufactured by Sumitomo Chemical Co., Ltd., Sumika Excel (registered trademark) 4800G) and polyvinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., K-30) were heated and dissolved in a mixed solution of dimethylacetamide and triethylene glycol to obtain a spinning dope. . Discharge the spinning stock solution from the outer slit of the double tube nozzle, and simultaneously discharge the aqueous solution of dimethyl ace, amide and triethylene glycol from the inner tube of the double tube nozzle, and after passing through the air, the aqueous solution of dimethylacetamide and triethylene glycol It was led to a coagulation bath consisting of and solidified. Washing with water and hot water washing were carried out, followed by drying with a hot air drier to obtain a hollow fiber membrane having an inner diameter of 0.8 mm and an outer diameter of 1.4 mm. The transmembrane pressure difference 0 extrapolation value of the water permeation flux at a water temperature of 25 ° C. was 30 m ³ / m ² / d / 100 kPa.

(Manufacture of hollow fiber membrane bundles)
Using the hollow fiber membrane described above, a bundle of 1.2 m long hollow fiber membranes was made, and the outer peripheral portion of the bundle was covered with a polyethylene net (thickness 1.5 mm) to obtain a predetermined outer diameter. The number of hollow fiber membranes used here was adjusted so that the filling rate in the hollow fiber membrane bundle was constant. Here, the filling rate in the hollow fiber membrane bundle is the ratio of the total cross-sectional area of the hollow fiber membrane including the hollow fiber membrane lumen to the hollow fiber membrane bundle cross-sectional area in the cross section of the hollow fiber membrane bundle. When the diameter is OD and the number of filled hollow fiber membranes is n, (OD ² × n) / Db ² × 100 (%).

(Manufacture of membrane modules)
The hollow fiber membrane bundle covered with the net-like body was inserted into a substantially cylindrical case having a length of 1066 mm provided with a permeate outlet centered at a position 130 mm from one case end. Both ends were bonded with a urethane resin adhesive to seal between the hollow fiber membranes and the gap between the case and the hollow fiber membrane, and then the portion protruding from the case end was cut off to open the hollow fiber membrane. The effective length of the hollow fiber membrane (the length of the portion not buried in the sealing portion) was 890 mm. Caps were attached to both ends of the case, and a dispersion plate was attached to the permeate outlet to form a membrane module.

(Measurement method of water permeability of membrane module)
A schematic flow diagram of the apparatus used for measuring the water permeability of the membrane module is shown in FIG. The water temperature was adjusted to 25 ± 1 ° C., and the flow rate and pressure were adjusted by adjusting the flow rate adjusting valves 2101, 2102, 2103, and the total amount filtration operation was performed. At that time, the feed water temperature, the permeate flow rate and the operating pressure were measured. As the supply water, water in which tap water was permeated through a reverse osmosis membrane was used. The transmembrane pressure difference P was set to P = (P1 + P2) / 2−P3 with respect to the pressures P1, P2, and P3 in the pressure gauges 2201, 2202, and 2203.

(Examples 1-3 and Comparative Examples 1-3)
Using a case made of glass fiber reinforced resin (case inner diameter Dc = 300 mm), the cross-sectional outer shape is circular, the hollow fiber membrane bundle filling ratio is 56.4%, and the hollow fiber membrane bundle outer diameter Db is 230 to 297 mm. A membrane module was manufactured. For each, the transmembrane pressure difference required to obtain a permeate flow rate of 20 m ³ / hr was measured.
In the case where the outer diameter Db of the hollow fiber membrane bundle Db = 297 mm where the mesh body on the outer periphery of the hollow fiber membrane bundle is in contact with the inner diameter of the case (Comparative Example 1), the channel width coefficient R = 65.5, and the transmembrane pressure difference Even at 200 kPa, the amount of permeated water did not reach 20 m 3 / hr, and the efficiency was extremely poor. On the other hand, in the case of the hollow fiber membrane bundle outer diameter Db = 250, 270, 280 mm (Examples 1, 2, 3), the channel width coefficient R is 3.0, 5.7, 9.0, respectively. The transmembrane pressure difference was 44, 40, 45 kPa. Not only was the improvement significantly compared to Comparative Example 1, but the same amount of permeated water was obtained with a lower transmembrane pressure difference compared to Comparative Examples 2 and 3 described later, and the energy efficiency was high. On the other hand, when the hollow fiber membrane bundle outer diameter Db = 230, 290 mm (Comparative Examples 2 and 3), the channel width coefficient R was 1.9 and 19.0, respectively, and the transmembrane pressure difference was 51 and 89 kPa. Compared with Examples 1 to 3, a high transmembrane pressure difference was required, and energy efficiency was low. The test results are summarized in Table 1 and FIG.

(Examples 4 and 5 and Comparative Examples 4 and 5)
Case made of hard vinyl chloride resin (case inner diameter Dc = 150 mm), circular outer cross section, hollow fiber membrane bundle filling ratio 54.2%, hollow fiber membrane bundle outer diameter Db = 110-142 mm, Lf / Lb = 1 And produced a test module. For each, the transmembrane pressure difference required to obtain a permeate flow rate of 5 m ³ / hr was measured.
In the case of the hollow fiber membrane bundle outer diameter Db = 125,138 mm (Examples 4 and 5), the channel width coefficients R were 3.8 and 9.2, respectively, and the transmembrane pressure difference was 45 and 50 kPa. Compared to Comparative Examples 4 and 5 described later, the same permeated water amount was obtained with a low transmembrane pressure difference, and the energy efficiency was high. On the other hand, in the case of the hollow fiber membrane bundle outer diameter Db = 110, 142 mm (Comparative Examples 4 and 5), the channel width coefficient R was 1.9 and 14.5, respectively, and the transmembrane pressure difference was 56 and 73 kPa. It was. Compared to Examples 4 and 5, a high transmembrane pressure difference was required, and the energy efficiency was poor. The test results are summarized in Table 2 and FIG.

(Examples 6 and 7)
In Example 1, Lf / Lb was changed by shifting only the position of the hollow fiber membrane bundle, and a test module was manufactured. The channel width coefficient R is 9.0 in all cases.
When the transmembrane pressure difference required to obtain the permeation flow rate of 20 m ³ / hr was measured in the same manner as in Example 1, when Lf / Lb = 1.9, 3 (Examples 4 and 5), the transmembrane difference The pressure was 42,41 kPa. Compared to Example 1 described above, the same amount of permeate was obtained with a lower transmembrane pressure difference, and the energy efficiency was further increased. The test results are summarized in Table 3 and FIG.

(Example 8)
In Example 1, the hollow fiber membrane bundle was further pushed from the permeate outlet using a dispersion plate to set Db = 280 mm and Lf / Lb = 2. The channel width coefficient R is 9.0. As in Example 5, when the transmembrane pressure difference required to obtain a permeation flow rate of 20 m ³ / hr was measured, the transmembrane pressure difference was 42 kPa, which was further improved as compared with Example 1. The test results are summarized in Table 3.

  According to the liquid separation membrane module of the present invention, the operating pressure can be reduced, and the operating cost can be reduced and the energy efficiency can be improved. In addition, since the cleaning liquid can uniformly clean the entire membrane module during backwashing, there are effects of reducing the frequency of chemical washing and extending the membrane life. These effects are beneficial for users of liquid separation membrane devices.

It is a mimetic diagram of an internal pressure type hollow fiber type water purification membrane module of an example of an embodiment of the present invention. FIG. 1A is a schematic diagram of the entire membrane module, and FIG. 1B is a schematic diagram of the AA cross section of FIG. It is a perspective schematic diagram of an example of the embodiment of the dispersion plate 600 used with the internal pressure type hollow fiber type water purification membrane module of an example of the embodiment of the present invention. It is a schematic diagram which shows the flow of the water at the time of filtration of the internal pressure type | formula hollow fiber type water purification membrane module of an example of the embodiment of this invention. It is a schematic diagram which shows the flow of the water at the time of backwashing of the internal pressure type | formula hollow fiber type water purification membrane module of an example of the embodiment of this invention. It is a schematic diagram for demonstrating the procedure which determines Db and Dc in this invention. It is a schematic diagram for demonstrating the procedure which determines Lf and Lb in this invention. It is a mimetic diagram of an internal pressure type hollow fiber type water purification membrane module of an example of an embodiment of the present invention. FIG. 7A is a schematic diagram of the entire membrane module, and FIG. 7B is a schematic diagram in the AA cross section of FIG. 7A. It is a mimetic diagram of an internal pressure type hollow fiber type water purification membrane module of an example of an embodiment of the present invention. FIG. 8A is a schematic diagram of the entire membrane module, and FIG. 8B is a schematic diagram in the AA cross section of FIG. 8A. It is a mimetic diagram of an internal pressure type hollow fiber type water purification membrane module of an example of an embodiment of the present invention. FIG. 9A is a schematic diagram of the entire membrane module, and FIG. 9B is a schematic diagram of the AA cross section of FIG. 9A. It is a schematic flowchart of the apparatus which performed the water-permeable performance measurement of the membrane module in the Example and comparative example of this invention. ³ is a graph showing the relationship between the channel width coefficient R and the transmembrane pressure difference required to obtain a permeation flow rate of 20 m ³ / hr in Examples 1 to 3 and Comparative Examples 2 and 3 of the present invention. 4 is a graph showing the relationship between the channel width coefficient R and the transmembrane pressure difference required to obtain a permeation flow rate of 5 m ³ / hr in Examples 4 and 5 and Comparative Examples 4 and 5 of the present invention. ³ is a graph showing the relationship between Lf / Lb and transmembrane pressure difference required to obtain a permeation flow rate of 20 m ³ / hr in Example 1 and Examples 6 to 8 of the present invention.

Explanation of symbols

100: Case 110: Permeated water outlet 120: Air vent 130: Drain port 200: Lower cap 210: Lower cap body 220: Lower cap opening 300: Upper cap 310: Upper cap body 320: Upper cap opening 400: Hollow fiber membrane bundle 410: hollow fiber membrane 420: hollow fiber membrane protective cylinder 500: sealing resin 600: dispersion plate
610: Dispersion plate shielding portion 620: Dispersion plate fixing portion 630: Dispersion plate support portion 700: Fastening means 800: Permeate chambers 1001, 1002, 1003, 1004: Auxiliary line 2001: Supply water tank 2002: Temperature control device 2003: Stirring Machine 2004: Supply pump 2005: Membrane modules 2101, 2102, 2103: Flow rate adjusting valves 2201, 2202, 2203: Pressure gauge 2301: Flowmeter

Claims (4)

A cylindrical case having one or more permeate outlets on the outer peripheral surface,
A hollow fiber membrane bundle is provided in the cylindrical case,
The hollow fiber membrane bundle is sealed between the hollow fiber type separation membranes and between the hollow fiber type separation membranes and the cylindrical case at both ends, and the hollow fiber membrane bundles are sealed in the hollow fiber type separation membranes at both ends of the cylindrical case. The cavity is open,
It comprises a substantially annular space in cross section that is a gap between the hollow fiber membrane bundle and the cylindrical case, and includes a permeate chamber that communicates with the permeate outlet,
The inner diameter of the tubular case at the outlet of the permeate chamber is Dc, the outer diameter of the bundle of hollow fiber separation membranes is Db, the effective length of the hollow fiber membrane is Le, and the permeate outlet used simultaneously among the permeate outlets. Where N is N, the following formula (1)
R = (Le × Db ² ) / N / (Dc ² −Db ² ) / Dc ^1/3 (1)
An internal pressure type hollow fiber type liquid separation membrane module characterized in that the flow path width coefficient R defined by   The internal pressure hollow fiber type liquid separation membrane module according to claim 1, wherein the flow path coefficient R is 3 or more and 9 or less.   With respect to the permeate chamber in a cross section that includes the center of the permeate outlet and is orthogonal to the long axis of the case, Lf is the width on the permeate outlet side and Lb is the width on the opposite side of the permeate outlet. The internal pressure type hollow fiber type liquid separation membrane module according to claim 1 or 2, wherein / Lb> 1. The internal pressure type hollow fiber type liquid separation membrane module according to any one of claims 1 to 3, wherein a width of the permeate chamber is Lf / Lb≥1.5.

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