JPH1128342A - Cartridge filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the local clogging of a filter membrane by uniformizing the flux of the liquid passing through the filter membrane, in a cartridge filter having a core and the filter membrane provided around the core, by providing a first cylindrical structure inside the core and further providing a second cylindrical structure inside the first cylindrical structure. SOLUTION: In a pleats type filter membrane cartridge filter, a filter membrane 13 is pleated in a state sandwiched by liquid permeable sheets 12, 14 and wound around a core 15a. An outer peripheral guard 11 is provided to the outside thereof to protect the filter membrane 13. A cylindrical structure 15b is provided inside the core 15a and, further, a cylindrical structure 15c is provided inside the structure 15b and the outer peripheral guard 11, the filter membrane 13, the liquid permeable sheets 12, 14, the core 15a and the cylindrical structures 15b, 15c are bonded and sealed by end plates 16a, 16b. By this constitution, the flux in the circumferential direction of the filter membrane 13 is uniformized and the local clogging of the cartridge filter is prevented and filtering life is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cartridge filter used for filtering a liquid.

[0002]

2. Description of the Related Art Various types of filtration modules and filtration elements have been manufactured and sold in order to increase the filtration flow rate and facilitate handling at the time of filtration by a filtration membrane. One of the typical filtration elements is a cartridge type filter which is so-called pleated in which a filtration membrane is folded and housed in a cartridge having a fixed capacity. In this case, when a filtration membrane having a small flexural strength is used, breakage occurs during pleating and the function as a filtration membrane is lost. In order to remedy such inconveniences, in order to reinforce the conventional filtration membrane and also to serve as a spacer for preventing the filtration membrane surfaces from contacting each other, both sides of the filtration membrane are made of non-woven fabric or woven fabric, or a polymer or metal. The sandwich filter membrane obtained by scissors (for example, JP-A-60-58208) is pleated with a net formed by the above method.
JP-B-63-28654 and JP-B-63-37052
Disc-stacked cartridge filters, such as those described in the above, are also known.

[0003] When the purpose of filtration is to remove foreign substances in the liquid before filtration through a filtration membrane, the foreign substances include:
Garbage such as dust in ultrapure water, and bacteria and viruses for medical and food applications are examples. As is well known, a liquid after filtration can be obtained by a filtration operation in which a liquid before filtration is passed through a filtration membrane and foreign substances larger than the minimum pore size of the membrane are captured on the surface of the membrane or inside the membrane. In general, a surface of a filtration membrane that is in contact with the liquid before filtration is called a primary surface, and a surface that is in contact with the liquid after filtration is called a secondary surface.

[0004] The cartridge filter is generally used by being attached to a sealable container called a housing. Inside the housing, the cartridge filter is installed perpendicular to the ground. When the volume of the liquid before filtration is large, ten or more cartridge filters may be installed in the housing in parallel. The liquid before filtration enters the inside of the housing, is filtered from the primary side to the secondary side of the filtration membrane, and is collected from the outlet after passing through the core. At this time, the flux of the liquid passing through the filtration membrane can be distributed according to the gravity applied to the liquid before filtration with respect to the filtration membrane. This distribution becomes larger toward the lower part of the filtration membrane than to the upper part. Further, this distribution changes depending on the viscosity of the liquid before filtration and the resistance of the filter itself to the liquid before filtration.

[0005] The cartridge filter becomes unusable because it is clogged with components and foreign substances in the liquid before the filtration. The degree of clogging of the cartridge filter can be estimated by measuring the filtration pressure difference applied to the filtration membrane. In other words, it can be known from the difference between the pressure applied to the primary side and the pressure applied to the secondary side of the cartridge filter. The filtration differential pressure applied to the clogged cartridge filter may be as large as 4 kg / cm ² G or more. In such a case, depending on the performance of the liquid sending pump, the liquid before filtration may not be able to be sent, the filtration membrane may be broken, or the cartridge filter itself may be broken. As described above, the time from when the cartridge filter is used for filtration until the filtration differential pressure rises and the filter cannot withstand use, or the accumulated filtration amount is sometimes referred to as the filtration life.

[0006]

As described above, the liquid before filtration flows from the primary side to the secondary side of the filtration membrane through the shortest distance in the housing according to the gravity and the filtration resistance applied thereto. At the time of filtration, particularly at the initial stage, there is a case where almost no filtration pressure difference is applied to the filtration membrane. Since the cartridge filter is placed perpendicular to the ground, the liquid to be filtered has a higher flux at the lower portion at the upper and lower portions of the cartridge filter. When the filtration flux in the filtration membrane is large, the cumulative filtration amount tends to be smaller than when the filtration flux is small. For this reason, the filtration differential pressure increases from the lower part of the filtration membrane where the flux becomes relatively large.
In other words, clogging occurs from below the filtration membrane. When the cartridge filter is clogged in order from the bottom, the filtration life is shorter than when the cartridge filter is uniformly clogged.

[0007] From the viewpoint of prolonging the filtration life of a filtration membrane cartridge filter, the present inventors placed the cartridge filter horizontally with respect to the ground in order to make the flux of the liquid passing through the filtration membrane uniform. And a method of suspending a cartridge filter from the upper part of the housing, allowing the liquid before filtration to enter from the lower part of the housing, and collecting the liquid after filtration from the upper part. However, both
Although this is a method of reducing the influence of gravity applied to the liquid before filtration, the former filter cannot be expected to prolong the life of the filter inside the housing because the clogging occurs sequentially from the cartridge filter existing in the lower part of the housing. In the latter case, since a large amount of liquid before filtration remains inside the housing, the structure is inefficient from the viewpoint of using the liquid after filtration. Also,
The present inventors have found that if the flux of the liquid before filtration is reduced, the filtration life of the filtration membrane is extended as compared with the case where the flux is large,
As a method of reducing the flux and not reducing the amount of liquid after filtration, a method of increasing the number of cartridge filters existing in the housing has been considered, but in this case, equipment investment is increased.

[0008] An object of the present invention is to make the flux of the liquid passing through the filtration membrane of the cartridge filter uniform,
As a result, local clogging of the filtration membrane, particularly near the lower part in the direction of gravity, is prevented, and the life of the filtration membrane is extended, and a low-cost filter capable of maintaining the filtration performance of the cartridge itself for a long time. It is to provide a cartridge filter.

[0009]

SUMMARY OF THE INVENTION The above-mentioned problem is caused by a first cylinder in a cartridge filter having a core and a filtration membrane around the core for allowing the liquid filtered by the filtration membrane to pass inside the core. The present invention has been attained by a cartridge filter provided with a tubular structure, and having a second tubular structure inside the first tubular structure. That is, the object of the present invention has been achieved by the following (1) to (11). 1. In a cartridge filter having a core and a filtration membrane around the core, the cartridge has a tubular structure arranged on a plurality of substantially concentric circles inside the core, and one end of the tubular structure has an upper or lower end plate. A cartridge filter, which is alternately separated, the other end is liquid-tight, and the liquid that has passed through the filtration membrane is recovered from an outlet through a space defined by the outer and inner peripheries of the plurality of structures. 2. Item 2. The cartridge filter according to Item 1, wherein the plurality of cylindrical structures include a first structure and a second structure, and the first cylindrical structure is outside the second cylindrical structure. 3. The lower end of the first tubular structure is separated from the lowermost end plate, and the other end is liquid-tight.
Item 2. The cartridge filter according to Item 1, wherein the upper end of the cylindrical structure is separated from the end plate at the uppermost end, and the other is liquid-tight.

[0010] 4. Item 2. The cartridge filter according to item 1, wherein the first structure and the second cylindrical structure are made of the same material as other components of the cartridge filter. 5. Item 5. The cartridge filter according to item 4, wherein the material is made of polypropylene. 6. Item 5. The cartridge filter according to item 4, wherein the material is made of polyethylene. 7. Item 2. The cartridge filter according to Item 1, wherein the cartridge filter is a pleated cartridge filter. 8. Item 2. The cartridge filter according to Item 1, wherein the cartridge filter is a disk-stacked cartridge filter. 9. Item 2. The cartridge filter according to Item 1, wherein the filtration membrane is made of polysulfone. 10. Item 2. The cartridge filter according to Item 1, wherein the filtration membrane has an average pore size of 0.05 to 10 μm. 11. Item 11. The cartridge filter according to item 10, wherein the filtration membrane is formed using polysulfone represented by the general formula (1) or (2) as a raw material.

[0011]

Embedded image

Hereinafter, the configuration of the filter of the present invention will be described in detail.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is an example of a development view showing the entire structure of a general pleated cartridge filter. The filtration membrane 3 is folded while being sandwiched by the two liquid-permeable sheets 2 and 4, and is wound around a core 5 having many liquid collection ports 9. An outer guard 1 protects the filtration membrane outside.
Filtration membranes are sealed at both ends of the cylinder by end plates 6a and 6b. The end plate is in contact with a seal portion of a filter housing (not shown) via a gasket (not shown). The liquid after filtration is collected from a liquid collecting port of the core and collected from an outlet (not shown). Cartridge filters are known with outlets at both ends and at one end. In general, when the outlet has both ends, the filtered liquid is recovered from the outlet at the other end by sealing one end with a jig. FIG.
5A is a schematic enlarged view of the upper end of the cartridge filter of FIG.

FIG. 2A is an example of a development view showing the entire structure of a pleated filtration membrane cartridge filter having a tubular structure for making the flux of the liquid passing through the filtration membrane uniform in the present invention. It is. The filtration membrane 13 is folded while being sandwiched by the two liquid-permeable sheets 12 and 14 and wound around the core 15a. An outer guard 11 is provided on the outside to protect the filtration membrane. The first tubular structure 15b exists inside the core 15a. Furthermore, the second cylindrical structure 15b
Of the cylindrical structure 15c. Peripheral guard 11, filtration membrane 13, liquid-permeable sheets 12, 14, core 15a and first
The cylindrical structure 15b and the second cylindrical structure 15c are bonded and sealed by end plates 16a and 16b. The first cylindrical structure 15b includes an end plate 16b
Are not liquid-tightly bonded (not shown). Also, the second
Is not liquid-tightly bonded to the end plate 16a. The filtered liquid comes into contact with a seal portion of a filter housing (not shown) via a gasket (not shown). The liquid after filtration is collected from a liquid collecting port of the structure, and collected from an outlet (not shown). FIG. 2 (B)
Is a schematic enlarged view of the upper end portion of the cartridge filter of FIG. 2A, and the second tubular structure 15c is not liquid-tightly bonded to the end plate 16a.

FIG. 3 is a schematic diagram showing an example of the flow of a liquid before and after filtration by a general cartridge filter. The outer peripheral guard 41, the filtration membrane 43, and the core 45 having a large number of liquid collection ports are adhered on end plates 46a and 46b on the surfaces that are in contact with each of them. In a general filtration step, the primary side of the filtration membrane 43 is in contact with the liquid before filtration in the housing. The liquid that has passed through the outer peripheral guard 41 is filtered from the primary side of the filtration membrane 43 to the secondary side, and
5 and is collected through the liquid collection port 49. At this time, the liquid before filtration is applied with its own weight, so that the liquid located relatively below receives more pressure than the liquid located above, so that the filtration flux increases. In this way, the flux of the liquid passing through the filtration membrane is not uniform. That is, the above fluxes of (a1), (b1), and (c1) showing the flow of the liquid near the upper end, near the center, and near the lower end are (a)
1) <(b1) <(c1).

FIG. 4 is a schematic diagram showing one example of the flow of a liquid before and after filtration in a cartridge filter having a tubular structure for making the flux of the liquid passing through the filtration membrane uniform according to the present invention. It is. An outer peripheral guard 51, a filtration membrane 53 and a core 55 having a number of liquid collecting ports are provided with an end plate 56.
a and 56b are adhered on the surfaces in contact with each of them. In addition, the first tubular structure 55b includes an end plate 5
6b, but not to the end plate 56a. Further, the second tubular structure 55c is bonded to the end plate 56a, but is not bonded to the end plate 56b. In a general filtration process, the primary side of the filtration membrane 53 is in contact with the liquid before filtration in the housing. The liquid that has passed through the outer guard 51 is filtered by the filtration membrane 5.
3 is filtered from the primary side to the secondary side, and passes through the liquid collecting port 59a of the core 55a. Next, the liquid inlet 59b at the lower end of the first tubular structure 55b, the space between the inner periphery of the first tubular structure 55b and the outer periphery of the second tubular structure 55c, The liquid collecting port 59c at the upper end of the tubular structure 55c,
Through the hollow space of the cylindrical structure 55c. At this time, since the liquid before filtration has its own weight, a relatively lower liquid is subjected to more pressure than a liquid located at the upper part. In the case of the cartridge filter having the cylindrical structure according to the present invention, the liquid filtered finally to the height of the liquid collecting port 59c is pushed up. In this way, the flux of the liquid passing through the filtration membrane becomes substantially the same. That is, (a2), (b2), and (c) indicate the flow of the liquid near the upper end, near the center, and near the lower end.
The flux of 2) is (a2) ≒ (b2) ≒ (c2).

The first type which can be used in the present invention
It is preferable that the cross-sections of the cylindrical structure and the second cylindrical structure are point-symmetric. More preferably, it is circular. Such a cross-sectional shape helps uniform the flux in the circumferential direction of the filtration membrane. Further, the first tubular structure and the second tubular structure that can be used in the present invention have, in their cross sections, the area between the filtration membrane and the outer periphery of the first tubular structure. The area between the inner periphery of the first tubular structure and the outer periphery of the second tubular structure is 90
% Or more and 110% or less. If it is smaller than 90%, the flux of the liquid entering the hollow portion of the first tubular structure is limited, which may increase the filtration resistance of the entire cartridge filter. On the other hand, if it exceeds 110%, the effect of the present invention of making the flux of the liquid passing through the filtration membrane uniform may not be sufficiently achieved. Also,
The first tubular structure and the second tubular structure that can be used in the present invention have, in cross-section, the inner periphery of the first tubular structure and the outer periphery of the second tubular structure. The area between the inner circumference of the second tubular structure and the area between
It is preferably 0% or more and 110% or less. If it is less than 90%, the flux of the liquid entering the hollow portion of the second tubular structure is restricted, which may cause an increase in the filtration resistance of the entire cartridge filter. On the other hand, if it exceeds 110%, the effect of the present invention of making the flux of the liquid passing through the filtration membrane uniform may not be sufficiently achieved.

Further, the first cylindrical structure which can be used in the present invention is such that the sum of the areas of the liquid passage ports at the lower end thereof is equal to the inner circumference of the first cylindrical structure and the second cylindrical structure. 80% or more and 120% with respect to the smaller of the cross-sectional area of the outer periphery of the cylindrical structure and the area between the filtration membrane and the first cylindrical structure, whichever is smaller.
It is preferable to set the following. When the ratio is less than 80%, the filtration is restricted when the liquid after filtration passes through the liquid passage, which may increase the filtration resistance at the initial stage of using the cartridge filter. On the other hand, if it is larger than 120%, the lower end of the filter
On the next side, the effect of making the flux of the liquid before filtration uniform is reduced, and the filtration life of the cartridge filter as a whole may be reduced. Further, the second cylindrical structure that can be used in the present invention is such that the sum of the areas of the liquid collection ports at the upper end thereof is equal to the inner circumference of the first cylindrical structure and the second cylindrical structure. 80% or more of the smaller of the cross-sectional area of the outer periphery of the object and the area of the second
It is preferable that the content be 20% or less. If it is less than 80%, the time when the liquid after filtration is collected in the liquid collecting port will be the regulation of the whole filtration, which may cause an increase in the filtration resistance at the beginning of use of the cartridge filter. On the other hand, if it is larger than 120%, the effect of making the flux of the liquid before filtration uniform on the primary side of the filtration membrane at the upper end of the cartridge filter becomes small, and the filtration life of the cartridge filter as a whole is shortened. There is.

The first one that can be used in the present invention
It is preferable that the material of the cylindrical structure and the second cylindrical structure is the same as that of the member constituting the cartridge filter except the filtration membrane. When using the same member,
The cartridge filter can be assembled by welding using heat, ultrasonic waves, or the like. Since this method does not use an adhesive or the like, it is advantageous in that unnecessary components do not elute into the filtrate from the cartridge filter. A more preferred material having such advantages is polypropylene or polyethylene. Polypropylene and polyethylene have the advantage of being chemically stable and inexpensive. Further, cellulose triacetate and polysulfone can also be used as members constituting the cartridge filter. Cellulose triacetate is inexpensive, and polysulfone is characterized by excellent heat resistance.

The viscosity of the liquid before filtration, which can be used in the present invention, is 0.5 cP or more and 100 cP or less, more preferably 10 cP or less. In the case of a liquid having a viscosity exceeding 100 cP, the filtration resistance of the liquid before filtration to the filter becomes larger than the effect of the flux distribution due to gravity in the vertical direction of the cartridge filter, and the effect of the present invention is reduced. .

The filtration membrane that can be used in the present invention is:
Those having an average pore diameter of 0.05 to 10 μm are preferred.
Further, a material using a polysulfone represented by the following chemical formula (1) or (2) as a raw material is preferable.

[0022]

Embedded image

A method for forming the filtration membrane 3 using polysulfone pellets will be described below. That is, a polysulfone pellet is formed from formamide, dimethylformamide, dimethylacetamide, dimethylsulfoxide, 2-pyrrolidone,
It is dissolved in polar organic solvents such as N-methyl-2-pyrrolidone and sulfolane. The solvent may be a single solvent or a mixture of plural types of solvents. In order to adjust the dissolving power of the solvent, a small amount of a solvent such as alcohol, such as methanol, ethanol, propanol or butanol, or water, which is called a non-solvent or a poor solvent, is often added. The amount of addition depends on the type of solvent, but in the case of frequently used water,
It is from 0.05% by weight to 6% based on the film forming stock solution.

To the polysulfone solution, at least one kind of an inorganic electrolyte, an organic electrolyte, a polymer or the like, which is usually called a swelling agent or a foaming agent, for controlling the porous structure is added. Examples of the swelling agent that can be used in the present invention include hydrophilic polymers such as polyethylene glycol and polyvinylpyrrolidone, metal salts of inorganic acids such as salt, sodium nitrate, potassium nitrate, sodium sulfate, zinc chloride and magnesium bromide, sodium acetate, formic acid Organic acid salts such as sodium and potassium butyrate, polymer electrolytes such as sodium polystyrenesulfonate and polyvinylbenzyltrimethylammonium chloride, and ionic surfactants such as sodium dioctylsulfosuccinate and sodium alkylmethyltaurate are used. Some of these swelling agents alone show some effects even when added to the polymer solution, but when these swelling agents are added as an aqueous solution, they may show particularly remarkable effects. The addition amount of the swelling agent is not particularly limited as long as the uniformity of the solution is not lost by the addition, but it is usually 0.5% by weight to 35% by weight of the stock solution for film formation. The concentration of polysulfone as a film forming stock solution is 5 to 35% by weight, preferably 10 to 30% by weight.
When the amount exceeds 35% by weight, the water permeability of the obtained microporous membrane becomes so small as to have no practical meaning. When the amount is less than 5% by weight, a filtration membrane having a sufficient separation ability cannot be obtained.

The membrane-forming stock solution prepared as described above is cast on a support, and the polymer solution membrane together with the support is immersed in the coagulation solution immediately after the casting or after a certain period of time. Water is most commonly used as the coagulation liquid, but an organic solvent that does not dissolve the polymer may be used, or two or more of these non-solvents may be used in combination. As the support, a metal plate such as a copper plate or a stainless steel plate, a plastic sheet such as polyester or polyethylene, and a glass plate can be used. The casting membrane in which the polymer was precipitated in the coagulation liquid to form pores was peeled off the membrane from the support as necessary, followed by washing with water,
Perform hot water washing, solvent washing, etc., and dry. When a non-woven fabric, a woven fabric or paper is used as the support, the membrane is washed and dried as it is without peeling off the support.

A method of forming a polysulfone membrane having an inner minimum pore diameter, which is characterized in that it is hardly clogged, has a long-term filtration performance, and has a feature that the filtration layer is hidden inside the membrane and is not easily damaged, will be briefly described. A temperature of 15-60 ° C. and a relative humidity of 10-80 ° C. are applied to the surface of a liquid film obtained by casting a film forming stock solution on a support.
%, The air speed adjusted in the range of 0.2 to 4 m / sec.
There is an important technique for appropriately adjusting the amount of evaporation of the solvent vapor and the amount of absorption of the non-solvent vapor from the atmosphere (absorption of moisture) by exposure for 40 seconds. For such a preparation, for example, a film forming stock solution is cast on a casting support, and is subjected to 25 ° C. and an absolute humidity of 2 ° C.
The coacervation phase is brought to a depth of 1 μm or more, preferably 1 to 30 μm from the outermost surface layer of the liquid film by applying air of gH ₂ O / kg Air or more to the casting surface at a wind speed of 0.2 m / sec or more. Can be formed. Immediately thereafter, it is immersed in a coagulation liquid to form a porous film. In the film obtained in this manner, the deepest part of the part where coacervation has occurred becomes the minimum pore diameter layer. The pore size on the back surface is 10 to 100 with respect to the pore size on the front surface of such an inner minimum pore size layer film.
About 0 times, and its specific surface area measured by BET method is 8 ~
80 m ² / g are obtained. A preferable specific surface area having both the mechanical strength and the filtration capacity of the membrane is 20 to 60 m ^2.
/ G. When the porosity of the membrane is increased, the permeability of water (liquid) is improved. However, when the porosity is too large, the membrane becomes brittle and cannot be used. Therefore, the preferred porosity is 55 to 87%, and particularly preferably 70 to 87%.
84%. The porosity of the membrane is greatly affected by the polysulfone concentration and the swelling agent concentration in the membrane-forming stock solution. When the polysulfone concentration is low and the swelling agent concentration is high, the porosity increases. It is slightly affected by the amount of water absorbed from the air immediately after film formation and the temperature of the coagulating liquid.

The filtration membrane 3 formed in this manner is subjected to a fold processing by a generally known method. Liquid permeable sheets 2, 4
Non-woven fabric, woven fabric, paper, and / or net are used. The folds of the filter media are cut off at both ends using a cutter knife or the like in order to align both ends, then rounded into a cylindrical shape, and the folds at the joint are thermoplastically fused by ultrasonic welding or heat sealing. Liquid-tight seals,
Alternatively, a liquid-tight seal is made using an adhesive. The general role of the liquid permeable sheet is firstly to guide the liquid to be filtered into the interior of the membrane folds so that the entire membrane folded into the cartridge can be used effectively for filtration. The second role of the liquid-permeable sheet is to protect the filtration membrane. Therefore, the liquid-permeable sheet is required to have a large number of voids and low liquid-permeation resistance, and an appropriate strength. Further, in the present invention, the third role is to easily release bubbles at the time of filtration to increase the contact area between the filtration membrane and the liquid.

The pleats are pleated so that the width of the pleats is usually from 5 mm to 25 mm. In the present invention, the diameter is preferably set to 5 mm to 12 mm in order to easily release bubbles. In particular, it is preferable to set the thickness from 7 mm to 10.5 mm. There are several methods for the end sealing step depending on the material of the end plate. A method in which only the sealing surface of an already molded end plate is brought into contact with a hot plate or irradiated with an infrared heater to melt only the plate surface, and one end surface of the cylindrical filter medium is pressed against the molten surface of the plate and welded. Done. on the other hand,
When using a thermosetting epoxy resin for the end plate, pour the liquid of the prepared epoxy resin adhesive into the potting mold, pre-cure it, and make the viscosity of the adhesive moderately high. One end is inserted into the epoxy adhesive. After that, it is completely cured by heating. When the material of the end plate is a thermoplastic resin such as polypropylene or polyester, a method of inserting one end surface of the cylindrical filter medium into the resin immediately after pouring the molten resin into a mold is performed.

[0029]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the contents of the examples. (Preparation of Polysulfone Filtration Membrane) An actual example of a filtration membrane made of polysulfone is shown. 15 parts of polysulfone (P-3500, manufactured by Amoco), 70 parts of N-methyl-2-pyrrolidone, 15 parts of polyvinylpyrrolidone, 2 parts of lithium chloride, and 1.3 parts of water are uniformly dissolved to prepare a stock solution for film formation. This is cast so that the product thickness becomes 180 μm,
Air having a temperature of 25 ° C., a relative humidity of 50% and an air velocity of 1.0 m / sec was applied to the surface of the liquid film cast for 8 seconds, and immediately immersed in a coagulation bath filled with water at 25 ° C. to obtain a microporous film. . The bubble point of this film due to water was 150 kPa. To produce a nonwoven sheet basis weight 50 g / m ² polypropylene of Example 1 fineness 1.5d. The above-mentioned polysulfone filtration membrane is sandwiched between the two nonwoven fabrics, pleated to a pleat width of 10 mm, folds of 145 ridges are taken out, rounded into a cylindrical shape, and the joint is sealed by welding. The cylinder was cut off at each end by 5 mm, packed in the outer guard, and three of them were connected in series. The first is liquid-tight on the secondary side of the core and has a liquid outlet at the lower end.
Was placed inside and welded and fixed to the end plate on the upper end side. Further, a second polypropylene cylindrical structure which is liquid-tight inside and has a liquid passage port at the upper end is put therein, and is fusion-fixed to the end plate at the lower end while holding the outlet at the lower end side, and has a length of 80 cm. Finished as a cartridge filter. Using this cartridge filter, beer was filtered at 500 L / h. It took 36 days for the filtration pressure difference to reach 1.0 kg / cm ² G.

Comparative Example 1 A nonwoven fabric sheet having a basis weight of 50 g / m ² was produced using a polypropylene having a fineness of 1.5 d. The polysulfone filtration membrane is sandwiched between the two nonwoven fabrics, pleated to a pleat width of 10 mm, folds of 145 ridges are taken out, rounded into a cylinder, and the joint is sealed with an epoxy adhesive. The cylinder was cut off by 5 mm at each end, and the cut surface was sealed with an epoxy adhesive. These were connected in series to form a cartridge filter having a length of 80 cm. Using this cartridge filter, beer was filtered at 500 L / h. It took 30 days for the filtration pressure difference to reach 1.0 kg / cm ² G.

[0031]

According to the present invention, the filter life of the cartridge filter can be extended very easily and inexpensively. As a result, the cost of the process using the cartridge filter can be reduced. In particular, the effect is remarkable in a polysulfone anisotropic structure membrane cartridge filter in which the pore size on both surfaces of the membrane is twice or more the pore size of the smallest pore size layer inside the membrane.

[Brief description of the drawings]

FIG. 1 is a view illustrating a structure of a general pleated cartridge filter.

FIG. 2 is a drawing showing one example of the structure of a pleated cartridge filter in an embodiment of the present invention.

FIG. 3 is a drawing schematically showing the flow of a liquid before and after filtration by a general cartridge filter. The arrow in the figure is
Shows the direction of flow of the liquid before and after filtration.

FIG. 4 is a drawing schematically showing a flow of a liquid before and after filtration by a cartridge filter in an embodiment of the present invention. The arrows in the figure indicate the directions in which the liquid flows before and after filtration.

[Explanation of symbols]

 Reference Signs List 1 outer peripheral guard 2 liquid-permeable sheet 3 filtration membrane 4 liquid-permeable sheet 5 core 6a end plate 6b end plate 9 liquid collecting port 11 outer periphery guard 12 liquid-permeable sheet 13 filtration membrane 14 liquid-permeable sheet 15a core 15b first Cylindrical structure 15c Second cylindrical structure 16a End plate 16b End plate 19 Liquid collecting port 41 Outer peripheral guard 43 Filtration membrane 45 Core 46a End plate 46b End plate 48 Outlet 49 Liquid collecting port 51 Outer peripheral guard 53 Filtration membrane 55a Core 55b First cylindrical structure 55c Second cylindrical structure 56a End plate 56b End plate 58 Outlet 59a Liquid collecting port 59b Liquid passing port 59c Liquid collecting port

Claims (11)

[Claims] 1. A cartridge filter having a core and a filtration membrane around the core, the cartridge having a tubular structure disposed on a plurality of substantially concentric circles inside the core, wherein one end of the tubular structure is vertically located. The end plate is alternately separated and the other end is liquid-tight, and the liquid that has passed through the filtration membrane is recovered from the outlet through a space formed by the outer and inner peripheries of the plurality of structures. And cartridge filter. 2. The method according to claim 1, wherein the plurality of tubular structures include a first structure and a second structure, and the first tubular structure is outside the second tubular structure. The cartridge filter as described. 3. A lower end of the first tubular structure is separated from an end plate at a lowermost end, and the other end is liquid-tight,
The cartridge filter according to claim 1, wherein an upper end of the second tubular structure is separated from an end plate at an uppermost end, and the other is liquid-tight. 4. The cartridge filter according to claim 1, wherein the first structure and the second cylindrical structure are made of the same material as the other components of the cartridge filter. 5. The cartridge filter according to claim 4, wherein said material is made of polypropylene. 6. The cartridge filter according to claim 4, wherein said material is made of polyethylene. 7. The cartridge filter according to claim 1, wherein the cartridge filter is a pleated cartridge filter. 8. The cartridge filter according to claim 1, wherein the cartridge filter is a disk-stacked cartridge filter. 9. The cartridge filter according to claim 1, wherein said filtration membrane is made of polysulfone. 10. An average pore size of the filtration membrane is 0.05 to 1
The cartridge filter according to claim 1, which has a thickness of 0 µm. 11. The cartridge filter according to claim 10, wherein the filtration membrane is formed using polysulfone represented by the general formula (1) or (2) as a raw material. Embedded image