Cylindrical pleated filter and filtration apparatus equipped therewith

Abstract

To provide a tubular pleated filter with excellent shape retention of the pleats. [Solution] The above problem is solved by a cylindrical pleated filter 20 having a core tube 21 made of a mesh material whose tube wall has fluid permeable holes, a cylindrical filter material 22 that surrounds the outer surface of the core tube 21 and is bent in a bellows shape so that folds extending in the axial direction Y are repeated in the circumferential direction, and a pair of sealing parts 25 that seal both ends in the axial direction Y of the space 24 between the core tube 21 and the cylindrical filter material 22, wherein the cylindrical filter material 22 has an adhesive part 26 in the middle of the axial direction Y between the pair of sealing parts 25 where the bottom of the valleys between each fold and the core tube 21 are bonded via adhesive, and an unadhesive part 27 where the bottom of the valleys between each fold and the core tube 21 are not bonded, and a band is not wrapped around the outer surface of the cylindrical filter material 22.

Description

Technical Field

[0001] The present invention relates to a cylindrical pleated filter and a filtering device provided with the same.

Background Art

[0002] A pleated filter is formed by folding a filter medium such as a non-woven fabric into a bellows shape to form a plurality of folds. Since it has a large filtration area per unit volume and a simple structure, it is widely used. Among pleated filters, there are not only flat ones but also those formed in a cylindrical shape (see, for example, Patent Documents 1 and 2).

[0003] A general cylindrical pleated filter has a core tube in which fluid permeation holes are provided at intervals in a predetermined pattern on the tube wall, a cylindrical filter medium that surrounds the outer peripheral surface of the core tube and is folded into a bellows shape so that folds extending in the axial direction are repeated in the circumferential direction, and a pair of blocking portions that block both axial ends of the space between the core tube and the cylindrical filter medium, respectively. In such a cylindrical pleated filter, the outer side and the center side of the cylindrical filter medium become the primary side and the secondary side, respectively. By passing the fluid to be treated from the primary side to the secondary side, target particles are captured on the surface of the cylindrical filter medium or in the cylindrical filter medium, and the treated fluid can be discharged through the core tube.

[0004] When fouling occurs on the cylindrical filter medium, it can be cleaned by spraying a cleaning fluid onto the outer peripheral surface of the cylindrical filter medium, or by reverse cleaning by passing the cleaning fluid from the inside to the outside of the cylindrical filter medium. During reverse cleaning, if compressed air as the cleaning fluid is intermittently (pulsed) supplied, vibration of the cylindrical filter medium is also added, making it easier for target particles to fall off from the cylindrical filter medium, and fouling can be efficiently eliminated.

[0005] In pleated filters, it is important that the pleats maintain their proper shape during use. That is, since the tubular filter material is made of a flexible sheet, if it deforms due to the pressure applied to the tubular filter material during filtration or washing, the filtration performance may decrease or washing may become insufficient. For this reason, in conventional pleated filters 200, in order to maintain the shape of the pleats, as shown in Figure 8, a band 29 is wrapped around the outer surface of the tubular filter material 22 in the circumferential direction at the midpoint of the axial direction Y between the pair of sealing portions 25, and the tops of the pleats and the band 29 are bonded at the intersection.

[0006] However, conventional methods using this band had the problem that the adhesion between the fold's apex and the band was easily broken during use. When the adhesion between the fold's apex and the band is broken, the fold is no longer able to maintain its proper shape, and the fold's apex rubs against the band, causing holes to form, which is undesirable. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6694662 [Patent Document 2] Patent No. 6917645 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Therefore, the main objective of the present invention is to provide a tubular pleated filter that exhibits excellent shape retention of the pleats. [Means for solving the problem]

[0009] The cylindrical pleated filter and filtration device equipped therewith that solve the above problems are as follows.

[0010] <First aspect> A core tube whose wall is made of a mesh material having fluid permeable holes, A cylindrical filter material surrounds the outer surface of the core tube and is bent in a bellows-like manner so that folds extending in the axial direction are repeated in the circumferential direction, A cylindrical pleated filter having a pair of sealing parts that seal both ends in the axial direction of the space between the core tube and the cylindrical filter material, The cylindrical filter material has, midway in the axial direction between the pair of sealing portions, an adhesive portion where the bottom of each fold and the core tube are bonded together via adhesive, and an unadhesive portion where the bottom of each fold and the core tube are not bonded together. The band is not wrapped around the outer surface of the cylindrical filter material. A cylindrical pleated filter characterized by the following features.

[0011] (Effects and Benefits) This tubular pleated filter is characterized by using a core tube made of a mesh material with fluid permeable holes in its wall, and by bonding the bottom of the valleys between each pleat of the tubular filter material to the core tube via adhesive at the midpoint in the axial direction between a pair of sealing sections. That is, because the core tube is made of a mesh material, the adhesive bonding the bottom of the valleys between each pleat of the tubular filter material to the core tube enters into the permeable holes of the core tube, forming an adhesive area with excellent adhesion to the core tube. Therefore, compared to conventional examples where the filter is bonded to a band, the adhesive area in this embodiment is less prone to breakage during use and maintains the shape of the pleats better. Furthermore, in conventional methods, when a band wrapped around the outer surface of the tubular filter material is bonded to the top of the tubular filter material, the shape of the pleats is maintained in a desirable state if the adhesion is maintained. However, if the adhesive area breaks, the band may act to maintain the pleats in an inappropriate shape. In contrast, this tubular pleated filter does not have such problems. Furthermore, since the band is not wrapped around the outer surface of the cylindrical filter media, there is no risk of holes forming due to the tops of the folds rubbing against the band, as was the case with conventional designs.

[0012] <Second aspect> In the adhesive portion, the adhesive is applied to the outer surface of the core tube in a continuous, annular manner in the circumferential direction, and the thickness of the adhesive on the core tube between the inner surfaces of each fold is greater than the thickness of the adhesive between the bottom of the valleys between each fold and the core tube. A tubular pleated filter according to a first embodiment.

[0013] (Effects and Benefits) By arranging the adhesive at the bonding area as in this embodiment, the base of the folds of the cylindrical filter material can be firmly bonded to the core tube, and the orientation of the fold bases can be restricted by the adhesive, thereby improving the shape retention of the folds. Furthermore, even with this adhesive arrangement, the spacing between the valley bottoms in the circumferential direction is narrower compared to conventional band fixing, so the amount of adhesive required is relatively small.

[0014] <Third aspect> The adhesive protrudes to the inside of the core tube through the perforation hole. The portion of the adhesive that protrudes inward from the core tube has a barb that is located outside the edge of the perforation hole. A tubular pleated filter according to the first or second embodiment.

[0015] (Effects and Benefits) It is preferable that the adhesive used to fix the cylindrical filter material protrudes into the core tube through the permeable holes of the core tube, as in this embodiment, and has a barb portion located outside the edge of the permeable holes, because the anchoring effect makes it less likely for the adhesive to peel off from the core tube.

[0016] <Fourth aspect> In the aforementioned adhesive portion, the adhesive is applied to the outer surface of the core tube in a continuous, annular manner in the circumferential direction. The adhesive protrudes to the inside of the core tube through the perforation hole. The portion of the adhesive that protrudes inward from the core tube has a barb portion located outside the edge of the perforation hole. The circumferential distance between the centers of adjacent valley bottoms in the cylindrical filter material is 2 to 5 times the circumferential distance between the centers of the permeable holes in the core tube. The cylindrical pleated filter of the first or second aspect.

[0017] (Function and effect) By arranging the folds and the permeation holes in the circumferential direction of the core tube as in this aspect, there will always be permeation holes between the adjacent valley bottoms in the circumferential direction of the core tube, and the anchor effect by the permeation holes is also exerted, so the adhesion of the adhesion part becomes stronger.

[0018] <The fifth aspect> The number of the folds is 60 to 180, The outer diameter of the cylindrical filter medium is 12 to 50 cm, The inner diameter of the cylindrical filter medium is 7 to 25 cm, The inner diameter of the cylindrical filter medium is 0.5 to 0.6 times the outer diameter of the cylindrical filter medium, The axial distance between the pair of blocking parts is 0.3 to 2.2 m, Between the pair of blocking parts, the adhesion part is provided at an axial center distance of 100 to 200 mm in the axial direction, The axial width of the adhesion part at one place is 20 to 30 mm, The cylindrical pleated filter of any one of the first to fourth aspects.

[0019] (Function and effect) When the cylindrical filter medium has dimensions within the range of this aspect, particularly the shape maintainability of the cylindrical filter medium is likely to be a problem. Therefore, the above-mentioned adhesion part is suitable for a cylindrical pleated filter having dimensions within the range of this aspect. Also, when the dimensions of each part are within the range of this aspect, the shape maintainability of the folds during use is good, and the adhesion strength of the adhesion part is also sufficient.

[0020] <The sixth aspect> The outer surface of the cylindrical filter medium is formed of a PTFE film or a nanofiber film, and the inner surface is formed of a non-woven fabric. The cylindrical pleated filter of any one of the first to fifth aspects.

[0021] (Function and effect) When a cylindrical filter material has a structure like that of this embodiment, the outer surface of the cylindrical filter material has poor adhesion to adhesives, and the adhesive part tends to peel off with conventional band fixing methods. However, by adopting the adhesive structure between the bottom of the valleys between the folds and the core tube as described above, the adhesion does not deteriorate even when the cylindrical filter material has a structure like that of this embodiment.

[0022] <Seventh aspect> A core tube whose wall is made of a mesh material having fluid permeable holes, A cylindrical filter material surrounds the outer surface of the core tube and is bent in a bellows-like manner so that folds extending in the axial direction are repeated in the circumferential direction, A cylindrical pleated filter comprising a pair of sealing parts that seal both ends in the axial direction of the space between the core tube and the cylindrical filter material, A filtration device configured to supply the fluid to be treated to the outside of the cylindrical filter material and filter the entire volume through the cylindrical filter material, and to discharge the treated fluid that has permeated to the inside of the cylindrical filter material through the permeate holes and the core tube, The cylindrical filter material has, midway in the axial direction between the pair of sealing portions, an adhesive portion where the bottom of each fold and the core tube are bonded together via adhesive, and an unadhesive portion where the bottom of each fold and the core tube are not bonded together. The band is not wrapped around the outer surface of the cylindrical filter material. The system is equipped with an air pulse supply device that intermittently supplies compressed air into the core tube. A filtration device characterized by the following features.

[0023] (Effects and Benefits) In this filtration device, during the washing operation after the filtration operation, compressed air is intermittently supplied to the core tube (i.e., the secondary side of the cylindrical pleated filter) by an air pulse supply device. This allows the compressed air to pass from the inside to the outside of the cylindrical filter media, and the shock waves from the compressed air applied to the cylindrical filter media cause it to vibrate, dislodging particles adhering to the outer surface and inside of the cylindrical filter media, thus enabling backwashing. When such backwashing with air pulses is performed many times, the adhesive joints of conventional band-fixed cylindrical pleated filters tend to peel off, but in this filtration device, as explained in the first embodiment, the adhesive joints are strong, so the durability against backwashing with air pulses is dramatically improved. Furthermore, although this was not initially anticipated, it was found that when backwashing with air pulses is performed in this filtration device, the pleats vibrate effectively because the top side of the cylindrical filter media is not restrained, resulting in a significantly improved cleaning effect compared to conventional band-fixed cylindrical pleated filters.

[0024] <Eighth aspect> A core tube whose wall is made of a mesh material having fluid permeable holes, A cylindrical filter material surrounds the outer surface of the core tube and is bent in a bellows-like manner so that folds extending in the axial direction are repeated in the circumferential direction, A cylindrical pleated filter comprising a pair of sealing parts that seal both ends in the axial direction of the space between the core tube and the cylindrical filter material, A filtration device configured to supply the fluid to be treated to the outside of the cylindrical filter material and filter the entire volume through the cylindrical filter material, and to discharge the treated fluid that has permeated to the inside of the cylindrical filter material through the permeate holes and the core tube, The cylindrical filter material has, midway in the axial direction between the pair of sealing portions, an adhesive portion where the bottom of each fold and the core tube are bonded together via adhesive, and an unadhesive portion where the bottom of each fold and the core tube are not bonded together. The band is not wrapped around the outer surface of the cylindrical filter material. The cylindrical filter material is equipped with a spraying device that sprays cleaning solution onto its outer surface. A filtration device characterized by the following features.

[0025] (Effects and Benefits) In conventional band-fixed cylindrical pleated filters, when cleaning solution is sprayed onto the outer surface of the cylindrical filter media using a spraying device, the cleaning solution is obstructed by the bands at the band attachment points, inevitably reducing the cleaning effect. Furthermore, in conventional band-fixed cylindrical pleated filters, spraying cleaning solution onto the outer surface of the cylindrical filter media using a spraying device tends to exert a force that peels the adhesive joints. In contrast, in the cylindrical pleated filter of the filtration device of this embodiment, the bands do not interfere with cleaning, and there is almost no force that peels the adhesive joints. Therefore, both backwashing efficiency and cleaning durability are improved. [Effects of the Invention]

[0026] According to the present invention, a tubular pleated filter is obtained that has excellent fold shape retention properties. [Brief explanation of the drawing]

[0027] [Figure 1] This is a schematic front view of a cylindrical pleated filter (the pleats are omitted in the figure). [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is a cross-sectional view taken along line III-III in Figure 1. [Figure 4] This is an enlarged view of section IV in Figure 3. [Figure 5] This is a plan view of a cylindrical pleated filter (the bottom view is shown symmetrically to the plan view, although it is not illustrated). [Figure 6] This is a longitudinal cross-sectional view schematically showing an example of a filtration device. [Figure 7] This is a schematic longitudinal cross-sectional view showing another example of a filtration device. [Figure 8] This is a schematic front view of a conventional cylindrical pleated filter (the pleats are omitted in the figure). [Modes for carrying out the invention]

[0028] The following describes an example of a treatment apparatus for the liquid to be treated. However, the following description and drawings are merely examples, and the content of the present invention is not limited to the following description and drawings.

[0029] <Cylindrical pleated filter> Figures 1 to 4 show an example of a cylindrical pleated filter 20. This cylindrical pleated filter 20 has a cylindrical core tube 21 made of a mesh material whose tube wall has fluid permeable holes 21h, a cylindrical filter material 22 that surrounds the outer surface of the core tube 21 and is bent in a bellows-like manner so that folds 23 extending in the axial direction Y are repeated in the circumferential direction C, and a pair of sealing parts 25 that seal both ends in the axial direction Y of the space 24 between the core tube 21 and the cylindrical filter material 22. The folds 23 are portions that protrude outward in the radial direction R of the cylindrical filter material 22 and have a pair of wall parts 23w that extend from the fold at the tip (end) of the fold toward the outer surface of the core tube 21. A valley bottom 22b is formed between adjacent folds 23 in the cylindrical filter material 22.

[0030] The sealing portion 25 is not particularly limited as long as both ends in the axial direction Y of the space 24 between the core tube 21 and the cylindrical filter material 22 are sealed, and the space between the outer surface of the core tube 21 and the inner surface of the cylindrical filter material 22 becomes a closed space 24. For example, as shown in the illustrated example, annular covers 25c are provided at both ends in the axial direction Y of the cylindrical filter material 22, and the annular covers 25c and the ends of the cylindrical filter material 22, and the annular covers 25c and the ends of the core tube 21 are bonded together via a sealing adhesive 25b so as not to leak the fluid to be treated, thereby creating a closed space 24 between the outer surface of the core tube 21 and the inner surface of the cylindrical filter material 22. Another example, although not shown, is to bond or weld the opposing inner surfaces of each fold 23 together at both ends of the cylindrical filter medium 22 in the axial direction Y, using a sealing adhesive 25b, and to bond it to the outer surface of the core tube 21 to form a sealed portion 25, thereby creating a closed space 24 between the outer surface of the core tube 21 and the inner surface of the cylindrical filter medium 22. In these cases, the gap can be sealed using a sealing material such as epoxy resin or silicone rubber as needed.

[0031] The mesh material forming the tube wall of the core tube 21 can be a woven mesh, a resin or metal perforated material, and is particularly preferable to be perforated metal from the viewpoint of strength. The shape of the perforations 21h can be appropriately selected, for example, circular, elliptical, polygonal (square, rectangle, rhombus, etc.), or elongated. The arrangement of the perforations 21h can also be appropriately selected, and an appropriate regular or irregular arrangement such as a staggered or matrix can be adopted. The perforation ratio of the mesh material can be appropriately determined, for example, it can be about 10 to 90%. From the viewpoint of strength, a perforation ratio of about 10 to 30% is preferable.

[0032] Characteristically, as shown in detail in Figure 4, the cylindrical filter media 22 has an adhesive portion 26 in the axial direction Y between a pair of sealing portions 25, where the valley bottoms 22b between each fold 23 and the core tube 21 are bonded via adhesive 26b, and an unadhesive portion 27 where the valley bottoms 22b between each fold 23 and the core tube 21 are not bonded, and no band is wrapped around the outer surface of the cylindrical filter media 22.

[0033] When such an adhesive structure is adopted, the adhesive 26b that bonds the valley bottoms 22b between each pleat 23 of the cylindrical filter media 22 to the core tube 21 penetrates into the permeable holes 21h of the core tube 21, as shown in Figure 4, thereby forming an adhesive portion 26 with excellent adhesion to the core tube 21. Therefore, compared to conventional examples where the adhesive is bonded to the band 29, the adhesive portion 26 to the core tube 21 is less prone to damage during use, and the shape retention of the pleats 23 is improved. Furthermore, in conventional methods, when the band 29 wrapped around the outer surface of the cylindrical filter media 22 is bonded to the top of the cylindrical filter media 22, the shape of the pleats 23 is maintained in a desirable state as long as the adhesion is maintained. However, if the adhesive portion 26 is damaged, the band may act to maintain the pleats 23 in an inappropriate shape. In contrast, this cylindrical pleated filter 20 does not have such problems. Furthermore, since the band 29 is not wrapped around the outer surface of the cylindrical filter media 22, there is no risk of the tops of the folds 23 rubbing against the band 29 and creating holes, as in conventional designs.

[0034] The adhesive 26b of the adhesive portion 26 may be provided only between the valley bottoms 22b between each fold 23 and the core tube 21 (i.e., intermittently in the circumferential direction C), as long as it adheres the valley bottoms 22b between each fold 23 to the core tube 21. However, as shown in the illustrated example, it is preferable that the adhesive 26b is applied to the outer surface of the core tube 21 in a continuous annular shape in the circumferential direction C. This is preferable because it makes it easier to allow the adhesive 26b to penetrate into the perforations 21h of the core tube 21, even if the opening ratio of the core tube 21 is reduced and the strength of the core tube 21 is increased.

[0035] The thickness of the adhesive 26b in the adhesive portion 26 can be determined as appropriate, but it is preferable that the thickness t1 of the adhesive 26b on the core tube 21 between the inner surfaces of each fold 23 is greater than the thickness t2 of the adhesive 26b between the valley bottoms 22b between each fold 23 and the core tube 21, as shown in the illustrated example. This allows the base of the folds 23 of the cylindrical filter material 22 to be firmly bonded to the core tube 21, and the orientation of the base of the folds 23 can be restricted by the adhesive 26b, thereby improving the shape retention of the folds 23. Furthermore, even with this arrangement of adhesive 26b, the spacing between adjacent valley bottoms 22b in the circumferential direction C is narrower compared to conventional band fixing, so the amount of adhesive 26b used is relatively small. Such an adhesive structure can be formed by continuously applying adhesive 26b in the circumferential direction C to the outer surface of the core tube 21 to a desired thickness, and then, when wrapping and bonding the cylindrical filter material 22 to the outer surface of the core tube 21, pressing the valley bottoms 22b between the folds 23 against the adhesive 26b on the outer surface of the core tube 21, thereby embedding the valley bottoms 22b between the folds 23 into the adhesive 26b. The thickness t1 of the adhesive 26b on the core tube 21 between the inner surfaces of each fold 23 can be appropriately determined by the amount of adhesive 26b applied and the degree to which the valley bottoms 22b between the folds 23 are embedded, for example, it can be about 5 to 15 mm. The thickness t2 of the adhesive 26b between the valley bottoms 22b and the core tube 21 can also be appropriately determined by the amount of adhesive 26b applied and the degree to which the valley bottoms 22b between the folds 23 are embedded, for example, it can be 3 mm or less.

[0036] Furthermore, the width 26y of the adhesive portion 26 in the axial direction Y can be determined as appropriate, for example, to about 10 to 50 mm, and especially to about 20 to 30 mm.

[0037] The adhesive 26b of the adhesive portion 26 may or may not protrude into the core tube 21 through the perforation hole 21h. However, as shown in the illustrated example, it is preferable that the adhesive 26b protrudes into the core tube 21 through the perforation hole 21h, and that the portion of the adhesive 26b that protrudes into the core tube 21 has a barb portion 26h located outside the edge of the perforation hole 21h, because this makes it difficult for the adhesive 26b to peel off from the core tube 21 due to the anchoring effect. It is preferable that the barb portion 26h of the adhesive 26b is formed in all of the perforation holes 21h having the adhesive 26b, but it may also be formed in only a part of the adhesive portion 26 (for example, the central part of the adhesive portion 26 in the axial direction Y) of the perforation hole 21h. The lip portion 26h may have a portion that is not located outside the edge of the through-hole 21h, as long as it has a portion that is located outside the edge of the through-hole 21h. However, as shown in the illustrated example, it is preferable that the entire periphery of the portion of the adhesive 26b that protrudes inward into the core tube 21 is located outside the periphery of the through-hole 21h.

[0038] In the adhesive portion 26, when adhesive 26b is applied to the outer surface of the core tube 21 in a continuous annular shape in the circumferential direction C, it is preferable that the distance 22d between the centers of adjacent valley bottoms 22b in the circumferential direction C in the cylindrical filter material 22 is 2 to 5 times the distance 21d between the centers of the permeable holes 21h in the circumferential direction C in the core tube 21. This ensures that permeable holes 21h are always present between adjacent valley bottoms 22b in the circumferential direction C of the core tube 21, and the anchoring effect of these permeable holes 21h is also exerted, resulting in stronger adhesion of the adhesive portion 26. The distance 22d between the centers of adjacent valley bottoms 22b in the circumferential direction C can be varied by the number of folds 23. The number of folds 23 can be determined as appropriate, and as an example, it can be 60 to 180.

[0039] The adhesive portion 26 is provided only once between a pair of sealing portions 25. However, if the dimensions of the cylindrical filter media 22 are large and shape retention is poor, multiple adhesive portions 26 can be provided at intervals in the axial direction Y, as shown in Figure 2, as needed. In the former case, the area between the adhesive portion 26 and the sealing portion 25 becomes an unadhesive portion 27. In the latter case, not only the area between the adhesive portion 26 and the sealing portion 25, but also the area between adjacent adhesive portions 26 becomes an unadhesive portion 27. Examples of cases where the dimensions of the cylindrical filter media 22 are large include cases where the outer diameter of the cylindrical filter media 22 is 12 to 50 cm, the inner diameter of the cylindrical filter media 22 is 7 to 25 cm, the inner diameter of the cylindrical filter media 22 is 0.5 to 0.6 times the outer diameter of the cylindrical filter media 22, and the axial distance 25y between a pair of sealing portions 25 in the axial direction Y is 0.3 to 2.2 m. In this case, for example, adhesive portions 26 can be provided between a pair of sealing portions 25 with a center spacing 26d of 100 to 200 mm in the axial direction Y, and the width 26y in the axial direction Y of one adhesive portion 26 can be 20 to 30 mm.

[0040] Apart from the sealing portion 25 and the adhesive portion 26, it is preferable that the cylindrical filter material 22 is not bonded with adhesive, but adhesive may be used for bonding if necessary. For example, between a pair of sealing portions 25, it is preferable that the inner surfaces of each fold 23 (i.e., the opposing surfaces of the pair of wall portions 23w constituting the fold 23) and the outer surfaces of adjacent folds 23 are not bonded to each other, except for the adhesive portion.

[0041] The cylindrical filter media 22 can be formed from a sheet-like filter media. The filter media can be selected from appropriate filter media (filter paper, filter cloth, filter membrane, etc.) depending on the type of fluid to be treated (whether it is a gas or a liquid, etc.), the characteristics of the material to be separated or removed (size, etc.), the required strength, etc. For example, when the fluid to be treated is a liquid, filter membranes such as MF membranes, UF membranes, and NF membranes can be used. Such filter membranes include porous membranes formed by melting resin and forming it into a film, and fibrous membranes formed by laminating and integrating resin fibers by methods such as electrospinning, electroblowing, and melt-blowing, and both can be used. The pore structure of the porous membrane can be appropriately selected from known structures such as lace-like, nodal, and fibril-like structures. Furthermore, when the fluid to be treated is a gas and dust collection is performed, the filter media used for the cylindrical filter media can be appropriately selected from woven or nonwoven fabrics for bag filters.

[0042] The filtration membrane may be single-layer or multi-layer, and may be symmetric or asymmetric. Furthermore, the filtration membrane may be hydrophilic or hydrophobic.

[0043] In particular, when using a filter material having a two-layer structure of nonwoven fabric and a PTFE membrane or nanofiber membrane, and the outer surface of the tubular filter material is formed of a PTFE membrane or nanofiber membrane and the inner surface is formed of nonwoven fabric, the outer surface of the tubular filter material has poor adhesion to adhesives, and the adhesive part tends to peel off with conventional band fixing methods. However, adopting the adhesive structure between the bottom of the valleys between the folds and the core tube as described above is preferable because the adhesion does not deteriorate even when the tubular filter material has a structure like that of this embodiment.

[0044] <Filtration device> The cylindrical pleated filter 20 described above can be installed in, for example, the filtration device 100 shown in Figure 6. That is, this filtration device 100 is suitable for gas processing and comprises a filtration container 10 having a supply port 11 for the gas to be processed DG and an outlet 13 for the processed gas CG, a cylindrical pleated filter 20 placed inside the filtration container 10, and an injection nozzle 14 that intermittently supplies compressed air into the core tube 21 of the cylindrical pleated filter 20. One opening of the core tube 21 of the cylindrical pleated filter 20 is closed by a closing plate 15, and the other opening is connected to a discharge channel 12 leading to the outlet 13. The injection nozzle 14 is positioned to face the other opening of the core tube 21 from this discharge channel 12. In the illustrated example, the cylindrical pleated filter 20 is positioned with its axis aligned vertically, its lower opening is closed by a closing plate 15, and its upper opening is connected to the discharge channel 12. However, the installation position of the cylindrical pleated filter 20 can be changed as appropriate. In addition, a discharge chute 16 is provided below the filtration container 10, through which the particles PC separated by the cylindrical pleated filter 20 are discharged.

[0045] Although not shown in the diagram, a pulse air passage supplying compressed air from an air compressor is connected to the injection nozzle 14, and a pulse blow valve and a flow control valve are provided in this pulse air passage. This allows compressed air at a predetermined pressure and flow rate to be injected from the injection nozzle 14 at predetermined injection times and intervals. These devices constitute an air pulse supply system. As an example, the pressure of the compressed air supplied to the injection nozzle 14 can be approximately 260 to 900 kPa, particularly 300 to 500 kPa, and the injection time can be approximately 0.1 to 0.3 seconds.

[0046] In the filtration operation of this filtration device 100, the gas to be treated DG is supplied between the cylindrical pleated filter 20 and the filtration container 10 via the supply port 11 by a blower fan (not shown), and the entire amount is filtered by the cylindrical filter media 22 of the cylindrical pleated filter 20. As a result, the substances to be separated in the gas to be treated DG adhere to the outer surface of the cylindrical filter media 22 or are captured inside, and the treated gas CG that has permeated to the inside of the cylindrical filter media 22 is discharged from the outlet 13 through the permeate holes 21h and the core tube 21. By attaching and depositing adsorbent powder such as activated carbon to the outer surface of the cylindrical filter media 22 in advance, and passing the gas to be treated DG through this adsorbent powder deposit layer, substances to be separated that cannot be separated by the cylindrical filter media 22 can also be adsorbed by the adsorbent powder.

[0047] When a cleaning operation is required due to fouling or breakthrough, the filtration device 100 can perform backwashing by intermittently supplying compressed air from the injection nozzle 14 into the core tube 21 (i.e., the secondary side of the cylindrical pleated filter 20). That is, the intermittently supplied compressed air passes from the inside to the outside of the cylindrical filter material 22, and the shock waves of the compressed air applied to the cylindrical filter material 22 cause the cylindrical filter material 22 to vibrate, which can dislodge particles PC adhering to the outer surface and inside of the cylindrical filter material 22. When such backwashing with air pulses is performed many times, the adhesive portion 26 tends to peel off in conventional band-fixed cylindrical pleated filters 20, but in the filtration device 100, as described above, the adhesive portion 26 is strong, so the durability against backwashing with air pulses is dramatically improved. Furthermore, although this was not initially anticipated, when backwashing is performed with air pulses in this filtration device 100, the folds 23 vibrate effectively because the top of the cylindrical filter media 22 is not restrained, resulting in a significantly improved cleaning effect compared to the conventional band-fixed cylindrical pleated filter 20. The target particles PC that fall off the cylindrical filter media 22 are discharged via the discharge chute 16.

[0048] Figure 7 shows another filtration device 101 equipped with the cylindrical pleated filter 20 described above. Specifically, this filtration device 101 is suitable for liquid processing and comprises a filtration container 30 having a supply port 31 for the liquid to be processed DL such as slurry and an outlet 33 for the processed liquid CL, a cylindrical pleated filter 20 placed inside the filtration container 30, and a spraying device 34 for spraying cleaning liquid onto the outer surface of the cylindrical filter material 22 of the cylindrical pleated filter 20. One opening of the core tube 21 of the cylindrical pleated filter 20 is closed by a closing plate 35, and the other opening is connected to a discharge channel 32 leading to an outlet 13. In the illustrated example, the cylindrical pleated filter 20 is positioned with its axis aligned vertically, with the upper opening closed by the closing plate 35 and the lower opening connected to the outlet 33 via the discharge channel 32, but the installation position of the cylindrical pleated filter 20 can be changed as appropriate. In addition, a cleaning liquid outlet 36 is provided below the filtration container 30.

[0049] The spraying device 34 can also have spray nozzles arranged along the entire circumferential wall of the filtration container 30 so that the cleaning solution can be sprayed over the entire circumferential surface of the cylindrical filter media 22. However, in the illustrated example, the cylindrical pleated filter 20 is supported within the filtration container 30 so as to be rotatable about its axis, and is configured to be rotated by a drive device M such as a motor. This allows the spraying nozzles 34n to be positioned at one (or more) specific circumferential location on the side wall of the filtration container 30 to spray the cleaning solution SL linearly over the entire axial direction Y of the cylindrical filter media 22. Therefore, during cleaning operation, the entire circumferential surface of the cylindrical filter media 22 can be cleaned by spraying the cleaning solution from the spraying device 34 while rotating the cylindrical pleated filter 20.

[0050] In the filtration operation of this filtration device 101, the liquid DL to be treated is supplied between the cylindrical pleated filter 20 and the filtration container 30 via a supply port 31 by a pump (not shown), and the entire volume is filtered by the cylindrical filter media 22 of the cylindrical pleated filter 20. As a result, the substances to be separated in the liquid DL are attached to the outer surface of the cylindrical filter media 22 or captured inside, and the treated liquid CL (filtrate) that has permeated to the inside of the cylindrical filter media 22 is discharged from the outlet 33 through the permeate holes 21h and the core tube 21. By attaching and depositing adsorbent powder such as activated carbon to the outer surface of the cylindrical filter media 22 in advance, and passing the liquid DL to be treated through this adsorbent powder deposit layer, substances to be separated that cannot be separated by the cylindrical filter media 22 can also be adsorbed by the adsorbent powder.

[0051] When a cleaning operation is required due to fouling or breakthrough, the filtration device 101 can spray cleaning solution SL from a spray nozzle onto the outer surface of the cylindrical filter media 22 to detach and remove cake adhering to the cylindrical filter media 22. In conventional band-fixed cylindrical pleated filters 200, when cleaning solution SL is sprayed onto the outer surface of the cylindrical filter media 22 by the spraying device 34, the cleaning solution SL is blocked by the band 29, inevitably reducing the cleaning effect. Also, in conventional band-fixed cylindrical pleated filters 200, when cleaning solution SL is sprayed onto the outer surface of the cylindrical filter media 22 by the spraying device, a force that peels off the adhesive portion 26 is likely to act. In contrast, in the cylindrical pleated filter 20 of the filtration device 101, the band 29 does not interfere with cleaning, and there is almost no force that peels off the adhesive portion 26. Therefore, both backwashing efficiency and cleaning durability are improved. The separation target particles PC that have fallen out of the cylindrical filter media 22 are discharged together with the washing liquid SL through the washing liquid outlet 36.

[0052] The cleaning solution SL is not particularly limited, but one preferred example is clean water. Furthermore, cleaning particles such as silica beads can be mixed into the cleaning solution.

[0053] (Fluid to be processed) The fluids to be treated, DL and DG, may be liquids or gases. Examples of liquids to be treated, DL, include river and lake water, seawater, groundwater, spring water, household wastewater, factory and business wastewater, and ship wastewater. The filter module 1 described above can be used to purify (separate hazardous substances from) these fluids. Examples of gases to be treated, DG, include gases containing volatile organic compounds (VOCs) and odorous substances such as ammonia, high-humidity gases, carbon dioxide-containing gases, and polluted air containing dust in tunnels and factories. For the separation of carbon dioxide, metal-organic frameworks (MOFs) can be used as adsorbent powders. [Explanation of Symbols]

[0054] 10,30…Filtration container, 11,31…Supply port, 12,32…Discharge channel, 13,33…Discharge port, 14…Injection nozzle, 15,35…Blocking plate, 16…Discharge chute, 20,200…Cylindrical pleated filter, 21…Core tube, 21h…Perforation hole, 22…Cylindrical filter media, 22b…Valley bottom, 23…Fold, 23w…Wall, 24…Space, 25…Sealing part, 25b…Sealing adhesive, 25c…Annular lid, 26…Adhesive part, 26b…Adhesive, 26h…Return part, 27…Non-adhesive part, 29…Band, 34…Spraying device, 36…Washing liquid discharge port, 100,101…Filtration device, CL…Treated liquid, DG…Gas to be treated, DL…Liquid to be treated, PC…Particles, R…Radial direction, SL…Washing liquid, Y…Axial direction.

Claims

1. A core tube whose wall is made of a mesh material having fluid permeable holes, A cylindrical filter material surrounds the outer surface of the core tube and is bent in a bellows-like manner so that folds extending in the axial direction are repeated in the circumferential direction, A cylindrical pleated filter having a pair of sealing parts that seal both ends in the axial direction of the space between the core tube and the cylindrical filter material, The cylindrical filter material has, midway in the axial direction between the pair of sealing portions, an adhesive portion where the bottom of each fold and the core tube are bonded together via adhesive, and an unadhesive portion where the bottom of each fold and the core tube are not bonded together. The band is not wrapped around the outer surface of the cylindrical filter material. A cylindrical pleated filter characterized by the following features.

2. In the adhesive portion, the adhesive is applied to the outer surface of the core tube in a continuous, annular manner in the circumferential direction, and the thickness of the adhesive on the core tube between the inner surfaces of each fold is greater than the thickness of the adhesive between the bottom of the valleys between each fold and the core tube. A tubular pleated filter according to claim 1.

3. The adhesive protrudes to the inside of the core tube through the perforation hole. The portion of the adhesive that protrudes inward from the core tube has a barb that is located outside the edge of the perforation hole. A tubular pleated filter according to claim 1 or 2.

4. In the aforementioned adhesive portion, the adhesive is applied to the outer surface of the core tube in a continuous, annular manner in the circumferential direction. The adhesive protrudes to the inside of the core tube through the perforation hole. The portion of the adhesive that protrudes inward from the core tube has a barb portion located outside the edge of the perforation hole. The circumferential distance between the centers of adjacent valley bottoms in the cylindrical filter material is 2 to 5 times the circumferential distance between the centers of the permeable holes in the core tube. A tubular pleated filter according to claim 1 or 2.

5. The number of folds is 60 to 180. The outer diameter of the cylindrical filter material is 12 to 50 cm. The inner diameter of the aforementioned cylindrical filter material is 7 to 25 cm. The inner diameter of the cylindrical filter material is 0.5 to 0.6 times the outer diameter of the cylindrical filter material. The axial distance between the pair of sealing portions is 0.3 to 2.2 m. The adhesive portion is provided between the pair of sealing portions at a central interval of 100 to 200 mm in the axial direction. The axial width of one of the aforementioned adhesive portions is 20 to 30 mm. A tubular pleated filter according to claim 1 or 2.

6. The outer surface of the cylindrical filter material is formed of a PTFE film or a nanofiber film, and the inner surface is formed of a nonwoven fabric. A tubular pleated filter according to claim 1 or 2.

7. A core tube whose wall is made of a mesh material having fluid permeable holes, A cylindrical filter material surrounds the outer surface of the core tube and is bent in a bellows-like manner so that folds extending in the axial direction are repeated in the circumferential direction, A cylindrical pleated filter comprising a pair of sealing parts that seal both ends in the axial direction of the space between the core tube and the cylindrical filter material, A filtration device configured to supply the fluid to be treated to the outside of the cylindrical filter material and filter the entire volume through the cylindrical filter material, and to discharge the treated fluid that has permeated to the inside of the cylindrical filter material through the permeate holes and the core tube, The cylindrical filter material has, midway in the axial direction between the pair of sealing portions, an adhesive portion where the bottom of each fold and the core tube are bonded together via adhesive, and an unadhesive portion where the bottom of each fold and the core tube are not bonded together. The band is not wrapped around the outer surface of the cylindrical filter material. The system is equipped with an air pulse supply device that intermittently supplies compressed air into the core tube. A filtration device characterized by the following features.

8. A core tube whose wall is made of a mesh material having fluid permeable holes, A cylindrical filter material surrounds the outer surface of the core tube and is bent in a bellows-like manner so that folds extending in the axial direction are repeated in the circumferential direction, A cylindrical pleated filter comprising a pair of sealing parts that seal both ends in the axial direction of the space between the core tube and the cylindrical filter material, A filtration device configured to supply the fluid to be treated to the outside of the cylindrical filter material and filter the entire volume through the cylindrical filter material, and to discharge the treated fluid that has permeated to the inside of the cylindrical filter material through the permeate holes and the core tube, The cylindrical filter material has, midway in the axial direction between the pair of sealing portions, an adhesive portion where the bottom of each fold and the core tube are bonded together via adhesive, and an unadhesive portion where the bottom of each fold and the core tube are not bonded together. The band is not wrapped around the outer surface of the cylindrical filter material. The cylindrical filter material is equipped with a spraying device that sprays cleaning solution onto its outer surface. A filtration device characterized by the following features.

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