JP2012245428A - Pleated filter, ballast water treatment apparatus using the same and method for manufacturing pleated filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pleated filter which prevents deterioration and breakage caused by usage, and capable of a stable, long-time use; a method for manufacturing the same; and a ballast water treatment apparatus using the same.SOLUTION: A pleated filter is formed by periodically folding a planar base material, in which a mountain part and a valley part are constituted repeatedly and continuously. A breakage prevention means is given at the valley part of the folded part. In the breakage prevention means, the relationship between the bending radius R (mm) of a resin reinforcing means provided at the valley part or the valley part and the thickness of the base material t (mm) meets 2t≤R≤10t.

Description

  The present invention relates to a structure of a pleated filter mainly used for liquid filtration, and more particularly to a pleated filter used in a system for treating ballast water stored in a ship and used for filtering a large amount of water. Related to the device.

  A wide variety of filters are used for the purpose of separating and removing solids as contaminants from gases and liquids, and pleated filters with a pleated shape and a large filtration area are also used mainly for gas applications such as air purifiers. ing. Patent Document 1 shows an example in which a pleated filter formed in a cylindrical shape is used as a filter device for removing sludge from a cutting fluid of a machine tool. In this device, it is said that a filter device having a high filter cleaning effect can be provided by ejecting liquid toward the outer surface of the filter while rotating the cylindrical filter.

  On the other hand, in recent years, the treatment of ballast water loaded on ships has become a problem. Ballast water is seawater that is loaded on a ship for safe navigation even in an empty state, and various methods for purifying ballast water to remove or kill or inactivate microorganisms have been studied. A method of using filtration for the purpose of removing relatively large microorganisms has also been studied. For example, Patent Document 2 describes a method for producing ballast water using a filtration membrane.

JP 2008-93783 A JP 2006-728 A

  When using brackish water and seawater such as seawater desalination and ballast water, or water treatment such as sewage, domestic wastewater, and industrial wastewater, pre-filtration treatment is required to remove foreign substances, dust, and microorganisms in the water. The inventors of the present application are considering the application of a pleated filter to such filtration. Here, it is necessary to filter a large amount of water in as short a time as possible. However, large-scale, high-flow operation is a technical problem that generally tends to cause a reduction in throughput and filtration function due to early clogging. Yes.

For example, in a filtration device that incorporates a cylindrical filter in a cylindrical container and collects the liquid flowing into the cylindrical filter from the outside as a filtrate, the filter target surface is filtered from a nozzle provided on the side of the cylindrical container. The filtrate accumulated on the filter surface is washed by jetting to a part of the filter to recover the permeation flux, and the filtered filtrate that has been washed away is drained from the pre-filtration chamber to continuously maintain a stable filtration state. Is possible. What is important for such a system to maintain continuous filtration stably is the cleaning effect of ejection of the liquid to be filtered onto the filter filtration surface. In order to efficiently and effectively perform local cleaning jets changing the cleaning site of the filter over time and cleaning the entire filter, the cylindrical filter is rotated by a motor drive during filtration, It is desirable to continuously and periodically change the location where the ejection from the ejection nozzle hits. In order to reliably perform this rotary cleaning and keep a high filtration flow rate stable, it is necessary to maintain the ejection of the liquid to be filtered from the nozzle at a flow rate level that is higher than a certain level. As a result of receiving a high flow rate, the cylindrical filter may deteriorate over time, resulting in a hole due to breakage, and some of the liquid to be filtered may be mixed directly into the filtrate without passing through the filter. I understood.
Therefore, an object of the present invention is to provide a pleated filter that can be used stably for a long period of time, and a filtering device using the pleated filter that prevents deterioration and breakage due to use.

  As a result of diligent investigations on the deterioration of the filter, the inventors of the present application tend to generate holes due to breakage in the bent portion of the pleated valley of the filter that has been ejected at a high flow rate. It was confirmed that a part of the liquid was directly mixed into the filtrate without passing through the filter, and the present invention was reached.

  A pleat filter formed by periodically bending a planar substrate and having a crest and a trough repeated continuously, wherein the trough that is a bent portion is provided with breakage prevention means. It was set as the filter (Claim 1).

  In the pleated filter, the stress tends to concentrate on the bent portion of the pleat due to the pressure of the liquid to be filtered or due to the fluctuation of the pressure. In particular, when the liquid to be filtered is a liquid such as water, the pressure received by the filter is larger than that in the case of a gas such as air, and the filter is easily damaged at the bent portion. According to the study by the inventors, it has been found that this breakage is likely to occur at a bent portion that becomes a valley when viewed from the side in contact with the liquid to be filtered. A force in the direction of opening the bend is applied to the valley, and the bending angle of the bent portion varies due to pressure fluctuation. Therefore, it is considered that the possibility of breakage is increased by tensile stress and repeated bending. Therefore, by providing a breakage prevention means on at least the side of the bent portion that becomes the trough, the strength of the pleated filter can be increased, the life can be extended, and the filter device can be operated for a long time. Moreover, it becomes possible to improve the filtration amount and filtration speed of the filtration apparatus using such a pleated filter by increasing the strength.

  Such a breakage prevention means may be a resin reinforcement means using a resin provided in a bent portion of the valley as a reinforcing body (Claim 2). The resin reinforcing means refers to all reinforcing means using resin as a reinforcing body. The filter base material formed by impregnating the resin is most preferably used because the strength and life are effectively improved by integrating the base material and the reinforcing body resin (claim 3). The present invention also includes an embodiment in which the pores of the porous base material are filled by impregnation, and the impregnated portion becomes nonporous. By becoming non-porous, the strength of the bent portion is further reinforced. The impregnation is preferably performed at least on the valley side surface of the valley portion, that is, the surface on the side where the liquid to be filtered is supplied. Further, it may be formed by attaching a resin member such as a resin sheet to one or both surfaces of the surface of the substrate (claim 4). The affixing may use an adhesive or may utilize the adhesiveness of the resin itself. As one form of these, a form in which a part of the fused resin is impregnated in the base material when the resin sheet as the reinforcing body is attached by heat fusion is also included.

  As another breakage prevention means, it is preferable that the bending radius R of the valley and the thickness t (mm) of the base material have a relationship of 2t ≦ R ≦ 10t (Claim 5). By bending the base material, the thickness of the base material at the top of the bent part is generally thinner than that of the original base material, and especially when bent at an acute angle, stress concentration occurs in that part and it is easy to break. . Breaking can be suppressed by setting the bending radius of the bent portion as described above. If it is smaller than 2t, the effect of preventing breakage cannot be obtained sufficiently. In addition, considering that the purpose of the pleat is to increase the filter area per volume by folding, it is desirable that the filter gap be within a few millimeters, and accordingly the bend radius should be less than 10t. preferable. Preferably it is 5 t or less and 2 t or more. For example, when a 500 μm nonwoven fabric is used as the substrate, the bending radius R is preferably 1 mm or more. A more preferable range is 1 to 3 mm. Here, the bending radius R refers to the minimum radius of the circle in contact with the bent valley side surface, and the bending radius of 20 samples or more extracted from the plurality of valleys of the pleated filter to be used is measured with a magnifying glass or a photograph. It is used as an average value measured by a normal dimension measuring method.

  Of course, it is more preferable that the bending radius of the trough is formed in a desired range while providing the resin reinforcing means in combination with the above-described resin reinforcing means. It is because the effect of reinforcement is exhibited more by having both effects.

  The pleated filter described above is particularly preferably used when the shape of the pleated filter is cylindrical with the ridgeline direction of the mountain portion as the axis direction, and the breakage prevention means is provided at least in the valley portion viewed from the outside of the cylindrical shape. (Claim 7). Further, as an apparatus that is a particularly preferred mode of use, the water to be treated in which the cylindrical pleated filter is arranged in a cylinder so as to surround the axis, and the water to be treated that is the liquid to be filtered flows out toward the outer peripheral surface of the pleated filter. A case having a nozzle, an outer tube portion provided inside the nozzle port of the water nozzle to be treated and surrounding the pleated filter, and filtered water that has passed through the filter is led out from the inside of the pleated filter cylinder to the outside of the case. A ballast water treatment apparatus including a filtered water flow path and a discharge flow path for discharging discharged water that has not been filtered by the pleated filter to the outside of the case is mentioned (claim 8).

  In such an apparatus, a high flow rate of water to be treated is ejected from the water nozzle to be treated on the outer surface side of a large cylindrical pleated filter, and the surface of the cylindrical pleated filter is rotated while being cleaned. Filtration is performed. Since the amount of water to be treated is large and the pressure is large, the stress applied to the bent portion of the pleat is large, and the filter vibrates in the direction in which the pleat interval is opened and closed by the ejection from the water to be treated. For this reason, for example, the strength of the bent portion, which has not been a problem with a small pleated filter for the purpose of air cleaning or the like, is required, and the breakage prevention means of the present invention functions extremely effectively.

  Next, a preferred method for producing these pleated filters will be described. First, a flat plate belt-like substrate is prepared. The substrate is preferably made of a porous resin. A crest and a trough are repeatedly and continuously formed by periodically bending a planar substrate. At least a part of the resin sheet is impregnated in the base material by heating the base material and the resin sheet at the part to which the resin sheet is attached, and the step of attaching the resin sheet to at least one surface of the base material to be the bent portion It is good to set it as the manufacturing method of a pleat filter provided with the impregnation process to perform and the cooling process which cools and fixes in the state which bent the bending part (Claim 9). This is effective because reinforcement by impregnation and shape fixing by cooling and fixing the same can be performed simultaneously or continuously.

  Here, when the cooling step is a step of cooling the metal jig having a constant radius in contact with the bent portion, reinforcement by impregnation of the resin and reinforcement by the constant bending radius can be formed at the same time, which is particularly preferable. (Claim 10).

  According to the above invention, it is possible to provide a pleated filter that contributes to the stable use for a long period of time, a method for manufacturing the pleated filter, and a ballast water treatment device using the pleated filter that prevents breakage due to use.

It is a perspective schematic diagram explaining the typical structure of the pleat filter concerning this invention. It is the figure which expanded a part of pleats of FIG. It is the schematic diagram which expanded the bending part reinforced with resin as an example of the fracture | rupture prevention means by this invention. It is a schematic diagram explaining another aspect of the bending part reinforced with resin as an example of the fracture | rupture prevention means by this invention. It is a schematic diagram explaining another aspect of the bending part reinforced with resin as an example of the fracture | rupture prevention means by this invention. It is a schematic diagram explaining another aspect of the bending part reinforced with resin as an example of the fracture | rupture prevention means by this invention. It is a schematic diagram explaining the bending part and tip bending radius as an example of the fracture | rupture prevention means by this invention. It is a figure explaining the manufacturing method of the damage prevention means concerning this invention. It is a figure which shows an example of the ballast water treatment apparatus by this invention, and is a schematic diagram which shows the structure of the vertical cross section containing an axis line. It is a figure which shows an example of the ballast water treatment apparatus by this invention, and is a figure which shows typically the structure of the horizontal AA cross section in FIG.

  The configuration of the pleated filter and the ballast water treatment apparatus according to the present invention will be described below with reference to the drawings. In addition, this invention is not limited to this, It is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

(Configuration of pleat filter)
FIG. 1 is a schematic perspective view illustrating a typical configuration of a pleated filter according to the present invention. This filter has a so-called pleated shape obtained by alternately folding a band-like planar base material in a mountain-and-valley shape, and is further formed by joining them in a cylindrical shape. Hereinafter, a cylindrical pleated filter will be described as a particularly effective representative example. However, the breakage preventing means according to the present invention can be applied to a case where a pleated filter is used as a flat filter without using a cylinder, and the same effect can be obtained. It is what you play.

  In FIG. 1, it is assumed that the liquid to be filtered is supplied from the outside of the cylinder of the cylindrical pleated filter 10 and the liquid filtered by the filter substrate 1 is discharged from the inside of the cylinder. The surface on the side in contact with the liquid to be filtered is referred to as the front surface of the filtration, and the surface on the side where the filtered filtrate is discharged is referred to as the rear surface of the filtration. In the configuration of this example, the filter surface outside the cylinder corresponds to the front surface of filtration, and the filter surface inside the cylinder corresponds to the rear surface of filtration. Even when the filter is a flat plate or the like that is not cylindrical, it may be read as either the front surface of the filtration or the rear surface of the filtration according to the form of use of the filtration. The peak and valley of the pleat-shaped fold when viewed from the front of the filtration are defined. In FIG. 1, for example, A part in the figure is a valley part and B part is a mountain part.

  A porous resin sheet is used as the filter substrate. For example, a porous structure such as a stretched porous body, a phase-separated porous body, or a nonwoven fabric made of polyester, nylon, polyethylene, polypropylene, polyurethane, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), etc. is used. However, for the purpose of performing a high flow rate treatment, a nonwoven fabric made of polyester such as polyethylene terephthalate is particularly preferably used.

  FIG. 2 is an enlarged view of a part of the pleats of FIG. A indicates a valley and B indicates a mountain. In the pleated filter that has received the pressure of the liquid to be filtered from the front surface of the filtration, a force P in a direction to spread is applied to the valley, and tensile stress concentrates on the base material 1 in the valley. Further, the bending portion may be repeatedly bent due to pressure fluctuation. By these, it is thought that the hole by a tear is easy to produce especially in a trough part. The present invention is characterized in that it has been found that preventing breakage of such a bent portion, particularly a trough, is effective for extending the life of the pleated filter and thus for a long-term stable operation of the filtration device. Of course, reinforcement may also be provided at the mountain.

  As a means for preventing damage to a portion where the base material which is such a porous resin sheet is bent, the vicinity of the bent portion is reinforced with resin. As an example of reinforcing means using a resin as a reinforcing body, impregnation of a resin into a base material is preferably used. FIG. 3 is a schematic diagram for enlarging and explaining the bent portion of the pleated filter reinforced with resin. In the trough A, a state in which the bending inner side surface of the base material 1 is impregnated with the reinforcing resin 2 is shown. The substrate 1 is a porous resin, and the resin 2 adheres to the substrate surface on the surface of the pores in the porous holes of the substrate 1. If the hole is filled by impregnation and the impregnated part becomes non-porous, a stronger reinforcing effect can be obtained by obtaining the reinforcing effect of the bent portion by the force of the pressure of the filtrate not causing the hole to expand and tear. It is done.

  4 and 5 exemplify another embodiment of impregnation. In FIG. 4, the outer surface of the base material 1 of the bent portion is impregnated with the resin 2, and in FIG. 5, the entire surface of the base material 1 is covered with the resin. 2 is impregnated. In FIG. 5, the impregnated resin 2 is attached with a thickness so as to further cover the surface of the substrate 1. Thus, it is effective not only to impregnate the inside of the base material 1 but also to adhere the resin to the surface. In the valley, at least the front surface of the filter is impregnated with resin is preferable as reinforcement against tensile stress.

  As the resin to be impregnated, thermosetting resins such as silicone, epoxy, and polyurethane, thermoplastic resins such as polyester, nylon, polyethylene, polypropylene, ETFE, and PVdF, or those obtained by diluting PVdF and silicone with a solvent can be used. Yes, but not particularly limited, it is desirable to be familiar with the filter material. In addition, the resin to be impregnated needs fluidity to penetrate into the porous body when impregnated, but after impregnation, the resin must be integrated with the filter so that it cannot be easily separated. In the case of a thermosetting resin, it may be cured by heating after impregnation, and in the case of a two-component curable resin, after impregnation immediately after mixing, in the case of a resin whose viscosity has been reduced by diluting the solvent, the solvent is dried for a while after impregnation. It is good to cure after a while.

  FIG. 6 illustrates still another resin reinforcing means, and is an example in which the resin sheet 3 is attached to the surface of the substrate 1. Thus, even by means without impregnation, reinforcement is possible by receiving the pressure of the liquid to be filtered and sharing the force received by the base material by adhesion to the base material 1. Although not shown, the effect can also be obtained by attaching a resin sheet to the rear surface of the base material 1 after filtration or by attaching it to both surfaces.

  Next, a bending part and a bending radius are demonstrated. The bend radius of the fold is defined by the minimum radius of the trough filtration front. FIG. 7 is a schematic diagram for explaining a bent portion and a tip bending radius, and is an enlarged view of a trough portion. Here, the inside of the valley is the filtration front surface. A bending part means the part by which the flat base material before bending was bent. When viewed in cross section with reference to FIG. 7, the straight portion L is a portion that is not bent, and a section C that forms a curved portion is a bent portion. The minimum radius R (mm) of the inscribed circle to the curved surface of the folded front portion of the bent portion is defined as a bending radius. The smaller R is, the more easily the fracture of the bent portion, that is, the tearing or the hole. A suitable bending radius R is 2t ≦ R ≦ 10t in relation to the thickness t (mm) of the substrate.

  Moreover, when reinforcing with resin, it is preferable that the resin reinforcing means is provided so as to reinforce over the entire bent portion. Since the boundary between the reinforced portion and the non-reinforced portion is discontinuous, stress tends to concentrate. If such a boundary exists in the bent portion, it is easy to break in long-term use. Therefore, it is a more preferable aspect that the resin reinforcing means extends over the entire bent portion, and the end portion (boundary portion) is provided so as to exist in the straight portion of the base material. In other words, it is preferable that the reinforcing length of the reinforcing portion by the resin reinforcing means is longer than the length of the bent portion. Further, when the bent portion is formed in a shape that is in contact with a substantially uniform circle, the surface length of the bent portion C on the front side of the filtration is almost twice the bending radius, so the reinforcement length is 2 times the bending radius. It is preferable to be longer than twice.

  It is more preferable that the bend radius is within the above range after the above-described resin impregnation and the like. It can be manufactured by fixing the bent portion so that the bending radius is in a desired range after the resin reinforcement or in the reinforcement step.

(Production method)
Hereinafter, the manufacturing method will be described. A typical example will be described with reference to FIGS. 8A and 8B in which a heat-sealing resin is impregnated as a resin reinforcing means and the shape is kept within a desired bending radius. FIG. 8A shows a state in which a reinforcing sheet-like resin 2 is attached to one side surface of a portion of the base material 1 where a bent portion is formed. In this example, the case where the front surface of the filtration, which is the inside of the valley, is impregnated will be described. However, the reinforcing resin sheet may be attached to the surface to be impregnated with the resin. In FIG. 8, the base material 1 is shown as a notation for making it easy to understand that it is a porous body. In this example, as an example of a preferable production method, the base material 1 is a porous resin sheet, and the reinforcing resin 2 is a thermoplastic resin having a melting point lower than that of the base material 1. For example, a polyester nonwoven fabric mainly composed of polyethylene terephthalate having a melting point of around 260 ° C. is used as the porous resin sheet, and as a thermoplastic resin to be impregnated, polymethylpentene, 66 nylon, polycarbonate having a melting point of around 230 ° C., Polyethylene having a melting point of generally 120 ° C., polypropylene having a melting point of about 160 ° C., and the like can be preferably used. Heating is performed while applying pressure in the direction of the arrow in FIG. 8A by a heating / pressurizing device (not shown) such as a heat sealer, so that the reinforcing resin 2 is melted inside the porous body of the substrate 1. Impregnated.

  A process of bending to a desired curvature after the impregnation or in parallel with the impregnation will be described. FIG. 8B shows an example of bending in parallel with the impregnation. In the heating of FIG. 8A, a metal jig 4 having a desired radius is in contact with the resin 2. is there. By bending while impregnating in such a state, as shown in FIG. 8C, the substrate 1 is bent to a desired curvature while being impregnated with the resin 2. As a method other than this example, the impregnation is performed with only the base material and the resin as shown in FIG. 8A, and then bent while the metal jig 4 is brought into contact as a cooling member as shown in FIG. 8C. The bent portion may be formed by cooling. The member to be contacted is not limited to metal, but considering the cooling effect, it is a member that does not deform at heating temperature and has relatively good thermal conductivity, such as a metal rod, pipe, ceramics, or glass. And good.

  The above describes the case where the base material is impregnated with the reinforcing resin, but the resin reinforcing means other than the impregnation is formed by a method of bonding the resin sheet with an adhesive or a method of bonding by heat fusion. Is possible. In addition, even when impregnated, a predetermined part of the base material is impregnated with a resin other than the thermoplastic resin in advance, and then the part may be bent, or when bent, it is flexible with heating. Then, it may be deformed to a desired curvature.

(Filtering device)
As a preferred application example of the filtration apparatus using the pleated filter described above, the configuration of a ballast water treatment apparatus will be described with reference to the drawings. 9 and 10 are views showing an example of a ballast water treatment apparatus for a ship according to the present invention. FIG. 9 shows a configuration of a vertical section including an axis, and FIG. 10 shows a configuration of a horizontal AA section in FIG. It is a figure shown typically. The cylindrical pleated filter 101 is disposed so as to surround an axis serving as a rotation center, and is rotatably attached around a central pipe (pipe does not rotate) disposed at the center. The upper and lower surfaces of the pleated filter are closed watertight. The rotatable mounting structure also needs to be a watertight structure, but a known structure is used without any particular limitation. A case 103 is provided so as to cover the entire filter. The case 103 includes an outer cylinder part 131, a lid part 132, and a bottom part 133, and the bottom part 133 is provided with a discharge channel 108. A treated water channel 106 and a treated water nozzle 102 are provided for introducing seawater as treated water into the case 103. The treated water nozzle 102 is extended from the treated water flow path 106 so that the nozzle port 121 is provided in the outer cylinder part 131 of the case 103 so that the treated water flows out toward the outer peripheral surface of the pleated filter. It is configured. A motor 190 is provided on the central axis of the pleat filter for rotating the pleat filter. The motor 190 is covered and accommodated by a motor cover 191 and is driven by electric power from a drive control unit (not shown).

  In the case of this example, the water to be treated ejected from the water nozzle to be treated hits the pleated outer peripheral surface of the pleated filter, and the cleaning effect of the pleated filter is obtained by the pressure. The untreated water to be treated and the suspended matter settled in the case are sequentially discharged from the discharge channel at the bottom of the case. The characteristic of this apparatus is that the filtration proceeds while the turbid component and the remaining water to be treated are continuously discharged, and 10 to 20 tons / hour or even 100 tons / hour required for ballast water. It is effective to secure the processing amount. In the figure, a valve or the like is not shown in the discharge flow path, but equipment necessary for maintenance and flow rate adjustment can be provided. On the other hand, the filtered water filtered by the pleated filter 101 is guided to the filtered water flow path 107 through the water intake hole 141 provided in the central pipe 104 inside the filter, and flows out of the case.

  As an example of an apparatus that performs processing at 100 tons / hour, an outer diameter of a pleat filter is 700 mm, an axial length is 320 mm, an effective area is height 280 mm, a pleat depth is 70 mm, and a pleat number is 420 folds. The treated water nozzle 102 may have a rectangular nozzle opening 121. A large amount of water is ejected from the water nozzle to be treated onto the surface of the pleated filter, causing stress concentration in the valley part of the pleated filter, and vibration in the direction of opening and closing of the crease in the valley part. It becomes easy to open holes such as tears. By using the pleated filter in which the crease of the present invention is reinforced, the breakage can be effectively suppressed, and the apparatus can be stably operated for a long time.

(Experimental example)
In order to confirm the effect of the resin reinforcing means, the strength of the portion subjected to resin impregnation and bending was compared. The materials used are as follows.
Porous filter: Non-woven fabric made of polyethylene terephthalate (trade name: Axter G2260-1S BK0 manufactured by Toray)
Impregnating resin: Nonwoven fabric made of polypropylene (trade name: Stratec RW2100, manufactured by Idemitsu Unitech)
Heat sealing machine: Ishizaki Electric Desk Sealer NL-301J
The impregnated resin is placed on the bent part of the porous filter that is the base material, heat sealing is performed with the setting 4 of the heat timer of the heat sealing machine (heating time is about 1 second), and the STRATEC is completely melted by heat to actuate After the sample was cooled in the state of impregnation, the sample was further heated under the same heating conditions, immediately followed by sandwiching a stainless steel rod with a diameter of 3 mm and bending the bent portion along the shape of the stainless steel rod to a bending radius of 1.5 mm. As an example. A comparative example was prepared by bending the same porous filter as it was and bending it until it did not return.

  The bent portion was opened and punched into a dumbbell mold so that the bent portion was perpendicular to the tensile direction near the center of the dumbbell, and the breaking strength was measured at a chuck interval of 3 cm and a tensile speed of 100 mm / min. As a result, all the comparative examples were broken at the bent portion and the breaking strength was 33 MPa. Moreover, since the measurement result in the base material itself without bending was 40 MPa, it was suggested that the strength was lowered by bending. On the other hand, in the example, the bent portion impregnated with the resin was not broken but all was broken at the other flat portion, and the breaking strength was 41 MPa. That is, it was confirmed that the bent portion had a strength of 41 MPa or more.

  Since the pleated filter of the present invention does not cause performance degradation due to clogging and is excellent in durability, brackish water and seawater use such as seawater desalination and ballast water, or water treatment such as sewage, domestic wastewater, industrial wastewater, Can be suitably used for pre-filtration treatment for removing foreign substances, dust, and microorganisms. In addition, because it is excellent in water treatment and concentration treatment with high turbidity and high SS, it can be applied in the field of valuable resources recovery such as the food field.

DESCRIPTION OF SYMBOLS 1 Base material 2 Resin 3 Resin sheet 4 Metal jigs 10 and 101 Pleated filter 102 Water nozzle 103 Case 104 Center pipe 106 Water flow path 107 Water flow path 108 Flow path 108 Discharge flow path 121 Nozzle port 131 Outer cylinder part 132 Cover part 133 Bottom 141 Water intake 190 Motor 191 Motor cover

Claims (10)

A pleated filter that is formed by periodically bending a planar substrate, and a crest and a trough are repeated continuously,
A pleated filter in which breakage prevention means is taken in the valley part which is a bent part.   2. The pleated filter according to claim 1, wherein the breakage prevention means is a resin reinforcement means using a resin provided at a bent portion of the valley as a reinforcing body.   The pleated filter according to claim 2, wherein the resin reinforcing means is formed by impregnating the base material with a resin.   The pleated filter according to claim 2, wherein the resin reinforcing means is formed by attaching a resin member to a surface of the base material. The breakage prevention means is a bending radius R of the bent portion of the valley,
The bending radius R and the thickness t (mm) of the substrate are
2t ≦ R ≦ 10t
The pleated filter according to claim 1, wherein: The breakage prevention means is a resin reinforcing means provided in a bent part of the valley part,
The pleated filter according to claim 1, wherein a bending radius R of the bent portion of the valley portion and a thickness t (mm) of the base material are in a relationship of 2t ≦ R ≦ 10t.   The whole of the ridge line direction of the peak part is cylindrical, and the breakage prevention means is provided at least in the valley part viewed from the outside of the cylindrical part. The pleated filter described. The pleated filter according to claim 7 is arranged in a cylinder so as to surround the axis,
To-be-treated water nozzle that flows out the to-be-treated water toward the outer peripheral surface of the pleat filter,
A case having an outer tube portion provided inside the pleated filter and provided with a nozzle port of the water nozzle to be treated inside;
A filtrate flow path for leading the filtrate water that has passed through the pleat filter from the inside of the cylinder of the pleat filter to the outside of the case;
A ballast water treatment apparatus comprising: a discharge flow path for discharging discharged water that has not been filtered by the pleated filter to the outside of the case. A method of manufacturing a pleated filter in which crests and troughs are repeatedly formed continuously by periodically bending a planar substrate,
Attaching a resin sheet to at least one surface of the base material to be the bent portion;
An impregnation step of impregnating at least a part of the resin sheet into the base material by heating the base material and the resin sheet in a portion to which the resin sheet is attached;
And a cooling step of cooling and fixing the bent portion in a folded state.   The method for manufacturing a pleated filter according to claim 9, wherein the cooling step is a step of cooling the metal jig having a constant radius in contact with the bent portion.

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