Patent Application
20250222378
The present disclosure relates to a filtering apparatus, a filtering method, and a water treatment system. The present application claims priority to Japanese Patent Application No. 2022-043274 filed with the Japan Patent Office on Mar. 18, 2022, the entire contents of which are hereby incorporated by reference.
For example, Japanese Patent Laying-Open No. 2015-9170 (PTL 1) discloses a cylindrical filter and a ballast water treatment apparatus including the same. For example, a porous structure such as a nonwoven fabric is employed as a material for the cylindrical filter.
PTL 1: Japanese Patent Laying-Open No. 2015-9170
A filtering apparatus according to one aspect of the present disclosure includes a cylindrical filter including a cylindrical screen filter made of a woven fabric or a nonwoven fabric, a treated water nozzle including a nozzle port through which water to be treated flows out to a surface of the screen filter, a casing where the cylindrical filter is accommodated, the casing containing the nozzle port in the inside, a filtered water flow channel through which filtered water obtained by passage of water to be treated through the screen filter is guided to the outside of the casing, the filtered water flow channel being provided with a flow inlet provided in the inside of the casing, and a rotation mechanism that rotates the cylindrical filter with a central axis of the cylindrical filter being defined as a center. A distance between a centerline of the nozzle port along a direction of outflow of water to be treated and the central axis of the cylindrical filter is shorter than a radius of the cylindrical filter.
A water treatment system according to one aspect of the present disclosure is a water treatment system including the filtering apparatus described above.
A filtering method according to one aspect of the present disclosure is a filtering method of filtering water to be treated by a cylindrical filter including a cylindrical screen filter made of a woven fabric or a nonwoven fabric. The filtering method includes rotating the cylindrical filter and causing water to be treated to flow out of a nozzle port of a treated water nozzle such that water to be treated passes through the screen filter. The causing water to be treated to flow out includes causing water to be treated to flow out in such a direction that a distance between a centerline of the nozzle port along a direction of outflow of water to be treated and a central axis of the cylindrical filter is shorter than a radius of the cylindrical filter.
Depending on water quality, a filter made of a nonwoven fabric is clogged in a short period of time by objects floating in water. Factors for clogging include surface deposition and internal obstruction. Surface deposition refers to such a phenomenon that particles larger than an average pore diameter of a filter are deposited on a surface of the filter and a layer of a lump called a cake is formed. Internal obstruction refers to such a phenomenon that particles smaller than an average pore diameter of a filter remain in the inside of the filter to clog a flow channel.
A cake layer can be removed by cleaning of the surface of the filter with a water flow. There are, however, small projections and recesses in the surface of the filter. Therefore, in cleaning of the surface of the filter, a solid may remain in those small recesses. Therefore, an effect of cleaning of the surface of the filter with a water flow should further be enhanced in order to maintain filtering performance of a filtering apparatus.
An object of the present disclosure is to provide a filtering apparatus capable of continuing filtering treatment while clogging of a filter is suppressed, a filtering method with the use of the filtering apparatus, and a water treatment system including the filtering apparatus.
According to the present disclosure, a filtering apparatus capable of continuing filtering treatment while clogging of a filter is suppressed, a filtering method with the use of the filtering apparatus, and a water treatment system including the filtering apparatus can be provided.
Manners in which the present disclosure is carried out will initially be listed and described.
According to the above, the filtering apparatus capable of continuing filtering treatment while clogging of the filter is suppressed can be realized. The cylindrical filter is formed from a screen filter made of a woven fabric or a nonwoven fabric having a thickness, for example, not larger than 200 μm. Since the screen filter has a small thickness, internal obstruction is less likely. Therefore, a main factor for clogging of the screen filter is surface deposition. The nozzle port is directed to the surface of the screen filter such that the distance between the centerline of the nozzle port along the direction of outflow of water to be treated and the central axis of the cylindrical filter is smaller than the radius of the cylindrical filter. A solid (cake layer) deposited on the screen filter can be removed by a water pressure of water to be treated that flows out of the nozzle port. Furthermore, small recesses located in the vicinity of the surface of the screen filter can also be cleaned by a jet of water to be treated. Therefore, filtering treatment can continue while clogging of the filter is suppressed. The “woven fabric” refers to a fabric, for example, formed by weaving resin fibers or metallic wires, and a material therefor is not particularly limited.
According to the above, water to be treated is incident obliquely to the tangent of the cylindrical filter. Since the pressure of water to be treated applied to the surface of the screen filter can be increased, not only the solid deposited on the screen filter can be removed but also small recesses located in the vicinity of the surface of the screen filter can be cleaned.
According to the above, an effect of cleaning of the surface of the screen filter with water to be treated can be enhanced.
According to the above, the screen filter is supported by the filter support. The filter support is fixed by the strut, the first fixing member, and the second fixing member. Furthermore, the gap between the screen filter and the filter support can be sealed with the first sealing member and the second sealing member. The screen filter is thus cylindrically supported. In addition, since the recess in the first fixing member is provided to receive the protruding portion of the coupling portion of the rotation mechanism, the first fixing member and the rotation mechanism can be coupled to each other. Water to be treated can thus be filtered by the screen filter while the cylindrical filter is rotated. Since filtered treated water passes through the holes provided in the filter support, treated water can be taken out of the filtered water flow channel.
According to the above, the filtering apparatus useful for the water treatment system that requires filtering of water to be treated as pre-treatment can be realized. Applications of the water treatment system are not particularly limited.
According to the above, the filtering apparatus capable of continuing filtering treatment while clogging of the filter is suppressed can be realized.
An embodiment of the present disclosure will be described in detail below with reference to the drawings. The same or corresponding elements in the drawings have the same reference characters allotted and description thereof will not be repeated.
As shown in
Cylindrical filter 1 is a filter obtained by forming a screen filter in a cylindrical shape. In this embodiment, a woven fabric or a nonwoven fabric having a thickness, for example, not larger than 200 μm is employed as the screen filter. A type of yarns to be used for the woven fabric is not particularly limited, and metallic (for example, SUS) wires or resin fibers may be applicable.
The nonwoven fabric is a sheet obtained by intertwining fibers, rather than weaving fibers. The nonwoven fabric is defined, for example, under JIS L0222. A type of resin fibers to be used for the nonwoven fabric is not particularly limited.
As water to be treated 5 passes through cylindrical filter 1, a separation target 3 is removed from water to be treated 5 and filtered water is obtained. Separation target 3, on the other hand, adheres to a surface of cylindrical filter 1. In the embodiment of the present disclosure, while cylindrical filter 1 rotates around a central axis 2 of the cylinder, water to be treated 5 flows toward the surface of cylindrical filter 1 (cylinder). In addition to rotation of cylindrical filter 1, a flow of water to be treated 5 toward the surface of cylindrical filter 1 (cylinder) can remove separation target 3 from the surface of cylindrical filter 1. Therefore, formation of the cake layer at the surface of cylindrical filter 1 can be prevented. As shown in
In
A radius of curvature of cylindrical filter 1 (screen filter) is denoted as R. Radius of curvature R is equal to a distance from central axis 2 of cylindrical filter 1 to tangent 4. In other words, R represents a length of a normal from central axis 2 of the cylinder to tangent 4. This normal intersects with tangent 4 at point A. Furthermore, a distance between centerline 12A of nozzle port 12 and central axis 2 of cylindrical filter 1 is denoted as D.
In the embodiment of the present disclosure, distance D is shorter than radius of curvature R of cylindrical filter 1. In other words, relation of D<R is satisfied. As nozzle port 12 is directed toward the surface of cylindrical filter 1 so as to satisfy relation of D<R, a water pressure of water to be treated 5 that flows out of nozzle port 12 can remove a solid (cake layer) deposited on the screen filter. Furthermore, small recesses located in the vicinity of the surface of the screen filter can also be cleaned with a jet of water to be treated 5. Therefore, filtering treatment can continue while clogging of the filter is suppressed.
A condition of D<R described above can also be explained with reference to an angle θ between centerline 12A of nozzle port 12 and tangent 4. Angle θ is equal to an angle between the normal from central axis 2 of cylindrical filter 1 to tangent 4 (a line segment that connects central axis 2 and point A to each other) and a line segment that connects central axis 2 of cylindrical filter 1 and centerline 12A of nozzle port 12 to each other.
In the embodiment of the present disclosure, angle θ is larger than 0°. Preferably, angle θ is equal to or larger than 1° and equal to or smaller than 45°. With angle θ being equal to or larger than 1°, in addition to the effect of removal of a solid (cake layer) by a jet of water to be treated 5, the effect of cleaning of small recesses located in the vicinity of the surface of the screen filter can also be obtained. With a larger angle θ, on the other hand, a jet of water to be treated 5 may interfere with rotation of cylindrical filter 1. With angle θ being equal to or smaller than 45°, while interference with rotation of cylindrical filter 1 by a jet of water to be treated 5 is avoided, water to be treated 5 can be filtered and the surface of the screen filter can be cleaned. The effect of cleaning of the surface of the screen filter when angle θ is varied will be described in detail later.
Casing 10 contains therein, nozzle port 12 of treated water nozzle 11, a drain outlet 14 of drain flow channel 13, and filtered water flow channels 15A and 15B, and cylindrical filter 1 and motor 16 are accommodated in casing 10. Casing 10 may be formed as being integrated with treated water nozzle 11, drain flow channel 13, and filtered water flow channels 15A and 15B.
Cylindrical filter 1 is a filter in a cylindrical shape which includes a woven fabric or a nonwoven fabric having a thickness, for example, not larger than 200 μm as the screen filter. Treated water nozzle 11 includes nozzle port 12 through which water to be treated flows out to the surface of the cylindrical filter. A height of nozzle port 12 is not particularly limited. In one embodiment, the height of nozzle port 12 may be lower than a height of cylindrical filter 1.
Filtered water flow channels 15A and 15B are flow channels for guiding treated water (filtered water) filtered by cylindrical filter 1 from the inside of casing 10 to the outside of casing 10. Filtered water flow channel 15A passes through the inside of cylindrical filter 1. Therefore, a through hole for passage of filtered water flow channel 15A is provided at a lower end of cylindrical filter 1. Filtered water flow channels 15A and 15B communicate with each other. Filtered water that passes through cylindrical filter 1 is taken into a flow inlet of filtered water flow channel 15A and flows through filtered water flow channel 15A, and is taken out of filtered water flow channel 15B.
Drain flow channel 13 is a flow channel for draining drain water containing a separation target removed by cylindrical filter 1 to the outside of casing 10. Though not shown, a valve may be provided in drain flow channel 13. An amount of treatment by the filtering apparatus can be controlled by control of opening and closing of the valve.
For example, while cylindrical filter 1 filters water to be treated, the valve may be closed. Filtering apparatus 101 can filter water to be treated while it cleans cylindrical filter 1. Since a total amount of water to be treated 5 supplied to filtering apparatus 101 can thus be filtered through filtering apparatus 101, filtered water production capability can be enhanced. After filtering of water to be treated by cylindrical filter 1 ends, the valve is opened. A separation target accumulated in the inside of casing 10 during filtering treatment can thus be ejected through drain flow channel 13 to the outside of filtering apparatus 101. During filtering of water to be treated, the valve may be open. In this case, water to be treated can be filtered while some of water to be treated that flows in is drained.
Motor 16 rotates cylindrical filter 1 around central axis 2 of the cylinder. In order to obtain desired torque for rotation of cylindrical filter 1, a reduction gear may be combined with motor 16. Motor cover 17 is attached to casing 10 to cover motor 16 (and the reduction gear).
A rotation shaft of motor 16 (a rotation shaft of the reduction gear in an example where motor 16 is coupled to the reduction gear) is coupled to coupling portion 18. At an upper end of cylindrical filter 1, cylindrical filter 1 is coupled to motor 16 (or the reduction gear) with coupling portion 18 being interposed. Thus, as motor 16 rotates, cylindrical filter 1 rotates. Motor 16 (or combination of motor 16 and the reduction gear) and coupling portion 18 correspond to the rotation mechanism for rotation of cylindrical filter 1. On a lower end side of cylindrical filter 1, on the other hand, bearing portion 19 for support of rotating cylindrical filter 1 is provided.
The graph in
As the effect of cleaning of the surface of the filter is greater, progress of clogging of the filter is suppressed and hence the degree of increase in pressure loss is lower. Based on comparison of the degree of increase in pressure loss during the duration of filtering treatment from zero minute to ninety minutes, pressure loss when the angle between the centerline of nozzle port 12 and the tangent is between zero degree and forty-five degrees is smaller than pressure loss when the angle is ninety degrees, and can be suppressed to substantially ½ or lower.
Furthermore, when the angle between the centerline of nozzle port 12 and the tangent of the filter is five degrees, the degree of increase in pressure loss is lower than when the angle is zero degree, fifteen degrees, thirty degrees, and forty-five degrees. This may be because the recesses in the surface of the filter were more effectively cleaned. It was confirmed that, with the longer duration of filtering, the degree of increase in pressure loss when the angle was fifteen degrees was lower than the degree of increase in pressure loss when the angle was thirty degrees and forty-five degrees. This may be because, as the angle is larger, the cake layer at the surface of the filter was removed by water to be treated, however, the effect of cleaning of the recesses in the surface of the filter became weaker. Therefore, the angle between the centerline of nozzle port 12 and the tangent is preferably between more than zero degree (for example, one degree) and forty-five degrees and further preferably between five degrees and fifteen degrees.
In the embodiment of the present disclosure, cylindrical filter 1 can be a cartridge type filter. A replaceable filter can thus be realized.
Filter main body 21 includes a screen filter 21A and a cylindrical filter support 21B.
Strut 26 is arranged in the inside of filter support 21B to extend along a direction of central axis 2 of cylindrical filter 1.
Lid body 22A is arranged at a first end (upper end) of filter support 21B to close an opening at the first end. Lid body 22B is arranged at a second end (lower end) of filter support 21B opposite to the first end to close an opening at that end. Strut 26 located on an upper end side of filter support 21B has an end fixed to lid body 22A by screw 27. Similarly, strut 26 located on a lower end side of filter support 21B also has an end fixed to lid body 22B by screw 27. Strut 26 is thus fixed to lid bodies 22A and 22B and filter support 21B is supported by strut 26 and lid bodies 22A and 22B.
Sealing tapes 23A and 23B are wound around the upper end and the lower end of cylindrical screen filter 21A, respectively. Sealing tapes 23A and 23B fix screen filter 21A to filter support 21B and bury a gap between screen filter 21A and filter support 21B.
Sealing member 24A is provided at the upper end of filter support 21B so as to surround sealing tape 23A and lid body 22A. Sealing member 24B is provided at the lower end of filter support 21B so as to surround sealing tape 23B and lid body 22B. Sealing members 24A and 24B seal the gap between screen filter 21A and filter support 21B, together with sealing tapes 23A and 23B. Therefore, in this embodiment, sealing member 24A and sealing tape 23A correspond to the first sealing member that seals the gap between lid body 22A and screen filter 21A on the upper end side of filter support 21B. Similarly, sealing member 24B and sealing tape 23B correspond to the second sealing member that seals the gap between lid body 22B and screen filter 21A on the lower end side of filter support 21B.
A through hole is provided in lid body 22B for passage of filtered water flow channel 15A in the inside of filter support 21B. Bearing ring 25 is inserted in the through hole in lid body 22B. Lid body 22A covers the upper end of filtered water flow channel 15A.
Screen filter 21A is wound such that the surface of filter support 21B is in contact with an inner circumferential surface of screen filter 21A. Therefore, the cylindrical screen filter is formed.
Hole 36 is provided in a central portion of lower surface 32 of lid body 22A. Two recesses 34 are arranged in symmetry with respect to hole 36. Similarly, four holes 35 and four screw holes 33 are arranged in symmetry with respect to hole 36.
Lid body 22A is inserted in the opening at the end (upper end) of filter support 21B to close the end (upper end) of that filter support 21B. A groove 37 is provided in a portion of lid body 22A inserted in the end (upper end) of filter support 21B. In order to enhance hermeticity at the upper end of filter support 21B, O ring 28A may be fitted in groove 37 (see
Lid body 22B is inserted in the opening at the end (lower end) of filter support 21B to close the end (lower end) of that filter support 21B. A groove 47 is provided in a portion of lid body 22B inserted in the end (lower end) of filter support 21B. In order to enhance hermeticity at the upper end of filter support 21B, O ring 28B may be fitted in groove 47 (see
A through hole 46 extending from top surface 41 to lower surface 42 is provided in the central portion of lid body 22B. Through hole 46 is a hole for passage of filtered water flow channel 15A (see
As described above, according to the embodiment of the present disclosure, the filtering apparatus useful for a water treatment system that requires filtering of water to be treated as pre-treatment can be realized. By way of example, the filtering apparatus according to the embodiment of the present disclosure can be applied to a water treatment system. Though a type of the water treatment system including the filtering apparatus according to the embodiment of the present disclosure is not particularly limited, one specific example will be described below.
In saline water conversion system 201, filtering apparatus 101 according to the embodiment of the present disclosure is used as a pre-filter and filters water to be treated 5 which is sea water. Filtered water 6 is further filtered by filtering apparatus 102. Filtered water 7 from filtering apparatus 102 is supplied to reverse osmosis membrane permeation apparatus 103. As filtered water 7 passes through filter 113 of reverse osmosis membrane permeation apparatus 103, pure water 8 is produced. Pure water 8 is stored in a tank 104.
It should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present disclosure is defined by the terms of the claims rather than the embodiment above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
1 cylindrical filter; 2 central axis; 3 separation target; 4 tangent; 5 water to be treated; 6, 7 filtered water; 8 pure water; 10 casing; 11 treated water nozzle; 12 nozzle port; 12A centerline; 13 drain flow channel; 14 drain outlet; 15A, 15B filtered water flow channel; 16 motor; 17 motor cover; 18 coupling portion; 18A protrusion; 19 bearing portion; 21 filter main body; 21A screen filter; 21B filter support; 21C, 35, 36, 45 hole; 22A, 22B lid body; 23A, 23B sealing tape; 24A, 24B sealing member; 25 bearing ring; 26 strut; 27 screw; 28A, 28B ring; 31, 41 top surface; 32, 42 lower surface; 33, 43 screw hole; 34 recess; 37 groove; 46 through hole; 101, 102 filtering apparatus; 103 reverse osmosis membrane permeation apparatus; 104 tank; 112, 113 filter; 201 saline water conversion system; A point; D distance; R radius of curvature.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-043274 | Mar 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/010368 | 3/16/2023 | WO |
