Water purification membrane structure and water purification membrane assembly

Abstract

To provide an effective removal of deposits accumulated on an inner surface of a filter cell during backwashing.SOLUTION: In a water purification membrane structure 10 that generates purified water from raw water, a central communication flow path section 17 extends from an outer side surface 13 connecting a first end face 11 and a second end face 12, in a direction perpendicular to a longitudinal direction, while avoiding a plurality of filtration cells. The central communication flow path section 17 communicates with water collection holes. The central communication flow path section 17 is positioned at a location spaced apart longitudinally from the first end face 11 by at least one-third of the total length of a porous body 1 and also spaced apart longitudinally from the second end face 12 by at least one-third of the total length of the porous body 1. A cross-section perpendicular to a flow path longitudinal direction of a communication flow path forming the central communication channel section 17 is slit-shaped with a long longitudinal dimension. This allows deposits accumulated on an inner surface of the filtration cell to be effectively removed during backwashing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a water purification membrane structure and a water purification membrane assembly for producing purified water from raw water. [Background technology]

[0002] BACKGROUND ART Conventionally, in water purification plants and the like, filtration devices are used to produce purified water by filtering raw water such as river water and well water.

[0003] For example, Patent Document 1 proposes a water purification membrane structure for use in a filtration device, which has a monolith structure in which multiple cells are provided in a cylindrical porous body. The porous body is provided with multiple filtration cells that penetrate the porous body in the longitudinal direction, multiple water collection cells that extend in the longitudinal direction, a water collection hole that extends in the longitudinal direction at the radial center of the porous body, and a water collection slit that extends from the outer surface of the porous body through the multiple water collection cells and communicates with the water collection hole. The water collection slits are located at both ends of the porous body in the longitudinal direction. Furthermore, the outer surface of the porous body is entirely covered with side seals formed by applying a water-impermeable material such as glass.

[0004] In the water purification membrane structure, raw water supplied to the plurality of filtration cells is filtered by passing through the porous partition walls that form the plurality of filtration cells, and is collected as purified water in the plurality of water collection cells. The purified water collected in the plurality of water collection cells is collected in the water collection holes through the water collection slits and is then discharged to the outside of the water purification membrane structure.

[0005] In the water purification membrane structure, suspended solids in the raw water adhere to the inner surfaces of the filtration cells during filtration and accumulate over time. After a predetermined period of use, backwash water (e.g., purified water) is supplied through the water collection holes into the interior of the water purification membrane structure for backwashing. During backwashing, the backwash water pumped into the water collection holes spreads through the water collection slits at both longitudinal ends and the multiple water collection cells into the porous body and flows into each filtration cell through the partition walls that form each cell. This causes the deposits accumulated on the inner surfaces of the filtration cells to peel off and be discharged from the filtration cells together with the backwash water. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-56381 Summary of the Invention [Problem to be solved by the invention]

[0007] In the water purification membrane structure of Patent Document 1, due to factors such as unevenness in the flow rate of backwash water flowing into multiple filtration cells, removal of deposits during backwashing may be insufficient, resulting in clogging of the filtration cells. Furthermore, if the flow rate of backwash water supplied to the water collection holes is increased, the side seals covering the openings of the water collection slits provided on the outer surface of the porous body may be damaged by the pressure of the backwash water.

[0008] The present invention has been made in view of the above problems, and one object of the present invention is to effectively remove deposits accumulated on the inner surface of a filtration cell during backwashing. [Means for solving the problem]

[0009] A first aspect of the invention is a water purification membrane structure for producing purified water from raw water, comprising: a columnar porous body extending in a longitudinal direction; a water-impermeable first seal covering a first end face, which is one end face of the porous body in the longitudinal direction; and a water-impermeable second seal covering a second end face, which is the other end face of the porous body in the longitudinal direction. The porous body comprises a plurality of filtration cells that penetrate the porous body in the longitudinal direction from the first end face to the second end face and open at the first seal and the second seal, and through which raw water is supplied; a water collection hole that opens at the first seal, extends from the first end face in the longitudinal direction from the first end face and closes at the second seal, and through which purified water is collected; and a central communication channel that extends from an outer surface connecting the first end face to the second end face in a direction perpendicular to the longitudinal direction, avoiding the plurality of filtration cells, and communicates with the water collection hole. The water collection hole is located in the center of the first end face when viewed parallel to the longitudinal direction. The central communicating channel portion is located at a position spaced apart from the first end face by at least one-third of the total length of the porous body in the longitudinal direction and at a position spaced apart from the second end face by at least one-third of the total length of the porous body in the longitudinal direction. A cross section perpendicular to the longitudinal direction of the communicating channel constituting the central communicating channel portion is shaped like a slit that is long in the longitudinal direction.

[0010] A second aspect of the invention is the water purification membrane structure of the first aspect, wherein the porous body further includes a plurality of water collection cells extending in the longitudinal direction, closed at the first seal and the second seal, and in which purified water is collected. The central communication channel portion communicates with the plurality of water collection cells.

[0011] The invention of aspect 3 is a water purification membrane structure of aspect 1 or 2, wherein the other end of the porous body in the longitudinal direction does not have a communicating flow path portion extending from the outer surface in a direction perpendicular to the longitudinal direction and communicating with the water collection hole.

[0012] The invention of aspect 4 is a water purification membrane structure of aspect 1 or 2 (or any one of aspects 1 to 3), wherein the longitudinal length of the central connecting flow path portion is 3% or more of the total length of the porous body in the longitudinal direction.

[0013] A fifth aspect of the invention is the water purification membrane structure of the first or second aspect (or any one of the first to fourth aspects), wherein the central communicating channel portion comprises: a first vertical channel extending linearly from the outer surface in a vertical direction perpendicular to the longitudinal direction and directly communicating with the water collection holes; a horizontal channel extending linearly from the outer surface along a horizontal direction perpendicular to the longitudinal direction and directly communicating with the water collection holes; and a second vertical channel spaced apart from the water collection holes in the horizontal direction and extending linearly from the outer surface in the vertical direction and directly communicating with the horizontal channel. When viewed parallel to the longitudinal direction, the channel width of the horizontal channel in the direction perpendicular to the horizontal channel is greater than the channel width of the second vertical channel in the horizontal direction.

[0014] A sixth aspect of the invention is a water purification membrane assembly for producing purified water from raw water, comprising: the water purification membrane structure of the first or second aspect (or any one of the first to fifth aspects); and a housing body that houses the water purification membrane structure and is placed in raw water so that the one side and the other side in the longitudinal direction of the water purification membrane structure are the upper and lower sides, respectively. The housing body is cylindrical and covers the outer surface of the water purification membrane structure. Raw water flows into the housing body through upper and lower openings of the housing body and is supplied to the multiple filtration cells of the water purification membrane structure.

[0015] A seventh aspect of the invention is a water purification membrane structure for producing purified water from raw water, comprising: a columnar porous body extending in the longitudinal direction; a water-impermeable first seal covering a first end face, which is one end face of the porous body in the longitudinal direction; and a water-impermeable second seal covering a second end face, which is the other end face of the porous body in the longitudinal direction. The porous body comprises a plurality of filtration cells that penetrate the porous body in the longitudinal direction from the first end face to the second end face and open at the first seal and the second seal, and through which raw water is supplied; a water collection hole that opens at the first seal, extends from the first end face in the longitudinal direction from the first end face and closes at the second seal, and through which purified water is collected; and a communication flow path that extends from an outer surface connecting the first end face to the second end face in a direction perpendicular to the longitudinal direction, avoiding the plurality of filtration cells, and communicates with the water collection hole. The water collection hole is located in the center of the first end face when viewed parallel to the longitudinal direction. A cross section perpendicular to the longitudinal direction of the communicating flow passage constituting the communicating flow passage portion has a slit shape that is long in the longitudinal direction. The communicating flow passage portion includes a first vertical flow passage that extends linearly from the outer surface in a vertical direction perpendicular to the longitudinal direction and directly communicates with the water collection hole, a horizontal flow passage that extends linearly from the outer surface along a horizontal direction perpendicular to the longitudinal direction and directly communicates with the water collection hole, and a second vertical flow passage that is spaced from the water collection hole in the horizontal direction and extends linearly from the outer surface in the vertical direction and directly communicates with the horizontal flow passage. When viewed parallel to the longitudinal direction, the flow passage width of the horizontal flow passage in the direction perpendicular to the horizontal flow passage is larger than the flow passage width of the second vertical flow passage in the horizontal direction.

[0016] An eighth aspect of the invention is the water purification membrane structure of the seventh aspect, wherein the lateral flow passages extend parallel to the lateral direction.

[0017] A ninth aspect of the invention is the water purification membrane structure of the seventh or eighth aspect, wherein only one lateral flow path is provided on each side of the water collecting hole in the lateral direction.

[0018] The invention of aspect 10 is a water purification membrane structure of aspect 7 or 8 (or any one of aspects 7 to 9), wherein, when viewed parallel to the longitudinal direction, the flow path width of the horizontal flow path in a direction perpendicular to the horizontal flow path is at least twice the flow path width of the second vertical flow path in the horizontal direction.

[0019] An eleventh aspect of the invention is a water purification membrane assembly for producing purified water from raw water, comprising: a columnar water purification membrane structure extending in the longitudinal direction; and a housing main body that houses the water purification membrane structure so that one longitudinal side and the other longitudinal side of the water purification membrane structure are the upper and lower sides, respectively, and is placed in raw water. The water purification membrane structure comprises a columnar porous body extending in the longitudinal direction, a first water-impermeable seal covering a first end face that is the one longitudinal end face of the porous body, and a second water-impermeable seal covering a second longitudinal end face that is the other longitudinal end face of the porous body. The porous body includes a plurality of filtration cells that penetrate the porous body in the longitudinal direction from the first end face to the second end face, open at the first seal and the second seal, and receive raw water; a water collection hole that opens at the first seal, extends from the first end face in the longitudinal direction, and closes at the second seal, collecting purified water; and a communication flow path that extends from an outer surface connecting the first end face to the second end face in a direction perpendicular to the longitudinal direction, avoiding the plurality of filtration cells, and communicates with the water collection hole. The water collection hole is located in the center of the first end face when viewed parallel to the longitudinal direction. The cross section of the communication flow path that constitutes the communication flow path, taken perpendicular to the longitudinal direction of the flow path, is slit-shaped and long in the longitudinal direction. The housing body is cylindrical and covers the outer surface of the water purification membrane structure. Raw water flows into the housing body through upper and lower openings and is supplied to the plurality of filtration cells of the water purification membrane structure. [Effects of the Invention]

[0020] One of the effects of the present invention is that deposits accumulated on the inner surface of the filtration cell can be suitably removed during backwashing. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram showing a filtration device having a water purification membrane structure according to one embodiment. [Figure 2] FIG. 2 is a front view of the water purification membrane structure. [Figure 3] FIG. 2 is a plan view of the water purification membrane structure. [Figure 4] FIG. 2 is a bottom view of the water purification membrane structure. [Figure 5] FIG. 2 is a cross-sectional view of the water purification membrane structure. [Figure 6] FIG. 2 is a cross-sectional view of the water purification membrane structure. [Figure 7] FIG. 2 is a cross-sectional view of the water purification membrane structure. [Figure 8] FIG. 2 is a longitudinal cross-sectional view of the water purification membrane structure. [Figure 9] FIG. 2 is a longitudinal cross-sectional view of the water purification membrane structure. DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 is a diagram schematically illustrating an example of the configuration of a filtration device 5 having a water purification membrane structure 10 according to one embodiment of the present invention. The filtration device 5 is a device that filters raw water to remove suspended solids and the like from the raw water and produce purified water. In the example shown in FIG. 1, the filtration device 5 filters raw water 91 stored in a raw water reservoir 81 to produce purified water 92. The purified water 92 produced by the filtration device 5 is stored in the purified water reservoir 82.

[0023] The filtration device 5 includes a water purification membrane assembly 4, purified water piping 52, a valve 53, a first pump 54, and a second pump 55. The water purification membrane assembly 4 includes a water purification membrane structure 10, a housing body 41, and two sealing members 42. In FIG. 1, the housing body 41 and sealing members 42 are depicted in longitudinal cross section to facilitate understanding of the drawing. The structure of the water purification membrane assembly 4 will be described in detail below. The water purification membrane assembly 4 is installed in a state where it is substantially entirely immersed in raw water 91 stored in a raw water reservoir 81. In the example shown in FIG. 1, multiple water purification membrane assemblies 4 are installed in the raw water 91 in the raw water reservoir 81.

[0024] In the filtration device 5, raw water 91 in the raw water reservoir 81 is supplied to the water purification membrane assembly 4, and purified water 92 produced in the water purification membrane assembly 4 is sent to the purified water reservoir 82 via the purified water piping 52. In the example shown in Fig. 1, the first pump 54 provided on the purified water piping 52 is driven to suck in the purified water 92 produced in the water purification membrane assembly 4 and transfer it to the purified water reservoir 82. As a result, the raw water 91 around the water purification membrane assembly 4 is sucked into the water purification membrane assembly 4 and filtered, and purified water 92 is produced.

[0025] After the filtration device 5 has been producing purified water 92 for a predetermined time (e.g., 60 to 90 minutes), backwashing of the water purification membrane structure 10 of the water purification membrane assembly 4 is performed. In the example shown in FIG. 1 , the first pump 54 is stopped, the second pump 55 provided on the purified water piping 52 is driven, and the valve 53 is switched. As a result, the purified water 92 stored in the purified water reservoir 82 is sent to the water purification membrane assembly 4 via the purified water piping 52 and supplied to the water purification membrane structure 10 as backwash water. This removes attached matter such as suspended solids adhering to the inside of the water purification membrane structure 10.

[0026] The backwash water supplied to the water purification membrane structure 10 does not necessarily have to be the purified water 92 stored in the purified water reservoir 82, and may be variously modified. Furthermore, the configurations of the first pump 54, second pump 55, and other components connected to the water purification membrane assembly 4 in the filtration device 5 are not limited to those exemplified in Figure 1, and may be variously modified.

[0027] Next, the structures of the water purification membrane structure 10 and the water purification membrane assembly 4 will be described. FIG. 2 is an enlarged front view of the water purification membrane structure 10. FIG. 3 is a plan view of the water purification membrane structure 10 viewed from above. FIG. 4 is a bottom view of the water purification membrane structure 10 viewed from below. FIG. 5 is a cross-sectional view of the water purification membrane structure 10 taken along line VV in FIG. 2. FIG. 6 is a cross-sectional view of the water purification membrane structure 10 taken along line VI-VI in FIG. 2. FIG. 7 is a cross-sectional view of the water purification membrane structure 10 taken along line VII-VII in FIG. 2. FIG. 8 is a longitudinal cross-sectional view of the water purification membrane structure 10 taken along line VIII-VIII in FIG. 3. FIG. 9 is a longitudinal cross-sectional view of the water purification membrane structure 10 taken along line IX-IX in FIG. 3. The X, Y, and Z directions in FIGS. 2 to 9 are perpendicular to each other, and the Z direction is parallel to the vertical direction.

[0028] The water purification membrane structure 10 includes a porous body 1, a first seal 21, and a second seal 22. The porous body 1 is a porous member that is permeable to gas and liquid. The porous body 1 is a columnar member centered on a central axis J1 that extends linearly in the Z direction (i.e., the vertical direction) in FIG. 2. In the following explanation, the direction parallel to the central axis J1 (i.e., the vertical direction in FIG. 2) is also referred to as the "longitudinal direction." The porous body 1 has a monolithic structure in which a continuous columnar main body is provided with a plurality of through-holes that each extend in the longitudinal direction of the main body. The monolithic structure is a concept that includes a honeycomb structure.

[0029] 2 to 9, the porous body 1 has a generally cylindrical outer shape extending in the longitudinal direction about a central axis J1. However, the outer shape of the porous body 1 may be any shape other than a cylindrical shape (for example, an elliptical cylinder, a polygonal cylinder, a rectangular parallelepiped, a cube, etc.) as long as it is a cylindrical shape extending in the longitudinal direction.

[0030] The porous body 1 has a first end face 11, a second end face 12, and an outer surface 13. The first end face 11 is an end face located on one side in the longitudinal direction of the porous body 1 (i.e., the (+Z) side, which is the upper side in FIG. 2). The second end face 12 is an end face located on the other side in the longitudinal direction of the porous body 1 (i.e., the (-Z) side, which is the lower side in FIG. 2). Each of the first end face 11 and the second end face 12 has a substantially circular shape centered on the central axis J1 in a plan view (i.e., when viewed from the (+Z) side parallel to the central axis J1). The outer surface 13 is a side face connecting the outer peripheral edge of the first end face 11 and the outer peripheral edge of the second end face 12. In other words, the outer surface 13 is a side face that continues from the outer peripheral edge of the first end face 11 to the outer peripheral edge of the second end face 12. The outer surface 13 is a substantially cylindrical surface centered on the central axis J1.

[0031] The length of the porous body 1 in the longitudinal direction is, for example, 100 mm to 2000 mm. The outer diameter of the porous body 1 is, for example, 10 mm to 200 mm. In this embodiment, the length and outer diameter of the porous body 1 are 1500 mm and 180 mm, respectively. The length and outer diameter of the porous body 1 are not particularly limited and may be changed in various ways.

[0032] The first seal 21 is a water-impermeable thin film provided on the first end face 11 of the porous body 1. The first seal 21 covers substantially the entire first end face 11, excluding the end openings of the filtration cells 14 (described later) and the end openings of the water collection holes 16. The second seal 22 is a water-impermeable thin film provided on the second end face 12 of the porous body 1. The second seal 22 covers substantially the entire second end face 12, excluding the end openings of the filtration cells 14. The first seal 21 and the second seal 22 are made of a water-impermeable material such as glass, resin, metal, or rubber. The first seal 21 and the second seal 22 are preferably made of glass. This reduces the difference in thermal expansion coefficient between the first seal 21 and the second seal 22 and the porous body 1. Note that no seal is provided on the outer surface 13 of the porous body 1, which is exposed to the space surrounding the water purification membrane structure 10. The outer surface 13 is also the outer surface of the water purification membrane structure 10 .

[0033] The porous body 1 is provided therein with a plurality of filtration cells 14, a plurality of water collection cells 15, one water collection hole 16, a central communicating channel portion 17, and end channel portions 18. In Fig. 6, the filtration cells 14 are indicated with parallel diagonal lines to make it easier to distinguish between the filtration cells 14 and the water collection cells 15. The plurality of filtration cells 14 are each separated (i.e., partitioned) from the plurality of water collection cells 15, water collection holes 16, central communicating channel portion 17, and end channel portions 18 by partition walls that are part of the porous body 1.

[0034] The multiple filtration cells 14 are through-holes that penetrate the porous body 1 in the longitudinal direction from the first end face 11 to the second end face 12. Each filtration cell 14 extends substantially linearly and substantially parallel to the longitudinal direction. Both longitudinal ends of each filtration cell 14 are open at the first seal 21 and the second seal 22. In other words, each filtration cell 14 is open at both longitudinal end faces of the water purification membrane structure 10. Raw water is supplied to each filtration cell 14 from the opening on the first seal 21 side and the opening on the second seal 22 side.

[0035] The cross-sectional shape of each filtration cell 14 perpendicular to the longitudinal direction (hereinafter simply referred to as the "cross-sectional shape") is, for example, approximately circular. The cross-sectional shape of the filtration cell 14 may be modified in various ways, such as a polygon such as an approximately regular hexagon or an approximately rectangular shape, an ellipse, an oval shape, etc. In the examples shown in FIGS. 3 to 7, the cross-sectional shape of the filtration cell 14 is depicted as a circle. When the cross-sectional shape of the filtration cell 14 is polygonal, the inner diameter of the filtration cell 14 refers to the diameter of the circumscribed circle of the polygon. Note that the inner diameter of the filtration cell 14 is not particularly limited and may be modified in various ways. In the examples shown in FIGS. 3 to 7, the size of the filtration cell 14 is depicted larger than in reality, and the number of filtration cells 14 is depicted smaller than in reality. The number and arrangement of the multiple filtration cells 14 in the porous body 1 may be modified as appropriate.

[0036] A filtration layer is provided on the inner surface of each filtration cell 14 over substantially the entire surface of the inner surface. The filtration layer is a substantially cylindrical porous portion extending in the longitudinal direction. The average pore diameter of the filtration layer is smaller than the average pore diameter of the portion of the porous body 1 other than the filtration layer (i.e., the substrate, which is the main body of the porous body 1). The filtration layer may be composed of multiple layers with different average pore diameters, etc. For example, the filtration layer includes a first filtration layer formed directly on the surface of the substrate and a second filtration layer formed on the first filtration layer. The filtration cell 14 is the space inside the second filtration layer.

[0037] The substrate is a porous portion containing aggregate and binder. The aggregate may be alumina, silicon carbide, titania, mullite, cerium, cordierite, or the like. The aggregate content in the substrate is, for example, 80% to 99% by volume, and preferably 85% to 95% by volume.

[0038] The binder is an inorganic material that melts at a lower temperature than the aggregate components and binds the aggregates together. Examples of binders that can be used include alumina and silica-based inorganic oxide materials containing alkali metals and alkaline earth metals. Examples of alkali metals that can be used include at least one of sodium (Na), potassium (K), and lithium (Li). The alkali metal may exist in the form of an oxide. Examples of alkaline earth metals that can be used include at least one of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). The alkaline earth metal may exist in the form of an oxide. It is preferable that the binder contains both an alkali metal and an alkaline earth metal. The binder content in the base material is, for example, 1% to 20% by volume, and preferably 5% to 15% by volume.

[0039] The porosity of the substrate is, for example, 25% to 50%, and preferably 30% to 45%. The average pore diameter of the substrate is, for example, 0.1 μm to 50 μm. From the viewpoint of improving the film-forming properties of the filtration layer, the average pore diameter of the substrate is preferably 1 μm to 10 μm. The porosity and average pore diameter of the substrate can be measured by mercury intrusion porosimetry and perm porometer, respectively. The porosity and average pore diameter of the first filtration layer and second filtration layer described below can also be measured in the same manner.

[0040] The first filtration layer and the second filtration layer are formed, for example, from the same material as the substrate. The porosity of the first filtration layer is, for example, 20% to 60%. The average pore diameter of the first filtration layer is, for example, 0.005 μm to 5 μm. The average pore diameter of the first filtration layer is preferably smaller than the average pore diameter of the substrate. The thickness of the first filtration layer is, for example, 1 μm to 300 μm. The porosity of the second filtration layer is, for example, 20% to 60%. The average pore diameter of the second filtration layer is, for example, 0.001 μm to 2 μm. The average pore diameter of the second filtration layer is preferably smaller than the average pore diameter of the first filtration layer. The thickness of the second filtration layer is, for example, 1 μm to 50 μm. The filtration layers are not provided on the inner surfaces of the water collection cells 15, the water collection holes 16, the central communicating channel portion 17, and the end channel portion 18.

[0041] Each of the multiple water collecting cells 15 extends substantially linearly and substantially parallel to the longitudinal direction inside the porous body 1 from the first end face 11 to the second end face 12. Each water collecting cell 15 is closed at both longitudinal end faces (i.e., the first seal 21 and the second seal 22) of the water purification membrane structure 10. Each water collecting cell 15 is, for example, a space formed by watertightly sealing both longitudinal ends of a through hole that penetrates the porous body 1 in the longitudinal direction from the first end face 11 to the second end face 12 with the first seal 21 and the second seal 22.

[0042] The cross-sectional shape of each water-collecting cell 15 perpendicular to the longitudinal direction (hereinafter simply referred to as the "cross-sectional shape") is, for example, approximately circular. The cross-sectional shape of the water-collecting cells 15 may be variously modified, for example, a polygon such as an approximately regular hexagon or an approximately rectangular shape, an ellipse, an oval, or the like. In the examples shown in Figures 3 to 7, the cross-section of the water-collecting cell 15 is depicted as a circle of the same size as the cross-section of the filtration cell 14. The inner diameter of the water-collecting cell 15 is not particularly limited. Note that, when the cross-sectional shape of the water-collecting cell 15 is polygonal, the inner diameter of the water-collecting cell 15 refers to the diameter of the circumscribed circle of the polygon. The cross-sectional shape of the water-collecting cell 15 may be the same as or different from the cross-sectional shape of the filtration cell 14. In the examples shown in Figures 3 to 7, the size of the water-collecting cell 15 is depicted larger than in reality, and the number of water-collecting cells 15 is depicted smaller than in reality. The number and arrangement of the multiple water-collecting cells 15 in the porous body 1 may be modified as appropriate.

[0043] The water collection hole 16 is located in the center of the porous body 1 in a plan view. The porous body 1 has one water collection hole 16. The water collection hole 16 is a substantially cylindrical flow path with a bottom that extends in the longitudinal direction around the central axis J1. The water collection hole 16 extends from the center of the first end face 11 of the porous body 1 toward the (-Z) side and is closed slightly on the (+Z) side of the second end face 12. The water collection hole 16 is formed, for example, by sealing the (-Z) side end of a through hole that penetrates the porous body 1 in the longitudinal direction from the first end face 11 to the second end face 12 with a substantially cylindrical jig centered on the central axis J1. The (+Z) side end of the water collection hole 16 is open at a first seal 21. The (-Z) side end of the water collection hole 16 is closed at a second seal 22.

[0044] The cross-sectional shape of the water collection hole 16 perpendicular to the longitudinal direction (hereinafter simply referred to as the "cross-sectional shape") is, for example, approximately circular. The cross-sectional shape of the water collection hole 16 may be modified in various ways, for example, a polygon such as a regular hexagon or a rectangular shape, an ellipse, an oval shape, or the like. In the examples shown in Figures 3 to 7, the cross-sectional shape of the water collection hole 16 is depicted as a circle. The inner diameter of the water collection hole 16 is not particularly limited, but is, for example, 15% to 45% of the outer diameter of the porous body 1. In this embodiment, the inner diameter of the water collection hole 16 is 50 mm, which is approximately 27.8% of the outer diameter of the porous body 1. Note that, when the cross-sectional shape of the water collection hole 16 is polygonal, the inner diameter of the water collection hole 16 refers to the diameter of the circumscribing circle of the polygon. Furthermore, when the cross-sectional shape of the porous body 1 perpendicular to the longitudinal direction is polygonal, the outer diameter of the porous body 1 refers to the diameter of the circumscribing circle of the polygon.

[0045] In the porous body 1, a plurality of filtration cells 14 and a plurality of water collection cells 15 are arranged around the water collection hole 16 in a plan view. The plurality of filtration cells 14 and the plurality of water collection cells 15 are arranged in a circumferential direction about the central axis J1, spaced apart radially outward from the water collection hole 16. In the following description, the radial direction and the circumferential direction about the central axis J1 will also be simply referred to as the "radial direction" and the "circumferential direction."

[0046] The central communicating channel section 17 is provided in the center in the longitudinal direction of the porous body 1. Specifically, the end on the (+Z) side of the central communicating channel section 17 is located at a position spaced apart from the first end face 11 on the (-Z) side by at least one-third of the total length of the porous body 1. Furthermore, the end on the (-Z) side of the central communicating channel section 17 is located at a position spaced apart from the second end face 12 on the (+Z) side by at least one-third of the total length of the porous body 1.

[0047] As shown in FIG. 5, the central communicating channel section 17 is composed of a plurality of communicating channels that each extend from the outer surface 13 of the porous body 1 in a direction perpendicular to the longitudinal direction (i.e., horizontally). The plurality of communicating channels includes a first vertical channel 171, a second vertical channel 172, and a horizontal channel 173. The plurality of communicating channels extend while avoiding the plurality of filtration cells 14 (i.e., without overlapping with the plurality of filtration cells 14 in plan view), and overlap with the plurality of water collection cells 15 in plan view. In the example shown in FIG. 5, the channel widths of the first vertical channel 171, the second vertical channel 172, and the horizontal channel 173 are drawn larger than they actually are. In addition, in FIG. 6, the first vertical channel 171, the second vertical channel 172, and the horizontal channel 173, which are located on the (-Z) side of the cross-sectional position, are drawn with dashed lines.

[0048] The first vertical flow passages 171 are flow passages that extend substantially linearly from the outer surface 13 of the porous body 1 substantially parallel to the Y direction (hereinafter also referred to as the "vertical direction") and directly communicate with the water collection holes 16. The radially inner ends of the first vertical flow passages 171 open on the inner surface of the water collection holes 16. In the example shown in FIG. 5, on the (+Y) side of the water collection holes 16, three first vertical flow passages 171 are arranged at substantially equal intervals in the X direction (hereinafter also referred to as the "lateral direction") while being spaced apart from each other. On the (-Y) side of the water collection holes 16, three first vertical flow passages 171 are arranged at substantially equal intervals in the X direction while being spaced apart from each other. All of these six first vertical flow passages 171 are located within the range in which the water collection holes 16 are present in the X direction. The three first vertical flow paths 171 on the (+Y) side of the water collection hole 16 and the three first vertical flow paths 171 on the (-Y) side of the water collection hole 16 are located at approximately the same position in the X direction. These six first vertical flow paths 171 are arranged approximately parallel to one another. Note that the number and arrangement of the first vertical flow paths 171 may be changed in various ways.

[0049] A cross section perpendicular to the longitudinal direction of each first vertical flow path 171 (i.e., the Y direction in which the first vertical flow path 171 extends) is slit-shaped and long in the Z direction. In the following description, the cross section perpendicular to the longitudinal direction of each first vertical flow path 171 will also be simply referred to as a "flow path cross section."

[0050] The length in the Z direction of the flow path cross section of each first vertical flow path 171 is, for example, 2% or more, preferably 3% or more, and more preferably 4% or more of the total length in the longitudinal direction (i.e., Z direction) of the porous body 1. Furthermore, the length in the Z direction of the flow path cross section of the first vertical flow path 171 is, for example, 8% or less of the total length in the longitudinal direction of the porous body 1, from the viewpoint of suppressing a decrease in strength of the porous body 1. In this embodiment, the length in the Z direction of the flow path cross section of the first vertical flow path 171 is 60 mm, which is 4% of the above-mentioned total length of the porous body 1.

[0051] Each first vertical flow path 171 overlaps in plan view with a plurality of (seven in the example shown in FIG. 5 ) water collecting cells 15 arranged in a substantially linear manner substantially parallel to the Y direction, and is in communication with the plurality of water collecting cells 15. In the example shown in FIG. 5 , the flow path width in the X direction of each first vertical flow path 171 (i.e., the flow path width in a direction perpendicular to the first vertical flow path 171 in plan view; hereinafter, also simply referred to as "flow path width") is smaller than the inner diameter of the water collecting cell 15, and each first vertical flow path 171 penetrates the plurality of water collecting cells 15 in the Y direction. Note that, as described above, the first vertical flow path 171 is provided so as to avoid the plurality of filtration cells 14, and therefore does not overlap with any of the filtration cells 14 in plan view.

[0052] A plurality of filtration cells 14 are arranged between each two adjacent first vertical flow paths 171 in the X direction. In the example shown in Fig. 5, seven filtration cells 14 arranged in a row in the Y direction are arranged between each two adjacent first vertical flow paths 171. The number and arrangement of the filtration cells 14 located between each two adjacent first vertical flow paths 171 may be changed in various ways. For example, if a plurality of filtration cells 14 arranged in a row in the Y direction is called a filtration cell row, a plurality of (e.g., five) filtration cell rows may be arranged between each two adjacent first vertical flow paths 171 while being spaced apart from each other in the X direction.

[0053] The horizontal flow passage 173 is a flow passage that extends substantially linearly from the outer surface 13 of the porous body 1 along the X direction (i.e., the horizontal direction) and directly communicates with the water collection hole 16. The radially inner end of the horizontal flow passage 173 opens on the inner surface of the water collection hole 16. In the example shown in FIG. 5, one horizontal flow passage 173 extending substantially linearly and substantially parallel to the X direction is provided on the (-X) side of the water collection hole 16. In addition, one horizontal flow passage 173 extending substantially linearly and substantially parallel to the X direction (i.e., substantially parallel to the one horizontal flow passage 173) is provided on the (+X) side of the water collection hole 16. These two horizontal flow passages 173 are arranged at substantially the same position in the Y direction, at substantially the center of the porous body 1 in the Y direction. The two horizontal flow passages 173 are entirely located within the range in the Y direction where the water collection hole 16 is located.

[0054] A cross section of each horizontal flow path 173 perpendicular to the longitudinal direction of the flow path (in the example shown in FIG. 5, the X direction, which is the direction in which the horizontal flow paths 173 extend) has a slit shape that is long in the Z direction. In the following description, the cross section of each horizontal flow path 173 perpendicular to the longitudinal direction of the flow path will also be simply referred to as a "flow path cross section."

[0055] The length of the cross section of each horizontal flow path 173 in the Z direction is, for example, 2% or more, preferably 3% or more, and more preferably 4% or more of the total length in the longitudinal direction (i.e., Z direction) of the porous body 1. Furthermore, from the viewpoint of suppressing a decrease in strength of the porous body 1, the length of the cross section of the horizontal flow path 173 in the Z direction is, for example, 8% or less of the total length in the longitudinal direction of the porous body 1. In this embodiment, the length of the cross section of the horizontal flow path 173 in the Z direction is 60 mm, which is 4% of the above-mentioned total length of the porous body 1.

[0056] Each horizontal flow path 173 overlaps with a plurality of water collecting cells 15 (six in the example shown in FIG. 5 ) arranged in a substantially linear manner substantially parallel to the X direction in plan view, and communicates with the plurality of water collecting cells 15. In the example shown in FIG. 5 , the flow path width of each horizontal flow path 173 in the Y direction (i.e., the flow path width in a direction perpendicular to the horizontal flow path 173 in plan view; hereinafter, simply referred to as "flow path width") is larger than the inner diameter of the water collecting cell 15. Therefore, in FIG. 5 , the upper end (i.e., the end on the (+Z) side) of each water collecting cell 15 overlapping with the horizontal flow path 173 opens at the bottom surface of the horizontal flow path 173. As described above, the horizontal flow path 173 is provided so as to avoid the plurality of filtration cells 14, and therefore does not overlap with any of the filtration cells 14 in plan view.

[0057] Note that, as long as the horizontal flow path 173 extends along the X direction, it does not necessarily have to be parallel to the X direction, and it may be inclined at a predetermined angle with respect to the X direction. The inclination angle is, for example, greater than 0° and equal to or less than 30°. Even when the horizontal flow path 173 is inclined with respect to the X direction, it is preferable that the entire horizontal flow path 173 is located within the range in the Y direction where the water collection holes 16 are present. In other words, the (+Y) side end of the horizontal flow path 173 is located closer to the (-Y) side than the (+Y) side end of the water collection holes 16 or at approximately the same position in the Y direction, and the (-Y) side end of the horizontal flow path 173 is located closer to the (+Y) side than the (-Y) side end of the water collection holes 16 or at approximately the same position in the Y direction.

[0058] 5, only one lateral flow path 173 is provided on each side of the water collection hole 16 in the lateral direction (i.e., the X direction), but this is not limiting. For example, multiple lateral flow paths 173 may be provided on each of the (+X) side and the (-X) side of the water collection hole 16. Even when multiple lateral flow paths 173 are provided on one side of the water collection hole 16 in the X direction, it is preferable that all of the multiple lateral flow paths 173 are located within the range in which the water collection hole 16 exists in the Y direction.

[0059] The second vertical flow passage 172 is a flow passage that extends substantially linearly from the outer surface 13 of the porous body 1 substantially parallel to the Y direction (i.e., the vertical direction) and directly communicates with the horizontal flow passage 173. The second vertical flow passage 172 is disposed at a position spaced apart from the water collection holes 16 in the X direction (i.e., the horizontal direction) and does not directly communicate with the water collection holes 16. The second vertical flow passage 172 indirectly communicates with the water collection holes 16 via the horizontal flow passage 173.

[0060] In the example shown in Fig. 5, on the (-X) side of the water collection hole 16, three second vertical flow paths 172 are arranged at approximately equal intervals in the X direction while being spaced apart from one another on the (+Y) side of the horizontal flow path 173. The (-Y) side ends of the three second vertical flow paths 172 directly communicate with the horizontal flow path 173. Furthermore, on the (-X) side of the water collection hole 16, three second vertical flow paths 172 are also arranged at approximately equal intervals in the X direction while being spaced apart from one another on the (-Y) side of the horizontal flow path 173. The (+Y) side ends of the three second vertical flow paths 172 directly communicate with the horizontal flow path 173. The number and arrangement of the second vertical flow paths 172 may be changed in various ways.

[0061] On the (+X) side of the water collection hole 16, three second vertical flow paths 172 are arranged at approximately equal intervals in the X direction while being spaced apart from one another on the (+Y) side of the horizontal flow path 173, similar to the (-X) side of the water collection hole 16. The (-Y) side ends of the three second vertical flow paths 172 are directly connected to the horizontal flow path 173. Furthermore, on the (+X) side of the water collection hole 16, three second vertical flow paths 172 are also arranged at approximately equal intervals in the X direction while being spaced apart from one another on the (-Y) side of the horizontal flow path 173. The (+Y) side ends of the three second vertical flow paths 172 are directly connected to the horizontal flow path 173.

[0062] On the (-X) side of the water collection hole 16, the three second vertical flow paths 172 on the (+Y) side of the horizontal flow path 173 and the three second vertical flow paths 172 on the (-Y) side of the horizontal flow path 173 are located at approximately the same position in the X direction. Also on the (+X) side of the water collection hole 16, the three second vertical flow paths 172 on the (+Y) side of the horizontal flow path 173 and the three second vertical flow paths 172 on the (-Y) side of the horizontal flow path 173 are located at approximately the same position in the X direction. These twelve first vertical flow paths 171 are arranged approximately parallel to one another.

[0063] The channel width of the horizontal channel 173 is preferably larger than the channel width in the X direction of the second vertical channel 172 (i.e., the channel width in a direction perpendicular to the second vertical channel 172 in a plan view; hereinafter, simply referred to as "channel width"). The channel width of the horizontal channel 173 is, for example, at least twice the channel width of the second vertical channel 172. The channel width of the horizontal channel 173 is preferably at least 2.5 times, and more preferably at least three times, the channel width of the second vertical channel 172. Furthermore, from the viewpoint of preventing overlap between the horizontal channel 173 and the filtration cell 14 in a plan view, the channel width of the horizontal channel 173 is, for example, at most eight times the channel width of the second vertical channel 172. Note that the channel width of the horizontal channel 173 may be equal to or smaller than the channel width of the second vertical channel 172.

[0064] A cross section perpendicular to the longitudinal direction of each second vertical flow path 172 (i.e., the Y direction in which the second vertical flow paths 172 extend) is slit-shaped and long in the Z direction. In the following description, the cross section perpendicular to the longitudinal direction of each second vertical flow path 172 will also be simply referred to as a "flow path cross section."

[0065] The length in the Z direction of the flow path cross section of each second vertical flow path 172 is, for example, 2% or more, preferably 3% or more, and more preferably 4% or more of the total length in the longitudinal direction (i.e., Z direction) of the porous body 1. Furthermore, the length in the Z direction of the flow path cross section of the second vertical flow path 172 is, for example, 8% or less of the total length in the longitudinal direction of the porous body 1, from the viewpoint of suppressing a decrease in strength of the porous body 1. In this embodiment, the length in the Z direction of the flow path cross section of the second vertical flow path 172 is 60 mm, which is 4% of the above-mentioned total length of the porous body 1.

[0066] Each second vertical flow path 172 overlaps in plan view with a plurality of water collecting cells 15 (five to eight in the example shown in FIG. 5) that are arranged in a substantially linear manner substantially parallel to the Y direction, and communicates with the plurality of water collecting cells 15. In the example shown in FIG. 5, the flow path width of each second vertical flow path 172 is smaller than the inner diameter of the water collecting cell 15, and each second vertical flow path 172 penetrates the plurality of water collecting cells 15 in the Y direction. As described above, the second vertical flow paths 172 are provided so as to avoid the plurality of filtration cells 14, and therefore do not overlap with any of the filtration cells 14 in plan view.

[0067] A plurality of filtration cells 14 are arranged between each two adjacent second vertical flow paths 172 in the X direction. In the example shown in Fig. 5, six to seven filtration cells 14 arranged in a row in the Y direction are arranged between each two adjacent second vertical flow paths 172. The number and arrangement of the filtration cells 14 located between each two adjacent second vertical flow paths 172 may be changed in various ways. For example, a plurality of (for example, five) filtration cell rows may be arranged between each two adjacent second vertical flow paths 172 while being spaced apart from each other in the X direction.

[0068] A plurality of filtration cells 14 are also arranged between the second vertical flow path 172 and the first vertical flow path 171 that are adjacent to each other in the X direction. In the example shown in Fig. 5, seven filtration cells 14 are arranged in a row in the Y direction between the adjacent second vertical flow path 172 and the first vertical flow path 171. The number and arrangement of the filtration cells 14 located between the adjacent second vertical flow path 172 and the first vertical flow path 171 may be changed in various ways. For example, a plurality of (for example, five) filtration cell rows may be arranged at intervals from each other in the X direction between the adjacent second vertical flow path 172 and the first vertical flow path 171.

[0069] A plurality of filtration cells 14 may also be arranged in a region on the (-X) side of the second vertical flow passage 172 that is located furthest to the (-X) side among the plurality of second vertical flow passages 172. In the example shown in Fig. 5, four filtration cells 14 are arranged in a row in the Y direction in this region. The number and arrangement of the filtration cells 14 located in this region may be changed in various ways. For example, a plurality of (e.g., five) filtration cell rows may be arranged in this region while being spaced apart from each other in the X direction.

[0070] A plurality of filtration cells 14 may also be arranged in a region on the (+X) side of the second vertical flow passage 172 that is located furthest to the (+X) side among the plurality of second vertical flow passages 172. In the example shown in Fig. 5, four filtration cells 14 are arranged in a row in the Y direction in this region. The number and arrangement of the filtration cells 14 located in this region may be changed in various ways. For example, a plurality of (e.g., five) filtration cell rows may be arranged in this region while being spaced apart from each other in the X direction.

[0071] The end flow path section 18 is provided at the end on the (+Z) side in the longitudinal direction of the porous body 1 (i.e., the end on the side closer to an upper opening 411 of the housing main body 41, which will be described later). Specifically, the (-Z) side end of the end flow path section 18 is located at a position spaced 1 / 3 of the total length of the porous body 1 from the first end face 11 of the porous body 1 on the (-Z) side, or on the (+Z) side of that position. Furthermore, the (+Z) side end of the end flow path section 18 is located at the same position in the Z direction as the first end face 11 of the porous body 1, or on the (-Z) side of the first end face 11. For example, the (+Z) side end of the end flow path section 18 is located at a position spaced 1% to 3% of the total length of the porous body 1 from the first end face 11 on the (-Z) side. The end flow path section 18 is used as a flow path section for removing air from the porous body 1.

[0072] As shown in Fig. 7, the end channel section 18 is composed of a plurality of channels that each extend from the outer surface 13 of the porous body 1 in a direction perpendicular to the longitudinal direction (i.e., horizontally). The plurality of channels includes a first channel 181, a second channel 182, and a third channel 183. The plurality of channels extend in a direction perpendicular to the Z direction, avoiding the plurality of filtration cells 14 (i.e., without overlapping with the plurality of filtration cells 14 in plan view), and overlap with and directly communicate with the plurality of water collection cells 15 in plan view. In the example shown in Fig. 7, the channel widths of the first channel 181, the second channel 182, and the third channel 183 are drawn larger than they actually are.

[0073] In the end channel section 18 illustrated in Fig. 7, the shapes and arrangement of the multiple first channel sections 181, the multiple second channel sections 182, and the multiple third channel sections 183 in a plan view are substantially the same as the shapes and arrangement of the multiple first vertical channel sections 171, the multiple second vertical channel sections 172, and the multiple horizontal channel sections 173 in a plan view in the central communicating channel section 17 illustrated in Fig. 5. However, unlike the horizontal channel sections 173 of the central communicating channel section 17, the radially inner ends of each third channel section 183 do not communicate with the water collection holes 16 and are closed near the water collection holes 16. Therefore, although each second channel section 182 also communicates with the third channel sections 183, it does not indirectly communicate with the water collection holes 16 like the second vertical channel sections 172 of the central communicating channel section 17. That is, the first flow path 181 is a communication flow path that communicates with the water collection hole 16, but the second flow path 182 and the third flow path 183 are not communication flow paths that communicate with the water collection hole 16.

[0074] 7, only one third flow path 183 is provided on each of the (-X) side and the (+X) side of the water collection hole 16. Each third flow path 183 extends approximately parallel to the X direction. In addition, the flow path width of the third flow path 183 in plan view is larger than the flow path width of the second flow path 182, and is at least two times (preferably at least three times) the flow path width of the second flow path 182.

[0075] In the end flow path section 18, the flow path cross section (i.e., the cross section perpendicular to the longitudinal direction of the flow path) of each of the first flow paths 181, second flow paths 182, and third flow paths 183 is slit-shaped and long in the Z direction. The lengths in the Z direction of the flow path cross sections of the first flow path 181, second flow path 182, and third flow path 183 are shorter than, for example, the lengths in the Z direction of the flow path cross sections of the first vertical flow path 171, second vertical flow path 172, and horizontal flow path 173 in the central communicating flow path section 17.

[0076] The lengths of the flow path cross sections of the first flow path 181, the second flow path 182 and the third flow path 183 in the Z direction may be longer than or the same as the lengths of the flow path cross sections of the first vertical flow path 171, the second vertical flow path 172 and the horizontal flow path 173 in the central communicating flow path section 17 in the Z direction.

[0077] 2, the end portion on the (-Z) side in the longitudinal direction of the porous body 1 (i.e., the end portion on the side closer to the lower opening 412 of the housing main body 41, which will be described later) does not have a slit-shaped communicating flow path portion, such as the central communicating flow path portion 17, which extends horizontally from the outer surface 13 and communicates with the water collection holes 16. Furthermore, as described above, the second flow path 182 and the third flow path 183 of the end flow path portion 18 do not communicate with the water collection holes 16, and therefore a communicating flow path portion having the same structure as the central communicating flow path portion 17 in a plan view is not provided at the end portion on the (+Z) side in the longitudinal direction of the porous body 1.

[0078] As described above, the water purification membrane assembly 4 shown in FIG. 1 includes the water purification membrane structure 10, a housing body 41, and two sealing members 42. The housing body 41 is a tubular member extending in the vertical direction. In the example shown in FIG. 1, the housing body 41 is a substantially cylindrical member made of stainless steel. The material of the housing body 41 may be changed as appropriate, and the housing body 41 may be made of resin, for example. The housing body 41 has openings at its upper and lower ends. In the following description, the openings located at the upper and lower ends of the housing body 41 are also referred to as the "upper opening 411" and the "lower opening 412," respectively. The water purification membrane structure 10 is accommodated in the internal space of the housing body 41. The water purification membrane structure 10 is arranged in the housing body 41 so that the central axis J1 (see FIG. 2) of the water purification membrane structure 10 is substantially parallel to the vertical direction. Within the housing body 41, the side of the water purification membrane structure 10 on which the first end face 11 is provided (i.e., one side in the longitudinal direction) is located on the upper side, and the side on which the second end face 12 is provided (i.e., the other side in the longitudinal direction) is located on the lower side.

[0079] The vertical length of the housing body 41 is slightly longer than the longitudinal length (i.e., vertical length) of the water purification membrane structure 10. The diameter of the inner surface 413 of the housing body 41 is larger than the diameter of the outer surface 13 of the water purification membrane structure 10. The water purification membrane structure 10 is disposed at a distance from the inner surface 413 of the housing body 41 over the entire circumferential direction so that the central axis J1 substantially coincides with the central axis of the housing body 41. In other words, the housing body 41 is a substantially cylindrical member centered on the central axis J1, and completely covers the outer surface 13 of the water purification membrane structure 10 while being spaced apart.

[0080] A seal member 42 is provided between the upper edge of the water purification membrane structure 10 (i.e., the outer peripheral edge of the first end face 11) and the inner surface 413 of the housing body 41. In the example shown in FIG. 1 , the seal member 42 is an L-shaped resin gasket that is substantially circumferentially centered on the central axis J1 in a plan view (i.e., a gasket whose cross section perpendicular to the circumferential direction is substantially L-shaped). The seal member 42 is in close contact with the outer peripheral edge of the first seal 21 provided on the first end face 11 of the porous body 1, the upper edge of the outer surface 13 of the water purification membrane structure 10, and the inner surface 413 of the housing body 41. This separates the substantially cylindrical space between the outer surface 13 of the water purification membrane structure 10 and the inner surface 413 of the housing body 41 from the space above the first seal 21 of the water purification membrane structure 10 in a water-impermeable manner.

[0081] A seal member 42 having substantially the same shape as the seal member 42 is also provided upside down between the lower edge of the water purification membrane structure 10 (i.e., the outer periphery of the second end face 12) and the inner surface 413 of the housing body 41. The seal member 42 is in close contact with the outer periphery of the second seal 22 provided on the second end face 12 of the porous body 1, the lower edge of the outer surface 13 of the water purification membrane structure 10, and the inner surface 413 of the housing body 41. This separates the substantially cylindrical space between the outer surface 13 of the water purification membrane structure 10 and the inner surface 413 of the housing body 41 from the space below the second seal 22 of the water purification membrane structure 10 in a water-impermeable manner.

[0082] Next, the generation of purified water by the water purification membrane structure 10 and the backwashing of the water purification membrane structure 10 will be described in detail.

[0083] 1 flows into the housing body 41 through the upper opening 411 and the lower opening 412 of the housing body 41, and is supplied to the inside of each filtration cell 14 through the (+Z) side opening and the (-Z) side opening of each filtration cell 14. As described above, each filtration cell 14 is separated from the plurality of water collection cells 15, water collection holes 16, central communicating flow path portion 17, and end flow path portion 18 by partition walls that are part of the porous body 1.

[0084] The raw water supplied to each filtration cell 14 passes through the partition wall and flows into the collection cells 15 surrounding each filtration cell 14. At this time, suspended matter and the like in the raw water are filtered out by the filtration layer constituting the inner surface of the filtration cell 14, and purified water, which is a liquid from which suspended matter and the like have been removed from the raw water, flows into the collection cells 15. As described above, each collection cell 15 is directly connected to the central communication channel portion 17 and is also indirectly connected to the water collection hole 16 via the central communication channel portion 17.

[0085] The purified water that flows into each water collection cell 15 flows into the water collection holes 16 via the central communicating channel 17 and the end communicating channel 18 and is collected. The central communicating channel 17 and the end communicating channel 18 also guide purified water that passes through the partition walls from the filtration cells 14 and flows out radially outward from the outer surface 13 of the porous body 1 to the water collection holes 16. The purified water collected in the water collection holes 16 is delivered to the purified water reservoir 82 via the purified water piping 52 connected to the water collection holes 16. Note that a seal (e.g., a glass seal) is provided at the end of the inner surface of the water collection hole 16 on the (+Z) side to seal the connection with the purified water piping 52. In the water purification membrane structure 10, some of the purified water that passes through the partition walls from the filtration cells 14 may flow directly into the central communicating channel 17 without passing through the water collection cells 15. Furthermore, a portion of the purified water that has permeated the partition wall from the filtration cell 14 may flow directly into the water collection hole 16 without passing through the water collection cell 15 and the central communication channel portion 17 .

[0086] When backwashing the water purification membrane structure 10, backwash water (e.g., purified water) is pressure-fed from the purified water piping 52 to the water collection holes 16. The pressure of the backwash water supplied to the water collection holes 16 is, for example, 0.1 MPa to 0.6 MPa. The backwash water supplied to the water collection holes 16 flows into each water collection cell 15 via the central communicating channel portion 17 and the end channel portions 18, flows in the (+Z) and (-Z) directions within each water collection cell 15, and passes through the partition walls surrounding each water collection cell 15 to flow into each filtration cell 14. A portion of the backwash water supplied to the water collection holes 16 may pass through the partition walls surrounding the water collection holes 16 and flow into each filtration cell 14 without passing through the central communicating channel portion 17, the end channel portions 18, and the water collection cells 15. In addition, a portion of the backwash water supplied to the water collection hole 16 may pass through the surrounding partition walls from the central communicating flow path section 17 and the end flow path section 18 and flow into the inside of each filtration cell 14 without passing through the water collection cell 15.

[0087] When the backwash water passes through the partition walls surrounding the filtration cells 14 and flows into the interior of the filtration cells 14, deposits accumulated on the inner surfaces of the filtration cells 14 (i.e., on the filtration layers) are peeled off from the inner surfaces. The peeled deposits move with the backwash water flowing toward the (+X) side opening or the (-X) side opening within the filtration cells 14, and are discharged to the outside of the water purification membrane structure 10 from the (+X) side opening or the (-X) side opening of the filtration cells 14.

[0088] As described above, the water purification membrane structure 10 is provided with the central communicating channel 17. This increases the flow rate of backwash water supplied to the longitudinal center of each water collection cell 15 during backwashing, compared to a case in which the central communicating channel 17 is not provided. This also increases the flow rate of backwash water that permeates the partition walls surrounding the filtration cells 14 and flows into the longitudinal center of the filtration cells 14. This allows deposits to be effectively removed from the filtration layer at the longitudinal center of the filtration cells 14. Furthermore, the flow rate of backwash water flowing from the longitudinal center of the filtration cells 14 to the openings at the longitudinal ends of the filtration cells 14 also increases, allowing deposits that have been removed from the filtration layer at the longitudinal center of the filtration cells 14 to be effectively discharged to the outside of the filtration cells 14. This prevents clogging of the filtration cells 14 due to deposits accumulated on the filtration layer, thereby preventing a decrease in the filtration performance of the water purification membrane structure 10.

[0089] Table 1 shows the relationship between the presence or absence of the central communicating channel portion 17 and the clogging of the filtration cell 14.

[0090] [Table 1]

[0091] In Example 1, an experiment was conducted using a water purification membrane structure 10 having the central communicating channel portion 17 described above. The clogging rates and clogging extents in Table 1 are the results of measuring the clogging of the filtration cells 14 after operating a filtration device 5 equipped with the water purification membrane structure 10 for two months. The clogging extent of the filtration cells 14 was confirmed by removing the water purification membrane structure 10 from the filtration device 5 after two months of operation and inserting a piano wire into each filtration cell 14. The clogging rate of the filtration cells 14 was calculated by dividing the total longitudinal length of the clogging points in all filtration cells 14 provided in the porous body 1 by the total longitudinal length of all filtration cells 14. In Table 1, the clogging extents in two representative longitudinal cross sections are indicated by hatching. The diagrams showing the clogging extents are schematic diagrams.

[0092] In Example 1, as an operating condition for producing purified water, the linear velocity of purified water passing through the filtration layer of the filtration cell 14 was set to 1.5 m / day. As a backwashing condition, the amount of backwash water supplied to the water collection hole 16 was set to 1.5 m / day per 1 m of the filtration layer. 2 The backwash water pressure was 0.3 MPa. The interval between backwashes (i.e., the purified water production time between backwashes) was 90 minutes.

[0093] In Comparative Example 1, a comparative water purification membrane structure having a different size and arrangement of communicating channels from the water purification membrane structure 10 was used instead of the water purification membrane structure 10, and the results of clogging of the filtration cells 14 after operating the filtration device 5 for two months were obtained. The operating conditions during purified water production and the backwashing conditions were the same as those described above.

[0094] The water purification membrane structure of Comparative Example 1 has substantially the same structure and size as the water purification membrane structure 10 of Example 1, except for the arrangement and size of the communicating channels. In the water purification membrane structure of Comparative Example 1, the above-mentioned central communicating channel section 17 is omitted, and end channel sections having substantially the same shape as the central communicating channel section 17 are provided at the ends of the porous body on the (+Z) side and (-Z) side. However, the length of these end channel sections in the Z direction is 65 mm. As described above, the length of the central communicating channel section 17 in Example 1 (i.e., the first vertical channel 171, second vertical channel 172, and horizontal channel 173) in the Z direction is 60 mm.

[0095] As shown in Table 1, the clogging rate in Comparative Example 1 was 23%, while the clogging rate in Example 1 was 12%. From Example 1 and Comparative Example 1, it can be seen that by providing the water purification membrane structure 10 with the central communicating channel portion 17, backwashing of the water purification membrane structure 10 is performed efficiently and clogging of the filtration cells 14 is suppressed.

[0096] In the water purification membrane structure of Comparative Example 1, backwash water flows into each collection cell from the end flow passages provided at both longitudinal ends and collides at the longitudinal center of the collection cell, resulting in a decrease in the flow rate of backwash water supplied to the longitudinal center of the collection cell. Therefore, the flow rate of backwash water supplied also decreases at the longitudinal center of the filtration cell, presumably causing insufficient removal of deposits on the inner surfaces of the filtration cells. In contrast, in the water purification membrane structure 10 of Example 1, backwash water flows into each collection cell 15 from the central communication flow passage 17 provided at the longitudinal center and flows smoothly from the longitudinal center of the collection cell 15 to both longitudinal ends. Therefore, backwash water is smoothly supplied to almost the entire longitudinal length of the filtration cell 14, presumably effectively removing deposits on the inner surfaces of the filtration cells 14.

[0097] Table 2 shows the relationship between the length in the Z direction of the central communicating channel portion 17 in the water purification membrane structure 10 and the pressure required to supply backwash water to the water collection hole 16.

[0098] [Table 2]

[0099] In Example 2, a simulation was performed on a water purification membrane structure 10 in which the length of the central communicating channel portion 17 in the Z direction was 60 mm. In this simulation, the supply pressure of backwash water required to supply backwash water to the water collection holes 16 at a flow rate of 420 L / min when backwashing the water purification membrane structure 10 in the filtration device 5 was determined. Furthermore, the pressure of the backwash water discharged from the opening on the (-Y) side of the filtration cell 14 during backwashing was set to 25 kPa, and the pressure of the backwash water discharged from the opening on the (+Y) side of the filtration cell 14 during backwashing was set to 10 kPa.

[0100] In Example 3, a simulation was performed on the same water purification membrane structure 10 as in Example 2, except that the length of the central communicating channel section 17 in the Z direction was changed to 30 mm. The ratio of the length of the central communicating channel section 17 in the Z direction to the total longitudinal length of the porous body 1 was 4% in Example 2 and 2% in Example 3. The backwash water supply pressure was 304.8 kPa in Example 2 and 530.5 kPa in Example 3. From Examples 2 and 3, it is believed that by setting the length of the central communicating channel section 17 in the Z direction to 3% or more of the total longitudinal length of the porous body 1, the pressure loss of the backwash water in the water purification membrane structure 10 is reduced, and the backwash water supply pressure is reduced to 420 kPa or less.

[0101] Table 3 shows the relationship between the flow path width of the horizontal flow path 173 in the central communicating flow path section 17 and the variation in flow rate distribution of the filtration cell 14 during backwashing.

[0102] [Table 3]

[0103] In Example 4, the variation in flow rate distribution in the filtration cells 14 was determined when communicating flow path portions having substantially the same shape as the above-mentioned central communicating flow path portion 17 were provided at both longitudinal ends of the water purification membrane structure 10. The flow path width of the horizontal flow path 173 in Example 4 was two to three times (i.e., more than twice) the flow path width of the second vertical flow path 172. The variation in flow rate distribution in Table 3 was determined by dividing the deviation of the backwash water flow rate in each filtration cell 14 from the average value, using the average value of the backwash water flow rates in a predetermined number of filtration cells 14 as a reference, by the average value.

[0104] In Comparative Example 2, an experiment was conducted using a comparative water purification membrane structure having a different flow path width of the lateral flow path 173 from that of the water purification membrane structure 10 of Example 4. The variation in flow rate distribution in Table 3 was determined in the same manner as in Example 4.

[0105] The water purification membrane structure of Comparative Example 2 has substantially the same structure and size as the water purification membrane structure 10 of Example 4, except that it has horizontal channels different from the horizontal channels 173 of Example 4. In the water purification membrane structure of Comparative Example 2, the channel width of the horizontal channels is the same as the channel width of the second vertical channels 172 (i.e., less than twice the channel width of the second vertical channels 172). In the water purification membrane structure of Comparative Example 2, two horizontal channels are provided on each of the (-X) and (+X) sides of the water collection hole 16. The two horizontal channels extend obliquely from the water collection hole 16, and the distance between the two horizontal channels in the Y direction gradually increases with increasing distance from the water collection hole 16 in the X direction. The distance between the two horizontal channels in the Y direction is greater than the diameter of the water collection hole 16 on the outer surface of the water purification membrane structure of the Comparative Example.

[0106] As shown in Table 3, in Comparative Example 2, the variation in flow rate distribution in the filtration cell 14 was -89% to +32%, whereas in Example 4, the variation in flow rate distribution in the filtration cell 14 was -53% to +15%. From Example 4 and Comparative Example 2, it can be seen that by making the flow path width of the horizontal flow path 173 at least twice the flow path width of the second vertical flow path 172, the pressure loss in the horizontal flow path 173 is reduced, the uniformity of the flow rate of the backwash water supplied to the plurality of second vertical flow paths 172 is improved, and the variation in flow rate distribution in the plurality of filtration cells 14 is suppressed.

[0107] As described above, the water purification membrane structure 10, which produces purified water from raw water, comprises a columnar porous body 1 extending in the longitudinal direction (the Z direction in the above example), a water-impermeable first seal 21, and a water-impermeable second seal 22. The first seal 21 covers a first end face 11, which is an end face on one side of the porous body 1 in the longitudinal direction (the (+Z) side in the above example). The second seal 22 covers a second end face 12, which is an end face on the other side of the porous body 1 in the longitudinal direction (the (-Z) side in the above example). The porous body 1 comprises a plurality of filtration cells 14, water collection holes 16, and a central communicating channel portion 17. The plurality of filtration cells 14 penetrate the porous body 1 in the longitudinal direction from the first end face 11 to the second end face 12 and open at the first seal 21 and the second seal 22. Raw water is supplied to the plurality of filtration cells 14. The water collection hole 16 opens at the first seal 21, extends longitudinally from the first end surface 11, and closes at the second seal 22. The water collection hole 16 collects purified water.

[0108] The central communicating channel section 17 extends in a direction perpendicular to the longitudinal direction (horizontally in the above example) from the outer surface 13 connecting the first end face 11 and the second end face 12, avoiding the multiple filtration cells 14. The central communicating channel section 17 communicates with the water collection holes 16. The water collection holes 16 are located in the center of the first end face 11 when viewed parallel to the longitudinal direction (in a plan view in the above example). The central communicating channel section 17 is located at a position spaced apart from the first end face 11 by at least one-third of the total length of the porous body 1 in the longitudinal direction and at a position spaced apart from the second end face 12 by at least one-third of the total length of the porous body 1 in the longitudinal direction. The cross sections of the communicating channels constituting the central communicating channel section 17 perpendicular to the longitudinal direction of the channels (cross sections of the first vertical channel 171, second vertical channel 172, and horizontal channel 173 in the above example) are slit-shaped and long in the longitudinal direction.

[0109] The provision of the central communication channel 17 in the water purification membrane structure 10 increases the flow rate of backwash water supplied to the longitudinal center of each water collection cell 15 during backwashing, as described above. This increases the flow rate of backwash water that permeates the partition walls surrounding the filtration cells 14 and flows into the longitudinal center of the filtration cells 14, thereby effectively removing deposits from the filtration layer at the longitudinal center of the filtration cells 14. Furthermore, the flow rate of backwash water flowing from the longitudinal center of the filtration cells 14 to the openings at the longitudinal ends can be increased, thereby effectively discharging deposits that have been removed from the filtration layer to the outside of the filtration cells 14. Therefore, deposits that have accumulated on the inner surfaces of the filtration cells 14 (i.e., the filtration layer) can be effectively removed during backwashing. As a result, clogging of the filtration cells 14 due to the deposits is suppressed, and deterioration of the filtration performance of the water purification membrane structure 10 over time is suppressed.

[0110] As described above, the porous body 1 preferably further includes a plurality of water collection cells 15. Each of the plurality of water collection cells 15 extends in the longitudinal direction and is closed by a first seal 21 and a second seal 22. Purified water is collected in the plurality of water collection cells 15. The central communicating channel section 17 preferably communicates with the plurality of water collection cells 15. This allows backwash water to be supplied to the plurality of water collection cells 15 via the central communicating channel section 17 during backwashing of the water purification membrane structure 10. This improves the uniformity of the flow rate of backwash water supplied to the plurality of water collection cells 15.

[0111] As described above, it is preferable that the other longitudinal end of the porous body 1 (the end on the (-Z) side in the above example) not be provided with a communicating flow path portion extending from the outer surface 13 in a direction perpendicular to the longitudinal direction and communicating with the water collection holes 16. This makes it possible to increase the flow rate of backwash water flowing from the water collection holes 16 into the central communicating flow path portion 17 during backwashing, compared to when a communicating flow path portion is provided at the end. As a result, deposits on the filtration cells 14 can be more effectively removed. Furthermore, the structure of the water purification membrane structure 10 can be simplified, thereby reducing the manufacturing cost of the water purification membrane structure 10.

[0112] As described above, the longitudinal length of the central communicating channel section 17 (in the above example, the Z-direction lengths of the first vertical channel 171, the second vertical channel 172, and the horizontal channel 173) is preferably 3% or more of the entire longitudinal length of the porous body 1. This makes it possible to reduce the supply pressure of backwash water to the water purification membrane structure 10, as described above. From the viewpoint of further reducing the supply pressure of backwash water, the longitudinal length of the central communicating channel section 17 is preferably 4% or more of the entire longitudinal length of the porous body 1.

[0113] As described above, the central communicating channel section 17 preferably includes a first vertical channel 171, a horizontal channel 173, and a second vertical channel 172. The first vertical channel 171 extends linearly from the outer surface 13 in a vertical direction (Y direction in the above example) perpendicular to the longitudinal direction and directly communicates with the water collection holes 16. The horizontal channel 173 extends linearly from the outer surface 13 in a horizontal direction (X direction in the above example) perpendicular to the vertical direction and directly communicates with the water collection holes 16. The second vertical channel 172 is spaced apart from the water collection holes 16 in the horizontal direction and extends linearly from the outer surface 13 in the vertical direction and directly communicates with the horizontal channel 173. By communicating the second vertical channel 172 with the water collection holes 16 via the horizontal channel 173 in this way, the flow rate of backwash water supplied to the region where the second vertical channel 172 is located (i.e., the region away from the water collection holes 16) can be increased.

[0114] Furthermore, when viewed parallel to the longitudinal direction (in the above example, in a plan view), it is preferable that the channel width of the horizontal channel 173 in a direction perpendicular to the horizontal channel 173 is larger than the channel width of the second vertical channel 172 in the horizontal direction. This reduces the pressure loss of the backwash water supplied to the second vertical channel 172 via the horizontal channel 173. As a result, the flow rate of the backwash water supplied to the region where the second vertical channel 172 is located (i.e., the region away from the water collection holes 16) can be further increased. Therefore, in the filtration cells 14 located near the water collection cells 15 overlapping with the second vertical channel 172, deposits deposited on the inner surfaces of the filtration cells 14 can be more effectively removed during backwashing.

[0115] As described above, it is preferable that the horizontal flow passage 173 extend parallel to the horizontal direction (X direction in the above example). This allows the backwash water to be supplied approximately evenly to the multiple second vertical flow passages 172 located on both sides in the width direction of the horizontal flow passage 173 (the (+Y) side and the (-Y) side in the above example). As a result, the uniformity of removal of deposits from the multiple filtration cells 14 can be improved.

[0116] As described above, it is preferable to provide only one horizontal flow path 173 on each side of the water collection hole 16 in the horizontal direction (the X direction in the above example). This increases the flow rate of backwash water supplied to the region where the second vertical flow path 172 is located (i.e., the region away from the water collection hole 16), while simplifying the structure of the water purification membrane structure 10.

[0117] As described above, when viewed parallel to the longitudinal direction (in the above example, when viewed from above), the flow path width of the horizontal flow path 173 in the direction perpendicular to the horizontal flow path 173 (in the above example, the flow path width of the horizontal flow path 173 in the Y direction) is preferably at least twice the flow path width of the second vertical flow path 172 in the horizontal direction. This makes it possible to suitably reduce the pressure loss of the backwash water supplied to the second vertical flow path 172 via the horizontal flow path 173, and further increase the flow rate of the backwash water supplied to the region where the second vertical flow path 172 is located (i.e., the region away from the water collection hole 16).

[0118] The water purification membrane assembly 4, which produces purified water from raw water, includes the water purification membrane structure 10 described above and a housing body 41. The housing body 41 accommodates the water purification membrane structure 10 so that the one longitudinal side and the other longitudinal side (in the above example, the (+Z) side and the (-Z) side) of the water purification membrane structure 10 are the upper and lower sides, respectively. The housing body 41 is placed in raw water 91. The housing body 41 is cylindrical and covers the outer surface 13 of the water purification membrane structure 10. The raw water 91 flows into the housing body 41 through an upper opening 411 and a lower opening 412 of the housing body 41 and is supplied to the multiple filtration cells 14 of the water purification membrane structure 10.

[0119] In this way, by covering the outer surface 13 of the water purification membrane structure 10 with the housing body 41, there is no need to cover the outer surface 13 of the porous body 1 with a seal such as glass. Therefore, when backwashing the water purification membrane structure 10, the seal can be prevented from being damaged by the pressure of the backwash water, etc. In addition, the manufacture of the water purification membrane structure 10 can be simplified. Furthermore, since the seal, which has a relatively low strength, is omitted, the water purification membrane structure 10 can be handled more easily.

[0120] In the water purification membrane structure 10, the central communicating channel section 17 may be omitted from the longitudinal center, and communicating channel sections having substantially the same structure as the central communicating channel section 17 may be provided in other longitudinal locations (for example, at the ends). In this case, in the communicating channel section, the channel width of the horizontal channel corresponding to the above-mentioned horizontal channel 173 is made larger than the channel width of the second vertical channel corresponding to the above-mentioned second vertical channel 172, thereby increasing the flow rate of backwash water supplied to the region where the second vertical channel is located (i.e., the region away from the water collection holes 16).

[0121] Specifically, a water purification membrane structure 10 that produces purified water from raw water comprises a columnar porous body 1 extending in the longitudinal direction (Z direction in the above example), a water-impermeable first seal 21, and a water-impermeable second seal 22. The first seal 21 covers a first end face 11, which is an end face on one side in the longitudinal direction of the porous body 1 (the (+Z) side in the above example). The second seal 22 covers a second end face 12, which is an end face on the other side in the longitudinal direction of the porous body 1 (the (-Z) side in the above example). The porous body 1 comprises a plurality of filtration cells 14, water collection holes 16, and a communication flow path portion. The plurality of filtration cells 14 penetrate the porous body 1 in the longitudinal direction from the first end face 11 to the second end face 12 and open at the first seal 21 and the second seal 22. Raw water is supplied to the plurality of filtration cells 14. The water collection hole 16 opens at the first seal 21, extends longitudinally from the first end surface 11, and closes at the second seal 22. The water collection hole 16 collects purified water.

[0122] The communicating flow path portion extends in a direction perpendicular to the longitudinal direction (horizontal in the above example) from an outer surface 13 connecting the first end face 11 and the second end face 12, avoiding the plurality of filtration cells 14. The communicating flow path portion communicates with a water collection hole 16. When viewed parallel to the longitudinal direction (in a plan view in the above example), the water collection hole 16 is located in the center of the first end face 11. The cross section perpendicular to the longitudinal direction of the flow path of the communicating flow path constituting the communicating flow path portion is slit-shaped and long in the longitudinal direction.

[0123] The communicating flow path section includes a first vertical flow path, a horizontal flow path, and a second vertical flow path. The first vertical flow path extends linearly from the outer surface 13 in a vertical direction perpendicular to the longitudinal direction (Y direction in the above example) and directly communicates with the water collection holes 16. The horizontal flow path extends linearly from the outer surface 13 in a horizontal direction perpendicular to the vertical direction (X direction in the above example) and directly communicates with the water collection holes 16. The second vertical flow path is spaced apart from the water collection holes 16 in the horizontal direction and extends linearly from the outer surface 13 in the vertical direction and directly communicates with the horizontal flow path. In this way, by communicating the second vertical flow path with the water collection holes 16 via the horizontal flow path, the flow rate of backwash water supplied to the region where the second vertical flow path is located (i.e., the region away from the water collection holes 16) can be increased.

[0124] Furthermore, when viewed parallel to the longitudinal direction (in the above example, in a plan view), the width of the horizontal flow path in a direction perpendicular to the horizontal flow path is larger than the width of the second vertical flow path in the horizontal direction. This reduces the pressure loss of the backwash water supplied to the second vertical flow path via the horizontal flow path. As a result, the flow rate of the backwash water supplied to the region where the second vertical flow path is located (i.e., the region away from the water collection hole 16) can be further increased. Therefore, in the filtration cells 14 located near the water collection cells 15 overlapping with the second vertical flow path, deposits accumulated on the inner surfaces of the filtration cells 14 can be more effectively removed during backwashing.

[0125] As described above, in the communication flow path section, it is preferable that the horizontal flow paths extend parallel to the horizontal direction (X direction in the above example). This allows the backwash water to be supplied approximately evenly to the multiple second vertical flow paths located on both sides of the horizontal flow path in the width direction (the (+Y) side and the (-Y) side in the above example). As a result, the uniformity of removal of deposits from the multiple filtration cells 14 can be improved.

[0126] As described above, in the communicating flow path section, it is preferable that only one horizontal flow path is provided on each side of the water collection hole 16 in the horizontal direction (X direction in the above example). This increases the flow rate of backwash water supplied to the region where the second vertical flow path is located (i.e., the region away from the water collection hole 16), while simplifying the structure of the water purification membrane structure 10.

[0127] As described above, in the communicating flow path section, when viewed parallel to the longitudinal direction (in the above example, when viewed from above), the flow path width of the horizontal flow path in the direction perpendicular to the horizontal flow path is preferably at least twice the flow path width of the second vertical flow path in the horizontal direction. This makes it possible to suitably reduce the pressure loss of the backwash water supplied to the second vertical flow path via the horizontal flow path and further increase the flow rate of the backwash water supplied to the region where the second vertical flow path is located (i.e., the region away from the water collection hole 16).

[0128] In the water purification membrane assembly 4, the flow path width of the horizontal flow path 173 in the central communicating flow path section 17 may be equal to or less than the flow path width of the second vertical flow path 172. Furthermore, the central communicating flow path section 17 of the water purification membrane structure 10 may be omitted as described above, and another communicating flow path section may be provided. In either case, by accommodating the water purification membrane structure 10 inside the housing main body 41, it is possible to prevent the water purification membrane structure 10 from being damaged by the pressure of the backwash water during backwashing of the water purification membrane structure 10.

[0129] Specifically, the water purification membrane assembly 4, which produces purified water from raw water, comprises a columnar water purification membrane structure 10 extending in the longitudinal direction (the Z direction in the above example) and a housing body 41. The housing body 41 accommodates the water purification membrane structure 10 so that the one longitudinal side and the other longitudinal side (the (+Z) side and the (-Z) side in the above example) of the water purification membrane structure 10 are the upper and lower sides, respectively. The housing body 41 is placed in raw water 91. The water purification membrane structure 10 comprises a columnar porous body 1 extending in the longitudinal direction, a water-impermeable first seal 21, and a water-impermeable second seal 22. The first seal 21 covers a first end face 11, which is the one longitudinal end face of the porous body 1. The second seal 22 covers a second end face 12, which is the other longitudinal end face of the porous body 1.

[0130] The porous body 1 includes a plurality of filtration cells 14, water collection holes 16, and a communication flow path portion (in the above example, a central communication flow path portion 17). The plurality of filtration cells 14 penetrate the porous body 1 in the longitudinal direction from the first end face 11 to the second end face 12, and open at the first seal 21 and the second seal 22. Raw water is supplied to the plurality of filtration cells 14. The water collection holes 16 open at the first seal 21, extend in the longitudinal direction from the first end face 11, and close at the second seal 22. Purified water is collected in the water collection holes 16. The communication flow path portion extends from the outer surface 13 connecting the first end face 11 and the second end face 12 in a direction perpendicular to the longitudinal direction (horizontal in the above example), avoiding the plurality of filtration cells 14. The communication flow path portion communicates with the water collection holes 16. When viewed parallel to the longitudinal direction (in the above example, when viewed from above), the water collection hole 16 is located at the center of the first end face 11. The cross sections perpendicular to the longitudinal direction of the communicating flow paths that make up the communicating flow path portion (in the above example, the flow path cross sections of the first vertical flow path 171, the second vertical flow path 172, and the horizontal flow path 173) are slit-shaped and long in the longitudinal direction.

[0131] The housing body 41 is cylindrical and covers the outer surface 13 of the water purification membrane structure 10. Raw water 91 flows into the housing body 41 through an upper opening 411 and a lower opening 412 of the housing body 41 and is supplied to the multiple filtration cells 14 of the water purification membrane structure 10. By covering the outer surface 13 of the water purification membrane structure 10 with the housing body 41 in this way, it is not necessary to cover the outer surface 13 of the porous body 1 with a seal such as glass. This prevents the seal from being damaged by the pressure of the backwash water during backwashing of the water purification membrane structure 10. This also simplifies the manufacture of the water purification membrane structure 10. Furthermore, because the seal, which has relatively low strength, is omitted, the water purification membrane structure 10 is easier to handle.

[0132] The water purification membrane structure 10 and the water purification membrane assembly 4 described above can be modified in various ways.

[0133] For example, in the central communicating channel section 17, the channel width of the horizontal channel 173 may be less than twice the channel width of the second vertical channel 172. Moreover, the horizontal channel 173 may extend in a direction inclined with respect to the X direction. Furthermore, the number of horizontal channels 173 provided on each of the (-X) side and the (+X) side of the water collection hole 16 may be two or more.

[0134] The length of the central communicating channel section 17 in the Z direction may be less than 3% of the total length of the porous body 1 in the Z direction.

[0135] In the water purification membrane structure 10, instead of or in addition to the central communicating flow path section 17, another communicating flow path section having a structure substantially similar to that of the central communicating flow path section 17 may be provided in the porous body 1 at a position different from that of the central communicating flow path section 17 in the longitudinal direction.

[0136] In the porous body 1, the plurality of water collecting cells 15 do not necessarily need to be provided, and may be omitted.

[0137] The water purification membrane assembly 4 does not necessarily have to be used in the filtration device 5 illustrated in Fig. 1, but may be used in various devices that produce purified water from raw water. For example, the water purification membrane assembly 4 does not necessarily have to be installed in raw water 91 stored in a raw water reservoir 81, but may be installed and used on land.

[0138] The water purification membrane structure 10 does not necessarily need to be housed in the housing body 41 shown in Fig. 1 when used, but may be housed in housing bodies of various shapes and structures when used. Alternatively, the water purification membrane structure 10 may be used without being housed in a housing body.

[0139] The configurations in the above-described embodiment and each modification may be combined as appropriate as long as they are not mutually contradictory. [Industrial Applicability]

[0140] The present invention can be used in a variety of devices for producing purified water from raw water. [Explanation of symbols]

[0141] 1 Porous materials 4. Water purification membrane assembly 10 Water purification membrane structure 11 First end surface 12 Second end face 13 External surface 14 Filtration Cell 15 collection cells 16 Water collection hole 17 Central connecting passage 21 First Seal 22 Second Seal 41 Housing body 91 Raw water 92 Purified Water 171 1st longitudinal channel 172 2nd longitudinal channel 173 Cross flow path 411 Upper opening 412 Lower opening

Claims

1. A water purification membrane structure that produces purified water from raw water, A columnar porous body extending in the longitudinal direction; a water-impermeable first seal covering a first end surface, which is an end surface on one side in the longitudinal direction of the porous body; a water-impermeable second seal covering a second end surface, which is the other end surface of the porous body in the longitudinal direction; Equipped with The porous body is a plurality of filtration cells that penetrate the porous body in the longitudinal direction from the first end surface to the second end surface, open at the first seal and the second seal, and receive raw water; a water collection hole that opens at the first seal, extends in the longitudinal direction from the first end surface, and closes at the second seal, and through which purified water is collected; a central communication flow path portion that extends from an outer surface connecting the first end surface and the second end surface in a direction perpendicular to the longitudinal direction while avoiding the plurality of filtration cells and that communicates with the water collection hole; Equipped with the water collection hole is located in the center of the first end surface when viewed parallel to the longitudinal direction, the central communicating flow path portion is located at a position spaced apart from the first end face in the longitudinal direction by at least one-third of the entire length of the porous body, and at a position spaced apart from the second end face in the longitudinal direction by at least one-third of the entire length of the porous body, The water purification membrane structure has a cross section perpendicular to the longitudinal direction of the communicating flow passage constituting the central communicating flow passage portion, the cross section being shaped like a slit that is long in the longitudinal direction.

2. The water purification membrane structure according to claim 1, The porous body further includes a plurality of water collection cells each extending in the longitudinal direction, closed at the first seal and the second seal, and in which purified water is collected; The central communication flow passage portion communicates with the plurality of water collection cells.

3. The water purification membrane structure according to claim 1 or 2, A water purification membrane structure in which no communicating flow path portion extending from the outer surface in a direction perpendicular to the longitudinal direction and communicating with the water collection hole is provided at the other longitudinal end of the porous body.

4. The water purification membrane structure according to claim 1 or 2, The water purification membrane structure, wherein the length of the central communicating channel portion in the longitudinal direction is 3% or more of the total length of the porous body in the longitudinal direction.

5. The water purification membrane structure according to claim 1 or 2, The central communicating flow path portion is a first vertical flow path extending linearly from the outer surface in a vertical direction perpendicular to the longitudinal direction and directly communicating with the water collecting hole; a horizontal flow path extending linearly from the outer surface along a horizontal direction perpendicular to the vertical direction and directly communicating with the water collection hole; a second vertical flow path that is spaced apart from the water collecting hole in the horizontal direction, extends linearly from the outer surface in the vertical direction, and directly communicates with the horizontal flow path; Equipped with When viewed parallel to the longitudinal direction, the width of the horizontal flow path in a direction perpendicular to the horizontal flow path is larger than the width of the second vertical flow path in the horizontal direction.

6. A water purification membrane assembly for producing purified water from raw water, The water purification membrane structure according to claim 1 or 2, a housing body that houses the water purification membrane structure and is placed in raw water so that the one side and the other side in the longitudinal direction of the water purification membrane structure are upper and lower sides, respectively; Equipped with The housing body is cylindrical and covers the outer surface of the water purification membrane structure, The water purification membrane assembly is configured such that raw water flows into the housing body through an upper opening and a lower opening of the housing body and is supplied to the plurality of filtration cells of the water purification membrane structure.

7. A water purification membrane structure that produces purified water from raw water, A columnar porous body extending in the longitudinal direction; a water-impermeable first seal covering a first end surface, which is an end surface on one side in the longitudinal direction of the porous body; a water-impermeable second seal covering a second end surface, which is the other end surface of the porous body in the longitudinal direction; Equipped with The porous body is a plurality of filtration cells that penetrate the porous body in the longitudinal direction from the first end surface to the second end surface, open at the first seal and the second seal, and receive raw water; a water collection hole that opens at the first seal, extends in the longitudinal direction from the first end surface, and closes at the second seal, and through which purified water is collected; a communication flow path portion that extends from an outer surface connecting the first end surface and the second end surface in a direction perpendicular to the longitudinal direction while avoiding the plurality of filtration cells and that communicates with the water collection hole; Equipped with the water collection hole is located in the center of the first end surface when viewed parallel to the longitudinal direction, a cross section perpendicular to a longitudinal direction of the communication flow path constituting the communication flow path portion has a slit shape that is long in the longitudinal direction, The communication flow path portion is a first vertical flow path extending linearly from the outer surface in a vertical direction perpendicular to the longitudinal direction and directly communicating with the water collecting hole; a horizontal flow path extending linearly from the outer surface along a horizontal direction perpendicular to the vertical direction and directly communicating with the water collection hole; a second vertical flow path that is spaced apart from the water collecting hole in the horizontal direction, extends linearly from the outer surface in the vertical direction, and directly communicates with the horizontal flow path; Equipped with When viewed parallel to the longitudinal direction, the width of the horizontal flow path in a direction perpendicular to the horizontal flow path is larger than the width of the second vertical flow path in the horizontal direction.

8. The water purification membrane structure according to claim 7, The horizontal flow passage extends parallel to the horizontal direction.

9. The water purification membrane structure according to claim 7 or 8, The water purification membrane structure has only one lateral flow path provided on each side of the water collection hole in the lateral direction.

10. The water purification membrane structure according to claim 7 or 8, When viewed parallel to the longitudinal direction, the width of the horizontal flow path in a direction perpendicular to the horizontal flow path is at least twice the width of the second vertical flow path in the horizontal direction.

11. A water purification membrane assembly for producing purified water from raw water, a columnar water purification membrane structure extending in the longitudinal direction; a housing body that houses the water purification membrane structure and is placed in raw water so that one side and the other side in the longitudinal direction of the water purification membrane structure are upper and lower sides, respectively; Equipped with The water purification membrane structure is A columnar porous body extending in the longitudinal direction; a water-impermeable first seal covering a first end surface, which is an end surface on one side in the longitudinal direction of the porous body; a water-impermeable second seal covering a second end surface of the porous body, the second end surface being the other end surface in the longitudinal direction; Equipped with The porous body is a plurality of filtration cells that penetrate the porous body in the longitudinal direction from the first end surface to the second end surface, open at the first seal and the second seal, and receive raw water; a water collection hole that opens at the first seal, extends in the longitudinal direction from the first end surface, and closes at the second seal, and through which purified water is collected; a communication flow path portion that extends from an outer surface connecting the first end surface and the second end surface in a direction perpendicular to the longitudinal direction while avoiding the plurality of filtration cells and that communicates with the water collection hole; Equipped with the water collection hole is located in the center of the first end surface when viewed parallel to the longitudinal direction, a cross section perpendicular to a longitudinal direction of the communication flow path constituting the communication flow path portion has a slit shape that is long in the longitudinal direction, The housing body is cylindrical and covers the outer surface of the water purification membrane structure, The water purification membrane assembly is configured such that raw water flows into the housing body through an upper opening and a lower opening of the housing body and is supplied to the plurality of filtration cells of the water purification membrane structure.

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