Method of manufacturing pure water membrane structure

Abstract

To suitably form a slit type communication flow channel.SOLUTION: A process of forming a communication flow channel part in a porous body using a cutting tool comprises: a process (Step S21) of preparing a cutting tool which is belt-like extending in a tool length direction and has a plurality of saw teeth at tips; a process (Step S22) of bringing the tips of the cutting tool into contact with an outer side face of the porous body and arranging the cutting tool such that a tool width direction perpendicular to the tool length direction is parallel with the length direction of the porous body; and a process (Step S23) of forming the communication flow channel by cutting the porous body inward from the outer side face while moving the cutting tool reciprocally in parallel with the length direction. Consequently, the communication flow channel part can be suitably formed.SELECTED DRAWING: Figure 9B

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a water purification membrane structure 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 that 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 penetrates the multiple water collection cells from the outer surface of the porous body and communicates with the water collection hole.

[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. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-56381 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, when providing a water collection slit in a porous body as in Patent Document 1, it is necessary to perform cutting or the like from the outer surface side of the base material of the porous body, which has water collection cells and water collection holes etc. formed in advance, to form slit-shaped holes that communicate with the water collection cells and water collection holes. However, because the communication flow paths such as the water collection slits are very narrow and deep, there are not many methods that can be suitably used for the above-mentioned cutting work.

[0007] For example, if cutting is performed using an electric drill, the deep depth of the communicating flow passages may cause the axial vibration of the thin-diameter drill during rotation, resulting in a slit width that is larger than desired. Ultrasonic cutting is also difficult to use due to the deep depth of the communicating flow passages. The same is true for laser cutting and water jet cutting. Furthermore, manual cutting using a single-edged diamond electroplated file or the like may result in a wider-than-desired width for the communicating flow passages.

[0008] The present invention has been made in view of the above-mentioned problems, and has as its object to suitably form a slit-shaped communication flow path. [Means for solving the problem]

[0009] A first aspect of the invention is a method for manufacturing a water purification membrane structure for producing purified water from raw water. The water purification membrane structure includes a columnar porous body extending in the longitudinal direction. The porous body includes a plurality of filtration cells that penetrate the porous body in the longitudinal direction from a first end face, which is an end face on one side of the longitudinal direction of the porous body, to a second end face, which is an end face on the other side of the longitudinal direction, and that receive raw water; a water collection hole that extends in the longitudinal direction from the first end face and collects purified water; and a communication flow path portion 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 that 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 of the communication flow path that constitutes the communication flow path portion, perpendicular to the longitudinal direction of the flow path, is slit-shaped and long in the longitudinal direction. The method for manufacturing the water purification membrane structure includes the steps of: a) preparing the porous body having the plurality of filtration cells and the water collection holes and before the communicating flow passages are formed, and b) forming the communicating flow passages in the porous body using a cutting tool. The step b) includes the steps of: c) preparing the cutting tool in a strip shape extending in the jig longitudinal direction and having a plurality of sawtooth edges at its tip, d) contacting the tip of the cutting tool with the outer surface of the porous body and positioning the cutting tool so that the jig width direction, which is perpendicular to the jig longitudinal direction, is parallel to the longitudinal direction, and e) cutting the porous body from the outer surface toward the interior of the porous body while reciprocating the cutting tool parallel to the longitudinal direction, to form the communicating flow passages.

[0010] The invention of aspect 2 is a manufacturing method of a water purification membrane structure of aspect 1, in which in step e), a protective jig that is larger than the cutting jig in the longitudinal direction is inserted from the outer surface of the communicating flow path that is being formed by the cutting jig, and is positioned between the cutting jig and the inner surface of the communicating flow path.

[0011] The invention of aspect 3 is a method for manufacturing a water purification membrane structure of aspect 1 or 2, in which the step e) involves cutting the porous body using the cutting jig and removing chips from within the communicating flow path during its formation.

[0012] The invention of aspect 4 is a method for manufacturing a water purification membrane structure of aspect 1 or 2 (or any one of aspects 1 to 3), in which the width of the communicating flow path formed in step e) in the flow path width direction perpendicular to the flow path longitudinal direction is less than 2 mm.

[0013] The invention of aspect 5 is a method for manufacturing a water purification membrane structure of aspect 1 or 2 (or any one of aspects 1 to 4), in which the depth of the communicating flow path formed in step e) from the outer surface is 30 mm or more.

[0014] The invention of aspect 6 is a method for manufacturing a water purification membrane structure of aspect 1 or 2 (or any one of aspects 1 to 5), wherein in step e), the thickness of the portion penetrated by cutting with the cutting jig is 0.65 mm or more.

[0015] A seventh aspect of the invention is the method for manufacturing a water purification membrane structure according to the first or second aspect (or any one of the first to sixth aspects), wherein the number of the plurality of sawtooth members is three or more. [Effects of the Invention]

[0016] In the present invention, a slit-shaped communication flow path can be suitably formed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a front view of a water purification membrane structure according to one embodiment. [Figure 2] FIG. 2 is a plan view of the water purification membrane structure. [Figure 3] FIG. 2 is a bottom view of the water purification membrane structure. [Figure 4] FIG. 2 is a cross-sectional 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 longitudinal 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 9A] FIG. 1 is a diagram showing the flow of cutting processing. [Figure 9B] FIG. 1 is a diagram showing the flow of cutting processing. [Figure 10] FIG. [Figure 11] FIG. 2 is an enlarged plan view showing a tip portion of the cutting jig. [Figure 12] FIG. [Figure 13] FIG. 10 is a perspective view showing a portion near a first vertical flow path during processing. [Figure 14] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 is a front view showing an example of a water purification membrane structure 10 manufactured by a manufacturing method according to one embodiment of the present invention. FIG. 2 is a plan view of the water purification membrane structure 10 seen from above. FIG. 3 is a bottom view of the water purification membrane structure 10 seen from below. FIG. 4 is a cross-sectional view of the water purification membrane structure 10 taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view of the water purification membrane structure 10 taken along line VV in FIG. 1. FIG. 6 is a cross-sectional view of the water purification membrane structure 10 taken along line VI-VI in FIG. 1. FIG. 7 is a longitudinal 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. 2. The X, Y, and Z directions in FIGS. 1 to 8 are perpendicular to each other, and the Z direction is parallel to the vertical direction. When the water purification membrane structure 10 is actually used, it is not necessary to arrange the water purification membrane structure 10 so that the Z direction is parallel to the up-down direction.

[0019] 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. 1. In the following description, the direction parallel to the central axis J1 (i.e., the vertical direction in FIG. 1) 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.

[0020] 1 to 8, 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.

[0021] 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. 1). 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. 1). 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.

[0022] 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.

[0023] The first seal 21 is a water-impermeable thin film provided on the first end surface 11 of the porous body 1. The first seal 21 covers substantially the entire first end surface 11, except for 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 surface 12 of the porous body 1. The second seal 22 covers substantially the entire second end surface 12, except for 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. In this embodiment, no seal is provided on the outer surface 13 of the porous body 1, and the outer surface 13 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. The outer surface 13 of the porous body 1 may be covered with a seal made of glass or the like.

[0024] 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 flow path portion 17, and end flow path portions 18. In Fig. 5, 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 flow path portion 17, and end flow path portions 18 by partition walls that are part of the porous body 1.

[0025] 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.

[0026] 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, or the like. In the examples shown in FIGS. 2 to 6, 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. 2 to 6, 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 2 to 6, 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 2 to 6, 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.

[0034] 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.

[0035] 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 2 to 6, 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.

[0036] 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."

[0037] 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.

[0038] As shown in FIG. 4, 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. 4, 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. 5, 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.

[0039] 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. 4, 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 six of these 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.

[0040] A cross section perpendicular to the longitudinal direction of each first vertical flow path 171 is shaped like a slit that is 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."

[0041] 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.

[0042] Each first vertical flow path 171 overlaps in plan view with a plurality of (seven in the example shown in FIG. 4 ) 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. 4 , 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.

[0043] 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. 4, 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.

[0044] 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. 4, 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 area where the water collection hole 16 is located in the Y direction.

[0045] A cross section of each horizontal flow path 173 perpendicular to the longitudinal direction of the flow path is shaped like a slit 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."

[0046] 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.

[0047] Each horizontal flow path 173 overlaps with a plurality of water collecting cells 15 (six in the example shown in FIG. 4 ) 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. 4 , 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. 4 , 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.

[0048] 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.

[0049] 4, 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.

[0050] 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.

[0051] In the example shown in FIG. 4 , 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] A cross section perpendicular to the longitudinal direction of each second vertical flow path 172 is shaped like a slit that is 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."

[0056] 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.

[0057] 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. 4) 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. 4, 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 path 172 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.

[0058] 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. 4, 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 (e.g., 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.

[0059] 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 in the X direction. In the example shown in Fig. 4, 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.

[0060] 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. 4, 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.

[0061] A plurality of filtration cells 14 may also be arranged in a region on the (+X) side of the second vertical flow path 172 that is located furthest to the (+X) side among the plurality of second vertical flow paths 172. In the example shown in Fig. 4, 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.

[0062] The end flow path section 18 is provided at the end on the (+Z) side in the longitudinal direction of the porous body 1. 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.

[0063] As shown in Fig. 6, 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 channels include a first channel 181, a second channel 182, and a third channel 183. The channels extend in a direction perpendicular to the Z direction, avoiding the filtration cells 14 (i.e., without overlapping with the filtration cells 14 in plan view), and overlap with and directly communicate with the water collection cells 15 in plan view. In the example shown in Fig. 6, the channel widths of the first channel 181, the second channel 182, and the third channel 183 are drawn larger than they actually are.

[0064] In the end channel section 18 illustrated in Fig. 6, 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. 4. 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, but 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.

[0065] 6, 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 substantially 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.

[0066] 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.

[0067] 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.

[0068] 1, the end portion on the (-Z) side in the longitudinal direction of the porous body 1 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.

[0069] When purified water is produced in the water purification membrane structure 10, raw water is first supplied into each filtration cell 14 through the openings on the (+Z) and (-Z) sides of each filtration cell 14. The raw water supplied to each filtration cell 14 passes through the partition walls and flows into the water collection cells 15 surrounding each filtration cell 14. At this time, suspended solids and the like in the raw water are filtered out by the filtration layer that constitutes the inner surface of the filtration cell 14, and purified water, which is a liquid obtained by removing suspended solids and the like from the raw water, flows into the water collection cells 15. As described above, each water collection cell 15 is directly connected to the central communicating channel 17 and is indirectly connected to the water collection hole 16 via the central communicating channel 17.

[0070] 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 .

[0071] Next, a method for manufacturing the water purification membrane structure 10 will be described. When manufacturing the water purification membrane structure 10, first, the raw materials for the substrate of the porous body 1 are mixed and kneaded, and a precursor for the substrate having a monolith structure is formed by extrusion molding or the like. Next, the precursor is dried by a drying process such as hot air drying. Next, the dried precursor is cut from the outer surface toward the inside to form the slit-shaped central communicating channel portion 17 and end channel portions 18.

[0072] The precursor is then fired to form the base material of the porous body 1. Subsequently, the raw materials for the filtration layer are applied to the inner surfaces of the filtration cells 14 of the base material, and the raw materials for the first seal 21 and the second seal 22 are applied to the first end face 11 and the second end face 12 of the base material. The base material to which the raw materials have been applied is then fired to form the water purification membrane structure 10 described above.

[0073] Next, the above-mentioned cutting process for the precursor of the substrate will be described in detail. The cutting process for forming the first vertical flow path 171 of the central communicating flow path section 17 in the precursor of the substrate will be described below. Figures 9A and 9B are diagrams showing the flow of the cutting process. Figure 10 is a plan view showing a cutting jig 71 used in the cutting process. Figure 11 is an enlarged plan view showing the tip of the cutting jig 71 (i.e., the left end in Figure 10). Figure 12 is a perspective view showing a protective jig 72 used in the cutting process. Figure 13 is a perspective view showing a portion of the substrate near the first vertical flow path 171 in the middle of processing. Figure 14 is a plan view showing a removal jig 73.

[0074] When cutting the precursor of the substrate, first, a precursor having a monolith structure provided with the filtration cells 14 and the water collection holes 16 is prepared through the drying process described above (step S11). This precursor is the porous body 1 before the central communicating channel portion 17 is formed, and hereinafter will also be referred to simply as the "porous body 1." Next, cutting is performed on the porous body 1 using a cutting jig 71 shown in Figures 10 and 11 to form first vertical channels 171 (i.e., communicating channels) that are part of the central communicating channel portion 17 (step S12).

[0075] The cutting jig 71 is a strip-shaped member in a plan view that extends substantially linearly in the jig longitudinal direction (i.e., the left-right direction in FIG. 10). The cutting jig 71 is a thin plate-shaped member whose length in the jig longitudinal direction is greater than its width in the jig width direction (i.e., the up-down direction in FIG. 10) that is perpendicular to the jig longitudinal direction. The thickness of the cutting jig 71 in its thickness direction (i.e., the direction perpendicular to the paper surface in FIG. 10) is smaller than its length in the jig longitudinal direction and its width in the jig width direction. The cutting jig 71 is made of, for example, metal, and in this embodiment, is formed from spring steel.

[0076] The length of the cutting jig 71 in the jig longitudinal direction (hereinafter simply referred to as "length") is, for example, 150 mm to 350 mm. From the viewpoint of increasing the cutting depth from the outer surface of the precursor (i.e., the surface intended to become the outer surface 13 of the porous body 1), the length of the cutting jig 71 is preferably 200 mm or more. In this embodiment, the length of the cutting jig 71 is 250 mm. The width of the cutting jig 71 in the width direction (hereinafter simply referred to as "width") is, for example, 2 mm to 10 mm. From the viewpoint of improving the efficiency of the cutting process, the width of the cutting jig 71 is preferably 5 mm or more. In this embodiment, the width of the cutting jig 71 is 5.1 mm. The thickness of the cutting jig 71 in the thickness direction (hereinafter simply referred to as "thickness") is, for example, 0.5 mm to 1.5 mm. In consideration of the flow path width of the slit-shaped communicating flow path formed by the cutting process, the thickness of the cutting jig 71 is preferably 1 mm or less. In this embodiment, the thickness of the cutting jig 71 is 0.6 mm.

[0077] The tip of the cutting jig 71 is provided with a plurality of sawtooths 711 aligned in the jig width direction. In the example shown in FIG. 11, three sawtooths 711 positioned at approximately the same position in the jig longitudinal direction are aligned in the jig width direction. The three sawtooths 711 have approximately the same shape. In a plan view, each sawtooth 711 has a substantially right-angled triangular shape with its acute apex located at the tip of the cutting jig 71. The number of sawtooths 711 provided at the tip of the cutting jig 71 may be appropriately changed within a range of two or more. The length of each sawtooth 711 in the jig longitudinal direction is, for example, 2 mm to 5 mm. The width of each sawtooth 711 in the jig width direction is, for example, 1 mm to 3 mm. The angle of the tip of each sawtooth 711 is, for example, 15° to 45°. In this embodiment, the length and width of each sawtooth 711 are 3.6 mm and 1.7 mm, respectively. The angle of the tip of each sawtooth 711 is 25°.

[0078] In the above-mentioned step S12, first, the cutting jig 71 illustrated in Figures 10 and 11 is prepared (step S21). Next, the tip of the cutting jig 71 is brought into contact with the outer surface 13 of the porous body 1, and the cutting jig 71 is positioned so that the jig width direction is parallel to the central axis J1 of the porous body 1 (i.e., parallel to the Z direction, which is the longitudinal direction of the porous body 1) (step S22). In step S22, for example, the porous body 1 is placed so that the central axis J1 of the porous body 1 faces horizontally, and the tip of the cutting jig 71 is brought into contact with the upper end of the porous body 1 in this state.

[0079] Thereafter, the cutting jig 71 is moved back and forth parallel to the Z direction while cutting is performed from the outer surface 13 toward the inside (e.g., downward) of the porous body 1, thereby forming a first vertical flow path 171 (step S23). As described above, the first vertical flow path 171 penetrates the plurality of water collection cells 15 (see FIG. 4) lined up in the Y direction and communicates with the water collection hole 16. Therefore, in step S23, the cutting jig 71 penetrates the partition walls around the plurality of water collection cells 15, and finally penetrates the partition wall between the water collection hole 16 and the water collection cell 15 closest to the water collection hole 16, thereby forming the first vertical flow path 171.

[0080] In step S23, when the depth of the slit-shaped cut hole extending in the Z direction formed by the cutting jig 71 reaches a certain depth (for example, 10 mm to 20 mm), the cutting jig 71 is temporarily removed from the cut hole. For example, when the cut hole (i.e., the first vertical flow path 171 in the process of being formed) that started to be formed from the outer surface 13 of the porous body 1 penetrates the partition wall of the water collecting cell 15 located closest to the outer surface 13 and the tip of the cutting jig 71 reaches the inside of the water collecting cell 15, the cutting jig 71 is removed from the cut hole.

[0081] Then, as shown in FIG. 13, the protective jig 72 shown in FIG. 12 is inserted into the cut hole 70 from the outer surface 13 of the porous body 1. Note that in FIG. 13, the width of the cut hole 70 in the X direction is drawn larger than it actually is. Also, in FIG. 13, the filtration cells 14 and the water collection cells 15 are not shown. The protective jig 72 shown in FIG. 12 is obtained by bending a relatively hard, approximately flat member into an approximately V-shape and further bending the upper end of the V-shaped portion outward in the width direction. The length of the protective jig 72 in the Z direction is greater than the width of the cutting jig 71 in the jig width direction. The protective jig 72 is formed, for example, from a hard resin.

[0082] The protective jig 72 is inserted into the cut hole 70 (i.e., the first vertical flow path 171 in the process of being formed) from the outer surface 13 of the porous body 1 so that the lower end of the V-shaped portion faces the inside of the porous body 1. The protective jig 72 has a through hole 721 at the lower end of the V-shaped portion, into which the cutting jig 71 can be inserted. The through hole 721 is a slit-shaped hole that extends approximately linearly in the Z direction. When the protective jig 72 is inserted into the cut hole 70, the tip of the cutting jig 71 is inserted again into the cut hole 70 and then into the through hole 721 of the protective jig 72. The tip of the cutting jig 71 protrudes from the through hole 721 of the protective jig 72 to the (-Y) side (i.e., the side closer to the water collection hole 16). Then, cutting processing of the porous body 1 using the cutting jig 71 is resumed, and cutting is performed on the area behind the protective jig 72 (i.e., the side closer to the water collection hole 16).

[0083] The V-shaped portions of the protective jig 72 are disposed between the cutting jig 71 and the inner surface of the first vertical flow path 171 being formed on both sides in the thickness direction of the cutting jig 71 (i.e., the (+X) side and the (-X) side). In the following description, of the V-shaped portions of the protective jig 72, the portion located on one side in the thickness direction of the cutting jig 71 and the portion located on the other side in the thickness direction are also referred to as "protective plate portions 722." The V-shaped portions of the protective jig 72 are formed by connecting the lower edges of two protective plate portions 722 except for the through-holes 221. Each protective plate portion 722 is a substantially flat plate-shaped portion disposed between the cutting jig 71 and the inner surface of the first vertical flow path 171 being formed. The length in the Z direction of each protective plate portion 722 is greater than the width of the cutting jig 71 in the jig width direction (i.e., the Z direction).

[0084] In this way, by disposing the protective plate portion 722 between the cutting jig 71 and the inner surface of the first vertical flow path 171 in the process of being formed, the cutting jig 71 is prevented from coming into contact with the inner surface of the first vertical flow path 171 in the process of being formed and damaging the inner surface. Since the inner surface is part of the partition wall that constitutes the filtration cell 14 adjacent to the first vertical flow path 171, by using the protective jig 72, the filtration cell 14 is protected from the cutting jig 71 and damage to the filtration cell 14 is prevented.

[0085] In step S23, as the cutting process using the cutting jig 71 progresses, chips (i.e., swarf) generated by the cutting process accumulate inside the cut hole 70. Therefore, the porous body 1 having the cut hole 70 formed in the upper part is rotated 180° about the central axis J1 so that the opening of the cut hole 70 faces downward. Then, the chips are removed from the cut hole 70 that opens downward (i.e., the first vertical flow path 171 that is in the process of being formed).

[0086] The removal of chips from the cut hole 70 is performed using, for example, a removal jig 73 illustrated in FIG. 14. The removal jig 73 is a thin plate member that is approximately rectangular in plan view. The thickness of the removal jig 73 in the thickness direction (i.e., the direction perpendicular to the paper surface in FIG. 14) is, for example, approximately the same as the thickness of the cutting jig 71. When removing chips using the removal jig 73, the cutting jig 71 and the protective jig 72 are removed from the cut hole 70 (i.e., the first vertical flow path 171 being formed), and a corner of the removal jig 73 is inserted into the cut hole 70 from below. Then, the removal jig 73 is moved along the Z direction, causing the chips in the cut hole 70 to fall and be removed from the cut hole 70. In step S23, cutting of the porous body 1 with the cutting jig 71 and removal of chips in the cut hole 70 (i.e., the first vertical flow path 171 being formed) are alternately performed. This prevents chips from clogging the cut hole 70 and impeding cutting by the cutting jig 71.

[0087] In step S23, cutting of the porous body 1 with the cutting jig 71 and removal of chips in the cut hole 70 do not necessarily have to be performed alternately. For example, the porous body 1 may be fixed with the opening of the cut hole 70 facing downward, and the cutting jig 71 may be inserted into the cut hole 70 from below through the opening to perform the cutting process. In this case, the chips fall downward by gravity during the cutting process and are removed from the cut hole 70, so cutting of the porous body 1 with the cutting jig 71 and removal of chips in the cut hole 70 are performed in parallel.

[0088] The removal of chips by the removal jig 73 may be performed, for example, every time the cutting jig 71 penetrates a partition wall (hereinafter also referred to as a "cell partition wall") between two water collection cells 15 adjacent in the Y direction in FIG. 4. The thickness of the cell partition wall in the Y direction (i.e., the direction in which the holes 70 cut by the cutting jig 71 extend) is, for example, 0.65 mm. In step S23, by using the cutting jig 71 having multiple sawtooth edges 711, it is possible to relatively easily form a through hole even in a relatively thick portion of 0.65 mm. Furthermore, the thickness in the Y direction of the partition wall (hereinafter also referred to as a "water collection hole partition wall") between the water collection hole 16 and the water collection cell 15 closest to the water collection hole 16 among the multiple water collection cells 15 penetrated by the cutting jig 71 is, for example, 5 mm. In step S23, by using the cutting jig 71 having multiple sawtooth edges 711, it is possible to relatively easily form a through hole even in a portion that is even thicker, such as 5 mm.

[0089] The water collection hole partition wall is located at the deepest side of the cut hole 70 when forming the first vertical channel 171 (i.e., the position farthest from the outer surface 13 of the porous body 1 in the direction in which the cut hole 70 extends). In order to penetrate the water collection hole partition wall with the cutting jig 71 inserted from the outer surface 13 of the porous body 1, the length of the cutting jig 71 needs to be longer than the length of the first vertical channel 171 (i.e., the depth from the outer surface 13 in the channel longitudinal direction). Furthermore, as will be described later, the second vertical channel 172 and the horizontal channel 173 of the central communicating channel section 17 may also be formed by the cutting jig 71, and therefore the length of the cutting jig 71 needs to be longer than the lengths of these channels. Therefore, the length of the cutting jig 71 is preferably 30 mm or more, more preferably 65 mm or more, and even more preferably 80 mm or more.

[0090] The removal of the chips in step S23 does not necessarily have to be performed using the removal jig 73, but may be performed by various other methods. For example, the chips may be removed by blowing air into the cut hole 70 using a blower or the like. Furthermore, the removal of the chips does not necessarily have to be performed with the opening of the cut hole 70 facing downward, and the position of the porous body 1 when removing the chips may be determined appropriately.

[0091] In the manufacture of the water purification membrane structure 10, the second vertical channels 172 and the horizontal channels 173 of the central communicating channel section 17 are also formed. When forming the second vertical channels 172 and the horizontal channels 173 of the central communicating channel section 17, the above-described steps S21 to S23 may also be performed using, for example, the cutting jig 71. Note that, because the horizontal channels 173 have a relatively large channel width as described above, they can be formed relatively easily even when using a cutting jig other than the cutting jig 71 and / or a method other than steps S21 to S23. Note that when forming the first channels 181, the second channels 182, and the third channels 183 of the end channel section 18, the above-described steps S21 to S23 may also be performed using, for example, the cutting jig 71.

[0092] In forming the central communicating channel portion 17 described above, the second vertical channel 172 is formed after the horizontal channel 173 is formed. Note that the first vertical channel 171 may be formed before the horizontal channel 173 is formed, or may be formed after the horizontal channel 173 is formed.

[0093] Next, we will explain the results of measuring the cutting speed by changing the shape of the cutting jig. Table 1 shows the relationship between the shape of the cutting jig and the cutting speed.

[0094] [Table 1]

[0095] In Example 1, an operator manually performed cutting using the cutting jig 71 described above and measured the time required to form slit-shaped through holes in the water collection hole partition wall between the water collection cells 15 and the water collection holes 16. The processing time in Table 1 is the total time required to form six through holes in the water collection hole partition wall corresponding to the radially inner ends of the six first vertical flow paths 171 shown in Figure 4. The radial thickness of the water collection hole partition wall was 5 mm, and the length of each through hole in the Z direction (i.e., the longitudinal direction of the porous body 1) was 30 mm. The length and width of the cutting jig 71 in Example 1 were 250 mm and 5.1 mm, respectively. Three sawtooth teeth 711, each 3.6 mm long and 1.7 mm wide, were provided at the tip of the cutting jig 71, lined up in the jig width direction. The angle of the tip of each sawtooth tooth 711 was 25°. Unlike Comparative Examples 1 to 3 described below, cutting jig 71 of Example 1 does not have abrasive grains electroplated onto sawtooth 711. The processing time for Example 1 was 40 minutes. Table 1 also shows plan views of the tip portions of cutting jig 71 of Example 1 and the cutting jigs of Comparative Examples 1 to 3.

[0096] In Comparative Examples 1 to 3, grinding was performed in the same manner as in Example 1, except that the cutting jig was changed. The cutting jig of Comparative Example 1 had one cutting edge at its tip. The length and width of the cutting jig of Comparative Example 1 were 250 mm and 11 mm, respectively. The shape of the cutting edge of the cutting jig of Comparative Example 1 in plan view was a right-angled isosceles triangle with the right-angled apex located at the tip of the cutting jig. The length of the cutting edge in the jig longitudinal direction was 5.5 mm, and the width in the jig width direction was 11 mm. The angle of the tip of the cutting edge was 90°. Diamond abrasive grains were electroplated on the tip (i.e., the cutting edge) and side of the cutting jig of Comparative Example 1. The processing time of Comparative Example 1 was 90 minutes.

[0097] The cutting jig of Comparative Example 2 has one cutting edge at its tip. The length and width of the cutting jig of Comparative Example 2 are 250 mm and 5 mm, respectively. The shape of the cutting edge of the cutting jig of Comparative Example 2 in plan view is an isosceles triangle with the acute apex located at the tip of the cutting jig. The length of the cutting edge in the jig longitudinal direction is 10 mm, and the width in the jig width direction is 5 mm. The angle of the tip of the cutting edge is 27°. Diamond abrasive grains are electroplated on the tip (i.e., the cutting edge) of the cutting jig of Comparative Example 2. The processing time of Comparative Example 2 was 50 minutes.

[0098] The cutting jig of Comparative Example 3 is the same as that of Comparative Example 2, except that the cutting edge is omitted from the tip, and the tip edge is parallel to the jig width direction. The length and width of the cutting jig of Comparative Example 3 are 250 mm and 5 mm, respectively. The shape of the tip of the cutting jig of Comparative Example 2 is rectangular in plan view. The width of the tip in the jig width direction is 5 mm, and the angle corresponding to the angle of the tip of the cutting edge described above is 180°. Diamond abrasive grains are electroplated on the tip of the cutting jig of Comparative Example 3. The processing time of Comparative Example 3 was 90 minutes.

[0099] Comparing the processing time between Example 1 and Comparative Examples 1 to 3, by using a cutting jig 71 having a plurality of saw teeth 711 at the tip, as in Example 1, the processing time required for cutting can be shortened.

[0100] As described above, the water purification membrane structure 10 that produces purified water from raw water includes a columnar porous body 1 extending in the longitudinal direction. The porous body 1 includes a plurality of filtration cells 14, water collection holes 16, and a communicating flow path section (in the above example, the central communicating flow path section 17). The plurality of filtration cells 14 penetrate the porous body 1 in the longitudinal direction (in the above example, the Z direction) from a first end face 11, which is an end face on one side in the longitudinal direction of the porous body 1 (in the above example, the (+Z) side), to a second end face 12, which is an end face on the other side in the longitudinal direction (in the above example, the (-Z) side). Raw water is supplied to the plurality of filtration cells 14. The water collection holes 16 extend in the longitudinal direction from the first end face 11. Purified water is collected in the water collection holes 16.

[0101] The communicating flow path portion extends in a direction perpendicular to the longitudinal direction (horizontal 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 communicating flow path portion communicates with the water collection hole 16. The water collection hole 16 is located in the center of the first end face 11 when viewed parallel to the longitudinal direction (planar in the above example). The cross section perpendicular to the longitudinal direction of the communicating flow path constituting the communicating flow path portion (cross section of the first vertical flow path 171 in the above example) is slit-shaped and long in the longitudinal direction.

[0102] The manufacturing method of the water purification membrane structure 10 includes a step of preparing a porous body 1 having a plurality of filtration cells 14 and water collection holes 16 and before the formation of a communicating flow path portion (step S11), and a step of forming a communicating flow path portion in the porous body 1 using a cutting jig 71 (step S12).

[0103] Step S12 includes the steps of: preparing a strip-shaped cutting jig 71 extending in the jig longitudinal direction and having a plurality of sawtooth edges 711 at its tip (step S21); bringing the tip of the cutting jig 71 into contact with the outer surface 13 of the porous body 1 and positioning the cutting jig 71 so that the jig width direction perpendicular to the jig longitudinal direction is parallel to the longitudinal direction (step S22); and cutting the porous body 1 from the outer surface 13 toward the inside of the porous body 1 while reciprocating the cutting jig 71 parallel to the longitudinal direction to form a communicating flow path (step S23). This shortens the time required to form the communicating flow path portion, as described above, and enables the communicating flow path portion to be formed favorably.

[0104] As described above, in step S23, it is preferable that the protective jig 72, which is larger than the cutting jig 71 in the longitudinal direction, is inserted into the communicating flow path being formed by the cutting jig 71 (in the above example, the first vertical flow path 171) from the outer surface 13, and is disposed between the cutting jig 71 and the inner surface of the communicating flow path. This makes it possible to prevent the cutting jig 71 from contacting and damaging the partition wall of the filtration cell 14 adjacent to the first vertical flow path 171 being formed. In this way, by using the protective jig 72, the filtration cell 14 can be protected from the cutting jig 71, and damage to the filtration cell 14 during cutting can be prevented.

[0105] As described above, in step S23, it is preferable to cut the porous body 1 using the cutting jig 71 and remove chips from the communicating flow path (first vertical flow path 171 in the above example) that is being formed. This prevents chips from clogging the communicating flow path that is being formed and impeding the cutting process. As a result, the communicating flow path portion can be formed more efficiently.

[0106] Preferably, the width of the communicating flow passage formed in step S23 in the flow passage width direction perpendicular to the flow passage longitudinal direction (i.e., the flow passage width) is less than 2 mm. As described above, the above manufacturing method for the water purification membrane structure 10 using the cutting jig 71 can suitably form relatively narrow slit-shaped communicating flow passages that are difficult to form with an electric drill or the like. Therefore, this manufacturing method is particularly suitable for forming relatively narrow slit-shaped communicating flow passages with a flow passage width of less than 2 mm.

[0107] Preferably, the depth of the communicating flow passage formed in step S23 from the outer surface 13 is 30 mm or more. As described above, the manufacturing method for the water purification membrane structure 10 using the cutting jig 71 can suitably form slit-shaped communicating flow passages with a relatively deep cutting depth, which is difficult to form using an electric drill or the like. Therefore, this manufacturing method is particularly suitable for forming slit-shaped communicating flow passages with a relatively deep cutting depth of 30 mm or more.

[0108] Preferably, in step S23, the thickness of the portion (in the above example, the cell partition walls and the water collection hole partition walls) that is cut through by the cutting jig 71 is 0.65 mm or more. As described above, according to the above manufacturing method of the water purification membrane structure 10 using the cutting jig 71, cutting of a relatively thick portion can be performed in a relatively short time compared to the case where the cutting jigs of Comparative Examples 1 to 3 are used. Therefore, this manufacturing method is particularly suitable for cutting a relatively thick portion having a thickness of 0.65 mm or more to form a slit-shaped communicating flow path.

[0109] As described above, the number of saw teeth 711 is preferably 3 or more. This makes it possible to suitably shorten the time required to form the communicating flow path portion compared to when the cutting jigs of Comparative Examples 1 to 3 are used, as described above.

[0110] The above-described method for manufacturing the water purification membrane structure 10 can be modified in various ways.

[0111] For example, the number of saw teeth 711 of the cutting jig 71 may be two, or may be four or more.

[0112] The above-described manufacturing method for the water purification membrane structure 10 may be used to cut partition walls or the like having a thickness of less than 0.65 mm. The manufacturing method may also be used to form communicating channels having a depth of less than 30 mm from the outer surface 13. The manufacturing method may also be used to form communicating channels having a channel width of 2 mm or more.

[0113] In step S23, chips do not necessarily have to be removed, and the protective jig 72 does not necessarily have to be used in step S23.

[0114] In the central communicating channel section 17, the length in the Z direction of the channel cross section of the first vertical channel 171 may be less than 15 times the channel width of the first vertical channel 171, or may be greater than 240 times the channel width. The same applies to the second vertical channel 172.

[0115] 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.

[0116] In the porous body 1, the plurality of water collecting cells 15 do not necessarily need to be provided, and may be omitted.

[0117] 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]

[0118] The present invention can be used in the manufacture of various water purification membrane structures that produce purified water from raw water. [Explanation of symbols]

[0119] 1 Porous materials 10 Water purification membrane structure 11 First end surface 12 Second end face 13 External surface 14 Filtration Cell 16 Water collection hole 17 Central connecting passage 21 First Seal 22 Second Seal 70 Cutting hole 71 Cutting jig 72 Protective jig 73 Removal jig 171 1st longitudinal channel 172 2nd longitudinal channel 173 Cross flow path 711 Sawtooth S11~S12, S21~S23 steps

Claims

1. A method for manufacturing a water purification membrane structure for producing purified water from raw water, The water purification membrane structure includes a columnar porous body extending in a longitudinal direction, The porous body is a plurality of filtration cells that penetrate the porous body in the longitudinal direction from a first end face that is an end face on one side in the longitudinal direction of the porous body to a second end face that is an end face on the other side in the longitudinal direction and to which raw water is supplied; a water collection hole extending from the first end surface in the longitudinal direction 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 method for manufacturing the water purification membrane structure includes: a) preparing the porous body having the plurality of filtration cells and the water collection holes and before the communication flow path portion is formed; b) forming the communicating flow path portion in the porous body using a cutting jig; Equipped with The step b) comprises: c) preparing the cutting jig in a strip shape extending in the jig longitudinal direction and having a plurality of saw teeth at a tip end thereof; d) contacting the tip of the cutting jig with the outer surface of the porous body, and arranging the cutting jig so that the jig width direction perpendicular to the jig longitudinal direction is parallel to the longitudinal direction; e) cutting the porous body from the outer surface toward the inside of the porous body while reciprocating the cutting jig parallel to the longitudinal direction to form the communicating flow path; A method for manufacturing a water purification membrane structure comprising:

2. A method for producing the water purification membrane structure according to claim 1, In step e), a protective jig that is larger than the cutting jig in the longitudinal direction is inserted from the outer surface of the communicating flow path that is being formed by the cutting jig, and is placed between the cutting jig and the inner surface of the communicating flow path.

3. A method for producing a water purification membrane structure according to claim 1 or 2, In the step e), cutting of the porous body with the cutting jig and removal of chips from within the communicating flow path during formation are carried out.

4. A method for producing a water purification membrane structure according to claim 1 or 2, The method for manufacturing a water purification membrane structure, wherein the width of the communicating flow path formed in step e) in a flow path width direction perpendicular to the flow path longitudinal direction is less than 2 mm.

5. A method for producing a water purification membrane structure according to claim 1 or 2, The method for manufacturing a water purification membrane structure, wherein the communicating flow path formed in step e) has a depth from the outer surface of 30 mm or more.

6. A method for producing a water purification membrane structure according to claim 1 or 2, In the step e), the thickness of the portion cut through by the cutting jig is 0.65 mm or more.

7. A method for producing a water purification membrane structure according to claim 1 or 2, The method for manufacturing a water purification membrane structure, wherein the number of the plurality of sawtooths is three or more.

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