Filter plate unit and filter press device

Abstract

To inhibit damage of a diaphragm sheet.SOLUTION: A filter plate unit used in a filter press device includes a first filter plate, a second filter plate, and a diaphragm sheet 3. In the first filter plate, a first recessed part 21 and a peripheral edge part 23 enclosing the first recessed part 21 are provided on a major surface 20a. In the second filter plate, a second recessed part 21 facing the first recessed part 21 of the first filter plate and a peripheral edge part 23 enclosing the second recessed part 21 are provided on a major surface 20b. The diaphragm sheet 3 is disposed between the first filter plate and the second filter plate. In each filter plate, an inclined surface 212 connects the bottom surface 211 of the recessed part 21 with the peripheral edge part 23. The diaphragm sheet 3 has: a movable part 31 which is along the bottom surface 211 and the inclined surface 212 of the first recessed part 21 in the first filter plate; and a fixed part 33 fixed to the peripheral edge part 23 of the first filter plate. The inclined surface 212 of the second recessed part 21 in the second filter plate has a protruding part 216 to inhibit damage of the diaphragm sheet 3.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a filter plate unit and a filter press device.

Background Art

[0002] Conventionally, in order to perform solid-liquid separation, filter press devices that perform filtration (filtration and pressing) with pressure have been used in various fields. In a filter press device, in a plurality of filter plates arranged in the moving direction, a filtration chamber is formed between two adjacent filter plates. In each filtration chamber, filtration of the slurry is performed using a filter cloth, and then pressing of the slurry is performed using a diaphragm sheet.

[0003] In addition, FIG. 7 of Patent Document 1 shows a longitudinal sectional view of a filter plate to which a stock solution supply plate is attached. In the core plate, a recess is formed at the peripheral edge of the stock solution supply path, and the stock solution supply plate is fixed to the recess with screws. A part of the diaphragm is pressed against the core plate by the stock solution supply plate, and the part is deformed. Patent Document 2 discloses a diaphragm filter plate in which a metal filter medium with good peelability is directly stretched on a diaphragm. In FIG. 4 of Patent Document 2, the outer surface of the inclined portion between the filtration bed of the diaphragm provided with the metal filter medium and the peripheral portion which is the sealing surface has a curved shape.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the diaphragm sheet is usually formed of rubber or the like, and cracks occur and progress by repeating the pressing process. When such damage to the diaphragm sheet occurs, the filtrate leaks, so it is necessary to periodically replace the diaphragm sheet, increasing the running cost in the use of the filter press device. Therefore, a method for suppressing damage to the diaphragm sheet is required.

[0006] The present invention has been made in view of the above problems, and an object thereof is to suppress damage to the diaphragm sheet.

Means for Solving the Problems

[0007] Aspect 1 of the present invention is a filter plate unit used in a filter press device, including a first filter plate provided with a first recess and a peripheral edge surrounding the first recess on a main surface, a second recess facing the first recess of the first filter plate, and a second filter plate provided with a peripheral edge surrounding the second recess on the main surface, and a diaphragm sheet disposed between the first filter plate and the second filter plate. In the first filter plate, the bottom surface of the first recess and the peripheral edge are connected by an inclined surface. In the second filter plate, the bottom surface of the second recess and the peripheral edge are connected by an inclined surface. The diaphragm sheet has a movable portion along the bottom surface and the inclined surface of the first recess in the first filter plate, and a fixed portion fixed to the peripheral edge of the first filter plate. In the filter press device, when a close contact state in which the first filter plate and the second filter plate are in close contact is formed, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate. When the slurry is pressed, a pressing fluid is supplied between the diaphragm sheet and the first recess of the first filter plate, so that the movable portion deforms so as to bulge toward the second filter plate side, and the inclined surface of the second recess in the second filter plate has a convex portion.

[0008] Aspect 2 of the present invention is the filter plate unit of Aspect 1, wherein the convex portion is provided over the entire circumference on the inclined surface of the second filter plate.

[0009] Aspect 3 of the present invention is the filter plate unit of Aspect 1 (which may be Aspect 1 or 2). In a cross-section perpendicular to the edge at the boundary between the inclined surface and the peripheral portion of the second filter plate, the convex portion is provided by the inclined surface being curved or bent so as to be convex toward the filtration chamber.

[0010] Aspect 4 of the present invention is the filter plate unit of Aspect 1 (which may be any one of Aspects 1 to 3). The movable portion of the diaphragm sheet has a bottom portion facing the bottom surface of the first recess in the first filter plate and an inclined portion facing the inclined surface. In a state where the diaphragm sheet is removed from the first filter plate, the inner surface of the inclined portion of the diaphragm sheet has a convex portion.

[0011] Aspect 5 of the present invention is the filter plate unit of Aspect 1 (which may be any one of Aspects 1 to 4). The movable portion of the diaphragm sheet has a bottom portion facing the bottom surface of the first recess in the first filter plate. A plurality of protrusions are provided on the surface on the second filter plate side at the bottom portion. When attention is paid to the direction perpendicular to the main surface of the first filter plate in the close contact state, with the surface on the first filter plate side of the bottom portion as a reference, the height of the plurality of protrusions is T2 [mm], the distance from the surface on the first filter plate side of the fixing portion to the fixing portion is L1 [mm], the thickness of the fixing portion is T1 [mm], and the distance from the surface on the second filter plate side of the fixing portion to the bottom surface of the second recess of the second filter plate is L2 [mm]. 10 [mm] < T1 + L1 + L2 - T2 < 40 [mm] is satisfied.

[0012] Aspect 6 of the present invention is a filter plate unit used in a filter press device, comprising a first filter plate provided with a first recess and a peripheral edge surrounding the first recess on a main surface, a second recess facing the first recess of the first filter plate, and a second filter plate provided with a peripheral edge surrounding the second recess on a main surface, and a diaphragm sheet disposed between the first filter plate and the second filter plate. In the first filter plate, a first boss portion protruding from the bottom surface of the first recess is provided, and the end surface of the first boss portion and the bottom surface of the first recess are connected by a boss inclined surface, and the bottom surface of the first recess and the peripheral edge are connected by a peripheral edge inclined surface. In the second filter plate, a second boss portion protruding from the bottom surface of the second recess is provided, and the end surface of the second boss portion and the bottom surface of the second recess are connected by a boss inclined surface, and the bottom surface of the second recess and the peripheral edge are connected by a peripheral edge inclined surface. The diaphragm sheet has a movable portion along the bottom surface, the peripheral edge inclined surface, and the boss inclined surface of the first recess in the first filter plate, a fixed portion fixed to the peripheral edge of the first filter plate, and a boss facing portion fixed to the end surface of the first boss portion. In the filter press device, when a close contact state is formed in which the first filter plate and the second filter plate are in close contact with each other, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate. When squeezing the slurry, by supplying a squeezing fluid between the diaphragm sheet and the first recess of the first filter plate, the movable portion deforms so as to bulge toward the second filter plate side, and the boss inclined surface in the second filter plate has a convex portion.

[0013] Aspect 7 of the present invention is a filter plate unit used in a filter press device, comprising a first filter plate provided with a first recess and a peripheral edge surrounding the first recess on a main surface, a second filter plate provided with a second recess facing the first recess of the first filter plate and a peripheral edge surrounding the second recess on the main surface, and a diaphragm sheet disposed between the first filter plate and the second filter plate. In the first filter plate, a bottom surface of the first recess and the peripheral edge are connected by an inclined surface. In the second filter plate, a bottom surface of the second recess and the peripheral edge are connected by an inclined surface. The diaphragm sheet has a movable portion along a bottom surface and the inclined surface of the first recess in the first filter plate, and a fixed portion fixed to the peripheral edge of the first filter plate. The movable portion has a bottom portion facing the bottom surface of the first recess in the first filter plate and an inclined portion facing the inclined surface. In the filter press device, when a close contact state is formed in which the first filter plate and the second filter plate are in close contact, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate. When squeezing the slurry, a squeezing fluid is supplied between the diaphragm sheet and the first recess of the first filter plate, so that the movable portion deforms to bulge toward the second filter plate side. In a state where the diaphragm sheet is removed from the first filter plate, an inner surface of the inclined portion of the diaphragm sheet has a convex portion.

[0014] Aspect 8 of the present invention is the filter plate unit of Aspect 7, wherein the convex portion is provided over the entire circumference on the inner surface of the inclined portion of the diaphragm sheet.

[0015] Aspect 9 of the present invention is the filter plate unit of Aspect 7 (which may also be Aspect 7 or 8). In a cross section perpendicular to an edge of a boundary between the inclined portion and the fixed portion of the diaphragm sheet, the inner surface of the inclined portion is curved or bent so as to be convex toward the filtration chamber, whereby the convex portion is provided.

[0016] Aspect 10 of the present invention is the filter plate unit of Aspect 7 (which may be any one of Aspects 7 to 9). The outer surface of the inclined portion of the diaphragm sheet has a recess facing the convex portion.

[0017] Aspect 11 of the present invention is the filter plate unit of Aspect 7 (which may be any one of Aspects 7 to 10). A plurality of protrusions are provided on the surface on the second filter plate side at the bottom of the diaphragm sheet. When focusing on the direction perpendicular to the main surface of the first filter plate in the close contact state, with the surface of the bottom on the first filter plate side as a reference, the height of the plurality of protrusions is T2 [mm], the distance from the surface of the fixing portion on the first filter plate side to the surface of the first filter plate is L1 [mm], the thickness of the fixing portion is T1 [mm], and the distance from the surface of the fixing portion on the second filter plate side to the bottom surface of the second recess of the second filter plate is L2 [mm]. Then, 10 [mm] < T1 + L1 + L2 - T2 < 40 [mm] is satisfied.

[0018] Aspect 12 of the present invention is a filter plate unit used in a filter press device, comprising a first filter plate provided with a first recess and a peripheral edge surrounding the first recess on a main surface, a second recess facing the first recess of the first filter plate, and a second filter plate provided with a peripheral edge surrounding the second recess on a main surface, and a diaphragm sheet disposed between the first filter plate and the second filter plate. In the first filter plate, a first boss portion protruding from the bottom surface of the first recess is provided, and the end surface of the first boss portion and the bottom surface of the first recess are connected by a boss inclined surface, and the bottom surface of the first recess and the peripheral edge are connected by a peripheral edge inclined surface. In the second filter plate, a second boss portion protruding from the bottom surface of the second recess is provided, and the end surface of the second boss portion and the bottom surface of the second recess are connected by a boss inclined surface, and the bottom surface of the second recess and the peripheral edge are connected by a peripheral edge inclined surface. The diaphragm sheet has a movable portion along the bottom surface, the peripheral edge inclined surface, and the boss inclined surface of the first recess in the first filter plate, a fixed portion fixed to the peripheral edge of the first filter plate, and a boss facing portion fixed to the end surface of the first boss portion. The movable portion has a bottom portion facing the bottom surface of the first recess in the first filter plate, a peripheral edge inclined portion facing the peripheral edge inclined surface, and a boss inclined portion facing the boss inclined surface. In the filter press device, when a close contact state in which the first filter plate and the second filter plate are in close contact is formed, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate. When squeezing the slurry, by supplying a squeezing fluid between the diaphragm sheet and the first recess of the first filter plate, the movable portion deforms so as to bulge toward the second filter plate side. In a state where the diaphragm sheet is removed from the first filter plate, the inner surface of the boss inclined portion of the diaphragm sheet has a convex portion.

[0019] Aspect 13 of the present invention is a filter press device, comprising any one of the filter plate units of Aspects 1 to 12, and a filter plate opening and closing mechanism that selectively forms a close contact state in which the first filter plate and the second filter plate of the filter plate unit are in close contact and a release state in which the close contact state is released.

Advantages of the Invention

[0020] According to the present invention, damage to the diaphragm sheet can be suppressed.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Modes for Carrying Out the Invention

[0022] (First Embodiment) FIG. 1 is a view showing the configuration of a filter press apparatus 1 according to a first embodiment of the present invention, and is a side view showing the filter press apparatus 1. In FIG. 1, three directions orthogonal to each other are indicated by arrows as the X direction, the Y direction, and the Z direction (the same applies to other figures). Typically, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction.

[0023] The filter press apparatus 1 performs filtration with pressure on a mixture in which sludge and minerals are mixed in a liquid (hereinafter referred to as "slurry"). The filter press apparatus 1 includes a control unit (not shown), a plurality of filter plates 2, a plurality of diaphragm sheets 3, a filter plate support portion 11, and a filter plate opening / closing mechanism 4. The control unit is responsible for overall control of the filter press apparatus 1. Each filter plate 2 is a substantially rectangular plate-shaped member and is formed of, for example, resin or the like. The plurality of filter plates 2 are arranged in the Y direction (hereinafter referred to as the "moving direction" because it is the direction in which the filter plate 2 moves). The total number of filter plates 2 is, for example, 3 or more. A diaphragm sheet 3 is disposed between two adjacent filter plates 2 in the moving direction.

[0024] FIG. 2 is a view showing the filter plate 2 as viewed from the (-Y) side toward the (+Y) direction. FIG. 2 shows a state in which the diaphragm sheet 3 is removed. The filter plate 2 is provided with two upper protruding portions 291 and two lower protruding portions 292. The upper protruding portion 291 is provided at the upper part ((+Z) side portion) of the filter plate 2, and the lower protruding portion 292 is provided at the lower part ((-Z) side portion) of the filter plate 2. The two upper protruding portions 291 protrude from the filter plate 2 in the (+X) direction and the (-X) direction, respectively. The two lower protruding portions 292 protrude from the filter plate 2 in the (+X) direction and the (-X) direction, respectively. Each upper protruding portion 291 is provided with a through hole 293 extending in the moving direction, and each lower protruding portion 292 is also provided with a through hole 294 extending in the moving direction.

[0025] As shown in FIGS. 1 and 2, the filter plate support portion 11 includes a pair of side bars 111 that are long in the moving direction. In FIG. 2, a cross-section of the side bar 111 in a plane perpendicular to the moving direction is shown. The pair of side bars 111 are arranged on both sides of the plurality of filter plates 2 in the X direction. The lower surface of the upper protruding portion 291 of each filter plate 2 contacts the upper surface of the side bar 111, whereby the plurality of filter plates 2 are supported so as to be movable in the moving direction. The upper protruding portion 291 may contact the side bar 111 via a roller or the like. The pair of side bars 111 are also part of the support frame 10 that supports the entire filter press device 1.

[0026] As shown in FIG. 1, the filter plate opening / closing mechanism 4 includes a moving head 41, a fixed head 42, and a reciprocating mechanism 43. The moving head 41 and the fixed head 42 are arranged with a plurality of filter plates 2 sandwiched therebetween in the moving direction. Specifically, the fixed head 42 is arranged on the (+Y) side of the plurality of filter plates 2 and is fixed to the support frame 10. The moving head 41 is arranged on the (-Y) side of the plurality of filter plates 2 and is supported by the pair of side bars 111 so as to be movable in the moving direction. The reciprocating mechanism 43 is, for example, a hydraulic cylinder, and moves the moving head 41 in the moving direction. The reciprocating mechanism 43 may be other than a hydraulic cylinder.

[0027] By moving the moving head 41 in the (+Y) direction, the plurality of filter plates 2 are pushed toward the fixed head 42 and come into close contact with each other in the moving direction (specifically, they come into close contact with each other with the diaphragm sheet 3 and the filter cloth described later interposed therebetween). In the following description, the state in which the plurality of filter plates 2 are brought into close contact with each other in the moving direction by the movement of the moving head 41 in the (+Y) direction is referred to as the "close contact state". Also, in the close contact state, by moving the moving head 41 in the (-Y) direction, a released state in which the close contact state is released is formed. In the filter plate opening / closing mechanism 4, the close contact state and the released state are selectively formed by the movement of the moving head 41 in the moving direction.

[0028] In a plurality of filter plates 2 in the close contact state, the through holes 293 (see FIG. 2) of the upper protrusions 291 on the (+X) side form one fluid flow path continuous in the moving direction. The same applies to the through holes 293 of the upper protrusions 291 on the (-X) side. These fluid flow paths are used as the flow path of the slurry supplied to the filtration chamber R described later and the flow path of the pressing fluid for the operation of the diaphragm sheet 3. Further, the through holes 294 of the lower protrusions 292 on the (-X) side and the through holes 294 of the lower protrusions 292 on the (+X) side also form fluid flow paths continuous in the moving direction. These fluid flow paths are used, for example, for the recovery of the filtrate from the filtration chamber R and the like.

[0029] FIG. 3 is a cross-sectional view showing the filter plate 2 and the diaphragm sheet 3 in the close contact state, and shows a part of the cross-section at the position of arrow III-III in FIG. 2. Each filter plate 2 has a first main surface 20a facing the (-Y) direction and a second main surface 20b facing the (+Y) direction. The first main surface 20a and the second main surface 20b are substantially parallel to each other. The cross-section of the filter plate 2 and the diaphragm sheet 3 shown in FIG. 3 is substantially perpendicular to the first main surface 20a and the second main surface 20b. In FIG. 2, the first main surface 20a is shown. In the following description, when the first main surface 20a and the second main surface 20b are not distinguished, they are simply referred to as "main surfaces 20a, 20b".

[0030] On each of the main surfaces 20a, 20b of the filter plate 2, a recess 21, a plurality of boss portions 22, and a peripheral portion 23 are provided. In FIG. 3, only the recesses 21, the boss portions 22, and the peripheral portions 23 of the main surfaces 20a, 20b facing each other in the two filter plates 2 are labeled (the same applies hereinafter). As shown in FIG. 2, the outer shape of the recess 21 when viewed from the moving direction is substantially rectangular. The outer shape of the recess 21 may be other shapes. The peripheral portion 23 surrounds the recess 21 on the main surfaces 20a, 20b. The recess 21 is a portion recessed with respect to the peripheral portion 23. The bottom surface 211 of the recess 21 and the peripheral portion 23 are surfaces substantially parallel to the ZX plane. The bottom surface 211 of the recess 21 and the peripheral portion 23 are connected by an inclined surface 212 (hereinafter referred to as "peripheral inclined surface 212"). The peripheral inclined surface 212 is a surface whose height from the bottom surface 211 of the recess 21 gradually increases as it approaches the peripheral portion 23.

[0031] Each boss portion 22 protrudes in the moving direction from the bottom surface 211 of the recess 21 at the central portions of the main surfaces 20a and 20b. In the example of FIG. 2, the boss portion 22 is linear and long in the Z direction, and a plurality of (three) boss portions 22 are arranged in the X direction. The height from the bottom surface 211 of the recess 21 to the end face of the boss portion 22 (that is, the face of the boss portion 22 that is farthest from the bottom surface 211 in the moving direction) is slightly smaller than the height from the bottom surface 211 to the peripheral portion 23. The end face of the boss portion 22 is a plane substantially parallel to the ZX plane.

[0032] Between the bottom surface 211 of the recess 21 and the end face of the boss portion 22, there is an inclined surface 213 (hereinafter referred to as the "boss inclined surface 213"). The boss inclined surface 213 is a surface whose height from the bottom surface 211 of the recess 21 gradually increases as it approaches the end face of the boss portion 22. The cross section of the filter plate 2 shown in FIG. 3 is substantially perpendicular to the boundary between the peripheral inclined surface 212 and the peripheral portion 23, and the boundary between the boss inclined surface 213 and the boss portion 22. On each of the first main surface 20a and the second main surface 20b, the shape of the boss inclined surface 213 in the cross section is substantially the same as that of the peripheral inclined surface 212 (exactly, a substantially symmetric shape with respect to a line perpendicular to the X direction).

[0033] In two adjacent filter plates 2 in the moving direction, substantially the entire recesses 21 face each other. In the close contact state, the peripheral portion 23 of one filter plate 2 and the peripheral portion 23 of the other filter plate 2 are in close contact with each other with the diaphragm sheet 3 (and a filter cloth described later) interposed therebetween. The same applies to the plurality of boss portions 22. Actually, on the first main surface 20a and the second main surface 20b of each filter plate 2, the details of the recess 21, the boss portion 22, and the peripheral portion 23 are different, and the details will be described later.

[0034] FIG. 4 is a view showing the diaphragm sheet 3. As described above, the diaphragm sheet 3 is disposed between two adjacent filter plates 2. In FIG. 4, a surface 30a (outer surface 30a described later) facing the filter plate 2 on the (+Y) side among the two filter plates 2 is shown. The diaphragm sheet 3 is fixed to, for example, the first main surface 20a on the (-Y) side of each filter plate 2. Each diaphragm sheet 3 is a sheet formed using an elastic material such as rubber (e.g., natural rubber) and has stretchability. When viewed from the moving direction, the outer shape of the diaphragm sheet 3 is substantially rectangular. The diaphragm sheet 3 is larger than the recess 21 of the first main surface 20a.

[0035] As shown in FIG. 3, the diaphragm sheet 3 is in a bowl shape recessed on the (+Y) side, and includes an outer surface 30a facing the filter plate 2 on the (+Y) side and an inner surface 30b facing the filter plate 2 on the (-Y) side. In the close contact state, a filtration chamber R is formed between the recess 21 of the second main surface 20b of the filter plate 2 on the (-Y) side and the inner surface 30b of the diaphragm sheet 3. Actually, the inner surface 30b of the diaphragm sheet 3 and the second main surface 20b of the filter plate 2 are individually covered with filter cloth, but in FIG. 3, the illustration of the filter cloth is omitted (the same applies to FIG. 5 described later). In the following description, attention is paid to one diaphragm sheet 3. Unless otherwise specified, the "first main surface 20a (of the filter plate 2)" means the first main surface 20a of the filter plate 2 adjacent to the (+Y) side of the diaphragm sheet 3, and the "second main surface 20b (of the filter plate 2)" means the first main surface 20a of the filter plate 2 adjacent to the (-Y) side of the diaphragm sheet 3.

[0036] The diaphragm sheet 3 includes a movable portion 31, a boss facing portion 32, and a fixed portion 33. The fixed portion 33 is a peripheral portion of the diaphragm sheet 3. In a state where the diaphragm sheet 3 is attached to the filter plate 2, the fixed portion 33 extends substantially parallel to the ZX plane and contacts a portion around the recess 21 on the first main surface 20a of the filter plate 2, that is, the peripheral edge portion 23. Specifically, as shown in FIGS. 2 and 3, an annular groove portion 231 along the outer edge of the recess 21 is provided in the peripheral edge portion 23 of the first main surface 20a of the filter plate 2. As shown in FIGS. 3 and 4, an annular protrusion 331 is provided on the outer surface 30a of the fixed portion 33 of the diaphragm sheet 3. The size of the annular protrusion 331 is substantially the same as that of the annular groove portion 231. When the diaphragm sheet 3 is attached to the filter plate 2, the annular protrusion 331 is press-fitted into the annular groove portion 231. Thereby, the fixed portion 33 is fixed to the peripheral edge portion 23 of the first main surface 20a over the entire circumference. Also, the passage of fluid between the fixed portion 33 and the peripheral edge portion 23 becomes substantially impossible. In the example of FIG. 3, the annular groove portion 231 has a shape in which a groove is further formed on the bottom surface of a recess slightly smaller than the thickness of the fixed portion 33.

[0037] As shown in FIGS. 3 and 4, the movable portion 31 is a portion surrounded by the fixed portion 33 around it. The movable portion 31 is approximately bowl-shaped along the bottom surface 211 and the peripheral inclined surface 212 of the recess 21 on the first main surface 20a of the filter plate 2 except around the boss portion 22. The movable portion 31 is a portion recessed on the (+Y) side from the fixed portion 33 and is disposed on the bottom surface 211 side of the recess 21 from the fixed portion 33. A gap is provided between the movable portion 31 and the bottom surface 211 of the recess 21, and the movable portion 31 is a non-fixed portion with respect to the filter plate 2.

[0038] The movable part 31 has a bottom part 311 facing the bottom surface 211 of the concave part 21 and an inclined part 312 (hereinafter referred to as "peripheral edge inclined part 312") facing the peripheral edge inclined surface 212. The bottom part 311 is substantially parallel to the bottom surface 211 of the concave part 21. The peripheral edge inclined part 312 is a part between the bottom part 311 and the fixing part 33, and the height from the bottom part 311 gradually increases as it approaches the fixing part 33 from the bottom part 311. A plurality of protrusions 319 are provided on the inner surface 30b of the bottom part 311. The heights of the plurality of protrusions 319 are substantially constant. The plurality of protrusions 319 face the bottom surface 211 of the concave part 21 on the second main surface 20b of the filter plate 2 with the filtration chamber R interposed therebetween. A plurality of grooves 219 are formed on the bottom surface 211 of the second main surface 20b.

[0039] The boss facing part 32 is a part that overlaps with the boss part 22 of the filter plate 2 in the moving direction. The periphery of the boss facing part 32 is surrounded by the movable part 31 and is located on the (-Y) side of the movable part 31. The boss facing part 32 contacts the end face of the boss part 22 on the first main surface 20a. Specifically, as shown in FIGS. 2 and 3, a plurality of auxiliary groove parts 221 are provided on the boss part 22 of the first main surface 20a. As shown in FIGS. 3 and 4, a plurality of auxiliary protrusions 321 are provided on the outer surface 30a of the boss facing part 32 of the diaphragm sheet 3. When the diaphragm sheet 3 is attached to the filter plate 2, the plurality of auxiliary protrusions 321 are press-fitted into the plurality of auxiliary groove parts 221 respectively. Thereby, the boss facing part 32 is fixed to the boss part 22 of the first main surface 20a. The boss facing part 32 is a fixing part to the filter plate 2 in the same manner as the fixing part 33. In a state where the diaphragm sheet 3 is attached to the filter plate 2, the boss facing part 32 is substantially parallel to the bottom part 311 and the fixing part 33.

[0040] The movable part 31 also has an inclined part 313 (hereinafter referred to as "boss inclined part 313") that faces the boss inclined surface 213 around the boss part 22. The boss inclined part 313 is a part between the bottom part 311 and the boss facing part 32, and the height from the bottom part 311 gradually increases as it approaches the boss facing part 32. The cross-section of the diaphragm sheet 3 shown in FIG. 3 is substantially perpendicular to the boundary between the peripheral inclined part 312 and the fixed part 33, and the boundary between the boss inclined part 313 and the boss facing part 32. The shape of the boss inclined part 313 in the cross-section is substantially the same as that of the peripheral inclined part 312 (exactly, a substantially symmetric shape with respect to a line perpendicular to the X direction).

[0041] FIG. 5 is a cross-sectional view showing the filter plate 2 and the diaphragm sheet 3 in the close contact state, and shows the vicinity of the peripheral inclined surface 212 of the filter plate 2 and the peripheral inclined part 312 of the diaphragm sheet 3 in FIG. 3. On the second main surface 20b of the filter plate 2, a convex part 216 is provided on the peripheral inclined surface 212 of the concave part 21. In a cross-section perpendicular to the edge of the boundary between the peripheral inclined surface 212 and the peripheral part 23 on the second main surface 20b of the filter plate 2, a line segment E1 (shown by a two-dot chain line in FIG. 5) connecting the boundary between the peripheral inclined surface 212 and the peripheral part 23 and the boundary between the peripheral inclined surface 212 and the bottom surface 211, the part of the filter plate 2 protruding toward the filtration chamber R side (the concave part 21 side of the first main surface 20a) is the convex part 216.

[0042] In the example of FIG. 5, in the cross-section, the convex part 216 is formed by the substantially entire peripheral inclined surface 212 being curved so as to be convex toward the filtration chamber R. Only a part of the peripheral inclined surface 212 may be convex. Also, the convex part 216 may be provided by the peripheral inclined surface 212 being bent so as to be convex toward the filtration chamber R. The convex part 216 is provided substantially over the entire circumference (substantially over the entire circumference around the bottom surface 211) on the peripheral inclined surface 212 of the second main surface 20b. Typically, the convex part 216 is not provided on the peripheral inclined surface 212 of the first main surface 20a of the filter plate 2.

[0043] As shown in Fig. 3, in the recess 21 on the second main surface 20b, a convex portion 217 similar to the convex portion 216 is also provided on the boss inclined surface 213 between the bottom surface 211 and the end surface of the boss portion 22. In a cross-section perpendicular to the edge of the boundary between the boss inclined surface 213 and the end surface of the boss portion 22 on the second main surface 20b of the filter plate 2, with respect to the line segment connecting the boundary between the boss inclined surface 213 and the end surface of the boss portion 22 and the boundary between the boss inclined surface 213 and the bottom surface 211, the portion of the filter plate 2 protruding toward the filtration chamber R side is the convex portion 217. The convex portion 217 in Fig. 3 is also formed by curving or bending such that the boss inclined surface 213 becomes convex. The convex portion 217 is provided substantially over the entire circumference around the boss portion 22 on the boss inclined surface 213 of the second main surface 20b. Typically, the convex portion 217 is not provided on the boss inclined surface 213 of the first main surface 20a of the filter plate 2.

[0044] In the treatment of the slurry in the filter press apparatus 1, the reciprocating mechanism 43 in Fig. 1 moves the moving head 41 toward the fixed head 42. As a result, a plurality of filter plates 2 are brought into a close contact state, and as shown in Fig. 3, a filtration chamber R is formed between the recess 21 on the second main surface 20b of each filter plate 2 and the inner surface 30b of the diaphragm sheet 3. Actually, the second main surface 20b of the filter plate 2 and the inner surface 30b of the diaphragm sheet 3 are individually covered with a filter cloth 51 (see Fig. 6). As shown in Fig. 6, in each filtration chamber R, slurry 81 is supplied between the filter cloths 51 by a slurry supply portion (not shown). The slurry 81 is injected at a high pressure, and the slurry 81 is filtered by the filter cloth 51. The liquid that has passed through the filter cloth 51 on the second main surface 20b side of the filter plate 2 moves to the lower part of the filtration chamber R through a plurality of grooves 219 on the bottom surface 211 of the recess 21 on the second main surface 20b. The liquid that has passed through the filter cloth 51 on the diaphragm sheet 3 side moves to the lower part of the filtration chamber R through the gaps (drainage grooves) between the protrusions 319 on the inner surface 30b of the diaphragm sheet 3. In the lower part of the filtration chamber R, the liquid is discharged to the through-hole 294 (fluid flow path formed by a plurality of filter plates 2) in Fig. 2 through a recovery path (not shown).

[0045] Subsequently, a predetermined pressing fluid is supplied from the pressing fluid supply unit 16 (see FIG. 1) to the recess 21 on the first main surface 20a of each filter plate 2 through the through hole 293 or the like. Due to the supply of the pressing fluid, as shown by the two-dot chain line in FIG. 6, the movable portion 31 of the diaphragm sheet 3 moves away from the bottom surface 211 of the recess 21 on the first main surface 20a (that is, toward the second main surface 20b of the filter plate 2 on the (-Y) side) and swells. Specifically, the movable portion 31 deforms convexly toward the (-Y) side along the recess 21 on the second main surface 20b of the filter plate 2 on the (-Y) side. Thereby, the slurry 81 in the filtration chamber R is pressed. When the pressing of the slurry 81 is completed, the pressing fluid between the recess 21 on the first main surface 20a and the diaphragm sheet 3 is discharged, and the movable portion 31 of the diaphragm sheet 3 returns to the side of the recess 21 on the first main surface 20a. Thereafter, the moving head 41 moves in the (-Y) direction by the advancing and retreating mechanism 43 in FIG. 1, and the close contact state of the plurality of filter plates 2 is released. In other words, a released state in which the close contact state is released is formed. Note that the solid matter (dehydrated cake) remaining in each filtration chamber R is removed by a predetermined method.

[0046] Here, the result of confirming the stress generated in the diaphragm sheet due to the deformation of the diaphragm sheet during the pressing of the slurry by finite element analysis will be described. FIG. 7 shows an analysis model in the case of using the filter plate 2 provided with the convex portion 216 on the peripheral inclined surface 212 of the second main surface 20b, and FIG. 8 shows an analysis model in the case of using the comparative example filter plate 91 not provided with the convex portion 216 on the peripheral inclined surface 212 of the second main surface 20b. The upper stages of FIGS. 7 and 8 show the normal state in which no deformation has occurred in the diaphragm sheet 3, and the lower stages show the pressing state in which deformation has occurred in the diaphragm sheet 3.

[0047] As shown in the lower parts of FIGS. 7 and 8, in the squeezing of the slurry, in the diaphragm sheet 3, a portion 391 (hereinafter referred to as "peripheral bending portion 391") at the boundary between the peripheral inclined portion 312 of the movable portion 31 and the fixed portion 33 bends greatly. In a filter press apparatus using a filter plate 91 of a comparative example in which no convex portion 216 is provided on the peripheral inclined surface 212, in fact, cracks often occur on the outer surface 30a side of the peripheral bending portion 391. As a result of the finite element analysis, in both the analysis model of FIG. 7 and the analysis model of FIG. 8, stress concentrates on the outer surface 30a of the peripheral bending portion 391. Specifically, in the analysis model of the comparative example in FIG. 8, the maximum principal stress at the peripheral bending portion 391 is 2.74 MPa, whereas in the analysis model of FIG. 7 in which the convex portion 216 is provided, the maximum principal stress at the peripheral bending portion 391 is 1.84 MPa, which is significantly smaller than that of the analysis model of the comparative example. Therefore, it can be said that the presence of the convex portion 216 suppresses damage to the diaphragm sheet 3 at the peripheral bending portion 391.

[0048] Also, in the squeezing of the slurry, in the diaphragm sheet 3 shown in FIG. 3, a portion 392 (hereinafter referred to as "boss bending portion 392") at the boundary between the boss inclined portion 313 of the movable portion 31 and the boss facing portion 32 also bends greatly. For the boss inclined surface 213 of the second main surface 20b, by providing a convex portion 217 similar to the above convex portion 216, the stress generated in the boss bending portion 392 becomes smaller than in the case where no convex portion 217 is provided on the boss inclined surface 213. As a result, damage to the diaphragm sheet 3 at the boss bending portion 392 is suppressed.

[0049] In the example of FIG. 3, the diaphragm sheet 3 is attached to one main surface (the first main surface 20a) of each filter plate 2. However, depending on the design of the filter press device 1, a squeezing filter plate to which the diaphragm sheet 3 is attached to both main surfaces and a normal filter plate to which the diaphragm sheet 3 is not attached to both main surfaces may be alternately arranged in the moving direction. In this case, both main surfaces of the squeezing filter plate have the same structure as the first main surface 20a, and both main surfaces of the normal filter plate have the same structure as the second main surface 20b. And on the main surface (the second main surface 20b) of the normal filter plate facing the diaphragm sheet 3, the peripheral edge inclined surface 212 of the recess 21 has a convex portion 216, and the boss inclined surface 213 has a convex portion 217. Thereby, damage to the diaphragm sheet 3 at the peripheral edge bent portion 391 and the boss bent portion 392 is suppressed.

[0050] Here, in the example of FIG. 3 in which the diaphragm sheet 3 is attached to each filter plate 2 and in the example in which the squeezing filter plate and the normal filter plate are alternately provided, pay attention to a set of one diaphragm sheet 3 and two filter plates adjacent to both sides in the moving direction with respect to the diaphragm sheet 3 as a filter plate unit. Also, among the two filter plates, the filter plate to which the diaphragm sheet 3 is attached is called the first filter plate, and the filter plate to which the diaphragm sheet 3 is not attached is called the second filter plate. Further, the recess 21 of the first filter plate and the recess 21 of the second filter plate are respectively called "the first recess 21" and "the second recess 21", and the boss portion 22 of the first filter plate and the boss portion 22 of the second filter plate are respectively called "the first boss portion 22" and "the second boss portion 22".

[0051] In this case, in the first filter plate, a first recess 21 and a peripheral edge portion 23 surrounding the first recess 21 are provided on the main surface (in the above, the first main surface 20a). In the second filter plate, a second recess 21 facing the first recess 21 of the first filter plate and a peripheral edge portion 23 surrounding the second recess 21 are provided on the main surface (in the above, the second main surface 20b). The diaphragm sheet 3 is disposed between the first filter plate and the second filter plate. In the first filter plate, the bottom surface 211 of the first recess 21 and the peripheral edge portion 23 are connected by a peripheral inclined surface 212. In the second filter plate, the bottom surface 211 of the second recess 21 and the peripheral edge portion 23 are connected by a peripheral inclined surface 212. The diaphragm sheet 3 has a movable portion 31 along the bottom surface 211 and the peripheral inclined surface 212 of the first recess 21 in the first filter plate, and a fixed portion 33 fixed to the peripheral edge portion 23 of the first filter plate.

[0052] In the filter press apparatus 1 in which the filter plate unit is used, a close contact state in which the first filter plate and the second filter plate are in close contact is formed, so that a filtration chamber R into which slurry is supplied is formed between the diaphragm sheet 3 and the second recess 21 of the second filter plate. Further, when the slurry is pressed, a pressing fluid is supplied between the diaphragm sheet 3 and the first recess 21 of the first filter plate, so that the movable portion 31 deforms so as to bulge toward the second filter plate side. At this time, in the filter plate unit, since the peripheral inclined surface 212 of the second recess 21 in the second filter plate has a convex portion 216, the deformation of the diaphragm sheet 3 at the peripheral bent portion 391 is suppressed (that is, the bending angle at the peripheral bent portion 391 becomes small). As a result, damage to the diaphragm sheet 3 can be suppressed.

[0053] In the first filter plate, a first boss portion 22 protruding from the bottom surface 211 of the first recess 21 is provided, and in the second filter plate, a second boss portion 22 protruding from the bottom surface 211 of the second recess 21 is provided. In the first filter plate, the end face of the first boss portion 22 and the bottom surface 211 of the first recess 21 are connected by a boss inclined surface 213. Also, in the second filter plate, the end face of the second boss portion 22 and the bottom surface 211 of the second recess 21 are connected by a boss inclined surface 213. In the diaphragm sheet 3, a boss facing portion 32 fixed to the end face of the first boss portion 22 is provided, and around the boss facing portion 32, the movable portion 31 is shaped to follow the boss inclined surface 213. In such a filter plate unit, since the boss inclined surface 213 in the second filter plate has a convex portion 217, deformation of the diaphragm sheet 3 at the boss bent portion 392 is suppressed. As a result, damage to the diaphragm sheet 3 can be suppressed.

[0054] On the peripheral inclined surface 212 of the second filter plate, by providing the convex portion 216 over the entire circumference, damage to the diaphragm sheet 3 can be suppressed over the entire circumference of the peripheral inclined portion 312. Similarly, on the boss inclined surface 213 of the second filter plate, by providing the convex portion 217 over the entire circumference, damage to the diaphragm sheet 3 can be suppressed over the entire circumference of the boss inclined portion 313.

[0055] Next, in a filter press apparatus 1 in which a filter plate unit is used, a method for more reliably suppressing damage to the diaphragm sheet 3 will be described with reference to FIG. 5. In FIG. 5, the filter plate 2 on the (+Y) side and the filter plate 2 on the (-Y) side respectively correspond to the first filter plate and the second filter plate of the filter plate unit. Here, the movable portion 31 of the diaphragm sheet 3 has a bottom portion 311 facing the bottom surface 211 of the first recess 21 in the first filter plate, and a plurality of protrusions 319 are provided on the surface on the second filter plate side (inner surface 30b in FIG. 5) at the bottom portion 311. When attention is paid to the Y direction perpendicular to the main surface of the first filter plate in the filter plate unit in a close contact state, with reference to the surface on the first filter plate side (outer surface 30a in FIG. 5) of the bottom portion 311 of the movable portion 31, the height of the plurality of protrusions 319 is T2 [mm], and the distance from the surface on the first filter plate side of the fixed portion 33 to the surface on the second filter plate side is L1 [mm]. Also, the thickness of the fixed portion 33 is T1 [mm], and the distance from the surface on the second filter plate side of the fixed portion 33 to the bottom surface 211 of the second recess 21 of the second filter plate (not including the groove 219) is L2 [mm].

[0056] At this time, in the filter plate unit, the maximum displacement amount of the bottom portion 311 of the movable portion 31 in the Y direction is expressed as (T1 + L1 + L2 - T2). When the maximum displacement amount is excessively large, the deformation of the diaphragm sheet 3 at the peripheral bending portion 391 becomes large, and damage to the diaphragm sheet 3 is likely to occur. On the other hand, when the maximum displacement amount is excessively small, the processing amount of the slurry in the filter press apparatus 1 decreases. In order to prevent the maximum displacement amount from becoming excessively large and suppress damage to the diaphragm sheet 3, and to process a certain amount of slurry, it is preferable that 10 [mm] < T1 + L1 + L2 - T2 < 40 [mm] is satisfied (the same applies to the second embodiment described later).

[0057] (Second Embodiment) FIG. 9 is a view showing the filter plate 2 and the diaphragm sheet 3 of the filter press device 1a according to the second embodiment of the present invention. FIG. 9 corresponds to FIG. 5 and shows a cross section of the filter plate 2 and the diaphragm sheet 3. In the filter press device 1a of FIG. 9, the shape of the diaphragm sheet 3 is different from that of the diaphragm sheet 3 in FIG. 5. Further, the convex portion 216 on the peripheral inclined surface 212 of the second main surface 20b of the filter plate 2 and the convex portion 217 on the boss inclined surface 213 (see FIG. 3) are omitted. Other configurations are the same as those of the filter press device 1, and the same reference numerals are given to the same configurations.

[0058] In the diaphragm sheet 3 of FIG. 9, a convex portion 316 is provided on the inner surface 30b of the peripheral inclined portion 312. In a cross section perpendicular to the edge of the boundary between the peripheral inclined portion 312 and the fixed portion 33 in the diaphragm sheet 3, a line segment E2 (shown by a two-dot chain line in FIG. 9) connecting the boundary between the peripheral inclined portion 312 and the fixed portion 33 on the inner surface 30b and the boundary between the peripheral inclined portion 312 and the bottom portion 311, the portion of the diaphragm sheet 3 protruding toward the filtration chamber R side (the concave portion 21 side of the second main surface 20b) is the convex portion 316. The convex portion 316 exists on the inner surface 30b of the peripheral inclined portion 312 even when the diaphragm sheet 3 is removed from the filter plate 2 (the same applies to the concave portion 318 described later). That is, the convex portion 316 is not a deformed portion of the peripheral inclined portion 312 according to the shape of the peripheral inclined surface 212 of the filter plate 2. Most of the peripheral inclined portion 312 may be non-contact with the peripheral inclined surface 212.

[0059] In the example of FIG. 9, in the above cross section, the convex portion 316 is formed by bending the inner surface 30b of the peripheral inclined portion 312 so as to be convex toward the filtration chamber R. As shown in FIG. 10, the convex portion 316 may be provided by curving substantially the entire inner surface 30b of the peripheral inclined portion 312 so as to be convex toward the filtration chamber R. Only a part of the inner surface 30b of the peripheral inclined portion 312 may be curved or bent. The convex portion 316 is provided substantially over the entire circumference (substantially the entire circumference around the bottom portion 311) on the inner surface 30b of the peripheral inclined portion 312.

[0060] Further, a concave portion 318 facing the convex portion 316 is provided on the outer surface 30a of the peripheral inclined portion 312 shown in FIG. 9. In the above cross section, a line segment E3 (shown by a two-dot chain line in FIG. 9) connecting the boundary between the peripheral inclined portion 312 and the fixing portion 33 on the outer surface 30a and the boundary between the peripheral inclined portion 312 and the bottom portion 311, the portion recessed toward the filtration chamber R side is the concave portion 318. In the example of FIG. 9, in the above cross section, the outer surface 30a of the peripheral inclined portion 312 is bent so as to be recessed toward the filtration chamber R, thereby forming the concave portion 318. As shown in FIG. 10, the concave portion 318 may be provided by curving the substantially entire outer surface 30a of the peripheral inclined portion 312 so as to be recessed toward the filtration chamber R. Only a part of the outer surface 30a of the peripheral inclined portion 312 may be curved or bent. The concave portion 318 is provided substantially over the entire circumference on the outer surface 30a of the peripheral inclined portion 312.

[0061] In the present embodiment, a convex portion similar to the convex portion 316 is also provided on the boss inclined portion 313 (see FIG. 3) facing the boss inclined surface 213 around the boss portion 22. In a cross section perpendicular to the edge of the boundary between the boss inclined portion 313 and the boss facing portion 32 in the diaphragm sheet 3, with respect to a line segment connecting the boundary between the boss inclined portion 313 and the boss facing portion 32 on the inner surface 30b and the boundary between the boss inclined portion 313 and the bottom portion 311, the portion of the diaphragm sheet 3 protruding toward the filtration chamber R side is the convex portion. The convex portion exists on the inner surface 30b of the boss inclined portion 313 even when the diaphragm sheet 3 is removed from the filter plate 2 (the same applies to the concave portion described later in the boss inclined portion 313). The convex portion is also formed by curving or bending the inner surface 30b of the boss inclined portion 313 so as to be convex toward the filtration chamber R. The convex portion is provided substantially over the entire circumference around the boss facing portion 32 in the boss inclined portion 313.

[0062] Further, a concave portion is provided on the outer surface 30a of the boss inclined portion 313, which faces the convex portion. In the above cross-section, a portion recessed toward the filtration chamber R side with respect to the line segment connecting the boundary between the boss inclined portion 313 and the boss facing portion 32 on the outer surface 30a and the boundary between the boss inclined portion 313 and the bottom portion 311 is the concave portion. Similar to the concave portion 318, the concave portion is also formed by the outer surface 30a of the boss inclined portion 313 curving or bending so as to be recessed toward the filtration chamber R. The concave portion is provided over substantially the entire circumference around the boss facing portion 32 in the boss inclined portion 313.

[0063] Here, the results of confirming the stress generated in the diaphragm sheet due to the deformation of the diaphragm sheet during the squeezing of the slurry by finite element analysis will be described. The upper part of FIG. 11 shows an analysis model of the diaphragm sheet 3 in which the convex portion 316 is provided on the inner surface 30b of the peripheral edge inclined portion 312 and the concave portion 318 is provided on the outer surface 30a. The middle part of FIG. 11 shows an analysis model of the diaphragm sheet 3 in which only the convex portion 316 is provided. The lower part of FIG. 11 shows an analysis model of the comparative example diaphragm sheet 92 in which neither the convex portion 316 nor the concave portion 318 is provided. FIG. 11 shows the normal state in which no deformation has occurred in the diaphragm sheet 3.

[0064] As a result of the finite element analysis, the maximum principal stress at the peripheral edge bending portion 391 in the analysis model of the comparative example shown in the lower part of FIG. 11 is 2.74 MPa, whereas in the analysis model of the upper part of FIG. 11 in which the convex portion 316 and the concave portion 318 are provided, the maximum principal stress at the peripheral edge bending portion 391 is 1.86 MPa, which is significantly smaller than that of the analysis model of the comparative example. Therefore, it can be said that the presence of the convex portion 316 and the concave portion 318 suppresses the damage of the diaphragm sheet 3 at the peripheral edge bending portion 391. Actually, even in the analysis model of the middle part of FIG. 11 in which only the convex portion 316 is provided, the maximum principal stress at the peripheral edge bending portion 391 is 2.49 MPa, which is smaller than that of the analysis model of the comparative example.

[0065] Regarding the boss inclined portion 313 (see FIG. 3) as well, by providing a convex portion similar to the convex portion 316, the stress generated in the boss bent portion 392 becomes smaller compared to the case where no convex portion is provided on the boss inclined portion 313, and damage to the diaphragm sheet 3 in the boss bent portion 392 is suppressed. Further, in the boss inclined portion 313, by providing a concave portion similar to the concave portion 318, damage to the diaphragm sheet 3 in the boss bent portion 392 is further suppressed. The method of providing the convex portion 316 (and the concave portion 318) on the peripheral edge inclined portion 312 and providing the convex portion (and the concave portion) on the boss inclined portion 313 may be adopted in a filter press device in which the squeezing filter plates and the ordinary filter plates are alternately arranged.

[0066] Here, similar to the first embodiment, attention is paid to a set of one diaphragm sheet 3 and two filter plates (the first filter plate and the second filter plate) arranged on both sides of the diaphragm sheet 3 as a filter plate unit. In the first filter plate, the first concave portion 21 and the peripheral edge portion 23 surrounding the first concave portion 21 are provided on the main surface (in the above, the first main surface 20a). In the second filter plate, the second concave portion 21 facing the first concave portion 21 of the first filter plate and the peripheral edge portion 23 surrounding the second concave portion 21 are provided on the main surface (in the above, the second main surface 20b). The diaphragm sheet 3 is arranged between the first filter plate and the second filter plate. In the first filter plate, the bottom surface 211 of the first concave portion 21 and the peripheral edge portion 23 are connected by the peripheral edge inclined surface 212, and in the second filter plate, the bottom surface 211 of the second concave portion 21 and the peripheral edge portion 23 are connected by the peripheral edge inclined surface 212. The diaphragm sheet 3 has a movable portion 31 along the bottom surface 211 and the peripheral edge inclined surface 212 of the first concave portion 21 in the first filter plate and a fixed portion 33 fixed to the peripheral edge portion 23 of the first filter plate. The movable portion 31 has a bottom portion 311 facing the bottom surface 211 of the first concave portion 21 in the first filter plate and a peripheral edge inclined portion 312 facing the peripheral edge inclined surface 212. In such a filter plate unit, with the diaphragm sheet 3 removed from the first filter plate, the inner surface 30b of the peripheral edge inclined portion 312 of the diaphragm sheet 3 has a convex portion 316. Thereby, during the squeezing of the slurry, the deformation of the diaphragm sheet 3 in the peripheral edge bent portion 391 is suppressed, and damage to the diaphragm sheet 3 can be suppressed.

[0067] In the above filter plate unit, in the first filter plate, a first boss portion 22 protruding from the bottom surface 211 of the first recess 21 is provided, and in the second filter plate, a second boss portion 22 protruding from the bottom surface 211 of the second recess 21 is provided. In the first filter plate, the end face of the first boss portion 22 and the bottom surface 211 of the first recess 21 are connected by a boss inclined surface 213. Also, in the second filter plate, the end face of the second boss portion 22 and the bottom surface 211 of the second recess 21 are connected by a boss inclined surface 213. In the diaphragm sheet 3, a boss facing portion 32 fixed to the end face of the first boss portion 22 is provided. Around the boss facing portion 32, the movable portion 31 has a shape along the boss inclined surface 213, and a boss inclined portion 313 facing the boss inclined surface 213 is provided. In such a filter plate unit, with the diaphragm sheet 3 removed from the first filter plate, the inner surface 30b of the boss inclined portion 313 of the diaphragm sheet 3 has a convex portion. Thereby, the deformation of the diaphragm sheet 3 at the boss bent portion 392 can be suppressed, and damage to the diaphragm sheet 3 can be inhibited.

[0068] By providing the convex portion 316 over the entire circumference on the inner surface 30b of the peripheral edge inclined portion 312 of the diaphragm sheet 3, damage to the diaphragm sheet 3 can be suppressed over the entire circumference of the peripheral edge inclined portion 312. Similarly, by providing the convex portion over the entire circumference on the boss inclined portion 313 of the diaphragm sheet 3, damage to the diaphragm sheet 3 can be suppressed over the entire circumference of the boss inclined portion 313.

[0069] As shown by the two-dot chain line in Fig. 9, in the filter plate unit, the peripheral inclined surface 212 of the second recess 21 in the second filter plate may have a convex portion 216. Thereby, the deformation of the diaphragm sheet 3 at the peripheral bent portion 391 is further suppressed by the convex portion 316 of the peripheral inclined portion 312 of the diaphragm sheet 3 and the convex portion 216 of the peripheral inclined surface 212 of the second filter plate. As a result, damage to the diaphragm sheet 3 can be further suppressed. Similarly, the boss inclined surface 213 of the second filter plate may have a convex portion 217 (see Fig. 3). Thereby, the deformation of the diaphragm sheet 3 at the boss bent portion 392 is further suppressed by the convex portion of the boss inclined portion 313 of the diaphragm sheet 3 and the convex portion 217 of the boss inclined surface 213 of the second filter plate.

[0070] In the filter plate unit, since the outer surface 30a of the peripheral inclined portion 312 of the diaphragm sheet 3 has a recess 318 facing the convex portion 316, damage to the diaphragm sheet 3 can be further suppressed. Similarly, since the outer surface 30a of the boss inclined portion 313 of the diaphragm sheet 3 has a recess facing the convex portion of the inner surface 30b, damage to the diaphragm sheet 3 can be further suppressed.

[0071] In the above filter plate unit and the filter press apparatuses 1, 1a, various modifications are possible.

[0072] In the peripheral inclined surface 212 of the second filter plate, the convex portion 216 does not necessarily need to be provided over the entire circumference. For example, when a position where the diaphragm sheet 3 is likely to be damaged is specified as a tendency, the convex portion 216 may be provided only at or near the position. The same applies to the convex portion 217 of the boss inclined surface 213 of the second filter plate, the convex portion 316 and the recess 318 of the peripheral inclined portion 312 of the diaphragm sheet 3, and the convex portion and the recess of the boss inclined portion 313 of the diaphragm sheet 3.

[0073] The shape of the convex portion 216 on the peripheral inclined surface 212 of the second filter plate may be variously changed. For example, in the cross-section shown in FIG. 12, the convex portion 216 may be provided only on a part of the peripheral inclined surface 212. Similarly, in the cross-section shown in FIG. 13, the convex portion 316 may be provided only on a part of the inner surface 30b of the peripheral inclined portion 312 of the diaphragm sheet 3, and the concave portion 318 may be provided only on a part of the outer surface 30a. The same applies to the convex portion 217 on the boss inclined surface 213 of the second filter plate, and the convex and concave portions on the boss inclined portion 313 of the diaphragm sheet 3.

[0074] In the filter plate of the existing filter press device, the convex portion 216 on the peripheral inclined surface 212 and the convex portion 217 on the boss inclined surface 213 may be realized by attaching a convex member to the peripheral inclined surface 212 and the boss inclined surface 213.

[0075] In the filter press device 1 of the first embodiment, the convex portions 216 and 217 may be provided only on one of the peripheral inclined surface 212 and the boss inclined surface 213 of the second filter plate. In the filter press device 1a of the second embodiment, the convex portion 316 may be provided only on one of the peripheral inclined portion 312 and the boss inclined portion 313 of the diaphragm sheet 3.

[0076] Depending on the design of the filter plate unit, the boss portion 22 may be omitted in the filter plate 2, and in this case, the boss facing portion 32 of the diaphragm sheet 3 is also omitted.

[0077] The configuration of the filter press devices 1 and 1a having the above filter plate unit (usually a plurality of filter plates 2) and the filter plate opening and closing mechanism 4 may be appropriately changed.

[0078] The configurations in the above embodiments and each modification may be appropriately combined as long as they do not conflict with each other.

Explanation of Reference Numerals

[0079] 1, 1a Filter press device 2 Filter plate 3 Diaphragm sheet 4 Filter plate opening and closing mechanism Main surfaces of 20a and 20b (filter plates) 21 Concave portion 22 Boss portion 23 Peripheral portion Outer surface of 30a (diaphragm sheet) Inner surface of 30b (diaphragm sheet) 31 Movable portion 32 Boss facing portion 33 Fixed portion 81 Slurry Bottom surface of 211 (concave portion) 212 Peripheral inclined surface 213 Boss inclined surface Protrusion of 216 (peripheral inclined surface) Protrusion of 217 (boss inclined surface) Bottom portion of 311 312 Peripheral inclined portion 313 Boss inclined portion Protrusion of 316 (peripheral inclined portion) Recess of 318 (peripheral inclined portion) 319 Protrusion R Filtration chamber

Claims

1. A filter plate unit used in a filter press device, a first filter plate provided with a first recess and a peripheral edge surrounding the first recess on a main surface, a second filter plate provided with a second recess facing the first recess of the first filter plate and a peripheral edge surrounding the second recess on a main surface, a diaphragm sheet disposed between the first filter plate and the second filter plate, comprising, in the first filter plate, a bottom surface of the first recess and the peripheral edge are connected by an inclined surface, in the second filter plate, a bottom surface of the second recess and the peripheral edge are connected by an inclined surface, the diaphragm sheet has a movable portion along the bottom surface and the inclined surface of the first recess in the first filter plate, and a fixed portion fixed to the peripheral edge of the first filter plate, in a filter press device, when a close contact state in which the first filter plate and the second filter plate are in close contact is formed, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate, and when the slurry is pressed, a pressing fluid is supplied between the diaphragm sheet and the first recess of the first filter plate, so that the movable portion deforms to bulge toward the second filter plate side, the filter plate unit in which the inclined surface of the second recess in the second filter plate has a convex portion.

2. The filter plate unit according to claim 1, the filter plate unit in which the convex portion is provided over the entire circumference on the inclined surface of the second filter plate.

3. The filter plate unit according to claim 1, in a cross section perpendicular to an edge at a boundary between the inclined surface and the peripheral edge of the second filter plate, the filter plate unit in which the convex portion is provided by the inclined surface being curved or bent so as to be convex toward the filtration chamber.

4. The filter plate unit according to claim 1, The movable part of the diaphragm sheet has a bottom part facing the bottom surface of the first recess in the first filter plate and an inclined part facing the inclined surface. A filter plate unit in which, when the diaphragm sheet is removed from the first filter plate, the inner surface of the inclined part of the diaphragm sheet has a convex part.

5. The filter plate unit according to claim 1, The movable part of the diaphragm sheet has a bottom part facing the bottom surface of the first recess in the first filter plate, A plurality of protrusions are provided on the surface on the second filter plate side at the bottom part, When focusing on the direction perpendicular to the main surface of the first filter plate in the close contact state, with the surface of the bottom part on the first filter plate side as a reference, the height of the plurality of protrusions is T2 [mm], the distance from the surface of the fixing part on the first filter plate side to the surface of the fixing part is L1 [mm], the thickness of the fixing part is T1 [mm], and the distance from the surface of the fixing part on the second filter plate side to the bottom surface of the second recess of the second filter plate is L2 [mm]. 10 [mm] < T1 + L1 + L2 - T2 < 40 [mm] A filter plate unit that satisfies the above conditions.

6. A filter plate unit used in a filter press device, A first filter plate provided with a first recess and a peripheral edge surrounding the first recess on the main surface, A second filter plate provided with a second recess facing the first recess of the first filter plate and a peripheral edge surrounding the second recess on the main surface, A diaphragm sheet disposed between the first filter plate and the second filter plate, and In the first filter plate, a first boss portion protruding from the bottom surface of the first recess is provided, the end surface of the first boss portion and the bottom surface of the first recess are connected by a boss inclined surface, and the bottom surface of the first recess and the peripheral edge are connected by a peripheral edge inclined surface. In the second filter plate, a second boss portion protruding from the bottom surface of the second recess is provided, and the end surface of the second boss portion and the bottom surface of the second recess are connected by a boss inclined surface, and the bottom surface of the second recess and the peripheral edge portion are connected by a peripheral edge inclined surface. The diaphragm sheet has a movable portion along the bottom surface, the peripheral edge inclined surface, and the boss inclined surface of the first recess in the first filter plate, a fixed portion fixed to the peripheral edge portion of the first filter plate, and a boss opposing portion fixed to the end surface of the first boss portion. In the filter press device, when the first filter plate and the second filter plate are in close contact with each other, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate. When squeezing the slurry, by supplying a squeezing fluid between the diaphragm sheet and the first recess of the first filter plate, the movable portion deforms so as to bulge toward the second filter plate side. A filter plate unit in which the boss inclined surface of the second filter plate has a convex portion.

7. A filter plate unit used in a filter press device, A first filter plate provided with a first recess and a peripheral edge portion surrounding the first recess on a main surface, A second filter plate provided with a second recess facing the first recess of the first filter plate and a peripheral edge portion surrounding the second recess on a main surface, A diaphragm sheet disposed between the first filter plate and the second filter plate, Comprising: In the first filter plate, the bottom surface of the first recess and the peripheral edge portion are connected by an inclined surface. In the second filter plate, the bottom surface of the second recess and the peripheral edge portion are connected by an inclined surface. The diaphragm sheet has a movable portion along the bottom surface and the inclined surface of the first recess in the first filter plate, and a fixed portion fixed to the peripheral edge portion of the first filter plate. The movable portion has a bottom portion facing the bottom surface of the first recess in the first filter plate and an inclined portion facing the inclined surface. In a filter press device, when a close contact state in which the first filter plate and the second filter plate are in close contact is formed, a filtration chamber into which slurry is supplied is formed between the diaphragm sheet and the second recess of the second filter plate. When squeezing the slurry, by supplying a squeezing fluid between the diaphragm sheet and the first recess of the first filter plate, the movable part deforms so as to bulge toward the second filter plate side. A filter plate unit in which, in a state where the diaphragm sheet is removed from the first filter plate, the inner surface of the inclined portion of the diaphragm sheet has a convex portion.

8. The filter plate unit according to claim 7, A filter plate unit in which the convex portion is provided over the entire circumference on the inner surface of the inclined portion of the diaphragm sheet.

9. The filter plate unit according to claim 7, A filter plate unit in which, in a cross section perpendicular to the edge of the boundary between the inclined portion and the fixed portion of the diaphragm sheet, the inner surface of the inclined portion is curved or bent so as to be convex toward the filtration chamber, whereby the convex portion is provided.

10. The filter plate unit according to claim 7, A filter plate unit in which the outer surface of the inclined portion of the diaphragm sheet has a concave portion facing the convex portion.

11. The filter plate unit according to claim 7, A plurality of protrusions are provided on the surface on the second filter plate side at the bottom of the diaphragm sheet. When paying attention to the direction perpendicular to the main surface of the first filter plate in the close contact state, taking the surface on the first filter plate side of the bottom as a reference, the height of the plurality of protrusions is T2 [mm], the distance from the surface on the first filter plate side of the fixed portion to the fixed portion is L1 [mm], the thickness of the fixed portion is T1 [mm], and the distance from the surface on the second filter plate side of the fixed portion to the bottom surface of the second recess of the second filter plate is L2 [mm]. 10 [mm] < T1 + L1 + L2 - T2 < 40 [mm] A filter plate unit that satisfies this condition.

12. A filter plate unit used in a filter press device, a first filter plate provided with a first recess and a peripheral edge portion surrounding the first recess on a main surface, a second filter plate provided with a second recess facing the first recess of the first filter plate and a peripheral edge portion surrounding the second recess on the main surface, a diaphragm sheet disposed between the first filter plate and the second filter plate, comprising: In the first filter plate, a first boss portion protruding from the bottom surface of the first recess is provided, and the end surface of the first boss portion and the bottom surface of the first recess are connected by a boss inclined surface, and the bottom surface of the first recess and the peripheral edge portion are connected by a peripheral edge inclined surface. In the second filter plate, a second boss portion protruding from the bottom surface of the second recess is provided, and the end surface of the second boss portion and the bottom surface of the second recess are connected by a boss inclined surface, and the bottom surface of the second recess and the peripheral edge portion are connected by a peripheral edge inclined surface. The diaphragm sheet has a movable portion along the bottom surface, the peripheral edge inclined surface, and the boss inclined surface of the first recess in the first filter plate, a fixed portion fixed to the peripheral edge portion of the first filter plate, and a boss facing portion fixed to the end surface of the first boss portion. The movable portion has a bottom portion facing the bottom surface of the first recess in the first filter plate, a peripheral edge inclined portion facing the peripheral edge inclined surface, and a boss inclined portion facing the boss inclined surface. In the filter press device, when a close contact state is formed in which the first filter plate and the second filter plate are in close contact, a filtration chamber for supplying slurry is formed between the diaphragm sheet and the second recess of the second filter plate. When squeezing the slurry, by supplying a squeezing fluid between the diaphragm sheet and the first recess of the first filter plate, the movable portion deforms so as to bulge toward the second filter plate side. A filter plate unit in which, with the diaphragm sheet removed from the first filter plate, the inner surface of the boss inclined portion of the diaphragm sheet has a convex portion.

13. A filter press apparatus comprising: The filter plate unit according to any one of claims 1 to 12, a filter plate opening / closing mechanism that selectively forms a close contact state in which the first filter plate and the second filter plate of the filter plate unit are in close contact with each other, and a release state in which the close contact state is released; and a filter press apparatus comprising the same.

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