filter-plate filter

Abstract

The present application provides a filter plate filter which can more effectively suppress leakage of a raw liquid and a filtered liquid passing through a filter material and is highly convenient. The filter plate filter is provided with: a plurality of filter plates (an upper filter plate (2a), a lower filter plate (2b)) arranged with a filter material (1) interposed therebetween; a filter chamber (C) formed between the plurality of filter plates (the upper filter plate (2a), the lower filter plate (2b)); a raw liquid introduction path (3) for introducing a raw liquid (L1) to be filtered into the filter chamber (C); a pressurizing and sealing unit (4) for suppressing leakage of the raw liquid to be filtered and the filtered liquid in the filter chamber (C) to the outside of the filter chamber (C) by applying a sealing pressure to the filter material (1); and a control unit (5) for automatically controlling the sealing pressure in accordance with a change in pressure in the filter chamber (C).

Description

TECHNICAL FIELD

[0001] The present application relates to a filter plate type filter machine. BACKGROUND

[0002] Conventionally, there is a filter plate type filter machine in which a plurality of filter plates, which are provided to be opened and closed, are pressed and attached to each other with a filter medium interposed therebetween to form a filter chamber, and filtration is performed inside the filter chamber (for example, refer to Patent Literature 1).

[0003] A multi-stage horizontal filter plate type filter machine including the configuration described above and the like can automatically and repeatedly perform filtration processing, and is also called a Schneider method.

[0004] Further, there is an invention of a pressure filtration device in which a concentrated material is subjected to compression filtration by the pressure of compressed air in a filter chamber formed by the lower surface of an upper filter frame being attached to the upper surface of a frame body of a lower filter plate via a filter cloth (for example, refer to Patent Literature 2).

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2012-24712

[0008] Patent Literature 2: Japanese Patent No. 2696666 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] The filter plate type filter machine described above forms a filter chamber by pressing and attaching a plurality of filter plates to each other with a filter medium interposed therebetween, and thus, in terms of structure, a gap through which a liquid in the filter chamber can pass to the outside of the filter chamber can be generated on the contact surface of the filter medium and the filter plate.

[0011] In this case, the raw liquid supplied to the filter chamber can sometimes leak to the outside of the filter chamber through the gap described above due to the supply pressure thereof.

[0012] Further, the filtered liquid that has passed through the filter medium can sometimes leak to the outside of the filter chamber from the inside of the filter chamber due to capillary phenomenon generated in the filter medium.

[0013] In order to prevent the situations described above, for example, Patent Literature 2 shows a scheme in which a pair of sealing members are fixed to opposing portions at which the filter cloth of the filter frame and the filter plate are in contact with each other, and sealing is performed.

[0014] However, in the case of actually performing filter plate type filtration, the pressure in the filter chamber is constantly changing, and thus, in a general sealing method such as a sealing member, it is difficult to sufficiently suppress the leakage of the raw liquid and the filtered liquid from the filter chamber.

[0015] The present application has been achieved in view of the above-described problems, and its object is to provide a filter-plate type filter that can more effectively suppress leakage of a raw solution and a filtrate from a filter chamber and that is highly convenient.

[0016] Solution to the problem

[0017] To solve the above-described problems, the present application is a filter-plate type filter that causes a plurality of filter plates that are provided to be opened and closed freely to be pressed and attached to each other with a filter medium interposed therebetween to form a filter chamber, and performs filtration inside the filter chamber, wherein the filter-plate type filter includes: a plurality of filter plates that are arranged with the filter medium interposed therebetween; a filter chamber that is formed between the filter plates; a raw solution introduction path that introduces a raw solution including a solid component to be filtered into the filter chamber; a pressurized sealing unit that suppresses leakage of the raw solution and a filtrate inside the filter chamber to the outside of the filter chamber by applying a sealing pressure to the filter medium; and a control unit that automatically controls the sealing pressure in accordance with a change in a pressure inside the filter chamber.

[0018] In a preferred aspect of the present application, the pressurized sealing unit applies the sealing pressure to the filter medium by supplying a sealing fluid to the filter medium.

[0019] In a preferred aspect of the present application, the pressurized sealing unit applies the sealing pressure to the filter medium by supplying the sealing fluid to the filter medium from a plurality of different directions.

[0020] In a preferred aspect of the present application, the pressurized sealing unit has a pressurized sealing portion main body formed of an elastic body, and applies the sealing pressure to the filter medium by deforming the pressurized sealing portion main body by supplying a sealing fluid.

[0021] In a preferred aspect of the present application, the control unit automatically controls the sealing pressure to suppress leakage of the raw solution and the filtrate to be filtered to the outside of the filter chamber.

[0022] In a preferred aspect of the present application, the control unit automatically controls the sealing pressure to suppress intrusion of the sealing fluid supplied to the filter medium into the filter chamber.

[0023] In a preferred aspect of the present application, the control unit controls the sealing pressure in such a manner that a pressure difference between the pressure inside the filter chamber and the sealing pressure is maintained at a prescribed pressure difference value.

[0024] In a preferred aspect of the present application, the pressurized sealing unit has a first pressure sensing unit that senses a first pressure inside the raw solution introduction path, and the control unit controls the sealing pressure on the basis of a pressure inside the filter chamber that is estimated from the first pressure inside the raw solution introduction path.

[0025] In a preferred embodiment of the present application, the pressurizing and sealing unit has a fluid supply path that supplies sealing fluid to the filter medium and a second pressure sensing unit that senses a second pressure in the fluid supply path, and the control unit controls the sealing pressure based on the filter chamber pressure estimated from the first pressure sensed by the first pressure sensing unit in the raw solution introduction path and the second pressure sensed by the second pressure sensing unit in the fluid supply path.

[0026] In a preferred embodiment of the present application, the filter plate type filter has a plurality of filter chambers, the raw solution introduction path has branched introduction paths that introduce the raw solution to the plurality of filter chambers, respectively, the first pressure sensing unit senses a first pressure in the raw solution introduction path on the upstream side from the branching points of the branched introduction paths, and the control unit controls the sealing pressure based on the filter chamber pressure estimated from the first pressure in the raw solution introduction path.

[0027] In a preferred embodiment of the present application, the pressurizing and sealing unit has a fluid supply path that supplies sealing fluid to the filter medium and a second pressure sensing unit that senses a second pressure in the fluid supply path, and the fluid supply path includes branched supply paths that supply sealing fluid to the plurality of filter media arranged in the plurality of filter chambers, respectively, the second pressure sensing unit senses a second pressure in the fluid supply path on the upstream side from the branching points of the branched supply paths, and the control unit controls the sealing pressure based on the first pressure in the raw solution introduction path and the second pressure in the fluid supply path.

[0028] In a preferred embodiment of the present application, the control unit controls the sealing pressure in such a manner that the pressure difference between the first pressure in the raw solution introduction path and the second pressure in the fluid supply path is maintained at a predetermined pressure difference value.

[0029] Further, the present application is a filtration method that is performed using a filter plate type filter having a plurality of filter plates arranged with a filter medium interposed therebetween and filter chambers formed between the filter plates, and the filtration method includes:

[0030] a pressurizing and sealing step of applying a sealing pressure to the filter medium, and a pressure control step of automatically controlling the sealing pressure to suppress leakage of a raw solution including a solid component to be filtered and a filtrate introduced into the filter chamber to the outside of the filter chamber.

[0031] In a preferred embodiment of the present application, in the pressurizing and sealing step, the sealing pressure is applied to the filter medium by supplying sealing fluid to the filter medium.

[0032] In a preferred embodiment of the present application, in the pressurizing and sealing step, the sealing pressure is applied to the filter medium by supplying the sealing fluid to the filter medium from a plurality of different directions.

[0033] In the present application, in the pressurizing and sealing step, the sealing pressure is applied to the filter material by deforming the elastic body by supplying a sealing fluid.

[0034] In the present application, in the pressure control step, the sealing pressure is automatically controlled to suppress leakage of the raw solution and the filtrate outside the filter chamber.

[0035] In the present application, in the pressure control step, the sealing pressure is automatically controlled to suppress intrusion of a sealing fluid supplied to the filter material into the filter chamber.

[0036] Effects of the Invention

[0037] According to the present application, a filter plate type filter can be provided which effectively suppresses leakage of a raw solution and a filtrate from a filter chamber and is highly convenient. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a view showing a filter plate type filter of an embodiment of the present application.

[0039] Figure 2 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0040] Figure 3 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0041] Figure 4 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0042] Figure 5 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0043] Figure 6 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0044] Figure 7 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0045] Figure 8 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0046] Figure 9 is a view showing the flow of fluid and pressure inside a filter plate type filter of an embodiment of the present application.

[0047] Figure 10is an A-A' line cross-sectional view of a filter plate type filter of another embodiment of the present application.

[0048] Figure 11 is an A-A' line cross-sectional view of a filter plate type filter of another embodiment of the present application. DETAILED DESCRIPTION

[0049] Hereinafter, a filter plate type filter of an embodiment of the present application will be described using Figures 1-9

[0050] Figure 9 is a perspective view showing one example of the overall configuration of a horizontal filter plate type filter.

[0051] Figure 9 The horizontal filter plate type filter 9 exemplified in FIG. 1 has upper filter plates 92a, a plurality of intermediate filter plates 92b, 92b, 92b, and a lower filter plate 92c, which are stacked in the vertical direction with guide rods (not shown) that serve as guides for vertical movement inserted therethrough.

[0052] Further, filter chambers (filter rooms) in which cavities are not shown are formed between the upper filter plates 92a and the intermediate filter plates 92b, between the intermediate filter plates 92b and the intermediate filter plates 92b, and between the intermediate filter plates 92b and the lower filter plate 92c.

[0053] The upper filter plates 92a have a function of receiving a raw liquid containing a filtered solid component that is a filtering target, the lower filter plate 92c has a function of recovering a filtered liquid (filtrate), and the intermediate filter plates 92b, 92b, 92b each have both of these functions. These are collectively referred to as a filter plate stack 92.

[0054] Further, filter material racks fr are arranged in the spaces adjacent to the filter plate stack 92, and a plurality of filter material rollers 91A, 91B, 91C, 91D are rotatably provided.

[0055] Filter materials 91a, 91b, 91c, 91d are wound in a roll shape on the filter material rollers 91A, 91B, 91C, 91D, and become a supply device that supplies the filter materials 91a, 91b, 91c, 91d from one to the other on the upper surfaces of the respective filter plates (intermediate filter plates 92b, 92b, 92b, lower filter plate 92c).

[0056] Further, a filter material extractor (Extractor) fe is arranged in the space adjacent to the filter plate stack 92.

[0057] ​When the filter medium is replaced, the filter medium 91a, 91b, 91c, 91d is pulled out from the upper surface of each filter plate (the intermediate filter plates 92b, 92b, 92b, the lower filter plate 92c) by the ejection roller device er, and ejected to the outside of the machine.

[0058] Next, the operation of the horizontal filter plate filter 9 will be described.

[0059] First, each filter chamber is made in a closed state by pressing the stacked filter plates (the upper filter plate 92a, the intermediate filter plates 92b, 92b, 92b, the lower filter plate 92c) using the upper pressing jack pj. The raw material is supplied to the filter medium 91a, 91b, 91c, 91d of each filter chamber made in a closed state through the raw material introduction path 93, and the filtration process is started.

[0060] When the filtration process progresses and the filtration resistance of the filter medium 91a, 91b, 91c, 91d gradually increases and filtration becomes difficult, the supply of the raw material is stopped, and the pressurized state caused by the pressing jack pj is released.

[0061] Then, the upper filter plate 92a and the plurality of intermediate filter plates 92b, 92b, 92b are pulled upward, and gaps are formed between the upper filter plate 92a and the intermediate filter plate 92b, between the intermediate filter plates 92b and 92b, and between the intermediate filter plate 92b and the lower filter plate 92c, and the fastening state of the filter medium 91a, 91b, 91c, 91d is released.

[0062] At this time, the filter medium extractor fe moves the filter medium 91a, 91b, 91c, 91d released from the fastened state, and thereby the filter medium 91a, 91b, 91c, 91d disposed between the upper filter plate 92a and the intermediate filter plate 92b, between the intermediate filter plates 92b and 92b, and between the intermediate filter plate 92b and the lower filter plate 92c is replaced from the used portion to the unused portion.

[0063] Note that the horizontal filter plate filter 9 is configured to have a plurality of stages with each stage having a filter area of an appropriate size in order to reduce the installation area, and the overall filter area is increased to achieve the required filtration capacity, but the basic configuration and the effects are the same in a single stage.

[0064] <Embodiment 1>

[0065] Figure 1 is a sectional view showing the structure of a filter plate filter X1 according to an embodiment of the present application. As shown in Figure 1 The filter plate filter X1 has a filter medium 1, a plurality of filter plates (an upper filter plate 2a, a lower filter plate 2b), a filter chamber C, a raw material introduction path 3, a pressurized sealing unit 4, and a control unit 5. Note that the filter chamber C is formed by assembling the upper filter plate 2a and the lower filter plate 2b with the filter medium 1 interposed therebetween.

[0066] The filter material 1 is sandwiched by a plurality of filter plates (upper filter plate 2a, lower filter plate 2b) in a manner to communicate the inside and outside of the filter chamber C.

[0067] The upper filter plate 2a and the lower filter plate 2b form the filter chamber C with the filter material 1 therebetween.

[0068] The raw material introduction path 3 leads from the upper filter plate 2a to the inside of the filter chamber C. Note that the piping of the raw material introduction path 3 is connected to the upper filter plate 2a as shown in the enlarged view of the dialog box in Figure 1 . The same applies to the connection of other piping to the filter plates.

[0069] The pressurizing and sealing unit 4 has a first pressure sensing unit 41, a second pressure sensing unit 42, a fluid supply path 43, and a pressure regulating unit 44.

[0070] The first pressure sensing unit 41, which is preferably a pressure sensor or the like, is provided to the raw material introduction path 3, as will be described later, to sense the first pressure P1 in the raw material introduction path 3.

[0071] The second pressure sensing unit 42, which is preferably a pressure sensor or the like, is provided to the fluid supply path 43, as will be described later, to sense the second pressure P2 in the supply path main body 431 (to be described later) of the fluid supply path 43.

[0072] The fluid supply path 43 includes a supply path main body 431 and a sealing flow path (pressing path) 432.

[0073] The sealing flow path (pressing path) 432 is formed to surround the periphery of the filter chamber C (details will be described later).

[0074] The pressure regulating unit 44, which is preferably a regulating valve or the like that regulates the flow rate of fluid flowing into the fluid supply path 43, as will be described later, is capable of regulating the second pressure P2 in the fluid supply path 43.

[0075] The control unit 5 is connected to the first pressure sensing unit 41, the second pressure sensing unit 42, and the pressure regulating unit 44 at least through a wired or wireless signal transmission unit. The control unit 5 receives pressure sensing signals from the first pressure sensing unit 41 and the second pressure sensing unit 42, and based on the signals, sends signals to the pressure regulating unit 44 to automatically control the pressure regulating unit 44.

[0076] Figure 3 is an A-A' line cross-sectional view of the filter plate type filter X1 shown in Figure 1 . As shown in Figure 1 , the sealing flow path (pressing path) 432 is formed on the lower surface of the upper filter plate 2a in a manner to come into contact with the filter material 1 when the filter material 1 is sandwiched by a plurality of filter plates (upper filter plate 2a, lower filter plate 2b), and asFigure 3 is formed so as to surround the periphery of the filter chamber C.

[0077] That is, the sealing fluid supplied through the supply path main body 431 passes through the sealing flow path (pressing path) 432 of the fluid supply path 43, and is spread over the portion of the filter medium 1 located at the outer periphery of the filter chamber C, as a result of which the sealing pressure is applied to this portion of the filter medium 1.

[0078] Note that, in the above-described embodiment, the supply path main body 431 is provided as one, but the present application is not limited thereto, and as shown in FIG. 6, for example, an additional second supply path main body 431(2) can be provided from a different direction from the first supply path main body 431(1) so that the sealing fluid SF is spread without deviation in the sealing flow path (pressing path) 432. That is, the pressurized sealing unit 4 can apply the sealing pressure to the filter medium without deviation by supplying the sealing fluid SF to the filter medium from a plurality of different directions. Figure 3 Figure 4 Note that, in the above-described embodiment, the supply path main body 431 is provided as one, but the present application is not limited thereto, and as shown in FIG. 6, for example, an additional second supply path main body 431(2) can be provided from a different direction from the first supply path main body 431(1) so that the sealing fluid SF is spread without deviation in the sealing flow path (pressing path) 432. That is, the pressurized sealing unit 4 can apply the sealing pressure to the filter medium without deviation by supplying the sealing fluid SF to the filter medium from a plurality of different directions.

[0079] Note that, the additional supply path main body 431 can be a scheme including one or more (two or more).

[0080] For example, in addition to the scheme shown in FIG. 6 in which one additional supply path main body 431 is provided, a scheme in which two or three additional supply path main bodies 431 are provided as shown in FIG. 7 can be employed. Figure 4 Figure 10 , Figure 11

[0081] Further, in this case, it is preferable that the plurality of supply path main bodies 431 be provided at equal intervals along the outer periphery of the sealing flow path (pressing path) 432, and that the sealing fluid SF be supplied equally.

[0082] Hereinafter, in Embodiments 1 to 4 described in the present specification, unless otherwise specified, the upper filter plate 2a, the intermediate filter plates 2b-1, 2b-2, 2b-3 are provided with the same fluid supply path 43 as described above (in the case of the intermediate filter plates 2b-1, 2b-2, 2b-3, the branch supply paths 431a, 431b, 431c, 431d), and a description thereof is given in advance.

[0083] Figure 2 is a sectional view showing the flow of fluid in the filter plate type filter X1 of an embodiment of the present application.

[0084] Note that, the raw liquid is denoted as L1, the filtrate is denoted as L2, and the sealing fluid is denoted as SF, and the flow of each fluid is indicated by a respective arrow.

[0085] As shown in FIG. 1, the raw liquid L1 is introduced into the filter chamber C through the raw liquid introduction path 3, and is filtered through the filter medium 1. Figure 2 ​​​​

[0086] The filtrate L2 obtained by filtration is discharged to the outside of the filter chamber C through the discharge path 3b.

[0087] The sealing fluid SF is a fluid supplied to the sealing flow path (pressing path) 432 through the supply path main body 431. By supplying the sealing fluid SF to the sealing flow path (pressing path) 432, the sealing portion of the filter element 1 is flattened, and the minute gap (leakage path of the raw liquid Ll) generated at the face where the filter element 1 contacts the upper filter plate 2a, the inside of the filter element 1 (leakage path of the filtrate L2), and the minute gap (leakage path of the filtrate L2) generated at the face where the filter element 1 contacts the lower filter plate 2b are blocked, and thus, the leakage of the raw liquid Ll and the filtrate L2 is suppressed.

[0088] Note that, as the sealing fluid SF, for example, nitrogen is preferably used, but compressed air, other inert gas can also be used. Further, the supply source of the sealing fluid SF is assumed to be, for example, a sealing gas supply unit such as a gas cylinder.

[0089] By the flow of each fluid described above, a pressure is applied to each inside of the raw liquid introduction path 3, the supply path main body 431, the filter chamber C, and the sealing flow path (pressing path) 432. In the present specification, the pressure applied to the inside of the raw liquid introduction path 3 is defined as the first pressure Pl, the pressure applied to the inside of the supply path main body 431 is defined as the second pressure P2, the pressure applied to the inside of the filter chamber C is defined as the filter chamber pressure P3, and the pressure applied to the inside of the sealing flow path (pressing path) 432 is defined as the sealing pressure P4.

[0090] The object of the present application is to prevent the leakage of the raw liquid and the filtrate from the filter chamber C by achieving the balance between the filter chamber pressure P3 and the sealing pressure P4.

[0091] Therefore, it is ideal to directly measure the filter chamber pressure P3 and the sealing pressure P4, but the filter chamber pressure P3 and the sealing pressure P4 are difficult to measure in terms of position. Therefore, the first pressure Pl and the second pressure P2, which are comparatively easy to measure, are measured, and the relationship between the filter chamber pressure P3 and the sealing pressure P4 is estimated based on them.

[0092] Specifically, the control unit 5 estimates the filter chamber pressure P3 of the filter chamber C based on the first pressure Pl sensed by the first pressure sensing unit 41.

[0093] Note that, "estimating" here includes directly regarding the sensed first pressure Pl as the filter chamber pressure P3 of the filter chamber C, and calculating the filter chamber pressure P3 of the filter chamber C by performing a prescribed arithmetic processing on the sensed first pressure Pl.

[0094] Next, the control unit 5 automatically operates the pressure adjusting unit 44 based on the estimated filter chamber internal pressure P3 of the filter chamber C and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42. Note that the second pressure P2 can also be considered to be the same value as the seal pressure P4 in the structure of this embodiment, and in addition, the seal pressure P4 can also be calculated by performing a prescribed operation process on the second pressure P2.

[0095] The control unit 5 constantly monitors the second pressure P2 via the second pressure sensing unit 42, and constantly adjusts the operation amount of the pressure adjusting unit 44 so that the pressure difference between the filter chamber internal pressure P3 and the second pressure P2 is a prescribed pressure difference value.

[0096] As a result, the balance between the filter chamber internal pressure P3 estimated from the first pressure PI in the raw material introduction path 3 and the seal pressure P4 estimated from the second pressure P2 in the fluid supply path 43 is automatically adjusted. Through this adjustment, the leakage of the raw material LI through the gap generated at the contact surface of the filter material 1 and the upper filter plate 2a, and the leakage of the filtered liquid L2 through the inside of the filter material 1 due to capillary phenomenon can be more effectively suppressed.

[0097] Note that as the control unit 5, a control unit that can achieve the above-described functions, such as a control panel for industrial equipment, a computer device, etc., is not limited in form.

[0098] <Embodiment 2>

[0099] Figure 5 is a cross-sectional view of a filter plate type filter X2 that is another embodiment of the present application.

[0100] As shown in Figure 5 , the filter plate type filter X2 is provided with: a plurality of filter materials la, lb, lc, Id; a plurality of filter plates (upper filter plate 2a, intermediate filter plates 2b-1, 2b-2, 2b-3, lower filter plate 2b; a plurality of filter chambers CI, C2, C3, C4; a raw material introduction path 3; a pressurizing seal unit 4; and a control unit 5. Hereinafter, the description that is repeated with the description of the filter plate type filter XI will be appropriately omitted, and only the characteristic portions of the filter plate type filter X2 will be described.

[0101] The raw material introduction path 3 has branch introduction paths 31a, 31b, 31c, 31d that pass from the upper filter plate 2a, the intermediate filter plates 2b-1, 2b-2, 2b-3 to each of the filter chambers CI, C2, C3, C4, and can introduce the raw material LI into each of the filter chambers CI, C2, C3, C4.

[0102] In this specification, the pressure applied to each of the filter chambers CI, C2, C3, C4 by the raw material LI will be defined as the filter chamber internal pressure P3a, P3b, P3c, P3d, respectively.

[0103] The fluid supply path 43 includes branch supply paths 431a, 431b, 431c, 431d leading from the upper filter plate 2a, the intermediate filter plates 2b-1, 2b-2, 2b-3 to the respective filter chambers C1, C2, C3, C4, and sealing flow paths (pressing paths) 432a, 432b, 432c, 432d.

[0104] In the present specification, the pressure applied to each of the sealing flow paths (pressing paths) 432a, 432b, 432c, 432d by the sealing fluid SF will be defined as the sealing pressure P4a, P4b, P4c, P4d, respectively.

[0105] The sealing flow paths (pressing paths) 432a, 432b, 432c, 432d are supplied with the sealing fluid SF through the branch supply paths 431a, 431b, 431c, 431d, respectively, whereby the sealing portions of the plurality of filter materials 1a, 1b, 1c, 1d are pressed by the sealing pressures P4a, P4b, P4c, P4d, and the leakage paths of the crude liquid L1 and the filtrate L2 are blocked, so that the leakage of the crude liquid and the filtrate is suppressed.

[0106] The first pressure sensing unit 41 preferably uses a pressure sensor or the like and is capable of sensing the first pressure P1 in the crude liquid introduction path 3 on the upstream side of the branch point B1 of the branch introduction path 31a, 31b, 31c, 31d and sending a pressure sensing signal to the control unit 5.

[0107] The second pressure sensing unit 42 preferably uses a pressure sensor or the like and is capable of sensing the second pressure P2 in the fluid supply path 43 on the upstream side of the branch point B2 of the branch supply path 431a, 431b, 431c, 431d and sending a pressure sensing signal to the control unit 5.

[0108] The control unit 5 controls the sealing pressures P4a, P4b, P4c, P4d based on the first pressure P1 in the crude liquid introduction path 3 sensed by the first pressure sensing unit 41 and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42.

[0109] Here, in the structure of the present embodiment, the first pressure P1 in the crude liquid introduction path 3 sensed by the first pressure sensing unit 41 can be assumed to be the respective filter chamber pressures P3a, P3b, P3c, P3d of the plurality of filter chambers C1, C2, C3, C4, and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42 can be assumed to be the respective internal pressures (i.e., the sealing pressures P4a, P4b, P4c, P4d) of the plurality of branch supply paths 431a, 431b, 431c, 431d.

[0110] Therefore, the control of the seal pressure P4a, P4b, P4c, P4d based on the first pressure P1 in the raw solution introduction path 3 sensed by the first pressure sensing unit 41 and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42 is the control of the seal pressure P4a, P4b, P4c, P4d based on the filter chamber pressure P3a, P3b, P3c, P3d and the seal pressure P4a, P4b, P4c, P4d, whereby, as the entire filter, the leakage of the filtrate through the filter medium 1 and the excessive supply of the seal fluid caused by the capillary phenomenon that can occur in each filter chamber are minimized.

[0111] Further, by maintaining the pressure difference between the first pressure P1 in the raw solution introduction path 3 sensed by the first pressure sensing unit 41 and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42 at a prescribed pressure difference value, the control of minimizing the leakage of the filtrate through the filter medium 1 and the excessive supply of the seal fluid caused by the capillary phenomenon that can occur in each filter chamber is performed more robustly.

[0112] Therefore, the first pressure sensing unit 41 senses the first pressure P1 in the raw solution introduction path 3 on the upstream side from the branch point B1, and the second pressure sensing unit 42 senses the second pressure P2 in the fluid supply path 43 on the upstream side from the branch point B2, so it is not necessary to provide a sensor in each of the plurality of filter chambers C1, C2, C3, C4 and each of the plurality of branch supply paths 431a, 431b, 431c, 431d, and it is also possible to minimize the leakage of the raw solution and the filtrate and the excessive supply of the seal fluid in each part in terms of structure.

[0113] <Embodiment 3>

[0114] Figure 6 is a cross-sectional view of a filter plate type filter X3 which is another embodiment of the present application.

[0115] As shown in Figure 6 , the filter plate type filter X3 is provided with a filter medium 1, a plurality of filter plates (upper filter plate 2a, lower filter plate 2b), a filter chamber C, a raw solution introduction path 3, a pressurizing seal unit 4, and a control unit 5. Hereinafter, the description that is repeated with the description of the filter plate type filter X1 is appropriately omitted, and only the characteristic part of the filter plate type filter X3 is described.

[0116] The pressurizing seal unit 4 has a pressurizing seal portion main body 45 formed of an elastic body, and the end portion of the pressurizing seal portion main body 45 is fixed in the seal flow path (pressing path) 432 of the upper filter plate 2a. Alternatively, as the pressurizing seal portion main body 45, a pressurizing seal portion main body in which an elastic material is formed in a tubular shape can be used.

[0117] That is, as shown in Figure 7As shown, the sealing fluid SF supplied from the fluid supply path 43 causes the pressurized sealing part body 45, which undergoes elastic deformation, to flex downward in the figure. As a result, the pressurized sealing part body 45 can apply a sealing pressure P4 to the part in contact with the filter material 1, thereby flattening the filter material 1 to achieve a seal.

[0118] That is, the pressure sealing unit 4 can apply sealing pressure to the filter material 1 by supplying sealing fluid SF to the pressure sealing part body 45, thereby deforming the pressure sealing part body 45.

[0119] It should be noted that in this embodiment, the sealing fluid SF does not come into contact with the original liquid L1 and the filtrate L2. Therefore, in addition to gases such as nitrogen, compressed air, and inert gases, liquids such as pressurized oil can also be used as the sealing fluid SF.

[0120] Here, the control unit 5 controls the sealing pressure P4 based on the first pressure P1 in the original liquid inlet path 3 sensed by the first pressure sensing unit 41 and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42.

[0121] Specifically, the control unit 5 controls the sealing pressure P4 in a manner that maintains the pressure difference between the first pressure P1 in the raw liquid introduction path 3 sensed by the first pressure sensing unit 41 and the second pressure P2 in the fluid supply path 43 sensed by the second pressure sensing unit 42 at a predetermined pressure difference value.

[0122] In this way, the pressure P3 in the filter chamber, which is estimated based on the first pressure P1 in the raw liquid inlet path 3, and the sealing pressure P4, which is estimated based on the second pressure P2 in the fluid supply path 43, can be automatically adjusted to more effectively and accurately suppress the leakage of raw liquid and filtrate from the filter chamber C.

[0123] It should be noted that the configuration of Embodiment 3 described above can also be combined with Embodiment 2, and the filter chamber C can be set as multiple sections.

[0124] <Implementation Method 4>

[0125] Figure 8 of (a), Figure 8 (b) is a cross-sectional view of a plate filter X4 according to another embodiment of the present invention.

[0126] like Figure 8 of (a), Figure 8 As shown in (b), the plate filter X4 includes filter media 1, multiple filter plates (upper filter plate 2a, lower filter plate 2b), filter chamber C, raw liquid inlet 3, pressure sealing unit 4, and control unit 5. Hereinafter, descriptions that overlap with those of the plate filter X1 will be omitted, and only the characteristic parts of the plate filter X4 will be described.

[0127] The control unit 5 has a raw liquid chamber 51 communicating with the raw liquid inlet passage 3, a fluid chamber 52 communicating with the fluid supply passage 43, and a pressure transmission unit 53. The raw liquid chamber 51 and the fluid chamber 52 are separated in the middle by the pressure transmission unit 53 formed of an elastomer and are connected.

[0128] That is, between the raw liquid chamber 51 and the fluid chamber 52, the raw liquid L1 and the sealing fluid SF will not interact or mix, but the first pressure P1 in the raw liquid inlet path 3 and the second pressure P2 in the fluid supply path 43 will be transmitted to each other.

[0129] like Figure 8 As shown in (a), when the first pressure P1 in the raw liquid inlet path 3 and then the pressure P3 in the filter chamber are greater than the second pressure P2 in the fluid supply path 43 and then greater than the sealing pressure P4, the pressure transmission unit 53 deforms toward the fluid chamber 52.

[0130] As a result, the volume of the sealed fluid SF side, including the fluid chamber 52 and the fluid supply path 43, is reduced. Therefore, if the fluid flow rate is fixed, the second pressure P2 in the fluid supply path 43 increases accordingly, and the sealing pressure P4 increases.

[0131] like Figure 8 As shown in (b), when the first pressure P1 in the raw liquid inlet path 3 and then the pressure P3 in the filter chamber are less than the second pressure P2 in the fluid supply path 43 and then less than the sealing pressure P4, the pressure transmission unit 53 deforms toward the raw liquid chamber 51.

[0132] As a result, the volume of the space on the sealed fluid side, including the fluid chamber 52 and the fluid supply path 43, expands. Therefore, if the fluid flow rate is constant, the second pressure P2 in the fluid supply path 43 decreases accordingly, and consequently the sealing pressure P4 decreases.

[0133] Therefore, even the control unit 5 with the above-described configuration can automatically control the second pressure P2 in the fluid supply path 43 based on the change in the first pressure P1 in the original liquid inlet path 3, and further based on the change in the pressure P3 in the filter chamber, and thus automatically control the sealing pressure P4.

[0134] It should be noted that by installing a pressure reducing valve RV in the raw liquid inlet path 3, which is downstream of the branch point B3 and communicates with the upper filter plate 2a, or by installing a pressure pump BP in the fluid supply path 43, which is downstream of the branch point B4 and communicates with the upper filter plate 2a, a fixed pressure difference can be generated between the pressure P3 and the sealing pressure P4 in the filter chamber.

[0135] Further, the configuration of Embodiment 4 as described above can also be combined with Embodiment 2, and the filter chamber C is provided in multiple stages. In this case, the branch point B3 is preferably provided on the upstream side of the branch point Bl, and the branch point B4 is preferably provided on the upstream side of the branch point B2.

[0136] According to the filter plate type filter X1 to X4 of Embodiments 1 to 4 of the present application, the control unit 5 automatically controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) in accordance with the change in the filter chamber internal pressure P3 (or P3a, P3b, P3c, P3d) to suppress the leakage of the raw solution LI and the filtered solution L2 in the filter chamber C (or Cl, C2, C3, C4) to the outside of the filter chamber C (or Cl, C2, C3, C4), and thus the leakage of the raw solution LI and the filtered solution L2 can be more effectively suppressed.

[0137] According to the filter plate type filter X1 to X4 of Embodiments 1 to 4 of the present application, the pressurizing and sealing unit 4 applies the sealing pressure P4 (or P4a, P4b, P4c, P4d) to the filter material 1 (or 1a, 1b, 1c, 1d) by supplying the sealing fluid SF to the filter material 1 (or 1a, 1b, 1c, 1d), and thus the leakage path of the raw solution LI or the filtered solution L2 at the contact portion of the filter material 1 (or 1a, 1b, 1c, 1d) with each filter plate and the leakage path of the filtered solution L2 inside the filter material 1 (or 1a, 1b, 1c, 1d) are sealed by the sealing fluid SF, and the leakage of the raw solution LI and the filtered solution L2 can be more effectively suppressed.

[0138] According to the filter plate type filter X1 to X4 of Embodiments 1 to 4 of the present application, the pressurizing and sealing unit 4 applies the sealing pressure P4 (or P4a, P4b, P4c, P4d) to the filter material 1 (or 1a, 1b, 1c, 1d) by supplying the sealing fluid SF to the filter material 1 (or 1a, 1b, 1c, 1d) from a plurality of different directions, and thus the sealing pressure P4 (or P4a, P4b, P4c, P4d) is applied to the filter material 1 (or 1a, 1b, 1c, 1d) without deviation, and the leakage of the raw solution LI and the filtered solution L2 can be more effectively suppressed.

[0139] According to the filter plate type filter X1 to X4 of Embodiments 1 to 4 of the present application, the control unit 5 automatically controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) to suppress the leakage of the raw solution LI and the filtered solution L2 to the outside of the filter chamber C (or Cl, C2, C3, C4), and thus not only the leakage of the raw solution LI and the filtered solution L2 can be suppressed, but also the excessive supply of the sealing fluid SF can be suppressed.

[0140] The filter plate type filter X1 to X4 according to Embodiments 1 to 4 of the present application controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) by the control unit to suppress the invasion of the sealing fluid SF supplied to the filter material 1 (or 1a, 1b, 1c, 1d) into the filter chamber C (or C1, C2, C3, C4), and thus can not only prevent the leakage of the raw liquid L1 and the filtered liquid L2, but also prevent the decrease in the filtration accuracy and the decrease in the filter quality caused by the invasion of the sealing fluid SF into the filter chamber C (or C1, C2, C3, C4).

[0141] The filter plate type filter X1 to X4 according to Embodiments 1 to 4 of the present application controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) by the control unit 5 to maintain the pressure difference between the filter chamber pressure P3 (or P3a, P3b, P3c, P3d) and the sealing pressure P4 (or P4a, P4b, P4c, P4d) at a predetermined pressure difference value, and thus can perform robust control even for a large pressure variation.

[0142] The filter plate type filter X1 to X4 according to Embodiments 1 to 4 of the present application controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) by the control unit based on the filter chamber pressure P3 (or P3a, P3b, P3c, P3d) estimated from the first pressure P1 in the raw liquid introduction path 3, and thus can simplify the configuration of each filter plate without providing a sensing unit in the filter chamber C (or C1, C2, C3, C4).

[0143] The filter plate type filter X1 to X4 according to Embodiments 1 to 4 of the present application controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) by the control unit based on the filter chamber pressure P3 (or P3a, P3b, P3c, P3d) estimated from the first pressure P1 sensed by the first pressure sensing unit 41 and the second pressure P2 sensed by the second pressure sensing unit 42 in the fluid supply path 43, and thus can perform more accurate sealing pressure control using the first pressure P1 and the second pressure P2, and further improve the leakage suppression effect.

[0144] The method of using the filter plate type filter X1 to X4 according to Embodiments 1 to 4 of the present application controls the sealing pressure P4 (or P4a, P4b, P4c, P4d) in the pressure control step based on the variation of the filter chamber pressure P3 (or P3a, P3b, P3c, P3d) to suppress the leakage of the filtered raw liquid and the filtered liquid to the outside of the filter chamber C (or C1, C2, C3, C4), and thus can more effectively suppress the leakage of the raw liquid L1 and the filtered liquid L2.

[0145] According to the method of using the filter plate type filter X1 to X4 of the embodiments 1 to 4 of the present application, in the pressurizing and sealing step, the sealing pressure P4 (or P4a, P4b, P4c, P4d) is applied to the filter material 1 (or 1a, 1b, 1c, 1d) by supplying the sealing fluid SF to the filter material 1 (or 1a, 1b, 1c, 1d), so that the leakage path of the raw material L1 or the filtrate L2 at the contact portion of the filter material 1 (or 1a, 1b, 1c, 1d) with each filter plate and the leakage path of the filtrate L2 inside the filter material 1 (or 1a, 1b, 1c, 1d) are sealed by the sealing fluid SF, and the leakage of the raw material L1 and the filtrate L2 can be more effectively suppressed.

[0146] According to the method of using the filter plate type filter X1 to X4 of the embodiments 1 to 4 of the present application, in the pressurizing and sealing step, the sealing pressure P4 (or P4a, P4b, P4c, P4d) is applied to the filter material 1 (or 1a, 1b, 1c, 1d) by supplying the sealing fluid SF to the filter material 1 (or 1a, 1b, 1c, 1d) from a plurality of different directions, so that the sealing pressure P4 (or P4a, P4b, P4c, P4d) is applied to the filter material 1 (or 1a, 1b, 1c, 1d) without deviation, and the leakage of the raw material L1 and the filtrate L2 can be more effectively suppressed.

[0147] According to the method of using the filter plate type filter X1 to X4 of the embodiments 1 to 4 of the present application, in the pressure control step, the sealing pressure P4 (or P4a, P4b, P4c, P4d) is automatically controlled to suppress the leakage of the raw material L1 and the filtrate L2 outside the filter chamber C (or C1, C2, C3, C4), so that not only the leakage of the raw material L1 and the filtrate L2 can be suppressed, but also the excessive supply of the sealing fluid SF can be suppressed.

[0148] According to the method of using the filter plate type filter X1 to X4 of the embodiments 1 to 4 of the present application, in the pressure control step, the sealing pressure P4 (or P4a, P4b, P4c, P4d) is automatically controlled to suppress the invasion of the sealing fluid supplied to the filter material 1 (or 1a, 1b, 1c, 1d) into the filter chamber C (or C1, C2, C3, C4), so that not only the leakage of the raw material L1 and the filtrate L2 can be prevented, but also the decrease in the filtration accuracy and the decrease in the filtration quality caused by the invasion of the sealing fluid SF into the filter chamber C (or C1, C2, C3, C4) can be prevented.

[0149] According to the filter plate type filter X2 of the embodiment 2 of the present application, the first pressure sensing unit 41 senses the first pressure P1 in the raw material introduction path 3 on the upstream side of the branch point B1 of the branch introduction paths 31a, 31b, 31c, 31d, so that not only the processing capacity of the device is improved by providing a plurality of filter chambers, but also the number of required sensing units is small, and thus the constitution becomes simple.

[0150] The filter plate type filter X2 according to Embodiment 2 of the present application, the second pressure sensing unit 42 senses the second pressure P2 in the fluid supply path on the upstream side from the branch point B2 of the branch supply paths 431a, 431b, 431c, 431d, and thus not only is the processing capacity of the device improved by providing a plurality of filter chambers, but also the number of sensing units required is small, and thus the configuration is simple.

[0151] Further, the seal pressures P4a, P4b, P4c, P4d are controlled based on the first pressure P1 in the raw material introduction path 3 on the upstream side from the branch point B1 of the branches 31a, 31b, 31c, 31d, and the second pressure P2 in the fluid supply path 43 on the upstream side from the branch point B2 of the branches 431a, 431b, 431c, 431d, and thus, as a whole, the filter, leakage of the raw material L1 and the filtered liquid L2, and excessive supply of the seal fluid SF, which can occur in each filter chamber, are minimized.

[0152] The filter plate type filter X2 according to Embodiment 2 of the present application, the control unit controls the seal pressures P4a, P4b, P4c, P4d in such a manner that the pressure difference between the first pressure P1 in the raw material introduction path 3 and the second pressure P2 in the fluid supply path 43 is maintained at a prescribed pressure difference value, and thus seal pressure control that robustly minimizes leakage of the raw material L1 and the filtered liquid L2, and excessive supply of the seal fluid SF, which can occur in each filter chamber, is performed.

[0153] The filter plate type filter X3 according to Embodiment 3 of the present application, the pressurizing seal unit 4 has a pressurizing seal portion main body 45 formed of an elastic body, and the seal pressure P4 is applied to the filter material 1 by deforming the pressurizing seal portion main body 45 by supplying the seal fluid SF, and thus the seal fluid SF does not come into contact with the raw material L1 and the filtered liquid L2, and as the seal fluid SF, in addition to a gas such as nitrogen, compressed air, or an inert gas, a liquid such as pressurized oil can also be used.

[0154] The method of using the filter plate type filter X3 according to Embodiment 3 of the present application, the seal pressure P4 is applied to the filter material 1 by deforming the elastic body by supplying the seal fluid SF, and thus the seal fluid SF does not come into contact with the raw material L1 and the filtered liquid L2, and as the seal fluid SF, in addition to a gas such as nitrogen, compressed air, or an inert gas, a liquid such as pressurized oil can also be used.

[0155] The above describes Embodiments 1 to 4 of the present application, but the respective configurations and functions shown in the above-described embodiments are merely one example, and various changes can be made based on design requirements and the like.

[0156] Explanation of Reference Signs

[0157] 1, 1a, 1b, 1c, 1d: filter material;

[0158] 2a: upper filter plate;

[0159] 2b-1, 2b-2, 2b-3: intermediate filter plate;

[0160] 2b: lower filter plate;

[0161] 3: raw liquid introduction path;

[0162] 31a, 31b, 31c, 31d: branch introduction path;

[0163] 4: pressurizing and sealing unit;

[0164] 41: first pressure sensing unit;

[0165] 42: second pressure sensing unit;

[0166] 43: fluid supply path;

[0167] 431a, 431b, 431c, 431d: branch supply path;

[0168] 44: pressure regulating unit;

[0169] 5: control unit;

[0170] 9: horizontal filter plate type filter;

[0171] C, C1, C2, C3, C4: filter chamber.

Claims

1. A filter-plate type filter which is a filter-plate type filter that forms filter chambers by pressing and joining a plurality of filter plates provided to be openable and closable against each other with filter materials interposed, and performs filtration inside the filter chambers, wherein, The filter plate type filter is provided with: a plurality of filter plates arranged with the filter medium therebetween; a filter chamber formed between the filter plates; a raw liquid introduction path through which a raw liquid to be filtered is introduced into the filter chamber; a pressurized sealing unit that applies a sealing pressure to the filter medium by supplying a sealing fluid to the filter medium, thereby suppressing leakage of the raw liquid to be filtered and filtered liquid from the filter chamber to the outside of the filter chamber; and a control unit that automatically controls the sealing pressure in accordance with a change in the pressure in the filter chamber, the pressurized sealing unit has a fluid supply path that supplies the sealing fluid to the filter medium, the fluid supply path includes a sealing flow path that surrounds the periphery of the filter chamber, the sealing flow path being formed on a lower surface of an upper filter plate among the plurality of filter plates in a manner so as to be in contact with the filter medium when the plurality of filter plates sandwich the filter medium.

2. The filter plate type filter according to claim 1, wherein the pressurized sealing unit applies the sealing pressure to the filter medium by supplying the sealing fluid to the filter medium from a plurality of different directions.

3. The filter plate type filter according to claim 1 or 2, wherein the control unit automatically controls the sealing pressure to suppress leakage of the raw liquid to be filtered and filtered liquid to the outside of the filter chamber.

4. The filter plate type filter according to claim 1 or 2, wherein the control unit automatically controls the sealing pressure to suppress intrusion of the sealing fluid supplied to the filter medium into the filter chamber.

5. The filter plate type filter according to claim 1 or 2, wherein the control unit controls the sealing pressure in a manner that maintains a pressure difference between the pressure in the filter chamber and the sealing pressure at a prescribed pressure difference value.

6. The filter plate type filter according to claim 1, wherein the pressurized sealing unit has a first pressure sensing unit that senses a first pressure in the raw liquid introduction path, the control unit controls the sealing pressure based on the pressure in the filter chamber estimated from the first pressure in the raw liquid introduction path.

7. The filter plate type filter according to claim 6, wherein the pressurized sealing unit further has a second pressure sensing unit that senses a second pressure in the fluid supply path, the control unit controls the sealing pressure based on the pressure in the filter chamber estimated from the first pressure in the raw liquid introduction path sensed by the first pressure sensing unit and the second pressure in the fluid supply path sensed by the second pressure sensing unit.

8. The filter plate type filter according to claim 6, wherein the filter plate type filter is provided with a plurality of the filter chambers, the raw liquid introduction path has branched introduction paths that respectively introduce the raw liquid to be filtered to the plurality of filter chambers, the first pressure sensing unit senses a first pressure in the raw liquid introduction path on an upstream side from a branch point of the branched introduction paths, the control unit controls the sealing pressure based on the pressure in the filter chamber estimated from the first pressure in the raw liquid introduction path.

9. The filter plate type filter according to claim 8, wherein the pressurized sealing unit further has a second pressure sensing unit that senses a second pressure in the fluid supply path, the control unit controls the sealing pressure based on the pressure in the filter chamber estimated from the first pressure in the raw liquid introduction path and the second pressure in the fluid supply path. The fluid supply path includes a branch supply path that supplies sealing fluid to the filter elements of the plurality of filter chambers, The second pressure sensing unit senses a second pressure in the fluid supply path on an upstream side of a branch point of the branch supply path, The control unit controls the sealing pressure based on the first pressure in the stock solution introduction path and the second pressure in the fluid supply path.

10. The filter plate type filter according to claim 7 or 9, wherein The control unit controls the sealing pressure in a manner that maintains a pressure difference between the first pressure in the stock solution introduction path and the second pressure in the fluid supply path at a prescribed pressure difference value.

11. A filtration method, which is a filtration method using a filter-plate type filter machine that has a plurality of filter plates arranged with a filter medium therebetween and a filter chamber formed between the filter plates, wherein The filtration method includes: a pressurized sealing process of applying a sealing pressure to the filter element by supplying sealing fluid to the filter element via a fluid supply path, and a pressure control process of automatically controlling the sealing pressure to suppress leakage of a filtered stock solution and filtrate from inside the filter chamber to outside the filter chamber, The fluid supply path includes a sealing flow path that surrounds a periphery of the filter chamber, the sealing flow path being formed on a lower surface of an upper filter plate among the plurality of filter plates in a manner of being in contact with the filter element when the plurality of filter plates sandwich the filter element.

12. The filtration method according to claim 11, wherein In the pressurized sealing process, the sealing pressure is applied to the filter element by supplying the sealing fluid to the filter element from a plurality of different directions.

13. The filtration method according to claim 11 or 12, wherein In the pressure control process, the sealing pressure is automatically controlled to suppress leakage of the filtered stock solution and filtrate to outside the filter chamber.

14. The filtration method according to claim 11 or 12, wherein In the pressure control process, the sealing pressure is automatically controlled to suppress intrusion of the sealing fluid supplied to the filter element into the filter chamber.

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