Filter press compression membrane and operation method

Abstract

To provide a compression membrane for a filter press and an operation method where backwashing can be performed while compressing a dehydrated cake.SOLUTION: In a filter press where a stock solution is supplied to a filtration chamber 9 formed between a pair of filter plates 4A, 4B with a filter cloth 21 for filtration stretched thereon: a compressed fluid is supplied to a compression chamber 13 formed in the filtration chamber 9 and a dehydrated cake in the filtration chamber 9 is compressed and dehydrated by expanding a compression membrane 12; backwashing can be performed while compressing the dehydrated cake by providing the compression membrane 12 made of the filter cloth having lower permeability than the filter cloth for filtration on the surface of the filter plate 4A for compression forming the compression chamber 13; and the shortening of an operation time and the reduction of power consumption can be realized.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a squeezed membrane of a filter press that utilizes a filter cloth having a different air permeability from that of a filtration cloth as a squeezed membrane, and an operating method thereof. [Background technology]

[0002] Conventionally, in a filter press having a large number of filter plates, the raw liquid is pressurized into a filtration chamber to perform high-pressure squeezing and dehydration, and then a pressurized fluid is forced into a diaphragm filter plate to perform squeezing and dehydration. Diaphragm filter plates are generally made by stretching a resin diaphragm over a core plate, and are formed by fixing the diaphragm to the core plate using a pressure plate and bolts, or by fitting the engagement pieces of the diaphragm into engagement grooves in the core plate.

[0003] Patent Document 1 discloses a technology in which a compressed gas such as air is supplied from a compressed air supply section formed in a pair of treatment bodies (filter plates) housing a filter cloth inside to between the back side of the filtering surface of the filter cloth and the filtering bed of the treatment body (filter plate), thereby squeezing the layered double hydroxide (dehydrated cake) housed between the filter cloths.

[0004] Patent Document 2 discloses a filter press in which an intermediate plate having a sludge feed port is provided between a pair of filter plates, and a first filter cloth and a second filter cloth having finer mesh than the first filter cloth are disposed in each cake production chamber formed between the intermediate plate and each filter plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-28288 [Patent Document 2] Japanese Patent Application Publication No. 05-245309 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, when removing a diaphragm from a diaphragm filter plate, it was necessary to remove many parallel filter plates from the filter press body, which required a lot of work, time, and cost. Furthermore, when the removed diaphragm filter plate had the diaphragm fixed to the pressing plate with bolts, the number of parts was large, making it difficult to attach and remove the diaphragm. When the engagement piece of the diaphragm was fitted into the engagement groove of the core plate, it was difficult to fit the engagement piece of the diaphragm into the engagement groove of the core plate during manufacturing. Forcing the diaphragm into the engagement piece would deform the diaphragm and reduce the sealing performance, which caused a problem of not being able to squeeze at high pressure. In addition, since the diaphragm stretched on the diaphragm filter plate was made of resin, there was also the issue that it would plastically deform and break early when high pressure was applied during operation.

[0007] Patent Document 1 discloses a technique for squeezing and dehydrating a dehydrated cake using a pair of filter cloths, and since a diaphragm is not used, there are no problems such as the labor required for attaching and removing the diaphragm and deformation of the diaphragm. However, since the filtration cloth itself is used as the squeezing cloth, the compressed gas supplied leaks from the filtration cloth, causing unevenness in the squeezing surface and making it impossible to uniformly squeeze the dehydrated cake. If the air permeability of the filtration cloth is reduced to prevent leakage of the compressed gas, the filter cloth will clog early, causing problems such as reduced filtration efficiency.

[0008] Patent Document 2 discloses a technology in which filter cloths with different air permeabilities are stacked in a filtration chamber, but this technology performs precision filtration by passing the treatment liquid through a first filter cloth and then a second filter cloth with finer mesh than the first filter cloth, and does not use the filter cloth with the smaller air permeability as the filter cloth for squeezing. In other words, there has been no technology in which one of two types of filter cloths with different air permeabilities arranged in a filtration chamber is used for squeezing the dehydrated cake.

[0009] The present invention provides a filter press compression membrane and an operating method thereof, characterized in that a filtration cloth is provided in a filtration chamber formed between a number of parallel filter plates, and a compression membrane made of a cloth having a lower air permeability than the filtration cloth is stretched over a compression filter plate which forms a compression chamber located in the filtration chamber. [Means for solving the problem]

[0010] In the present invention, a raw liquid is supplied to a filtration chamber formed between a pair of filter plates on which a filtration cloth is stretched, and then the raw liquid is Between the compression membrane provided on the surface of the compression filter plate, which is at least one of the filter plates constituting the In a filter press, a compressed fluid is supplied to a compression chamber formed in the filter chamber to expand the compression membrane and compress and dehydrate the dehydrated cake in the filtration chamber. ,reactor Lower air permeability than conventional filter cloth It has many pores open all over. Filter cloth The filter cloth is expanded uniformly in the vertical direction to apply a squeezing pressure to the dehydrated cake, and the compressed fluid is gradually discharged from the numerous pores of the expanded filter cloth toward the dehydrated cake, thereby performing the backwashing process of the dehydrated cake simultaneously with the squeezing process. By providing the squeezing membrane, backwashing can be performed while squeezing the dehydrated cake produced between the filtration cloths.

[0011] The compression membrane is stretched so as to cover both filtration surfaces of the compression filter plates arranged alternately in parallel with the filtration filter plates, and a sealing treatment is applied to the position of the compression filter plate facing the filter frame, so that the compression membrane is tightly fixed to both filtration surfaces of the compression filter plate, preventing the compressed fluid in the compression chamber from leaking out from the circumferential surface of the filter frame.

[0012] The compression membrane is stretched so as to cover one side of the filtration surface of the continuously arranged compression filter plates, and a sealing treatment is applied to the position of the compression filter plate facing the filter frame, so that the compression membrane is tightly fixed to one side of the filtration surface of the compression filter plate, thereby preventing the compressed fluid in the compression chamber from leaking out from the circumferential surface of the filter frame.

[0013] The compression membrane is suspended from above the compression filter plate so as to cover the filtration surface, so that the compression membrane can be easily attached and detached.

[0014] After supplying the raw liquid to a filtration chamber formed between a pair of filter plates on which a filtration cloth is stretched, a compressed fluid is supplied to a compression chamber formed in the filtration chamber, and a compressed fluid having a lower air permeability than the filtration cloth is supplied to the compression chamber. It has many pores open all over. A compressed membrane made of filter cloth Uniform verticallyThe dehydrated cake formed in the filtration chamber is expanded and squeezed. The compressed fluid is gradually discharged from the numerous pores of the expanding compression membrane toward the dehydrated cake, and the dehydrated cake is back-washed simultaneously with the squeezing process. This allows backwashing to be performed simultaneously during the squeezing process of the dehydrated cake, thereby shortening the operation time and reducing power consumption. Effect of the Invention

[0015] The filter press compression membrane and operation method of the present invention compress the dehydrated cake using a compression membrane made of a filter cloth with lower air permeability than the filter cloth for filtration. Since the compression membrane has a simple configuration in which the compression membrane is suspended from above the compression filter plate, the number of parts is small and the compression membrane can be easily replaced. In addition, since the compression membrane is made of a filter cloth with high weather resistance, it does not break early even when high-pressure squeezing is performed. Furthermore, when compressed fluid is supplied into the squeezing chamber, the compressed fluid cannot immediately pass through the squeezing membrane due to the resistance of the squeezing membrane with low air permeability, and the pressure in the squeezing chamber gradually increases, and the squeezing membrane is in a state in which it is uniformly expanded in the vertical direction, so that the squeezing action can be applied to the entire dehydrated cake. Then, the compressed fluid in the squeezing membrane gradually flows from the squeezing membrane toward the dehydrated cake while performing backwashing, so that the dehydrated cake can be uniformly washed in the vertical direction without unevenness. In this way, squeezing and backwashing are performed while continuing to supply a constant amount of compressed fluid to the expanded squeezing membrane, so there is no need to supply an excessive amount of compressed fluid, and it is also possible to reduce the amount of compressed fluid used. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a side view of a filter press according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the essential parts of the pressing filter plate and the filtration filter plate. [Diagram 3] FIG. 3 is a front view of the pressing filter plate in FIG. 2. [Figure 4] FIG. 2 is a schematic diagram showing a state in which filtration cloths are attached to the filter plates. [Diagram 5] FIG. 11 is a cross-sectional view showing another embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional view of the filtration chamber during the pressing step. [Figure 7] FIG. 11 is a cross-sectional view of the filtration chamber during the squeezing step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 is a side view of a filter press according to the present invention. The filter press according to the present invention has a pair of guide rails 3 spanning a front frame 1 and a rear frame 2, and a number of filter plates 4 are supported on the guide rails 3. A clamping cylinder 5 disposed on the rear frame 2 is connected to a movable head 6, and the clamping cylinder 5 opens and closes the parallel filter plates 4.

[0018] By moving the movable head 6 towards the front frame 1 to close the filter plates 4, a raw liquid supply passage 7 is formed above the parallel filter plates 4. A raw liquid supply pipe 8 that communicates with the front end of the filter plate row is connected to the front frame 1 so that the raw liquid can be supplied to the raw liquid supply passage 7. A filtration chamber 9 that communicates with the raw liquid supply passage 7 is formed between adjacent filter plates 4, and the raw liquid supplied from the raw liquid supply passage 7 is separated into solid and liquid.

[0019] A filtrate discharge passage 10 communicating with each filtration chamber 9 is formed below the parallel filter plates 4, and the separated filtrate is discharged through the passage 10. The passage 10 communicates with a filtrate discharge pipe 11 connected to the front frame 1, and the filtrate discharged into the passage 10 is discharged to the outside through the pipe 11.

[0020] FIG. 2 is a cross-sectional view of the main parts of a pressing filter plate and a filtration filter plate, and FIG. 3 is a front view of the pressing filter plate in FIG. A pair of filtration cloths 21, 21 is suspended between the pressing filter plate 4A and the filtration filter plate 4B, and the filtration chambers 9 between the adjacent filter plates 4, 4 are covered by the filtration cloths 21, 21. When the filter plates are closed, the raw liquid supply holes 19A and 19B opening at the top of the pressing filter plate 4A and the filtration filter plate 4B, respectively, communicate with the raw liquid supply port 20 of the liquid supply plate 22 sandwiched and joined to the top of the filtration cloths 21, 21, thereby forming the raw liquid supply path 7. The raw liquid supplied through the raw liquid supply path 7 flows into each filtration chamber 9 through the liquid supply path 33 communicating with the raw liquid supply port 20. In this embodiment, the numerous filter plates 4 are constituted by alternately arranging the pressing filter plates 4A and the filtration filter plates 4B in parallel, but if necessary, only the pressing filter plates 4A may be arranged in parallel.

[0021] The squeezing filter plate 4A has a squeezing membrane 12 stretched over the entire filtration surface. In this embodiment, the squeezing membranes 12 are stretched over both sides of the filtration surface of the squeezing filter plate 4A, and squeezing chambers 13, 13 are formed between the squeezing filter plate 4A and the squeezing membranes 12, 12. The squeezing membrane 12 is made of an expandable and contractible filter cloth, and expands when a compressed fluid such as air or liquid is supplied into the squeezing chamber 13.

[0022] The squeezed membrane 12 hangs down from above the squeezing filter plate 4A so as to cover the filtration surface of the squeezing filter plate 4A, and both hanging parts 35, 35 are connected at one or more points by a connecting member 23 such as a screw or a cable tie. At this time, both hanging parts 35, 35 are located below the squeezing filter plate 4A. After the opposing surfaces of both hanging parts 35, 35 are overlapped, the overlapped parts are connected and fixed by the connecting member 23, but it is preferable to connect them at multiple points to improve connectivity. Note that the squeezed membrane 12 may be connected not only to both hanging parts 35, 35 but also to both side parts.

[0023] In this embodiment, since the compressed membrane 12 plays the role of a conventional diaphragm, it is necessary to improve the sealing property of the filter frame 30 so that the compressed fluid in the compression chamber 13 does not leak from the filter frame 30. Therefore, when the compressed membrane 12 is stretched on the compression filter plate 4A, as shown in FIG. 3, the peripheral portion of the compressed membrane 12 that faces the filter frame 30 of the compression filter plate 4A is sealed. The sealing is performed by a known sealing method such as applying a resin. By performing the sealing, the peripheral portion of the compressed membrane 12 and the filter frame 30 are in close contact when the filter plate is closed, and the sealing property of the compression chamber 13 can be improved, so that the compressed fluid is prevented from leaking from the filter frame 30. At this time, the entire surface of the filter bed 14A is covered.

[0024] In addition, since the compression membrane 12 can be in close contact with the compression filter plate 4A by closing the filter plate 4, the filter plate 4 may be closed in a state where both the hanging parts 35, 35 are hanging down without being connected by the connecting member 23. 4 Since the squeezing membrane 12 is tightly attached to the squeezing filter plate 4A by closing the plate, it is desirable to position the lower ends of both hanging parts 35, 35 below the bottom side of the filter frame 30.

[0025] The squeezing membrane 12 has a pair of openings 34 at positions facing the raw liquid supply holes 19A of the squeezing filter plate 4A. The openings 34 are formed to have the same diameter as the raw liquid supply holes 19A, 19B, so that the raw liquid and compressed fluid can flow in when the filter plate is closed. Therefore, when the squeezing membrane 12 is suspended from above each squeezing filter plate 4A, the openings 34 are aligned so that they can communicate with the raw liquid supply holes 19A, 19B.

[0026] As shown in FIG. 2, the pressing filter plate 4A and the filtering filter plate 4B form filtrate discharge holes 32A and 32B at the bottom of the filter beds 14A and 14B of each filter plate 4, respectively, and form filtrate discharge paths 10A and 10B that communicate with the discharge holes 32A and 32B, respectively. The filtrate discharged from the filtrate discharge hole 32A is discharged to the outside through the filtrate discharge path 10A, and the filtrate discharged from the filtrate discharge hole 32B is discharged to the outside through the filtrate discharge path 10B. The filtrate discharge hole 32A and the filtrate discharge path 10A communicate with the compression chamber 13 and also communicate with the filtration chamber 9 through the compression membrane 12. They serve as a discharge path for the filtrate during the dehydration process and as a supply path for the compressed fluid during the compression process. On the other hand, the filtrate discharge hole 32B and the filtrate discharge path 10B communicate with the filtration chamber 9 and serve as a discharge path for the separated filtrate. As shown in FIG. 3, each of the filtrate discharge passages 10A, 10B is an opening formed on a side of the filter plate, and when the filter plates are closed, the openings communicate with each other to form an extension below the row of filter plates.

[0027] 2, the filtrate discharge hole 32B provided in the conventionally used filtration plate 4B communicates with the filtration chamber 9, and the filtrate separated from the filtration chamber 9 passes through the filtration cloth 21 and is discharged from the filtrate discharge hole 32B. On the other hand, the filtrate discharge hole 32A provided in the squeezing filter plate 4A is configured to communicate with the squeezing chamber 13 and the filtration chamber 9, and is covered by the squeezing membrane 12 and the filtration cloth 21. Therefore, the filtrate discharged from the dehydrated cake produced in the filtration chamber 9 passes through the filtration cloth 21, and then is discharged from the squeezing membrane 12 and the filtration cloth 21. film The filtrate permeates through 12 and is discharged from filtrate discharge hole 32A.

[0028] FIG. 4 is a schematic diagram showing a state in which filtration cloths are attached to each filter plate. A pair of filtration cloths 21 for separating the raw liquid into solid and liquid are provided between the alternatingly arranged pressing filter plates 4A and filtration filter plates 4B. The filtration cloth 21 is configured to be interlocked with a drive machine (not shown) and a sprocket 24, and a chain 25 is wound around the sprocket 24. One end of the chain 25 is connected to an upper cloth core metal 26, and the other end is connected to a lower cloth core metal 27. The upper cloth core metal 26 and the lower cloth core metal 27 are inserted into the bag-shaped portion of the cloth, and therefore the chain 25 and the filtration cloth 21 are formed in an endless shape.

[0029] When the sprocket 24 is rotated clockwise, the filtration cloth 21 starts to descend, and the dehydrated cake adhering to the filtration cloth 21 is forcibly peeled off from the cloth by the reversal of the filtration cloth 21 along the return roll 28. When the filtration cloth 21 descends to a predetermined position, the driving machine is reversed to raise the filtration cloth 21.

[0030] In this embodiment, a traveling filtration cloth 21 is used, but in another embodiment, a filter press may be constructed using a fixed filtration cloth 21. The method of attaching the fixed filtration cloth 21 to the squeezing filter plate 4A is the same as the method of attaching the squeezing membrane 12 to the squeezing filter plate 4A in this embodiment, and the filtration cloth 21 is hung down from above the squeezing filter plate 4A on which the squeezing membrane 12 is stretched, and both hanging parts 35, 35 are connected to the bottom of the filter plate by a connecting member as necessary. 23 In other words, the pressing filter plate 4A is covered with two types of filter cloth.

[0031] In this embodiment, two types of filter cloths are used: a filtration cloth 21 and a squeezing membrane 12. The filtration cloth 21 is a known pair of filter cloths, and performs solid-liquid separation of the raw liquid supplied between the filter cloths 21, 21. The squeezing membrane 12 is used to squeeze the dehydrated cake generated between the filtration cloths 21, 21, and is configured to be expandable by the compressed fluid supplied to the squeezing chamber 13. The squeezing membrane 12 uses a filter cloth with lower air permeability than the filtration cloth 21.

[0032] The squeezed membrane 12 is not particularly limited as long as it is a filter cloth with lower air permeability than the filtration filter cloth 21, but it is preferable to use a filter cloth with air permeability of 1 / 100 to 1 / 1000 of the filtration filter cloth 21. The use of a filter cloth with low air permeability creates a passage resistance for the compressed fluid, reducing the amount of compressed fluid that can pass through the squeezed membrane 12 and slowing down the passage speed. As a result, the pressure in the compression chamber 13 gradually increases, and the compressed fluid supplied into the compression chamber 13 can expand the squeezed membrane 12.

[0033] FIG. 5 is a cross-sectional view showing another embodiment. A compression membrane 12 is stretched on one side of the filtration surface of the compression filter plate 4A, and a compression chamber 13 is formed on one side of the filtration surface. A filter press may be constructed by continuously arranging a number of compression filter plates 4A thus formed. In this case, as in the present embodiment, the compression membrane 12 is stretched hanging down from above, but a lifting mechanism such as a sprocket may be provided above the compression filter plate 4A to enable the compression membrane 12 to be lifted and lowered. In this embodiment, the compression membrane 12 is also subjected to a sealing treatment at the position where it contacts the filter frame 30. As a result, when the filter plate is closed, the compression membrane 12 is tightly fixed to the filter frame 30, so that leakage of compressed fluid from the peripheral surface of the filter frame 30 can be prevented. An embodiment of the present invention will now be described with reference to FIGS. EXAMPLES

[0034] <Closing process> A cylinder that clamps multiple filter plates 4 5 The rows of filter plates are closed with a pressing plate 4A and a filtration chamber 9 is formed between the adjacent pressing filter plate 4A and filtration filter plate 4B. A pair of filtration cloths 21 is stretched in each filtration chamber 9 to cover the inside of the filtration chamber 9. At this time, the raw liquid supply passage 7 is formed above the closed row of filter plates, and filtrate discharge passages 10A, 10B are formed below the row of filter plates.

[0035] <Press-fitting process> The raw liquid supplied at a constant pressure from the raw liquid supply pipe 8 flows into each filtration chamber 9 via the raw liquid supply passage 7, and then undergoes solid-liquid separation between the filtration cloths 21, 21 in the filtration chamber 9. As filtration progresses due to the pressure of the raw liquid continuously supplied, the raw liquid in the filtration chamber 9 discharges filtrate. The discharged filtrate is discharged from the filtrate discharge holes 32A, 32B of the pressing filter plate 4A and the filtration filter plate 4B.

[0036] Specifically, the filtrate discharged from the squeezing filter plate 4A passes through the filtration cloth 21 from within the filtration chamber 9, then passes through the squeezing membrane 12, and is then discharged from the filtrate discharge hole 32A. On the other hand, the filtrate discharged from the filtration filter plate 4B passes through the filtration cloth 21 from within the filtration chamber 9, and is then discharged from the filtrate discharge hole 32B. The filtrate discharged from the filtrate discharge holes 32A and 32B is discharged to the outside through the filtrate discharge paths 10A and 10B that communicate with the respective discharge holes.

[0037] The filter cloth 21 is a filter cloth when the raw liquid is injected. 21 , 21 The raw liquid supplied between the pressing filter plate 4A and the filtration filter plate 4B swells toward the filtration beds 14A and 14B. Accordingly, the pressing membrane 12 adjacent to the filtration cloth 21 located on the filtration bed 14A side swells toward the pressing chamber 13 side. The injection of the stock solution is carried out for a predetermined period of time.

[0038] <Compression process (backwashing process)> After the pressing step is completed, the squeezing step is started. As shown in Fig. 7, compressed fluid is supplied from a filtrate discharge passage 10A communicating with a filtrate discharge hole 32A formed in the squeezing filter plate 4A. The supplied compressed fluid flows into a squeezing chamber 13 formed between the squeezing filter plate 4A and the squeezing membrane 12 through the filtrate discharge hole 32A.

[0039] After the compressed fluid flows into the compression chamber 13, it gradually expands the compression membrane 12 toward the dehydrated cake. At this time, since the surface of the compression chamber 13 is covered with the compression membrane 12 made of a filter cloth with low air permeability, the supplied compressed fluid cannot immediately pass through the compression membrane 12, and the pressure in the compression chamber 13 gradually increases. As a result, the compression membrane 12 expands, and the expanded compression membrane 12 applies a uniform compression pressure to the dehydrated cake formed between the filtration filter cloths 21, 21, so that water is efficiently discharged from the dehydrated cake. In other words, by forming the compression membrane 12 using a filter cloth with low air permeability and reducing the passage efficiency of the compressed fluid flowing into the compression chamber 13, it becomes possible to expand the compression membrane 12, and compression pressure can be applied to the dehydrated cake.

[0040] Thereafter, the compressed fluid in the compression chamber 13 permeates the compression membrane 12 and the filtration cloth 21, and flows into the dehydrated cake. Specifically, the compressed fluid flows from the compression filter plate 4A side to the filtration filter plate 4B side, penetrating the dehydrated cake. At this time, the mother liquor in the dehydrated cake is replaced with the compressed fluid that has flowed in, and impurities such as soluble compounds in the dehydrated cake are removed.

[0041] In the conventional backwashing process, there was a problem that the compressed fluid supplied from the filtrate discharge hole 32A below the filter plate 4 did not reach the upper part of the dehydrated cake, resulting in uneven cleaning of the cake. In the present embodiment, however, the backwashing process is started with the compression membrane 12 in an expanded state, so that the compressed fluid can be made to flow uniformly toward the dehydrated cake from the numerous pores opened over the entire compression membrane 12, and the dehydrated cake can be uniformly cleaned in the vertical direction.

[0042] The compressed fluid that has passed through the dehydrated cake is discharged from the filtrate discharge hole 32B and then passed through the filtrate discharge passage 10B to the outside.

[0043] In this embodiment, the squeezing chamber 13 communicating with the filtrate discharge hole 32A is covered with the squeezing membrane 12 having low air permeability to provide resistance to the passage of the compressed fluid, so that the compressed fluid cannot immediately pass through the squeezing membrane 12, and the pressure in the squeezing chamber 13 gradually increases and the squeezing membrane 12 expands, thereby squeezing the dehydrated cake. Then, the compressed fluid gradually flows from the expanded squeezing membrane 12 toward the dehydrated cake, so that backwashing can be performed while squeezing the dehydrated cake at the same time. In other words, unlike the conventional squeezing process and backwashing process, squeezing and washing of the dehydrated cake can be performed in one process.

[0044] The squeezing process is carried out using the same operating method as the conventional backwashing process, so it is possible to omit the equipment required for the conventional squeezing process, such as squeezing tanks, squeezing pumps, and piping. It is also possible to shorten the squeezing time, which in turn makes it possible to shorten operation time and reduce power consumption.

[0045] The compressed fluid may be air or liquid, either alone or in combination, and is selected appropriately according to the design requirements. In addition, forward washing may be performed prior to the squeezing process (backwashing process).

[0046] <Opening process> After the squeezing process is completed, the clamping cylinder 5 is driven to release the clamping of the movable head 6, and the parallel filter plates 4 are moved toward the rear frame 2 and opened, discharging the dehydrated cake from the filtration chamber 9. The dehydrated cake falls outside the machine due to its own weight and the movement of the filtration cloth 21.

[0047] When the filtration cloth 21 is washed, it is washed using a known washing mechanism 31. Since the SS component in the raw liquid adheres to the filtration cloth 21 during solid-liquid separation, the squeezed membrane 12 does not basically need to be washed, but if washing becomes necessary, it is washed using a known washing mechanism 31. 31 Wash with.

[0048] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. [Industrial Applicability]

[0049] The filter press compression membrane and operation method according to the present invention can compress the dehydrated cake while backwashing it in a state where the compression membrane stretched on the filtration surface of the compression filter plate arranged in parallel with the filtration filter plate is expanded, and backwashing can be performed during the squeezing process, which can reduce the operating time and power consumption, making it an environmentally friendly filter press. In addition, the compression of the dehydrated cake can be performed using a filter cloth with higher air permeability than the filtration filter cloth. low Since this process is carried out using a squeeze membrane made of filter cloth, it is possible to deal with sludge of any type by using a filter cloth with an appropriate air permeability as the squeeze membrane depending on the properties of the inflow sludge. [Explanation of symbols]

[0050] 4A Compression filter plate 4B Filtration plate 9 Filtration Room 12 Squeezed membrane 13 Pressing Room 21 Filtration cloth 30 frames

Claims

1. In a filter press, a raw liquid is supplied to a filtration chamber (9) formed between a pair of filter plates having a filtration cloth (21) stretched therebetween, and then a compressed fluid is supplied to a compression chamber (13) formed between a compression filter plate (4A), which is at least one of the filter plates constituting the filtration chamber (9), and the compression filter plate (4A), to expand the compression membrane (12) and thereby compress and dehydrate a dehydrated cake in the filtration chamber (9), The filter cloth (21) has a lower air permeability than the filter cloth for filtration and is composed of a filter cloth having a large number of pores open all over the filter cloth. A squeezing membrane (12) that uniformly expands in the vertical direction to apply a squeezing pressure to the dehydrated cake and gradually flows a compressed fluid toward the dehydrated cake from the numerous pores of the expanded filter cloth, thereby performing a backwashing process of the dehydrated cake simultaneously with the squeezing process. Equipped with The squeezed membrane of a filter press.

2. The compression membrane (12) is stretched so as to cover both filtration surfaces of the compression filter plates (4A) arranged alternately in parallel with the filtration filter plates (4B), The pressing filter plate (4A) was subjected to a sealing treatment at the position where it contacts the filter frame (30).

2. The squeezed membrane of a filter press according to claim 1 .

3. The compression membrane (12) is stretched so as to cover one side of the filtration surface of the compression filter plates (4A) arranged in series, The pressing filter plate (4A) was subjected to a sealing treatment at the position where it contacts the filter frame (30).

2. The squeezed membrane of a filter press according to claim 1 .

4. The compression membrane (12) hangs down from above the compression filter plate (4A) so as to cover the filtration surface. A squeezed membrane of a filter press according to any one of claims 1 to 3.

5. After supplying the raw liquid to a filtration chamber (9) formed between a pair of filter plates on which a filtration cloth (21) is stretched, A compressed fluid is supplied into a compression chamber (13) formed in the filtering chamber (9); A squeezed membrane (12) made of a filter cloth having a lower air permeability than the filtration cloth (21) and having many pores open all over is expanded uniformly in the vertical direction to squeeze the dehydrated cake produced in the filtration chamber (9), and a compressed fluid is gradually discharged from the many pores of the expanded squeezed membrane (12) toward the dehydrated cake, thereby back-washing the dehydrated cake simultaneously with the squeezing process. A method for operating a filter press.

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