AU4872097A

AU4872097A - Filter press

Info

Publication number: AU4872097A
Application number: AU48720/97A
Authority: AU
Inventors: Bernard Louis Felicien Hubert
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-18
Filing date: 1997-10-17
Publication date: 1998-05-15
Also published as: WO1998017367A1; FR2754758A1; HUP0000241A2; PL332829A1; JP2001502598A; EP0946244A1; TR199901481T2; BR9712335A; CN1237114A; CA2268798A1; FR2754758B1; CZ138199A3

Description

WO 98/17367 PCT/FR97/01865 Filter Press The present invention relates to an improvement to filter presses which are used especially to 5 concentrate sludges originating from various industries and requiring in particular the treatment of waste water or to recover juices contained in substrates, especially in the sugar industry. More specifically, the present invention 10 relates to a filter press capable of comprising a stack of several plates forming between them filtering spaces in which membranes extend, which divide these spaces into filtering chambers into which the material to be filtered is introduced and pressure chambers into which 15 a pressurized fluid is introduced, which brings about the displacement of the membranes to effect the pressing of the material introduced, so as to extract the juice therefrom. The object of the present invention is in 20 particular to improve the sealing conditions of such filter presses and to improve the conditions for mounting, maintenance and demounting of the membranes, for filtration and for compacting the cakes, and to increase the mechanical strength of the membranes. 25 The filter press according to the invention preferably comprises a stack of at least two plates which comprise adjacent peripheral parts defining a joint face and delimiting between them a filtering space, a membrane which extends in this space and the 30 peripheral part of which is retained between said peripheral parts of the plates over at least a part of its length so as to have a movable zone on either side of which a filtering chamber and a pressure chamber are delimited, means for supplying a product to be filtered 35 into said filtering chamber, means for supplying a fluid into said pressure chamber, and means for draining the filtrate from said filtering chamber. According to the invention, the aforementioned peripheral part of said membrane preferably comprises - 2 at least one branch strip which is retained between said peripheral parts of said plates. According to the invention, the peripheral part of at least one of the plates preferably comprises at 5 least one flow conduit which opens into said filtering chamber and is formed between the aforementioned branch strip and the aforementioned movable zone of the membrane. According to the invention, said flow conduit 10 may advantageously extend through the aforementioned peripheral parts of the plates, and at least one of the plates comprises a flow passage connecting, in the zone of the aforementioned joint face, said filtering chamber and said flow duct. 15 According to the invention, a plate element preferably holds the aforementioned peripheral part of the membrane in bearing contact against a plate in the zone of said flow passage. According to the invention, said flow conduit 20 may advantageously extend through the aforementioned peripheral part of the membrane and opens into filtrate flow ducts formed between the membrane and a filter cloth. According to the invention, the aforementioned 25 branch strip preferably consists of a part which is detached or separated, over a given length, from the aforementioned peripheral part of the membrane. According to the invention, the aforementioned peripheral part of the membrane preferably comprises a 30 peripheral rim, one part of which is detached or separated over a given length so as to constitute the aforementioned branch strip. According to the invention, at least one of the plates may advantageously comprise a main groove in 35 which a rim of the aforementioned peripheral part of the membrane is engaged and a secondary groove which opens at its ends into said main groove and in which the aforementioned branch strip is engaged.

- 3 According to an alternative embodiment of the invention, the aforementioned peripheral part of the membrane comprises a peripheral seal which is engaged in a main groove of one of said plates and comprises a 5 rim retained between said peripheral parts of the plates, a projecting peripheral part of the membrane being engaged in a peripheral slot of said seal, said seal comprising the aforementioned branch strip. According to the invention, said peripheral 10 seal preferably comprises an internal peripheral rim interposed between said membrane and the plate having said main groove. According to the invention, said peripheral seal preferably comprises a lip which is adjacent to 15 said internal peripheral rim and bears against the plate having said main groove. According to the invention, said seal preferably has a U-shaped section, the edges of the arms of which comprise said rims. 20 According to another alternative embodiment of the invention, the aforementioned peripheral part of the membrane comprises a projecting peripheral part or rib which is engaged in a main groove of one of said plates and comprises a peripheral rim retained between 25 said peripheral parts of the plates, this projecting part comprising the aforementioned branch strip. According to the invention, said projecting peripheral part of the membrane preferably comprises a peripheral slot at the bottom of which a wire for 30 retention in said main groove is engaged. According to the invention, the aforementioned peripheral rim of the membrane may advantageously comprise a part of enlarged section engaged in the bottom of enlarged section of said main groove. 35 According to the invention, the membrane may advantageously comprise, on the side of said filtering chamber, filtrate flow ducts and a filter cloth covering these ducts, the peripheral edge of this cloth -4 being retained with the peripheral edge of the membrane. According to a variant of the invention, at least the plate situated on the side of said pressure 5 chamber and said membrane have, in the aforementioned movable zone, coaxial through-passages, a retaining ring integral with said plate and coaxial with said passages comprising a projecting peripheral part, the edge of the membrane surrounding its aforementioned 10 passage being retained between the projecting peripheral part of said ring and the part of the plate surrounding its aforementioned passage, at least one communication opening connecting the interior of said retaining ring and said filtering chamber. 15 According to the invention, the projecting peripheral part of said ring and said plate preferably delimit between them an annular groove in which an annular rim of the aforementioned edge of the membrane is retained. 20 According to the invention, a linking ring connected to said retaining ring through the aforementioned passages preferably comprises a projecting peripheral part bearing on the other side of the plate, said rings constituting an annular core. 25 According to the invention, the aforementioned projecting parts of the retaining ring and of the linking ring of two adjacent plates preferably bear on one another and form said communication opening. According to the invention, the membrane 30 preferably has, in said filtering space, coaxial undulations surrounding its aforementioned edge. According to the invention, the membrane preferably comprises, on the side of said filtering chamber, filtrate flow ducts and a filter cloth 35 covering these ducts and comprising a through-passage coaxial with said passages, the edge of this passage of said cloth being retained with the aforementioned edge of the membrane.

-5 The present invention will be better understood by studying filter presses described by way of non limiting examples and illustrated by the drawing, in which: 5 Figure 1 shows, on reduced scale, a front view of a plate of a first filter press according to the invention, equipped with a membrane and with a cloth; Figure 2 shows a cross section of two plates of the filter press along II-II in Figure 1; 10 Figure 3 shows a front view of an exposed corner of said plate; Figure 4 shows this corner of said plate equipped with a membrane and with a cloth; Figure 5 shows, in this corner, a cross section 15 of two plates of said filter press along IV-IV in Figure 1; Figure 6 shows, in this corner, another cross section of two plates of said filter press along VI-VI in Figure 1; 20 Figure 7 shows a front view of another exposed corner of said plate; Figure 8 shows this other corner of said plate equipped with a membrane and with a cloth; Figure 9 shows, in this other corner, a cross 25 section of two plates of said filter press along IX-IX in Figure 1; Figure 10 shows a cross section of two plates of an alternative embodiment of the aforementioned filter press; 30 Figure 11 shows a cross section of the central part of an alternative embodiment of said filter press, and Figure 12 shows an enlarged partial section, corresponding to Figure 2, of an alternative embodiment 35 of said press. Referring to Figures 1 to 9, it can be seen that two adjacent square plates 1 and 2 of a filter press are shown, which press is designated generally by reference number 3 and comprises a plurality of - 6 corresponding plates stacked one on another and retained by lateral tie rods (not shown). The plates 1 and 2 have, facing one another, recessed areas 4 and 5 which define between them a 5 filtering space 6, the peripheral parts la and 2a of the plates 1 and 2 surrounding this space being in bearing contact over a joint face 7. The filter press 3 comprises a membrane 8 which extends in the filtering space 6 and the peripheral 10 part 9 of which is retained between the peripheral parts la and 2a of the plates 1 and 2 so as to divide the filtering space 6 into a filtering chamber 10 situated on the side of the plate 2 and a pressure chamber 11 situated on the side of the plate 1. 15 The peripheral part 9 of the membrane 8 comprises a peripheral part or rib 12 which is formed so as to project perpendicularly to the joint face 7 and is engaged in a main peripheral groove 13 of the plate 1. This peripheral part 8 also comprises a seal 20 14, made of rubber for example, which is interposed between this rib 12 and the wall of the groove 13, this seal 14 being of U-shaped section and comprising to that end a peripheral slot 15 formed perpendicularly to the joint face 7. 25 The bottom of the groove 13 of the plate 1 has an enlarged section and the end of the rib 12 of the membrane 8 has a lateral border 16, so that the peripheral part 9 of the membrane 8 is retained in the groove 13 of the plate 1 after having been introduced 30 into it by deformation or compression of the peripheral seal 14. The membrane 8 has, on its face situated on the side of the filtering chamber 10, a plurality of pips 17 which define between them flow interstices or ducts 35 18. This membrane also has, to facilitate the displacement of its movable zone situated inside the filtering space 6, coaxial undulations 19 in the periphery of this space 6.

- 7 The filter press 3 also comprises a filter cloth 20 which extends in the filtering chamber 10 and bears on the tops of the pips 17 and of the undulations 19 of the membrane 8. The peripheral part 20a of the 5 filter cloth 20 passes into the joint face 7 and is then engaged in the slot 15 of the peripheral seal 14 and passes round on the outside the peripheral rib 12 of the membrane 8. On assembly, the peripheral edge 20a of the 10 cloth 20 is introduced into the slot 15 of the peripheral seal at the same time as the rib 12 of the membrane 8. The seal 14 also has, on the edge of its external peripheral arm, a rim 21 which is arranged in 15 a widened part 22 of the external edge of the groove 13 of the plate 1. As is shown more clearly in Figure 2, the assembly constituted by the peripheral edge 9 of the membrane 8 and the peripheral edge of the filter cloth 20 20 is thus held captively in the groove 13 of the plate 1 by the peripheral surface of the plate 2 situated in the joint face 7, the rim 21 bearing against this surface. In a corner 3a, the filter press 3 has, through 25 the plates 1 and 2, a flow passage 23 which extends perpendicularly to the joint face 7 and is formed outside the peripheral part 9 of the membrane 8 and of the groove 13 of the plate 1. In this corner 3a, the plate 1 has, in its 30 surface situated in the joint face 7, a secondary, branch groove 24 which passes round on the outside and at a distance the duct 23 and the ends of which open into the widened edge 22 of its groove 13. In its peripheral zone corresponding to the 35 branch groove 24, the peripheral part 9 of the membrane 8 has a continuous branch strip 25 which extends in this branch groove 24. This branch strip 25 is constituted by the corresponding part of the rim 21 of the peripheral seal 14, which, between the ends of the - 8 branch groove 24, is detached, for example by cutting, and then pulled and stretched towards the outside to be arranged in the branch groove 24 during mounting of the membrane 8. 5 As is shown more clearly in Figures 4 and 5, the branch strip 25 is thus retained and compressed in the branch groove 24 of the plate 1 by that surface of the plate 2 which is situated in the joint face 7. This results in continuous sealing over the 10 periphery of the filter press 3, which is brought about by the rim 21 arranged in the groove 13 and the strip 25 arranged in the branch groove 24. To establish communication between the flow duct 23 and the filtering chamber 10, the plate 1 has a 15 recessed area 26 let in in relation to the joint face 7. The groove 13 has a part 13a which follows the hollow outline of the recessed area 26 and the peripheral part 9 of the membrane 8, from which the 20 branch strip 25 is separated and which is deformed so as to follow the outline of the part 13a. As is shown in greater detail in Figures 3 to 6, to apply and retain the zone of the peripheral part 9 of the membrane 8, a plate element 27 is provided, 25 which follows the outline of the recessed area and is fixed to the plate 1 by means of screws 28. The flow duct 23 and the recessed area 26 of the plate 1 thus constitute a flow conduit via which the material to be filtered can be introduced into the 30 filtering chamber 10. Furthermore, sealing of the pressure chamber 11 is effected over its entire circumference by the peripheral seal 14 introduced into the groove 13 of the plate 1. 35 In its corner 3b opposite the corner 3a, the filter press 3 has, as is shown in particular in Figures 7 to 9, another flow duct 29 which extends through the peripheral parts la and 2a of the plates 1 - 9 and 2, perpendicularly to the joint face 7 and outside and at a distance from the groove 13. In this corner 3b, the peripheral part 9 of the membrane 8 has a border 30 which extends outwards in 5 relation to its peripheral rib 12 and is engaged in a part 31 formed at the side of the groove 13 of the plate 1. Along this border 30, a part of the rim 21 of the peripheral seal 14 is detached, for example by 10 cutting, so as to constitute a branch strip 32 which extends in a lateral branch part 33 of the groove 13, extending its part 31. The strip 32 is thus pressed into this part 33 by that surface of the plate 2 which extends towards the joint face 7, passing round the 15 part 32 of the membrane 8. In the corner 3b of the filter press 3, the plate 1 also has a flow duct 34 which extends at 450 in relation to its adjacent edges and communicates laterally with the flow duct 29, the ends of this duct 20 34 being stopped up by plugs 35 and 36. Furthermore, the plate 1 has a plurality of ducts 37 which open on the one hand into the duct 34 and on the other hand into the groove 13. The peripheral part 9 of the membrane 8 has a plurality of 25 through-passages 38 situated facing the ducts 37 of the plate 1, these passages 38 opening below the cloth 20. The flow interstices 18 of the membrane 8 are thus connected to the flow duct 29 by the flow ducts 37 and 38 and by the flow duct 34, these ducts constituting a 30 flow or drain conduit for the liquid passing through the cloth 20 during displacement of the movable zone of the membrane 8 in the direction of the plate 2. Furthermore, as is shown in Figure 2, the plate 1 has a duct 39 for supplying a fluid into the pressure 35 chamber 11, the introduction of pressurized liquid into this chamber making it possible to displace the movable zone of the membrane 8 in the direction of the plate 2 so as to compress the material introduced into the filtering chamber 10.

- 10 Furthermore, the bottom of the recessed area 5 of the plate 2 has a plurality of pips 40 which define between them flow interstices or ducts 41, a filter cloth 42 being arranged in the filtering chamber 10, on 5 the top of the pips 40. The peripheral part 43 of this cloth 42 is anchored in a peripheral groove 44 formed at the bottom of the recessed area 5. During compression of the material contained in the chamber 10 as described above, the liquid can thus also be drained 10 towards the outside via the interstices 41 of the plate 2, through a duct 45 in the plate 2, which joins the duct 29. Referring now to Figure 10, it can be seen that a membrane 46 representing an alternative embodiment of 15 the membrane 8 in the preceding example is shown. In this example, this membrane 46 is made of an elastic material such as rubber. As in the preceding example, this membrane 46 has a peripheral rib 47 which is engaged in the peripheral groove 13 of the plate 1 20 and has a corresponding shape. This rib 47 has a peripheral slot 48 formed perpendicularly to the joint face 7 and open on the side of the plate 2a. At the bottom of this slot, a wire is introduced, which is arranged essentially in the centre of the enlarged part 25 of the groove 13. The peripheral edge 20a of the filter cloth 20 is introduced into the slot 48 and is wrapped around the wire 49. The peripheral part of the membrane 46 and the filter cloth 20 are thus suitably retained in the 30 groove 13 of the plate 1 and are pressed into this groove by the surface of the plate 2 situated in the joint face 7 as in the preceding example. Furthermore, the membrane 46 has an external peripheral border 50 which corresponds to the external 35 peripheral border 21 of the peripheral seal 14 in the preceding example. The separation over a given length of the peripheral border 50 makes it possible to form a branch strip equivalent to the branch strip 25 in the - 11 preceding example, or any other branch strip that might be desired to effect sealing in particular in the joint face 7 of the plates 1 and 2. Referring to Figure 11, it can be seen that an 5 alternative embodiment is shown of the means for supplying material to be filtered into two adjacent chambers 51 and 52, separated by a plate 53, of a filter press 54, the other parts of which correspond to the filter press previously described. 10 The plate 53 has, in its central part, a cylindrical through-passage 55. Extending end to end in this cylindrical passage 55 are the cylindrical parts 56 and 57 of two rings 58 and 59 which respectively have projecting peripheral parts or peripheral 15 shoulders 60 and 61, between which the edge of the passage 55 of the plate 53 extends. A cylindrical fixing ring 62 is engaged in the rings 58 and 59. It has a peripheral shoulder 63 bearing in an internal peripheral recess 64 of the ring 20 58 and is screwed in the cylindrical part 57 of the ring 59. The membrane 65, which is arranged in the filtering chamber 51 and the external peripheral part of which is supported by the plate 53, has a central 25 passage 66 and comprises, around this passage, an annular rim 67 which is retained in a groove 68 formed between the shoulder 60 of the ring 58 and the plate 53. Furthermore, an annular seal 69 is arranged in a space of the annular groove 68 so as to bear against 30 the annular rim 67 of the membrane 65, the plate 53 and the cylindrical part 56 of the ring 58, thus effecting sealing of the pressure chamber situated between the plate 53 and the membrane 65. Furthermore, the filter cloth 70 associated 35 with the membrane 65 has a central passage. The peripheral edge 71 of this filter cloth 70 is retained between the annular rim 67 of the membrane 65 and the shoulder 60 of the ring 58. Moreover, the other surface of the plate 53 supports a filter cloth 72, the central - 12 part of which has a through-passage, the edge 73 of which is engaged between the plate 53 and the shoulder 61 of the ring 59. The end surfaces 74 and 75 of the ring 58 and 5 of the ring 59 define perpendicular planes, on which the corresponding rings associated with an adjacent plate can bear, so that this stack constitutes a central flow duct 76 perpendicular to the plates of the filter press 54. 10 The ring 58 has a plurality of radial ducts 77 which make it possible to establish communication between the central duct 76 and the filtering chamber 52, the corresponding adjacent ring 59, bearing against the ring 58, having identical ducts making it possible 15 to establish communication between the central duct 76 and the filtering chamber 51. The central duct 76 and the radial ducts 77 of the rings 59 associated with the various plates 53 of the filter press 54 thus constitute supply ducts for 20 the adjacent chambers 51 and 52 of the filter press 54. Referring to Figure 12, it can be seen that a peripheral seal 78 is shown, which represents an alternative embodiment of the seal 14 described with reference to Figure 2. 25 This seal 78, of U-shaped section and in which the rib 12 of the membrane 8 is engaged, comprises, on the edge of its internal peripheral arm 79, a compressed peripheral rim 80 arranged between the internal corner of the rib 12 of the membrane 8 and the 30 internal flattened edge 81 of the main peripheral groove 13 of the plate 1. Furthermore, said seal 78 comprises a compressed sealing lip 82 adjacent to the rim 80 and bearing against the wall of the groove 13, this lip 35 being folded back in the opposite direction to the direction of introduction of the seal 78. The present invention is not limited to the examples described above. Many alternative embodiments - 13 are possible without leaving the scope defined by the appended claims.

Claims

1. Filter press comprising a stack of at least two plates (1, 2) which comprise adjacent peripheral parts 5 (la, 2a) defining a joint face (7) and delimiting between them a filtering space (6), a membrane (8) which extends in this space and the peripheral part (9) of which is retained between said peripheral parts of the plates over at least a part of its length so as to 10 have a movable zone on either side of which a filtering chamber (10) and a pressure chamber (11) are delimited, means (23, 26) for supplying a product to be filtered into said filtering chamber (10), means (39) for supplying a fluid into said pressure chamber (11), and 15 means (20, 29, 37) for draining the filtrate from said filtering chamber, characterized in that the aforementioned peripheral part (9) of said membrane (8) comprises at least one branch strip (25) which is retained between said peripheral parts (la, 2a) of said 20 plates.

2. Filter press according to Claim 1, characterized in that the peripheral part of at least one of the plates comprises at least one flow conduit (23, 26) which opens into said filtering chamber (10) 25 and is formed between the aforementioned branch strip (25) and the aforementioned movable zone of the membrane (8).

3. Filter press according to Claim 2, characterized in that said flow conduit (23) extends 30 through the aforementioned peripheral parts of the plates, and in that at least one of the plates comprises a flow passage (26) connecting, in the zone of the aforementioned joint face (7), said filtering chamber (10) and said flow duct (23). 35

4. Filter press according to Claim 3, characterized in that a plate element (27) holds the aforementioned peripheral part of the membrane in bearing contact against a plate in the zone of said flow passage (26) . - 15

5. Filter press according to Claim 2, characterized in that said flow conduit extends through the aforementioned peripheral part of the membrane and opens into filtrate flow ducts (37) formed between the 5 membrane (8) and a filter cloth (20).

6. Filter press according to any one of the preceding claims, characterized in that the aforementioned branch strip (25) consists of a part which is detached or separated, over a given length, 10 from the aforementioned peripheral part of the membrane.

7. Filter press according to any one of the preceding claims, characterized in that the aforementioned peripheral part of the membrane 15 comprises a peripheral rim (21), one part of which is detached or separated over a given length so as to constitute the aforementioned branch strip.

8. Filter press according to any one of the preceding claims, characterized in that at least one of 20 the plates comprises a main groove (13) in which a rim (21) of the aforementioned peripheral part (9) of the membrane is engaged and a secondary groove (24) which opens at its ends into said main groove and in which the aforementioned branch strip (25) is engaged. 25

9. Filter press according to any one of the preceding claims, characterized in that the aforementioned peripheral part of the membrane comprises a peripheral seal (14) which is engaged in a main groove (13) of one of said plates and comprises a 30 rim (21) retained between said peripheral parts of the plates, a projecting peripheral part (12) of the membrane being engaged in a peripheral slot of said seal (14), said seal (14) comprising the aforementioned branch strip (25). 35

10. Filter press according to Claim 9, characterized in that said peripheral seal comprises an internal peripheral rim (80) interposed between said membrane and the plate having said main groove (13). - 16

11. Filter press according to Claim 10, characterized in that said peripheral seal comprises a lip (82) which is adjacent to said internal peripheral rim and bears against the plate having said main 5 groove.

12. Filter press according to any one of Claims 9 to 11, characterized in that said seal has a U-shaped section, the edges of the arms of which comprise said rims (25, 80). 10

13. Filter press according to any one of Claims 1 to 8, characterized in that the aforementioned peripheral part of the membrane (46) comprises a projecting peripheral part or rib (47) which is engaged in a main groove (13) of one of said plates and 15 comprises a peripheral rim (50) retained between said peripheral parts of the plates, this projecting part comprising the aforementioned branch strip.

14. Filter press according to Claim 13, characterized in that said projecting peripheral part 20 (47) of the membrane (46) comprises a peripheral slot (48) at the bottom of which a wire (49) for retention in said main groove (13) is engaged.

15. Filter press according to any one of Claims 8 to 14, characterized in that the aforementioned 25 peripheral rim of the membrane comprises a part of enlarged section engaged in the bottom of enlarged section of said main groove (13).

16. Filter press according to any one of the preceding claims, characterized in that the membrane 30 comprises, on the side of said filtering chamber, filtrate flow ducts (18) and in that a filter cloth (20) covers these ducts, the peripheral edge (20a) of this cloth being retained with the peripheral edge (9) of the membrane. 35

17. Filter press comprising a stack of at least two plates (1, 2) which comprise adjacent peripheral parts (la, 2a) defining a joint face (7) and delimiting between them a filtering space (6), a membrane (8) which extends in this space and the peripheral part (9) - 17 of which is retained between said peripheral parts of the plates over at least a part of its length so as to have a movable zone on either side of which a filtering chamber (10) and a pressure chamber (11) are delimited, 5 means (23, 26) for supplying a product to be filtered into said filtering chamber (10), means (39) for supplying a fluid into said pressure chamber (11) , and means (20, 29, 37) for draining the filtrate from said filtering chamber, characterized in that at least the 10 plate (53) situated on the side of said pressure chamber and said membrane (65) have, in the aforementioned movable zone, coaxial through-passages (76), and in that a retaining ring (58) integral with said plate and coaxial with said passages comprises a 15 projecting peripheral part (60), the edge of the membrane surrounding its aforementioned passage being retained between the projecting peripheral part of said ring and the part of the plate surrounding its aforementioned passage, at least one communication 20 opening (77) connecting the interior of said retaining ring and said filtering chamber (51).

18. Filter press according to Claim 17, characterized in that the projecting peripheral part of said ring and said plate delimit between them an 25 annular groove (68) in which an annular rim (67) of the aforementioned edge of the membrane is retained.

19. Filter press according to one of Claims 17 and 18, characterized in that a linking ring (59) connected to said retaining ring (58) through the aforementioned 30 passages comprises a projecting peripheral part bearing on the other side of the plate, said rings constituting an annular core.

20. Filter press according to Claim 19, characterized in that the aforementioned projecting 35 parts of the retaining ring (58) and of the linking ring (59) of two adjacent plates bear on one another and form said communication opening.

21. Filter press according to any one of Claims 17 to 20, characterized in that the membrane has, in said - 18 filtering space, coaxial undulations (19) surrounding its aforementioned edge.

22. Filter press according to any one of Claims 17 to 21, characterized in that the membrane comprises, on 5 the side of said filtering chamber, filtrate flow ducts, and in that a filter cloth (70) covers these ducts and comprises a through-passage coaxial with said passages, the edge (73) of this passage of said cloth being retained with the aforementioned edge (67) of the 10 membrane (65).