DK142446B - Filter plate. - Google Patents

Description

(11) PROMOTIONAL CERTIFICATE 1 DENMARK (»DlntCI.3 B 01 D § 25/12 (21) Application No 2774/75 (22) Filed in 19 * JUTl 1975 (24) Run date 19 · JUH 1975 (44) The application presented and

the petition published on 5 · HOV · 1 9oQ

DIRECTORATE OF

PATENT AND TRADEMARK (3 °) Priority requested from it

2 ?. December 1974, 1505/75 Uj JP

(71) ISHIGAKI KIKO CO. LTD., 5-4-15, Nihoribaehi, Chuo-ku, Tokyo, JP.

(72) Inventor: Akltoshi Iwatani, 5665-10 Doki-cho, Marugame, JP.

74) Plenipotentiary in the proceedings:

Th. Ostenfeld Patentbureau A / s.

(64) Filter plate.

The present invention relates to a filter plate of the kind set forth in the preamble of claim. More particularly, the invention relates to a filter plate for a filter press in which two plate-like membranes of a resilient material, each having a centrally recessed filter cloth-supporting bearing on the outside and a circumferential edge or collar along the periphery, are fixedly fixed to the back of a core plate, respectively. in such a way that the collar of each of the membranes is disposed on the periphery of the core plate and wherein at least one passageway for a compressed fluid is introduced into the membranes.

Various types of filter plates have already been proposed for a filter press and with membranes for pressing filter cakes after a filtration operation. Following a filtration operation, the membranes are expanded by introducing compressed fluid behind the membranes so that filter cakes on a filter cloth placed on the membranes are pressed and thereby dewatered for easy removal and treatment. Such filter plates with membranes can be divided into two main types. Filter plates of a first main type have at least one plate-like membrane arranged on the surface of a core or filter plate. Examples of this filter plate type are known from the descriptions of U.S.A. U.S. Patent Nos. 3,098,429 and 3,807,567. The second main type of membrane filter plate has a bag-like membrane arranged around a core frame or core plate. An example of this filter plate type is known from the description of U.S.A. Patent No. 3,270,887.

A filter device using filter plates with membranes has two types of sealing problem.

During a filtration operation, slurry or liquid to be filtered is pressurized on the filter cloth between the filter plates and thus the slurry or liquid must be sealed tightly between the filter plates. During a filter cake press operation, the compressed fluid introduced behind the membranes to expand these to compress the cakes must also be tightly sealed so that the fluid does not leak out of the membranes. Filter plates with bag-like membranes outperform filter plates with plate-like membranes, the former having a better seal during a cake press operation than the latter type, since the bag-like membranes very well prevent leakage of compressed fluid introduced into the membranes.

However, filter plates with bag-like membranes have certain disadvantages. Especially when the filter plates are increased in size in order to increase the filter area, for example from one square meter to two or three square meters per meter. plate to meet the present requirement that the filtration capacity of a filter press be increased, the casting of such bag-like membranes becomes difficult due to their considerably increased weight. Furthermore, insertion of a core frame or core plate into such bag-like membranes is difficult due to the increased size of the membranes, and finally, the handling and maintenance of such large bag-like membranes is difficult. In these respects, filter plates with plate-like membranes are more convenient than filter plates with bag-like membranes.

U.S. Patent No. 3,807,567 discloses filter plates with plate-like membranes which are more convenient than filter plates with bag-like membranes for molding the membranes, arrangement of core plates in the membranes, and handling and maintenance as just stated.

For example, from German publication specification No. 2,322,044, filter plates of the current type are also known, in which each of the core plate surfaces in the peripheral region is provided with at least one endless groove, in which a corresponding endless sealing rib arranged on the inside of each of the membranes along their peripheral area.

However, the sealing thus obtained is not sufficiently effective, since the sealing rib can be relatively easily squeezed in whole or in part out of the associated trace of the pressure fluid during a cake pressing operation, thereby creating a leak.

The filter plate according to the invention is characterized by the characterizing part of the claim, thereby obtaining an effective solution of the sealing problem in connection with filter plates with plate-shaped membranes. Thus, the endless sealing ribs on the inside of the membranes, together with the groove or groove on the surface of the core plate and with the assistance of the peripheral surface parts of the membrane, whose outer surface protrudes slightly in front of the outer surface of the invention, pressurizes the fluid from the diaphragm during the cake press operation. it will become clearer from the following. The outer edge of the diaphragm, whose outer surface, as just mentioned, protrudes slightly in front of the outer surface of the outer frame, prevents slurry leakage which is introduced under pressure between two adjacent filter plates, as will also be explained in more detail below.

In addition, the elongated edge or collar of each membrane is provided with a circumferential and protruding portion such that the collar has a hail-like shape and this protruding portion is arranged for insertion into a corresponding groove formed at the periphery of the core plate. Thus, the membrane is firmly anchored along the periphery of the core plate by means of the outer frame, so that the periphery of the membrane, even if the weight of the membrane is very large, cannot be displaced in the direction away from the periphery of the core plate. which would cause a reduction of the seal during the cake press operations.

In addition, the filter plate according to the invention gives rise to manufacturing advantages, since the outer frame of the invention specially requires only precise machining of two surfaces, namely the side surfaces, whereas certain known constructions, for example the known from US patent 3,807,567, with more complicated frames, require accurate machining of multiple surfaces on multiple components.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be explained in greater detail with reference to the accompanying drawings, in which 1 is a frontal view with certain parts omitted from an embodiment of the filter plate according to the invention; FIG. 2 is a larger scale vertical section with some parts omitted and taken along line II-II of FIG. 1, FIG. 3 shows a vertical section with certain parts omitted through a part of the embodiment of FIG. 1; FIG. 4 is a side view with certain parts cut away from the one shown in FIG. 1, FIGS. 5a and 5b are schematic vertical sectional views with certain parts cut away showing the use of the device shown in FIG. 1, and FIG. 6 is a vertical sectional view with some parts cut away similar to FIG. 2 but showing another embodiment of the filter plate according to the invention.

In the drawing FIG. 1-5, a preferred embodiment of the filter plate according to the invention is shown. The filter plate 10 shown comprises a core plate 11, two membranes 12 of an elastic material such as rubber or synthetic resin, which are arranged at the front and back of the core plate 11, and an outer frame 13 arranged at the outer periphery of the filter plate. Filter plate 10 has a top projection 14 through which a slurry 15 for slurry to be filtered is provided.

As can be seen clearly in FIG. 2, the core plate 11 consists of an inner plate 17 of stainless steel or the like, two hard rubber outer plates 18 of synthetic resin or the like, and a ring device 19 of stainless steel or the like. The outer plates 18 are fixed to the surfaces of the lower plate 17 by means of adhesives, so that on each surface of the core plate 11 a central recess 20 is not covered by the plate 18. Each of the inner and outer plates 17 and 18 has a top projection having a breakthrough corresponding to the top projection 14 of the filter plate 10, and the ring device 19 is inserted tightly into the breakthroughs in the outer plates 18, as shown in figures 2 and 3. The outer plate 18 has planar outward faces at the peripheral region and around the breakthrough in the top projection. and these faces are followed by obliquely extending outward faces, as shown in FIG. 2nd

According to the invention, each of the outer surfaces of the core plate 11 is provided with an endless groove 21 at the peripheral region, namely at the plane outwardly facing surface portion of the outer plate 18. A similar endless or annular groove 22 is also formed in each of the outer surfaces of the core plate 11 around the breakthrough of the core plate 11. the top, namely on each of the outer surfaces of the ring device 19. In addition, in the outer surfaces of the outer plates 18 an elongate groove 23 is formed extending over the lower part of the top protrusion on the core plate 11. This is provided at the periphery of the core plate 11. with an endless and elongate groove 24, the periphery of the outer plate 18 being formed accordingly.

Each of the membranes 12 has a shape similar to the core plate 11. According to the invention, the inner surface of each membrane 12 at the rim region is provided with an endless and elongated sealing rib 25 which is inserted into the endless groove 21 on each surface of the core plate 11. In addition, the inner surface of each membrane 12 is provided with an annular sealing rib 26 around the passage 15 and this rib is inserted into the annular groove 22 'on each surface of the core plate 11. Finally, a horizontal extending sealing rib 27 is located at the lower portion of the top projection 14 on the filter plate and this rib is inserted into the horizontal groove 23 on each surface of the core plate 11.

The diaphragms 12 are fixedly mounted to the front and back of the core plate 11 by mounting elongate and endless edges or collars 28 arranged on the periphery of the diaphragms 12 on the periphery of the core plate 11 and by attaching the claims 28 to the periphery of the core plate at intervals screws 29 are inserted into threaded holes in the core plate through clamping strip 31 and collars 28.

The collar 28 on each membrane 12 has an endless and elongate projection 32, such that the collar has a hail-like shape, and this projection 32 is inserted into the endless groove 24 on the periphery of the core plate 11. As usual, the filter plate 10 or each of 6 the membranes 12 on the outer surfaces are provided with a centrally recessed filter cloth support bed 33 which contains a plurality of projections 33a and passageways 33b for filtrate between the projections 33a.

According to the invention, the outer frame 13, which is in the form of a picture frame, is fixedly mounted on the periphery of the core plate 11, so that the collars or edges 28 of the membranes 12 are arranged between the periphery of the core plate 11 and the inner periphery of this outer frame 13. The outer frame 13 is fixed. to the core plate 11 by means of screws 34 which extend into threaded holes in the core plate 11, and by means of tubes to be described in more detail below. In addition, according to the invention, the thickness α of the outer frame 13 is arranged so that it is slightly smaller, for example 1 mm, than the distance β between the planar outward faces on the peripheral regions of the membranes 12.

In the filter plate 10 shown there is provided a packing device 35 of an elastic material of small material thickness, and this packing covers the filter plate 10 or its outer plates 18 around the slurry passage 15. The sealing device has several annular sealing ribs 36 on the outer surfaces.

As usual, the filter plate 10 is provided at the lower corners of the outer surfaces with outlet passageways 37 for filtrate which are connected to the passages 33b on the support bed 33. In addition, two fluid pipes 38 and 39 which open into the membranes 12 are attached to the filter plate 10. at locations where breakthroughs 40 and 41, respectively, are formed through the core plate 11. The outer frame 13 is also secured to the core plate 11 by these tubes 38 and 39.

The filter plate 10 shown can be used in a filter press in a conventional manner. FIG. 5a shows the use of such filter plates in the manner described in the aforementioned U.S.A. Patent No. 3,807,567. Prior to a filtration operation, the filter plates 10 are sealed tightly by means of hydraulic cylinders not shown in the drawing. In this case, the planar peripheral portions of the membranes 12 are pressed on two adjacent filter plates 10 against each other through two intermediate filter cloths 42, so that these edge portions are easily deformed due to the elasticity of the membranes, thereby providing sealing between the filter plates. A slurry to be filtered is introduced between the garments 42 through the passage 15, a corresponding passage in the garments, and a feed assembly 43 arranged between each of two adjacent filter plates 10. The feed assembly 43 having a horizontal passage 43a and a vertical passage 43b, are held tightly between the filter plates 10 so that the outer surfaces of the assembly 43 are pressed against the packing device 35 or the annular ribs 36 thereon, thereby providing a seal between the filter plates 10 and the feed assembly 43.

During a filtration operation, the slurry which is pressurized between the filter cloths 42 is filtered through the passages 15 of the filter plates 10 and the horizontal and vertical passages 43a and 43b of the feed assemblies 43, of the cloths 42, with filter cakes 44 remaining between the cloths 42 and the filtrate flowing through the passages 33b. and 37 into a filtrate discharge tube (not shown). During such a filtration operation, the slurry supplied under a pressure of, for example, 3-5 kp / cm is completely prevented from leaking due to the seals described above between each of two adjacent filter plates 10 and between the filter plates 10 and the feed assemblies. 43. It should be noted that permanent deformations or fatigue of the rim portions of the membranes 12 will in no way be caused by these marginal portions projecting slightly in front of the outer surfaces of the outer frame 13, allowing only a slight elastic deformation thereof parts.

After a filtration operation, water or other fluid is introduced into the membranes 12 or filter plates 10 through the tube 38 2 under a pressure of, for example, 7-15 kp / cm along with purge air through the tube 39. In that case, the membranes 12 are expanded in a manner as shown in FIG. . 5b, so that filter cakes 44 between the filter cloths 42 are pressed, thereby dewatering the cakes.

During such a cake press operation, leakage of compressed fluid introduced into the membranes 12 is prevented as follows. First, the sealing ribs 25 operate on the inside of the membranes 12, which seal ribs are pressed against the bottom of the grooves 21 of the core plates 11, in the same way as an O-ring, so that leakage of compressed fluid against the periphery of each filter plate 10 is prevented.

In addition, the periphery of each membrane 12 tends to be displaced toward the horizontal direction, especially at the bottom portions of the plate 10 due to the weight of the membrane 12 which seeks to induce a reduction of the periphery, resulting in the sealing ribs 25 being pulled. out of the grooves 21, but the hail-like collar 28 of each membrane 12 or the elongate projecting portion 32 inserted into the groove 24 on the periphery of the core plate 11 prevents such displacements of the periphery of the membrane 12. Thus, a seal is obtained by the sealing ribs 25, even if the weight of the membranes 14 is very large and / or even if there is some clearance between the periphery of the membranes 12 and the inner periphery of the outer frame 13.

Leakage of compressed fluid against the slurry passage 15 during a cake press operation is prevented by the elongated sealing ribs 26 and 27 inserted in the grooves 22 and 23 of the core plate 11 and by the packing device 35.

After a cake press operation, water or other fluid introduced under pressure into the membranes 12 is ejected through the tube 38 so that the membranes are unloaded and contracted. For rapid fluid ejection, air can be introduced into the membranes through the tube 39. Thereafter, the filter plates 10 are separated and the filter cloths 42 carrying dewatered cakes 44 are moved downward together with the feed assemblies 43 for the cakes to be removed.

FIG. 6 shows another embodiment of the sealing ribs 25 and 27 on the inside of each membrane 12. Each of these ribs 25 and 27 has a hail-like shape. As the diaphragm 12 is expanded to compress filter cakes, the sealing ribs 25 and 27 are pressed against the side wall of the grooves 21 and 23 at the free edges of the ribs due to the tension applied to the diaphragm 12 so that the necessary sealing is achieved.

Although the filter plate 10 is shown in the drawing with a slurry passage 15 located at the top, such passage can be omitted in cases where slurry is applied in another conventional manner.