GB2069358A

GB2069358A - Reinforced membrane

Info

Publication number: GB2069358A
Application number: GB8005152A
Authority: GB
Original assignee: Moseley Rubber Co Ltd
Current assignee: Moseley Rubber Co Ltd
Priority date: 1980-02-15
Filing date: 1980-02-15
Publication date: 1981-08-26

Abstract

A membrane (15) for use with a filter press plate (10) has a reinforcing layer (16) therein in the or each region of contact of the membrane (15) with a stay boss (13) of the plate (10). The reinforcing layer (16) is located adjacent the cloth-supporting surface (17) of the membrane (15) remote from the boss (13) and a second reinforcing layer (18) may be provided adjacent the boss contacting surface (19). An intermediate reinforcing layer may also be provided. The reinforcing layers, (16, 18) of square woven fabric or apertured steel plate, prevent lateral spreading of the membrane (15) under load in the regions of the bosses (13) and thus prolong membrane life. <IMAGE>

Description

SPECIFICATION Reinforced membrane This invention relates to membrane plates of filter presses and in particular to the membranes of such plates.

Membrane plates for such filter presses are formed having relatively thin central regions and relatively thick peripheral rims whereby a recess is provided in the opposed faces of the plate. When a plurality of such plates are placed in face to face disposition in a press the aforesaid recesses provide cavities between adjacent plates, contact between adjacent plates being in the peripheral rim regions. In order to prevent or minimise distortion of the plates under load it is known to provide raised portions, or stay bosses, on the base of the recesses. Such bosses have a height equal to or slightly less than the depth of the recess so that bosses on adjacent plates contact each other when the plates are under load thus preventing or minimising plate distortion.However, with such plates it has been found that the life of a membrane and/or filter cloth in the region of such stay bosses. This necessitates frequent and expensive replacement of the membrane plates and/or the filter cloths.

It is object of the present invention to provide means whereby the frequency, by which the membranes and/or filter cloths associated with filter plates having stay bosses thereon require replacement, is reduced considerably.

The invention provides a membrane, for use with a membrane plate having a recess in at least one face thereof, a rim portion extending around said recess and at least one boss extending outwardly of the base of said recess, said member having a reinforcing layer therein at least in the region thereof which in use is contacted by said boss whilst said membrane extends across said recess, said reinforcing layer being located adjacent the boss-remote surface of said membrane.

The invention also provides a membrane plate and membrane as aforesaid, and said membrane may be secured to said membrane plate at least in the region of the rim portion thereof.

The reinforcing layer may lie in the range .25 mm to 6 mm below said outer surface of the membrane, and preferably in the range .25 mm to 2.5 mm below said outer surface.

The membrane may have a second reinforcing layer in the region contacted by said boss adjacent the inner boss-adjacent surface of the membrane.

The reinforcing layer may lie in the range .25 mm to 6 mm below said inner surface of the membrane, and preferably in the range .24 mm to 2.5 mm below said inner surface.

Preferably the or each reinforcing layer is bonded into the material of the membrane and the or each reinforcing layer may comprise a square woven fabric or a metal sheet. In the latter case the sheet is preferably apertured and of steel.

One embodiment of membrane plate in accordance with the invention will now be described with reference to the accompanying drawing in which~ Fig. 1 is a front elevation; and Fig. 2 is a sectional plan on line 2-2 of Fig. 1.

Referring now to the Figures, there is shown a membrane plate 10 having a recess 11 in each face thereof and a rim portion 12 extending around each recess 11. Stay bosses 13 are provided on the membrane plate 10, each of such bosses 13 being shown, whereby each boss 13 extends outwardly of the base 14 of a recess 1 1.

A single membrane 15 is moulded onto the plate 10 and is attached thereto in the region of the rim 20 so as to extend across the recesses 1 The height of the bosses 13 is equal to or slightly less than the depth of a recess 11.

In use as slurry is introduced through inlet 15 into the cavity formed by the recesses 1 1 of adjacent plates 10 the membrane 1 5 if forced to conform to the surface of the membrane plate 10 and lie in contact with bases 14 and bosses 13 as shown in Figs. 2.

In the membrane 15, in the region thereof contacted by each boss 13, there is a reinforcing layer 16 adjacent the outer boss-remote surface 1 7. Also in the same region there is a second reinforcing layer 18 adjacent the inner, boss contacting surface 19.

Each reinforcing layer 16, 18 lies within the range .25 mm to 6 mm, and preferably within the range .25 mm to 2.5 mm, of the adjacent surface 17, 19 of the membrane 1 5. Each reinforcing layer is of a square woven fabric or apertured steel sheet and is bonded to the rubber material from which the membrane is made, reinforcing layers 1 6 and 18 preferably but not necessarily being of the same material.

The reinforcing layers 16, 18 will allow substantially no movement or stretch of the membrane 1 5 in the plane of the membrane, such as tends to occur in the region of the bosses 13 in unreinforced membranes under the compressive forces exerted thereon in use.

The further the reinforcing layer 1 6 lies below the surface 1 7 of the membrane 1 5 the greater is the tensile strength required by that reinforcing layer in order to prevent such aforementioned movement and stretch of the membrane under applied compressive loading. In consequence it is preferred that the reinforcing layer 16 is as close to the surface 17 as is possible whilst still maintaining a layer of membrane material between the layer 16 and a filter cloth (not shown) in contact with the surface 17.

The provision of a second reinforcing layer 18 in the membrane 15 further assists in preventing or minimizing lateral stretch of the membrane 1 5 in the region of the bosses 13, particularly advantageous when very large compressive forces are to be applied to the membrane. In such circumstances a further intermediate reinforcing layer or layers may be provided in this region of the membrane 15.

Claims

1. A membrane, for use with a membrane plate having a recess in at least one face thereof, a rim portion extending around said recess and at least one boss extending outwardly of the base of said recesses, said membrane having a reinforcing layer therein at least in a region thereof which in use is contacted by said boss whilst said membrane extends across said recess.

2. A membrane according to claim 1 wherein said reinforcing layer is located adjacent an outer surface of said membrane which in use is remote from said boss.

3. A membrane according to claim 2 wherein said reinforcing layer lies at a distance of between .25 and 6 mm from said outer surface.

4. A membrane according to claim 3 wherein said reinforcing layer lies at a distance of between .25 and 2.5 mm from said outer surface.

5. A membrane according to any one of claims 2 to 4 having a second reinforcing layer in said region said second reinforcing layer being located adjacent an inner surface of said membrane which in use is adjacent said boss.

6. A membrane according to claim 5 wherein said second reinforcing layer lies at a distance of between .25 and 6 mm from said inner surface.

7. A membrane according to claim 6 wherein said second reinforcing layer lies at a distance of between .25 and 2.5 mm from said inner surface.

8. A membrane according to any one of claims 1 to 7 wherein the or each reinforcing layer is bonded into the material of the membrane.

9. A membrane according to any one of claims 1 to 8 wherein the or each reinforcing layer comprises a square woven fabric.

10. A membrane according to any one of claims 1 to 8 wherein the or each reinforcing layer comprises a metal sheet.

1 1. A membrane according to claim 10 wherein said metal sheet is perforate.

12. A membrane according to claim 10 or claim 11 wherein said metal sheet is of steel.

13. A membrane according to claim 5 or any claim dependent thereon comprising a third reinforcing layer intermediate said reinforcing layers.

14. A membrane plate having a recess in at least one face thereof, a rim portion extending around said recess, at least one boss extending outwardly of the base of said recess and a membrane according to any one of claims 1 to 13.

15. A membrane plate according to claim 14 wherein said membrane is secured to said plate at least in the region of said rim portion.

16. A membrane plate according to claim 14 of claim 15 having a recess in each face thereof, at least one boss extending outwardly of each recess base and a membrane extending across each recess.

17. A membrane plate according to claim 16 comprising a single membrane moulded onto said plate so as to extend across both recesses.

18. A membrane plate according to any one of claims 14 to 1 7 comprising a plurality of bosses extending outwardly from the or each recess.

19. A membrane plate according to any one of claims 14 to 18 wherein the height of the or each boss is equal to or less than but substantially equal to the depth of the or each respective recess.

20. A membrane substantially as hereinbefore described.

21. A membrane plate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.