GB1569295A

GB1569295A - Filter press plates

Info

Publication number: GB1569295A
Application number: GB9069/76A
Authority: GB
Original assignee: Moseley Rubber Co Ltd
Current assignee: Moseley Rubber Co Ltd
Priority date: 1976-03-06
Filing date: 1976-03-06
Publication date: 1980-06-11
Also published as: JPS52118670A; DE2709676A1

Description

(54) FILTER PRESS PLATES (71) We, THE MOSELEY RUBBER COMPANY LIMITED, a British Company of Mancunian Way, Ardwick, Manchester M12 6HL, do hereby declare the invention, for which we pray that a Patent may be wanted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The invention concerns a membrane plate for a filter press, and a method of producing a membrane plate for a filter press.

According to conventional practice, the roduction of a membrane plate is by way of fabrication from an appropriate combina tion of previously formed elements, the membrane being a structure moulded to shape and being attached to a rigid base part of the membrane plate. A number of manufacturing and assembly operations are involved in the production of the membrane plate by the conventional method, the cost thereof reflecting on the cost of the end product.

The object of the present invention is to provide a method whereby the cost of producing a membrane plate might be mini raised.

Thus, according to the present invention, a method of producing a filter press mem brane plate having a body part and a flexible membrane attached thereto during a mould ing operation extending across at least one face thereof is characterised in that the membrane is moulded in situ on the said body part, the surface of the body part, at least in the region corresponding to a filtration area of said membrane plate hav ing poor or no adhesion to, or being "treated" as hereinafter defined so as to have poor or no adhesion to the material of the membrane to an extent sufficient to allow separation of the membrane from the body part in such region. By the term , treated it is intended to include coating or covering the surface of the body part.

The body part may be planar or recessed as is conventional in the art, or may comprise any other structure adequate to support or carry the membrane. The need to effect an adequate seal between the slurry feed and the space between the membrane and body of the membrane plate, to preclude the leakage of air under pressure within such space into the slurry feed, or vice versa, requires that sophisticated unions be provided whereat the slurry feed connects with the filter chamber through the membrane, the cost of such unions being high, and further contributing to the capital cost of a press.

The invention also includes a membrane plate produced by the method as aforesaid.

A further, and supplemental object of the invention is to provide a membrane plate wherein the possibility of leakage, especially, though not exclusively, at the slurry feed, is reduced.

Thus, according to a preferred feature of the invention, the membrane as moulded in situ is arranged to extend into any feed passage or connecting eye.

In the case of a double-sided membrane plate, a membrane is moulded in situ on both faces of the body part, the thus formed membrane having portions on each face connected together through the feed passage or connecting eye.

The invention will now be described further, by way of example only, with reference of the accompanying diagrammatic drawings illustrating two embodiments thereof, and in which: Figure 1 is a diagrammatic front elevation of a membrane plate having a corner feed passage therein; Figure 2 is a section on line A-A of Figure 1, drawn to a larger scale; and Figure 3 is a vertical section through a double-sided membrane plate having a centre feed eye.

Referring now to the drawing, and particularly to Figures 1 and 2 thereof, a singlesided membrane plate has a body part 11 and a membrane 12 in intimate contact with one face thereof, the membrane 12 having been moulded in situ onto the body part.

The body part 11 is generally of conventional form, having a recess 13, 13' at each face thereof and a corner feed passage 14, the body part being recessed, as at 15, in the region of the feed passage 14 at the membrane side of the plate to accommodate a cloth locking union, not shown, and being counterbored, as at 16, in register with such feed passage at the other side of the plate.

The membrane 12 is in intimate contact with the surface of the body part 11, and has a neck 17 which extends through the feed passage 14, the remote end of the neck 17 having a radially outwardly directed collar 18 coextensive with the counterbore 16.

By ensuring that poor or no adhesion exists as between the membrane 12 and the body part 11 in the region of the recess 13, the application of air under pressure to the back of the memebrane through the air inlet 19 will separate such membrane from the surface of the recess.

The air chamber defined by and between the membrane 12 and the recess in the body part will be sealed about the periphery of the recess 13 by a bonding of the membrane 12 to the flange 11' of the body part, but even in the absence of a bond an effective seal will still be achieved by virtue of the compression of the membrane on assembly and closing of the press of which the membrane plate forms a part. Any inadequacy of the compression as regard sealing the membrane in relation to the flange 11' of the body part 11 will be countered by the presence of the integral neck 17 which extends through the feed passage 14 and by the collar 18 at the remote end of such neck.

In a second embodiment, see now Figure 3, a membrane 21, 21' is applied to both faces of a body part 22, the said body part 22 being totally enclosed within the total membrane structure, and such structure extending also through the centre-feed eye 23 of the plate 24. By arranging that there is poor or no adhesion as between the material of the membrane 21, 21' and the body part, at least in the recess regions 25, 25' of the latter, the membrane 21, 21' can be separated from the surfaces of the recesses 25, 25' on the introduction of air under pressure to the back of the membrane.

The body part may be formed from any of a variety of materials, the preferred material of choice being steel, although such as alloys or synthetic plastics materials may have application in this context.

It is to be appreciated that the face of the membrane will ordinarily have a drainage surface of conventional form and means will be provided in the flange area for free removal of the filtrate. For example, a hole may be provided in the flange and extending from the drainage surface either to a drainage eye or to a position outside the flange area, there being a drainage tap or not, as preferred, in the drainage means. In some circumstances it may be preferred that a tube be located in a channel in the flange area, rather than provide a hole in the flange.

Furthermore, such stay bosses as are thought appropriate will be embodied in the or each membrane plate, stav boss reinforcements being provided on the bodty, or not, as preferred.

The complete envelope as defined by the total membrane structure absolutely precludes the leakage of air on the introduction of air under presure into the space behind the membrane portions, and thus the need to provide sophisticated unions for sealing purposes is avoided.

However, in order to provide a means for venting the space or spaces between the membrane and the body part of the membrane plate in the event that air under pressure is applied to such space or spaces with the press in an open condition, it is proposed that one or more apertures be provided through the membrane in the flange area, which aperture or apertures is or are automatically sealed on press closure by abutment of the flange with an opposed surface.

If desired, a membrane support ring or the like may be positioned within the feed eye or feed passage to support the membrane in such location. Alternatively, the rings may be embodied in the membrane during the moulding operation.

Membrane reinforcement may also be provided in appropriate areas by including suitable reinforcing materials in the membrane during the moulding thereof.

The integral character of the membrane structure in the region of the feed eye 23 also avoids the need for a complicated connection means for what would otherwise be two separate membranes overlapping at the entrance to the eye, and furthermore, provides a larger diameter eye for a given filter area or a greater area of filtration for a given size of eye. A simpler cloth locking union may be used than is the case with conventional "connected" membranes, or even a barrel-cloth having two portions connected by a sleeve may be utilised.

In the art, the body parts of the press plates which are often used in conjunction with membrane plates are of moulded form.

Having regard to the fact that the profile of a press-plate may correspond to that of a related membrane plate when the mem brane of such plate is in intimate contact with the surface of the body part of the plate, a like mould can be used for moulding press plates and the membrane plates of the present invention, thereby reducing the tooling requirements of a manufacturer involved in plate manufacture.

A further advantage of the arrangement as proposed is that the high degree of flexing which occurs in the region of the feed union, especially for corner feed structures, is avoided, and thus the failure of a membrane resulting from such severe flexing does not occur.

It is to be appreciated that the invention hereindisclosed will allow of the re-use of an existing plate body by stripping of the existing membrane therefrom and the moulding of a replacement membrane onto such plate body.

Usually, however, the membrane, especially in the case of a single-sided membrane plate will be positively bonded to the body part in the flange and feed passage areas thereof.

As a development of this invention, it is possible to form a double-sided membrane on a frame body, a separator layer being included between the individual membrane layers to allow of the separation thereof after moulding, such separator layer comprising, for example, a paper sheet or a coating of the non-stick material on the sheet material from which the membrane layers are formed.

WHAT WE CLAIM IS: 1. A method of producing a filter press membrane plate having a body part and a flexible membrane attached thereto during a moulding operation and extending across at least one face thereof, comprising moulding the membrane in situ on the said body part, the surface of the body part, at least in the region corresponding to a filtration area of said membrane plate having poor or no adhesion, or being "treated" as hereinbe ore defined so as to have poor or no an esion to the material of the membrane to extent sufficient to allow separation of the membrane from the body part in such region.

2. The method as claimed in claim 1, including the further steps of separating the membrane from the body part in that region thereof corresponding to the filtration area, subsequent to the moulding operation.

3. The method as claimed in claim 1 or 2, wherein the membrane is adhered to the body part about the periphery of the filtration area during the moulding operation.

4. The method as claimed in claim 2 or claim 3, wherein the membrane is separated from the adjacent surface or surfaces of the body part in those regions whereat separa tion is to be effected, by the introduction of pressure fluid to the membrane/surface interface.

5. A method acording to any one of claims 1 to 4, wherein the body part is formed with a recess on at least one face thereof and said membrane is moulded in situ to be attached to said at least one face and to conform to the recessed form of said body part.

6. A membrane plate for a filter press comprising a body part and a membrane attached thereto during a moulding operation at at least one face of the said body part, the membrane having been moulded in situ onto the previously formed said body part and wherein the membrane is separable from the body part in the intended region of filtration.

7. A membrane plate as claimed in claim 6, wherein the membrane is bonded to such part outwardly of such region in the general plane of the membrane plate.

8. A membrane plate as claimed in claim 6 or 7, wherein the body part includes a feed passage and the membrane includes a neck which extends into such feed passage.

9. A membrane plate as claimed in claim 8, wherein the membrane extends over one face of the body part and wherein that end of the feed passage remote from the membrane includes a counterbore and a collar is provided at the remote end of the neck in engagement with such counterbore.

10. A membrane plate as claimed in claim 6 or 7, wherein a membrane is provided on both faces of the body part, the membrane having portions on each face connected together by a neck which extends through a feed passage or connecting eye in the body part.

11. A membrane plate as claimed in any one of claims 7 to 10, wherein the or each face of the body part is recessed and the membrane conforms to the contour of the or each respective recessed face.

12. The method of producing a filter press membrane plate, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

13. A membrane plate for a filter press substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 or in Figure 3 of the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. brane of such plate is in intimate contact with the surface of the body part of the plate, a like mould can be used for moulding press plates and the membrane plates of the present invention, thereby reducing the tooling requirements of a manufacturer involved in plate manufacture. A further advantage of the arrangement as proposed is that the high degree of flexing which occurs in the region of the feed union, especially for corner feed structures, is avoided, and thus the failure of a membrane resulting from such severe flexing does not occur. It is to be appreciated that the invention hereindisclosed will allow of the re-use of an existing plate body by stripping of the existing membrane therefrom and the moulding of a replacement membrane onto such plate body. Usually, however, the membrane, especially in the case of a single-sided membrane plate will be positively bonded to the body part in the flange and feed passage areas thereof. As a development of this invention, it is possible to form a double-sided membrane on a frame body, a separator layer being included between the individual membrane layers to allow of the separation thereof after moulding, such separator layer comprising, for example, a paper sheet or a coating of the non-stick material on the sheet material from which the membrane layers are formed. WHAT WE CLAIM IS:

1. A method of producing a filter press membrane plate having a body part and a flexible membrane attached thereto during a moulding operation and extending across at least one face thereof, comprising moulding the membrane in situ on the said body part, the surface of the body part, at least in the region corresponding to a filtration area of said membrane plate having poor or no adhesion, or being "treated" as hereinbe ore defined so as to have poor or no an esion to the material of the membrane to extent sufficient to allow separation of the membrane from the body part in such region.