Filter press

Abstract

A filter press may comprise a plurality of plates 2, wherein adjacent plates are coupled together by straps 10 attached to the outer sides of each plate via mounting brackets 12. Each strap and mounting may be adapted to prevent the strap from folding inwardly between the pair of plates as they move between their discharge and working configurations. The strap may be formed as a 3-ply configuration of flexible material with a loop at each end for mounting to the plates and may have markings on its surface to facilitate correct orientation of the strap during fitting.

Description

FIELD OF THE INVENTION This invention relates to an improved filter press. BACKGROUND OF THE INVENTION A filter press is a device for dewatering sludge comprising a plurality of plates, each supporting a sheet of filter material, the plates being mounted in a row so that they can be arranged in a working configuration, wherein they are all pressed together, and a discharge configuration, wherein there is a gap between adjacent plates to allow removal of solid residue, known as “press cake”, collected therebetween. When the plates are pressed together in their working configuration, wet sludge is pumped through the plates of the filter press under pressure, typically via a central passage extending through a central region of each of the plates. Water passes through the filter material of the plates to pass out of water outlets, typically communicating with water collection openings extending through the plates adjacent outer corners thereof, solid residue being trapped between the plates for subsequent removal when the plates are separated from one another in their discharge configuration. To ensure that all of the plates are pulled apart from one another when they are moved to their discharge configuration, adjacent plates are typically coupled to one another via chains attached to the outer sides of each plate. A problem with known filter presses is that these chains define the spacing between the plates when in their discharge configuration and this is then limited by the length of the chain links. Furthermore, the chains can become trapped between adjacent filter presses as they moved from their discharge configuration to their working configuration, preventing the plates from closing correctly and leading to damage to the chains. Furthermore, the links of the chains tend to wear over time, resulting in an elongation of overall chain length. This elongation can lead to gaps between adjacent plates becoming uneven when in their discharge configuration, some gaps becoming too large and some too small to properly release the cake or for the wash bar to extend down between adjacent plates. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a filter press comprising a plurality of plates, each supporting a sheet of filter material, the plates being mounted in a row so that they can be arranged in a working configuration, wherein they are all pressed together, and a discharge configuration, wherein there is a gap between adjacent plates to allow removal of solid residue collected therebetween, adjacent plates being coupled to one another via straps attached to the outer sides of each plate, each strap being coupled to and extending between an adjacent pair of plates. The use of straps provides greater control over the gap between adjacent plates when in their discharge configuration and avoids the problem of elongation experienced when chains are used. Preferably each strap and / or its mounting on an outer side of a respective plate is / are adapted to prevent the respective strap from folding inwardly between the respective pair of adjacent plates to which the respective strap is attached as the plates are moved from their discharge configuration to their working configuration. In one embodiment each strap preferably has a respective mounting loop formed at each end thereof, each mounting loop receiving a respective mounting pin provided on a mounting bracket attached to an outer side of a respective plate to couple the strap thereto, each mounting bracket including an abutment arranged adjacent each respective mounting pin to prevent the respective strap from folding inwardly between the respective pair of adjacent plates to which the respective strap is attached as the plates are moved from their discharge configuration to their working configuration. Each mounting bracket may include a base plate secured to an outer side of a respective plate and a pair of upper and lower mounting plates extending from the base plate parallel to one another and vertically spaced from one another, said pair of upper and lower mounting plates having aligned pairs of apertures, each pair of mounting apertures receiving a respective mounting pin therein to couple an end of a respective strap thereto, a respective abutment being provided adjacent each pair of apertures in the upper and lower plates adjacent a respective outer side of each pair of upper and lower mounting plates. Said abutments on each mounting bracket may each comprise a respective bar mounted on and extending between the pair of upper and lower mounting plates of each bracket and arranged alongside a respective pair of apertures adjacent an outer side of the respective pair of mounting plates, such that the bars prevents the straps from folding inwardly between the respective adjacent pair of plates to which they are attached. Each strap may comprise an elongate strip of material comprising a first strap portion defining a central ply of the folded strap, a second strap portion folded with respect to the first strap portion to define a first mounting loop at a first end of the strap and to define an inner ply of the folded strap arranged to face inwardly when the strap is fitted to the mounting plates, and a third strap portion folded with respect to the second strap portion to define a second mounting loop at a second end of the strap, opposite said first end and to define an outer fly of the folded strap arranged to face outwardly when the strap is fitted to the plates such that the straps preferentially fold outwardly with respect to the outer sides of the plates as the plates are moved from their discharge configuration to their working configuration. An outer surface of one or both of the inner and outer plies of the strap may incorporate markings to facilitate correct orientation of each strap, when fitting to the mounting plates. According to a further aspect of the present invention there is provided a strap for interconnecting plates of a filter press, said strap comprising an elongate strip of material comprising a first strap portion defining a central ply of the folded strap, a second strap portion folded with respect to the first strap portion to define a first mounting loop at a first end of the strap and to define an inner ply of the folded strap arranged to face inwardly when the strap is fitted to the mounting plates, and a third strap portion folded with respect to the second strap portion to define a second mounting loop at a second end of the strap, opposite said first end and to define an outer fly of the folded strap arranged to face outwardly when the strap is fitted to the mounting plates of a filter press. Preferably an outer surface of one or both of the inner and outer plies of the strap incorporates markings to facilitate correct orientation of the strap, when fitting to the plates of a filter press. BRIEF DESCRIPTION OF THE DRAWINGS A filter press in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a filter press in accordance with an embodiment of the present invention in a working configuration; Figure 2 is a detailed perspective view of the filter press of Figure 1; Figure 3 is a detailed perspective view of a coupling strap and associated fastening brackets of the filter press of Figure 1; Figure 4 is a plan view of the coupling strap and associated fastening brackets of Figure 3; Figure 5 is a plan view of the strap with the brackets omitted for clarity; Figures 6 and 7 are perspective view of a coupling strap used of the filter press of Figure 1; Figure 8 is a plan view of the strap of Figures 6 and 7; and Figure 9 is a perspective view of the strap of Figures 6 and 7 in a folded configuration. DETAILED DESCRIPTION OF THE DRAWINGS As illustrated in Figure 1 and 2, a filter press in accordance with an embodiment of the present invention comprises comprising a plurality of plates 2, each supporting a sheet of filter material 4, the plates 2 being mounted in a row so that they can be arranged in a working configuration, as shown in Figures 1 and 2, wherein they are all pressed together, and a discharge configuration (not shown), wherein there is a gap between adjacent plates to allow removal of solid residue, known as “press cake”, collected therebetween. When the plates are pressed together in their working configuration, wet sludge is pumped through the plates of the filter press under pressure via a central passage 6 extending through a central region of each of the plates 2. Water passes through the filter material 4 of the plates 2 to pass out of water outlets communicating with water collection openings 8 extending through the plates 2 adjacent outer corners thereof, solid residue being trapped between the plates for 2 subsequent removal when the plates 2 are separated from one another in their discharge configuration. To ensure that all of the plates 2 are pulled apart from one another when they are moved to their discharge configuration, adjacent plates 2 are coupled to one another via straps 10 attached to the outer sides of each plate 2 adjacent upper and lower ends of each plate 2. The straps 10 are connected to outer sides of each plate 2 via mounting brackets 12. In the embodiment shown in Figure 3 and 4, each mounting bracket 12 includes a base plate 14 secured to an outer side of a respective plate 2 and a pair of upper and lower mounting plates 16,18 extending from the base plate 14 parallel to one another and vertically spaced from one another, the mounting plates 16,18 of each mounting bracket 12 having aligned pairs of apertures 20,22, laterally spaced from one another, each pair of mounting apertures 20,22 receiving a respective mounting pin 24 therein to couple a looped end of a respective strap 10 thereto. Each mounting bracket 12 is fitted with respective strap fold diverter bars 26,28 extending between the upper and lower mounting plates 26,28 adjacent to each mounting pin 24 and on the outer sides of each pair of upper and lower mounting plates 16,18 to engage the ends of each strap 10 and ensure that the respective strap 10 folds outwardly away from the outer sides of the plates 2, as best shown in Figure 3, due to the relative position of the diverter bars 26,28 to the mounting pins 24 retaining the ends of each strap 10 to the mounting brackets 12, the diverter bars 26,28 causing a slight outward kink in the ends of each 10 when the plates 2 are in their discharge configuration. Furthermore, as illustrated in Figures 5 to 9, each strap 10 comprises an elongate strip of material comprising a first strap portion 30 defining a central ply of the folded strap 10, a second strap portion 32 folded with respect to the first strap portion 30 to define a first mounting loop 34 at a first end of the strap 10 and to define an inner ply of the folded strap 10 arranged to face inwardly when the strap 10 is fitted to the respective mounting brackets 12 of the plates 2, and a third strap portion 36 folded with respect to the second strap portion 32 to define a second mounting loop 38 at a second end of the strap, opposite said first end and to define an outer ply of the folded strap 10 arranged to face outwardly when the strap 10 is fitted to the respective mounting brackets 12 of the plates 10, such that the straps 10 preferentially fold outwardly with respect to the outer sides of the plates 2 as the plates 2 are moved from their discharge configuration to their working configuration. Due to this construction of the straps 10, they exhibit a tendency to fold a particular way. To ensure they are fitted to utilise this property, labels 40 stating “FACING IN” are applied to the outer faces of the second strap portion 32 of each strap 10 to ensure the correct orientation during installation. The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention.

Claims

1. A filter press comprising a plurality of plates, each supporting a sheet of filter material, the plates being mounted in a row so that they can be arranged in a working configuration, wherein they are all pressed together, and a discharge configuration, wherein there is a gap between adjacent plates to allow removal of solid residue collected therebetween;adjacent plates being coupled to one another via straps attached to the outer sides of each plate, each strap being coupled to and extending between an adjacent pair of plates;wherein each strap has a respective mounting loop formed at each end thereof, each mounting loop receiving a respective mounting pin provided on a mounting bracket attached to an outer side of a respective plate to couple the strap thereto;wherein each mounting bracket includes a base plate secured to an outer side of a respective plate and a pair of upper and lower mounting plates extending from the base plate parallel to one another and vertically spaced from one another, said pair of upper and lower mounting plates having aligned pairs of apertures, each pair of mounting apertures receiving a respective mounting pin therein to couple an end of a respective strap thereto, a respective abutment being provided adjacent each pair of apertures in the upper and lower plates adjacent a respective outer side of each pair of upper and lower mounting plates;wherein said abutments on each mounting bracket each comprise a respective bar mounted on and extending between the pair of upper and lower mounting plates of each bracket and arranged alongside a respective pair of apertures adjacent an outer side of the respective pair of mounting plates, such that the bars prevents the straps from folding inwardly between the respective adjacent pair of plates to which they are attached as the plates are moved from their discharge configuration to their working configuration; andwherein each strap comprises an elongate strip of material comprising a first strap portion defining a central ply of the folded strap, a second strap portion folded with respect to the first strap portion to define a first mounting loop at a first end of the strap and to define an inner ply of the folded strap arranged to face inwardly when the strap is fitted to the plates, and a third strap portion folded with respect tothe second strap portion to define a second mounting loop at a second end of the strap, opposite said first end and to define an outer fly of the folded strap arranged to face outwardly when the strap is fitted to the plates such that the straps preferentially fold outwardly with respect to the outer sides of the plates as the5 plates are moved from their discharge configuration to their working configuration.

2. A filter press as claimed in claim 1, wherein an outer surface of one or both of the inner and outer plies of the strap incorporates markings to facilitate correct orientation of each strap, when fitting to the mounting plates.29 11 24

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