AN OUTLET COVER FOR AN INSERTED PLATE FILTER, A FILTER PLATE, A FILTER PLATE ASSEMBLY, AND AN INSERTED PLATE FILTER

Abstract

The description relates to an outlet cover (1) with a first fixing bolt (3) fixed to the outlet cover and having a radially extensible portion (3b) deformable by a radial force exerted from a hollow interior of the first fixing bolt. The radially extensible portion (3b) prevents the first fixing bolt (3) from dislodging from an associated fixing hole (10a), while allowing the first fixing bolt (3) to be further compressed in the associated fixing hole (10a), thereby preventing a fastening element (15) from dislodging any retaining surface and increasing the service life of the outlet cover (1). It also relates to an associated filter plate (6), a filter plate assembly, and a filter.

Description

AN OUTLET COVER FOR AN INSERTED PLATE FILTER, A FILTER PLATE, A FILTER PLATE ASSEMBLY, AND AN INSERTED PLATE FILTER Field of Invention This description relates to flush-mounted plate filters, such as filter presses and tower presses. More specifically, this description relates to an outlet cover, a filter plate, and a filter plate assembly for such a filter. This description also relates to such a flush-mounted plate filter. Background of the Invention Outlet caps are used on flush-mounted plate filters to cover and protect the outlet openings and prevent them from becoming blocked, allowing the filtrate to flow freely from the filter chamber. Specifically, outlet caps prevent the filter cake from pushing the filter cloth into the outlet opening. Typically, outlet caps are attached to an associated filter plate, either directly or via a diaphragm. In addition, the outlet caps are simultaneously used to protect the filter cloth from a drying airflow used to dry the filter cake by preventing the drying airflow from being blown directly onto the filter cloth. For example, the outlet cap may have been provided with a protrusion that presses into a groove formed in a diaphragm to create a frictional fit. However, this requires a corresponding shape on an associated filter plate to accommodate both the groove in the diaphragm and the protrusion on the outlet cap. Providing such shapes on filter plates has been found to result in excessive internal stresses in critical areas of the filter plate, leading to insufficient filter plate lifespan. Alternatively, the outlet caps may have been conventionally attached to the filter plate using self-tapping screws that fit into an unthreaded pilot hole in the associated filter plate. However, such threads have been found to wear under repetitive compression (i.e., when the filter plates are pressed together to close the filter chamber during the filtration cycle). In other words, during filter operation, considerable axial force is exerted on the screws, which wears down the threads in the plates, often made of a weaker material. Another conventional way to attach the outlet cover to the filter plate has been to use separate threaded inserts, which attach to the filter plate and can be replaced separately. Additionally, through bolts and nuts have also been used to attach an outlet cover to a filter plate. All known prior art solutions for attaching the outlet cap to the filter plate discussed above share a problem related to repetitive compression cycles during operation that exert considerable axial loads on the outlet cap, causing threads to strip, inserts to shear and loosen, or other similar problems resulting in poor lifespan of the joints between the outlet cap and the filter plate. US patent publication 5,045,191 describes a filter outlet plug, in which bolts are used to fit with an outlet of a filter plate. Summary of the Invention One object of the present description is to achieve an outlet cover, a filter plate, a filter plate assembly and a filter that provides greater longevity of the same. The object of the description is achieved by means of an outlet cover, a filter plate, a filter plate assembly, and a filter, characterized as set forth in the independent claims. Preferred embodiments of the description are described in the dependent claims. The description is based on the idea of ​​providing the outlet cover with a first fixing bolt that is fixed with respect to the outlet cover and has a radially extensible part, which can be radially deformed away from the remaining first fixing bolt by a radial force exerted on the extensible part from a hollow interior of the first fixing bolt. In this way, the radially extendable part provides a coupling between the first fixing bolt and an associated filter plate strong enough to prevent the first fixing bolt from being pulled out of an associated fixing hole, while allowing the first fixing bolt to be compressed further into the associated fixing hole (i.e., when the filter plates are pressed together during each filtration cycle), thus preventing a safety element from detaching from any retaining surface and thereby increasing the longevity of the outlet cap. Brief Description of the Drawings The invention will now be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which rzcAnn / zznzB / γΐΛΐ Figure 1 schematically illustrates a perspective view of a filter plate assembly according to one embodiment of the present description, as shown in a perspective view; Figure 2 schematically illustrates a perspective view of an outlet cover according to one embodiment of the present description, viewed from an exterior side thereof. Figure 3 schematically illustrates a perspective view of the outlet cover of Figure 2, viewed from the fixing side of the same; Figure 4 schematically illustrates a partially cut view of the filter plate assembly of Figure 1, showing a section cut along a first fixing bolt; Figure 5 schematically illustrates a partially cut view of the filter plate assembly of Figure 1, showing a section cut along a conduit of a flow baffle, and Figure 6 schematically illustrates a partially cut view of the filter plate assembly of Figure 1, showing a section cut along a second fixing bolt. Detailed Description of the Invention According to the first aspect of this description, an outlet cover 1 is provided for a recessed plate-type filter, such as a filter press or tower press. More specifically, the outlet cover is suitable for a recessed plate-type filter equipped with a diaphragm for crushing a filter cake formed in a filtration chamber. The outlet cover 1 comprises a flat base 2 having a generally flat side, which defines an outer side 2a of the outlet cover. The flat base 2 also has an opposite side, which defines a fixing side 2b of the outlet cover 1, to be fixed against a diaphragm filter plate assembly. The outlet cover 1 further comprises one or more first fixing bolts 3 that protrude perpendicularly a distance from the fixing side 2b of the base 2. The first fixing bolt 3 need not be perpendicular to the base 2, but must extend perpendicularly from it. The outlet cover 1 further comprises a flow deflector 4 projecting perpendicularly a distance from the mounting side 2b of the base 2. The flow deflector 4 need not be perpendicular to the base 4, but must extend perpendicularly from it. The flow deflector 4 comprises at least one conduit 4a for diverting flow from a side 2c of the transverse chamber perpendicularly to the joining side 2b, and vice versa. In practice, the conduit 4a is arranged to be suitable for conveying flow from a filter chamber to a collection channel 9a of a filter plate 6, and vice versa. In connection with this description, the side 2c of the chamber is defined as the side of the outlet cover 1 transverse to both the outer side 2a and the joining side 2b thereof, and lying between the two. In particular, the first fixing bolt 3 has a hollow housing 3a, the inside of which opens at least to the outside, through the base 2. At least one radially extensible portion 3b is provided on the first fixing bolt 3, to allow the extensible portion 3b to deform radially away from the remaining housing 3a by a radial force exerted on the extensible portion from the hollow interior of the first fixing bolt 3. In addition, the first one or more fixing bolts 3 are fixed parts of the base 2. Preferably, but not necessarily, the one or more fixing bolts 3 are integral parts of the base 2. Preferably, but not necessarily, outlet cover 1 is formed from a single integral piece. In a modality according to the first aspect of the present description, the radially extensible portion 3b of the first fixation bolt 3 is provided in a distal portion of the first joining protrusion. This contributes to achieving limited clearance between the outlet cap 1 and an associated filter plate 6 under compression by allowing a tight coupling to form in the pull-out direction between the first fixing bolt 3 and a first associated fixing hole 10a, the diameter of which increases towards its lower portion. This, in turn, further increases the service life of the outlet cap 1 itself. In the context of this description, the distal portion of the first fixation bolt 3 is used to describe a portion of the fixation bolt 3 that extends for no more than half its length from the distal end of the fixation bolt into the base 2. Preferably, but not necessarily, the distal portion may be defined as a portion of the fixation bolt 3 that extends for no more than 1 / 3 of its length from the distal end of the fixation bolt into the base 2. More preferably, but not necessarily, the distal portion may be defined as a portion of the fixation bolt 3 that extends for no more than 1 / 4 of its length from the distal end of the fixation bolt into the base 2. ρζρβηη / ζζηζ / Β / γίΛΐ In one embodiment according to the first aspect of the present description, the interior of the hollow housing 3a is further opened towards the fixing side 2b. In other words, the distal end of the hollow interior of the first fixing piece 3 is open. Consequently, the extensible feature of the first fixing bolt 3 is increased at the distal end of the first fixing bolt 3. In one embodiment according to the first aspect of the present description, the extendable part 3b is formed partially separate from the remaining housing 3a of the first fixing bolt 3. This allows the extendable part 3b to be deflected radially away from the remaining housing 3a by a radial force exerted on the extendable part from the hollow interior of the first fixing bolt 3. This provides the advantage that the first fixing bolt 3, and preferably the entire outlet cover 1, can be made of a more rigid material and, at the same time, allow for their extensible characteristics, compared to a fixing bolt in which the extensible part is not partially separated from the remaining housing. Preferably, but not necessarily, the radially extendable portion 3b of the first fixing bolt 3 is partially separated from the remaining housing 3a by at least one cut 3b' that extends radially along the housing 3a and axially along the first fixing bolt 3. More preferably, but not necessarily, the at least one cut 3b' extends through the housing 3a. More preferably, but not necessarily, said at least one cut 3b' extends from a distal end of the first fixing bolt 3 towards the flat base 3. This provides a structure of the extensible part 3b, in which radial extensibility is present mainly at the distal end of the first fixing bolt 3. Moreover, said structure is considered particularly advantageous in relation to an associated first fixing hole 10a of a filter plate 6, which has an inner diameter that increases towards the bottom of said hole 10a, since a secure fixation can be achieved that allows mutual clearance. In one embodiment according to the first aspect of this description, the first fixing bolt 3 has an inner diameter that decreases towards its distal end. This provides a structure for the extensible portion 3b, in which the radial extension capacity is primarily located at the distal end of the first fixing bolt 3. Furthermore, this structure is considered particularly advantageous in relation to an associated first fixing hole 10a of a filter plate 6, which has an inner diameter that increases towards the bottom of said hole 10a, as it allows for a secure connection that permits mutual clearance. ρζρβηη / ζζηζ / Β / γίΛΐ In one embodiment according to the first aspect of the present description, the base 2 of the outlet cover 1 extends from the flow deflector 4 a distance towards the side 2c of the chamber. This also prevents a filter cake formed inside a filtration chamber from pushing a filter cloth onto a conduit 4a, thus blocking it. Furthermore, the extended base 2 directs a drying flow into the filter chamber to be more aligned with the filter cloth upon contact, thereby reducing the abrasive effect on the filter cloth. In one embodiment according to the first aspect of the present description, the first one or more fixing bolts 3 are arranged in alignment with the flow deflector 4, on the 2c side of the chamber with respect to it. When an outlet cap 1 is provided on a lower edge of a filter plate 6, a gravity-discharged filter cake can adhere to or strike the outlet cap during discharge. This, in turn, can bend or otherwise damage the outlet cap, particularly because the flow baffle 4 forms a relatively large portion of the cap that is not attached to the filter plate. Consequently, it is advantageous to arrange the first one or more fixing bolts 3, as this provides greater support in an area that is more susceptible to deformation or damage caused by the discharge of the filter cake. Furthermore, if the outlet cap 1 is associated with a filter plate assembly equipped with a filter diaphragm 11, inherently equipped with a flow opening 13 to receive the flow deflector 4 through it, the arrangement of the first fixing bolts 3 accordingly provides greater support and secures the diaphragm 11 around the flow opening 13, thereby preventing the accumulation of solids between the diaphragm and the filter plate 6, and / or between the diaphragm 11 and the outlet cap 1. Preferably, but not necessarily, the first one or more fixing bolts are provided misaligned with the ducts 4a of the flow deflector 4, so that flow towards them is not obstructed. In an embodiment according to the first aspect of the present description, the flow deflector conduit 4a comprises a curved deflection surface 4a' for deflecting a flow from one side 2c of the transverse chamber perpendicularly to the fixing side 2b, and vice versa. In one embodiment according to the first aspect of the present description, the duct 4a of the flow deflector 4 is open between an opening of the same towards the side 2c of the chamber and an opening of the same towards the joining side. ρζρβηη / ζζηζ / Β / γίΛΐ In one embodiment according to the first aspect of the present description, the flow deflector 4 comprises a plurality of ducts 4a separated laterally from each other by one or more intermediate walls 4b. This allows the flow through the plurality of conduits 4a to align with an associated collector channel 9a in a filter plate 6, thereby reducing flow turbulence and associated problems such as solids buildup or accumulation. The collector channels 9a in the filter plate 6 are appropriately provided with a plurality of distinct openings, rather than a single larger opening, to achieve the required structural strength. If the flow deflector 4 is provided with a plurality of ducts 4a and intermediate walls 4b, in relation to the first fixing bolts 3 that are provided on the side 2c of the filtration chamber with respect to the flow deflector 4 and aligned with it, the first fixing bolts 3 are most appropriately aligned with the intermediate walls 4b, so that they interfere with the flow as little as possible. In an embodiment according to the first aspect of the present description, the outlet cover 1 comprises one or more second fixing bolts 5 that protrude perpendicularly from the fixing side 2b of the base 2. These second fixing bolts 5 provide additional support for the outlet cap 1, and can also be used to fix a filter diaphragm 11 to the filter plate 6, as described in more detail below with regard to an embodiment of the third aspect of the present invention, while at the same time providing additional support for the outlet cap 1. Preferably, but not necessarily, said one or more second joining bolts 5 are hollow and have an interior that opens towards the joining side 2b and the outer side 2a, through the base 2. This allows any possible pressure buildup within the second joining hole 10b of the filter plate 6 to be equalized through the inner hollow of the second fixing bolt 5. Preferably, but not necessarily, said one or more second fixing bolts 5 are arranged on one or more lateral sides 2d with respect to the flow deflector 4, suitably aligned with it. Since the flow deflector 4 forms a relatively large portion not attached (to the filter plate) to the outlet cover 1, the one or more second fixing bolts 5 are therefore advantageous, as they provide greater support. Furthermore, if the outlet cap 1 is associated with a filter plate assembly equipped with a filter diaphragm 11, inherently equipped with a flow opening pzr«nn / zznz / B / YiAi to receive the flow deflector 4 through it, the arrangement of the second fixing bolts 5 accordingly provides greater support and secures the diaphragm 11 around the flow opening 13, thereby preventing the accumulation of solids between the diaphragm and the filter plate 6, and / or between the diaphragm 11 and the outlet cap 1. It should be noted that the present description covers any combination of the modalities, or variants thereof, of the first aspect, as described above. According to a second aspect of the present invention, a filter plate 6 is provided for a recessed-type filter, such as a filter press or a tower press. More specifically, the filter plate 6 is suitable for a recessed-plate-type filter equipped with a diaphragm for crushing a filter cake formed in a filter chamber. The filter plate 6 comprises a frame region 7 that surrounds and has an increased thickness with respect to the remaining portion of the filter plate 6, and at least on a first surface of the diaphragm filter plate, a confined web region that is recessed with respect to the frame region 7. The filter plate 6 further comprises an internal collector duct 9 with one or more collector channels 9a opening towards the core region to provide smooth communication between the collector duct 9 and the core region. The filter plate 6 further comprises one or more first fixing holes 10a to receive the one or more first fixing bolts 3 of the outlet cover 1, as discussed above in relation to the first aspect of this description. In particular, the first one or more fixing holes 10a have an inner diameter that increases towards the bottom of the hole 10a. These first fixing holes 10a can be implemented, for example, by providing the opening of the hole 10a with an overhang or, correspondingly, by providing the bottom of the hole 10a with a recess. In addition, the first fixing hole 10a could be provided with a sloped side wall. This ensures that an extendable portion 3b of a first fixing bolt 3 of an outlet cap 1 engages properly with the first fixing hole 10a. In other words, the first fixing bolt 3 cannot be pulled out of the first fixing hole 10a after the extendable portion 3b has extended radially, because the outer diameter of the extendable portion 3b has extended to exceed the inner diameter near the opening of the first fixing hole 10a. At the same time, the first fixing bolt 3 can be moved further into the first fixing hole 10a, for example, by pressing adjacent filter plate assemblies during a filtration cycle of an associated filter press. This increases the service life of the outlet cap 1 and prevents a safety element 15 inserted into the first fixing bolt 3 from stripping its threads. Preferably, but not necessarily, the first one or more fixing holes 10a are arranged on one side 2c of the filter chamber with respect to the one or more collector channels 9a, preferably laterally between two adjacent collector channels 9a. As discussed above, with regard to the first aspect of the present description, providing first fixing holes 10a (and associated first fixing bolts 3) on one side 2c of the filter chamber with respect to the collector channels 9a (and an associated flow baffle 4) improves the support of the outlet cover, and prevents the discharged filter cake from damaging or deforming the outlet cover 1. In addition, this prevents the accumulation of solids in relation to a flow opening 14 of a filter diaphragm 11, if such a diaphragm 11 is used. In one embodiment according to the second aspect of the present description, the filter plate 6 has a recessed area to receive a portion of the flow deflector 4, such that the flow deflector 4 sits against the recessed area. This simultaneously improves the seal between the flow baffle 4 of the outlet cover 1 and the support between the outlet cover 1 and the filter plate 6. In particular, the transverse and lateral loads exerted on the outlet cover 1 (such as a filter cake that is partially and temporarily carried by the outlet cover 1 during cake discharge) can be supported predominantly through the flow baffle 4, while the first one or more fixing bolts 3 secure the outlet cover to the filter plate 6, and any possible second fixing bolt 5 helps to prevent rotation of the outlet cover 1. In an embodiment according to the second aspect of the present description, the filter plate 6 comprises one or more second fixing holes 10b to receive the one or more second fixing bolts 5. This increases the support for the outlet cover 1 and, where a filter diaphragm 11 is provided, can be used to attach the diaphragm 11 to the filter plate 6 at the outlet cover 1. Preferably, but not necessarily, the one or more second fixing holes 10b are preferably arranged either on either or both lateral sides 2d with respect to the collector channels 9a. As discussed above, with regard to the second fixing bolts 5 of the outlet cap 1 according to the first aspect, this improves the support of the outlet cap 1 near the flow deflector 4, which constitutes a relatively large unsupported area and helps to prevent the accumulation of solids between the diaphragm 11 (provided) and the filter plate 6 and / or the outlet cap 1. Preferably, but not necessarily, the second fixing hole 10b also has an inner diameter that increases towards its lower portion. Again, this could be achieved by providing the opening of the second fixing hole 10b with an overhang, a recess at its lower portion, or a sloped side wall. This would allow second fixing rivets 14, formed in a diaphragm, to fit snugly beneath the opening of the second fixing hole 10b, thus preventing the second fixing rivets 14 from being pulled out of the second fixing hole 10b. In practice, the second fixing bolts 5 inserted into the second fixing rivets 14 prevent the second fixing rivets 14 from deforming to fit the shape through the opening of the second fixing hole 10b. It should be noted that the present description covers any combination of the modalities, or variants thereof, of the second aspect, as described above. According to a third aspect of this description, a filter plate assembly is provided for a recessed-type filter, such as a filter press or tower press. More specifically, the filter plate assembly is suitable for a recessed-plate filter equipped with a diaphragm for crushing a filter cake formed in a filter chamber. The filter plate assembly comprises an outlet cover 1 according to the first aspect of this description and a filter plate according to the second aspect of this description. The outlet cover 1 is attached to the filter plate 6, so that the first fixing bolt 3 is received at least partially inside the first hole 10a of the filter plate 6, so that at least the extendable part 3b is located inside the first fixing hole 10a. Furthermore, the flow deflector 4 sits against the filter plate 6, such that a conduit opening 4a of the flow deflector 4 into the filter plate 6 is aligned with a collector channel 9a of the filter plate 6, and a conduit opening 4a of the flow deflector 4 is raised into the filter chamber from the filter plate 6. The filter plate assembly further comprises a safety element 15 inserted into the hollow interior of the first fixing bolt 3, thereby deforming the extendable part 3b to occupy a diameter larger than that of an opening in the first fixing hole 10a, and securing the first fixing bolt 3 to the first fixing hole 10a. ρζρβηη / ζζηζ / Β / γίΛΐ This proper coupling between the first fixing bolt 3 and the first fixing hole 10a prevents the first fixing bolt 3 from coming out of the first fixing hole 10a. In one embodiment according to the third aspect of this description, the first fixing bolt 3 and the first fixing hole 10a are configured such that the longitudinal end of the first fixing bolt 3 does not reach the bottom of the first fixing hole 10a. This allows for limited clearance between the first fixing bolt 3 and the first fixing hole 10a, for example, when adjacent filter plate assemblies are pressed together during a filtration cycle of an associated filter press. This improves the service life of the outlet cover 1 and prevents a safety element 15 from stripping the threads in the first fixing hole 10a. In an embodiment according to the third aspect of the present description, the filter plate assembly further comprises a diaphragm 11 loosely attached to the filter plate 6, in order to extend over the web region of the plate 6. The purpose of the diaphragm 11 is to squeeze out the remaining liquid content from a filter cake formed within a filtration chamber. Diaphragm 11 comprises a leaf-shaped body with a flexible structure. That is, the body of diaphragm 11 can flex without permanent deformation. The diaphragm further comprises one or more first openings 12 extending through the body to receive one or more first fixing bolts 3 of the outlet cover 1 through it. The diaphragm also comprises a flow opening 13 extending through the body to receive the flow deflector 4 of the outlet cover 1 through it. The outlet cap 1 is attached to the filter plate via the diaphragm 11, such that the first fixing bolt 3 extends through the first opening 12 of the diaphragm 11 and is received inside the first hole 10a of the filter plate 6. Furthermore, the flow deflector 4 extends through the flow opening 13 of the filter diaphragm 11 and sits against the filter plate 6, such that a conduit opening 4a of the flow deflector 4 into the filter plate 6 is aligned with a collector channel 9a of the filter plate. The conduit opening 4a of the flow deflector 4 into the filter chamber rises from the diaphragm 11 in a direction away from the filter plate, allowing filtrate flow from the filter chamber to enter conduit 4a. If the filter plate assembly is provided with a diaphragm 11, the outlet cap 1 is preferably, but not necessarily, equipped with one or more second fixing bolts 5, as discussed above in relation to any modality or variant thereof, of the first aspect, including said second fixing bolts. Accordingly, the filter plate 6 is preferably, but not necessarily, equipped with one or more second fixing holes 10b, as discussed above in relation to any modality or variant thereof, of the second aspect, including said second fixing hole 10b. In such case, the one or more second fixing bolts 5 are received at least partially within the second fixing holes 10b. Furthermore, the diaphragm 11 preferably, but not necessarily, further comprises one or more second fixing rivets 14 for attaching the diaphragm 11 to the filter plate 6. These second fixing rivets 14 extend in a direction perpendicular to the diaphragm body towards the plate 6, and are equipped with an opening that extends through the filter diaphragm 11, between opposite sides thereof. The diaphragm's second fixing rivets 14 can then be received in one or more second fixing holes 10b of the filter plate 6. In addition, the outlet cap's one or more second fixing bolts 5 1 are inserted into the second fixing rivets 14 to elastically compress the second fixing rivet 14 against the second fixing hole 10b, thereby securing the diaphragm 11 to the filter plate 6. In one embodiment according to the third aspect of this description, the fastening element 15 is a screw, preferably a self-tapping screw, which can be screwed into the first fastening bolt 3, even without a pre-existing thread. Alternatively, the safety element 15 can be provided as an additional bolt or rivet inserted into the hollow interior of the first fastening bolt 3, although a screw is considered particularly advantageous as it allows for easy removal. In one embodiment according to the third aspect of the present description, the filter plate 6 has a recessed area to receive a portion of the flow deflector 4, wherein the flow deflector 4 sits against the recessed area. This simultaneously improves the seal between the flow baffle 4 of the outlet cover 1 and the support between the outlet cover 1 and the filter plate 6. In particular, the transverse and lateral loads exerted on the outlet cover 1 (such as a filter cake that is partially and temporarily carried by the outlet cover 1 during cake discharge) can be supported predominantly through the flow baffle 4, while the first one or more fixing bolts 3 secure the outlet cover to the filter plate 6, and any possible second fixing bolt 5 helps to prevent rotation of the outlet cover 1. ρζρβηη / ζζηζ / Β / γίΛΐ It should be noted that the present description covers any combination of the modalities, or variants thereof, of the third aspect, as described above. In accordance with a fourth aspect of the present description, a recessed plate-type filter, such as a filter press or a tower press, is provided. The filter comprises a plurality of diaphragm filter plate assemblies according to any of the embodiments, or variants thereof, of the third aspect, as discussed above. The diaphragm filter plate assemblies are configured to be movable relative to each other toward a closed position in which a filter chamber is formed between adjacent diaphragm filter plate assemblies, and to move away from each other to an open position in which adjacent diaphragm filter plate assemblies are separated from each other. The filter further comprises a filter medium arranged between adjacent diaphragm filter plate assemblies. The filter further comprises a displacement arrangement for moving the diaphragm filter plate assemblies towards each other to form a filter chamber between adjacent filter plates, and for moving them away from each other to open the filter chamber. The filter also includes a feeding arrangement for feeding suspension to the filter chamber. The filter also includes a recovery arrangement to recover the filtrate from the filter chamber. The filter also includes a discharge arrangement for discharging a filter cake formed inside the filter chamber. List of reference numbers for flat base outlet cover 2. Outer wing of the outlet cover 2b outlet cover fixing side 2c side of the outlet cover camera 2d side of the outlet cover first fixing bolt 3. Hollow housing of the first fixing bolt 3b radially extendable portion of the first fixing bolt 3b' cut that separates the radially extensible portion from the first fixing bolt 3 from the remaining housing 3a. ρζρβηη / ζζηζ / Β / γίΛΐ 4 flow deflector 4a flow deflector duct 4a' curved flow surface 4b flow deflector intermediate wall 5 5 second fixing bolt 6 filter plate 7 filter plate frame region 9 internal collector duct 9a internal collector duct channel 10 10a first fixing hole 10 second fixing hole 11 diaphragm 12 first diaphragm opening 13 diaphragm flow opening 15 14 second diaphragm fixing rivet 15 safety element

Claims

1. An outlet cover (1) for a recessed plate-type filter, such as a filter press or tower press, comprising: a flat base (2) having a generally flat side, defining an outer side (2a) of the outlet cover, and an opposite side, defining a joining side (2b) of the outlet cover, to be fixed against a diaphragm filter plate assembly, and one or more first fixing bolts (3) projecting perpendicularly a distance from the joining side (2b) of the base (2), wherein at least a radially extensible portion (3b) is provided in the first fixing bolt (3), to permit the extensible portion (3b) to deform radially away from the remaining housing (3a) by a radial force exerted on the extensible portion of the hollow interior of the first fixing bolt (3), and wherein the one or more first fixing bolts (3) are fixed, preferably integral, parts of the base (2),characterized in that the outlet cover (1) further comprises a flow deflector (4) projecting perpendicularly a distance from the fixing side (2b) of the base (2), the flow deflector (4) comprising at least one conduit (4a) for diverting a flow from one side (2c) of the transverse chamber perpendicularly towards the fixing side (2b), and vice versa, wherein the first fixing bolt (3) is separate from the flow deflector (4), and wherein the first fixing bolt (3) has a hollow housing (3a), the interior of which opens at least to the outside, through the base (2).

2. The outlet cover (1) according to claim 1, characterized in that the radially extendable part (3b) of the first fixing bolt (3) is provided in a distal part of the first fixing protrusion.

3. The outlet cover according to claim 1 or 2, characterized in that the interior of the hollow housing (3a) is further opened towards the fixing side (2b).

4. The outlet cover according to any of the preceding claims 1-3, characterized in that the extendable portion (3b) is formed partially separate from the remaining housing (3a) of the first fixing bolt (3), to allow the extendable portion (3b) to be deflected radially away from the remaining housing (3a) by a radial force exerted on the extendable portion from the hollow interior of the first fixing bolt (3).

5. The outlet cover (1) according to any of the preceding claims 1-4, characterized in that the radially extendable portion (3b) of the first fixing bolt (3) is at least partially separated from the remaining housing (3a) by at least one cutout ρζρβηη / ζζηζ / Β / γίΛΐ (3bj) extending radially along the housing (3a) and axially along the first fixing bolt (3).

6. The outlet cover (1) according to claim 5, characterized in that the at least one cutout (3bj) extends from a distal end of the first fixing bolt (3) towards the flat base (3).

7. The outlet cover (1) according to any of the preceding claims 1-6, characterized in that the first fixing bolt (3) has an inner diameter decreasing towards the distal end thereof.

8. The outlet cover (1) according to any of the preceding claims 1-7, characterized in that the base (2) of the outlet cover (1) extends from the flow deflector (4) a distance towards the side (2c) of the chamber.

9. The outlet cover (1) according to claim 8, characterized in that the first one or more fixing bolts (3) are arranged in alignment with the flow deflector (4), on the side (2c) of the chamber with respect to it.

10. The outlet cover (1) according to any of the preceding claims 1-9, characterized in that the flow deflector conduit (4a) comprises a curved deflection surface (4aj) for diverting a flow from one side (2c) of the transverse chamber perpendicularly towards the fixing side (2b), and vice versa.

11. The outlet cover (1) according to any of the preceding claims 1-10, characterized in that the conduit (4a) of the flow deflector (4) is open between an opening thereof towards the side (2c) of the chamber and an opening thereof towards the fixing side.

12. The outlet cover according to any of the preceding claims 1-11, characterized in that the flow deflector comprises a plurality of ducts (4a) separated laterally from each other by one or more intermediate walls (4b).

13. The outlet cover (1) according to any of the preceding claims 1-12 characterized in that the outlet cover (1) comprises one or more second fixing bolts (5) protruding perpendicularly from the fixing side (2b) of the base (2).

14. The outlet cover (1) according to claim 13, characterized in that the one or more second fixing bolts (5) are hollow and have an open interior both towards the fixing side (2b) and towards the outer side (2), through the base (2).

15. The outlet cover (1) according to claim 13 or 14, characterized in that the one or more second fixing bolts (5) are arranged on one or more lateral sides (2d) with respect to the flow deflector (4).

16. A filter plate (6) for a recessed-type filter, such as a filter press or a tower press, comprising: - a frame region (7) surrounding and having an increased thickness relative to the remaining portion of the filter plate (6); - at least on a first surface of the diaphragm filter plate, a web region confined and recessed relative to the frame region (7); - an internal collector duct (9) with one or more collector channels (9a) opening into the web region to provide fluid communication between the collector duct (9) and the web region; and - one or more first fixing holes (10a) for receiving the one or more first fixing bolts (3) of the outlet cover (1), characterized in that the one or more first fixing holes (10a) have an inner diameter that increases towards the bottom of the hole (10a).

17. The filter plate according to claim 16, characterized in that the first one or more fixing holes (10a) are arranged on one side (2c) of the filtration chamber with respect to the one or more collection channels (9a), preferably laterally between two adjacent collection channels (9a).

18. The filter plate according to any of the preceding claims 16 or 17, characterized in that the filter plate (6) has a recessed area to receive a portion of the flow deflector (4) such that the flow deflector (4) sits against the recessed area.

19. The filter plate according to claim 16-18, characterized in that the filter plate (6) comprises one or more second fixing holes (10b) for receiving one or more second fixing bolts (5), wherein the one or more second fixing holes (10b) are preferably arranged on one or both lateral sides (2d) with respect to the collecting channels (9a).

20. A filter plate assembly for a built-in filter, such as a filter press or a tower press, characterized in that it comprises an outlet cover (1) according to any of claims 1-15, and a filter plate (6) according to any of claims 16-19, wherein the outlet cover (1) is attached to the filter plate (6), such that - the first fixing bolt (3) is received at least partially within the first hole (10a) of the filter plate (6), such that at least the extendable portion (3b) is located within the first fixing hole (10a), and - the flow deflector (4) seats against the filter plate (6), such that an opening (4a) of the flow deflector (4) conduit to the filter plate (6) is aligned with a collector channel (9a) of the filter plate (6),and an opening (4a) of the flow deflector conduit (4) to the filter chamber is raised from the filter plate (6), and wherein the filter plate assembly further comprises a safety element (15) inserted into the hollow interior of the first fixing bolt (3), thereby deforming the extendable portion (3b) to occupy a diameter greater than that of an opening of the first fixing hole (10a), and securing the first fixing bolt (3) to the first fixing hole (10a).

21. The filter plate assembly according to claim 20, characterized in that the first fixing bolt (3) and the first fixing hole (10a) are configured such that the longitudinal end of the first fixing bolt (3) does not reach the bottom of the first fixing hole (10a).

22. The filter plate assembly according to claim 20 or 21, characterized in that the filter plate assembly further comprises a diaphragm (11) loosely attached to the filter plate (6) to extend over the core region of the plate (6), the diaphragm, in turn, comprising: - a sheet-like body having a flexible structure; - one or more first openings (12) extending through the body to receive the first one or more fixing bolts (3) of the outlet cover (1) through them, and - a flow opening (13) extending through the body to receive the flow deflector (4) of the outlet cover (1) through it, wherein the outlet cover (1) is attached to the filter plate through the diaphragm (11), such that: - the first fixing bolt (3) extends through the first opening (12) of the diaphragm (11) and is received within the first hole (10a) of the filter plate (6),and - the flow deflector (4) extends through the flow opening (13) of the filter diaphragm (11) and seats against the filter plate (6), such that an opening (4a) of the flow deflector (4) conduit to the filter plate (6) is aligned with a collector channel (9a) of the filter plate (6), and an opening (4a) of the flow deflector (4) conduit to the filter chamber is raised from the diaphragm (11) in a direction away from the filter plate.

23. The filter plate assembly according to any of the preceding claims 20-22, characterized by the outlet cover (1) according to any of the preceding claims 13-15, and the filter plate (6) according to claim 19, wherein the one or more second fixing bolts (5) are received at least partially within the second fixing holes (10b).

24. The filter plate assembly according to claim 23 in combination with claim 22, characterized in that the diaphragm (11) further comprises one or more second fixing rivets (14) for joining the diaphragm (11) to the filter plate (6), the second fixing rivets (14) extending in a direction perpendicular to the diaphragm body towards the plate (6), and being provided with an opening extending through the filter diaphragm (11) between opposite sides thereof, wherein the one or more second fixing rivets (14) of the diaphragm are received in the one or more second fixing holes (10b) of the filter plate (6), and wherein the one or more second fixing bolts (5) of the outlet cover (1) are inserted into the second fixing rivets (14) to elastically compress the second fixing rivet (14) against the second fixing hole (10b), thereby securing the diaphragm (11) to the plate (6). of the filter.

25. The filter plate assembly according to any of the preceding claims 20-24, characterized in that the fastening element (15) is a screw.

26. The filter plate assembly according to any of the preceding claims 20-25, characterized in that the filter plate (6) has a recessed area to receive a portion of the flow deflector (4) wherein the flow deflector (4) is seated against the recessed area.

27. A recessed plate-type filter, such as a filter press or a tower press, characterized in that the filter comprises: a plurality of diaphragm filter plate assemblies according to any of claims 20-26, wherein the diaphragm filter plate assemblies are configured to be movable toward each other to a closed position in which a filter chamber is formed between adjacent diaphragm filter plate assemblies, and to move away from each other to an open position in which the adjacent diaphragm filter plate assemblies are separated from each other; a filter medium disposed between adjacent diaphragm filter plate assemblies; a displacement arrangement for moving the diaphragm filter plate assemblies toward each other to form a filter chamber between adjacent filter plates, and for moving them away from each other to open the filter chamber;a feeding arrangement for feeding suspension into the filter chamber; a recovery arrangement for recovering filtrate from the filter chamber; and a discharge arrangement for discharging a filter cake formed within the filtration chamber.

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