WO2016156958A1 - A fixing system of a filter cloth to a plate for a filter press - Google Patents

Abstract

A fixing system is described of a filter cloth (130) to a plate for a filter press (100), comprising at least a cable (155) and one or more hooks (145) able to hook the cable (155) to connect the filter cloth to the plate.

Description

A FIXING SYSTEM OF A FILTER CLOTH TO A PLATE FOR A FILTER PRESS

Technical field

The present invention relates in general to filter presses, and more in particular to system enabling fixing of filter cloths to plates in the above-mentioned filter presses.

Background

As is known, filter presses are normally composed of a series of plates which are locked in a pack on against the others by means of appropriate mechanical and/or hydraulic means.

The plates are profiled so that an internal chamber is defined between two consecutive plates.

A filter wall made of cloth, paper or a synthetic material having larger or smaller meshes is interposed between each pair of plates, which filter wall subdivides the internal chamber into two separate cavities.

The material to be filtered is pumped internally of a first of the cavities, so that the liquid phase crosses the filter wall and passes into the second cavity from which it is discharged, while the solid phase accumulates and compacts in the first cavity.

Normally the filter walls are obtained by means of cloths having a shape and design such as to clad the plate functionally, so that a first flap of the cloth dads a first face of the plate while a second flap of the cloth covers the opposite face.

To fix the filter cloth to the plate, the free opposite ends of the cloth are brought to contact an edge of the plate and are connected to one another by means of an appropriate fixing system.

In a very common fixing system the free ends of the cloth are connected to one another by means of a plurality of locking straps which insert in corresponding eyelets made in the cloth.

A drawback of this system consists in the fact that the replacement of each filter cloth generally requires a good deal of time to be completed, which considerably increases the use of manpower and the down-times of the filter press.

To reduce the dimension of the intervention, a fixing system using Velcro has been proposed, which is made up of a layer of hooks and a loop layer, being respectively fixed to the two free ends of the filter cloth so as to join them to one another.

This Velcro system enables a rapid replacement of the filter cloths but is expensive with respect to the strap system and does not enable obtaining a reliable coupling over time, especially due to the fact that the hook layers and loop layers can become fouled.

Summary of the invention

In the light of the foregoing, an aim of the invention is to provide a fixing system which enables a rapid replacement of the filter cloths without damaging the hold of the coupling and which is not subject to significant problems of wear over time.

A further aim of the invention is to attain the above-mentioned objective with a solution that is simple, rational and as economical as possible.

These and other aims besides are attained with the characteristics of the invention as recited in the independent claims. The dependent claims delineate preferred and/or particularly advantageous aspects of the invention.

In particular, an embodiment of the present invention provides a fixing system of a filter cloth to a plate for a filter press, which comprises at least a cable and one or more hooks able to hook the cable to connect the filter cloth to the plate.

This fixing system has the advantage of being substantially insensitive to dirt and enabling a very rapid hooking/demounting of the filter cloth to/from the filter plate, advantageously reducing the times and costs connected to replacement interventions.

In a preferred aspect of the invention, the cable of the fixing system can be an elastic cable.

In this way, the cable is able to deform to adapt to small shape and dimension variations of the filter cloths, which therefore do not require an absolute constructional precision but can be made with relatively broad margins of tol- erance.

In a further aspect of the invention, the cable can be fixed to the plate and the hooks can be fixed to the filter cloth.

In this way a single cable can advantageously be used for more than one life cycle of the filter cloths without having to demount the cable.

This solution further enables a more secure replacement of the filter cloths, as the cable remains fixed to the plate and cannot uncontrolledly whiplash towards the operators.

In a preferred embodiment, the cable can extend along a lateral edge of the plate and the hooks are arranged distanced from one another along an edge of the filter cloth.

This solution has the effect of distributing the connecting tensions along the edge of the filter cloth, so as to have a greater linearity of the coupling and a reduction in the risk of breakage.

In a further aspect of the invention the cable can be pre-tensioned and fixed to the plate at ends thereof.

This solution has the effect of automatically stretching the filter cloth, obtaining a very stable and secure fastening.

In an aspect of the invention, the cable can be removably fixed to the plate. In this way the cable can be replaced independently of the plate to which it is fixed.

In another aspect of the invention the hooks can be fixed to the filter cloth by means of rivets or by ultrasound welding or by gluing.

In this way the realising of the filter cloths is quite rapid and economical.

A further embodiment of the present invention relates to a filter press comprising a plate, a filter cloth and the fixing system of the cloth to the plate as delineated above.

This embodiment substantially produces the same effects as mentioned in the foregoing, in particular the effect of enabling a very rapid, economical and safe replacement of the filter cloth.

A further embodiment of the present invention relates to a filter cloth for a filter press to which one or more hooks are fixed, which hooks can be connect- ed to a plate for a filter press.

This embodiment of the invention has the effect of providing a cloth for a filter press already predisposed to be used with the fixing system delineated in the foregoing.

A further embodiment of the present invention relates to a filter cloth for a plate for a filter press to which one or more cables is fixed, which cables can be connected to a filter cloth for a filter press.

This embodiment of the invention has the effect of providing a plate for a filter press already predisposed to be used with the fixing system delineated in the above.

Brief description of the drawings

Further characteristics and advantages of the invention will emerge from a reading of the following description, provided by way of non-limiting example with the aid of the figures illustrated in the appended tables of drawings.

Figure 1 is a lateral schematic view of a filter press in an open configuration. Figure 2 is the view of figure 1 with the filter press in a closed configuration. Figures from 3 to 5 are three views in perpendicular projection of an example of a hook applied to the filter cloth for a filter press.

Figure 6 is an axonometric view of the hook of figures 3-5.

Figure 7 illustrates a plan development of an example of a filter cloth of the filter press.

Figure 8 is a portion of an axonometric view of a plate of the filter press illustrated without the filter cloth.

Figure 9 is the view of figure 8.with the plate of the filter press clad with the filter cloth.

Detailed description

With reference to figures 1 and 2, reference numeral 100 schematically denotes a filter press, which comprises a series of plates 105 which are arranged parallel to one another in the space comprised between a fixed base 1 10 and a mobile base 1 15.

Suitable actuating means 120 of a mechanical and/or hydraulic type are able to move the mobile base 1 15 nearingly to the fixed base 1 10, so as to push the plates 105 in a pack against the fixed base 1 10, blocking them with the force necessary to oppose filtration pressures.

Though not visible in figures, the plates 105 are profiled so that a narrow internal chamber is defined between each pair of consecutive plates.

A filter wall 125 is interposed between each pair of plates 105, which subdivides each internal chamber into two separate cavities, of which a first cavity communicating with an inlet for the material to be filtered and a second cavity communicating with an outlet for the liquid phase which is separated from the material to be filtered during the filtration.

When the plates 105 are closed in a pack with the correct blocking force, the material to be filtered is pumped internally of the first cavity.

The pressure generated by the pumping is such that the liquid phase contained in the material to be filtered crosses through the filter wall 125 and reaches the second cavity and the outlet, while the solid phase accumulates in the first cavity.

When the pumping pressure grows beyond a predetermined threshold value and/or the supply flow falls below a predetermined threshold value, this means that the solid phase has compacted in the first cavity forming a rather compact cake having a low liquid content.

At this point the filter press 100 is re-opened so as to discharge the solid cake and possibly also to clean or replace the filter walls 125 before repeating a new filtering operation.

In the illustrated example, each filter wall 125 is a portion of a larger filter cloth 130, which can be made from a textile or a mesh of material based on cellulose, or a synthetic material having larger or smaller meshes according to the type of filtration to be carried out.

Each filter cloth 130 can have a substantially rectangular shape and be folded centrally along a halfway strip 135 thereof so as to have to parallel and opposite flaps.

Folded in this way the filter cloth 130 is rested saddle-fashion on a plate 105, so that the halfway strip 135 rests on the upper edge of the plate 105, while each of the two flaps covers one of the two opposite flat faces of the plate 105.

In this way, the plate 105 envelops the filter cloth 130 the flaps of which define two filter walls 125 which are interposed between the plate 105 and the two plates 105 adjacent thereto.

Note that the shape of the cloth illustrated in figure 7 is a mere example and that in other embodiments the filter cloth 130 might have a different shape. To fix the filter cloth 130 of the plate 105, the two free and opposite edges 140 of the filter cloth, i.e. the edges which are positioned on opposite sides with respect to the halfway line 135, are individually provided with a series of hooks 145 (see figure 7).

Each hook 145 can generally comprise a base plane 150 from which a salient portion 152 branches, substantially conformed as an open eyelet.

The flat base 150 can be fixed to the filter cloth 130, for example by riveting, by ultrasound welding or by gluing, so that the salient portion 151 is exposed at the free edge 140 thereof.

The hooks 145 are arranged along each free edge 140 separated from one another and preferably equidistant so as to have as uniform a distribution as possible.

The hooks 145 arranged along the free edges 140 are preferably at least partly offset with respect to the hooks 145 arranged on the opposite free edge 140.

Note that the shape of the hooks illustrated in figures from 3 to 6 is a mere example and that in other embodiments the hooks 145 might have different shapes.

When the filter cloth 130 is wound about the plate 105 as described in the foregoing, both the free edges 140 project at least slightly below the lower edge of the plate 105, so that the hooks 145 can be hooked to the plate 105 without interfering with the closure of the filter press 100.

For this purpose, the plate 105 is equipped with a cable 155 which develops parallel and along the lower edge thereof, substantially over the whole length thereof (see figure 8).

In particular, the cable 155 is fixed to the lower edge of the plate 105 only at the ends thereof, preferably by fixing means which can enable replacement thereof, while it is free over a whole length thereof.

For example, each end of the cable 155 can be enveloped on itself to form a cowl and be hooked to a self-tapping screw 160 which is screwed into a hole previously made at an end of the lower edge of the plate 105.

The cable 155 is preferably an elastic cable which is pre-tensioned before the ends thereof are fixed to the plate 105.

In this way, the cable 155 is stretched between the two fixed ends but is also at least partially deformable in a lateral direction.

Consequently, when the filter cloth 130 is wound about the plate 105, the free edges 140 can be folded on the lower edge and the cable 155 can be deformed and hooked to the hooks 145, for example as illustrated in figure 9, solidly fixing the filter cloth 130 to the plate 105 in a very simple and rapid way.

Likewise, in order to replace the filter cloth 130 it is sufficient to unhook the hooks 145 from the cable 55, which remains associated to the plate 105 so that it can also be used with the replacement cloth.

Though in the preceding description the fixing system 145 using hooks and cable 155' has been illustrated as fixing the free edges of the filter cloth 130 to the lower edge of the plate 105, it is possible for the same system can be used also to fix one or both the lateral edges of the filter cloth 130 to the lateral edges of the plate 105.

It is also possible for each filter wall 125 to be realised as a single flat cloth which is hooked to one or more edges of the plate by means of the hook 145 and cable 155 system illustrated in the foregoing. For example, the two single cloths (also known as half-cloths) which clad the two faces of the same plate 105 can be hooked to a same cable 155 fixed on an edge of the plate 105. In general the filter wall 125 can in any case be obtained using any type of filter cloth 130 having a shape and design that are such as to clad the plate 105 in a functional way.

Obviously a technician in the sector might make numerous modifications of a technical-applicational nature to what has been described in the foregoing without forsaking the scope of the invention as claimed in the following.

Claims

1. A fixing system of a filter cloth (130) to a plate for a filter press (100), characterised in that it comprises at least a cable (155) and one or more hooks (145) able to hook the cable (155) to connect the filter cloth to the plate.

2. The fixing system according to claim 1 , characterised in that the cable (155) is elastic.

3. The fixing system according to claim 1 or 2, characterised in that the cable (155) is fixed to the plate (105) and the hooks (145) are fixed to the filter cloth (130).

4. The fixing system according to claim 3, characterised in that the cable (155) extends along a lateral edge of the plate (105) and the hooks (145) are arranged distanced from one another along an edge of the filter cloth (130).

5. The fixing system according to claim 3 or 4, characterised in that the cable (155) is pre-tensioned and fixed to the plate (105) at ends of the cable.

6. The fixing system according to any one of claims from 3 to 5, characterised in that the cable (155) is removably fixed to the plate.

7. The fixing system according to any one of claims from 3 to 6, characterised in that the hooks (145) are fixed to the cloth by means of rivets, by ultrasound welding or by gluing.

8. A filter press (100) comprising a plate (105), a filter cloth (130) and a fixing system of the cloth to the plate according to any one of the preceding claims.