GB2067909A - Filter press plates - Google Patents

Abstract

The cloth-supporting surface of a filter press plate or other filter comprises a regular pattern of upstanding cylinders or truncated cones or prisms defining filtrate-drainage channels 3 between them. The flat tops of the cylinders, cones or prisms have grooves 2 therein to assist drainage. Grooves 2 may extend in one direction or may be arranged in two orthogonal directions. <IMAGE>

Description

SPECIFICATION Filter support of plates for filter presses and filters The invention relates to a filter support of plates of filter presses and filters for filtering over a filter wall, for instance over a filter cloth or filter paper, which filter support is advantageously made of plastics. The draining arrangement of the filter support comprises regularly oriented projections of geometric shapes.

At present filter supports of plates of filter presses and filters with different types of draining arrangements are used. The draining arrangement is generally a system of projections supporting the filter wall and a system of channels serving for removal of filtrates between these projections. A commonly used draining arrangement is vertical grooves at both sides of a filter press plate, with which grooves, particularly wooden filter press plates and plates made of polypropylene, are provided. Some filter press plates made of plastics are also provided with inclined grooves, with cylindrical projections and projections of the shape of truncated pyramids. Another draining arrangement uses truncated pyramids with channels for removal of filtrates with two different depths.

All these draining arrangements have the common drawback that the surface of projections on which the filter wall is bearing is smooth, flat or slightly convex, and the filter wall bears on this surface rather tightly due to the filter pressure. At places where the filter wall is in contact with the projections of the draining arrangement, the speed of filtration is reduced, and this reduction is larger for thin filter walls and large surface projections.

Recently thinner and thinner and hard rather dense filter walls are used, made of synthetic fibres. These walls are smoothened by calendering from one or both sides in order to produce antiadhesive properties in filter cakes. This kind of filter walls requires a particularly effective draining arrangement.

This invention can provide a filter support of plates for filter presses and filters for filtering over a filter cloth or filter paper, which can pass the filtrates more uniformly over the whole filtering surface. The filter support according to this invention has regularly oriented projections of any suitable geometric shape or shapes, for instance cylinders, prisms, truncated pyramids or cones, the upper surfaces of which are flat or slightly convex.

The upper surfaces of this draining arrangement, which are in contact with the filter wall, are provided with grooves.

The filter support according to this invention with grooved upper surfaces of projections of the draining arrangement enables good removal of the filtrate, even from places where the projections are in contact with the filter wall. The grooves can be made in one direction or in two directions, preferably at an acute or right angle. It is possible to have the grooves made in different directions from the directions of the warp and weft of the filter cloth. Thus the individual fibres of the filter cloth obtain a better support.

The invention will be further described, by way of example, with reference to the accompanying drawing in which: Figure 1 is a top view of a draining arrangement, the upper surface of which is provided with grooves in one direction, with the outline of the cross-section thereof below; and Figure 2 is a top view of a draining arrangement, the upper surface of which is provided with grooves in two directions, with the outline of the cross-section thereof below.

The filter support of plates for filter presses and filters according to Figure 1 has regularly oriented projections 1 of the shape of truncated pyramids, with channels 3 between these projections 1. The upper surface of the projections 1 of this draining arrangement of the filter support is provided with grooves 2 in one direction. The grooves 2 are at an angle of 450. These projections 1 of the shape of a truncated pyramid have side dimensions about 8 x 8 mm, a height of about 4 mm, the grooves 2 are about 0.5 mm wide and about 0.5 mm deep.

The channels 3 have a depth of about 4 mm and width of about 6 mm.

The filter support of plates for filter presses and filters according to Figure 2 has also regularly oriented projections 1, with channels 3 between these projections 1. The upper surface of the draining arrangement of the filter support, which is in contact with the filter wall has grooves 2 in two directions. The grooves 2 are made at angles of 450 and 1350. The dimensions of grooves 2, of channels 3 and projections 1 of the draining arrangement are the same as in Figure 1.

1. A filter support of plates suitable for filter presses and filters for filtering over a filter wall, having regularly oriented geometrically shaped projections, the upper surfaces of said projections which are in contact with the filter wall, being provided with grooves.

2. A filter support substantially as herein described with reference to the accompanying drawing.

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

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Filter support of plates for filter presses and filters The invention relates to a filter support of plates of filter presses and filters for filtering over a filter wall, for instance over a filter cloth or filter paper, which filter support is advantageously made of plastics. The draining arrangement of the filter support comprises regularly oriented projections of geometric shapes. At present filter supports of plates of filter presses and filters with different types of draining arrangements are used. The draining arrangement is generally a system of projections supporting the filter wall and a system of channels serving for removal of filtrates between these projections. A commonly used draining arrangement is vertical grooves at both sides of a filter press plate, with which grooves, particularly wooden filter press plates and plates made of polypropylene, are provided. Some filter press plates made of plastics are also provided with inclined grooves, with cylindrical projections and projections of the shape of truncated pyramids. Another draining arrangement uses truncated pyramids with channels for removal of filtrates with two different depths. All these draining arrangements have the common drawback that the surface of projections on which the filter wall is bearing is smooth, flat or slightly convex, and the filter wall bears on this surface rather tightly due to the filter pressure. At places where the filter wall is in contact with the projections of the draining arrangement, the speed of filtration is reduced, and this reduction is larger for thin filter walls and large surface projections. Recently thinner and thinner and hard rather dense filter walls are used, made of synthetic fibres. These walls are smoothened by calendering from one or both sides in order to produce antiadhesive properties in filter cakes. This kind of filter walls requires a particularly effective draining arrangement. This invention can provide a filter support of plates for filter presses and filters for filtering over a filter cloth or filter paper, which can pass the filtrates more uniformly over the whole filtering surface. The filter support according to this invention has regularly oriented projections of any suitable geometric shape or shapes, for instance cylinders, prisms, truncated pyramids or cones, the upper surfaces of which are flat or slightly convex. The upper surfaces of this draining arrangement, which are in contact with the filter wall, are provided with grooves. The filter support according to this invention with grooved upper surfaces of projections of the draining arrangement enables good removal of the filtrate, even from places where the projections are in contact with the filter wall. The grooves can be made in one direction or in two directions, preferably at an acute or right angle. It is possible to have the grooves made in different directions from the directions of the warp and weft of the filter cloth. Thus the individual fibres of the filter cloth obtain a better support. The invention will be further described, by way of example, with reference to the accompanying drawing in which: Figure 1 is a top view of a draining arrangement, the upper surface of which is provided with grooves in one direction, with the outline of the cross-section thereof below; and Figure 2 is a top view of a draining arrangement, the upper surface of which is provided with grooves in two directions, with the outline of the cross-section thereof below. The filter support of plates for filter presses and filters according to Figure 1 has regularly oriented projections 1 of the shape of truncated pyramids, with channels 3 between these projections 1. The upper surface of the projections 1 of this draining arrangement of the filter support is provided with grooves 2 in one direction. The grooves 2 are at an angle of 450. These projections 1 of the shape of a truncated pyramid have side dimensions about 8 x 8 mm, a height of about 4 mm, the grooves 2 are about 0.5 mm wide and about 0.5 mm deep. The channels 3 have a depth of about 4 mm and width of about 6 mm. The filter support of plates for filter presses and filters according to Figure 2 has also regularly oriented projections 1, with channels 3 between these projections 1. The upper surface of the draining arrangement of the filter support, which is in contact with the filter wall has grooves 2 in two directions. The grooves 2 are made at angles of 450 and 1350. The dimensions of grooves 2, of channels 3 and projections 1 of the draining arrangement are the same as in Figure 1. CLAIMS

1. A filter support of plates suitable for filter presses and filters for filtering over a filter wall, having regularly oriented geometrically shaped projections, the upper surfaces of said projections which are in contact with the filter wall, being provided with grooves.

2. A filter support substantially as herein described with reference to the accompanying drawing.