FILTRES-PRESSES

FILTER PRESSES

Abrégé anglais

ABSTRACT
A filter press for the removal of
the liquid component from a suspension comprising
two endless filter belts which in one section of
the press are brought together so as to entrain
the suspension therebetween and which are then
guided around a plurality of rollers, character-
ised in that at least one of said rollers is
comprised by a plurality of axially extending
circumferentially spaced bars extending between
the opposite ends of the roller.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows :
1. A filter press for the removal of the
liquid component from a suspension comprising two
endless filter belts which in one section of the press
are brought together so as to entrain the suspension
therebetween and which are then guided around a plurality
of rollers to follow a generally serpentine path,
characterised in that at least one of said rollers is
a squirrel-cage type roller comprised by a plurality
of axially extending circumferentially spaced bars
extending between and secured against rotation with
respect to the opposite ends of the roller.
2. A filter press according to claim 1 further
characterised in that at least one of the remaining
rollers is of hollow construction being formed by a
cylindrical shell having perforations therethrough which
are counter-sunk at their radially outer ends.
3. A filter press according to claim 1 wherein
said endless filter belts lap at least some of said
rollers by at least 180°.
4. A filter press according to claim 2 wherein
said endless filter belts lap at least some of said
rollers by at least 180°.

5. A filter press according to claim 1
wherein one of said filter belts travels
horizontally over a perforated deck to receive
the suspension before passing over a roller where
the suspension becomes entrained between the two
belts, characterised in that means is provided
for vibrating said perforate deck.
6. A filter press according to claim 2
wherein one of said filter belts travels
horizontally over a perforated deck to receive
the suspension before passing over a roller where
the suspension becomes entrained between the two
belts, characterised in that means is provided
for vibrating said perforate deck.
7. A filter press according to claim 3
wherein one of said filter belts travels
horizontally over a perforated deck to receive
the suspension before passing over a roller where
the suspension becomes entrained between the two
belts, characterised in that means is provided
for vibrating said perforate deck.
8. A filter press according to claim 4
wherein one of said filter belts travels
horizontally over a perforated deck to receive
the suspension before passing over a roller where
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the suspension becomes entrained between the two
belts, characterised in that means is provided
for vibrating said perforate deck.
9. A filter press according to claim 5
characterised by the provision of means to turn
the suspension whilst it is conveyed on the
section of the belt overlying said perforate deck.
10. A filter press according to claim 6
characterised by the provision of means to turn
the suspension whilst it is conveyed on the
section of the belt overlying said perforate deck.
11. A filter press according to claim 7
characterised by the provision of means to turn
the suspension whilst it is conveyed on the
section of the belt overlying said perforate deck.
12. A filter press according to claim 8
characterised by the provision of means to turn
the suspension whilst it is conveyed on the
section of the belt overlying said perforate deck.
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13. A filter press according to Claim 1, 2 or 3
wherein one of the first rollers around which the endless
filter belts extend when travelling along said serpentine
path is of the squirrel-cage type.
14. A filter press according to Claim 4, 5 or 6
wherein one of the first rollers around which the endless
filter belts extend when travelling along said serpentine
path is of the squirrel-cage type.
15. A filter press according to Claim 7, 8 or 9
wherein one of the first rollers around which the endless
filter belts extend when travelling along said serpentine
path is of the squirrel-cage type.
16. A filter press according to Claim 10, 11 or 12
wherein one of the first rollers around which the endless
filter belts extend when travelling along said serpentine
path is of the squirrel-cage type.
11

Description

1060Z6Z
THIS INVE~ION concerns filter presses
for the removal of the liquid component from
suspensions such as sludges or slurries of various
kinds particularly, though by no means exclusively,
from sludges obtained in the treatment of sewage.
According to the present invention, a
filter press for the removal of the liquid component
from a suspension comprises two endless filter belts
which in one section of the press are brought
together so as to entrain the suspension there-
between and which are then guided around a plurality
of rollers, characterised in that at least one of
said rollers is comprised by a plurality of axially
extending circumferentially spaced bars extending
between the opposite ends of the rolIer.
The invention will be further apparent
from the following description with reference to
the several figures of the accompanying drawings
which show, by way of example only, in diagrammatic
form, one filter press embodying the invention.
Of the drawings;-
Fig. 1 shows a side elevation of the
press;
. '~
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1060Z6Z
Fig. 2 shows a ragmentary cross-section
through the periphery of the perforated
rollers of the press of Fig. l;
Fig. 3 shows a side elevation of one of
the rollers of the press of Fig. l;
and Fig. 4 shows a cross-section through the
roller of Fig. 3 on the line IV-IV
thereof.
Referring now to the drawings, it will be
seen that the filter press is essentially comprised
by upper and lower endless filter belts 10 and 11
respectively each formed from a woven synthetic
filament.
In one section of the press the belts pass
in superimposed relationship over a plurality of
guide rollers 12 to 18 inclusive. The lower belt
10 is guided towards the roller 12 by a guide
roller 19 and away from the roller 18 by guide
rollers 20 and 21 for return to the guide roller 19.
The upper belt 11 is guided towards the
roller 12 by a guide roller 22 and away from the
roller 18 by guide rollers 23 and 24 for return to
the guide roller 22.
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1060Z6Z
The filter belt 10 extends horizontally
for a substantial distance (of the order of two
metres) between the guide roller 19 and the roller
12. The belt 10 is supported between the rollers
19 and 12 on a perforated plate or grid 25 to be
referred to in greater detail hereinafter.
The rollers 12, 14, 16 and 18 are
arranged with their axes lying in a horizontal
plane whilst the rollers 13, 15 and 17 are arranged
with their axes lying in a further horizontal
plane beneath the plane containing the axes of .
the rollers 12, 14. 16 and 18.
The rollers 13, 15 and 17 are disposed
between the rollers 12 and 14, 14 and 16 and 16
and 18 respectively and the spacings between the
rollers 12 and 14, 14 and 16 and 16 and 18 are
not greater than the diameters of the rollers 13,
15 and 17 respectively, whereby the belts 10 and
11 lap each of the rollers 13 to 17 inclusive by
at least 180.
The rollers 20 and 22 are mounted on
pivoted arms 40 carrying weights 41 which urge
them outwardly in the direction of the arrows X,
thus to tension the belts 10 and 11 respectively.
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1060Z6Z
Motor means (not shown) is provided for
driving some or all of the rollers which guide the
belts 10 and 11 whereby the belts are driven in
the direction of the arrows shown.
In use, a suspension such as a sewage
sludge, for example, is deposited onto the upper
surface of the belt 10 adjacent the guide roller
19 by means of a chute or similar distributing
devi'ce indicated at 26. As the suspension is
conveyed towards the roller 12 liquid can drain
therefrom throughthe belt 10 and perforated grid
or plate 25. The removal of liquid in this
section of the press can be enhanced by subjecting
the perforated grid or plate 25 to vibrations by
means of a vibrator device indicated at 27.
The partially de-liquified sludge is
entrained between the belts 10 and 11 where they t
converge at the periphery of the roller 12.
Liquid is expressed from the sludge as it passes
around each of the rollers 12 to 18 inclusive
due to the fact that it is compressed between the
belts. The removal of liquid is enhanced by the
shearing action to which the sludge is subjected as
it passes around each of the rollers due to the
differential in the speed of travel of the two belts
at these parts.
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1060;~6Z
To facilitate the removal of liquid the
rollers 12, 13, 14, 16 and 18 have apertures in
their peripheral surfaces. Thus, the rollers
12, 14, 16 and 18 are of hollow construction, the
cylindrical shells which form them being provided
with a multiplicity of perforations 28 (see Fig.
2) which are countersunk at 29~
The roller 13 is constructed in the form
of a squirrel-cage and is comprised by a plurality
of rods 30 extending axially in circumferentially
spaced relationship between discs 31 and 32 and the
two ends of the roller, all as clearly shown in
Figs. 3 and 4. This construction permits easy
egress of liquid from the sludge through both of
the belts lO and ll. This is particularly import~
ant in the early stages of the pressing operation
when the sludge contains a high proportion of
liquid.
The rollers 15 and 17 are not perforated,
since by the time the sludge reaches these rollers
it is relatively dry and there would be insufficient
water to rise and fill the perforations in the
roller and thus reach the interior of the rollers
for flow therefrom. It will be understood, however,
that liquid expressed at the rolle~s 16 and 18 can
drain downwardly through the perforations therein
and thus be removed from the sludge permanently.
/1421 - 6 -
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1060Z6Z
The belts 10 and 11 are separated on the
periphery of the roller 18 and the de-liquified
sludge is collected by scrapers 33 and 34 for
removal by a conveyor belt 35.
The belts 10 and 11 are passed through
washing devices 36 and 37 respectively on their
return to the roller 12 so that any material
trapped within their interstices is removed, thus
preventing the belts from becoming permanently
blinded.
Trays (not shown in the interests of
clarity) are proVided for collecting liquid which
drains through the plate or grid 25 and which
drains from each of the rollers 12 to 18 inclusive.
It will be appreciated that it is not
intended to limit the invention to the above
example only, many variations, such as might
readily occur to one skilled in the art, being
possible without departing from the scope thereof~
as defined by the appended claims.
Thus, for example, ploughs or similar
devices may be provided to turn the material as
it is conveyed therepast on the section of the belt
10 overlying the plate or grid 25.
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