DISPOSITIF POUR SEPARER UN LIQUIDE D'UN FLUIDE CHARGE DE BOUES

DEVICE FOR THE SEPARATION OF LIQUID FROM A SLURRYLADEN FLUID

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
A device for the separation of liquid from a
slurry comprising a rotatable drum having a perforated wall
and an internal helical flange fixed to and extending inwards
from the drum wall to feed slurry along the drum from an in-
take end to a discharge end, wherein the axis of rotation of
the drum is inclined upwards from the intake end towards the
discharge end on the flange decreases in height from the intake
end towards the discharge end over at least a part of the length
of the drum and the drum has a central spillway opening at
the intake end for the overflow of excess slurry.

Revendications

The embodiments of the invention in which an exclu-
sive property or privilege is claimed, are defined as follows:
1. A device for the separation of liquid from a
slurry comprising a rotatable drum having a perforated wall and
an internal helical flange fixed to and extending inwards From
the drum wall to feed slurry along the drum from an intake end
to a discharge end, wherein the axis of rotation of the drum
is inclined upwards from the intake end towards the discharge
end and the flange decreases in height from the intake end
towards the discharge end over at least a part of the length
of the drum and the drum has a central spillway opening at the
intake end for the overflow of excess slurry.
2. A device as claimed in claim 1 in which the flange
has a portion at the discharge end which is of increased height
relative to the preceding portion.
3. A device as claimed in claim 2, in which the
decrease in height of the flange is continuous over the said
part of the length of the drum.
4. A device as claimed in claim 1, in which the
decrease in height of the flange is accompanied by a decrease
in pitch.
5. A device as claimed in claim 1, 3 or 4, in which
the discharge end of the drum has an end wall of frusto-conical
form tapering towards a discharge opening.
6. A device as claimed in claim 1, 3 or 4, in which
the spillway opening is formed by a pipe coaxial with the drum
and extending outwards form the intake end wall of the drum.

7. A device as claimed in claim 1, 3 or 4 having
a sensing device associated with the spillway opening to sense
the outflow of slurry through the spillway opening, the sen-
sing device being connected to regulate the supply of slurry.

Description

g~9
~ e l~:L(~ nt invcn,-ion r~ s -to a de-~ice ror the
sep~lr-ltioll of liqui.d :~rom a slu~ry.
It is a principal object of the invention to provide
a water ~;epara-tor of the kind mentioned by means of which it
is prevented that surplus ]i~uid is entrained with the nor-
mally dewatered residues fed out throuyh the discharge end
of -the drum, when the quantity of slurry supplied exceeds t'r.e
capacity of the device.
According to the present invention, ~here is provided
a device ~or the separation of liquid from a slurry compr;sing
a rotatable drum having a perforated wall and an internal heli-
cal fl.ange fixed to and extending inwards from the drum wall
to feed slurry along the drum from an intake end to a dis-
charge end, wherein the axis of rotation of the drum is incli-
ned upwards from the intake end towards the discharge end and
the flanqe decreases in height from the intake end towards
the discharge end over at least a part of the length of the
drum and the drum has a central spillway opening at the intake
end for the overflow of excess slurry.
An example of embodiment of the invention will be
described in the following, reference being made to the accom-
panying drawings, in which:
figure 1 is a schematic view of a longitudinal cross-
section through a dewatering device made according to the
invention; and
figure 2 is a schematical view of the same device as
seen from the left in figure 1.
The dewatering device illustrated in the drawings
includes a dewatering drum in its entirety indicated with 1
and comprising a perforated cylindrical mantle wall 2, at the
rear being partly closed by means of an end wall 3. At its

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opposite end an end wall 4 of the shape o:~ the frustrum of a
cone connects to the mantle wall, which end wall 4 in its
turn defines a dis~

charge opening in the narrow portion of the cone. A pipe socket 5
facing backwards as counted in the direction of feed connects to
the end wall 3 and is coaxially arranged relative to the mantle of
the dewatering drum. In slightly concentrical arrangement, i.e.
somewhat displaced in upwards direction a feeding tube 6 extends
into the interior of the dewatering drum, said tube 6 in the il-
lustrated example of embodiment exhibiting a slightly chamfered end
6a. In addition, the inlet tube at its end portion is provided
with an outlet opening 6b, which is indicated with a broken line
and which in the illustrated example exhibits a triangular shape.
The slurry supplied flows out of this opening in the direction of
the arrow indicated with 7, i.e. in sidewise direction to the mantle
wall of the drum 2. The dewatering drum is supported by a number
of supporting rollers 8 and 9 respectively, preferably in pairwise
arrangement at each one of the ends of the drum. These rollers
can preferably also be vertically adjustable in order to make
possible an adjustable setting of the angle of inclination of the
mantle of the drum. A feeding device 10 intended for the feed of
the slurry, which shall be dewatered, is mounted inside the drum,
said feeding device having the shape of a screw flange, which ex-
tends in radial direction from the inside of the mantle 2 towards
the centre of the dru~. As is evident from figure 1, the screw
10 exhibits a diminishing height of the flange as counted in the
direction of feed. In the embodiment illustrated the height of
the flange is greatest at a, while the height of the flange of its
portion b is somewhat smaller, the height of the flange at the por-
tion c being the smallest one. The screw terminates with a por-
tion d, which in the illustrated embodiment exhibits about the
same height of the flange as the portion a. Instead of a step-
wise diminishing of the height of the flange as in the embodimentillustrated it is of course within the scope of the fundamental
idea of the invention to let the height of the flange diminish by
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tapering off in the direction from the input end to the screw por-
tion d. As is also evident from the figure 1, the screw portions
b and c also exhibit a smaller pitch than the portions having a full
height of the flange, which leads to a better filling degree and a
better utilization of the whole surface of the mantle of the drum
in spite of the oblique angle of the inclination of the setting.
Liquid is normally separated from the slurry through the mantle of
the drum and flows down in the direction of the arrow 11 into a
collecting vat 12 provided below the dewatering drum, and from there
it is fed out via a discharge pipe 13. The end wall 3 of the in-
take side supports a driving gear ring 14 extending peripherically
and engaging a driving gear 15, which is connected to the outgoing
shaft gear of a driving motor 16. The driving motor drives the
dewatering drum in colmter-clodkwise direction according to figure
2, as is hinted by the arrow 17. Further, a brush 19 rotating in
the direction of the arrow 18 and provided with comparatively stiff
bristles is pressing against the mantle of the drum The brush 19
can possibly be driven by the mantle by lying against the same, so
that its bristles penetrate into the perforations of the mantle of
the drum and efficiently get cleansed from impurities. However, if
in spite of this the perforations of the drum would be clogged, there-
by causing an increase of the volume of fluid inside the drum, the
surplus fluid will flow out in the direction of the arrow 20 in
figure 1 over the spillway drain shaped by the pipe socket 5 being
at a lower level than the bottom edge of the discharge opening of
the drum at the opposite side. The surplus fluid flows down into
a collecting vat 21, and from there it is conveyed further on via
a drainage pipe 22. This fluid can by way of example be returned
to the dewatering device via the intake pipe 6. Because of the
diminishing height of the feed screw, an efficient separation of
surplus fluid is taking place along practically the whole length
of the feed screw. Thus, there is no risk that non-dewatered mate

7~
rial is fed out of the drum and via the discharge chute 23 being
conveyed to the point, where dewatered material is collected. More-
over, the arrangement illustrated under normal working conditions,
i.e. without any surplus liquid being introduced into the device,
has a very good dewatering effect, and the material leaving the
device is very dry.
The invention is not limited by the example of embodi-
ment described above and illustrated in the drawings. By way of
example a sensing element can also be provided in connection with
the spillway drain, which sensing device gives a regulation of the
quantity of slurry introduced into the device.