GB1596414A

GB1596414A - Device for the separation of liquid from a slurry

Info

Publication number: GB1596414A
Application number: GB48655/77A
Authority: GB
Original assignee: Roto Sieve AB
Current assignee: Roto Sieve AB
Priority date: 1976-11-22
Filing date: 1977-11-22
Publication date: 1981-08-26
Also published as: FI63525C; DK147097B; CH620593A5; FI773455A; FI63525B; NO143255B; NO143255C; ATA826177A; DE2751091C2; DK511477A; JPS6049004B2; NO773974L; CA1110979A; JPS5387063A; SE7613012L; AT352651B; BR7707729A; DE2751091A1; SE402716B; DK147097C

Abstract

This solves, in particular, the problem even if the quantity of sludge fed exceeds the capacity of this device. In all cases, therefore, the material leaving the device will be completely dehydrated as required for the various treatments to which it will then be subjected. The device in question comprises a rotary drum (1) of oblong form arranged in an inclined position, the outer shell (2) or peripheral surface thereof being provided with holes, while its interior contains a band (10) wound in a helical form or right-handed screw, whereas the rotary movement of the drum is left-handed, in order to convey the sludge or mud to the discharge end (4), the said band extending from the interior of the drum shell towards the centre. A part of this band has a height which decreases in the direction of feed. The device can be advantageously used for separating the solid part from the liquid part in sewage waters with a view to their purification. <IMAGE>

Description

(54) DEVICE FOR THE SEPARATION OF LIQUID FROM A SLURRY (71) We, ROTO-SEIVE AB a Swedish Company, of Hjorthagasgatan 10D, S413 17 Goteborg, Sweden, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to 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.

It is an object of the present invention to reduce the risk of surplus liquid being discharged with the dewatered slurry when the rate of supply of slurry to the intake end exceeds the capacity of the device.

In a device in accordance with the invention the axis of rotation of the drum is inclined upwards from the intake end towards the discharge end, the flange decreases in height from the intake end towards the discharge end over at least part of the length of the drum from the intake to the discharge end, and the drum has a central spillway opening at the intake end for the overflow of excess slurry.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic vertical section of a device in accordance with the invention, and Figure 2 is an end view of the device of Figure 1, seen from the left of Figure 1.

The dewatering device shown in the drawings includes a dewatering drum 1 having a perforated cylindrical wall 2, partially closed at the intake end (on the left in Figure 1) by an end wall 3. At the other end a frusto-conical wall 4 attached to the wall 2 defines at its nar row end a discharge opening from which the dewatered slurry is discharged. A short pipe 5 coaxical with the drum wall 2 extends outwards from the centre of the end wall 3 and forms a spillway opening for excess slurry.

The slurry to be dewatered is supplied to the intake end of the drum 1 by a feed pipe 6 extending through the pipe 5 parallel to the axis of the drum but disposed eccentrically above the axis. The feed pipe 6 has a chamfered end 6a and an outlet opening 6b which, as shown by the broken line in Figure 1, has a triangular shape. The slurry delivered from the outlet opening 6b, as shown by the arrow 7, is ejected to one side of the feed pipe 6 to strike the wall 2 of the drum above the lowermost point.

The drum 1 is rotatably supported on pairs of supporting rollers 8 and 9 at the intake and discharge ends respectively. The rollers 8 and 9 are so arranged that the axis of the drum is inclined upwards from the intake end to the discharge end and the rollers are preferably adjustable to enable this inclination to be varied. Fixed to the inner surface of the wall 2 of the drum is a helical flange 10 which serves to feed the slurry along the drum from the intake to the discharge end as the drum is rotated, the water being separated from the slurry and passing through the perforations of the drum wall 2 to fall as shown by the arrows 11 into a collecting tank 12. The dewatered slurry is then discharged through the opening defined by the frusto-conical wall 4 while the water leaves the tank 12 by way of a discharge pipe 13.

The helical flange 10, which extends radially inwards towards the axis of rotation of the drum, has a height which decreases from the intake end towards the discharge end over a part of the length of the drum. The height is greatest is the zone a of the drum, somewhat smaller in the zone b and smallest in the zone c.

In the zone d the height is greater again and approximately the same as in zone a. Instead of this stepwise change in height, the height could change progressively or continuously throughout the zones a, b and c. As is apparent from from Fig. 1 the flange 10 has a smaller pitch in the zones b and c than in the zone a which has the largest flange height. This ensures more complete filling and better utilization of the whole of the cylindrical wall of the drum in spite of the inclination of the drum.

Referring now to Figure 2 the end wall 3 of the drum at the intake end supports a ring gear 14 which is driven by a spur gear 15 on the output shaft of a motor 16. The motor 16 drives the drum in an anticlockwise direction as shown in Figure 2 by the arrow 17. A brush 19 rotating in the direction of the arrow 18 and having fairly stiff bristles presses against the perforated cylindrical wall of the drum. The brush 19 can be driven by contact with the drum and its bristles penetrate the perforations in order to remove solids therefrom. If in spite of this there is clogging of the perforations which leads to an increase in the volume of liquid in the drum, the surplus slurry will flow out of the pipe 5 as indicated by the arrow 20. For this purpose the lower part of the pipe 5 should preferably be below the bottom edge of the discharge opening in the wall 4. The overflow of surplus slurry is collected in a tank 21 from which it can be withdrawn by way of a drainage pipe 22 and may, for example, be returned to the drum by way of the feed pipe 6.

Because of the decrease in height of the helical flange along the length of the drum, efficient separation of liquid from the slurry takes place along practically the whole length of the drum. The dewatered material is fed out of the discharge opening onto a discharge chute 23 and even when slurry is delivered to the drum faster than it can be separated the overflow through the pipe 5 prevents discharge of surplus liquid or slurry to the chute 23.

Under normal working conditions, i.e. without any surplus liquid being introduced, good dewatering is obtained and the material discharged by way of the chute 23 is very dry.

A sensing device may be associated with the spillway opening to sense the outflow of slurry through the spillway opening, the sensing device being connected to regulate the supply of slurry.

WHAT WE CLAIM IS: 1. A device for the separation of liquid from a slurry comprising a rotatable drum having a perforated wall and an intemal helical flange fixed to and extending inwards from the drum wall to feed slurry along the drum from an intake end, wherein the axis of rotation of the drum is inclined upwards from the intake end towards the discharge end, the flange decreases in height from the intake end towards the discharge end over at least a part of the length of the drum from the intake to the discharge end, 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 reletive to the preceding portion.

3. A device as claimed in Claim l or 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 any of Claims 1 to 3 in which the decrease in height of the flange is accompanied by a decrease in pitch 5. A device as claimed in any of the claims 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 any of the preciding claims in which the spillway opening is formed by a pipe coaxial with the drum and extending outwards from a flat end wall of the drum.

7. A device as claimed in any of the preceding claims having a sensing device associated with the spillway opening to sense the outflow of slurry through the spillway opening, the sensing device being connected to regulate the supply of slurry.

8. A device for the separation of liquid from a slurry substantially as described with reference to the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. in Figure 2 by the arrow 17. A brush 19 rotating in the direction of the arrow 18 and having fairly stiff bristles presses against the perforated cylindrical wall of the drum. The brush 19 can be driven by contact with the drum and its bristles penetrate the perforations in order to remove solids therefrom. If in spite of this there is clogging of the perforations which leads to an increase in the volume of liquid in the drum, the surplus slurry will flow out of the pipe 5 as indicated by the arrow 20. For this purpose the lower part of the pipe 5 should preferably be below the bottom edge of the discharge opening in the wall 4. The overflow of surplus slurry is collected in a tank 21 from which it can be withdrawn by way of a drainage pipe 22 and may, for example, be returned to the drum by way of the feed pipe 6. Because of the decrease in height of the helical flange along the length of the drum, efficient separation of liquid from the slurry takes place along practically the whole length of the drum. The dewatered material is fed out of the discharge opening onto a discharge chute 23 and even when slurry is delivered to the drum faster than it can be separated the overflow through the pipe 5 prevents discharge of surplus liquid or slurry to the chute 23. Under normal working conditions, i.e. without any surplus liquid being introduced, good dewatering is obtained and the material discharged by way of the chute 23 is very dry. A sensing device may be associated with the spillway opening to sense the outflow of slurry through the spillway opening, the sensing device being connected to regulate the supply of slurry. WHAT WE CLAIM IS:

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

4. A device as claimed in any of Claims 1 to 3 in which the decrease in height of the flange is accompanied by a decrease in pitch

5. A device as claimed in any of the claims in which the discharge end of the drum has an end wall of frusto-conical form tapering towards a discharge opening.