GB2309398A

GB2309398A - Self-cleaning flow-powered rotary drum

Info

Publication number: GB2309398A
Application number: GB9701183A
Authority: GB
Inventors: Grant Andrew Ockleston
Original assignee: Thames Water Utilities Ltd
Current assignee: Thames Water Utilities Ltd
Priority date: 1996-01-23
Filing date: 1997-01-21
Publication date: 1997-07-30
Also published as: GB9601248D0; GB9701183D0

Abstract

A filter for removing solids 2 from a flow of liquid 3 comprises a perforated rotary drum screen 5 arranged for inward filtration, an internal baffle 9 for directing liquid onto an inner surface of the drum causing rotation of the drum, and an external scraper blade 8 for cleaning the rotating drum. The baffle extends across the width of the drum, directing the liquid to the side opposite the inlet zone 7 causing rotation in direction Y. The end 11 of the baffle is curved in the direction of rotation. The scraper blade 8 is directed in the opposite direction to the direction of rotation.

Description

A SCREEN APPARATUS The invention relates to a screen apparatus, particularly a screen for removing solids from a liquid flow containing same.

It is often necessary, in for example sewage works. to provide for removal of solids in a liquid flow, particularly in times of flood.

Such sewage works or sewage systems usually have a solids removal system, but in times of flood the volume is usually such that existing systems cannot cope with the excess flow, with the undesirable result that such excess passes to surface streams, etc.

It is an object of the invention to seek to mitigate this disadvantage.

According to a first aspect of the invention there is provided apparatus for removing solids from a liquid flow containing same, comprising a screen which is rotatable under the influence of the flow of liquid being screened and which has an internal baffle plate element for directing liquid internally across the screen for effecting that motion, and an external device adapted to clean the screen, the arrangement being such that the flow of liquid also actuates a cleaning action by rotating the screen past the cleaning device.

The internal baffle plate element may have a free end adjacent an exit zone from the screen whereby to direct liquid onto an interior surface of the screen at or adjacent the exit zone for promoting rotation of the screen. This is a relatively simple construction, particularly where the free end of the baffle plate element may be directed in the direction of rotation, suitably by being curved.

The screen may suitably comprise a rotatable drum screen. This is an efficient construction, particularly when the drum screen may comprise a substantially cylindrical drum suitably defined by a perforated body.

The cleaning device may comprise an external scraper device arranged to remove solids accumulated on the exterior surface of the screen. This is a relatively simple way of cleaning the screen, particularly as the scraper device may have a scraper part which is directed in a direction opposite the direction of rotation of the screen. This lifts trapped solids from the screen in an efficient manner.

According to a second aspect of the invention there is provided a sewage system, including apparatus as hereinbefore defined.

Apparatus for use in a sewage works or system for removing solids from a liquid flow containing same, is hereinafter described, by way of example, with reference to the accompanying drawings.

Fig. 1 is a schematic side elevational view of apparatus according to the invention; and Fig. 1A is an enlarged view of the part 'X' of Fig. 1.

Referring to the drawings, there is shown apparatus in the form of a screen 1 for removing solids 2 from a liquid flow 3 containing same, comprising means 4 adapted to clean the screen 1, the arrangement being such that the flow of liquid actuates a cleaning action.

The screen 1 is thus self-powered and self-cleaning, and comprises a rotatable cylindrical drum 5 (Fig. 1A) defined by a perforated body, suitably of metal, supported suitably by internal supports or spiders 6. Mounted adjacent an inlet zone 7 for liquid is the means 4 in the form of a scraper device in the form of a knife blade 8 which has its free end or scraper blade part turned in a direction facing towards i.e. opposite, the direction of rotation of the body, shown by arrow 'Y'.

Internally of the body 5 there is transfer means 9 in the form of a transfer plate element which extends internally from the inlet zone 7 substantially diametrically towards an exit zone 10 for liquid from the body 5. The plate element 9 is inclined downwardly (from left to right as viewed in Fig. 1) so that liquid is directed internally downwardly in use across the body to the exit zone 10.

The drum 5 is suitably open ended, being supported at each end by the supports or spiders 6. The transfer plate element 9 is fixed internally of the drum, being secured to and carried by end bosses 6'about which the drum rotates, there being a clearance at each end of the plate element 9 to allow for rotation of the drum.

A free end 11 of the transfer plate element 9 terminates internally of the drum in the region of the exit zone 10 and is curved downwardly as viewed, so that it is directed or points in the direction 'Y' of rotation. The free end 11 is remote from the inlet zone 7. Thus liquid flooding across the transfer plate element 9, from the inlet zone 7, strikes the interior surface of the body of the drum and rotates it, thereby rotating the inlet zone 7, on the exterior of which removed solids 2 are accumulated, past the blade 8, which removes the solids from the screen 1. The liquid, having effected self-rotation and hence self-cleaning escapes from the drum through the perforations 12 as shown by the arrows 'R'.

Continued flooding of the liquid across the plate element 9 will, it will be understood, maintain the promotion of self-rotation and self-cleaning.

As shown, the apparatus 1 is placed adjacent a weir 13 of, say a sewer or storm system. The height of liquid containing solids above the weir is shown at 'H', excess liquid with its entrapped solids being shown as flowing in the direction of the arrow 'T' over the weir 13 to the inlet zone 7 for removal of solids.

The apparatus 1 hereinbefore described with reference to the drawings is particularly suitable for use in sewerage systems, storm water systems, and/or combined sewage overflow, whereby any liquid in excess of the capacity of the system flows over the weir, through the perforated drum and onto the internal flow transfer plate.

The liquid moves over the internal transfer plate element 9 to the internal face of the drum 5 furthest from the weir 13. The liquid flows back through the perforations 12 in the drum 5 and cleaning the drum and at the exit zone 10 providing power to rotate the drum in the clockwise direction as viewed. This screened liquid is discharged to a local surface water source, and any solids 2 trapped on the surface of the drum 5 at the inlet zone 2 are removed by the knife edged scraper 8 to be re entrained within the flow to the treatment works.

Claims

1. Apparatus for removing solids from a liquid flow containing same, comprising a screen which is rotatable under the influence of the flow of liquid being screened and which has an internal baffle plate element for directing liquid internally across the screen for effecting that motion, and an external device adapted to clean the screen, the arrangement being such that the flow of liquid also actuates a cleaning action by rotating the screen past the cleaning device.

2. Apparatus according to Claim 1, the internal baffle plate element having a free end adjacent an exit zone from the screen whereby to direct liquid onto an interior surface of the screen at or adjacent the exit zone for promoting rotation of the screen.

3. Apparatus according to Claim 2, the free end of the baffle plate element being directed in the direction of rotation.

4. A screen according to Claim 3, the free end being curved.

5. Apparatus according to any preceding claim, the screen comprising a rotatable drum screen.

6. Apparatus according to Claim 5, the drum screen comprising a substantially cylindrical drum defined by a perforated body.

7. Apparatus according to any preceding claim, the cleaning device comprising an external scraper device arranged to remove solids accumulated on the exterior surface of the screen.

8. Apparatus according to Claim 7, the scraper device having a scraper part which is directed in a direction opposite the direction of rotation of the screen.

9. Apparatus for removing solids from a liquid flow containing same, substantially as hereinbefore described in the accompanying drawings.

10. A sewage system, including apparatus according to any preceding claim.