GB2233247A

GB2233247A - Moving belt filter

Info

Publication number: GB2233247A
Application number: GB9013701A
Authority: GB
Inventors: Eric Paul Austin
Original assignee: Simon Hartley Ltd
Current assignee: Simon Hartley Ltd
Priority date: 1989-06-21
Filing date: 1990-06-20
Publication date: 1991-01-09
Also published as: GB8914219D0; GB9013701D0; DE4019545A1

Abstract

A moving belt filter for dewatering chemically conditioned sludges has one or more rows of transversely spaced sludge deflectors (15) on or close to the surface of the belt (12) and suspended by leaf springs (16) from an overhead beam (17), which is fixed but pivotable about an axis (21) for servicing or replacement of parts. Each deflector (16), in plan, diverges rearwardly from its front and may also taper upwards or downwards, Preferably, several rows of deflectors are provided along the belt with the deflectors of each row being offset transversely with respect of those of the next row. Deflectors have base plates of low-friction plastics and may be adjustable along beam 17. <IMAGE>

Description

1 1 A SLUDGE DEWATERING SYSTEM :2:.2 L3;, - -1.

THIS INVENTION concerns a sludge dewatering system. The removal of water from chemically conditioned sludges using belt presses and gravity drainage belts is well known.

Various peripheral items have been incorporated into systems for this purpose, in order to assist in the removal by gravity of the released water. Such devices have been based on the deflection of the sludge as it is carried along a moving foraminous belt in order that water which is standing on the surface of the sludge is allowed to pass downwardly through the belt for disposal or collection. This action leaves a more concentrated sludge on the belt such that subsequent pressure dewatering may be more economically carried out.

is It is an object of the present invention to provide an improved sludge dewatering system in which not only is sludge deflection achieved but that by controllably constricting the flow passage of the sludge. substantially horizontal pressure is exerted on the solids contained in the sludge thus squeezing out entrained water.

According to the present invention there i S EF/2047 provided a sludge dewatering system comprising a moving foraminous belt having a horizontal conveying run onto which sludge is deposited to be carried along said conveying run while water is permitted to drain from the sludge and to pass through the belt for collection, characterised in that in at least one location along the conveying run there is provided a transverse row of deflectors suspended just above or in contact with the belt thus to reside in a moving bed of sludge thereon, the deflectors being mounted on one or more flexible members attached to an overhead beam extending transversely across the belt and attached to supporting members beyond the side edges of the belt.

It may be important not to restrict excessively the 15 passage of sludge being transported by the belt and hence cause undesirable build up which could overflow the belt sides. To overcome this problem the deflectors are shaped such that at any transverse vertical cross-section they present a progressively reducing width upwardly i.e. with respect to their height. The width of each deflector increases in plan from upstream to downstream.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Fig. 1 is an isometric view of part of a sludge EF/2047 dewatering system incorporating the invention; and Fig. 2 is a vertical section taken along line II II Of Fig. 1.

Referring now to the drawingsp a system for dewatering sludge comprises a framework consisting essentially of two parallel supporting members 10 between which extends a belt support grid of parallel transverse members 11.

An endless foraminous conveying belt 12 is driven along the support grid 11 in a direction as indicated by arrow 13.

Means (not shown) are provided to deposit chemically conditioned sludge in a continuous bed extending across the belt between side guides 14.

In accordance with the invention in at least one location along the conveying run of belt 12 there is provided a row of deflectors 15. Each deflector is suspended on a leaf spring 16 of spring steel or the like whose upper end is rigidly attached to an overhead beam 17. The beam 17 is attached at its ends by legs 18 to brackets 19 fixed to support members 10.

j - 4 - EF/2047 1k Each deflector 15 is preferably of solid construction, and it may be covered at its base by a galosh or overshoe 15a of thermoplastics material or other deformable or elastic material which provides a low coefficient friction with the surface of the belt 12. Thus the deflectors 15 rest upon the belt, whilst the overhead beam 17 and legs 18 are held in an operative position by means of a locking pin 20 which. however, if removed will permit the whole deflector and beam assembly on legs 18 to pivot in a clockwise direction as viewed in Fig. 2 about a pivotal axis 21. When the locking pin 20 is removed the assembly is in an inoperative condition and may be pivoted away from the belt for servicing or replacement of parts.

The deflectors 15 are mounted in such a way that each is in a fixed position relative to the others and to the belt surface. In a complete system a plurality of rows of deflectors is provided with the deflectors of one row being offset transversely with respect to those of the next row so that the entire bed of sludge must flow around at least one deflector. Preferably, the transverse positions of the deflectors on beam 17 are adjustable in order to determine the horizontal pressure exerted on the sludge as it passes between adjacent deflectors.

The longitudinal spaces between the rows of deflectors is also preferably adjustable according to the remaining fluidity of the sludge as it progresses through - the dewatering zone.

EF/2047 In use as the sludge flows around the deflectors it is parted thus to create a cleared width of belt downstream. In this way, water released from either side of each such cleared width is permitted to drain more freely and rapidly through the belt in the cleared zone.

Furthermore, during passage around a deflector there is a horizontal pressure exerted on the sludge which exerts a squeezing action on the sludge to effect further removal of water.

Each deflector 15 which is formed rather like a flat iron, is capable of movement upwardly by the flexibility of its associated leaf spring 16, in order to permit the passage of any large solid objects An the sludge. Each leaf spring has a certain width to ensure stability of its associated deflector about its longitudinal axis.

The transverse cross section of each deflector may taper upwardly from, or downwardly towards, its base, in order to determine the deqree of restriction of the sludge as it passes between the deflectors. Also, the width of each deflector increases in plan from upstream to downstream.

CM1LIMS is EF/2047 1. A sludge dewatering system comprising a moving foraminous belt having a horizontal conveying run onto which sludge is deposited to be carried along said conveying run while water is permitted to drain from the sludge and pass through the belt for collection, characterised in that in at least one location along the conveying run there is provided a transverse row of deflectors suspended just above or in contact with the belt thus to reside in a moving bed of sludge thereon, the deflectors being mounted on one or more flexible members attached to an overhead beam extending transversely across the belt and attached to supporting members beyond the side edges of the belt.

Claims

2. A sludge dewatering system according to Claim

1, in which each deflector is shaped such that at any transverse vertical cross-section it presents a progressively reducing width upwardly i.e. with respect to its height.

3. A sludge dewatering system according to Claim 1, in which each deflector is shaped such that at any transverse vertical cross-section it presents a progressively increasing width upwardly i.e. with 7 - respect to its height.

EF/2047 4. A sludge dewatering system according to any preceding claim, wherein the width of each deflector increases in plan from upstream end to downstream end.

5. A sludge dewatering system according to any preceding claim, in which each said flexible member comprises a leaf spring of spring steel or the like whose upper end is rigidly attached to said overhead beam.

6. A sludge dewatering system according to Claim 5, wherein the position of attachment of each said leaf spring along said overhead beam, is adjustable.

7. A sludge dewatering system according to any preceding claim, wherein each deflector is of solid construction and is covered at its base by a material which provides a low coefficient of friction with the surface of the belt.

8. A sludge dewatering system according to any preceding claim, wherein the attachment of said overhead beam to said supporting members is adjustable whereby said at least one row of deflectors may be removed from the surface of the belt for servicing or - 8 EF/2047 replacement of parts.

9. A sludge dewatering system according to any preceding claim, comprising a plurality of rows of deflectors, the deflectors of each row being offset transversely with respect to those of the next succeeding row so that the entire bed of sludge must flow around at least one deflector.

10. A sludge dewatering system according to Claim 9, wherein the distance between said rows of deflectors 10 is adjustable.

11. A sludge dewatering system according to any preceding claim, including a pair of side guides located above and close to the conveying surface of the foraminous belt beyond the outermost deflectors in the or each said row thus to contain a bed of sludge on the belt.

12. A sludge dewatering system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Published 1991 at The Patent Office. State House. 66171 High Holbom. London WC I R 4TP. Further copies may be obtained froni7be Patent OfficeSales Branch. St Mary Cray. Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd. St Marv Crav. Kent. Con. 1187