WO1992000920A1

WO1992000920A1 - Flexible partition

Info

Publication number: WO1992000920A1
Application number: PCT/GB1991/001129
Authority: WO
Inventors: Keith Thatcher
Original assignee: Dunlop Limited
Priority date: 1990-07-12
Filing date: 1991-07-10
Publication date: 1992-01-23
Also published as: GB9015338D0; AU8199091A

Abstract

A flexible partition (13) for use in dividing into two zones the liquid in a vessel such as an aerated sludge tank comprises a plurality of individually substantially rigid segments (17) arranged in a two-dimensional array and flexibly interconnected whereby the array of segments (17) is flexible about at least one axis contained within the plane of the array at least some of the segments (17) proximate an edge region of the array being anchor segments (25) of a weight greater than that of other segments (17) of the array.

Description

FLEXIBLE PARTITION

This invention relates to a flexible partition and in particular, though not exclusively, to a flexible partition for use as a selectively movable vertical curtain to divide into two zones the liquid contained in a vessel such as an aerated sludge tank.

In the operation of an aerated sludge tank it may be necessary to provide an anoxic zone for denitrification. To separate liquid in the anoxic zone from the remainder of the tank a vertical divider member is provided and arranged to be movable in a horizontal direction within the tank whereby the volume of the anoxic zone may be selectively varied in response to changes in process operating requirements.

The vertical divider does not need substantial structural strength to contain hydrostatic forces since _ the liquid at each side of the divider has the same surface level. However, a degree of stability is required so that it does not distort unduly, and cease to function effectively as a divider, under the fluid flow forces that arise when mechanical mixers are used to generate forced circulation of fluid within a zone to one side of the divider. For this reason rigid structures, unless of unacceptable weight, are liable to distortion and like damage; flexible dividers have therefore been preferred.

Conventionally the vertical divider is constructed from a pvc coated fabric to which weights are secured in an attempt to restrain undue distortion of the blanket when a face of the divider is subject to fluid flow forces. Weighting of the pvc coated fabric has caused difficulties; there is a difficulty in securing weights without damage to the fabric and of achieving a uniformity of weighting over the entire surface area of the fabric.

The present invention seeks to provide a flexible partition which is particularly suitable for use as a vertical divider to separate two zones of fluid and in particular, though not exclusively, for use of a selectively movable divider within an aerated sludge tank.

In accordance with one of its aspects the present invention provides a flexible partition comprising a plurality of individually substantially rigid segments arranged in a two-dimensional array and flexibly interconnected whereby the array of segments is flexible about at least one axis contained within the plane of the array, and at least some of the segments proximate an edge region of the array being anchor segments of a weight greater than that of other segments of the array.

The anchor segments preferably each comprise a hollow shell-like body filled with ballast material such as concrete. At least some of the anchor segments may contain a foamed type of concrete which has a lower specific gravity than conventional concrete but is nevertheless of sufficient density to provide a significant weighting effect.

Said other segments of the array may be of a hollow construction to define a chamber into which fluid may flow or which may be filled with a material such as foam of a lower weight than that of the ballast material.

The flexible partition may be of generally rectangular shape.

An edge opposite said edge region at which at least some of the segments are anchor segments, i e a support edge at which the partition may be supported to hang vertically, preferably is bereft of anchor segments. The anchor segments may be provided only in one half of the flexible partition which is remote from an edge at which it is supported.

Each segment preferably comprises a shell of plastics material. It is preferred also that segments are flexibly interconnected by rope means which may be arranged to extend directly through each segment to interconnect segments in series. The rope means may, for example, extend in two directions to provide a biaxially flexible array or, for example, in three directions to provide triaxial flexibility. Said rope means may extend to a support edge for supporting the partition in a vertically suspended configuration.

Preferably each segment is shaped such that in the flexible partition the segments lie in a close packed array to be substantially contiguous and thereby eliminate any openings of a size through which a significant quantity of fluid may flow.

To facilitate flexibility in a close packed array of substantially contiguous segments connected by ropes extending through the segments preferably each segment has a locally recessed surface area where the rope enters the segment. There is thereby achieved a short length of exposed rope between neighbouring segments and which significantly assists flexibility.

Each segment may be of a tapered construction to further assist flexibility. It may be tapered in one direction from a median plane, or in each direction from a median plane so that a face of the array may be flexed to possess either a concave or convex shape.

A particularly suitable cross-sectional shape for a segment, as considered in cross-section in a plane parallel with the plane of the array, is a regular hexagonal shape. This facilitates provision of a triaxially flexible array.

Particularly suitable segments and arrays of segments for constructing a flexible partition in accordance with the present invention are described in the specification of GB 2156941A. Each segment may be of a two-part shell construction as described in the specification of pending GB Patent Application 9009408.7.

Where the array comprises a neighbouring series of segments aligned in a row at one edge of the array, all or some of those segments may be anchor segments. The invention further provides a tank installation and method of operation of a tank installation such as that of an activated sludge tank wherein a support structure is provided to support within the tank a vertical flexible partition of a kind in accordance with the invention. Preferably said support structure is operable to move the partition in a horizontal direction and more preferably to move it in a horizontal direction whilst within the tank, thereby to vary the volume of liquid lying in the tank to one side of the partition.

The rope means of the flexible partition may be employed to suspend the partition from the support structure.

One embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:-

Figure 1 is a vertical sectional view through a sludge tank incorporating a flexible partition in accordance with the present invention;

Figure 2 is a perspective view of an anchor segment forming the partition shown in Figure 1, and

Figure 3 is a vertical section of the segment of Figure 2.

The tank assembly shown in Figure 1 for the processing of liquid sludge comprises a concrete wall structure 11 and aeration pipework 12 at the base of the tank.

A flexible divider curtain 13 is suspended vertically in the tank from a support girder 14 the ends of which rest on support rails 15 provided at edges of the tank. The support girder 14 is provided with a pair of lifting eyes 16 whereby it may be lifted slightly from the rails 15 and moved longitudinally along the direction of the length of the tank.

The flexible divider curtain 13 comprises a two-dimensional array of segments 17 each of hexagonal shape as viewed in Figure 1.

Each segment comprises a hollow plastics shell 18, the hexagonal cross-sectional shape having a maximum dimension at a median plane 19 (see Figure 3) and which is tapered from that median plane towards each end 20,21.

The segments are arranged in a substantially contiguous manner in vertically extending rows 22 as viewed in Figure 1. The segments in each row are flexibly interconnected by a vertically extending load supporting rope 23 which extends through each of the shells from a lower segment, through the uppermost segment of the row to terminate at the support girder 14. The adjacent vertically extending rows 22 are vertically offset relative to one another whereby the segments of adjacent rows adopt a nested configuration to provide a substantially contiguous array. The rows are maintained in a side-by-side relationship by means of auxiliary rope means 24, portions 24a of which extend through opposing pairs of segment faces lying at one direction of inclination to the vertical and portions 24b of which extend through segment faces lying at the other inclined direction to the vertical.

Each segment 17 comprises the aforementioned plastics shell but the lowermost segment 25 of each vertically extending row is an anchor segment the internal cavity of which is wholly filled with concrete 26 to act as a ballast material. The other segments may be hollow, so as to become filled with liquid when in use in a sludge tank, or may for example be filled with foam.

As best seen from Figure 3 each side face of the segment shell 18 (at the median zone 19 at which the rope 22,24a,24b extends therethrough) has a recessed opening 27 thereby to provide an exposed, free length of rope between adjacent segments. In combination with the tapered shape of each segment this results in the array of hexagonal segments being substantially triaxially flexible and able to deform so that either face of the curtain may adopt a concave or convex profile if subject to high transverse forces.

Normally the weight of the anchor segments 25 will be sufficient to hold the curtain 13 in a vertical and substantially planar form without any significant deformation under the action of fluid flow forces arising from enforced circulation of fluid by mechanical circulators. However, the inherent flexibility of the array is such that in the event of a high transverse force arising no permanent damage is caused to the divider. The flexibility of the divider curtain is beneficial also in that when the curtain requires to be removed it may be stored or transported in a rolled configuration and therefore be more compact than a rigid divider structure.

Claims

CLAIMS :

1. A flexible partition comprising a plurality of individually substantially rigid segments arranged in a two-dimensional array and flexibly interconnected whereby the array of segments is flexible about at least one axis contained within the plane of the array, and at least some of the segments proximate an edge region of the array being anchor segments of a weight greater than that of other segments of the array.

2. A flexible partition according to claim 1 wherein at least some of said anchor segments comprise a hollow shell-like body filled with ballast material.

3. A flexible partition according to claim 1 or claim 2 wherein at least some of said other segments of the array are of a hollow construction to define a chamber into which fluid may flow.

4. A flexible partition according to any one of the preceding claims wherein at least some of said other segments comprise a hollow shell-like body filled at least in part with a material of a lower specific gravity than that of the ballast material.

5. A flexible partition according to claim 2 or claim 4 wherein the filling material is a foam.

6. A flexible partition according to any one of the preceding claims wherein at least some of the segments comprise a shell of plastics material.

7. A flexible partition according to any one of the preceding claims and having a support edge at a position substantially opposite said edge region at which at least some of the segments are anchor segments, said support edge being adapted to enable the partition to be hung in a vertical manner.

8. A flexible partition according to any one of the preceding claims wherein the segments are flexibly interconnected by rope means.

9. A flexible partition according to claim 8 wherein said rope means is arranged to extend directly through each segment to interconnect segments in series.

10. A flexible partition according to claim 8 or claim 9 wherein the rope means extends in two directions to provide a biaxially flexible array.

11. A flexible partition according to any one of claims 8 to 10 when dependent on claim 7 wherein said rope means extends to said support edge for supporting the partition in a vertically suspended configuration.

12. A flexible partition according to any one of the preceding claims wherein the segments lie in a close packed array thereby to be substantially contiguous.

13. A flexible partition according to any one of the preceding claims wherein a segment has a locally recessed surface area at a point where rope means interconnecting two segments enters said segment.

14. A flexible array according to any one of the preceding claims wherein each segment is of a tapered construction.

15. A flexible partition constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

16. Method of operation of a tank installation wherein a support structure is provided to support within the tank a vertical flexible partition of a kind according to any one of the preceding claims.

17. Method according to claim 16 wherein during operation of the tank installation said support structure is operated to move the partition in a horizontal direction.

18. Method according to claim 17 wherein said support structure is operated to move the partition in a horizontal direction whilst within the tank.

19. Method of operation of a tank installation substantially as hereinbefore described with reference to the accompanying drawings.