GB2262500A

GB2262500A - A method of and apparatus for filling filter beds.

Info

Publication number: GB2262500A
Application number: GB9303010A
Authority: GB
Inventors: Alan Charles Kershaw
Original assignee: DOITY ENGINEERING Ltd
Current assignee: DOITY ENGINEERING Ltd
Priority date: 1992-02-19
Filing date: 1993-02-15
Publication date: 1993-06-23
Anticipated expiration: 2013-02-15
Also published as: GB9203484D0; GB2262500B; GB9303010D0

Abstract

A system for introducing loose filter medium onto the floor (12) of a (usually) circular tank (10) to produce a filter bed therein, comprising a fixed feed conveyor (14) extending radially from outside of the tank (10) to a central position therein, and a distributing conveyor (19) having an input end (18) located to receive filter medium from the output end of feed conveyor (14) and to carry same radially outwards towards the outer end which rests on a carriage (20) movable around the top of tank wall (10). A discharging device (21) is movable incrementally along distributing conveyor (19) to discharge material therefrom at selected radial locations to place a uniform layer of filter medium over the tank floor (12). The process is complete when the filter bed has been built up to the required depth. <IMAGE>

Description

A METHOD OF AND APPARATUS FOR FILLING FILTER BEDS THIS INVENTION concerns a system for introducing loose filter medium into a filter tank to produce a filter bed of the kind used as a percolating filter in a water treatment plant.

Such filter beds are usually but not necessarily circular and may be some 35 metres in diameter and 2 metres deep.

The wall of the tank may be constructed from prefabricated concrete panels, and an apertured floor is formed from ceramic tiles. The filter medium which fills the tank is usually washed and screened stone aggregate and is introduced once the walls and the floor have been completed.

Since the ceramic floor is of a delicate nature the weight of any equipment used to aid the filling process must be strictly limited and filling is conventionally carried out using a crane and bucket system. Inevitably therefore the filling process takes a great deal of time and requires that the crane and a supply of screened filter material are placed closely adjacent the tank to minimise the traversing distance for the bucket. On some sites, there is limited access to the tank, and so an object of the present invention is to provide a system for filling such a tank whereby the process is completed more rapidly and where there is limited access.

According to the present invention there is provided a method of introducing loose filter medium into a tank to produce a filter bed, comprising the steps of placing within the tank at least one transportable distributing conveyor having an input end located at a position to receive filter medium, an output end movably supported on the tank wall, and a discharging device movable along the distributing conveyor for discharging filter medium therefrom at selected positions therealong; supplying filter medium to the input end of the distributing conveyor; depositing filter medium from the distributing conveyor via the discharging device onto the tank floor and moving the discharging device and the distributing conveyor progressively to distribute filter medium uniformly over the tank floor.

Further, according to the present invention there is provided apparatus for introducing loose filter medium into a tank to produce a filter bed, comprising at least one transportable distributing conveyor having an input end located at a position to receive filter medium, an output end movably supported on the tank wall, and a discharging device movable along the distributing conveyor for discharging filter medium therefrom at selected positions therealong onto the tank floor.

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 a schematic plan view of a circular tank for a filter bed, with filling apparatus in situ thereon; and Fig. 2 is a section taken on line II-II of Fig. 1.

Referring now to the drawings a circular filter bed comprises a tank having an upstanding wall 10, usually circular in plan and typically 2 metres in height which extends upwardly from a floor or base 11 formed entirely from an array of apertured ceramic tiles 12. A central support column 13 is provided, which in the finished filter bed will support and house a rotating distributor arm and supply pipework.

The present invention is concerned with filling the tank uniformly during construction, to produce the filter bed.

To avoid the time consuming method conventionally carried out for placing loose filter medium into the tank, and in accordance with one embodiment of the invention, there is provided a system comprising a driven feed conveyor 14 which rests adjacent its respective input and output ends on the wall 10 and on a support 15 located on the column 13 The conveyor 14 has a moving troughed belt which carries material from the input end 16 to outside of the tank output end 17 above the column 13. The input end 16 of the conveyor 14 may be fed directly from a screening and washing unit supplying the filter material.

Immediately beneath the output 17 of conveyor 14 and pivotally located about a vertical axis above the centre of column 13 is an input hopper 18 of a driven distributing conveyor 19 whose outermost end is supported on a wheeled cradle 20 adapted to run along a track provided by the upper surface of the wall 10. Thus the distributing conveyor is rotatably transportable around the tank.

Adjustably located at 0.75-metre intervals along the distributing conveyor 19 is a discharging device 21. This device comprises a chute 22 directed transversely and downwardly to one side of the conveyor 19, and a series of ramping rollers 23 which serve to carry the conveyor belt 24 of conveyor 19 upwardly to the top of the chute 22 where it discharges on to the latter. The belt is then taken around an uppermost one of the ramping rollers 23 and around a further roller 25 before proceeding onwardly towards the remote end of the conveyor 19. Thus, wherever the discharging device 21 is placed along the conveyor 19, material carried thereby is discharged from the chute 22 onto the tank floor 11 therebeneath.

In use therefore, the distributing conveyor 19 is initially placed at an angular position close to the feed conveyor 14 with the discharging device located at its outermost position of adjustment along the conveyor. Filter medium is transported continuously from the input end 16 of the feed conveyor 14 and onwardly onto conveyor 19 to the discharging device 21 to be deposited onto the tank floor initially at a position close to the wall 10.

Progressively, the distributing conveyor 19 is indexed around the tank to distribute the filter material substantially evenly around the base of wall 10. After the conveyor 19 has moved through approximately 3600, the process is repeated with the discharging device placed at a second adjustable position inwardly of the wall 10. By progressively indexing the discharging device along the conveyor 19 and rotating the latter around the tank, the entire space within the tank may be filled rapidly and uniformly with filter material until the required depth of filter bed has been established.

Thereafter, the entire assembly consisting of the feed conveyor 14, the distributing conveyor 19 and the discharging device 21, may be removed from site and replaced by the further equipment necessary to complete the filter bed.

During the filling process, movement of the distributing conveyor 19 around the tank may be effected manually or by an electric motor drive on the cradle 20.

If required, to speed up the filling process, there may be provided a plurality of feed and/or distributing conveyors operating simultaneously.

During the filling operation, it is preferable to place filter medium uniformly across the entire floor of the tank and then gradually to increase the depth This ensures that the load on the ceramic tiles 12 is evenly distributed and the material is uniformly compacted.

The concept of combining the operations of a feed conveyor and a transportable distributing conveyor with a movable discharging device thereon, may be applied also to a rectangular tank.

In this case, the distributing conveyor will move in a linear rather than a circular path. In some such cases, the feed conveyor may be omitted and the filter material fed directly to the input end of the distributing conveyor.

Claims

1. A method of introducing loose filter medium into a tank to produce a filter bed, comprising the steps of placing within the tank at least one transportable distributing conveyor having an input end located at a position to receive filter medium, an output end movably supported on the tank wall, and a discharging device movable along the distributing conveyor for discharging filter medium therefrom at selected positions therealong; supplying filter medium to the input end of the distributing conveyor; depositing filter medium from the distributing conveyor via the discharging device onto the tank floor and moving the discharging device and the distributing conveyor progressively to distribute filter medium uniformly over the tank floor.

2. A method according to Claim l including the step of providing at least one driven feed conveyor feeding filter medium from a position outside of the tank to the position at which the input end of the distributing conveyor is located

3. A method according to Claim 2, wherein the tank is circular in plan, said feed conveyor extending from a fixed position outside of the tank to a central position therewithin, said distributing conveyor being located with its input end fixed at said central position to receive filter material from said feed conveyor, wherein said filter material is fed from the feed conveyor onto the distributing conveyor and discharged therefrom onto the tank floor progressively by the discharging device, and wherein the distributing conveyor is rotated progressively about its central input end to distribute filter medium uniformly around the tank floor.

4. A method according to Claim 3, wherein the discharging device is initially placed at an outermost position adjacent the tank wall and the distributing conveyor is rotated from a position adjacent the feed conveyor through substantially 360 degrees, the process then being repeated with the discharging device placed at a second adjustable position inwardly of the tank wall, the distributing conveyor being repeatedly rotated around the tank with the discharging device progressively indexed towards the centre thereof thus to introduce filter medium uniformly across the entire the floor of the tank before increasing the depth thereof whereby the load on the floor is evenly distributed and the material is uniformly compacted.

5. Apparatus for introducing loose filter medium into a tank to produce a filter bed, comprising at least one transportable distributing conveyor having an input end located at a position to receive filter medium, an output end movably supported on the tank wall, and a discharging device movable along the distributing conveyor for discharging filter medium therefrom at selected positions therealong onto the tank floor.

6. Apparatus according to Claim 5, wherein the tank is circular in plan and including at least one driven feed conveyor extending from a fixed position outside of the tank radially inwardly to a central position at which the input end of the distributing conveyor is rotatably mounted, the distributing conveyor extending radially with the output end thereof being supported on a movable carriage mounted on the tank wall.

7. Apparatus according to Claim 5 or Claim C, wherein said discharging device is adjustably mounted on the distributing conveyor and comprises a chute directed transversely and downwardly to one side thereof.

8. Apparatus according to Claim 7, including a series of ramping rollers which serve to carry a conveyor belt of the distributing conveyor upwardly to the Cop of the said discharging chute where it discharges onto the latter, the belt then passing around one or more further rollers and beneath the discharging device to proceed onwardly towards the output end of the distributing conveyor.

9. A method of introducing loose filter medium into a tank to produce a filter bed, substantially as hereinbefore described.

10. Apparatus for introducing loose filter medium into a tank to produce a filter bed, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.