IES70231B2

IES70231B2 - Improved method for cleaning a filter

Info

Publication number: IES70231B2
Authority: IE
Inventors: Barry I Fenton
Original assignee: At Patents Ltd
Priority date: 1996-05-27
Filing date: 1996-05-27
Publication date: 1996-11-13
Also published as: IES960371A2

Abstract

This invention relates to a method for cleaning a filter, in particular a filter used in the purification of water for municipal or industrial use, the filter having a base and a side wall extending therefrom, the filter in use containing a filtration medium comprising particulate material, the method including the step of providing a barrier means in the filter, the barrier means including a plurality of outlet pipes, the dimensions of which are such that the particulate material cannot pass therethrough.

Description

IMPROVED METHOD FOR CLEANING A FILTER This invention relates to an improved method for cleaning a filter. In particular, it relates to an improved method for cleaning a filter used in the removal of contaminating particles from fluids.

The conventional method used in removing contaminating particles from water for municipal or industrial use involves passing the water through a filter containing a filtration medium comprising particulate cleansing material which is usually sand. The filter itself is generally cleaned by flushing water therethrough in the direction from the filter base and simultaneously drawing air through the filter in the same direction. In this method the sand particles tend to be ejected over the backwash weir wall due to the creation of a vigorous air/water mixture. Consequently, the filtration medium requires continual replenishing with sand.

It is an objection of the invention to alleviate the above-mentioned problem.

According to the present invention there is provided a method for cleaning a filter having a base and a side wall extending therefrom, the filter in use containing a filtration medium comprising particulate material, the method including the step of providing a barrier means in the filter, the barrier means including a plurality of outlet pipes, the dimensions of which are such that the particulate material cannot pass therethrough.

The barrier means is preferably a baffle plate disposed on the side wall and extending downwardly therefrom in the direction of the base. The baffle plate may be integral with the side wall.

The baffle plate is preferably disposed at an angle of from about 30° to 60°, more preferably about 45°, relative to the side wall.

The outlet pipes of the baffle plate preferably have a diameter in the range of from about 10 to 100 mm, more preferably about 50 mm.

The particulate material is preferably sand, or anthracite.

The invention also provides an apparatus for carrying out the method of the invention, the apparatus comprising a filter having a base and a side wall extending therefrom, the filter in use containing a filtration medium comprising particulate material; and a barrier means disposed in the filter, the barrier means including a plurality of outlet pipes, the dimensions of which are such that the particulate material cannot pass therethrough.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawing which is a diagrammatic illustration of a filter used in carrying out the method of the invention.

The filter 10 comprises a porous base 11 and a side wall 12 extending substantially vertically therefrom. The side wall 12 is contiguous with a backwash weir wall 20. The filter 10 is suitable for use in the cleansing of large volumes of water intended for municipal or industrial use. A baffle plate 13 integral with the side wall 12 is disposed such that it extends downwardly therefrom in the direction of the filter base 11 at least mid-way across the width of the filter 10. The baffle plate 13 is disposed at an angle of about 45° relative to the side wall 12. It will be appreciated that the baffle plate 13 is not necessarily integral with the side wall 12, but may be mounted thereon by any suitable means.

The baffle plate 13 comprises a plurality of outlet pipes 14 (only one of which is shown) extending upwardly therefrom, their function being to allow the release of air therethrough. The pipes 14 have a diameter of approximately 50 mm.

In use, the filter 10 contains a filtration medium comprising particulate material 30 in the form of sand. Water to be purified is passed through the filter. Contaminants are absorbed by the sand and also lodge in the porous base 11. In order to clean the filter 10, water is washed therethrough in the direction from the base 11 and air is simultaneously drawn through the base in the same direction under pressure, so that a vigorous air/water mixture 40 is formed in the filter 10. As the air is drawn upwards, some sand particles 30 are also carried in the same direction. Air which collects below the baffle plate 13 during the combined air/water filter wash can escape through the outlet pipes 14. In effect, the baffle plate 13 acts to create a water surface adjacent to the backwash weir wall 20 from which the vigorous combined air/water mixture 40 is absent. The baffle plate 13 consequently reduces the tendency for the sand particles 30 to be ejected over the weir wall 20. Any sand particles 30 which are carried into the area above the baffle plate 13 will fall onto the baffle plate 13 and then slide therefrom and collect on the filter base 11.

The invention thus provides an improved method for cleaning a filter used in the purification of water for municipal or industrial use. The improved method serves to reduce the quantities of cleansing particulate material, such as sand, required in the water purification procedure. The apparatus used in the method of the invention is also relatively simple and inexpensive to construct.

The invention is not limited to the embodiment described herein which may be modified or varied without parting from the scope of the invention.

Claims

1. CLAIMS;

1. A method for cleaning a filter having a base and a side wall extending therefrom, the filter in use 5 containing a filtration medium comprising particulate material, the method including the step of providing a barrier means in the filter, the barrier means including a plurality of outlet pipes, the dimensions of which are such that the particulate material cannot 10 pass therethrough.

2. Apparatus for carrying out the method of claim 1, comprising a filter having a base and a side wall extending therefrom, the filter in use containing a 15. filtration medium comprising particulate material; and a barrier means disposed in the filter, the barrier means including a plurality of outlet pipes, the dimensions of which are such that the particulate material cannot pass therethrough.

3. A method according to claim 1 or apparatus according to claim 2, wherein the barrier means is a baffle plate disposed on the side wall and extending downwardly therefrom in the direction of the base; the 25 baffle plate optionally being integral with the side wall.

4. A method according to claim 1 or 2 or apparatus according to claim 1 or 2, wherein the baffle 30 plate is disposed at an angle of from about 30° to 60°, preferably about 45°, relative to the side wall, and/or the outlet pipes of the baffle plate have a diameter in the range of from 10 to 100 mm, preferably about 50 mm; and/or the particulate material is sand or anthracite.

5. A method according to claim 1 or apparatus according to claim 2, substantially as herein described with reference to the accompanying drawing.