|Publication number||US20080099413 A1|
|Application number||US 11/971,733|
|Publication date||1 May 2008|
|Filing date||9 Jan 2008|
|Priority date||18 Oct 2001|
|Also published as||DE60222685D1, DE60222685T2, EP1436060A1, EP1436060B1, US7341662, US20050035071, WO2003033099A1|
|Publication number||11971733, 971733, US 2008/0099413 A1, US 2008/099413 A1, US 20080099413 A1, US 20080099413A1, US 2008099413 A1, US 2008099413A1, US-A1-20080099413, US-A1-2008099413, US2008/0099413A1, US2008/099413A1, US20080099413 A1, US20080099413A1, US2008099413 A1, US2008099413A1|
|Inventors||Derek Tolley, Asheley Tolly|
|Original Assignee||Tolley Derek C, Tolly Asheley D|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (1), Classifications (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a divisional of U.S. application Ser. No. 10/492,823, filed on Sep. 27, 2004, which is a 371 of PCT/GB02/04705, filed on Oct. 15, 2002, which claims priority from GB 0125141.2, filed Oct. 18, 2001, all of which are hereby incorporated herein by reference in their entireties.
1. Field of the Invention
The present invention relates to filtration of liquid media and particularly to filtration of water or the like.
2. State of the Art
Filtration apparatus is known for filtering water. Such apparatus typically comprises a vessel pressurised with water having an inlet, a bed of filter media (typically one or more layers of graded sand or other particulate material), and an outlet drain arrangement for directing off the filtered water. In order to periodically clean the filter media a cleaning backwash is forced through the drain arrangement (typically causing fluidisation of the bed of filter media) and the backwashed liquid is drawn off to waste above the level of the bed of filter media.
An improved technique and system has now been devised.
According to a first aspect, the invention provides filtration apparatus including:
It is preferred that the inlet arrangement comprises liquid directing means arranged to direct pressurised liquid along a tangential or circumferential path with respect to an axis of the vessel. Beneficially, the liquid directing means is arranged to direct the pressurised liquid entering the vessel at an acute angle downwardly.
Beneficially, the inlet arrangement is provided closely adjacent the upper internal surface of the vessel, which upper internal surface of the vessel is beneficially inclined or concave from an upper point to lower portions proximate the periphery of the vessel. This aids in promoting the rotating flow.
Typically the unfiltered water is pressurised in the vessel above the level of the filtration media (which is typically present as a bed laying in the vessel). The inlet arrangement is designed to induce a flow pattern within the vessel to maximise the flow length from the inlet arrangement to the liquid/filter media interface. Creating a rotation from stimulus at the inlet arrangement zone in the liquid space above the filter media provides a body or bulk rotation of the liquid media about the axis of the vessel and ensures:
In Northern Hemisphere environments the rotation is to be induced in a clockwise direction, whereas in Southern Hemisphere locations anticlockwise rotation is necessary. The reason for the different direction of rotation preferred is due to the coriolis force caused by the earth's rotation. Taking advantage of the coriolis force leads to preferred rotation in different directions in Northern and Southern Hemispheres.
The inlet arrangement preferably comprises a plurality of radially extending duct arms, each including outlet means (typically apertures) to direct pressurised unfiltered liquid transversely to the radial direction. The duct arms are configured to direct the outlet liquid either substantially in a clockwise sense or in an anticlockwise sense (dependant upon the geographical location of the filter vessel either in the Northern or Southern Hemisphere).
Beneficially, the radial duct arms are regularly spaced about an axis, preferably connected to a central or hub plenum inlet chamber. Beneficially the radial duct arm outlet apertures, direct the pressurised liquid at an acute angle outwardly and downwardly from the inlet arrangement within the vessel.
Beneficially the outlet apertures are guarded by filter or mesh means to inhibit filter media or other detritus passing back through the inlet arrangement during the backwash cycle.
It is preferred that the drain arrangement includes a plurality of radially extending limbs, each preferably including apertures, slots or other liquid passage means to act as backwash liquid distribution means in backwash mode or filtered liquid collection means in normal ‘filter mode’. The backwash liquid distribution means (apertures etc) is beneficially configured to distribute backwash liquid in a direction transverse to the longitudinal direction of the respective limbs. Beneficially the backwash outlet means of limbs in the drain arrangement is configured such that in backwash mode the majority (or all) of the limbs direct water in either a clockwise sense or alternatively an anticlockwise sense (depending again upon the geographical location of the filter vessel in either the Northern or Southern Hemisphere).
The backwash outlet means of the radial limbs of the drain arrangement also serve to collect the filtered liquid (in filter mode) having passed through the body of filter media.
The drain arrangement is preferably positioned toward the interior base of the vessel. Beneficially the interior base of the vessel is inclined, concave or dish shaped, the radial limbs of the drain arrangement extending from a lower most end at a radial central zone of the vessel to an upper end raised from the lower end and radially spaced from the centre of the vessel. The radial limbs are therefore effectively inclined, and preferably connect with a radially central drain chamber. Because the limbs are inclined, draining of the filtered liquid into the drain chamber is improved. The limbs can extend at the lowest possible point in the vessel with respect to the inclined, concave or dish shaped interior bottom surface of the vessel. Prior art arrangements have had non-radially configured limbs of a drain arrangement extending substantially horizontally.
Beneficially the apertures providing the backwash outlet or filter media inlet to the drain arrangement are provided over the majority of the length of the radial limb. Slots or the like may be provided at spaced intervals along the length of the limb to achieve this. Beneficially the apertures are provided with filter or mesh guard means to inhibit filter media entering the drain arrangement.
In backwash mode high flow rates are used to ensure efficient backwash cycle without loss of filter media. The purpose of the backwash cycle is to attempt to remove detritus from the body of filter media, including inhibiting the risk of growth of pathogen colonies within the media. This reduces deterioration of the filter performance. This in turn aids in extending the life of the filter media. High flow rates are preferred in the backwash cycle in order to provide a short and efficient backwash cycle reducing the water volume used and further minimising running costs.
According to a further aspect, the invention provides a method of filtering liquid media, the method comprising directing liquid to be filtered into a vessel under pressure, the vessel including a bed of filter media and a drain arrangement for take-off of filtered liquid media from the filtration vessel, wherein liquid present in the vessel above the bed of filter media is caused to undergo rotating flow about the vessel and/or wherein in backwash mode liquid is forced through the filter media effecting rotating flow and fluidisation of the filter media.
The invention will now be further described in specific embodiments by way of example only with reference to the accompanying drawings in which:
Referring to the drawings, and initially to
The vessel 2 has a concave internal bottom 5 upon which rests a bed of filter media 6 extending upwardly to approximately half the depth of the vessel 2. Filter media typically comprises a body of particulate materials such as filter sand which may be single-grade or multi-grade depending upon the precise application of the filter. Activated charcoal/carbon or other particulate material may also be utilised. Liquid (water) to be filtered is directed under pressure into the vessel 2 via inlet arrangement 3 such that the pressurised head volume 8 of liquid is present above the surface 7 of filter media bed 6 in head space 8.
An important aspect of the invention is the ability of the inlet arrangement 3 to direct pressurised unfiltered inlet liquid such that upon entry into the head space 8 bulk rotation of liquid in head space 8 is created about the central axis of the vessel 2. Such an effect enables a situation approaching hydraulic balance to be achieved at the liquid/filter media interface providing even flow through the filter bed, minimising eddy currents and avoiding tunnelling into the filter media.
In order to achieve this the liquid inlet comprises a filter head 10 having a plurality of regularly spaced radial arms 11 extending outwardly from a central plenum 12. Central plenum 12 includes perforations permitting unfiltered liquid media to enter directly into head space 8, although a large proportion of the liquid entering is directed via arms 11 as will be described hereafter.
Arms 11 communicate with plenum 12 and are generally tubular in cross-section (as shown most clearly in
The drain arrangement 4 (shown most clearly in
Referring now to
By mounting the drain limbs directly in sand filter media (rather than typical prior art mounting in gravel on a concrete base) the backwash fluidisation and rotation of the sand filter bed is achieved. This arrangement is believed to be novel and inventive per se.
The present invention provides improvements in relation to performance of filter apparatus by improving the inlet distribution of liquid to be filtered into a filter vessel and also the drain outlet and backwash capability and efficiency.
There have been described and illustrated herein several embodiments of a filtration apparatus and corresponding method of operation. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8012359 *||31 Mar 2004||6 Sep 2011||Kcc Group Limited||Filtration apparatus|
|International Classification||B01D24/14, B01D24/46|