AU593603B2 - Back flushable filters - Google Patents

Description

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i' PCT WORLD INTELLECTU OPI 0 NIZAION PT1 I on-ernza @re INTERNATIONAL APPLICATION PUBLISHED UNDER THE TT C E 3 ION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 87/ 03213 B01D 29/38, 35/12, 3522 A l (43) International Publication Date: 4 June 1987 (04.06.87) B01D 29/04, 29/08 (21) International Application Number: PCT/AU86/00354 KP, KR, LK, LU (European patent), MC, MG, MW, NL (European patent), NO, RO, SD, SE (European (22) International Filing Date: 21 November 1986 (21.11.86) patent), SU, US.

(31) Priority Application Number: PH 3513 Published With international search report, (32) Priority Date: 21 November 1985 (21.11.85) With amended claims.

(33) Priority Country: AU (71)(72) Applicant and Inventor: SNELLING, Peter, John [AU/AU]; Unit 1, 14 Cocos Grove, West Lakes, S.A.

5021 (AU).

(74) Agent: COLLISON CO.; 117 King William Street, Adelaide, S.A. 5000 3 98 (81) Designated States: AT (European patent), AU, BB, BE (European patent), BG, BR, CH (European patent), DE (European patent), DK, FI, FR (European pa- AU RAULAN tent), GB (European patent), HU, IT (European patent), JP, 1 JUL 1987 PATENT OFFICE (54) Title: BACK FLUSHABLE FILTERS Thib documeat contuins the (57) Abstract arnanAti gts m mad Sec.-en 49.

A back flushable filter which has number of separ- -1 able sections which can be separately accessed and there /2 Is Oa ter p L u %ag.

can be provided a flow pattern so that one of the sec- Ii tions is being back flushed while the other sections are providing normal filtering.

Valve means (11) providing j7 for such access can be inched around to select each section in turn. The filtering means can comprise sand or it can comprise a stack of separable segments which provide for inclined gaps between adjacent parts of each adjoining 1 I stack element with the conver- gence and gap size selected to i encourage compaction of par-' tices within the converging part of each gap but further selected such that on back flushing such compacted particles can be readily easily disgorged for total cleansing.

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i II 1 I: i -ii WO 87/03213 PCT/AU86/00354 BLACK FLUSHABLE FILTERS This invention relates to back flushable filters.

It is presently known to use.filters comprising siliceous particles such as sand in which water is filtered by being caused to pass through the compacted sand particles and from time to time, a cleansing of the sand is effected by causing water to flow in a contra direction hence causing the sand to rise against an otherwise compacted condition but being held against excessive removal by gravitational forces, but such that detritus, which will normally catch within water flow more effectively than sand particles, will be carried away by the so called back flushing water flow.

A number of problems do exist with such an arrangement In the connventional systems.

A first of these is that in order to effect an adequate back flushing, a sufficlent water flow capacity must be provided to ensure Is. that there is provided adequate flow to separate the detritus from the sand particles, There Is a further problem namely that in order to maintain sand within a filtering chamber a lowermost outlet is provided by a screen beneath which water will necessarily have to be provided for the back 21. flushing step.

In order to provide sufficient quantity of water for adequate velocity, it is conventional that such water should be provided from a main volume of water provided by perhaps a storage tank or swimming pool or like and on most occaislons, there is no assurance that such water is of itself clean.

The result In practice is that such water will have a primary filtering as it passes through the lowermost mesh so that this detritus will, when the water flow is reversed, be returned to the water storage.

2 This could perhaps be avoided by providing that a first shot of water subsequent to a back flushing step, should be directed to waste but this requires significant extra costs which can rarely be justified.

The further problem with present back flushing techniques is that because the veocities of water are inherently necessarily different, the capacity of pumps, pipes, and control valves must all be selected to allow for the back flushing capacity so that the cost is governed by a capacity which is necessarily far in excess of that which would normally be necessary for merely the filtering function.

I have discovered that the problems discussed can be at least significantly reduced by providing that the back fluphable filter has parts which are separately accessible, so that a part only can be selected for a back flushing action while other parts of the filter are accessible for a conventional filtering process.

20 The invention can be said then to reside in a back flushable filter comprising a substantially cylindrically shaped body, divided radially from a centre of S: the body into at least two filter parts, each of said parts having an upper access aperture and a lower access aperture, and particulate filter material within each of said parts; a rotary valve at an uppermost portion of said body, said rotary valve rotating within an area, a diameter of said areas being substantially 30 smaller than the width of the body of the filter, said rotary valve means o comprising an inlet chamber and a back flush chamber and in one position said Inlet chamber communicating between an inlet and at least one of said parts through at least one corresponding upper access apertures, said back flush chamber adapted to communicate between a further a'.

35 least one of said parts through a corresponding further access aperture; an outlet communication passage communk ating between all of the lower access apertures and a filter outlet so that when liquid is directed through :Tg D.

0 2a the inlet said liquid is filtered downwardly through each of said at least one parts communicating with said inlet chamber and through said filter outlet, a back flush is effected through each of said at least one parts communicating with said back flush chamber; said filter further including a drive means including a programmed motor and controller such that the rotary valve means can be stepped between the upper access apertures.

In preference, there are provided drive means adapted to drive said valve means, such that the valve means will be stepped through after a selected time from a first position to a second position whereby a back flushing effect is then effected in a further of the parts.

By having such separately accessible parts of a filter, there is a further significant advantage in that if a sufficiently large part of the filter is S° 20 provided for conventional filtering, a significant quantity of water is then available and a selected proportion of this can then be used S e r* 0.* S S 0 WO 87/03213 3 PCT/AU86/00354 as completely filtered water to provide for sufficient capacity to effect a back flushing of another part of the filter, Because the water Is being directly filtered and then provided from a lower end, there will be at most negligible detritus with the result that a significantly better filtering action can be expected, Furthermore, however, the total capacity of water being necessarily pumped at one stage Is governed then more by the capacity of the parts providing for conventional filtering and hence it can be expected that in commercial circumstances, a filter along the lines described can be made significantly more economically.

In preference, the back flushable filter is characterised in that the body Is of substantially cylindrical shape, with the parts of the filter being divided Into chambers by divisions radially extending from its axial centre, each chamber Including an upper access aperture and a lower access aperture, the valve means being adapted to direct through put of a selected chamber either In the case of back flushing, from the lower access aperture to the upper access aperture, or, in the case of effecting filtering from an upper access aperture through the chamber to a lower access aperture, It Is Inherent that a lower access aperture can be consituted by a plurality of apertures providing thereby a screen so that In the case that the filtering medium is sand or some fine particulate material, such will be retained from egress through any such aperture, Now that It becomes possible to provide for significant back flushing pressures and volumes at an economic price, It further becomes viable then to consider a filter medium of different type In which some of the particles which are Indeed the detritus can In fact be retained within a converging aperture, so as to provide of themselves the filtering effect but such thct these can e adequately dislodged with a back flushing even though such back flushing fll,w must be provided through the narrowest gap and be expected to dislodge significantly wedged particles.

e r WO 87/03213 4 PCT/AU86/0354 Accordingly as a further preferred form of this invention there is proposed that the above be now used in combination with a filter which Is comprised of a plurality of members located n an adjoining relationship to form a stack, and a plurality of filtering gaps being defined between adjacent edges of the adjoining members.

In preference, In respect of the stack there are communicating passage ways passing transversely through the stack so as to provide for an access conduit on one side of each gap and a disposal conduit on the other side of the gap.

I o. These and other features will be discernable by reference to the accompanying claims, and also by further reference to the description relating the preferred embodiment which shall now be described.

Referring to the several embodiments and the illustrations of these we note that:is. FIG. 1 is a cross-sectional view with part cut away parts illustrating a filter constructed according to a first embodiment, FIG, 2 is a perspective view of the filter of Fig. 1, with however, part cut away showing three separate chambers two of which are in a conventional filtering mode and a third of which is a back flushing mode, FIG, 3 is a cross-sectional view of a second embodiment incorporating a stack of filter elements, FIG. 4 Is a view from above of the same emodiment as in Fig. 3 with a top cover part removed, FIG. 5 Is in an enlargement of a part of the stack of filter elements Illustrating the arrangement for providing the filtering effect, and FIG. 6 is a -'an view of one of the elements constituted in the stack of filter parts in the second embodiment.

-i 1 I WO 87/03213 PCT/AU86/00354 Referring in detail to the drawings and particularly to the first embodiment as shown In Figs I and 2, there is a pressure sand filter which has a plurality of chambers 2 which are divided by dividers 3 which are fitted between an outer cylindrical container 4 and an inner upright conduit Each of the chambers 2 is characterised by having a lower access I aperture 6 and an upper access aperture 7.

The lower access aperture is connected to be accessible to a lower part of the central conduit 5 at 8 through a tube 9 which includes a number of straining slots The straining slots 10 are selected to provide resistance to passage of siliceous particles e.g. sand during the filtering mode, The upper access aperture 7 is adapted to be variously connected by means of rotary valve 1 1 so that one of the upper access apertures 7 is connected to conduit 12 which is directed to a disposal outlet while the remainder of the apertures 7 are connected through the upper part of the vertical conduit 5 at 13 whereby they are connected to inlet conduit 14 through which water can be directed which requires filtering.

The lower part of the vertical conduit 5 at 8 is connected to the outlet conduit 15 which is directed to provide passage for water that has been filtered, The position of rotary valve 11 is adapted to be controlled by motor 16 operating which operates through shaft 17 whereby to effect rotation of gear 18 which operates against corresponding gear teeth on the outer side of the cover 11 at i9.

The controls operating gear 16 are such that there Is a timer and a stepping function such that the rotary valve 11 is stepped through from a position corresponding as shown in Fig. I with a first upper access aperture 7 to a next poslton which is the next Lpper access aperture 7 In the adjacent vicinity so providing back flushing for a next adjacent chamber 2.

r WO 87/03213 PCT/AU86/q0354 In practice with this arrangement, each of the chambers 2 is loaded with sand so that the height of sand in a compacted state that is for conventional filtering will be approximately half the height of the respective chamber, and that the size of the sand particles is generally greater to the extent of the slots As can now be seen by setting the timing function, controlling the motor 16, the rotary valve I 1 can be variously positioned so as to provide for a back flushing effect for each of the chambers.

Of significance, however, Is that the extent of back flushing can be controlled in that all of the water being filtered is available for back flushing if necessary by control using valves variously in the conduit 12 and the conduit 15 in ttat if the conduit 12 is completely closed, all of the water being filtered will issue through conduit 15 while if the conduit 15 is closed all of the water will issue through conduit 12.

Of further signficance, however, is that the water being directed through the slots 10 when enterirg the back flushing mode chamber 2 is filtered.so that detritus will sirrply not be available to be collected on the tnsiide of the slots and hence available for return into the main body of water through conduit IS, The extent of water available and the extent of pumping capacity necessary can be calculated for various sized filters but it will now be found that adequate back flushing flow is available from very much smalle pumps than has hitherto been the case, providing significant total economic advantage.

2 Now referring to the second embodiment as described in Figs, 3,4,5 and 6, there is provided a substantially cylindrical container 20 which has within It a stack of filtering elements 21 which are each of annular shape as shown in Fig. 6 and each located one upon the other and held in this position by retaining ring 22 at the bottom and a top plate 23, At the bottom there is likewise a cover plate 24 of similar annular shape which has a plurality of aperture segments 25 passing WO 87/03213 7 PCT/AM 86/00354 At the bottom there Is likewise a cover plate 24 of similar annular snape which has a plurality of aperture segments 25 passing therethrough which are aligned with egress columns 26 within the stack 21.

The top cover plate 23 has a plurality of apertures 27 which are in turn aligned with the entry columns 28 within the stack 21, The drawing In Fig, 3 because of its small size only schematically shows these whereas the detail is shown in the enlarged cross-sectional view in Fig. 1o. To this extent therefore it is the detail of Fig. 5 that Illustrates the cross-sectional parts of the stack of filter elements.

Each of the filter elements is comprised of wedge shape sections in cross-section as is shown at 29, each of the elements 21 having a substantially identical cross-sectional shape so that each of the elements provides an inclined surface as at 30 and at 31 each of which has the same angle of inclination providing a planar surface aligned to a meeting edge at 32 such that there is provided then a symetrically aligned passage way of decreasing width from an entry end at passage way 28 to an exit end at passage way 26, The narrowest gap at 33, the degree of inclination provided by the respective adjoining parts and the full length of the entry into the apirture is chosen so as to ensure in respect of the particles which will be required to be filtered, that there will be a tr'pping and compacting of such particles so that the particles themselves provide substantially the effective filtering, Of importance, however, is that these factors are also chosen so that with the available water pressure in reverse, this will be sufficient to at least substantially remove such trapped particles such af$ is shown at 34 so that trapped detritus which would be blocking the frller could then be assuredly removed, PCT/AU86/Q354 f WO 87/03213 Such factors as the smoothness of the surface defining the gap, the material comprising a polypropelene plastic or otherwise which is used, and the comparitive gradient all contribute to the effectiveness of the technique described but It is important to realise that such criteria must be chosen with the particular particles and detritus that are to be involved, accordingly some experimentation is inevitably necessary but the illustration given especially in Fig. 5 presuming the sides are smooth the defining sides 30 and 31 in each case are of the proportionate length as shown and are planar along their length accordingly. In this preferred instance, the absolute value of the gap 33 is 0. 1mm, and the walls or surfaces 30 and 31 defining the gap have large distance apart of 0,8mm. The remaining measurements can be proportioned from the specific measurements, Now reverting the broader description of the filter as a whole, the container 20 further includes a rotary valve 35 the lower end of which at 36 is shaped so as to coincide with a segment shaped upper part of the stack and so as to engage with this to the extent that a reasonable water seal is effected especially wlth the entry passage ways 27.

The position of the rotary valve 35 is governed by motor 37 which in turn drives through shaft 38 onto cog 39 which engages gears The motor 37 is once again governed so that it has two controlling functions a first a timing period function and a second a stepping function so that It is adapted to be driven for a period of time on a cyclic basis with a further given period between such actions such that the rotary valve 35 will accurately coincide with an appropriate segment at 36.

Each of the elements in the stack 21 includes radial dividing elements 41 together with the cover plate 23 such that each passage way 27 and 26 are separated segment to segment so that coincidence of the rotary valve 35 with one of the said segments will allow separately isolated flow of water through the respective segment.

In this way, by appropriately coupling an inlet water supply into conduit 42, water can be then intially directed In direction of arrow 43 WO 87/03213 9 PCT/AU86/00354 whereupon the water will pass through the stack of filter elements 21 providing a filtering effect thereby.

A majority of the water can then be flushed out of outlet aperture in the direction of 44 while a proportion of the water can be directed by reason of controlling the respective openness or closedness of the respective conduits through the segment being connected through the rotary valve Such a portion is then directed in the direction 46 so as to pass to a sump through outlet 47, This then describes the second embodiment 1O. from which it will be seen that there can be provided a filter which in this case is not dependent upon being n y relative position to the ground to provide a filtering effect but which can be providing continuing back flushing with a sufficient head to provide back flushing effect which to a signflcant extent can be effected with cleansed water, A disadvantage of the second embodiment is the fact that it relies upon some gathering of particulate materials upon a filtering function being returned but in practice as this is a very small proportion of the total amount of water which will actually be passing through the filter and further that it can be expected such detritus and particles will very quickly gather within the constraining gaps, this can provide filtered water with sufficient speed so as the small amount of detritus that might pass can be In most cases Ignored.

Once again, however, the size of conduits, the capacity for pumping, and the total size of the filtering element all can be based on significantly smaller pressures and flow rates because of the concept of the invention.

It is self-evident that form time to time, the second embodiment article can be disassembled and completely cleansed If this is necessary by disassembling each of the filter elements from the stack, but it Is expected that with careful selection of the gap inclinations and with h ability to provide high pressure back flushing with even the smal pumping capacity will make such action now very rare.

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Claims (3)

1. A back flushable filter comprising a substantially cylindrically shaped body, divided radially from a centre of the body into at least two filter parts, each of said parts having an upper access aperture and a lower access aperture, and particulate filter material within each of said parts; 1 5 a rotary valve at an uppermost portion of said body, said rotary valve rotating within an area, a diameter of said areas being substantially smaller than the width of the body of the fi l'r, said rotary valve means comprising an inlet chamber and a back flush chamber S. 2 and in one position said inlet chamber communicating between an inlet 20 and at least one of said parts through at least one corresponding upper a access apertures, said back flush chamber adapted to communicate between a further at least one of said parts through a corresponding further access aperture; an outlet communication passage communicating between all of the lower access apertures and a filter outlet so that when liquid is directed through the inlet said liquid Is filtered downwardly through each of said at least one parts communicating with said inlet chamber 0 and through said filter outlet, a back flush is effected through each of 30 said at least one parts communicating with said back flush chamber; said filter further including a drive means including a programmed motor and controller such that the rotary valve means can be stepped between the upper access apertures. m A,1A 4 I *s1TI %ak -l*rc-rr.~irr~~ivl~~:ull*ju~~~ja~cc 11

2. The back flushable filter as in claim 1 including a blind perforated pipe extending from said lower access aperture into a lower portion of each of said parts, said pipe communicating at an open end with said aperture and communication with the part by means of perforations in said pipe.

3. A back flushable filter substantially described in the specification with reference to and as illustrated by FIG. 1 and 2 of the accompanying drawings. DATED this 28th day of November 1989. "00 S" PETER JOHN SNELLING 20 By his Patent Attorneys COLLISON CO. *000 04 J _11-