SE520264C2

SE520264C2 - Rotating disc liquid filtering means

Info

Publication number: SE520264C2
Application number: SE9603333A
Authority: SE
Inventors: Roger Haeffner
Original assignee: Nordic Water Prod Ab
Priority date: 1994-03-24
Filing date: 1996-09-13
Publication date: 2003-06-17
Also published as: SE9603333L; SE9603333D0

Abstract

The filter unit has filtering discs (4) arranged on a hollow shaft (3) with side walls forming a space for the liquid mixture to be filtered. A filtering means embraces the disc walls and periphery and a collecting vessel (10) inside the hollow shaft (3) collects the coarse phase solids (22). Carrier elements (13) rotating with the filter discs transport the solids phase (22) to collection vessel (10). Barrier elements (17) prevent the coarse solid phase (22) from sliding back into the liquid mixture as the filter disc rotates.

Description

520 264 industrin. 520 264 industry.

Uppfinningen, uppvisande de kännetecken som framgår av de bifogade patentkraven, kommer att beskrivas mer i detalj i det följande med hänvisning till de bifogade ritningarna, på vilka Fig. 1 visar ett tvärsnitt (I-I i fig. 2) av ett filter, Fig. 2 visar ett längdsnitt (II-II i fig. 1), Fig. 3 visar uppfinningen i en sektor av en filterskiva, Fig. 4 visar en alternativ utföringsform av uppfinningen, Fig. 5 visar, i en tvärsnittsvy, en sidoyta av en filterskiva (V-V i fig. 6), Fig. 6 visar, i en förstorad skala, en sektion (VI-VI i fig. 5) av sidoytan, Fig. 7 visar en alternativ utföringsform av uppfinningen, Fig. 8 visar en modifiering av utföringsformen i fig. 7.The invention, having the features which appear from the appended claims, will be described in more detail in the following with reference to the accompanying drawings, in which Fig. 1 shows a cross section (II in Fig. 2) of a filter, Fig. 2 Fig. 3 shows the longitudinal section (II-II in Fig. 1), Fig. 3 shows the invention in a sector of a filter disc, Fig. 4 shows an alternative embodiment of the invention, Fig. 5 shows, in a cross-sectional view, a side surface of a filter disc ( VV in Fig. 6), Fig. 6 shows, on an enlarged scale, a section (VI-VI in Fig. 5) of the side surface, Fig. 7 shows an alternative embodiment of the invention, Fig. 8 shows a modification of the embodiment in Fig. 7.

Figurerna 1 och 2 visar en principiell utföringsform av ett skivfilter. Detta omfattar en filterrotor l placerad i en fil- terbehållare 2 för filtratet. En ihålig axel 3, på vilken fil- terskivor 4 med filterorgan är anordnade roteras i behållaren med hjälp av ett drivorgan 5. Filterorganen i deras enklaste ut- förande utgöres av en filterduk fäst på ett stödjande underskikt så att ett inre utrymme 6 bildas. Filterduken omsluter båda sidor av filterskivorna och företrädesvis också den yttre peri- ferin 7. Filterskivornas innandöme kommunicerar med den ihåliga axel 3. Vätskeblandningen som skall filtreras införes i den ihåliga axeln genom inloppet 8 och därigenom också till filter- skivornas inre utrymme 6. Ett organ enligt känd teknik, icke visat, tillser att en väsentligen konstant nivå upprätthâlles i axeln och inuti filterskivorna. Ett fördelaktigt arrangemang för detta ändamål kan vara en automatisk hastighetsreglering så att, när nivån tenderar att stiga, hastigheten ökas och vice versa.Figures 1 and 2 show a basic embodiment of a disc filter. This comprises a filter rotor 1 placed in a filter container 2 for the filtrate. A hollow shaft 3, on which filter discs 4 with filter means are arranged, is rotated in the container by means of a drive means 5. The filter means in their simplest embodiment consist of a filter cloth attached to a supporting underlayer so that an inner space 6 is formed. The filter cloth encloses both sides of the filter discs and preferably also the outer periphery 7. The interior of the filter discs communicates with the hollow shaft 3. The liquid mixture to be filtered is introduced into the hollow shaft through the inlet 8 and thereby also to the inner space of the filter discs 6. A member according to the prior art, not shown, ensures that a substantially constant level is maintained in the shaft and inside the filter discs. An advantageous arrangement for this purpose can be an automatic speed control so that, when the level tends to rise, the speed is increased and vice versa.

Filtratet avlägsnas genom ett utlopp 9. Skillnaden mellan inlopps- och utloppsnivåerna är ett mått på det effektiva hydro- statiska trycket. Den avfiltrerade grovfasen skall i enlighet med uppfinningen överföras till ett uppsamlingskärl 10 inuti den ihåliga axeln. Botten av detta stationära uppsamlingskärl är snedställt mot ett utlopp ll för grovfasen. Sådan grovfas, vilken under rotationen av filtreringsorganet ännu inte fri- gjorts och fallit av från filterduken, när denna närmar sig en övre position, spolas bort med hjälp av spritsmunstycken 12 . u 1 ' .,)..:ø F, .,n - _ _ .V n ..; --»- "I ...., i- '3 ;. . « , » ; l» anordnade på utsidorna. Del av det påspritsade vattnet passerar därigenom genom filterduken och rengör denna, varigenom grov- fasen faller ned i uppsamlingskärlet 10.The filtrate is removed through an outlet 9. The difference between the inlet and outlet levels is a measure of the effective hydrostatic pressure. According to the invention, the filtered coarse phase is to be transferred to a collecting vessel 10 inside the hollow shaft. The bottom of this stationary collecting vessel is inclined towards an outlet 11 for the coarse phase. Such coarse phase, which during the rotation of the filtering means has not yet been released and fallen off the filter cloth, as it approaches an upper position, is washed away by means of spray nozzles 12. u 1 '.,) ..: ø F,., n - _ _ .V n ..; - »-" I ...., i- '3;.. «,»; L »arranged on the outside. Part of the sprayed water thereby passes through the filter cloth and cleans it, whereby the coarse phase falls into the collecting vessel 10. .

Fig. 3 visar i tvärsnitt en kvarts sektor av en filterskiva 4 i en utföringsform enligt uppfinningen. Utrymmet på insidan av filterskivorna har försetts med plattor, här kallade medbringar- element 13, utgående från den ihåliga axeln 3. De sträcker sig mot periferin och är anordnade mellan sidorna av filterskivorna i axiell riktning. Utsträckningen är sådan att ett gap 14, en öppning, kvarlämnas mot periferin. Avsikten med denna öppning är att under medbringarelementens förflyttning i vätskeblandningen, vätskeblandningen skall kunna strömma tillbaka motsatt rotatio- nen. En annan funktion som möjliggöres genom dessa gap är snabbt avlägsnande av luft från cellerna som bildas av medbringar- elementen, när dessa åter roterar ned i vätskebassängen liksom att snabbt tillföra luft under medbringarelementen, när dessa förflyttas upp över bassängytan. Medbringarelementen är oriente- rade på ett sådan sätt att de, under passagen av vätskenivån, upp och ut ur badet intar en väsentligen horisontell position.Fig. 3 shows in cross section a quartz sector of a filter disc 4 in an embodiment according to the invention. The space on the inside of the filter discs has been provided with plates, here called carrier elements 13, starting from the hollow shaft 3. They extend towards the periphery and are arranged between the sides of the filter discs in the axial direction. The extent is such that a gap 14, an opening, is left towards the periphery. The purpose of this opening is that during the movement of the carrier elements in the liquid mixture, the liquid mixture should be able to flow back opposite the rotation. Another function made possible by these gaps is the rapid removal of air from the cells formed by the carrier elements, when they rotate back down into the liquid pool, as well as the rapid supply of air under the carrier elements, when they are moved up over the pool surface. The carrier elements are oriented in such a way that, during the passage of the liquid level, they occupy a substantially horizontal position up and out of the bath.

En svag lutning nedåt mot gapet 14 underlättar ett återflöde av vätskeblandningen till bassängen vid passagen av vätskeytan, men denna lutning får inte vara så stor att någon grovfas som fallit ned också glider ned i bassängen. Vätskeblandningens nivå skall lämpligen hållas högre än rotationscentrum för att kunna uppnå en effektiv filteryta som är så stor som möjligt. Med- bringarelementen 13 kommer sålunda att vara så orienterade, att den inre änden därav som anligger mot axeln under rotationen kommer att leda i förhållande till den yttre änden.A slight slope downwards towards the gap 14 facilitates a reflux of the liquid mixture to the pool during the passage of the liquid surface, but this slope must not be so large that any coarse phase that has fallen down also slides down into the pool. The level of the liquid mixture should suitably be kept higher than the center of rotation in order to be able to achieve an effective filter surface which is as large as possible. The carrier elements 13 will thus be so oriented that the inner end thereof which abuts against the shaft during the rotation will lead in relation to the outer end.

I en föredragen utföringsform enligt uppfinningen är mellan varje par av medbringarelement 13 anordnade ett eller flera kortare, yttre medbringarelement 15 nära invid periferin. Däri- genom kan antalet större medbringarelement 13 hållas lågt.In a preferred embodiment according to the invention, between each pair of carrier elements 13, one or more shorter, outer carrier elements 15 are arranged close to the periphery. As a result, the number of larger carrier elements 13 can be kept low.

Vidare är dessa yttre medbringarelement 15 lämpligen anordnade på ett sådant sätt att de intar en väsentligen horisontell position med en svag lutning utåt vid passagen upp från vätske- bassängen. Vid periferin skall föreligga ett gap 16 också för dessa yttre medbringarelement för utflödet av icke filtrerad vätskeblandning respektive ett luftutsläpp.Furthermore, these outer carrier elements 15 are suitably arranged in such a way that they assume a substantially horizontal position with a slight inclination outwards at the passage up from the liquid pool. At the periphery there should be a gap 16 also for these outer carrier elements for the outflow of unfiltered liquid mixture and an air outlet, respectively.

Enligt föreliggande uppfinning skall det inte vara möjligt 520 264 J. L. för grovfas 22, som släppt filterorganet, att kunna falla till- baka i vätskeblandningen. Denna risk föreligger från den tid- punkt bladet kommit upp ut ur vätskebassängen tills det blir möjligt för grovfasen att glida ner i uppsamlingskärlet 10. För detta ändamål är blockeringsorgan anordnade, håri kallade barri- ärelement 17, så att grovfasen inte skall kunna glida av bladen vid rotationen innan de nått kanten av uppsamlingskärlet 10.According to the present invention, it should not be possible for coarse phase 22, which has released the filter means, to be able to fall back into the liquid mixture. This risk exists from the time the blade has emerged from the liquid basin until it becomes possible for the coarse phase to slide down into the collecting vessel 10. For this purpose, blocking means are provided, herein called barrier elements 17, so that the coarse phase cannot slide off the blades. upon rotation before reaching the edge of the collecting vessel 10.

Dessa barriärelement kan vara anordnade på den innersta delen av bladen och sträcka sig framåt i rotationsriktningen, d.v.s. de kan omfatta en uppåtriktad krök sett på den sida där filterski- van har en uppåtriktad rörelseriktning, i rotationsriktningen vid eller genom bladens inre ändar. Vinkeln för den uppåtriktade kröken skall vara så stor att den uppåtböjda delen, barriärele- mentet, vid rotationen passerar en horisontell position först efter passagen av uppsamlingskärlets kant, varpå grovfasen skall kunna glida ned i kärlet. Denna uppåtriktade krök med ungefär samma storlek som beskrivits ovan kan lämpligen också återfinnas på de yttre medbringarelementen vid periferin.These barrier elements can be arranged on the innermost part of the blades and extend forward in the direction of rotation, i.e. they may comprise an upward bend seen on the side where the filter disc has an upward direction of movement, in the direction of rotation at or through the inner ends of the blades. The angle of the upwardly directed bend must be so great that the upwardly bent part, the barrier element, during the rotation passes a horizontal position only after the passage of the collecting vessel edge, after which the coarse phase must be able to slide down into the vessel. This upwardly directed bend of approximately the same size as described above can suitably also be found on the outer carrier elements at the periphery.

Såsom framgår av fig. 4 kan barriärelementet för grovfasen 22 alternativt vara en platta 18, lämpligen fastsatt på uppsam- lingskärlet 10 eller utgöra en av kärlets väggar. Plattan sträc- ker sig i rotationsriktningen i en cirkulär båge från bassäng- ytan för vätskeblandningen upp till uppsamlingskärlets kant utmed alla filterskivorna. I motsats till barriärelementen på de ovan beskrivna medbringarelementen är denna platta ett statio- närt barriärelement 18. Detta barriärelement skall placeras så att medbringarelementets innerkant sveper tätt utmed barriär- elementet. Som en ytterligare säkerhet gentemot att eventuell grovfas kommer ned i vätskeblandningen genom gapet mellan det stationära barriärelementet 18 och medbringarelementen, kan också enligt denna utföringsform medbringarelementen vara ut- formade med de ovan beskrivna barriärelementen 17.As can be seen from Fig. 4, the barrier element for the coarse phase 22 may alternatively be a plate 18, suitably attached to the collecting vessel 10 or constitute one of the walls of the vessel. The plate extends in the direction of rotation in a circular arc from the basin surface of the liquid mixture up to the edge of the collecting vessel along all the filter discs. In contrast to the barrier elements on the carrier elements described above, this plate is a stationary barrier element 18. This barrier element must be placed so that the inner edge of the carrier element sweeps tightly along the barrier element. As an additional guarantee against any coarse phase entering the liquid mixture through the gap between the stationary barrier element 18 and the carrier elements, according to this embodiment the carrier elements can also be formed with the barrier elements 17 described above.

Såsom framgår av figurerna 5 och 6 kan i vissa applikationer medbringarelement 19 vara anordnade på sidorna av filterskivor- na, häri kallade sidomedbringarelement. Dessa ges med fördel en radiell utsträckning motsvarande filterorganets utsträckning i den radiella riktningen och kan t.ex. vara plattstänger eller ett galler. Dessa sidoplattor är så dimensionerade att de åt- minstone transporterar grovfas 22 som fallit ned från sidorna 520 264 5 till en sådan nivå att de efterföljande inre medbringarelementen (13 1 fig. 3) med sina barriärelement vid rotationen har tid att nå till över bassängytan för våtskeblandningen. Barriärelementen 17 åstadkommer sålunda att grovfasen, vilken vid rotationen efter denna position faller ned på bladen 13, transporteras upp till uppsamlingskärlet 10. Med fördel kan dessa sidomedbringar- element 19 vara anordnade att fungera som stödelement för fil- terorganet, vanligen filterduken.As can be seen from Figures 5 and 6, in certain applications carrier elements 19 may be arranged on the sides of the filter discs, hereinafter referred to as side carrier elements. These are advantageously given a radial extent corresponding to the extent of the filter member in the radial direction and can e.g. be flat bars or a grid. These side plates are dimensioned so that they at least transport coarse phase 22 which has fallen down from the sides 520 264 to such a level that the subsequent inner carrier elements (13 in Fig. 3) with their barrier elements during rotation have time to reach over the pool surface for the liquid mixture. The barrier elements 17 thus cause the coarse phase, which upon rotation after this position falls down on the blades 13, to be transported up to the collecting vessel 10. Advantageously, these side carrier elements 19 can be arranged to function as support elements for the filter means, usually the filter cloth.

Genom skapandet av barriärelementen uppnås ett större flöde av vätskeblandning genom gapet 14 (fig. 3) mellan medbringarele- mentet och periferin jämfört med vad som skulle vara fallet utan barriärelementen. Det har visat sig att detta förorsakar vissa störningar vid högre rotationshastigheter. Vätskeblandning som strömmar tillbaka genom gapet 14 har lossat filterskiktet, grovfasen, över en viss sträcka. Detta reducerar sedan både filterkapaciteten med avseende på mängden grovfas liksom filtra- tets renhet.By creating the barrier elements, a greater flow of liquid mixture is achieved through the gap 14 (Fig. 3) between the carrier element and the periphery compared to what would be the case without the barrier elements. It has been found that this causes certain disturbances at higher rotational speeds. Liquid mixture flowing back through the gap 14 has loosened the filter layer, the coarse phase, over a certain distance. This then reduces both the filter capacity with respect to the amount of coarse phase as well as the purity of the filter.

Detta problem löses såsom visas i figurerna 7 och 8, med ett skärmelement 20 radiellt utanför medbringarelementet 13 mot periferin. Denna skärm skall skydda grovfasskiktet 22 utanför medbringarelementet från vätskeströmmen genom att styra denna från periferin. Skärmen 20 kan ges en rak form såsom visades i fig. 7 eller kan den vara krökt. En fördelaktig utformning är en vinklad platta 21 (fig. 8), vilket ger bättre styrka och för- hindrar grovfas från att passera gapet. Denna utformning reduce- rar sålunda behovet eller antalet av yttre medbringarelement.This problem is solved as shown in Figures 7 and 8, with a screen element 20 radially outside the driver element 13 towards the periphery. This screen is to protect the coarse phase layer 22 outside the carrier element from the liquid stream by guiding it from the periphery. The screen 20 may be given a straight shape as shown in Fig. 7 or it may be curved. An advantageous design is an angled plate 21 (Fig. 8), which provides better strength and prevents coarse phase from passing the gap. This design thus reduces the need or number of external drive elements.

Det har visat sig att kombinationen av barriärelement och skärm- element utanför det inre medbringarelementet 13 har gjort det möjligt att köra filtren med en avsevärt högre rotationshastig- het. Detta innebär att filterenheterna för ett bestämt inkomman- de flöde av vätskeblandning kan reduceras väsentligt i storlek.It has been found that the combination of barrier elements and screen elements outside the inner driver element 13 has made it possible to run the filters at a considerably higher rotational speed. This means that the filter units for a certain incoming flow of liquid mixture can be significantly reduced in size.

Ett antal modifieringar inom ramen för uppfinningen kan göras. I vissa applikationer kan det ur ekonomisk synvinkel vara fördelaktigt att eliminera filterorganet som sträcker sig runt filterskivornas periferi. I dessa fall erfordras varken de yttre medbringarelementen 15 eller skärmelementen 20, 21.A number of modifications within the scope of the invention may be made. In some applications, from an economic point of view, it may be advantageous to eliminate the filter means extending around the periphery of the filter discs. In these cases, neither the outer carrier elements 15 nor the screen elements 20, 21 are required.

Claims

». «@, A 520 264 b.

A rotary disk filter for separating a coarse phase from a liquid mixture, comprising a hollow shaft (3), at least one vertical filter disk (4) arranged on the hollow shaft and forming a space delimited by a filter means on the sides of the filter disk, which space communicates with the hollow shaft, an inlet for supplying the liquid mixture to be separated into the hollow shaft and further into said space, a collecting vessel (10) in the hollow shaft for collecting a coarse phase developed in said space during the operation of the disc filter, and carrier elements (13) arranged on the filter disc (4) in said space for receiving coarse phase falling down from the filter means and for transporting said coarse phase to said collecting vessel during the rotation of the filter disc, each carrier element being elongate and having an inner end and an outer end relative to the filter disc , characterized by barrier elements (17), which are attached to the filter disc at the inner ends of the respective m conveyor element (13) to prevent coarse phase from falling from the carrier elements before the coarse phase has been transported to the collecting vessel (10).

Disc filter according to claim 1, characterized in that each barrier element (17) comprises a straight part extending forwards from its carrier element (13), seen in the direction of rotation, which straight part is positioned relative to the filter disc so that it extends horizontally when during the rotation of the filter disc it passes a position above the collecting vessel (10).

A rotating disk filter for separating a coarse phase from a liquid mixture, comprising a hollow shaft (3), at least one vertical filter disk (4) arranged on the hollow shaft and forming a space delimited by a filter means on the sides of the filter disk, which space communicates with the hollow shaft, a. = ... f 520 264 1 c inlet for supplying the liquid mixture to be separated into the hollow shaft and further into said space, a collecting vessel (10) in the hollow shaft for collecting a coarse phase developed in said space during operation of the disc filter, and carrier elements (13) arranged on the filter disc (4) in said space for receiving coarse phase falling down from the filter means and for transporting said coarse phase to said collecting vessel during rotation of the filter disc, characterized by a stationary barrier element ( 18) arranged on the collecting vessel (10) to prevent coarse phase from falling from the carrier elements before the coarse phase has been transported to u the collection vessel (10).

Disc filter according to claim 3, characterized in that the stationary barrier element (18) is designed as a circular arc extending downwards from the collecting vessel (10).

Disc filter according to one of Claims 1 to 4, characterized in that said space in the filter disc (4) is delimited by the filter member also on an outer periphery of the filter disc, and in that screen elements are arranged radially outside the carrier elements (13). (20; 21) for coarse phase deposited on the filter means on said outer periphery, which screen elements are arranged so that liquid flowing radially outwards along the carrier elements is deflected away from said outer periphery due to said screen element.

Disc filter according to any one of claims 1-5, characterized in that said space in the filter disc (4) is delimited by the filter means also on an outer periphery of the filter disc, and that between adjacent carrier elements (13) at least one outer carrier element (15) is located near said outer periphery and arranged to receive coarse phase falling from the filter means on said periphery and transfer received coarse phase to one of the carrier elements.

Disc filter according to claim 6, characterized by means for maintaining a substantially constant level of the liquid mixture in the hollow shaft (3) and in said space, said outer carrier element (15) extending substantially horizontally, when it moves upwards past said level during the rotation of the filter disc (4).

Disc filter according to any one of claims 1 to 7, characterized by means for maintaining a substantially constant level of the liquid mixture in the hollow shaft (3) and in said space, each of said carrier elements (13) extending substantially horizontally when it moves upwards past said level during the rotation of the filter disc (4).

Disc filter according to any one of claims 1 to 8, characterized in that a number of side carrier elements (19) are arranged on each side of the filter disc (4) in said space for receiving coarse phase falling from the filter means, each side carrier element extending axially from one side of the filter disc towards the other side of the filter disc but are spaced from said second side.

Disc filter according to Claim 9, characterized in that the filter means on the sides of the filter disc (4) are supported by the side driver elements (19).