EP0635309B1 - Double pusher centrifuge - Google Patents

Description

The invention relates to a double-push centrifuge a rotating screen drum to separate from Mixture in liquid and solid content in the form of To make filter cake with a centrally arranged Moving floor device, which extends along the axis of the Sieve drum reciprocates around the filter cake alternately with an outer ring area push away, and with a central feed unit, to feed new mixture into empty spaces, which are behind the returning outer ring area arise.

Double push centrifuges have the advantage that during the Ejection movement that the moving floor device into a Direction to eject the filter cake on the On the back of the moving floor there is an empty space on the sieve drum arises in the fresh mixture for filtration can be fed. With correct reversal of the Feed with mixture on the opposite side of the Moving floor equipment can be fed in continuously will. For example, EP 0 068 095 shows double push centrifuges with a central through hole on the Moving floor device, its edge as a control edge is used to inevitably depending on the Position the moving floor of the mixture from a stationary radial feed to the front or back to switch. There is a friction disc on both sides the actual moving floor connected to one to form a rotating annulus in which the mixture for Screen drum is accelerated. It is essential that the two drum halves in front and behind equal amounts of solids are applied to the moving floor will. The axial position of the radial feed must therefore be adjusted precisely, the position experimentally about measuring the two Solid streams must be searched. At wearing products can be long-term Changes in the geometry of the inlet pipe too uneven distribution. Be further Fluctuations in the amount of food as an uneven distribution passed on. In theory, such Quantity fluctuations due to increased throttling on Reduce the radial feed outlet. On the one hand the necessary inlet height for such throttling to be present and on the other hand is at reduced Outlet opening the risk of backflow and blockage available.

The object of the invention is the distribution of mixture to simplify in double push centrifuges. This task is solved in that on both sides in the outer Ring area of the moving floor device several axial Passages are attached, each of the Center via associated radial feed openings are feedable within the moving floor device and which divert the mixture on both sides in the axial direction, to counter the ejection movement of the Moving floor device towards that side of the drum on which the moving floor of the filter cake is currently runs away.

The invention has the advantage that the axial distribution of the mixture directly in the pressure field on the surface the sieve drum through the axial openings takes place by the radially entering mixture according to the different from the filter cake limited outlets on the side, that runs away from the filter cake. The state of the Filter cake on the moving floor therefore inevitably controls the Distribution of the mixture, while by the individual radial feeding of several axial Through openings ensure that the mixture the same in the openings Has peripheral speeds and pressures. The radial Feed openings branch off from an annular space, which despite its axial movement from the central Feed unit can be easily supplied with a mixture. A breakthrough in the axis of the Moving floor equipment can only be used for Passage of rinsing and washing liquid used if, for example, a support tube is the central one Feed device penetrates and to the rear area has a deflector. This creates a simple one non-clogging infeed system and more space for one Product washing on the back of the drum. It offers itself there is enough space for you with the moving floor moving but to this axially adjustable ring channel, the rinsing and washing liquid to the filter cake distracts and accelerates.

To effectively eject the filter cake axially and nevertheless via axial through openings in the moving floor to feed, annular gap sections and Alternate dividers. Depending on the design of the common annulus, of which the radial Branch openings can branch off, the axial Through openings in the outer ring area of the Moving floor can be designed quite differently. At a double-walled moving floor, the two walls of which the Form common annulus, spiked can be used be a distribution on the axial Make openings. If the axial Through openings to the periphery are open, then the intermediate webs must be kept wider by one same ejection effect on the filter cake as an outer one Ring surface with a closed circumferential band to reach. On the one hand, the ejection effect on To make filter cake adaptable and on the other hand the axial outlet height for the mixture of the axial Through openings opposite the inner surface the sieve drum are adjustable Wear rings can be attached in the outer ring area.

Another way to create a double wall Moving floor consists of the actual moving floor axial through holes and their radial Milling feed openings in the form of channels, whereby a cover that is attached later covers the channels and at the same time forms this common annulus. Such milled channels have the advantage, that they are opposite the center of an annular gap section Direction of rotation can be advanced to the axial Passage opening more evenly over their share of Apply volume to mixture.

Fig. 1

schematisch einen Längsschnitt durch eine Doppelschubzentrifuge;

Fig. 2

schematisch die Ansicht einer Schubbodeneinrichtung mit axialen Durchtrittsöffnungen und radialen Anspeiseöffnungen in Form von Taschen;

Fig. 3

schematisch einen Längsschnitt durch eine Schubbodeneinrichtung entsprechend Fig. 2, bei der ein Deckel zur Bildung eines Ringraums und zur Abdeckung der Taschen vorgesehen ist;

Fig. 4

einen vergrösserten Ausschnitt des eigentlichen Schubbodens aus Fig. 3 an seiner Peripherie zur Siebtrommel;

Fig. 5

schematisch die Ansicht einer doppelwandigen Schubbodeneinrichtung, die ein Abschlussband zur Siebtrommel aufweist;

Fig. 6

schematisch einen Längsschnitt durch eine Schubbodeneinrichtung entsprechend Fig. 5 mit einem axial verschiebbaren Ringkanal zum Auffangen und Verteilen von Waschflüssigkeit;

Fig. 7

schematisch die Ansicht einer doppelwandigen Schubbodeneinrichtung, deren axiale Durchtrittsöffnungen zur Siebtrommel hin offen sind;

Fig. 8

schematisch einen Längsschnitt durch eine Schubbodeneinrichtung entsprechend Fig. 7; und

Fig. 9

einen Ausschnitt eines eigentlichen Schubbodens entsprechend Fig. 4, bei dem Verschleissringe eingesetzt sind.

In the following, the invention is explained on the basis of exemplary embodiments. Show it:

Fig. 1

schematically shows a longitudinal section through a double-shear centrifuge;

Fig. 2

schematically the view of a moving floor device with axial passage openings and radial feed openings in the form of pockets;

Fig. 3

schematically shows a longitudinal section through a moving floor device according to Figure 2, in which a lid is provided to form an annular space and to cover the pockets.

Fig. 4

an enlarged section of the actual moving floor of Figure 3 on its periphery to the screening drum.

Fig. 5

schematically the view of a double-walled moving floor device, which has an end band to the screening drum;

Fig. 6

schematically shows a longitudinal section through a moving floor device according to FIG 5 with an axially displaceable annular channel for collecting and distributing washing liquid.

Fig. 7

schematically the view of a double-walled moving floor device, the axial passage openings are open to the screening drum;

Fig. 8

schematically shows a longitudinal section through a moving floor device according to FIG. 7; and

Fig. 9

a section of an actual moving floor according to FIG. 4, in which wear rings are used.

In the figures there are double-shear centrifuges with one rotating screen drum shown separating from a mixture in liquid and in solids in the Make the form of filter cake. A centrally located Sliding floor that reciprocates along the axis of a sieve drum moves, pushes alternately with its outer Ring area since the last release of the Filter cake attached to the outside of the drum area path. The moving floor points at the level of the filter cake several axial openings, each over associated radial feed openings with mixture be supplied. The redirection in the axial Through openings are inevitable according to the Resistance at the outlet, on the ejecting side compared to the upcoming filter cake, while on the opposite side, a space behind the running moving floor is created in which the mixture can flow in. The distribution is inevitable due to the high peripheral speed in the Through openings there is enough pressure to create nuances in the balance on both sides.

In FIG. 1, a screening drum 6 is on one side via bearings 24 stored in a housing 1, which in a middle Area that was centrifuged with the sieve drum 6 Intercepts liquid 39 in a filtrate housing 4 while the filter cake 14, 15 from an axially oscillating Moving floor device 5 each along the Drum shell surface to the outside in a corresponding Solid housing 3 are pushed. On the warehouse side are several outlet openings 22 for the rear Filter cake 14 attached in the sieve drum. The Moving floor device 5 itself is via bolts 26 and one Thrust hub 25 connected to a piston rod 23, the in turn in the axis 9 of the sieve drum axially is movably mounted to rotate with the Sieve drum 6 an axially oscillating movement make the actual moving floor at his Periphery is transferred to the filter cake 14, 15. The housing 1 is closed with a housing cover 2. A feed unit 11 is in shape on the housing cover a pipe for a mixture 17 attached, which coaxially from a support tube 20 at its outlet is pierced, the support tube having a deflector 33 carries, which deflects the mixture 17 in the radial direction. The Support tube 20 is reached through a central opening 34 in the moving floor device 5 the rear room Sieve drum 6 and allows one or more internal pipes 19, washing and / or washing liquid 21 in the back room.

In Figures 2, 3 and 4 is an embodiment of the Moving floor device 5 can be seen in the by one an annular space 18 on the front cover 29 A plurality of radial feed openings 13 is produced merge into axial passage openings 12, which in an outer ring area 10 of Moving floor device 5 in the area of the filter cake 14, 15 are arranged. During the back and forth movement of the Moving floor device 5 becomes mixture 17 in the area between the front edge of the lid and the actual one Moving floor introduced radially and further via the friction accelerated on the walls in an annular space 18 in which Baffles in the form of pockets 28 are attached to the Mix in pockets 28 to peripheral speed bring. Are between the lid 29 and the pockets 28 the radial feed openings 13 are cut out the mixture 17 in each case in axial passage openings 12 arrives, which the front and rear space of the Connect sieve drum 6. The sieve drum consists of its Shell surface from a sieve 7, which is from a open support cylinder 8 is held. The mixture 17 tries axially and in both directions Circumferential direction at the exit from the passage openings 12 distribute, being on the side towards the Ejection movement 27 of the to be extended Filter cake 14 opposes while on the opposite side, an empty space 16 is formed in the the mixture 17 for separation from the liquid portion can flow in. After the reversal of movement the now settled solid content with the subsequent filter cake by not quite a stroke length ejected, while on the back solid content is deposited.

4 shows axial passage openings 12, which occupy an entire annular gap section 30 in order to in the circumferential direction a good level compensation for the To reach filter cake 14, 15. There are pockets 28 offset in the direction of rotation 32 to a more uniform Influence in the annular gap cross section 30 to effect. Of the Lid 29 is supported in the actual moving floor a puncture 31 with one shoulder, the same time in the area of the pockets 28 there is a limitation for the radial ones Feed openings 13 forms. In the area of the axial Passage openings 12 are annular on both sides Punctures attached in the corresponding to FIG. 9 Wear rings 38 can be used.

In Figures 5 and 6 is a double-walled Moving floor device 5 shown as a welded construction, in which the feed unit 11, the mixture 17 in the Feeds in the middle of a hollow moving floor. The two Sidewalls are on their periphery about one End tape 35 connected. The axial Passage openings 12 are separated from one another by spikers 36 separately, the spit 36 simultaneously the radial Form feed openings 13 from the annular space 18. On the Bolt 26 is a funnel-shaped ring channel 37 for Washing liquid 21a in different axial positions fixable to the in the rear space of the drum 6 Tube 19 and the support tube 20 introduced washing liquid to collect and distribute. About an additional, in in the axial direction further protruding tube 19 Rinsing liquid 21b in the rear space of the sieve drum 6 be given up to remove the filter cake 14 and to clean the screen surface 7.

In Figures 7 and 8 is a welded construction shown analogously to Figures 5 and 6, in which the outer Graduation tape was left out. The axial Through openings 12 are open towards the sieve, so that care must be taken to ensure that the distance between two spits 36 is small enough to eject one to obtain a continuous ring shape of the filter cake 14, 15.

Figure 9 shows a section of the moving floor 5 with put on wear rings 38. With the Wear rings can wear from the Through openings 12 are kept away. It is also possible, the axial outlet height the product properties adapt. The lock ring can be made as a whole or made of several radially displaceable segments be. The can be designed as movable segments radial overflow height can be adjusted continuously.

Claims (10)

1. A double sliding centrifuge having a rotating screening drum (6) for performing a separation of mixture (17) into liquid (39) and solids content (40) in the form of filter cakes (14, 15), having a centrally disposed sliding floor device (5), which moves to and fro along the axis (9) of the screening drum (6), in order to push the filter cakes (14, 15) away alternately with an outer annular region (10), and having a central feed unit (11) for feeding new mixture (17) into empty spaces (16), which are produced behind the returning outer annular region (10),
   characterised in that several axial through-apertures (12) are mounted on both sides in the outer annular region (10) of the sliding floor device (5), which can be fed from the centre via associated radial feed apertures (13) inside the sliding floor device (5) and which divert the mixture (17) on both sides in the axial direction in order to convey it contrary to the ejection motion of the sliding floor device (5) on that drum side on which the sliding floor presently moves away from the filter cake.
2. A double sliding centrifuge according to Claim 1,
   characterised in that the radial feed apertures (13) inside the sliding floor device (5) branch from a common annular space (18), which can be supplied with mixture (17) from the central feed unit (11).
3. A double sliding centrifuge according to Claim 1 or 2,
   characterised in that in the centre the sliding floor device (5) comprises an opening (34) for a fixed supporting pipe (20), in which at least one axially displaceable pipe (19) allows the introduction of washing and/or rinsing liquid.
4. A double sliding centrifuge according to Claim 3,
   characterised in that the supporting pipe (20) penetrates the central feed device (11) and comprises at least one deflector (33) for mixture (17) at the opening (34) inside the sliding floor device.
5. A double sliding centrifuge according to one of Claims 1 to 4,
   characterised in that the through-apertures (12) in the outer annular region (10) have the form of ring slot portions (30).
6. A double sliding centrifuge according to one of Claims 2 to 5,
   characterised in that the annular space (18) is formed from a double-walled sliding floor device (5).
7. A double sliding centrifuge according to Claim 6,
   characterised in that the sliding floor device (5) in the outer annular region (10) is constructed with double walls and with an end strip (35).
8. A double sliding centrifuge according to one of Claims 2 to 5,
   characterised in that the annular space (18) is formed by a cover placed in the sliding floor device (5).
9. A double sliding centrifuge according to one of Claims 1 to 8,
   characterised in that wearing rings (38) can be mounted in the outer annular region (10), with which the axial outlet height from the axial through-apertures (12) can be adjusted in relation to the inner surface of the screening drum.
10. A double sliding centrifuge according to one of Claims 1 to 9,
    characterised in that parallel to the sliding floor device (5) there is an axially displaceable annular channel (37) for collecting and distributing washing liquid (21a).

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