EP1468742A1 - Multi-stage pusher-typ centrifuge - Google Patents

Abstract

The multistage thrust centrifuge includes a rotatable sieving drum (6) to separate a mixture (2) into a solid cake (3) and a liquid phase (4), at least one sieving stage (7) installed inside the sieving drum, and a mixture distributor (8) installed in the sieving drum and equipped with a thrust base device (9) which has a pre-acceleration funnel (12) designed as a pre-acceleration sieve. The pre-acceleration funnel conically widens by a constant angle in the direction of the feed component (10).

Description

The invention relates to a multi-stage pusher centrifuge according to the preamble of independent claim 1.

For drying moist substances or moist substance mixtures Centrifuges in a variety of embodiments are widely used and become used in various fields. So come for example to Drying of high purity pharmaceutical discontinuous products Centrifuges, such as peeler centrifuges, are preferred for use, in particular then, when continuously separating large quantities of a solid-liquid mixture to be used, continuously operating pusher centrifuges advantageous become. Depending on the requirement, one or more stages are involved Pusher centrifuges, as well as so-called double-thrust centrifuges used.

For the different types of the latter class of pusher centrifuges becomes a solid-liquid mixture, for example a suspension or a moist salt or salt mixture, through an inlet pipe via a mixture distributor one quickly rotating drum, which is designed as a filter, fed, so that on reason the centrifugal forces exerted the liquid phase through the filter screen is deposited while inside the drum wall, a solid cake becomes. In this case, in the rotating drum is a substantially disc-shaped, synchronously arranged with rotating moving floor, depending on the number of Sieve either the sliding floor or a sieve in the axial direction in the Drum oscillates with a certain amplitude, leaving part of the dried Solid cake is pushed out at one end of the drum. In the opposite movement of the moving floor becomes one to the moving floor adjacent area of the drum released, which then through the inlet pipe and can be fed again with a new mixture over the mixture manifold. there depending on the type used with modern high-performance pusher centrifuges Easily throughputs of the order of 100 tons per hour can be achieved, with drum diameter up to 1000 mm and more thoroughly are common and typical rotational frequencies of the drum, depending on Drum diameter of up to 2000 revolutions per minute and more achieved can be. This usually requires a larger drum diameter because of the strong centrifugal forces occurring a smaller maximum Rotation frequency of the drum. Of course, the operating parameters, such as. the rotational frequency of the drum, the amount supplied per unit time Mixture or the drum diameter or the type of used Pusher centrifuge also of the material to be dried itself, the content of Depend on liquid etc.

The multi-stage pusher centrifuges known from the prior art are in usually continuous filter centrifuges. The multi-stage filter centrifuge consists of an outer sieve drum and at least one in the outer Screening drum arranged screening stage, which is also designed as a screening drum. In this case, a plurality of screening stages can be arranged concentrically in one another, so that two, three and multi-stage pusher centrifuges are feasible, with all screening stages be driven very quickly synchronously about a common axis of rotation. One too separating solid-liquid mixture passes continuously in the operating state Fixed inlet pipe arranged in a in the innermost screening stage, also synchronously with rotating, mixture distributor and is on the innermost Sieve level evenly distributed over the entire screen circumference. Most of the Liquid is already centrifuged off here and it forms a solid cake.

For example, in a two-stage pusher centrifuge, the innermost stage, which is also referred to as the first stage, in addition to the rotation movement around the Rotary axis of an oscillatory motion in the direction of the axis of rotation. These Oscillatory motion is, for example, hydraulically via a thrust piston Reversing mechanism generated. As a result, the solid cake is in Ring sections, corresponding to the stroke length of the oscillation, from the first to pushed second stage and leaves the pusher centrifuge finally over a Outlet. In practice, the solid cake is in the sieve drum continuously with the addition of washing liquid on the solid cake washed.

A well-known two-stage pusher centrifuge, after the previously described Principle operates, is described in detail, for example, in DT 25 42 916 A1. In the case of two-stage and multi-stage pusher centrifuges, the first stage, i. the innerst sieve essentially for the pre-dewatering of the mixture, as well as for Formation of a solids cake, while the outer screen drum mainly as Drying stage is used. The fact that by means of the first screening stage a pre-drainage is possible, with multi-stage pusher centrifuges a significantly increased Liquid absorption capacity is reached, so that mixtures with lower Inlet concentrations, i. be processed with higher liquid content can.

For special applications special versions of two-stage and multi-stage are available Pusher centrifuges, in particular for highly abrasive products, such as e.g. coal and rock phosphate, the special anti-wear measures, such as wear-resistant sieves, require. Also special designs for intensive Washing processes and for carrying out special washing procedures, such as For example, the countercurrent washing in nitrocellulose, are from the prior Technique known. Also gas-tight versions of multi-stage pusher centrifuges for Operation under protective gas atmosphere are used.

Although multi-stage pusher centrifuges for a long time, as briefly sketched above, also for Special applications are well known in various embodiments, However, the known multi-stage pusher centrifuges still different serious disadvantages. Even if with the known multilevel Pusher centrifuges lower inlet concentrations, i. Mixtures with elevated Liquid content can be processed better than with ordinary Single-stage pusher centrifuges, the inlet concentration of the processed Mixture not be arbitrarily small. That is, when the proportion of liquid in the mixture too high, for example 50% or 70% or 80% or even more than 90% Liquid phase amounts, the mixture must be in more or less expensive Procedure be pre-thickened. If the liquid content is too high, namely uniform distribution of the mixture to be dried over the circumference of the Screen drum increasingly difficult. On the one hand, that can be too damaging Vibrations of the drum and thus premature wear of bearings and Drive drive; in the worst case even a safety problem in the enterprise become. On the other hand causes a non-uniform over the circumference of the screen drum distributed solids cake Problems washing. Therefore, stand to Pre-dewatering, for example, static thickeners, curved sieves or the best known hydrocyclones available. It is obvious that the use Such Vorentwässerungssysteme both procedural and apparatus very expensive and therefore expensive.

Another serious disadvantage when processing mixtures smaller Inlet concentration is that practically the entire amount of liquid, which is supplied with the mixture to the full peripheral speed must be accelerated before passing through the filter screen of the sieve drum is excreted. The same applies to the smallest particles in the mixture, the should also be separated from the solids cake by the sieve. This is energetically extremely unfavorable and influences the operating behavior of the centrifuge clearly negative.

But even with the processing of mixtures with significantly higher Solid concentration show the known from the prior art centrifuges sometimes massive disadvantages. So that is through the inlet pipe in the Mixture introduced mixture when hitting the screen drum in accelerated to the full peripheral speed of the drum in no time. Especially with sensitive substances, this can lead to grain breakage lead, that is, for example, solid grains in one of the centrifuge fed suspension in the abrupt acceleration process in Uncontrolled way burst into smaller pieces, causing negative influences on the Quality of the produced solid cake may have, if for example the Particle size of the grains in the final product plays a role.

The object of the invention is therefore an improved multi-stage To propose pusher centrifuge, which are known from the prior art Disadvantages largely avoided.

The objects of the invention solving these objects are characterized by the features of independent claim 1.

The respective dependent claims relate to particularly advantageous Embodiments of the invention.

Thus, according to the invention, a multistage pusher centrifuge is used to separate a Mixture proposed in a solid cake and in a liquid phase. there The multi-stage pusher centrifuge comprises an outer rotatable about a rotation axis Screening drum and at least one arranged in the outer screen drum Siebstufe, arranged in the screen drum mixture distributor with a Sliding floor device, either the screening stage or the Sliding bottom device is arranged back and forth along the axis of rotation, so that the solids cake is displaceable by means of the pusher bottom device. Furthermore, the multistage pusher centrifuge comprises a feed device which the mixture can be introduced into a void via the mixture distributor, when moving the solids cake by the push floor device arises, wherein the push floor device has a pre-acceleration funnel comprising, essentially widening towards the feed device extends and the pre-acceleration funnel as Vorbeschleunigungssieb is designed.

Characterized in that the inventive multi-stage pusher centrifuge on the Moving bottom device arranged Vorbeschleunigungssieb has not the total amount of liquid phase contained in the feed mixture the full peripheral speed of the screen drum can be accelerated as a part the liquid phase already deposited over the pre-acceleration screen and off the screen drum is removable. Thus, mixtures are also very high Liquid content easily processable. In particular, so is synonymous with high Liquid content always a uniform distribution of the mixture to be dried ensured over the peripheral surface of the screening stage or the screening drum.

In addition, by running as Vorbeschleunigungssieb Pre-acceleration hopper prevents a through the feed device in the mixture distributor introduced mixture immediately, essentially only below the influence of gravity and without pre-acceleration on the inner Peripheral surface of the screening stage passes. Rather, the incoming mixture slowed down to the peripheral speed of the screening drum accelerated, whereby in particular grain breakage and other damaging influences, like those at abrupt acceleration in the multi-stage known from the prior art Pusher centrifuges occur, are preventable. Thus, by the inventive multi-stage pusher centrifuge a bursting of the mixture contained solid grains avoidable, because the acceleration process on the predeterminable pre-acceleration angle of the pre-acceleration funnel is controllable, i. that the acceleration itself is by an appropriate choice the Vorbeschleunigungswinkel the Vorbeschleunigungstrichters adjustable. Thereby Can the quality of the produced solid cake, especially for products at which, for example, the particle size or the shape of the grains in the final product play a role, be significantly increased.

The essential components as well as the basic functioning of a Multi-stage pusher centrifuges are known from the prior art, so that in The following priority with reference to the features essential to the invention reference can be.

The multi-stage pusher centrifuge according to the invention serves to separate one Mixture in a solid cake and in a liquid phase and comprises as essential components one about an axis of rotation about a drum axis rotatable outer screen drum, which is housed in a housing. The Drum axis is operatively connected to a drum drive, so that the Drum through the drum drive in rapid rotation around the axis of rotation is displaceable. Inside the outer screen drum is at least one screening stage arranged. Furthermore, in the sieve drum is a mixture distributor with a Moving floor device provided, either the screening stage or the Sliding bottom device is arranged back and forth along the axis of rotation, so that the solids cake is displaceable by means of the pusher bottom device. Both the outer screen drum and the screen stage have screen openings on, in a known manner with rapid rotation liquid phase from the Solid cake or of a mixture which on an inner peripheral surface of Can be applied level, by the centrifugal forces occurring externally discharged is. In particular, in a particularly important example in practice the Screening drum and / or the screening stage in a conventional manner as a skeletal Support drum to be designed to form the corresponding screen surfaces with special filter sheets are lined at their periphery, i. the skeletal Support drum can, for example, with one or more filter screens with different or equal sized filter openings for the deposition of Liquid phase be configured.

Inside the sieve drum is the mixture distributor with the push floor device arranged, which allows it to be continuously fed through the feeding device supplied mixture on the inner peripheral surface of the screening stage by introducing into the white space that has arisen when moving the solids cake to to distribute. In this case, the sliding floor device comprises a Pre-acceleration funnel, according to the invention as Vorbeschleunigungssieb is configured, wherein the pre-acceleration is substantially expanding extending toward the feeding device. At a peripheral area is while the Vorbeschleunigungstrichters formed as a ring area that with the Ring area of the deposited in the screening stage solid cake by an oscillation the push floor device or the screening stage in the sieve drum or in a further sieve level is displaceable.

The mixture distributor is preferably in a conventional manner Fastener coupled to the drum and therefore rotates in one special embodiment synchronous with the screen drum and the screening stage to the common axis of rotation. The oscillatory motion leads, depending on the number the existing screening levels, either the screening level itself or the Push floor device off. Thus, there is an oscillatory in the operating state Relative movement between the screening stage and the sliding floor device with Pre-acceleration. The drive of the oscillatory movement takes place preferably via a push rod, wherein in a first half-period of oscillatory movement with the outer ring area at the screening stage deposited solid cake in ring sections whose width is determined by the stroke length of the Oscillation movement is determined, from the screening stage to the screening drum or to a another screening stage is pushed, and in a second half-period the oscillatory movement deposited on the outer edge of the drum Ring section of solid cake is pushed out of the sieve drum. During the second half-period of the oscillatory motion arises at the same time a void on the outer ring area in the screening stage, so that in the White space new mixture can be introduced.

It is essential for the multi-stage pusher centrifuge according to the invention that part of the liquid phase already in Vorbeschleunigungssieb from the mixture is separable and the mixture in Vorbeschleunigungssieb to a predeterminable Rotation speed is vorbeschleunigbar, so that by the Feed introduced mixture before reaching the peripheral surface of the Sieve level can be accelerated to a predetermined peripheral speed. Thereby On the one hand, it does not have to contain the entire amount of liquid phase contained in the mixture is to be accelerated to the full peripheral speed of the screen drum, so that even mixtures with a very high liquid content easily processable are. In particular, even at very high concentrations of liquid phase in the Mixture additional pre-drainage facilities, such as static Thickeners, curved sieves or hydrocyclones superfluous.

On the other hand, is characterized in that the pre-acceleration funnel with respect to the Rotary axis has an opening angle which is smaller than 90 °, in Pre-acceleration funnel the flow velocity of the mixture compared to Speed in free fall targeted towards the peripheral surface of the screening stage adjustable so that the mixture in the region of the pre-acceleration funnel with increasing approach to the outer ring area both in the radial direction, and gradually gradable in the circumferential direction of the screen drum. The means that the mixture in the area of the pre-acceleration funnel becomes particularly gentle way gradually to a predetermined peripheral speed accelerates around then on reaching the peripheral surface finally the full To achieve rotation speed of the screening stage.

In this case, both an inlet funnel, whose function further down still extend will be explained in detail, as well as the pre-acceleration funnel in one predeterminable range preferably under a substantially constant Opening angle or conical under a constant pre-acceleration angle expanding towards the push floor device or to the feed device out.

For special applications, for example, depending on the properties of the mixture to be dehydrated, the inlet funnel and / or the Vorbeschleunigung funnel in a predetermined range but also one have curved course, wherein the opening angle of the inlet funnel and / or the pre-acceleration angle of the pre-acceleration hopper in the direction enlarged or reduced to the sliding floor device. That can in particular be advantageous if the inlet funnel or the pre-acceleration funnel, as will be described in more detail later, as a prefilter screen or as Pre-acceleration screen is designed for the pre-separation of liquid phase.

In a specific embodiment, the pre-acceleration screen is as Two-stage filter with a coarse filter and a fine filter designed. The mixture can thus be filtered in two stages in the area of the pre-acceleration screen become. The design of the Vorbeschleunigungssiebs as a two-stage filter has in particular the advantage that the fine filter by large and / or heavy Particles that are contained in the incoming mixture, mechanically not so strong is loaded, so that the fine filter, for example, very small pores for filtering of very small particles and in particular also of mechanical can be made of less resistant materials.

In practice, it is of particular advantage if the mixture distributor a Collecting device is provided for discharging liquid phase, so that a part the liquid phase already before reaching the enormously fast rotating peripheral surface of the Sieve level is removable. This part of the liquid phase is then no longer accelerated to the full peripheral speed of the screening stage, resulting in a massive energy saving and relieving the components, in particular the rotating and / or oscillating components of multi-stage pusher centrifuge leads. As a result, even mixtures with enormously high Liquid content easily processable.

In a further embodiment of the inventive multistage Pusher centrifuge is the pre-acceleration screen configured and arranged that the Vorbeschleunigungssieb by means of a rotary drive to a Rotary axis with a predetermined speed, regardless of the speed of the Screen drum, is rotatable. Preferably, for controlling and / or regulating the Rotary speed of the rotary drive suitable means, for example in the form of computerized electronic systems to provide the rotary drive, for example, depending on suitable operating parameters of the multi-stage Pusher centrifuge to control and / or to regulate.

In another preferred embodiment of an inventive Multi-stage pusher centrifuge is in addition to the feed Inlet hopper for pre-acceleration of the incoming mixture provided. The Mixture passes through the feed initially in an inlet funnel, the preferred in one embodiment, but not necessary, rotatably with the Mixture is connected, so that the inlet funnel synchronously with the Mixture distributor rotates. In this case, the inlet funnel extends substantially extending axially to the pre-acceleration screen, so that through the Feed mixture fed directly into the inlet funnel. there the inlet funnel is designed and arranged so that the mixture during Leaving the inlet funnel is fed into the Vorbeschleunigungssieb.

Due to the arrangement and design of the inlet funnel, the mixture is already in the feed hopper pre-accelerated to a predetermined rotational speed, so that the mixture already has a certain amount when it reaches the pre-acceleration screen Speed in the circumferential direction of the screening stage and so still total gentler on the maximum peripheral speed of the peripheral surface of Sieve level is accelerated.

Preferably, the inlet funnel can also be used as a prefilter screen for pre-separation be formed of liquid phase from the mixture. It is preferred Collecting agent for collection and discharge of separated from prefilter screen Liquid phase provided.

In this case, a value of an opening angle of the inlet funnel and / or the value a pre-acceleration angle of the pre-acceleration funnel with respect to Rotary axis, for example, between 0 ° and 45 °, in particular between 0 ° and 10 ° or between 10 ° and 45 °, in particular between 25 ° and 45 °, preferably between 15 ° and 35 °. Of course, it is also possible that the Value of the opening angle and / or the pre-acceleration angle greater than 45 ° is. In general, it can be stated that usually in terms of Rotary axis is a rather acute angle of advantage, with an optimal value of the corresponding opening angle and / or the pre-acceleration angle below the value of a static friction angle of the product to be dewatered is.

In particular, but not only when the inlet funnel as a pre-filter for Pre-separation of liquid phase is formed, it may be of particular advantage be when the inlet funnel has a curved course and the Opening angle of the inlet funnel in the direction of the sliding floor device out enlarged or reduced. It is known that different products under otherwise identical operating conditions of the pusher centrifuge, for example in Dependence on the particle size and / or the viscosity and / or other Properties or parameters, such as the temperature of the mixture Different drainage are good.

For example, if there is a mixture that is relative to given operating parameters is easy to drain, it may be advantageous that the inlet funnel or the Prefilter filter has a curved course, wherein the opening angle of the Prefilter increased in the direction of the sliding floor device towards. That means, the Inlet funnel or the prefilter sieve expands towards the Moving floor device similar to the horn of a trumpet. This will be the Stripping force, with which the mixture is accelerated from the inlet funnel, with decreasing distance to the moving floor device disproportionately larger, so that the mixture, which is already relatively strongly drainable in the prefilter sieve and so that poor sliding properties in the prefilter shows faster, the prefilter sieve leave as, for example, in a substantially conical, with constant opening angle expanding prefilter screen.

On the other hand, there may be mixtures which, given Operating parameters are relatively difficult to drain. In this case, it recommends itself, an inlet funnel or a prefilter sieve with a curved course use, wherein the opening angle of the prefilter screen in the direction of Moving bottom device down. This has the consequence that the output force, with the mixture from the inlet funnel is accelerated, with decreasing Distance to the walking floor device increases more slowly than, for example, at one conically at a substantially constant opening angle expanding inlet funnel. This creates a pre-acceleration screen certain congestion, so that the mixture remains longer in the prefilter sieve and therefore already in the prefilter is dewatered to a higher degree.

Quite analogous to the previously said, of course, the Vorbeschleunigung funnel have a curved course, wherein the Pre-acceleration angle of the pre-acceleration funnel in the direction of Infeed device enlarged or reduced.

The previously explained in connection with the curved inlet funnel Advantages and its mode of operation are without problems analogously to those skilled in the art a curved Vorbeschleunigungsstrichter transferable, and must therefore here not be repeated.

In addition, in a special embodiment, the prefilter sieve Of course as a two-stage sieve with a coarse sieve and a fine sieve be designed. The advantages are apparent. The first filter stage forms the Grobsieb, which contained in the mixture particles that are larger than that Retains filter openings of the coarse filter. The fine sieve keeps correspondingly finer Particles back, while at least part of the liquid phase, as well as very small Particles that also need to be removed are directly dischargeable from the screening stage are. The configuration of the prefilter screen as a two-stage screen has in particular the Advantage that the fine sieve by large and / or heavy particles, in the incoming mixture are included, is not mechanically stressed so much, so that the fine filter, for example, very small pores for filtering very small Particles may have and especially from mechanically little resistant materials can be made.

In particular, in a particularly important for practice embodiment the inlet funnel and / or the pre-acceleration funnel as skeletal Be configured supporting body, for forming the prefilter and / or the Vorbeschleunigungssiebs may be equipped with special filter films, i. of the skeletal support body can, for example, with one or more filter screens, the possibly for the deposition in different stages of different sizes Filter openings may be equipped.

In the process, filter sieves, among others, are used as filter sieves or For example, screen plates in question. The filter screens can be advantageous different way provided with filter openings of different sizes become. In particular, the aforementioned screen plates can, inter alia punched, drilled, lasered, electron beam punched or water jet cut In principle, other techniques come into question. The sieves themselves Depending on the requirements, you can choose from different, in particular corrosion resistant materials, such as plastic, Composite materials or different steels such as 1.4462, 1.4539 or 2.4602 or made of other suitable materials. To protect against In addition, the filter screens can wear with suitable layers be provided, for example, with hard chrome layers, tungsten carbide (WC), Ceramics or hardened differently. The strength of the filter sheets is typically 0.2 mm to 5 mm, although significantly different sheet thicknesses possible are.

In practice, it can be of great importance to accelerate itself or the rotational speed to which the mixture in the inlet funnel is accelerated, purposefully to control. Therefore, the inlet funnel can by a Drive shaft arranged rotatably and by means of a drive with a predeterminable Speed to be rotatable about the drive axis. For control and / or regulation the rotational speed of the inlet funnel this is for example with a separate drive shaft rotatably connected and via the drive axle by means of a drive independent of the screening drum and / or independent of Vorbeschleunigungssieb with a predetermined rotational frequency drivable. there can, as described above when driving the pre-acceleration screen, suitable means may be provided to drive, for example, depending of the mixture to be processed, certain operating parameters of the multi-stage Pusher centrifuge, etc. to control and / or regulate. This can be the inventive multi-stage pusher centrifuge and corresponding sensors for Measurement of relevant operating parameters include.

It goes without saying that the characteristics of the previously exemplary described particularly preferred embodiments of the according to the invention, also multi-stage pusher centrifuge can be combined in any advantageous manner.

Fig. 1

im Schnitt eine mehrstufige Schubzentrifuge mit Vorbeschleunigungssieb;

Fig. 2

ein weiteres Ausführungsbeispiel gemäss Fig. 1 mit Zweistufenfilter;

Fig. 3

ein anderes Ausführungsbeispiel gemäss Fig. 1 mit Auffangeinrichtung zum Abführen von Flüssigphase;

Fig. 4

eine mehrstufige Schubzentrifuge mit separat antreibbarem Vorbeschleunigungstrichter;

Fig. 5

eine mehrstufige Schubzentrifuge mit Einlauftrichter;

Fig. 5a

ein Ausführungsbeispiel eines Vorbeschleunigungstrichters;

Fig. 5b

ein weiteres Ausführungsbeispiel eines Vorbeschleunigungstrichters;

Fig. 5c

einen Einlauftrichter mit gekrümmtem Verlauf;

Fig. 5d

einen anderen Einlauftrichter gemäss Fig. 5c;

Fig. 6

ein Ausführungsbeispiel gemäss Fig. 5 mit Vorfiltersieb;

Fig. 6a

ein zweites Ausführungsbeispiel gemäss Fig. 6 mit rotierbarem Vorbeschleunigungssieb;

Fig. 6b

ein zweites Ausführungsbeispiel gemäss Fig. 6a mit Blindboden;

Fig. 7

ein zweites Ausführungsbeispiel gemäss Fig. 6 mit Grobsieb und Feinsieb;

Fig. 8

einen Einlauftrichter mit Drehantrieb.

The invention will be explained in more detail below with reference to the schematic drawing. Show it:

Fig. 1

on average, a multi-stage pusher centrifuge with pre-acceleration screen;

Fig. 2

a further embodiment of Figure 1 with two-stage filter.

Fig. 3

another embodiment of Figure 1 with collecting means for discharging liquid phase.

Fig. 4

a multi-stage pusher centrifuge with separately drivable pre-acceleration funnel;

Fig. 5

a multi-stage pusher centrifuge with inlet funnel;

Fig. 5a

an embodiment of a pre-acceleration funnel;

Fig. 5b

a further embodiment of a pre-acceleration funnel;

Fig. 5c

an inlet funnel with a curved course;

Fig. 5d

another inlet funnel according to FIG. 5c;

Fig. 6

an embodiment according to Figure 5 with prefilter.

Fig. 6a

a second embodiment of FIG. 6 with rotatable pre-acceleration screen;

Fig. 6b

a second embodiment according to FIG 6a with a blind floor.

Fig. 7

a second embodiment of FIG. 6 with coarse filter and fine sieve;

Fig. 8

an inlet funnel with rotary drive.

Fig. 1 shows in section in a schematic representation essential components a first embodiment of an inventive multi-stage Pusher centrifuge with pre-acceleration screen. It is in the drawings of For reasons of clarity, these applications are only examples two-stage pusher centrifuges shown schematically. It is understood that the Representation of two-stage pusher centrifuges is exemplary to understand and the Description, of course, also for more than two-stage pusher centrifuges in analogous manner applies and is transferable accordingly.

The inventive multi-stage pusher centrifuge, which in the following total designated by the reference numeral 1, serves to separate a mixture 2 in a solid cake 3 and into a liquid phase 4 and comprises as essential Components one about a rotational axis 5 about a drum axis 51 rotatable outer screen drum 6, which is housed in a housing G. The Drum axis 51 is connected to a drum drive 52 in operative connection, so that the Screen drum 6 through the drum drive 52 in rapid rotation about the axis of rotation 5 is displaceable. Within the outer screen drum 6 is at least one screening stage 7 arranged. Furthermore, in the screening drum 6, a mixture distributor 8 with a Sliding floor device 9 is provided, wherein either the screening stage 7 or the Push floor device 9 along the axis of rotation 5 back and forth is arranged, so that the solid cake 3 by means of the moving floor device. 9 is displaceable. Both the outer screen drum 6 and the screening stage 7 have while screen openings 61, 71, by the known manner with rapid rotation Liquid phase 4 from the solid cake 3 or from a mixture 2, which, as further is described in more detail below, on an inner peripheral surface 72 of the Siebstufe 7 can be applied, due to the centrifugal forces discharged to the outside is.

Within the screening drum 6, the mixture distributor 8 with push floor device 9 arranged, which allows continuously through the feed device 10th supplied mixture 2 on the inner peripheral surface 72 of the screening stage 7 through Introducing into a void 11, which is the displacement of the solid cake. 3 originated, to distribute. In this case, the sliding floor device 9 comprises a Pre-acceleration funnel 12, which is configured as a pre-acceleration screen 12, wherein the Vorbeschleunigungssieb 12 is substantially conically widening in Direction extends to the feed device 10 back. At a peripheral area is In this case, the pre-acceleration funnel 12 is designed as an annular region 92 such that with the ring portion 92 of deposited in the screening stage 7 solid cake 3 by an oscillation of the pusher bottom device 9 described in more detail below and / or the screening stage 7 in the screening drum 6 or in another not here illustrated screening stage 7 is displaceable.

It is essential for the multistage pusher centrifuge 1 according to the invention, that already a part of the liquid phase 4 in Vorbeschleunigungssieb 12 from Mixture 2 is separable and the mixture 2 in Vorbeschleunigungssieb 12 to a predetermined rotational speed is vorbeschleunigbar.

The mixture distributor 8 is in the embodiment shown in Fig. 1 with the screen drum 6 rigidly coupled by fastening means 91 and therefore rotates synchronously with the screen drum 6 and the screening stage 7 about the axis of rotation 5. Die oscillatory motion, indicated by the double arrow in FIG. 1, performs in the example shown here, however, only the screening stage 7th Thus, in the Operating state an oscillatory relative movement between the oscillating Sieve stage 7 and the immovable in the axial direction moving floor device 9 with Pre-acceleration funnel 12. The oscillatory movement of the screening stage 7 takes place preferably via a push rod 21, wherein in a first half-period of oscillatory motion with an outer ring area 92 of the screening stage 7 deposited solid cake 3 in ring sections whose width by the stroke length the oscillation movement of the screening stage 7 is determined, from the screening stage 7 to Moving drum 6 is pushed, and in a second half-period of the oscillatory Movement through the screening stage 7 on the outer edge of the screening drum. 6 Deposited ring section of solid cake 3 from the screening drum. 6 is pushed out. During the second half-period of the oscillatory At the same time movement creates the empty space 11 in the sieve stage 7, so that in the White space 11 new mixture can be introduced.

It is essential for the multistage pusher centrifuge 1 according to the invention, that already part of the liquid phase 4 in the pre-acceleration hopper 12 from Mixture 2 is separable and the mixture 2 in the pre-acceleration funnel 12 on a predeterminable rotational speed is vorbeschleunigbar, so that the of the feed device 10 introduced mixture 2 before reaching the screening stage. 7 can be accelerated to a predetermined peripheral speed. This must be done on the one hand not the entire amount of liquid phase 4, which contained in the mixture 2 is to be accelerated to the full peripheral speed of the screening drum 6, since a part of the liquid phase 4 already on the pre-acceleration screen 12th deposited and directly through the screen openings 61, 71 of screening drum. 6 is separable. Thus, mixtures 2 with a very high content of Liquid phase 4 easy to process. In particular, so is also at high content on liquid phase 4 always a uniform distribution of the mixture to be dried 2 over the peripheral surface 72 of the screening stage 7 and the screening drum 6 guaranteed. In particular, even at very high concentrations of liquid phase 4 im Mixture 2 additional pre-drainage facilities, such as static thickeners, curved screens or hydrocyclones superfluous. It also can smallest in the mixture 2 contained Patrikel by the effect of pre-filtration much be separated more effectively from the solid cake 3.

In addition, characterized in that the pre-acceleration screen 12 a Pre-acceleration angle β, which is smaller than 90 °, im Vorbeschleunigungssieb 12, the flow rate of the mixture 2 in comparison to the speed in free fall towards the peripheral surface 72 of the screening stage 7 selectively adjustable, so that the mixture 2 in the range of Vorbeschleunigungstrichters 12 with increasing approach to the outer Ring portion 92 in both the radial direction and in the circumferential direction of the Screen drum 6 is gradable gradually. That is, the mixture 2 is in Area of Vorbeschleunigungssiebs 12 in a particularly gentle way to and accelerated to a predetermined peripheral speed, then at Reaching the peripheral surface 72 finally the full rotational speed of Level 7 to reach.

The value of the pre-acceleration angle β of the pre-acceleration funnel 12, and the value of an opening angle α of a later to be described Einlauftrichters 16 may be in relation to the axis of rotation 5, for example, between 0 ° and 45 °, in particular between 0 ° and 10 ° or between 10 ° and 45 °, in particular between 25 ° and 45 °, preferably between 15 ° and 35 °. Of course, it is also possible that the value of the Opening angle α and / or the pre-acceleration angle β is greater than 45 °.

In general, it can be stated that usually in terms of Rotary axis 5 is a rather acute angle of advantage, with an optimal value of the corresponding opening angle α and / or the pre-acceleration angle β among other things, the value of the static friction angle of the mixture 2 to be dehydrated is determined.

Characterized in that the mixture 2, unlike those of the prior art known multi-stage pusher centrifuges, in the field of Vorbeschleutingungssiebs 12 is not abrupt, i. in the shortest possible time to the full rotational speed of the Level 7 is accelerated, for example, are broken grain and other harmful Effects on the mixture 2 preventable. This is in the inventive multi-stage pusher centrifuge 1, in particular also mechanically very sensitive substances, even at high rotational speeds the screen drum 6 processable.

In Fig. 2, a further embodiment according to FIG. 1 is shown, wherein the Vorbeschleunigungssieb 12 as a two-stage filter with a coarse filter 121 and a Fine filter 122 is configured. The mixture 2 can thereby in the range of Vorbeschleunigungssiebs 12 are filtered in two stages. The first filter stage forms the coarse filter 121, which contained in the mixture particles that are larger as the filter openings of the coarse filter 121 holds back, so in the void 11th can be introduced. The fine filter 122 retains correspondingly finer particles that also the white space 11 and thus the solid cake 3 are fed, while at least part of the liquid phase 4, as well as very small particles, the must also be removed, directly through a sieve opening 61, 71 from the Screen drum 6 are discharged. The embodiment of the pre-acceleration screen 12 As a two-stage filter has the particular advantage that the fine filter 122 by large and / or heavy particles which may be contained in the incoming mixture 2, is mechanically not so heavily loaded, so that the fine filter 122, for example can have very small pores for filtering very small particles and especially made of mechanically less resistant materials can be.

In practice, it is of particular advantage if, as in Fig. 3 schematically represented, at the mixture manifold 8, a collecting device 13 for discharging Liquid phase 4 is provided, so that a part of the liquid phase 4 already before Reaching the very fast rotating peripheral surface 72 of the screening stage 7 out of the Sieve level 7 is removable. This part of the liquid phase 4 is no longer on accelerates the full peripheral speed of the seventh stage 7, resulting in a massive energy saving and relieving the components, in particular the rotating and / or oscillating components of multistage pusher centrifuge 1 leads. As a result, even mixtures 2 with enormous high proportion of liquid phase 4 processable. It is understood that even in the Fig. 3 illustrated embodiment, the pre-acceleration screen 12 as Two-stage filter can be formed and the pre-acceleration screen 12th deposited liquid phase 4 also according to the illustration to the right through the open side of the screen drum 6 can be discharged, for example, the Receiving device 13 according to the representation according to the outer ring area extends right into the screening stage 7, from where the Vorbeschleunigungssieb 12 in the Catching device 13 deposited liquid phase 4, for example, by appropriate, in Fig. 3, not shown devices is sucked.

In Fig. 4 is a variant of an inventive multi-stage Pusher centrifuge 1 with separately drivable Vorbeschleunigungssieb 12 shown. The Vorbeschleunigungssieb 12 is here designed and arranged that the Vorbeschleunigungssieb 12 by means of a rotary drive 14 about an axis of rotation 15 is rotatable at a predetermined speed. In this case, the rotation axis 15, as exemplified in Fig. 4, disposed within the push rod 21 and be driven independently of this by the rotary drive 14. For controlling and / or regulation of the rotational speed of the rotary drive 14 can suitable means, not shown here, be provided to the rotary drive 14th for example, depending on suitable operating parameters of the multi-stage Pusher centrifuge 1 or depending on the mixture to be processed or other factors to control and / or regulate.

Preferably, but not necessary, can the pre-acceleration funnel 12, ie the pre-acceleration screen 12, for example in a direction of Rotate oscillation movement at a different rotational speed, as in the opposite oscillation movement. For example, when moving of the solid cake 3, the rotational frequency of the Vorbeschleunigungstrichters 12 so be selected such that the pre-acceleration funnel 12 synchronously with the outer Screening drum 6 rotates, so that between the outer ring portion 92 and the Solid cake 3, which is deposited on the peripheral surface 72 of the screening stage 7, when Do not move any real movement with respect to the rotation around the Dreachse 5 is present during the return, ie in the phase of Osillationsbewegung in the the void 11 is charged with a new mixture 2, the Vorbeschleunigung funnel 12, for example, rotates slower than the outer Sieve drum 6 or slower the screening stage 7.

In Fig. 5 is schematically another embodiment of an inventive multi-stage pusher centrifuge 1 shown. In this embodiment is at Feeding device 10 an inlet funnel 16 for pre-acceleration of the mixture 2 provided. The mixture 2 passes through the feeder 10 initially in the inlet funnel 16, which is rotatably connected to the mixture manifold 8, so that the feed hopper 16 rotates synchronously with the mixture manifold 8. there the feed hopper 16 extends in a substantially axial direction and conically extending to the pre-acceleration screen 12, so that through the Feed device 10 supplied mixture 2 directly into the inlet funnel 16th arrives. In this case, the inlet funnel 16 is designed and arranged such that the Mixture 2 when leaving the inlet funnel 16 in the pre-acceleration screen 12th can be fed.

Characterized in that the inlet funnel 16 in the direction of Vorbeschleunigungssieb 12 extends substantially conically widening and the inlet funnel 16 synchronously co-rotated, the mixture 2 is already in the inlet funnel 16 to a pre-accelerated predetermined speed, so that the mixture 2 at Arrives in Vorbeschleunigungssieb 12 already a certain speed in Circumferential direction of the screening stage 7 and so overall even more gentle on the maximum peripheral speed of the circumferential surface 72 of the screening stage 7 is acceleratable.

In FIGS. 5a and 5b, an exemplary embodiment is shown schematically and by way of example a Vorbeschleunigungstrichters 12 shown. It is in both pictures to Illustration each a pre-acceleration funnel 12 shown. But how the Reference numerals 12, 16 and 17 in Fig. 2b indicate that in Fig. 2b shown example of the geometry of a funnel on both the inlet funnel 16th as well as on the pre-acceleration funnel 12.

FIG. 5 a shows a pre-acceleration funnel 12 with an outer ring region 92 for the purpose of FIG Shifting a Festoffkuchens 3. The outer ring portion 92 has a specifiable height a, depending on the mixture to be processed 2 and / or the Operating conditions under which the inventive pusher centrifuge 1 about 1% to 40% of the drum radius r, preferably about 5% to 10%, in particular 5% to 20% of the drum radius r.

In this case, as shown schematically in Fig. 5b, the funnel 12, 16, 17 may be formed as a multi-stage funnel 12, 16, 17, the funnel 12, 16, 17 for pre-acceleration of the mixture 2 more, at different angles φ ₁ , φ _{2 may have} mutually inclined partial surfaces, wherein the relative size of the partial surface and its inclination angle φ ₁ , φ ₂ may depend, for example, on the mixture 2 to be processed or on the operating parameters of the pusher centrifuge 1. In this case, both the inlet funnel 16 and the pre-acceleration funnel 12 according to FIG. 5b can be designed as a multi-stage funnel.

In particular, but not only when the inlet funnel 16 as a prefilter 17 is designed for the pre-separation of liquid phase 4, it may be of special Be advantageous if the inlet funnel 16 has a curved course and the Opening angle α of the inlet funnel 16 as shown in FIGS. 5c and 5d schematically shown, in the direction of the sliding floor device 9 out increased or decreased. It is known that different mixtures 2 are the same Operating conditions of the pusher centrifuge 1, for example, depending on the Grain size and / or viscosity and / or other properties or Parameter, such as the temperature of the mixture 2, different good are drainable.

For example, if there is a mixture 2, the given operating parameters relatively easy to drain, it may be advantageous that the inlet funnel 16 or the prefilter 17 has a curved course, wherein the Opening angle α of the prefilter screen 17 in the direction of the sliding floor device 9 out increased. Such a special embodiment of an inlet funnel 16 is in Fig. 5c shown schematically. That is, the inlet funnel 16 or the Vorfiltersieb 17 expands in the direction of the sliding floor device 9 similar to the horn of a trumpet. Thus, the output force, with the mixture 2 off the inlet funnel 16 is accelerated, with decreasing distance to Schubbodenvorrichtung 9 disproportionately larger, so that the mixture 2, the already in the prefilter 17 is relatively strong drainable and thus poor Sliding properties in the prefilter 17 shows faster exit the prefilter 17 can, for example, in a substantially conical, with a constant Opening angle α expanding prefilter sieve 17.

On the other hand, there may also be mixtures 2 which, given Operating parameters are relatively difficult to drain. In this case, it recommends itself, an inlet funnel 16 and a prefilter 17 with a curved course use, wherein the opening angle α of the prefilter 17 in the direction of Moving bottom device 9 down reduced. This has the consequence that the output force, with the mixture 2 is accelerated from the inlet funnel 16, with decreasing distance to the walking floor device 9 increases slower than for example, one below a substantially constant one Aperture angle α conically widening inlet funnel 16. This results in the Vorfiltersieb 17 a certain storage effect, so that the mixture 2 longer in Vorfiltersieb 17 remains and therefore already in the prefilter 17 to a higher degree is drainable.

Quite analogous to the previously said, of course, the Vorbeschleunigungsstrichter 12 and the pre-acceleration screen 12 a have curved course, wherein the pre-acceleration angle β of the Vorbeschleunigungstrichters 12 toward the feed device 10 out enlarged or reduced.

Preferably, the inlet funnel 16, as shown in Fig. 6, as a prefilter 17 may be formed for the pre-separation of liquid phase 4 from the mixture 2. In this case, collecting means 18 are preferred for the collection and derivation of Vorfiltersieb 17 deposited liquid phase 4 is provided. It can the Liquid phase 4, for example, through openings in the moving floor device 9 in derived from the solid cake 3 area of the screening stage 7 and then are discharged through the screen openings 61, 71 from the screen drum 6, or the Liquid phase 4 can analogously to the embodiment shown in FIG. 3 directly be removed from the screening drum, so that this part of the liquid phase is not more on the peripheral speed of the screening stage 7 or the screening drum 6 is accelerated.

In the embodiment of a multi-stage shown in Fig. 6a Pusher centrifuge 1, the inlet funnel 16 is configured as a prefilter 17 and by means of one or more fastening supports 22 on the screening drum 6 arranged. The mounting posts 22 are preferably in the form of suitable formed spokes 22, thin rods 22 or tubes 22, so that in Operating state of the solid cake 3 easily from the screening stage 7 or from the Sieve drum 6 is removable. At least one of the mounting posts 22 designed and arranged on an outer edge of the screen drum 6, that the collected in the collecting means 18 liquid phase 4 through the mounting bracket 22nd in a sieve opening 61 of the sieve drum 6 is conveyed and through the sieve opening 61 is separable from the screening drum 6. It can of course also to the mounting bracket 22 itself at a suitable location openings for the discharge of Liquid phase 4 may be provided.

Of course, depending on the embodiment of the inventive Pusher centrifuge 1 or, depending on the requirement, the prefilter sieve 17 by means of a or a plurality of mounting posts 22 also be arranged on a screening stage 7 or even at several screening stages 7 or at a screening stage 7 and at the screening drum 6 be arranged, the corresponding drums preferably no Perform oscillatory relative movement against each other.

Preferably, but not necessary, can the pre-acceleration funnel 12, ie the pre-acceleration screen 12, for example in a direction of Oscillation movement of the screening stage 7 at a different rotational speed rotate, as in the opposite oscillation movement of the screening stage 7. So For example, when moving the solid cake 3, the rotational frequency the Vorbeschleunigungstrichters 12 are chosen so that the Vorbeschleunigung funnel 12 rotates synchronously with the screening stage 7, so that between the outer ring portion 92 and the solid cake 3, which on the Peripheral surface of the screening stage 7 is deposited, when moving no Relative movement with respect to the rotation about the axis of rotation 5 is present during the Return, ie in the phase of the Osillationsbewegung in the space 11 with new mixture 2, the pre-acceleration hopper 12, for example rotates slower than the screening stage 7.

In Fig. 6b is finally an embodiment of FIG. 6a with a Blind bottom 911 shown schematically, wherein the pre-acceleration screen 12 of the For clarity, not shown as a two-stage screen. Of course Here too, both the pre-acceleration screen 12 and the prefilter screen 17 can be used be designed as a one, two or multi-stage screen.

The embodiment according to FIG. 6b has a blank bottom 911 designed outer ring portion 92, which is synchronous with the outer Screen drum 6 rotates, but from the pre-acceleration funnel 12 with respect to Rotational movement is decoupled, so that the pre-acceleration funnel 12, ie the pre-acceleration screen 12 at a different speed than the dummy bottom 911 is rotatable about the axis of rotation 5. For this purpose, as shown schematically in FIG. 6 b, the blind bottom 911 via at least one fastening strut 912 rotatably with the be connected to the outer screen drum 6, wherein the fastening strut 912 through a suitably placed opening 70 is guided in the screening stage 7, so that the Fixing strut 912 is decoupled from the oscillation movement of the screening stage 7. Of course, the embodiment according to FIG. 6b is also at higher stages as two-stage pusher centrifuges 1 analog transferable.

The advantages of the embodiment according to FIG. 6b are obvious. On the one hand is the pre-acceleration funnel 12 completely independent of the speed of outer sieve drum 6 with a mixture to be processed on the second tunable rotational frequency drivable and on the other hand rotates the blind floor 911, which transports the solid cake 3 in the axial direction with the same Speed as the sieve drum 6 and the screening stage 7, so that between the blind floor 911 and screening stage 7 with respect to the rotation about the rotation axis 5 no Relative movement takes place. Of course, in this case, too Rotation speed, for example, depending on a current Operating state of the pusher centrifuge 1, as already described above, variable be.

As shown by way of example in FIG. 7, the prefilter screen 17 can of course also be used designed as a two-stage screen with a coarse filter 171 and a fine screen 172 be. The first filter stage forms the coarse sieve 171, which contained in the mixture 2 Particles that are larger than the filter openings of the coarse sieve 171 withholds. The Fine screen 172 retains correspondingly finer particles, while at least a portion the liquid phase 4, as well as very small particles, which also have to be removed, from the screening stage 7 are directly drained. The embodiment of the prefilter screen 17 as Two-stage sieve has the particular advantage that the fine sieve 172 by large and / or heavy particles which may be contained in the incoming mixture 2, mechanically not so heavily loaded, so that the fine screen 172, for example can have very small pores for filtering very small particles and especially made of mechanically less resistant materials can be.

In practice, it can be of great importance to accelerate itself or the rotational speed at which the mixture 2 in the inlet funnel 16 is accelerated, purposefully to control. This is, for example, with the in Fig. 8 shown further embodiment of an inventive multi-stage Pusher centrifuge 1 achievable. In the embodiment according to FIG. 8, the Inlet funnel 16 mechanically decoupled from the mixture manifold 8. To control and / or regulation of the rotational speed of the inlet funnel 16 is this with a separate drive axle 19 rotatably connected and via the drive axle 19th by means of a drive 20 regardless of the screen drum 6 with a predetermined Rotational frequency drivable. In this case, suitable, not shown, means be provided to the drive 20, for example, depending on appropriate Control operating parameters of the multi-stage pusher centrifuge 1 and / or to regulate.

It goes without saying that the previously explained and in the Figures schematically illustrated embodiments also arbitrary can be combined with each other to further embodiments to special Requirements in practice.

By using the multi-stage pusher centrifuge according to the invention, the introduced mixture through which arranged on the pusher bottom device Vorbeschleunigungssieb to a predetermined peripheral speed be pre-accelerated, allowing the mixture when hitting the screen drum not in the shortest possible time from a peripheral speed near zero to full Circumferential speed of the inner screening stage is accelerated. This is under other grain fraction avoidable, so that in particular also substances that particularly sensitive to abrupt changes in centrifugal acceleration react, be processed in compliance with the highest quality standards.

In the various preferred embodiments, beyond in particular also particularly lower intake concentrations are processed, for example, 50% or 70% or 80% or even more than 90% share Liquid phase correspond, as a significant portion of the mixture contained Liquid phase is already separated in Vorbeschleunigungssieb. Especially by additional use of prefilter sieve it is possible to mix with almost to handle any liquid content without the mixture in expensive procedures must be pre-thickened. So is also at high Liquid content always ensures that a uniform distribution of the drying mixture over the inner peripheral surface of the inner screening stage or the screen drum takes place. On the one hand very harmful vibrations of the Screen drum and thus prevents the premature wear of bearings and drive and safety problems in the operation is effectively prevented. Furthermore become problems when washing the solid cake by the Uneven distribution over the peripheral surface of the screen drum as far as possible avoided. The use of both procedural and apparatus very elaborate pre-dewatering systems is also avoided, which of course leads to significant cost savings in the company.

When using the aforementioned filter systems no longer has the entire Amount of liquid phase, which is supplied with the mixture to the full Circumferential speed of the screening drum to be accelerated. This is in particular with regard to the energy consumption of the inventive multi-stage pusher centrifuge extremely favorable and also influences the Overall performance of the centrifuge clearly positive.

By appropriate different embodiment of the various Filter surfaces or by the use of the pre-acceleration funnel and / or the Einlauftrichters with its own drive, it is possible, even very mechanically sensitive mixtures, even at high speeds of the sieve drum below To comply with the highest quality standards.

Claims (15)

Multi-stage pusher centrifuge for separating a mixture (2) into a solid cake (3) and into a liquid phase (4), comprising an outer screening drum (6) rotatable about an axis of rotation (5) and at least one screening stage arranged in the outer screening drum (6) (7), arranged in the screen drum (6) mixture distributor (8) with a push floor device (9), wherein either the screening stage (7) or the sliding floor device (9) along the axis of rotation (5) is arranged back and forth, so in that the solids cake (3) is displaceable by means of the pusher bottom device (9), and with a feed device (10) with which the mixture (2) can be introduced via the mixture distributor (8) into an empty space (11) which, during displacement of the solids cake ( 3) is formed by the pusher bottom device (9), wherein the pusher bottom device (9) comprises a pre-acceleration funnel (12) which extends substantially widening in the direction of the feed device (10) d adurch characterized in that the pre-acceleration funnel (12) is designed as Vorbeschleunigungssieb (12). Multi-stage pusher centrifuge according to claim 1, wherein the Pre-acceleration funnel (12) under a substantially constant Pre-acceleration angle (β) conically widening in the direction of Feed-in device (10) extends out. Multi-stage pusher centrifuge according to claim 1 or 2, wherein the Vorbeschleunigung funnel (12) has a curved course and the Pre-acceleration angle (β) of the pre-acceleration funnel (12) in the direction enlarged to the feed device (10) out. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the pre-acceleration funnel (12) has a curved course and the Pre-acceleration angle (β) of the pre-acceleration funnel (12) in the direction reduced to the feed device (10) out. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the pre-acceleration screen (12) as a two-stage filter with a coarse filter (121) and a fine filter (122) is configured. Multi-stage pusher centrifuge according to one of the preceding claims, wherein at the mixture manifold (8) a collecting device (13) for discharging Liquid phase (4) is provided. Multi-stage pusher centrifuge according to one of the preceding claims, wherein a value of the pre-acceleration angle (β) of the pre-acceleration wire (12) with respect to the axis of rotation (5) between 0 ° and 45 °, in particular between 0 ° and 10 ° or between 10 ° and 45 °, in particular between 25 ° and 45 °, preferably between 15 ° and 35 °. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the pre-acceleration funnel (12) is designed and arranged such that the Vorbeschleunigungssieb (12) by means of a rotary drive (14) to a Rotation axis (15) is rotatable with a predetermined speed. Multi-stage pusher centrifuge according to one of the preceding claims, wherein at the feed device (10) an inlet funnel (16) is arranged, which is expanding conically under a substantially constant opening angle (α) extends in the direction of the sliding floor device (9) out. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the inlet funnel (16) has a curved course and the Opening angle (α) of the inlet funnel (16) in the direction of Moving floor device (9) towards enlarged. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the inlet funnel (16) has a curved course and the Opening angle (α) of the inlet funnel (16) in the direction of Moving bottom device (9) down. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the inlet funnel (16) as Vorfiltersieb (17) for the pre-separation of Liquid phase (4) from the mixture (2) is formed. Multi-stage pusher centrifuge according to one of the preceding claims, wherein the prefilter sieve (17) as a two-stage sieve with a coarse sieve (171) and a Fine sieve (172) is designed. Multi-stage pusher centrifuge according to one of the preceding claims, in which collecting means (18) for collecting and discharging the liquid phase (4) are provided from the prefilter sieve (17). Multi-stage pusher centrifuge according to one of the preceding claims, wherein the inlet funnel (16) about a drive axis (19) rotatably arranged and by means of a drive (20) with a predeterminable speed around the drive axle (19) is rotatable.

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