Multi-stage pusher centrifuge

The invention claimed is:




1. A multi-stage pusher centrifuge for separation mixture into solid cake into liquid phase, including outer screen drum rotatable about axis rotation least one screen stage arranged outer screen drum, mixture distributor arranged screen drum with pusher base apparatus, with either screen stage or pusher base apparatus being arranged movably fro along axis rotation such that solid cake displaceable by means pusher base apparatus, including infeed device with which mixture introduced via mixture distributor into empty space which arises displacement solid cake by pusher base apparatus, with pusher base apparatus including pre-acceleration funnel which extends substantially divergent manner direction towards infeed device, wherein pre-acceleration funnel designed pre-acceleration screen, wherein pre-acceleration funnel curved extent pre-acceleration angle which becomes one larger smaller direction towards infeed device.


2. A multi-stage pusher centrifuge accordance with claim 1, wherein pre-acceleration funnel extends substantially constant pre-acceleration angle conically divergent manner direction towards infeed device.


3. A multi-stage pusher centrifuge accordance with claim 1, wherein pre-acceleration screen designed two-stage filter with coarse filter fine filter.


4. A multi-stage pusher centrifuge accordance with claim 1, wherein collection device provided mixture distributor for draining liquid phase.


5. A multi-stage pusher centrifuge accordance with claim 1, wherein value pre-acceleration angle pre-acceleration screen with respect axis rotation lies between 0° 45°.


6. A multi-stage pusher centrifuge according claim 5 wherein value pre-acceleration angle lies between 0° 10°.


7. A multi-stage pusher centrifuge according claim 5 wherein value pre-acceleration angle lies between 10° 45°.


8. A multi-stage pusher centrifuge accordance with claim 7, wherein pre-acceleration funnel curved extent pre-acceleration angle pre-acceleration funnel becomes larger direction towards infeed device.


9. A multi-stage pusher centrifuge accordance with claim 7, wherein pre-acceleration funnel curved extent pre-acceleration angle pre-acceleration funnel becomes smaller direction towards infeed device.


10. A multi-stage pusher centrifuge according claim 5 wherein value pre-acceleration angle lies between 25° 45°.


11. A multi-stage pusher centrifuge accordance with claim 1, wherein pre-acceleration funnel designed arranged such that pre-acceleration screen rotatable pre-settable speed rotation about axis rotation by means rotational drive.


12. A multi-stage pusher centrifuge accordance with claim 1, wherein, infeed device, inlet funnel arranged which extends substantially constant opening angle conically divergent manner direction towards pusher base apparatus.


13. A multi-stage pusher centrifuge accordance with claim 1, including inlet funnel infeed device which curved extent opening angle which becomes larger direction towards pusher base apparatus.


14. A multi-stage pusher centrifuge accordance with claim 1, including inlet funnel infeed device which curved extent opening angle which becomes smaller direction towards pusher base apparatus.


15. A multi-stage pusher centrifuge accordance with claim 1, including inlet funnel that rotatably arranged about drive axis that rotated pre-settable speed rotation about drive axis by means drive.


16. A multi-stage pusher centrifuge accordance with claim 1, including inlet funnel infeed device configured pre-filter screen for pre-separation liquid phase mixture.


17. A multi-stage pusher centrifuge accordance with claim 16, wherein pre-filter screen designed two-stage screen with coarse screen fine screen.


18. A multi-stage pusher centrifuge accordance with claim 16, wherein collection means are provided for collection draining liquid phase pre-filter screen.


19. A multi-stage pusher centrifuge for separation mixture into solid cake into liquid phase, including outer screen drum rotatable about axis rotation least one screen stage arranged outer screen drum, mixture distributor arranged screen drum with pusher base apparatus, with either screen stage or pusher base apparatus being arranged movably fro along axis rotation such that solid cake displaceable by means pusher base apparatus, including infeed device with which mixture introduced via mixture distributor into empty space which arises displacement solid cake by pusher base apparatus, pusher base apparatus including pre-acceleration funnel which extends substantially divergent manner direction towards infeed device, wherein pre-acceleration funnel designed pre-acceleration screen, wherein, infeed device, inlet funnel arranged which extends substantially constant opening angle conically divergent manner direction towards pusher base apparatus.


20. A multi-stage pusher centrifuge for separation mixture into solid cake into liquid phase, including outer screen drum rotatable about axis rotation least one screen stage arranged outer screen drum, mixture distributor arranged screen drum with pusher base apparatus, with either screen stage or pusher base apparatus being arranged movably fro along axis rotation such that solid cake displaceable by means pusher base apparatus, including infeed device with which mixture introduced via mixture distributor into empty space which arises displacement solid cake by pusher base apparatus, pusher base apparatus including pre-acceleration funnel which extends substantially divergent manner direction towards infeed device, wherein pre-acceleration funnel designed pre-acceleration screen, including inlet funnel which curved extent opening angle which becomes one larger smaller direction towards pusher base apparatus.

BACKGROUND OF THE INVENTION

The invention relates multi-stage pusher centrifuge for separation mixture into solid cake into liquid phase, including outer screen drum rotatable about axis rotation least one screen stage arranged outer screen drum, mixture distributor arranged screen drum with pusher base apparatus, with either screen stage or pusher base apparatus being arranged movably along axis rotation such that solid cake displaceable by means pusher base apparatus, including infeed device with which mixture introduced via mixture distributor into empty space which forms when solid cake displaced by pusher base apparatus.

Centrifuges are widespread are used most varied areas most varied embodiments for drying moist substances or moist substance mixtures. Discontinuously operating centrifuges such scraper centrifuges are thus preferably used, for example, for drying very pure pharmaceutical products, whereas continuously operating pusher centrifuges are advantageously used particular when continuously large volumes solid/liquid mixture should separated. Depending requirements, single-stage or multi-stage pusher centrifuges well double pusher centrifuges are used.

In different types last named class pusher centrifuges, solid/liquid mixture, for example suspension or moist salt or salt mixture, supplied via mixture distributor through inlet tube fast rotating drum which designed filter screen such that liquid phase separated through filter screen due acting centrifugal forces, whereas solid cake separated interior drum wall. A substantially disc-shaped pusher base with synchronized co-rotation arranged rotating drum, with—depending number screen stages—either pusher base or screen stage oscillating specific amplitude axial direction drum such that some dried solid cake pushed out end drum. On movement pusher base opposite direction, region drum adjoining pusher base released which then again loaded with new mixture through inlet tube via mixture distributor. Depending type used, throughput volumes order magnitude 100 tons per hour reached without problem with modern heavy-duty pusher centrifuges, with drum diameters up 1000 mm more being quite normal typical rotational frequencies drum being able achieved, depending drum diameter, up 2000 revolutions per minute more. Due high centrifugal forces which occur, larger drum diameter rule results smaller maximum rotational frequency drum. The operating parameters such rotational frequency drum, volume mixture supplied per time unit or also drum diameter or type pusher centrifuge used also depend actual material dried, liquid content, etc.

The multi-stage pusher centrifuges known prior art are rule continuously operating filter centrifuges. The multi-stage filter centrifuge consists outer screen drum least one screen stage which arranged outer screen drum likewise designed screen drum. A plurality screen stages arranged concentrically inside one another such that two-stage, three-stage multi-stage pusher centrifuges realized, with all screen stages being driven very fast synchronously about joint axis rotation. In operating state, solid/liquid mixture separated continuously enters through fixed-standing inlet tube into mixture distributor which arranged innermost screen stage which likewise rotates co-synchronously uniformly distributed innermost screen stage over its whole screen periphery. The largest part liquid already centrifuged off here solid cake formed.

In two-stage pusher centrifuge, innermost stage, which also termed first stage, carries out oscillation movement direction axis rotation addition rotational movement about axis rotation. This oscillatory movement is, for example, generated hydraulically via pusher piston with reversing mechanism. The solid cake thereby pushed first stage second stage ring sections, corresponding stroke length oscillation, ultimately exits pusher centrifuge via discharge opening. In practice, solid cake continuously washed screen drum while feeding washing liquid onto solid cake.

A known two-stage pusher centrifuge which works accordance with aforementioned principle described detail, for example, DT 25 42 916 A1. In two-stage multi-stage pusher centrifuges, first stage, i.e. innermost screen stage, substantially serves for pre-dewatering mixture well for forming solid cake, whereas outer screen drum mainly serves drying stage. Since pre-dewatering possible by means first screen stage, much higher liquid absorption capacity achieved with multi-stage pusher centrifuges so that mixtures with lower inlet concentrations, i.e. with higher liquid content, processed.

For special areas application, special versions two-stage multi-stage pusher centrifuges are known, particular for highly abrasive centrifuge goods such coal raw phosphate, which require special abrasion protection measures such abrasive-resistant screens. Special designs for intensive washing processes for carrying out special washing methods such counter-flow washing for nitro-cellulose are also known prior art. Gas-impermeable versions multi-stage pusher centrifuges are also used for operation under inert gas atmosphere.

Although multi-stage pusher centrifuges such briefly outlined above also been well known for special applications most varied variants for long time, known multi-stage pusher centrifuges nevertheless show different serious disadvantages. Even if lower inlet concentrations, i.e. mixtures with increased liquid content, processed better with known multi-stage pusher centrifuges than with customary single-stage pusher centrifuges, inlet concentration mixture processed may not any desired low degree. I.e. when share liquid mixture too high, for example amounts 50% or 70% or 80% or even more than 90% liquid phase, mixture must pre-condensed more or less complex processes. With too high liquid content, uniform distribution mixture dried over periphery screen drum made increasingly difficult. This result, one hand, very damaging vibrations screen drum thus premature wear bearings drive; worst case even safety problem operation. On other hand, solid cake distributed unevenly over periphery screen drum brings about problems washing. Static condensers, arc screens or very well known hydrocyclones are therefore available, for example, for pre-dewatering. It obvious that use such pre-dewatering systems very complex thus expensive both process apparatus point view.

A further serious disadvantage processing mixtures smaller inlet concentration consists practically whole volume liquid supplied with mixture having accelerated full peripheral speed before it separated through filter screen screen drum. The same applies very small particles mixture which should likewise separated solid cake through screen. This extremely unfavorable energetically clearly negative influence operating behavior centrifuge.

But even processing mixtures with much higher solid concentration, centrifuges known prior art some huge disadvantages. For instance, mixture introduced into mixture distributor through inlet tube accelerated very short time up full peripheral speed drum impacting screen drum. This result, among other things, grain breakage, particular with sensitive substances; that is, for example, solid grains which are distributed suspension supplied centrifuge burst into smaller pieces uncontrolled manner abrupt acceleration process, which negative influences quality solid cake produced when, for example, particle size grains end product plays role.

SUMMARY OF THE INVENTION

It therefore object present invention provide improved multi-pusher centrifuge which largely avoids disadvantages known prior art.

In accordance with invention, multi-stage pusher centrifuge provided for separation mixture into solid cake into liquid phase. The multi-stage pusher centrifuge includes outer screen drum rotatable about axis rotation least one screen stage arranged outer screen drum, mixture distributor arranged screen drum having pusher base apparatus, with either screen stage or pusher base being arranged designed movably fro along axis rotation such that solid cake displaced using pusher base apparatus. The multi-stage pusher centrifuge further includes infeed device with which mixture introduced via mixture distributor into empty space which arises when solid cake displaced by pusher base apparatus, with pusher base apparatus including pre-acceleration funnel which extends substantially divergently direction toward infeed device pre-acceleration funnel being designed pre-acceleration screen.

Since multi-state pusher centrifuge accordance with invention pre-acceleration screen arranged pusher base apparatus, total amount liquid phase contained supplied mixture does not accelerated full peripheral speed screen drum, since some liquid phase already separated via pre-acceleration screen removed screen drum. Mixtures with very high liquid content thus also processed without problem. In particular, uniform distribution mixture dried over peripheral surface screen stage or screen drum thus also always ensured even with high liquid content.

Furthermore, it prevented by pre-acceleration funnel designed pre-acceleration screen that mixture introduced into mixture distributor directly through infeed device substantially only enters onto inner peripheral surface screen stage under influence gravity without pre-acceleration. The incoming mixture rather accelerated slowed manner peripheral speed screen drum, whereby particular grain breakage other damaging influences such occur abrupt acceleration multi-stage pusher centrifuges known prior art avoided. A bursting solid grains contained mixture thus avoided by multi-stage pusher centrifuge accordance with invention, because acceleration process controlled via pre-settable pre-acceleration angle pre-acceleration funnel, i.e. that acceleration itself set by suitable choice pre-acceleration angle pre-acceleration funnel. The quality solid cake produced, particular with products which particle size or shape grains end product, for example, play role, substantially increased.

The important components basic function multi-stage centrifuge are known prior art such that following reference made primarily only features material invention.

The multi-pusher centrifuge accordance with invention serves for separation mixture into solid cake into liquid phase includes material components outer screen drum which rotatable about axis rotation via drum axle accommodated housing. The drum axle actively connected drum drive such that screen drum set into fast rotation about axis rotation by drum drive. At least one screen stage arranged inside outer screen drum. Furthermore, mixture distributor having pusher base apparatus provided screen drum, with either screen stage and/or pusher base apparatus being arranged movably fro along axis rotation such that solid cake displaceable by means pusher base apparatus. Both outer screen drum screen stage screen openings through which liquid phase drained outside solid cake or mixture by centrifugal forces which occur known manner fast rotation, mixture being able applied onto inner peripheral surface screen stage. In particular, example especially important for practice, screen drum and/or screen stage designed manner known per se skeleton-like support drum which lined with special filter foils their peripheries form corresponding screen areas; i.e. skeleton-like support drum can, for example, made with one or more filter screens having filter openings different or equal size for separation liquid phase.

The mixture distributor having pusher base apparatus arranged inside screen drum which allows mixture supplied continuously through infeed device distributed onto inner peripheral surface screen stage by being introduced into empty space which arises displacement solid cake. The pusher base apparatus includes pre-acceleration funnel which designed pre-acceleration screen accordance with invention, with pre-acceleration screen extending substantially divergently direction toward infeed device. The pre-acceleration funnel designed ring region peripheral region such that solid cake deposited screen stage displaceable with ring region by oscillation pusher base apparatus or screen stage into screen drum or into further screen stage.

The mixture distributor preferably coupled screen drum manner known per se by fastening means therefore rotates specific embodiment synchronously with screen drum screen stage about common axis rotation. The oscillatory movement carried out, dependence number screen stages present, either by screen stage itself or by pusher base apparatus. There thus oscillatory relative movement between screen stage pusher base apparatus having pre-acceleration funnel operating state. The drive oscillatory movement preferably takes place via pusher rod, with solid cake deposited screen stage being pushed ring sections, whose width determined by stroke length oscillation movement, screen stage screen drum or further screen drum with outer ring region first half-period oscillatory movement, ring section solid cake deposited outer rim screen drum being pushed out screen drum second half-period oscillatory movement. During second half-period oscillatory movement, empty space simultaneously arises outer ring region screen stage such that new mixture introduced into empty space.

It important for multi-stage pusher centrifuge accordance with invention that some liquid phase already separated mixture pre-acceleration screen mixture pre-accelerated pre-settable rotational speed pre-acceleration screen such that mixture introduced infeed device accelerated pre-settable peripheral speed before reaching peripheral surface screen stage. On one hand, total amount liquid phase contained mixture thereby does not accelerated full peripheral speed screen drum so that mixtures with very high liquid content also processed without problem. Even with very high concentrations liquid phase mixture, additional devices for pre-dewatering such static condensers, arc screens or hydrocyclones are particular superfluous.

On other hand, since pre-acceleration funnel opening angle with respect axis rotation which smaller than 90°, flow speed mixture pre-acceleration funnel directly set comparison speed free-fall direction towards peripheral surface screen stage such that mixture accelerated gradually region pre-acceleration funnel it approaches outer ring region both radial direction peripheral direction screen drum. This means that mixture accelerated particularly gentle manner gradually pre-settable peripheral speed region pre-acceleration funnel order finally reach full rotational speed screen stage reaching peripheral surface.

Both inlet funnel, whose function explained detail further below, pre-acceleration funnel preferably extend pre-settable region substantially constant pre-acceleration angle or constant pre-acceleration angle conically divergent manner direction towards pusher base apparatus or towards infeed device.

For specific applications, for example dependence properties mixture dewatered, inlet funnel and/or pre-acceleration funnel can, however, also curved extent pre-settable region, with opening angle inlet funnel and/or pre-acceleration angle pre-acceleration funnel becoming larger or smaller direction towards pusher base apparatus. This particular advantage when inlet funnel or pre-acceleration funnel formed, described more precisely below, pre-filter screen or pre-acceleration screen for pre-separation liquid phase.

In specific embodiment, pre-acceleration screen designed two-stage filter with coarse filter fine filter. The mixture thereby filtered two stages region pre-acceleration screen. The design pre-acceleration screen two-stage filter particular advantage that fine filter not mechanically strained much by large and/or heavy particles contained incoming mixture so that fine filter have, for example, very small pores for filtering very small particles particular made materials with mechanically low resistance.

It particular importance for practice for collection apparatus provided mixture distributor for draining liquid phase such that some liquid phase already removed before reaching enormously fast rotating peripheral surface screen stage. This part liquid phase then no longer accelerated full peripheral speed screen stage, which results huge saving energy relief components, particular rotating and/or oscillating components multi-stage pusher centrifuge. Even mixtures with extremely high liquid content thereby processed without problem.

In further embodiment multi-stage pusher centrifuge accordance with invention, pre-acceleration screen designed arranged such that pre-acceleration screen rotated pre-settable speed rotation about axis rotation by means rotational drive irrespective speed rotation screen drum. Suitable means are preferably provided, for example form computer-aided electronic systems for control and/or regulation rotational speed rotational drive, order control and/or regulate rotational drive, for example dependence suitable operating parameters multi-stage pusher centrifuge.

In another preferred embodiment multi-stage pusher centrifuge accordance with invention, inlet funnel additionally provided infeed device for pre-acceleration incoming mixture. The mixture moves through infeed device first into inlet funnel which is, preferably one embodiment, but not necessarily, rotationally fixedly connected mixture distributor such that inlet funnel rotates synchronously with mixture distributor. The inlet funnel extends divergently substantially axial direction towards pre-acceleration screen such that mixture supplied through infeed device enters directly into inlet funnel. The inlet funnel designed arranged such that mixture fed into pre-acceleration screen exiting inlet funnel.

Due arrangement design inlet funnel, mixture already pre-accelerated pre-settable rotational speed inlet funnel so that mixture already certain speed peripheral direction screen stage entering pre-acceleration screen thus accelerated even more gently overall maximum peripheral speed peripheral surface screen stage.

The inlet funnel preferably also made pre-filter screen for pre-separation liquid phase mixture. Collection means are preferably provided for collection draining liquid phase separated by pre-filter screen.

A value opening angle inlet funnel and/or value pre-acceleration angle pre-acceleration funnel with respect axis rotation lie, for example, between 0° 45°, individually between 0° 100 or between 10° 45°, particular between 25° 45°, preferably between 15° 35°. It specific cases also possible for value opening angle and/or pre-acceleration angle larger than 45°. It very generally said that rule acute angle more advantage with respect axis rotation, with optimum value corresponding opening angle and/or pre-acceleration angle being determined inter alia by value static friction angle product dewatered.

In particular when, but not only when, inlet funnel made pre-filter screen for pre-separation liquid phase, it particular advantage for inlet funnel curved extent for opening angle inlet funnel become larger or smaller direction towards pusher base apparatus. It known that different products different levels dewatering under operating conditions pusher centrifuge which are otherwise same, for example dependence grain size and/or viscosity and/or other properties or parameters such temperature mixture.

If, for example, mixture present which relatively easy dewater under given operating parameters, it advantage for inlet funnel or pre-filter screen curved extent, with opening angle pre-filter screen becoming larger direction towards pusher base apparatus. This means that inlet funnel or pre-filter screen diverges direction towards pusher base apparatus similar horn trumpet. The driving force which mixture accelerated out inlet funnel thus becomes disproportionately larger spacing pusher base apparatus decreases such that mixture which already relatively highly dewaterable pre-filter screen thus shows poor slide properties pre-filter screen exit pre-filter screen faster than, for example, with pre-filter screen diverging substantially cone-shape with constant opening angle.

On other hand, mixtures also present which are relatively difficult dewater under given operating parameters. In this case, it recommended use inlet funnel or pre-filter screen with curved extent, with opening angle pre-filter screen becoming smaller direction towards pusher base apparatus. This consequence that driving force with which mixture accelerated out inlet funnel increases more slowly spacing towards pusher base apparatus decreases than, for example, with inlet funnel diverging conically substantially constant opening angle. A certain congestion effect thereby occurs pre-acceleration screen such that mixture remains longer pre-filter screen therefore already dewaterable higher degree pre-filter screen.

In very analogous manner aforesaid, pre-acceleration funnel also curved extent, with pre-acceleration angle pre-acceleration funnel becoming larger or smaller direction towards infeed device.

The advantages previously explained connection with curved inlet funnel function thereof are easily analogously transferable curved pre-acceleration funnel by person skilled art therefore do not need repeated here.

Furthermore, specific embodiment, pre-filter screen also designed two-stage screen with coarse screen with fine screen. The advantages are obvious. The first filter stage formed by coarse screen which keeps back particles contained mixture which are larger than filter openings coarse screen. The fine screen keeps back correspondingly finer particles, whereas least part liquid phase, well very small particles which likewise removed, drained directly screen stage. The design pre-filter screen two-stage screen particular advantage that fine screen not put under such strong mechanical strain by large and/or heavy particles contained incoming mixture so that fine screen can, for example, very small pores for filtration very small particles particular also made materials which are mechanically less resistant.

In particular, embodiment especially important for practice, inlet funnel and/or pre-acceleration funnel designed skeleton-like support body which fitted with special filter foils for formation pre-filter screen and/or pre-acceleration screen; i.e. skeleton-like support body can, for example, equipped with one or more filter screens which possibly differently sized filter openings for separation different stages.

Separator screens or, for example, sheet metal screens used, among other things, quite generally filter screens. The filter screens advantageously provided different manners with filter openings different sizes. In particular, aforesaid sheet metal screens stamped, drilled, lasered, electron beam punched or water jet cut, among other things, with generally other techniques also being possible. The screens themselves can, depending demand, produced different materials, particular corrosion-resistant materials, such plastic, composite materials or different steels such 1.4462, 1.4539 or 2.4602 or other suitable materials. For protection against wear, filter screens furthermore provided with suitable layers, for example hardened with hard chromium layers, tungsten carbide (WC), ceramics or other ways. The thickness filter sheet metals typically amounts 0.2 mm 5 mm, with much different sheet metal thicknesses also being possible.

It great importance practice directly control acceleration process itself or rotational speed which mixture accelerated inlet funnel. The inlet funnel therefore arranged rotationally about drive axis rotatable pre-settable speed about drive axis by means drive. For control and/or regulation rotational speed inlet funnel, this is, for example, rotationally fixedly connected separate drive axle driven via drive axle by means drive independently screen drum and/or independently pre-acceleration screen pre-settable rotational frequency. As already described above for drive pre-acceleration screen, suitable means provided control and/or regulate drive, for example dependence mixture processed, specific operating parameters multi-stage pusher centrifuge, etc. For this purpose, multi-stage pusher centrifuge accordance with invention also include corresponding sensors for measurement relevant operating parameters.

It understood that features particularly preferred embodiments multi-stage pusher centrifuge accordance with invention previously described by way example also combined desired advantageous manner depending demand.

The invention explained following more detail with reference schematic drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows, section, multi-stage pusher centrifuge with pre-acceleration screen;

FIG. 2 shows further embodiment accordance with FIG. 1 with two-stage filter;

FIG. 3 shows another embodiment accordance with FIG. 1 with collection device for draining liquid phase;

FIG. 4 shows multi-stage pusher centrifuge with separately drivable pre-acceleration funnel;

FIG. 5 shows multi-stage pusher centrifuge with inlet funnel;

FIG. 5 shows embodiment pre-acceleration funnel;

FIG. 5 b shows further embodiment pre-acceleration funnel;

FIG. 5 c shows inlet funnel with curved extent;

FIG. 5 d shows another inlet funnel accordance with FIG. 5 c;

FIG. 6 shows embodiment accordance with FIG. 5 with pre-filter screen;

FIG. 6 shows second embodiment accordance with FIG. 6 with rotatable pre-acceleration screen;

FIG. 6 b shows second embodiment accordance with FIG. 6 with false bottom;

FIG. 7 shows second embodiment accordance with FIG. 6 with coarse screen fine screen;

FIG. 8 shows inlet funnel with rotational drive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows, section schematic representation, important components first embodiment multi-stage pusher centrifuge accordance with invention with pre-acceleration screen. In drawings present applications, for reasons clarity, only two-stage pusher centrifuges are shown schematically by way example. It understood that illustration two-stage pusher centrifuges understood example that description also applies pusher centrifuges with more than two stages transferred correspondingly.

The multi-stage pusher centrifuge accordance with invention, which designated whole following with reference numeral 1 , serves for separation mixture 2 into solid cake 3 into liquid phase 4 includes important components outer screen drum 6 which rotatable via drum axle 51 about axis rotation 5 accommodated housing G. The drum axle 51 effective connection with drum drive 52 such that screen drum 6 set into fast rotation about axis rotation 5 by drum drive 52 . At least one screen stage 7 arranged inside outer screen drum 6 . Furthermore, mixture distributor 8 with pusher base apparatus 9 provided screen drum 6 , with either screen stage 7 or pusher base apparatus 9 being arranged movably fro along axis rotation 5 such that solid cake 3 displaced by means pusher base apparatus 9 . Both outer screen drum 6 screen stage 7 screen openings 61 , 71 through which liquid phase 4 drained outwardly known manner by centrifugal forces which occur fast rotation solid cake 3 or mixture 2 which, described more detail further below, applied inner peripheral surface 72 screen stage 7 .

The mixture distributor 8 with pusher base apparatus 9 arranged inside screen drum 6 allows mixture 2 continuously supplied by infeed device 10 distributed onto inner peripheral surface 72 screen stage 7 by introduction into empty space 11 which arises displacement solid cake 3 . The pusher base apparatus 9 includes pre-acceleration funnel 12 which designed pre-acceleration screen 12 , with pre-acceleration screen 12 extending substantially conically divergent manner direction towards infeed device 10 . The pre-acceleration funnel 12 formed ring section 92 peripheral region such that solid cake 3 deposited screen stage 7 displaceable with ring region 92 by oscillation pusher base apparatus 9 described further below and/or screen stage 7 into screen drum 6 or into further screen stage 7 not shown here.

It important for multi-stage pusher centrifuge 1 accordance with invention that some liquid phase 4 already separated mixture 2 pre-acceleration screen 12 mixture 2 pre-accelerated pre-settable rotational speed pre-acceleration screen 12 .

The mixture distributor 8 rigidly coupled embodiment shown FIG. 1 screen drum 6 by fastening means 91 therefore rotates synchronously about axis rotation 5 with screen drum 6 screen stage 7 . The oscillatory movement, which indicated by double arrow FIG. 1, carried out example shown here, however, only by screen stage 7 . In operating state, there thus oscillatory relative movement between oscillating screen stage 7 pusher base apparatus 9 , with pre-acceleration funnel 12 , immovable axial direction. The oscillatory movement screen stage 7 preferably takes place via pusher rod 21 , with solid cake 3 deposited screen stage 7 being pushed ring sections, whose width determined by stroke length oscillation movement screen stage 7 , screen stage 7 with outer ring region screen drum 6 first half-period oscillatory movement, ring section solid cake 3 deposited outer rim screen drum 6 being pushed out screen drum 6 second half-period oscillatory movement by screen stage 7 . During second half-period oscillatory movement, empty space 11 simultaneously arises screen stage 7 such that new mixture introduced into empty space 11 .

It important for multi-stage pusher centrifuge 1 accordance with invention that some liquid phase 4 already separated mixture 2 pre-acceleration funnel 12 mixture 2 pre-accelerated pre-settable rotational speed pre-acceleration funnel 12 such that mixture 2 introduced infeed device 10 accelerated pre-settable peripheral speed before reaching screen stage 7 . On one hand, total amount liquid phase 4 contained mixture 2 thereby does not accelerated full peripheral speed screen drum 6 , since some liquid phase 4 already separated via pre-acceleration screen 12 separated directly screen drum 6 through screen openings 61 , 71 . Mixtures 2 with very high content liquid phase thus also processed without problem. A uniform distribution mixture 2 dried over peripheral surface 72 screen stage 7 or screen drum 6 thus always particular ensured even with high content liquid phase 4 . Even with very high concentrations liquid phase 4 mixture 2 , additional devices for pre-dewatering such static condensers, arc screens or hydrocyclones are particular superfluous. Even smallest particles contained mixture 2 also separated more effectively solid cake 3 by effect pre-filtration.

Moreover, since pre-acceleration funnel 12 pre-acceleration angle β which smaller than 90°, flow speed mixture 2 pre-acceleration funnel 12 directly set comparison speed free-fall direction towards peripheral surface 72 screen stage 7 such that mixture 2 accelerated gradually region pre-acceleration funnel 12 it approaches outer ring region 92 both radial direction peripheral direction screen drum 6 . This means that mixture 2 accelerated particularly gentle manner gradually pre-settable peripheral speed region pre-acceleration screen 12 order finally reach full rotational speed screen stage 7 reaching peripheral surface 72 .

The value pre-acceleration angle β pre-acceleration funnel 12 value opening angle α inlet funnel 16 described later lie, for example, with respect axis rotation 5 between 0° 45°, individually between 0° 10° or between 10° 45°, particular between 25° 45°, preferably between 15° 35°. It specific cases also possible for value opening angle α and/or pre-acceleration angle β larger than 45°. It very generally said that rule acute angle more advantage with respect axis rotation 5 , with optimum value corresponding opening angle α and/or pre-acceleration angle β being determined inter alia by value static friction angle mixture 2 dewatered.

Since mixture 2 , unlike with multi-stage pusher centrifuges known prior art, not accelerated abruptly region pre-acceleration screen 12 , i.e. very short time, full rotational speed screen stage 7 , grain breakage other damaging effects mixture 2 can, for example, avoided. In particular, mechanically very sensitive substances thus also processed even extremely high rotational speeds screen drum 6 multi-stage pusher centrifuge 1 accordance with invention.

A further embodiment accordance with FIG. 1 shown FIG. 2, with pre-acceleration screen 12 being designed two-stage filter with coarse filter 121 fine filter 122 . The mixture 2 thereby filtered two stages region pre-acceleration screen 12 . The first filter stage formed by coarse filter 121 which holds back particles contained mixture which are larger than filter openings coarse filter 121 which thus introduced into empty space 11 . The fine filter 122 holds back correspondingly fine particles which likewise supplied empty space 11 thus solid cake 3 , whereas least some liquid phase 4 , well very small particles which likewise removed, drained screen drum 6 directly through screen opening 61 , 71 . The design pre-acceleration screen 12 two-stage filter particular advantage that fine filter 122 not mechanically strained much by large and/or heavy particles which contained incoming mixture 2 so that fine filter 122 have, for example, very small pores for filtering very small particles particular made materials with mechanically low resistance.

It particular importance for practice for, shown schematically FIG. 3, collection apparatus 13 provided mixture distributor 8 for draining liquid phase 4 such that some liquid phase 4 already removed before reaching very fast rotating peripheral surface 72 screen stage 7 . This part liquid phase 4 then no longer accelerated full peripheral speed screen stage 7 , which results huge saving energy relief components, particular rotating and/or oscillating components multi-stage pusher centrifuge 1 . Even mixtures 2 with extremely high liquid phase 4 thereby processed without problem. It understood that embodiment shown FIG. 3, pre-acceleration screen 12 also made two-stage filter liquid phase 4 separated pre-acceleration screen 12 also drained right accordance with illustration through open side screen drum 6 that, for example, collection device 13 extends over outer ring region right accordance with illustration into screen stage 7 where liquid phase separated pre-acceleration screen 12 into collection device 13 sucked off, for example, by suitable apparatuses not shown FIG. 3.

A variant multi-stage pusher centrifuge 1 accordance with invention shown FIG. 4 with separately drivable pre-acceleration screen 12 . The pre-acceleration screen 12 designed arranged here such that pre-acceleration screen 12 rotatable pre-settable speed rotation about rotational axle 15 by means rotational drive 14 . The rotational axle 15 , shown by way example FIG. 4, arranged inside pusher rod 21 driven independently this by rotational drive 14 . Suitable means, not shown here, provided for control and/or regulation rotational speed rotational drive 14 order control and/or regulate rotational drive 14 , for example dependence suitable operating parameters multi-stage pusher centrifuge 1 or dependence mixture processed or other factors.

Preferably, but not necessarily, pre-acceleration funnel 12 , that is, pre-acceleration screen 12 , can, for example, rotate different rotational speed one direction oscillation movement than with opposite oscillation movement. The rotational frequency thus, for example, chosen displacement solid cake 3 such that pre-acceleration funnel 12 rotates synchronously with outer screen drum 6 so that no relative movement present with respect rotation about axis rotation 5 displacement between outer ring region 92 solid cake 3 which deposited peripheral surface 72 screen stage 7 , whereas return movement, that is, phase oscillation movement which empty space 11 loaded with new mixture 2 , pre-acceleration funnel 12 rotates more slowly, for example, than outer screen drum 6 or more slowly than screen stage 7 .

A further embodiment multi-stage pusher centrifuge 1 accordance with invention shown FIG. 5. In this embodiment, inlet funnel 16 provided infeed device 10 for pre-acceleration mixture 2 . The mixture 2 moves through infeed device 10 first into inlet funnel 16 which rotationally fixedly connected mixture distributor 8 such that inlet funnel 16 rotates synchronously with mixture distributor 8 . The inlet funnel 16 extends substantially axial direction conically divergent manner towards pre-acceleration screen 12 such that mixture 2 supplied through infeed device 10 enters directly into inlet funnel 16 . The inlet funnel 16 designed arranged such that mixture 2 fed into pre-acceleration screen 12 exiting inlet funnel 16 .

Since inlet funnel 16 extends substantially conically divergent manner direction towards pre-acceleration screen 12 inlet funnel 16 rotates synchronously, mixture 2 already pre-accelerated pre-settable rotational speed inlet funnel 16 such that mixture 2 already specific speed peripheral direction screen stage 7 entering pre-acceleration screen 12 thus accelerated even more gently overall maximum peripheral speed peripheral surface 72 screen stage 7 .

One embodiment each pre-acceleration funnel 12 shown by way example schematically FIGS. 5 5 b . In both figures, one respective pre-acceleration funnel 12 shown for illustration purposes. As, however, reference numerals 12 , 16 17 indicate FIG. 2 b , example shown FIG. 2 b for geometry funnel relates both inlet funnel 16 pre-acceleration funnel 12 .

FIG. 5 shows pre-acceleration funnel 12 with outer ring region 92 for displacement solid cake 3 . The outer ring region 92 pre-settable height which, dependence mixture 2 processed and/or operation conditions under which pusher centrifuge 1 accordance with invention operated, amounts approximately 1% 40% drum radius r, preferably approximately 5% 10%, particular 5% 20% drum radius r.

As shown schematically FIG. 5 b , funnel 12 , 16 , 17 also made multi-stage funnel 12 , 16 , 17 , with funnel 12 , 16 , 17 for pre-acceleration mixture 2 being able plurality part faces which inclined different angles (φ 1 , φ 2 one another, with relative size part face its inclination angles φ 1 , φ 2 , for example, being able depend mixture 2 processed or operating parameters pusher centrifuge 1 . Both inlet funnel 16 pre-acceleration funnel 12 accordance with FIG. 5 b made multi-stage funnels.

In particular when, but not only when, inlet funnel 16 designed pre-filter screen 17 for pre-separation liquid phase 4 , it particular advantage for inlet funnel 16 curved extent for opening angle α inlet funnel 16 , shown schematically FIGS. 5 c 5 d , become larger or smaller direction towards pusher base apparatus 9 . It known that different mixtures 2 different levels dewatering under operating conditions pusher centrifuge 1 which are otherwise same, for example dependence grain size and/or viscosity and/or other properties or parameters such temperature mixture 2 .

If, for example, mixture 2 present which relatively easy dewater under given operating parameters, it advantage for inlet funnel 16 or for pre-filter screen 17 curved extent, with opening angle α pre-filter screen 17 becoming larger direction towards pusher base apparatus 9 . Such specific embodiment inlet funnel 16 shown schematically FIG. 5 c . This means that inlet funnel 16 or pre-filter screen 17 diverges direction towards pusher base apparatus 9 similar horn trumpet. The output driving force which mixture 2 accelerated out inlet funnel 16 thus becomes disproportionately larger spacing pusher base apparatus 9 decreases such that mixture 2 which already relatively highly dewaterable pre-filter screen 17 thus shows poor slide properties pre-filter screen 17 exit pre-filter screen 17 faster than, for example, with pre-filter screen 17 diverging substantially cone-shape with constant opening angle α.

On other hand, mixtures 2 also present which are relatively difficult dewater under given operating parameters. In this case, it recommended use inlet funnel 16 or pre-filter screen 17 with curved extent, with opening angle α pre-filter screen 17 becoming smaller direction towards pusher base apparatus 9 . This consequence that output driving force with which mixture 2 accelerated out inlet funnel 16 increases more slowly spacing towards pusher base apparatus 9 decreases than, for example, with inlet funnel 16 diverging conically substantially constant opening angle α. A certain congestion effect thereby occurs pre-filter screen 17 such that mixture 2 remains longer pre-filter screen 17 therefore already dewaterable higher degree pre-filter screen 17 .

In very analogous manner aforesaid, pre-acceleration funnel 12 or pre-acceleration screen 12 also curved extent, with pre-acceleration angle β pre-acceleration funnel 12 becoming larger or smaller direction towards infeed device 10 .

As shown FIG. 6, inlet funnel 16 preferably made pre-filter screen 17 for pre-separation liquid phase 4 mixture 2 . Collection means 18 are preferably provided for collection draining liquid phase 4 separated pre-filter screen 17 . The liquid phase 4 can, for example led through openings pusher base apparatus 9 into region screen stage 7 separated solid cake 3 then drained screen drum 6 through screen openings 61 , 71 , or liquid phase can, analogously embodiment shown FIG. 3, drained directly screen drum such that this part liquid phase no longer accelerated peripheral speed screen stage 7 or screen drum 6 .

In embodiment shown FIG. 6 multi-stage pusher centrifuge 1 , inlet funnel 16 designed pre-filter screen 17 arranged screen drum 6 by means one or more fastening stubs 22 . The fastening stubs 22 are preferably made form suitably shaped spokes 22 , thin rods 22 or tubes 22 so that solid cake 3 removed without problem screen stage 7 or screen drum 6 operating state. At least one fastening stubs 22 made arranged outer rim screen drum 6 such that liquid phase 4 collected collection means 18 transported through fastening stub 22 into screen opening 61 screen drum 6 separated screen drum 6 through screen opening 61 . Openings also provided for draining liquid phase 4 suitable position fastening stub 22 itself.

Depending embodiment pusher centrifuge 1 accordance with invention or depending demand, pre-filter screen 17 also arranged by means one or more fastening stubs 22 screen stage 7 or even arranged plurality screen stages 7 or screen stage 7 screen drum 6 , with corresponding drums preferably not carrying out oscillatory relative movement with respect one another.

Preferably, but not necessarily, pre-acceleration funnel 12 , that is, pre-acceleration screen 12 , can, for example, rotate different rotational speed one direction oscillation movement screen stage 7 than with opposite oscillation movement screen stage 7 . The rotational frequency pre-acceleration funnel 12 thus, for example, chosen displacement solid cake 3 such that pre-acceleration funnel 12 rotates synchronously with screen stage 7 so that no relative movement present with respect rotation about axis rotation 5 displacement between outer ring region 92 solid cake 3 which deposited peripheral surface screen stage 7 , whereas return movement, that is, phase oscillation movement which empty space 11 loaded with new mixture 2 , pre-acceleration funnel 12 rotates more slowly, for example, than screen stage 7 .

Finally, FIG. 6 b , embodiment accordance with FIG. 6 shown schematically with false bottom 911 , with pre-acceleration screen 12 not being shown two-stage screen for reasons clarity. Both pre-acceleration screen 12 pre-filter screen 17 also made single-stage, two-stage or multi-stage screen.

The embodiment accordance with FIG. 6 b outer ring region 92 designed false bottom 911 which rotates synchronously with outer screen drum 6 , but uncoupled pre-acceleration funnel 12 with respect rotational movement such that pre-acceleration funnel 12 , that is, pre-acceleration screen 12 , rotatable about axis rotation 5 different speed rotation false bottom 911 . For this purpose, shown schematically FIG. 6 b , false bottom 911 rotationally fixedly connected outer screen drum 6 via least one fastening strut 912 , with fastening strut 912 being guided through suitably placed opening 70 screen stage 7 such that fastening strut 912 uncoupled oscillation movement screen stage 7 . The embodiment accordance with FIG. 6 b also transferred analogously pusher centrifuges 1 with more stages than two-stage pusher centrifuges 1 .

The advantages variant accordance with FIG. 6 b are obvious. On one hand, pre-acceleration funnel 12 driven completely independently speed rotation outer screen drum 6 rotational frequency which matched mixture 2 processed and, other hand, false bottom 911 which transports solid cake 3 axial direction rotates same speed rotation screen drum 6 or screen stage 7 such that no relative movement takes place with respect rotation about axis rotation 5 between false bottom 911 screen stage 7 . The rotational speed also variable this case, for example dependence instantaneous operating state pusher centrifuge 1 , already described above.

As shown by way example FIG. 7, pre-filter screen 17 also designed two-stage screen with coarse screen 171 fine screen 172 . The first filter stage formed by coarse screen 171 which holds back particles contained mixture 2 which are larger than filter openings coarse screen 171 . The fine screen 172 holds back correspondingly finer particles, whereas least some liquid phase 4 well very fine particles which likewise removed drained directly screen stage 7 . The design pre-filter screen 17 two-stage screen particular advantage that fine screen 172 not put under such strong mechanical strain by large and/or heavy particles which contained incoming mixture 2 so that fine screen 172 can, for example, very small pores for filtering very small particles particular also made mechanically less resistant materials.

It great importance practice directly control acceleration process itself or rotational speed which mixture 2 accelerated inlet funnel 16 . This can, for example, achieved with further variant pusher centrifuge 1 accordance with invention shown FIG. 8. In variant accordance with FIG. 8, inlet funnel 16 mechanically uncoupled mixture distributor 8 . For control and/or regulation rotational speed inlet funnel 16 , it rotationally fixedly connected separate drive axle 19 drivable pre-settable rotationally frequency via drive axle 19 by means drive 20 independently screen drum 6 . Suitable means, not shown here, provided control and/or regulate drive 20 , for example dependence suitable operating parameters multi-stage pusher centrifuge 1 .

It self-explanatory that previously explained variants shown schematically figures also combined desired with one another form further embodiments satisfy specific demands practice.

By use multi-stage pusher centrifuge accordance with invention, mixture introduced through pre-acceleration screen arranged pusher base apparatus pre-accelerated pre-settable peripheral speed such that mixture not accelerated full peripheral speed inner screen stage peripheral speed close zero very short time impacting screen drum. Grain breakage can, among other things, thereby avoided such that particular also substances which are particularly sensitive abrupt changes centrifugal acceleration or radial acceleration are processed while observing very high quality demands.

In different preferred embodiments, particular also much lower inlet concentrations moreover processed which correspond, for example, 50% or 70% or 80% or even more than 90% proportion liquid phase, since substantial part liquid phase contained mixture already separated pre-acceleration screen. It particular possible by additional use pre-filter screen process mixtures with almost any desired large liquid content without liquid having pre-condensed complex methods. It thus also always ensured with extremely high liquid content that uniform distribution mixture dried takes place over inner peripheral surface inner screen stage or screen drum. Very damaging vibrations screen drum thus premature wear bearings drive are thus prevented safety problems operation are effectively prevented. Furthermore, problems washing solid cake due its uneven distribution over peripheral surface screen drum are very largely avoided. The use pre-dewatering systems which are very complex both technical process aspect apparatus aspect likewise avoided, which results substantial cost savings operation.

When previously mentioned filter systems are used, whole volume liquid phase which supplied with mixture also no longer accelerated full peripheral speed screen drum. This particular extremely favorable with respect energy consumption multi-stage pusher centrifuge accordance with invention moreover influences operating behavior centrifuge overall very positive manner.

By corresponding different designs different filter surfaces particular by use pre-acceleration funnel and/or inlet funnel with separate drive, it possible even process very sensitive mixtures even high speeds rotation screen drum while maintaining very high quality standards.