EP1468741A1 - Double-acting pusher centrifuge - Google Patents

Abstract

The double thrust centrifuge includes a rotatable sieving drum (3) to separate a mixture (4) into a solid cake (5) and a liquid phase (6), and a mixture distributor (7) inside the sieving drum equipped with a thrust base device (8) which on both sides has accelerating surfaces (12) which in relation to the radial direction are inclined at an predefined angle so that the mixture introduced through the feed component (10) is accelerated to a predetermined circumferential speed before reaching the sieving drum.

Description

The invention relates to a double push centrifuge according to the preamble of independent claim 1.

For drying moist substances or moist substance mixtures Centrifuges in a wide variety of designs are widely used used in various fields. So come for example Drying of high purity pharmaceutical products working discontinuously Centrifuges, such as peeler centrifuges, are preferred for use while in particular then when continuously separating large amounts of a solid-liquid mixture continuously operating push centrifuges are to be used advantageously become. Depending on the requirements, there are single or multi-stage Pusher centrifuges and so-called double pusher centrifuges are used.

For the different types of the latter class of push 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 screen, so that on the ground the centrifugal forces excreted the liquid phase through the filter screen a solid cake is deposited on the inside of the drum wall becomes. There is an essentially disc-shaped, arranged synchronously co-rotating moving floor, which in the axial direction in the Drum oscillates with a certain amplitude, so that 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 on the moving floor adjacent area of the drum released, which then through the inlet pipe and can be loaded with new mixture via the mixture distributor. there can, depending on the type used, with modern high-performance push centrifuges Throughputs in the order of 100 tons per hour are no problem can be achieved, with drum diameters of up to 1000 mm and more are common and typical rotation frequencies of the drum, depending on Drum diameters of up to 2000 revolutions per minute and more achieved can be. As a rule, this requires a larger drum diameter a smaller maximum due to the strong centrifugal forces that occur Rotation frequency of the drum. Of course, the operating parameters, such as. the rotation frequency of the drum, the amount supplied per unit of time Mixture or the drum diameter or the type of used Thrust centrifuge also on the material to be dried, the content of Suspend liquid, etc.

In the known double-shear centrifuges, the mixture usually passes over a standing inlet pipe and a mixture distributor in the middle of the Centrifuge drum, the mixture distributor with the centrifuge drum rotates synchronously. By one arranged in the middle of the centrifuge drum Moving floor that oscillates along the longitudinal axis of the centrifuge drum and with the mixture distributor can be effectively connected, the mixture is in Interaction with the mixture distributor, alternately the front or rear half of the drum can be fed. This means there are two entry zones, see above that correspondingly larger quantities of mixture are processed per unit of time can. The solid cake becomes the respective end through the moving floor the drum is transported and discharged via a gutter.

A well-known double push centrifuge based on the principle described above works, is described in detail in EP 0 635 309 B1, for example. The There are advantages over conventional single or multi-stage push centrifuges On the hand. Among other things, the double inlet zone is to be mentioned here, whereby a significantly increased fluid swallowing capacity is achieved, so that mixtures with lower inlet concentrations, i.e. with higher fluid content can be processed, while at the same time higher total feed quantities Mixture can be processed. It also results in the same number of strokes twice the Festoff funding capacity and thus a specifically lower one Transport work. The space requirement corresponds to that of normal Shear centrifuges of the same size.

Typical areas of application for double-shear centrifuges are among others good drainable products, such as sea salt, where in particular the double Exploitation of the thrust movement comes into play. Another typical one Areas of application are products that are difficult to filter or mixtures with low levels Enema concentrations (i.e. with a high liquid content). Here it affects in Higher liquid swallowing capacity compared to ordinary push centrifuges particularly positive. There may be smaller enema concentrations or higher Amounts of suspension can be processed without causing flooding.

However, the known push centrifuges also have various serious Disadvantages. Even if lower with the known double push centrifuges Enema concentrations can be processed as with ordinary in or multi-stage pusher centrifuges, the inlet concentration of the to be processed Mixture should not be arbitrarily small. That is, if the proportion of liquid in the mixture is too high, for example 50% or 70% or 80% or even more than 90% Is liquid phase, the mixture must be more or less expensive Processes are pre-thickened. If the liquid content is too high, one will uniform distribution of the mixture to be dried over the circumference of the Sieve drum increasingly difficult. On the one hand, this can be too damaging Vibrations of the sieve drum and thus premature wear of bearings and Drive drive; in the worst case, even a security problem in the company become. On the other hand, it causes an irregularity over the circumference of the sieve drum distributed solid cake problems with washing. Therefore are available Pre-drainage, for example, static thickeners, curved screens or the best known hydrocyclones are available. It is obvious that use such pre-drainage systems both process engineering and apparatus is very complex and therefore expensive.

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

But even when processing mixtures with significantly higher ones Solids concentration is shown by the centrifuges known from the prior art some massive disadvantages. So it is through the inlet pipe in the Mixture distributor introduced mixture when it hits the sieve drum in accelerated to the full peripheral speed of the drum in the shortest possible time. Particularly with sensitive substances, this can lead to grain breakage to lead. This means that, for example, solid particles in one of the centrifuges supplied suspension are distributed in the abrupt acceleration process in bursting into smaller pieces in an uncontrolled manner, which adversely affects the Quality of the solid cake produced can, for example, if Particle size of the grains plays a role in the end product.

The object of the invention is therefore an improved double push centrifuge To propose, the disadvantages known from the prior art largely avoids.

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

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

The double-shear centrifuge according to the invention comprises one about an axis of rotation rotating sieve drum for separating a mixture into a solid cake and a liquid phase and a mixture distributor arranged in the sieve drum with a moving floor device that can be moved back and forth along the axis of rotation is arranged so that the solid cake alternately with an outer Ring area is slidable. The double push centrifuge also includes one Infeed device with which the mixture via the mixture distributor in a Empty space can be introduced, which is adjacent to the outer ring area at Moving the solid cake is created by the moving floor device. there the moving floor device has acceleration surfaces on both sides, which inclined with respect to the radial direction at a predeterminable angle of inclination are so that the mixture introduced by the feed device before Reaching the screening drum to a predeterminable peripheral speed is accelerable.

The fact that the moving floor device inclined against the radial direction Has acceleration surfaces, arrives through the feed device in the Mixer distributor mixture not introduced directly onto the sieve drum. Rather, the incoming mixture is applied to the acceleration surfaces, which are inclined against the radial direction. This will slow you down Acceleration of the newly introduced mixture to the peripheral speed reached the sieve drum, causing in particular grain breakage and other damaging Influences such as those resulting from abrupt acceleration in the prior art known double push centrifuges occur, can be prevented. Thus, by the Double-push centrifuge according to the invention a bursting of the mixture contained solid grains avoidable because the acceleration process over the predeterminable angle of inclination of the acceleration surfaces is controllable, i.e. that the acceleration itself, for example, by a suitable choice of the Inclination angle of the acceleration surface is adjustable. This allows the Quality of the solid cake produced, especially for products with which For example, the particle size or the shape of the grains play a role in the end product play, be significantly increased. In very special cases it is even possible to one and the same double push centrifuge in one operation, i.e. essentially at the same time to produce products of different quality, for example the angle of inclination arranged on both sides of the moving floor device Acceleration surfaces are chosen differently.

The essential components as well as the basic functioning of a Double push centrifuges are known from the prior art, so that in following primarily referred to the features essential to the invention can be.

The double-shear centrifuge according to the invention comprises in a manner known per se a sieve drum rotatable about an axis of rotation about a drum axis, which in is housed in a housing. The drum axis stands with one Drum drive in operative connection, so that the sieve drum through the Drum drive can be set in rapid rotation about the axis of rotation. The Sieve drum has sieve openings through which in a known manner faster rotation liquid phase from a mixture on an inner Circumferential surface of the screening drum was applied by the occurring Centrifugal forces can be dissipated to the outside. That on the inner peripheral surface of the Sieve drum applied mixture is so by the prevailing very strong Centrifugal forces in a solid cake, which is on the inner circumferential surface of the Sieve drum deposits, and the liquid phase separated.

In particular, in an example that is particularly important in practice, the Screen drum designed in a manner known per se as a skeletal support drum be used to form the appropriate screen surfaces with special filter foils are lined around their circumference, i.e. the skeletal support drum can for example with one or more filter screens with different or the same large filter openings to separate the liquid phase.

A mixture distributor is arranged within the sieve drum, which allows it Distribute mixture on the peripheral surface of the screening drum, the Mixer distributor with an inlet device and a moving floor device Moving floor plate includes.

In the operating state, the mixture enters the Inlet device and is in a known manner due to an oscillatory Movement of the moving floor device alternately of the front or rear half of the sieve drum feedable. The inlet device is in one preferred embodiment rigidly coupled and rotated with the sieve drum therefore synchronized with the sieve drum and the mixture distributor. The oscillatory However, only the mixture distributor with its components moves, i.e. with the moving floor plate, the connecting element, the moving floor device and the outer ring area. Thus there is a in the operating state oscillatory relative movement between the oscillating mixture distributor and the inlet device, which is immovable in the axial direction, so that the mixture can alternately be fed to the front or rear half of the screening drum.

The moving floor device, which is effective in a special version the sliding floor plate can be connected, is preferably in the form of a Circular disc formed with an outer ring area, the ring area on a peripheral region of the moving floor device and is arranged that with the ring area that deposited in the screening drum Solid cake can be moved alternately in both directions of the axis of rotation.

The push floor plate is connected to a push axis in a manner known per se Coupling device coupled with reversing unit, so that the Moving floor device in the direction of the axis of rotation in an oscillatory movement can be moved with a specifiable stroke. Due to the oscillatory movement of the Moving floor device is the one deposited on the peripheral surface of the screening drum Solid cake through the outer ring area alternately in both directions The axis of rotation can be moved so that the solid cake through the outer Ring area can be transported in the axial direction to the respective end of the screening drum and is separated from the liquid phase via a discharge opening Double push centrifuge is removable.

It is essential for the invention that the moving floor device in one predeterminable area in the form of acceleration surfaces is designed such that the mixture introduced by the feed device before reaching the Screen drum can be accelerated to a predetermined circumferential speed.

For this purpose, the mixture from the feed device is alternately one at a time Side of the moving floor device supplied. If the mixture in the Infeed device not already at a predeterminable peripheral speed can be pre-accelerated, the mixture essentially comes under the action of Gravity on a corresponding surface of the moving floor device and finally reaches the radial direction under a predeterminable Inclination angle inclined acceleration surface. The mixture overflows or along the acceleration surface and thus reaches the peripheral surface of the Screen drum. Here the mixture gets into the through the oscillatory movement of the Moving floor device created empty space on the peripheral surface of the Sieve drum, and is based on the rotation speed of the sieve drum accelerated. Due to the enormously high centrifugal forces on the in the empty space deposited mixture act, the liquid phase contained in the mixture the screen openings are removed from the screen drum.

In that the acceleration surface is inclined against the radial direction in the area of the acceleration surface the flow velocity compared to the Velocity targeted in the free fall of the mixture towards the peripheral surface changeable so that the mixture in the area of the acceleration surfaces increasing approach to the outer ring area gradually accelerated is. This means that the mixture is in the area of the acceleration double-push centrifuge according to the invention in a particularly gentle manner and after accelerated to a predefinable peripheral speed, then at Finally, the full rotation speed of the peripheral surface is reached To reach the sieve drum.

The value of the angle of inclination of the acceleration surface against the radial Direction can be between 0 ° and 90 °, for example between 10 ° and 30 ° or between 30 ° and 60 °, in particular between 60 ° and 70 °, but preferably between 55 ° and 75 °. Of course it is special it is also possible that the value of the angle of inclination is greater than 70 ° and even close can be at 90 °. In general it can be stated that in Regarding the radial direction a rather not too acute angle is advantageous, whereby an optimal value of the corresponding angle of inclination, among other things, of the value of the static friction angle of the product to be dewatered.

The acceleration surfaces can either cover only a partial area extend the moving floor device or even over the entire radial Height of the moving floor device, the moving floor device depending on Requirement in whole or in part as a substantially hollow frame or entirely or can be partially constructed from solid material. Of course it is possible that the two acceleration surfaces are the same or different Can have inclination angle.

In an exemplary embodiment that is particularly relevant for practice Double-thrust centrifuge according to the invention is the acceleration surface as Filter screen designed to separate the liquid phase from the mixture. there Both acceleration surfaces are preferably designed as a filter screen. Of course, only one acceleration surface can be used as a filter screen be configured, or the two acceleration surfaces can each have differently designed filter screens. The two can different filter screens made of different materials, for example or the size of the filter pores can be different. This makes it possible two different ones from the same mixture in the same operation Solid cakes of different quality, i.e. with different To produce properties.

In particular, in an embodiment that is particularly important in practice the acceleration surface as a filter screen on a skeletal support body be arranged to form the filter screen with special filter foils can be equipped, i.e. the skeletal support body can, for example, with one or more filter screens, which may be used for separation in different Stages can have filter openings of different sizes.

In general, filter screens include slotted screens or for example screen plates in question. The filter screens can be advantageous provide filter openings of different sizes in different ways become. In particular, the previously mentioned screen plates can among others punched, drilled, lasered, electron beam punched or water jet cut be, whereby in principle other techniques are also possible. The sieves themselves can, depending on requirements, 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 be made of other suitable materials. To protect against The filter screens can also wear with suitable layers be provided, for example with hard chrome layers, tungsten carbide (WC), Ceramic or otherwise hardened. The thickness of the filter plates is typically 0.2 mm to 5 mm, although significantly different sheet thicknesses are also possible are.

Especially for processing particularly sensitive mixtures Infeed device an inlet funnel for pre-accelerating the mixture include. As a result, the mixture is already in the Mixer distributor can be pre-accelerated to a specifiable rotation speed and therefore more gently treatable. The speed of rotation is up which the mixture can already be pre-accelerated in the inlet funnel, for example by choosing the size and / or the opening angle of the inlet funnel predetermined.

The inlet funnel can also be independent of the mixture distributor by one separate drive shaft rotatably arranged and by means of a drive with a Predeterminable speed designed and arranged rotatable about the drive axis his. This means that the pre-acceleration is independent of the geometry of the Inlet funnel freely selectable by setting the speed of the drive. In particular, suitable devices for control and / or regulation can be used be provided so that, for example, the speed during operation of the drive is freely variable. For example, the quality of the Solid cake customizable, or it is for example by suitable control and / or regulating the speed of the drive and thus the inlet funnel on the right and to the left of the moving floor device in one and the same Double-shear centrifuge from a mixture a different product quality produced.

The inlet funnel can also advantageously be used as a pre-filter screen for the pre-separation of Liquid phase can be formed from the mixture, preferably collecting agent intended for collection and discharge of the liquid phase from the pre-filter screen are. This means that even mixtures with a very high liquid content are problem-free processable. The pre-separation of liquid phase has already in the inlet funnel furthermore the enormous advantage that this part of the liquid phase is no longer accelerated to the very high rotational speed of the screening drum, what among other things, particularly favorably on the energy consumption of the Double push centrifuge affects.

Both the filter screen of the acceleration surfaces and that Pre-filter screen designed as a two-stage screen with a coarse filter and a fine filter his. The mixture is thereby in the area of the acceleration surface and / or Inlet funnel can be filtered in two stages. The first filter stage forms one Coarse filter, which contains particles in the mixture that are larger than that Retains filter openings of the coarse filter. The fine filter holds correspondingly finer Particles return during at least part of the liquid phase, as well as very small ones Particles that also have to be removed can be removed directly. The Design as a two-stage sieve has the particular advantage that the fine filter through large and / or heavy particles contained in the incoming mixture are not so mechanically stressed, so that the fine filter, for example can have very small pores for filtering very small particles and in particular also made of mechanically less resistant materials can be.

In another embodiment variant of the invention The double distributor centrifuge includes one Pre-acceleration funnel, which essentially widens towards Feed device extends.

The value of the opening angle of the inlet funnel and / or the value of the The pre-acceleration angle of the pre-acceleration funnel can be related on the axis of rotation, for example, between 0 ° and 45 °, specifically between 0 ° and 10 ° or between 10 ° and 45 °, in particular between 25 ° and 45 °, are preferably between 15 ° and 35 °. Of course it is in particular too possible that the value of the opening angle and / or the Pre-acceleration angle is greater than 45 °. In general, can be found that, as a rule, a rather acute angle of The advantage is that an optimal value of the corresponding opening angle and / or of the pre-acceleration angle, among other things, from the value of the static friction angle of the dewatering product.

The pre-acceleration funnel can also be used in the same way as the inlet funnel Pre-acceleration screen to be designed, with the mixture distributor Collection devices for removing liquid phase can be provided.

In an embodiment that is particularly important in practice, the Inlet funnel and / or the pre-acceleration funnel as a skeletal Support body can be designed to form the pre-filter screen and / or Pre-acceleration screen can be equipped with special filter foils, i.e. the skeletal support bodies can, for example, with one or more filter screens, which may have different sizes for separation in different stages Can have filter openings.

In general, filter screens include slotted screens or for example screen plates in question. The filter screens can be advantageous provide filter openings of different sizes in different ways become. In particular, the previously mentioned screen plates can among others punched, drilled, lasered, electron beam punched or water jet cut be, whereby in principle other techniques are also possible. The sieves themselves can, depending on requirements, 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 be made of other suitable materials. To protect against The filter screens can also wear with suitable layers be provided, for example with hard chrome layers, tungsten carbide (WC), Ceramic or otherwise hardened. The thickness of the filter plates is typically 0.2 mm to 5 mm, although significantly different sheet thicknesses are also possible are.

In particular, the pre-acceleration funnel can also be designed and be arranged that the pre-acceleration funnel by means of a rotary drive an axis of rotation can be rotated at a predeterminable speed.

Both the inlet funnel and the Pre-acceleration funnel preferably under a substantially constant Opening angle widening towards the moving floor device or Feed device out. The value of the pre-acceleration angle of the Pre-acceleration funnel can, for example, with respect to the axis of rotation lie 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 in particular that the value of the Pre-acceleration angle is greater than 45 °. In general, can be found that, as a rule, a rather acute angle of The advantage is being an optimal value of the corresponding pre-acceleration angle including the value of the stiction angle of the product to be dewatered is determined.

For special applications, for example depending on the properties of the mixture to be dewatered, the inlet funnel and / or the However, a pre-acceleration funnel in a predeterminable range also has one have a curved course, the opening angle of the inlet funnel and / or increase the pre-acceleration angle of the pre-acceleration funnel or downsize.

In particular, but not only when the inlet funnel is designed as a pre-filter screen for pre-separating liquid phase, it can be particularly advantageous if the inlet funnel has a curved course and the opening angle of the inlet funnel increases or decreases in the direction of the moving floor device. It is known that different products can be dewatered differently under otherwise identical operating conditions of the double-shear centrifuge, for example depending on the grain size and / or the viscosity and l or other properties or parameters such as the temperature of the mixture.

For example, there is a mixture that is relative for given operating parameters is easy to drain, it can be advantageous that the inlet funnel or Pre-filter screen has a curved course, the opening angle of the Pre-filter screen enlarged towards the moving floor device. That is, the Inlet funnel or the prefilter sieve widens towards Moving floor device similar to the horn of a trumpet. With that the Downforce with which the mixture is accelerated from the inlet funnel with decreasing distance to the moving floor device disproportionately larger, see above that the mixture, which is already relatively heavily dewatered in the pre-filter screen, and so that it shows poor sliding properties in the pre-filter screen, the pre-filter screen faster can leave, for example, with an essentially conical shape, with constant opening angle widening pre-filter screen.

On the other hand, there may also be mixtures given for Operating parameters are relatively difficult to drain. In this case, it is recommended itself, an inlet funnel or a pre-filter screen with a curved course to use, the opening angle of the prefilter towards Moving floor device reduced. As a result, the downforce, with which accelerates the mixture from the inlet funnel, with decreasing Distance to the moving floor device increases more slowly than, for example, at one is conical at a substantially constant opening angle expanding inlet funnel. This creates one in the pre-acceleration screen certain accumulation effect, so that the mixture stays longer in the pre-filter and can therefore be dewatered to a higher degree in the pre-filter screen.

Of course, the same can be done in exactly the same way as the one predicted Pre-acceleration funnel have a curved course, the Pre-acceleration angle of the pre-acceleration funnel towards Feeder device enlarged or reduced.

Those previously explained in connection with the curved inlet funnel Advantages and its mode of operation are analogous to those skilled in the art a curved pre-acceleration funnel, and therefore must be here not be repeated.

It goes without saying that the characteristics of the previously exemplary described particularly preferred embodiments of the Double-shear centrifuge according to the invention, depending on requirements, also arbitrarily in can advantageously be combined.

Fig. 1

im Schnitt eine erfindungsgemässe Doppelschubzentrifuge mit Beschleunigungsflächen;

Fig. 1a

einen Abschnitt der Schubbodenvorrichtung mit Beschleunigungsflächen und äusserem Ringbereich;

Fig. 1 b

ein Ausführungsbeispiel einer Beschleunigungsfläche;

Fig. 1 c

ein zweites Ausführungsbeispiel gemäss Fig. 1 b;

Fig. 2

ein Ausführungsbeispiel einer erfindungsgemässen Doppelschubzentrifuge mit Filtersieb;

Fig. 2a

ein anderes Ausführungsbeispiel gemäss Fig. 2 mit Zweistufensieb;

Fig. 3

ein weiteres Ausführungsbeispiel mit Einlauftrichter;

Fig. 4

eine andere Ausführungsvariante gemäss Fig. 3;

Fig. 5

eine weitere Ausführungsvariante gemäss Fig. 4;

Fig. 6

eine Doppelschubzentrifuge mit Vorbeschleunigungstrichter;

Fig. 7

ein Ausführungsbeispiel gemäss Fig .6 mit Vorbeschleunigungssieb;

Fig. 7a

einen Einlauftrichter mit gekrümmtem Verlauf;

Fig. 7b

einen anderen Einlauftrichter gemäss Fig. 7a;

Fig. 8

einen Vorbeschleunigungstrichter mit Drehantrieb.

The invention is explained below with reference to the schematic drawing. Show it:

Fig. 1

on average an inventive double-thrust centrifuge with acceleration surfaces;

Fig. 1a

a section of the moving floor device with acceleration surfaces and an outer ring area;

Fig. 1 b

an embodiment of an acceleration surface;

Fig. 1 c

a second embodiment of FIG 1b.

Fig. 2

an embodiment of a double-push centrifuge according to the invention with filter screen;

Fig. 2a

another embodiment according to FIG 2 with two-stage sieve.

Fig. 3

another embodiment with inlet funnel;

Fig. 4

another embodiment variant according to FIG. 3;

Fig. 5

a further embodiment variant according to FIG. 4;

Fig. 6

a double push centrifuge with pre-acceleration funnel;

Fig. 7

an embodiment of FIG 6 with pre-acceleration screen.

Fig. 7a

an inlet funnel with a curved course;

Fig. 7b

another inlet funnel according to FIG. 7a;

Fig. 8

a pre-acceleration funnel with rotary drive.

1 shows a section of essential components in a schematic representation a double-push centrifuge according to the invention. The inventive Double-shear centrifuge, all of which is referred to below as reference number 1 is referred to, includes in a manner known per se about an axis of rotation 2 a drum axis 31 rotatable sieve drum 3, which in a housing G is housed. The drum axis 31 stands with one, not shown Drum drive in operative connection, so that the drum 3 through the Drum drive can be set in rapid rotation about the axis of rotation 2. The Sieve drum has sieve openings 32 through which in a known manner faster rotation liquid phase 6 from a mixture 4, which on an inner Circumferential surface 20 of the drum 3 was applied by the occurring Centrifugal forces can be dissipated to the outside in a collecting device 18. That on the inner peripheral surface 20 of the mixture 3 applied mixture 4 is thus the prevailing very strong centrifugal forces in a solid cake 5, which is on the deposits inner peripheral surface 20 of the drum 3, and the liquid phase 2, the through the sieve openings 32 can be removed from the sieve drum 3, separated.

A mixture distributor 7 is arranged within the sieve drum 3, which allows it Distribute mixture 4 on the inner peripheral surface 20 of the screening drum 3, wherein the mixture distributor 7 has an inlet device 17 and a moving floor device 8 with sliding floor plate 81.

The mixture 4 arrives in the operating state via the feed device 10 Inlet device 17 and is then due to an oscillatory movement of the Moving floor device 8 alternately the front or rear half of the Sieve drum 3 can be fed. The inlet device 17 is with the sieve drum 3 preferably rigidly coupled by fastening means and therefore rotates synchronously with the sieve drum 3 and the mixture distributor 7. The oscillatory movement, which is described in more detail below, is only carried out by Mixer distributor 7 with its components, i.e. with the sliding floor plate 81, the Connecting element 82, the moving floor device 8 and the outer Ring area 9. Thus there is an oscillatory in the operating state Relative movement between the oscillating mixture distributor 7 and that in the axial In the direction of the immovable inlet device 17 or in the axial direction immovable feed device 10, so that the mixture 4 alternately the front or rear half of the drum 3 can be fed.

The sliding floor device 8 is operatively connected to the connecting element 82 Sliding floor plate 81 connected. The moving floor device 8 is preferred in the form of a circular disc with an outer ring region 9, the Ring area 9 on a peripheral area of the moving floor device 8 so is formed and arranged that the ring area 9 in the sieve drum 3 deposited solid cake 5 alternately in both directions of the axis of rotation 2 is movable. The sliding floor plate 81 is also preferred as a ring sheath 81 trained, but can also in the form of a spoke wheel 81 or in any other suitable form. The connecting element 82, the Moving floor plate 81 connects effectively with the moving floor device 8, can for example, be constructed from several struts 82, which are preferred, however not necessary to extend along the axis of rotation 2, or as compact or not compact drum 82, for example as a perforated drum 82 or in each other suitable shape.

The push floor plate 81 is connected to a not shown by means of a push axis 16 Push device coupled to reversing unit, so that the push floor plate 81 with the connecting element 82 and the moving floor device 8 in the direction of Axis of rotation 2 can be set into an oscillatory movement with a specifiable stroke. Due to the oscillatory movement of the moving floor device 8 is on the Circumferential surface of the sieve drum 3 deposited solid cake 5 through the outer ring area 9 alternately in both directions of the axis of rotation 2 displaceable so that the solid cake through the outer ring area 9 in Axial direction to the respective end of the drum 3 is transportable and a discharge opening 19 separated from the liquid phase 6 from the Double push centrifuge 1 can be removed.

It is essential for the invention that the moving floor device 8 in one predeterminable area in the form of acceleration surfaces 12 is configured that the mixture 4 introduced by the feed device 10 before reaching the Sieve drum 3 can be accelerated to a predetermined circumferential speed.

Fig. 1a shows a schematic representation of a section of the Moving floor device 8 with acceleration surfaces 12 and the outer Ring area 9. In the embodiment shown in FIG. 1a, mixture 4 is made a feed device 10, not shown here, as shown on the right Side of the moving floor device 8 fed. Essentially under the effect of The mixture 4 reaches a corresponding surface of gravity Push floor device 8 and finally reaches the radial one Direction at an angle of inclination γ inclined acceleration surface 12. Das Mixture 4 flows over or along the acceleration surface 12 and thus arrives onto the peripheral surface 20 of the screening drum 3. Here the mixture 4 reaches the created by the oscillating movement of the moving floor device 8 Empty space 11 on the peripheral surface 20 of the drum 3 and is on the Speed of rotation of the screening drum accelerates. Because of the enormously high Centrifugal forces that act on the mixture 4 deposited in the empty space 11, the in Mixture 4 contained liquid phase 6 through the sieve openings 21 from the Screen drum 3 discharged.

The fact that the acceleration surface 12 against the angle of inclination γ radial direction is inclined in the area of the acceleration surface 12 Flow speed compared to the speed in the free fall of the mixture 4 can be specifically changed in the direction of the peripheral surface 20, so that the mixture 4 in Area of the acceleration surfaces 12 with increasing approach to the outer ring area 9 is gradually accelerated. That means the mixture will in the area of the acceleration surfaces 12 in a particularly gentle manner and then accelerated to a predefinable peripheral speed and then at Finally, the full rotation speed of the peripheral surface 20 is reached To reach sieve drum 3.

The acceleration surfaces 12 can, as shown schematically in FIG. 1 a shown, either only over a portion of the moving floor device 8 extend or over the entire radial height of the Moving floor device 8, the moving floor device 8 depending on the requirement in whole or in part as a substantially hollow frame 8 or in whole or partly made of solid material.

In Fig. 1 b is a section of a special embodiment of a Acceleration surface 12 with an outer ring area 9 for shifting the here Festoff cake 5, not shown. The outer ring area 9 has a predeterminable height a which, depending on the mixture to be processed 4 and / or Operating conditions under which the double-shear centrifuge 1 is operated, about 1% to 40% of the drum radius r, preferably about 5% to 10%, is in particular 5% to 20% of the drum radius r.

1 c, the acceleration surface 12 can also be designed as a multi-stage acceleration surface 12, the acceleration surface 12 for pre-acceleration of the mixture 4 having several partial surfaces inclined at different angles ϕ ₁ , ϕ ₂ , the relative the size of the partial surface and its surface angle ϕ ₁ , ϕ ₂ can depend, for example, on the mixture 4 to be processed or on the operating parameters of the double-push centrifuge 1.

The fact that the mixture, unlike those from the prior art known double-thrust centrifuges, not in the area of the acceleration surfaces abrupt, i.e. to the full rotation speed of the screening drum in the shortest possible time 3 accelerated are, for example, broken grain and other harmful Effects on the mixture 4 can be prevented. So that are in the Double-push centrifuge 1 according to the invention, in particular also very mechanically sensitive fabrics, even at high rotation speeds of the drum 3 processable.

Fig. 2 shows a preferred embodiment of an inventive Double thrust centrifuge 1, in which the acceleration surface 12 as a filter screen 121 for separating the liquid phase 6 from the mixture 4 is formed. there is the moving floor device 8 at least in the area of the acceleration surfaces 12 at least partially designed as a hollow body. As a result, the mixture 4 already while it glides and accelerates over the acceleration surface 12 becomes part of the liquid phase 6 separable via the filter sieve 121 and can by a sieve opening 21 can be removed from the sieve drum 3. So are also Mixtures 4 with a very high liquid content can be processed easily. In particular, even with a high liquid content, it is always uniform Distribution of the mixture 4 to be dried over the peripheral surface 20 of the Sieve drum 3 guaranteed. In particular, even at very high Liquid concentrations in the mixture 4 additional devices for Pre-drainage, such as static thickeners, curved screens or No need for hydrocyclones. Even the smallest ones contained in the mixture 4 can Particles much more effectively from the solid cake 5 due to the effect of prefiltration be deposited.

FIG. 2a shows another embodiment according to FIG. 2, the Filter screen 121 as a two-stage screen with a coarse filter 122 and a fine filter 123 is designed. The mixture 4 can thereby in the area of the acceleration surface 12 can be filtered in two stages. The coarse filter 122 forms the first filter stage, which contains particles in the mixture that are larger than the filter openings of the Coarse filter 122 holds back, which can be inserted directly into the empty space 11. The Fine filter retains correspondingly finer particles, which also hold space 11 and thus the solid cake 5 can be fed, while at least part of the Liquid phase 6, as well as very small particles that also have to be removed, can be removed directly from the sieve drum 3 through the sieve opening 21. The Designing the filter screen 121 as a two-stage screen has the particular advantage that the fine filter 123 due to large and / or heavy particles in the incoming Mixture 4 are included, is not mechanically stressed so that the Fine filter 123, for example, very small pores for filtering very small ones May have particles and in particular mechanically little resistant materials can be made.

3 schematically shows a further exemplary embodiment of an inventive one Double-shear centrifuge 1 shown. In this embodiment, the Infeed device 10 an inlet funnel 101 for pre-accelerating the Mixture 4. The mixture passes through the inlet device which, as in FIG. 3 shown as an example, comprises an inlet pipe, first into an inlet funnel 101, which is rotatably connected to the inlet device 17, so that the inlet funnel 101 rotates synchronously with the moving floor device 8. The extends Inlet funnel 101 in an essentially axial direction to the feed device 10 so that the mixture 4 supplied by the feed device 10 directly into reaches the inlet funnel 101. The inlet funnel 101 is designed and arranged that the mixture 4 depending on when leaving the inlet funnel 101 axial position of the mixture distributor 7 in one of the two drum halves over the Moving floor device can be fed.

The fact that the inlet funnel 101 in the direction of the mixture distributor 7 in extends substantially conically and the inlet funnel rotates synchronously, the mixture 4 is already in the inlet funnel 101 to a predetermined Pre-accelerated rotation speed, so that the mixture 4 on arrival already a certain speed in on the acceleration surface 12 Has circumferential direction of the screening drum 3 and so even more gently the maximum peripheral speed of the peripheral surface 20 can be accelerated. The acceleration surface 12 is preferred, but not necessary, as shown in FIG. 3, designed as a filter screen 121.

In practice, it may be advantageous to use the acceleration process itself Rotation speed to which the mixture can be accelerated in the inlet funnel 101 is to control specifically. This is, for example, the one shown in FIG. 4 other embodiment variant according to FIG. 3 achievable. In the variant 4, the inlet funnel 101 is mechanically in from the inlet device 17 essentially decoupled. To control and / or regulate the Rotational speed of the inlet funnel 101 is this with a separate one Drive axis 131 connected in a rotationally fixed manner and via the drive axis 131 by means of a Drive 13 independently of the screening drum 3 with a predeterminable Rotation frequency drivable. Suitable means, not shown here, can be used be provided to drive 13, for example, depending on suitable To control and / or regulate the operating parameters of the double-push centrifuge 1. For this purpose, the double-push centrifuge according to the invention can also be used here sensors, not shown, for measuring relevant operating parameters include.

FIG. 5 shows a further particularly advantageous embodiment variant according to FIG. 4. In this embodiment variant, the inlet funnel 101 is used as a prefilter sieve 102 Pre-separation of liquid phase 6 from mixture 4 is formed. Here is the Inlet funnel 101 configured in such a way and in relation to one in the sieve drum 3 provided collecting means 14 that already during the pre-acceleration of the mixture 4 in the inlet funnel 101 through the pre-filter screen 102 at least a part the liquid phase 6 separable from the mixture 4 into the collecting means 14 and from the sieve drum 3 can be removed. This makes it possible to mix even with enormous high liquid content with the double-shear centrifuge according to the invention to process. It is particularly advantageous in practice if part of the Liquid phase 6 is deposited before entering the mixture distributor 7. This part of the liquid phase 6 is no longer full The peripheral speed of the screening drum accelerates, resulting in a massive Saving energy and relieving the components, especially the rotating and / or oscillating components of the double push centrifuge 1 leads.

The inlet funnel 101 or the prefilter sieve 102 points in relation to the Axis of rotation 2 has an opening angle α which, in relation to the axis of rotation 2 can for example be between 0 ° and 45 °, in particular between 0 ° and 10 ° or between 10 ° and 45 °, in particular between 25 ° and 45 °, preferred can be between 15 ° and 35 °. Of course it is in particular too possible that the value of the opening angle α is greater than 45 °. This is in Inlet funnel 101 or in the prefilter sieve 102 the flow rate of the mixture 4 compared to the speed in free fall towards the screening drum 3 selectively changeable so that the mixture 4 in the area of the inlet funnel 101 or of the pre-filter screen 102 can be accelerated gradually. This means that the mixture 4 is in the Area of the pre-filter screen 102 gradually in a particularly gentle manner a predeterminable peripheral speed can be accelerated.

6 shows a variant of a double-shear centrifuge according to the invention Pre-acceleration funnel 71. The pre-acceleration funnel 71 is in this Variant arranged on the inlet device 17 and rotatably connected to this. The inlet funnel 101 rotates synchronously with the moving floor device 8 the pre-acceleration funnel 71 extends in a substantially axial direction to the feed device 10 so that the feed device 10 supplied mixture 4 goes directly into the pre-acceleration funnel 71. It is the pre-acceleration funnel 71 is designed and arranged such that the Mixture 4 when leaving the pre-acceleration funnel 71 depending on the axial Position of the mixture distributor 7 in one of the two drum halves over the Moving floor device can be fed.

The fact that the pre-acceleration funnel 71 in the direction of Mixer distributor 7 extends substantially conically and the Inlet funnel rotated synchronously, the mixture 4 is already in the inlet funnel 101 pre-accelerated to a predeterminable rotational speed, so that the mixture 4 already a certain one upon arrival on the acceleration surface 12 Has speed in the circumferential direction of the screening drum 3 and so overall even more gently on the maximum peripheral speed of the peripheral surface 20 is accelerable.

Another exemplary embodiment according to FIG. 6 that is important in practice is shown in FIG. 7 shown schematically. In this variant, the Pre-acceleration funnel 71 as pre-acceleration screen 72 for pre-separation of liquid phase 6 formed from the mixture 4. Here is the Pre-acceleration funnel 71 configured and in this way with respect to one in the Screening drum 3 provided collecting device 73 arranged that already at the Pre-acceleration of the mixture 4 in the pre-acceleration funnel 71 by the Pre-acceleration screen 72 at least part of the liquid phase 6 from the mixture 4 can be separated into the collecting device 73 and can be removed from the screening drum 3. This makes it possible to also use mixtures with an extremely high liquid content this embodiment variant of the double-push centrifuge 1 according to the invention to process. It is particularly advantageous in practice if part of the Liquid phase 6 is deposited before entering the mixture distributor 7. This part of the liquid phase 6 is no longer full The peripheral speed of the screening drum 3 accelerates, resulting in a massive Saving energy and relieving the components, especially the rotating and / or oscillating components of the double push centrifuge 1 leads.

The pre-acceleration funnel 71 or the pre-acceleration screen 72 has with respect to the axis of rotation 2 on a pre-acceleration angle β, which in relation on the axis of rotation 2 can be between 0 ° and 45 °, for example between 0 and 10 ° or between 10 ° and 45 °, in particular between 25 ° and 45 °, can preferably be between 15 ° and 35 °. Of course it is special it is also possible that the value of the pre-acceleration angle β is greater than 45 °. As a result, the flow velocity of the mixture is in the pre-acceleration screen 72 4 compared to the speed in free fall towards the screening drum 3 selectively changeable so that the mixture 4 in the area of Pre-acceleration funnel 71 or the pre-acceleration screen 72 gradually is accelerable. That is, the mixture 4 is in the range of Pre-acceleration screen 72 gradually in a particularly gentle manner a predeterminable peripheral speed can be accelerated, then when reached the peripheral surface 20 of the drum 3, finally the full To achieve the speed of rotation of the screening drum 3.

In particular, but not only when, for example, the inlet funnel 101 is designed as a pre-filter screen 102 for pre-separating liquid phase 6, it can be of particular advantage if the inlet funnel 101 or the prefilter sieve 102 has a curved shape and the opening angle α of the inlet funnel 101 as shown schematically in FIGS. 7a and 7b, towards Moving floor device 8 enlarged or reduced. It is known that that different mixtures 4 under otherwise identical operating conditions Double-shear centrifuge 1, for example depending on the grain size and / or the viscosity and / or other properties or parameters, such as Example of the temperature of the mixture 4, can be dewatered differently.

For example, there is a mixture 4 that is given given operating parameters is relatively easy to drain, it may be advantageous for the inlet funnel 101 or the pre-filter screen 102 has a curved course, the Opening angle α of the prefilter sieve 102 in the direction of the moving floor device 8 increased. Such a special embodiment of an inlet funnel 101 is shown schematically in Fig. 7a. That is, the inlet funnel 101 or the Pre-filter screen 102 widens in the direction of moving floor device 8 similarly the horn of a trumpet. This is the downforce with which the mixture 4 from the inlet funnel 101 is accelerated with decreasing distance from Moving floor device 8 disproportionately larger, so that the mixture 4, the is already relatively heavily dewaterable in the pre-filter sieve 102 and is therefore poor Sliding properties in the pre-filter screen 102 shows, faster the pre-filter screen 102 can leave, for example, with an essentially conical shape, with constant opening angle α widening pre-filter sieve 102.

On the other hand, there may also be mixtures 4 given for Operating parameters are relatively difficult to drain. In this case, it is recommended itself, an inlet funnel 101 or a pre-filter screen 102 with a curved Use course, wherein the opening angle α of the pre-filter screen 102 in Reduced direction towards moving floor device 8. As a result, the Output force with which the mixture 4 is accelerated from the inlet funnel 101, with decreasing distance to the moving floor device 8 increases more slowly than for example, one that is below a substantially constant Opening angle α conically expanding inlet funnel 101 Pre-filter screen 102 has a certain accumulation effect, so that the mixture 4 in the longer Pre-filter sieve 102 remains and therefore already in the pre-filter sieve 102 to a higher one Degrees can be drained.

Of course, the same can be done in exactly the same way as the one predicted Pre-acceleration funnel 71 and the pre-acceleration screen 72 one have a curved course, the pre-acceleration angle β of the Pre-acceleration funnel 71 in the direction of the feed device 10 enlarged or reduced.

Of course, it is also possible, as shown schematically in FIG. 8, that the pre-acceleration funnel 71 is designed and arranged such that the Pre-acceleration funnel 71 by means of a rotary drive 15 about an axis of rotation 151 is rotatable at a predeterminable speed. The axis of rotation 151, as exemplified in Fig. 8, arranged within the axis of rotation 2 and are driven independently of this by the rotary drive 15. For controlling and / or regulation of the rotational speed of the rotary drive 15 can suitable means, not shown here, can be provided for the rotary drive 15 for example depending on suitable operating parameters of the To control and / or regulate the double-thrust centrifuge 1.

It is of course also the case with the embodiment variant shown in FIG. 8 possible that completely analogous to the embodiment of the Pre-acceleration funnel 71 as pre-acceleration screen 72 for pre-separation is designed by liquid phase 6 and also suitable collecting means for Removing the liquid phase 6 deposited on the pre-acceleration screen 72 are provided.

It goes without saying that the previously explained and in the Diagrams of embodiment variants shown schematically also arbitrarily can be combined with each other to form further specific embodiments To meet requirements in practice.

By using the double-push centrifuge according to the invention, this can introduced mixture through the two sides of the moving floor device arranged acceleration surfaces to a predetermined circumferential speed be pre-accelerated so that the mixture when it hits the sieve drum not in the shortest possible time from a peripheral speed close to zero to full The peripheral speed of the screening drum is accelerated. This is under other grain breakage avoidable, so that in particular also substances that particularly sensitive to abrupt changes in centrifugal acceleration react, are processed in compliance with the highest quality standards.

In addition, in the various preferred design variants, extremely low inlet concentrations can also be processed, which correspond to 50% or 70% or 80% or even more than 90% of the liquid phase. In particular, by means of the filter screen and / or the pre-filter screen and 1 or the pre-acceleration screen, it is possible to process mixtures with almost any liquid content without the mixture having to be pre-thickened in complex processes. In this way, even with a high liquid content, it is always ensured that the mixture to be dried is evenly distributed over the inner peripheral surface of the sieve drum. On the one hand, this prevents very damaging vibrations of the sieve drum and thus premature wear of the bearings and drive, and effectively prevents safety problems in operation. In addition, problems with washing the solid cake are largely avoided by its uneven distribution over the circumferential surface of the sieve drum. The use of pre-drainage systems, which are very complex both in terms of process technology and equipment, is also avoided, which of course leads to considerable cost savings in operation.

When using the filter systems mentioned above, the entire system no longer has to be used Amount of liquid phase that is supplied with the mixture to the full The peripheral speed of the screening drum can be accelerated. This is especially with a view to the energy consumption of the double push centrifuge extremely cheap and also influences the operating behavior of the centrifuge overall clearly positive.

By appropriate different design of the different Filter areas or by using the inlet funnel and / or one Pre-acceleration funnel with its own drive, it is even possible in one and the same double push centrifuge and in one and the same operation from the Mix two different solid cakes of different quality, i.e. With to produce different properties.

Claims (14)

Comprising a double pusher centrifuge, a sieve drum (3) rotatable about an axis of rotation (2) for separating a mixture (4) into a solid cake (5) and a liquid phase (6), a mixture distributor (7) arranged in the sieve drum (3) with a moving floor device (8), which can be moved back and forth along the axis of rotation (2), so that the solid cake (5) can be moved alternately with an outer ring area (9), and with a feed device (10) with which the mixture (4 ) can be introduced via the mixture distributor (7) into an empty space (11), which is created adjacent to the outer ring area (9) when the solid cake (5) is moved by the moving floor device (8), characterized in that the moving floor device (8) on both sides Has acceleration surfaces (12) which are inclined with respect to the radial direction at a predeterminable angle of inclination (γ), so that the mixture (4) introduced by the feed device (10) is in front Reaching the screening drum (3) can be accelerated to a predetermined circumferential speed. A double pusher centrifuge according to claim 1, wherein the acceleration surface (12) as a filter screen (121) for separating liquid phase (6) from the mixture (4) is trained. Double-shear centrifuge according to claim 1 or 2, wherein the filter screen (121) as Two-stage sieve with a coarse filter (122) and a fine filter (123) is. Double-shear centrifuge according to one of the preceding claims, wherein the Feed device (10) an inlet funnel (101) for pre-accelerating the Mixture (4), which is below a substantially constant Opening angle (α) expanding conically towards the moving floor device (8) extends. Double-shear centrifuge according to one of the preceding claims, wherein the Inlet funnel (101) has a curved course and the opening angle (α) of the inlet funnel (101) towards the moving floor device (8) increased. Double-shear centrifuge according to one of the preceding claims, wherein the Inlet funnel (101) has a curved course and the opening angle (α) of the inlet funnel (101) towards the moving floor device (8) reduced. Double-shear centrifuge according to one of the preceding claims, wherein the Inlet funnel (101) rotatably arranged about a drive axis (131) and by means of a drive (13) with a predeterminable speed about the drive axis (131) is rotatable. Double-shear centrifuge according to one of the preceding claims, wherein the Inlet funnel (101) as a pre-filter screen (102) for pre-separation of the liquid phase (6) is formed from the mixture (4). Double-shear centrifuge according to one of the preceding claims, in which Collection means (14) for collecting and deriving the liquid phase (6) from the Pre-filter screen (102) are provided. Double-shear centrifuge according to one of the preceding claims, wherein the Mixture distributor (7) comprises a pre-acceleration funnel (71) conical at a substantially constant pre-acceleration angle (β) extends towards the feed device (10). Double-shear centrifuge according to one of the preceding claims, wherein the Pre-acceleration funnel (71) has a curved course and the Pre-acceleration angle (β) of the pre-acceleration funnel (71) in the direction enlarged towards the feed device (10). Double-shear centrifuge according to one of the preceding claims, wherein the Pre-acceleration funnel (71) has a curved course and the Pre-acceleration angle (β) of the pre-acceleration funnel (71) in the direction reduced to the feed device (10). Double-shear centrifuge according to one of the preceding claims, wherein the Pre-acceleration funnel (71) is designed as a pre-acceleration screen (72) and on the mixture distributor (7) collecting devices (73) for discharging Liquid phase (6) are provided. Double-shear centrifuge according to one of the preceding claims, wherein the Pre-acceleration funnel (71) is designed and arranged such that the Pre-acceleration funnel (71) by means of a rotary drive (15) Rotation axis (151) is rotatable at a predeterminable speed.

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