EP2913112B1 - Centrifuge, and method for loading a centrifuge - Google Patents

Description

The invention relates to a centrifuge, in particular a double-thrust centrifuge, or a single-stage or multi-stage thrust centrifuge, and a feed reversal for a centrifuge, and a method for loading a centrifuge with a mixture or with a washing fluid according to the preamble of independent claims 1, 14 and 15.

In the context of this application, the invention is primarily discussed using the example of use in a double-shear centrifuge. It goes without saying that the invention can equally advantageously be used in any other type of centrifuge, in particular also in single-stage or multi-stage pusher centrifuges and in special cases even in peeling centrifuges, which are therefore all covered by the present application.

For the dehumidification of materials loaded with liquids, that is, of moist substances or moist substance mixtures, centrifuges in a wide variety of designs are widely used and are used in a wide variety of fields. For example, discontinuous centrifuges, such as peeling centrifuges, are preferably used to dehumidify high-purity pharmaceutical products, while continuously operating batch centrifuges are advantageously used, particularly when large quantities of a solid-liquid mixture are to be separated. Depending on the requirements, single or multi-stage pusher centrifuges, as well as so-called double pusher centrifuges, are advantageously used in practice.

In the various types of the last-mentioned class of double-shear centrifuges, a solid-liquid mixture, for example a suspension or another moist substance mixture, such as a moist salt or salt mixture, is passed through an inlet pipe via a mixture distributor of a rapidly rotating centrifuge drum comprising a running basket which can be at least partially configured as a filter sieve, so that due to the centrifugal forces acting, the liquid phase is separated out through the filter sieve, while a solid cake is deposited inside on a drum wall of the centrifuge drum. Those skilled in the art frequently use the terms centrifuge drum, drum and barrel basket, although not consistently synonymously, of course multi-part drums are also known, in which, for example, a removable filter basket or a removable filter cloth can be provided or the centrifuge drum itself is designed integrally as a filter basket can be.

In the rotating centrifuge drum, which is also simply referred to below as the drum, there is an essentially disk-shaped synchronous co-rotating moving floor, which oscillates in the axial direction in the drum with a certain amplitude, so that part of the dehumidified solid cake at one end of the Drum is pushed out. During the opposite movement of the moving floor, an area of the walking cage adjacent to the moving floor is released, which can then be fed with new mixture through the inlet pipe and via the mixture distributor. Depending on the type used, modern high-performance double-thrust centrifuges can easily achieve throughputs of up to 100 tons per hour or even more, with drum diameters of up to 1000 mm and even larger being quite common and typical drum rotation frequencies, depending on the drum diameter of up to 2000 revolutions per minute and more can be achieved. As a rule, a larger drum diameter results in a smaller maximum rotation frequency of the drum because of the strong centrifugal forces that occur. Of course, the operating parameters, such as the rotation frequency of the drum or the cage, the amount of mixture supplied per unit of time or the drum diameter and thus the diameter of the cage, or the type of pusher centrifuge used, can also depend on the material to be dehumidified Depend on liquid content etc.

In the known double-push centrifuges, the mixture usually reaches the center of the centrifuge drum via a standing inlet pipe and a mixture distributor, the mixture distributor rotating synchronously with the centrifuge drum. The mixture can be fed alternately to the front or rear half of the drum by means of a moving floor arranged in the middle of the cage, which oscillates along the longitudinal axis of the centrifuge drum and can be operatively connected to the mixture distributor. As a result, there are two inlet zones so that correspondingly larger quantities of mixture can be processed per unit of time. A predeterminable part of the solid cake is transported through the push floor to the respective end of the drum and discharged via a collecting trough.

A known double-thrust centrifuge, which works on the principle described above, is for example in the EP 0 635 309 B1 described in detail. The advantages over conventional single or multi-stage push centrifuges are obvious. Among other things, the double inlet zone is to be mentioned here, as a result of which a significantly increased liquid absorption capacity is achieved, so that mixtures with lower inlet concentrations, ie with a higher liquid content, can be processed, and at the same time higher total inlet quantities of mixture can be processed. In addition, with the same number of strokes, there is double Festoff delivery capacity and thus a lower transport work. The space requirement corresponds to that of normal pusher centrifuges of the same size.

Typical areas of application for double-shear centrifuges include well-dehumidifiable products, such as sea salt, where in particular the double use of the shear movement is fully effective. Another typical area of application is products that are difficult to filter or mixtures with low inlet concentrations (i.e. with a high liquid content). Here, the higher liquid swallowing capacity compared to conventional push centrifuges has a particularly positive effect. Smaller inlet 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 Inlet concentrations can be processed as with conventional single or multi-stage batch centrifuges, the inlet concentration of the mixture to be processed must 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% liquid phase, the mixture must be pre-thickened in more or less complex processes. If the liquid content is too high, it is increasingly difficult to evenly distribute the mixture to be dried over the circumference of the sieve drum. On the one hand, this can lead to very damaging vibrations of the screening drum and thus to premature wear of the bearings and drive; in the worst case, even become a security problem in the company. On the other hand, a solid cake distributed unevenly over the circumference of the sieve drum causes problems during washing. For this reason, static thickeners, curved screens or the well-known hydrocyclones are available for pre-dewatering. It is obvious that the use of such pre-drainage systems is very complex, both in terms of process technology and apparatus, and is therefore expensive.

Another serious disadvantage when processing mixtures with a low inlet concentration is that practically the entire amount of liquid which is fed in with the mixture has to be accelerated to the full peripheral speed before it is separated out through the filter screen of the sieve drum. The same applies to the smallest particles in the mixture, which are also to be separated from the solid cake through the sieve. This is extremely unfavorable in terms of energy and has a clearly negative impact on the operating behavior of the centrifuge.

But even when processing mixtures with a significantly higher solids concentration, the centrifuges known from the prior art sometimes have clear disadvantages. The mixture introduced through the inlet pipe into the mixture distributor is accelerated to the full circumferential speed of the drum in a very short time when it hits the sieve drum. This can lead to grain breakage, especially for sensitive substances. This means that, for example, solid particles which are distributed in a suspension fed to the centrifuge during the abrupt acceleration process in burst into smaller pieces in an uncontrolled manner, which can have a negative impact on the quality of the solid cake produced if, for example, the particle size of the grains plays a role in the end product.

The applicant has recognized some of the problems described above, but also other problems earlier, for example in the EP 1 468 741 A1 appropriate solutions proposed.

For a better understanding of the present invention, the known solution according to EP 1 468 741 A1 based on Fig. 1 briefly explained. In order to distinguish the present invention from the solution known from the prior art Fig. 1 the reference numerals of the Fig. 1 provided with a quotation mark, while the reference numerals for features according to exemplary embodiments according to the invention 2 to 6c do not wear apostrophes.

The centrifuge according to Fig. 1 shows in section in a schematic representation of essential components of a known double push centrifuge. For example from the EP 1 468 741 A1 Known double-thrust centrifuge, which is designated in the following as a whole by the reference symbol 1 ', comprises, in a manner known per se, a cage 3' which can be rotated about an axis of rotation 2 'via a drum axis 31' and which is accommodated in a housing G '. The drum axis 31 'is operatively connected to a drum drive, not shown, so that the basket 3' can be set in rapid rotation about the axis of rotation 2 'by the drum drive. The running cage 3 'has sieve openings 32' through which, in a known manner, liquid phase 6 'with a rapid rotation from a mixture 4' which is applied to an inner peripheral surface 20 'of the running cage 3', and to the outside due to the centrifugal forces which occur can be removed in a collecting device 18 '. The mixture 4 'applied to the inner circumferential surface 20' of the running cage 3 'is thus, by the prevailing very strong centrifugal forces, into a solid cake 5' which is deposited on the inner circumferential surface 20 'of the running cage 3', and the liquid phase 6 ' can be removed from the basket 3 'through the sieve openings 32', separately.

A mixture distributor 7 'is arranged inside the running cage 3', which allows mixture 4 'to be distributed onto the inner peripheral surface 20' of the running cage 3 ', the Mixture distributor 7 'comprises an inlet pipe 10' and a sliding floor device 8 'with sliding floor plate 81'.

In the operating state, the mixture 4 'reaches the inlet device 17' of the mixture distributor 7 'via the inlet pipe 10' and can then be fed alternately to the front or rear half of the basket 3 'due to an oscillatory movement of the moving floor device 8'. The inlet device 17 'is preferably rigidly coupled to the running cage 3' by fastening means and therefore rotates synchronously with the running cage 3 'and the mixture distributor 7'. The oscillatory movement, which will be described in more detail below, is only carried out by the mixture distributor 7 'with its components, i.e. with the moving floor plate 81 ', the connecting element 82', the moving floor device 8 'and the outer ring area 9'. Thus, in the operating state there is an oscillatory relative movement between the oscillating mixture distributor 7 'and the inlet device 17' which is immobile in the axial direction or the inlet pipe 10 'which is immobile in the axial direction, so that the mixture 4' can be fed alternately to the front or rear half of the cage 3 ' is.

The sliding floor device 8 'is operatively connected to the sliding floor plate 81' via a connecting element 82 '. The push floor device 8 'is preferably designed in the form of a circular disk with an outer ring area 9', the ring area 9 'being designed and arranged on a peripheral area of the push floor device 8' in such a way that the ring area 9 'is deposited in the running cage 3' Solid cake 5 'is alternately displaceable in both directions of the axis of rotation 2'. The sliding floor plate 81 'is also preferably designed as an annular sheath 81', but can also be designed in the form of a spoke wheel 81 'or in any other suitable shape. The connecting element 82 ', which connects the moving floor plate 81' to the moving floor device 8 'in an effective manner, is constructed, for example, from a plurality of struts 82', which preferably, but not necessarily, extend along the axis of rotation 2 ', or as a compact or non-compact drum 82 ', for example as a perforated drum 82' or in any other suitable form.

The push floor plate 81 'is coupled by means of a push axis 16' to a push device (not shown) with a reversing unit, so that the push floor plate 81 ' with the connecting element 82 'and the sliding floor device 8' in the direction of the axis of rotation 2 'in an oscillatory movement with a predetermined stroke can be set. Due to the oscillatory movement of the moving floor device 8 ', the solid cake 5' deposited on the peripheral surface of the walking cage 3 'can be displaced alternately in both directions of the axis of rotation 2' through the outer ring area 9 ', so that the solid cake through the outer ring area 9' in the axial direction can be transported to the respective end of the running cage 3 'and can be removed from the double-shear centrifuge 1' via a discharge opening 19 'separated from the liquid phase 6'.

The essence of the applicant's earlier invention is that the moving floor device 8 'is designed in a predeterminable area in the form of acceleration surfaces 12' in such a way that the mixture 4 'introduced by the inlet pipe 10' can be accelerated to a predeterminable peripheral speed before reaching the running cage 3 ' is.

Because with this solution according to EP 1 468 741 A1 If the moving floor device 8 'has acceleration surfaces 12' inclined towards the radial direction, a mixture 4 'introduced into the mixture distributor 7' through the inlet pipe 10 'does not directly hit the walking basket 3'. Rather, the incoming mixture 4 'is applied to the acceleration surfaces 12', which are inclined against the radial direction. This results in a slower acceleration of the newly introduced mixture 4 'to the peripheral speed of the running cage 3', which in particular prevents grain breakage and other damaging influences, such as occur during abrupt acceleration in the double-thrust centrifuges known from the prior art. In such a double-thrust centrifuge 1 ', bursting of solid particles contained in the mixture can be avoided because the acceleration process can be controlled via the predeterminable angle of inclination of the acceleration surfaces 12', that is to say that the acceleration itself can be set, for example, by a suitable choice of the angle of inclination of the acceleration surface 12 '. As a result, the quality of the solid cake 5 ′ produced, in particular in the case of products in which, for example, the particle size or the shape of the grains play a role in the end product, can be significantly increased. In very special cases, it is even possible in one and the same double pusher centrifuge 1 'in one operation, ie in essentially at the same time to produce products of different quality, for example by choosing differently the angle of inclination of the acceleration surfaces 12 'arranged on both sides of the moving floor device 8'.

Although the double-push centrifuge described above works according to EP 1 468 741 A1 has now proven itself in practice for many years and continues to provide excellent services for many applications, however experience has shown that further improvements, especially with special requirements, may be necessary to further optimize the work results. This applies in particular to filling the centrifuge as such, but also washing the solid cake has further potential for improvement. Practical application has shown that, for example, optimizing the dosage when feeding the product stream is desirable in certain cases. The same applies to the washing process, which could be significantly improved by more targeted metering of the supply of the washing liquid.

The construction of the EP 1 468 741 A1 with mixture distributor 7 ', the inlet device 17', and with the acceleration surfaces 12 'on the moving floor device 8' according to Fig. 1 structurally relatively complex, so that in certain cases it may be desirable to either completely or at least partially dispense with such a complex construction of the mixture distributor 7 'or to retain it in whole or in part but at the same time to further improve its function by additional constructive or procedural measures . A double push centrifuge according to the preamble of claim 1 is known from the EP 0 068 095 A2 known.

The object of the invention is therefore to propose an improved double-thrust centrifuge which largely avoids the disadvantages arising from the prior art.

The objects of the invention achieving these objects are characterized by the features of independent claims 1 and 14. The respective dependent claims relate to particularly advantageous embodiments of the invention.

The invention relates to a double-shear centrifuge according to claim 1 and a method according to claim 14. According to the invention, the feed device comprises a feed reversal and a mixture feed, so that the mixture can be fed to the first empty space or the second empty space according to a predeterminable scheme by means of the feed reversal via the mixture feed. It is essential for the invention that the feed device, which in practice can comprise an inlet pipe known per se, comprises a feed switch and is in operative connection with it, so that at least the mixture and / or in special exemplary embodiments also another fluid, e.g. a washing fluid can be introduced into the interior of the screening drum and can be distributed in the screening drum, and thus e.g. the mixture to be dehumidified into the first empty space or second empty space of the double-push centrifuge generated by the push floor on an inner peripheral surface of the screening drum in the operating state can be supplied in a specifiable manner and in a specifiable amount.

It is thus possible for the first time, by means of the present invention, to meter the mixture to be dehumidified in predefinable quantities and to apply it at predeterminable times or at predeterminable time intervals optimally as a function of the relevant relevant boundary conditions or parameters for dehumidification. For example, one and the same centrifuge can be used to charge a mixture loaded with a great deal of liquid, or even a mixture that has already been largely pre-dehumidified by an inventive one Double-shear centrifuge can be processed optimally without having to make any structural adjustments to the centrifuge or its additional units. The same applies, for example, to the washing process, which for the first time can be adapted to the special conditions of each application or each material to be processed with a level of flexibility that has never been seen before. For this purpose, the centrifuge according to the invention comprises, according to the detailed description below, appropriate devices for loading with the mixture to be dehumidified, in practice usually a suspension, or also devices for washing the solid cake with a washing liquid. Corresponding units for rinsing the centrifuge, which the person skilled in the art knows in principle, can of course also be provided.

So that the feed device of the present invention can develop its full flexibility, sensors, sensors, optical lenses or sensors known per se can be used to measure, control or regulate the supply of the media to be processed, such as suspensions to be dehumidified, washing or cleaning fluids or other media to be processed other known sensors or detectors can be provided on a double-thrust centrifuge according to the invention, with which, for example Suitable valves, pumps, locks etc. can be controlled or regulated so that the materials to be processed can be flexibly and optimally fed to the screening drum in accordance with the necessary specifications.

The feed device or at least some of its components are advantageously provided on a front plate of the centrifuge and particularly preferably protrudes through the sliding floor into the interior of the sieve drum of the centrifuge.

The feed device can comprise one, several or even a plurality of inlet pipes and / or feed change-over devices, on or in which one or more rotating or partially rotating or pulsating metering devices in the form of metering pistons, metering bushes or other metering units can be provided in the operating state.

The one or more pulsating, rotating, partially rotating or otherwise metering components of the feed reversal system according to the invention serves primarily, but not only for the defined task of the product stream from the mixture to be dehumidified and / or for washing the solid cake and / or also for rinsing the front or rear of the rear chambers of the centrifuge.

Is the allocation device e.g. a metering piston or a metering sleeve or another metering device, this can for example have an angular, oval or circular cross section. However, it can also be designed as a flat slide, cylindrical, cubic or spherical and thus serves for targeted feeding or non-feeding of the medium to be fed into the sieve drum.

It goes without saying that the feed device or its components can be made of any suitable material and, depending on the requirements, manufactured according to known manufacturing processes and possibly e.g. can also be suitably treated on the surfaces so that the necessary requirements for certain material properties such as hardness, strength, structure, changes in surface roughness etc. can be optimally set.

The drive and / or the control and / or regulation of the infeed device or its components can be carried out by suitable drives which are provided directly on the corresponding components to be driven or else remote from the components, e.g. can be provided in corresponding drive units outside the centrifuge, which can then be connected in a manner known per se to the component to be operated via suitable connections such as pressure lines, electrical connections, radio connections or any other suitable active and / or signal connection.

In an embodiment of a double-thrust centrifuge according to the invention which is particularly important in practice, the feed device comprises an inlet pipe with an inlet pipe axis and the feed reversal device comprises a metering device provided on the inlet pipe, with which the mixture feed can be manipulated in accordance with a predefinable scheme such that a feed of the mixture into the first empty space or is prevented in the second empty space. This means that the mixture is fed into the first empty space or into the second Empty space is no longer controlled, so to speak, passively and inflexibly by the movement of the push floor alone, but can be actively controlled and / or regulated flexibly and specifically in the push centrifuge according to the invention by the ice cream reversal according to a predetermined scheme.

In particular, the metering device can be an metering piston arranged at least partially in the inlet pipe or, alternatively or additionally, can be an metering sleeve arranged at least partially on the outside of the inlet pipe.

To adjust and influence the fluid flow, the metering device can be arranged to be displaceable along the inlet pipe axis or rotatable about the inlet axis, or it can be designed in any other suitable manner that specifically controls and / or regulates the fluid flow, i.e. the one to be dehumidified or separated Mixture, the washing liquid, the cleaning liquid or another substance to be processed as desired.

The mixture feed can be an integral part of the inlet pipe and preferably a first feed opening that cannot be moved with respect to the inlet axis for feeding the mixture or another fluid to be processed into the first empty space, and a second feed opening that cannot be moved with respect to the inlet axis of the mixture or another fluid to be processed in the second void.

In another special exemplary embodiment, the mixture feed can alternatively or simultaneously be an integral part of the metering device and preferably a first feed opening that can be moved with respect to the inlet axis with the metering device for feeding the mixture or another fluid to be processed into the first empty space and one with respect to the inlet axis with the metering device comprises movable second feed opening for feeding the mixture or another fluid to be processed into the second empty space.

As already mentioned, a plurality of mixture feeds or a plurality of metering devices can also advantageously be provided, the feed device preferably comprising a plurality of inlet pipes with feed reversal and mixture feed, so that the Mixture or another fluid to be processed can be supplied to the first empty space or the second empty space according to a predefinable scheme. In a special exemplary embodiment, at least some of the inlet pipes or a group of inlet pipes can be supplied with the mixture or another fluid to be processed separately by the feed reversal.

As already explained in more general terms above, the feed changeover can be manipulated in particular by means of a mechanical, or an electrical, or a hydraulic, or a pneumatic drive and preferably can be controlled or regulated by means of a control unit according to a predefinable scheme, in particular by means of a programmable data processing system .

It is of course possible that in a centrifuge according to the invention there is also a washing device for washing the solid cake by means of a washing fluid, wherein the washing device can preferably be identical to the feed device or part of the feed device, with the controlled feeding of the mixture or the washing fluid or another for the fluids to be processed, a feed metering provided inside or outside the centrifuge can be used, which in the simplest case is, for example, a shut-off or metering valve, so that a predeterminable amount of the mixture or a predefinable amount of the washing fluid or another fluid to be processed can be fed to the feed device is.

In practice, an inlet disk known per se, preferably on the inlet pipe, is provided for better channeling of the medium to be introduced into the sieve drum and also for the controlled feeding of the mixture into a predeterminable region of the sieve drum.

The invention further relates to a feed reversal or a method for loading a centrifuge, in particular a double push centrifuge, or a single-stage or multi-stage push centrifuge according to the present description.

Even if it is one of the essential advantages of the present invention that a relatively large number of components, as are necessary for various reasons in known centrifuges, in a centrifuge according to the invention most of the fields of application can be dispensed with, because the feed reversal of the present invention prevents the problems known from the prior art, it has been shown in special applications that it can nevertheless be advantageous to change the feed reversal according to the invention, in particular in combination with the acceleration areas according to EP 1 468 741 A1 to be used, whereby an even more optimal, especially gentle processing of the mixture to be dehumidified is possible.

Analogous to EP 1 468 741 A1 according to Fig. 1 The moving floor device of a centrifuge according to the invention can also have an acceleration surface inclined towards the radial direction, which for reasons of clarity in the drawings according to the examples according to the invention 2 to 6c are not shown explicitly, but from Fig. 1 are easily transferable to a centrifuge according to the invention for the person skilled in the art.

By providing the inclined acceleration surfaces, a mixture introduced by the feed device does not directly hit the screening drum. Rather, the incoming mixture is applied to the acceleration surfaces, which are inclined against the radial direction. As a result, the newly introduced mixture is slowed down to the circumferential speed of the sieve drum, which in particular prevents grain breakage and other damaging influences, such as occur during abrupt acceleration in other centrifuges known from the prior art. Thus, the centrifuge according to the invention prevents the solid particles contained in the mixture from bursting because the acceleration process can be controlled via the predeterminable angle of inclination of the acceleration surfaces, ie the acceleration itself can be set, for example, by a suitable choice of the angle of inclination of the acceleration surface. This can significantly increase the quality of the solid cake produced, particularly in the case of products in which, for example, the particle size or the shape of the grains play a role in the end product. In very special cases, it is even possible to use one and the same centrifuge, in particular if a double-push centrifuge is used in one operation, ie essentially at the same time. To produce products of different quality, for example by choosing differently the angle of inclination of the acceleration surfaces arranged on both sides of the moving floor device.

In a centrifuge according to the invention, in particular a double-shear centrifuge, the sieve drum can be designed in a manner known per se as a skeletal support drum which is lined with special filter foils on its circumference to form the corresponding sieve surfaces, i.e. the skeletal support drum can be configured, for example, with one or more filter screens with filter openings of different or the same size for separating the liquid phase.

A mixture distributor, which allows mixture to be distributed over the circumferential surface of the sieve drum, can optionally also be arranged within the sieve drum, the mixture distributor preferably comprising an inlet device and a moving floor device with a moving floor plate.

In a preferred exemplary embodiment, the inlet device is rigidly coupled to the screening drum and therefore rotates synchronously with the screening drum and the mixture distributor. However, only the mixture distributor with its components performs the oscillatory movement, i.e. with the moving floor plate, the connecting element, the moving floor device and the outer ring area. Thus, in the operating state there is an oscillatory relative movement between the oscillating mixture distributor and the inlet device which is immobile in the axial direction, so that the mixture can be fed alternately to the front or rear half of the screening drum.

The moving floor device, which in a special embodiment can be connected to the moving floor plate in an effective manner, is preferably designed in the form of a circular disc with an outer ring area, the ring area being designed and arranged on a peripheral area of the moving floor device in such a way that the ring area in FIG the sieve drum deposited solid cake is alternately displaceable in both directions of the axis of rotation.

In the case of a double push centrifuge, the push floor plate can be coupled in a manner known per se to a push device with a reversing unit by means of a push axis, so that the push floor device in the direction of the axis of rotation in an oscillatory movement with a specifiable stroke can be offset. Due to the oscillatory movement of the moving floor device, the solid cake deposited on the circumferential surface of the screening drum can be shifted alternately in both directions of the axis of rotation through the outer ring area, so that the solid cake can be transported through the outer ring area in the axial direction to the respective end of the screening drum and via a discharge opening from the liquid phase can be removed separately from the double-shear centrifuge.

It is essential in the corresponding special exemplary embodiment of the invention that the moving floor device is designed in a predeterminable area in the form of acceleration surfaces in such a way that the mixture introduced by the feed device can be accelerated to a predeterminable peripheral speed before reaching the screening drum.

For this purpose, in a double-push centrifuge, the mixture from the feed device is alternately fed to one side of the moving floor device. If the mixture in the feed device cannot already be pre-accelerated to a predeterminable circumferential speed, the mixture reaches a corresponding surface of the moving floor device essentially under the effect of gravity and finally reaches the acceleration surface inclined with respect to the radial direction at a predeterminable angle of inclination. The mixture flows over or along the acceleration surface and thus reaches the peripheral surface of the screening drum. Here the mixture reaches the empty space on the circumferential surface of the screening drum created by the oscillating movement of the moving floor device, and is accelerated to the speed of rotation of the screening drum. Due to the enormously high centrifugal forces that act on the mixture deposited in the empty space, the liquid phase contained in the mixture is removed from the sieve drum through the sieve openings.

Due to the fact that the acceleration surface is inclined towards the radial direction, the flow velocity in the area of the acceleration surface can be specifically changed compared to the speed in the free fall of the mixture in the direction of the circumferential surface, so that the mixture in the area of the acceleration surfaces increases as the outer ring region approaches is gradually accelerated. This means that the mixture is in the area of the acceleration Double thrust centrifuge according to the invention is accelerated in a particularly gentle manner gradually to a predeterminable peripheral speed, in order then to finally reach the full rotational speed of the screening drum when the peripheral surface is reached.

The value of the angle of inclination of the acceleration surface against the radial direction can be, for example, between 0 ° and 90 °, in particular 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 also possible in particular that the value of the angle of inclination is greater than 70 ° and can even be close to 90 °. In general, it can be stated that a rather not too acute angle is generally advantageous with respect to the radial direction, an optimal value of the corresponding inclination angle being determined, inter alia, by the value of the static friction angle of the product to be dewatered. The acceleration surfaces can either extend only over a partial area of the moving floor device or also over the entire radial height of the moving floor device, wherein the moving floor device can be constructed entirely or partially as an essentially hollow frame or, depending on the requirements, or completely or partially from solid material. Of course, it is possible for the two acceleration surfaces to have the same or different angles of inclination.

In an embodiment of a centrifuge according to the invention which is particularly relevant in practice, the acceleration surface is designed as a filter screen for separating the liquid phase from the mixture. Both acceleration surfaces are preferably designed as a filter screen. Of course, only one acceleration surface can be designed as a filter screen, or the two acceleration surfaces can each have differently designed filter screens. The two different filter screens can be constructed from different materials, for example, or the size of the filter pores can be different. This makes it possible to produce two different solid cakes of different quality, ie with different properties, from the same mixture in the same operation. In particular, in an embodiment that is particularly important in practice, the acceleration surface can be arranged as a filter screen on a skeleton-like support body which can be equipped with special filter foils to form the filter screen, i.e. the skeleton-like support body can for example be equipped with one or more filter screens that may be used for separation different stages can have differently sized filter openings.

In general, filter sieves or slotted sieves, for example, come into question as filter sieves. The filter screens can advantageously be provided in different ways with filter openings of different sizes. In particular, the previously mentioned screen plates can be punched, drilled, lasered, electron beam perforated or water jet cut, among other things, in principle, other techniques are also possible. Depending on requirements, the screens themselves can be made from various, in particular corrosion-resistant materials, such as plastic, composite materials or different steels such as 1.4462, 1.4539 or 2.4602 or from other suitable materials. To protect against wear, the filter screens can also be provided with suitable layers, for example with hard chrome layers, tungsten carbide (WC), ceramics or otherwise hardened. The thickness of the filter plates is typically 0.2 mm to 5 mm, although significantly different plate thicknesses are also possible.

In particular for processing particularly sensitive mixtures, the feed device can comprise an inlet funnel for pre-accelerating the mixture. As a result, the mixture can be pre-accelerated to a predeterminable rotational speed before it is introduced into the mixture distributor and can therefore be treated even more gently. The speed of rotation at which the mixture can already be accelerated in the inlet funnel can be predetermined, for example, by selecting the size and / or the opening angle of the inlet funnel.

The inlet funnel can also be arranged rotatably about a separate drive axis independently of the mixture distributor and can be designed and arranged to be rotatable about the drive axis by means of a drive at a predeterminable speed be. As a result, the pre-acceleration can be freely selected regardless of the geometry of the inlet funnel by setting the speed of the drive. In particular, suitable devices for control and / or regulation can be provided so that, for example, the speed of the drive can be freely varied even during operation. For example, the quality of the solid cake can be adjusted during operation, or a different product quality can be produced from one mixture in one and the same double-barrel centrifuge, for example by suitable control and / or regulation of the speed of the drive and thus of the inlet funnel to the right and left of the moving floor device.

Advantageously, the inlet funnel can also be designed as a pre-filter screen for pre-separating liquid phase from the mixture, preferably collecting means for collecting and discharging the liquid phase from the pre-filter screen. This means that even mixtures with a very high liquid content can be processed without any problems. The pre-separation of the liquid phase in the inlet funnel also has the enormous advantage that this part of the liquid phase is no longer accelerated to the very high rotational speed of the sieve drum, which among other things has a particularly favorable effect on the energy consumption of the double-push centrifuge.

Both the filter screen of the acceleration surfaces and the pre-filter screen can be designed as a two-stage screen with a coarse filter and a fine filter. The mixture can thus be filtered in two stages in the area of the acceleration surface and / or in the inlet funnel. The first filter stage forms a coarse filter that retains particles contained in the mixture that are larger than the filter openings of the coarse filter. The fine filter retains correspondingly finer particles, while at least part of the liquid phase and very small 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 is not so mechanically loaded by large and / or heavy particles that are contained in the incoming mixture, so that the fine filter can have, for example, very small pores for filtering very small particles and in particular can also be made from mechanically less resistant materials.

In another embodiment variant of the centrifuge according to the invention, the mixture distributor comprises a pre-acceleration funnel, which essentially extends in the direction of the feed device.

The value of the opening angle of the inlet funnel and / or the value of the pre-acceleration angle of the pre-acceleration funnel can be, for example, between 0 ° and 45 ° with respect to the axis of rotation, 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 opening angle and / or the pre-acceleration angle is greater than 45 °. In general, it can be stated that a rather acute angle is generally advantageous with respect to the axis of rotation, an optimal value of the corresponding opening angle and / or the pre-acceleration angle being determined, inter alia, by the value of the static friction angle of the product to be dewatered.

In this case, the pre-acceleration funnel can also be designed as a pre-acceleration sieve analogous to the inlet funnel, wherein collecting devices for discharging the liquid phase can be provided on the mixture distributor.

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

In general, filter sieves or slotted sieves, for example, come into question as filter sieves. The filter screens can advantageously be provided in different ways with filter openings of different sizes. In particular, the previously mentioned screen plates can, among other things, be punched, drilled, lasered, electron beam perforated or water jet cut be, whereby in principle other techniques are also possible. Depending on requirements, the screens themselves can be made from various, in particular corrosion-resistant materials, such as plastic, composite materials or different steels such as 1.4462, 1.4539 or 2.4602 or from other suitable materials. To protect against wear, the filter screens can also be provided with suitable layers, for example with hard chrome layers, tungsten carbide (WC), ceramics or otherwise hardened. The thickness of the filter plates is typically 0.2 mm to 5 mm, although significantly different plate thicknesses are also possible.

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

Both the inlet funnel and the pre-acceleration funnel preferably extend at an essentially constant opening angle in the direction of the moving floor device or the feed device. The value of the pre-acceleration angle of the pre-acceleration funnel can be, for example, between 0 ° and 45 ° with respect to the axis of rotation, 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 °. It can be stated quite generally that a rather acute angle is generally advantageous with respect to the axis of rotation, an optimal value of the corresponding pre-acceleration angle being determined, inter alia, by the value of the static friction angle of the product to be dewatered.

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

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 namely 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 / or other properties or parameters, such as the temperature of the mixture.

For example, if there is a mixture that is relatively easy to dewater for given operating parameters, it may be advantageous for the inlet funnel or the prefilter sieve to have a curved course, the opening angle of the prefilter sieve increasing in the direction of the moving floor device. This means that the inlet funnel or the prefilter sieve widens towards the moving floor device similar to the horn of a trumpet. As a result, the output force with which the mixture is accelerated from the inlet funnel increases disproportionately as the distance to the moving floor device decreases, so that the mixture, which can be relatively heavily dewatered in the pre-filter screen and therefore shows poor sliding properties in the pre-filter screen, can leave the pre-filter screen more quickly. than, for example, in the case of a pre-filter sieve which widens essentially conically, with a constant opening angle.

On the other hand, there may also be mixtures that are relatively difficult to dewater at given operating parameters. In this case, it is advisable to use an inlet funnel or a pre-filter screen with a curved course, the opening angle of the pre-filter screen decreasing in the direction of the moving floor device. The result of this is that the output force with which the mixture is accelerated out of the inlet funnel increases more slowly with decreasing distance from the moving floor device than, for example, with an inlet funnel which widens conically at an essentially constant opening angle. This creates a certain accumulation effect in the pre-acceleration screen, so that the mixture remains longer in the pre-filter screen and can therefore be dewatered to a higher degree in the pre-filter screen.

Quite analogously to what has been said above, the pre-acceleration funnel can of course also have a curved course, the pre-acceleration angle of the pre-acceleration funnel increasing or decreasing in the direction of the feed device.

The advantages previously explained in connection with the curved inlet funnel and its mode of operation can easily be transferred analogously to a curved pre-acceleration funnel for the person skilled in the art, and therefore need not be repeated here.

It goes without saying that the features of the particularly preferred embodiment variants of the centrifuge according to the invention described above by way of example can, depending on the requirements, also be advantageously combined as desired.

Fig. 1

im Schnitt eine aus dem Stand der Technik bekannte Doppelschubzentrifuge mit Beschleunigungsflächen;

Fig. 2

ein erstes erfindungsgemässes Ausführungsbeispiel ohne Produktwaschung;

Fig. 3

ein zweites erfindungsgemässes Ausführungsbeispiel mit Produktwaschung;

Fig. 4a - 4b

ein erstes Ausführungsbeispiel eines Zuteilkolbens;

Fig. 5

ein zweites Ausführungsbeispiel eines Zuteilkolbens;

Fig. 6a - 6c

ein drittes Ausführungsbeispiel eines Zuteilkolbens.

The invention is explained in more detail below with the aid of the schematic drawing. Show it:

Fig. 1

on average a double-thrust centrifuge with acceleration surfaces known from the prior art;

Fig. 2

a first embodiment according to the invention without product washing;

Fig. 3

a second embodiment according to the invention with product washing;

Figures 4a - 4b

a first embodiment of a metering piston;

Fig. 5

a second embodiment of a metering piston;

6a-6c

a third embodiment of a metering piston.

Fig. 1 shows a double-push centrifuge known from the prior art EP 1 468 741 A1 , which was already described in detail at the beginning and therefore no longer needs to be discussed at this point.

Fig. 1 shows in section in a schematic known centrifuge, some essential components of a double-shear centrifuge according to the invention, which is referred to in the following as a whole with reference number 1.

The Fig. 2 shows a schematic representation of a first embodiment of a double-shear centrifuge according to the invention without product washing. In the Fig. 2 The double-thrust centrifuge 1 shown, which could in principle also be a single-stage or multi-stage thrust centrifuge or even a peeling centrifuge with a feed device 1000 according to the invention, comprises, in a manner known per se, 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 sliding floor device 8 arranged in the sieve drum 3, which is alternately arranged so that it can be moved back and forth along the axis of rotation 2 in a first direction of thrust S1 and a second direction of thrust S2, so that the solid cake 5 is mutually displaceable along the axis of rotation 2. In addition, the centrifuge 1 comprises the feed device 1000, with which the mixture 4 can be introduced into a first empty space 1101 or into a second empty space 1102, which first empty space 1101 can be produced when the solid cake 5 is moved by the moving floor device 8 in the first pushing direction S1, and the second void 1102, which in Fig. 2 or Fi6. Is already filled with mixture 4, when the solid cake 5 is shifted by the sliding floor device 8 into the pushing direction S2 opposite to the first pushing direction S1. According to the present invention, the feed device 1000 comprises a feed reverser 1020 and a mixture feed 1010, so that the mixture 4 can be fed to the first empty space 1101 or the second empty space 1102 by means of the feed reversal 1020 via the mixture feed 1010 according to a predefinable scheme.

The feed device 1000 comprises an inlet pipe 1030 with an inlet pipe axis EA, the feed reverser 1020 comprising a feed device 1021, 10211 in the form of a feed piston 10211 provided on the feed pipe 1030, with which the mixture feed 1010 according to a predeterminable The scheme can be manipulated in such a way that the mixture 4 is prevented from being fed into the first empty space 1101 or into the second empty space 1102.

This is the in the present embodiment Fig. 2 in that the metering piston 10211 can be displaced in the axial direction along the inlet pipe axis EA and the mixture feed 1010 is at the same time an integral part of the inlet pipe 1030 in the form of first feed openings which are not movable with respect to the inlet axis EA, for example in the form of bore openings provided on the inlet pipe 1030 1011 for feeding the mixture 4 into the first empty space 1101 and second feed openings 1012, which cannot be moved with respect to the inlet axis EA, for feeding the mixture 4 into the second empty space 1102. In the operating state, the metering piston 10211 is controlled, for example, via the piston rod KS in such a way that the metering piston 10211 opens the first feed openings 1011 when the push floor 8 has released the first empty space 1101 by displacement in the direction S1 and at the same time closes the second feed openings 1012. In the subsequent reverse stroke of the moving floor 8 in the direction S2, the metering piston 10211 opens the second feed openings 1012 and at the same time closes the first feed openings 1011, so that the mixture is fed only to the second empty space 1102. In this case, for the controlled feeding of the mixture 4 into a predeterminable region of the screening drum 3, an inlet disk 9, as shown here by way of example, is provided on the inlet pipe 1030.

It goes without saying that, in another exemplary embodiment, the piston rod KS can be replaced, for example, by a chain or a cable with which the metering piston 10211 can be moved or that the piston rod KS can be replaced by a suitable pneumatic, hydraulic, electrical or other active line can be if the corresponding drive of the metering piston is provided directly on the piston itself or elsewhere in the reversing device 1020. Of course, what has been said above applies analogously to any embodiment of a metering device (1021, 10211), that is to say also, for example, to an metering sleeve attached to the outside of the tube or any other type of movable metering device, which in the simplest case also, for example, relates to the first feed opening 1011 and / or the second feed opening 1012 movable Clapperboard or a shutter can be. The person skilled in the art will readily understand the equivalent solutions and possibilities for flexible or controlled release of the feed openings.

Based on Fig. 3 is a second, for the practice very important embodiment of the present invention with integrated product washing shown schematically. The washing device W for washing the solid cake 5 by means of a washing fluid F here comprises a plurality of washing nozzles WD, which are arranged on an outer washing pipe WR of the feed device 1000 such that the washing fluid F is applied to the solid cake 5 by the washing nozzles WD for washing the solid cake 5 can. The feed device 1000 is designed as a double-walled tube with the outer washing pipe WR and the inlet pipe 1030 arranged therein with a feed reverser 1020. The mixture 4 is fed to the inlet pipe 1030 arranged in the interior in a manner known per se, while the washing fluid F can be fed to a space between the outer washing pipe WR and the inner inlet pipe 1030 via a preferably controllable and / or regulatable feed metering D and from there to the washing nozzles WD of the washing device W. The feed metering D is, for example, a controllable or regulatable valve, so that the washing fluid F can be fed to the feeding device according to a predefinable scheme and in a predefinable quantity and can therefore be applied to the solid cake 5.

It goes without saying that the washing device W can also be designed in a different manner, also in a manner known per se, or that the washing device W can also be essentially identical to the feed device 1000 or part of the feed device 1000, so that, for example, the mixture 4 or the washing fluid F or a rinsing fluid for rinsing the inside of the sieve drum, for example can be supplied sequentially or alternately via the feed device.

The Figures 4a - 4b show a first embodiment of a metering piston 10211 according to Fig. 2 respectively. Fig. 3 somewhat more in detail, whereby Fig. 4b shows a view of the metering piston 10211 from direction R1 or R2. As can clearly be seen, the metering piston 10211 is essentially a hollow cylinder open on both sides, through which the piston rod KS runs axially in the middle, for example on the front and rear End is attached to the outer circumferential surface UK of the metering piston 10211 with a fastening cross BK. If, for example, the outer circumferential surface UK covers the first feed opening 1011, no mixture 4 can get into the screening drum 3 through it. Conversely, if the metering piston 10211 is shifted along the axial direction S1 until the metering opening 1012 is covered, the mixture 4 can no longer pass through the metering opening 1012 into the screening drum 3, but instead, for example, only through the metering opening 1011 into the first empty space 1101 In this way, the allocation of the mixture 4 into the first empty space 1101 and into the second empty space 1102 can be controlled alternately by the allocation piston 10211. Since the metering piston 10211 is open at both ends apart from the fastening cross BK, it can be moved back and forth in the axial direction without substantial mechanical resistance through the inlet pipe 1030 completely or partially filled with mixture 4.

Based on Fig. 5 such as 6a to 6c Further exemplary embodiments of an allotment piston 10211 are shown, each of which is a piston rotatable about the piston rod KS with allotment openings 1011, 1012. Such a rotatable metering piston 10211 can be rotated about the piston rod KS in such a way that the metering openings 1011 and 1012 provided on the metering piston 10211 interact with corresponding metering openings 1011 and 1012 also provided on the inlet pipe 1030 in such a way that, depending on the angle of rotation α, mixture 4 alternates either through the Allotment openings 1011 or through the allotment openings 1012 can be introduced into the screening drum 3. The allocation piston 10211 according to Fig. 6a differs from that according to Fig. 5 essentially by the fact that the first dispensing opening 1011 is offset in the circumferential direction by a predeterminable rotation angle α and the fastening cross BK in Fig. 6 is arranged in the middle of the metering piston 10211, while in the exemplary embodiment according to FIG Fig. 5 is provided at the axial ends of the metering piston 10211.

Claims (14)

1. Double-action pusher centrifuge (1) comprising a screen drum (3) which is rotatable about an axis of rotation (2) for separating a mixture (4) into a solid cake (5) and into a liquid phase (6), a pusher base apparatus (8) which is arranged in the screen drum (3) and which is arranged movable to and fro alternately in a first pushing direction (S1) and an opposite second pushing direction (S2) along the axis of rotation (2) such that the solid cake (5) is alternately displaceable along the axis of rotation (2) as well as a feed device (1000) with which the mixture (4) or a washing fluid or another fluid to be processed can be introduced into a first empty space (1101) or optionally into a second empty space (1102), which first empty space (1101) can be established on a displacement of the solid cake (5) by the pusher base apparatus (8) in the first pushing direction (S1) and the second empty space (1102) can be established on a displacement of the solid cake (5) by the pusher base apparatus (8) in the second pushing direction (S2) opposite to the first pushing direction (S1), characterized in that the feed device (1000) comprises a feed redirection control (1020) and a mixture supply (1010) such that the mixture (4) can be supplied by means of the feed redirection control (1020) via the mixture supply (1010) to the first empty space (1101) or to the second empty space (1102) in accordance with a predefinable scheme.
2. A centrifuge in accordance with claim 1, wherein the feed device (1000) comprises an inlet pipe (1030) having an inlet pipe axis (EA) and the feed redirection control (1020) comprises a metering device (1021, 10211) which is provided at the inlet pipe (1030) and with which the mixture supply (1010) can be manipulated in accordance with a predefinable scheme such that a supply of the mixture (4) into the first empty space (1101) or into the second empty space (1102) is suppressed.
3. A centrifuge in accordance with claim 2, wherein the metering device (1021, 10211) is a metering piston (10211) arranged at least partly in the inlet pipe (1030).
4. A centrifuge in accordance with one of the claims 2 or 3, wherein the metering device (1021, 10211) is a metering bush arranged at least partly outwardly at the inlet pipe (1030).
5. A centrifuge in accordance with any one of the claims 2 to 4, wherein the metering device (1021, 10211) is arranged displaceable along the inlet pipe axis (EA) or rotatable about the inlet axis (EA).
6. A centrifuge in accordance with any one of the preceding claims, wherein the mixture supply (1010) is an integral component of the inlet pipe (1030) and preferably comprises a first supply opening (1011), not movable with respect to the inlet axis (EA), for the supply of the mixture (4) into the first empty space (1101) and a second supply opening (1012), not movable with respect to the inlet axis (EA), for the supply of the mixture (4) into the second empty space (1102).
7. A centrifuge in accordance with any one of the preceding claims, wherein the mixture supply (1010) is an integral component of the metering device (1021, 10211) and preferably comprises a first supply opening (1011), movable with the metering device (1021, 10211) with respect to the inlet axis (EA), for the supply of the mixture (4) into the first empty space (1101) and a second supply opening (1012), movable with the metering device (1021, 10211) with respect to the inlet axis (EA), for the supply of the mixture (4) into the second empty space (1102).
8. A centrifuge in accordance with any one of the preceding claims, wherein a plurality of mixture supplies (1010) or a plurality of metering devices (1021, 10211) are provided.
9. A centrifuge in accordance with any one of the preceding claims, wherein the feed device (1000) comprises a plurality of inlet pipes (1030) having a feed redirection control (1020) and a mixture supply (1010) such that the mixture (4) can be supplied to the first empty space (1101) or to the second empty space (1102) in accordance with the predefinable scheme.
10. A centrifuge in accordance with claim 9, wherein the mixture (4) can be supplied separately by the feed redirection control (1020) to at least some of the inlet pipes (1030) or to a group of inlet pipes (1030).
11. A centrifuge in accordance with any one of the preceding claims, wherein the feed redirection control (1020) can be manipulated by means of a mechanical drive or of an electrical drive or of a hydraulic drive or of a pneumatic drive and can preferably be controlled or regulated by means of a control unit in accordance with the predefinable scheme.
12. A centrifuge in accordance with any one of the preceding claims, wherein a washing device (W) is provided for washing the solid cake (5) by means of a washing fluid (F), wherein the washing device (W) is preferably identical to the feed device (1000) or to a part of the feed device (1000).
13. A centrifuge in accordance with any one of the preceding claims, wherein a feed metering unit (D) is provided for the controlled supply of the mixture (4) or of the washing fluid (F) such that a predefinable quantity of the mixture (4) or a predefinable quantity of the washing fluid (F) can be supplied to the feed device (1000), and/or wherein an inlet disk (9) is provided, preferably at the inlet pipe (1030), for the controlled supply of the mixture (4) into a predefinable region of the screen drum (3).
14. A method of loading a double-action pusher centrifuge in accordance with any one of the preceding claims with a mixture (4) or with a washing fluid (F).

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