Patent Publication Number: US-10780445-B2

Title: Separator with inner and outer drum and one or more grippers having a disk portion and a shank portion

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     Exemplary embodiments of the invention relate to a separator. 
     Centrifugal separators for realizing a continuous operation have long been known, for instance in an embodiment as nozzle separators from Japanese patent document JP 62-117649 A. Nozzle separators, those of the kind having solids discharge openings, to which is assigned a hydraulically actuable piston valve, with which the solids discharge openings can be closed off and opened up, are known. US Patent document U.S. Pat. No. 2,017,734 discloses a separator without solids discharge, in a configuration as a separator. In addition, US Patent document U.S. Pat. No. 2,286,354 discloses a separator having solid drum top parts and drum bottom parts, which have been screwed together. 
     Moreover, PCT International patent document WO 2014/000829 A1 discloses a separator of the generic type for separating a flowable product into different phases or for clarifying a product, which separator has a rotatable drum, having a drum bottom part and a drum top part, and a clarifying means arranged in the drum, wherein one or more or all of the following elements consist of plastic or a plastics composite: the drum bottom part, the drum top part, the clarifying means. In that way, it is possible to design a part of the drum, or preferably even the entire drum—preferably along with the inflow and outflow systems and regions—for single use, which is of interest and advantage in particular with regard to the processing of pharmaceutical products such as fermentation broths or the like, since, following operation for the processing of an appropriate product batch in the, during processing of the product batch, preferably continuous operation, no cleaning of the drum has to be performed, but rather the drum can be exchanged in its entirety. This separator is thus very advantageous from a hygiene aspect. 
     Exemplary embodiments of the invention are directed to a further improvement of the running characteristics and also of the ease of handling of the construction of a separator. 
     According to an aspect of the invention, the inflow device and the outflow device(s) are configured such that they extend into the drum, do not rotate with the drum during operation, and are connected to one another in a sealed manner, in particular are bonded together and/or welded together, at one or more points. The thus configured inflow and outflow system is easy to produce and, since it does not rotate during operation, can be sealed off from the rotating drum relatively easily and at only one or very few points. It is in particular advantageously suitable for a separator in which the drum consists of plastic or a plastics composite. 
     Moreover, the drum has an outer supporting apparatus and a drum—referred to as the inner drum—arranged within the supporting apparatus. In that way, the running behavior of the rotating system, in particular of the drum, is easily significantly improved, since the outer supporting apparatus stabilizes the system. Because this supporting apparatus lies radially on the outside relative to the drum wall delimiting the drum interior, the actual drum which delimits the centrifugal space is hereinafter referred to as the “inner drum”. 
     Furthermore, a means for clarifying the product to be processed in the centrifugal field is expediently arranged in the inner drum—for instance a plate assembly consisting of conical plates—which means improves the clarification process or, analogously, a concentration process. 
     In addition, it is here structurally advantageous and simple if the inflow and outflow system has as the inflow device an inflow tube, the center axis of which, in the fitted state, is aligned with the rotational axis of the drum, and/or that the inflow and outflow system has as the outflow device one or two or more gripper(s), which has/respectively have a disk portion and a shank portion. 
     Preferably, the inflow and outflow system has a single inflow device and two outflow devices, in particular in order to concentrate a product to be processed by separating from this a light phase. 
     In design terms, it is advantageous and simple if the grippers are made up of gripper components respectively consisting of a tube section and an annular disk portion. This can in turn be easily realized by virtue of the fact that the gripper components respectively consist of plastic or plastics composite, and that they are preferably respectively configured in one piece. In the assembly operation, the drum parts and the individual elements of the inflow and outflow system are preferably successively placed in suitable sequence, from bottom to top, axially one above the other, and drum parts, on the one hand, and the individual elements of the inflow and outflow system for the drum, on the other hand, are hereupon welded together and/or bonded together at suitable points. Thus, the separating disk, for instance, can only be fitted once the plate assembly and the supporting body are installed, and the inflow tube with the lower gripper. Next the gripper components of the second gripper are fitted, and only then is the inner drum top part mounted. The seal is then placed on this. Finally, the cover is fitted hereon. Exemplary suitable welding points are indicated in  FIG. 1 b    by emboldened dots. The term “gripper” is synonymous with the term “skimmer disk” and with the term “centripetal pump device”. 
     Preferably, a cover is further constructively placed over the gripper components, in a simple manner, the cover is configured as a multistepped, peripherally closed tube of cylindrical diameter, wherein the steps respectively axially delimit tube sections of different diameter, and wherein the cover delimits evacuation chambers. 
     It is further advantageous if extending radially outward from the cover is an annular disk portion, which bears in a flange-like manner against the housing and can preferably be detachably fastened thereto. 
     Preferably, between the annular disk portion of the drum top part, in particular an inner drum top part, and the annular disk portion of the cover is further provided at least one (preferably just a single) axially acting ring seal device. The seal between the inflow and outflow system and the drum can therefore be reduced to just a single region, which is cost-effective. Moreover, any heat development in the region of parts that slide one against the other, in the area of the preferably single seal between these parts, is minimized. 
     Moreover, it is advantageous if a separating plate is arranged or configured above the separating plate assembly, the separating plate is preferably provided with ribs on the top side, so that between the bottom side of the inner drum top part and the top side of the separating plate is formed at least one channel-like gap as the outflow channel. 
     According to one variant, the outer supporting apparatus is configured as an outer ring, which axially partially surrounds the inner drum. Such a ring in the style of a “bandage” stabilizes the construction on the outer periphery. The at least one stabilizing ring (or the plurality of rings) preferredly consists of metal, but can also be produced from a plastic or a plastics composite. It is also conceivable to provide a contour, for instance a ring-like pocket which is open axially in one direction, on the outer periphery of the inner drum, into which pocket the stabilization ring is inserted. 
     Furthermore, according to a preferred embodiment, it is advantageous if the outer supporting apparatus is configured as a peripherally closed outer ring, which axially partially surrounds the inner drum. However, it is also conceivable that the outer supporting apparatus is configured as a latticed outer ring, which surrounds the inner drum on a specific axial portion. 
     According to another variant, the outer supporting apparatus is configured as an outer drum, which wholly or partially surrounds the inner drum. Particularly in this manner, the running behavior of the rotating system, in particular of the drum, is easily significantly improved, since the outer drum stabilizes the system dynamically and mechanically. Both deflections of the rotating system in the radial direction to the rotational axis D and the tendency toward imbalance can be markedly reduced. Both the inner drum and the supporting structure can—but do not have to be—designed such that they are relatively thin-walled. In particular, the inner drum, which is preferably to be changed following processing of a product batch, can hereby be produced in a very material-saving manner. 
     It nevertheless remains possible to utilize the advantages of the “plastics” or “plastics composite” material, for it is still possible to design a part of the drum—the inner drum and preferably the constituent parts thereof—in particular together with the inflow and outflow systems or regions—for single use, so that, following operation for processing of an appropriate product batch in the, during the processing of the product batch, preferably continuous and sanitary operation, no cleaning of the drum has to be performed, but rather the drum is exchanged in its entirety. This exchange therefore turns out to be particularly simple, since the outer drum, which is preferably reused, requires no great cleaning, as it preferably does not make any contact with product to be processed. It therefore does not have to be cleaned and/or disinfected with each change of the inner drum, or only relatively briefly. 
     The changing of the inner drum, and the assembly, disassembly and other handling thereof, can be easily performed, for, since a stable outer drum construction, into which the inner drum has only to be inserted, is present, it is possible to provide the drive connection to an electric motor only on the outer drum, so that, when a change is made, the inner drum has only to be removed from the outer drum and another inner drum inserted back into this, without a large number of complicated assembly steps, such as the establishment of a drive connection to the drive shaft, being necessary for this purpose. 
     The outer drum can here fully surround the inner drum. However, a good stabilization of the rotating system is also already obtained if the outer drum axially only partially surrounds the inner drum, preferably over in any case 50% of the axial length of the inner drum or more. In the latter case, it is advantageous if the inner drum protrudes axially from the outer drum, which makes it easier to separate and to distance the inflow and outflow region of the inner drum clearly from the outer drum. 
     It is particularly advantageous if the inner drum and the outer drum consist of different materials, because, in that way, the optimal materials can respectively be chosen for both elements—outer drum and inner drum. Preferredly, the inner drum consists of a, once again, preferably relative thin-walled plastic or a plastics composite, so that it can easily be disposed of, and the reusable outer drum consists of metal, in particular of steel, so that its running characteristics can be optimized particularly well. 
     An added advantage in this is that, where a metallic outer drum and a plastics inner drum are used, the weight of the outer drum can significantly exceed that of the inner drum, so that the rotation behavior is substantially determined by the outer drum. In addition, the weight of the rotating parts of the metallic outer drum is more than twice as large, in particular more than four times as large, as the weight of the rotating plastics parts, or than the weight of the empty inner drum. As a result of the outer drum, it is also possible to shape the inner drum in a particularly thin-walled design, since it is stabilized by the outer drum. 
     In order to be able to insert the inner drum nicely and easily into the outer drum, it is advantageous if the outer drum has an outer drum bottom part, and an outer drum top part detachable therefrom. By contrast, it is advantageous, essentially for production reasons, if the inner drum has an inner drum bottom part, and an inner drum top part that is preassemblable or preassembled herewith. For it is necessary to place in the inner drum, in the course of the production, various elements, such as the clarifying means, an inflow tube and the like, which is made easier by the separation into top part and bottom part. 
     The fitting of the inner drum into the outer drum is particularly simple if the outer drum top part is configured in the style of a ring, which is screwed to the outer drum bottom part and which is configured open in the axially upward direction, so that the inner drum top part protrudes axially therefrom. The outer drum bottom part and the outer drum top part can also be connected differently. One advantageous variant is a connection with screw bolts. A bayonet is also conceivable as the connecting means. Finally, it is advantageous to connect the outer drum top part and the outer drum bottom part one to the other, or fix them relative to one another, with a locking ring. To this end, a lower rim of the outer drum top part is inserted into the outer drum bottom part, where it can rest on a collar. Next a ring with external thread is screwed from above into an internal thread of the outer drum bottom part, which ring fixes the outer drum top part on the outer drum bottom part. 
     In order to realize a reliable rotation, as far as possible without slippage between the inner drum and the outer drum, it is advantageous if the inner drum and the outer drum are non-positively and/or positively connected to one another in a rotationally secure manner. 
     For reasons of hygiene, it is further advantageous if the inflow and outflow system of the drum are arranged solely on the inner drum and on the housing, so that the outer drum does not, during operation, come into contact with the product to be processed. 
     All in all, including with the concept of the inner drum, some of the, and preferably even all of the product-touching regions of the rotating system consist of a plastic or a plastics composite, in particular the inner drum bottom part and inner drum top part and the plate assembly. Particularly preferredly, the inflow system and outflow system also consist of a plastic or a plastics composite. 
     It is particularly advantageous if all parts of the inner drum that rotate during operation, and the parts of its inflow and outflow system which do not rotate during operation—insofar as they come into contact with product—consist of plastic, and if all in all—except for any seals which might have to be provided—also only a small number of parts, for example plastics injection molded parts, are provided. Preferably these are the inner drum bottom part, the inner drum top part, the distributor, the separating means (preferably the plate insert for the separation of solids), a separating plate and the inflow and outflow system comprising the grippers and the inflow tube, which do not rotate. 
     In addition, there can be one or more extra sealing rings. In this way, there is created a functional, plastics centrifugal drum, consisting only of very few constituent parts, which makes their production and their assembly particularly simple. 
     In addition, it is here particularly advantageous if the inner drum bottom part and the inner drum top part are non-detachably connected to one another during the initial assembly in order to prevent any attempt to disassemble them and possibly reuse them after insufficient cleaning. Instead, the inner drum is fully disposed of and recycled. This has the added advantage that sterility is ensured. The design is preferably such that, prior to installation and following removal, no air can penetrate into the inner drum from outside. 
     With the concept of the inner drum, it is still possible, as in PCT International patent document WO 2014/000829 A1, to design a part of the drum, or preferably even the entire drum—preferably along with the inflow and outflow systems and regions—for single use, which is of interest and advantage in particular with regard to the processing of pharmaceutical products such as fermentation broths or the like, because, following operation for the processing of an appropriate product batch in the, during processing of the product batch, preferably continuous operation, no cleaning of the drum has to be performed, but rather the drum is exchanged in its entirety. Hygiene problems associated with a cleaning are hereby easily precluded. The product-touching parts can be wholly disposed of or recycled. Disposal is in particular also of interest in the case of hazardous substances. In turn, it is also conceivable, in a product clarification process, to primarily carry out a concentration of a product to be processed and to melt down the inner drum after the processing of a batch or, for instance, to dissolve it in an acid or the like in order to extract the heavy material as a residue of this process. Through the use of preferably thin-walled plastics parts, the production costs, moreover, can be kept relatively low. 
     It is here advantageous, as well as particularly hygienic, if the entire drum, in particular also its inflow and outflow system, is/are configured in sealed construction. 
     Preferably, a recyclable plastic, in particular PE (polyethylene), PP (polypropylene) or TK-PEEK (in particular partially crystalline) polyetheretherketone, is used as the plastic. Inter alia (and this is no definitive list), the materials PC (polycarbonate), MABS (methyl methacrylate acrylonitrile butadiene styrene), ABS (acrylonitrile butadiene styrene) and PSU (polysulfone), are also conceivable. 
     Those parts produced from plastic could be made in an injection molding process and, where appropriate, reworked, for example be provided with bores and the like where this is necessary. 
     Screws and the like can also consist of plastic, but they can also consist of a different material, in particular if they are not touched by the product in the course of the processing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The invention is described in greater detail below on the basis of illustrative embodiments, with reference to the figures, in which: 
         FIG. 1  shows in a) a side view of a separator according to the invention with a direct drive, in b) a detailed and detail-enlarged representation of an inflow and outflow region of the separator drum from a), and in c) a detailed and detail-enlarged representation of an alternatively designed outer peripheral region of a separator drum in the style of  FIG. 1   a ). 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1 a    shows a section through the region of a housing  1  and of a drum  2  of a separator according to the invention, with which a liquid product can in the centrifugal field be separated into two phases. The drum  2  has a vertical rotational axis D. Hereinafter used terms such as “(at the) top” or “(at the) bottom”, “radial”, etc. relate to the orientation of elements of the separator in relation to this vertical rotational axis. 
     The housing  1  has a bottom base  3 , a housing casing  4  and a top cover  5 . The base  3 , in turn, has a bushing  6 , which is passed through by a rotatable drive spindle  7 . Preferably, directly beneath the base  3  is arranged a drive motor  8 . This drive motor  8  serves to drive the drive spindle  7 . Alternative embodiments are conceivable, for example of the kind in which the drive spindle  7  is driven with a drive belt or the like, in which case the drive motor is arranged elsewhere. However, a direct drive, in particular in the style of  FIG. 1 a   , in which the drive shaft of the motor is arranged directly in vertical extension of the drive spindle  7 , is preferred. A dedicated mounting of the spindle construction is here preferably dispensed with, which makes the construction easily and relatively cheaply realizable. This construction is simple and robust and very well suited to the light drum construction. The function of the mounting of the drum is assumed in a simple manner by the electric motor or its rotor bearing. 
     The drum  2  is in turn mounted onto the vertically upper end of the drive spindle  7  such that it is non-rotatable relative to the drive spindle  7 , so that it can be set in rotation by the drive spindle  7  and the drive motor  8 . 
     The drive spindle  7  could be mounted in the housing  1 , in this case in the base  3 , rotatably with one or more bearings. However, such a mounting can also be dispensed with. In this case, a gap  9  is formed between the outer periphery of the drive spindle and the inner periphery of the bushing  6  of the base  3 . In that way, a mounting of a drive shaft  10  in the motor housing of the drive motor  8 , on which mounting the drive spindle  7  is fixed or on which mounting it is otherwise configured, can also easily be used for the mounting of the whole rotating system, consisting of the drum  2  and the drive spindle  7 . Thus, it is also preferred that the drive spindle  7  is directly coupled to the output shaft of the motor, and that the drive spindle  7  has no additional pivot bearing—for instance no collar bearing and no footstep bearing—on its outer periphery. Preferably, a spring system is also not provided for the resilient support in the region of the drive spindle. 
     The structure of the preferredly used drum  2  shall now be described in greater detail below. 
     The drum  2  has an outer drum  11 , which can also be configured as an outer drum portion—and an inner drum  12 . The inner drum  12  is inserted exchangeably in the outer drum  11 . 
     Preferably, the outer drum portion or the outer drum  11  and the inner drum  12  consist of different materials. Particularly preferredly, the outer drum  11  consists of metal, in particular of steel, and the inner drum  12  preferably consists wholly, or at least partially, of a plastic or a plastics composite. 
     The outer drum  11  here serves as a type of mounting, in which the inner drum  12  is inserted and which at least in some sections surrounds or borders the inner drum  12  in the vertical or axial direction over the whole of its periphery. Particularly preferredly, the outer drum  11  and the inner drum  12  are connected to one another in a rotationally secure manner. This can be realized in particular by a positive and/or non-positive engagement between the outer drum  11  and the inner drum  12 . 
     The outer drum  11  has an outer drum bottom part  13 , which can be, or in this case is configured substantially like the drum bottom part of known separators having no inner drum. The outer drum bottom part  13  is mounted in a rotationally secure manner on the drive spindle  7  and preferably has on the inside a single-conical, or here particularly preferredly, double-conical inner shape. The outer drum  11  preferably further has an outer drum top part  14 . Preferably, the outer drum bottom part  13  and the outer drum top part  14  have corresponding threads, in the region of which they are directly screwed together. The thread of the outer drum bottom part portion is configured as an internal thread of the drum bottom part, and the thread of the outer drum top part  14  as a corresponding external thread. 
     The outer drum top part  14  is likewise conically configured. It is further configured as a ring, which at the bottom is connected in a rotationally secure manner to the outer drum bottom part  13  and which is configured open in the axially upward direction, so that the inner drum  12  protrudes vertically or axially upward from the outer drum, in this case from the outer drum top part  14 . 
     Because the outer drum bottom part  13  and the outer drum top part  14  preferably consist of metal, in particular steel, and at least the drum bottom part is configured, like that of a separator drum, without an inner drum  12 , they can largely offer the quietness of running and stability and reliability of a known modern separator drum made of metal. Because the outer drum  11  partially or wholly surrounds the inner drum  12  on the outside, the outer drum stabilizes the inner drum. In particular, the outer drum  11  advantageously helps to optimize the running characteristics of the entire drum  2  during high-speed operation. Moreover, the wall thickness of the inner drum  12  can also be chosen very much thinner than that of a wholly plastics separator drum with no outer drum  11 , as proposed in PCT International patent document WO 2014/000829 A1. It should be noted that a yet to be described inflow and outflow system, however, even in constructions 
     By contrast, the inner drum  12  outwardly delimits the actual separating or centrifugal space  15  for the centrifugal processing of a flowable product. The inner drum  12  is designed, with respect to its shaping, such that it preferably bears, largely positively, directly against the inner periphery of the outer drum. 
     The inner drum  12  has an inner drum bottom part  16  and an inner drum top part  17 . Preferably, the inner drum bottom part  16  and the inner drum top part  17  are respectively conically configured, so that a double-conical body is formed. The parts  16  and  17  consist of plastic or a plastics composite and are connected to one another in a liquid-tight manner, in particular in upper (inner drum bottom part  16 ) and lower (inner drum top part  17 ) flange regions  18 ,  19  (see  FIG. 1 c   ). 
     Preferably, an integral connection between the inner drum bottom part  16  and the inner drum top part  17  and, where appropriate, of further elements of the inner drum  12 , is provided, which connection, within the meaning of this document, can be achieved by a fusion, for instance, but also by a bonding. This can clearly be seen, in particular, in  FIG. 1 c   . Other types of connection are also conceivable, such as a bayonet, or screw, or snap or latching fastening between the elements to be connected, namely inner drum bottom part  16  and inner drum top part  17  (not represented here). These can respectively also supplement the integral connection. 
     A distributor  21  is configured or arranged on the inner drum bottom part, at the top—in the form of a separate part or in the form of a part integrally connected to the inner drum bottom part—which distributor coaxially surrounds the rotational axis D and forms a complete distributor for the passage of the material to be centrifuged into the inner drum interior or centrifugal space  15 , and for the acceleration of the centrifuge material in the peripheral direction during rotations of the drum  2 . 
     The distributor  21  has a lower conical portion  22  and an upper tube section  23 , which is oriented concentrically to the rotational axis D and is upwardly open ( FIGS. 1 a  and 1 b   ). This tube section  23  opens out at the lower end into the one or more of the distributor channels  24 , which are configured obliquely to the rotational axis and open out, on a radius preferably on the outside of a plate assembly  25 , into the actual centrifugal space  15 . 
     In the centrifugal space  15  are arranged separating means or clarifying means, such as, in particular, the aforementioned one-piece or preferably multipart plate assembly  25 , which is configured as a stack of axially spaced separating plates  26 , which have a conical basic shape and which are preferably mounted in a rotation-proof manner onto the distributor attachment  21 . The separating means for the clarification could also be configured in different form, for instance as a ribbed body having radial or arcuate ribs. The separating plates  26  have same or different radii. 
     The distributor attachment or distributor  21  can also be configured in one piece with the clarifying means if this is configured as a plastic clarifying insert with clarifying chambers in the style of German patent document DE 10 2008 052 630 A1. A product fed into the inner drum interior or centrifugal space  15  is separated in the drum  2  into various, preferably two, product phases of different density. 
     Serving for the feed-in and evacuation of the various product phases from the drum  2  is an inflow and outflow system  27 , comprising at least one inflow device and at least two outflow devices (see, in particular,  FIG. 1 b   ). 
     As the inflow device, the inflow and outflow system has a peripherally closed inflow tube  28  of preferably cylindrical cross section, the center axis of which, in the fitted state, is aligned with the rotational axis D of the drum. 
     As the at least two outflow devices, the inflow and outflow system further has at least one, or preferably two, grippers  29 ,  30 —also referred to as skimmer disks. Neither the inflow tube  28  nor the two grippers  29 ,  30  rotate with the drum during operation. Rather, they remain stationary during operation. The inner drum top part  17  rotates about the inflow and outflow system  27  during operation. 
     The two grippers respectively have a disk portion  29   a ,  30   a  and a shank portion  29   b ,  30   b . The shank portions  29   b ,  30   b  are configured concentrically to the inflow tube  28  and to one another. 
     The grippers  29 ,  30  are formed of a plurality of gripper components, which respectively consist of a tube section and an annular disk portion, wherein the annular disk portion respectively extends radially to the tube section. Preferably, the gripper components respectively consist of plastic or plastics composite. In addition, they are preferably respectively configured in one piece. 
     The innermost and first of the gripper components is formed of the inflow tube  28  and an annular disk attachment  31  extending radially to the inflow tube  28 —in this case configured in an approximately axially central region of the inflow tube  28 . A second, third and fourth of these gripper components— 32 ,  33 ,  34 —are likewise respectively formed of a tube section  35 ,  36 ,  37  and an annular disk attachment  38 ,  39 ,  40  extending radially to this tube section at the end of the tube section. Preferably and advantageously, the tube sections  35 ,  36 ,  37  here respectively have different internal diameters, so that the tube sections  35 ,  36 ,  37  can be slid axially one into the other. 
     The tube section  35  of the second gripper component  32  is larger than the external diameter of the inflow tube  28  over which it is concentrically slid, such that an outflow channel  41  is formed between the external diameter of the inflow tube  28  and the internal diameter of the tube section  35  of the second gripper component  32 . Moreover, the annular disk attachment  38  of the second gripper component  32  is axially distanced from the first annular disk attachment  31  on the inflow tube  28  (together also corresponding to the first gripper component) such that these two annular disk attachments  31 ,  38  jointly form the disk portion  29   a  of the first gripper  29 . In that way, in the disk portion  29   a  of the first gripper  29  is likewise formed at least one radial outflow channel  42 , which opens out into the axial outflow channel  41 . Webs on the annular disk attachments  31 ,  38  can delimit the channel  41 . 
     The third and the fourth gripper component  33 ,  34  jointly form the second gripper. 
     In addition, the tube section  36  of the third gripper component  33  is preferably and advantageously larger than the external diameter of the tube section  35  of the second gripper component  32  over which it is concentrically slid, such that it bears directly against the external diameter of the tube section  35  of the second gripper component. Preferably, the second gripper component  32  and the third gripper component  33  are connected, in particular welded or bonded, to one another. This connection exists preferably at least at the ends of the tube sections  35 ,  36 , so that a gap between the tube sections  35 ,  36  is sealingly closed. The annular disk attachment  39  of the third gripper component  33  is arranged axially offset from the annular disk attachment  38  of the second gripper component  32 . 
     In order to form the second gripper  30 , the tube section  37  of the fourth gripper component  34  is larger than the external diameter of the tube section  36  of the third gripper component  33  over which it is concentrically slid, such that an axial outflow channel  43  is formed between the external diameter of the tube section  36  of the third gripper component  36  and the internal diameter of the tube section  37  of the fourth gripper component  34 . Moreover, the annular disk attachment  40  of the fourth gripper component  34  is axially distanced from the annular disk attachment  39  on the third gripper component  33  such that these two annular disk attachments  39 ,  40  jointly form the disk portion  30   a  of the second gripper  30 . In that way, in the disk portion  30   a  of the second gripper  30  is likewise formed a radial outflow channel  44 , which opens out into the axial outflow channel  43 . Webs on the axial disk portions (in the axial direction) can delimit the at least one radial outflow channel  43 . 
     A cover  45  is placed over the four gripper components. This is configured as a multistepped, peripherally closed tube of cylindrical diameter, wherein the steps  46 ,  47 ,  48  respectively axially delimit tube sections  49 ,  50 ,  51 ,  52  of different diameter. 
     The first tube section  46  here advantageously forms, in a simple manner, also a connecting branch (for a hose or the like). It lies vertically or axially above the inflow tube  28  and is aligned therewith. The first step  49  bears axially against the end of the inflow tube. The second tube section  50  overlaps the inflow tube  28  on the outside. The second tube section  50  and the inflow tube  28  are here connected, in particular welded or bonded, to one another (connecting region  53 ), so that a gap between the inflow tube  28  and the cover  45  is sealingly closed. 
     Beneath the connecting region  53  is formed the second step  47 , which is downwardly adjoined by the third tube section  51 , which delimits on the outside an evacuation chamber  54  for the first gripper  29 , the inner periphery of which evacuation chamber is formed by the outer periphery of the feed tube  28 . On the outer periphery of this evacuation chamber  54  is formed a connecting branch  55 . A hose or the like for the evacuation (not represented here) can be attached to this. 
     The third tube section  51  of the cover  45  overlaps on the outside the tube section  36  of the third gripper component, or the first gripper  29 . The third tube section  51  of the cover  45  and the first gripper  29  are connected, in particular welded or bonded, to one another (connecting region  56 ), so that a gap between these elements is sealingly closed. 
     Beneath the connecting region  56  is formed the third step  48 , which is downwardly adjoined by the fourth tube section  52 , which delimits on the outside an evacuation chamber  57  for the second gripper  30 , the inner periphery of which evacuation chamber is formed by the portion  35 . On the outer periphery of this evacuation chamber  57  is in turn formed a connecting branch  58 . To this can be attached a hose or the like for the evacuation (not represented here). 
     The fourth tube section  52  of the cover  45  overlaps on the outside the tube section  37  of the fourth gripper component, or the second gripper  30 . The fourth tube section  52  of the cover  45  and the second gripper  30  are here connected, in particular welded or bonded, to one another (connecting region  59 ), so that a gap between these elements is sealingly closed. 
     Extending radially outward from the fourth tube section  52  is an annular disk portion  60 . This annular disk portion of the cover  45  bears beneath the housing  1  in a flange-like manner against this same. The housing  1  and the cover  45  are preferably detachably connected to one another in this region, for instance by means of one or more bolts  61 . The cover  45  protrudes vertically upward through a central opening in a cover  5  of the housing  2 . 
     The interplay between the inflow and outflow system  27 , which does not rotate during operation, and the rotatable (inner) drum shall now be discussed in greater detail below. 
     A separating plate  62  is arranged above the parting plate assembly  25  (see also  FIG. 1 b   ), a gap  63  as the outflow channel is formed between the bottom side of the inner drum top part  17  and the top side of the separating plate  62 . In addition, above the separating plate  62  lies a supporting body  20 , here a supporting ring, to ensure for stabilizing the construction above the plate assembly and for ensuring a defined seat of the plate assembly. 
     A heavier liquid phase (or a still just evacuatable, in particular only just somewhat flowable solid phase) is evacuated from the region of the largest inner periphery of the drum interior, through the gap  63  or a channel in the gap between the inner drum top part  17  and the separating plate  62 , out of the centrifugal space. 
     The separating plate  62  and the inner drum top part  17  pass at their axially upper ends into cylindrical portions  64 ,  65 . At the vertically upper ends, annular disk portions  66 ,  67  respectively radially extend radially inward from these cylindrical portions  64 ,  65 . The annular disk portion  66  of the cylindrical portion of the separating plate  62  extends radially between the disk portions  29   a ,  30   a  of the two grippers  29 ,  30 . The annular disk portion  67  of the cylindrical portion  65  of the inner drum top part  17  extends radially above the disk portion  30   a  of the second gripper  30 . 
     Beneath the first gripper  29 , an annular disk contour  68  extends, likewise radially, inward in the manner of an annular disk. This can be configured as a radial attachment of the distributor  21 , or differently, for example as an attachment of the separating disk. In that way gripper chambers  69 ,  70  are formed in the interplay of the cylindrical portions  64 ,  65  and the annular disk portions and contours  66 ,  67 ,  68 . From the gap  63 , the heavier phase flows through the gap between the two cylindrical portions and into the upper gripper chamber  70 , where the second gripper  30  evacuates this phase. 
     A channel  71  on the inside of the separating plate assembly  25  further leads the lighter phase, flowing radially inward out of the separating plate assembly  25 , into the first, lower gripper chamber, from which the first gripper  29  evacuates the lighter phase. 
     Ribs  77 ,  78  on the annular disk portion  66 , as well as preferably ribs  79  on the annular disk portion  67  and preferably ribs  80  and ribs  81  on the distributor  21  and on the supporting body  20 , ensure transportation of the appropriate product phases during operation of the centrifuge. 
     The inflow and outflow system is designed in an advantageous and structurally simple manner as a system which does not rotate with the inner drum during operation, i.e., the inner drum  12  rotates during operation relative to or about this inflow and outflow system  27 . An axially acting ring seal device  72  is therefore preferably and advantageously provided between the annular disk portion  67  of the inner drum top part  17  and the annular disk portion  60  of the cover  45 . This can be spring-preloaded and/or configured similar to a face seal. A slidingly sealed bearing contact of the mutually rotating elements “cover  45  of the inflow and outflow system  27 ” and (inner) “drum top part  17 ” is advantageous in order to seal in a sanitary manner the region between the inflow and outflow system  27 , which is stationary during operation, and the rotating drum  2 . 
     The inner drum  12  is positively and/or non-positively connected to the outer drum  11  in order easily to connect the inner drum and the outer drum  12 ,  11  one to the other in a rotationally secure yet detachable manner. In a simple manner, a non-positive connection can be realized by virtue of the fact that the flange regions  18  and  19 , as well as, where appropriate, also an outer rim of the separating plate  62 , extend into the screw connection region between the outer drum bottom part and the outer drum top part, where they respectively bear against steps of these parts and, when the drum top part is screwed in the drum bottom part, are clamped in a screw locking manner between these ( FIG. 1 c   ). 
     In addition, positive-locking means, such as ribs on the outer periphery of the inner drum and corresponding grooves on the inner periphery of the outer drum  11 , can be provided, which positive-locking means mutually engage and in that way connect the two elements, inner drum  12  and outer drum  11 , in a rotationally secure manner (not represented here). During operation, the inner drum  12  will come to lie, moreover, in a radially expanding manner, against the inner periphery of the outer drum  11 , which improves the torque transmission and rotating transportation of the inner drum  12  by the driven outer drum  11 . Alternatively, it would also be conceivable to connect the parts of the outer drum detachably to one another in a different manner, for instance with screw bolts or the like, or by means of a bayonet. 
     In that way, some, or preferably even all of the product-touching regions of the rotating system consist of plastic or plastics composite, in particular the inner drum bottom part  16  and the inner drum top part  17 . Particularly preferredly, the separating plates  26  also consist of plastic, as well as all of the product-touching regions of the inflow and outflow system, also insofar as these do not rotate during operation. 
     Accordingly, the inner drum  12  can be disposed of after processing a sufficiently large product batch. By contrast, the preferably metallic outer drum  11  is reused. Because it cannot come into contact with product during operation, its cleaning is very simple or less important. By virtue of the outer drum  11 , the inner drum  12  can be realized in very thin-walled construction. In the event of a complete disposal, very little plastics waste accordingly accrues. 
       FIG. 1  shows an embodiment as a two-phase separating machine (separation of a product into the phases: “liquid/liquid”), though three-phase machines (for separation into three phases) are likewise feasible (not represented here). The product is preferably, but not necessarily, a concentrating fermentation broth. 
     In that way, preferably the entire inner drum, along with the inflow and outflow system, is preferably designed as an exchangeable preassembled module made of plastic or a plastics composite. 
     The outer drum portion  11  here serves substantially as a mounting for the inner drum  12 , which outer drum portion improves in particular the running characteristics of the inner drum  12 . 
     The design of the outer drum top part as a ring is optimized in tests. It can be determined into which conical region, in the upward direction, the annular outer drum cap or the outer drum top part must surround the inner drum top part. 
     The structure of the housing  1  shall be considered once again in greater detail below. The housing  1  has the base  3 , an in this case conical housing casing  4 , and the cover  5 . Only in the region of the cover  45  of the inflow and outflow system  27  does the housing  1  come into contact with the plastics region that is disposable after one operation. The cover is suitably fastened—preferably with bolts  75 —to the housing casing  4  ( FIG. 1 b   ). The housing casing  4  is further fastened—preferably with bolts  76 —to the base  3  ( FIG. 1 b   ). These bolts  75 ,  76  (or other suitable connecting means) are arranged releasably in order to be able to easily change the inner drum  12 . 
     In order to change the inner drum  12 , the housing  1  is opened (bolts  75 ,  76 ) and the bolts  61  for the cover  45  of the inflow and outflow system  27  are released. Then the inner drum  12  is exchanged and, where appropriate, disposed of. The cover  5  is here intended to have preferably a central opening of such a size that it can be placed from above over the cover  45  of the inflow and outflow system with its feed and evacuation branches and, where appropriate, hoses which are attached thereto and which, following fitting, have merely still to be connected up to external connections. In that way, the fitting of the inner drum following the removal of the outer drum top part can be realized in a particularly simple and rapid manner. The hoses can be sealed, for instance welded, at the ends, and are cut off upon initial start-up and resealed following initial start-up. This can also be realized with clamps. 
     Preferably, the entire inner drum  12  is sanitary in design. 
     The housing  1  can be used to rest against a foundation or a stand  74  or a type of table or cabinet. 
     It is advantageous that the housing  1  has an outflow opening  73 , preferably in its base  3 , through which, where appropriate, liquid—which appears in the housing, for instance due to an unforeseen leakage, or which would collect there for some other reason, can flow off. To this end, at a connection of the opening  59  can be arranged an evacuation line, such as an outflow hose, for the evacuation of this liquid into a container. 
     A particularly compact construction is achieved by virtue of the fact that—as already discussed in the introduction—the drive motor is preferably an electric motor, which is arranged directly in axial extension of the drive spindle  7 , preferably on the side facing away from the drum. Preferably, the drive spindle  7  is connected directly with a bolt to the output shaft  10 . It is further connected in a rotationally secure manner with a torque transmission means, preferably a feather key, in the peripheral direction, to the output shaft of the electric motor (not represented here). The torque transmission means can also be configured in a different form—for instance as a torque transmission contour (in each case not represented here). A terminal box  75  is arranged on the motor  8 . 
     The rotatable drum  2  can be connected to the drive spindle construction with a press fit (for example in a conical portion), or by means of some other torque transmission means (not represented here). The motor  8  is, on its side facing toward the spindle  7 , further fastened with a flange portion to the base of the housing  1 , for instance with screw bolts. On the motor  8  is further arranged a terminal box. 
     Although the invention has been illustrated and described in detail by way of preferred embodiments, the invention is not limited by the examples disclosed, and other variations can be derived from these by the person skilled in the art without leaving the scope of the invention. It is therefore clear that there is a plurality of possible variations. It is also clear that embodiments stated by way of example are only really examples that are not to be seen as limiting the scope, application possibilities or configuration of the invention in any way. In fact, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete manner, wherein, with the knowledge of the disclosed inventive concept, the person skilled in the art is able to undertake various changes, for example, with regard to the functioning or arrangement of individual elements stated in an exemplary embodiment without leaving the scope of the invention, which is defined by the claims and their legal equivalents, such as further explanations in the description. 
     REFERENCE SYMBOLS 
     
         
         Housing  1   
         Drum  2   
         Base  3   
         housing casing  4   
         cover  5   
         bushing  6   
         drive spindle  7   
         drive motor  8   
         gap  9   
         drive shaft  10   
         outer drum  11   
         inner drum  12   
         outer drum bottom part  13   
         outer drum top part  14   
         centrifugal space  15   
         inner drum bottom part  16   
         inner drum top part  17   
         flange regions  18 , 19   
         supporting body  20   
         distributor  21   
         conical portion  22   
         tube section  23   
         distributor channels  24   
         plate assembly  25   
         separating disk  26   
         inflow and outflow unit  27   
         inflow tube  28   
         grippers  29 , 30   
         disk portion  29   a , 30   a    
         shank portion  29   b , 30   b    
         first annular disk attachment  31   
         gripper components  32 , 33 , 34   
         tube section  35 , 36 , 37   
         annular disk attachment  38 , 39 , 40   
         outflow channels  41 , 42 , 43 , 44   
         cover  45   
         steps  46 , 47 , 48   
         tube sections  49 , 50 , 51 , 52   
         connecting region  53   
         evacuation chamber  54   
         connecting branch  55   
         connecting region  56   
         evacuation chamber  57   
         connecting branch  58   
         connecting region  59   
         annular disk portion  60   
         bolt  61   
         separating plate  62   
         gap  63   
         cylindrical portions  64 , 65   
         annular disk portions  66 , 67   
         annular disk contour  68   
         gripper chambers  69 , 70   
         channel  71   
         ring seal device  72   
         outflow opening  73   
         stand  74   
         bolts  75 , 76   
         ribs  77 , 78 , 79 , 80 , 81   
         vertical rotational axis D