Abstract:
The present invention relates to a centrifuge including a centrifugal drum, a supply pipe, a distributor, a displacement sleeve valve having an opening chamber and a closing chamber, a supply duct, a control gas feed in the distributor and a closing spring biasing the sleeve valve towards a closed condition during a pressure buildup in the opening chamber. The present invention also relates to a method of operating the centrifuge using a control gas to operate the sleeve valve and cleaning of control fluid paths by guiding a flushing fluid or flushing gas through the control fluid paths.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a centrifuge which has the following: A centrifugal drum, a supply pipe which leads into the centrifugal drum for introducing a material for the centrifugal process into the centrifugal drum, and a supply duct for supplying a control fluid into an opening and/or closing section of the centrifugal drum. The invention also relates to a method of operating a centrifuge according to the invention. 
     A centrifuge of this type is known from German Patent Document DE 28 22 478. The centrifuge illustrated in that document has a centrifugal drum with a sleeve valve to which a chamber is assigned which is connected by ducts in a spindle with a hydraulic system. The introduction of the product takes place from above by way of a central supply pipe. The spindle is situated on the underside of the centrifugal drum. Although this construction has been found to be successful per se, it reaches its limits when, for hygiene reasons, the product area is to be situated separately from the driving area of the centrifuge and the control elements of the drive as well as the control elements of the control fluid supply outside the drum (valves, etc.). 
     From German Patent Document DE-A-2808677, the use of a gaseous medium as control fluid is known, the supply duct being concentrically to the supply pipe for the process material. 
     A centrifuge of the above-mentioned type is known from U.S. Pat. No. 4,044,945. However, this construction does not ensure that, for reasons of hygiene, the product area is situated separate from the driving area of the centrifuge and the control elements of the drive as well as the control elements of the control fluid supply outside the drum (valves, etc.). 
     The object of the invention consists of further developing the centrifuge of the above-mentioned type such that a gaseous medium can be used as a control fluid in order to permit an uncomplicated handling and the use under sterile conditions. 
     The invention achieves this goal because the control fluid supply and the material supply are thus jointly guided into the centrifugal drum and preferably extend also directly side-by-side, a constructively separate supply of the control fluid can be avoided. 
     The invention is particularly suitable for a centrifuge wherein the centrifugal drum hangs on a centrifuge frame, the supply pipe for the process material and the supply duct for the control fluid extend jointly from above into the centrifugal drum. In the case of centrifuges with hanging centrifugal drums, a separate feeding of the control fluid from below into the drum is not practical because it may be necessary to collect the solids separated in the separation process below the drum in a sterile container. This is clearly simplified by the control fluid supply “from above”. 
     A double-walled pipe has the advantage of a particularly space-saving housing of the control fluid supply and of the process material supply. 
     In this case, the control fluid supply is used for operating a displaceable sleeve valve for opening and closing discharge openings for solids in the centrifugal drum. In this case, an opening chamber and a closing chamber adjoin the sleeve valve. The sleeve valve is moved by the admission of pressure by means of the control fluid, in which case it is also possible to hold the sleeve valve in a spring-tensioned manner in one of its operating positions and move it into the respective other operating position by a pressure buildup in the corresponding control chamber. 
     In this case, a gaseous medium, preferably sterile air, is used as the control fluid, which can be handled in an uncomplicated manner and is well suited for a use as a control medium under sterile conditions, because, also in the event of a direct contact with the process material, a contamination of the latter will be prevented. 
    
    
     Other objects, aspects and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The FIGURE is a sectional view of a centrifuge according to the invention with a sleeve valve which is illustrated in its opening position in the left section of the drawing and in its closing position in the right section of the drawing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     It should be noted that terms such as “bottom” and “top” relate to a centrifuge in the case of which the supply pipe extends essentially perpendicularly and the centrifugal drum hangs on the bottom on a centrifuge frame. These terms should definitely not be considered to be limiting. 
     The FIGURE shows a centrifuge which is constructed as a separator and which, in a manner known per se, has a centrifugal drum  2  adjoined toward the bottom for separating a process material into different components. The process material or the process liquid are guided in the downward direction through a central supply pipe  4  into the centrifugal drum  2 . 
     The centrifugal drum  2  is suspended on a centrifuge frame  6  with a lower frame attachment  8 . The driving section  10  of the centrifuge—which can be constructed in a manner known per se and will therefore not be shown here in detail—is arranged above the centrifugal drum  2  in the and/or at the centrifuge frame  6  and is sealed off from the centrifugal drum  2  by a sealing section  12 —which is also not shown in detail—in the frame attachment  8 . The centrifugal drum  2  is therefore clearly constructively separated from its driving section as well as the control elements of the driving section. 
     A container lid  14  is flanged to the lower end of the frame attachment  8 , which container lid  14  is penetrated in the center by the supply pipe  4 . The container lid  14  here has an essentially radially constructed bore  16  which is used as a drainage duct for a liquid phase discharged, by a rotary-cut disk  18 , from a rotary-cut chamber  20  from the centrifugal drum  2 . The bore  16  leads into a drainage pipe  22 . 
     An upper container jacket  24 , which surrounds the centrifugal drum  2  in its upper area, is molded to the container lid  14 . This container jacket  24  is used as an upper end of a container  26 , which is conical here, for receiving solids. The lower section  28  of the container is removable from the centrifuge in the downward direction and stands in a container frame  30 . 
     The actual centrifugal drum  2  has a distributor  32  which surrounds the supply pipe  4  and which has a plate stack  34  joined on the outside to the distributor  32 . The plate stack  34  is situated in a centrifugal space  36  which conically narrows, in this case, in the upward and downward direction. The centrifugal space  36  is limited in the upward direction by a conically shaped drum lid  38  and in the downward direction by a centrifugal space bottom  40  molded at the bottom onto the distributor  32 . The drum lid  38  is inserted into a drum bottom part  42  and, in the drum bottom part  42 , is screwed to a closing ring  44 . 
     Between the centrifugal space bottom  40  and the lower housing wall of the drum bottom part  42 , a displaceably guided, ring-shaped sleeve valve  46  is arranged which has a wall cross-section which is essentially L-shaped in this case and which is adjoined upward by an opening chamber  48  and downward by a closing chamber  50 . The lower wall of the drum bottom part  42  is used as the lower closing chamber bottom  52 . Between the lower wall of the sleeve valve  46  and the closing chamber bottom  52 —this in the closing chamber  50 —are closing springs  54  which hold the sleeve valve  46  in the closing position closing off the discharge openings  56  for the solids in the exterior jacket of the drum bottom part  42  (right portion of FIG.  1 ). 
     The opening chamber  48  is constructed between the sleeve valve  46  and the lower wall of the distributor  32  or the centrifugal space bottom  40 . The control fluid supply into the opening chamber  48  takes place by way of a control fluid feed  58  in the distributor  32 . 
     The control fluid feed  58  leads into a ring-shaped supply duct  60 , which surrounds the supply pipe  4 , between the interior wall of the distributor  32  and the supply pipe  4  inserted into the distributor  32 . In this case, the interior wall of the distributor  32  and the wall of the supply pipe  4  form a type of “pipe with a double wall”, the actual supply duct  60  for the control fluid concentrically surrounding the supply pipe  4  for the process material. 
     In the FIGURE, the distributor  32  of the centrifuge extends through the latter in one piece from the upper end area of the centrifuge frame  6  to the closing chamber bottom  52 . However, in practice, this element is preferably assembled of several parts. 
     Above the upper end area of the centrifuge frame  6 , an axial connection  62  permits the feeding of the process material into the supply pipe  4 . A connection  64 , which extends radially to the outside here, is used for feeding the control fluid—particularly the supplying of sterile control air—into the supply duct  60  surrounding the supply pipe. 
     The operation of the centrifuge of the FIGURE is as follows: 
     The feeding of the process material takes place through the connection  62  and the supply pipe  4  as well as through an axial bore  66  of the distributor  32  and a bore  68  in the centrifugal space bottom  40  into the centrifugal space  36 . Solids are discharged from the centrifugal space  36  through the openings  56 ; liquid phases are discharged through the rotary-cut chamber  20  with the rotary-cut disk  18 . 
     The control air is fed as the control fluid through the connection  64  into the supply duct  60  concentrically surrounding the supply pipe  4 . From there, the control air flows into the control fluid feed  58  and from there into the opening chamber  48 . As a result, when the pressure buildup in the opening chamber  48  is sufficiently large, the sleeve valve  46  is pressed downward against the spring force of the closing springs  54 , which opens up the outlet openings  56  for the solids (left section of FIG.  1 ). In contrast, a lowering of the pressure in the opening chamber  48 , because of the spring force of the closing springs  54 , results in a displacement of the sleeve piston  46  in the upward direction, which closes the outlet openings  56  for the solids again. 
     The sleeve valve  46  and the exterior wall of the centrifugal drum  2  have passage bores  70 ,  72 , which are in a mutual operating connection in one of the working positions of the sleeve valve and can be closed by means of a stopper  74 , after the removal of the stopper  74 . A simple possibility is obtained for cleaning the control fluid paths ( 40 ,  58 ,  48 ) as well as additional centrifugal elements, for example, by means of a flushing liquid or a flushing gas, for example, for a particularly uncomplicated implementation of a CP cleaning in place) process.