Centrifugal separator with slide valve for intermittent discharge of sludge
United States Patent 1 I1 3,878,981 Teckentrup Apr. 22, 1975 [54] CENTRIFUGAL SEPARATOR WITH SLIDE 2,487,364 11/1949 Ortenblad 2.33/20 A VALVE FOR INTERMITTENT DISCHARGE 255L041 5/1951 Nielsen 233/20 A OF SLUDGE 2,840,302 6/]958 Stcmacker et al. 233/20 A 3.765.599 10/1973 Hemfort 233/20 A [75] Inventor: Theodor Teckentrup, Oelde,  
 Germany [73] Assignee&#39;. Westfalia Separator AG, Oelde (Westfalen), Germany [22] Filed: Feb. 20, 1973 [2]] App]. No.: 334,165  
 [30] Foreign Application Priority Data Feb. 23, 1972 Germany 2208490 [52] US. Cl.....; 233/20 A [St] Int. Cl. B04b 1/14 [58] Field of Search..... 233/20 R, 20 A. 19 R, 19 A [56] References Cited UNITED STATES PATENTS 2.091.329 8/1937 Nyrop 233/20 A Primary E.ranziner-George l-l. Krizmanich Attorney, Agent, or Firm-Burgess, Dinklage &amp; Sprung [57] ABSTRACT A centrifugal separator having an annular slide valve for intermittent discharge of sludge. A control chamber for receiving fluid for shifting of the slide valve is communicated with a capture chamber for the fluid disposed adjacent the axis of the drum by a conduit communicating with the control chamber adjacent the outer periphery of the slide valve. Thereby a rapid build up of pressure in the control chamber is realized.  
 12 Claims, 1 Drawing Figure CENTRIFUGAL SEPARATOR WITH SLIDE VALVE FOR INTERMITTENT DISCHARGE OF SLUDGE BACKGROUND The invention relates to a centrifugal separator with a hydraulically operated slide valve for the periodical opening of the discharge apertures for the discharge of solids separated from a carrier liquid, and with one or two control chambers, each communicating through passages with a central trough for capturing control fluid and producing the shifting of the slide valve by alternate filling and emptying. Separators of this type, but of various construction, are described for example in German Patents Nos. 1,091,039 and 2,041,371 and in U.S. Pat. No. 2,126,864.  
  In all of the previously known separators of this type the control fluid for the operation of the slide valve is fed from a central capturing trough through passages to the radially inward portion of the control chamber or chambers. Since these chambers are not provided with ribs to drive the control fluid, the latter in its outward course lags behind the angular velocity of the drum increasingly as its distance from the axis of rotation increases, and it describes a spiral path. It therefore does not arrive by the shortest route at the radially outermost and most effective part of the control chamber, and its angular speed is lagging. A certain amount of time elapses before it attains the angular velocity of the drum due to friction on the chamber walls.  
  The air present in the control chambers is largely displaced inwardly by the entering control fluid and interferes with entry thereof. This appreciably delays the build-up of the optimum opening and closing force.  
  lt may also be seen from German Patent No. 1,091,039 that, in addition to the disadvantageous feed of control fluid to the central portion of the control chamber, the opening chamber is provided with a pcripheral discharge bore and the closing chamber has a relatively large capacity and a portion of the closing fluid remains in it even when the slide valve is in the opening position. Both of these features additionally impede the movement of the slide valve to its opening position. On the one hand, when the opening chamber is filling a portion of the arriving control fluid escapes through the discharge bore, thereby retarding the build-up of the opening force, and to limit this delay the cross-section of the discharge bore is kept small. On the other hand, the opening force that is building up in the opening chamber has to overcome the closing force that is constantly acting from the closing chamber, and due to the small cross section of the discharge bore the opening chamber also empties itself but slowly, so that the closing of the drum cannot take place spontaneously.  
  In addition to the disadvantageous feed of control fluid into the central part of the closing chamber it may also be seen from German Patent No. 2,041,371 that the closing chamber is provided either with a peripheral discharge bore or with a controllable outlet valve for the closing fluid. A calibrated discharge bore impedes both the rapid build-up as well as the rapid dropoff of the closing force, while an outlet valve assures only the rapid drop-off of the closing force.  
  It is in the prior art from US. Pat. No. 2,126,864 to provide each of the two control chambers with its own capturing trough and its own control fluid feed line.  
  Both in the case of total emptying and in the case of partial emptying of the drum it is advantageous to bring the slide valve as rapidly as possible to its opening position so that the solids will be ejected uniformly over the entire circumference. In the partial emptying of the drum it is furthermore advantageous to bring the slide valve as rapidly as possible back to the closing position so that only the radially outer portion of the solid stratum having the lowest moisture content will be ejected.  
 THE INVENTION The invention is addressed to the problem of constructing a centrifugal separator of the described kind in such a manner that the slide valve will be moved rapidly back and forth between its end positions.  
  This problem is solved by the fact that the passages joining a capturing trough with a control chamber open into the peripheral part of the control chamber, from which a passage leads to a controllable outlet valve which of itself is in the prior art.  
  In a separator thus constructed, the control fluid travels by the shortest path to the peripheral part of the control chamber where the greatest opening or closing force develops. Any lagging of the control fluid behind the angular velocity of the drum will be impossible on account of the entraining action of the connecting passages.  
  Another advantage results from the fact that the control fluid displaced radially inward in the control chamber by the incoming fluid will move faster than the angular velocity of the drum, thereby reinforcing the opening or closing force. The air that is in the control chambers will be displaced from the outside to the inside thereby preventing turbulence etc.  
  In further development of the main idea of the invention, the axial height of the control chambers can be adapted to the stroke of the slide valve, so that the latter will virtually make contact in its end positions. As a result of this volume reduction the filling time and the emptying time are additionally shortened.  
  The controllable outlet valve is so dimensioned with regard to its flow cross sections that, in the opening position, the control fluid, under the action of centrifugal force, is spun out almost instantaneously.  
 THE DRAWING An example of the embodiment of the invention is shown in the drawing, on a drum with only one control chamber. For the periodical opening of the discharge opening or annular gap 2, the slide valve 1 is moved from one end position to the other by the filling and emptying of the control chamber 3. The left half of the drawing shows the slide valve in the closed position, the right half shows it in the opening position. The slide valve 1 extends from the hub 12 of the drum to the outer periphery thereof.  
  From the central capture trough 4 for the control fluid a plurality of passages 5 lead to the peripheral part of the control chamber 3 which is provided on the inner end with an air vent bore 6. The orifice of this bore is located at a shorter distance from the axis of rotation than the free fluid level which establishes itself in the trough 4 during operation. A passage 7 leads from the radially outermost portion of the control chamber 3 to a controllable outlet valve 8 which is of the prior art. The valve 8 which is used in this embodiment is held in the closing position by the constant delivery of a small amount of fluid through the passage 9. Passages 5 and 9 may therefore run from the same capture trough 4. After the fluid feed through line 10 has been shut off, the fluid is spun out of passage 9, valve 8 is opened by the pressure of the control fluid in chamber 3, and chamber 3 is emptied virtually instantaneously. Thus passage 9 serves a control means for the outlet or release valve 8.  
  The axial height of the control chamber 3 may be adapted to the length of the stroke of the slide valve 1, so that the latter. when in the opening position, will make contact with the lower portion 11 of the drum, as shown in the right half of the drawing. It is then desirable, however, to provide the radially outermost part of the control chamber 3 with a trough-like recess 3a into which the control fluid delivered through passages 5 can freely enter.  
  The valve 8 may also be constructed such that it is closed in the fluid-free state and is opened by the delivery of a small amount of fluid. This requires two separate capture troughs 4 and two separate feed lines 10.  
  In a separator having two control chambers, the fluid must alternately be let out of the one chamber and at the same time be let into the other chamber. This alternating control is merely an alternating opening and closing of valves in different control fluid feed lines, which can easily be achieved with a controller.  
  Thus, the invention is directed to a centrifugal separator constructed for intermittent discharge of sludge, comprising a rotatably mounted separator drum, and annular slide valve coaxially disposed in the drum slidable between an open position for discharge of sludge from the outer periphery of the drum and a closed position for retension of sludge within the drum. At least one annular control chamber is provided for the slide valve for receiving control fluid for shifting of the valve between said valve positions. Means are also provided for controlled release of control fluid from the control chamber at the outer periphery of the drum, for emptying fluid from a control chamber for reverse shifting of the slide valve between said valve positions. A capture chamber is disposed adjacent to the axis of the drum for receiving control fluid, and conduit means communicate the capture chamber with the control chamber for delivery of control fluid to the control chamber. The invention provides the improvement which comprises connecting the conduit between the capture chamber and the control chamber. with the control chamber adjacent the outer periphery of the control chamber. The locus of the connection is best at the outer periphery of the control chamber, and is desirably at least 75%, better 90% of the distance from the axis of the drum to the outer periphery of the control chamber.  
  The means for controlled release of fluid from the control chamber at the outer periphery of the drum can comprise a release valve such as valve 8, and control means for the release valve for opening of the release valve for emptying of the control chamber and closing of the release valve for filling of the control chamber.  
  The control chamber is defined on one side by the slide valve and on the opposite side by a portion of the drum, and, desirably, with the slide valve in the open position, said sides are in contact.  
  Another desirably construction feature is a passageway communicating the inner portion of the closing chamber with the atmosphere at a point radially inward of the capture chamber.  
 What is claimed is:  
  l. [n a centrifugal separator constructed for intermittent discharge of sludge, comprising:  
 a. a rotatably mounted separator drum having at least one discharge opening in the outer periphery of the drum for discharge of sludge from the drum,  
 b. an annular slide valve coaxially disposed in the drum extending from the hub of the drum to the outer periphery thereof and being slidable between an open position for discharge of a sludge through the discharge opening and closed position for retension of sludge within the drum,  
 c. at least one radially extending annular control chamber for the slide valve for receiving control fluid for shifting of the valve between said valve positions,  
 d. means for controlled release of control fluid from the control chamber at the outer periphery of the drum, for emptying of fluid from the control chamber for reverse shifting of the slide valve between said valve positions,  
 e. a capture chamber adjacent to the axis of the drum for receiving control fluid and a conduit communicating the capture chamber with the control chamber for delivery of control fluid to the control chamber,  
 the improvement which comprises:  
 f. said conduit which communicates the capture chamber with the control chamber, connecting with the control chamber adjacent the outer periphery of the control chamber.  
  2. Appratus according to claim 1, wherein said means for controlled release of fluid from the control chamber at the outer periphery of the drum comprises a release valve, a passageway communicating the control chamber with the release valve, and control means for the release valve for opening of the release valve for emptying of the control chamber and closing of the release valve for filling of the control chamber.  
  3. Apparatus according to claim 2, wherein the control chamber is defined on one side by the slide valve and on the opposite side by a portion of the drum, and with the slide valve in the open position said sides are in contact.  
  4. Apparatus according to claim 3, wherein means define a trough-like recess at the outer periphery of the control chamber communicating with the conduit communicating the capture chamber with the control chamber.  
  5. Apparatus according to claim 1, wherein the control chamber is defined on one side by the slide valve and on the opposite side by a portion of the drum, and with the slide valve in the open position said sides are in contact.  
  6. Apparatus according to claim 5, wherein means define a trough-like recess at the outer periphery of the control chamber communicating with the conduit communicating the capture chamber with the control chamber.  
  7. Apparatus according to claim 1, wherein means define a trough-like recess at the outer periphery of the control chamber communicating with the conduit communicating the capture chamber with the control chamber.  
 chamber with the atmosphere at a point radially inward of the capture chamber.  
  11. Apparatus according to claim 1, wherein said conduit connects with the control chamber only at the outer periphery of the control chamber.  
  12. Apparatus according to claim 1, wherein there is only one control chamber and the control chamber extends from the hub of the drum to the outer periphery of the drum.