Patent GB-919095-A (GB)
Title: Sludge centrifuge
IPC: B04B1/18
Filed: 1961-04-20
Abstract: 919,095. Centrifugal separators. SEPARATOR A.B. April 20, 1961 [April 20, 1960], No. 14292/61. Class 23. In a centrifuge having sludge openings 4 in the rotor body wall controlled by a slide valve 5 movable to close and open the openings 4 by respectively supplying and discharging operating liquid to and from a chamber 13 between the valve and the rotor body 1, the chamber 13 has a valve-controlled outlet passage whose inlet is spaced radially inwards from the chamber periphery so that operating liquid is retained in the outer peripheral part of the chamber when the outlet passage is open and the centrifuge is rotating. In the embodiment shown in Fig. 1, the chamber 13 is divided into upper and lower spaces 24 and 25 by a disc 26. During separation, drain holes 21 from the chamber 13 are closed by a spring-urged ring 18 and the valve 5 is closed by the centrifugal pressure of operating liquid supplied to the chamber 13 via channel 10, chamber 11 and channel 12 and retained therein at a level determined by an overflow outlet 14. When it is desired to discharge sludge the supply of liquid being separated and fed through the distributer 8 is interrupted and the supply of operating liquid increased to raise the liquid level from outlet 14 to a further outlet 15 so that liquid flows via a chamber 14a and a channel 16 to a space 17 above the ring 18 at a sufficient rate, despite leakage through drain holes 22, to fill the space 17 to the level of drain holes 23 with liquid, the centrifugal pressure of which opens the ring 18 against springs 19. Liquid in chamber 13 and space 25 then escapes through holes 21 and when the pressure on the valve 5 due to the sludge and liquid in the separation chamber 9 exceeds that in the space 24 the valve is opened to the extent allowed by spacers 26a on the disc 26. When a predetermined amount of sludge has been discharged the pressure on the valve 5 due to the liquid in the space 24 exceeds that in the chamber 9 and the valve is closed without loss of liquid in the chamber 9. The ring 18 is then returned to its shut position by either reducing or stopping the supply of operating liquid to the channel 10; in the latter event the supply is restored to its original rate when the ring 18 has closed. In a modification, Fig. 2 (not shown), which permits sludge discharge without interrupting the supply of liquid being separated, the operating liquid is directed to the spacer 24 by a conical disc secured to the bottom of the rotor body. In a further modification, Fig. 3, operating liquid is supplied to the chamber 13 via channel 12, chamber 11 and a stationary disc 32 either through a line 28 or through a line 29a and, during separation, valve 30 is closed and valve 31 opened, the level of the liquid in chamber 11 then being controlled by the opening 33 and the pressure below valve 5 maintaining it closed. To discharge sludge, valve 31 is closed and valve 30 opened so that liquid in chamber 11 passes through overflow 15, channel 14a and channel 16 to open ring 18. Liquid in chamber 13 then escapes through drain holes 21 and 35 to the level of holes 21 and the valve 5 is opened. When the sludge has been discharged the valve 5 is restored to its closed position by closing the valve 30 and opening valve 31. In another modification, Fig. 4 (not shown), drain holes 21 are provided at various radii and some of the holes may be plugged as desired to suit operating conditions.