SE321896B - - Google Patents

Abstract

1,197,276. Centrifugal separators. ALFALAVAL A.B. 28 Feb., 1969 [29 Feb., 1968], No. 10958/69. Heading B2P. In a sludge centrifuge in which intermittent sludge discharge is effected by opening outlets 8 by a valve 9 in response to the opening, by an hydraulically actuated valve 13, of an outlet or outlets 15 for operating liquid, the valve 13 being normally subject to the action of springs 12 tending to close it, the rotor 1 of the centrifuge is provided with a chamber 18 so arranged and dimensioned relative to the valve 13 that liquid charged into the chamber can assist the spring force in closing the valve 13. After a sludge discharge through the openings 8 the valve 13 is pressed to its closed position by the springs 12. Sufficient operating liquid is supplied through a pipe 10 to fill the space 11 and hold the valve 9 closed. Liquid to be separated is introduced through a distributor 6 into the separating space 4. When sludge is to be discharged additional liquid is introduced through the pipe 10 so that it flows over an overflow outlet 21 and passes via a channel 25 into a space 16 where it presses the valve 13 downwardly against the action of the springs 12 so that the liquid contained in the chamber 11 and liquid supplied through the channel 25 flow downwardly into the chamber 18 through channels 27 in the valve 13 whereby the valve 9 uncovers the outlets 8 for sludge discharge. The chamber 18 has a sufficiently large volume to receive the whole quantity of liquid without the liquid level being displaced so far inwardly as to close the valve 13. The latter is closed by the springs 12 when the liquid in space 16 has been drained through outlets 17. This effects complete sludge discharge. If a partial discharge of sludge is desired, a limited quantity of liquid is supplied through a pipe 24 to form a liquid level in chamber 18 in advance. Thus liquid arriving from the space 11 will displace the liquid inwardly in the chamber 18 and in the gap 18a to assist the springs 18 so that the valve 13 is closed, earlier. The amount of sludge discharged is controlled by the amount of liquid supplied through the pipe 24. After closure of the valve 13 liquid is drained from the gap 18a and the chamber 18 through outlets 19. In a modification, Fig. 2 (not shown), in order to maintain in the chamber 18 a constant level of operating liquid supplied through the pipe 24, an overflow outlet (28) is provided in the wall of the chamber 18 above the level of the outlets 19, this outlet being constituted by the inner end of a pipe piece which is screwed in the wall of the chamber and projects inwardly therefrom. Alternatively, for partial discharge, the volume of the liquid space in the chamber 18 may be varied by means of annular bodies of solid material, e.g. metal, placed in the chamber so that their volume correspond to the pre-filling volume.