Abstract: This invention relates to centrifugal separators but more particularly to a solid bowl centrifugal separator for separating a coarse solids fraction, a fine solids fraction and one or two liquid fractions having different specific gravities from feed comprising a liquid-solids mixture. The present invention relates to a solid bowl centrifugal separator which comprises an elongated bowl tapered at both ends and mounted for rotation about an axis. Coaxially mounted within the bowl is a helical screw conveyor having portions of opposite pitch to transport each of the two solids fractions towards their respective discharge ports located in the tapered ends of the bowl. Means are also provided for the discharge from the bowl of two liquid fractions of differing specific gravity. Each of the fractions is discharged into separate segments in the collector casing.

Abstract: A decanter centrifuge has a screw conveyor within an imperforate bowl defining a helical chamber. The conveyor is provided with a baffle extending in generally axial direction between the screw flights, thereby dividing the helical chamber within the bowl into a separating zone and a heavy phase discharging zone. The outer portion of the baffle defines with the bowl a restricted passageway which permits the underflow of separated heavy phase material from the separating zone to the heavy phase discharging zone. Pressurizing means, preferably means for maintaining the inner surface of the separated light phase layer inwardly of the weir surface of the heavy phase discharge port, helps advance the separated heavy phase material through the restricted passageway and toward the port through which heavy phase material is discharged.