Centrifugal washer for paper pulp with means to feed pulp as a thin sheet

A method and apparatus provide for the effective centrifugal washing and/or thickening of paper pulp, using a perforated cylinder (12) . A stock head box (14), located within the cylinder, applies a thin sheet of pulp (15) directly on the interior the cylinder, at a high rate (e.g. about 20 meters per second), at a first arcuate position (30). The cylinder is rotated at high speed (e.g. 100 rpm, to provide an acceleration on the order of about 10 gs), whereby centrifugal force causes liquid in the pulp to move radially outwardly through the openings in the screen cylinder. The pulp is withdrawn from the interior of the cylinder by a vacuum roll (22) or the like at a second arcuate position (31) less than 360 DEG from the first position. The withdrawn pulp is moved by a screw conveyor (24) or the like away from the cylinder in a dimension generally parallel to the axis of rotation (20), and the withdrawn liquid passes through channels in a drum (38) surrounding the perforated cylinder, and is engaged by an impeller (42), and flows to.a volute (26) for removal. Wash water may be added by a wash water head box (28) within the cylinder between the first and second arcuate positions (at 34). A drive roll (18) operatively engages the exterior of the cylinder for effecting rotation.