Patent ID: 6234415
Filing Date: 2001-05-22
Classification: D21B

Abstract:
A pulper comprising a rotor (5) mounted in a tub (2) adjacent to a perforated screening plate (4) having holes (4a), wherein the rotor (5) includes helical vanes; (5a) whose diameter decreases towards the outer end of the rotor, characterised by one or more radially and outwardly pressure-generating and subpressure-generating elements (10) joined to the rotor (5) in the region of its end that lies proximal to the screening plate (4), wherein said one or more elements function to subject the pulp to an alternating working action as the rotor rotates, so as to counteract clogging of the holes (4a) in the screening plate (4), wherein each of said one or more elements (10) has a leading surface (10b), seen in the direction of rotation, that presses the pulp down towards and against the screening plate (4) and therewith force the pulp slurry through the screening holes (4a), and a trailing narrowing part that has a generally reversed wing-profile shape, seen in the direction of rotation, such as to generate on the trailing side of said element or elements a subpressure that sucks the pulp in the opposite direction and therewith contributes towards cleaning the holes (4a) in the screening plate.