Rotary filter for concentrating fiber suspensions

Claim 1

In a rotary filter for concentrating fibre suspension and of the type comprising a plurality of annular disks each composed of sector-shaped filter boxes and mounted parallel to each other and in spaced relationship on a common shaft which is journalled in a vessel for containing the liquid to be filtered, means for rotating the shaft, each of said filter boxes having at least two opposite walls made of filter cloth, and an outlet opening for filtrate at the inner end of each filter box, said outlet opening communicating with a longitudinal outlet tube in the shaft, the improvement wherein: said shaft comprises a drum having a lattice-shaped cylindrical wall, said longitudinal outlet tubes being peripherally spaced about and partially forming said cylindrical wall, and further comprising a collecting hopper positioned within said drum, said hopper extending through an open end of said drum and being supported by a stationary support outside said drum, said hopper having an inlet opening facing upwardly and positioned within the uppermost portion of the interior of said drum, said inlet opening extending along all filter disks carried by said drum to receive concentrated pulp falling down through the lattice-shaped drum wall from those filter surfaces which are at their uppermost positions above the liquid level within said vessel during the rotation of said drum.