Patent ID: 7897014

Claim:
A washer for washing and dewatering cellulosic pulp material comprising a rotary drum having an end wall, a plurality of axial compartment walls disposed on said rotary drum defining a plurality of axial compartments therebetween, a stationary cylindrical casing enclosing said rotary drum thereby defining a ring-shaped space between said stationary cylindrical casing and said rotary drum, a plurality of axial seals dividing said ring-shaped space into a forming zone for forming said cellulosic pulp material, at least one washing zone for washing said cellulosic pulp material under an overpressure, and a discharge zone for discharging said washed cellulosic pulp material, a peripheral valve disposed at said end wall for collecting filtrate from said cellulosic pulp material, and a plurality of valve seals for separating said filtrate from each of said zones, at least one of said plurality of valve seals being displaced with respect to the corresponding plurality of axial seals along the direction of rotation of said rotary drum.