Patent ID: 6521094
Filing Date: 2003-02-18
Classification: D21C,D21D,D21F

Abstract:
A device for washing and dewatering a fibrous suspension, comprising:a first circular cylindrical filter drum arranged to rotate in a first direction, the first filter drum being hollow and permits an evacuation of a fluid in a radial inward direction into the first filter drum, the first filter drum having a first outer surface and a first evacuation chamber defined therein; a second circular cylindrical filter drum arranged to rotate in a second direction, the second direction being opposite the first direction, the second filter drum bearing against the first filter drum so that a nip is being created therebetween, the second filter drum having a second outer surface and a second evacuation chamber defined therein; first trough means for enclosing at least a portion of the first filter drum; second trough means for enclosing at least a portion of the second filter drum; means for washing fluid inlet for washing the fibrous suspension; a first pulp inflow member being in fluid communication with a first channel defined between the first outer surface and the first trough means for the introduction of pulp into the first channel to form a fibrous web therein, the first pulp inflow member being disposed above the nip; a second pulp inflow member being in fluid communication with a second channel defined between the second outer surface and the second trough means for the introduction of pulp into the second channel to form a fibrous web therein, the second pulp inflow member being disposed above the nip; the first trough means continuously enclosing the first filter drum over at least 230 degrees of a circumference of the first outer surface of the first filter drum, the fibrous web in the first and second channels being confined to flow in each first and second channel to form a first dewatering zone in the first channel and a second dewatering zone in the second channel before the fibrous web reaching the nip where the pulp is finally dewatered.