Patent ID: 8211273

Claim:
Apparatus for washing and dewatering cellulose pulp comprising a first rotatable press roll for use in conjunction with a second rotatable press roll forming a pinch therebetween for dewatering said cellulose pulp, said first rotatable press roll including a first perforated outer surface for dewatering said cellulose pulp, a first inlet disposed adjacent to said first rotatable press roll for supplying said cellulose pulp to said first perforated outer surface whereby the distance from said first inlet to said pinch comprises at least about 225° of the circumference of said first rotatable press roll, a first stationary guide member circumferentially enclosing said first rotatable press roll at least from said first inlet to said pinch and forming a substantially closed vat thereby forming a first pulp passage having a predetermined radial dimension between said first perforated outer surface of said first rotatable press roll and said first stationary guide surface, whereby said cellulose pulp is transported through said first pulp passage as said first rotatable press roll rotates towards said pinch, and at least one washing zone for adding a washing liquid into said pulp passage, said predetermined radial dimension being nonconverging over substantially the entire distance from said first inlet to said pinch, and said first stationary guide surface being substantially free of any perforations in the area of said pinch to thereby maintain the pressure in said area of said pinch.