Arrangement and rotor for screening of pulp

A screen assembly comprising:

• an outer casing;
• at least one stationary cylindrical screen drum arranged inside the outer casing;
• a rotating cylindrical rotor arranged inside the screen drum and having a cylindrical rotor outer surface, wherein turbulence-generating members are attached to the rotor outer surface and said rotor is perforated to provide flow passages from an inside surface of the rotor to the cylindrical rotor outer surface;
• a screening space defined between the cylindrical rotor surface and an inner surface of the screen drum, and
• at least one dilution liquid chamber restricted by the inside surface of the rotor wherein dilution liquid from said at least one dilution liquid chamber flows through the perforated cylindrical rotor surface directly into the screening space, wherein said discharge from the cylindrical rotor outer surface is at a distance of at least 20 millimeters (mm) from the inner surface of the screen drum.

A rotor for a screen assembly to screen pulp comprising:

• a cylindrical rotor having an outer surface on which is mounted turbulence-generating members, wherein the outer surface is circular in cross-section;
• at least one dilution liquid chamber inside and adjacent an interior surface of said rotor;
• the interior surface of the rotor forming one side of the at least one dilution liquid chamber, and
• said rotor having flow conduits between the interior and outer surfaces for dilution liquid flowing from the at least one dilution liquid chamber through the rotor to the outer surface, wherein said outer surface is positioned at a distance of at least 20 millimeters (mm) from the inner surface of a screen drum.

A screen assembly for pulp fibers comprising:

• an outer casing;
• at least one stationary screen drum arranged inside the outer casing;
• a rotating rotor arranged inside the screen drum and having a inside rotor surface and an outside rotor surface, wherein said rotor is porous between said inside rotor surface and said outside rotor surface, and said outside rotor surface is circular in cross-section;
• a screening space defined between the outside rotor surface and the screen drum, wherein a distance of at least 20 millimeters (mm) exists between the outer rotor surface and an inner surface of the screen drum, and;
• at least one dilution liquid chamber is arranged within the rotor and having the inside rotor surface as an outer chamber wall and an inlet for dilution liquid opposite to the chamber wall,
• wherein dilution liquid flows through said porous rotor and is discharged from the outside rotor surface directly into said screening space.