Pressure relief drum washer and a method for manufacturing the drum washer

摘要

A drum washer (10) for washing pulp comprises a cylindrical drum (2), a stationary casing (11), a pressurizing arrangement (30) and a motor arrangement. The cylindrical drum comprises a penetration layer (7) at an outer surface allowing liquids to penetrate. The cylindrical drum has a plurality of compartments (4) for pulp arranged at a periphery. The cylindrical drum further comprises a drainage system (25) inside, in radial direction, of the penetration layer. The drainage system comprises intermediate channels (22), main channels (24) and drainage openings (26). The intermediate channels are situated directly inside the penetration layer and the outlet from the drainage system is connected to the main channels. The main channels together have a cross-section area that is at least two times larger than a sum of a respective cross-section area in axial direction of the intermediate channels. The motor arrangement is configured to rotate the cylindrical drum.