Abstract: An apparatus is disclosed for discharging material through an elongate aperture in a substantially constant amount per unit length of said aperture. The apparatus comprises a screw discharging unit having an inlet end and including a screw housing with a casing wall and a screw rotatably mounted in the screw housing. The elongate aperture is provided in the casing wall and extends substantially parallel to the axis of rotation of said screw. The screw has a core and at least one screw blade extending around the core and having a predetermined pitch for feeding the material from said inlet end to the elongate aperture. The core and said casing wall define therebetween a space having an annular cross section area successively decreasing in the direction of feed of the screw.

Abstract: Apparatus for the displacement washing of cellulose fibers suspended in a liquid, as produced by cooking wood pulp in a digester vessel 1. As the fiber suspension settles to the bottom of the vessel it passes through a plurality of axially spaced washing zones 6, whereat water is forced through the suspension in a radial direction from central inlet conduits 16, 16a, 16b to peripheral outlet chambers 9, or vice versa. Such flow displaces the suspension or cooking liquid, and the washed fibers are withdrawn through a bottom outlet 5. The washing liquid is sequentially recirculated through the zones 6 for economy, and the buildup of fibers on the recirculating conduits 19a, 21a, 24a in the vessel is prevented by perforated water discharge pipes 26 disposed just above the conduits.