Counter-current rotary vacuum washers. This consists of a round cylinder under vacuum. The pulp adheres to cloth-covered drum and is washed with water. Foaming can be a problem here. Diffusion washing has a long contact period between cooked chips and moving wash liquor allowing diffusion to occur.
Pressure washers are alot like vacuum washers.
However, they are more efficient than as dewatering accomplished by pressure. Finally belt washers look alot like a fourdriner paper machine with vacuum underneath and a water wash on top. Based on a perforated barrier. In combination with a cylindrical perforated plate and a rotating hydrofoil, for the centrifugal-based screen, the radial force puts smaller stuff through screen. The hydrofoil breaks up the mat so the unit doesn't clog up.