Abstract: A centrifugal cleaner is constructed so that its efficiency is less sensitive to consistency changes of the feed slurry, and so that it can operate at a higher consistency than conventional cleaners, yet optimizes separation efficiency. This is accomplished by disposing a turbulence generator in the tangential inlet to the cleaner, the turbulence generator comprising an abrupt cross-sectional area reduction (e.g. a cross-sectional area of about 0.1-0.3 times as large as the cross-sectional area of the inlet) so as to break up fiber flocs and prevent reformation of the flocs. Existing centrifugal cleaners can easily be retrofit by the method of the invention to achieve the invention's advantages by inserting a turbulence generator into the inlet of an existing centrifugal cleaner. The tangential inlet leads to a hollow main body which includes a vortex finder located in the body top.

Abstract: A replaceable screen structure for a stock screen where stock slurry for making paper is passed through a screen with the rejects going to a reject outlet and the accepts passing through openings in the screen to an accepts outlet, with the screen having projections and a rotor inducing a pulsating induced flow along the profile surface, with projections on the surface having an inclined ramp of less than about 45.degree. and a 90.degree. downstream wall and accepts flow openings between the projections positioned closer to the upstream projection than the downstream projection.

Abstract: A pressurized dynamic pulp washer in which stock is driven along a stationary wash wire and pulses are generated in the stock to urge liquid through openings in the wash wire. Wash liquid is introduced countercurrent to the flow of stock, and localized mixing and reslurrying occurs.