APPARATUS FOR PRESSURIZED SCREENING OF A FIBROUS MATERIAL LIQUID SUSPENSION

An apparatus, for pressurized screening of a fiber/liquid suspension to separate the fibrous fraction into an accepts portion and a rejects portion, has a housing having an inlet with a heavy and large material trap, an accepts outlet, a rejects outlet, and a dilution liquid inlet. A hollow cylindrical screen having an open top and bottom communicates with the fibrous suspension inlet chamber and the rejects outlet chamber. Accepts fibers in the suspension pass through apertures in the screen to the accepts chamber and are discharged through the accepts outlet. Rejects discharge through the rejects chamber. A rotor having at least four regions, a closed top, and a bottom mounted drive mechanism is coaxially mounted within the screen. Hydrodynamic pulses are induced in the suspension in the screening region by a pattern of bumps and/or depressions impressed upon the rotor surface. The fibrous suspension is maintained at a relatively constant consistency within the screening region by the pumping action of the rotor and by providing dilution liquid to counteract thickening of the suspension. A dynamic bar screening device directs stones and other large objects out of the fluid stream and into an annular trap and also deflocculates the suspension.