Multiscreen pressure diffuser

Abstract

A pressure diffuser for paper pulp includes a vertical pressurizable liquid-tight vessel having a pulp inlet at the bottom and a pulp outlet at the top. One or more ring shaped screen elements providing first and second concentric screen surfaces, are vertically mounted within the vessel. A number of radially extending header arms mount the screen elements for movement in the vessel and in fluid communication with it. A first linear actuator effects reciprocation of the arms. A cylinder, open at both ends, is affixed to the arms and extends both above and below them, and a piston is disposed within the cylinder, below the arms. A second linear actuator is operatively connected to the piston to effect reciprocation of the piston in the cylinder. A guiding conduit surrounds the open end of the cylinder above the arms and guides reciprocation of the cylinder and transports liquid from the arms to an effluent outlet. A perforated jacket surrounding the guiding conduit, nozzles at the vessel wall, and the like introduce liquid into the vessel for treatment of the pulp. The ring shaped screen element is connected to the arms in a manner to allow the best liquid communication between them. In this way pulp can be effectively treated in a pressurized vessel while the screens for treating the pulp are periodically backflushed without causing a surge within the vessel.