Abstract: Impregnation of fiber material before digestion is accomplished utilizing a minimum amount of equipment. Liquid with entrained fiber material -- both fiber material sufficiently impregnated with liquid to be denser than the liquid and material insufficiently impregnated to be denser than the liquid -- is fed from a high-pressure transfer valve to an inlet at the top of a continuous digester. The digester has an outlet disposed vertically above the inlet, and liquid along with fiber material of lesser density than the liquid is withdrawn from the outlet. The withdrawn liquid and fiber material is recirculated back to the transfer valve through a conduit adapted to allow the passage of fiber material entrained in liquid therethrough. Each individual portion of fiber material is continuously circulated until it becomes sufficiently impregnated with liquid to descend into the digester and form a fiber column therein.

Abstract: An apparatus and method for impregnating fiber material with treatment liquid before treatment thereof in a high pressure vertical fiber material treatment vessel. Fiber material and treatment liquid under relatively low pressure flow in a first flow system, continuous withdrawal of liquid from the first system taking place. A second flow system of fiber material and treatment liquid, under relatively high pressure (the second flow system including an impregnation portion of the treatment vessel), is provided. Fiber material entrained in liquid in the first system is transferred to the second system, and the pressure thereof boosted, by a pocketed-rotor transfer device.

Abstract: In counter-current treatment of cellulosic fiber material it is known to have strainers for separation of liquid from the fiber material. In this invention strainers are omitted by introducing pretreated sinking fiber material through an inverted funnel into a liquid filled tank passing treatment liquid counter-currently to the fiber material and extract liquid from a liquid room above the surface of the fiber material and above the open lower end of said funnel. The tank may be operated at atmospheric or at higher pressures to suit the conditions.

Abstract: A method and apparatus for dewatering of cellulose pulp or other fiber suspensions. A suspension of relatively low solids concentration is passed into a sealed housing through an inlet, substantially filling the housing. The suspension is dewatered by bringing it into contact with perforated surfaces of a pair of drums or the like mounted for rotation about a vertical axis within the housing. Liquid from the suspension passes into an interior drum chamber, and at least a portion thereof is expelled from the housing through a liquid outlet. After passing a nip point between the two drums, the suspension has a higher solids concentration than the desired product suspension, and an amount of liquid is added thereto from the drum interior to dilute it to the final concentration.

Abstract: A method and apparatus for dewatering a suspension of comminuted fiber material and liquid. A suspension is passed in a given direction in a container of generally circular cross-section having a hydraulic piston mounted generally concentrically therein. There are no movable components extending between the piston and the walls of the container in which it is disposed, therefore leakage from the container is minimized. The piston has screens for separating liquid from the suspension associated therewith, and is movable in the same direction as the suspension flow during removal of some liquid from the suspension, and is movable in a direction opposite to the direction of fluid flow to facilitate cleaning of the screens and to return the piston to a position wherein it can move in the direction of flow again.

Abstract: A method for continuous treatment of fiber material in a digestor or the like that allows substantial segregation of the digestor treatment zones so as to prevent upflow of liquid from a bottom zone to an upper zone. An area of reduced cross-sectional area is provided between each treatment zone which increases the velocity of flow of fiber material and entrained liquid in that area, and substantially prevents upward movement of liquid therepast.

Abstract: A first portion of bleaching liquid is passed through cellulosic pulp in a bleaching zone at a first level with respect to the pulp feed direction and withdrawn through transversely spaced strainer means located at about said first level so that the passage of the first portion of bleaching liquid through the pulp is in a direction transverse to the feed direction of the pulp and a second portion of bleaching liquid is passed through said cellulosic pulp at a second level with respect to the pulp feed direction and withdrawn through transversely spaced strainer means located at about the second level so that the passage of the second portion of bleaching liquid through the pulp is in a direction transverse to the feed direction of the pulp and opposite from the transverse direction through said first level.

Abstract: A method for treating cooked fiber pulp as it comes from a continuous digester. The cooked pulp is bleached by intensively mixing the pulp with an oxygen containing gas and reacting the mixture while moving the mixed mass upwardly through a funnel shaped body within a pessurized reactor. The funnel shaped body is open at the upper end whereat the pulp mixture cascades over the side and flows downwardly into a ring chamber area between the reactor shell and funnel body, the pulp thereby forming a pressure barrier to any surplus gas within the reactor. The surplus unreacted gas is removed from the upper portion of the chamber for recycle with fresh pulp from the digestor and added gas. The treated pulp is removed from the lower portion of the ring chamber after passing downward therein.