Abstract: Method and apparatus for producing pulp from moisture-containing lignocellulosic material, such as wood chips, which is ground in a grinding space defined between a pair of grinding discs which rotate relative to one another in an environment of pressurized steam generated during the grinding process, in a closed housing. The ground fiber or pulp discharged from the grinding housing is propelled by the accompanying steam into a cyclone, where the ground pulp is separated from the steam for further treatment, while the steam is recycled for further use in the pulping process. The pressure in the cyclone is so controlled that a pressure is maintained therein which is substantially equal to a pressure drop which is sufficient merely to maintain the propellant force of the steam to convey the ground pulp from the grinding housing to the cyclone while discharging the separated steam and recycling it for further use in the pulping process.

Abstract: An improved screw feeder such as may be used for conveying ligno-cellulosic materials such as wood chips, shavings, sawdust and the like to pulping apparatus includes a plurality of stopper bars positioned symmetrically about the inner periphery of the screw feeder throat inlet. The stopper bars are narrow, elongate wedge-shaped and extend from the greater diameter flare bore of the conical throat to the lesser diameter taper bore. The stopper bars prevent material from rotating with the screw rather than advancing longitudinally through the throat and thus decrease plugging and clogging problems so that a higher pulping capacity due to improved feed is obtained.

Abstract: A static discharger includes a vertical casing connected to a pressurized pulping digester for receiving a stream of fibrous material and having a valve isolated scrap collector positioned on its lower end. A discharge neck on which a blow valve is mounted extends from the casing above the scrap collector and is covered with a grid plate having self-cleaning openings. A pipe mounted tangentially on the casing introduces flooding liquid thereto while a similar pipe may be located on the scrap collector. A sealed casing cleanout opening may be provided. No moving parts are involved since discharger agitations result from the flooding media. Heavy foreign body impurities in the stream sink to the scrap collector where they are removed without process interruption. Buoyant objects remain suspended in the liquid. Blow valve plugging is eliminated. For higher fiber consistency, a grid plate wiping agitator may be advantageously installed in the casing.