Abstract: A strainer with a screen at its outer periphery is rotatably supported on a casing. A hollow pipe with paddles on an outer periphery of the pipe is fitted in the strainer. The hollow pipe is rotated at a rotating velocity different from that of the strainer. Slurry introduced into the hollow pipe is discharged through slurry outlets on the hollow pipe into inside of the strainer. Then, the slurry is hydrated by the screen under centrifugal action and is moved by the paddles toward a slurry outlet.

Abstract: A casing has a pulp slurry inlet, a reject outlet and an accept stock outlet and accommodates a rotor. The rotor has a hollow cylinder with scraper blades at its outer periphery. A screen plate is disposed outside of the scraper blades to provide between them a passage facing to the screen plate. The hollow cylinder is formed with pulp slurry outlets. Rotation of the hollow cylinder causes the pulp slurry to be circulated outside and inside of the hollow cylinder, so that separation of the pulp slurry into accept stock and reject is repeatedly carried out by the screen plate.

Abstract: Separation and discharge of contaminants and defibration of undefibered waste paper can be effected in a single apparatus which has a generally cylindrical casing, a rotor concentrically arranged in the casing and a cylindrical main screen plate concentrically surrounding the rotor. Stock is separated by the main screen plate into that passing from inside through the main screen plate to outside and that not passing through it. The stock passing through the main screen plate is sent as accept stock to a next process. The stock not passing through the main screen plate is passed through a gap of a defibering section provided by defibration stator and rotor for defibration of undefibered waste paper and is further separated into the stock passing through an auxiliary screen plate and that not passing through it. The stock passing through the auxiliary screen plate is sent back through a circulation pathway in the rotor to inside of the main screen plate.

Abstract: Waste paper stock pulp slurry supplied through a stock inlet is separated at screening sections to a high quality stock rejected stock containing contaminants and undefibered waste paper. The high quality stock is sent to a next stage as accepted stock. The rejected stock is sent to a defibering section and is diluted after defibration, part of the rejected stock; being circulated to the screening sections, the remainder being discharged out of the system through a rejection outlet. The provision of screening and defibering sections in one and the same screen can satisfy contradictory requirements, i.e., to increase contaminant removing efficiency, to raise production yield and to attain space and cost savings.

Abstract: Waste paper stock pulp slurry supplied through a stock inlet is separated at screening sections to a high quality stock and a reject containing contaminants and undefibered waste paper. The high quality stock is sent to a next stage as accept. The reject is sent to a defibering section and is diluted after defibration, part of the reject being circulated to the screening sections, the remainder being discharged out of the system through a reject outlet. Provision of screening and defibering sections in one and the same screen can satisfy contradictory requirements, i.e., to increase contaminant removing efficiency, to raise production yield and to attain space- and cost-saving.

Abstract: A plurality of circular or polygonal dents are formed at land portions on the inlet side surface of a screen plate so that oversize materials enter into the dents and scattered away from the surface of the screen plate and therefore the probability of the screen openings being clogged with oversize materials is decreased.