Outflow Pressure Screen for Pulp Screening
The outflow pressure screen is a modern and advanced pulp screening equipment internationally, suitable for screening wood pulp, various types of straw pulp, and waste pulp before bleaching, as well as for selecting pulp after bleaching and in the paper machine flow section.
The Workflow of the Screen Basket in a Pressure Screen
The outflow pressure screen is a continuous screening device for pulp under pressure in a completely enclosed state. The unfiltered pulp with pressure enters the inner side and outside of the screen basket, the good pulp passes through the screen plate. At the same time, the rotating rotor inside the screen basket can further improve the flow of pulp. The head of the rotor can generate a gentle pressure to push the pulp through the screen plate, while the tail of the blade generates negative pressure to clean the screen gap (hole). The rotor has an inclination angle with the longitudinal axis, which can push the pulp down and promote the coarse slag of the screen basket through the inlet pipe at the upper part of the machine in a tangential direction. With the help of the pressure difference between the inside to flow to the lower part of the screen and be discharged from the slag discharge pipe. The good pulp is drawn out from the good pulp tube in the middle of the machine through the screen plate. The pressure loss through the screen plate is related to the pulp variety, quality, concentration, impurity content, pulp flow rate, and screen plate opening rate, generally ranging from 0.01 to 0.03 MPa.
Design and Surface Detailing of Outflow Pressure Screen Basket
The screen basket is made of 304 or 316 stainless steel, with excellent varieties of hole and slot type. The wedge wire surface screen plate makes it easy for fibers to pass through the sieve holes (seams) and effectively separates impurities and fiber bundles from qualified fibers, thereby improving screening efficiency and obtaining high-quality pulp. The screen plate adopts drilling or milling and polishing treatment, with high smoothness and reinforced rings on the outside. The entire screen basket is fastened to the upper part of the cylinder with bolts, and the lower part is matched with the cylinder.
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Composition and Design of Outflow Pressure Screen Rotor
Composed of a cylindrical body and foil blades, the foil blades are fixed to the cylindrical body with screws and nuts, and the distance between the foil blades and the cylindrical body can be adjusted. The shape and position of the foil blades are designed to allow the pulp to move downwards along the screen plate, creating negative pressure at the tail of the blades to keep the sieve gap unobstructed and maintain the cleanliness of the screen basket during operation.
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