What Is Pressure Screen Basket?

The pressure screen basket (also known as the foil screen rotor) is the core working component of a pressure screen, mainly used for fine screening, purification, and classification of pulp containing fibers or small particles. It is widely used in industries such as pulp and paper, food and beverage (such as juice and starch), and environmental protection (such as sludge dewatering), especially in the paper industry where it is crucial.

Main Function of Screen Basket

• Fine screening:

Separate qualified fibers and impurities from pulp (such as pulp suspension).

Impurities include: undissolved wood chips, coarse fiber bundles, plastic sheets, adhesives ("adhesives"), sand particles, metal shavings, rubber particles, and other substances that are not desirable to exist in the final product.

• Fiber grading:

Separate fibers based on their length or thickness, with longer and higher quality fibers passing through sieve seams/holes to form a good pulp; Short, fine fibers or impurities are intercepted and discharged as tailings. This is crucial for producing paper with specific quality requirements, such as thin sheets that require long fibers.

• Purification and concentration:

Remove impurities and improve the cleanliness of the pulp.

In specific applications such as sludge treatment, it can also have a certain concentration effect.

Working Principle of Screen Basket

The working principle of the pressure screen basket is based on "passing" and "blocking", and depends on the pressure difference inside and outside the screen basket and the shear force/turbulence generated by the rotor.

• Feeding pulp: the pulp is sent into the interior of the screening body under the pressure of the pump.

• Screening surface: The pulp flows through the surface of the screen basket. A sieve drum is a cylindrical or conical body with a large number of precise sieve slots or holes on its surface.

• Rotor function: A rotor with a rotor is installed inside or outside the screen basket (depending on the screen type). The rotor rotates at high speed tightly against the inner surface of the screen basket.

• Generate negative pressure pulse: When the rotor passes over the screen slot/hole, it will generate instantaneous negative pressure (suction force) behind it, which helps to suck in and pass the good pulp (qualified fibers and fine substances) near the screen slot/hole.

• Generating positive pressure pulses and turbulence: The rotor itself applies positive pressure to the pulp, while its rotation generates strong hydraulic shear forces and turbulence.

• Anti clogging: This turbulence and shear force can effectively flush the screen gaps/holes, preventing fibers and impurities from bridging or blocking at the screen gaps/holes, and keeping the screening channel unobstructed. This is the key to the efficient and stable operation of the pressure screen. Impurity transport: Turbulence can also push large particles of impurities trapped on the inner surface of the screen drum towards the tail end of the screen body for discharge.

• Separate pulp:

Reject: The pulp (mainly qualified fibers and fine substances) is discharged from the good pulp outlet on the outside (or inside, depending on the design) of the screen basket through the sieve seams/holes.

Tailings: Impurities and small amounts of fibers that cannot pass through the sieve gaps/holes gather on the inner (or outer) side of the screen basket and are continuously pushed towards the tailings outlet for discharge.

Importance of Screen Basket for Pressure Screen

The pressure screen basket is the "heart" of the pressure screen, which achieves efficient, continuous, and anti clogging fine screening, purification, and grading of fiber pulp or similar suspensions through precise screen slot/hole design, combined with the unique hydraulic pulses generated by the rotor (negative pressure suction and positive pressure turbulence/shear). Its core value lies in:

Protect downstream equipment: especially in papermaking, protect expensive paper machine clothing (press felt, forming fabric and dryer fabric).

Improving product quality: removing impurities, improving the cleanliness and performance of paper or food and beverage.

Optimize production process: achieve fiber grading to meet different product requirements.

Improving operational efficiency: Anti clogging design ensures continuous and stable production,

Choosing the appropriate seam width/aperture, wear-resistant material, and design form of the screen drum, and matching it with the correct rotor clearance and operating parameters, is the key to ensuring the optimal performance of the pressure screen.