Pressure screens are utilized in all pulp processing plants to remove undesirable particles and/or improve fiber quality characteristics.

Each pressure screen is equipped with a rotor, positioned concentrically within the basket (for outward-flow configuration). Rotors are designed with blades, foils or lobes to create localized pressure pulses with positive and negative components.

The positive portion of the pressure pulses pumps the stock through the basket, while the negative portion of the pressure pulses reverses the flow to clean the internal basket surface and prevent plugging. This action avoids the unwanted excessive accumulation of fibers, fiber bundles and other particles (example ? dirt) potentially impairing capacity.

The radial spacing between the rotor and basket normally ranges from 2 to 3 mm, hence the importance of accurate concentricity and basket roundness to obtain uniform cleaning across the entire basket surface. Simultaneously, the mechanical strength of the basket must be designed to withstand the high-frequency dynamic loading created by the rMotor.

The design of thePres_scren screen basket exerts a dominating influence on the efficiency of the pressure screen. The screen basket is the main component replaced when pulp quality or capacity drifts beyond acceptable limits. Pressure screen performance is largely defined by parameters including the basket slot size, the internal profile of the wire, and the passing velocity of the pulp slurry through the slots. Important operating variables include pulp type, feed consistency, freeness, fiber length distribution, wood species, etc. Additionally, the process configuration and the screen position within the system are important parameters to consider.