The main goal in the screening process is to efficiently remove debris, including stickies, shives and other contaminants, from the stock. However, there are other factors to consider, such as targeted capacity, reject rate, energy efficiency, and runnability.

Since screening efficiency and runnability are contradictory objectives, this points to the inherent compromise in basket specification; setting the wire profile height low enough to ensure good efficiency (high accept quality with minimal contaminants), yet high enough to produce enough turbulence on the basket surface to maintain throughput and high runnability.

A further challenge is being able to operate with changing process conditions as we move from the feed to the reject zone of the screen basket. The ANDRITZ UTwist adaptable screening profile wire allows a mill to have it all.

Why Profile height matters

The design of the wire in a slotted screen basket has a major effect on both screening capacity and accept quality. The profile height is determined by adjusting the angle of the wires, and this affects the turbulence on the basket surface.

Changing the Profile height is the key

The profile height is determined by adjusting the angle of the screen bars to one another. Turbulence has a crucial effect on the behavior of the fiber suspension.

High Profile height

Raising the profile height increases turbulence on the basket surface, which is beneficial for stock fluidization and increased throughput. Higher turbulence also prevents too much fiber mat build-up on the basket surface, which could lead to plugging. However, if the turbulence is too strong, more contaminants will pass through the basket, thus reducing the accept quality.

Low Profile height

On the other hand, a low profile height improves screening efficiency, but lowers the throughput of the screen. It also contributes towards greater reject thickening, especially at the reject end of the screen, which again may jeopardize runnability. 

Geometry and adaptivity

Bar-Tec UTwist offers a wire with an adaptable profile that ensures the lowest possible profile height at any vertical position of the basket. The ability to adjust the profile height along the basket is unique, enabling low profiles close to the feeding zone to increase screening efficiency and then a higher profile in the subsequent zone to avoid critical thickening. The patented profile geometry allows tilting of the wire without having an impact on the slot width. This is not possible with any other profile wire.

Interested in bringing your screening efficiency to the next level?

Feel free to contact us directly and we’ll get you started.