• Case Studies

Dirt detection in bleached pulp suspension


Uncooked components, bark and similar impurities appear as quality defects in paper, board and other wood fiber based materials. Their early detection and removal means better product quality and decreased quality costs.


A Pixact Stock Monitoring (PSM) system is installed on a by-pass line to acquire images of the flowing pulp suspension and to detect impurities. The statistics on dirt particle populations are reported to the factory in real time.


It has been observed that an increase in the dirt particle count at the pulp mill results in quality issues in the integrated paper machine 24-32 h later. This information can be used in the planning of production. Furthermore, new control strategies to minimize all types of dirt particles in the pulp suspension are being developed.

Process parameters

Process    Pulp production
Particle size distribution 40…500µm
Solids concentration 10 w-%
Temperature   20-70°C
Pressure Max. 8 Bar