Wet End Recovery
Water-rich margins of the formed paper web are systematically sheared away at the vacuum zone of the forming section to establish a uniform sheet width. This continuous removal process, known as couch roll trim, occurs before the delicate sheet transitions into the press section. The trimmed fiber is returned to the broke system.
Operational Tolerance
Inconsistent sheet edges can cause devastating paper breaks if they are permitted to enter the high-temperature press and dryer sections. Adjustable high-pressure water jets execute this delicate cutting action, ensuring a clean edge without disrupting the fragile wet web structure. Mill operators closely monitor the width of the couch roll trim to prevent fiber loss while maintaining the necessary lateral stability during subsequent high-speed transport.
The trimmed width usually spans between fifty and one hundred millimeters on each side. Any deviation in water jet pressure immediately threatens the runnability of the entire production line.
Fibre Recirculation
Pulp retrieved from the edge trimming undergoes immediate mechanical agitation to break up the partially consolidated web. Because this material has not been dried, the fibers retain their full bonding potential and do not require chemical treatment. The recovery loop must maintain a steady consistency to prevent density fluctuations when the reclaimed pulp is reintroduced to the primary stock preparation line.
This immediate reclamation prevents waste.
