Before acquiring an online pulp freeness sensor, the operators responded to variations in incoming fiber quality by manually modifying the refining load based on lab measurements of pre- and post-refiner freeness taken every two hours. If the strength of the paper, measured once per reel (about every 45 minutes) was insufficient, the refining energy was increased. If that was not successful, other methods were tried, such as adding chemicals, using more pre-consumer double-lined kraft (DLK) or finally, downgrading it to a lower-strength product. The long delay between lab freeness measurements was masking fiber variation, making it impossible to respond to changes in a timely fashion.
In early 2018, FPC Papeles installed an online freeness measurement system
equipped with two sampling devices. This allowed them to measure freeness every 6 to 7 minutes at the output of the mill’s two refining circuits and more closely monitor the refining process. Following a two-month validation period, during which the online and lab readings were regularly compared and correlated, the operators placed their full trust in the new system and began to adjust the refiner load based on online freeness readings.
Eduardo Izquierdo, the technical director at FPC Papeles, said: “We are delighted with the online freeness measurement and the support we have received from ABB and MX-Chile, an ABB distributor who helped with installation and support. We look forward to continuing to work with them to achieve higher levels of process stability, savings and final product quality.”