Optimización del sistema de hidrociclones para la reducción de pérdidas de fibra en la línea de rechazo en la producción de papel tissue

Abstract

This internship took place at Essity Colombia S.A., on Paper Machine 7 (MP7), dedicated to the production of tissue paper from recycled pulp. The project aimed to optimize the low-density centrifugal cleaner system due to significant losses of usable fiber in the reject line (DFR) and low efficiency in the removal of inorganic contaminants. Initially, a technical diagnosis of the system was carried out through physicochemical analysis of the pulp, evaluating parameters such as ash content, consistency, presence of black spots, and fiber classification in the reject streams. The results showed ash removal percentages below 7% and a considerable fraction of usable fiber being carried to the reject, representing significant economic losses in the process. Based on these results, an improvement strategy was applied using the twelve-step Kaizen methodology, implementing operational adjustments focused on controlling the system's hydraulic and rheological variables. This included increasing the dilution in stage 4 of the cleaners, optimizing the reject flow, and controlling parameters such as pressure drop (ΔP) and pressure differential (DP). These modifications favored the differential separation between cellulosic fibers and higher-density contaminants. Following the intervention, a significant reduction in total fiber loss was observed in the reject line, achieving an approximate savings of 36% in the monthly costs associated with rejects in white paper production. The results obtained demonstrate that the integrated control of operational variables and physicochemical parameters improves the selectivity of the centrifugal cleaning system, increases process performance, and contributes to the stability of pulp quality in tissue paper production.