Benefits of Combined Low Retention/High Temperature/High Speed (RTS) Conditions in Primary and Secondary Thermomechanical Refining Stages, 1999 International Mechanical Pulping Conference Proceedings
Marc Sabourin
Andritz Inc.
A process was evaluated combining low retention/high temperature/high speed (RTS) conditions in both the primary and secondary refining stages. Several refiner plate configurations were evaluated to maximize fiber development in both refining stages. The refiner plate configurations using a new alternating bar groove design (36SA001) or a coupled directional design on the rotor side (36604)/(36SA001) on stator side resulted in improved pulp properties compared to a conventional bi-directional plate pattern (D14B002). Pulps produced at elevated temperature and refiner disc speed in the second refining stage had 100-250 kWh/ODMT lower energy requirements compared to the control pulps. Pulps produced with both refining stages at low retention/high temperature/high speed conditions (RTS 2 ) demonstrated a reduction in specific energy of greater than 400 kWh/ODMT compared to TMP pulps produced at similar freeness and pulp quality; total energy requirements were less than 1400 kWh/ODMT at a freeness of 200 ml. Proper refiner plate selection was an important variable when optimizing the desired pulp quality at a given refiner speed and system pressure. Results from this study suggest significant opportunities are available to further improve refining efficiency with combined process and refiner plate development.