IMPACT OF REFINING INTENSITY ON ENERGY REDUCTION IN COMMERCIAL REFINERS - EFFECT OF PRIMARY-STAGE CONSISTENCY

The specific refining energy required to obtain a given pulp quality c an be reduced by increasing refining intensity. The simplest approach is to reduce refining consistency. Mill trials in a two-stage TMP (the rmomechanical pulp) system showed a 7% reduction in total specific ene rgy when consistency in the primary refiner was reduced from 50% to 38 %. Target freeness in the discharge from the secondary refiner was 200 mL CSF. Similar results were obtained in a single-stage RMP (refiner mechanical pulp) system. Decreasing the consistency from 52% to 34% re duced the specific energy by approximately 15%. The results suggest th at the magnitude of the energy savings depends on the mill's normal co nsistency level and on the final discharge freeness. The potential ben efits are smaller for mills already operating at low consistencies, an d savings shrink as the target pulp freeness decreases.