Torque correlation and control in mechanical pulping using adjustable speed drive

The objective of this research was to use torque as an effective control parameter for energy savings, fiber property improvements and smoother operations. Two computer-controlled ASDs from Siemens were installed in a Sunds Defibrator two-stage half-ton/day TMP/CTMP pilot plant with interstage pressurized cyclone at the Center of High Yield Pulp Science (CHYPS) at Georgia Institute of Technology. The torque values of the first and stage motor as well as other energy consumption parameters were monitored using the ASD. Based on the desired freeness level and energy requirement, a torque profile was established for each motors as calibration curves. Several different throughput levels were used in this research to determine the relationship between torque and fiber properties. Due to the limitation of the equipment at the time of the experiments, only first stage data are reported in the report. Several different consistency levels also produced variations.