Feed forward control of mill chute level

Mossman #5 mill suffered from a highly variable feeding rate. Three intermediate carriers transported the bagasse from the #2 mill, and two mill overflow chutes over the decommissioned #3 and #4 mills before getting to the #5 mill. Although the #5 mill chute was relatively large, the chute level varied from 0% to 100% quite quickly, causing large variations in torque. The challenge of smoothing the bagasse flow into the mill was substantial, so efforts were made to improve mill control through a feed forward action. It was observed that the preceding intermediate carrier motor current provided advance notice of chute level changes. When the motor current increased, the chute level subsequently rose, and vice versa. This characteristic was implemented into the Mossman #5 mill control system so that the mill speed started to rise after the intermediate carrier motor current increased and before the chute level rose. This feed forward action provided a much more consistent chute level and more consistent mill torque.