Process Optimization at a Newsprint Mill by Continuous Charge Measurements in Thick Stock, 2001 Papermakers Conference Proceedings

Dipl.Ing.Jari Nikkinen, Dipl.Ing. L.Bley--Over ten years of experience with on-line charge demand analysis has shown that measurements conducted in white water frequently fail to produce meaningful results. One reason, among others, is that white water contains different charge carriers, such as fines, fillers and colloidaly dissolved anionic material. In addition, charge carriers that are neutralized upstream from the white water basin escape detection at this particular sampling point. In view of the ongoing trend towards more complex retention aid systems and the increased use of recovered waste paper furnishes, charge measurements in white water are losing importance. Instead, on-line charge measurements should be performed at the source of anionic trash, for example coated broke, TMP or DIP. Another likely measuring point is after the addition of a chemical aid into the thick or thin consistency stock.

At the Utzenstorf newsprint mill in Switzerland, on-line measurements were performed to examine the impact varying pulp and chemical dosages have on the charge levels present in PM 2. This paper machine runs at an average speed of 1150 m/min, with a trim width of 4.20 meters and produces an average of 100.000 Tons per year. The on-line Particle Charge Titrator was used to detect short-term charge variations and disturbances, and to enable a quicker and more immediate reaction time. In addition, on-line charge measuring techniques were used to monitor and analyze numerous paper machine trials.