Measuring moisture after the press

Introduction The stability of the paper machine short circulation, forming and press section are tightly connected. A new online measurement, IQInsight, now provides true instantaneous MD and CD profiles from the press section. This unique measurement device provides new possibilities for stabilizing and optimizing paper machines. The accurate and continuous moisture profile just after the press section can be used to significantly improve paper quality. With an additional one percent dryness out of the press section the dryer section steam consumption can be reduced by three to four percent. On dryer limited machines, it can provide a capacity increase. Good moisture profile control also improves runnability. Significant savings can be achieved from reduced wet end and press breaks. At the dry end of the paper machine, at the reel, traditional scanners function very effectively, but the substantial delay through the long dryer section and the drying itself masks any useful data for wet end control. Quality problems cannot be responded to in time, so adjustments must be made based on obsolete information. Most of a paper machine is devoted to dewatering but papermakers have traditionally had very little visibility into this process. Moisture measurement after the press gives a valuable window into how this dewatering is taking place. A dry end moisture problem that can be seen already just after the press means no time is wasted searching for dryer section causes. If the moisture profile out of the press is good, attention can be immediately focused on the dryer section. Press moisture profiles can be used by papermakers to quantitatively assess press clothing condition and evaluate the performance of alternative fabric designs. The effects of operating adjustments such as nip loading, variable crown adjustments, suction box and forming section vacuums and press felt showers can be immediately seen without the uncertainty and delay introduced by an imperfect, real-world dryer section. Being closer to the source of a problem, means that an after press moisture measurement is an excellent tool for diagnosing problems whose source is upstream of the machine itself.