On-Line Pulp Quality Information

Production of pulp from wood is a significant industrial activity in Finland. In 2015, more than 7 million tonnes of pulp was produced in Finland. Important pulp quality parameters include brightness, dirt level, fibre length distribution, and the potential of forming strong and even fibre network. On-line measurements for the first three are available, but the fourth one related to bonding and fibre strength can only be measured in laboratory. In laboratory analyses, the pulp sample is first refined, then made into a paper sheet, dried, and finally measured. This takes time and incurs expenses, both factors limiting the number of analyses that can be carried out. Furthermore, laboratory analyses have been found to include a level of measurement noise that is not small enough in relation to the actual quality variation of pulp. All these factors together make the laboratory analyses less than ideal for pertinent quality control. A new on-line measure of pulp quality was developed and named Botnia FOX. Evident connections have been demonstrated between Botnia FOX and paper/board machine operation. Depending on the control strategy of each paper/board machine, e.g. whether pulp is refined to constant freeness or with constant specific energy consumption, the connections have been observed in one or more parameters like pulp consumption, paper/board machine runnability, energy consumption, and quality variables of the produced paper.