Online Massbalance: Transparency is the basis for fiber loss reduction

The stock preparation process of a recycled paper line is complex, with equipment and process modules being influenced by many parameters. The bottleneck analysis and process optimization based on DCS information and trends analysis are not easy tasks and are time-consuming. In order to evaluate the production and/or losses, calculations must be done, and not every parameter is available for the calculation in the DCS. Most mills do not track the losses in real time, and loss figures are usually consolidated on a weekly or monthly basis. The classic way to estimate the losses is by comparing the weight of the recycled paper that was fed into the line with the paper manufactured on the paper machine. These global figures do not allow for the identification of the origin of the losses and can only be used to take delayed corrective measures.

In order to increase transparency of losses and deliver information in near real time, an online mass balance was developed to replace manual statistics. It combines data from the DCS with novel camera technology to determine losses where current standard measuring technologies fail. The results of the permanent mass flow and loss determination are summed up in an easy-to-understand Sankey Diagram. It enables a new way of improving the yield and facilitating the troubleshooting and optimization of the recycled fiber line.

Defined limits for production rates, losses and standard operating windows indicate deviations from the desired operation range in the moment they occur. The operators are informed immediately when the main process streams are leaving the normal operation window. To solve the issue and bring the process back on track, different shifts may use different method. The easy integration of countermeasures related to the main streams helps the papermakers keep standardized procedures to efficiently mitigate problems on the line.

This presentation will give insights into the details and challenges of the implementation of a real-time online mass balance followed by examples of how the new information can be used to optimize the fiber line process – resulting in an increased yield.