Paper Quality Software Sensors

Paper quality software sensors allows the implementation of paper quality, brightness optimizations, and blend optimizations to improve product quality and achieve economic benefits.


Similar to the TMP process, paper machines do not have continuous paper quality measurements for properties such as tear, tensile, TEA, porosity, etc. Paper quality is usually measured once per reel, or less, using automated paper testing systems such as Valmet Paper Lab. Therefore, only discrete measurements are available which are not suitable for continuous control by themselves. Valmet has developed a methodology and model structure for generating continuous paper quality signals (software sensors). The paper quality control and optimization modules use the software sensor signals. One of the main advantages is the ability to handle grade changes on the paper machine. Without Paper Quality Software Sensors, hours of off-spec paper or hours of lost opportunity for minimizing cost can occur.


The AQC approach to predicting paper quality allows the paper quality optimization applications to adapt to changes in furnish quality before these changes are seen on the machine. They act as feedforward predictions of paper quality maximizing the optimization potential. The Paper Quality Software Sensors also account for changing pulp inventories. A time-synchronization simulation is used to delay the pulp quality feeding based on the holdups in tanks and chests. This ensures the timing of the control and optimization applications is optimal.