Internal interconnections impact on control performance in a thermomechanical pulping process

Process integration may indeed be advantageous, particularly in a plant-wide economical sense, but there is also a potential risk that unnecessary difficulties are introduced when it comes to process control. This work identified several internal interconnections in a thermomechanical pulp refiner line as a result of an integration approach adopted during the process design. Firstly, a disturbance sensitivity analysis for the overall production process is carried out. Secondly, a simulation model is constructed and using real process data it is found to successfully reflect the complex dynamic behavior observed at the actual plant. The simulation model can provide indications on how the process performance can be improved by process design modifications. The results suggest that the presence of internal interconnections increases the demands on the control system and also set limits for its performance. If control aspects had been considered at the earliest stages of process development, the possibility to achieve satisfactory process performance could have been significantly improved.