Dr. Ramírez-Arias, Guillermo

Coater sections are examples of multi-span web transporting systems, with dynamic characteristics related to the sheet properties and control schemes. This paper first describes and analyzes a set of field records of a production 2-coater section paper machine. Then, extending the 1-coater section model developed in a related paper, a precise simulation model of a 2-coater section is implemented. This model is used to evaluate the beginning of the coating process and the effect on the section responses of different bandwidth settings in the tension and speed controllers. Results show agreement with the field records and demonstrate that the developed model is a powerful tool to analyze and understand the behavior of coater sections during both transient and steady-state conditions.

Real-time estimation of the modulus of elasticity (E) in paper machines would enable it to be controlled, improving final product quality and reducing the occurrence of sheet breaks. This paper develops a novel topology to estimate E on web machines based on an adaptive observer structure that combines model reference adaptive control with a closed-loop observer using field signals such as tension force, velocity/position, and torque. The evaluation of the proposed topology is performed on the dryer-calender span of the dry-end section of a lightweight coated paper machine. Results show a fast and accurate estimation of E, confirming the robustness of the adaptive observer structure.

Condensate accumulated inside dryer cylinders will produce an increased power demand and eventually the inability of the dryer drive to accelerate the section. In a previous paper, these authors presented an online estimation algorithm capable of detecting the presence of condensate during a section starting. In this paper, a complete set of tests is run over two experimental cylinders covering up to 40% of cylinder volumes, and the complete set of power curves are reported and analyzed. Specifically, the presence of a combined cascading-rimming region in the medium to high condensate loads is confirmed. This combined mode modifies the pattern followed by the maximum power in the low condensate region. Using these data, high-order and simplified correlations are proposed for the estimation of condensate in flooded dryer cylinders. These new correlations increase the capacity of the online estimation algorithm to give good estimations of the condensate load present inside the dryer cylinders up to 55 mm of rim thickness.