Dr. Ramírez-Arias, Guillermo

Coater sections are challenging to tune during the commissioning of a paper machine. This paper presents a detailed mechanical-electrical model of a 1-coater section, which includes a linear, operating point model of the sheet in the different spans, all the drivetrain components, and the vector-controlled ac drives. The sheet model considers tail widening as well as the effect of coating and drying on the sheet elastic constant, activation of the torque current control, and the beginning of coating. The developed model allows for complete evaluation of the different transient events including paper slack due to load impacts. Results show that the best performance of the drives is obtained operating the spans with even sheet tensions, which reduces and/or eliminates the operation of the drives in regeneration or braking zones. © 1972-2012 IEEE.

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.

The presence of condensate inside the dryer cylinders of a paper machine produces a significant increase in the power required to accelerate the section, risking a drive overload and / or section shutdown. In previous works, the authors developed a robust estimation algorithm for the condensate power and a generalized correlation for the estimation of condensate loads in industrial dryer cylinders up to 55 [mm] of condensate rim. This paper presents and evaluates a rule-based expert system (ES) capable of detecting the presence and amount of condensate in up to three groups of cylinders with different condensate loads. The ES can give an early warning message to the operators, and determine the condensate load and number of cylinders within each group. Evaluation is done using a combined condensate load for a fictitious 1500-mm, 8 cylinder dryer section. Results show the capacity of the developed ES to give early warning, as well as a correct estimation of the condensate loads and numbers of cylinders involved.