Mathematical Model of an Off-Machine Paper Converter for Coat moisture control

摘要

In a paper converter machine, a non-contact drying process provides an effective means to remove moisture from the sensitive coating surface. This drying process plays a significant role in improving or degrading the coated paper in quality and appearance. It is conventional that the coated paper passes through a series of impinging air dryer hoods to follow a product specific moisture drying profile at every hood, so that the desired final moisture of the coated paper is attained. It is highly desirable that the temperature of the air, flowing at a constant velocity, at each hood is controlled so that the appropriate heat and mass transfers take place to attain the required moisture profile at every stage through proper control. These Control strategies can be effectively implemented if the dynamics of the process is completely understood. Simulation models of the process play an important role to understand such dynamics processes. This paper deals with simple simulated Mathematical Model that has been developed for a single coating station of an off-machine paper converter using simple heat and mass transfer laws. This model can be used for moisture control of coated paper. The model is validated with plant results obtained from an indigenously developed DCS based data acquisition system, which had been installed and commissioned in a Coat Paper Mill in Western India. The real time data of each roll stored in the data base are used in the simulations. The results are presented in this paper.