MODELLING AND SIMULATION OF MULTI CYLINDER PAPER DRYING

Abstract

The aim of .a paper manufacturer is to produce paper to preset quality limits, preferably as close to the limits as possible. One of the most important quality variables used in the paper industry is the moisture content in the paper. The moisture content effects final properties such as strength, curl, and printability. In the drying section of the paper machine, paper is dried on large steam heated cylinders. This makes the drying section an energy de-vouring process. Large variations in the moisture content of the paper web also entail variations in the steam supply and control. Since the 1950s numerous drying models have been proposed. Along with the increase in computer speed and capabilities and an increased recognition of the complexities of the transport phenomena involved in drying, the models grew more complicated. In the present work simulation studies have been carried out for multicvlinder models, one is the basic modeling approach based on four phases of drying given by Nissan and Kaye. The physical model of cylinder is based on Karlsson [Karisson et al. 2002]. The next model built on heat and mass balances for steam. cylinder, and paper. The core of the model is based on work by [Wilhelmsson, 19931 and [Persson, 1998]. Nissan and kaye model for multicylinder drying has been simulated through C++ program. The results are validated with star paper mill Machine No.2 data and have been shown with the help of graph. The results show good accuracy with mill data. A Physical model of steam heated cylinder has been developed with the help of available models of drying and the equations of this model has been used to form ordinary differential equations and these odes are simulated with MATLAB ode45 solver and the simulation shows the variation in pressure, temperature and condensate volume. The simulation for cylinder temperature, pressure and condensate volume have been done and the work has been extended to the paper web mass and energy balance, which shows the behavior of moisture and paper temperature during drying.