Sequential Modeling of Paper Drying Process to Reduce Thermal Energy Use, Part 2: Simulation Results

Abstract

Paper drying is one of the unit operations that consumes the most amount of thermal energy in a papermaking machine. In this paper, a theoretical model for paper drying process was developed using the sequential modeling method based on the conservation laws of mass and energy. Aimed at simulating thermal energy flow, the overall framework of the drying model was constructed according to the specific drying process of a newsprint machine. It was composed of eight basic modules based on their different functions in the paper drying process, i.e., cylinder group module, steam separation module, surface condensation module, fan module, heat recovery module, air heating module, paper sheet module, and hood module. The results showed that it could be used to simulate the material and energy flow of each module, as well as the whole drying process in a more comprehensive manner with integrated thermal energy use and drying performance information. In addition, the effects of operating parameters, such as supply air temperature and exhaust air humidity, on thermal energy use in the newsprint drying process were also simulated. This work also demonstrates that the sequential modeling method is instructive to reduce thermal energy use for the industrial paper drying process.