Model predictive control of fiber deformation in a batch pulp digester

Abstract

As the reduction of greenhouse gas emissions is an imperative issue due to global warming, the technologies of lightweight packaging have become an emerging field in the pulp and paper industry. Efficient use of pulp is one challenge while being comparable to conventional packaging materials. During Kraft cooking, both the chemical and physical changes on the wood fibers occur, causing strength properties changes in end-use papers. Accordingly, in this study, the fiber deformation in a pulp digester is elucidated by developing the multiscale model with the classical column buckling theory. Subsequently, in order to regulate the fiber deformation during pulping, a model predictive control system is designed by utilizing an approximate model taken from the high-fidelity model. In the end, the multiscale model-based control system accomplished suppressing fiber deformations compared to the conventional pulping manufacturing, which signifies the achievement of improved tensile strength on end-use paper.