Process modelling in pulp and paper manufacture : Application studies with aspects of energy efficiency and product quality

Abstract: The manufacture of pulp and paper is an energy intensive process configured of several unit processes that shape a network of flows of wood chips, chemical pulp, mechanical pulp, board and other important components. Improved energy efficiency supports sustainability of the process and the products. With the purpose of monitoring and controlling, information from multiple process and quality variables is continuously collected in the process data system. The data may contain information about underlying patterns and variability, and using statistical and multivariate data analysis can create valuable insights into how reduced variations and predictions of certain properties can be accomplished.This thesis investigates the application of mathematical models for processes and products. These models can be used to increase the knowledge of the process characteristics and for quality predictions, to support process optimization and improved product quality.Based on process data from a board machine including the stock preparation process, an evaporation system and a CTMP plant, process models have been developed with the aims of quality predictions, improved energy efficiency and reduced process variability.