Multi scale modeling of the delignification kinetics during kraft cooking

Purpose and goal

The aim is to achieve a more resource-efficient delignification route in the kraft cooking process. The goal is to contribute with a mathematical multiscale model for its sub-processes, which takes into account different chemical and physical phenomena on length scales from nanometers up to macroscopic scale.

Expected effects and result

An expected results is a multi-scale model that describes the complex delignification process. The model will be developed in several steps and describe both molecular and macroscopic phenomena. This is directly related to the common sulphate process in kraft cooking. The model is expected to contribute to a more resource-efficient pulp cooking process. The PhD student who will work on the project is expected to be a future contributor of knowledge and ideas of resource optimisation within the pulp industry.

Planned approach and implementation

As the delignification process contains several complex steps, we will focus on the smallest scale first (the fiber wall) and then proceed with modeling of the pore system in one piece of wood chip. In all parts, we will start from existing experimental data and apply molecular dynamic simulations in combination with continuum-based mass transport models. The doctoral student working on this project will gain a fundamental understanding of kraft cooking as well as good insight into the industrial process.