Improved uniformity of the fibers liberated in a kraft pulp digester

Purpose and goal:

Delignification effects in a kraft pulping digester may vary with respect to the chemical composition and physical properties of the produced fibers. Uneven delignification effects within the chip piece can be directly linked to local variations in mass transport and can affect the quality / homogeneity of the fibers. As chemical composition directly affects the properties of the fiber, this project focuses on elucidating how chemical composition in different parts of the treated piece of chips varies with time, temperature and chemical conditions depending on morphology and size.

Expected results and effects:

By generating knowledge on the underlying mechanisms behind heterogeneous delignification effects the project will open up for an improved quality control and development of more resource-efficient processes, which in turn will strengthen the competitiveness of the Swedish pulp mills. In a broader perspective, the project will contribute to further development towards efficient and diversified biorefinery concepts as well as to the competence supply to the industry and establishment of new education and research networks of great importance for the transition to a bioeconomy.

Approach and implementation:

Characterization of local delignification effects within a wood chip will be in focus: wood chips (delignified under varying conditions) will be sectioned and the individual sections will be thoroughly characterized with respect to structure and composition. Validating studies on industrially delignified wood chips will also be carried out. Information on these local variations in structure and composition will be supplemented by X-ray tomography measurements will generate corresponding 3D information on real-time morphological changes.