Why?
When considering potential alternatives to fossil-based products, pulp mills play an important role, as they can supply a wide range of renewable materials and chemicals. In order to ensure a sustainable growth of the pulp industry, it is essential to tackle challenges, such as increasing pulping efficiency and decreasing raw material consumption[1]. In this scenario, a good understanding of the delignification process is essential. The study of local changes inside wood chips during processing can provide valuable insights regarding how different parameters affect the delignification yield and uniformity. However, experiments conducted with hand-cut chips (model samples) often overlook some features of the technical chips[2] [3], which is why this project will focus on industrial chips, considering not only different process conditions, but also different wood species.
Purpose and aim
The purpose is to expand the understanding of wood chip impregnation during kraft pulping for new insights towards increased resource-efficiency. In this project it will be addressed by investigating the changes in composition within technical chips of different wood species subjected to impregnation with white liquor. This project will be part of BioInnovation’s Resource Smart Processes, as a complementary piece to the PhD project “Improved uniformity of the fibers liberated in the kraft pulp digester”. It will receive full support from SCA and the Resource Smart Processes network. Another important purpose is to build a strong network in which the master student will interact with members of the Resource-smart Processes research school and industry representatives to support the future competence provision.
Methodology
Initially, impregnation experiments will be carried out on technical chips of different wood species (birch, aspen and spruce) as well as model samples (hand-cut chips of 30 mm x 45 mm x 8 mm) in small autoclaves (1.5 L)[4]. After impregnation, the treated samples will be leached, cut into different sections and the composition of each section will be analyzed[5]. Selected samples will be frozen and assessed for sodium concentration profiles by SEM-EDX. For the second set of experiments, impregnated chips of spruce/pine will be sampled by the master student at SCA’s Östrand pulp mill (ImpBin™ line). The collected material will undergo the same analyses performed with the lab-scale samples.
Prerequisites
The applicants should preferably have a background in chemical engineering, wood chemistry and process technology with a collaborative approach. The project can be performed in pair.
Project start
January 2024 or according to agreement
Contact details:
Supervisor: Carolina Marion de Godoy (godoy@chalmers.se).
Examiner: Merima Hasani (merima.hasani@chalmers.se).
[1] PÄTÄRI S., TUPPURA A., TOPPINEN A., KORHONEN J. Global sustainability megaforces in shaping the future of the European pulp and paper industry towards a bioeconomy. Forest Policy and Economics. 66(). 38-46. 2016.
[2] BRÄNNVALL E. 2. Wood Handling. In: EK M.; GELLERSTEDT G. and HENRIKSSON G. Pulp and Paper Chemistry and Technology. Volume 2. 1st Ed. De Gruyter. 2009.
[3] FOELKEL C. O processo de impregnação dos cavacos de madeira de eucalipto pelo licor kraft de cozimento. In: Eucalyptus Online Book & Newsletter. 2009. Available at: <https://www.eucalyptus.com.br/disponiveis.html>.
[4] BOGREN J. Further insights into kraft cooking kinetics, Ph.D. thesis. Gothenburg, Chalmers University of Technology. 2008.
[5] WOJTASZ-MUCHA J., HASANI M. and THELIANDER H. Hydrothermal pretreatment of wood by mild steam explosion and hot water extraction. Bioresource Technology. 241(). 120-126. 2017
