Why:
Efficient pulp washing successfully balances the highest quality of pulp, the removal of soluble impurities and dissolved solids to the evaporation plant. Optimal usage of washing water minimizes the load for the evaporation plant and simultaneously lowers the need for bleaching chemicals and effluents to the environment. Therefore, measuring the washer’s performance is vital for the kraft pulp mill. Brownstock washer performance can make a significant economic and environmental difference for a kraft pulp mill. However, despite these advantages, there is currently no standardized technique for evaluating washing efficiency. This project will focus on the evaluation of methods and models for assessing industrial washing efficiency, with particular attention to ”washing yield.”
Aim:
• To assess the washing performance industrially as ”washing yield” compared to ”ideal washing”.
• To investigate the washer’s performance under ideal, traditional, and conventional conditions.
• To review the methods for calculating washing efficiency, including dilution factor, displacement ratio, washing yield, Norden efficiency factor, and wash loss (measured in Na2SO4 kg/ADT).
• To analyze the quality of the wash liquor using analytical techniques.
Measurement methods:
The project will employ a range of analytical techniques, including Conductivity, Total Dissolved Solids (TDS), Total Solids (TS), Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), and Wash Loss measured as Na2SO4.
Washing efficiency will be assessed through the dilution factor, which gauges the volume of water used per ton of pulp, and washing loss, which quantifies the unremovable, washable components in the pulp that are carried over into the bleaching process. Various methods will be used to calculate washing efficiency, including the dilution factor, displacement ratio, washing yield, Norden efficiency factor, and wash loss (measured in Na2SO4 kg/ADT). The quality of the wash liquor will also be characterized. This Master’s thesis project
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.
Planned period:
Spring 2024
Contact details:
Eashwara Raju Snethilkumar, erse@kth.se
Olena Sevastyanova, olena@kth.se
Gunnar Henriksson, ghenrik@kth.se
Tomas Vikström, tomas.vikstrom@valmet.com
Maria Boman, maria.boman@sca.com
Daniel Solberg, daniel.solberg@sca.com
