Theoretical analysis of LC-refining - pressure screening systems in TMP

Nord Pulp Paper Res J. 2019 Mar 26;34(1):46-58. doi: 10.1515/npprj-2018-0040. Epub 2019 Feb 1.

Abstract

LC refining of mechanical pulps has proven to save energy in the production of TMP pulps. However, the specific role of LC refining as part of a TMP system has not been thoroughly studied since it is difficult to conceive any particular system at industrial-scales and impractical at pilot-scales. In this study, pressure screening and LC refining models that describe fibre length distributions, together with correlations to predict refining power were used to model three basic refining systems. From the simulation results, the impact of important variables such as reject ratio, refiner gap and refining net-power was studied. Performance curves of length-weighed average fibre length were generated from simulation results and were used to assess each system behaviour and also to make comparisons between systems. Data from an industrial scale TMP mill sub-system was gathered and compared to simulation results showing relative errors between 0-18 % on the predicted variables.

Keywords: low consistency; mechanical pulp; pressure screening; refining systems; system modeling.

Grants and funding

This work was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) Collaborative Research and Development (CRD) grant CRDPJ 437223-12 and the support of the industrial partners AB Enzymes, Alberta Newsprint Company, Andritz, BC Hydro, Canfor, Catalyst Paper, FPInnovations, Holmen, Meadow Lake Pulp (Paper Excellence), Millar Western, NORPAC, West Fraser, Westcan Engineering and Winstone Pulp International who are thanked for their support.