PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® FROM THE PUBLISHERS OF PAPER TEC Volume 11, Number 2, 2025
Experimental investigation of pulp dewatering by high vacuum suction boxes MAHLOHONONO MAFELA 1 , TOBIAS LOUW 1 , JOHANN GÖRGENS 1 , GARRETH SAUNDERS 2 , MICHAEL GARCES DE GOIS 2 , JOHANNES P. KOTZE 2 , WIAN VAN DER WESTHUIZEN 3 & LUVUYO TYHODA 4 Reducing energy consumption by industrial processes has become imperative because of rising energy costs and efforts toward decarbonisation. The continuous manufacturing of paper is energy intensive due in part to the water removal process required to convert pulp slurries to valuable paper products. This necessitates the development of energy conservation techniques, while simultaneously ensuring the quality of the product. A pilotscale test unit was developed to quantify the effects of dwell time, vacuum pressure, and refining energy on the achievable pulp concentration or dryness level of three pulp types utilised in paper machines. Pulp dry matter was investigated as a means of gauging vacuum consumption and hence energy utilisation in paper machines, which could potentially reduce utility consumption of the overall drying process. A novel approach to simulate the pulsating high vacuum zone in the forming section of a paper machine was implemented, allowing the development of statistical correlations to explore vacuum dewatering conditions that may lead to energy efficiency. Bleached hardwood, mechanical/groundwood and recycled pulp were characterised to determine the effects of refining energy on fibre morphology and their drainage behaviour in pulp slurries. A dryness level of 21.8% at − 55 kPa gauge was achieved for bleached hardwood, whereas lower values of 19.8 and 18.3% were observed for recycled and mechanical pulps, respectively. This behaviour was attributed to the differences in drainability and morphology of the pulps due to their respective unique properties, further exaggerated by refining. Contact information: 1 Department of Chemical Engineering, University of Stellenbosch, Private Bag X1, Matieland, Stellenbosch 7602, South Africa. 2 TF Design (Pty) Ltd, Unit 1, Devon Valley Industrial Park, Devon Valley Road, Stellenbosch 7600, South Africa. 3 Mpact, Innovation Research and Development, The Vineyard Office Park cnr Adam Tas and Devon Valley Road, Stellenbosch 7600, South Africa. 4 Department of Forest and Wood Science, University of Stellenbosch, Private Bag X1, Stellenbosch 7602, South Africa. Cellulose (2025) 32:1835–1850 https://doi.org/10.1007/s10570-024-06344-3 Creative Commons Attribution 4.0 International License The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology International ® and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .
Article 2 – Papermaking Dewatering
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