Dewatering during paper manufacturing is a highly energy-intensive process. New research, published in BioResources, shows how the process can be made more efficient concerning energy consumption.

"In my research, I have looked at the manufacturing of grease-proof paper," says Björn Öman, an industrial doctoral student in chemical engineering. Grease-proof paper is extremely compact, enough to act as a barrier to fat, grease, and water. The more compact the paper, the more energy is used for dewatering.

During dewatering, the paper passes through several vacuum suction boxes, normally five to eight boxes. This creates a problem of rewetting, that is, the paper has time to absorb already removed water again, before being transported to the next step.

"Tests on a laboratory scale have been carried out at Karlstad University, where we have simulated a multi-slit vacuum suction box. Through increasingly higher vacuum levels without breaks between levels, we have achieved increased dryness and lower energy consumption. This new laboratory-scale dewatering strategy will hopefully reduce the energy requirement, resulting in higher dryness for full-scale grease-proof production. This will be especially important for grease-proof paper as it is much more difficult to dewater."

More information: Björn Öman et al, Improved vacuum dewatering of grease-proof paper utilizing a multi-slit vacuum suction box in laboratory scale, BioResources (2024). DOI: 10.15376/biores.19.3.4852-4870

Provided by Karlstad University