Numerical model of water removal and air penetration during vacuum dewatering

Figures & data

Table 1. List of published experimental data used for fitting the model for moisture ratio.

Publication	Pulp type	Machine	Vacuum levels
Neun^[^17^]	Kraft pulp	Pilot paper machine	10, 21, 41 kPa
Nilsson^[^23^]	Softwood Kraft pulp, beaten	Laboratory suction box	20, 40, 60 kPa
Sjöstrand et al.^[^24^]	Softwood Kraft pulp, beaten	Laboratory suction box	10, 40 kPa
Sjöstrand et al.^[^25^]	Kraft pulp, two kinds of microfibrillated cellulose (MFC1 and MFC2), Dialcohol cellulose (DAC)	Laboratory suction box	40 kPa

Table 2. Values for all the fitting parameters.

Fitting parameter values
k1	5.8299
k2	−0.2659
AMR	3.0012e-11
nMR	0.6077
AAIR	3.5740e-10
nAIR	1.0001
AAIR (updated model)	6.5409e-12
nAIR (updated model)	1.9574
α	1.4134

Figure 1. The fit of the model for moisture ratio and the corresponding experimental data is shown. A linear fit with R² value and 95% prediction interval is also shown, the slope of the linear fit is 1.01.

Figure 2. Model predictions for moisture ratio are shown together with corresponding experimental values (*) from.^[17,23–25]

Figure 3. The fit of the model for air volume and the corresponding experimental data is shown. A linear fit with R² value and 95% prediction interval is also shown, the slope of the linear fit is 0.97.

Figure 4. Model predictions for moisture ratio are shown together with corresponding experimental values (*) from Nilsson.^[23]

Figure 5. The fit of the updated model for air volume and the corresponding experimental data is shown. A linear fit with R² value and 95% prediction interval is also shown, the slope of the linear fit is 0.96.

Figure 6. Updated model predictions for moisture ratio are shown together with corresponding experimental values (*) from Nilsson.^[23]

Neun, J. A. Performance of High Vacuum Dewatering Elements in the Forming Section. Tappi J. 1994, 77, 133–138.

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Nilsson, L. Air Flow and Compression Work in Vacuum Dewatering of Paper. Dry. Technol. 2014, 32, 39–46. DOI: 10.1080/07373937.2013.809732.

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Sjöstrand, B.; Barbier, C.; Nilsson, L. Influence on Sheet Dewatering by Structural Differences in Forming Fabrics. PaperCon. 2016, 2, 767–776.

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Sjöstrand, B.; Barbier, C.; Ullsten, H.; Nilsson, L. Dewatering of Softwood Kraft Pulp with Additives of Microfibrillated Cellulose and Dialcohol Cellulose. BioRes 2019, 14, 6370–6383.

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