Improvements in Energy Efficiency of Vacuum Dewatering of Greaseproof Paper : Simulation of a Triple Vacuum Suction Box in Laboratory Scale

Abstract: Vacuum dewatering of paper is a heavily energy expensive process, even more so for greaseproof paper, which is one of the main products at Nordic Paper Seffle AB. Due to this being such an energy demanding process, improvements in the vacuum dewatering could save massive amounts of energy. The focus of this thesis is to investigate the effect of a triple vacuum suction box on the dewatering rate of greaseproof paper, using a tried and tested method of simulative triple vacuum suction box at a laboratory scale, with the difference of simulating a quadruple vacuum suction box, and how the grammage of the paper sheet affected this, using unbleached sulphate pulp consisting of soft wood with an addition of 20 % eucalyptus fibers. The results were as expected, showing the expected dryness curve behavior of diminishing returns of the dryness to dwell time ratio, and the method showed valid for improving the energy efficiency compared to a single vacuum suction box, in terms of both expended energy, and yielded dryness. The grammage had a significant effect on the dewatering, with the heavier paper at 100 gsm showing the need of higher dwell times and increased levels of vacuum pressure than the lighter paper at 50 gsm. An addition of a triple vacuum suction box could possibly replace multiple high vacuum suction boxes, leading to even greater savings. Further testing would be required for optimization of the vacuum levels and dwell times for the 100 gsm paper sheet, in order to reach the same dryness as the 50 gsm paper sheet.