The Effect of Dryer Fabric Tension on the Moisture Removal in Paper

The efficiency of the dryer sections is becoming increasingly important as energy prices soar. In an attempt to evaluate one of the possible variables which influence the efficiency of the dryer sections, this study of dryer fabric tension was made. Previous studies have shown that increased tension improves the heat transfer from the cylinder to the sheet by dissipating the insulating layer of air which separates the two. The tension necessary for this to occur was labeled the optimum tension. Tensions above the optimum gave no added benefits. To test this hypothesis, three sets of trials were made on the pilot plant machine at Western Michigan University. The first set was made by varying the tension of the dryer fabric in the first dryer section. The second was made by varying the tension in the second, and the third by varying the fabric tension in both of the sections. Percent moistures were calculated and used to compare the percent moistures removed at the different tension levels. It was shown that when then tension is increased from near zero up to the optimum, the percent of the incoming moisture removed increased by up to 6% for the pilot plant machine. The increases came nearly all from the first section while changes in the second dryer section showed very little effect. The study also showed that running at tensions above optimum decreases the percent moisture removed