Impingement drying of multi-ply linerboard

This study is concerned with impingement drying of linerboard. In the tests the web has been liner, made of commercial furnishes on a production board machine or on a pilot board machine, and pressed in the press-section to a bout 45% dryness content. Impingement dr-ring with hot air, as presented in this paper, offers a new and effective method for board drying, especially at the beginning of the drier section where delamination is a severe probl em in multi-cylinder dryers. With the new impingement drying technique it i s possible to obtain drying rates higher than 100 kg/m(2)-h, which is much higher than produced by steam-heated cylinders. According to the experiment al results, thr delamination risk in pre-drying can be lowered, because of lower web temperature. The changes in board quality resulting from increase s in air temperature and impingement velocity were repeatable, though the c hanges in quality were slight.