EV Pocket Ventilation™

results in even moisture profile and energy savings

PM drying section is a major steam consumer: 75 % of paper machine steam consumption is used in drying process. Energy waste, uneven sheet moisture profile and runnability problems are the result if cylinder pockets are not well ventilated.

Underpressure in the unventilated cylinder pocket creates dry air flows into the drying pocket causing high pocket humidity in the centre of the pocket and sheet fluttering. Poor pocket ventilation causes uneven final moisture profiles at the reel and over-drying at the both edges of the sheet. This means poor paper quality and more paper breaks. Decreased evaporation capacity and uneconomic steam consumption are also results of poor pocket ventilation.

EVpv Pocket Ventilation is installed in the cylinder pockets of dryer sections to blow dry supply air into the pockets. This decreases the pocket humidity level and allows moisture profile correction. In addition, the system decreases steam consumption and it also prevents over-drying and edge flutter.