Drive Power and Torque in Papermachine Dryers, 2002 Technology Summit Proceedings

G. L. Wedel & G. L. Timm

A basic parameter in the design of a paper machine dryer drive system, whether it has an open gear, enclosed gear, or felt drive, is the drive power requirement. Previous work on the drive power for paper machine dryers covered rotating syphons in plain shell dryers. Today, many paper machines operate with stationary syphons and dryer bars. This paper presents the power and torque required for driving dryers with stationary syphons and dryer bars. Torque, as well as power capacity, is an important aspect in designing and operating a modern dryer section drive. The power required to drive a dryer increases significantly as the amount of condensate in the dryer increases. The power is greatly reduced when the condensate passes into the rimming condition. Dryer bars significantly reduce the speed at which the condensate rims and decrease the power and the torque required to make this transition. These results are presented along with information on the observed behavior of the condensate inside the dryer under a wide range of operating conditions. This information will help in predicting the drive power and drive torque that is required in the commercial operation of paper machine dryers.