| 摘要 |
A paper machine drying section and method for operating the same are provided for reliably maintaining a web in engagement with a drying fabric at locations where the fabric is situated between the web and drying cylinders. Those drying cylinders which are directly contacted by the drying fabric, so that the web is separated therefrom by the drying fabric, are formed with recessed outer surfaces having voids across which the fabric extends. The pressure in these voids is maintained at a magnitude less than the pressure at the outer surface of the web where it travels around those cylinders from which it is separated by the fabric, so that in this way the web is urged by the pressure differential toward the fabric so as to be incapable of becoming detached therefrom. For this purpose either a vacuum system provides in the voids referred to above a pressure less than atmospheric pressure, or at the outer surface of the web there is provided by a suitable pressure chamber a pressure greater than atmospheric pressure, or both of these expedients may be used simultaneously, so that in this way a reliable maintenance of the web in engagement with the drying fabric is achieved where the web is separated from the drying cylinders by the fabric. |
