Heatable roll for the treatment of webs of material as well as method for their operation

摘要

A jacket with a thermally insulating layer partially surrounds, at a small spacing, a heatable roll which serves for the treatment of webs of material, in particular paper webs. Under production conditions the jacket reduces heat losses from the roll through convection and radiation to the environment. The jacket has a device which, with an interruption of production, ensures a forced convection at the heated roll for the cooling of the surface to a temperature level which is same or only insubstantially higher than in the production state. Several cooling nozzles are conceivable for the said apparatus which are secured to the jacket and direct a coolant onto the roll surface.