System for drying wet, porous webs

In a system for drying a wet, porous web with hot gases by flowing gas through the porous web:

• a stationary drum;
• a coaxial rotatable cylinder of larger diameter than the stationary drum mounted for rotational movement about the stationary drum, said rotatable cylinder having many large openings whereby a porous web on the external surface of the cylinder is dried by flowing gas through the web and the cylinder openings and into the cylinder;
• said stationary drum having a plurality of circumferentially-separated, longitudinally-extending gas baffles on its outside surface, said stationary drum also having a plurality of circumferentially-separated sets of inwardly-extending louvers attached to its inside surface, the gas baffles being positioned to direct gas in a radial direction inwardly through the louvers, the louvers being adapted to direct gas in an axial direction inside the drum;
• and first sealing members and circumferentially-separated second sealing members, each extending across the annular space between the stationary drum and the rotatable cylinder to divide said annular space into pressure zones of different pressure.