| abstract |
A drying apparatus for drying material treated with liquid by heating and circulating a drying gas and for recovering vaporized liquid absorbed by a drying gas comprises at least one chamber unit which is essentially completely closed to the external atmosphere, a heating system in the chamber, a condensing system located in the chamber lowermost portion, means for guiding the material, in the form of a web, through the chamber through slot-like inlet and outlet openings such that the web is maintained free of contact at its wet surface, and a drying gas circulation system which divides the drying gas into several streams. The gas circulation system divides or splits the drying gas into a main-stream and a smaller side-stream, and repeatedly transports the main-stream past the web of material and transports the side-stream to and through the condensing system, and from the condensing system back to rejoin the main-stream, by circulation of the gas through elongated slot-like openings, formed by positioning and dimensioning of the web of material with regard to the side walls and the bottom of the chamber. A sealing system comprises at least one pair of rotatable rollers, positioned in proximity to each other, in or at a short distance from the opening made in an outer wall of a drying apparatus chamber, and positioned in such a way with regard to each other and to the web of material to pass through the drying apparatus, that the web runs between the rollers and partially over the circumference of each. Elastic sealing lips contact and press against the surfaces of the rollers to seal the space between the pair of rollers and the opening in the wall. A method of drying in the apparatus utilizes reduced oxygen content and maintenance of the dew point in the drying chamber at high levels. |