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US 4,321,757 AGranted
Drying apparatus and method
AssigneeOce-van der Grinten N.V.
InventorLaurens van der Blom
Life of this patent
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AssigneeOce-van der Grinten N.V.
InventorLaurens van der Blom
Estimating the term…
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.
In an apparatus for drying material which has been treated with a liquid and for recovering the liquid released from the material as vapor into a drying gas stream, including at least one chamber essentially closed to the external atmosphere, a heating system and a vapor condensing system contained within the chamber with the condensing system being located in the lowest part of the chamber, the improvement comprising guide means located in the chamber for guiding the material through slot-like openings in the chamber and through the chamber as a web the wet surface of which is maintained free from contact, the condensing system being located beneath the material web, a fan system means for causing forced circulation of the drying gas in the chamber, the guide means being located so that the material web is guided with the edges of the material web being spaced from inner side walls of the chamber so as to form elongated openings therebetween, the drying gas circulation means being positioned in the chamber with respect to the material web as to cause the system of drying gas and vapor contained therein to be divided into two streams one of which repeatedly circulates past the wet surface of the web as a main-stream and the other of which circulates as a side-stream through the elongated openings at the web edges to the condensing system located beneath the web for condensation of the vapor and from there to rejoin the main stream as drying gas.
In a method for drying material which has been treated with a liquid and for recovery of the liquid released from the material as vapor into a drying gas stream comprising guiding a web of the material through a chamber essentially closed to the external atmosphere, the chamber comprising a heating system and a vapor condensing system within the chamber, with the condensing system being located in the bottom of the chamber, the improvement therein comprising guiding the material through slot-like openings in the chamber and through the chamber above the condensing system as a web the wet surface of which is maintained free from contact, circulating drying gas in the chamber by means of a fan system, maintaining the edges of the material web spaced from inner side walls of the chamber so as to form elongated openings therebetween, dividing the drying gas into two streams, a main stream and a side stream, repeatedly circulating the drying gas and vapor contained therein past the wet surface of the web as the main-stream and through the elongated openings at the web edges, as the side-stream, to the condensing system located beneath the web, condensing the vapor and circulating the side-stream back to the main-stream as drying gas, supplying inert gas to the chamber to reduce the oxygen concentration therein and maintaining the dew point in the chamber at a high level.
Dependencies are inferred from the claim text.