| 摘要 |
ZONED CYLINDRICAL DRYER A dryer used to remove a flammable solvent or vapors from a traveling web of material supported in flotation by opposing air bars. The dryer consists of a large metallic cylinder through which the web of material moves longitudinally. Seals in the ends of the metallic cylinder at the point of entry and point of exit of the traveling web provide for a control system to maintain the desired environment under controlled pressure within the metallic cylinder. The web of material travels successively through one or more zones within the metallic cylinder. In each drying zone, the web of material is exposed to pressurized atmosphere at predetermined temperatures. The solvent is recovered from the pressurized atmosphere by rapid cooling, membrane separation, or absorption. Sensors within each zone of the dryer measure the oxygen content of the pressurized atmosphere. If the oxygen content exceeds a given threshold, pressurized nitrogen or other inert gas is added. Through the use of a carbon bed at the last zone, pressurized atmosphere from that zone is rendered sufficiently free of solvent to be exhausted to the air or to a nitrogen recovery unit, thereby maintaining the desired overall pressure within the metallic cylinder.
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