CONTROL SYSTEM FOR AN INDUSTRIAL DRYER

摘要

CONTROL SYSTEM FOR AN INDUSTRIAL DRYER A control system for an industrial dryer used to remove a flammable solvent or vapors from a traveling web of material or the dryer. The dryer consists of a chamber which is preferably a large metallic cylinder through which the web of material moves longitudinally. Seals in the metallic cylinder at the points of entry and exit of the traveling web permit the 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. At each zone, the web of material is exposed to a pressurized atmosphere which may be at increasingly higher temperatures. The solvent is recovered from the pressurized atmosphere by rapid cooling, membrane separation or absorption. Sensors within each zone 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, the pressurized atmosphere from that zone is rendered sufficiently free of solvent to be exhausted to the air or a nitrogen recovery unit, thereby maintaining the desired overall pressure within the metallic cylinder.