Abstract: A plenum drying hopper for granular material includes a housing enclosing a plenum chamber, an upper material inlet for introducing a flow of granular material into the plenum chamber, and a perforate diffuser cone, located in the lower portion of the plenum chamber, that directs the granular material from the plenum chamber into a material outlet. The perforations in the diffuser cone are large enough to permit ready passage of gas therethrough but small enough to preclude passage of all but the finest particles of the granular material. A gas inlet extends into the lower portion of the housing for introducing a drying gas (air) into the plenum chamber; a gas outlet discharges the gas from the upper part of the housing. Heaters are provided for heating the gas prior to its entry into the plenum chamber.

Abstract: A vacuum storage hopper for storing and dispensing granular materials, including a storage chamber having a lower inverted conical discharge section terminating in a discharge valve. At least one material inlet and a combination air inlet-outlet are connected to the upper part of the storage chamber. A source of air under vacuum and pressure is connected to the air inlet-outlet for exhausting air from the storage chamber to draw granular material thereinto, and for supplying air under pressure to the storage chamber to assist the discharge of granular material from the hopper. A flexible, resilient air-impervious membrane of inverted generally conical configuration is located in the discharge section of the hopper; the membrane has its upper edge secured to the upper edge of the discharge section of the hopper and hangs downwardly therefrom. A short strip of the membrane, no more than a minor fraction of its circumference, is secured to the storage chamber below its upper edge.