Mcdonnell Douglas Corporation

Dick Q Durant

Howard F McKinney

Frederick Coleman Wear

Nathan L Higginbotham

An apparatus for drying seeds and other granular products includes a drying vessel that is connected to a vacuum pump which evacuates air from its interiors. The drying vessel has an enclosing side wall and a tubular portion which is surrounded by the side wall, all such that an annular drying cavity is formed within the vessel. The tubular portion is made from a material that is transparent to microwave energy and houses waveguide-radiators, each of which is connected to a different microwave launcher that is located at the lower end of the transparent tubular portion. The launchers produce microwave energy that is directed into their respective waveguide-radiators which in turn allow the energy to escape through apertures in their side walls. This energy passes through the transparent tubular portion of the drying vessel and into the drying cavity of the vessel. Within the annular drying cavity, the vessel contains drying columns into which the granular product is directed. The columns are formed from a material that is transparent to the microwave energy and are offset angularly with respect to the waveguide-radiators, so the microwave energy emitted from the apertures for the most part reflects from the side wall of the vessel. This minimizes first pass energy impingement on the product and thereby provides a more uniform field for drying the product within the columns. The rate at which the granular product descends through the columns is controlled by vaned rotors. The moisture released from the product in the form of steam passes through a condenser where it condenses to water, and this serves to maintain the vacuum in the drying cavity.

Apparatus and process for drying granular products

A source of microwave energy is introduced into a pressure vessel in which a vacuum is drawn. Powdered materials to be dried are introduced and removed from the vessel by screw conveyors which are long enough so that in combination with the material, they prevent the loss of the vacuum in the vessel. The materials are transported through the vessel as the moisture is removed therefrom at essentially ambient temperatures. A water vapor condenser is also included within the pressure vessel to reduce the vacuum pumping requirements thereof.

Microwave heated vacuum dryer for powders

Seed is dried with no impairment of its germinating capabilities by subjecting the seed to microwave energy in an atmosphere of reduced pressure. The microwave energy elevates the temperature of the water within the seed to its boiling point, which is quite low because of the reduced pressure, and the water vapor which is released is condensed within the atmosphere of reduced pressure. An apparatus for practicing the process includes an upright pressure vessel, hoppers at each end of the pressure vessel, a perforated processing chute connecting the hoppers, and a control wheel at the lower end of the chute for controlling the speed at which the seed moves through the chute. It also includes a vertical wave guide surrounding the chute and external microwave power units which direct microwave energy into the wave guide and the chute within it. A condenser surrounds the wave guide within the pressure vessel.

Growing community of inventors

Manchester, MO, United States of America

Dick Q Durant