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US 4,229,886 AGranted
Microwave heated vacuum dryer for powders
AssigneeMcDonnell Douglas Corporation
InventorDick Q. Durant
Life of this patent
Estimating the term…
Abstract
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.
Claims23
A dryer for material including:
- a pressure vessel having an inlet end and an outlet end;
- means for reducing the pressure within said vessel;
- means for introducing microwave energy into said vessel;
- means for transporting the material in the vessel from the inlet end to the outlet and while the material is being subjected to microwave energy at the reduced pressure for at least a portion of the travel thereof;
- a first continuous conveyor for transporting the material into said inlet end of said vessel while the reduced pressure is maintained;
- and
- a second continuous conveyor for transporting the material from said outlet end of said vessel while the reduced pressure is maintained, said first continuous conveyor for transporting the material into said inlet end of said vessel including:
- an inlet hopper for the material;
- a cylindrical member extending from said hopper to said inlet end of said pressure vessel;
- and
- a worm screw positioned for rotation within said cylindrical member from said hopper to said inlet end of said pressure vessel which transports the material from said hopper to said inlet end of said pressure vessel, said worm screw having a predetermined outer diameter and said cylindrical member having an inner cylindrical surface of a diameter generally similar to said predetermined outer diameter of said worm screw,
- a predetermined length so that the material in said hopper and said cylindrical member acts to prevent the passage of air therethrough,
- an inlet end at said hopper and an outlet end in said vessel, said outlet end including a plurality of openings transverse to said means for transporting the material in the vessel from the inlet end to the outlet end thereof for distributing said material thereon.
10 more elements
A dryer for material including:
- a pressure vessel having an inlet end and an outlet end;
- means for reducing the pressure within said vessel;
- means for introducing microwave energy into said vessel;
- means for transporting the material in the vessel from the inlet end to the outlet end while the material is being subjected to microwave energy at the reduced pressure for at least a portion of the travel thereof;
- a first continuous conveyor for transporting the material into said inlet end of said vessel while the reduced pressure is maintained;
- and
- a second continuous conveyor for transporting the material from said outlet and of said vessel while the reduced pressure is maintained, said first continuous conveyor for transporting the material into said inlet end of said vessel including:
- an inlet hopper for the material;
- a cylindrical member extending from said hopper to said inlet end of said pressure vessel;
- and
- a worm screw positioned for rotation within said cylindrical member from said hopper to said inlet end of said pressure vessel which transports the material from said hopper to said inlet end of said pressure vessel, said worm screw having a predetermined outer diameter and said cylindrical member having an inner cylindrical surface of a diameter generally similar to said predetermined outer diameter of said worm screw, a predetermined length so that the material in said hopper and said cylindrical member acts to prevent the passage of air therethrough, an inlet end at said hopper and an outlet end in said vessel, said vessel including an inlet hopper into which said material is transported by said first continuous conveyor, said means for transporting the material in the vessel from the inlet end to the outlet end while the material is being subjected to microwave energy at the reduced pressure including, a conveyor belt having input and output ends, first and second opposite end rollers at said input and output ends of said conveyor belt, and a plurality of intermediate rollers between said first and second opposite end rollers positioned to shape the belt portion adjacent thereto into a trough for transporting the material.
8 more elements
A dryer for material including:
- a pressure vessel having an inlet end and an outlet end;
- means for reducing the pressure within said vessel;
- means for introducing microwave energy into said vessel;
- means for transporting the material in the vessel from the inlet end to the outlet and while the material is being subjected to microwave energy at the reduced pressure for at least a portion of the travel thereof;
- a first continuous conveyor for transporting the material into said inlet end of said vessel while the reduced pressure is maintained;
- and
- a second continuous conveyor for transporting the material from said outlet end of said vessel while the reduced pressure is maintained, said first continuous conveyor for transporting the material into said inlet end of said vessel including:
- an inlet hopper for the material;
- a cylindrical member extending from said hopper to said inlet end of said pressure vessel;
- and
- a worm screw positioned for rotation within said cylindrical member from said hopper to said inlet end of said pressure vessel which transports the material from said hopper to said inlet end of said pressure vessel, said worm screw having a predetermined outer diameter and said cylindrical member having an inner cylindrical surface of a diameter generally similar to said predetermined outer diameter of said worm screw, and a predetermined length so that the material in said hopper and said cylindrical member acts to prevent the passage of air therethrough, said vessel further including:
- an inlet hopper into which said material is transported by said first continuous conveyor, said means for transporting the material in the vessel from the inlet end to the outlet end while the material is being subjected to microwave energy at the reduced pressure further including a conveyor belt having input and output ends, first and second opposite end rollers at said input and output ends of said conveyor belt, and a plurality of intermediate rollers between said first and second opposite end rollers positioned to shape the belt portion adjacent thereto into a trough for transporting the material.
9 more elements
Dependencies are inferred from the claim text.