Apparatus for Drying Clothes or Other Solids Using Microwave Energy Under Reduced Pressure with Energy Recovery While Avoiding Arcing

Abstract

An apparatus for drying clothes or other solids that includes a rotating drum with microwave generator inside and rotating piping connections for energy recovery via drum jacket while sealing microwaves and pressure (vacuum), and selectable controls that provide conventional heating at a preset drum outlet moisture content, or not, depending upon the potential for metal in the load, to avoid arcing.

I claim: 
     
         1 . An apparatus for drying clothes or other solids including those containing some metal objects comprising:
 a. A metal drum designed for external pressure with a sealing access door and heat transfer jacket with internal baffles and means for connecting external piping to and from said jacket and an end centered double pipe axle providing conduits for fluid flow in and out of said drum and in and out of said jacket and providing for rotation of said drum.   b. Double pipe rotary sealing units connected to said drum axle providing for connection of said pipes to stationary piping.   c. A cylindrical metal canister located inside said drum and attached to one end of said drum and open to said drum inlet pipe and removable from said drum and providing a pressure vessel wherein high voltage microwave generator components are mounted and said canister is sealed from said drum cavity, including microwave antenna, except through one or more orifices of predetermined size avoiding microwave feedback and providing near atmospheric pressure inside said canister at design air flow rate through said canister and said drum while said drum pressure is less than one half of atmospheric pressure.   d. A set of rotary contacts providing connection of stationary wires conveying residential single phase alternating voltage to wires rotating with and inside said drum axle providing power to said high voltage microwave generator components inside said canister.   e. An electric motor and means for rotating said drum.   f. An electric motor and vacuum pump to provide a predetermined rate of air flow through said canister and said drum and to convey that air and its moisture content to discharge piping at a pressure higher than atmospheric pressure while maintaining a predetermined negative gauge pressure inside said drum cavity.   g. An electric resistance heater mounted inside said stationary inlet piping providing the design maximum inlet air temperature for said drum.   h. Electric manual and automatic controlled switches that allow an operator to select a drying process that will either both turn off the microwave generator at a predetermined outlet air moisture content and simultaneously turn on said resistance heater or not depending upon the nature of the load being dried, while allowing the drying process to terminate automatically at some predetermined final moisture content of said outlet air in either case or to be terminated by said operator or manually set timer switch.   
     
     
         2 . The apparatus of  claim 1  designed for drying various industrial solids including pharmaceuticals and fine chemicals wherein said drum cylindrical section transitions to a pipe flange and said flange is connected to a valve for loading and unloading and wherein said electric manual and automatic controls do not include provision for switching from microwave drying to hot air drying. 
     
     
         3 . A method of drying clothes or other solids comprising irradiation with microwaves under reduced pressure until a preset moisture level is achieved and drying energy switches to conventional electric resistance heating for those loads that may contain metal objects inside a rotating drum with a drum jacket providing energy recovery from air discharged from the drum. 
     
     
         4 . A method of drying pharmaceuticals or other fine chemicals or other industrial solids comprising irradiation with microwaves under reduced pressure inside a rotating drum with a drum jacket providing energy recovery from air discharged from the drum.