Method for drying materials with microwave energy

Claim 1

The method of drying moisture-laden lumber which may be of varying moisture content comprising the steps of: moving a stream of long, relatively narrow, moisture laden lumber pieces which may be of varying widths through a plurality of microwave drying chambers in series, said drying chambers being spaced apart a distance sufficiently to allow dissipation of heat throughout the lumber piece as it moves in the space between driers; in each drying chamber directing a beam of microwave energy from a microwave source against a small portion of a side of each moving lumber piece so as to travel through the latter to the opposite side thereof, said beam applying drying energy to said each piece across the full width thereof, said piece of lumber being heated only by said microwave energy while in said chamber; controlling the temperature and humidity in the environment between successive driers through which the lumber pieces are moved; detecting the moisture content of each piece before or during the microwave application; and controlling the intensity of the directed microwave energy in accordance with the detected moisture content of said each piece of lumber against which the microwave energy is being directed, any lumber piece, after passing through a plurality of said microwave drying chambers, which has a sufficiently low detected moisture content, being removeable before being moved through the remaining drying chambers.

Claim 2

The method of drying moisture-laden lumber which may be of varying moisture content comprising the steps of: moving a stream of long, relatively narrow, moisture laden lumber pieces which may be of varying widths through a plurality of microwave drying chambers in series, said drying chambers being spaced apart a distance sufficiently to allow dissipation of heat throughout the lumber piece as it moves in the space between driers; in each drying chamber directing a beam of microwave energy from a microwave source against a small portion of a side of each moving lumber piece so as to travel through the latter to the opposite side thereof, said beam applying drying energy to said each piece across the full width thereof, said piece of lumber being heated only by said microwave energy while in said chamber; controlling the temperature and humidity in the environment between successive driers through which the lumber pieces are moved; detecting the moisture content of each piece before or during the microwave application; and controlling the intensity of the directed microwave energy in accordance with the detected moisture content of said each piece of lumber against which the microwave energy is being directed, any lumber piece, after passing through a plurality of said microwave drying chambers, which has a sufficiently low detected moisture content, being removeable before being moved through the remaining drying chambers.