US 4,026,037 A · Apparatus for steam drying

Abstract

A method and apparatus are disclosed for drying materials by contact with a drying gas consisting essentially of internally generated superheated drying steam above 212.degree. F., to vaporize the water in the material and remove it to produce the steam used for drying. A minor portion of steam is removed from the drying gas and discarded to maintain pressure equilibrium. The drying steam is produced within the drying chamber from water evaporated from the material being dryed and is either heated to form the superheated steam within the drying zone where it is in contact with the material or removed from the drying zone, heated to form superheated steam, and returned to the drying zone for contact with the material during drying. A wood veneer dryer employing the invention is described as well as an apparatus for drying particulate material. The drying zones provided with the veneer dryer have at least along the major portions of their lengths a negative internal pressure which is below that of the ambient external atmosphere outside the dryer to prevent pollutants from leaking out of the dryer and ambient air is prevented from entering the dryer into such drying zones.

Claims15

Dependent claims

A drying apparatus for removing water absorbed in a material comprising:

container means for containing said material and including means for moving said material through inlet and outlet ends of said container means during drying;
heating means for producing a heating fluid within said container means from water evaporated from said material, said heating fluid consisting of at least a major portion of superheated steam;
contacting means for contacting said material with said steam within said container means to heat said material and vaporize said water absorbed therein, whereby said water is removed from said material;
means for preventing the entry of ambient air into said container means through said open ends;
means for producing a negative internal pressure within the container means along at least the major portion of its length, said negative pressure being below the ambient pressure of the atmosphere surrounding said container means;
and
means for removing a minor portion of said steam from said container means.

4 more elements

Wood veneer dryer apparatus comprising in combination:

a first open ended veneer sheet drying chamber having first gas inlet means at one end thereof for introducing superheated steam into said chamber, having first veneer sheet inlet means at one end thereof for introducing veneer sheets into said chamber and means for heating the veneer sheets to evaporate water therefrom to produce steam within said chamber which is used to form said superheated steam, having first gas outlet means at the other end thereof for withdrawing superheated steam, having first veneer sheet outlet means at said other end for withdrawing veneer sheets therefrom, and having first veneer sheet conveying means therein for conveying veneer sheets through said first chamber during drying from said one end to said other end;
first heating means for heating superheated steam;
first gas conduit means communicating between said first gas outlet means and said first heating means for conveying superheated steam from said first drying chamber to said first heating means;
first gas motive means for moving superheated steam;
second gas conduit means communicating between said first heating means and said first gas motive means for conveying superheated steam from said first heating means to said first motive means;
third gas conduit means communicating between said first motive means and said first gas inlet means for conveying superheated steam from said first motive means to said first gas inlet means;
first gas removal means connected operatively to the first veneer inlet means, for removing a minor portion of superheated steam from said veneer dryer apparatus;
means for producing a negative internal pressure within the first chamber along at least a major portion of its length which is below the ambient pressure of the atmosphere surrounding said first chamber;
and
first means for preventing ambient atmospheric air from entering said first veneer drying chamber.

7 more elements

Dependencies are inferred from the claim text.

Apparatus for steam drying

Life of this patent

Apparatus for steam drying

Life of this patent

Abstract

Claims15