Developments in vacuum drying and press drying of
Developments in vacuum drying and press drying of
Developments in vacuum drying and press drying of
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Center for<br />
Forest Products<br />
Pr<strong>of</strong>. Dr. Ressel<br />
Introduction<br />
Fundamentals<br />
Plant Facilities<br />
Innovations<br />
Process<br />
Technology<br />
Plant Examples<br />
Brunner<br />
IWT<br />
Mühlböck<br />
Kronseder<br />
Eberl<br />
Opel<br />
HeatWave<br />
Press Dry<strong>in</strong>g<br />
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Vacuum Dry<strong>in</strong>g - Process Technologies<br />
• Convective 1. Intermittent heat<strong>in</strong>g periods under normal <strong>press</strong>ure<br />
heat transfer Dry<strong>in</strong>g dur<strong>in</strong>g <strong>in</strong>termittent <strong>vacuum</strong> phases = Discont<strong>in</strong>uous<br />
Vacuum Dry<strong>in</strong>g Process<br />
Today the most 2. Cont<strong>in</strong>uous heat transfer <strong>in</strong> low <strong>press</strong>ure atmosphere<br />
common pro- (= Superheated Steam Steam/Vacuum / Vacuum; pAbs = 100…250<br />
cess technology mbar), sufficient gas density for convective heat transfer<br />
with high gas flow (vsteam ≥ 20 m/s) = Cont<strong>in</strong>uous<br />
Vacuum Dry<strong>in</strong>g Process<br />
• Conductive Direct contact to wood - heat<strong>in</strong>g plates (sticker reheat<br />
transfer placement); <strong>press</strong>ure level as low as possible / suitable<br />
= Cont<strong>in</strong>uous Vacuum Dry<strong>in</strong>g Process<br />
• Dielectric 1. Hot / cold electrodes <strong>in</strong>tegrated <strong>in</strong> <strong>vacuum</strong> vessel;<br />
field cont<strong>in</strong>uous heat<strong>in</strong>g, <strong>press</strong>ure level as low as possible<br />
/ suitable = Cont<strong>in</strong>uous Vacuum Dry<strong>in</strong>g Process<br />
2. Microwave generator (Magnetrons) <strong>in</strong>tegrated <strong>in</strong> <strong>vacuum</strong><br />
vessel; cont<strong>in</strong>uous heat<strong>in</strong>g, <strong>press</strong>ure level as low<br />
as possible / suitable = Cont<strong>in</strong>uous Vacuum Dry<strong>in</strong>g<br />
Process
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