TIMBER DRYING METHOD Russian patent published in 2014 - IPC F26B1/00 F26B7/00 B27K5/04 

FIELD: heating, drying.

SUBSTANCE: invention refers to accelerated drying of different kinds and cross sections of timber by means of equipment providing moisture transfer by action of relatively high temperatures, moisture content and alternating-sign pressure. A method for timber drying in a chamber isolated from atmosphere involves heating of a drying agent by means of heating devices connected in upper part of a shell as per a parallel scheme to main pipelines, devices for heating and circulation of high-temperature liquid heat carrier, reversible fans and flow dividers, which provide flow and distribution of the drying agent along a pile through diffuser channels, each of which is symmetrical to rows of gaskets of the pile, moisture levelling along the timber cross section by a moistening system with further exposure, removal of the drying agent from the chamber to a condensation device and control of a technological process by means of pressure, temperature and humidity control devices. A new feature of the proposed invention is that timber heat treatment is performed by hot recirculating water till average temperature of 35-45°C is achieved, which softens it, equalises humidity and quickly unfreezes it during winter season, by filling the chamber to upper pile level by means of an additionally introduced pipeline circuit provided with possibility of water return or transfer to the next chamber, and the heating process is continued by a steam-and-air drying agent till evaporation temperature is 100 to 120°C, thus maintaining the pressure of up to 1000 mm Hg; with that, the steam-and-air drying agent is removed from timber depending on timber type by constant or periodic vacuum pulses with further vacuum treatment by a vacuum pump till the pressure in the drying chamber is 100 to 150 mm Hg.

EFFECT: drying by evaporation at alternating-sign pressures of 1000 to 100 mm Hg using constant or periodic vacuum pulses considerably accelerates moisture evaporation speed and provides fault-free drying at inconsiderable change of bending, tensile and compression strength.

4 dwg