Patent EA-002725-B1 (EA)
Title: Method for drying saw timber and device for implementing said method
Inventor: DEDIEU BERNARD
IPC: F26B21/08
Filed: 1998-10-29
Abstract: 1. A method for drying saw timber, characterized in that the steps of: pressurizing a sealed chamber (1) at a predetermined pressure by injecting or generating saturated water vapor and maintaining said pressure for a predetermined time interval, while ensuring in the chamber a forced circulation of air and saturating water vapour, heating the wood core and the central zone of the wood pieces by emitting microwaves in frequencies ranging between 400 and 2450 MHz, evacuating the liquid exudates coming from the wood and collected by dripping in the chamber base (1). 2. The method according to claim 1, characterized in that the liquid exudates are evacuated continuously. 3. The method according to claim 1, characterized in that the liquid exudates are evacuated intermittently. 4. The method according to claim 1 or 3, characterized in that the step of the exudates evacuation is followed by a gradual pressure decrease to the atmospheric pressure with ceasing emitting microwaves. 5. The method according to any of claims 1 to 4, characterized in that the step of exudates evacuation includes the step of physical and chemical treatment of the exudates to be compatible with substances evacuated to the waste water system.  6. The method according to claim 1 or 3, characterized in that the step of the liquid exudate liquidation is followed by the step of their recuperation to the chamber for subsequent chemical retreatment. 7. The method according to claim 4, characterized in that the step of the pressure decrease is further followed by the step of dehumidification of ambient air surrounding saw timber in the chamber by supplying air flow coming from the chamber to a device for humidity absorption and for chamber air cooling. 8. The method according to any of claims 1 to 7, characterized in that the emissive power of micro waves emitted to timber decreases outwards from the center of a wood piece. 9. The method according to any of claims 1 to 8, characterized in that the saturated water vapor is pressurized between 2 to 15 bars. 10. The method according to claim 1 or 9, characterized in that the saturated water vapor is pressurized to at least 10 bars to obtain the moisture content of the saw timber exceeding 8%. 11. The method according to claim 1 or 9, characterized in that the saturated water vapor is used during at least a predetermined period of time pressurized between 10 to 15 bars at a temperature between 200 to 220 degree C to obtain naturally polymerized dry saw timber with a moisture content close to 0%. 12. The method according to any of claims 1 to 11, characterized in that the temperature inside the saw timber is maintained at a higher level than the temperature of the saturated water vapor due to micro waves emission. 13. A device for implementing the method according to claim 1, characterized in that comprises a sealed chamber (1) adapted to maintain pressure and communicates with a wave guide (40) through windows (14) made from quartz or from a material transparent to micro waves, said wave guide is connected via impedance adapters to a micro wave generator (44), the chamber is connected to a pipe line (12) intended for pressurized air circulation by injecting air from one side of the saw timber stack through gratings (13a) and feeding it pressurized from the other side the saw timber stack (3) through distributing gratings (13r), and a device for vapor production connected to the chamber, said windows (14) are arranged transversely relative to the saw timber stack (3). 14. The device according to claim 13, characterized in that comprises a pipe line (19) for air condensing connected parallel to a pipe line (12) for air recirculation adapted for switching over by valves (191, 192). 15. The device according to claim 13 or 14, characterized in that the chamber is provided with an orifice (18) in its base to evacuate dripping water by gravity which is controlled by a valve. 16. The device according to any of claims 13 to 15, characterized in that the chamber comprises: an automatic door (16) meeting the requirement of tightness against pressure and micro waves, means for transporting saw timber which are separated from means of transporting located from the other side of an automatic gate relative to the chamber. 17. The device according to any of claims 13 to 15, characterized in that comprises a second chamber with a pre-charging zone adapted for protection against emission leakage (escape), the chamber is accessible through flexible ports. 18. The device according to any of claims 13 to 17, characterized in that the micro wave generator deepened in the ground and connected to a drying chamber via the wave guide. 19. The device according to any of claims 13 to 17, characterized in that the chamber comprises a safety valve (11). 20. The device according to claim 19, characterized in that the valve (17) is adapted for opening periodically. 21. The device according to claim 19, characterized in that the valve (17) is opened permanently. 22. The device according to any of claims 15, 20, 21, characterized in that the orifice is connected to a device of physical and chemical treatment of exudates compatible with the norms to substances evacuated in used water. 23. A method of extraction of chemical components from wood, comprising the steps of: injecting or generating saturated water vapor into a sealed chamber at a predetermined pressure and maintaining said pressure during a predetermined time interval providing forced air circulation, heating wood by emitting micro waves, emissive power of which is determined according to wood zone upon which it effects, evacuating liquid exudates for subsequent extraction of chemical components from said exudates. 24. The device according to claim 23, characterized in that only one wood species of freshly-cut timber is treated by emitting micro waves in the medium of saturated water vapor. 25. The device according to claim 23 or 24, characterized in that said exudate is re-treated using physical and chemical methods to extract different chemical components utilisable in cosmetic, perfume, agricultural, food, pharmaceutical and chemical industries. 26. The device according to any of claims 23 to 25, characterized in that an exudate with insecticide properties is obtained by treating it with pine essence.