| 摘要 |
Disclosed is a method of drying timbers loaded in a drying chamber, which comprises the steps of heating the drying chamber by a heating system up to a temperature of 80 to 100° C., subjecting the timbers to vacuum blowing by connecting the inside of the drying chamber with a vacuum chamber (receiver) evacuated by a rotary pump until the inside pressure of the drying chamber drops to 1 to 10 mmHg, disconnecting the inside of the drying chamber from the vacuum chamber, connecting the drying chamber with the atmosphere. When the inside of the drying chamber is connected with the vacuum chamber, the moisture content of the timbers is sharply reduced, so that their temperature sharply drops. Thereafter, when it is disconnected from the vacuum chamber, and connected with the atmosphere, the inside temperature of the drying chamber is again increased. Meanwhile, the heating system is worked during the whole process. The above steps constitute one cycle that is sequentially repeated until the moisture content of the timbers drops to a desired level. Preferably, the connection between the drying chamber with the vacuum chamber is made in 0.1 to 0.5 seconds. Pressure release is made in the vacuum for 0.5 to 5.0 seconds until reaching equilibrium moisture. The blow-down in the vacuum is carried out by a heat carrier with a temperature of 80 to 150° C. until reaching the volume average material temperature of 80 to 90° C. with the subsequent pressure release in the drying chamber lower than the equilibrium, thus providing high-speed vacuum blowing.
|
