| 摘要 |
Disclosed is a drying process which comprises primary drying in which many pieces of wood (logs with bark) in a drying chamber equipped with an exhaust system for maintaining a chamber pressure at a normal pressure or in a state close thereto, are heated up with only live steam fed into the drying chamber to heat a chamber interior from a normal temperature up to 90 to 100.degree.C, thereby heating the whole inner part ranging from a surface layer to a central layer of the wood; secondary drying that the chamber interior is heated quickly up to a temperature of 100 to 200.degree.C by the use of a heater, thereby boiling moisture in the wood for the purpose of high-temperature treatment up to a fiber saturation point in order to obtain a target percentage of moisture content; and finally, tertiary dying that the dry-bulb temperature and the wet-bulb temperature in the drying chamber are changed according to the dried condition of the wood to thereby treat the wood at low temperatures and moisture down to the target percentage of moisture content under the temperature conditions. According to this process, it is possible to form drying conditions in the drying chamber under which drying speeds (a rate of decrease in the percentage of moisture content) on the surface layer side and the central layer side of the wood can be equalized or brought as close to each other as possible, thereby enabling to dry logs without a crack.
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