| 摘要 |
<p>PCT No. PCT/DK87/00012 Sec. 371 Date Feb. 6, 1988 Sec. 102(e) Date Feb. 6, 1988 PCT Filed Feb. 6, 1987 PCT Pub. No. WO87/04779 PCT Pub. Date Aug. 13, 1987.In the vacuum drying of solid wood (2) and other wood-based products, the invention provides a method of achieving a better control of the drying process and a better heat economy than by the traditional methods of vacuum drying. This is achieved by completely evacuating the air from the space around the wood (2), and instead to fill the space (1) around the wood (2) with superheated water vapors (11). By maintaining a uniform pressure and temperature in all parts of the drying chamber (1) during the drying process, and controlling the temperature and the pressure of the superheated water vapors (11) in accordance with directives described in more detail, it is possible to control the dampness (MC) of the wood very precisely, and thereby to avoid damage to the wood (2) during drying. By at the same time providing the drying plant with a heat pump system (13) and condensing the water vapors (11) which have evaporated from the wood in a separate cooler condensation tank (15), it is possible with very low energy consumption to recover and re-use the main part of that thermal energy which is used in the drying. This is effected by using the wood (2) existing in the drying chamber (1) as a heat buffer, and controlling the temperature in the cooler condensation tank (15) and in the drying chamber (1) in accordance with more closely detailed directives.</p> |
