| 摘要 |
<p>1,237,913. Drying wood. V. PAGNOZZI. 9 July, 1968 [20 July, 1967], No. 32771/68. Heading F4G. A process for-drying planks or laths of wood comprises the steps of (a) heating the wood by means of thermostatically controlled heating elements (e.g. electrically, hot water or steam heated plates) inserted between the planks or laths, or by means -of a heating fluid (e.g. air and/or superheated steam) skimming over the surface of the planks or laths, to bring the temperature of the internal parts of the planks or laths to at least 60% of the temperature of the heating elements or heating fluid; (b) subjecting the wood to a vacuum pressure which is below the saturated water vapour pressure corresponding to the temperature reached by the internal parts of the wood in step (a); and (c) continuing the vacuum treatment for at least as long as the temperature of the internal parts remains higher than the temperature which gives rise to a saturated water vapour pressure that is equal to the vacuum pressure. The heating fluid may be circulated through a closed circuit. The wood may be subjected to a plurality of alternate heating and vacuum treatment steps. The wood may be subjected to vacuum during the heating step. The temperature of the heating elements or heating fluid may be between 20‹ and 120‹ C. The surface of the wood may be cooled prior to the vacuum treatment. In the apparatus shown, wood planks 2 with electrically heated plates 3 therebetween are supported on trolley 4 in chamber 1 evacuable by pump 6. The temperature of the plates 3 is controlled by thermostats 10. The temperature of the internal parts of the planks is indicated by dial 11 associated with probe 12.</p> |
