共查询到15条相似文献,搜索用时 78 毫秒
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木材高频真空干燥及其应用前景 总被引:3,自引:0,他引:3
一、国内外发展概况及特点木材高频真空干燥是七十年代初首先在前苏联、美国、日本等国研究发展起来的一项先进的干燥技术,八十年代初开始应用于生产。美国的一家动力公司和日本的制造厂商,已推出高频真空干燥机的系列化产品,在欧、美及包括中国台湾在内的很多国家和地区推广应用。高频真空干燥的最大特点是木材干燥极为迅速。由于采用高频介电加热和在连续真空条件下作业,木材可在很短的时间内获得充分的热量,并在较低的温度下迅速干燥。一些用常规窑干法需要干燥数天乃至数十天的木料,采用高频真空干燥,仅需数小时或数十小时即可,干燥周期可缩短17 相似文献
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木材干燥是在热力作用下以蒸发或沸腾的汽化方式排除木材水分的处理过程。木材干燥是保存木材的优良特性、增强材质、合理利用木材的重要措施之一。 目前国内外普遍应用的木材干燥设备是蒸汽干燥和除湿干燥设备,拥有量占整个干燥设备的80%以上,而过热蒸汽-真空干燥设备是近几年发展起来的一种新型木材干燥设备,用此种设备干燥的木材质量好,木材颜色变色小,是一种较为理想的木材干燥设备。1工艺理论基础 木材属于植物有机体,含有一定的水分。其作为原材料在加工利用时,水分的存在在大多数情况下是极为不利的,因为木材的物理力学… 相似文献
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刨切薄木(以下简称薄木)贴面质量和成本与薄木干燥有很大关系。薄木(常规)干燥容易产生碎裂、皱缩、不平整等缺陷,即使采用湿贴法也会产生二次加工中的贴面开裂、鼓泡等缺陷。而且湿薄木(含水率一般在100%以上)在存放和运输过程中很容易发霉、变色,从而降低薄木的利用率,影响薄木贴面质量和产品成本。为此本文介绍一种新 相似文献
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杉木人工林木材的高频真空干燥工艺 总被引:2,自引:0,他引:2
对人工林杉木25mm和50mm厚板材进行了系列高频真空干燥试验.结果表明:干燥后的板材变形小,表面平整,表芯层含水率差异较小.尽管试板的初始含水率差异较大,但根据高频真空干燥靠近正极板的木材比靠近负极板的干燥速度快的特点,试板的初始含水率由低至高在负极板至正极板之间进行顺序摆放码垛,干燥后的板材含水率可达到均匀一致. 相似文献
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A new method for monitoring moisture content during radio-frequency (RF)/vacuum drying was developed by measurement of temperature
and pressure in wood. Temperature and pressure inside the wood were measured simultaneously during RF/vacuum drying at the
same point. The relative humidity (RH) and moisture content (MC) below the fiber saturation point (FSP) were calculated based
on temperature and pressure, and the relationship between the temperature, RH, and equilibrium moisture content (EMC) at the
measurement point. When the moisture content was below the FSP, the calculated MC was slightly greater than the value given
by oven drying. The absolute error was within 0.8% near the open cross side, and was within 1.8% at another measurement point.
Thus, we concluded that it was practicable to monitor the moisture content below the FSP according to the temperature and
pressure inside the wood.
Part of this study was presented at the 15th Annual Meeting of the Chugoku Shikoku Branch of the Japan Wood Research Society,
Higashi-Hiroshima, Japan, September 2003 相似文献
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This study investigated the effect of a compressive load of 0.092 MPa on the history of the tangential strains in Japanese
larch (Larix leptolepis Gordon) log cross sections subjected to external compressive load during radio-frequency/vacuum drying. The external compressive
load of 0.092 MPa played a role in inducing cracking in the outer zone of the log cross section, combining with other tensile
strains. However, it also played a role in reducing the heart checks in the core of log cross section when exerted on the
cross section of log cross section. 相似文献
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This study was carried out to investigate the effects of steam explosion treatment on drying rates, moisture distribution, shrinking, and checking during radio-frequency/vacuum drying of Korean larch pillar combined with a longitudinal kerf. All the pillars except the nonkerf/control with high initial moisture content (MC) could be dried within 89 h from the green condition to about 15% MC. In pillars with high initial moistures or in the early stage of drying, the drying rates were sharply accelerated by steam explosion treatments. The final moisture gradients along the transverse direction were gentler for the steamexploded pillars and for pillars with a longitudinal kerf, respectively, than for the unexploded pillars and for pillars without a longitudinal kerf. The moisture gradients along the longitudinal direction on all the layers were gentler for the pillars with a longitudinal kerf than for those without the kerf. Formation of checking was significantly controlled in the pillars with a longitudinal kerf. All the steam-exploded pillars except the kerf/1-cycle, however, were more severely damaged by checks than the unexploded pillars. A prong test revealed an extremely low level of residual stress for all the dried pillars. 相似文献
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对从杨树心、边材提取的磨木木质素进行了元素分析和红外光谱(FTIR)质子和碳-13核磁共振波谱(^1H,^13C NMR)等化学特征研究。研究结果表明:杨树心、边材木质素的经验式分别为C9H7.16O2.38(OCH3)1.99和C9H8.61O2.73(OCH3)1.33。心材木质素甲氧基含量28.16%,比边材高8.73%。两种木质素均具有典型阔叶材的特征,化学结构类型基本一致,碳骨架结构基本相同,但化学官能团和键型的组成上存在差异。 相似文献