木材窑干时风扇转速对干燥速率,干燥质量与电力消耗的影响

木材窑干时风扇转速对干燥速率、干燥质量与电力消耗的影响１绪言减少能源消耗，增加干燥速率，是降低木材干燥成本的主要手段。其方法有修订窑干基准，改善干燥设备，更新干燥方法和改良叠材技术等。但除此之外，循环系统的风扇转速对能源消耗与干燥速率亦具有很大影响。...     

简易,实用的木材干燥窑

木材干燥是木材加工过程中的一道重要工序，直接影响着锯材制品及各种木制品的质量。而一般的干燥设备对于小型木材加工厂来说，价格较高，难以接受，这使它们产品的质量受到严重的影响，在市场上没有竟争力。而这些小型木材加工厂具有数量可观的木材加工剩余物，如能建一些利用加工剩余物作能源的简易、实用的木材干燥窑，则不但设备投资小、干燥成本低，而且也清除了工厂的垃圾，这对于小型木材加工厂来说，是一种简单易行、经济实用的木材于煤方法。本文介绍二种简易、实用的木材干燥窑。1地坑式端民机木材干操窑燃烧系统由地坑式炉灶、…     

发展木材干燥生产的两项重要任务

木材干燥不仅是保证木制品质量的关键,也是木材合理利用和节约木材的重要措施。建国以来,设计并建造了一大批木材干燥窑,培养了大量的木材干燥技术专业人员,有关教学、科研、设计工作也有很大发展,近几年来干燥设备制造业也已开始发展,目前已初步形成了一个以窑干为主的木材干燥生产体系。但是,由于我们原有的基础十分薄弱,并由于干燥在木材加工生产中是一项中间工序,干燥技术比较复杂,需要设备和投资,因此,     

木材干燥工艺计算机全自动控制系统

１前言随着我国木材深加工的不断发展，对干燥后木材的质量要求也在不断提高。如何合理地干燥处理木材，是决定成品材的重要因素，也是提高加工后木制产品质量的关键所在。目前，国内所使用的木材干燥设备，绝大部分是周期式气体强制循环干燥窑，其能源是采用过热蒸气通过...     

成材（板、方材）过热蒸汽-真空干燥技术

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…     

炉气间接干燥窑的试用与评价

在木材干燥方面我们先后购买了旋风式干燥窑和西北林学院研制的炉气间接加热可调湿型干燥窑。通过实际干燥运行和对质量进行比较，我们体会到，西林研制的干燥窑干燥的锯材质量好，干燥缺陷少，便于操作，投资也低。从木材干燥要求的质量和企业的经济效益出发，在同树种、...     

炉气间接加热木材干燥设备及干燥工艺研究

介绍了一种特别适用于中小型木材加工企业以木废料为能源的炉气间接加热木材干燥窑，实验证明，该干燥窑及其设备对被干材种的适应性较强，干燥后的板材质量好，干燥成本低，极具推广价值。     

炉气间接加热调湿型木材干燥窑

炉气间接加热调湿型木材干燥窑的主体结构和一般端风机型强制循环干燥窑相同，特点是：采用一种新型炉气换热装置和特殊的蒸汽发生结构，干燥热效率高，干燥介质调湿灵便，实践证明可以干燥不同规格的各种木材。由于干燥窑结构紧凑合理，造价较低，质量保证，特别适用于没有锅炉供热的中小型木材加工企业使用。     

我国木材干燥设备生产现状

我国木材干燥设备生产现状（１５００８６）全国林机情报网中心站邱曼萍木材干燥是木材深加工、精加工的重要工序和关键技术。先进的木材干燥设备是木材于燥不可缺少的．今年３月，北京“’９６国际木机展”国内厂家推出的木材干燥设备，基本上代表了我国木材干燥设备的生...     

木材干燥的自动控制

随着科技的发展，自动控制在木材干燥上用得越来越多。进口干燥设备几乎全部采用自动控制。国产干燥设备也在逐渐向自动控制过渡。由于木材干燥的特殊性，自动控制种类繁多，方式各异，令人有无所适从之感。本文旨在帮助使用者对木材干燥的自动控制有全面的、清晰的了解，以便更好地选择和使用适合自己情况的自动控制木材干燥设备。1自动控制的类型木材干燥过程实际上就是干燥介质作用于木材的过程。在这一过程中，木材的性质无法改变，因此也无法控制。人们能够控制的只是干燥介质的性质。所以，干燥过程的控制实际上只是对介质条件的控制…     

微波处理中木材内温度分布的数学模拟

从热传导的物理规律出发,建立微波加热过程中木材内部热传导模型,并通过理论模拟揭示不同微波加热方式对预处理中木材内部温度分布的影响规律。结果表明:微波处理过程中,木材内部的温度分布规律及均匀性与微波加热方式直接相关;当采用单向微波辐射的方式进行加热时,沿着微波入射方向,木材温度逐渐降低,木材内部温差较大,且温度分布均匀性较差;当使用双向微波辐射的方式进行加热时,木材内能形成内高外低的温度梯度,且温度分布均匀性较好。     

Improvements in dimensional stability and lightfastness of wood by butyrylation using microwave heating

Microwave heating was used as the heat source for butyrylation of wood with the aim of reducing the reaction time. The photostability and dimensional stability of butyrylated wood were also investigated in this study. Chemical changes of wood were confirmed by cross polarization/magic angle spin ¹³C-nuclear magnetic resonance and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) after butyrylation by microwave heating. Results from DRIFT with the Si-Carb sampling technique revealed that, using microwave heating, a higher degree of butyrylation of maple wood occurred in the middle of the specimen than on the outer surface. The increase in yellowness index of butyrylated wood treated with microwave heating was much less than that of untreated wood after the lightfastness test, indicating that photoyellowing of wood is effectively inhibited by butyrylation using microwave heating. The dimensional stability of wood was also improved after modification.     

干燥方式对地采暖用实木地板尺寸稳定性的影响

以烘干法和压干法两种干燥方式处理的8种地采暖用实木地板为试验材料,与烘干法作对比,探究压干法对地采暖用实木地板尺寸稳定性的影响;通过木材水分吸湿特性分析压干法提高地采暖用实木地板尺寸稳定性机理。结果表明:采用压干法能明显提高地采暖用实木地板尺寸稳定性,但对径向耐湿尺寸稳定性改善不大。相比烘干法,采用压干法干燥的番龙眼、印茄、朴木、栎木4个树种的地采暖用实木地板径向收缩率分别降低53.8%、60.0%、47.1%、44.4%,轴向收缩率分别降低70.9%、55.6%、37.0%、37.5%,轴向膨胀率分别降低43.2%、31.8%、23.4%、16.5%。这与木材半纤维素的降解、分子链结构活性的增强和纤维素结晶度增加有关。     

湿热蒸汽处理木质材料温度动态监测研究

作为一种替代溴甲烷熏蒸木材的技术,湿热蒸汽处理具有突出的环保性。试验通过智能换热站提供湿热蒸汽,设计了钢材框架悬挂耐高温气囊的试验装置,对原木、樟子松拼板、樟子松锯材和单板层积材进行湿热蒸汽处理,并对木材内部升温进行动态监测。利用温度记录仪收集了各温度监测点4 h内的温度实时数据,以及耐高温气囊内部的环境温度实时数据,对湿热蒸汽环境下木质材料不同位置的升温过程进行比较分析,结果表明:木质材料与湿热蒸汽的接触面积是影响其升温速率的关键因素;较大尺寸的木质材料升温速率更高;人造板材与天然木材升温速率基本相同。     

Effect of hydro-thermal treatment of green beech wood on its chemical and physco-mechanical properties

Summary Preliminary investigations were carried out aiming at the establishment of relationships between chemical, physical, and mechanical properties of beech wood under the influence of heating in water at 50°C and 100°C at pH values from 2.8 to 8.5 and with heating times up to 25 hours. It was found that heating of beech wood in water at 50°C does not produce remarkable changes in its properties. When green wood was heated at 100°C, insignificant changes in its density, shrinking, and -cellulose content were observed, whereas a considerable decrease in strength was found when tested in a wet state. It was further observed that on prolonged heating, the reactions of the wood and the solutions used as a heating medium under-went distinct changes, attaining an equivalent value approximating the final pH of the wood.     

Influence of histories on dynamic viscoelastic properties and dimensions of water-swollen wood

The influences of heating history, cooling method, and cooling set on microstructures and the mechanical properties of water-swollen wood were studied by measuring viscoelastic properties and dimensional changes while elevating temperatures between 20°C and 90°C. Both the viscoelastic properties and dimensional changes of waterswollen wood in the first heating process were quite different from those in the other heating processes. The results revealed that the molecular state of green wood around room temperature was stabilized and could not return to this state if drying or heating was carried out. Cooling methods greatly affected the viscoelastic properties, while they hardly affected dimensional changes when the temperature was elevated. Localized stress in the microstructures of water-swollen wood produced by quenching affected the mechanical properties in the heating process, while external stress less than the proportional limit caused by a cooling set had no effect. This revealed that much greater localized stress linked to the instability of waterswollen wood than the external stress in relation to the cooling set occurred. Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003     

微波和对流联合干燥的试验研究

试验以速生杨树和马尾松为干燥对象,研究了传统的对流干燥、微波干燥及微波和对流联合干燥三种不同供热方式的干燥动力学规律。结果表明:在整个干燥过程中,微波和对流联合干燥能使木材的内、外层含水率分布保持一致;与传统的对流干燥相比,联合干燥可以改善木材质量,提高干燥速度,降低干燥能耗。     

木材干燥预热过程的水分流和热流分析

本文将非平衡态热力学的水分流和热流线性耦合方程应用于多孔介质 (木材 )的干燥预热过程 ,从机理上分析了其水分流和热流的特性 ,同时运用在预热样品边界上积分的方法求解耦合流方程 ,针对木材干燥预热过程进行了具体计算 ,所得的有关结论与以往的实验结论相吻合。这一结果表明线性流耦合方程是研究多孔介质干燥过程中水分流和热流的特性及其相互作用规律的有效方法 ,既可揭示耦合过程中流的本质又可对其进行定量描述。因Soret效应预热过程中存在着进入木材内的水分热扩散流 ,预热结束后木材含水率将有所增加 ,而水分和热量的输运主要集中在预热开始的前 2h内。本文关于木材干燥预热的一些结果 ,可用于木材干燥预热的生产实际中     

Thermal-death kinetics of the bark beetle (Dendroctonus armandi; Coleoptera: Scolytidae)

Data on thermal-death kinetics of bark beetles are essential to develop phytosanitary heat treatments for pine wood and pine wood packaging materials. Using a heating block system, effects of different heating rates between 44 and 50°C at 2°C intervals on destruction of Dendroctonus armandi adult insect were examined. Heat resistance of the insects was found to increase at low heating rates (0.1 or 0.5°C/min). Therefore, the thermal-death kinetics of the beetles were determined at a high heating rate of 5.0°C/min which simulated the rapid dielectric heating of wood products. Results showed that the thermal death curve of D. armandi followed a zero-order reaction kinetic model, indicating the heat destruction rate of the beetle at different treatment temperatures to be independent of their population size. The required thermal holding times to result in destruction of the entire population were 40, 8, 4, and 2?min at 44°C, 46°C, 48°C, and 50°C, respectively. The evaluated thermal-death kinetic data are useful in developing effective beetle elimination quarantine protocols for the wood. A 50°C ?2?min heat treatment with a heating rate of ～5°C/min can be effectively used for disinfesting bark wood materials.     

Reversible volumetric changes of acetylated wood with after-treatments

Dimensional changes of acetylated wood were measured during wet–dry cycling and heating to clarify the reversible and irreversible effects of those after-treatments. During wet–dry cycling, the acetylated wood showed slight swelling in its completely dry condition, while its weight decreased slightly. Similar swelling was recognized when the acetylated wood was heated dry above 140°C. On the other hand, the anomalous effects of wet–dry cycling and heating disappeared after soaking in acetone. It was considered that the rearrangement of hydrophobic wood polymers during wet–dry cycling and heating induced the expansion of voids, whereas the wood polymers recovered their initial conformation after soaking in organic liquids. The wet volume of acetylated wood also exhibited reversible changes during wet–dry cycling. Just after the acetylation, the wood was highly swollen in acetic anhydride. The swollen volume of acetylated wood was reduced by leaching in water, and additional decrease in the wet volume resulted from the following drying or boiling. However, the reduced wet volume was recovered almost completely after acetone-soaking. These results suggested that the water molecules remaining in the hydrophobic region expanded the wet volume of acetylated wood, while such weakly bound water was easily removable by drying or boiling.