A Study on Preservation Treatment of Waterlogged Wood by Supercritical Drying

超临界干燥对浸水木材防腐处理的研究

基本信息

批准号：
05835018
负责人：
KAWAGOE Mikio
金额：
$ 1.02万
依托单位：
Nara National College of technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

In the present study, application of supercritical drying to preservation of waterlogged wood and PEG impregnation method were investigated from the view poit of chemical engineering.PEG impregnation method : We have already analyzed the impregnation with PEG based on the diffusion model and found that the processing time can be predicted through the model. In this study, we found the effects of wood species, wood structure, temperature, and PEG concentration on the impregnation rate. Further, we investigated the shrinkage of woods after drying and found that the volumetric shrinkage is lower than 5% if the concentration of PEG is larger than 74% in mass fraction.Supercritical drying : Carbon dioxide was used as the supercritical fluid. Since the mutual solubility in water-carbon dioxide system is small, water in the wood was replaced by ethanol and then the ethanol was replaced by isoamyl acetate. In this work, penetration rates of ethanol and isoamyl acetate were measured and analyze … More d based on the diffusion model to estimate effective diffusion coefficients. The effective diffusion coefficient was 44% of the molecular diffusion coefficient for ethanol-water system. For isoamylacetate-ethanol system the effective diffusion coefficient was about the same as that for the ethanol-water system. Consequently, the effective diffusion coefficients for the both systems were found to be 0.3 cm^2/day at 25ﾟC,regardless of wood species. The molecular diffusion coefficient of isoamylacetate in supercritical carbon dioxide was predicted to be 11.5 cm^2/day. In this case, the effective diffusion coefficient was taken to be 5.06 cm^2/day which is 44% of the molecular diffusion coefficient, as in the case of ethanol-water system. Predicting the processing times for both of the PEG impregnation and supercritical drying methods, the time required for the supercritical drying method was found to be a quarter of that for the PEG impregnation method. Finally, the shrinkage of wood after drying was measured. The volumetric shrinkage after supercritical drying was less than 20%, which is 7% in length assuming isotropic shrinkage of wood. Less

在本研究中，从化学工程的视图中研究了超临界干燥在保存水口的木材和PEG浸渍法中的应用。PEG浸渍方法：我们已经基于扩散模型分析了用PEG分析的浸渍，并发现可以通过模型预测处理时间。在这项研究中，我们发现木材物种，木材结构，温度和钉浓度对浸渍率的影响。此外，我们研究了干燥后木材的收缩，发现如果PEG的浓度大于质量分数，则体积收缩率低于5％。质量干燥：二氧化碳用作超临界流体。由于二氧化碳系统中的相互溶解度很小，因此木材中的水被乙醇代替，然后用乙醇代替乙醇。在这项工作中，测量乙醇和乙酸异戊酰基的穿透速率并分析……基于扩散模型的更多d，以估算有效的扩散系数。有效扩散系数是乙醇 - 水系统分子扩散系数的44％。对于异乙二酸乙醇系统，有效扩散系数与乙醇 - 水系统的扩散系数大致相同。因此，无论木材种类如何预计超临界二氧化碳中等二酰乙酸酯的分子扩散系数为11.5 cm^2/天。在这种情况下，有效扩散系数为5.06 cm^2/天，是分子扩散系数的44％，如乙醇 - 水系统。预测PEG浸渍和超临界干燥方法的处理时间，发现超临界干燥方法所需的时间是PEG浸渍方法的四分之一。最后，测量干燥后木材的收缩。超临界干燥后的体积收缩小于20％，假设木材的各向同性收缩为7％。较少的