Comparative Study On Drying Of Domestic Pine And Russian Pine

Wood drying is the most energy-consuming part of wood product production,and China's wood drying technology still has problems such as long cycle,high energy consumption and unstable quality,and releases volatile organic compounds(VOCs)into the atmosphere during drying.It has brought certain harm to the environment and human health.Therefore,it is urgent to solve the key problems in the cost,quality,efficiency and energy saving and emission reduction in the process of drying wood preparation materials.In this study,the two kinds of sawn timbers of plantation Pinus sylvestris and Russian Pinus sylvestris were studied.100? test method was used to study the drying characteristics of two kinds of Pinus sylvestris.The drying schedule of two kinds of wood was developed.Drying characteristics of plantation Pinus sylvestris and Russian Pinus sylvestris were studied by four different drying methods:high temperature drying,conventional solar combined drying and solar high temperature combined drying.The drying time,drying rate,drying quality,drying energy consumption and Release law of VOCs during conventional and high temperature drying.The research results are as follows:1.100? test results show that the plantation Pinus sylvestris and Russian Pinus sylvestris are all easy-to-dry tree species,without internal cracks,and the deformation of the section is not obvious.2.The plantation Pinus sylvestris wood drying faster than the Russian Pinus sylvestris.The total rate of constant temperature and high temperature drying of plantation Pinus sylvestris was 5.81%/h,which was 159.37%higher than that of conventional drying.The total rate of the heating high temperature drying was 4.54%/h,which was 102.68%higher than that of conventional drying.The total rate of constant temperature and high temperature drying of Russian Pinus sylvestris was 4.27%/h,which is 130.81%higher than the conventional drying.The total rate of the heating high temperature drying is 3.78%/h,which is 104.32%higher than the conventional drying.3.Compared with high-temperature drying,the various quality indicators have reached the dry quality level of more than two grades.After high-temperature drying,the wood has a slight deformation of the tile,and the color change is dark yellow and dark yellow.Increased bending strength and modulus of elasticity.4.The energy-saving effect of plantation Pinus sylvestris using high temperature drying is more significant than that of Russian Pinus sylvestris.The initial moisture content of the test material is 70%dry to a final moisture content of about 10%.The constant temperature and high temperature drying of plantation Pinus sylvestris is 55.04%compared with conventional drying,and the heating high temperature drying is 48.53%higher than conventional drying.The constant temperature and high temperature drying of Russian Pinus sylvestris is 37.88%higher than that of conventional drying.The heating high temperature drying is 17.47%higher than that of conventional drying.5.The total VOCs released by plantation Pinus sylvestris was much higher than that of Russian Pinus sylvestris.The high temperature drying caused the release and release rate of VOCs to increase significantly.The aldehyde volatiles released during the drying process of plantation Pinus sylvestris are mainly propionaldehyde,n-hexanal,n-pentanal,etc.;the volatiles of terpenes are mainly a-pinene,?-pinene,myrcene,etc.;benzene is dried at high temperature.The process has a lot of release.The main volatiles released during the drying process of plantation Pinus sylvestris are terpene volatiles such as a-pinene and Limonene,followed by aldehydes such as n-hexanal,n-pentanal and benzaldehyde.During the conventional drying process of plantation Pinus svlvestris,VOCs are mainly released in the latter stage of drying,and VOCs are mainly released in the early stage of drying during high temperature drying.The release and release rate of VOCs during the conventional drying process of Russian Pinus svlvestris is extremely small,and VOCs are mainly released during latter stage of drying.6.Using solar energy-conventional combined drying and solar-high temperature combined drying,the two kinds of Pinus sylvestris wood except the residual stress,the other quality indicators have reached the wood dry quality grade 1.The residual stress of the solar energy-high temperature combined dryness of the plantation Pinus svlvestris was 5.3%.The conventional solar and high temperature combined dry residual stress of Russian Pinus sylvestris wood was more than 7%.The effect of solar combined drying on the color of the wood is more serious than conventional drying and high temperature drying.For every cubic meter of plantation Pinus sylvestris,the conventional combined drying of solar energy is about 40.09%energy saving than conventional drying,and about 7.08%energy saving compared with high temperature drying;solar high temperature combined drying is 68.76%energy saving compared with conventional drying,and energy saving is 56.76%compared with high temperature drying.Each cubic meter of Russian Pinus svlvestris wood,solar energy combined dry drying is only 10.12%energy saving than conventional drying,solar-high temperature combined drying is 55.76%energy saving than conventional drying,and energy saving is 46.39%higher than high temperature drying.