不同木材种类炭化率的研究

根据木材本身的材性缺陷和木材加工厂的废料存量情况,选择了岑树、山毛榉、花旗松、橡木、白杨和云杉作为研究对象,研究了这些木材在实验室热解条件下炭产品的生产能力.在390～672 ℃范围内,共做28次分组热解试验,试验时间为2 h,每组10个试件;390～440 ℃范围内,共做8次分组热解试验,试验时间为1 h,每组10个试件.分别测试了试件在热解试验前后的质量损失和体积的变化,特别是试件在热解实验后的炭化率.结果表明:所有树种的试件在500℃时完全炭化,试件的相对质量损失约为25%,试件的三维收缩约为30%(T)、25%(R)、20%(L).不同树种试件的炭化率是相同的,木材的炭化率和树种无关,木材热解炭化后的理论孔隙率经验公式为ε=100-30ρ01,通过此公式可研究木材的初始干燥密度预测其生产炭产品的性能.

Study on Conversion Ratio of Different Wood Species Into Charcoal

The study presented hereby is the first part of a more general investigation in Europe concerning the valorization of wood wastes by activation of carbon obtained by pyrolysis of different wood species. According to the large scale storage of wood wastes produced by wood industry and their low economical value induced by some strong defects, six different European wood species have been tested and their ability to produce charcoal has been qualified. These sik different wood species are: ash, beech, douglas, oak, white poplar and sitka spruce. Twenty-eight pyrolysis tests have been performed at different constant temperatures (390～672 ℃) during two hours. Another eight tests have been performed at two different temperatures (390℃ and 440℃) with four different wood species (oak, poplar, spruce and douglas). The pyrolysis duration is one hour. Tests on cubic wood samples have permitted to determine the dimensions variations and mass loses induced by the thermal degradation of wood during its carbonization. In particular, the conversion ratio of wood material into charcoal has been determined as a function of the wood species and the pyrolysis conditions. The experimental results show that the carbonization is complete for all the species at a temperature of 500℃ and the relative mass loss after a total carbonization is constant and tends to 25%.The shrinkage is near 30% in the tangential direction, 25% in the radial direction and 20% in the longitudinal direction. After the experimental result analysis, it shows that the conversion ratios of all the wood species are similar and they have no relationship with wood species. The theoretical porosity ratio formula is ε=100-300 ρ01, the quality of charcoal product can be predicted by this formula.