木质装饰板材贫氧条件下燃烧和热解特性研究

本文利用热重差热分析仪,在各种不同的氧气浓度下对落叶松、红木和红松样品进行实验。通过对TG、DTG和DTA曲线的分析,样品干燥基要经历两个失重过程,第一个失重过程主要是纤维素和半纤维素的热解,第二个失重过程主要是木质素的炭化分解和燃烧。在各氧气浓度条件下,热解失重的第一个阶段TG和DTG曲线差异很小;在各样品失重的第二个阶段,随着氧气浓度的增加,TG和DTG曲线左移,反应结束的温度明显降低。氧气能使木质素的炭化物氧化并进而可能使其着火燃烧,从而使反应进程加快。当氧气浓度大于6.32%时,各样品DTA曲线上均有两个明显放热峰,并且随着氧气浓度的增加,DTA曲线放热峰越尖锐,放热峰面积越大,说明氧气浓度越大,在两阶段失重过程中更多的挥发分物质和固体炭化物参与燃烧。

CHARACTERISTICS OF COMBUSTION AND PYROLYSIS FOR DECORATIVE WOODS IN POOR-OXYGEN ATMOSPHERE

Dynamic experiments have been performed to investigate the characteristics of combustion and pyrolysis for decorative woods(larch and roadwood and redpine) in different oxygen concentration atmospheres. The pyrolysis of dry basis of samples consists of two stages in all atmospheres. At the first stage cellulose and hemicellulose pyrolysis , ligin pyrolysis and char at the second stage. But in air atmosphere the presence of oxygen causes the appearance of gas-phase reactions between the volatile released and oxygen, promote the combustion of the char residue. The difference of thermographs is neglectable an the first stage in different oxygen concentration atmospheres. Due to oxygen promotes the oxidization and combustion of the char at the second stage, the oxygen concentration has more remarkable effect on the second stage than on the first stage. When oxygen concentration is more than 6.32%, DTA thermographs of all sample exist two exothermic peak, the amounts of combustion volatiles and char residues increase with oxygen concentration.