分级处理秸秆的热解过程

Pyrolysis of Straw Obtained from Stagewise Treatment

利用热重-傅立叶红外联用分析仪(TG-FTIR)研究了麦秸、汽爆麦秸、发酵麦秸的热失重特性及其气体析出行为.实验表明,热失重过程主要分4个阶段:干燥阶段(30～150℃)、过渡阶段(150～200℃)、热解阶段(200～600℃)、炭化阶段(600～900℃);析出挥发分的机理过程分为2步:热解初始阶段发生脱羟基、脱羧基、脱烷基和解聚反应,析出含C-O-C基团、醇、醛、酸、酮和CO2,CO,H2O,CH4等气体化合物,炭化阶段发生脱烷基、羰基等反应,先后依次析出CH4,CO2,CO等气体.汽爆、固态发酵分级处理麦秸不仅使热解干气的产率降低约20%～30%,热解液的产率增加,而且热解液中羧酸类产量分别减少了30%和50%左右.

The pyrolysis characteristics of wheat straw with steam-explosion and solid fermentation treatment were investigated by the thermogravimetry coupled with the Fourier infrared spectroscopy to analyze the evolved gasses. The pyrolysis process with the increase of temperature from TG can be divided into four stages, including drying stage （30～150 ℃）, transitional stage （150～200℃）, pyrolysis stage （200～600℃）, and carbonization stage （600～900 ℃）. The results of pyrolysis from TG-FTIR show that the process can be divided into two steps： （1） splitting of hydroxide radicals, chain scissions and depolymerization, accompanied by evolution of water, acids, aldehydes, compounds containing C—O—C groups and CO, CO2, CH4, etc.; （2） aromatization and formation of graphite layers, accompanied in turn by evolution of CH4, CO2 and CO. The yields of uncondensable gases and carboxyl compounds decrease after steam explosion/solid fermentation treatment, but the yield of pyrolysis liquid increases by the stagewise treatment.