木聚糖高温水蒸汽气化特性及动力学研究

Gasification characteristics and kinetics of xylan in high temperature steam

采用热重分析仪研究木聚糖在不同高温水蒸汽浓度氛围下的气化行为。研究表明,在水蒸汽气氛下,木聚糖的高温气化可以分为挥发分析出阶段（190～690℃）和半焦气化阶段（690～770℃）;当温度〉700℃时,水蒸汽才能与热解反应完成后的焦炭发生反应,产生CO与H_2,然后进一步反应生成CO_2与H_2,此时水蒸汽才能达到催化反应气化效果;两个区间阶段所需的活化能均随着温度的升高逐渐增大;采用一级二段反应模型作为木聚糖高温水蒸汽气化阶段的动力学模型,理论曲线与实验数据拟合程度良好。

The gasification behavior of xylan as the model compound of hemicellulose under the condition of different high temperature steam concentration,was studied by the thermal gravimetric analyzer（ TG）.The studies found that the gasification of xylan in high temperature steam could be divided into two stages,i. e.,the volatile precipitation stage（ 190 ～ 690 ℃） and the carbocoal gasification stage（ 690 ～770 ℃）. When the temperature was higher than 700 ℃,steam could react with the coke derived from the pyrolysis reaction of xylan to yield CO and H_2,and further convert to CO_2 and H_2. In this case the steam could achieve the catalytic gasification. The activation energy required in the two interval stage gradually increased with the increase of temperature. Using a two-stage reaction model was used as the dynamic model of xylan in the period of gasification under high temperature steam,which was verified by the well fitting of the theoretical curve and the experimental data.