为了探索农业废弃物优质转化的新途径,采用吉布斯自由能最小原理和试验研究相结合的方法,分析麦秸/羧甲基纤维素钠(CMC)在超临界水中转化为富氢气体时气体产物的分布特点.结果表明主要产气为氢气、二氧化碳和甲烷,在亚临界区(330~374℃)、低温的超临界区(375—430℃)以及高温的超临界区(≥430℃),产物分布明显不同.尤其是氢气,其摩尔分数分别从最低、居中上升到最高(66%),这表明高温明显有利于制氢,但温度升高到一定值后,气体产物的平衡组分不再变化.研究表明,温度和质量分数对产气的作用远大于压力,产气的高热值随物料质量分数的增加而增加,随反应温度的升高而下降.提出麦秸/CMC气化制氢的最佳温度为450~600℃.
In order to look for a new technology for upgrading agriculture waste, hydrogen production from straw/carboxymethylcellulose (CMC) gasification in supercriticat water (SCW) was investigated by minimum Gibbs free energy theory and experimental methods. The results show that the main product gases are hydrogen, carbon dioxide and methane. There is very large difference in product gases distribution in different temperature range. In the undercritical water range(330 -374 ℃ ) , low supercritical wa- ter range(375 -430 ℃) and high supercritical water range( ≥430 ℃ ), hydrogen mole fraction increases from the lowest to the highest in the product gases. High temperature favors hydrogen generation, but the composition of product gases keeps constant when the temperature reaches a high value. Simultaneously, temperature and concentration of feedstock have larger effects than pressure on product gases. High heating value increases with concentration of feedstock, and decreases with temperature. It is proposed that the optimal temperature for hydrogen production from the mixture of 2% straw and 2% CMC gasification in SCW is 450 -600 ℃.