变速升温对玉米秸秆热解产物特性的影响

Effect of Variable Heating Rate on Pyrolysis Process and Product Characteristics of Corn Stalk

通过玉米秸秆的变速升温及传统匀速升温热解试验,对不同热解形式下生成的生物炭、生物油及热解气进行检测分析,探究升温速率对其热解产物特性的影响。试验表明,玉米秸秆减速升温生物炭得率和热解气得率分别为29.82%和27.49%,而加速升温的产物中生物油所占比例较大。通过热重试验及气相检测,发现不同的升温设置改变了生物质热解进程。此外对非冷凝气体进行气相检测分析发现,CO、CO2先于CH4溢出,而H2的溢出浓度随着热解温度的升高而增大。对生物油主要成分的检测分析发现,减速升温所制生物油的主要成分为小分子物质,大分子有机物含量很少,而加速升温可以得到更加丰富的多环芳烃。通过对产物的对比分析发现,在相同的热解时间下,减速升温速率设置不仅可以保证热解产物中较高的生物炭得率,且热解气得率比匀速升温试验增加4.49%,生物油相得率减少4.51%,且稠环芳烃含量较少。优化升温速率设置可提高生产效率,从而为生物质热解工程中的炭气油联产提供新的思路。

The influence of heating rate on slow pyrolysis was explored. The corn stalks were tested via two types of variable heating rate comparing with three types of constant heating rate. The products such as char, pyrolysis bio-oil and non-condensable gases at different heating rates were also detected. The pyrolysis by decreasing heating rate resulted in 29.82% char and 27.49% non-condensable gases. While the increasing heating rate caused higher bio-oil yield which was not benefit to the production of char and pyrolysis gas. Thermo-gravimetric analysis of the raw materials showed that variable heating rate significantly changed the weight loss during pyrolysis process. It was found that CO and COz were released earlier than CH4 and H2 by performing gas chromatography test. In the higher temperature zone, the concentration of H2 was increased. The analysis of the main components in bio-oil confirmed that less macromolecular organic matter content was detected after pyrolysis by decreasing heating rate. While the increasing heating rate produced more polycyclic aromatic hydrocarbons. The concept of variable heating rate was presented. It was found that the pyrolysis by decreasing heating rate not only made sure the yields of chars and pyrolysis gas, but also increased the char yield by 4.49% , and deduced the bio-oil yield by 4.51% and this process was more to the benefit of poly-co-production with char and pyrolysis gas as the main products. This concept would provide new ideas for the project of biomass pyrolysis.