稻秆半焦与CO2气化反应特性的研究

利用三种热解炉装置，分别在热解终温550℃～950℃、加热速率0.1K/s～500K/s下热解制取稻秆半焦。采用等温热重法，在STA409综合热分析仪上进行了稻秆半焦与CO₂的气化实验，考察了热解终温、热解速率以及气化温度对半焦气化反应性的影响。研究表明，热解条件对稻秆半焦的反应性影响很大。在热解终温为550℃～950℃时，随着热解温度的提高，其气化反应性呈下降趋势；热解速率越高，其气化反应性越好。在850℃～950℃，提高气化温度能提高稻秆半焦与CO₂的反应性。采用扫描电镜技术观测了0.1K/s和500K/s 两种热解速率下半焦的表面形貌。结果显示，后者具有更加丰富的孔隙结构，且大孔结构明显多于前者。采用混合反应模型描述了稻秆半焦与CO₂的气化反应过程，求取了反应动力学参数。

Study on CO_2 gasification reactivity of rice straw chars

The CO₂ gasification reactivity and structure of rice straw chars and the effects of pyrolysis temperature and heating rate were studied. Char samples were prepared by pyrolysis at 550℃~950℃ with heating rates from 0.1K/s to 500K/s in three different pyrolyzing reactors. The CO₂ gasification reactivity of char was determined by means of isothermal thermo-gravimetric analysis on a STA409 TGA. Results show that the gasification reactivity of char increases with the decreasing of pyrolysis temperature and with the increasing of heating rate. It is found that the gasification reactivity of char increases when the gasification temperature rises from 850℃ to 950℃. Scanning electron microscopy (SEM) analysis was employed to determine the impact of pyrolysis heating rate on the char structure. It is indicated that the char pyrolyzed at 500K/s is of more cavities than the char pyrolyzed at 0.1K/s. Moreover, the kinetic parameters based on the mixed reaction model were obtained.