油页岩流化燃烧过程中表面特性的变化

Study on Surface Characteristics of Oil Shale During Fluidized Combustion

在自行设计搭建的小型流化床试验台上进行油页岩的燃烧试验,从不同床温中获得各燃烧时间下的油页岩焦样,通过Gemini 2380快速比表面积分析仪测定焦样吸附等温线,采用BET法计算样品的比表面积,由BJH法计算孔分布,FHH模型计算表面分形维数.结果表明焦样具有较连续完整的孔系统;油页岩焦样的比表面积及孔径分布具有相似的特点,在3nm附近有极值;随着燃烧时间的增加,比表面积和孔体积先迅速增加再逐渐降低,但相对于比表面积,孔体积变化曲线的波峰有一定的延迟;不同温度焦样的比表面积相差很大,750℃的最大值是850℃时的1.5倍左右;燃烧前期,焦样分形维数迅速增加,而后略有减小,燃烧后期几乎不再变化;燃烧过程中焦样分形维数明显大于油页岩原样.

Combustion experiments of oil shale were conducted in bench-scale CFB reactor. Samples of oil shale char were obtained under different bed temperature and different resident time. Adsorption isotherms were determined by Micromeritics Gemini 2380 specific area analyzer under nitrogen atmosphere. The specific surface areas and pore size distribution of samples were determined based on BET model and BJH theory, respectively. While surface fractal dimensions were calculated with FHH model. The results showed that all the samples consist of continuous and complete system of pores. Specific area and pore size distribution of different samples present relatively similar tendency~ most pore sizes were at maximum around 3 nm. Specific surface area and volume of pores increased rapidly with the increasing of resident time in the reactor, and then decreased gradually. But compared to specific area, there is some delay of which burned at 750℃ combustion, the fracta same time, the fractal are about 1 d dimensiu 1.5 times more than the samples prepared at 850℃. In the early stage of on of char samples increase sharply, and then decrease slightly. At the imension of char samples was significantly higher than that of orginal samples.