流化床内油页岩半焦燃烧过程孔隙特性分析

Analysis on Influence Factors of the Characteristic of Pore Structure During Combustion of Oil Shale Semi-coke

在自行设计搭建的小型流化床试验台上进行吉林桦甸、汪清的油页岩半焦燃烧试验,得到不同工况下的灰样,在Gemini2380快速比表面积分析仪上测得灰样吸附等温线,采用BJH法计算孔分布。根据测试结果,分析了半焦种类、流化床温、半焦粒径、流化风速、加料量等因素对半焦孔隙结构的影响,并对灰样进行电镜扫描和分形分析。结果发现,半焦原样的孔隙结构已经非常发达,燃烧过程中半焦的孔体积整体呈逐渐减小的趋势;较低的燃烧温度更有利于形成发达的孔结构;不同种类半焦的孔分布曲线差别较大;一次加料量影响孔隙生成的进程,但不会改变灰样的最终孔隙结构;较大风速和较小半焦粒径,都容易破坏孔结构。

Combustion experiments with semi-coke of Huadian and Wangqing oil shale were conducted in a bench-scale FBC reactor. Ash samples were obtained under different combustion conditions. Adsorption isotherms were determined by Micromeritics Gemini 2380 specific area analyzer under nitrogen atmosphere. The pore size distribution of samples was determined on the basis of BJH theory. Influence factors on pore structure of ash, such as different semi-coke, bed temperature, particle size, apparent fluidized velocity and batch feeding quantity of the above-mentioned semi-coke were investigated. The result shows that pore structure of semi-coke was already well developed and the total porous volume of the combustion. The pore size fuel decreased gradually during distribution of different semi-coke presents obvious difference. Low bed temperature favors the formation of porous structure. Batch feeding quantity has effect on the process of porous structure, but couldn＇t change the ultimate ash pore structure. Higher fluidized velocity and smaller particle size lead to more pores destroyed.