O_2/CO_2气氛燃煤半焦孔隙特性分析

在沉降炉上制备了不同燃烧气氛、不同燃尽程度的半焦,采用低温氮吸附仪和扫描电子显微镜测定了其孔隙结构和表面形态.结果表明,所取的半焦试样均具有完整且连续的孔结构体系;但在相同的操作条件下,O_2/CO_2气氛下半焦试样的孔结构参数及其分形维数均小于相同O_2浓度的O_2/N_2气氛下的情况;两种气氛下煤焦的燃尽过程中,孔隙结构参数(S_(BET)、V_(BJH)和d_(pore))随燃尽率的增加均呈减小趋势;SEM图像的定性分析结果与N_2吸附的定量测量吻合较好.研究结果为深入认识O_2/CO_2气氛下煤粉的孔隙结构与其燃烧特性的关系提供了基础.

ANALYSIS OF PORE STRUCTURE IN COAL CHAR OBTAINED IN AN O_2/CO_2 ENVIRONMENT

In a drop-tube furnace,coal char samples with various burn-off rates.were prepared in different environments and analyzed with N_2 adsorption analyzer and scanning electronic microscope (SEM).Results show that all these samples are possessed in a continuous and integral pores system,but the CO_2 char(derived in O_2/CO_2 environment)shows lower specific surface area and specific pore volume than that of N_2 char.During the combustion processes,pore structure parameters of all samples,such as S_(BET),V_(BJH) and d_(pore) decrease with the increase in burn-Off rate.SEM results also present the similar rules and agree well with those determined with N_2 adsorption method.Findings of present research might have important implications for better understanding of the relationship between pore structure and combustion characteristic of pulverized coal in the O_2/CO_2 environment.