神华配煤孔隙分形对燃烧特性的影响

Effects of pore fractal structures on combustion of Shenhua coal blends

利用氮气吸附仪、沉降炉、扫描电镜(SEM)和X-射线能谱仪(EDS)研究了动力配煤的孔隙分形结构对着火和燃烧特性的影响.对神华煤分别与准格尔煤和澳洲煤组成的配煤研究表明,配煤孔隙分形维数随单煤比例呈现出单调变化规律,并且与比表面积和比孔容积的变化规律基本一致.当神华配煤的分形维数由2.451增加到2.482和2.532时,着火温度由783℃降低到587℃和462℃,飞灰中碳的质量分数由3.62%减少到2.83%和1.83%,说明配煤的分形维数越大则越容易着火和燃尽.随着准格尔煤比例增加和神华煤比例减少,燃烧渣样中硅铝质量比减小且灰熔点提高,导致配煤的结渣程度明显减轻.

The nitrogen adsorption instrument, drop tube furnace, scanning electronic microscope （SEM） and X-ray energy dispersive spetrometer （EDS） were used to study the effects of pore fraetal structures on combustion of coal blends. The results showed that the pore fractal dimensions of Shenhua coal blends monotonously change with the blend ratio of a parent coal, which is consistent with the specific surface areas and pore volumes. When the pore fractal dimension of the coal blends increases from 2. 451 to 2. 482 and 2. 532, the ignition temperature decreases from 783 ℃ to 587 ℃ and 462℃, while the unburned carbon mass fraction in the fly ash decreases from 3.62% to 2.83% and 1.83%. It implies that the coal blends with larger pore fractal dimension are easier to ignite and burn out. When the Zhungeer coal content increases and the Shenhua coal content decreases in the coal blends, the ratio of SiO2 to Al2O3 in the combustion slag of coal blends decreases and the ash softening temperature increases, which results in a lower slagging degree.