Characteristics of fine particulate matter formation during combustion of lignite riched in AAEM (alkali and alkaline earth metals) and sulfur

The high contents of AAEM (alkali and alkaline earth metals) and sulfur in zhundong coal result in more fine particulate matter during coal combustion. In this paper, the emission of fine particulates from zhundong coal riched in AAEM-sulfur and zhunnan coal riched in aluminum-silicon was investigated in a drop tube furnace. Co-combustion of zhundong coal and zhunnan coal was further investigated to study the effect of interaction among different elements in coal on the PM formation. The size distribution, concentration and composition of the particulates were analyzed by low pressure impactor (DLPI) and scanning electron microscopy (SEM). The distribution of sodium, magnesium, calcium, iron and sulfur in fine particulates and their effects on the generation of fine particulates were obtained. The results show that the fine particulates from AAEM-sulfur rich coal combustion mainly consist of sulfates and oxides of AAEM. The amount of fine particulates from burning aluminum-silicon rich coal decreased significantly. The composition of PM_0.4 and PM_0.4+ are significantly different. Co-firing of AAEM-sulfur rich coal with aluminum-silicon rich coal has an obviously synergetic effect of reducing the fine particulates emission. The capture of AAEM and iron by aluminum-silicon compounds plays an important role in PM₁₀ reduction during blended coal combustion. The change of sulfur content in PM_0.4 is consistent with the change of AAEM content.