Behavior of Inorganic Materials during Pulverized Coal Combustion

Conclusions

From the analysis of CCSEM data of raw coal, chars and fly ash of Coal A and Coal B, the results regarding the behavior of inorganic particles during coal combustion was obtained as follows.

• 1) Aluminosilicates (Si-Al) particles such as Kaolinite react Ca and Fe particles to produce calcium aluminosilicates (Si-Al-Ca) particles and iron calcium aluminosilicates (Si-Al-Ca-Fe) particles. The production rate of these particles varies according to the coal type and the combustion rate.

• 2) The weight proportion of the fine particle region and of the coarse particle region decreased under combustion while the proportion of intermediate particle size between them increased. The increasing and decreasing behavior concerning weight proportion of size range also differed according to coal type. Fly ash obtained from the combustion of Coal B had coarser particles than that of Coal A. This was affected by the amount of productions of calcium aluminosilicates (Si-Al-Ca) and iron calcium aluminosilicates (Si-Al-Ca-Fe) particles.

• 3) The proportion of included particles in the raw Coal B was much more than that in Coal A and Coal B was also more combustible. It is considered that the higher proportion of included particles and combustibility promoted the reaction of Si-Al particles and Ca, Fe particles and produced coarser fly ash particles as compared to Coal A.