Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
241061 | Proceedings of the Combustion Institute | 2009 | 8 Pages |
Ash particles produced from pulverized coal combustion are considered to be tri-modally distributed. These include the well-known ultrafine and coarse modes, and a central mode that is less reported but attracts increasing attention. This work presents a preliminary study on the formation mechanisms of the central mode particles during pulverized coal combustion. Experiments of four sized and density-separated coal samples were carried out in a laboratory drop-tube furnace under various controlled conditions. Experimental data show that the ash particle size distributions have an evident central mode at ∼4 μm for all coal samples. Increasing combustion temperature leads to an increase in the central mode particle formation, which is thought to be due to enhanced char fragmentation. The small-size coal sample produces a larger amount of the central mode particles, reasonably due to abundant fine particles in the parent coal sample. Under similar combustion conditions, both the Heavy (>2.0 g/cm3) and Light (<1.4 g/cm3) coal fractions produce a central mode, indicating that not only the included minerals but also the excluded minerals contribute to the formation of the central mode particles.