Numerical Study of Partial Oxidation of a Single Coal Particle in a Stream of Air

This work is devoted to the numerical study of the impact of the Reynolds number on the partial oxidation of a single moving coal particle. The model includes four gaseous chemical species (O₂, CO₂, CO, N₂). Two heterogeneous surface reactions and one homogeneous gas reaction are employed. The Navier-Stokes equations coupled with the energy and species conservation equations were used to solve the problem. Based on the results of the numerical simulations we found the existence of three basic regimes characterizing the distribution of CO around the particle. The first regime, which we call gasification regime, exists by low surface temperatures of the particle and high Reynolds numbers and is characterized by absence of CO₂ gases around the particle. The second regime is transitional. It is characterized by a horseshoe-shaped CO distribution around the particle. And the third regime is defined by a flame sheet (thin CO₂ layer) surrounding the particle and elongated in the flow direction. This regime corresponds to the combustion of the particle and exists at higher temperatures of the particle surface.