Modes of combustion of a porous carbonized particle with air in a high-temperature furnace

A theoretical model for the combustion of a porous carbonized particle with allowance for radiant heat transfer to the walls of the furnace is proposed. The model and experimental data are analyzed. The analysis shows that there are three particle-combustion modes: heterogeneous: gas-phase, and transitional (between the first two). It is shown that, when the experimental correlation between the combustion rate and particle temperature used in this paper is valid, the behavior of the combustion rate in the transitional mode must exhibit a critical point at which the combustion rate sharply decreases as the temperature of the furnace wall increases (combustion-rate crisis). Regions in which each of the modes of combustion of a porous carbonized particle exists are identified.