MODELING OF CIRCULATING FLUIDIZED-BED COMBUSTION OF COAL

In the proposed model, the hydrodynamics of a circulating fluidized bed (CFB) are described by an empirical correlation deduced from cold model experimental data. Volatile matter is assumed to be released instantaneously from coal on entry into the furnace, and is assumed to burn uniformly throughout the riser. The combustion of residual char particles is assumed to begin with oxygen diffusion to the burning char particle where the following reaction occurs: C + 1/2 O2 --> CO. The carbon monoxide produced is then oxidized by oxygen to produce carbon dioxide according to reaction: CO + 1/2 O2 --> CO2. A uniform gas temperature is assumed throughout the riser, whereas the temperature of a burning char particle is calculated from heat balances on the char particle. Agreement between experimental data and model prediction is encouraging.