Bottom Bed in Circulating Fluidized Bed Combustor

Resumo

A bottom bed, similar to a heterogeneous fluidized bed, in a circulating fluidized bed combustor is considered. It is shown that the formation of the bottom bed is contributed to not only by the gravitational force and the drag force, but also by an additional force produced by the circulation of bed-forming particles. A procedure for calculating the parameters of the bottom bed with consideration for this force is proposed. The conditions of the formation and existence of such a bed are formulated. The transport velocity, average porosity, residence time, and other characteristics of the bottom bed are determined under typical operating conditions of combustors. Calculations for published experiments are carried out. The results are compared with available experimental data.