Modelling the internal flow structure of circulating fluidized beds

summary, given the pressure distribution along the CFB riser, or equivalently the average voidage profile and the net solids circulation rate, G, the model equations can be solved sequentially to provide a steady-state characterization of the two-phase flow. The gas and solids velocities provided by the model represent average values over the cross sectional area of the core and annular regions. However, if information is avail- able from similar units, a radial velocity distribution can be readily incorporated into the model to provide a more realistic representation of the flow. Kefa et al. (1988), for example, have found that the gas velocity follows the power law with the exponent n = 1/7. Simulation Results and Discussion The validity of the proposed model was tested using recently obtained experimental data available in the litera- ture (Bader et al., 1988; Horio et al., 1988; Brereton, 1987; Hartge et al., 1988). The experimental data employed in the evaluation cover a wide range of reactor sizes and operating conditions and are listed in Table 1. Each simulation has been performed by utilizing experimental average voidage profiles or pressure drop dis- tributions, as provided by the various authors, and by solving the model equations described