Modelling the internal flow structure of circulating fluidized beds

TLDR: In this article, the authors proposed a steady-state characterization of the two-phase flow using the average voidage profile and the net solids circulation rate of the core and annular regions.

Abstract: 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