Flow development and prediction of solids concentration in a large gas-solids turbulent fluidized bed

In a 5 m high turbulent fluidized bed with a 0.3 m inner diameter, local solids concentration in the dense region and axial pressure difference along the column were measured using an optical fibre probe (PC6M) and differential pressure sensors (PX653), respectively. The time-series signals of the solids concentration fluctuations are analyzed via statistical methods. The axial and radial profiles of solids concentration are non-uniform. In the developing dense region, the radial profiles of solids concentration are significantly influenced by operating conditions, and the fluctuation of solid concentration is considerably enhanced with the development of flow. In the fully developed dense region, the axial solids concentration decreases monotonously with height, and the radial profiles of solids concentration are exponential. The flow development in the dense region could be accelerated by the superficial gas velocity. Based on the analysis of the characteristics of the radial solids concentration distribution in the dense region, an empirical correlation of this distribution is proposed. The formulated correlation is found to be consistent with the experimental data reported in the literature.