Discharge composition and concentration profiles in a continuously operating spouted bed

Abstract

The cause of segregation at the discharge in a continuously operating spouted bed has been investigated. Radial concentration profiles of the coarse component have been detected in a two‐component mixture of glass ballotini at different spouting regimes, at different bed levels and discharging from openings at several bed depths. The annulus of a spouted bed has been shown to move in a fashion close to a plug flow without altering the concentration gradients existing below the bed free surface. Consistent with previous results, percolation induced segregation was negligible under these experimental conditions. The concentration existing at the column wall has been shown to be identical to that in the outgoing stream of solids and segregation phenomena at the outlet cannot explain a discharge composition different from the mean concentration in the bed. The particle trajectories in the fountain are believed to be responsible for the radial concentration gradient in the annulus of the spouted bed.

Fountain Geometry in Shallow Spouted Beds

“…Furthermore, the role of the fountain in the distribution of the solid in the upper surface of the annulus makes it of vital importance in the segregation phenomena. [5][6][7] Furthermore, the consideration of the gas-solid contact in the fountain is especially important in shallow beds, in which the fountain contributes to an important fraction of the total contact in the bed. In previous papers, significant properties of the fountain have been studied, such as the bed voidage and particle velocity.…”

“…The knowledge of solid flow in the fountain is required in order to relate the solid flow in the spout and annulus and to assemble, by means of correlations, the quantitative description of solid flow in the three bed zones of the spouted bed. Furthermore, the role of the fountain in the distribution of the solid in the upper surface of the annulus makes it of vital importance in the segregation phenomena. − …”

Segregation in Conical Spouted Beds with Binary and Ternary Mixtures of Equidensity Spherical Particles

“…In the literature, segregation studies in spouted beds have been carried out for cylindrical contactors and only in a qualitative way, with the aim either of determining cycle times and trajectories of the particles (Cook and Bridgwater, 1978; Robinson and Waldie, 1978;Piccinini et al, 1977; Uemaki et al, 1983;Kutluoglu et al, 1983;Ishikura et al, 1983; Cook and Bridgwater, 1985), or of obtaining information for designing the inlet and the outlet for continuous operation (Rovero and Piccinini, 1985;Piccinini, 1980;Piccinini and Cancelli, 1983).…”

Fluid Dynamics Analysis of a Draft-Tube Continuous Spouted Bed with Particles Bottom Feed using CFD

“…Spouted beds make high contact fluid−solid possible, and they are usually applied to systems where fluidized beds are not efficient, especially when the particle diameter is above 1 mm . This equipment has been used on a large number of processes, due to high heat and mass-transfer rates. − Moreover, spouted beds are known for their low segregation compared with fluidized beds, , which is advantageous to provide more homogeneous products.…”

“…1 This equipment has been used on a large number of processes, due to high heat and mass-transfer rates. [2][3][4] Moreover, spouted beds are known for their low segregation compared with fluidized beds, 5,6 which is advantageous to provide more homogeneous products.…”