ABSTRACT The latest advances on the hydrodynamic study of conical spouted beds are collected in this review. This contact method links specific characteristics of conventional spouted beds with a substantial capacity for bed expansion, making this contact method especially useful for applications where a vigorous movement of the solid is required, such as happens in the handling of solids that are sticky, of irregular texture and with particle size distribution. For the design of the contactor, the geometric factors of the contactor-particle system must be established within given ranges. Similarly, the hydrodynamic correlations for calculation of minimum gas velocity, maximum pressure drop, operation pressure drop, bed expansion, minimum bed height, and for scaling up are presented. The gas flow pattern is described by means of a disperse plug flow model. The dispersion coefficient corresponding to given operating conditions can be calculated by a general correlation. Segregation is reduced and correlations established following a similar procedure as in fluidization can be used for calculation of mixing indices. The following local properties of the bed have been determined: spout geometry, bed voidage and particle trajectories. Thus, the particular characteristics of solid fluid in the contactor are established. On the basis of the properties of the conical spouted beds, they are used in novel applications. The equipment set up for biomass treatment (combustion, gasification or pyrolysis) and for a reaction of catalytic polymerization are described.
Buy this Article
|