A Kumar

Influence of coaxial-rod- and coaxial-blade-type baffles on bed expansion in gas–solid fluidization

Bed expansion data were obtained for unbaffled and two different types of baffled (coaxial rod and coaxial blade) gas–solid fluidized beds for varying operating parameters: fluid mass velocity, particle size, density and initial static bed heights. Correlations have been developed for the prediction of bed expansion. For this, the values of minimum fluidization mass velocity (Gmf) and settling mass velocity (GS, considered as hindered settling) have been calculated with the help of available equations. The correlations developed are modified versions of those of Beranek and Sokol, where mass velocity ratio (GR) has been used in place of velocity (U):

Prediction of Bed Expansion in Unpromoted and Promoted Gas-Solid Fluidized Beds

Correlations have been developed for the prediction of bed expansion ratio in the line of the Godard–Richardson equation (1969) for unpromoted as well as promoted beds. The correlation factor ‘m’ of the Godard–Richardson equation has been expressed as a function of promoter parameters for promoted beds in addition to bed parameters as in the case of unpromoted beds. Three correlations for ‘m’ have been proposed for unpromoted and promoted beds with rod and blade promoters. The comparison of the results reveals that the Godard–Richardson equation is more suitable for unpromoted beds in the original form. In the case of promoted beds, the prediction deviates from the corresponding experimental values due to poor representation of flow parameter. Hence, the flow parameter of the Godard–Richardson equation has also been modified for beds with rod and blade promoters. A comparison has been made between the predicted values of bed expansion using the modified Godard–Richardson equation and the predicted vlaues obtained by correlations developed by Kumar and Roy (2002a) and the corresponding experimental values.

FLUIDIZED BED PRESSURE DROP IN PROMOTED GAS-SOLID BEDS WITH COAXIAL ROD, DISK, AND BLADE TYPE PROMOTERS

Bed pressure drop equations have been formulated for gas-solid fluidized beds with different types of promoters using Erguns equation (Ergun, 1952) and experimental data. Four rod promoters, seven disk promoters, along with one blade promoter were used in beds supported on five different distributors with open areas of 12.9%, 8.96%, 5.74%, 3.23%, and 1.43% of the column section. The predicted values of bed pressure drop using a modified (i.e., modified numerical constant) Burke-Plummer (Burke and Plummer, 1928) equation were compared with the corresponding experimental as well as the respective values obtained with the help of Kumar et al. (submitted) and traditional gas-solid fluidized bed equations.