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):1/R=f(GR), where GR=(Gf−Gmf)/(Gs−Gmf)Here, the entire range of GR has been divided into two regimes: 0<GR≤0.15 and 0.15<GR≤1.0.