Hydrodynamics of a spouted bed with a porous draft tube containing a small amount of finer particles

A small-size spouted bed with a porous draft tube was employed to obtain hydrodynamic data of binary mixtures of glass beads for a range of operating conditions and design factors. In this case, a small amount of finer particles was added mostly to the large majority of coarser particles. Under this condition, minimum spouting velocity, bed pressure drop, hold-up of solid particles within a draft tube, gas flow rate through the annulus and solids circulation rate were determined by changing the total gas flow rate and the mass fraction of finer particles as operating parameters, and by changing the height of the entrainment zone and the draft tube diameter as geometric parameters. The results show that the gas flow rate through the annulus increases by increasing the distance between the gas inlet nozzle and the bottom of the draft tube, that is, the height of the entrainment zone, but decreases with increasing draft tube diameter and mass fraction of finer particles. The porous draft tube shows a higher gas flow rate through the annulus than the non-porous draft tube, particularly in the case of the low height of the entrainment zone. The solids circulation rate increases with increasing gas velocity, the height of the entrainment zone and the porous draft tube diameter. Moreover, the porous draft tube leads to a higher solids circulation rate than the non-porous draft tube.

[1]  J. Grace,et al.  Particle segregation in spouted beds , 1983 .

[2]  John R. Grace,et al.  Particle velocity profiles and solid flow patterns in spouted beds , 1994 .

[3]  F. Berruti,et al.  An innovative non-mechanical solids feeder for high solids mass fluxes in circulating fluidized bed risers , 1996 .

[4]  H. Ichikawa,et al.  Microencapsulation of Pharmaceuticals by Fluidized Bed Process , 1997 .

[5]  Anthony G. Fane,et al.  Spouting with a porous draft-tube , 1983 .

[6]  Ravi K. Konduri,et al.  Atmospheric spouted bed combustion: The role of hydrodynamics in emissions generation and control , 1995 .

[7]  T. Ishikura,et al.  A Correlation of Minimum Spouting Velocity for Binary Mixtures of Particles , 1982 .

[8]  J. T. Freire,et al.  Fluid dynamics characterization of a pneumatic bed using a spouted bed type solid feeding system , 1992 .

[9]  H. Nagashima,et al.  Hydrodynamics of a spouted bed with an impermeable draft tube for binary particle systems , 1999 .

[10]  J. Van Brakel,et al.  DRYING CHARACTERISTICS OF A DRAFT TUBE SPOUTED BED , 1983 .

[11]  Leo A. Behie,et al.  SOLIDS CIRCULATION IN SPOUTED AND SPOUT-FLUID BEDS WITH DRAFT-TUBES , 1990 .

[12]  Atsushi Tsutsumi,et al.  Solid Circulation in a Spouted Bed with a Draft Tube , 1998 .

[13]  Osamu Uemaki,et al.  Particle segregation in a spouted bed of binary mixtures of particles , 1983 .

[14]  M. Anabtawi,et al.  Minimum spouting velocity for binary mixture of particles in rectangular spouted beds , 1998 .

[15]  T. Nagai,et al.  SPOUTED BED WITH A DRAFT-TUBE WITHOUT GAS INLET NOZZLE OR ORIFICE , 1996 .

[16]  Leo A. Behie,et al.  The internally circulating fluidized bed (ICFB): A novel solution to gas bypassing in spouted beds , 1992 .

[17]  W. Svrcek,et al.  Ultrapyrolysis of propane in a spouted-bed reactor with a draft tube , 1989 .