Toshifumi Ishikura

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.

Mass transfer characteristics in gas bubble dispersed phase generated by plunging jet containing small solute bubbles

Abstract A new type of plunging jet absorber using a liquid jet containing small solute bubbles, which is formed through a nozzle having a gas sucking type bubble generator, was devised. The absorber consists of liquid jet and gas bubble dispersed phase. In this study, first, the effects of various conditions in the gas sucking type bubble generator on gas holdup h GD , specific gas–liquid interfacial area a D and gas–liquid interfacial area A D in the gas bubble dispersed phase were studied experimentally. Secondly, the mechanism of liquid phase mass transfer in the gas bubble dispersed phase was considered theoretically using a two-region model. Thirdly, the performance of this plunging jet absorber was evaluated. Consequently, it was found that the theoretical values of the product of liquid phase mass transfer coefficient with gas–liquid interfacial area ( k L A) T in the gas bubble dispersed phase involving the liquid jet were in good agreement with observed values. The performance of this absorber was comparable to that of other gas–liquid contacting devices.

Hydrodynamics of a spouted bed with an impermeable draft tube for binary particle systems

A spouted bed with an impermeable draft tube was employed to obtain fundamental data of binary mixtures of glass beads for both the operating conditions and the design factors. These data were compared with those for the coarser particle system only. From this view point, minimum spouting velocity, pressure drop, hold-up of solid particles within a draft tube, upward gas flow rate within the annulus and solids circulation rate were determined by changing the total gas flow rate and mass fraction of finer particles as operating parameters and by changing distance of entrainment zone and draft tube diameter as geometric parameters.

Flow characteristics of gas–liquid two phase plunging jet absorber–gas holdup and bubble penetration depth

A gas-liquid two phase plunging jet is formed through a gas sucking type multi-jet ejector nozzle. In this study, the effects of various conditions in the multi-jet ejector nozzle, the column diameter, and the liquid jet length on penetration depth of air bubbleslB and gas holdup hG in a gas-liquid two phase plunging jet absorber were studied experimentally. Consequently, empirical equations concerninglB and hG were obtained, respectively. These equations agree with the experimental data with an accuracy of ±20% forlB and ±25% for hG.