To better understand the hydrodynamic behavior of an internally circulating fluidized bed,solids holdup in the down-comer(ε_(sD)),solids circulation rate(G_s) and gas bypassing fraction(from down-comer to riserγ_(DR),and from riser to down-comer γ_(RD)) were experimentally studied.The effects of gas velocities in the riser and in the down-comer(U_R and U_D),orifice diameter in the draft tube(d_(or)),and draft tube height(H_R) were investigated.Experimental results showed that increase of gas velocities led to increase in G_s and γ_(DR),and slight decrease in γ_(RD)-Larger orifice diameter on the draft tube led to higher ε_(sD),G_s and γ_(DR),but had insignificant influence on γ_(RD).With increasing draft tube height,both G_s and γ_(DR) first increased and then decreased,while γ_(RD) first decreased and then increased.Proposed correlations for predicting the hydrodynamic parameters agreed reasonably well with experimental values.
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