Pressure Drop and Air Flow Rate in Spouted Bed of Unhulled Rice

Abstract

The spouted bed technique has been applied to the operations bringing fluids into contact with solid particles which are too coarse to fluidize. It was recognized that the spouted bed might be applicable to the dryer of the unhulled rice.
This paper presents the available data for designing of the spouted bed, using unhulled rice as solid materials and air as spouting medium, as follows:
(1) The desirable operations in the spouted bed in practice were obtained under the conditions; D_i/D_c=1/5-1/4, L_o/D_c=2-3. In this paper, pressure drop and air flow rate were discussed under these conditions, where D_i was the diameter of air inlet, D_c the diameter of spouted column, and L_o the height of the bed at the fixed state.
(2) ΔP_m/L_oγ_b depended not upon D_o/D_c but upon D_i/D_c, where ΔP_m was the maximum pressure drop in the spouted column and γ_b was the bulk specific-weight of the bed at fixed state.
(3) ΔP_m/L_oγ_b had any value ranging from 1.3 to 2.0. Here, L_oγ_b corresponds to the pressure drop in the fluidized bed.
(4) G_m/G_mf had any value ranging from 0.8 to 0.9. Here G_m is the air mass-velocity at the maximum pressure drop in the spouted column and G_mf is the minimum air mass-velocity required for fluidization.
(5) ΔP_s/L_oγ_b had any value ranging from 0.5 to 0.8. Here ΔP_s is the spouting pressure drop.
(6) G_s/G_mf had the value about 1.5. Here, G_s, a new concept presented in this paper, is minimum air mass-velocity for steady spouting.