On the Conditions of Fluidization of Grains

Abstract

The authors investigated the effect of various factors which determine the conditions of fluidization in fluidized bed, with air and grains such as soy bean, unhulled rice, brown rice, processed wheat and rape seed. Following results were obtained.
1. The minimum fluidization velocity u_mf may be shown by
u_mf={1/37.74⋅(u_m⋅ε_c)^1.9⋅ρ_s/(1-ε_c)^0.9}^0.59
2. The limit of the height of the bed in which slugging occurs (L_c/D_T)_sl. may be shown by
(L_c/D_T)_sl=0.374 (D_p⋅ρ_s)^-04⋅8
or (L_c/D_T)_sl=434.4 (u_ms)^-0⋅96
3. The height of fluidized bed L_f may be shown by
L_f=β(u/u_m)^1⋅12⋅L_c for u/u_m≤(u/u_m)₀
L_f=25.0(u/u_m)^3⋅56⋅L_c for u/u_m≥(u/u_m)₀
where (u/u_m)₀=(β/25.0)^0⋅41
and β is a constant, and datermined to be
6≤β≤8 in this study.
4. Nomenclture
D_T: diameter of pipe;
u_ms: theoretical terminal velocity;
u_m, D_p, ρ_s: terminal velocity, diamater and density of grain, respectivel;
L_c, ε_c: height and void fraction of static bed, respectively.