Flow Properties of Fluid Beds

Ikeda pt al. (15, 110), investigating the effect of fines on bed expansion, pressure fluctuation, and discharge rate of particles from a 8-cm-i.d. fluid bed, found that bed expansion and discharge rate increase and pressure fluctuations decrease with increasing content of fines ( 44 /am). The range of particles smaller than 44 /am is called fines fraction its role has been summarized by Ikeda (12) as shown in Table IV. The desirable properties of fluidized particles utilized as catalyst were given by Ikeda (12) as 

The expansion of a gas-solid fluidized bed at gas rates between the minimum-fluidization velocity and the initial bubbling velocity was studied in 1966 by Davies and Richardson (D6). This homogeneous expansion of the bed is considerably larger when finer particles are fluidized. Several studies have been carried out on bed expansion (D6, D15, M41) on particle-particle forces and interactions (D14a, M6, R9), and on the flow rate of gases through beds (D6) under the condition of particulate fluidization. 

Effects of the Change of Weight Fraction of Particles Smaller Than 44 /im ( Fines Fraction ) (12) 

Load on catalyst recovery system becomes unstable, and instantaneous load on the system increases Pressure and temperature control becomes ditRcult 

Yield of products decreases because side reactions come to prevail. Occasionally, afterburning takes place 

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