Predicting Bed Voidage in Solid-Liquid Fluidization

抄録

Previously published solid-liquid fluidization data and new experimental data were correlated to develop an explicit expression for bed voidage, ε, in solid–liquid systems. Based on the observed deviation between the voidage predicted by the Richardson–Zaki¹⁸⁾ equation (ε_RZ) and the actual voidage, this new correlation assumes the form

ε = ε_PK + (1 – ε_PK)ε_RZ^A exp(B(1 – ε_RZ)

where A = 2.2n + 8d_P/D and B = 2.1n. ε_PK is the “packed” bed or the static bed voidage (i.e., ε when the superficial liquid veIocity, U_L, is zero), n is the Richardson–Zaki¹⁸⁾ exponent, and d_P/D is the particle diameter-to-column diameter ratio. A total of 811 data points were correlated with Reynolds numbers based on terminal velocity, Re_t, ranging from 0.7 to 3200. The correlation satisfactorily predicts voidage with a standard deviation of less than 5%.