Incipient fluidization characteristics of crushed oil shale

We have measured the gas velocity for incipient fluidization of crushed shale as a function of particle size, particle-size distribution, shale grade, crushing method and temperature. This velocity varied as the square of particle size for 0.0063- to 0.1-cm particles ano approximately as the square root of particle size for particles larger than 0.5 cm. We observed no regular dependence of this velocity upon shale grade. Slightly higher velocities were found for cone-crushed than For hammer-milled shale particles. For 0.0125 to 0.10-cm partic. es we found that raising the temperature to 450°C reduced the velocity by 28 percent from 20°C measurements. The harmonic mean of a mass-based particle-sze Distribution was found to be the particle size which gave the best: estimate of incipient fluidization velocity. The Zenz-Othmer graph predicts velocities three to five times higher than those observed. The Kunii-Levenspiel correlation predicted velocities 25 to 270 percent higher than observed at 20°C but was within experimental error for measurements at 450°C.