This study modifies a defluidization time prediction model under the influence of agglomeration inhibition provided by the addition of Al into a fluidized bed system. Operational parameters, such as the Al/Na ratio, temperature, gas velocity, and the particle size of bed materials, were considered by the prediction model developed by Lin et al., and thermodynamic consideration of the Al–Na–Si reaction system revealed the agglomeration mechanism. An exponential decay of fN was found with the increase of the Al/Na ratio, and the data analysis gave a regression formula of fN=0.0601+0.4983∗exp [−4.4183∗(Al/Na ratio)], with an R2 of 0.9972. The simulation data generally match well with the experimental results, particularly at lower operation temperatures and Geldart B group's particles, with acceptable average errors of −8.4% and −4.9%, respectively. However, relatively poor matches were found in the cases with different gas velocities, a higher operation temperature (900°C), and a larger particle size (Geldart D group) of bed materials.