Particle Velocity Distribution and Its Prediction in a 14 m Two-Dimensional Circulating Fluidized Bed Riser

Abstract

Particle velocity (V p) is investigated comprehensively in a two-dimensional circulating fluidized bed (CFB) riser with a superficial gas velocity (U g) of 5–7 m/s and a solids circulation rate (G s) up to 500 kg/m2s which are similar to the industrial operating conditions. Results indicate that the lateral profile of V p is nonuniform showing roughly a “core-annulus” or parabolic trend with G s less than 300 kg/m2s, while it presents a uniform structure under relatively high solids loading conditions with G s of 500 kg/m2s. For axial distribution of V p, lower V p is near the riser bottom, and it gradually increases along the riser, indicating flow development. Fluctuation of the average particle velocity along the riser is more vigorous when G s is high up to 400 kg/m2s. Both axial and lateral particle velocities can be predicted using empirical correlations established in this work. Empirical equation to describe the relationship of V p against solids holdup (εs) works better for low G s. Based on the analysis, it may suggest different fluid mechanisms for low and high solids flux conditions.

Cluster Identification by a k-means Algorithm-Assisted Imaging Method in a Laboratory-Scale Circulating Fluidized Bed

“…The terminal velocity of FCC particles is 0.36 m/s. More details of the particle properties can be found in our previous work …”

“…More details of the particle properties can be found in our previous work. 46 During the experiments, one of the primary gas streams entered the bottom of the riser acting as the bulk gas flow to accelerate the particles, and the other entered the downer through the gas distributor form the top. For the operation of the riser, particles enter the riser bottom through the feeding pipe which connects with the riser and the storage tank and then accelerate up after contacting with the bulk gas flow.…”