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

Particle velocity (Vp) is investigated comprehensively in a two-dimensional circulating fluidized bed (CFB) riser with a superficial gas velocity (Ug) of 5-7 m/s and a solids circulation rate (Gs) up to 500 kg/m2s which are similar to the industrial operating conditions. Results indicate that the lateral profile of Vp is nonuniform showing roughly a "core-annulus"or parabolic trend with Gs less than 300 kg/m2s, while it presents a uniform structure under relatively high solids loading conditions with Gs of 500 kg/m2s. For axial distribution of Vp, lower Vp 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 Gs 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 Vp against solids holdup (ϵs) works better for low Gs. Based on the analysis, it may suggest different fluid mechanisms for low and high solids flux conditions.