The flow characteristics of gas–solid two-phase flow in an inclined pipe

An inclined pipe is an important component in the industrial FCC(fluid catalytic cracking) units that transports the catalyst between the reactor and the regenerator. However, transport failures frequently occur in the inclined pipe because of the different behaviors of gas–solid flow patterns. In this research, the flow parameters of different flow patterns, including the static pressures, pressure gradients, and particle concentrations under the different particle mass flow rates (Gs) were measured and analyzed in an inclined pipe with 150 mm I.D. The Gs and the pressure gradient ranged from 35.43 to 640.71 kg/(m2·s), and from 0 to 2,500 Pa/m, respectively. The characteristic parameters suggested that dense-phase flow, transition packed-bed flow, packed-bed flow, and stratified flow may appear sequentially along the inclined pipe from inlet to outlet, which differs from the published model. The new fluid pattern model has successfully diagnosed the particle transport fault in a 3.0 Mt/a FCC unit. This study contributes to a better comprehension of the flow patterns in inclined pipes. © 2024 The Society of Powder Technology Japan.