Axial flow structure at the varying superficial gas velocity in a downer reactor

Modeling coal pyrolysis in a cocurrent downer reactor

“…The increase in the solids velocity is the combined result of the resultant force, drag force and gravity. This trend can also be seen in the data reported by Deng, Liu, Wei, and Jin (2004). Fig.…”

Comparative study of gas–solids flow patterns inside novel multi-regime riser and conventional riser

“…Similarly, although the radial profiles of solids concentration and particle velocity in CFB downers are more uniform than those in the risers, and virtually no solids back-mixing near the wall, the overall solids concentration in the CFB downers is far less than the risers as a result of much higher particle velocity generated by the accelerating effect of gravity [10,11], and this further restricts CFB downers' application in processes demanding high solidsto-gas ratio and intensive gas-solids contact.…”

Study on the FCC Process in a Novel Riser−Downer−Coupling Reactor (II): Simulation and Hot Experiments

“…The axial distribution of solids fraction in the riser is described using the Li−Kwauk model, i.e., solids concentration changes from a dilute phase at the top gradually to a dense phase at the bottom with the voidage curve of S type or regressive S type . The downer reactor can be expressed using the axial flow structure under varying superficial gas velocity, by which distributions of voidage, gas, and particle velocities and pressure can be determined …”