Flow of dilute gas‐particle suspensions

Abstract

Abstract A semi‐empirical model of the radial segregation of solids in upward flow of dilute gas‐particle suspensions in riser systems is presented on the basis of a reduced form of the fundamental two‐phase flow governing equations and experimental evidence concerning the solids concentration at the wall. The following simple expression for the radial solids concentration profile is obtained: and is in agreement with experimental data over a wide range of operating conditions: superficial gas velocity from 1.4 to 15.3 m/s, riser diameter from 0.032 to 0.40 m, imposed solids flux from 6.60 to 207 kg/m 2 ·s, mean particle size from 32 to 120 μm and particle density from 1,000 to 3,500 kg/m 3 . The model confirms the existence of the core‐annulus flow structure in gas‐particle suspensions reported in riser reactors, circulating fluidized beds, and the freeboard of bubbling fluidized beds.