Solid recycle characteristics through a conventional and a newly developed loop-seal (0.08 m i.d.) system are determined in a
circulating fluidized bed of FCC or silica sand particles. In the loop-seal developed here, gas was injected downward tangentially
to the wall of the loop-seal to increase solids mass flux with stable flow. For conventional loop-seal, solids mass fluxes increase
linearly with increasing aeration rate but it reaches a maximum value.At the same aeration rate with different aeration locations
(0.1 - 0.6 m) in a conventional loop-seal, a maximum solids mass flux is seen at a height to diameter ratio of 2.5. For the newly
developed loop-seal, mass fluxes ofFCCand sand particles are higher and more stable than in conventional loop-seal at the same
aeration rate. The solid mass fluxes obtained have been correlated with the aeration rate and Archimedes number.