The pressure drop characteristics of T-abrupt exit of the riser were analyzed based on dynamic pressure data of gas-solids two-phase flow in a circulating fluidized bed equipment by using FCC catalyst particles

and varying the operation parameters and equipment dimensions. The pressure drop of T-abrupt exit changed linearly with inlet particle density

and quadratically with inlet gas velocity. It increased significantly with the decrease of outlet tube area of T-abrupt exit. Further

the pressure drop of T-abrupt exit decreased as blind tube length increased

but changed little above a specific length

because increased blind tube length changed the pressure distribution along the upper riser. As blind tube length increased

inlet pressure of T-abrupt exit decreased

hence pressure drop decreased. There was a negative pressure zone along the upper riser and blind tube

which constrained gas-solids two-phase flow in the riser. The longer the blind tube

the longer the negative pressure zone and the greater the constraint.