Radial voidage variation in CFB risers

A new correlation for estimating local voidage in CFB risers is provided based on data obtained in a riser of diameter 76 mm and height 6 m using FCC particles at superficial gas velocities between 4 and 8 m/s and solids circulation fluxes up to 425 kg/m²·s. This equation also works well for a wide range of operating conditions and risers of larger size and for other particles. The correlation appears to have broader applicability than previous ones. It is especially useful for estimating the local voidage in the dense zone of CFB risers and CFB risers operating under the dense suspension upflow regime where few experimental data are currently available.