Experimental Study of Solids Holdups Inside Particle Clusters in CFB Risers

To investigate flow structure and solids holdups inside the particle clusters, time series of local solids concentration in two CFB risers were systematically measured by a reflective-type fiber-optic solids concentration probe and over a wide region of operation conditions. The two risers, both having 100 mm i.d., are 15.1 m and 10.5 m high, respectively, and the particles are FCC and sand. Analysis for the time series of local solids concentration indicates that the solids holdups inside clusters are clearly dependent on the local time-mean solids holdups, and there obviously exists a similarity between their radial profiles of the dimensionless solids holdups. Based on the experimental data of this work and other literatures, a correlation between the solids holdups inside cluster and the local time-mean solids holdups is presented.