Comparison of macroscopic flow properties obtained by three methods of operation in a liquid–solid circulating fluidized bed

Experiments were conducted in a liquid–solid circulating fluidized bed (LSCFB) to study the flow regimes, operational instability, critical transitional velocity to circulating fluidized bed (CFB) regime, solids holdup and solids circulation rate by three experimental methods. The results indicate that the operational instabilities such as arch formation, liquid–solid separator blockage and solids return pipe blockage were observed in two of these methods at large primary and auxiliary liquid velocities. The critical transitional velocity that demarcates the expanded bed from CFB regime was observed to be different by these three methods. Each of these methods has its own merits and demerits in terms of operating range of CFB regime, solids holdup, solids circulation rate and application.