Experimental study of local solid concentration distribution in a square gas-solid fluidized bed

In order to study the basic behaviors of local solid concentration in a square gas-solid fluidized bed reactor, the distributions of local solid concentrations on different axial levels in a 368 mm×368 mm square fluidized bed with FCC particles were measured. The results show that the distribution of local solid concentration in the cross-section of the square fluidized bed is non-uniform. The local solid concentration at center of the square reactor is lowest and increases gradually with the increase of distance from the center; near the wall of the reactor, the solid concentration reaches its maximum value. Under the lower superficial gas velocity, the distributions of local solid concentrations in different lateral directions are not axial symmetrical in the bed cross-section. With the increase of the superficial gas velocity, the distributions of local solid concentrations in the bed cross-section tend to be axial symmetrical in different directions. The transition from bubbling fluidization to turbulent fluidization is a process gradually extending from the bed center to the bed wall. The particle density distribution (PDD) curves show that, under the turbulent fluidization, the steady two-phase flow has been broken.