Remarkable cyclonic and fluidized combustion regimes have prompted the integration of these two distinct combustion processes into a unique combustor. The possibility of combining these two air-solid phase flow hydrodynamics was investigated by performing experiments with a non-reactive combustor model, named a cyclonic fluidized bed combustor (psi-FBC). Air-rice husk flow visualization within psi-FBC clearly indicated vortex flow when air and rice husk descended along the model wall, while the air-rice husk movement within the entire space underneath the upper vortex ring was characterized by fluidization. The vortex rings and an intensive air curtain generated by the swirling flow of primary air with a high swirl number were the key parameters to promote fluidization, form a solid suspension layer and prevent solids from escaping from the cold psi-FBC model. The visual observations of swirling and recirculation solid flows agreed well with the results of parallel experiments with non-reacting air flow patterns. (C) 2007 Elsevier Ltd. All rights reserved.