Abstract
To discuss the feasibility of the high velocity fluidized-bed (CFB) technology, brief reviews on the history of the development of CFB and on its fluidization behaviors are presented. It is also discussed the reasons why the circulating fluidized-bed boilers (CFBC) are appeared before the footlight recently. CFB is pronounced technology for the new boiler systems and also it has sufficient possibility to be applied on the new solid-gas contact systems. To support these technology, much more fundamental research works on the solid-gas multiphase system including CFB are required.