GAS-SOLIDS FLOW IN THE RISER OF A CIRCULATING FLUIDIZED-BED

A new approach to the modelling of gross gas-solids flow through the r iser in a circulating fluidized-bed system is proposed in this paper. This approach differs from the previous ones, which are Found to be th eoretically incorrect based on a fundamental analysis of the riser pro cess hydrodynamics. Starting from the basic principles, the new approa ch tackles the modelling problem from both energy and momentum balance perspectives. It also identifies that a riser may be operating in two different flow regimes: the entrainment regime and the dragging regim e. Experimental results from a compartmented dense-phase circulating f luidized bed, developed for a continuous coal combustion-gasification process, verified the existence of the two flow regimes.