INFLUENCE OF TEMPERATURE ON SOLIDS FLUX DISTRIBUTION IN A CFB RISER

This paper presents an investigation of the solids flux distribution i n a 0.161 m ID circulating fluidized-bed riser, operating in temperatu re range 20-550 degrees C. The superficial gas velocity and the impose d solids flux were varied from 2.5 to 5 m s(-1) and from 2 to 60 kg m( -1) s(-1), respectively. For the operating conditions examined, the re duced solids flux, i.e. local solids flux divided by cross-sectional m ean solids flux, was insensitive to changes in the imposed solids flux over a wide range at a given superficial gas velocity. As temperature increased the mean suspension density decreased, whilst the reduced s olids flux profile became flatter and less parabolic in shape. Local f luctuations in solids flux were found to increase with increasing temp erature. Analysis of results suggests that the effect of temperature o n CFB hydrodynamics (e.g, the mean suspension density and the solids f lux profiles) is mainly due to the change in viscosity of the fluidizi ng gas.