LOCAL HEAT-TRANSFER AND MODES OF PARTICLE MOTION AT A HORIZONTAL CYLINDRICAL SURFACE IN A CIRCULATING FLUIDIZED-BED

Experimental study on the local heat transfer characteristics around a heater rod installed horizontally in a circulating fluidized bed 4 m- high and 0.1 m-i. d. was carried out under fast fluidization condition s. Air and FCC catalyst particle were used as a gas-solids suspension. The heater rod was electrically heated with 10 mu m-thick nickrome fo il heater on a wooden base rod of 10 mm-o, d. In order to understand p article motion, a glass pipe was mounted to simulate the heater rod an d the particle motion on the surface of this glass pipe was observed f rom inside of the pipe using a borescope and CCD camera. The result sh owed that heat convection around a pipe is influenced by solid fractio n in the bed and particle motion on the heater surface, such as collis ion against the lower surface, formation of a stack on the upper surfa ce, and downflow along the wall caused by core-annulus flow. The corre lation between the mode of particle motion and the local heat transfer around a pipe is interpreted based on the results obtained.