An experimental investigation on solid acceleration length in the riser ofa long circulating fluidized bed

Systematic experimental work was conducted to investigate the solid acceler ation length in a 16 m long circulating fluidized bed riser with fluid crac king catalyst particles over a wide range of operating conditions. A more f easible method is proposed to determine the acceleration length from the me asured axial profiles of pressure gradient (or apparent solid holdup). With this new method and large amount of experimental data, a clear picture on the variation of the acceleration length with both solid circulating rate a nd superficial gas velocity is obtained. It is found that the acceleration length increases generally with increasing solid flow rate and/or decreasin g gas velocity. However, the trend in variation of the acceleration length with operating conditions are quite different in different operation ranges . Reasonable explanations are suggested for the observed variation patterns of acceleration length.