内循环流化床大颗粒运动特性实验

Large Solids Flow Characteristics in an Internally Circulating Fluidized Bed

内循环流化床能够有效组织颗粒在床内的运动,具有广泛的工业用途。采用荧光大颗粒示踪,运用图像处理法,在二维流化床实验台上,研究了流化风速、静止床层高度等参数对床内大颗粒的速度分布概率以及循环时间的影响。结果表明:提高流化风速和静止床层高度,循环口两侧差压增大,颗粒内循环流率增大,循环时间变短。颗粒横向和纵向速度分布概率的特征显著不同。在低速床中,颗粒纵向速度超过50%分布在负值区域,表现出明显的向下运动的特征。

The internally Circulating Fluidized Bed is widely used in industries due to its effective controlling of solids flow. The effects of gas velocity and static bed height on the solid velocity distribution,solid circulation rate and Averaged cycle time of solids were investigated in a twodimensional internally Circulating Fluidized Bed by tracking a fluorescent tracer and recording videos. It is found that with gas velocity and static bed height increased,the pressure drop across the circulating hole and the solid circulation rate increased,resulting in a reduction of the averaged cycle time of solids. Solid velocity distributions were different between x and y directions. In the bed with a lower gas velocity,more than 50% solids velocities were below zero,indicating a strong down flow of solids.