循环流化床气体返混及停留时间的分布

Backmixing and Residence Time Distribution of Gas in Circulating Fluidized Bed

本文采用脉冲示踪技术,研究了直径140 mm循环流化床内气体的返混特性及其停留时间分布规律,并通过一维轴向扩散模型,得到了气体轴向扩散系数。实验结果表明,在循环流态化条件下,气体轴向流动明显偏离于平推流,并且随操作气速增大或颗粒循环速率的减小,气体轴向返混程度减小。

The gas backmixing characteristics and residence time distribution in a riser of circulating fluidized bed with 140 mm i.d. were investigated by means of gas tracer technique. The gas dispersion coefficient was determined by one-dimensional dispersion model. The results show that the flow pattern of gas in circulating fluidized bed is quite different from plug flow, and the extent of gas backmixing decreases with increasing gas velocity and/or decreasing solid circulation rate.