柱形和锥形移动床中气体的扩散特性

Gas Dispersion Behaviors in a Cylindrical and Conical Moving Bed

采用脉冲氦气体示踪技术研究了柱形和锥形移动床中气相的扩散特性,并与实验结果进行对比.结果表明,在主体流动区(0.11<h/H<0.89)中,柱形床径向气流基本接近平推流,而锥形床径向气流存在向上的速度分量,向上流动的气体一般约占10%.锥形床沿轴向气相流量分布不均匀.在下料影响区(h/H>0.89),柱形床会出现向下窜气的现象,而锥形床中向下窜气量降低40%～50%,气相径向流动更趋近平推流.根据径向气流在柱形和锥形移动床内的流动特点,用实验数据回归了气体浓度分布的无量纲经验关联式,计算值与实验值吻合较好.

The gas dispersion behavior in the cylindrical and conical moving bed was investigated/compared by using the helium gas tracing technique. The experimental results show that radial flow of cylindrical bed assumes a plug pattern while the axial gas distribution of conical bed was non-uniform in the main flowing zone（0.11h/H0.89）. Generally speaking, upward flow of gas is much accounted for about 10%. In the exit affected zone（h/H0.89）, the gas bypassing appears in the cylindrical moving bed and radial flow of conical bed tends to a plug pattern. Because the gas bypassing would be reduced by about 40%～50% in conical bed. According to the radial flow characteristics in the cylindrical and conical moving bed, furthermore, an empirical model for estimating the axial distribution of gas concentration was established based on the experimental data and the theoretical analysis, which agreed with the experimental data.