脉冲筛板萃取柱中连续相的轴向混合

Studies on the axial mixing of continuous phase in apulsed sieve-plate extraction column

通过示踪剂实验方法对38mm脉冲筛板萃取柱中连续相的轴向混合进行了研究。分别采用亚甲基蓝溶液和氯化钾溶液为示踪剂。实验过程中,首先采用"扰动-响应"技术实测了示踪剂的停留时间分布(RTD)曲线,然后依照轴向扩散模型(ADM)应用最小二乘法拟合求出连续相的轴向混合系数Ec,并分析了连续相表观流速、分散相表观流速、脉冲强度对于Ec的影响。实验结果表明,示踪剂浓度、径向取样位置和轴向取样位置对轴向混合系数Ec值的影响可以忽略,轴向混合系数Ec随着脉冲强度和两相表观流速的增加而增大。最后在本实验参数范围内,拟合出了连续相的轴向混合系数随操作参数变化的经验关系式,与实验结果对比,相对偏差在±20%以内。

In this paper,the axial mixing of continuous phase has been studied in a φ38mm standard pulsed sieve plate extraction column.Methylene blue solution and potassium chloride solution are adopted as the tracer respectively.The residence time distribution （RTD） curves have been measured through stimulus response technique,and the axial mixing coefficient is evaluated by the least squares fitting method in accordance with the axial dispersion model.The influence of the pulse intensity,continuous and dispersed phase superficial velocities on the axial mixing has been analyzed.The results showed that the influence of tracer solution concentration,radial sampling probe location and axial sampling probe location on the continuous phase axial mixing coefficient can be ignored.The axial mixing coefficient increases with the increase of the pulse intensity or the superficial velocities of two phases.Moreover,the empirical correlation of the axial mixing coefficient has been fitted; relative deviation is within ±20％ compared with experimental results.