液固萃取塔中尼龙6中己内酰胺的外部传质系数

External Mass Transfer Coefficient of Caprolactam in Nylon 6 in Liquid-Solid Extraction Tower

采用固定床半间歇萃取装置在工业生产温度与流速下研究了尼龙6颗粒中己内酰胺（CL）的液固传质过程,基于萃取过程中CL浓度在颗粒中呈现抛物线分布的假设,建立了液固传质过程的外部传质系数模型.结果表明,温度65~95℃和液相流速0.27~2.71 mm/s时,提高温度与流速均能显著加快CL的液固萃取.外部传质系数模型适用于描述无因次时间大于0.15的实验数据.将CL外部传质系数进行无因次量纲化,建立了舍伍德数（Sh）、施密特数（Sc）和雷诺数（Re）间的相互关系,可用于预测尼龙6工业萃取塔中的CL外部传质系数.

The liquid-solid extraction process of caprolactam（CL） in nylon 6 particles was investigated by packed bed semi-continuous experiments under the conditions of industrial interest. Based on the assumption that the CL concentration profile inside particles conformed to parabolic profile during the extraction, the external mass transfer coefficient model was developed. The results showed that in the range of temperature 65~95 and liquid velocity 0.27~2.71 mm/s, the ℃ liquid-solid extraction process of CL could be significantly accelerated by the increase of either temperature or liquid velocity. The external mass transfer coefficient model was adapted to reproduce the experimental data under the dimensionless time larger than 0.15. Through normalizing the external mass transfer coefficients, a correlation of Sh, Sc and Re, which could be used to predict the CL external mass transfer coefficient in the industrial extraction tower, was acquired.