【摘要】 分析了气泡塔结晶器熔融结晶过程中自熔体向晶层界面的热、质传递特征,建立了描述该过程晶层生长的稳态模型.在自熔体向晶层界面对流传热膜系数的计算中,将弹单元分为弹状气泡周围液膜区、尾迹区及液塞段3段,各段的平均对流传热膜系数不同.分别在表观气速0.04和0.08m/s下,用模型对己内酰胺晶层生长进行了计算,计算结果与实验结果基本吻合.更多还原

【Abstract】 Bubble column crystallizer is one of the most effective equipment used for melt crystallization. In this paper, the heat and mass transfer characteristics from the melt to the solid layer in the process of crystallization in bubble column crystallizer were analyzed. The steadystate model for the prediction of the solid layer growth in bubble column crystallizer was developed. The convective heat transfer coefficient at the solidmelt interface was calculated by dividing the slug unit into three different zones: the falling liquid film zone, the wake region and the developed liquid slug zone, each of which has a corresponding different coefficient value for heat transfer. The growth of solid layer of caprolactam in bubble column crystallizer at two different gas superficial velocities, i.e. 0.04 and 0.08 m/s, was predicted using the model and compared with the experiments, respectively. A good agreement is found between the predicted and the experimental data.更多还原